LOW TEMPERATURE OXIDATION OF CARBON MONOXIDE USING 
MICROFIBROUS ENTRAPPED CATALYSTS FOR  
FIRE ESCAPE MASK APPLICATION 
 
 
Mukund R. Karanjikar 
 
 
A Dissertation 
Submitted to 
the Graduate Faculty of 
Auburn University 
in Partial Fulfillment of the 
Requirements for the 
Degree of 
Doctor of Philosophy 
 
Auburn, Alabama 
August 8, 2005 
 iii
VITA 
 
 
 
          Mukund R Karanjikar, son of Ramchandra Karanjikar and Mangal Karanjikar was 
born on April 19, 1978. He received his secondary school certificate degree in March 
1993 and higher secondary school certificate degree in March 1995. In August 1995 he 
entered University of Mumbai (formerly University of Bombay) and graduated with a 
Bachelor of Chemical Engineering in May 1999. In June 1999, he started working for 
Rallis India Ltd., an agrochemical manufacturing company for a span of two years. In 
August 2001, he entered Graduate School of Auburn University, Auburn AL for 
Doctorate of Philosophy. 
    
 iv
LOW TEMPERATURE OXIDATION OF CARBON MONOXIDE USING 
MICROFIBROUS ENTRAPPED CATALYSTS FOR  
FIRE ESCAPE MASK APPLICATION 
 
Mukund R Karanjikar 
Doctor of Philosophy, August 8, 2005 
(B.Chem. Engg., University of Mumbai 1999) 
 
224 Typed Pages 
Directed by Bruce J. Tatarchuk 
The prime reason for life casualties in fire is not the fire itself but poisoning 
caused by presence of carbon monoxide. It has been reported by American Medical 
Association that CO causes about 2100 deaths per year and about 10000 physical injuries 
in United States. Carbon monoxide can be lethal at a concentration of more than 400 
ppm. Depending upon cases, fire can contain as high as 3600 ppm of carbon monoxide.  
This dissertation presents results of R&D efforts to develop a thin, low pressure 
drop, high face velocity, catalyst substrate capable of meeting various CO reduction 
standards for Respiratory Protection Applications including CBRN (recently adapted by 
NIOSH), EN 403 (European Union) and ANSI / ISEA 110-2003 (ANSI). 
 
 v
The goals for this work were set based on performance of current commercial 
products in the domain and new and emerging standards for testing of fire escape masks. 
The current products meet well existent EN 403 standards, which corresponds to removal 
of 2500 ppm CO down to 200 ppm, for a flow rate of 30 LPM for minimum 15 minutes. 
The new and emerging standards are more stringent and pose a significant challenge for 
development. Also, current commercial products have been designed based on packed 
bed configuration of catalyst, hence suffer pressure drop. 
The effort here utilizes a unique approach known as Microfibrous Entrapment. 
Resultant materials are a composite structure wherein a micron sized powder of the 
catalyst (ca. 10-250 micron in diameter) is entrapped within a sinter-locked mesh of 
metal, polymer or ceramic fibers (ca. 2 ? 20 micron in diameter). These materials are 
highly advantageous for applications where high contacting efficiency is required. The 
approach also provides a number of other advantages such as high thermal conductivity, 
low pressure drop, and high mechanical & structural stability. 
In this work, a promoted and proprietary Pt/Al
2
O
3
 (150 ? 250 micron) has been 
entrapped into a nickel microfibrous mesh consisting of 2-3 vol% of 4 and 8 micron 
diameter fibers. The catalyst has been tested in a tubular reactor. Various tests were 
performed according to all the test protocols. Non-linear dynamics of CO oxidation, 
hysteresis effects, effect of moisture, kinetic oscillations phenomenon are also discussed. 
Analysis of commercial products was done to compare this technology with existing 
ones. The results show that this technology utilized 10 times lower quantity of catalyst, 
has a four-fold lower pressure drop and weighs ten times lighter compared to commercial 
products. Technology transfer has been detailed to test the scalability of the process.   
 vi
ACKNOWLEDGEMENTS 
 
I would like to express my sincere gratitude towards Dr. Bruce Tatarchuk for his 
kind financial and moral support. I would also like to acknowledge Dr. James Guin, Dr. 
Chris Roberts, and Dr. Daniel Harris for serving on my committee. Special thanks to Dr. 
Christopher Roy for serving as outside reader for this dissertation. I express my 
appreciation towards all the members of Center for Microfibrous Materials 
Manufacturing for their kind help, especially Mr. Dwight Cahela. Many thanks are due to 
Mr. Joe Aderholdt and Mr. Wendell Sandler for timely help on fabrication.  
Special thanks are due to Dr. Amit Mitra for offering great help, while I was 
making important career decisions. Thanks are due to Dr. Said Elnashaie for special 
exposure towards chemical engineering and personal help. I shall like to express my deep 
appreciation to Tamara and other members of LeadershipAU. Special thanks are due to 
my fellow Auburnites; Rushabh, Bhavin, Nimir, Aziz, BK, Eric, Vitaly, Philip, Ranjit 
and Dan. 
I would like to express my deepest gratitude towards my parents; everything 
always seemed easy when they explained it. My younger brother, Vikas is always a 
source of inspiration for me, special thanks to him. 
Very many thanks to friends; Lakhan, Prashant, Sanjeev and Shailendra, without 
whom, it is impossible for me to visualize a life.  
 vii
Style manual or journal used: American Chemical Society Style Guide: A Manual 
for Authors and Editors  
 
Computer software used: Microsoft Word
TABLE OF CONTENTS 
 
LIST OF TABLES xiii 
LIST OF FIGURES  
xiv 
CHAPTER I: INTRODUCTION AND LITERATURE REVIEW 
 
1 
 I.1   Motivation 1 
 I.2   Introduction 2 
        I.3 Importance of Carbon Monoxide Removal for Direct Human 
Application 
3 
        I.4 History of Breathing Apparatus and Gas Mask Development for 
Protection from Irrespirable Gases 
3 
 I.5 Types of Respiratory Protection System 6 
 I.6 Testing standards and Test Protocols 7 
  I.6.1    EN 403 standards details 7 
  I.6.2 NIOSH Standards 8 
  I.6.3    ANSI/ISEA 110-2003 Standards 10 
 I.7 Current status of Escape Respirators 11 
 I.8 Carbon Monoxide Oxidation Catalysts 14 
 I.9 Methods of Catalyst Preparation 24 
  I.9.1    Precipitation Method 24 
  I.9.2 Impregnation Method 25 
 I.10 Catalyst Treatment Steps 25 
  I.10.1 Calcination 25 
  I.10.2 Reduction to the Metal 26 
 I.11 Catalyst Characterizations 27 
  I.11.1   Measurement of Surface Area 27 
  I.11.2  Specific Area by Selective Chemisorption 27 
  I.11.3  Pore Size Distribution 28 
  I.11.4  Selected Instrumental Methods 28 
  I.11.5    Calorimetry 30 
  I.11.6  Gravimetric Methods 30 
 I.12 Microfiber Based Composite Materials 31 
  I.12.1  Wet ? lay Process/ Sintering Process 31 
 
 viii
  I.12.2  Alternate Materials of Manufacturing  32 
 I.13 Applications of Microfiber Composite Materials 35 
  I.13.1  Microfibrous Entrapped Catalysts and Sorbents 35 
  I.13.2  Microfibrous Metallic Filters 35 
  I.13.3  Microfibrous Entrapped Electrocatalysts and Faradaic 
Materials 
35 
CHAPTER II: EXPERIMENTAL 36 
 II.1 Catalyst Preparation 36 
  II.1.1 Incipient Wetness Procedure 37 
  II.1.2 Co-precipitation Method 38 
 II.2 Details of Chemicals Used 39 
 II.3 Experimental Apparatus 40 
 II.4 Details of Instruments and Equipments used  44 
  II.4.1 Experimental Conditions 45 
 II.5 Pressure Drop Measurements 45 
 II.6 Apparatus for Commercial Product Testing 46 
 II.7 Analytical Section 47 
  II.7.1 Measurement of Inlet CO Concentration 47 
  II.7.2 Measurement of Relative Humidity 47 
  II.7.3 CO Detection and Datalog 47 
CHAPTER III RESULTS AND DISCUSSION 50 
 III.1 Catalyst Screening Tests 50 
  III.1.1    Gold Based Catalysts 50 
  III.1.2   Platinum Based Catalysts 57 
  III.1.3   Miscellaneous Catalysts 60 
  III.1.4   Commercial Catalyst and Sorbent 62 
 III.2 Catalyst Selection 63 
 III.3 Effect of Catalyst Making Process & Composition on the 
Performance of Pt/SiO
2
64 
  III.3.1   Effect of Promoter 64 
  III.3.2   Effect of Promoter on Activity of Pt/Al
2
O
3
65 
  III.3.3   Comparison between Different Promoters 67 
 III.4 Effect of Operating Conditions on Behavior of Pt/Mn/SiO
2
68 
  III.4.1   Effect of Temperature 68 
  III.4.2   Effect of Inlet CO Concentration 70 
  III.4.3   Effect of Promoter Loading 73 
 III.5 Catalyst Activity Details of Pt/Mn/SiO
2
 to comply with EN 403 76 
 ix
  III.5.1   Effect of GHSV 76 
 III.6 Intermittent Goal Setting 79 
 III.7 Effect of Face Velocity on Activity of Pt/Mn/SiO
2
81 
 III.8 Testing of Pt/Co/Al
2
O
3 
for Meeting different Test Protocols 86 
  III.8.1   EN403 86 
 III.9 Multiple Steady States in CO Oxidation 92 
  III.9.1   Investigations of Multiplicity in Low Temperature CO 
Oxidation 
96 
  III.9.2   Hysteresis Effects 99 
 III.10 Effect of Moisture 104 
  III.10.1  Hysteresis under Dry Conditions 105 
  III.10.2  Effect of Moisture on Hysteresis 106 
  III.10.3  Effect of Moisture on Pt/Mn/SiO
2
107 
  III.10.4  Water Promotion Effect of CO oxidation on Promoted 
Pt/Al
2
O
3
113 
 III.11 Self-sustained Oscillations 114 
 III.12 Comparison of Same Particle Size Catalyst in Packed and 
Microfibrous Entrapped Configuration 
118 
CHAPTER IV: ANALYSIS OF COMMERCIAL PRODUCTS 123 
 IV.1 Commercial Product I: Drager? Parat C? Details 124 
 IV.2 Commercial Product II : Essex? plus 10? Details 127 
 IV.3 Commercial Product III: Sundstrom? SR 77? Details 131 
 IV.4 Commercial Product Testing 132 
  IV.4.1  Testing of Drager? Canister 132 
  IV.4.2  Testing of Essex ? Monolith 138 
CHAPTER V: TECHNOLOGY TRANSFER 144 
 V.1 Accelerated Aging Tests 146 
 V.2 Pressure Drop Measurements 152 
 V.3 Process Analysis 153 
  V.3.1   Wet-lay  155 
  V.3.2   Drying 155 
  V.3.3   Pre-oxidation 155 
  V.3.4   Sintering 155 
  V.3.5   Impregnation I 156 
  V.3.6    Drying II 156 
  V.3.7   Calcination I 156 
  V.3.8    Impregnation II 156 
  V.3.9   Drying III 157 
 x
  V.3.10   Calcination II 157 
  V.3.11    Reduction 157 
 V.4 Identification of Rate-determining Stages 158 
  V.4.1    Cost of Catalyst  158 
  V.4.2  Batch Cycle Time Reduction 161 
  V.4.3 Use of Continues Sintering Furnace 162 
  V.4.4  Elimination of Stages 162 
CHAPTER VI: CONCLUSION AND RECOMMENDATIONS FOR FUTURE  
                          WORK 
165 
 VI.1 Conclusion 165 
  VI.1.1  Catalyst 165 
  VI.1.2  Process 166 
  VI.1.3  Improvement in Existing Products 166 
  VI.1.4   Technology Transfer: Cost Issue 167 
 VI.2 Recommendations for Future Work 168 
  VI.2.1  Further Reduction is Catalyst Loading 168 
  VI.2.2  Smooth and Integrated Manufacturing Processes 170 
  VI.2.3  Customizing Process to fit Available Hardware 170 
  VI.2.4  Alternate Carrier Material 170 
  VI.2.5  Integration of MiniCOT with other Sorbents  171 
  VI.2.6  Packaging 172 
  VI.2.7   Computational Fluid Dynamic and Residence Time      
             Distribution Studies in Microfibrous Beds 
172 
  VI.2.8   Heat Transfer Experiments 173 
REFERENCES 174
APPENDICES 179
 A QRAE? Data Sample 180 
 B Test Results for Various Standards 185 
 C Adiabatic Flame Temperature Calculation 201 
 D Preliminary Results from SEM/EDS 203 
 
 
 xi
LIST OF TABLES 
 
 
Table 1.1 EN 403 Standards Details 8 
Table 1.2 NIOSH Standards Details 8 
Table 1.3 Other Gas Requirements for ANSI/ISEA 110-2003 10 
Table 1.4 Description of Parat C? and SR 77? 12 
Table 2.1 List of Chemicals used for Catalyst Preparation 39 
Table 2.2 List of Equipments/Instruments used for CO Oxidation Set up 44 
Table 3.1 Results of Gold Based Catalysts Tests 56 
Table 3.2 Results of Platinum Based Catalysts Tests 57 
Table 3.3 Results of Miscellaneous Catalysts Tests 60 
Table 3.4 Gas Life Corresponding to GHSV 78 
Table 3.5 Research Goals Based on Intermediate Findings and Survey 79 
Table 3.6 List of Operating Variables and Parameters with Range 80 
Table 4.1 Details of Parat C? 124 
Table 4.2 Technical Details of Essex Plus 10? 130 
Table 4.3 Product Details of SR 77? 131 
Table 4.4 Comparison of MiniCOT with Commercial Products 143 
Table 5.1 Material Take-off for Wet-lay  155 
Table 5.2 Material Take-off for Impregnation I 156 
Table 5.3 Material Take-off for Impregnation II 157 
Table 5.4 Cost Calculation for Platinum 158 
Table 5.5 Costing of Materials after Initial Response from Johnson 
Matthey? 
159 
Table 5.6 Weight Loss Comparison 161 
Table 6.1 Other Gas Requirements for EN 403 171 
 
 xii
LIST OF FIGURES 
 
Figure 1.1 The All Service Gas Mask  5 
Figure 1.2 Schematic of Fire Escape Mask on a Manikin  11 
Figure 1.3 Sundstrom? SR77? on a Manikin 13 
Figure 1.4 Drager? Parat C? Done by a Model 13 
Figure 1.5 SEM Image of 4 ?m Nickel Fiber Mesh 31 
Figure 1.6 Polymer Fiber Entrapped Support 33 
Figure 1.7 Ceramic fiber Entrapped 150 -250 Micron SiO
2
34 
Figure 2.1 Experimental Apparatus for Catalyst Screening 41 
Figure 2.2 Catalyst Testing Reactor  42 
Figure 2.3 Schematic of Pressure Drop Measurement Apparatus  43 
Figure 2.4 Schematic of Drager? Canister Testing Reactor 46 
Figure 2.5 Schematic of plus 10? Monolith Test Reactor 46 
Figure 3.1 Activity Tests of Au/MnOx Catalysts 53 
Figure 3.2 Activity Tests of Supported Gold Catalysts 55 
Figure 3.3 Activity Tests of Au/TiO
2
 Catalyst 56 
Figure 3.4 Activity Tests of Pt Based Supported Catalysts 58 
Figure 3.5 Activity Tests of Platinum Based Titania Supported Catalysts 59 
Figure 3.6 Activity Tests of Pd/Ce/Titania, Cu/Ceria and Ru-hopcalite 61 
Figure 3.7 Activity Tests of Commercially Available CuCl adsorbent and 
Hopcalite Catalyst 
62 
Figure 3.8 Comparison between Promoted and Un-promoted Pt/silica Catalysts 64 
Figure 3.9 Comparison between Promoted and Un-promoted Pt/Al
2
O
3
 catalysts 65 
Figure 3.10 Comparison of Various Transition Metal Promoters for Pt/SiO
2
 
Catalyst 
67 
 
 xiii
Figure 3.11 Effect of Operating Temperature on the Performance of Pt/Mn/SiO
2
  69 
Figure 3.12 Effect of Inlet CO Concentration on the Performance of Pt/Mn/SiO
2
  71 
Figure 3.13 Effect of Inlet CO Concentration on the Performance of Pt/Mn/SiO
2
  72 
Figure 3.14 Effect of Manganese Concentration on Pt/Mn/SiO
2
 Performance 73 
Figure 3.15 Effect of Support on Performance of Pt Catalysts 75 
Figure 3.16 Effect of GHSV on the Performance of Pt/Mn/SiO
2
 Catalyst 77 
Figure 3.17 Effect of Face Velocity on Catalyst Activity (Pt/Mn/SiO
2
) 81 
Figure 3.18 Activity Tests of Pt/Mn/SiO
2
82 
Figure 3.19 Effect of Inlet CO Concentration on Activity of Pt/Mn/SiO
2
83 
Figure 3.20 Effect of Face Velocity on Activity of Pt/Mn/SiO
2
84 
Figure 3.21 Effect of Bed Depth on Activity of Pt/Mn/SiO
2
85 
Figure 3.22 Catalyst Test for EN 403 (2500) 87 
Figure 3.23 Catalyst Test for EN 403 (5000) 88 
Figure 3.24 Catalyst Test for EN 403 (7500) 89 
Figure 3.25 Catalyst Test for EN 403 (10000) 90 
Figure 3.26 Adiabatic Temperature Rise for CO Oxidation Reaction 91 
Figure 3.27 Schematic Representation of Heat Generation and Heat Removal 
Curves as Functions of Inlet Temperature 
94 
Figure 3.28 Cross Section of the Bifurcation Set in the Plane of Gas 
Temperature and CO Feed Volume Fraction 
96 
Figure 3.29 Hysteresis Phenomenon in Low Temperature Oxidation of CO 99 
Figure 3.30 Steady State Temperature Hysteresis 102 
Figure 3.31 Hysteresis Phenomenon in Absence of moisture 105 
Figure 3.32 Effect of moisture on Hysteresis 106 
Figure 3.33 Effect of Moisture on CO Oxidation Process - Reversible Nature of 
Activity 
107 
Figure 3.34 Effect of Moisture on Catalyst Activity 109 
Figure 3.35 Self-sustained Oscillations in CO Oxidation 114 
Figure 3.36 Schematic of Different Bed Configurations  119 
Figure 3.37 Comparison of Catalyst Activity for Different Bed Configurations 120 
 xiv
Figure 4.1 Drager? Escape Mask Done 125 
Figure 4.2 Drager? Canister 126 
Figure 4.3 Drager? Canister ? Opened 126 
Figure 4.4 Essex Plus 10? Mask Done 127 
Figure 4.5 Essex? Canister Front View 128 
Figure 4.6 Essex? canister back side 128 
Figure 4.7 Carbon Monoxide Oxidation Monolith from Essex plus10? 129 
Figure 4.8 Drager Parat C? Test for EN 403 132 
Figure 4.9 Drager Parat C? Test for EN 403 133 
Figure 4.10 Drager Parat C? Test for CBRN General 135 
Figure 4.11 Drager Parat C? Test for ANSI 110-2003 #6 136 
Figure 4.12 Essex? Monolith Test for EN 403 138 
Figure 4.13 Essex? Monolith Test for ANSI #6 139 
Figure 4.14 Essex? Monolith Test for CBRN General Category 141 
Figure 4.15 Essex? Monolith Test for Inspired Air Temperature 142 
Figure 5.1 Comparison of Catalyst activity with Aged catalyst in Presence of 
TEDA/C, at 70
0
C for 48 hrs 
146 
Figure 5.2 Comparison of Catalyst Activity with Aged Catalyst in Presence of 
URC, at 70
0
C for 48 hrs 
148 
Figure 5.3 Comparison of Catalyst Activity with Aged Catalyst in Presence of 
ASZM/TEDA, at 22
0
C for 48 hrs 
149 
Figure 5.4 Comparison of Fresh Catalyst Activity with Aged Catalyst at 70
0
C  150 
Figure 5.5 Pressure Drop Through MiniCOT Catalyst as a Function of Face 
Velocity for Various Bed Thicknesses 
152 
Figure 5.6 Process Flow Diagram of Catalyst Preparation 154 
Figure 5.7 Testing of Catalyst after Elimination of Pre-Ox ? Sample I 163 
Figure 5.8 Testing of Catalyst after Elimination of Pre-Ox ? Sample II 164 
 
 xv
CHAPTER I 
INTRODUCTION AND LITERATURE REVIEW 
 
I.1 Motivation: 
Motivation of the research here is to be able to develop suitable microfibrous 
entrapped catalysts for low temperature oxidation of carbon monoxide. The research 
under consideration is applicable for developing respiratory protection systems for 
military, mining and space devices. It also has applications in orbiting closed cycle CO
2
 
lasers used for weather monitoring and other remote sensing applications. The catalyst 
can also be incorporated into fuel cell filter for protecting cathode from CO that can be 
present in the ambient air. This can be mainly applicable for fuel cell vehicles. The CO 
content on the roads can be up to 40 ppm. This concentration is sufficient to deactivate 
the fuel cell catalyst. Hence this catalyst can also be employed to protect the cathode. 
A special consideration has been given to the PPE (personal protective equipment) 
application. This particular catalyst can be incorporated into a fire escape mask to oxidize 
carbon monoxide generated in fire. 
 
 1
I.2 Introduction:  
It has been long known that removal of carbon monoxide is a difficult task. The 
reason why carbon monoxide removal has been found to be difficult lies in its physical 
and chemical properties. Due to its low boiling point and critical temperature, adequate 
adsorption at ordinary temperature is not possible. Due to its very low solubility in all 
solvents makes it impossible to be removed by physical absorption under any condition. 
Chemically CO is very inert at room temperature. The only known means so far is to 
oxidize carbon monoxide by means of a very powerful oxidizing agent such as platinum, 
palladium etc. Due to many important applications of low temperature carbon monoxide 
oxidation process, it has received considerable attention over a period of time. Moreover 
the simplistic appearance of the reaction, yet complex behavior observed in this reaction, 
became subject of investigations. The reaction has significant applications in control of 
emission in automotive exhaust gases, environmental clean up and a gamut of industrial 
applications of significant economic importance. The reaction can be written as follows: 
CO + 0.5O
2
 ? CO
2
Many catalysts which are active for this process under different conditions are very well 
known. There still exists a need for developing a better catalyst that would be active for 
longer time and would be tolerant to moisture and impurities in reacting gases. Moreover 
effective contacting pattern between the catalyst surface and reacting gases always plays 
a key role in catalytic reactions. Microfibrous materials are a means of better contacting 
efficiency as smaller size of catalyst particles can be used at lower pressure drop.  
 2
I.3  Importance of Carbon Monoxide Removal for Direct Human Application: 
As it is well known, the main cause of life casualties in fire is Carbon monoxide 
poisoning rather than the fire itself. Carbon monoxide is often referred to as the ?Silent 
Killer?. Carbon monoxide causes about 2100 deaths per year and about 10000 physical 
injuries [1.1]. Carbon monoxide can be lethal at a concentration of more than 400 ppm. 
Depending upon cases, fire can contain as high as 3600 ppm of carbon monoxide. Other 
places where it is possible to get poisoned by carbon monoxide are, ship boiler rooms due 
to defective ventilation, fires below deck in and out, manufacture of power and 
illuminating gas, coal mining, certain classes of copper mining, wherever explosives are 
being used in enclosed spaces, leaky flues, exhaust gases from explosive engines and 
places where coal fires are employed in case of improper ventilation. The catalyst 
developed here can be very effective to remove CO from the breathing air by 
incorporating it into gas mask or breathing apparatus. 
 
I.4  History of Breathing Apparatus and Gas Mask Development for Protection 
from Irrespirable Gases [1.2]: 
The history of oxygen breathing apparatus began in 1853 [1.3]. The apparatus was 
developed by Prof. Schwann as part of an academic competition at Academie Royale 
Belgique. The machine looked similar to those in use today. In late 1800s Fluess 
apparatus was developed in England by Prof. H.A. Fleuss. In 1903, an early type of 
draeger apparatus appeared in Germany. In the United States, mining companies were the 
first ones to recognize the need of breathing apparatus. Philadelphia & Reading Coal & 
Iron Co. of Pennsylvania and Anaconda Copper Mining Co. of Montana were the first 
 3
ones to provide breathing machines as rescue apparati in their mines in 1907. The United 
States investigated cause of casualties in mining operations, as a part of which the Bureau 
of Mines came into being in 1910. The bureau took-up the development of breathing 
apparatus. Two early American types developed were Gibbs and Paul. The bureau also 
approved Fleuss-Davis Apparatus developed in England. Due to Bureau?s experience 
with breathing apparatus development, they were called upon in World War I to direct 
the development of Military Gas Mask. Few years later the research was transferred to 
Research Division of Chemical Warfare Service. It had long been believed that carbon 
monoxide could be used as chemical warfare agent. Hence it was important to 
incorporate materials that would provide protection against carbon monoxide. After 
World War I, Bureau of Mines carried on investigations to develop gas mask that would 
be suitable for industrial uses where poisonous gases could be sometimes encountered. 
The very first escape category mask that bureau of mines came up with was, the 
?Universal Gas Mask? [1.4]. The universal gas mask did not supply oxygen and was of 
the gas purification type. It contained following different adsorbents and catalysts for gas 
purification purpose: 
i. Activated charcoal for removing organic vapors 
ii. Caustic soda or pumice stones for acid gas removal 
iii. Fused calcium chloride to remove water vapor so that hopcalite catalyst 
(susceptible to poisoning) does not deactivate 
iv. Hopcalite catalyst for removing carbon monoxide by direct oxidation 
v. Silica gel for removing ammonia 
 4
vi. Filters of cotton wool to remove suspended particulate matter such as dust and 
mists 
The year after that the Bureau introduced ?The All Service Gas Mask? [1.2]. Figure 
1.1 shows the details of this mask.  
 
Absorbent cotton filter .25 in thick between wire screens
Fused calcium chloride 160 cc
Hopcalite 330 CC
Fused calcium chloride 300 CC
Pumice impregnated with anhydrous calcium chloride, 85 cc
Absorbent cotton filter .25 in thick between wire screens
Activated charcoal impregnated with copper sulfate 660 CC
Dome of wire screen covered with Turkish toweling
Heavy wire screen
 
Figure 1.1: The All Service Gas Mask 
As seen in figure this canister does not have the silica gel layer for ammonia 
removal. Instead of silica, the activated charcoal was impregnated with copper sulfate to 
remove ammonia. Copper sulfate reacts with ammonia to form ammonium copper sulfate.  
The canister rested on wearer?s chest with a hose connected to the face-piece. The total 
volume of the canister was 1720-1750 cc. 
This development led to different types of masks and breathing apparatus available on the 
market today.  
 5
 
I.5  Types of Respiratory Protection System: 
OSHA (Occupational Safety and Health Administration) Respiratory Protection 
Standard 29 CFR 1910.134 defines following different classes of respiratory protection 
systems. 
 
1. Filtering Face-piece (Dust Mask) 
A negative pressure particulate respirator with a filter as an integral part of the face-piece 
or with the entire face-piece composed of the filtering medium. 
 
2. Air-Purifying Respirator (APR) 
It is a respirator with an air-purifying filter, cartridge, or canister that removes specific air 
contaminants by passing ambient air through the air-purifying element.  
a. Powered Air-Purifying Respirator (PAPR) 
It is an air-purifying respirator that uses a blower to force the ambient air 
through air-purifying elements to the inlet covering. 
 
3. Atmosphere-Supplying Respirator 
a. Self-contained Breathing Apparatus 
SCBA is an atmosphere-supplying respirator for which the breathing air source is 
designed to be carried by the user. These are used in oxygen deficiency type of 
environments or any situation that is IDLH (Immediately Dangerous to Life or Health) or 
 6
can become IDLH or any environment that has unknown environment both in terms of 
levels and types of contaminants. 
b. Supplied Air Respirators 
It is an atmosphere-supplying respirator for which the source of breathing air is not 
designed to be carried by the user. It is also called airline respirator. 
 
4. Escape Only Respirator 
A respirator intended to be used only for emergency exit. For example in a building on 
fire situation escape respirators with appropriate purifying materials in the canister of the 
mask can be used for escape purpose. 
 
I.6  Testing standards and Test Protocols 
For suitability of escape only respirators, European Standards Institute [1.5], 
NIOSH (National Institute of Occupational Safety and Health) [1.6] and ANSI (American 
National Standards Institute)/ISEA (International Safety Equipment Association) [1.7] 
have published different testing standards that these have to comply in order to be 
suitable for commercial use. 
 
I.6.1  EN 403 Standards for Escape mask application 
Table 1.1 shows the details of European EN 403 standards. These standards were 
proposed and accepted by European Union in 1993. Since then, America also followed 
the same standards. Recently new standards are being proposed. 
Table 1.1: EN 403 Standards Details 
 7
Test Agent Test gas Conc. In air (ppm) Breakthrough Conc. (ppm) 
Propenal (acrolein) 100 10.5 
Hydrogen Chloride (HCl) 1000 5 
Hydrogen Cyanide 400 10 
Carbon Monoxide 2500 200
a
a
: Time weighted average over 10 min.  
 
I.6.2 NIOSH Standards 
NIOSH standards were published in March 2003 as attachment A to CFR 42.84. 
Table 1.2 lists the details of NIOSH CBRN (Chemical, Biological, Radioactive and 
nuclear) with CO standards.  
Table 1.2: NIOSH Standards Details 
Test Agent Test gas Conc. In air (ppm) Breakthrough Conc. (ppm) 
Ammonia 1250 25 
Cyanogen Chloride 150 2 
Cyclohexane 1300 10 
Formaldehyde 250 10 
Hydrogen Cyanide 470 10 
Hydrogen Sulfide 500 30 
Nitrogen Dioxide 100 1 
Phosgene 125 1.25 
Phosphine 150 0.5
 8
Test Agent Test gas Conc. In air (ppm) Breakthrough Conc. (ppm) 
Sulfur Dioxide 750 5 
Carbon Monoxide
c
3600 402.5
b
b
: Time weighed average over the one time use of canister 
c
: For a flow rate of 64 LPM (equivalent to breathing flow rate) 
The respirators would be evaluated under following conditions: 
a. Three respirators to be tested at 64 ? 10 LPM continuous airflow at 89 to 95% 
relative humidity at 25 ? 3
0
C. 
b. Three respirators to be tested at 64 ? 10 LPM continuous airflow at 89 to 95% 
relative humidity at 0 ? 2.5
0
C. 
Additional Tests for Carbon Monoxide: 
Service Life Testing: 
- For an inlet concentration of 3600 ppm and flow rate of 110 LPM, the canister 
should be able to remove CO down to 402.5 ppm average for at least 5 minutes 
Inspired Air Temperature: 
- For an inlet concentration of 1200 ppm, outlet concentration should always be 
less than 10 ppm, wherein the temperature does not exceed 46 
0
C. 
Specific Category Tests: 
- The inlet concentration of 6000 ppm of CO to be reduced to 402.5 time weighted 
over the service period 
Service Life Test: 
- For an inlet concentration of 6000 ppm and flow rate of 110 LPM, the canister 
should be able to remove CO down to 402.5 ppm average for at least 5 minutes 
 9
I.6.3 ANSI/ISEA 110-2003 Standards 
American National Standards Institute, in collaboration with International Safety 
Equipment Association has proposed a set of standards for fire escape application. There 
are seven different categories. Category number six and seven are applicable to Carbon 
Monoxide removal. 
I.6.3.1 ANSI/ISEA 110-2003 #6: 
The mask should be active minimum for 15 minutes while removing 3090 ppm 
CO down to less than 200 ppm instantaneous at room temperature and 90% relative 
humidity of the feed. 
I.6.3.2 ANSI/ISEA 110-2003 #7: 
The mask should be active minimum for 15 minutes while removing 5150 ppm 
CO down to less than 200 ppm instantaneous at room temperature as well as zero deg C, 
and 90% relative humidity of the feed. Table 1.3 shows the details of other gas 
requirements for ANSI/ISEA 110-2003 standards. 
Table 1.3: Other Gas Requirements for ANSI/ISEA 110-2003 
Test Agent Test gas Conc. In air (ppm) Breakthrough Conc. (ppm) 
Propenal (acrolein) 100 0.5 
Hydrogen Chloride (HCl) 1000 5 
Hydrogen Cyanide 400 10 
Cyclohexane  500 5 
Sulfur Dioxide 100 3 
 
 
 10
I.7  Current Status of Escape Respirators: 
Major manufacturers like Drager?, Sundstrom? and Essex? amongst others are 
into manufacturing of escape masks. No manufacturer has a CBRN with CO compliant 
escape mask as of now.  
Schematic appearance of a fire escape mask on a manikin is shown in figure 1.2. 
 
  
Figure 1.2: Schematic of Fire Escape Mask on a Manikin  
(Source: Sundstrom product leaflet) 
A: Hood  D: Canister 
B: Visor  E: Particulate Filter 
C: Half mask  F: Exhalation Valve 
 11
The description of the two chosen escape respirators is given in table 1.4. 
Table 1.4: Description of Parat C? and SR 77? 
Attribute Parat C?* SR 77?**  
Standards Passed EN 403 EN 403 
Area 71 cm
2
73 cm
2
Total Catalyst Loading 173 gm  
(Hopcalite) 
182 gm 
(Carbon = 58 gm) 
(Mol Sieve = 40 gm) 
(Hopcalite = 84 gm) 
Total Bed Depth 4.5 cm 4.5 cm 
Pressure Drop thro? 
the bed 
> 40 mm of H
2
O > 40 mm of H
2
O 
Time 19 min 35 min 
(Source: *Product literature, **Personal communications) 
 12
Figures 1.3 and 1.4 show the product pictures for PARAT C? and SR 77? respectively. 
 
Figure 1.3: SR 77? on a Manikin 
(Source: Sundstrom website) 
 
 
Figure 1.4: Parat C? Done by a Model 
(Source: Drager? Website) 
As can be seen from the pictures and the numbers in the table, both these products are 
very big with a high pressure drop, which directly means breathing resistance here. These 
products are heavy as well. The main reasons for these products to be big are as follows: 
 13
- The catalyst loading inside the cartridge is packed bed of approximately 1x3 mm 
particles. This particular configuration offers very weak contacting efficiency. 
- The main component of the cartridge, hopcalite catalyst is very sensitive to 
moisture poisoning. It deactivates extremely rapidly in presence of moisture. 
Hence these masks have excess quantities of catalyst. 
Moreover, as mentioned earlier, the products on the market so far, can meet only EN 
403 standards which are relatively benign when compared to NIOSH or ANSI standards. 
Due to all these reasons, it is very important to develop a suitable material for respiratory 
protection that would effectively remove the carbon monoxide before inhalation. The 
escape mask incorporating the material should be lighter in weight and better in 
performance. The breathing resistance offered by the material should be extremely low 
for ease of use.  
Microfibrous entrapped Oxidation catalysts offer a promise for research into this 
arena. This catalyst can be incorporated into the fire escape mask to convert CO to CO
2
 
thereby reducing the risk of physical injury.  
 
I.8  Carbon Monoxide Oxidation Catalysts: 
The development of CO Oxidation catalysts started in the early 1920s. One of the 
very first developed catalysts was Hopcalite. The development of hopcalite is well known. 
Lamb, Bray and Frazer and co-workers [1.8] conducted most of the investigations that 
resulted into the production of this catalyst. Hopcalite is copper and manganese mixed 
oxide catalysts. Individually manganese oxide and copper oxide are high-temperature 
active [1.9]. Due to the mixture effect, the mixed oxide becomes low temperature active 
 14
for CO oxidation. This catalyst suffers due to loss in activity in presence of moisture very 
rapidly. Same investigators reported much of the later work [1.10, 1.11] on the catalyst 
oxidation of carbon monoxide related to various factors influencing the catalytic activity 
of hopcalite and its constituent oxides. 
Almquist and Bray [1.9] tested effect of catalyst composition, various operating 
conditions such as temperature, CO concentration, moisture content and reduction under 
flowing carbon monoxide. Their findings indicated a strong poisoning by moisture and 
irreversible activity loss due to reduction of catalysts under carbon monoxide in absence 
of oxygen.    
Lamb and Vail [1.10] studied effect of water on CO oxidation by hopcalite. The 
different reasons for this deactivation could be, (1) the water can be adsorbed onto the 
catalyst surface as molecules thereby hindering the access of active sites to reactants or 
desorption of products from the surface; (2) water might react stoichiometrically with the 
whole surface or part of it, to form a layer of inactive material that may behave similar to 
a water layer;(3) water vapor might absorb active radiation of electrons emitted from the 
catalyst, or it might react with the activated molecules, ion or atoms of the gases near the 
catalyst surface and so diminish the number of reacting particles; (4) more than one of 
these effect might happen simultaneously. 
Brittan et al [1.12] proposed kinetic model for hopcalite catalyzed carbon 
monoxide oxidation reaction. The model exhibits significant departure from previously 
assumed first order kinetics. It follows Langmuir-Hinshelwood type of mechanism. 
Veprek et al [1.13] studied the mechanism of deactivation of hopcalite by various 
analytical techniques. The techniques and characteristics of the catalyst used and 
 15
observed were EDS (Energy dispersive spectroscopy) for Bulk Composition, SEM 
(scanning electron microscopy) for Morphology, BET ((Branuer, Emmett, Teller)) for 
surface area, XRD (X-ray diffraction) for bulk structure, TG/TDA (thermo gravimetric 
analysis/differential thermal analysis) for thermal properties, XPS (X-ray photoelectron 
spectroscopy) for surface chemistry, structure and composition and ISS (ion scattering 
spectroscopy) for depth profile. Phase change induced segregation and impurities and 
dopants at small levels appearing and blocking sites were observed to be causes of 
deactivation.  
Rogers and co-workers [1.14] investigated mixtures of manganese, cobalt and 
silver oxides for low temperature CO oxidation. These catalysts exhibited activity similar 
to that of hopcalite and were found to be moisture sensitive.  
Imamura and co-workers [1.15] investigated oxidation of carbon monoxide catalyzed 
by Manganese-silver composite oxides. The results indicated that composite oxides had 
much higher activity compared to single oxide of manganese or silver. Silver in the 
composite catalyst remained in the oxide form for a mol% of less than 50, while it lost 
lattice oxygen in the presence of manganese at higher temperatures. 
Musick and Williams [1.16] compared different catalysts for low temperature carbon 
monoxide oxidation. The aim of the research program was to be able to reduce CO 
concentration from 5000 ppm to 50 ppm and be able to maintain it at that level for at least 
72 hours in a volume of 4248 m
3
. Following catalysts were chosen for study:  
- carbon impregnated with copper, chromium and silver (whetlerite),  
- hopcalite,  
- supported palladium metal  
 16
- supported platinum metal.  
The catalysts were tested with 3000 to 5000 ppm of CO in air at 2100 Hr
-1
 space 
velocity, different temperatures and 15% & 50% relative humidity. Their findings 
indicate, at room temperature and 50% RH, hopcalite and platinum have no catalytic 
activity. At room temperature and 15% RH, hopcalite is superior to platinum. Hopcalite 
is more efficient in the temperature range of 52 ? 66 
0
C compared to all other catalysts 
for both the humidity levels. At higher temperatures of 113 ? 135 
0
C, platinum and 
palladium are superior to hopcalite or whetlerite. Higher humidity affects hopcalite 
adversely. 
G?rdag and Hahn [1.17] studied the synergistic catalytic activity of platinum and 
metal antimonates and compared that to Pt/SnO
2
/Al
2
O
3
. The various catalysts used for 
this study were Pt/NiSb
2
O
6
, Pt/CoSb
2
O
6
, Pt/CuSb
2
O
6
 and Pt/SnO
2
/Al
2
O
3
. Their results 
indicate that in the zero order region of oxidation reaction when CO concentration is 
higher, very low degree of synergism is present between platinum and antimonite 
compared to pt and SnO
2.
Benton and Williams [1.18] studied the oxidation of carbon monoxide in presence of 
quartz glass. The findings indicated that quartz glass had no effect on the oxidation.  
Engelder and Miller [1.19] report the experimental investigation of carbon monoxide 
oxidation over titania and mixtures of titania with various metallic oxides that included 
UO
2
, Fe
2
O
3
, NiO, Cr
2
O
3
, Co
2
O
3
, CeO
2
, CuO, SnO
2
, MnO
2
, ZnO, ThO
2
, Bi
2
O
3
, HgO, 
Al
2
O
3
, Ag
2
O, MgO and CdO in different proportions. The best catalysts were obtained 
from 50:50 mixtures of these oxides. Fe, Cu and Ni oxides exhibited the highest activity 
 17
at this ratio. All these results were obtained at higher temperatures mainly 150 
0
C and 300 
0
C. At low temperature of 50 
0
C to 60 
0
C, the catalysts exhibited lower activities. 
Haruta and Co-workers [1.20] discovered that supported gold particles exhibit high 
catalytic activities for low temperature oxidation of CO. Especially gold supported on 
TiO
2
, ?-Fe
2
O
3
 and Co
3
O
4
, NiO, Be(OH)
2
 and Mg(OH)
2
 is very active even at 
temperatures below 273 K. Among the gold catalysts supported on TiO
2
, ? -Fe
2
O
3
 and 
Co
3
O
4
, the turnover frequencies for CO oxidation per surface gold atom are almost 
independent of the kind of support oxides used and increase sharply with a decrease in 
diameter for gold particles below 4 nm. 
It has been shown that activities of above supported gold catalysts for low-
temperature CO oxidation are enhanced by moisture [1.21]. Some of these catalysts are 
already commercialized to remove odor and CO in air at room temperature. Other 
commercial applications include selective CO gas sensors [1.22, 1.23]. These catalysts 
and Au/Fe
2
O
3
 prepared by other groups have been tested for sealed CO
2
 lasers [1.24, 
1.25]. 
These successes were achieved mainly due to method of preparation (achieving very 
high level of dispersion) because the gold catalysts prepared by conventional 
impregnation method exhibit no appreciable activity.  
It is very difficult to obtain gold in a highly dispersed phase as those of Pt or Pd 
mainly because of lower melting point of Au (1336 K) compared to 2042 for Pt and 1823 
for Pd. It has been reported that melting point of gold particles below 2 nm diameter is 
lowered to 573 K due to the quantum size effect. Since gold itself is known to be very 
inactive, the enhancement in activity of gold metal oxide catalyst can be attributed to 
 18
electronic interactions and/or the active sites on the interfacial perimeter resulting from 
the gold deposition on a support. 
M. Haruta et al [1.26] discussed the low temperature activity of gold based 
catalysts prepared by co-precipitation method for CO oxidation. The catalysts prepared 
were Au/MnO
x
, Au/ ? -Fe
2
O
3
, Au/Co
3
O
4
, Au/NiO and Au/CuO. Among these Au/ ? -
Fe
2
O
3
, Au/Co
3
O
4
 and Au/NiO were highly active for CO oxidation showing appreciable 
enhancement in catalytic activity due to combined effect of gold and the transition metal 
oxide. These catalysts were active for CO oxidation even at a temperature as low as 203 
K. The high activity of these catalysts is attributed to fine dispersion of gold on the 
surface of metal oxide giving particle size smaller than 10 nm. 
Jia at al [1.27] studied oxidation and adsorption of CO on Au/Al
2
O
3
 by infra red 
spectroscopy. The findings include formation of two different species on the surface of 
gold, reversibly adsorbed CO and irreversibly adsorbed CO. Gold particles catalyzed the 
CO oxidation process by means of reversibly adsorbed species whereas irreversibly 
adsorbed species remain untouched. It has also been found that oxidized gold particles 
have no activity for oxidation also Au/Al
2
O
3
 calcined at 1273 K had no activity. 
Grunwaldt and Baiker [1.28] studied the Au/TiO
2
 catalyst for the role of gold-
titania interface in CO oxidation. The observed chemisorptive properties of the 
gold/titania interfaces followed a mechanistic model which is based on oxygen 
adsorption on vacancy sites of titania and CO adsorption on gold.  
Jansson et al [1.29] discussed the low temperature oxidation of CO over cobalt 
oxide catalyst supported on alumina. The catalyst has been found to be active at low 
temperature but deactivates rapidly. The deactivation is attributed to carbonate formation 
 19
detected by FTIR studies and consumption of surface oxygen that makes the particular 
site lose its activity. 
Costello et al [1.30] studied deactivation behavior of Au/Al
2
O
3
 catalyst for CO 
oxidation. The activity is reported to drop very fast for first few minutes. The proposed 
reaction pathway is insertion of CO into the Au+OH- bond to form a hydroxycarbonyl 
which, is oxidized to a bicarbonate. Decarboxylation of the bicarbonate completes the 
reaction. Water addition to the feed is reported to be helpful for enhancing activity. 
Date et al [1.31] reported the performance of Au/TiO
2
 catalyst for CO oxidation 
under ambient conditions. The best performance was obtained with a catalyst calcined at 
473 K at room temperature. The catalyst maintained activity for few days. Is has also 
been proposed that there is an optimum moisture level in the feed at around 200 ppm. 
The catalyst could be effectively regenerated by light irradiation.  
Gardner and Hoflund [1.32] prepared and tested MnO
x
, Ag/MnO
x
, Au/MnO
x
, 
Cu/MnO
x
, Pd/MnO
x
, Pt/MnO
x
, Ru/MnO
x
, Au/CeO
x
 and Au/Fe
2
O
3
 for low temperature 
CO oxidation. According to these researchers Pt and Pd based catalysts need to be pre-
reduced for better performance. Au/MnO
x
 catalyst was observed as the best effective 
catalyst at low temperatures such as room temperature. Also heat treatment in air or 
oxygen was observed to be beneficial for MnO
x
 based catalysts.  
In a separate study Hoflund, Gardner and co-workers [1.33] reported the influence of 
promoters on the performance of Au/MnO
x
 and Pt/SnO
x
/SiO
2
 low temperature CO 
oxidation catalysts under stoichiometric conditions. The results indicate that, the 
performance of Pt/SnO
x
/SiO
2
 catalyst is improved by the addition of 5wt% of Fe, 1 wt% 
Sb, 5 wt% Sb, 1 wt% As and 1.8% P. The performance of Au/MnO
x
 could be improved 
 20
significantly by the addition of 1 at% Ce but reduced by the addition of 1 at% Co. Under 
the conditions studied, Au/MnO
x
 is found to be better catalyst compared to Pt/SnO
x
/SiO
2
.  
Dong and co-workers [1.34] studied various palladium based catalysts for low 
temperature CO oxidation. These include Pd/CeO
2
, Pd/SnO
2
-TiO
2
, Pd/ZrO
2
-TiO
2
, 
Pd/Al
2
O
3
-TiO
2
, Pd/CeO
2
-TiO
2
 and Pd/TiO
2
. Among all the catalysts, Pd/CeO
2
-TiO
2
 
exhibited better catalytic activity. Among various Pd/CeO
2
-TiO
2
 catalysts the best 
candidate corresponds to 1wt% Pd loading and Ce/Ti ratio of 1:7 to 1:5. This catalyst 
showed significant activity at room temperature. 
Gulari et al [1.35] discussed use of silver cobalt composite oxide for CO oxidation. 
The catalyst structure study by XRD, XPS and TGA indicate that silver cobalt oxide is a 
composite oxide where silver is stabilized in an oxide in the presence of cobalt at 
temperatures as high as 1073 K. IR spectroscopy study of the reaction shows that, the 
catalyst is deactivated due to presence of CO
2
 and water in the feed stream. This was 
mainly because of weak adsorption of CO
2
 and water on the surface of catalyst thereby 
physically blocking the sites. This deactivation was not observed at temperatures more 
than 393 K.  
 Lin et al [1.36] reported the preparation and testing of Au/Y zeolite, and Au-Fe/Y 
zeolite. These catalysts exhibited significant activity at lower temperatures. XPS studies 
done on Au-Fe/Y suggested that formation of carbonate like species that covered the 
active sites was the main cause for catalyst deactivation. On the other hand TEM studies 
suggested that the sintering of nano-gold particles was the main reason for the slight 
deactivation of Au/Y. 
 21
Hoflund [1.37] prepared and studied silica supported Pt/ SnO
x
 and Fe promoted 
Pt/SnO
x
. Ion scattering spectroscopy (ISS) has been used to examine the outermost 
atomic layers of these catalysts. The nonpromoted catalyst exhibits agglomeration of the 
platinized tin oxide film exposing the inactive silica support. Whereas this does not 
happen when Fe is present as promoter and active surface area can be maintained.  
Torncrona et al [1.38] studied the low temperature activity of cobalt oxide and 
ceria promoted Pt and Pd catalyst. Results indicate that cobalt containing catalysts are the 
most effective ones even in the absence of noble metals. These catalysts showed much 
lower light-off temperature compared to un-promoted Pt and Pd catalysts. 
Thormahlen et al [1.39] studied Pt/Al
2
O
3
, CoO
x
/Al
2
O
3
 and Pt/CoO
x
/Al
2
O
3
 in 
monolith form. Preoxidized Pt/CoO
x
/Al
2
O
3
 was found to be active at very low 
temperatures even at 200K. At these low temperatures the activity of the catalyst is 
independent of platinum content. The deactivation was also studies here. Presence of 
moisture leads to formation of OH
-
 species on the surface of the catalyst thereby blocking 
the active sites. Carbonate formation is also reported as a cause of catalyst deactivation.  
Mergler et al [1.40] reported the activity of Pt/CoOx/SiO
2
, Pt/MnOx/SiO
2
 and 
Pt/SiO
2
. Performance of these catalysts was compared with commercially available 
catalysts viz. Pt/CeO
x
/Al
2
O
3
, Pt/Rh/Al
2
O
3
 and Pt/Al
2
O
3
. Pt/CoO
x
/SiO
2
 and Pt/MnO
x
/SiO
2
 
were the most active catalysts for CO oxidation after a pretreatment of reduction. 
Partially reduced metal oxides are necessary to increase the activity of Pt/CoOx/SiO
2
, 
Pt/MnO
x
/SiO
2
 or Pt/CeO
x
/Al
2
O
3
. In Pt/CoO
x
 catalyst, CoO
x
 acts as an o-supplier thereby 
affecting the adsorption of CO or O
2
 on platinum. 
 22
Fuller and Warwick [1.41] studied low temperature oxidation of carbon monoxide 
on SnO2-CuO gels. The catalyst was found to be active after thermal treatment at 450 
0
C. 
This effect has been attributed to the ion-exchange sorption of Cu (II) on the surface of 
the primary hydrous SnO
2
 particles formed during the precipitation process. The best 
activity was observed at an atomic ratio of 0.55:1 of Cu:Sn.  
Imamura and Yoshie [1.42] reported effect of samarium addition on activity and 
thermal stability of manganese/silver catalysts. The results suggest that manganese oxide 
serves as oxygen reservoir that helps in maintaining the activity of the catalyst when used 
in highly oscillating conditions. The lattice oxygen from manganese oxide is readily 
transferred to and desorbed from Ag. The results further include an addition of small 
amount of Sm inhibits grain growth of manganese oxides treated at high temperatures in 
a reducing atmosphere, thus, leading to retention of a large surface area. Due to restricted 
grain growth of Mn/Ag/Sm catalyst, Ag could be finely and homogeneously dispersed in 
the matrix of the catalyst. On the other hand Ag aggregated on the surface as large 
crystals or migrated towards center of Mn/Ag catalyst particle. 
OH and Eickel [1.43] studied effects of Cerium addition on CO oxidation kinetics 
over alumina supported rhodium catalyst. The observed changes in the kinetics include a 
suppression of the CO inhibition effect, decreased sensitivity of the rate of O
2
 
concentration and decreased apparent activation energy. The kinetic effects involved here 
can be best explained by surface oxidation mechanism. Carbon monoxide adsorbed on 
Rh site reacts with lattice oxygen of neighboring ceria particle. It was also observed that 
Ce addition has the same effect regardless of sequence of deposition while preparing the 
catalyst. 
 23
I.9  Methods of Catalyst Preparation: 
The preparation of catalyst is commonly described as art [1.44]. In some cases 
relationship between formulation procedures and final catalyst behavior be obscure but 
an understanding of effects generated with certain components by manipulations such as 
precipitation, washing, drying, heating etc helps to clarify the reasoning behind certain 
procedure. This also throws light on possible improvements in catalyst making process.  
Many of the catalysts are either a finely divided a metal supported on a high surface area 
carrier such as Alumina, zeolites, or a metal oxide either on a carrier or unsupported. 
Some other types of catalysts include promoted catalysts, wherein the performance of 
metallic catalyst is improved by the presence of some other metal oxide. Following two 
are main methods of catalyst preparation: 
i. Precipitation Method 
ii. Impregnation Method 
 
I.9.1  Precipitation Method 
This method involves in its initial stages, mixing of two or more solutions or 
suspensions of materials causing precipitation. This is followed by filtration, drying, 
washing, forming and heating. Simple wet mixing without precipitation is also used 
sometimes, but this fails to generate required degree of contacting between the 
species involved. If a carrier needs to be incorporated, the precipitation is done in the 
presence of suspension of a finely divided support or a compound that can be 
converted to required form of the carrier. Sometimes binders, cements, die-lubricants 
or thixotropic agents are also added in a later stage if required. The forming process 
 24
determines the final characteristics of the catalyst such as pore size distribution, size 
and shape of the catalyst particles. The catalyst is activated by physical and chemical 
changes. This typically involves heating to cause decomposition or calcinations. 
Sometimes pre-treatments such as reduction is used to regain the metal form of the 
oxidized catalyst.  
 
I.9.2  Impregnation Method 
In this method a carrier, normally porous is contacted with a solution, usually 
aqueous of one or more suitable metallic compounds. Normally this is done by two 
different procedures, dipping the support completely into excess quantity of solution 
or incipient wetness where, support is contacted as by spraying with the solution of 
appropriate concentration. Incipient wetness method allows a better control over the 
amount of the active ingredient and reproducibility of the results is better. The carrier 
is then dried and the catalyst is activated as mentioned above under precipitation 
method. The final size and shape of the catalyst are that of carrier material. This 
method is preferred for making noble metal catalysts as it is much cheaper to spread 
finely divided metallic particles.  
 25
 
I.10 Catalyst Treatment Steps: 
This section lists the steps involved in conditioning the catalyst to suit a given 
requirement. The stages discussed are calcination and reduction of catalyst to metallic 
form by treating at high temperature in reductive environment.  
I.10.1 Calcination 
Calcination process can have various purposes. The first is to eliminate 
extraneous material such as binders and die lubricants, also volatile and unstable anions 
and cations that have been previously introduced but are not desired in the final catalyst. 
Second, a substantially elevated temperature is usually needed to increase the strength of 
the final pellet or extrudate by causing incipient sintering. Excessive sintering, however, 
may reduce the catalyst activity by reducing surface area, and it may also cause diffusion 
limitations by reduction of pore size, so an optimum is desired. 
 
I.10.2 Reduction to the Metal 
Most commonly, a metal is formed by reduction of the oxide at an elevated 
temperature by contact with flowing hydrogen or hydrogen diluted with nitrogen, the 
latter for safety reasons [1.44]. 
It can be observed from thermodynamic calculations that at temperatures in the 
region of 570 to770 K the reduction of metal oxide to the metal is highly favored for all 
group VIII elements and copper, silver, gold, and rhenium [1.45]. For the elements 
chromium, vanadium, tantalum, titanium, and manganese, the oxide form is highly 
favored. 
 26
I.11  Catalyst Characterizations: 
The correlation between catalyst behavior and the physical and chemical structure 
of the catalyst is a basic problem as most practical catalysts are complex materials. As a 
result very few methods of characterization are standardized. These include 
determination of total surface area by the Brunauer-Emmett-Teller (BET) method, void 
fraction, pore size distribution and in some cases specific metal area by selective 
chemisorption. Other than these many analytical techniques developed in other branches 
of chemistry are available for studying the catalyst.  
 
I.11.1  Measurement of Surface Area: 
The principal method of measuring total surface area of a catalyst is by adsorption 
of a particular molecular species from a gas or liquid on the surface. If the conditions 
under which a complete adsorbed layer, averaging one molecular thick, can be 
established and the area covered per molecule is known, then the quantity of the adsorbed 
material gives directly the total surface area of the sample.  
The most common method of measuring surface area, and used very routinely in catalyst 
studies is that developed by Brunauer, Emmett and Teller in 1938.  
 
I.11.2  Specific Area by Selective Chemisorption: 
For a supported metal catalyst it is frequently desirable to be able to determine the 
exposed metal area in distinction to the total surface area. This can be achieved by 
 27
measuring the uptake of a gas that is chemisorbed on the metal but negligibly on the 
support, under conditions that allow monolayer coverage. Most useful for this purpose is 
hydrogen gas but carbon monoxide as well as oxygen are also used for this purpose. 
Hydrogen has been studies most extensively especially on platinum and nickel. 
As a prerequisite, it is necessary to know the chemisorption stoichiometry which is the 
number of surface atoms covered for each molecule of gas adsorbed, and the surface area 
occupied per metal atom. For hydrogen this number is almost always be 2, since it 
dissociates upon adsorption and each hydrogen atom is adsorbed on one metal atom. 
 
I.11.3  Pore Size Distribution: 
Pore size distribution is important for prediction of the effective diffusivity in a 
porous catalyst. Two different methods are used for this purpose: Physical adsorption of a 
gas, which is applicable to pores less than about 60 nm in diameter, and mercury 
porosimetry, applicable to pores larger than about 3.5 nm. In method 1, the measurement 
of adsorption or desorption of a gas as a function of reduced pressure is used to determine 
the pore size distribution. Method 2 works on the principle of non wetting liquid 
penetration in a capillary.  
 
I.11.4  Selected Instrumental Methods: 
This section describes the details of selected instrumental methods for catalyst 
characterization. 
 28
I.11.4.1 Scanning Electron Microscopy (SEM)/Energy Dispersive Spectrometry (EDS): 
SEM has been used primarily for examination of the topology of catalyst surfaces, 
for example characterization of platinum gauzes before and after use in a reactor and 
sintering of large supported metal crystallites. EDS can be used for quantification of 
various elements present in the catalyst. It also gives wt% of various metals. 
I.11.4.2  Transmission Electron Microscopy (TEM): 
TEM is useful for indicating the size of the supported metal crystallites, change in 
their size, shape, and position with catalyst use. Replicas are useful for obtaining 
information on pore structure.  
I.11.4.3  X-Ray Diffraction Crystallography (XRD): 
XRD can be used to obtain information about the structure and composition of 
crystallite materials. Common compounds can be identified using tabulations of reference 
patterns. The minimal limit of detection is approximately 5% for compounds and 
approximately 1% for elements. With calibration procedures it is possible to obtain 
quantitative information and thus determine the approximate amount of a particular phase 
in a sample.  
The mean crystallite size of a material can also be determined from the 
broadening of an X-ray diffraction peak. Small angle scattering may be used to give the 
particle distribution in the range of 5 to 100 nm. 
I.11.4.4  X-Ray Photoelectron Spectroscopy (XPS): 
 29
This method is also called as Electron Spectroscopy for Chemical Analysis 
(ESCA). It is a powerful technique, which can analyze for all the elements except 
hydrogen. It gives the most accurate and precise atomic electron binding energy and thus 
it yields the structural data in terms of the valence of the oxidation state as well as atomic 
charge densities. Also the analysis is chemically non-destructive. 
 
I.11.5  Calorimetry: 
Calorimetry may be employed to observe various types of chemical 
transformations that are accompanied by significant energy changes. A differential 
scanning calorimeter may be used with small samples. 
 
I.11.6 Gravimetric Methods: 
The change in weight of a catalyst with changing experimental conditions can be 
used for a variety of studies. The method has been applied for adsorption-desorption 
studies and has been particularly useful for studying the rate of coking, dehydration, 
sorption of poisons, catalyst regeneration etc as a function of reaction conditions. It is 
also useful for catalyst characterization, e.g. that of oxidation catalysts in which weight 
gain or weight loss may reveal the state of oxidation and hence stability as a function of 
environment.  
 30
I.12  Microfiber Based Composite Materials: 
This section gives the details of microfibrous entrapped material development and 
associated literature. 
I.12.1 Wet ? lay Process/ Sintering Process 
Microfibrous materials are very important due to their typical characteristics of 
offering enhanced heat and mass transfer in chemical processes. A new patented [1.46] 
class of materials made by wet lay process followed by sintering at high temperatures 
produce a fine mesh of metal fibers. Figure 1.5 shows an SEM image of 4 microns Ni 
fiber mesh.  
 
Figure 1.5: SEM Image of 4 ?m nickel fiber mesh [1.46] 
These materials have the capability to incorporate micron scale particles. Sintered 
Microfibrous composites using 16% Ni/Al
2
O
3
 catalyst for toluene hydrogenation have 
shown 2-6 times higher specific activity than conventional packed bed catalyst on a 
 31
weight basis, while volumetric activities of 40 vol.% composite catalysts were 80% 
higher than conventional pellets [1.47]. 
Microfibrous materials have various other advantages including high intra bed 
thermal conductivity, adjustable void volume, higher exposed surface area of catalysts 
thereby giving higher effectiveness factors, reduced pressure drop and mechanical and 
structural stability [1.46]. 
The combination of wet lay and sintering processes allow adjustable void 
volumes from almost 98% down to those of packed beds [1.48]. This permits the 
optimization of composite catalysts as per the process requirement.  
I.12.2 Alternate Materials of Manufacturing  
Microfibrous materials can also be manufactured using various polymer [1.51] 
and ceramic fibers [1.52] depending upon the type of application. Figures 1.6 and 1.7 
show polymeric and ceramic microfibrous entrapped high surface area catalyst supports 
respectively. 
 
 32
 
X100 
Figure 1.6: Polymer Fiber Entrapped Support [1.51] 
Polymer microfibrous materials have substantial cost advantage over metal 
materials. Hence these materials can be used for high volume low value type of 
applications such as duct filters. However these materials suffer a major disadvantage in 
terms of very high temperature instability hence cannot be used for applications such as 
high temperature catalysis. 
 33
500?m
 
Figure 1.7: Ceramic Fiber Entrapped 150 -250 Micron SiO
2 
[1.52] 
Ceramic materials find applications in corrosive environment where metal fibers 
cannot be used. Ceramic microfibrous entrapped materials is a cheaper option to metal 
fibers. 
 34
I.13  Applications of Microfiber Composite Materials: 
 
 I.13.1 Microfibrous Entrapped Catalysts and Sorbents: 
The application of Microfibrous materials to eliminate hot-spots in a temperature 
sensitive reactor enables the use of these materials in fuel processing and reforming 
applications [1.49]. 
 
I.13.2 Microfibrous Metallic Filters: 
These materials have applications in commercial processes such as polymer 
filtration, assorted HEPA filter applications and automotive airbags. The relatively low-
cost of these media opens the possibility of using regenerable metallic filter elements for 
automobiles and other low cost applications in place of currently employed disposables. 
This would result in significant reduction in environmental pollution due to disposables 
[1.49].  
 
I.13.3 Microfibrous Entrapped Electrocatalysts and Faradaic Materials: 
Due to the electrical conductivity of metal mesh, Microfibrous materials are 
suitable candidates for reducing intra particle and intra electrode resistances and transport 
limitations experienced in many electrochemical processes and devices such as liquid 
double layer capacitors and batteries [1.50]. 
 35
CHAPTER II 
 
EXPERIMENTAL 
 
 
 
This chapter presents the experimental apparatus and detailed procedures used in this 
research. Following various aspects of this research are discussed in this chapter: 
II.1  Catalyst preparation 
II.2  Details of chemicals used 
II.3  Experimental set-up and reactor details 
II.4  Details of instruments and equipments used for this research work 
II.5  Pressure drop test set-up 
II.6  Commercial products testing set-up 
II.7  Analytical section 
 
II.1  Catalyst Preparation 
All the catalysts tested in this study were prepared by either co-precipitation or 
incipient wetness method. Most noble metal based catalysts supported on a high surface 
area were prepared by incipient wetness, for example platinum supported on silica. 
Catalysts such as Cu/CeO
2 
were prepared using co-precipitation method.  
 
 36
II.1.1 Incipient Wetness Procedure: 
The required support is divided into 150 ? 250 ? particle size and dried at about 
100
0
C for 24 hours to make sure that there is no water in the pores of the support. The 
support was then impregnated with required metal solution until the whole surface was 
completely wet. The resulting material was then dried at about 100
0
C for 24 hours.  
The dried material was then calcined for about 4 hours. For a promoted catalyst, one 
more step of impregnation, drying and calcinations was added. 
II.1.1.1  Preparation of Microfibrous Entrapped Cobalt Promoted 
Platinum/Alumina Catalysts: 
The procedure for preparation of microfibrous entrapped cobalt promoted 
platinum/alumina catalyst is detailed here. 
II.1.1.2  Materials: 
? Support: ? - Alumina (220 m
2
/gm, 150 ? 250 micron) 
? Metal:   Platinum {Diaminedinitroplatinum (II), 3.4% platinum solution} 
? Promoter:  Cobalt: {Cobalt (II) Nitrate 99.5% assay, 0.25 M solution} 
? Microfibrous Materials: 
3:1 mixture of 4 micron and 2 micron wires 
3:1 ratio of metal to cellulose 
4 gm of alumina entrapped in one 6? disk. 
II.1.1.3  Procedure: 
1. Entrap 4 gm of 150 -250 micron alumina in one 6? disk. (Composition: 8 micron 
Ni = 1.5 gm, 4 micron Ni = 0.5 gm, Cellulose = 0.67 gm, Alumina = 4 gm) 
2. Dry 3 disks together to make a 2? thick precursor.  
 37
3. Pre-oxidize the precursor for 30 minutes at 400
0
C under controlled air flow. 
4. Sinter the material.  
5. Dip the precursor in 0.25 M cobalt nitrate solution 
6. Apply vacuum to the precursor to remove excess nitrate solution. 
7. Dry the precursor in oven at 100
0
C for 24 hrs. 
8. Calcine the precursor for 4 hrs in air at 400
0
C. 
9. Impregnate platinum solution drop by drop on the support until wet.* 
10. Dry the precursor in oven at 100
0
C for 24 hrs. 
11. Calcine the precursor for 4 hrs in air at 400
0
C. 
12. Reduce in flowing hydrogen at 250-300
0
C for 2 hrs. 
*: Dip and vacuum procedure can also be applied for platinum impregnation and excess 
solution can be recovered. 
 
II.1.2 Co-precipitation Method: 
The required chemicals were mixed in required proportions carefully monitoring 
the pH of the resulting solution. The solution was then filtered, dried and calcined to 
yield final catalyst. The catalyst was then crushed to obtain 150 ? 250 ? particle size. 
 38
II.2 Details of Chemicals Used: 
This section details the chemicals used for this research work mainly catalyst 
preparation along-with source of the material. Table 2.1 gives the list of chemicals used 
for various catalyst preparations. 
Table 2.1: List of Chemicals used for Catalyst Preparation 
Sr. 
No. 
Chemical Purity /Assay 
(%) 
Purpose Supplier 
1. Pt(NH
3
)
2
(NO
2
)
2
3.4% Pt Metal precursor Aldrich Chem. Co. 
2. Mn(NO
3
)
2
.XH
2
O 99.98 Metal precursor Alfa Aesar Co 
3. Co(NO
3
)
2
.6H
2
O 99.5 Metal precursor Alfa Aesar Co 
4 Fe(NO
3
)
3
.9H
2
O 98 Metal precursor Alfa Aesar Co 
5. Ce(NO
3
)
3
.6H
2
O 99.5 Metal precursor Alfa Aesar Co 
6 HAuCl
4
49.5 wt% Au Metal precursor Alfa Aesar Co 
7 AgNO
3
99.9 Metal precursor Alfa Aesar 
8 Pd(NH
2
)
2
5% Pd Metal precursor Alfa Aesar Co. 
9 Cu(OH)
2
56-57 % Cu Metal precursor Aldrich Chem. Co. 
10 RuCl
3
.3H
2
O 42.71% Ru Metal precursor Alfa Aesar 
11 SiO
2
 Support Alfa Aesar Co 
12  Al
2
O
3
   Support Alfa Aesar 
13 TiO
2
99.9% Support Alfa Aesar Co 
14 Na Y Zeolite  Support  
15 BPL Carbon  Support  
16 4A Zeolite  Support Zeolyst 
 39
 II.3 Experimental Apparatus: 
The apparatus used for catalyst screening tests is shown in figure 2.1. Figure 2.2 
shows the reactor for catalyst testing. Figure 2.3 shows the apparatus used for pressure 
drop measurement. 
 
 
CO =          1200 - 6000 ppm 
5%CO/N
2
 O
2 
=           17.6- 19.5% 
Balance=    N
2
RH =         90% 
QRAE Plus? 
Detector
 
 
low 
 
Water
Saturator
Mass F
Controller
Reactor
Aerosol 
low 
 
Trap
Mass F
Controller
TC
GC, 
 
Relative 
Humidity
Detector
TC
Exhaust 
Ice Bath
Air
 
Figure 2.1: Experimental Apparatus for Catalyst Screening 
 
 40
S
u
p
p
o
r
t
 
S
c
r
e
e
n
 
20.26 cm
2 
C
a
t
a
l
y
s
t
 
b
e
d
 
5.08 cm 
5
0
.
8
 
c
m
 
20.26 cm
2
5.08 cm
5
0
.
8
 
c
m
 
S
u
p
p
o
r
t
 
S
c
r
e
e
n
 
C
a
t
a
l
y
s
t
 
b
e
d
 
Optional packed bed  
of various sorbents 
 
Figure 2.2: Catalyst Testing Reactor 
 
As shown in figure 2.1, a mixture of air and carbon monoxide is passed through a 
water saturator and fed to the reactor thereafter. The reactor is packed bed tubular reactor. 
Typically catalyst quantity used for these tests was 0.1 g. After passing through the 
reactor the gas stream was fed to the gas chromatograph through a moisture trap. The 
resulting gas mixture was analyzed for carbon monoxide, carbon dioxide, oxygen and 
nitrogen content. As seen in figure 2.2, the catalyst could be tested in presence of optional 
packed bed of additional sorbents. 
 41
Mass Flow 
Controller 
Sample 
Pressure Drop 
measurement Cell 
Air 
 
Figure 2.3 Pressure Drop Measurement Apparatus 
 42
II.4 Details of Instruments and Equipments used  
Table 2.2 gives the list of equipments/instruments used for CO oxidation set up. 
Table 2.2: List of Equipments/Instruments used for CO Oxidation Set up 
Sr. No. Item Description Range of Operation 
1. Reactor Glass 0.5 cm dia  
2.  Reactor Furnace Tube Furnace  0 ? 500 
0
C 
3.  Air Flow Controller Make: Omega Co. 0 ? 35 LPM 
4.  CO Flow Controller Make: Omega Co. 0 ? 2   LPM 
5 Gas Chromatograph Make: Agilent, Model: 6890, 
Column: Molecular sieves, 
Detector: TCD 
 
6. CO analyzer Make: RAE systems model: 
QRAE plus?  
0- 1500 ppm 
 
II.4.1 Experimental Conditions 
The experimental conditions for low temperature oxidation were as follows for given sets 
of experiments: 
CO concentration:   0.25 ? 2% 
Face Velocity:   0.9- 3 cm/sec 
Water Content:  3% 
Temperature:   20 ? 100 
0
C 
Pressure:   1 atm 
 43
 
II.5 Pressure Drop Measurements: 
Pressure drop through the Microfibrous material was measured using a sample 
cell consisting of 0.75 in. Swagelok? Ultratorr fitting with 0.75 in. SS tubing inserted 
into the ends of the fitting. The cell was equipped fitted with spacers inside the fitting to 
hold the sample of Microfibrous material properly. The cell was connected to the outlet 
of a mass flow controller (Omega, 0 ? 50 LPM). Pressure drop was measured by a DP 
cell (Omega, PX154-010DI) and the readings were indicated by a four digit process 
meter (Omega DP24E). The pressure drop was measured at various values of the inlet 
flow rate.  
Schematic diagram of pressure drop measurement apparatus is shown in figure 
2.3. 
 44
II.6 Apparatus for Commercial Product Testing: 
Schematic diagram of apparatus for testing of commercial products namely 
canister of Drager? Parat C? and Monolith of Essex? plus 10? are shown in figures 2.4 
and 2.5 respectively. 
The apparatus were constructed out of PVC pipes with flanges for holding the 
Drager? canister. For monolith testing, the PVC pipe was fabricated to be able to hold 
the monolith. The edges of the monolith were sealed using high vacuum silicone sealant. 
This pipe was then connected via a socket to another pipe which was used for outlet CO 
measurement section. Air and carbon monoxide mixture at appropriate concentration 
level passes through moisture saturator and then flows through the canister. QRAE? 
detector measures the outlet CO concentration.  
 45
 
 
Figure 2.4: Schematic of Drager? Canister Testing Reactor 
 
 
 
In 
Canister 
Flange 
Monolith
Socket
Out 
In 
Out 
Figure 2.5: Schematic of plus 10? Monolith Test Reactor 
 46
II.7 Analytical Section: 
This section describes the analytical techniques used for low temperature 
oxidation of carbon monoxide. 
 
II.7.1 Measurement of Inlet CO Concentration: 
For measurement of inlet CO concentration, gas chromatograph has been used 
(HP 6890). The detector used was of thermal conductivity detector (TCD). The minimum 
concentration of CO that can be measured using this column was 100 ppm. The gas 
chromatograph has been equipped with computer to analyze the data and interface 
software to communicate with computer. 
II.7.1.1 GC Calibration: 
The gas chromatograph was calibrated using standard gas mixture ordered from 
BOC/Air products?. It was calibrated in the beginning and end of every experiment.  
 
II.7.2 Measurement of Relative Humidity 
Relative humidity was measured using relative humidity detector.  
 
II.7.3 CO Detection and Datalog: 
Carbon monoxide can be detected with a sensitivity of 0.1 ppm using the QRAE? 
plus detector. The detector works on the principal of electrochemical sensor. It is an 
online type of detector and also logs real time data of carbon monoxide concentration. 
Once the datalog is over, it can be connected to computer to download the data.  
II.7.3.1 Detector Calibration: 
 47
 The QRAE? detector was calibrated using standard gas ordered from RAE? 
systems. The calibration was done at least once for each set of experiments.   
II.7.3.2 Data Download: 
Following procedure should be used to download the data: 
1. Make sure the computer has Pro RAEsuite? software that logs the data. 
2. Launch the Pro RAEsuite program from the PC 
3. Please make sure that the instrument is fully charged before connecting it to PC. 
If the instrument runs out of power while the downloading process is on, 
processor may hang up and the unit would need to be returned to factory. 
4. Turn on the instrument and connect the computer interface cable between the 
instrument and the computer 
5. Put the instrument into PC communication mode. This can be done by toggling 
the main menu with the mode key until an option ?communicate with PC?? 
appears and then press the [Y/+ button]. 
6. The instrument should display ?Ready to communicate? 
7. Under the communications menu in ProRAE Suite, click on ?receive data?. A 
window will popup reminding to connect the instrument with PC and put it in 
?communication with PC? mode. 
8. Click ?OK? on the popup window. The download may take few minutes 
depending upon, how much data is present on the instrument. 
9. If communication fails, please check connected cable and the 
communication/setup port window in ProRAE suite to make sure that the correct 
 48
COM port is connected. (COM 1). Also check if the instrument is in ?Ready to 
communicate? mode. 
II.7.3.3 Exporting Data to Excel?: 
1. Only data files can be exported, one file at a time. 
2. Launch the ProRAE suite ? program from the PC. 
3. Display a data file by either by opening a file stored on the computer or by 
downloading data as described above. 
4. Select one of the events and proceed to Option >> Export Text which will bring 
up the ?Save As? window, save the file. (File type automatically should be ?Tab 
delimited text files? *.txt) 
5. Launch Excel? and go to File >> Open option 
6. This will bring up the ?Open? window. At the bottom of the window change file 
type to ?All Files?. 
7. Select the required file to be exported 
8. Once the file is opened, the ?Text Import Wizard? window will appear. (3 steps) 
9. Click ?Next? to go to step 2, under delimiters click ?Space? in addition to the 
already selected ?Tab?. 
10. Click finish and an excel spreadsheet should appear containing the exported data.  
Typical data file as well as exported excel files are shown in Appendix A. 
 49
CHAPTER III 
 
RESULTS AND DISCUSSION  
 
III.1 Catalyst Screening Tests 
 This part contains the activity measurements in terms of CO conversion for 
various catalysts prepared as a part of this study. Appendix 3.1 lists all the catalysts 
prepared and tested. The typical conditions used for this catalyst testing were 2% Carbon 
monoxide in excess air at room temperature. 
 
III.1.1 Gold Based Catalysts 
Table 3.1 gives the list of gold based catalysts tested for activity. The activity is 
stated in terms of initial conversion (IC) and time required for conversion to start 
dropping from 100% if applicable (t
drop
). The initial conversion stated here is 100% 
which can correspond to anywhere from 0 to 100 ppm of CO content in the product 
stream. 
 50
Out of the gold based catalysts prepared, 10% Au/MnO
x
 is the only catalyst that is 
capable of removing carbon monoxide completely for first 25 minutes. This is mainly due 
to higher gold content as well as significant quantity of manganese present in the oxide 
form. Same metals when loaded on high surface area supports i.e. silica, alumina, zeolite, 
BPL carbon and titania do not show appreciable conversion due to significant reduction 
in total metal sites available for oxidation and dispersion might not be as fine as it was 
observed in Au/MnO
x
 [1.20].  Gold supported on TiO
2
 is another gold based catalyst 
capable of exhibiting high activity for CO conversion (>80%) for first 15 minutes before 
it starts deactivating. The metal support boundary here is responsible for catalytic activity 
[1.29]. 
But this catalyst is tested without any moisture in the feed. When the catalyst is 
tested with 3% moisture content in the feed, the conversion drops very fast as water acts 
as a deactivating agent for the catalyst. When gold/titania is promoted with suitable 
transition metal such as manganese, the activity drops significantly thereby indicating 
that promoter affects the reaction adversely.  
Table 3.1: Activity Tests of Gold Based Catalysts for Low Temperature CO Oxidation  
Sr. No. Catalyst IC (%) t
drop
 (min) Notes 
1. 10% Au/MnO
x
100% 25  (10% Au) 
2. 5% Au/MnO
x
44% NA (5% Au)
3.  2.5 at% Au/Fe
2
O
3
6% NA (2.5% Au)
4. 1.3%Au-Fe
2
O
3
-Al
2
O
3
4% NA (1.3% Au)
5. Au - Mn ? Alumina 8% NA  
 51 
6. Au - Mn ? Silica 9% NA  
7. Au - Mn ? Zeolite 7% NA  
8. Au - Mn ? BPL carbon 7% NA  
9. Au - Co ? Silica 7% NA  
10. Au - Co ? Alumina 8% NA  
11. Au/TiO
2
88% 15 (4% Au)
12. Au/Mn/TiO
2
40% NA (4% Au)
 
 52 
III.1.1.1 Au/MnO
x
 Based Catalysts: 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 50 100 150 200 250 300
Time (min)
C
O
 C
onv
er
s
i
on (
%
)
10 at% Au/MnOx
5 at% Au/MnOx
 
Figure 3.1: Activity Tests of Au/MnO
x
 Catalysts 
Conditions: 
Inlet CO Concentration = 2 % 
Relative Humidity = 90% 
Catalyst loading= 0.1 gm 
As shown in figure 3.1, the CO conversion drops to below 50% in one hour. The 
activity drop can be explained by irreversible adsorption of CO on the surface of gold 
 53 
which is a pronounced effect for CO oxidation over most metals. Moreover OH
-
 ions 
from water are adsorbed irreversibly on the surface of gold thereby physically blocking 
active sites present for CO adsorption [1.30].   
III.1.1.2 Activity Tests of Supported Gold Catalysts: 
Fig 3.2 and fig 3.3 show the results from activity tests of various supported gold 
catalysts prepared by method of conventional impregnation.  
None of the catalysts show appreciable conversion. This is explained by Haruta et 
al [1.20]. According to these authors, finely dispersed gold only is responsible for 
catalysis. Conventional impregnation method of catalyst preparation fails to reach the 
required particle size of gold on the support. 
 54 
0%
2%
4%
6%
8%
10%
12%
0 20 40 60 80 100 120 140
Time (Min)
CO
 Co
n
v
e
r
s
i
o
n
 (
%
)
Au/Mn/BPL carbon
Au/Co/Silica
Au/Co/Alumina
Au/Mn/Zeolite
Au/Mn/Silica
Au/Mn/Alumina
 
Figure 3.2: Activity Tests of Supported Gold Catalysts 
Conditions: 
Inlet CO Concentration = 2 % 
Relative Humidity = 90% 
Catalyst loading= 0.1 gm 
Reactor configuration: Packed Bed  
 
 
 55 
III.1.1.3 Activity Test of Au/TiO
2
 Catalyst: 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 20 40 60 80 100 120 140
Time (Min)
C
O
 C
onver
s
i
on 
(
%
)
 
Figure 3.3: Activity Test of Au/TiO
2
 Catalyst 
Testing Conditions: 
Inlet CO Concentration = 2% 
Relative humidity= 90% 
Catalyst Loading= 0.1 gm 
Reactor Configuration= packed bed  
 56 
As explained earlier, the initial higher activity of Au/TiO
2
 catalyst is due to role 
played by the metal support interaction. Same observation is reported by Grunwaldt et al 
[1.28]. 
 
III.1.2 Platinum Based Catalysts 
Table 3.2 shows the activity measurement studies for Platinum based catalysts. 
Table 3.2: Activity Tests of Platinum Based Catalysts  
Sr. No. Catalyst IC (%) t
drop
 (min) Notes 
1. Pt-Fe
2
O
3
-Al
2
O
3
7 NA 4% Pt
2. 4%Pt-CeO
2
-Al
2
O
3
5   
3.  4%Pt-Mn
2
O
3
-Al
2
O
3
4   
4. 2%Pt-Al
2
O
3
8%   
5. Pt- Co
2
O
3
 -Al
2
O
3
5  1.1 wt%Pt 
6. Pt- Co
2
O
3
 ?Al
2
O
3
28  4.7 wt%Pt 
7. 4% Pt-Co
2
O
3
-Al
2
O
3
25  4% wt Pt 
8. 4% Pt- Mn
2
O
3
-Al
2
O
3
18%  4% wt Pt 
9. 4% Pt- Co
2
O
3
-SiO
2
7%   
10. 4.7% Pt- Co
2
O
3
-Al
2
O
3
70%  Co:Al = 0.04, 4.7wt% Pt 
11. Pt/TiO
2
71%   
12. Pt/Co/TiO
2
75%   
13 Pt/Mn/SiO
2
100% 10 5.7 wt% Pt 
 
 57 
Among the platinum based catalysts, Pt/Mn/SiO
2
 is the only catalyst that 
give100% CO conversion. Pt/Mn/SiO
2
 gives 100% conversion for first 10 minutes before 
it starts deactivating. All these catalysts are tested with the presence of 3% moisture in 
the feed.  
III.1.2.1 Activity Tests of Supported Platinum Catalysts: 
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
0 20 40 60 80 100 120 140
Time (Min)
C
O
 C
o
n
v
ers
i
on (%
)
Pt/Fe/Alumina
Pt/Ce/Alumina
Pt/Mn/Alumina
Pt/Co/Alumina
Pt/Alumina
 
Figure 3.4: Activity Tests of Pt Based Supported Catalysts 
Testing Conditions: 
Inlet CO Concentration = 2% 
Relative humidity= 90% 
 58 
Catalyst Loading= 0.1 gm 
Reactor Configuration= packed bed 
Figure 3.4 shows the activity of promoted and unpromoted platinum based 
catalysts on high surface area alumina. The promoters were chosen from transition metal 
elements. None of these catalysts showed appreciable conversion for low temperature 
oxidation.  
III.1.2.2 Platinum Supported on TiO
2
: 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 20 40 60 80 100 120 140
Time (Min)
C
O
 C
onv
er
s
i
o
n
 (
%
)
Pt/Co/Titania
Pt/Titania
 
Figure 3.5: Activity Test of Platinum Based Titania Supported Catalysts 
 59 
Testing Conditions: 
Inlet CO Concentration = 2% 
Relative humidity= 90% 
Catalyst Loading= 0.1 gm 
Reactor Configuration= packed bed 
Figure 3.5 shows the activity test for titania based Platinum catalysts. The 
unpromoted Pt/TiO
2
 catalyst shows high activity in the beginning but drops rapidly. The 
cobalt promoted catalyst shows better activity. The conversion is 100% for first 5 minutes 
and then drops rapidly. 
III.1.3 Miscellaneous catalysts 
Few more catalysts were tested for CO oxidation are listed in table 3.3 
Table 3.3: Tests of miscellaneous catalysts 
Sr. No. Catalyst IC (%) t
drop
 (min) Notes 
1. Pd ? CeO
2
 - TiO
2
22%  1 wt% Pd 
2. CuO/CeO
2
10   
3.  Hopcalite 1 14%  Cu, Mn mixed oxide 
4. Co/TiO
2
2   
5. Mn/TiO
2
8   
6. CuCl 61  Adsorbant 
7. Hopcalite 
3
25%  Ru added ,without moisture 
8. Mn/SiO
2
8%   
 
None of these catalysts showed appreciable conversion for CO oxidation. 
 60 
0%
2%
4%
6%
8%
10%
12%
0 20 40 60 80 100 120 140
Time (Min)
C
O
 C
o
nv
er
s
i
on (
%
)
Cu/Ceria
Pd/Ce/Titania
Ru-Hopcalite
 
Figure 3.6: Activity Tests of Pd/Ce/Titania, Cu/Ceria and Ru-hopcalite 
Testing Conditions: 
Inlet CO Concentration = 2% 
Relative humidity= 90% 
Catalyst Loading= 0.1 gm 
Reactor Configuration= packed bed 
 61 
Figure 3.6 shows the activity test of Pd/Ce/TiO
2
, Cu/CeO
2
 and Ru-Hopcalite 
catalysts for low temperature oxidation. As seen here, none of these catalysts shows 
appreciable conversion of carbon monoxide.  
III.1.4 Commercial Catalysts and Sorbents 
0%
10%
20%
30%
40%
50%
60%
70%
0 204060801012014
Time (Min)
C
O
  co
n
v
e
r
si
o
n
 (
%
)
0
Hopcalite
CuCl adsorbent
 
Figure 3.7: Activity Test of Commercially Available CuCl Adsorbent and Hopcalite 
Catalyst 
Figure 3.7 shows the activity tests of commercially available CO removal 
products i.e. cuprous chloride adsorbent and hopcalites (Cu - Mn mixed oxide) catalyst. 
 62 
CuCl was very active for first few minutes and the activity dropped suddenly. This means 
the adsorbent has very short breakthrough time. The CO removal action happens to be by 
formation of Cu(CO)Cl complex as it is well known in literature. Hopcalites do not show 
appreciable activity under the given conditions. Hopcalites are known to deactivate very 
fast in presence of moisture as mentioned in chapter 1. 
 
III.2 Catalyst Selection 
Amongst the various catalysts tested Pt/Mn/SiO
2
 after calcinations and 
Pt/Co/Al
2
O
3
 with reduction as pre-treatment under flowing hydrogen at 250 
0
C were 
chosen to be suitable candidates for low temperature oxidation of carbon monoxide. 
Between these two catalysts, Pt/Mn/SiO
2
 was chosen to be the first candidate as it does 
not need any pre-treatment before using.  
 63 
III.3 Effect of Catalyst Making Process and Composition on the Performance of 
Pt/SiO
2 
 
III.3.1 Effect of Promoter: 
Figure 3.8 shows the comparison between activities of promoted and un-promoted 
Pt/SiO
2
 catalysts. It also shows the activity of Mn/SiO
2
 catalyst.  
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10203040506070
Time (Min)
C
O
 C
onv
er
s
i
on (
%
)
Pt/Mn/Silica
Pt/Silica
Mn/Silica
 
Figure 3.8: Comparison of promoted and un-promoted Pt/silica catalysts 
Conditions: 
Inlet CO concentration = 2500 ppm 
Relative Humidity= 90% 
 64 
Reactor configuration= microfibrous bed 
Promoter= cobalt (Co:Al = 0.4) 
As shown in the figure, unpromoted Pt/SiO
2
 loses activity quite rapidly. In the 
first 10 minutes CO conversion drops from 100% to 10%. On the other hand manganese 
promoted Pt/SiO
2
 catalyst shows much sustained activity.  
III.3.2 Effect of Promoter on the Activity of Pt/Al
2
O
3
: 
Figure 3.9 shows the enhancement in activity due to addition of promoter to Pt/Al
2
O
3
.  
0
200
400
600
800
1000
1200
1400
0 10203040506070
Time (Min)
O
u
t
l
e
t
 CO
 Co
n
c
.
 (
p
p
m
)
 
No promoter 
Promoted Catalyst 
Figure 3.9: Comparison between promoted and un-promoted Pt/Al
2
O
3
 catalysts, 
 65 
Conditions: 
Inlet CO concentration = 2500 ppm 
Relative Humidity= 90% 
Reactor configuration= microfibrous bed 
Promoter= cobalt (Co:Al = 0.4)
 66 
III.3.3 Comparison between Different Promoters: 
Figure 3.10 shows the comparison between Pt/SiO
2
 catalysts promoted by 
different transition metal promoters. As seen in the figure, among Mn, Co, Fe and Ce, Mn 
was found to be the best promoter. Co promoted catalyst also shows some activity in the 
beginning. Fe and Ce promoters do not enhance the activity appreciably.  
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10203040506070
Time (Min)
C
O
 C
onv
er
s
i
on
Pt-Mn-SiO2
Pt-Co-SiO2
Pt-Ce-SiO2
Pt-Fe-SiO2
 
Figure 3.10: Comparison of Various Transition Metal Promoters for Pt/SiO
2
 Catalyst 
Conditions:  
Inlet CO Concentration = 2% 
Relative humidity= 90% 
Catalyst Loading= 0.1 gm 
Reactor Configuration= packed bed 
 67 
 
 III.4 Effect of Operating Conditions on the Performance of Pt/Mn/SiO
2
This section discusses the effect by various operating conditions as well as 
catalyst making parameters and catalyst composition on the performance of Pt/Mn/SiO
2
 
catalyst.  
  
III.4.1 Effect of Temperature 
Figure 3.11 shows the effect of operating temperature on the performance of 
Pt/Mn/SiO
2
 catalyst. The temperatures studied are 20
0
C, 50
0
C and 100
0
C. 
 68 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60 70 80 90 100 110 120 130
Time  (min)
C
O
 C
o
n
v
er
s
i
on 
(
%
)
20 deg C
50 deg C
100 deg C
 
Figure 3.11: Effect of Operating Temperature on the Performance of Pt/Mn/SiO
2
 catalyst  
Conditions:  
Inlet CO Concentration = 2% 
Relative humidity= 90% 
Catalyst Loading= 0.1 gm 
Reactor Configuration= packed bed 
As shown in figure 3.11, the rate of deactivation of Pt/Mn/SiO
2
 catalyst decreases 
as temperature increases. This can be explained by enhancement in desorption of CO 
 69 
from the surface due to increase in temperature. Thus temperature helps in slowing down 
the deactivation process of the catalyst. As temperature is increased to 100
0
C, there is no 
deactivation shown by the catalyst.  
 
III.4.2 Effect of Inlet CO Concentration 
Figure 3.12 and 3.13 show the effect of inlet CO concentration on the activity of 
Pt/Mn/SiO
2
 catalyst. Figure 3.12, shows the effect of inlet CO concentration when the 
inlet concentration rages between 1% and 2%. The catalyst loading was 0.1 g. The 
reactor was operated in integral mode here. The reactor was operated close to a 
differential mode with much lower catalyst quantities and higher flow rates with lower 
concentrations of CO. The CO concentrations studies were 2500, 5000 and 7500 ppm 
shown in figure 3.13.  
 70 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1020304050607080901010120130
Time  (min)
%
c
onver
si
o
n
2% CO
1% CO
1.5% CO
 
Figure 3.12: Effect of Inlet CO Concentration on the Performance of Pt/Mn/SiO
2
 Catalyst 
Conditions:  
Inlet CO concentration = 2% 
Relative humidity= 90% 
Catalyst Loading= 0.1 gm 
Reactor configuration= packed bed 
 71 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 102030405060708090
Time (Min)
CO
 co
nv
er
si
on (
%
)
2500 ppm CO
5000 ppm CO
7500 ppm CO
  
Figure 3.13: Effect of Inlet CO Concentration on the Performance of Pt/Mn/SiO
2
 Catalyst  
Conditions:  
Inlet CO concentration = 2% 
Relative humidity= 90% 
Catalyst loading= 0.016 gm 
Reactor configuration= packed bed 
As seen in figure 3.12 and 3.13, at higher inlet concentration of CO, the 
deactivation of catalyst is much faster. This observation similar to the effect of 
temperature effect also shows the deactivation by irreversible adsorption of CO on the 
 72 
surface of the catalyst. All the catalysts here were used under dry condition. Hence 
moisture is not responsible for deactivation.  
 
III.4.3 Effect of Promoter Loading 
of promoter loading on the activity of manganese 
promot
Figure 3.14 shows the effect 
ed Pt/SiO
2
 catalyst.  
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 50 100 150 200 250 300
Time (Min)
C
O
 C
o
nv
er
s
i
on 
(
%
)
Mn:Si = 0.025
Mn:Si = 0.0125
Mn:Si = 0.0062
Mn:Si = 0.05
Mn:Si = 0.1
  
Figure 3.14: Effect of Manganese Concentration on Pt/Mn/SiO
2
 Performance 
Conditions:  
 73 
Inlet CO concentration = 2% 
cked bed 
anese loading of Mn:Si =0.025 shows the highest 
catalyti
I.4.4 Effect of Support on the Activity of Promoted Pt/SiO
2
e activity of manganese 
promot
Relative humidity= 90% 
Catalyst loading= 0.1 gm 
Reactor configuration= pa
As seen in the figure, mang
c activity. Concentrations above or below 0.25 molar solution of manganese salt 
do not yield good results. Thus these exists an optimum ratio of manganese to platinum.  
 
II
Figure 3.15 shows the effect of various supports on th
ed Pt/SiO
2
 catalyst. The supports were chosen due to different properties. Alumina 
being acidic, silica and carbon being neutral to Na-Y-zeolite being basic in nature.  
 74 
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 102030405060708
Time (min)
C
o
nv
e
r
s
i
on
 (
%
)
0
Pt/Mn/SiO2
Pt/Mn/C
Pt/Mn/Al2O3
Pt/Mn/TiO2
Pt/Mn/Na-Y Zeolite
  
Figure 3.15: Effect of Support on Performance of Promoted Pt Catalysts  
Conditions:  
Inlet CO Concentration = 2% 
Relative humidity= 90% 
Catalyst loading= 0.1 gm 
Reactor configuration= packed bed 
As observed in figure 3.15, silica supported catalyst has highest activity among all the 
supports tested.  
 
 
 75 
III.5 Catalyst Activity Details of Pt/Mn/SiO
2
 to Comply with EN 403 
This section shows the effect of various operating conditions to comply with 
accepted and proposed standards for CO removal. 
 
III.5.1 Effect of GHSV: 
Figure 3.18 shows the effect of GHSV on CO conversion. The face velocity was 
equivalent to 30 LPM flow rate through 500 cm
2
 area. The flow rate number comes from 
EN 403 standards as mentioned before. The area is maximum area that a person can have 
for fire escape hood.  
 
 76 
0
50
100
150
200
250
300
0 50 100 150 200 250
Time (Min)
C
O
 C
onc
en
t
r
at
ion 
(
p
p
m
)
29022 per hr
19348 per hr
14511 per hr
9674 per hr
7255 per hr
 
Figure 3.16: Effect of GHSV on the Performance of Pt/Mn/SiO
2
 Catalyst 
Conditions:  
Inlet CO Concentration = 2500 ppm 
Relative humidity= 90% 
Reactor Configuration= microfibrous bed 
As shown in figure 3.16, the conversion of CO drops rapidly as GHSV is 
increased. Time corresponding to 200 ppm of CO concentration is an important 
 77 
parameter according to EN 403 standards. This is the maximum time upto which the gas 
mask consisting of CO removal catalyst can be used without any health problems.  
Table 3.4 shows the permissible time for which the mask incorporating this 
catalyst can be used corresponding to each GHSV. 
Table 3.4: Gas Life Corresponding to GHSV 
Sr. No. GHSV Hr-1 Permissible Time (min) 
1 7255 210 
2 9674 98 
3 14511 90 
4 19348 39 
5 29022 29 
 
The maximum GHSV value of 29022 Hr-1 corresponds to a bed depth of 2 mm. 
Thus a layer of 2 mm think, when incorporated in a fire escape mask of 500 cm
2
 area, can 
provide protection from 2500 ppm carbon monoxide for 29 minutes. Thus this 
configuration passes the EN 403 standards.  
 78 
III.6 Intermediate Goal Setting 
  While this research was progressing towards escape masks meeting EN 403 
standards, a survey of commercial products was undertaken. One of the startling 
observations was that most of the escape masks had canisters and hoods instead of 
regular masking around the face. At the same time, more stringent CBRN and 
ANSI/ISEA 110-2003 standards were being proposed. Based on these two major 
happenings; following various goals of this research work were formulated. These goals 
are listed in Table 3.5.  
Table 3.5: Research Goals Based on Intermediate Findings and Survey 
Attribute Goal 
Catalyst activity time 60 minutes minimum 
Pressure drop four fold lower than commercial products (commercial 
products have a pressure drop of about 45 mm of water 
through the catalyst bed alone) 
Catalyst mass Order of magnitude reduction (current commercial products 
have catalyst mass of approximately 170 gm) 
Bed depth Order of magnitude reduction (Current commercial products 
have a bed depth of about 45 mm) 
Standards Ability to meet more stringent CO reduction standards 
which were in the proposal stages. 
Canister cross section area 85 cm
2
 maximum 
 
 79 
Based on these formulated goals and information available from these standards, 
various combinations of following operating variables and parameters became the sample 
space under consideration. The range of parameters and operating variables has been 
given in Table 3.6. 
Table 3.6: List of Operating Variables and Parameters with Range 
Operating variable/ parameter  Range 
Catalyst activity time 15, 30 45 and/or 60 minutes  
Pressure drop 70 mm of water (maximum permissible) 
Inlet CO concentration 1200 ? 10000 ppm 
Face velocity 6.88 ? 21.5 cm/sec 
Relative humidity > 90% 
Bed depth 4 mm 
Reaction mixture Carbon monoxide, air, moisture 
Temperature 25 
0
C 
Pressure 1 atm
 80 
III.7 Effect of Face Velocity on Activity of Pt/Mn/SiO
2 
Figure 3.17 and 3.18 show that the approximate bed depth should be minimum 1 
cm to meet EN 403 standard at higher face velocities. 
0
100
200
300
400
10203040506
Time (Min)
C
O
 c
oncent
r
a
t
i
on (
ppm
)
0
2500 ppm & 8 cm/sec
2500 ppm & 12 cm/sec
Fig 3.17: Effect of Face Velocity on Catalyst Activity (Pt/Mn/SiO
2
) 
Conditions: 
Catalyst: Pt/Mn/SiO
2
Relative Humidity = 90% 
Inlet CO Concentration = 2500 ppm 
Bed Depth = 1 cm 
 81 
0
100
200
300
400
102030405060
Time (Min)
C
O
 c
o
nce
n
t
r
at
i
o
n (
p
p
m
)
3600 ppm & 8 cm/sec
2500 ppm & 12 cm/sec
 
Figure 3.18: Activity Tests of Pt/Mn/SiO
2
Conditions:  
Catalyst: Pt/Mn/SiO
2
Relative humidity = 90% 
Bed Depth = 1 cm 
 82 
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
10203040506
Time (Min)
C
O
 co
ncen
t
r
a
t
i
on i
n
 pp
0
m
3600 ppm
2500 ppm
5500 ppm
 
Figure 3.19: Effect of Inlet CO Concentration on Activity of Pt/Mn/SiO
2
  
Conditions: 
Face velocity = 12 cm/sec 
Bed depth = 1 cm 
Relative humidity = 90% 
Figure 3.19 shows that the catalyst fails to meet CBRN general standard at a bed 
depth of 1 cm.
 83 
0
50
100
150
200
250
300
350
400
10203040506
Time (Min)
C
O
 c
onc
ent
r
a
t
i
on (
ppm
)
0
4 cm/sec
12 cm/sec
8 cm/sec
 
Figure 3.20: Effect of Face Velocity on Activity of Pt/Mn/SiO
2
Conditions: 
Inlet CO concentration= 2500 ppm 
Bed depth = 1 cm 
Relative Humidity = 90% 
Figure 3.21 shows the effect of bed depth to meet conditions corresponding to 
CBRN general standards. As seen form the figure, a bed depth of 1.5 cm is necessary to 
meet this standard. Some more stringent standards such as CBRN specific category 
 84 
would even need deeper bed. This would substantially increase the cost of these materials 
as well as pressure drop which directly corresponds to breathing resistance.  Primarily 
due to these considerations, testing and development of the second catalyst (Pt/Co/Al
2
O
3
) 
was undertaken.
0
200
400
600
800
1000
1200
10203040506
Time (Min)
C
O
 concent
r
a
t
i
on
 (
p
pm
)
0
1.5 cm
2 cm
1 cm
Figure 3.21: Effect of Bed Depth on Activity of Pt/Mn/SiO
2
Conditions: 
Inlet CO concentration = 3600 ppm 
Face velocity = 12 cm/sec 
Relative humidity = 90% 
 85 
 III.8 Testing of Pt/Co/Al
2
O
3 
for Meeting Different Test-protocols: 
As mentioned in chapter 1, as of now there are following different test protocols 
in consideration: 
? EN 403 (European Standards) 
? CBRN: (NIOSH standards) 
? ANSI/ISEA 110-2003 (ANSI/ISEA standards) 
Out of these, EN 403 standards are the only ones in practice. Rest of the standards are 
in various stages of proposal. This section deals with testing CO oxidation catalysts under 
conditions pertinent to each test protocol. The figures shown in this section are 
corresponding to EN403 tests only. All the results pertaining to meeting NIOSH- CBRN 
and ANSI/ISEA 110-2003 #6, #7 are documented in appendix B.  
 
III.8.1 EN403 
Following are the different test conditions for EN403 standards. 
Inlet CO Concentration  = 2500, 5000, 7500, 10000 ppm 
Face Velocity    = Min 5.88 cm/sec (30 LPM into 85 cm
2
) 
Temperature   = 22 
0
C 
Bed Thickness   = 4 mm 
Relative Humidity   = 90% 
Figure 3.22 shows performance of CO oxidation catalyst at 2500 ppm inlet and 12.5 
cm/sec face velocity. 
 
 86 
0
50
100
150
200
0 1020304050607080
Time (Min)
O
u
t
l
et
 C
O
 C
o
nc.
 (
p
pm
)
4 mm
 
Figure 3.22: Catalyst Test for EN 403 (2500) 
Conditions: 
Face velocity = 12.5 cm/sec 
Temperature = 22 
0
C 
Bed cross section = 20.26 cm
2
Bed Depth = 4 mm 
Note: The detector logs data at the rate of 20 per minute, for clarity of graphs, all the data 
points are not shown in figures 3.22 through 3.25. 
 87 
Figures 3.23, 3.24, and 3.25 show catalyst testing for meeting 5000, 7500 and 10000 ppm 
inlet CO condition at 5.88 cm/sec face velocity as stated in the EN 403 document 
respectively. 
0
50
100
150
200
0 20 40 60 80 100
Time (Min)
O
u
t
l
et
 C
O
 C
onc
 (
ppm
)
 
Figure 3.23: Catalyst Test for EN 403 (5000) 
Conditions: 
Face velocity = 5.88 cm/sec 
Temperature = 22 
0
C 
Bed cross section = 20.26 cm
2
 88 
0
50
100
150
200
0 20 40 60 80 100 120
Time (Min)
Ou
tl
e
t
 C
O
 C
o
n
c
 (
p
p
m
)
 
Figure 3.24: Catalyst Test for EN 403 (7500) 
Conditions: 
Face velocity = 5.88 cm/sec 
Inlet CO conc. = 7500 ppm 
Temperature = 22 
0
C 
Bed cross section = 20.26 cm
2
 
 89 
0
50
100
150
200
20406080
Time (Min)
Ou
t
l
e
t
 CO Co
nc
 (
p
pm)
10
 
Figure 3.25: Catalyst Test for EN 403 (10000) 
Conditions:  
Face velocity = 5.88 cm/sec 
Inlet CO conc. = 10000 ppm 
Temperature = 22 
0
C 
Bed cross section = 20.26 cm
2
As observed from figures 3.22, 3.23, 3.24 and 3.25 the outlet CO concentration 
follows a peculiar trend of rising immediately and falling off. This trend can be attributed 
 90 
to adiabatic rise in temperature since CO oxidation is an exothermic reaction. Due to this 
increased temperature, the self-inhibition of CO reduces thereby increasing the 
conversion. CO oxidation on Pt catalyst has been known as self-inhibition type of 
reaction in literature. 
This observation has been supported by temperature profile in figure 3.26. As 
seen from the figure, the temperature of the reaction mixture increases rapidly to close to 
adiabatic flame temperature in first three minutes.  
22
27
32
37
42
47
52
0246810
Time (Min)
Tem
per
at
ur
e (
0
C)
12
 
Figure 3.26: Adiabatic Temperature Rise for CO Oxidation Reaction 
 91 
Conditions: 
Inlet CO conc = 3600 ppm 
Face velocity = 6.8 cm/sec 
Catalyst bed depth = 4 mm 
Relative humidity = 90% 
The calculation of adiabatic flame temperature has been separately attached as 
appendix C. As the temperature increases, the conversion increases and outlet 
concentration of carbon monoxide falls. The gap in measured temperature and adiabatic 
flame temperature is due to heat loss as effect of improper insulation. The reactor had not 
been insulated to closely imitate the conditions as faced by the catalyst bed in actual 
escape mask. One hypothesis that supports this observation could be centered on 
formation of multiple steady states.  
 
III.9 Multiple Steady States in CO Oxidation: 
There can be different reasons for formation of multiple steady states such as (i) 
thermokinetic interaction [3.1], (ii) isothermal coupling between a self-inhibition reaction 
and either intra-paticle diffusion limitations [3.2] or intraparticle transport limitations 
[3.3],  (iii) coupling among two or more steps in the overall reaction scheme [3.4].  
It has long been known that, exothermic catalytic reactions follow non-linear dynamics. 
This primarily happen because of two different driving forces working in opposite of 
each other.  
For a simple reaction; 
A ? B 
 92 
Rate of a reaction can be written as; 
r
A
 = k*C
A
where 
k = A*exp(-E
a
/RT) 
where 
A = Arrhenius constant 
Ea = Activation energy 
R = Universal gas constant 
T = temperature 
k = Reaction rate constant 
r
A
 = Rate of reaction 
C
A
 = Concentration of reactant A. 
As temperature goes-up due to exothermic nature of the reaction, rate of reaction 
increases due to increasing k. At the same time, concentration of A starts decreasing 
thereby forcing the rate to slow down. As a result of these two opposite acting forces, 
multiplicity results in the reaction. Multiplicity is a result of formation of multiple steady 
states in a reaction. 
This can be represented by following schematic of heat, generation and removal 
curves. 
 
 93 
 
 
T
in
  
G(T), R(T) 
Figure 3.27: Schematic Representation of Heat Generation and Heat Removal Curves as 
Functions of Inlet Temperature 
As observed from figure 3.27, the S shaped curve is a typical representation of a 
heat generation curve. The lines on the graph correspond to heat removal curves for that 
particular inlet temperature.  At steady state heat removal rate and heat generation rate 
should be same. The intersection of these two plots would be steady states corresponding 
to that inlet temperature.  
Moreover carbon monoxide reaction has also been known to follow the 
Langmuir-Hinshelwood Kinetics. The rate expression can be written as; 
 94 
2
)1(
*
AA
AA
A
CK
Ck
r
+
=  
Where 
K
A
 = Equilibrium adsorption constant 
Thus this reaction can be classified as one that is self-inhibition type. At high CO 
concentrations, the denominator is large compared to numerator and hence the reaction 
rate goes down. One more reason for CO oxidation being self-inhibition type is 
irreversible adsorption of CO on the surface of platinum. This phenomenon has been 
investigated by several researchers in the past. 
These reasons and observations led to following experimental as well as 
theoretical investigations.  
 
 95 
III.9.1 Investigations of Multiplicity in Low Temperature CO Oxidation 
32
37
42
47
52
57
62
67
72
77
82
2000 3000 4000 5000 6000 7000
Inlet CO Concentration (ppm)
G
a
s
 T
e
m
per
at
ur
e 
0
C
Ignition
Extinction
 
Three Solutions 
One Solution 
Figure 3.28: Cross Section of the Bifurcation Set in the Plane of Gas Temperature and 
CO Feed Volume Fraction 
Conditions: 
Inlet CO conc = 3600 ppm 
Face velocity = 6.8 cm/sec 
Catalyst bed depth = 4 mm 
Relative humidity = 90% 
 96 
As seen in figure 3.28, the ignition temperature increases monotonically with inlet 
CO concentration. The graph of extinction temperature vs. CO fraction has a local 
maximum. The region with two stable states is bounded between the two graphs. Under 
the extinction branch, only one solution exists which means only one stationary state 
exists. 
Similar results were observed by Harold and Luss [3.5] who performed oxidation 
of carbon monoxide on the surface of single pellet of Pt/Al
2
O
3
. Multiple steady states 
were observed for all CO concentration in the range of 0.6 ? 8% and gas temperatures in 
the range of 20 -250 
0
C. The multiplicity was observed by measuring temperature of the 
center of pellet as a function of gas temperature and CO mole fraction. At most only two 
stable stationary states were found for any given set of operating conditions. It could be 
deduced from studying the bifurcation map that thermokinetic coupling and intraparticle 
transport limitations were affecting the system. 
Numerous researchers attempted in different capacities to model the multiple 
steady states behavior of CO oxidation reaction.  
Harold and Luss [3.5] attempted to fit the multiplicity behavior of CO oxidation 
using a bimolecular Langmuir-Hinshelwood rate expression, interparticle and 
intraparticle transport resistances, and an estimate for the intraparticle activity profile. 
The kinetic model was found adequate to describe the trends but could not predict 
quantitative behavior.  
Herz and Marin [3.6] attempted to fit the rate data of CO oxidation on platinum 
surface. The findings indicate that reaction models with no CO adsorption equilibrium 
 97 
assumption fit the rate data more correctly compared to Langmuir-Hinshelwood rate 
expression that assumes adsorption equilibrium. 
Harold and Garske [3.7] proposed various models that can fit experimental rate 
date at various conditions. It has been demonstrated that the common three step model 
consisting of reversible CO adsorption, dissociative oxygen adsorption and a Langmuir 
reaction step can predict qualitatively the reaction behavior under ultra high vacuum 
conditions. It could predict the shape of the multiplicity region in the catalyst 
temperature ? CO pressure plane.  A new method has been proposed in which parameter 
space has been divided into regions in which different shapes of temperature-CO pressure 
bifurcation maps would be observed. Five different models have been proposed.  
Zhdanov and Kasemo [3.8] proposed that effect of oxide formation on the surface 
of platinum should be taken into account to accurately describe the shape of bifurcation 
map in CO oxidation. According to authors, at ultra high vacuum and high CO pressure 
conditions it may be sufficient to use Langmuir-Hinshelwood model to predict bistability 
but it would be necessary to take into account oxide formation under oxygen rich 
environment at atmospheric pressure. Monte Carlo simulations performed could predict 
the shape of bifurcation map qualitatively under oxygen rich environment. These 
predictions were found to be in agreement with STM studies of CO oxidation on 
platinum. 
 98 
III.9.2 Hysteresis Effects: 
This section deals with observations and explanation of hysteresis phenomenon in low 
temperature CO oxidation reaction. 
30
40
50
60
70
80
90
100
0 2000 4000 6000 8000 10000 12000
Inlet CO Conc. (ppm)
C
O
 C
onver
si
on (
%
)
Increasing Conc.
Decreasing Conc.
 
Figure 3.29: Hysteresis Phenomenon in Low Temperature Oxidation of Carbon 
Monoxide 
Conditions: 
Face Velocity = 12.5 cm/sec 
Catalyst bed depth = 4 mm 
 99 
Relative Humidity = 90% 
As seen in figure 3.29, the inlet CO concentration has been changed from 2500 to 
11000 ppm. As inlet CO concentration increase from 2500 to 5500 ppm, the conversion 
remains constant 100 %. As the inlet concentration increases beyond 6000 ppm, the 
conversion falls down to 85% and keeps on decreasing with increasing CO concentration. 
When the CO concentration is decreased from 11000 ppm to 2500 ppm, the conversion-
inlet CO concentration follows a different route. The conversion for concentrations 
between 2500 and 11000 is much lower compared to corresponding conversion on the 
increasing concentration plot. On the decreasing concentration arm of the graph, CO 
conversion keeps on decreasing even after decreasing inlet CO concentration down to 
6000 ppm. As the concentration falls below 6000 ppm, conversion starts to increase, and 
attains a 100% level at 2500 ppm, thereby resuming its original position.  
This particular phenomenon is a clear indication of occurrence of multiple steady 
states in low temperature CO oxidation for a promoted precious metal catalyst. Similar 
results have been observed by many researchers in the past for platinum as catalyst.  
R Jaree et al [3.9] report formation of hysteresis and extinction waves in catalytic 
CO oxidation caused by reactant concentration change.  The reaction was studied in 
packed bed configuration of Pt/Al
2
O
3
. A model had been proposed to explain this 
phenomenon.  
Bykov et al [3.10] suggest that Langmuir-Hinshelwood mechanism can be used to 
predict multiplicity of steady states in CO oxidation.  
Abramova et al [3.11] take into account the surface non-uniformities of the 
catalyst to propose a model to explain low temperature CO oxidation at low CO 
 100 
concentrations. This work has been proposed as an extension of ZBG (Ziff, Gulari, 
Barshad) model.  
Haaland et al [3.12] relate the formation of hysteresis loops in CO oxidation to 
CO island formation. FTIR studies performed to observe the ratio of intensities of the 
absorption bands due to linear and bridge bonded CO. This ratio was found to be constant 
thereby suggesting CO island formation. The hysteresis phenomena in both CO reaction 
probability and CO surface coverage were found to be inversely related. This also 
suggests blocking of active sites by carbon monoxide on the Pt surface.  
Salanov et al [3.13] explained the nature of hysteresis in oxidation of carbon 
monoxide on platinum. With excess oxygen in the reaction mixture formation of surface 
oxide of platinum takes place thereby that in turn leads to changing surface properties of 
platinum and hence the nature of the Hysteresis loop. 
 101 
 III.9.2.1 Steady State Temperature Hysteresis: 
0
10
20
30
40
50
60
70
80
0 2000 4000 6000 8000 10000 12000
Inlet CO Conc. (ppm)
O
u
t
l
et
 Tem
p
.
 (
deg C
)
Measured Temp
Adiabatic flame temp
 
Fig 3.30: Steady State Temperature Hysteresis 
Conditions: 
Temperature = 22
0
C 
Face velocity = 12 cm/sec 
Catalyst: Pt/Co/Al
2
O
3
Relative humidity = 90% 
 
 102 
Figure 3.30 shows thermal hysteresis in CO oxidation. As seen from the figure, 
the steady state temperature rises as a function of inlet CO concentration up-to 6500 ppm 
value. As the concentration increased beyond 6500 ppm, the temperature starts dropping 
rapidly and keeps on reducing even if the concentration has been decreased to about 6500 
ppm. When concentration has been decreased further to about 5000 ppm, the temperature 
starts rising and resumes its original value at 2500 ppm inlet concentration. Thus the 
reaction follows an altogether different path while the concentration decreases. 
 103 
III.10 Effect of Moisture: 
One of the very interesting observations in this research work was ?enhancement 
in catalyst activity in presence of moisture?. 
This section explains the effect of moisture content in the feed on activity of the 
catalyst. As observed in various experiments during the progress of this research, 
moisture has been found to be enhancing the activity of the catalyst. Figure 3.31 shows 
the study of hysteresis phenomenon in the absence of moisture. Comparison of this figure 
with figure 3.29 shows that on the decreasing branch of concentration, catalyst behavior 
is radically different. Same can be mentioned for increasing concentration branch of the 
hysteresis map. In presence of moisture, conversion remains at 100% for the 
concentration range of 2500 ? 5500 ppm. Under dry conditions, conversion drops well 
below 90% when inlet concentration increases beyond 3000 ppm. For the decreasing 
concentration branch, in presence of moisture, conversion resumes at 100% once the 
concentration is decreased to 2500 ppm whereas under dry conditions the conversion 
remains at a much lower value of 68%.   
 104 
III.10.1 Hysteresis under Dry Conditions 
30
40
50
60
70
80
90
100
0 2000 4000 6000 8000 10000 12000
Inlet CO Conc. (ppm)
C
O
 C
onv
er
s
i
on 
(
%
)
Increasing Conc.
Decreasing Conc.
 
Fig 3.31: Hysteresis Phenomenon in Absence of Moisture 
Conditions: 
Temperature = 22
0
C 
Face Velocity = 12 cm/sec 
Catalyst: Pt/Co/Al
2
O
3
Relative Humidity = 0% 
 
 105 
III.10.2 Effect of Moisture on Hysteresis 
30
40
50
60
70
80
90
100
0 2000 4000 6000 8000 10000 12000
Inlet CO Conc. (ppm)
C
O
 C
o
nve
r
s
i
on (
%
)
Relative Humidity = 90%
Bone Dry Air
 
Figure 3.32: Effect of Moisture on Hysteresis 
Conditions: 
Temperature = 22
0
C 
Face velocity = 12 cm/sec 
Catalyst: Pt/Co/Al
2
O
3
Relative humidity = 90% 
 
 106 
Figure 3.32 shows the comparison of catalyst activity under dry and wet feed 
conditions. The conversion is much higher for a given CO concentration. It has also been 
confirmed that the activity difference between two feed conditions is reversible.  
III.10.3 Effect of Moisture on Pt/Mn/SiO
2
0
50
100
150
200
250
300
350
400
16400 16600 16800 17000 17200 17400 17600
Time (sec)
C
O
 con
c.
 (
ppm
)
 
Figure 3.33: Effect of Moisture on CO Oxidation Process - Reversible Nature of Activity  
Conditions: 
 Inlet CO concentration = 2500 ppm 
Relative humidity at the beginning = 90% 
 107 
Face velocity = 8 cm/sec 
Catalyst = Microfibrous entrapped Pt/Mn/SiO
2
As shown in figure 3.33, the original feed introduced while testing the activity of 
this catalyst had relative humidity of about 90%. During the course of the reaction, when 
the feed nature changed from wet to dry, conversion of carbon monoxide keeps on 
dropping. As soon as the feed nature resumed back to original, the conversion started 
increasing and reached its original value. Same experiment was repeated several times to 
confirm the behavior. From this behavior it can be observed that, moisture helps the 
catalyst to regain its activity by reducing the surface coverage of carbon monoxide which 
tends to poison the catalyst. Figure 3.34 shows a comparison of activity under dry 
conditions and with feed having about 90 % relative humidity.  
 
 108 
0
50
100
150
200
250
300
350
400
450
2040608
Time (Min)
C
O
 c
onc
 (
p
pm
)
0
 
Figure 3.34: Effect of Moisture on Catalyst Activity 
Conditions: 
Inlet CO Concentration = 2500 ppm 
Face Velocity = 4 cm/sec 
Catalyst = Pt/Mn/SiO
2 
 109 
As seen from figures 3.32, 3.33 and 3.34, it is clear that presence of moisture is 
very beneficial for low temperature oxidation of carbon monoxide. This can happen due 
to various different reasons. A vast body of literature suggests different mechanisms by 
means of which water can participate in the reaction and help enhance the catalyst 
activity for oxidation.  
Lavin and Jackson [3.14] investigated the effect of moisture on carbon monoxide 
oxidation. The conclusion reached was hydroxyl ion coming out of water dissociation 
reacts with carbon monoxide to produce carbon dioxide and sets a proton free.  
OH + CO = CO
2
 + H 
This reaction is exothermic to the tune of 24 Kcal which helps the temperature 
rise hence the reaction. The yield of CO
2
 increased as the moisture content of the feed 
was increased everything else remaining same.  
Same effect has been observed by Allers et.al. [3.15]. While measuring angular 
and velocity distribution of carbon dioxide desorbing as reaction product of carbon 
monoxide oxidation on Pt (1, 1, 1), four different peaks corresponding to CO
2
 desorption 
were observed (? ?
3
, ?
2
, ?
1
). These four different peaks could be related to different 
mechanisms of CO
2
 production. ? was ascribed to Where ? ?CO
2
 coincides with the O
2
 
desorption from and the dissociation of pure chemisorbed molecular oxygen, and thus 
indicates a reaction channel coupled with desorption and dissociation of O2, ?
1
-CO, 
corresponds to the reaction path investigated before by many researchers and is most 
likely due to the reaction at the boundaries of ordered CO and oxygen islands. The 
formation of ?
2
, ?
3
 peaks was less clear at this point of time. Bergeld et al [3.16] 
performed experimental investigation of low temperature CO oxidation on Pt(1, 1, 1) in 
 110 
presence of water and studied TPR. From observation of TPR spectrum an autocatalytic 
route has been explained. The mechanism proposed consists of following stages: 
2O
ad
 + CO
ad
 + 2H
2
O
ad
 ? O
ad
 + CO
ad
 + 3OH
ad
? CO
2g
 + O
ad
 + 2H
ad
 + 2OH
ad
H
ad
 + OH
ad
 ? H
2
O
ad
  ? H
2
O
g
OH
ad
 + OH
ad
 ? H
2
O
g
 + O
ad
H
ad
 + O
ad
 ? OH
ad
The overall autocatalytic mechanism suggested was; 
CO
ad
 + OH
ad
 ? CO
2ad
 + H
ad
This reaction leads to the formation of one more OH
ad
 and hence the reaction becomes 
autocatalytic. This mechanism also explained the origin of ?
2
 and ?
3
 peaks of earlier 
observed CO
2
 desorption. 
Xue-Qing Gong and P. Hu [3.17] studied the catalytic role of water using density 
function theory (DFT).  The CO oxidation barrier under dry condition is 0.8 eV. In the 
presence of water this barrier reduces to 0.33 eV. The reduction in barrier happens 
primarily because of H-bonding between H in water and the O at the transition state (TS) 
that stabilizes the TS. Secondly, CO can readily react with OH with a barrier of 0.44 eV. 
Thirdly in the H
2
O + OH mixed phase, CO can be easily converted to CO
2
 through two 
steps; CO reacts with OH to form COOH that in turn loses one H to a nearby H
2
O 
molecule and at the same time an H in water transfers to a OH leading to CO
2
 formation.  
The conclusions of this research include; 
 111 
i. The reaction CO + O + H
2
O ? CO
2
 + H
2
O is not responsible for low temperature CO 
oxidation, even though the barrier of 0.33 eV seems to be in accordance with CO
2
 
desorption temperature 
ii. The possibility that CO oxidation at boundaries of CO domains and H
2
O + OH mixed 
phases being a major source of CO
2
 desorption is negligible 
iii. It is likely that CO oxidation occurring in the H
2
O + OH mixed phase is the major 
source for CO
2
 formation at low temperature. The various elementary steps involved are; 
2H
2
O + O ? 2OH + H
2
O ? (1) 
CO + OH ? COOH ? (2)  
COOH + H
2
O + OH ? CO
2
 + H
2
O + H
2
O ? (3) 
In reaction (3), H
2
O plays a bridge role thereby passing a H from COOH to a OH. Thus 
water promotion could be divided into two classes; class I, H-bonding between the H of 
H
2
O and an electronegative species such as O in the reaction of CO + O + H
2
O ? CO
2
 + 
H
2
O, water can stabilize the transition state of the of the reaction and hence reduce the 
barrier. Class II, Water first dissociates and then H and OH participate in the reaction. As 
a result the reaction mechanism changes and a favored route is formed via OH formation. 
 112 
III.10.4 Water Promotion Effect on CO oxidation over Promoted Pt/Al
2
O
3
For the promoted catalyst, transition metal oxide acts as a carrier for oxygen and 
platinum surface adsorbs carbon monoxide as well as water, and may produce OH ions. 
The OH ions formed may help CO
2 
desorption as described above. Also only water and 
CO are competing for active sits on platinum as against the well known competitive 
inhibition of the active sites by carbon monoxide over oxygen.  
In addition, carbon monoxide has tendency to form islands on Pt surface. Haaland 
and Williams [3.12] studied CO island formation effect on the surface of platinum using 
Fourier transform infrared spectroscopy. The ratio of intensities of the absorption bands 
due to both linear and bridge bonded CO was constant during oxidation. These 
observations were interpreted as resulting from CO island formation. 
Our hypothesis here is that, water helps break the CO islands on the Pt surface, 
thereby reducing active site loss. Hence moisture can be helpful for low temperature CO 
oxidation reaction as observed. 
 113 
III.11 Self-sustained Oscillations 
0
50
100
150
0 100 200 300 400 500 600
Time (Min)
O
u
tlet
 C
O
 c
o
nc
 (
p
pm
)
 
Figure 3.35: Self-sustained Oscillations in CO oxidation 
Conditions:  
Inlet CO concentration = 2500 ppm 
Face velocity = 8 cm/sec 
Bed depth = 1 cm 
Catalyst: microfibrous entrapped Pt/Mn/SiO
2
Moisture: 3% (Relative humidity ~ 90-100%) 
 114 
Approximate temperature rise = 7-8 
0
C 
As seen in figure 3.35, self-sustained oscillations have been observed in the low 
temperature oxidation of carbon monoxide. There could be various reasons why self-
sustained oscillations can be present in this reaction. 
Lagos et al [3.18] modeled the behavior of heterogeneously catalyzed CO 
oxidation on Pt surface. Experimental data indicate presence of three different regimes, 
steady state, oscillatory and a quasi-chaotic regime. The explanation of various regimes 
has been provided by means of phase diagram analysis.  
McCarthy et al [3.19] explain various reasons why oscillations could be present in 
CO oxidation. The reasons could be classified in two broad categories (i) thermal 
behavior and (ii) intrinsic kinetics that characterizes this reaction. Thermal oscillations 
happen due to inter-phase temperature gradients. Within intrinsic kinetics; either two 
different reactions could be rate limiting or autocatalytic reaction step exists. During 
isothermally performed it was concluded that the intrinsic kinetics contain two different 
rate determining steps as possibility of autocatalytic reaction did not exist. The two 
different rate determining steps take over the process dynamically as surface 
concentration of CO changes from low to high and vice-versa. Rate equation of the 
following form could be taken into account to explain such an observation. 
 
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
+
?
?
?
?
?
?
?
?
=
21
/
1
*
1
1
KCcoCk
R
co
o
 
 
 115 
Thus at low CO partial pressures linearity is exhibited while at high CO partial pressures, 
negative order is evident. Maxima can be observed.  
Turner et al [3.20] studied oscillations in carbon monoxide oxidation over 
polycrystalline Pt wire at atmospheric pressure. The oscillations were observed in both 
temperature of Pt wire and concentration of carbon dioxide formed over a wide range of 
CO concentration (0.001 < P
co
/PO
2
 < 0.045), temperature range of 150
0
C to 350
0
C. These 
oscillations were believed to occur between two branches of Langmuir-Hinshelwood 
reaction mechanism. Slow formation of sub-surface oxide and further reductions was 
believed to be the reason of oscillations. When chemisorbed oxygen reacts with Pt 
surface, some of it gets incorporated under the surface and starts formation of oxide layer 
thereby deactivating the surface. When this surface gets exposed to carbon monoxide, it 
reduces back to Pt metal active site. Thus the activation-deactivation triggered by surface 
oxide formation led to oscillations. A model proposed called the ?oxide model? described 
qualitatively the oscillatory behavior. 
Collins et al [3.21] proposed ?carbon model? to explain temporal oscillations 
observed in carbon monoxide oxidation. Combinations of Langmuir-Hinshelwood 
reaction steps with activation-deactivation due to carbon formation was assumed to be the 
cause of oscillations. Coupling between carbon removal by reaction with gaseous oxygen 
and carbon removal by reaction with chemisorbed oxygen happening at comparable rates 
led to oscillations. This model could qualitatively represent experimental data. 
Ladas et al [3.22] linked oscillations formation to surface faceting by in-situ 
LEED studies. They proposed a mechanism in which facet formation on a CO covered 
1X1 surface and the removal of facets by a thermal reordering process get coupled to 
 116 
cause kinetic oscillations. An increase in the period of oscillations was observed as extent 
of faceting increased.
 Tsai et al [3.23] observed oscillations in Pt catalyzed CO oxidation between low, 
intermediate and high activity. The oscillations were direct effect of coupling between 
two different catalytic loops called as coupled catalytic oscillators. 
Imbihl et al [3.24] explained formation of autonomous kinetic oscillations in CO 
oxidation over Pt.  The main hypothesis was, surface defects induce oscillations.  The 
reaction was studies over a single crystal of Pt under isothermal conditions at very low 
pressure.  
Note: Figure 3.35 does not show all the readings on the curves for clarity 
purposes. 
 117 
III.12 Comparison of Same Particle Size Catalyst in Packed and Microfibrous 
Entrapped Configuration 
This section details the observations of anomalous activity behavior of the catalyst 
when in microfibrous configuration. It was observed that the activity for same catalyst 
loading and operating condition was higher in microfibrous beds compared to equivalent 
packed bed and operating conditions. Following four different bed configurations were 
selected: 
i. Packed bed 
ii. Diluted packed bed with alpha-alumina as diluent 
iii. Layered packed bed with layers of microfibrous materials between packed 
beds 
iv. Microfibrous bed  
Configuration number ii and iii were added to test for following effects if observed;  
a. Thermal behavior of reaction differs vastly in packed bed and diluted packed bed 
mode 
b. Due to addition of layers of microfibrous bed the gas flow channeling was taken 
care of, which otherwise can happen in packed beds. 
Figure 3.36 shows schematic of different configurations for activity comparison.
 118 
 
  
 
Diluted  
Packed Bed 
Packed Bed 
 
 
  
 
Microfibrous Bed
 
 
 
Layered Packed 
Bed 
 
Figure 3.36: Schematic of Different Bed Configurations  
 119 
 
0
10
20
30
40
50
60
70
80
90
100
0 10203040506070
Time (Min)
C
onv
er
si
on of
 C
O
 (
%
)
Microfibrous Bed
Diluted Packed Bed
Layered Packed Bed
Packed Bed
 
Fig 3.37: Comparison of Catalyst Activity for Different Bed Configurations 
Conditions: 
Inlet CO Concentration = 2500 ppm 
Relative Humidity = 90% 
Reactor Diameter = 0.5 cm 
 120 
Experimental conditions for the demonstrations were; temperature of 25?C at 
atmospheric pressure and particle size of 150-250 ?m.  The microfibrous media for both 
of the CO oxidation tests used nickel fibers of 4 and 8 ?m in a weight ratio of 1:3.  The 
nickel fibers, particulates and cellulose are cast into a preform by wetlay papermaking 
technique.  The resulting preform is sintered at 950?C in H
2
 atmosphere for 30 minutes.  
The sintered media contains approximately 18 vol. % particulates, 1.6 vol. % fibers and 
ca. 80 % bed voidage.  Both of the CO oxidations of sintered media were done in an 8 
mm I.D. tube with bed depth of 1 cm.  The packed beds of catalyst powder were tested in 
a 4 mm ID tube.  Each test employed the same amount of catalyst powder.  Other 
conditions for low temperature oxidation of CO were as follows: Transition metal 
promoted platinum on silica gel catalyst (Pt-M
n
-SiO
2
), inlet CO concentration of 2500 
ppm, GC detection limit is 40 ppm CO, oxygen concentration of 20% with balance 
nitrogen, face velocity of 8 cm/sec, relative humidity of 86%.  The CO oxidation catalyst 
deactivates due to reactant inhibition, so conversion as a function of time data is shown as 
Figure 3.37.   
Conversion of CO by manganese promoted platinum on silica at low temperature 
is shown In Figure 3.37.  Conversion is plotted against time since the reaction is 
deactivated by reactant poisoning.  The results for the three different packed beds of 
catalyst particles are all about the same.  At ten minutes after the reaction was started the 
conversion for the three packed beds are about fifteen percent and for the microfibrous 
mesh it is about ninety-five percent.  If a rate constant is calculated from these data it 
indicates that the reaction rate for the catalyst in the microfibrous mesh is about 1.8 times 
 121 
higher than for the packed beds.  The microfibrous mesh catalyst also shows less 
deactivation during the experiment than the packed beds.   
Studying computational fluid dynamics of flow and reactions over microfibrous 
beds has been proposed to be one way to explain the anomalous increase in activity of the 
catalyst. It has been hypothesized that, observing residence time distribution within 
microfibrous bed should throw some light on this phenomenon. Another hypothesis is 
that of enhancement in external mass transfer due to presence of wires. A comprehensive 
experimental analysis followed by theoretical explanation would explain this effect.  
 122 
CHAPTER IV 
 
ANALYSIS OF COMMERCIAL PRODUCTS 
 
 This chapter deals with testing and analysis of commercially available products 
for fire escape applications. All these products meet existing EN403 standards. These 
products served as intermediate bench marks while the research was progressing. 
The products selected for analysis are: 
1. Drager parat C ? 
2. Essex plus 10? 
3. Sundstrom SR 77? 
Products 1 and 2 are Hopcalite based, while third mask is precious metal monolith 
based. All these products carry a price-tag in the neighborhood of USD 170.   
 123
IV.1 Commercial Product I: Drager? Fire Escape Mask Details 
Components: 
1. Hood 
2. Canister 
a. Particulate filter (HEPA) 
b. Hopcalite 
c. Particulate filter 
3. Half Mask 
4. Visor 
5. Exhalation valve 
Table 4.1 lists all the technical, performance and product details of Parat c?. 
Table 4.1: Details of Parat C? 
Sr. No. Attribute Value 
1 Canister Weight 262.2 gm 
2 Canister Cross-sectional Area 71 cm
2
3 Catalyst Hopcalite 
4 Catalyst Weight 173 gm 
5 Canister depth 45 mm 
6. Breakthrough time 15 minutes 
 
Figure 4.1 shows the drager? mask done by a researcher. As seen here the orange color 
hood goes around the face and head. The mask also has a half face visor. Air breathed in 
 124 
passes through the canister into the half face mask. While breathing out, the air flows 
through the exhalation valve on the left side of the face.  
 
Figure 4.1: Drager Escape Mask Done  
 125 
 
Figure 4.2: Drager Canister 
  
Figure 4.3: Drager Canister Opened 
 126 
Figures 4.2 and 4.3 show pictures of canister as it is and when opened 
respectively. The canister is a metallic housing that incorporates Hopcalite, HEPA and 
another particulate filter inside. The catalyst bed configuration is packed bed.  
 
IV.2 Commercial Product II : Essex? plus 10? Details 
 
Figure 4.4: Essex plus 10? Mask Done 
Figure 4.4 shows the Essex plus 10 mask done by a researcher. The design of this 
product is markedly different from other commercial hoods. The whole hood is made up 
of transparent material hence the mask does not need a visor. The front side of the 
canister shown in figure 4.5 is a rectangular housing. The back side of the canister is a 
cylindrical housing that holds the monolith for CO removal and copper heat sink in place 
is shown in figure 4.6. The front side of the canister houses charcoal cloths for removal of 
other gases. Figure 4.7 shows the monolith for CO removal. 
 127 
 
Picture 4.5: Essex Canister Front View 
 
Figure 4.6: Essex Canister Back Side 
 
 128 
 
Figure 4.7: Essex plus10? Carbon Monoxide Oxidation Monolith  
Components: 
1. Hood 
2. Fire retardant Nomex? layer 
3. Canister 
a. Activated carbon coated cloth: 21 layers 
b. Precious Metal monolith 
c. Copper monolith: heat sink (7 layers of perforated copper discs riveted 
together 
4. Exhalation valve 
Table 4.2 lists all the technical, performance and product details for Essex plus 10?. 
 129 
 
Table 4.2: Technical Details of Plus 10? 
Sr. No. Attribute Value 
1 Canister weight 244.6 gm 
2 Weight of precious metal monolith 56.03 gm 
3 Catalyst Precious metal monolith 
4 Diameter of monolith 76 mm 
5 Channel diameter 1 mm 
6 Height of monolith 20 mm 
7 Weight of heat sink 168 gm 
8 Diameter of heat sink 65 mm 
9 Heat sink height 8 mm 
10 Breakthrough time 15 minutes 
 
 130 
IV.3 Commercial Product III: Sundstrom? SR 77? Product Details 
The product details for this product had been obtained through personal communications 
with a research scientist from Sundstrom of Sweden [4.1] 
The SR77? consists of following: 
1. Hood 
2. Visor 
3. Canister 
4. Half mask 
5. exhalation valve 
Table 4.3 lists all the technical, performance and product details for SR 77? 
Table 4.3: Product details of SR 77?  
Sr. No. Attribute Value 
1 Total weight 590 gm 
2 Canister diameter 96 mm 
3 Canister height 45 mm 
4 Total height 48.5 mm 
5 Activated carbon type BR1 NC " from Suthcliff" 78 cc 
6 Activated carbon type ER2 "from Suthcliff" 18 cc 
7 "Drier" Molekyl Sil? 66 CC 
8 CO converter Moleculite 140 CC 
9 Total weight including canister/top 2946 gm 
10 Breakthrough time >35 minutes 
 131 
IV.4 Commercial Product Testing 
This section shows the details of commercial products tested for catalyst activity 
for carbon monoxide removal. The products tested are Drager Parat C and Essex plus 10.  
IV.4.1  Testing of Drager? Canister 
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20 25 30 35
Time (Min)
O
u
t
l
et C
O
 C
o
nc
.
 (
p
pm
)
 
Figure 4.8: Drager Parat C? test for EN 403  
Test Conditions: 
Testing standards: EN 403 
CO concentration: 2500 ppm 
 132 
Inlet flow rate:  30 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
As seen in figure 4.8, the canister gives nineteen minutes of gas life before it deactivates. 
It is rated for 15 minutes of gas life. 
0
200
400
600
800
1000
1200
1400
1600
1020304
Time (Min)
O
u
t
l
et C
O
 C
o
nc
.
 
(
p
pm
0
)
 
Figure 4.9: Drager Parat C? Test for EN 403  
Test Conditions: 
 133 
Testing standards: EN 403 
CO concentration: 5000 ppm 
Inlet flow rate:  30 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
As seen in figure 4.9, the canister gives about 26 minutes of gas life before it 
deactivates. Higher concentration of CO for the same flow rate further increases the 
temperature adiabatically thereby increasing the activity of the catalyst.  
 134 
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20
Time (Min)
O
u
tl
e
t
 C
O
 C
o
n
c
. (p
p
m
)
 
Figure 4.10: Drager Parat C? Test for CBRN General  
Test Conditions: 
Testing standards: CBRN (general category) 
CO concentration: 3600 ppm 
Inlet flow rate:  64 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
 135 
As shown in figure 4.10, this canister fails to meet the 15 minute test as specified in 
CBRN general document.  
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20
Time (Min)
O
u
t
l
e
t
 C
O
 C
onc. (
ppm
)
 
Figure 4.11: Drager Parat C? Test for ANSI 110-2003 #6 
Test Conditions: 
Testing standards: ANSI #6 
CO concentration: 3000 ppm 
Inlet flow rate:  93 LPM 
Temperature:  22
0
C 
 136 
Pressure:  1 atm 
Relative humidity: 90% 
As seen in figure 4.11, drager canister fails to meet the 15 minutes test conditions as 
specified in ANSI/ISEA 110-2003. 
 137 
IV.4.2  Testing of Essex Plus10? Monolith 
This section shows the test results of Essex plus10? monoliths.  Figure 4.12 
shows the results of testing of monolith for EN 403 standards. As seen in the figure, 
monolith shows a behavior similar to microfibrous materials. In the beginning the outlet 
CO concentration increases and then falls down to almost zero. The monolith was stable 
running for about 1 hour. This product has been rated for 15 minutes gas life.  
0
50
100
150
200
250
204060801
Time (Min)
O
u
t
l
e
t
 C
O
 C
o
nc 
(
ppm
0
)
 
Figure 4.12: Essex? Monolith Test for EN 403 
Conditions: 
 138 
Testing standards: EN 403 
CO concentration: 2500 ppm 
Inlet flow rate:  30 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
Test for ANSI #6 Standards 
0
200
400
600
800
1000
1200
1400
1600
102030405
Time (Min)
O
u
tl
e
t
 C
O
 C
o
n
c
 (p
p
m
0
)
 
Figure 4.13: Testing of Essex? Monolith for ANSI #6 
 139 
Conditions: 
Testing standards: ANSI #6 
CO concentration: 3000 ppm 
Inlet flow rate:  93 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
Figure 4.13 shows the test results for ANSI #6 standards. The concentration rises 
in the beginning upto approximately 1200 ppm. The monolith fails to meet the 
instantaneous requirement of 200 ppm outlet CO. 
Figure 4.14 and 4.15 show results of CBRN general category test and inspired air 
temperature tests respectively. As seen from these figures the monolith fails to meet both 
these standards.  
 140 
0
200
400
600
800
1000
1200
1400
1600
0 1020304050607
Time (Min)
O
u
t
l
et
 C
O
 C
o
nc (
p
pm
0
)
 
Figure 4.14: Testing of Essex? Monolith for CBRN General Category 
Conditions: 
CO concentration: 3600 ppm 
Inlet flow rate:  64 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
 141 
0
50
100
150
200
250
300
2040608
Time (Min)
O
u
t
l
et
 C
O
 C
o
nc (
p
pm
0
)
 
Figure 4.15: Testing of Essex? Monolith for Inspired Air Temperature Test 
Conditions: 
CO concentration: 1200 ppm 
Inlet flow rate:  40 LPM 
Temperature:  22
0
C 
Pressure:  1 atm 
Relative humidity: 90% 
 
 142 
IV.5 Comparison of CM
3
 (MiniCOT) Catalyst with Commercial Catalysts 
Table 4.4 shows the comparison of performance attributes of MiniCOT with parat 
C? and SR 77?.  
Table 4.4: Comparison of MiniCOT attribute with commercial products 
Attribute Parat C? SR 77?  MiniCOT 
Standards Passed EN 403 EN 403 EN 403 
Area 71 cm
2
73 cm
2
85 cm
2
Total Catalyst Loading 173 gm  
(Hopcalite) 
182 gm 
(Carbon = 58 gm) 
(Mol Sieve = 40 gm) 
(Hopcalite = 84 gm) 
16 gm 
Total Bed Depth 4.5 cm 4.5 cm 4 mm 
Pressure Drop thro? the 
bed 
> 40 mm of H
2
O > 40 mm of H
2
O 8 mm H
2
O* 
Time 19 min 35 min > 60 min 
 
As seen in the tables, with regards to the original goals, following achievement 
were made possible: 
1. Order of magnitude reduction in catalyst loading 
2. Four fold reduction in pressure drop 
3. Gas life of canisters > 1 hr 
4. Order of magnitude reduction in bed depth 
*The pressure drop tests are discussed in details in chapter 5 (Technology Transfer). 
 143 
CHAPTER V 
 
TECHNOLOGY TRANSFER 
 
After catalyst development and activity testing on laboratory scale it was found 
that catalyst met all the imposed standards for gas mask canister testing. As previously 
discussed the only standards that are actually in practice are EN 403.  
The next logical step in the development process was to transfer the technology 
from bench to actual scale. The preparation of microfibrous wet-lay preform part had 
already been commercialized for a similar application before under the supervision of 
Intramicron Inc. This wet lay process corresponds to block I in figure 5.6. Sintering has 
also been scaled-up for a previous application which is represented by block III in figure 
5.6. All the previous applications corresponded to development of adsorbents. MiniCOT 
technology transfer would be the first technology for catalytic applications. Some of the 
unique things pertaining to catalyst preparation were the primary challenges in the 
technology transfer activity. Reductions in cost of manufacturing and batch times are 
parts of the technology transfer process.  
 144
Other challenges present were catalyst aging studies and breathing resistance 
offered by the bed at higher flow rates. This chapter has been divided into following 
major sections: 
1. Catalyst aging studies 
2. Pressure drop tests (breathing resistance) 
3. Process analysis to reduce costs and time 
4. Identification and elimination of possible redundancies in process 
 145
V.1 Accelerated Aging Tests: 
This section shows the results of accelerated aging tests of this catalyst.  
Accelerated aging tests needed to be performed for following two reasons: 
1. Final use of the catalyst would be in a fire escape mask that also contains other 
sorbents to remove acid gases, organic vapors etc. 
2. Shelf life is a very important parameter since this face mask would be used at one 
time only, being anytime after manufacturing. 
0
50
100
150
200
250
300
350
400
450
500
550
1020304050607
Time (Min)
O
u
t
l
et
 C
O
 C
onc
 (
ppm)
0
Fresh catalyst
aging in presence of TEDA/C
 
Figure 5.1: Comparison of Catalyst Activity with Aged Catalyst in Presence of TEDA/C, 
at 70
0
C for 48 hrs 
 146
Conditions: 
Inlet CO concentration = 3600 ppm 
Relative humidity =          90% 
Bed cross section =       20.26 cm
2
Figure 5.1 shows the comparison of activity of fresh catalyst to a catalyst that was 
aged for 48 hours in presence of TEDA/C (Tri-ethylene Diamine/carbon) which is a 
common sorbent for removal of organic vapors, acid gases etc. As seen from the figure, 
the activity of the catalyst aged in presence of TEDA/C drops drastically in first few 
minutes. The observation can be supported by deactivation of catalyst due to TEDA 
vapors.  
 
 147
0
50
100
150
200
250
300
350
400
450
500
550
1020304050607
Time (Min)
O
u
t
l
et
 
C
O
 C
onc
 (
ppm
)
0
Fresh catalyst
aging in presence of 2 cm URC
 
Figure 5.2: Comparison of Catalyst Activity with Aged Catalyst in Presence of URC, at 
70
0
C for 48 hrs 
Conditions: 
Inlet CO concentration = 3600 ppm 
Relative humidity =          90% 
Bed cross section =       20.26 cm
2
 
 148
Figure 5.2 shows the comparison of activity of catalyst aged in presence of URC 
(universal respirator carbon) to that of fresh catalyst. The aged catalyst shows some 
deactivation but not significant. The catalyst can still perform well to meet EN 403 
standards. The outlet CO concentration after 1 hr was below 100 ppm.  
0
50
100
150
200
0 1020304050607
Time (Min)
O
u
t
l
et
 C
O
 C
onc (
ppm
)
0
Fresh catalyst
aging in presence of TEDA/C at RT
 
Figure 5.3: Comparison of Catalyst Activity with Aged Catalyst in Presence of 
ASZM/TEDA, at 22
0
C for 48 hrs 
Conditions: 
Inlet CO concentration = 3600 ppm 
 149
Relative humidity =          90% 
Bed cross section =       20.26 cm
2
Figure 5.3 shows comparison of catalyst aged in presence of TEDA/C at room 
temperature to that of fresh catalyst. The deactivation of catalyst was not significant 
showing that the catalysts deactivates only when heated in presence of TEDA/C. 
0
50
100
150
200
250
300
350
400
1020304050607
Time (Min)
O
u
t
l
et
 C
O
 C
onc (
ppm
)
0
Fresh catalyst
aging of catalyst alone
 
Figure 5.4: Comparison of Fresh Catalyst Activity with Aged Catalyst at 70
0
C for 48 hrs 
Conditions: 
Inlet CO concentration = 3600 ppm 
 150
Relative humidity =          90% 
Bed cross section =       20.26 cm
2
Figure 5.4 shows the comparison of activity of catalyst aged all by itself in 
presence of air to that of fresh catalyst. The loss in activity is insignificant. 
 151
V.2 Pressure Drop Measurements 
Pressure drop is a very important parameter in the design of face masks since it 
directly corresponds to breathing resistance. The total pressure drop permitted by NIOSH 
under CBRN standards is 70 mm of water at 85 LPM flow rate through the canister. 
MiniCOT has a pressure drop of 8 mm of water which is extremely low compared to 
what has been permitted. All the same, this pressure drop is about 4 times lower 
compared to commercial products. 
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
Face Velocity (cm/sec)
P
r
e
s
s
u
re
 D
r
o
p
 (m
m
 
H
2
O)
8 mm
6 mm
4 mm
 
Figure 5.5: Pressure Drop through MiniCOT Catalyst as a Function of Face Velocity for 
Various Bed Thicknesses 
 152
V.3 Process Analysis: 
For the sake of technology transfer the catalyst preparation process was divided 
into different blocks as shown in figure 5.6. Each block then was carefully analyzed for 
both cost as well as time taken by that particular block and any other challenges that 
existed. The basis for all the analysis here considered was 4 mm, 85 cm
2
 disk. 
 
 153
  
Wet Lay 
Drying I 
Sintering 
Pre-Oxidation 
Impregnation I 
Drying II 
Impregnation II Calcination I 
Drying III 
Calcination II 
End 
Start 
Reduction 
Figure 5.6: Process Flow Diagram of Catalyst Preparation
 154
V.3.1 Wet-lay: 
Material take-off (MTO): 
Table 5.1 shows the material take-off calculation for wet-lay process stage. The major 
cost carrying items for this stage are Ni fibers. 
Table 5.1: Material Take-off for Wet-lay stage 
Material Quantity (gm) Cost ($)
4 micron Ni fibers 1.5  0.13 
8 micron Ni Fiber 4.5  0.39 
Cellulose 2.0 -- 
Alumina 12 0.01
 
Time:  
Material weighing:   5 minutes 
Blending:  10 minutes 
Material preparation: 10 minutes 
V.3.2 Drying: 
Material:   product of stage I 
Time:    24 hours (@100 
0
C) 
V.3.3  Pre-oxidation 
Material: product of stage II 
Time:  30 min. 
V.3.4  Sintering 
Material:    product of stage III 
 155
Time:    30 minutes 
Furnace start-up time:  8 hrs 
Furnace shutdown time: 8 hrs 
V.3.5  Impregnation I 
Table 5.2 shows the material take-off calculation for impregnation I stage. Cobalt 
solution adds to the cost of preparation of material in this stage. 
Table 5.2: Material Take-off for Impregnation I: 
Material Quantity (gm) Cost ($)
Sintered preform 17.2 gm - 
Cobalt Solution 19.05 ml (0.28 gm Co) 0.14 
 
Time: 60 minutes 
V.3.6:  Drying II 
Material:   Cobalt impregnated sintered preform 
Time:    24 hours (@100 
0
C) 
V.3.7: Calcination I 
Material:  Product of stage VI 
Time:  4 hours  
V.3.8:  Impregnation II 
Table 5.3 shows the material take-off calculation for impregnation II stage. 
Platinum solution adds to the cost of preparation of material in this stage. This has been 
the most expensive material so far in to the process. 
 
 156
Table 5.3: Material Take-off for Impregnation II: 
Material Quantity (gm) Cost ($)
Sintered preform(Cobalt impregnated) 17.2 gm - 
Platinum Solution 16.5 gm (0.56 gm Pt) 33.00 
 
Time: 60 minutes 
V.3.9:  Drying III 
Material:   platinum impregnated sintered preform 
Time:    24 hours (@100 
0
C) 
V.3.10: Calcination II 
Material:  Product of stage IX 
Time:  4 hours  
V.3.11: Reduction 
Material:  Final catalyst 
Time:  3 hours  
 157
V.4 Identification of Rate-determining Stages: 
The catalyst making process for lab-scale preparation has been documented in 
chapter 2. For large scale manufacturing, following challenges existed: 
1. High cost of making the catalyst 
2. Longer batch times 
3. Use of Continuous Sintering Furnace 
 
V.4.1 Cost of Catalyst  
It was quickly realized that prime cost-driver for catalyst making here is the cost 
of platinum pre-cursor. (Current recipe: 5 % platinum on Al
2
O
3
 (Co:Al = 0.34)) 
Table 5.4 shows the details of cost of platinum solution. The calculations are 
based on 85 cm
2
 disc with 4 mm thickness. This is equivalent to meeting EN403 
standards. 
Table 5.4: Cost calculations for platinum 
Sr. No. Attribute Value  
1 Area of 6" disk (cm
2
) 182.32 
2 Alumina for 3X6" disk-2 mm (gm)   12.00
3 Alumina for 85 cm
2
, 4 mm layer (gm)   11.19
4 Platinum content (gm) 0.56
 Price of 3.4 % Pt solution ($/ml) 2.00
 Solution required making one prototype (ml) 16.47 
 Price of Pt solution for one prototype 33.00
 
 158
The prime motive in technology transfer as far as cost goes, was to bring this cost 
down to half as a first milestone. Hence personal communications were initiated with 
bulk manufacturers of platinum solution. Following modified costing as shown in table 
5.5 is possible after getting a response from Johnson Matthey?. 
V.4.1.1  Costing of MiniCOT Catalyst for Meeting EN 403 Standards (4 mm 
Bed Thickness) 
Table 5.5 shows the costing of material after Johnson Matthey? response: 
Table 5.5: Modified costing of MiniCOT 
Sr. No. Attribute Value  
1 Area of 6" disk (cm
2
) 182.32
2 Alumina for 3X6" disk-2 mm (gm) 12.00
3 Alumina for 85 cm
2
, 4 mm layer (gm) 11.19
4 Platinum content (gm) 0.56
Johnson Matthey (50 gm/L solution)      (50 - 100 Gal range) 
1 Pt bulk price ($/troy ounce)*** 856.00
2 Pt bulk price ($/gm)                              27.52
3 Fabrication cost* ($/troy ounce) 22.00
4 Fabrication cost ($/gm)  0.71  
5 Total cost $/gm of Pt content           28.23
6 For 4 mm layer ($)         15.79  
Johnson Matthey (50 gm/L solution)      (higher quantities) 
1 Pt bulk price ($/troy ounce)*** 856.00
 159
Sr. No. Attribute Value  
2 Pt bulk price ($/gm)                              27.52
3 Fabrication cost* ($/troy ounce) 15.00
4 Fabrication cost ($/gm) 0.48
5 Total cost $/gm of Pt content           28.00
6 For 4 mm layer ($)         15.67  
 
Notes: 
*Fabrication cost has been defined as a charge that Johnson Matthey? counts to convert 
a given quantity of platinum into corresponding salt for catalyst preparation purposes.  
***: This number can be found real time at www.platinum.matthey.com (changes as 
bullion price) 
 160
V.4.2  Batch Cycle Time Reduction 
As seen in the process documented in chapter 2, drying was the highest time 
consuming process on a laboratory scale. Two different drying cycles together took 48 
hours of drying time. Various experiments were performed to reduce this time as much as 
possible. First set of experiments consisted of cutting the drying time by half. The 
following table indicates the loss of moisture (weight) comparison of the precursor. It 
was observed that the weight loss in both drying cycles, viz. 12 hours and 24 hours was 
exactly same. Hence in conclusion drying time could be reduced in half. Further 
reduction in drying time could reduce the batch times further as it was the still the slowest 
step in the process. 
The catalyst support was dried for 1.5 hours at 150
0
C. The observations on weight 
(moisture) are detailed in table 5.6. 
Table 5.6: Weight Loss Comparison 
Weight (gm) Reading 
Sample 1 Sample 2 Sample 3 
Weight before drying 34.8 33.9 34.45 
Weight after drying 29.54 28.8 29.3 
Weight loss 5.26 5.1 5.15 
 
Sample 3 was dried in the conventional way, 24 hours at 100
0
C. As seen from the 
table, the total moisture loss in either case remained same. Hence the final drying time 
reached was 1.5 hours. 
 161
 
V.4.3 Use of Continues Sintering Furnace 
In the lab-scale preparation of catalyst; the maximum size of the catalyst that 
could be obtained was limited by the size of the sintering furnace. The maximum cross-
sectional area for one catalyst disc would be 5 cm
2
. The end-application demands 
minimum cross-section on the disk to be 85 cm
2
. The continuous sintering furnace was 
used to sinter multiple disks of 182 cm
2
 area each. The results on the final product, that 
is, the sintered pre-cursor for catalyst preparation, were similar to lab-scale preparation. 
 
V.4.4  Elimination of Stages 
Conventional microfibrous carrier preparation process contains ?pre-oxidation 
step?. The purpose of this stage is to burn the cellulose that has been used as a binder 
while wet-lay processing of these wires. The pre-oxidation is performed at 400
0
C in 
presence of 5% oxygen for about 30 minutes. Handling of materials become tedious since 
very fragile material coming out of pre-oxidation stage needs to be carried to sintering 
furnace. Hence some experiments were performed to check if this stage can be eliminated 
during the technology transfer process. Few pre-forms were sintered without pre-
oxidation. After impregnation and pre-reduction as described previously, these catalysts 
were tested. Figure 5.7 shows that, there was very little to no change in activity of this 
catalyst when compared to activity of the catalysts that were prepared out of pre-oxidized 
preforms. However this needs to be tested for further activity sustenance by performing 
more demanding tests before finalizing of elimination of pre-oxidation stage.  
 162
0
50
100
150
200
250
300
350
400
0 1020304050607
Time (Min)
O
u
t
l
et
 C
O
 C
o
nc
 (ppm)
 
0
 
Figure 5.7: Testing of Catalyst after Elimination of Pre-oxidation Stage- Sample I 
Conditions: 
Standards tested for:   EN403 
Inlet CO Concentration: 2500 ppm 
Relative Humidity:  90 % 
Bed Depth:   4 mm 
 163
0
50
100
150
200
250
300
350
400
0 1020304050607
Time (Min)
O
u
t
l
et
 C
O
 C
o
nc
 (
p
pm
0
)
 
Figure 5.8: Testing of catalyst after Elimination of Pre-oxidation Stage- Sample II 
Conditions: 
Standards tested for:   EN403 
Inlet CO concentration: 2500 ppm 
Relative humidity:  90 % 
Bed depth:   4 mm 
 
 164
CHAPTER VI 
 
CONCLUSION AND RECOMMENDATIONS FOR FUTURE WORK 
 
This chapter lists the various intermediate conclusions drawn out of the present 
research work and general future direction for this research project based on current 
information. 
VI.1 Conclusion 
This section details the various conclusions drawn our of this research project. The 
conclusions can generally be divided as following: 
1. Catalyst 
2. Process 
3. Improvement in existing products 
4. Technology transfer 
 
VI.1.1  Catalyst 
          An extensive number of catalysts have been proposed and investigated by many 
researchers for the low temperature oxidation of carbon monoxide in hydrogen, as 
described in Chapter I.  
 
 165
VI.1.2  Process 
Chapter 3 described catalyst screening, effect of various catalyst making 
conditions and parameters on the activity of the catalyst. Originally two catalysts were 
candidates for this reaction but finally cobalt promoted Pt/Al
2
O
3
 was found to be the most 
active catalysts over the whole gamut of conditions. A considerable thought has been 
given to reaction ignition-extinction behavior, which is well known in literature.  The 
benign effect of moisture on the catalyst activity has also been studies in details. The 
hysteresis maps have been plotted and described in details. A well-known self-sustained 
oscillations behavior has been observed under pertinent sets of conditions.  It has also 
been observed that, the reactivity of catalyst bed, in microfibrous configuration was much 
higher compared to packed bed of equivalent particle size.  
 
VI.1.3  Improvement in Existing Products 
Chapter IV describes the testing of commercial products and internal bench-
marking. Two commercial products were tested in detail, Drager?, Parat C? and Essex? 
Plus10?. Also relevant analysis of Sundstrom SR77? was done. Following conclusions 
were reached based on comparison of MiniCOT with commercially available products 
mainly Parat C? and SR 77?; 
i. Order of magnitude reduction in catalyst loading 
ii. Four fold reduction in pressure drop 
iii. Gas life of canisters > 1 hr 
iv. Order of magnitude reduction in bed depth 
 
 166
VI.1.4 Technology Transfer: Cost Issue 
The technology transfer process described in chapter V, details how manufacturing 
cost could be reduced as phase I of the transfer. The platinum cost was reduced by half to 
$15.67 for scale-up. The time of processes such as drying has been reduces considerably. 
The microfibrous carriers have been prepared using the continuous belt-furnace to test for 
effect of scaling-up. Very little change has been observed. Studies have been performed 
to eliminate the pre-oxidation process so that material handling could be easier. Materials 
are extremely fragile between pre-oxidation and sintering process. Hence handling 
becomes an important issue. Pressure drop tests have been performed to test the 
suitability of this material. As described in chapter V, the pressure drop through the bed 
of microfibrous material was four times lower than that of equivalent packed bed. 
 167
VI.2 Recommendations for Future Work 
This section describes in-brief, the general future research direction for this project. 
1. Further reduction in catalyst loading 
2. Smooth and integrated manufacturing process 
3. Alternate carrier materials: primarily polymers 
4. Integration of MiniCOT with other sorbents to remove other contaminants from 
fire gases 
5. Packaging 
6. Computational fluid dynamic and residence time distribution studies in 
microfibrous beds  
 
VI.2.1  Further Reduction is Catalyst Loading 
As of now, catalyst, primarily platinum metal forms a large fraction of 
manufacturing cost of the canister. Hence it is very important to lower the loading of 
platinum to further reduce the cost of material. 
 
VI.2.1.1 Exploitation of Ignition-Extinction Behavior 
This can be done by taking advantage of layering characteristics of microfibrous 
bed. Microfibrous materials can be layered every millimeter with different particle and 
fiber size. 
Smaller catalyst particles can ignite the reaction by increasing the temperature 
locally since the heat capacity is very low. If front part of the bed can be packed with 
 168
extremely small particle size layer, and then increasing the particle size gradually, 
following advantages can be realized: 
i. Front of the bed ignites and hence drives the reaction faster due to temperature rise. 
ii. Back part of the bed, having larger particle size structure, can offer resistance to 
deactivation. The top layer can be deactivated quickly but the inner of the catalyst still 
remains active.  
Thus layering of particles can help not only this reaction, but any reaction that has 
tendency to show multiplicity behavior.  
 
VI.2.1.2  Modeling of Ignition-Extinction Phenomenon 
Considerable work has been done by various researchers on modeling of ignition-
extinction behavior and hysteresis. This body of literature can be further utilized to come-
up with a suitable model for promoted platinum/alumina catalyst. This model can also be 
helpful in predicting layering of various particle sizes. 
 
VI.2.1.3  Analytical & Surface Chemistry Studies 
A qualitative reaction model could be proposed with the help of surface 
chemistry. The enhancement of reaction rate due to moisture could be further studied to 
quantify the effect. 
Analysis should also be performed to study catalyst structure and quantitatively 
find out catalyst structure. Preliminary results from SEM/EDS are shows in appendix D. 
 
 
 169
VI.2.2  Smooth and Integrated Manufacturing Processes 
The various manufacturing processes involved can be further smoothened out and 
integrated. This would mainly consist of customizing available set-up. The customization 
shall consist of making trays that can hold optimum number of catalyst disks. The whole 
tray then can be moved from stage to stage. The efficiency at the impregnation stage 
should be improved to minimize losses. Other ideas for integrating the process could be 
grabbed from bench-marking against processes of current extrudate manufacturers. 
 
VI.2.3 Customizing Process to Fit Available Hardware 
As described under catalyst preparation section in Chapter II, the current process 
incorporates calcination at 400
0
C for about 4 hours. However the existing equipment that 
Intramicron? has possession of is convective ovens that can heat only upto 300
0
C. Hence 
catalysts were prepared at these conditions. Following figures show the comparison of 
catalyst activity with calcination temperature of 300
0
C to the conventionally prepared 
catalyst. It can be observed that, the activity of the catalyst remains same.   
 
VI.2.4  Alternate Carrier Material 
The current fiber material used for making MiniCOT is nickel. This can be 
replaced with polymer, a material which is a much cheaper option. Following sets of 
experiments should be performed in order to test the suitability of polymer materials for 
this application. 
i. Preparing catalyst as powder: 
 170
Catalyst needs to be prepared in the powder form before entrapping it into 
polymer fibers as catalyst needs to pass through calcination process at 400
0
C. Polymer 
fibers are temperature intolerant about 120 ? 130
0
C. 
ii. Testing catalyst activity for water tolerance: 
The wet-lay process used for making catalyst carriers consists of preparing the 
material in deep water column. Hence catalyst activity tests need to be performed after 
dipping the catalyst in water and drying. 
iii. Catalyst reduction at lower temperature: 
The catalyst pre-reduction process needs to be performed at a temperature lower 
than 120
0
C. If catalyst does not activate enough, sets (ii) could be repeated for pre-
reduced catalyst. 
 
VI.2.5  Integration of MiniCOT with Other Sorbents  
As stated in various standards already, the canister should be capable of removing 
a lot of other contaminants viz., HCl, HCN, Propenal, NH
3
, cyclohexane, phosgene etc. 
For example the requirements for EN 403 are listed in Table 6.1. 
Table 6.1:  Other gas requirements for EN403 
Test Agent Test gas Conc. In air (ppm) Breakthrough Conc. (ppm) 
Propenal (acrolein) 100 10.5 
Hydrogen Chloride (HCl) 1000 5 
Hydrogen Cyanide 400 10 
 
 171
All the gases listed in the table above could be removed using carbon sorbents. 
Universal Respirator Carbon (URC) entrapped in polymer microfibrous materials can be 
a good candidate material for Propenal, HCl and HCN removal. 
A layer of this material can be placed up-front of MiniCOT to remove these 
contaminants. Some of the ageing studies have already been performed (reported in 
Technology transfer Chapter) in presence of URC. More extensive tests could be 
performed in this direction to make an integrated microfibrous canister. 
 
VI.2.6  Packaging 
The packaging issues need to be resolved as these materials may not be used for 
few years and they should still be active. The shelf-life for existing commercial canisters 
is about seven years. MiniCOT in integrated fashion should be able to offer a similar 
shelf-life. 
 
VI.2.7  Computational fluid dynamic and residence time distribution studies in 
microfibrous beds 
As described in chapter 3, the activity of the catalyst observed in microfibrous 
configuration is much higher compared to packed bed configuration for the same particle 
size. This needs to be studied further to explain the behavior. Computational fluid 
dynamic studies and residence time distribution studies can be useful tools to explain this. 
A simple tracer study where the inlet tracer is a delta function and monitoring the outlet 
tracer concentration as a function of time can throw some light on flow patterns within 
micro-fibrous bed. This phenomenon can also be modeled using models, such as 
 172
dispersion model to further explain the behavior. Simple heat transfer experiments can 
also be performed to compare rates of heat transfer of different geometries.  
 
VI.2.8 Heat Transfer Experiments 
Simple heat transfer experiments can be performed to monitor the radial rise of 
temperature inside a microfibrous bed. At time t = 0, increase the temperature of the 
reactor wall to a higher value and then monitor the center temperature. A profile of 
temperature as a function of time and radius can be compared with that of packed bed to 
find out the difference between the rates of heat transfers. Same set of experiments can be 
performed for axial heat transfer. This phenomenon can also be modeled in terms of 
various resistances. 
 173
REFERENCES 
[1.1] S. Yoon, S. Macdonald, R. G. Parrish, Journal of American Medical Association, 
279, 685-687(1998). 
[1.2]  S. Katz, G. McCaa, A. Barth, Bureau of Mines Bulletin 14, 1924 
[1.3] D. Parker, G. McCaa, E. Denny, Bureau of Mines Handbook,139 (1923) 
[1.4] S.Katz, Industrial and Engineering Chemistry 6 555-557(1925) 
[1.5] EN 403, European Standards for Testing of Respiratory Protective Devices, EN 
403: 1993 
[1.6] CBRN, NIOSH Standards 2003 
[1.7] ANSI/ISEA 110-2003 ANSI Standards 2003 
[1.8] A. Lamb, W. Bray, J. Frazer, Ind. Eng .Chem., 12, 213-221 (1920) 
[1.9] J. Almquist, W. Bray, J.  Am. Chem. Soc., 45 2305-2322 (1923) 
[1.10] A. Lamb, W. Vail, J.  Am. Chem. Soc, 47 123 ? 142 (1925) 
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 178
APPENDICES
 179
Appendix A: QRAE? datalog sample 
 
1. Screen shot of ProRAE suite?  
 
 
 
2. Above File in the text format: 
 
Instrument: QRAE+ (PGM2000)                           Serial Number: 
408301 
User ID: 00000001           Site ID: 00000001            
Data Points: 47             Data Type: Avg            Sample Period: 60 
sec 
Last Calibration Time: 10/25/2004 11:14 
=======================================================================
============= 
Gas Type:                       CO(ppm)    H2S(ppm)      OXY(%)        
NONE 
High Alarm Levels:               1500.0       250.0       -----       -
---- 
Low Alarm Levels:                1435.0       200.0       -----       -
---- 
=======================================================================
============= 
Line#       Date  Time          CO(ppm)    H2S(ppm)      OXY(%)        
NONE 
 180
=======================================================================
============= 
   1  03/08/2005 14:59             38.9         0.0       -----       -
----  
   2  03/08/2005 15:00              2.2         0.0       -----       -
----  
   3  03/08/2005 15:01              0.6         0.0       -----       -
----  
   4  03/08/2005 15:02              0.3         0.0       -----       -
----  
   5  03/08/2005 15:03              0.2         0.0       -----       -
----  
   6  03/08/2005 15:04              0.1         0.0       -----       -
----  
   7  03/08/2005 15:05              0.1         0.0       -----       -
----  
   8  03/08/2005 15:06              0.0         0.0       -----       -
----  
   9  03/08/2005 15:07              0.0         0.0       -----       -
----  
  10  03/08/2005 15:08              0.0         0.0       -----       -
----  
  11  03/08/2005 15:09              0.0         0.0       -----       -
----  
  12  03/08/2005 15:10              0.0         0.0       -----       -
----  
  13  03/08/2005 15:11              0.0         0.0       -----       -
----  
  14  03/08/2005 15:12              0.0         0.0       -----       -
----  
  15  03/08/2005 15:13              0.0         0.0       -----       -
----  
  16  03/08/2005 15:14              0.0         0.0       -----       -
----  
  17  03/08/2005 15:15              0.0         0.0       -----       -
----  
  18  03/08/2005 15:16              0.0         0.0       -----       -
----  
  19  03/08/2005 15:17              0.0         0.0       -----       -
----  
  20  03/08/2005 15:18              0.0         0.0       -----       -
----  
  21  03/08/2005 15:19              0.0         0.0       -----       -
----  
  22  03/08/2005 15:20              0.0         0.0       -----       -
----  
  23  03/08/2005 15:21              0.0         0.0       -----       -
----  
  24  03/08/2005 15:22              0.0         0.0       -----       -
----  
  25  03/08/2005 15:23              0.0         0.0       -----       -
----  
  26  03/08/2005 15:24              0.0         0.0       -----       -
----  
 181
  27  03/08/2005 15:25              0.0         0.0       -----       -
----  
  28  03/08/2005 15:26              0.0         0.0       -----       -
----  
  29  03/08/2005 15:27              0.0         0.0       -----       -
----  
  30  03/08/2005 15:28              0.0         0.0       -----       -
----  
  31  03/08/2005 15:29              0.0         0.0       -----       -
----  
  32  03/08/2005 15:30              0.0         0.0       -----       -
----  
  33  03/08/2005 15:31              0.0         0.0       -----       -
----  
  34  03/08/2005 15:32              0.0         0.0       -----       -
----  
  35  03/08/2005 15:33              0.0         0.0       -----       -
----  
  36  03/08/2005 15:34              0.0         0.0       -----       -
----  
  37  03/08/2005 15:35              0.0         0.0       -----       -
----  
  38  03/08/2005 15:36              0.0         0.0       -----       -
----  
  39  03/08/2005 15:37              0.0         0.0       -----       -
----  
  40  03/08/2005 15:38              0.0         0.0       -----       -
----  
  41  03/08/2005 15:39              0.0         0.0       -----       -
----  
  42  03/08/2005 15:40              0.0         0.0       -----       -
----  
  43  03/08/2005 15:41              0.0         0.0       -----       -
----  
  44  03/08/2005 15:42              0.0         0.0       -----       -
----  
  45  03/08/2005 15:43              0.0         0.0       -----       -
----  
  46  03/08/2005 15:44              0.0         0.0       -----       -
----  
  47  03/08/2005 15:45              0.2         0.0       -----       -
----  
 
 
 182
3. Data Exported to MS Excel?: 
 
 
Instrument: QRAE+ (PGM2000)                   Serial Number: 408301 
User ID: 00000001      Site ID: 00000001  
Data Points: 47        Data Type: Avg         Sample Period: 60 sec 
Last Calibration Time: 10/25/2004 11:14  
=======================================================
================================================= 
Gas Type:    CO(ppm)  
H2S(ppm) 
High Alarm Levels: 1500 250 
Low Alarm Levels: 1435 200 
=======================================================
================================================= 
Line# Date  Time   CO(ppm) Alarm  
H2S(ppm)
Alarm 
=======================================================
================================================= 
1 3/8/2005 14:59 38.9 0  
2 3/8/2005 15:00 2.2 0  
3 3/8/2005 15:01 0.6 0  
4 3/8/2005 15:02 0.3 0  
5 3/8/2005 15:03 0.2 0  
6 3/8/2005 15:04 0.1 0  
7 3/8/2005 15:05 0.1 0  
8 3/8/2005 15:06 0 0  
9 3/8/2005 15:07 0 0  
10 3/8/2005 15:08 0 0  
11 3/8/2005 15:09 0 0  
12 3/8/2005 15:10 0 0  
13 3/8/2005 15:11 0 0  
14 3/8/2005 15:12 0 0  
15 3/8/2005 15:13 0 0  
16 3/8/2005 15:14 0 0  
17 3/8/2005 15:15 0 0  
18 3/8/2005 15:16 0 0  
19 3/8/2005 15:17 0 0  
20 3/8/2005 15:18 0 0  
21 3/8/2005 15:19 0 0  
22 3/8/2005 15:20 0 0  
23 3/8/2005 15:21 0 0  
24 3/8/2005 15:22 0 0  
25 3/8/2005 15:23 0 0  
26 3/8/2005 15:24 0 0  
27 3/8/2005 15:25 0 0  
28 3/8/2005 15:26 0 0  
29 3/8/2005 15:27 0 0  
30 3/8/2005 15:28 0 0  
31 3/8/2005 15:29 0 0  
32 3/8/2005 15:30 0 0  
 183
33 3/8/2005 15:31 0 0  
34 3/8/2005 15:32 0 0  
35 3/8/2005 15:33 0 0  
36 3/8/2005 15:34 0 0  
37 3/8/2005 15:35 0 0  
38 3/8/2005 15:36 0 0  
39 3/8/2005 15:37 0 0  
40 3/8/2005 15:38 0 0  
41 3/8/2005 15:39 0 0  
42 3/8/2005 15:40 0 0  
43 3/8/2005 15:41 0 0  
44 3/8/2005 15:42 0 0  
45 3/8/2005 15:43 0 0  
46 3/8/2005 15:44 0 0  
47 3/8/2005 15:45 0.2 0  
 
 
 184
Appendix B 
Results of Tests Performed according to Various Proposed Standards 
Catalyst testing for CBRN General and Specific Category: 
Following are the different test condition for CBRN general and specific category. 
? Inlet CO Concentration:  3600 ppm (General), 6000 ppm (Specific) 
? Outlet CO Concentration: ? 500 ppm (time weighted average    
   over 5 minutes, c*t = 2013 ppm.min) 
? Relative Humidity:   89 ? 95% 
? Temperature:   25 ? 2.5 
0
C & 0 ? 2.5 
0
C  
? Inlet Flow Rate:  64 ? 10 LPM 
? Time:    15, 30, 45 and/or 60 minutes 
? Pressure Drop:   ? 70 mm of H
2
O (Entire canister) 
Service Life Testing 
? 100 ? 10 LPM inlet flow rate , 5 minutes minimum lifetime at 25 ? 2.5 
0
C (Other 
conditions same as above) 
Inspired Air Temperature Test: 
? Inlet CO Conc. = 1200 ppm 
? Flow Rate = 40 LPM 
? Outlet Conc.  < 10 ppm 
? Temperature Measured at face-piece < 46
0
C (Dry Bulb) 
 
 185 
0
50
100
150
200
250
300
350
400
450
500
550
600
0 1020304050607
Time (Min)
O
u
tl
e
t
 C
O
 
C
o
n
c
. (
p
p
m
0
)
 Face Velocity = 21.6 cm/sec
 Face Velocity = 12.5 cm/sec
 
Figure A3.1: Catalyst testing for CBRN general category  
 
Test Conditions: 
Inlet CO Concentration= 3600 ppm 
Bed Depth=   4 mm 
Relative humidity=  90% 
Temperature=   22
0
C
 186 
0
50
100
150
200
250
300
350
400
450
500
550
600
0 2040608010120
Time (Min)
O
u
tl
e
t
 C
O
 C
o
n
c
. 
(p
p
m
)
 
Figure A3.2: Catalyst testing for CBRN general category at 0
0
C 
 
Test Conditions: 
Inlet CO Concentration= 3600 ppm 
Bed Depth=   6 mm 
Relative humidity=  90% 
Temperature=   0
0
C 
Face velocity=   12.5 cm/sec
 187 
CBRN Specific Category: 
0
100
200
300
400
500
600
0 10203040506070
Time (Min)
Ou
tl
e
t
 C
O
 C
o
nc. (
p
p
m
)
4 mm
2 mm
 
Figure A3.3: Catalyst testing for CBRN specific category at 22
0
C 
 
Test Conditions: 
Inlet CO Concentration= 6000 ppm 
Relative humidity=  90% 
Temperature=   22
0
C 
Face Velocity=  12.5 cm/sec
 188 
0
50
100
150
200
250
300
350
400
450
500
550
600
2040608
Time (Min)
O
u
t
l
et
 C
O
 C
onc
.
 (
ppm
0
)
 
Figure A3.4: CBRN Specific Category at 0
0
C 
 
Test Conditions: 
Inlet CO Concentration= 3600 ppm 
Bed Depth=   6 mm 
Relative humidity=  90% 
Temperature=   0
0
C 
Face velocity=   12.5 cm/sec
 189 
Inspired Air Temperature Test: 
0
10
20
30
40
50
60
70
80
90
100
0 10203040506070
Time (Min)
O
u
tl
e
t
 C
O
 C
o
n
c
. (p
p
m
)
2 mm
4 mm
 
Figure A3.5: CBRN general and specific inspired air temperature test 
 
Test Conditions: 
Inlet CO Concentration= 1200 ppm 
Relative humidity=  90% 
Temperature=   22
0
C 
Face velocity=   7.8 cm/sec
 190 
ANSI 110-2003 # 6 and #7 tests: 
? Inlet CO Concentration:  3000 ? 90 ppm (#6), 5000 ? 150 ppm (#7) 
? Outlet CO Concentration ?200 ppm  
? Relative Humidity:   87 ? 3% 
? Temperature:   27 ? 2 0C (#6 & #7), 0 ? 2 0C (#7)  
? Inlet Flow Rate:  100 ? 0.5 LPM 
? Time:    15 minutes 
0
50
100
150
200
250
300
350
400
2040608
Time (Min)
O
u
tl
e
t
 C
O
 C
o
n
c
.
 (p
p
m
0
)
 
Figure A3.6: catalyst testing for ANSI #6  
 191 
 
Test Conditions: 
Inlet CO Concentration= 3000 ppm 
Bed depth=   4 mm 
Relative humidity=  90% 
Temperature=   22
0
C 
Face velocity=   19.5 cm/sec 
 
0
50
100
150
200
250
300
350
400
0 10203040506070
Time (Min)
O
u
t
l
et
 C
O
 C
o
nc
.
 (
p
pm
)
 
 192 
Figure A3.7: Test for ANSI #7  
 
Test Conditions: 
Inlet CO Concentration= 5150 ppm 
Bed depth=   6 mm 
Relative humidity=  90% 
Temperature=   22
0
C 
Face velocity=   19.5 cm/sec 
0
50
100
150
200
250
300
350
400
450
500
0 10203040506070
Time (Min)
O
u
t
l
et
 C
O
 
C
o
nc
.
 (
p
pm
)
6 mm
8 mm
 
 193 
Figure A3.8: Test for ANSI #7 at 0
0
C 
 194 
 
Test Conditions: 
Inlet CO Concentration= 3600 ppm 
Relative humidity=  90% 
Temperature=   0
0
C 
Face velocity=   19.5 cm/sec 
 195 
Experimental Results with Heat Capacity added upstream of the Bed: 
Some key tests were repeated with 2 cm bed of carbon 12X30 particles upstream of the 
microfibrous entrapped CO oxidation catalyst. 
0
50
100
150
200
250
300
350
400
450
500
550
600
0 20 40 60 80 100 120 140
Time (Min)
O
u
t
l
et
 
C
O
 C
onc.
 (
p
pm
)
 
Figure A3.9: CBRN general category at 0
0
C 
Test Conditions: 
Inlet CO Concentration= 3600 ppm 
Bed depth=   4 mm 
Relative humidity=  90% 
 196 
Temperature=   0
0
C 
Face velocity=   12.5 cm/sec 
0
50
100
150
200
250
300
350
400
450
500
550
600
0 1020304050607
Time (Min)
O
u
t
l
et
 
C
O
 C
o
nc
.
 (
p
pm
0
)
 
Figure A3.10: CBRN specific category  
Test Conditions: 
Inlet CO Concentration= 6000 ppm 
Bed depth=   6 mm 
Relative humidity=  90% 
Temperature=   0
0
C 
 197 
Face velocity=   21.5 cm/sec 
 
0
50
100
150
200
250
300
350
400
450
500
550
600
204060801
Time (Min)
O
u
tl
e
t
 C
O
 C
o
n
c
. (p
p
m
0
)
 
Figure A3.11: CBRN General Category  
 
Test Conditions: 
Inlet CO Concentration= 3600 ppm 
Bed depth=   4 mm 
Relative humidity=  90% 
 198 
Temperature=   22
0
C 
Face velocity=   12.5 cm/sec 
 199 
0
10
20
30
40
50
60
70
80
90
100
0 10203040506070
Time (Min)
O
u
tle
t
 C
O
 C
o
nc
. (
p
pm
)
 
Figure A3.12: Inspired air temperature test with packed bed of sorbents 
 
Test Conditions: 
Inlet CO Concentration= 1200 ppm 
Bed depth=   4 mm 
Relative humidity=  90% 
Temperature=   22
0
C 
Face velocity=   7.8cm/sec 
 200 
Appendix C 
Adiabatic Flame Temperature Calculation 
Definition: 
When an exothermic reaction is carried out in adiabatic mode, all the heat generated in 
the reaction goes to raise the temperature inside the reactor. This temperature is referred 
to as, adiabatic flame temperature. 
Adiabatic flame temperature of a reaction can be evaluated by solving following 
equation: 
() ( )
eed
f
in
iiRfad
out
ii
THnHnTHn
??
+??=  ????... (0) 
Reaction: 
CO + 0.5O
2
 ? CO
2 
282?=?
R
H  kJ/mol ??????????..??. (1) 
Sample Calculation: 
Inlet CO Concentration = 3600 ppm 
Basis: 
Inlet CO Conc =  1 mole 
Inlet O
2
 Conc =  19 moles 
Inlet N
2
 Conc =  258 moles 
Tref =    298 K (same as feed temperature) 
Heat in: 
( )
?
?=?
refinpin
TTmCH  ??????????.. (2) 
Heat Out: 
 201
( )
?
?=?
refadpout
TTmCH  ??????????. (3) 
Equations (1), (2) and (3) when substituted in equation (0), can be solved for Tad, 
adiabatic flame temperature.  
Heat capacities for various components of the reaction can be found in Perry?s 
Handbook. 
C
pCO2 
= 0.03611 + 4.233*10
-5
*T
ad 
C
pO2 
= 0.02910 + 1.158*10
-5
*T
ad
C
pN2 
= 0.02900 + 0.2199*10
-5
*T
ad
Substituting these expressions in equations (2) and (3) and simplifying yields: 
T
ad
 = 332 K 
 
 202
Appendix D 
Preliminary Results from SEM/EDS 
 
This section gives the Scanning Electron Microscope (SEM) and SEM/ Energy 
Dispersive Spectrometer (EDS) information of the microfiber composite catalyst. Figures  
3.21 (a & b) and 3.22 (a & b) show the SEM images of the microfiber composite catalyst 
perform i.e. silica support material entrapped into the Microfibrous mesh. Figures 3.21 a 
& b are the SEM images of the perform after Wet lay and before sintering. Figures 3.22 a 
& b are the SEM images of the perform after sintering. 
As shown in the figure 3.21 b, the silica particles are properly entrapped into the 
mesh of cellulose and nickel fibers. Figure 3.22 b, shows that the cellulose after pre-
oxidation and sintering is removed from the mesh and only nickel fibers are left. 
 203
 
Figure 3.21 a: SEM image of microfiber entrapped Silica particles at ma
of 37 (before sintering). 
 
4 ?m
Fiber 
 204
gnification level 
8 ?m Ni 
Fiber 
Cellulose 
Fiber 
Silica 
Particle 
 Ni 
Figure 3.21 b: SEM image of microfiber entrapped Silica particles at magnification level 
of 200 (before sintering). 
 
Figure 3.22 a: SEM image of microfiber entrapped Silica particles at magnification level 
of 37 (After sintering). 
 205
 
Silica 
Particle 
8 ?m Ni 
Fiber 
4 ?m Ni 
Fiber 
Figure 3.22 b: SEM image of microfiber entrapped Silica particles at magnification level 
of 200 (after sintering). 
 206
SEM/EDS of the catalyst for quantification: 
Figure 3.23 shows the EDS spectrum of Pt/Mn/SiO2 catalyst. 
 
 
Figure 3.23: EDS spectrum of Pt/Mn/SiO
2
 catalyst  
As seen in figure, there is one peak corresponding to each element present in the 
catalyst. Based on the spectrum table 3.7 gives the quantification of various elements 
present in the catalyst. 
 207
 
Table 3.7: Quantification of Pt/Mn/SiO2 catalyst based on EDS spectrum: 
Sr. 
No. 
Element Wt % Atomic % 
1 Si 34.45 24.73 
2 O 58.73 74.02 
3 Mn 2.07 0.76 
4 Pt 4.74 0.49 
 
The weight % of platinum shown by EDS is in good agreement with the 
calculated weight (5.1%). The atomic ratio of Mn:Si  (0.03) is also in good agreement 
with the calculated atomic ratio (0.025). 
 
Table 5-1. Quantification of Pt-Co/Al
2
O
3
 catalyst based on the EDS spectrum. 
Sr. No. Element Wt % Atomic % 
1 Al 41.87 31.01 
2 O 51.05 67.53 
3 Co 3.02 1.04
4 Pt 4.06 0.42 
 
 208
The weight % of Pt obtained by EDS is in good agreement with the calculated 
weight (4.7wt%) during the incipient-wetness impregnation process. The atomic ratio of 
Co:Al (0.034:1) is also in good agreement with the calculated atomic ratio (0.04:1). 
 
Figure 3.24: EDS spectrum of Pt/Co/Al
2
O
3
 catalyst  
 
 209