This Is AuburnElectronic Theses and Dissertations

Hydrotreatment of Biomass and Waste Derived Hydrothermal and Pyrolysis Liquid Intermediates for the Production of Fuels and Lubricants




Roy, Poulami

Type of Degree

PhD Dissertation


Biosystems Engineering

Restriction Status


Restriction Type


Date Available



Extensive use of crude oil resources in producing fuel, energy, and chemicals to sustain the growing world population has led to the depletion of natural resources and the release of greenhouse gas emissions leading to global warming and climate change. There is an indispensable need to maintain the development of lignocellulosic biomass and waste resources for biofuel and bioproduct conversion, as this could be the answer to energy security and the use of various domestic natural resources. The objectives of this dissertation were based on the perceived need to develop biofuels and high value bioproducts such as biolubricants from waste precursors and biomass produced from hydrothermal liquefaction (HTL) and pyrolysis after hydrotreatment over different heterogeneous catalyst supports. First, hydrotreatment of non-edible vegetable oil (Brassica Carinata) was carried out over biochar-supported catalysts. These catalysts were developed from nickel (Ni) - and cobalt (Co)- nitrates and hydroxide salts. Nitrate-based (from water-soluble salts) and hydroxide-based (from water-insoluble salts) catalysts of Ni and Co were prepared via wetness impregnation and aqueous dispersion methods, respectively. The synchroton method showed nitrate-sourced metals were primarily dispersed in the pores, while the hydroxide-sourced metals were distributed mainly on the catalyst surface. The C=C saturation and cracking of triglycerides, decarboxylation, and hydrogenation of aromatic structures appeared to be dominant on the hydroxides of transition metals, taking place on the catalyst surface. However, methanation and dehydrogenation (thus aromatization) seemed to be a pore phenomenon, catalyzed more than nitrate-based catalysts. A reaction network was proposed based on chemical analysis of upgraded carinata oil and erucic acid model compound. Catalytic cracking followed by hydrotreatment performed better in fuel properties than other approaches in this study. Since biochar-supported Co and Ni catalysts successfully hydrotreated carinata oil to produce biofuel, especially Co-produced better results than Ni. This further motivated us to utilize the same biochar support in the present study and introduce a bimetallic (cobalt and molybdenum) component instead of a monometallic (cobalt) component on the support and hydrotreat a mixture of oils (HTL algae and carinata) instead of only carinata. Therefore, in the present study, sulfided and unsulfided bimetallic (CoMo) catalysts on two supports (Douglas fir biochar support (DF) and alumina support (Al)) were used for hydrotreating a blend of HTL algae biocrude and carinata oil. Four types of catalysts were used: 1) alumina-supported CoMo (denoted as CoMo/Al, 2) sulfided alumina-supported CoMo (denoted as S-CoMo/A, 3) Douglas fir biochar (DF)-supported CoMo (denoted as CoMo/DF), and 4) sulfided DF-supported CoMo (denoted S-CoMo/DF). The main objective of this study was to understand the synergistic effect of the blending and the order of reactivity for different supports in terms of hydrodeoxygenation (HDO), hydrodenitrogenation (HDN), hydrodesulfurization (HDS) and hydrodemetallization (HDM). Results showed a synergistic effect when HTL algae biocrude and carinata oil blends are hydrotreated. The yield of the upgraded blend (UB) oils retrieved over the alumina catalyst was higher than the individual hydrotreated parent oils. For example, a 9% and 5% increase in yield was noted compared to the average of individual hydrotreated parent oils. The upgraded blends had higher heating value (syngas) was higher irrespective of the support type. The UB produced from sulfided CoMo/Al exhibited superior HDO activity primarily by decarbonylation. This was apparent in increased heating value, carbon addition, higher octane number, and lower total acid number than the oils obtained from the biochar-supported catalysts. Sulfided CoMo/DF catalyzed cracking reactions, which lowered the viscosity, followed by high HDN and HDS activity compared to the commercial catalyst. The two supports showed different sorption behaviors. Interestingly, CoMo/DF had an effective sorption mechanism that helped increase metal removal from the oil. Additionally, presulfiding and DF support exhibited positive results in less coke formation. In brief, biochar supports have higher acidic sites, inorganic mineral oxides, ion exchange capacity, high surface area, pore structure and connectivity. All of these make a substantial contribution to its unique catalytic behavior. This further motivated us to explore the alumina and DF biochar supports and carinata oil as one of the blending feedstocks for the hydrotreatment of more complex pyrolysis oil this time. Additionally, there needs to be more understanding of pyrolysis oil and vegetable oil/animal fat behavior when subjected to hydrodeoxygenation under different catalyst supports. Hence, this research aimed to assess the co-hydrotreatment of fast pyrolysis oil and carinata oil or poultry fat to identify synergistic effects, if any. Overall, the blended hydrotreated oil produced from biochar support showed a better positive synergistic effect in carbon and hydrogen addition, oxygen removal, HHV and viscosity. Biochar-supported catalysts demonstrated higher jet fuel fraction consisting mainly of paraffin and the lowest amount of light and heavy diesel. Oxygen was predominantly removed via dehydrogenation and methylation reactions, consuming more hydrogen. Alumina-supported catalysts removed oxygen predominantly via decarboxylation and decarbonylation reactions. A lower amount of coke formation was seen for biochar support. Large oxygen-containing functional groups, inorganic mineral oxides, high surface area, pore structure and acid sites make biochar-support catalysts better HDO catalysts compared to alumina-supported catalysts. On the other hand, blending the pyrolysis oil with poultry fat yielded better bio-oil quality over carinata oil due to the presence of C15 hydrocarbons. In summary, pyrolysis oil blended with poultry fat and hydrotreated using biochar support catalysts was more successful in HDO activity and improving overall bio-oil quality than alumina-supported catalyst and carinata oil. There is a need to support the biofuel sector by utilizing waste materials for its production and finding uses for co-products through an integrated approach. Due to bio-oils diverse composition, other applications of it are emerging, such as foams, resins and most importantly, biolubricants, a product with increasing global demand. Given the hydrocarbon chain number produced from the above objectives, these products can also be used as lubricants. This study produced four hydrocarbon biolubricants (HBL) via a hydrotreatment process. Two samples were produced using hydrothermal liquefaction (HTL) of algae (HAL) and sewage sludge (HSS), whereas the other two samples were from nonedible oil (carinata; HCA) and animal fat (poultry fat; HPF) and were evaluated for their tribological properties and compared with mineral base oil (MBO). These potential biolubricants samples had viscosity indices (VI) ranging from 197 to 254, pour points (PP) from -10℃ to -20℃, and Noack volatilities between 16% to 23%. The coefficient of friction (COF) for HAL and HSS was lower than MBO, HPF, and HCA, but the wear was high. Large amounts of oxygenates and olefins imparted higher viscosity index and pour points to HPF. Even though both HSS and HAL demonstrated higher amounts of paraffin, they exhibited lower thermo-oxidative stability, poor pour point, and higher volatility than other samples. HPF had the lowest wear, highest viscosity index and pour point but higher COF. In contrast, volatility and COF were predominantly dependent on cyclic structures, unsaturation, and heteroatoms. The results indicated that the hydrotreated bio-oil produced from HTL biocrude and waste precursors could be considered eco-friendly hydrocarbon biolubricants blend stock.