Design of Copper-Based Adsorbents for Gas Separation and Purification: Exploring Novel Materials and Optimization Strategies

Abstract

This dissertation provides a comprehensive overview of the design, synthesis, and performance optimization of copper-based adsorbents for gas separation and purification. Adsorption, a cost-effective separation technique known for its high capacity and selectivity, has garnered significant attention in various gas separation applications. The dissertation is structured into four distinct chapters, each exploring different aspects of copper-based adsorbents and their effectiveness in capturing specific gases. In the first chapter, the current state of the field of adsorption is presented, along with identified research gaps. Emphasis is placed on the importance of investigating the adsorbent-adsorbate interaction to design new materials and explore their performance under realistic conditions. Various chemical modification methods for various supports, including activated carbon, zeolites, mesoporous silica, alumina, and metal-organic frameworks, are discussed. Specifically, the focus is on enhancing the adsorption capacity and selectivity for carbon monoxide (CO) as a representative system. The second chapter delves into the modification of copper surface to form CuCl as an active material for interaction with CO. The study examines the effect of solvent-regulated CuCl morphologies on CO adsorption capacity, selectivity, and kinetics. It is revealed that CuCl with triangular and granule morphologies show the highest adsorption capacity, while the cubic morphology provides the highest selectivity for CO adsorption. The significance of surface morphology and crystalline plane in achieving desired adsorption performance is emphasized. In the third chapter, a dual-active site adsorbent based on Cu(I) ions is synthesized through a two-step synthesis route. This chapter addresses the challenges associated with stability and selectivity of CuCl-modified copper and explores the aspect of surface energetic heterogeneity and the performance of the sample under realistic condition for CO separation from CO-CO2 mixture as a representative system for hydrogen purification. The study highlights the superior CO selectivity achieved by the dual-active site adsorbent, which makes it a promising candidate for CO separation for gas purification purposes. The stability of the adsorbent under atmospheric air and the impact of surface modifications on the adsorbent performance are thoroughly investigated. In the fourth chapter a facile synthesis method for zeolite@MOF composites at room temperature is presented. This chapter focuses on pre- and post-synthesis surface modification techniques and their influence on structural and chemical properties of the composites. The CO and CO2 adsorption performance of composite is evaluated, revealing the influence of copper salt choice, solvent selection, and modification of the zeolite and MOF components on adsorption capacity and selectivity. The role of surface chemistry in enhancing the interaction with CO is highlighted, and the overall performance of the designed composite is discussed. These studies showcase the advancements in design and performance of copper-based adsorbents for gas separation and purification. The investigations highlight the importance of designing novel materials, optimizing their structure and properties, and exploring various strategies to enhance adsorption performance and stability. The findings in this dissertation offers promising avenues for further development of efficient adsorbents for gas separation applications.