Gözenekli koordinasyon ağlarında gaz adsorpsiyon ve difüzyon: Bir hesaplamalı çalışma

Adsorbents and membranes play a significant role in energy efficient gas separations. Higher energy costs in recent decades have made the adsorption- and membrane-based gas separation processes even more economically competitive with traditional separation methods. Adsorbents having high selectivity and working capacity are needed for effective adsorption-based separation processes. Similarly, membranes exhibiting high selectivity and high gas permeability are required to lower the cost of large scale membrane-based gas separation processes. Developing ideal adsorbents and membranes having desired properties has been the main focus of adsorption and membrane research in the world for a very long time. Porous coordination networks (PCNs) are a new class of crystalline nanoporous materials constructed from metal organic complexes and organic linkers to create highly porous structures with permanent porosity. Their properties, such as tunable pore sizes, large surface areas, high porosities, good chemical and mechanical stabilities, make them attractive in a large variety of applications such as gas storage, catalysis, and gas separation. During synthesis, different combinations of metal ions and organic linkers lead to a large variety of PCN materials. Although a large number of PCNs has been synthesized to date, the potential performance of PCNs for adsorption-based and/or membrane-based gas separation applications is not studied in detailed. There is currently no study in the literature that examines the membrane-based gas separation properties of PCNs which requires information on gas transport properties in PCNs' pores. In this thesis, atomic simulations are performed to investigate adsorption-based, diffusion-based and membrane-based separation performances of various PCN materials for industrially important gas separations including CH4/H2, CO2/CH4, CO2/H2, CO2/N2 and O2/N2 mixtures. To evaluate the adsorption-based and membrane-based separation performances of PCNs, important parameters such as adsorption selectivity, working capacity, regenerability, sorbent selection parameter, diffusion selectivity, permeation selectivity and gas permeability are computed. PCNs' separation performance is compared with other nanoporous materials to assess the potential of PCNs as adsorbents and membranes. The effect of charge assignment method on the calculation of separation properties is also studied. Simple models to predict adsorption, diffusion and permeation selectivities are developed. Additionally, PCN-filled mixed matrix membranes are investigated performing molecular simulations for separating O2 from N2. To conclude, adsorption-based and membrane-based separation performances of PCNs using atomic simulations are examined for the first time in the literature. Results suggest that PCNs offer considerably high potential to be used as adsorbents and membranes for gas separation applications. This study provides simple models to predict adsorption, diffusion and permeation selectivities of PCNs that will be highly useful for quick screening of PCNs for gas separation applications to identify the promising materials. Time, resources and efforts can be then directed to more detailed examination of these promising materials using experimental manners.