(347b) Modeling Cation Dependence of Gas Adsorption in Zeolites

Natural gas mixtures comprised of CH₄, N₂, CO₂, and hydrocarbons (among other components) are of great industrial interest, most notably for CH₄ which can be burned for fuel. It is, however, highly inefficient to burn the raw mixture, resulting in the need to separate CH₄ from the rest of the components. Gas separation is a field with many avenues that strive for affordable, efficient, and accessible separation of target gases. To this end, this study examines the adsorption of various gases in zeolites using Monte Carlo methods. Zeolites are cheap aluminosilicate materials with varying cation content that are capable of thermodynamic and kinetic separation of gases. The thermodynamic adsorption of CH₄, N₂, and CO₂ in CLI, RHO, and LTL-type zeolites with varied cation mixtures of Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ were calculated from 0.1-60 bar at 298.15 K using the Continuous Fractional Component Monte Carlo technique. Upon examination of adsorption in single cation and selected binary cation zeolite systems, a linear trend in adsorption was observed. Using a randomized mixture of cations, adsorption was both simulated and calculated with a linear model using the aforementioned adsorbates and zeolites, yielding a high level of agreement between the two methods. Future directions for this study include seeking experimental confirmation of this model and studying its application to kinetic properties, such as diffusion.