A theoretical study on the separation of CO2/CH4 through MFI zeolite

Abstract

The separation of carbon dioxide (CO2) and methane (CH4) is important in addressing global warming and energy shortages. Porous materials play a large role, of which MFI zeolite has received much attention. To better analyse mechanisms or guide experiments, the adsorption and diffusion properties of CO2 and CH4 in MFI zeolite have been studied by Monte Carlo and molecular dynamics simulations. Due to stronger interactions, the loading of pure CO2 is significantly higher than that of CH4. For mixtures (biogas or natural gas), CO2 dominates in competitive adsorption. Lower temperatures and higher pressures correspond to higher adsorption selectivity. In addition, the self-diffusion coefficients of guest molecules in MFI zeolite were also calculated. The diffusion performance of pure CH4 is superior to CO2 under the same conditions. And their self-diffusion coefficient increases with increasing temperature and decreasing load. For mixed components, CO2 greatly limits the diffusion of CH4.