Molecular simulation on separation of CO2/CH4 gas mixture with carbon membrane

A simulation study was conducted in separation of CO2/CH4 gas mixture using Materials Studio and Lammps softwares, respectively. Zigzag-type pore model was developed to describe the pore structure and verified by CO2 adsorption isotherm experimentally determined with home-manufactured carbon membranes. Adsorption and diffusion behaviors of pure gas and gas mixture within the pores of carbon membrane were investigated under different conditions in an effort to explore the separation mechanism. Overall separation coefficient of CO2/CH4 adsorption and diffusion was examined in the present study. Results showed that appropriately low temperature and small pore size were beneficial to achieve separation of CO2/CH4 gas mixture. As the temperature and the pore size were decreased, the separation coefficient increased. The overall separation coefficient of gas mixture was 20.1 at 298 K of the operating temperature and 0.670 nm of the pore size of membrane, which was consistent with the experimental value. This fundamental research would provide a basis for optimizing the preparation of carbon membranes and for studying the separation mechanism of CO2/CH4 gas