Simulation Study of Mass Transfer Characteristics of CH4/CO2 Separation in Multiple Types of Covalent Organic Framework Membrane Materials

Covalent organic framework (COF) membrane materials arebeing increasinglyutilized in gas separation processes due to their low-carbon, clean,and efficient properties. These materials are expected to have large-scaleindustrial applications in natural gas clean-up and separation processes.The separation effects of COFs materials vary for the CO2 membrane separation process, which has a significant impact on gasrecovery. This paper aims to compare the mass transfer patterns ofdifferent COFs to separate CO2 and to expose the mechanismof separation. Employing a combination of Monte Carlo (GCMC) and moleculardynamics (MD) methods, this paper analyzes the mass transfer behaviorsof CO2 separation from CH4/CO2. Thestudy also examines the thermodynamic parameters, such as separationtemperature, separation pressure, and gas components, to reveal theproperties of CO2 separation from different COFs and thetransport rules of gas molecules at the microscopic level. The findingssuggest that pore size, CO2 concentration, and lower temperatureenvironment contribute to the ability of CO2 adsorption.Additionally, COFs with oxygen-containing groups (NUS-2, COF-5, etc.)have better diffusion separation ability, and the AA stacking formsshould be maintained during the process of completing the diffusionseparation CO2. This paper could provide the essentialbasis for the design and adjustment of the structure of COFs and theenhancement of the gas membrane separation technology.