Preparation of Carbon Molecular Sieves Used for CH4/N2 Separation

In this study, carbon molecular sieves (CMS) were prepared by chemical vapor deposition method using benzene as depositing agent based on activated carbon. The influences of deposition temperature, time, and flow rate of benzene on adsorption capacity and separation coefficient were investigated. The results show that the CH4 equilibrium adsorption capacity and CH4/N2 separation coefficient of CMS-G, which is prepared at the deposition temperature of 1023 K, time of 60 min, and flow rate of 4 mL·min–1, are at a maximum value (parametric investigation of this study is based on the parameter ranges in the text). The deposition temperatures had an obvious effect on the textural modification of CMS. CMS-G was characterized by mercury intrusion, CO2 permeation, analysis of kinetics, and pressure swing adsorption (PSA). Both kinetic and PSA results demonstrate a good CH4/N2 separation performance for the CMS-G. A very high kinetic selectivity was observed, which reached 35.26. An enrichment of 30.20% for methane in pressure swing adsorption experiment was also observed. The data demonstrate that CMS-G is a good adsorbent suitable for separating CH4 from methane and nitrogen gas mixture.