Analyzing adsorption characteristics of CO2, N2 and H2O in MCM-41 silica by molecular simulation

•The GCMC simulation of CO2, N2, and H2O adsorption in MCM-41 has been presented.•Pressure and temperature effects on the adsorption characteristics are discussed.•The results demonstrate three mechanisms of gas molecules adsorbed in MCM-41.•The applicability of adsorbing H2O by MCM-41 is presented. The adsorption characteristics of carbon dioxide, nitrogen and water molecules in MCM-41 mesoporous molecular sieve have been investigated by the molecular simulation. We evaluate the pressure–adsorption isotherms and adsorption density profiles under variant gas pressure, operating temperature and mesopore radius of MCM-41 by the grand canonical Monte Carlo simulation. According to the calculated adsorption energy distributions, the adsorption mechanisms of gas in MCM-41 are mainly divided into three types, namely “surface adsorption” on the pore wall, “multilayer adsorption” on the adsorbed gas molecules and “molecular self-aggregation” near the pore center. In addition, the adsorption characteristics of water molecules in MCM-41 are found to be quite different from those of carbon dioxide and nitrogen due to the hydrogen bonds effect. The results indicate that the MCM-41 is practicable in engineering application for the capture, storage, and re-use of water molecules, since it is temperature-sensitive and can achieve significant adsorption loadings within a small range of pressure values via the capillary condensation phenomena.