Enhanced Selectivity for CO2 Adsorption on Mesoporous Silica with Alkali Metal Halide due to Electrostatic Field: A Molecular Simulation Approach

Abstract: Since adsorption performances are dominantly determined by adsorbate？adsorbent interactions, accurate theoretical prediction of the thermodynamic characteristics of gas adsorption is critical for designing new sorbent materials as well as understanding the adsorption mechanisms. Here, through our molecular modeling approach using newly-developed quantum-mechanics-based force field, it is demonstrated that the CO2 adsorption selectivity of SBA-15 can be enhanced by incorporating crystalline potassium chloride particles. It is noted that the induced intensive electrostatic fields around potassium chloride clusters create gas trapping sites with high selectivity for CO2 adsorption. The newly developed force field can provide a reliable theoretical tool in accurately evaluating the gas adsorption on given adsorbents, which can be utilized to identify good gas adsorbents.