Adsorption of Hydrogen and Methane Mixtures on Carbon Cylindrical Cavities

Abstract

The purpose of this work is to provide some insights into the adsorption of hydrogen and methane mixtures on carbon cavities with cylindrical geometry. Hydrogen and methane mixture adsorption has been simulated in pore sizes ranging from micropores to mesopores at room temperature. The grand canonical Monte Carlo method provided the amount adsorbed as a function of pressure and bulk composition. In addition, the microscopic characteristics of the adsorbed phase have been accomplished by calculating density profiles and adsorption energy distribution functions. The results show that the first methane and hydrogen adsorbed layers are co-incident, and there is a second hydrogen layer that is not present in the pure compound adsorption. In addition, the adsorption energy stages for hydrogen in the mixture are more favorable than those for pure hydrogen, revealing that the presence of methane molecules favors energetic hydrogen stabilization (for micropores, hydrogen adsorption energy changes are observed from 6.3 to 75%, depending on the operational conditions). These results can shed light on the knowledge of the underlying adsorption behavior of these mixtures, which are of interest in hydrogen storage and purification by adsorption, and therefore of potential applications in hydrogen technology (clean hydrogen production, fuel cells, etc.).