Modeling Adsorption Properties on the Basis of Microscopic,Molecular, and Structural Descriptors for Nonpolar Adsorbents.

We propose a method for analyticallypredicting single-componentadsorption isotherms from molecular, microscopic and structural descriptorsof the adsorbate–adsorbent system and concepts of statisticalthermodynamics. Expressions for Henry’s constant and the heatof adsorption at zero coverage are derived. These functions dependon the pore size, pore shape, chemical composition, and density ofthe adsorbent material. They quantify the strength of the solid–fluidinteraction, which governs the low-pressure part of the adsorptionisotherm. For intermediate and high pressures, the fluid–fluidinteractions must also betaken into account. Both solid–fluid and fluid–fluidinteractions are combined within the framework of the Ruthven statisticalmodel (RSM). The RSM thus constructs theoretical adsorption isothermsthat are entirely based on microscopic molecular and structural descriptors.The theoretical results that we obtained are compared with experimentaldata for the adsorption of pure CO2and CH4onall-silica zeolites. The developed methodology allows for the estimationof the optimum properties of a nonpolar adsorbent for the adsorptionof CO2in cyclic adsorption processes. [ABSTRACT FROM AUTHOR]