Carbon materials porosity analysis using DFT models for potential application in the recovery of methane from its low-concentration mixtures

• Methane recovery from gas mixtures containing low-concentration of methane. • PSD textural characteristics using the 2D-NLDFT and QSDFT/NLDFT models. • DFT-based prediction of CH 4 adsorption isotherms at ambient temperature. • Relationship between the textural properties of carbons and their CH 4 capacity. • Selection of the adsorbent material for adsorption-based processes. One of the key factors in the adsorption-based processes such as Pressure Swing Adsorption is the proper selection of the adsorbent material. The primary motivation of this work is the thorough analysis of the porous structure of selected carbon materials for this process. Considering that the pore size distribution (PSD) determines the specific part of the adsorbent structure that is accessible to probe molecules of N 2 and CO 2 used for the analysis, we discuss the optimal pore size for the adsorption of CH 4 at 293 K having molecular diameter is larger than N 2 and CO 2 . To perform a detailed textural characterization of our carbon samples using the N 2 and CO 2 adsorption isotherms, we apply the 2D-NLDFT and QSDFT/NLDFT models available in the SAIEUS and ASiQwin software packages, respectively. To discuss the relationship between the PSD and the CH 4 adsorption of our samples, we chose to use PSDs derived by the dual gas N 2 & CO 2 analysis method (SAIEUS software). We show that it is possible to estimate the experimental CH 4 adsorption isotherms at 293 K based on the porous texture characteristics derived from N 2 at 77 K and CO 2 at 273 K and the application of appropriate 2D-NLDFT models. Furthermore, we demonstrate that the described carbon PSD characterization and the following prediction methods constitute valuable links between the textural properties and CH 4 adsorption isotherms of the carbon materials. We believe that the results of this work will be a practical guide for future research on the selection of adsorbents for the separation of mixtures containing low concentrations of methane.