Search

A combined experimental and molecular simulation study of the coadsorption of CO2 and CH4 in porous carbons is reported. We address the effect of surface chemistry by considering a numerical model of disordered porous carbons which has been modified to include heterochemistry (with a chemical composition consistent with that of the experimental sample). We discuss how realistic the numerical sample is by comparing its pore size distribution (PSD), specific surface area, porous volume, and porosity with those for the experimental sample. We also discuss the different criteria used to estimate the latter properties from a geometrical analysis. We demonstrate the ability of the MP method to estimate PSD of porous carbons from nitrogen adsorption isotherms. Both the experimental and simulated coadsorption isotherms resemble those obtained for pure gases (type I in the IUPAC classification). On the other hand, only the porous carbon including the heterogroups allows simulating quantitatively the selectivity of the experimental adsorbent for different carbon dioxide/methane mixtures. This result shows that taking into account the heterochemistry present in porous carbons is crucial to represent correctly adsorption selectivities in such hydrophobic samples. We also show that the adsorbed solution theory describes quantitatively the simulated and experimental coadsorption isotherms without any parameter adjustment.

Nitrogen adsorption at 77 K on metal–organic framework (MOF) is investigated by means of molecular simulations. We consider both regular Cu–BTC crystal and a MOF-based hierarchical porous solid consisting of a mesopore carved out of a Cu–BTC crystal. The t-plot method is applied to these solids by using a non-porous Cu–BTC surface as the reference sample. The values of the mesoporous and external surface areas are determined from the t-plot, and the validity of the method for this type of hierarchical solid is discussed., Institut Carnot (Chimie, Environnement et De´veloppement Durable)