Tests of Pore-Size Distributions Deduced from Inversion of Simulated and Real Adsorption Data

An adsorption isotherm provides indirect information about the geometry of the host material and its interaction with the adsorbed fluid. This paper presents a critical study of the inversion of experimental data to elucidate desired information about this geometry. Using Ar and H-2 as representative classical and quantum fluids and a carbon slit-pore geometry, we compare the accuracy of isotherms derived from non-local density functional theory with isotherms from grand canonical Monte Carlo simulations, using a quantum-corrected potential for H-2. We determine the pore size distributions (PSDs) for a series of model and experimental materials by inverting the adsorption integral equation, with the goal of probing the ability of the inversion procedure to reproduce faithfully the input pore size distribution and ascertain the reality of anomalous gaps often deduced in the literature. Drawing from the GCMC simulations, we then explore the concept of effective porous materials, or 'iso-PSDs', which have similar adsorption isotherms, despite very different pore size distributions.