(351k) Characterization ?-Alumina Porosity By Monte Carlo Slit-Pore Kernel

Despite its importance in the area of catalysis and adsorption, γ-alumina does not have a specific kernel for its characterization. We report adsorption isotherms of nitrogenat 77 K in γ-alumina calculated using Grand Canonical Monte Carlo method. Nitrogen molecules were represented by a single-site model and γ-alumina was modeled as a limited collection of individual slit-shaped pores. Validated forcefield parameters for alumina-nitrogen interaction were applied. Adsorption analysis of specific individual pores is also presented. Our collection was able to reproduce the experimental isotherm of a porous γ-alumina sample. When compared to models based on cylindric-shaped pores or on DFT calculations, our model performed better, especially at very low-pressure range (P/P₀ < 10^-2) where the adsorption in the micropores is more significant. We also found that the microporous volumes of γ-alumina were systematically underestimated by existing methods.