Effect of framework distortion on xylene adsorption in AlPO4-11 predicted from Monte Carlo simulations

Abstract: In this short communication we present a study of xylene adsorption equilibria in distorted and non-distorted AlPO4-11 (AEL) materials using grand canonical Monte Carlo (GCMC) simulations. A previous energy minimization study showed that the AlPO4-11 crystal distorts upon xylene adsorption, but the effect of this distortion on the adsorption loadings was not known. In this work, we compare predictions from GCMC simulations in the distorted and non-distorted frameworks with experiments. The simulations show that the distorted structure adsorbs smaller amounts of xylenes than the non-distorted structure, and simulations in both structures predict ortho-selectivity, as seen in experiment. The lower adsorption capacity of the distorted structure can be related to changes in the adsorption sites. The results indicate that, besides pore blocking, structural deformations can be an important cause of lower adsorption capacity in molecular sieves. [Copyright &y& Elsevier]