Influence of Confinement on Barriers for Alkoxide Formation in Acidic Zeolites

Abstract

The influence of the confinement imposed by eight different zeotypes on the formation of the alkoxides of 13 primary alcohols is studied using dispersion corrected density functional theory calculations with the PBE-D3 functional. Adsorption energies of the alcohols are computed along with barriers for formation of the alkoxides, which is the first step of the stepwise dehydration mechanism. We find that variations in the adsorption and transition state energies are largely governed by van der Waals interactions between substrates and the zeolite framework. Trends between different reactants, on the other hand, are largely due to the size of the molecules, which can be described quantitatively by the number of atoms constituting them. We find that the stabilization of adsorbates is largest for frameworks that are neither too small, leading to repulsive interaction, nor too spacious leading only to weak interaction.