Comparing homogeneous and heterogeneous acid catalysts by a density-functional based sensitivity analysis of their interaction with carbenium ions

Abstract

An attempt has been made to develop a quantitative comparison of the properties of homogeneous and heterogeneous catalyst systems. The bond formation, and its projected covalent character, of a carbenium ion with the surface of zeolites and with water molecules in solution served as a basis to collect quantitative data. These data are the global electronegativity and hardness and the local softness (reactivity parameter of atoms-in-molecules) as these can be calculated for solids and molecules in the EEM formalism. A consistent model could be developed for a quantitative and qualitative comparison. It shows that generally, hydrated carbenium ions remain more ionic than those interacting with the surface of silicates or zeolites.