The Role of the Protons and the Electrostatic Potential in the Reactivity of the (110) Sulfated Zirconia Surface

Abstract

Several models for the adsorption of H2SO4 on (110)-ZrO2 surface were studied by total energy pseudopotential calculations, based on density functional theory. The analysis of the results focuses on the implications of the properties of the sulfated surface in its catalytic activity with hydrocarbons. The structural features of the models studied were in agreement with recently reported data on (101) and (001) faces of this material. The comparison of some properties of the sulfated surface with those of the hydroxylated one shows that one of the main features of sulfated zirconia (SZ) surface is its strong electrostatic potential around the sulfate group. This potential is intense enough to polarize hydrocarbons in the initial steps of their interaction with the surface. By combining this effect with the impact of proton detachment, a model for the interaction of SZ surface with hydrocarbons emerged. This model stresses the importance of adsorbed protons in the activity, and allows us to rationalize the dependence of the latter on the water content in the reaction environment.