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Ab initio study of the adsorption of acetone and keto-enol equilibrium on the MgO(100) surface

1998; Elsevier BV; Volume: 397; Issue: 1-3 Linguagem: Inglês

10.1016/s0039-6028(97)00643-2

1879-2758

Jaime Oviedo, Javier Fdez. Sanz,

Mesoporous Materials and Catalysis

Abstract An ab-initio quantum mechanical study of the adsorption of acetone and 2-propenol on a clean MgO(100) surface is reported. Ab-initio Hartree-Fock calculations have been carried out using an embedded-cluster approach in which the environment is described by total ion potentials and point charges. Optimized geometries for both acetone and 2-propenol adsorbed on the surface have been obtained using two basis sets and several model clusters. The adsorbate-surface interaction is found to be weak and electrostatic in nature, although there is a relative stabilization of the enol tautomer. The effect of the surface on the keto-enol equilibrium is analyzed and explained on the basis of this differential adsorption. Surface reconstruction induced by the adsorbate is also considered. While the surface relaxation effects are found to be negligible for acetone, they appear to be larger for 2-propenol, and allowing the surface to relax changes the qualitative description of the enolization process since in this case an enolate species is found to be adsorbed on the surface.