Adsorption properties of the tetragonal P4/nmm WO3 (100) surface toward molecules involved in the hydration of ethylene

Abstract Industrial demand for ethanol has stimulated research on improved catalysts for ethylene hydration. WO 3 and other tungsten-based catalysts have been used in direct hydration of ethylene to ethanol, showing high conversion rate and selectivity toward this reaction. By using first-principles calculations based on spin polarized density functional theory, including also dispersion forces, this paper presents the adsorption properties of molecules involved in the ethylene hydration on the tetragonal P 4/ nmm WO 3 (100) surface. The inclusion of dispersion forces, improved our lattice parameters prediction with respect to previous theoretical studies. For the WO 3 tetragonal crystal, the (100) surface contains five chemically distinct atoms: a five-fold coordinate W 5 c , three different types of two-fold binding oxygen O 2 c , and a single-coordinated oxygen O 1 c . The energetically favored adsorption sites of water, ethylene, and ethanol (including also hydrogen) are determined here for the first time on this surface. The surface presents high reactivity towards water and ethylene, the single-fold coordinated oxygens stabilize the adsorbed molecules and after adsorption the tungsten atoms take a W 6 c role. The obtained configurations of the reactants suggest a Rideal–Eley mechanism of ethylene over adsorbed water. These results reveal the interactions between the selected tetragonal WO 3 surface and the molecules involved in the hydration of ethylene, which ultimately determine the reaction mechanism for ethanol production.