Identification of the Active Sites in the Dehydrogenation of Methanol on Pt/Al<sub>2</sub>O<sub>3</sub> Catalysts
Tianjun Xie, Bryan J. Hare, Paul J. Meza-Morales, Carsten Sievers, Rachel B. Getman
Abstract
Conversion of oxygenates derived from biomass is a promising strategy for the production of fuels and chemicals. The needed H2 can be supplied simultaneously (and sustainably) via aqueous phase reforming (APR; CnH2nOn + nH2O → nCO2 + 2nH2). APR is typically carried out over supported metal catalysts under liquid water. Dehydrogenation is the first constituent reaction in APR and involves both C–H and O–H bond cleavages; however, details about the mechanism and natures of the active sites remain unknown. Herein, such details are provided for methanol dehydrogenation over a supported Pt/Al2O3 catalyst. Using density functional theory calculations, we find that methanol dehydrogenation occurs on the Pt terraces and at the Pt/Al2O3 interfaces but follows different paths: on interfacial sites, O–H cleavage occurs first and dehydrogenation follows a methoxy route, whereas on terrace sites, C–H cleavage occurs first and dehydrogenation follows a hydroxymethyl route.