Strong metal-support interaction boosting the catalytic activity of Au/TiO2 in chemoselective hydrogenation

Abstract

Gold catalysts have been reported as highly effective catalysts in various oxidation reactions. However, for chemoselective hydrogenation reactions, gold-based catalysts normally show much lower catalytic activity than platinum group metals, even though their selectivities are excellent. Here, we report that the chemoselective hydrogenation activity of 3-nitrostyrene to 3-vinylaniline over Au/TiO2 can be enhanced up to 3.3 times through the hydrogen reduction strategy. It is revealed that strong metal-support interaction, between gold nanoparticles (NPs) and TiO2 support, is introduced through hydrogen reduction, resulting in partial dispersion of reduced TiOx on the Au surface. The partially covered Au not only increases the perimeter of the interface between the gold NPs and the support, but also benefits H2 activation. Reaction kinetic analysis and H2-D2 exchange reaction show that H2 activation is the critical step in the hydrogenation of 3-nitrostyrene to 3-vinylaniline. Density functional theory calculations verify that hydrogen dissociation and hydrogen transfer are favored at the interface of gold NPs and TiO2 over the hydrogen-reduced Au/TiO2. This study provides insights for fabricating highly active gold-based catalysts for chemoselective hydrogenation reactions.