Particle size and support effects in hydrogenation over supported gold catalysts

Abstract

Particle size and support effects were determined for the hydrogenation of nitrobenzene over gold supported on alumina and titania by kinetic experiments, TEM and in situ high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD XAS). Especially when supported on alumina, the catalytic activity correlated well with the fraction of particles smaller than 2 nm. These particles are able to split hydrogen on undercoordinated gold atoms, hence the strong particle size effect. In addition, on titania the increased length of the metal–support interface for smaller particles leads to enhanced activity because of the beneficial effect of the metal–support interface on the splitting of hydrogen. Reporting the average particle size is not always relevant in describing catalytic performance.