Deposition of gold nanoparticles on ZnO and their catalytic activity for hydrogenation applications
Résumé
Gold nanoparticles have been deposited on zinc oxide by deposition–precipitation methods. The selection of the support characteristics is critical to control gold nanoparticle sizes and surface properties. Two ZnO supports have been studied, one is commercially obtained and the second is lab prepared by chemical vapor deposition resulting in tetrapod morphologies. In the latter two gold loadings were incorporated. These catalysts were mainly characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Also the three samples were tested for the selective hydrogenation of cinnamaldehyde. We have shown that the use of AuZnO as catalyst permits higher selectivity in desired products than that observed using alternative catalysts. The selectivity values which vary among 58% and 99% depending on the surface structure of the gold nanoparticles induce steric constraints between the phenyl group of the substrate and the metal surface of large particles. These catalysts show also good stability without detectable sintering.