NiO-doped Au/Ti-powder: A catalyst with dramatic improvement in activity for gas-phase oxidation of alcohols

An active and stable NiO@Au/Ti-powder catalyst, which can be obtained by doping Au/Ti-powder (Au: 35-40 nm) with NiO, has been developed for the gas-phase oxidation of alcohols. Gold particles are found to be partially covered with tiny NiO segments to form specific NiO@Au ensembles thereby leading to a dramatic conversion improvement from only ∼5% (without NiO doping) to ∼94% for the benzyl alcohol oxidation at 280 C. Additionally, the selective oxidation of cyclopropyl carbinol can proceed over this catalyst at 280 C with a selectivity of 94% and a conversion of 72-80% throughout the entire 300 h test. The hybrid active-sites, Ni₂O₃-Au⁺, on the NiO@Au ensemble are identified using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS).