Effects of ZrO2 addition to the Au/CeO2 and the pretreatment methods of the catalysts on the partial oxidation of methanol (POM) were investigated. ZrO2 addition to Au/CeO2 catalyst led to (i) formation of a Ce0.5Zr0.5O2 solid solution; (ii) enhancement of lattice oxygen reducibility of the Ce0.5Zr0.5O2 support; and (iii) formation of surface Auδ+ (δ = 1 or 3) species coexisting with Au0 nanoparticles. Catalytic evaluation showed that the highest hydrogen selectivity was achieved over Au/Ce0.5Zr0.5O2 at 270 °C. The reductive pretreatment could improve the hydrogen selectivity and methanol conversion as well. At higher reaction temperature Auδ+ clusters in Au/Ce0.5Zr0.5O2 catalyst activated the O‒H bond in the adsorbed CH3‒Oδ−‒Hδ+ due to the interaction between Auδ+ and Oδ−‒Hδ+ of methanol that favors the release of H+ proton, and thus benefits the H2 selectivity enhancement. Some oxygen vacancies in the catalysts evidenced by XPS analysis participated in the formation of active surface oxygen species that promoted CO oxidation to CO2 on Au0 nanoparticles A reaction mechanism of POM involving in the methanol surface adsorption on Auδ+ species, O‒H bond activation, and CO oxidation on Au0 nanoparticles and oxygen defects was proposed. Graphic abstract: [Figure not available: see fulltext.].
- Hydrogen production
- Partial oxidation of methanol