Au/CeO2 supported nanocatalysts: Interaction with methanol

The effect of preparation procedure (Direct Anionic Exchange, DAE, Deposition-Precipitation, DP, and wet Impregnation, IMP) and Au/Ce atomic ratio (0.018 and 0.066) on Au/CeO2 supported nanocatalysts was investigated with respect to reactivity. XPS data suggest the presence of traces of Ce(III). Usually, gold is present as Au(0) but in the DAE sample with high Au content, traces of oxidized species are observed. The Au/Ce XPS atomic ratio is lower than the expected value. Au deposition decreases surface interaction with atmospheric moisture and carbon dioxide. Methanol interacts molecularly and dissociatively with the samples; methoxy groups are observed to be mono-coordinated at Ce(IV) at room temperature and bi-coordinated to Ce(IV) and Ce(III) at increasing temperature. Oxidation products (formates, carbonates, carbon dioxide) form at temperatures higher than 373-423 K; activity and selectivity in methanol oxidation reaction are influenced by the metal content and the preparation procedure.