Role of Support Oxygen Vacancies in the Gas Phase Hydrogenation of Furfural over Gold

ABSTRACT: We have examined the role of support oxygen vacancies in the gas phase hydrogenation of furfural over Au/TiO(2) and Au/CeO(2) prepared by deposition–precipitation. Both catalysts exhibited a similar Au particle size distribution (1–6 nm) and mean (2.8–3.2 nm). Excess H(2) consumption during TPR is indicative of partial support reduction, which was confirmed by O(2) titration. Gold on CeO(2) with a higher redox potential exhibited a greater oxygen vacancy density. A lower furfural turnover frequency (TOF) was recorded over Au/CeO(2) than Au/TiO(2) and is linked to suppressed H(2) chemisorption capacity and strong –C=O interaction at oxygen vacancies that inhibited activity. Gold on non-reducible Al(2)O(3) as benchmark exhibited greater H(2) uptake and delivered the highest furfural TOF. Full selectivity to the target furfuryl alcohol was achieved over Au/TiO(2) and Au/Al(2)O(3) at 413 K and over Au/CeO(2) at 473 K with hydrogenolysis to 2-methylfuran at higher reaction temperature (523 K). A surface reaction mechanism is proposed to account for the activity/selectivity response. GRAPHICAL ABSTRACT: [Image: see text]