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/TiO₂ and Au/CeO₂ prepared by deposition–precipitation. Both catalysts exhibited a similar Au particle size distribution (1–6 nm) and mean (2.8–3.2 nm). Excess H₂ consumption during TPR is indicative of partial support reduction, which was confirmed by O₂ titration. Gold on CeO₂ with a higher redox potential exhibited a greater oxygen vacancy density. A lower furfural turnover frequency (TOF) was recorded over Au/CeO₂ than Au/TiO₂ and is linked to suppressed H₂ chemisorption capacity and strong –C=O interaction at oxygen vacancies that inhibited activity. Gold on non-reducible Al₂O₃ as benchmark exhibited greater H₂ uptake and delivered the highest furfural TOF. Full selectivity to the target furfuryl alcohol was achieved over Au/TiO₂ and Au/Al₂O₃ at 413 K and over Au/CeO₂ 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: [Figure not available: see fulltext.]