Highly active gold-ceria catalyst for the room temperature oxidation of carbon monoxide

Abstract

Ceria supported gold catalysts containing 0.1–5 wt.% gold are prepared by deposition–precipitation technique in which the precipitate is subjected to ultrasound treatment and aging in the parent solution at 65 °C for 2 h prior to filtration and drying. The catalysts are found to be very active for the room temperature oxidation of CO. Au/CeO 2 catalyst containing as low as 1 wt.% Au is found to be a highly active catalyst for the room temperature oxidation of CO to CO 2 with complete conversion of CO and specific activity up to 490 × 10 −4 mol CO s −1 g Au −1. The catalyst shows good stability and sustains its high activity for a prolonged period. Aging of the catalyst in the parent solution is found to be important in obtaining a highly active catalyst. The catalysts are characterized by XRD, SEM, TEM, XPS and TPR/TPD. TPR, TPD and XPS studies suggest that the active site for CO oxidation may be a combination of Au + OH − and metallic gold in interface with reduced Ce 3+ sites. In other words, the presence of highly dispersed gold particles in close contact with the ceria surface defects is vital for the superior performance of the catalyst.