On-site Refreshing Active Species Responsible for Catalytic Activity During Cooling Catalyst in H2-rich Reaction Atmosphere

While CuxO-CeO2 catalysts have a superb catalytic activity in preferential oxidation of CO, the reduction of CuxO to metallic Cu is inevitable on the surface due to the presence of H-2-rich reaction atmosphere during catalysis, resulting in loss of active species and decreased activity. This work synthesized the CuO/CeO2 catalysts by the hydrothermal method, which consist of highly dispersed CuxO species, CuxO nanoclusters at the Cu-[O-x]-Ce interface, and bulk CuxO on the surface of catalysts. It is found that the highly dispersed CuxO clusters is responsible for low-temperature activity, and the CuxO clusters at the Cu-[O-x]-Ce interface play an important role at high temperature. After three cycle tests, the spent-10CuO/CeO2 catalyst is shown to be on-site regenerated during cooling process due to the synergy between copper and cerium species as well as strong interaction between the support and reactant molecules with fully accessible H-2. The CeO2 suffers dynamic transformation during the cooling process when the copper and cerium species interact with reactant molecules. Understanding such dynamic process can help to reveal the evolution of the catalyst in the reaction atmosphere.