Synergistic metal-support interaction promoting the formation of oxygen vacancies and their role in CO-PROX over CuO/NiO-CeO2 catalyst

Abstract

A series of x/yCuO/NiO-CeO2 catalysts with a constant Cu+Ni molar content and low copper loading of 1 wt% had been prepared by the step-by-step impregnation method and characterized by various techniques (XRD, N2-adsorption/desorption, HR-TEM, H2-TPR, Raman and XPS). CO preferential oxidation (CO-PROX) under H2/CO2-rich conditions had been performed. Experimental results indicated that the catalytic activity of CuO/CeO2 could be enhanced by substituting partial Cu with Ni, and with a Cu/Ni molar ratio of 1/2, the highest catalytic performance was observed. Under the conditions of temperature 130 ℃, space velocity 20266 mL·gcat−1·h−1 and oxygen excess coefficient 1.2, the 1/2CuO/NiO-CeO2 catalyst gave rise to a maximum CO conversion of about 94.8%. The 1/2CuO/NiO-CeO2 catalyst also exhibited good catalytic stability up to 100 h, showing that this catalyst system could be further developed for potential commercial application. Combined with the detailed characterization data, it had been proposed that there was a synergistic interaction among Cu, Ni and CeO2 in the catalyst, generating more oxygen vacancies than the binary CuO/CeO2 and NiO/CeO2 catalysts. With a Cu/Ni molar ratio of 1/2, the formed ternary CuO/NiO-CeO2 catalyst had the highest content of oxygen vacancies, which was believed to play a crucial role in the CO-PROX reaction.