Engineering stable active Cu0-Cuσ+ sites via in situ surface reconstruction over Cu/CeO2 catalyst for the hydrogenation of carbon-oxygen bonds

Abstract

Cu/CeO2 catalysts have been wildly used for the hydrogenation of carbon-oxygen bonds reactions due to their excellent catalytic performance. It is widely accepted that the Cu0-Cuσ+ interface could be the primary active sites during the reaction, but how to form and maintain highly dispersed such species remains challenging under the reaction conditions of high temperature and H2 partial pressure. In this work, we proposed an effective strategy to construct stable Cu0-Cuσ+ interface sites over the Cu/CeO2 catalysts by in situ N2O-involved oxidation treatment. It was evidenced that the sequential oxidation-reduction by N2O and H2 broke the grain boundaries of Cu nanoparticles and therefore facilitated the formation of the active Cu0-Cuσ+ sites, leading to an enhanced activity. However, a rapid deactivation was observed after this temporary enhancement due to the aggregation of copper species. We further introduced some additional cerium species during catalyst preparation. The 16Cu/CeO2-1Ce catalyst prepared by post-impregnation of 1 wt% cerium achieved a stable performance of 90.6% MA conversion after the N2O-involved oxidation treatment, which was much higher than that of 26.2% over the 16Cu/CeO2 catalyst. It was demonstrated that the strong interaction between the formed CeO2 and reconstructed Cu species prevented the metal sintering and increased the fraction of the Cu0-Cuσ+ sites. This method that combined in situ N2O-involved oxidation treatment and cerium modification may offer potential in engineering stable active sites for high-performance catalysts in the hydrogenation of carbon-oxygen bonds.