The significant role of oxygen vacancy in Cu/ZrO_2 catalyst for enhancing water-gas-shift performance

摘要

Three Cu/ZrO_2 catalysts were synthesized utilizing co-precipitation (CP), deposition -precipitation (DP) and deposition-hydrothermal (DH) methods, respectively. The micro-structure and texture of those catalysts are characterized by means of XRD, SEM, N_2-physisorption, Raman and EPR characterizations. It is demonstrated that different morphologies and textures of ZrO_2 are formed, and the micro- and crystal structure of Cu nanoparticles as well as the concentration of oxygen vacancies of ZrO_2 are distinguish from each other. In addition, H_2-TPR technique is employed to investigate the reducibility properties of the as-synthesized Cu/ZrO_2 catalysts. It is found that the synergy interaction between Cu-ZrO_2 obtained by the DH method is the strongest, owning to the possession of the largest amount of oxygen vacancies. Furthermore, their catalytic activities with respect to the water gas shift reaction are also performed, and the Cu/ZrO_2-DH shows high catalytic activity, the reasons are the well dispersion and small crystallite size of Cu, the largest amount of oxygen vacancies, as well as the strongest interaction between Cu-ZrO_2.