The significant role of oxygen vacancy in Cu/ZrO2 catalyst for enhancing water–gas-shift performance

• Cu/ZrO2 with highly catalytic activity was fabricated by DH method.
• EPR technique was employed to characterize the coordination environments of Cu2+.
• The present of oxygen vacancies promotes the dissociation of H2O.
• The dispersion and crystal sizes of Cu sites are vital for Cu/ZrO2 catalyst.

Three Cu/ZrO2 catalysts were synthesized utilizing co-precipitation (CP), deposition–precipitation (DP) and deposition–hydrothermal (DH) methods, respectively. The microstructure and texture of those catalysts are characterized by means of XRD, SEM, N2-physisorption, Raman and EPR characterizations. It is demonstrated that different morphologies and textures of ZrO2 are formed, and the micro- and crystal structure of Cu nanoparticles as well as the concentration of oxygen vacancies of ZrO2 are distinguish from each other. In addition, H2-TPR technique is employed to investigate the reducibility properties of the as-synthesized Cu/ZrO2 catalysts. It is found that the synergy interaction between Cu–ZrO2 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/ZrO2-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–ZrO2.

The catalyst prepared by Deposition–Hydrothermal method (Cu/ZrO2-DH) shows the best catalytic activity for CO conversion during the WGS reaction. The reasons are the as-obtained catalyst possesses small crystallite sizes, good Cu particles dispersion, large amount of oxygen vacancies, thus showing stronger synergy interaction between Cu–ZrO2 and higher catalytic activity for the WGS reaction compared to the other two.Figure optionsDownload as PowerPoint slide