Effect of CeO_2 Support Preparaed with Different Methods on the Activit and Stability of CuO/CeO_2 Catalysts for the Water-Gas Shift Reaction

Three CeO2 materials were prepared with precipitation (A), hydrothermal route (B) and citrate sol-gel (C) methods, and then used as the support of CuO/CeO2 catalysts, which were prepared by a deposition-precipitation method and examined with respect to their catalytic activities for the water-gas shift (WGS) reaction. The effect of the CeO2 support prepared with different methods on the structural properties, redox properties, catalytic activities and stabilities of the CuO/CeO2 catalysts for the WGS reaction was studied in detail using N2 physics adsorption (Brunauer- Emmett-Teller, BET), powder X-ray diffraction (PXRD), in situ PXRD, H2-temperature programmed reduction (H2-TPR) and cyclic voltammetry (CV). Results indicate that both the catalytic activities and stabilities of the as -synthesized CuO/CeO2 catalysts are CuO/CeO2-ACuO/CeO2-BCuO/CeO2-C. Characterization results show that catalytic activities of the CuO/CeO2 catalysts are closely related to the crystal size of CuO particles, the microstrain value for CuO, and the amount of moderate size copper oxides (crystalline) that interacted with ceria. These factors depend greatly on the thermal stabilities of the CeO2 supports. CV results suggest that the peak area of Cu2+圮Cu0 redox reaction decreased from the first to the second cycle, indicating that the electrode reaction is irreversible and this might be a reason for the observed deactivation of CuO/CeO2 catalysts after the temperature cycle.