Effect of hydrothermal synthesis time on the performance of Cu/Ce-Zr catalysts for catalytic water-gas shift reaction

Ce-Zr oxide support was hydrothermally synthesized from metal nitrates of cerium and zirconium as the raw materials using citric acid instead of alkali precipitant, and then Cu/Ce-Zr catalyst was prepared by the impregnation method. The support and catalyst samples were characterized by XRD, BET, H₂-TPR, XPS techniques, and the effects of different hydrothermal time on the structure, properties and performance in water-gas shift reaction were investigated. The results show that the catalyst activity is mainly related to the Cu specific surface area, reduction temperature of CuO and the number of oxygen vacancies on the catalyst surface. Among them, the Cu/Ce-Zr catalyst with hydrothermal time of 12 h has a large Cu specific surface area, a lower reduction temperature of CuO, and a large number of oxygen vacancies, so it shows a good catalytic activity. When the reaction temperature is 320 ℃, the molar ratio of water to gas (W/M) is 2, and the gas space velocity GHSV=6600 h⁻¹, the CO conversion rate is 96.9%, which is close to the thermodynamic equilibrium value of 97.1%.