Highly active Y-promoted CuO/ZrO₂ catalysts for the production of hydrogen through water-gas shift reaction

ZrO₂ doped with various concentrations of yttrium(0-5%) was prepared by a hydrothermal homogeneous co-precipitation method and CuO was then deposited on ZrO₂ by a deposition-precipitation method to get the yttrium promoted CuO/ZrO₂ catalyst; its performance in the water-gas shift reaction for producing hydrogen was then investigated. The results indicate that the catalytic activity of CuO/ZrO₂ can be effectively improved by yttrium modification; over the yttrium promoted CuO/ZrO₂ catalyst with an yttrium concentration of 2%, the CO conversion reaches 91.4% at 270℃, much higher than those over the conventional CuO/ZnO and CuO/CeO₂ catalysts. The XRD, N₂-physisorption, N₂O titration, SEM and CO-TPR characterization results reveal that Y³⁺ is successfully incorporated into the lattice of ZrO₂, which has a great influence on the structure and reducibility of the CuO/ZrO₂ catalysts. Y³⁺ doping into ZrO₂ introduces oxygen vacancies, improving the dispersion of CuO and increasing the proportion of catalytically active Cu-O-Zr species. In addition, the introduction of yttrium improves the monodispersity and modifies the texture properties of the CuO/ZrO₂ catalysts. As a result, the superior activity of 2% yttrium promoted CuO/ZrO₂ catalyst is probably attributed to the abundance of Cu-O-Zr species, high reducibility of Cu-O-Zr species and surface hydroxyl groups, high monodispersity and proper textural properties.