CuO/ZrO2 catalysts for the production of H2 through the water-gas shift reaction: Effect of calcination temperature of ZrO2

A series of CuO/ZrO2 catalysts were prepared by a deposition-precipitation method using ZrO2 calcined at various temperatures (120, 250, 350 and 450℃) as supports. The water-gas shift (WGS) reaction was carried out on these catalysts using H2 rich reactant gas (15% CO, 55% H2, 23% N2, 7% CO2). It was shown that the catalytic activity of the catalysts increased at first and then decreased with increasing calcination temperature of ZrO2. The catalyst supported on ZrO2 calcined at 250℃ showed the highest catalytic activity. The structure and reducibility of CuO/ZrO2 catalysts were studied by various techniques, such as XRD, N2-physisorption, N2O titration, H2-TPR and CO-TPR-MS. The results show that the Cu dispersion and the proportion of catalytically active Cu-[O]-Zr species ([ ] represents an oxygen vacancy on ZrO2 support) decrease with the increase of ZrO2 calcination temperature. The calcination of ZrO2 at higher temperature leads to an improvement of the reducibility of Cu-[O]-Zr species and hydroxyl groups on the CuO/ZrO2 catalysts, resulting in an easier onset of the surface WGS reaction between surface hydroxyl groups and CO reductant. The two factors reach a balance for the catalyst supported on ZrO2 calcined at 250℃ (moderate temperature), as is thought to be responsible for the highest WGS activity of this catalyst. © 2019, Science Press. All right reserved.