Reactions CuO-M_xO_y Water Gas Shift Catalysts

It is the key for commercialization of fuel cell to seach a catalyst which has high activity and stability at low temperatures in water-gas shifts reaction. Both of industral middle-temperature Cu-Zn and high-temperature Fe-Cr catalysts can’1meet the requirements of fuel cell at low temperature. The double-function CuO-CeO2and CuO-Fe2O3catalysts were expected to solve the problem including catalysts by changing the preparation method, constituent ratio and doping another oxide in this paper. The physical and chemical properties of catalysts were characterized by means of N2-physical adsorption, Transmission Electron Microscope (TEM), scanning electron microscope (SEM), X-Ray Powder Diffraction (XRD), Diffuse Reflectance Spectrophotometry (UV-vis DRS), Temperature Programmed Reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). These results are combined with activities to get some valuable conclusions.The main results in this paper summarize as follows:1. The preparation method, constituent ratio, H2reduction temperature and the way of precipitator adding were optimized for CuO-CeO2catalyst. Beyond that, the CeO2was replaced by other oxsides to find a better support. The result shows that,20%CuO-CeO2catalyst prepared by co-precipitation with cocurrent flow of precipitator shows the better activity after H2reduced at200℃by improving the dispersion and lowering the reducing temperature. Cu0and Cu+as the active sites appeare after CuO-CeO2catalyst reduced by H2, while excessive reducing will damage the interaction of CuO and CeO2resulting in active drpping.2. The constituent ratio, calcination temperature and H2reduction temperature were investigated for CuO-Fe2O3catalyst. It turns out that:50%CuO-Fe2O3and60%CuO-Fe2O3catalysts calcinated at500℃gave the best activity after H2reduced at200℃and CO conversion were respectively52.8%and54.8%. Cu0and Cu+are considered as the active sites while the interaction of CuO and Fe2O3can not be ignored. CuFe2O4as a new phase reflects the interaction and is conducive to increase the CO conversion. The50%CuO-Fe2O3catalyst occured some sinter after reacted for30h suggests it is not stable under the reaction conditions.3. NiO, Al2O3or CeO2added in50%CuO-Fe2O3catalyst is helpful to increase activity by improving the dispersion and becomes more stable. The highest CO conversion of2.5%Al2O3-50% CuO-Fe2O3catalyst was82%which appeared little sinter after reacted30h. In conclusion,2.5%Al2O3-50%CuO-Fe2O3catalyst shows high activity and stability at low temperature.