Promoted the reduction of Cu2+ to enhance CuO-CeO2 catalysts for CO preferential oxidation in H2-rich streams: Effects of preparation methods and copper precursors

A series of CuO-CeO2 catalyst samples synthesized by using various methods (CuCe-SF-N, CuCe-UGC-N, CuCe-SG-N and CuCe-ST-N) and copper precursors (CuCe-SF-N, CuCe-SF-C, CuCe-SF-A and CuCe-SF-S) were estimated for CO preferential oxidation in H-2-rich streams. It was found that both synthesis routes and copper precursors have an important effect on catalytic behaviors of CuO-CeO2 catalyst. Compared to CuCe-UGC-N, CuCe-SG-N and CuCe-ST-N, CuCe-SF-N exhibits the lowest temperature and the widest temperature window for 100% CO conversion (about 50 degrees C), which should be attributed to synergistic effects of smaller crystallite size, the formation of more Cu+ species together with the high ratio of Ce3+/(Ce3++Ce4+). Among the four catalysts prepared with different Cu precursors (CuCe-SF-N, CuCe-SF-C, CuCe-SF-A and CuCe-SF-S), the corresponding CO conversions of them are in the order of CuCe-SF-N > CuCe-SF-A > CuCe-SF-C CuCe-SF-S. The lowest catalytic activity of CuCe-SF-S should be due to the presence of SO42- species covered on the surface of the catalyst, which not only results in the formation of the less Cu active species but inhibits the interaction between Cu species and CeO2. In addition, the optimal CuCe-SF-N catalyst displays relative stability during the 200 h time-on-stream test even in the presence of H2O and CO2. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.