A Comparative Study of Supported and Bulk Cu–Mn–Ce Composite Oxide Catalysts for Low-Temperature CO Oxidation

Abstract

A series of supported and bulk Cu–Mn–Ce ternary oxide catalysts was synthesized by wet-impregnation (IM), deposition–precipitation (DP), traditional co-precipitation (CP), co-precipitation with cetyltrimethyl ammonium bromide (CC), and sol–gel (SG) methods. The supported catalysts (CuMn/Ce-IM, CuMn/Ce-DP) exhibited significantly higher activity for CO oxidation than the bulk catalysts (CuMnCe-CP, CuMnCe-CC and CuMnCe-SG). The improved performance could be attributed to the presence of more isolated CuO and MnOx entities on the surface of supported catalysts, which contributed to the efficient utilization of both lattice oxygen from CeO2 and spillover oxygen from surface MnOx. For bulk catalysts, major Cu–Mn species were doped to form $${\text{C}}{{\text{u}}_{\text{x}}}{\text{M}}{{\text{n}}_{\text{y}}}{\text{C}}{{\text{e}}_{1 - {\text{x}} - {\text{y}}}}{{\text{O}}_{2 - {\text{z}}}}$$ solid solutions and a part of them were coated by ceria mechanically. Lowest 50% CO conversion temperature were achieved at 76.9 °C for CuMn/Ce-IM catalyst. Low-temperature CO oxidation activities of all catalysts were in the sequence of CuMn/Ce-IM > CuMn/Ce-DP > CuMnCe-SG > CuMnCe-CC > CuMnCe-CP.