Manganese-promoted cobalt oxide as efficient and stable non-noble metal catalyst for preferential oxidation of CO in H2 stream

摘要

The modification by MnO_x significantly enhanced the activity and stability of Co3O4 for the preferential oxidation of CO in H2-rich stream. The MnO_x-promoted Co3O4 catalyst with a Mn/Co molar ratio of 1/8 exhibited the best performance; CO conversion was 56% at 40 °C and increased to >90% as the temperature was raised to >75 °C. This catalyst could provide 100% CO conversion at 125-175 °C. CO conversions of 97% and 100% remained unchanged for 100 h at 100 and 125 °C, respectively, whereas the deactivation was observed over Co3O4 alone. Our characterizations using XRD, XPS and TEM indicated that the modification of Co3O4 with MnO_x caused the formation of smaller Mn_xCo_(3-x)O4 solid-solution particles. The O2-TPD, CO-TPD, and pulse reaction studies suggest that the incorporation of MnO_x into Co3O4 increased the amounts of reactive oxygen species and adsorbed CO species over catalyst surfaces and enhanced the regeneration ability of the reduced catalyst by O2. All these enhancements are proposed to be responsible for the improved catalytic performance of the MnO_x-promoted Co3O4.