Highly active Pd catalysts supported on surface-modified cobalt-nickel mixed oxides for low temperature oxidation of lean methane

Abstract A highly active palladium catalyst supported on SiO2-modified cobalt-nickel mixed oxide (denoted as 0.5Pd/M-Co1Ni4) was prepared and used for lean methane combustion. It was found that such a surface modification strategy enhanced the synergistic interaction between deposited palladium phase and reactive cobalt-nickel oxide, leading to substantial improvement in performance towards methane combustion. Over 0.5Pd/M-Co1Ni4, 90% methane conversion was realized at 323℃ and a space velocity of 60,000 mLg−1 h−1, which is 62 °C lower than that required for its untreated counterpart, 0.5Pd/Co1Ni4. The results of XRD, TEM, transmission FTIR and XPS demonstrated that the introduced SiO2, which was presented as an amorphous phase covering the carrier surface, could effectively tune the electronic structure of both Co1Ni4 support and palladium entities. More importantly, H2-TPR and O2-TPD results of 0.5Pd/M-Co1Ni4 revealed that the presence of SiO2 could enhance the low-temperature redox capability and increase the supply of oxygen species during the reaction process. We believe that the combination of PdOx (1