Effect of different reaction conditions on catalytic activity of La(Mn, Fe)O3+λ catalyst for methane combustion

Abstract

The La(Mn, Fe)O3+λ catalyst, a novel rare earth perovskite composite oxide catalyst for catalytic combustion, was prepared by sol-gel method, which was at natural gas automobile exhaust catalytic purification, smoke gas catalytically desulfurization and other fields had broad application prospects [–]. The newly developed catalysts were characterized by several complementary techniques. The effects of different reaction conditions such as calcination temperature, citric acid (CA) content and ethylene glycol (EG) content on the catalytic performance of the catalyst were investigated by using low concentration methane catalytic combustion as the probe reaction. The results showed that a stable single-phase rare earth perovskite La(Mn, Fe)O3+λ catalyst could be formed after calcination at 600 °C for 3 h in air atmosphere. When EG/M = 1/2, CA/M = 1/2, the catalyst exhibited good methane catalytic combustion activity in the middle and low temperature regions. The light-off temperature (T10) and complete conversion temperature (T90) were 363 °C and 493 °C, respectively, the surface activation energy was 60 ∼ 80 kJ mol−1, and the catalytic activity was significantly improved. The O2-TPD and XPS characterization results showed that La(Mn, Fe)O3+λ had higher surface Mn4+, Fe3+ and more active oxygen species, which significantly improved the catalytic activity.