Insight into the Effect of Cobalt Substitution on the Catalytic Performance of LaMnO₃ Perovskites for Total Oxidation of Propane

Abstract

Cobalt-substituted LaMnO3 perovskite catalysts synthesized by the citric acid sol–gel method have been investigated for the total oxidation of propane, as a model for emission control of hydrocarbon volatile organic compounds. Characterization studies demonstrate that a trace of cobalt substitution can enhance the specific surface area, produce abundant reactive oxygen species, and improve low-temperature reducibility, which promote the catalytic activities of LaCoxMn1–xO3 catalysts remarkably. LaCo0.2Mn0.8O3 exhibits the highest catalytic activity (T90 = 355 °C), of which T90 is 25 °C lower than that of LaMnO3. In situ DRIFTS and C3H8-TPSR results indicate that the adsorption and activation of propane will be accelerated by appropriate Co substitution and acetone and carboxylate species are considered as intermediates involved in propane oxidation. In addition, the influence of water vapor on the catalytic activity of the LaCo0.2Mn0.8O3 catalyst for propane oxidation is greater than that of CO2, while LaCo0.2Mn0.8O3 can sustain robust stability under CO2 and water vapor atmospheres.