Component regulation in novel La-Co-O-C composite catalyst for boosted redox reactions and enhanced thermal stability in methane combustion

• A novel La-Co-O-C composite (LC-C) is synthesized by co-hydrothermal route with oxides and glycerol. • The catalytic performance is optimized via component regulation for methane oxidation. • The catalytic mechanism of the composite changes from “Two-term” to “Rideal-Eley” with addition of Co. • The thermal stability of the La 2 O 2 CO 3 species is enhanced by component regulation. A novel La-Co-O-C (LC-C) composites were prepared via a facile co-hydrothermal route with oxides and glycerol and further optimized for methane catalytic activity and thermal stability via component regulation. It was demonstrated that Co 3 O 4 phase was the main component in regulation. The combined results of X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of oxygen (O 2 -TPD), temperature-programmed reduction of hydrogen (H 2 -TPR), temperature-programmed desorption of ammonia/carbon dioxide (NH 3 /CO 2 -TPD) revealed that component regulation led to more oxygen vacancies and exposure of surface Co 2+ , lower surface basicity and optimized acidity, which were beneficial for adsorption of active oxygen species and activation of methane molecules, resulting in the excellent catalytic oxidation performance. Especially, the (3.5)LC-C (3.5 is Co-to-La molar ratio) showed the optimum activity and the T 50 and T 90 (the temperature at which the CH 4 conversion rate was 50% and 90%, respectively) were 318 and 367°C, respectively. Using theoretical calculations and in situ diffuse reflection infrared Fourier transform spectroscopy characterization, it was also found that the catalytic mechanism changes from the “Rideal-Eley” mechanism to the “Two-term” mechanism depending on the temperature windows in which the reaction takes place. Besides, the use of the “Flynn-Wall-Ozawa” model in thermoanalytical kinetics revealed that component regulation simultaneously optimized the decomposition activation energy, further expanding the application scope of carbon-containing composites.