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 (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 Co3O4 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 (NH3/CO2-TPD) revealed that component regulation led to more oxygen vacancies and exposure of surface Co2+, 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 CH4 conversion rate was 50% and 90%, respectively) were 318 and 367 degrees 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. (C) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

A novel La-Co-O-C composite was prepared via a co-hydrothermal route and further optimized for methane catalytic activity and thermal stability through component regulation. The results showed that component regulation led to more oxygen vacancies and exposure of surface Co2+, lower surface basicity and optimized acidity, resulting in excellent catalytic oxidation performance.