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 ...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 Co3O_(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 T50and T90(the temperature at which the CH_(4)conversion rate was 50%and 90%,respectively) were 318 and 367℃,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 carboncontaining composites.展开更多
基金supported by the National Natural Science Foundation of China (No.U20A201714)Hebei Education Department (No.QN2021059)Natural Science Foundation of Hebei Province (Nos.B2021208033 and B2021208040)。
文摘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 Co3O_(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 T50and T90(the temperature at which the CH_(4)conversion rate was 50%and 90%,respectively) were 318 and 367℃,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 carboncontaining composites.
