Abstract:La_0.8Cu_0.2MnO_(3±δ) perovskite-type catalyst for methane combustion prepared through sol-gel process was characterized by X-ray Diffractometry(XRD), X-ray Photoelectron Spectroscopy(XPS) and Scanning Electron Microscopy(SEM). XPS analyses reveal that the surface characteristics of the catalyst are changed. The lattice defects and oxygen vacancies on the catalyst surface are enhanced due to a part of La³⁺ being substituted by Cu²⁺. Temperature-programmed-desorption(TPD) and temperature-programmed-reduction(TPR) analyses were carried out to study the catalytic behavior. It is found that there are two O₂-desorption peaks at 350℃ and 650℃ in the TPD pattern, and two CH₄-consumption peaks at 420℃ and 750℃ in the TPR patterns respectively, which indicates that the two kinds of oxygen species, so-called α and β oxygen, can react with the methane during catalytic combustion process. The catalytic activity tests were performed in a fixed-bed reactor, and the results show that the T_1/2 at which the conversion of methane attains 50% of La_0.8Cu_0.2MnO_(3±δ) is lower by 55℃ than that of LaMnO₃. This indicates that the catalytic activity of La_0.8Cu_0.2MnO_(3±δ) is increased with partial substitution of Cu²⁺ for La³⁺.

Key words: perovskite-type catalyst; methane catalytic combustion; sol-gel; TPD-TPR-MS characterization