Methane Combustion Catalyst For Microwave-assisted Synthesis And Properties

Methane,the richer in nature, is a promising clean energy source which has been received attention recently. But there is a problem of inefficiency and lots of pollution in the conventional flame combustion. It is an efficient way to resolve the question by catalytic combustion, which is the unremitting pursue of the catalytic workers. Recently, microwave-assisted synthesis was introduced into the field of materialsIn this dissertation, Mn-base perovskite catalysts were successfully prepared by microwave irradiation processing using only several minutes for heat treatment. Compared with the sol-gel method microwave irradiation processing has the advantages, such as fast reaction velocity, energy conservation, and environment-friendly. Firstly, the LaMnO_3.15 was synthesized by microwave irradiation processing, then investigated the catalytic activity effect of dopping with alkaline-earth metals (Ca,K,Ba,Sr) and noble metals(Ag,Pd). It is found that replaced La with alkaline-earth metals can promote the catalytic activity of Mn-base perovskite compound oxide in the methane combustion. in which the samples of substituting Ba for La performed the best activity. A series of catalysts of higher activity were obtained; The methane conversion can reach 100% at 550℃over La_0.85Ba_0.15MnO_3.15. It also has the better activity in the catalysts replaced by Sr. The catalytic effect of La_0.9Sr_0.1MnO_3.15 is prominent. Among the dopping of noble metal, substituting Ag for La performed better activity than that of Pd. It is characterized the phase and morphology by XRD, Raman and SEM, investigated the reducibility and the distribution of species by XPS, H₂-TPR and O₂-TPD, suggesting that the samples prepared by microwave irradiation processing possesses relative higher surface area, the increase in Mn4+ and oxygen vacancy content and the enhancement in the mobility of lattice oxygen which play an important role part in the methane combustion.In addition, it is investigated the effect of catalysts prepared by microwave irradiation processing and conventional heat in methane combustion. It is found the catalytic activity of the former was better than the latter. It made know that the carrier didn't be destroyed during the process of Pd loading. MIP-90s performed the best activity. There were the most Pd and the oxygen vacancies on surface of MIP-90s, which was investigated by the XPS. They are important factors in methane combustion.