Preparation Of Lanthanum Manganese Perovskite Catalysts And Their Catalytic Performance For Methane Combustion

With the development of modern industrial technology, people demand for energy increases, the resulting environmental problems get more and more attention, methane catalytic combustion technology is an important mean to restrain NOx emissions. Methane catalytic combustion technology can make methane react with oxygen at low temperature and release energy. The paper take LaMnO3+δas the research object,investigate the influence of the difFerentcomplexing agents、 the roasting time the heating rate、 metal ion concentration in the solution and Fe doped in B bit on the structure of the catalysts and its catalytic performance for catalytic combustion methane, The structure andtextural properties of the synthesized catalysts were characterized via the XRD,BET,H2-TPR,O2-TPD,and XPS techniques.Thecatalysts prepared with citric acid has uniform crystal phase, the high content of activated oxygen and high valent manganese ions contributed to the high activity for catalytic combustion methane. The proper the roasting time and heating rate may increase the contenthigh valent ions and thethermal stability of the catalyst. Too long roasting time make catalyst sinter, fast heating rate lower the activity ability of the surface-adsorbed oxygen, and produce more impurity phase, then have a bad influence of catalytic combustion methane. With the higher metal ion concentration in the solution will increase the content of nonstoichiometric oxygen, but decrease the surface-adsorbed oxygen and high valent ions, even reduce thethermal stability of the catalyst which were not conducive to the combustion of methane. When doped Fe in B bit, the surface-adsorbed oxygen and thermal stability of the catalyst decreased, so the activity decrease.When using hard template prepared catalyst, add ethanol in solution will be appropriate to increase the surface- adsorbed oxygen of the catalyst, thermal stability and Mn4+ content.Compared with the catalyst prepared by conventional sol-gel method, the catalystprepared by hard template has large specific surface area, it can absorb more oxygen for the oxidation of methane, also has the high Mn4+ content and O22-/O-, as well as best catalytic activity for methane catalytic combustion.its Tio and T50 is 318℃ and 480℃ respectively, which is much less than the 380℃ and 532 ℃ catalyst prepared by conventional sol-gel method.