| La-B-Sn-O (B=Mn, Fe, Co, Ni, Cu) system composite oxide catalysts were prepared by sol-gel method. The catalytic activity of the samples' was tested in methane combustion. And we characterized their composition, structure, infrared spectrum, Specific and Surface area, electrical conductivity and appearance by means of XRD, FI-IR, TPR, BET, TEM, and electrical conductivity test and so on.The experiment results showed that under 1100℃for 3h, La-Mn-Sn-O, La-Fe-Sn-O, La-Co-Sn-O systems accordingly formed two phases as perovskite oxide LaMn0.8O3, FeLaO3, LaCoO3 and pyrochlore La2Sn2O7. And the La-Ni-Sn-O, La-Cu-Sn-O systems also formed two phases as double perovskite oxide La2NiSnO6, La2CuSnO6 and La2Sn2O7. Test revealed that the catalytic activity was best of all samples in La-Mn-Sn-0 system of which the T10 and T90 were 440℃and 628℃. Nest was La-Co-Sn-O system, with 496℃and 692℃for T10 and T90. The catalytic activity was a little lower in La-Ni-Sn-O system than that of La-Co-Sn-O system, and lowest in La-Fe-Sn-O and La-Cu-Sn-O systems.In order to compare the catalytic activity of La-Mn-Sn-O and La-Co-Sn-O systems with their phases of the systems contained respectively, this paper tested their catalytic activity based on preparing single-phase LaCoO3, LaMnO3 and La2Sn2O7 by the same method. Research showed that the catalytic activity of La-Mn-Sn-O and La-Co-Sn-O systems was higher than any phase they contained solitarily, which was credited to the cooperating effect of LaMnO3/La2Sn2O7, LaCoO3/La2Sn2O7 in the system.The main phase of La-Ni-Sn-O system was La2NiSnO6, this system sample was prepared by different ways including sol-gel-microwave- method, homogenous- precipitation-drying cabinet dry method and homogenous-precipitation supercritical dry method. The activity of single-phase La2NiSnO6 which here prepared by sol-gel-microwave- method was to some extent enhanced thus indicates that La2NiSnO6 was a good catalyst for methane combustion.
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