新型La2CuMnO6和LaMnO3催化剂的甲烷燃烧催化性能比较

Catalytic Performance Comparison of the Novel Catalyst La_2CuMnO_6 and LaMnO_3 for Methane Combustion

采用溶胶-凝胶法在空气气氛下于1100℃焙烧3 h后制备了一种新型单相稀土双层钙钛矿催化材料La2CuMnO6,测试了其甲烷催化燃烧反应性能.该化合物对甲烷催化燃烧反应表现出较好的催化活性,起燃温度(T10)和完全转化温度(T90)分别为437.5和649.2℃,在相同条件下与稀土单层钙钛矿型催化剂LaMnO3相比,其T10和T90分别降低了53.1和116.5℃.XPS结果显示,La2CuMnO6氧空位浓度相对较大,此外,La2CuMnO6与LaMnO3相比,其TPR谱、SEM、TEM和磁性明显不同,并与其甲烷催化燃烧活性有一定的对应关系.

A novel rare-earth double perovskite-type catalyst La2CuMnO6 was prepared by the sol-gel method using citric acid as a complex agent.The catalytic activity of the sample toward methane combustion was evaluated.The catalyst was characterized by X-ray diffraction,Fourier transform infrared spectroscopy,magnetic properties,H2-temperature-programmed reduction,Scanning electron microscopy and X-ray photoelectron spectroscopy.The results show that La2CuMnO6 forms a single-phase double perovskite-type oxide by the sol-gel method at 1100 ℃ under air atmosphere for 3 h.The La2CuMnO6 reveals good catalytic activity for methane combustion.It shows light off temperature T10 of 437.5 ℃ and T90 of 649.2 ℃.Compared with the single perovskite-type oxide LaMnO3 which always was made for methane combustion catalyst,the lower light-off temperature T10 decreases 53.1 ℃ and total conversion T90 decreases 116.5 ℃,respectively.The results of FTIR show that the synthesized oxides all possess perovskite-type structures.The results of H2-TPR indicate that an increasing in the oxygen mobility existe in La2CuMnO6.Furthermore,The SEM,TEM and the magnetic properties results also testified that,the two catalysts have different surface feature and magnetic property,In addition,XPS shows that La2CuMnO6 have more oxygen vacancies than LaMnO3.These results are in the accord with methane catalytic combustion.