铈基复合氧化物中晶格氧用于甲烷部分氧化制合成气

The ceriabased complex oxides oxygen carriers (Ce-M-O, M＝Fe、Mn、Cu ) were prepared by coprecipitation method and their characterizations were studied by means of Xray diffraction (XRD).The reactions between methane and lattice oxygen over the complex oxides were investigated. The Ce-M-O oxygen carriers were regenerated by air oxidation at different reaction times and temperatures, and then the catalytic performances of oxygen carriers for partial oxidation of methane to syngas using lattice oxygen were investigated. The results showed that the Ce-Fe-O sample consisted of single crystal phase and its lattice oxygen was found to be suitable for partial oxidation methane to synthesis gas. There were two kinds of oxygen species in the fresh Ce-Fe-O solid solution. The stronger oxygen species was responsible for the complete oxidation of methane. Methane could be selectively oxidized to CO and H2 by the weaker oxygen specie (bulk lattice oxygen) at a higher temperature, then the lost bulk lattice oxygen could be selectively supplemented by air reoxidation at appropriate reaction conditions. Using the oxygen carrier which was regenerated at 850℃ for 7min, the selectivity of CO and H2 could reach 96.68% and 97.56% respectively and the value of H2/CO mol ratio in syngas was 2.02. In the absence of gas phase oxygen, it is possible to generate syngas using the lattice oxygen of the Ce-Fe-O to react with methane following the redox mechanism.