不同载体铈基催化剂部分氧化甲烷制合成气研究

Study on the CeO_2-Based Catalysts with Different Supports for Partial Oxidation of Methane to Syngas

研究不同载体(TiO2,MgO和Al2O3)负载的铈基催化剂在熔融盐中利用晶格氧直接部分氧化甲烷制合成气。结果表明:反应温度升高对10%CeO2/MgO催化剂的CH4转化率和H2选择性影响较小,且反应开始阶段几乎检测不到CO的存在;在反应温度825℃前10%CeO2/Al2O3催化剂的CH4转化率、H2选择性和10%CeO2/MgO催化剂相差不大,但随反应温度的升高CH4转化率、H2选择性远高于10%CeO2/MgO催化剂,并且10%CeO2/Al2O3催化剂具有最大的比表面积;10%CeO2/TiO2催化剂的活性较小,其CH4转化率、CO和H2选择性都低于10%CeO2/Al2O3催化剂。研究800℃反应温度下3种催化剂的氧化-还原循环性能,结果表明:5次循环反应后10%CeO2/MgO、10%CeO2/TiO2和10%CeO2/Al2O3催化剂均出现衰减现象,衰减程度分别为31.4%、14.8%和6%。10%CeO2/Al2O3催化剂表现出较好的热稳定性。

The CeO2based catalysts with different supports（TiO2, MgO and Al2O3） were investigated in the direct partial oxidation of methane to syngas using their lattice oxygen in molten salt. The results showed that the rising of reaction temperature had little effect on the methane conversion and H2 selectivity of the 10% CeO2/MgO catalyst, and the content of CO couldn＇t be detected at the initial stage of reaction. Above 825℃, the methane conversion and H2 selectivity of the 10% CeO2/ Al2O3 catalyst had no obvious difference from the 10% CeO2/ MgO catalyst＇s, but the methane conversion and H： selectivity of the 10% CeO2/ Al2O3 catalyst were more higher than the 10% CeO2/ MgO catalyst＇s as the reaction temperature raising, and the 10% CeO2/ Al2O3 catalyst had the biggest area surface. The reactivity of the 10% CeO2/ TiO2 catalyst was lower, and its methane conversion, H2 and CO selectivity were all lower than the 10% CeO2/ Al2O3 catalyst＇s. The oxidation-reduction cycles of the catalysts were tested at the reaction temperature 800℃, and the results indicated that the capability of the 10%CeO2/MgO, 10%CeO2/TiO2 and 10%CeO2/Al2O3 catalysts exhibited reduction by the different degrees of 14.8%, 31.4% and 6%, respectively. The 10% CeO2/Al2O3 catalyst had better heat stability.