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采用柠檬酸络合法制备了NiO-CeO2-TiO2复合氧化物并将其用于甲烷部分氧化反应,考察了柠檬酸加入量、Ce/Ti原子比、焙烧温度和镍组分含量对催化剂活性的影响.结果表明,NiO-CeO2-TiO2对甲烷部分氧化反应具有很高的活性和稳定性.在原料气体积组成为20%CH4,10%O2和70%N2,GHSV=55 200 ml/(g.h),反应温度在650~850℃范围内,700℃焙烧的10%NiO-Ce0.50Ti0.50O2催化剂具有最高的CH4转化率和H2选择性,750℃下经50 h连续测试后,其活性和选择性仍保持在较高水平.催化剂的XRD和TPR表征结果说明NiO处于高分散状态;在NiO-TiO2催化剂中,NiO与TiO2发生固相反应并以NiTiO3形式存在,而NiTiO3比与载体发生相互作用的表面NiO难还原;加入CeO2可以形成Ce-Ti-O固溶体,对NiO和TiO2的固相反应有抑制作用,有利于提高催化剂的中低温反应活性,同时NiTiO3对甲烷部分氧化反应也具有催化活性.
NiO-CeO2-TiO2 composite oxide was prepared by citric acid complexation method and used for partial oxidation of methane. The effects of the addition amount of citric acid, atomic ratio of Ce / Ti, calcination temperature and nickel content on the catalytic activity The results show that NiO-CeO2-TiO2 has high activity and stability for partial oxidation of methane.When the volume of feed gas is 20% CH4, 10% O2 and 70% N2, GHSV = 55 200 ml / (gh ), The reaction temperature is in the range of 650 ~ 850 ℃. The NiO-Ce0.50Ti0.50O2 catalyst calcined at 700 ℃ has the highest CH4 conversion and H2 selectivity. After being continuously tested at 750 ℃ for 50 h, the activity and Selectivity is still maintained at a high level.XRD and TPR characterization of the catalyst results show that the NiO is in a highly dispersed state; in the NiO-TiO2 catalyst, NiO and TiO2 solid-state reaction and the presence of NiTiO3 form, and NiTiO3 than with the carrier mutual NiO and CeO2 can be reduced by adding CeO2 into Ce-Ti-O solid solution, which inhibits the solid-state reaction of NiO and TiO2, and promotes the low and middle temperature reactivity of NiTiO3 catalyst. At the same time, NiTiO3 catalyzes the partial oxidation of methane active.