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以硝酸亚铈(Ce(NO3)3·6H2O)和正硅酸四乙酯(C8H20O4Si)为前驱体,采用溶胶-凝胶法合成了系列具有大比表面积的xCeO2-(1.x)SiO2(x=0,0.25,0.50,0.75,1)复合氧化物载体,然后浸渍活性组分Ni制得用于甲烷部分氧化制合成气的Ni催化剂.运用N2物理吸附-脱附、X射线粉末衍射、扫描电镜、紫外-可见漫反射光谱、氢程序升温还原、氨程序升温脱附和热重等手段对所得催化剂的组织结构、还原性、表面酸性和积炭行为等进行了表征;同时考察了催化剂的组成、焙烧温度和反应时间等对催化剂在甲烷部分氧化制合成气中催化性能的影响.表征结果表明,该系列Ni/CeO2-SiO2催化剂具有大比表面积,CeO2晶粒较小,NiO的分散性好且易被还原,表面酸性弱,不容易积炭.当Ce/Si摩尔比为1:1,活性组分Ni的质量分数为10%,焙烧温度为700°C时,所制备的Ni/CeO2-SiO2催化剂表现出较好的稳定性、最高的CH4转化率(~84%)和对产物CO及H2的选择性(>87%).
A series of xCeO2- (1.x) SiO2 (x) nanocrystals with large specific surface area were synthesized by sol-gel method using cerium nitrate (Ce (NO3) 3 · 6H2O) and tetraethyl orthosilicate (C8H20O4Si) as precursors = 0,0.25,0.50,0.75,1) composite oxide support, and then impregnated with Ni as active component to prepare Ni catalyst for partial oxidation of methane to syngas.Using N2 physisorption-desorption, X-ray powder diffraction, scanning The microstructure, reducibility, surface acidity and carbon deposition behavior of the obtained catalyst were characterized by SEM, UV-visible diffuse reflectance spectroscopy, temperature-programmed reduction of hydrogen, ammonia temperature-programmed desorption and thermogravimetry. , Calcination temperature and reaction time on the catalytic performance of the catalyst in the partial oxidation of methane to syngas.The characterization results show that the series of Ni / CeO2-SiO2 catalysts have large specific surface area, small CeO2 grains and good dispersion of NiO And easy to be reduced, the surface acidity is weak, not easy carbon deposition.When Ce / Si molar ratio of 1: 1, the mass fraction of Ni is 10%, the calcination temperature is 700 ° C, the prepared Ni / CeO2 -SiO2 catalyst showed better stability, the highest CH4 conversion (~ 84%) The product selectivity of CO and H2 (> 87%).