【摘要】 为了考察金属分散度对活性的影响,本试验用浸渍法制备了两个系列的催化剂,A系列样品是加入担体表面改性剂La₂O₃使担体表面改性,然后金属镍分散在改性的表面上,增强金属与担体之间的相互作用,提高金属的分散度,当La₂O₃加量不同时,便可制得一系列晶粒度不同的样品;B系列样品是在相同的担体表面上负载不同量的金属镍,制得一系列晶粒度不同的样品。 用x光衍射法测定担体表面上金属镍和NiO的平均晶粒度。样品的活性评价在常压装置上进行,考察甲烷水蒸汽转化制氢的活性。实验证明,金属活性组份在担体表面上的分散度对催化反应的活性有显著的影响,对于本试验采用的Ni/α-Al₂O₃催化剂,CH₄水蒸汽转化制氢反应的活性最高点所对应的最适宜的金属分散度为:NiO和Ni的平均晶粒度约为210A,适宜的NiO和Ni平均晶粒度范围约200～230A。更多还原

【Abstract】 The dispersion of metallic active component on the support surface is an important problem in the study of catalysts. Metal is dispersed in the form of crystallites. The size of crystallites has a great influence upon activity of catalytic reaction. The optimum dispersion is the one with the highest catalytic activity. It depends on the type of catalyst and catalytic reaction.Two series of samples prepared by impregnation were examined to determine the effect of metal dispersion on activity. The"A" series of samples was Ni/a-Al2O3. The modifying agent of support surface, Lanthanum Oxide(La2O3), was first added during preparation. Then, nickel was dispersed on the modified surface. Therefore, metallic Ni dispersion was increased by strong metal-support interaction. The "A" series of samples with different size of crystallites were prepared by adding various amounts of LaaO3, and the "B" series of samples with different size of crystallites were prepared with various contents of Ni on the same support surface.The average size of these crystallites of NiO and Ni on the support surface was measured by means of X-Ray diffraction. The activity of samples for steam reforming of methane were evaluated by using a fluidized bed apparatus under atmospheric pressure. It was found that the dispersion of metal had a great influence upon activity of catalytic reaction. The optimum dispersion at which the activity of samples Ni/a-Al2O3, for steam reforming of methane reached a maximum was average size about 210A, and size range 200-230A.更多还原