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本文用X射线衍射法(XRD),透射电镜(TEM),配合电子衍射对Ni/Al2O3,Ni/γ-Al_2O_3-La_2O_3等催化剂中镍晶粒度和La_2O_3的分散状态进行了测量和讨论。用透射电镜测量了不同La_2O_3含量的催化剂中镍晶粒度分布,其平均直径可与X射线宽化法测定值相比较。催化剂中随La_2O_3加入量的增加,Ni晶粒有细化趋势,从而提高了甲烷化催化活性。对La_2O_3在γ-Al_2O_3表面作密置单层分散的模型提出了新的旁证,并推断由于La_2O_3在γ-Al_2O_3表面高分散并产生较强相互作用,使γ-Al_2O_3接近表层晶格发生畸变。
In this paper, XRD, TEM and EDS were used to measure and discuss the distribution of Ni grain size and La 2 O 3 in Ni / Al 2 O 3 and Ni / γ-Al 2 O 3-La 2 O 3 catalysts. Transmission electron microscopy was used to measure the particle size distribution of nickel in the catalysts with different La_2O_3 contents. The mean diameter of nickel particles can be compared with that of the X-ray broadening method. With the addition of La 2 O 3 in the catalyst, the Ni grains have a tendency of refinement, which improves the catalytic activity of methanation. This paper presents a new circumstantial proof for the La_2O_3 dispersion model on γ-Al_2O_3 surface and deduces that due to the high dispersion of La_2O_3 on the γ-Al_2O_3 surface and the strong interaction between γ_Al_2O_3 and γ-Al_2O_3, the distortion of γ-Al_2O_3 near the crystal lattice is observed.