【摘要】 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-Al₂O₃-La₂O₃等催化剂中镍晶粒度和La₂O₃的分散状态进行了测量和讨论。用透射电镜测量了不同La₂O₃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La₂O₃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La₂O₃在γ-Al₂O₃表面作密置单层分散的模型提出了新的旁证,并推断由于La₂O₃在γ-Al₂O₃表面高分散并产生较强相互作用,使γ-Al₂O₃接近表层晶格发生畸变。更多还原

【Abstract】 Ni/γ-Al₂O₃, Ni/γ-Al₂O₃-La₂O₃ （La₂O₃ 6.7%）and Ni/γ-Al₂O₃-La₂O₃ （La₂O₃ 11.7%） catalysts were prepared by incipient wetness technique. The particle size distribution （Fig. 9） and the average size of nickel in these catalysts were determined by Transmission Electron Microscopy （TEM）. Average particle size could be compared with the data determined by X-Ray Diffraction （XRD）（see Table3）. It has been found that the particle size of nickel in catalysts is decreasing （Table 1） and activity of methanation is increasing （Fig. 2） as adding La₂O₃ to Nicatalyst. Results of TEM and XRD in this paper support the model suggested by Xie Youchang et. al., of close-packed monolayer La₂O₃ dispersed on γ-Al₂O₃ surface, if the amount of La₂O₃ is less than the threshold value （0.28g La₂O₃/100m² γ-Al₂O₃）. X-Ray line broaden of γ-Al₂O₃ in La₂O₃/γ-Al₂O₃ sample （Fig. 4） indicates that some lattice deformation occurs in γ-Al₂O₃ lattice, due to La₂O₃ highly dispersed on the surface of alumina.更多还原