摘要
研究了浸渍液的浓度和酸度,浸渍时间,竞争吸附剂对金属离子在Al_2O_3上分布的影响。制得了Pd呈不同分布的Pd-Al_2O_3催化剂,和金属呈不同分布的Pd-Pt-Al_2O_3,Pd-Co-Al_2O_3,Pd-Ni-Al_2O_3双金属催化剂。用光学照相和EDX表征了催化剂上金属的分布。用TEM法测定Pd-Al_2O_3催化剂金属粒度的结果表明,Pd在Al_2O_3上分布的形式不同,其粒度也不同,其粒度次序为:蛋黄型>蛋白型>蛋壳型>均匀型。而该催化剂的苯加氢活性次序为:蛋白型>蛋黄型>蛋壳型>均匀型。双金属催化剂的苯加氢活性也与金属分布有关。
The effects of concentration and acidity of impregnation solution, impregnation time, and competitive adsorbate on the distribution of metal ion on A12O3 were studied. The Pd-Al2O3, Pd-Pt-Al2O3, Pd-Co-A12O3 and Pd-Ni-Al2O3 catalysts with different distributions of metals, such as egg shell, egg white, egg yolk and uniform, were prepared under proper impregnation conditions respectively. The distribution of metal on the monometallic and bimetallic Pd-catalyst sections was characterized by photography and EDX methods. The Pd particle size and the catalytic activity for benzene hydrogenation of Pd-Al2O3 catalyst are related to the distribution of Pd in alumina bead. The order of Pd particle size is as follows, egg yolk>egg white>egg shell>uniform catalyst. The order of the catalytic activity for benzene hydrogenation is egg white>egg yolk>egg shell>uniform. It is interesting to notice that the catalytic activity of bimetallic catalysts for benzene hydrogenation is also affected by the distribution of the two metals in support pellet.
关键词
钯催化剂
双金属催化剂
苯
加氢
Palladium catalyst,bimetallic catalyst,metal distribution,metal particle size,benzene,hydrogenation
