Studies on Preparation and Catalytic Propeties of Amorphous Thin Film Alloys

用射频溅射方法制备了金属薄膜(Ni、Pd、Pt、Ru)及其硼化物和磷化物。通过改变溅射条件，可以方便地制备出不同成分的非晶态合金薄膜。在金属硼化物膜中，硼向金属提供电子，导致金属的高电子密度。在金属磷化物膜中，磷接受金属中的电子，导致金属的电子密度较低。在二烯烃(1，3-丁二烯和环戊二烯)和乙炔在这些合金薄膜上的加氢反应中，用系综效应和配体效应解释了部分加氢的选择性。金属团簇尺寸小，电子密度低，使部分加氢具有较高的选择性。特别是非晶态Pd_lt；75&gt；P_&lt；25&gt；薄膜表现出较高的选择性(&gt；95%)，而在真空中加热晶化的Pd_&lt；75&gt；P_&lt；25&gt；薄膜表现出较高的选择性(&gt；99%)。另一方面，在Ru和Pd薄膜上研究了二烯烃和乙炔加氢反应中的结构依赖性。晶面的取向随着薄膜的生长而发生变化，即Ru薄膜的晶面取向由(002)取向转变为(101)取向，而Pd薄膜的晶面取向由(111)取向转变为(220)取向。结果表明，(002)取向的Ru膜和(220)取向的Pd膜具有较高的加氢选择性。这些金属薄膜具有柱状结构，因此薄膜的比表面积随着薄膜的生长而增大。采用射频溅射法制备了具有活性和选择性的薄膜催化剂。

Metal thin films (Ni,Pd,Pt,Ru) and their borides and phosphides were prepared by using the RF sputtering method. Amorphous alloy thin films with various compositions were easily prepared by changing the sputtering conditions. In the metal boride films, boron donated electrons to metal, resulting in the high electron density of metal. With the metal phosphide films, phosphorous accepted electrons from metal, resulting in the low electron density of metal. In the hydrogenation of diolefins (1,3-butadiene and cyclopentadiene) and acetylene over these alloy thin films, the selectivity for the partial hydrogenation was explained in terms of the ensemble and the ligand effects. The small ensemble size and the low electron density of metal brought about the high selectivity for the partial hydrogenation. Especially, amorphous Pd_<75>P_<25> film showed the high selectivity (>95%) and further Pd_<75>P_<25> film heated in a vacuum, which was crystallized, exhibited the higher selectivity (>99%). On the other hand, the structure dependence in the hydrogenation of diolefins and acetylene was investigated on the Ru and Pd films. The orientation of the crystal faces changed with the film growth, that is, the orientation altered from (002) orientation to (101) orientation in the Ru films while changed from (111) orientation to (220) orientation in the Pd film. It was found that the (002) oriented Ru film and the (220) oriented Pd film showed the high selectivity for the hydrogenation. These metal films had the columnar structure and therefore the surface area of the films increased with the film growh. The active and selective film catalysts were developed by using the RF sputtering method.