Catalysis of Organic..

160 Raney® Metastable Precursorsslowly solidified specimen. In this case, the direct effect of Pd dissolved in the Cuskeleton on the conversion ratio is hard to explain clearly, because high specificsurface area contributes to the high conversion ratio. We have developed a directTEM observation method for the microstructure of leached specimens by slicing thespecimen using an ultra-microtome. Figure 8 shows an example of TEM images forCu of Pd free and 1.5mass % Pd. They have a skeletal structure composed of finegranular Cu particles. The size of Cu particles was about 30-40nm for a Pd freematerial and 10nm for a 1.5 mass %Pd added material. It suggests that the dissolvedPd in the precursor suppressed the growth of Cu particles as obstacles for therearrangement of Cu. The size obtained by direct observation by TEM was almostthe same as that evaluated by the X-ray line- broadening method.(a) Pd free (b) Pd 1.5 mass %Figure 8. TEM image of as-leached state (Raney Cu).Mechanical alloying (MA) is another process solution in addition to rapidsolidification for making a supersaturated solid. In this process, the pure powdersof different elements are mixed and encapsulated in a metallic container with somesteel balls. Then, the container is rotated or vibrated for an extended time. Thepowders are cold worked by collisions of steel balls. This cold working makesmechanically alloyed powder.This process was applied to prepare Al 3 Ni precursor with 2at% Ti. The catalyticbehavior was examined for the hydrogenation of acetone in an autoclave. The rate ofchange of hydrogen pressure with time was evaluated, i.e. the rate of decrease from0.3MPa (initial pressure). This value is an indicator of the activity of the catalyst. It