Catalysis of Organic..

Yamauchi 15519. 2006 Murray Raney Award Lecture:Synthesis and Features of New Raney®Catalysts from Metastable PrecursorsAbstractIsamu YamauchiOsaka University, Yamadaoka 2-1 Suita, Osaka, 565-0871 Japanyamauchi@mat.eng.osaka-u.ac.jpPrinciples of skeletal structure formation of Raney® catalysts are discussed, firstfrom the perspective of phase transformation by chemical leaching. Some ideas arethen proposed for making new Raney catalysts. Rapid solidification and mechanicalalloying (MA) are described as potential processes for preparing particulateprecursors. A rotating-water-atomization (RWA) process developed by the authorand co-workers is shown as an example of rapid solidification.Specific examples of RWA are further described. Raney copper precursor with asmall amount of Pd was prepared by this process. Rapid solidification was effectivein keeping most of the added Pd dissolved in the precursor. The specific surface areaof the leached specimen increased by about 3 times in comparison with that ofordinary Raney copper catalyst. The conversion from acrylonitrile to acrylamide bythe hydration reaction was about 60%, or more than 20% higher than that fromordinary Raney copper catalyst. In case of Ti or V addition, the conversionincreased to 70-80%. Rapid solidification was quite effective in decreasing thedefect rate of Raney catalysts from some precursors. The potential for design of newcatalysts may be widely extended by rapid solidification.Some examples of ternary alloy precursors are also shown. Their generalproperties were examined and their microstructures were directly observed bytransmission electron microscopy. Thus, catalysts synthesized from multi-systemalloys had high solubility of additional elements into a major element, and might beexpected to work as new catalysts.The relation between the size of fine particles in skeletal structure and X-raybroadening was also discussed. These results may bring important information todesigning new Raney catalysts.Large particles (diskettes) were formed by applying a spark plasma sinteringprocess to leached catalyst particles. Almost all of the catalyst specific surface areawas retained after sintering. This may open a way to manufacture pellet typecatalysts or electrodes with high specific surface area.