Preparation of Pd/C designed for chiral modified catalyst: Comparison with Pd/TiO2 in enantioselective hydrogenation of α-phenylcinnamic acid

Abstract Enantioselective hydrogenation of α-phenylcinnamic acid was investigated on Pd/C catalysts prepared in our laboratory to compare activity and selectivity with those on commercial Pd/C and Pd/TiO 2 catalysts. The Pd/C catalysts after the 353 K-H 2 -pretreatment exhibited satisfactory and comparable performances obtained with commercially available best ever Pd/C by optimizing catalyst preparation. In contrast to Pd/TiO 2 , a high loading of Pd is not necessary with Pd/C, but only 5% loading on a certain activated carbon was found to result in high e.e. It is suggested that the optimum size or size-distribution of Pd metal particle are different between the two supports, suggesting a support effect of this catalyst system.