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

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/TiO2 catalysts. The Pd/C catalysts after the 353 K-H2-pretreatment exhibited satisfactory and comparable performances obtained with commercially available best ever Pd/C by optimizing catalyst preparation. In contrast to Pd/TiO2, 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.

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► Cinchonidine-modified catalysts were prepared with eggshell and homogeneous Pd/C.
► Optimized loading of Pd on the carbon was only 5%.
► The best prepared Pd/C showed identical performance with the commercial best Pd/C.
► The H2-pretreatment prior to the CD-modification was also effective for the freshly prepared catalyst.
► The properties of Pd/C in enantioselective hydrogenation were different from those of Pd/TiO2.