Pd nanoparticles dispersed on solid supports: synthesis, characterization and catalytic activity on selective hydrogenation of olefins in aqueous media

Two types of Pd nanoparticle catalysts were prepared having 2-4 nm particle size using silica gel and porous polymer beads as solid supports. 2-Pyridinecarboxaldehyde ligand was anchored on commercially available 3-aminopropyl-functionalized silica gel followed by Pd metal dispersion. Bead-shaped cross-linked poly(4-vinylpyridine-co-styrene) gel was prepared by an emulsifier-free emulsion polymerization of 4-vinylpyridine, styrene and divinylbenzene in the presence of ammonium persulfate and subsequently dispersing the Pd metal on the synthesized polymer. These catalysts were characterized by SEM, TEM and ICP techiniques with respect to appearance, size and possible leaching out, respectively. Furthermore, the reactivity of these catalysts was tested on hydrogenation of various alpha,beta-unsaturated carbonyl compounds using aqueous solvent under a hydrogen balloon (1 atm). The results showed that the Pd dispersed on silica was a more efficient catalyst than Pd dispersed on polymer and the former could be recycled more than 10 times without considerable loss in activity. Copyright (C) 2010 John Wiley & Sons, Ltd.This work was supported by Ansan Environmental Technology Development Center (grant 09-2-80-81) and the National Research Foundation of Korea (grant 2009-000-0000-1611). Y.-W. Chang acknowledges financial support from the SRC/ERC program of MEST (grant R11-2005-056-04004-0). Likewise, M. L. and K. A. D. C. appreciate the financial support from the Korean Ministry of Education through the second stage of the BK21 project for the Hanyang University Graduate Program, and M. L. also acknowledges the Seoul Metropolitan Government for Seoul Science Fellowship