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

Abstract

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 α,β-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.

Noble metal/silica “raspberry” type hybrids: Synthesis and functionalization

“…The interaction between support and catalyst can also lead to more reactive materials and allows for much easier recovering and recycling, especially important for rare catalysts, which finally results in the saving of energy. Lim et al [13] have reported that Pd dispersed on SiO 2 is a more efficient catalyst in the hydrogenation of olefins than Pd dispersed on polymer and the former could be recycled more than 10 times without considerable loss in activity. Okumura et al [14] have observed that SiO 2 is a good support for catalytically active metal particles.…”

“…[13,[19][20][21]. For instance Sai et al [19] have coated noble metals like Au and Ag on amine functionalized SiO 2 nanosprings (helical nanowires), which showed high surface-enhanced Raman spectroscopy activity, useful in sensor applications.…”

Nanocatalysts for Hydrogenation Reactions

“…11 The 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.…”

Azide–alkyne cycloaddition reactions in water via recyclable heterogeneous Cu catalysts: reverse phase silica gel and thermoresponsive hydrogels

“…These properties make it possible to use water as a solvent for organic reactions. These solid supports were applied to the syntheses of Pd, Au immobilized heterogeneous catalysts and organic reactions such as hydrogenations, 53 Suzuki–Miyaura couplings, 54,55 Heck–Mizoroki couplings, 56 Sonogashira couplings, 56 Tsuji–Trost reactions, 57 and A-3 coupling reactions 58 that were performed in water. Herein, we wish to demonstrate that our supports can be extended to other metal catalyzed organic reaction applications.…”