Seeding Growth of Pd/Au Bimetallic Nanoparticles on Highly Cross-Linked Polymer Microspheres with Ionic Liquid and Solvent-Free Hydrogenation

We developed a method to immobilize Pd/Au bimetallic nanoparticles (NPs) on highly cross-linked polymer microspheres. In this route, the cross-linker divinylbenzene and ionic liquid (IL) 1-vinyl-3-butyl imidazolium chloride ([VBIM]Cl) were first copolymerized in ethanol to prepare the cross-linked polymer microspheres with the IL. The PdCl4 2− ions were immobilized on the polymer support, and the Pd NPs immobilized on the support were formed after the PdCl4 2− ions were reduced. The supported bimetallic Pd/Au NPs were obtained after seeding growth process. The polymer support and metallic NPs/support composites were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, inductively coupled plasma analysis, X-ray photoelectron spectroscopy, and elemental analysis. It was demonstrated that the immobilized metallic NPs were nearly monodispersed and the Pd and Au in the composites showed excellent synergy to catalyze the hydrogenation of cyclohexene.