A Protector-Free One-Pot Strategy To Synthesize Highly Dispersed Pd Hydrogenation Catalysts In A Broad Loading Range On Polystyrene

Pursuing a strategy to feasibly acquire nanoparticles in clean state(protector-free)and desired size range(ca.3.0-5.0 nm)is a fundamental demand for the application of state-of-art precious metal catalysts.Herein,vinylbenzyl trimethylammonium chloride(VTC)was tried to co-polymerize onto the surface of polystyrene(PS)as the capturing group for anchoring PdCl42-through their electrostatic interaction to prepare PS supported Pd nanoparticles in one-pot system for selective hydrogenation of phenylacetylene to styrene.With characteristic combinations of Inductively coupled plasma-optical emission spectrometer(ICP-OES),Zeta potential analysis(ZPA),X-ray diffraction(XRD),Transmission electron microscopy(TEM)and Fourier transform infrared spectra(FT-IR)techniques,it was demonstrated that introducing VTC on PS in a proper amount(VTC:styrene molar ratio at 0.05)was a key factor to optimize the electrostatic state of polystyrene substrate,which facilitated the uniform anchoring of PdCl42-and following in-situ reduction to Pd particles under protector-free conditions,leading to the particles be in desired ca 3.0-5.0 nm size range even if a broad Pd loading range in 20 times change was adjusted(from 0.2wt.% to 4.6 wt.%).The catalytic measurements and corresponding kinetic analysis for selective hydrogenation of phenylacetylene to styrene showed the regular change of catalytic performance among samples was directly governed by the Pd particle size,in addition,the good stability of the present Pd catalyst was verified by leach experiment and recycle use tests on typical sample.These results indicated that the present strategy was promising in acquiring clean and size-controllable metal nanoparticles,which could be inferred as a feasible system to get desired metal nano-catalysts for advanced heterogeneous catalysis applications.