Study On The Catalytic Performance Of Bimetallic Modified Phosphotungstate For Styrene Oxidation

In this paper,cobalt-nickel modified phosphotungstate（CoNiPW）and iron-molybdenum modified phosphotungstate（FeMoPW）materials were prepared by simple mixture-calcination method using H₃PW₁₂O₄₀·6.5H₂O（PW）,Co（NO₃）₂·6H₂O,Fe（NO₃）₃·9H₂O,（NH₄）₆Mo₇O₂₄·4H₂O,and Ni Cl·6H₂O as raw materials.The prepared materials were characterized by physicochemical techniques such as X-ray powder diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）,ultraviolet-visible spectroscopy（UV-Vis）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray photoelectron spectroscopy（XPS）to determine their composition and structurer.The catalytic performance of the CoNiPW materials for solvent-free oxidation of styrene to benzaldehyde using molecular oxygen as an oxidant was evaluated and they exhibited efficient catalytic functions with 63.0%conversion of styrene and 98.0%selectivity to benzaldehyde.A detail study on influence of key reaction parameters,as well as catalytic role of various constituents in CoNiPW on the reactivity and selectivity was conducted to identify active sites.The reaction mechanism via benzyl alcohol intermediate was proposed by in situ adsorption of styrene on the catalyst surface and the product intermediate produced in the oxidation reaction.The recovery and reusability of the catalyst was also evaluated.Besides,the Fe-Mo modified phosphotungstate composites FeMoPW were used as catalysts for solvent-free oxidation of styrene to benzaldehyde using H₂O₂ as an oxidant,and higher catalytic activity（60.0%conversion of styrene）and high selectivity to benzaldehyde（90.0%）were achieved.A detail study on influence of key reaction parameters,as well as catalytic role of various constituents composed of FeMoPW on the reactivity and selectivity was conducted to identify active sites.The in situ infrared spectroscopy for adsorption of styrene and H₂O₂on the catalyst surface was carried out.The reaction mechanism of the catalytic reaction via forming styrene oxide and benzyl alcohol intermediates was proposed.The recovery and reusability of the catalyst was also evaluated.