Preparation,characterization And Catalytic Hydrogenation Performance Of Three-dimensional Graphene-supported Palladium Catalyst

Three-dimensional graphene is a porous carbon nanomaterial with a three-dimensional structure,which has excellent characteristics such as high specific surface area,high porosity,high strength and high conductivity.Therefore,it has a wide range of applications in the fields of energy storage,catalysts,environmental protection,stretchable conductors,and biosensing.In the field of catalysis,three-dimensional graphene has shown many excellent properties as a supported catalyst carrier.In this paper,three-dimensional graphene was first prepared by hydrothermal reduction method,and then three-dimensional graphene-supported palladium catalyst was prepared by using three-dimensional graphene as a carrier.On this basis,the catalytic hydrogenation performance of the catalyst for the hydrogenation of carbon tetrachloride and the hydrogenation of dicyclopentadiene（DCPD）was studied respectively,and the catalyst composition,preparation conditions and process conditions of the catalytic hydrogenation were optimized.The specific research contents are as follows:（1）First,three-dimensional graphene was prepared by the classical modified Hummers method and hydrothermal reduction method using expanded graphite as the starting material.On this basis,three-dimensional graphene-supported palladium metal catalysts were prepared by impregnation method and nitrogen-hydrogen mixed gas reduction method.Then,the graphene and its supported palladium catalyst were characterized by scanning（transmission）electron microscopy,low-temperature nitrogen adsorption,Raman spectroscopy,XRD,FT-IR and other analytical testing methods.The results show that the reduced transition metal palladium appears as uniformly dispersed nanoparticles on the surface of the threedimensional graphene support without obvious agglomeration.（2）Using n-hexane as solvent,the catalytic performance of three-dimensional graphene supported palladium metal catalyst for the liquid-phase hydrodechlorination of carbon tetrachloride was investigated by batch reaction.The optimal reaction conditions for the hydrogenation of carbon tetrachloride were explored under different reaction temperatures and catalyst loadings.The results show that when the pressure is 3 MPa,the Pd loading is 1.0 wt%,the catalyst reduction temperature is 773 K,and the hydrodechlorination reaction temperature is 398 K,the conversion rate of carbon tetrachloride is 98.12%,and the selectivity of chloroform is as high as 85.23 %,which is a relatively excellent operating condition.（3）Using ethanol as solvent,the catalytic performance of three-dimensional graphenesupported palladium metal catalyst for the liquid-phase hydrogenation of dicyclopentadiene was investigated by batch reaction.The optimal reaction conditions for the hydrogenation of dicyclopentadiene were explored at different reaction temperatures,catalyst loadings and hydrogen pressures.The study found that the optimal process conditions for the preparation of Endo-THDCPD by catalytic hydrogenation of DCPD are as follows: the reaction temperature is 373 K,the catalyst Pd loading is 1.0 wt%,the reaction hydrogen pressure is 1.0MPa,and the conversion rate of DCPD is 95%.The selectivity of Endo-THDCPD was as high as 81.3%.