Preparation Of Spinel Copper Ferrite Supported On Porous Carbon For Catalytic Oxidation Of Vanillyl Alcohol

Since the 1950s,spinel-type catalysts have attracted extensive attention from scientists around the world.Due to their small particles,large surface area,high selectivity and excellent stability,spinel-type catalysts occupy an important position in nanomaterials and are widely used in various fields,including biotechnology,magnetic resonance imaging,data storage,and anode materials.Among various spinel materials,copper ferrite has become the most widely used magnetic nanomaterial with the advantage of low cost,low toxicity and multiple valence states.However,its small particles and easy aggregation will significantly reduce the exposed active sites,thus lowering the catalytic activity and limiting its further application.Therefore,the preparation of highly dispersed spinel ferrite catalyst is particularly necessary for its development and utilization,and is the key to its wide application in the field of catalysis.In this thesis,lignite and corncob-based porous carbon were used as carriers,and supported spinel copper ferrite catalysts were prepared by hydrothermal,sol-gel,and equal volume impregnation methods,and using vanillyl alcohol oxidation reaction as a probe,the effects of different preparation methods,Ni/Co doping and different Co doping ratios on the structure and performance of the catalyst were explored respectively.The crystal structure,pore structure,surface element composition and microstructure of the catalyst are analyzed by X-ray diffraction,physical adsorption,X-ray photoelectron spectroscopy,scanning electron microscopy and transmission electron microscopy.The catalytic performance of the catalyst was evaluated by vanillyl alcohol oxidation reaction,and the oxidation mechanism of vanillyl alcohol to vanillin over copper ferrite catalyst was studied.（1）Inner Mongolia lignite and Xuzhou corncob are used as raw materials to prepare porous carbon carriers.When the ratio of alkali to carbon is 3:1,the porous carbon has the largest specific surface area.The supported copper ferrite catalysts were prepared by hydrothermal method,sol-gel method and equal volume impregnation method,and the prepared catalysts all showed a spinel structure.Among these catalysts,the corncob-based porous carbon（BPC）supported Cu Fe₂O₄ catalyst prepared by the equal volume impregnation method has the highest selectivity to vanillin,the optimal preparation condition of the supported copper ferrite catalyst is as follows:equal volume impregnation method,calcination at 600 ^oC and 33%load capacity.（2）The supported copper ferrite catalyst doped with Ni/Co was successfully prepared and characterized.The results show that the specific surface area and the degree of dispersion increases,the crystal size decreases after doping,but the crystal structure remains unchanged and still presents a spinel structure.Doping Ni/Co improves the catalytic activity of copper ferrite in the oxidation of vanillyl alcohol.Among them,Cu_0.5Co_0.5Fe₂O₄/BPC has good catalytic activity in the oxidation of vanillin.The conversion yield of vanillyl alcohol is 91%,and the selectivity of vanillin reaches 78%.The optimal conditions for vanillyl alcohol oxidation reaction are:1 mmol vanillyl alcohol,40 m L acetonitrile,2 mmol H₂O₂,75 mg catalyst,40 min of reaction time,80 ^oC of reaction temperature.（3）Cu_xCo_1-xFe₂O₄/BPC catalysts with different Co doping amounts were prepared.With the increase of Co doping ratio,the characteristic diffraction peaks of spinel copper ferrite gradually shifted to higher angles and widened,and the lattice spacing d gradually decreased.Among them,Cu_0.4Co_0.6Fe₂O₄/BPC has the largest specific surface area,the smallest crystal size,and an average particle size of 4.45 nm.When x=0.4,the conversion yield of vanillyl alcohol is 96%and the selectivity of vanillin reaches 81%,and the catalytic performance is the best.The catalyst still has good stability after repetitive use for 5 times.The thesis has 46 figures,6 tables and 122 references.