Preparation And Characterization Of Selenium-doped Carbon Materials And Their Application In Green Oxidation Reactions

In this thesis,the application of selenium-doped carbon materials in thermal catalysis and photocatalytic green oxidation reactions was studied.The main content includes the following three parts:1.The reaction of the alcohol oxidation catalyzed by g-C₃N₄-Se was studied.The reaction process conditions were optimized,such as:doped metal,solvent,selenium doping amount,catalyst dosage.The best yield was obtained with Pd-doped g-C₃N₄-Se fabricated with selenium powder/melamine ratio at 5 wt%as catalyst and dioxane as solvent.Under optimized conditions,twelve alcohol compounds were catalytically oxidized.The catalysts were characterized by SEM,HRTEM,ICP,etc.The possible reaction mechanism was proposed through verification experiments.Compared with the existing methods,the present method has mild reaction conditions,simple operation,and only requires clean hydrogen peroxide as the oxidant,is green and environmentally friendly,and provides a green and efficient synthesis route for producing alcohol compounds.2.The oxidation of olefins catalyzed by Se/C materials was studied.The method utilizes a catalytic amount of Se/C material as a catalyst,an environmentally friendly ethanol as a solvent,and hydrogen peroxide as the oxidant.We performed several screenings on the reaction conditions,such as:selenium doping amount,reaction temperature,solvent,reaction time,etc.Ten carbonyl compounds were obtained,and all the compound structures were characterized by IR,'H NMR and other methods.The catalysts were characterized by XRD and HRTEM.Through a series of comparative experiments,the possible reaction mechanism was proposed.Compared with the existing methods,the method is,green and no waste is produced,providing a new method for the oxidation of alkenes to produce carbonyls.3.The photocatalytic oxidation of alcohol-aldehydes with g-C₃N₄ materials was studied.g-C₃N₄ has excellent thermal stability and chemical stability,and can respond to visible light.It was widely used in the field of photocatalysis.However,due to the narrow absorption range of traditional bulk g-C₃N₄ materials in the visible wavelength range,the separation effect of photo generated carriers is not ideal.For this reason,we have introduced selenium simple substance to make pores for bulk g-C₃N₄ to increase its specific surface area.It assisted the exfoliation of g-C₃N₄ and allowed it to change from bulk to porous nanorods,increasing its photocatalytic efficiency.At the same time,in order to further enhance its photocatalytic efficiency,we in-situ grown CeO2 on the surface of selenium-doped g-C₃N₄ nanorods to construct novel heterojunction photocatalysts and they were employed to catalyze the oxidative degradation of acetaldehyde and isopropanol..