Preparation Of Materials Based On Visible Light Catalysis Of Small Organic Molecules And Their Reaction Performance

In the 21st century,photocatalytic organic synthesis,as a green organic synthesis,has attracted great attention.Photocatalysis technology has become a promising and economical method to solve this problem.Light-driven organic synthesis has gained a huge advantage from the development of cheap,effective,robust,simple and long-term stable photocatalysts.Considering the poor light capturing capability of most organic molecules in the visible region,it is usually necessary to activate them using external photocatalysts with photo and redox properties.Therefore,the focus of this study is to find and construct suitable catalysts to improve the activity of organic synthesis reactions.WO₃ and Cu Bi₂O₄ photocatalysts were successfully prepared by hydrothermal method.The photocatalytic efficiency was improved by adjusting the morphology of WO₃,met al doping of Cu Bi₂O₄ and the structure of heterojunction between WO₃ and Cu Bi₂O₄.The experiment is divided into three parts.In the first part,different preparation methods（acid type,p H,calcination temperature）were used to prepare WO₃ for the reaction of benzyl alcohol and aniline to imine.The experimental results show that 2D WO₃（hydrochloric acid method,p H=1,400°C）can make the conversion rate of benzyl alcohol and aniline to imine up to 75.9%with good stability.In the second part,Cu Bi₂O₄ catalyst was prepared by hydrothermal method as the carrier,and x wt%Pd（1%,2%,3%,4%,5%）with different weight ratios was loaded by Na BH₄ reduction method.The experimental results show that 3 wt%Pd@Cu Bi₂O₄ can selectively oxidize benzyl alcohol to benzaldehyde and increase the conversion rate to 73.2%with good stability,which is about 5 times higher than the reaction activity of Cu Bi₂O₄.In the third part,p-n type heterojunction of x-Cu Bi₂O₄/WO₃ photocatalyst was prepared with different mass ratios（x is the mass ratio of Cu Bi₂O₄）by ultrasonic and mechanical stirring.In the selective oxidation reaction of benzyl alcohol,the conversion rate is 54.8%when 40%-Cu Bi₂O₄/WO₃ is used as catalyst,and it has good stability.The activity of 40%-Cu Bi₂O₄/WO₃ is higher than that of pure WO₃,Cu Bi₂O₄ and other mass ratios of x-Cu Bi₂O₄/WO₃.In this paper,the prepared catalysts（WO₃,Pd@Cu Bi₂O₄,Cu Bi₂O₄/WO₃）were tested by a series of characterization methods,including XRD,XPS,SEM,TEM,UV-VIS DRS,PL,BET and EIS spectra.At the same time,a series of optimization tests were carried out for the organic reaction,including the type of solvent,the type of base,the amount of base,the amount and proportion of reactants,and the amount of catalyst to determine the optimal reaction conditions.Finally,the light intensity,wavelength range,active species,five cycles and activation energy of the catalyst were tested.