Photothermal Synergistic Effect And Its Mechanism In Selective Oxidation Of Aromatic Alcohols

Aromatic aldehyde and its derivatives are important fine chemical intermediates,which are widely used in the synthesis of spices,confectionery,alcoholic beverages,etc.Oxidation of aromatic alcohols to corresponding aromatic aldehydes has always been the research topic of fine chemical industry.Oxidation of aromatic alcohols to corresponding aldehydes in industry usually requires stoichiometric strong oxidants such as Cr reagent,permanganate,potassium ferrate（K₂Fe O₄）and Cl O^-.Using such oxidants is not only expensive,but also produces metal wastes,organic wastewater and corrosive gases with the same equivalent amount of metals,causing environmental pollution.Therefore,developing new oxidation technology to realize the conversion of aromatic alcohol to corresponding aldehyde is of great significance in both environmental and economic aspects.According to literature investigation,a great deal of research work has been done on the selective oxidation of aromatic alcohols to corresponding aromatic aldehydes based on semiconductor materials as photocatalysts.Under suitable conditions,the conversion rate of aromatic alcohols and the selectivity of aromatic aldehydes have achieved good results.However,considering the industrial production,the photocatalytic reaction rate is far from the industrial level.Therefore,coupling photocatalytic technology with other technologies to industrial production will become an inevitable choice for photocatalytic research in the future.In this paper,we successfully coupled photocatalyst and thermal catalyst to prepare various photo-thermal catalysts for selective oxidation of aromatic alcohols.In O₂atmosphere,Mn₃O₄/Cd_0.9Zn_0.1S and Ce O₂/g-C₃N₄prepared by us show excellent photo-thermal catalytic activity.the photo-thermal catalytic yield of 10%Mn₃O₄/Cd_0.9Zn_0.1S is 6.7times that of monomer Cd_0.9Zn_0.1S,and the photo-thermal catalytic yield of 50%Ce O₂/g-C₃N₄is that of monomer g-C₃N₄.XRD,XPS,SEM,TEM,DRS,PL,BET and electrochemical analyzer were used to characterize the physical and chemical properties of the prepared catalyst.EPR technology was used to analyze the free radicals existing in the reaction,and other related characterizations were combined to give the possible reaction mechanism.In addition,we successfully prepared NCO/Cd S（NCO is Ni/Ce O₂composite catalyst）photo-thermal catalyst for catalytic oxidation of aromatic alcohol in atmospheric air.We found that 60%NCO/Cd S photo-thermal catalysis of aromatic alcohol,the yield of aromatic aldehyde is as much as 6 times as that of monomer Cd S.It is an important step to realize the industrialization of photo-thermal catalytic oxidation of aromatic alcohol in atmospheric air,which provides a new idea for future research.Through a series of characterization,we put forward the possible reaction mechanism.