Preparation Of F-TiO₂/WO₃ Catalyst And Its Photocatalytic Degradation Of Gas Phase Toluene

The environmental pollution caused by PM2.5 and ozone is the focus of current society.VOCs are important precursors of PM2.5 and ozone,so effective measures should be taken to treat VOCs to reduce environmental hazards.In this paper,toluene,the iconic substance of VOCs,was selected as the subject of this study.Pure TiO₂ has high catalytic activity and is non-toxic,and the reaction conditions are mild,but the utilization rate of visible light is low,and the photo-generated electron-hole pairing ratio is high,so it is limited in industrial applications.Therefore,the key to improving the activity of the TiO₂-based catalyst is to expand the photoresponse range and reduce the recombination rate of photogenerated electron-holes.Therefore,this method uses TiO₂ and WO₃composite method to modify TiO₂.During the research,it is found that the catalyst has a certain deactivation phenomenon,so the reason for its deactivation is analyzed.The specific contents are as follows:The F-TiO₂/WO₃ composite catalyst was prepared and the preparation conditions were optimized.Nano-level WO₃ was prepared by calcination method,and TiO₂ and WO₃ were composited by sol-gel method.The photocatalytic activity of TiO₂/WO₃ composite catalyst was improved.Finally,the TiO₂/WO₃catalyst was doped with F.The preparation conditions were optimized.The photocatalytic activity of TiO₂/WO₃ catalyst was the highest when the molar ratio of W/Ti was 0.10 and the calcination temperature was 450°C.The degradation rate reached 52.0%at 120 min.Fluorine doping,when the F/Ti doping molar ratio is 0.10,the degradation rate of F-TiO₂/WO₃ catalyst at 120 min is 71.0%,and the activity is increased by 19.0%compared with that before doping.It was proved by XRD,UV-Vis,SEM,XPS that the doping of F can enhance the activity of the catalyst.The influence of reaction conditions on the catalytic activity of F-TiO₂/WO₃catalyst was investigated,and the formation path of by-products was analyzed.The F-TiO₂/WO₃ catalyst with higher degradation activity for toluene was screened out.The effects of initial concentration,gas flow rate,relative humidity,catalyst dosage,oxygen content and light source on the photocatalytic activity of the catalyst were investigated.GC-MS analysis of the inactivated Cuihua agent identified major by-products such as benzoic acid,benzaldehyde and phenol.To investigate the cause of catalyst deactivation,the catalysts before and after deactivation were characterized by XRD,UV-Vis,SEM,BET,XPS and PL.It was found that the crystal shape did not change significantly before the inactivation,and the crystal grain size changed obviously.The absorption strength of the deactivated catalyst in the visible light region was significantly lower than that of the fresh catalyst.The TiO₂ and WO₃ particles showed obvious agglomeration,and the pore size and pore volume were also fresher.The F loss of TiO_2-x-x F_x in the F-TiO₂/WO₃ lattice resulted in the conversion of Ti³⁺to Ti⁴⁺,and the decrease of the oxygen vacancies of the catalyst resulted in a decrease in its activity.