Preparation Of FS-TiO₂ Modified Catalyst And Its Photocatalytic Degradation Of Acrylonitrile

As an important chemical raw material,acrylonitrile has a large market demand,and the global output of acrylonitrile has increased year by year.In the production process of acrylonitrile,a large amount of toxic and harmful acrylonitrile wastewater will be produced.If it is not properly degraded,it will have extremely serious harm to human body and natural environment.Therefore,it is necessary to find an effective method for degrading acrylonitrile.Traditional removal methods are subject to high cost,inadequate removal,and harsh operating conditions.Photocatalytic degradation is a possible removal route.The photocatalytic method has the advantages of complete degradation,low cost,and reaction at normal pressure and normal temperature.In this paper,acrylonitrile was used as the target pollutant in aqueous solution,and the reason of poor stability was analyzed based on the existing FSBi-TiO₂ catalyst.The FS-TiO₂catalyst was optimized by Zr and Al modification,and the degradation of acrylonitrile under simulated sunlight was studied.The details are as follows:Aiming at the problem of poor stability of FSBi-TiO₂ catalyst,it is proposed that it is caused by the loss of F species on the catalyst surface during photocatalytic reaction.In order to verify this idea,the FSBi-TiO₂ catalyst was characterized by XPS,and the valence changes of the F,S and Bi elements in the catalyst before and after photocatalytic reaction were analyzed.The results show that the reason for the catalyst deactivation is not only due to the loss of surface F species of the catalyst,but also the loss of F doped into the TiO₂ lattice.This finding corrects the original idea.The stability of doping TiO₂ with different combinations of F,S and Bi elements was studied.The relatively stable FS-TiO₂ was selected for modification research.In order to improve the activity of the catalyst,FS-TiO₂ was modified by Zr,and the activity of FSZr-TiO₂ for photocatalytic degradation of acrylonitrile was evaluated.The optimum preparation conditions of the FSZr-TiO₂ catalyst are a molar ratio of Ti:Zr=1:0.07,a calcination temperature of 450°C,and a calcination time of 2 h.The results of photocatalytic reaction showed that the degradation rate of acrylonitrile by FSZr-TiO₂ reached 79.2%after 6 min of simulated sunlight.It was increased by 5.1%relative to FS-TiO₂.The characterization results show that Zr modification can effectively inhibit the recombination of TiO₂ photogenerated carriers,and the existence form of Zr before and after the reaction does not change.In order to improve the stability of the catalyst,the FSZr-TiO₂ was optimized for Al,and the stability of FSZrAl-TiO₂ photocatalytic degradation of acrylonitrile was studied.The results show that the stability of the prepared catalyst is best when the molar ratio of Ti to Al is 1:0.005,the calcination temperature is 450°C,and the calcination time is 2 h.In the fifth repeated reaction,the degradation rate of acrylonitrile was 54.7%after photocatalytic degradation for 6 min,and its stability was 9.4%higher than that of FSZr-TiO₂ catalyst,and 18.3%higher than that of FS-TiO₂ catalyst.