石英反应器中硝基物的光催化还原

研究了在石英反应器(QGR)中,用纳米TiO2 将对氯硝基苯(PCNB)光催化还原为对氯苯胺(PCA)的反应,并与在Pyrex玻璃反应器(PGR)中的反应进行了对比,讨论了反应器壁材质、反应时间、溶剂及催化剂种类的影响。QGR优良的透光性使反应速率提高,但光解副反应也增加。在QGR中,P25型TiO2 使PCA产率达到82 29%仅需 1h,而在PGR中需要 7 .5h。在反应的前 4h,A101型TiO2 使QGR中PCA产率高于PGR;但 4h以后,PCA产率下降。光催化还原反应具有典型的连串反应特征,还原过程中,PCA存在一最高产率,PCNB起始质量浓度为 0. 63、1 .26、2 .56mg/L时,P25催化的PCA的最高产率分别为 82 .29%、76 .06%和 77 .56%。反应体系中水量增多,会明显抑制光催化还原反应。P25催化剂的催化性能优于A101,在QGR中,光催化还原 1h,P25使PCA产率高达 82 .29%,而用A101时PCA产率仅为 26. 09%。

Photocatalytic Reduction of Nitro Compound in Quartz Glass Reactor

The photocatalytic reduction of p-chloronitrobenzene (PCNB) to p-chloroaniline (PCA) in titanium dioxide slurries under UV light irradiation in quartz glass reactor (QGR) was investigated.The experimental results in QGR were compared with those in Pyrex glass reactor (PGR).The effects of reduction time,properties of TiO_2,and the wall material of the reactor were evaluated.Due to higher light transparency,the reaction in QGR has much higher speed and less selectivity for PCA than that carried out in PGR.When the reaction was catalyzed with P25 TiO_2,the reduction time needed for 82.29% yield of PCA was only 1 h in QGR,while in PGR it was 7.5 h.When A101 TiO_2 was used,the yield of PCA in QGR was higher than that in PGR in the first 4 h of the reaction;after that the yield of PCA began to decrease.Photocatalytic reduction was characterized in sequential reaction mechanism,accompanied with a maximum yield of PCA during UV irradiation.When the initial concentration of PCNB were 0.63,1.26 and 2.56 mg/L,the maximum yields of PCA in the presence of P25 were respectively 82.29%,76.06% and 77.56%.The photocatalytic reduction would be markedly restrained by more water in the reaction system.P25 has better catalytic activity than A101.In QGR yield of PCA could reach 82.29% in 1 h with P25,while with A101 it was only 26.09%.