苯在TiO2上的气相光催化氧化反应历程

 以超细TiO2为催化剂，在内循环光反应装置中考察了苯的气相光催化氧化反应．苯的初始质量浓度为50mg／m3时，在0．1g催化剂和0．013m2的光照面积下，460min后苯几乎全部分解完毕；光照面积增大1倍时，反应时间缩短为240min．常温下苯在TiO2表面不易吸附，但反应中间产物有较强的吸附性，能吸附在催化剂表面从而引起催化剂失活．经红外检测可知，反应的中间产物是个六元环醇，据此推测了苯的气相光催化可能的反应历程．通过实验结果并参考有关文献的结论，证明苯的气相光催化氧化在不同的反应条件下遵循不同的反应历程．

Reaction Mechanism of Gas-Phase Photocatalytic Oxidation of Benzene on TiO2

Gas phase photocatalysis is an effective way for decomposing toxic organics, but the studies on benzene decomposition are relatively little. Our objective was to assess the capability of TiO 2 to decompose benzene and establish reaction mechanism for the photocatalytic oxidation of benzene. The photocatalytic oxidation of benzene in gas phase was performed in a recirculation photoreactor including a UV lamp emitting around 254 nm and TiO 2 coated glass plate. When the initial mass concentration of benzene was 50 mg/m 3, it was almost decomposed completely after 460 min on 0 1 g of TiO 2 and 0 013 m 2 area of catalyst layer activated by ultraviolet. The reaction time was reduced from 460 to 240 min when the irradiated area was 0 026 m 2. At ambient temperature, the adsorption of benzene on TiO 2 surface was not obvious, but the intermediate reaction product had very good adsorptivity, occupied the active sites and deactivated the catalyst. The IR results showed that the intermediate product was a hexatomic ring alcohol. A probable photocatalytic oxidation mechanism of benzene in gas phase was inferred through the intermediate based on the experiment and the results in the literature. The gas phase photocatalytic oxidation of benzene had different reaction mechanisms under different reaction conditions.