二氧化钛薄膜上三氯乙烯光催化氧化反应机理

 研究了二氧化钛薄膜上三氯乙烯(TCE)气相光催化氧化的反应机理. 结果表明,TCE气相光催化氧化反应生成的氯气可引发TCE的连锁反应. 当添加氯气的浓度相同时TCE表面光催化反应的初速率约为光化学反应初速率的2倍,说明连锁反应主要发生在催化剂表面. 氯可吸附在催化剂表面,作为电子的接受体抑制空穴与电子复合,提高TiO2光催化剂的活性. 除了TCE与吸附在催化剂表面的·OH的相互作用及反应产物/中间产物二氯乙酰氯的光催化分解可生成氯气以外,光气在与氯气共存时的光分解也有利于氯的生成.

Reaction Mechanism of Photocatalytic Oxidation of Trichloroethylene on TiO2 Film

The reaction mechanism of photocatalytic oxidation of trichloroethylene (TCE) in gas-phase on TiO 2 film was investigated by FT-IR and GC-MS techniques. Chlorine, the product of photocatalytic oxidation of TCE on TiO 2 film, could initiate the chain reaction of TCE. The homogeneous photochemical oxidation and photocatalytic oxidation occurred simultaneously resulting in the increase of oxidation rate of TCE. When the same amount of chlorine was added, the photocatalytic oxidation rate of TCE was 2 times larger than that of homogeneous photochemical oxidation. The photocatalytic oxidation of TCE occurred mainly on the surface of TiO 2 film. It was presumed that chlorine became one of the surface species through being adsorbed on the surface of TiO 2 film and enduced chain reaction of TCE. Chlorine adsorbed on the surface of TiO 2 film in the form of anion could inhibit the recombination of electrons and holes, and enhance the catalytic activity of TiO 2 film. Photodissociation of phosgene in the gas phase could also release chlorine.