甲醛光催化氧化的反应机理

摘要

采用程序升温脱附（ TPD） , 电子自旋共振（ ESR）及自旋捕获-电子自旋共振 (ST- ESR)等物理方法对甲醛光催化氧化过程中 ,反应物的吸附状态、自由基中间物种及反应机理进行了研究 .结果表明 ,在光催化氧化空气中微量甲醛的反应条件下 ,吸附在催化剂表面的空气中的氧气被光生电子还原为· O－ 2,微量水被空穴氧化为· OH.二者为甲醛的深度氧化提供了高活性的氧化剂 .甲醛是通过中间产物甲酸而氧化为终点产物二氧化碳的 .%The adsorption state of reactants,free radical intermediates and the reaction mechanism have been studied by means of temperature programmed description (TPD),electron spin resonance (ESR) and spin traping- ESR in the photocatalytic oxidation of formaldehyde.The results showed that O2 adsorbed on the surface of photocatalyst could be reduced to · O－ 2 by photogenerated electrons and H2O could be oxidized to · OH by holes.Both free radicals are active oxidants in the reaction of photocatalytic oxidation of HCHO.The photocatalytic oxidation of HCHO carried out with two steps.Firstly,HCHO was oxidized into HCOOH,then HCOOH converted into final product of CO2 and H2O.