流动态甲醇气相光催化降解的机制研究

Study on Mechanism of Methanol Photocatalytic Decomposition in Flow Gas-phase

在253.7nm紫外光作用下,研究纳米TiO2光催化氧化流动态甲醇的机制,结果表明,甲醇的光催化降解不受水汽的影响,只受氧气含量的影响.在不含氧气的情况下,即使有足量的水汽,甲醇都不会有明显的降解.TiO2受光诱导生成空穴-电子对后,空穴直接氧化甲醇,生成的甲醇正离子在氧气作用下进一步被氧化,形成各种氧化产物.甲醇氧化过程是多通道反应,宏观表现为准一级反应.空气和氧气条件下甲醇的总降解速率常数分别为9.78×10-3和1.79×10-2s-1.

Nano TiO2 photocatalytic decomposition of flow gas-phase methanol was investigated under 253.7 nm UV light. The result indicated that oxygen content exerted a significant influence on methanol photocatalytic decomposition. In the absence of oxygen, there was no distinct decomposition even with abundant water vapor. It was concluded that after hole-electron pairs were induced by ultraviolet light, the hole then oxidized methanol directly, forming methanol free radical cation, which would be further oxidized in the presence of oxygen. Methanol oxidation process was a multi-path reaction, and in macro view a pseudo-first-order reaction with decomposition rate constant of 9.78 × 10^-3 s^-1 in the presence of air and 1.79 × 10^-2 s^-1 in the presence of oxygen.