乙醛光催化降解的动力学研究

Kinetics of Acetaldehyde Photocatalytic Degradation

利用气相色谱分析技术,在自制的间歇式循环反应系统中对乙醛的气-固相光催化降解动力学行为进行了实验研究.结果表明:当乙醛初始浓度较高时,如果催化剂表面辐射强度较低,则反应过程处于光子传递控制过程,反应速率与光强成正比,若催化剂表面辐射强度较高,则反应过程符合Langmuir-Hinshelwood动力学方程;当乙醛初始浓度较低时,随着紫外光辐射强度从低到高变化,光催化反应均为一级反应过程,反应速率常数随着光强的增加而增大,但当光强大于11.6 W/m2时,光催化反应过程处于表面作用控制过程,光强的提高对反应速率不再有促进作用.

With a batch type photocatalytic reactor, the kinetics of the photocatalytic degradation of acetaldehyde is investigated using gas chromatography. It is found that the reaction is in photon transfer controlled step with high initial concentration of acetaldehyde and low light intensity of ultraviolet on the surface of catalyst, and the reaction rate is proportional to light intensity. If the light intensity is high, the degradation of acetaldehyde can be described by Langmuir-Hinshelwood equation. When the initial concentration of acetaldehyde in the reactor is low, the degradation is a typical first-order reaction regardless of light intensity. With the increase of the light intensity, the reaction rate constantly rises. As the light intensity exceeds 11.6 W/m^2 , the reaction becomes surface controlled, and further increase of light intensity has no effect on the reaction rate.