低浓度甲苯的气相光催化降解研究

研究了较低浓度的甲苯在较短停留时间时(17s～83s)的光催化降解,考察了甲苯初始浓度、停留时间、湿度、光源和催化剂载体等因素的影响,并分析了光催化处理降解能力随甲苯负荷的变化.研究表明,在较短停留时间时,甲苯降解率随进口浓度的增大而下降,且停留时间越短,随进口浓度增大而下降的越快;在某一停留时间范围内,甲苯的降解近似遵循一级反应动力学,动力学常数随浓度的增大而增大;低浓度时甲苯的光催化降解受湿度影响较小;低压汞灯为光源时甲苯的光催化降解率显著高于黑光灯为光源时的降解率;涂覆在不锈钢网状上的光催化剂性能随载体目数的增加而提高,但不及涂覆在铝板上的光催化剂.

Photocatalytic Degradation of Low Level Toluene in the Gas Phase

Photocatalytic degradation of low level toluene in the gas phase at low retention time (17s-83s) was studied. The effects of the inlet concentration, retention time, relative humidity, ultraviolet wavelength and carrier of the catalyst were investigated, as well as the change of the photocatalytic degradation capability with the load. It was showed that the degradation rate of toluene at low retention time decreased with increase of inlet concentration, and it decreased more significantly at shorter retention time. Within a range of retention time, the degradation of toluene followed with first order kinetics approximately, and the reaction rate constant increased with inlet concentration. The relative humidity affected the degradation rate a little when the inlet concentration was low. The photocatalytic degradation rate when irradiated with low-pressure mercury lamp (254 nm) was significantly higher than that irradiated with black light lamp having same power. The photocatalyst coated on the stainless steel mesh showed higher activity while it was on the mesh with higher number, however it was not as good as the photocatalyst coated on the aluminum plate.