等离子体协同催化降解VOCs过程中O_3的作用机理

Role of O_3 during the plasma-catalytic oxidation of VOCs

等离子体协同催化降解挥发性有机化合物(volatile organic compounds,VOCs)过程中,O_3的产生是不可避免的。为研究此过程中的O_3对VOCs降解的影响,本文将不同类型的催化剂(SBA-15、Fe Ox/SBA-15、Fe Ox-Ag Ox/SBA-15)分别置于等离子体区域中和区域后,测定了甲苯降解过程中O_3产生量的变化以及催化剂对甲苯降解的影响。研究结果表明,不同类型的催化剂在等离子体区域中均能使O_3和ΔO_3值显著增加,而在等离子体区域后,O_3产生量比催化剂置于等离子体区域中有一定程度的降低,但与空管相比差别不大,而甲苯降解效率显著提高,CO2选择性显著降低。在单独等离子体条件下,随着甲苯浓度的升高,O_3呈现逐步升高的趋势。加入催化剂后,在甲苯浓度为410mg/m3和615mg/m3时,O_3产生量较单独等离子体显著升高,但随着甲苯浓度的增加,不同催化剂对O_3的产生量影响不大。

The emergence of O3 was inevitable during the VOCs oxidation by plasma assisted catalysis. In order to study the mechanism of VOCs oxidation with the formation of O3 byproduct during plasma,different catalysts（SBA-15,Fe Ox/SBA-15,Fe Ox-Ag Ox/SBA-15） were placed inside and outside the plasma zone,and then the O3 concentration was measured and the effect of the catalysts on the toluene degradation was studied. The results showed that the O3 and ΔO3 were significantly increased when the catalysts were put inside the plasma zone,while the O3 concentration decreased when the catalysts were put outside the plasma zone,close to the case of bare plasma. The toluene removal efficiency improved,and the CO2 selectivity decreased. At the same time,O3 concentration gradually decreased with the increase of toluene concentration when only plasma were used. However,when the catalysts were put inside the plasma zone,the O3 concentration increased under the toluene concentration of 410 mg/m3 and 615 mg/m3,but the catalysts has little effect on the O3 concentration when the toluene concentration further increased.