Mn、Fe和Cu氧化物在低温等离子体催化氧化甲苯体系中的活性比较

Removal of toluene by Mn,Fe and Cu oxides catalyst combined with nonthermal plasma

采用等体积浸渍法制备了MnOx/γ-Al2O3、FeOx/γ-Al2O3和CuOx/γ-Al2O3催化剂,测定了不同催化剂在低温等离子体场内分解甲苯的活性,用X射线衍射(XRD)、氢气程序升温还原(H2-TPR)技术对催化剂进行表征。结果表明催化剂分解甲苯的活性的顺序是MnOx/γ-Al2O3>FeOx/γ-Al2O3>CuOx/γ-Al2O3。催化剂分解臭氧的实验表明,不同催化活性组分对臭氧的催化分解性能顺序与对甲苯的分解性能顺序是一致的。MnOx/γ-Al2O3催化剂的Mn负载量对其催化活性有明显影响,Mn的含量为1%(质量分数)时,催化剂的活性最高,当能量密度为19J/L时,其对甲苯催化氧化的转化率接近100%。催化剂表征结果表明当Mn含量为1%(质量分数)时,氧化锰在载体γ-Al2O3上最接近单层分散量,此时活性组分与载体表面的相互结合力最强,在载体上有很好的分散性,从而表现出对甲苯分解的最好性能。

The activity of MnOx/γ-Al2O3、FeOx/γ-Al2O3 andCuOx/γ-Al2O3 catalysts for toluene oxidation was investigated in a dielectric barrier discharge reactor. The catalysts were prepared by impregnation method,and then characterized with X-ray diffraction （XRD） and temperature programmed reduction by H2 （H2-TPR）. Resuits showed that the catalytic activity of these metal oxide catalysts for toluene decomposition followed the or- der. MnOx/γ-Al2O3〉FeOx/γ-Al2O3〉CuOx/γ-Al2O3 and meanwhile the activity of these catalysts for ozone decom- position to produce active oxygen also followed the order. MnOx/γ-Al2O3〉FeOx/γ-Al2O3〉CuOx/γ-Al2O3. The Mn loading has a significant effect on the activity of the catalysts for catalytic oxidation of toluene. The activity of the catalyst with 1wt% Mn loading was the highest. A 100% conversion of toluene at an energy density of 20J/ L was achieved by using the catalyst with Mn loading of lwt%. Results of XRD quantitative analysis and H2- TPR showed that lwt% Mn loading was close to the monolayer dispersion threshold of MnOx on 7-Al2O3 ,and thus there was strong interaction between MnOx and the support, suggesting a highly dispersion system. As a result,the catalyst with Mn loading of 1wt% exhibited the optimum performance of toluene oxidation in the plasma zone.