CeO2-MnOx催化剂上氯乙烯有机废气的催化燃烧

采用柠檬酸(CA)溶胶-凝胶法制备了不同Mn:(Ce+Mn)摩尔比的CeO2-MnOx催化剂,以氯乙烯有机废气的催化燃烧为模型反应,考察了催化剂制备条件和反应条件对于CeO2-MnOx催化剂性能的影响,并用N2吸附、X射线衍射(XRD)和H2程序升温还原(H2-TPR)对催化剂进行了表征.结果表明,CeO2-MnOx催化剂上氯乙烯燃烧反应产物只有HCl,H2O和CO2,没有检测到其他氯代烃和氯气等副产物.当CA:Mn:Ce=0.3:0.50:0.50时,所制备的CeO2-MnOx催化剂活性最高,对于较宽的空速范围(10000～30000h-1)和较宽的浓度范围(0.05%～0.15%),低浓度氯乙烯的催化燃烧反应具有较好的操作弹性.其中当氯乙烯浓度为0.1%,空速为15000h-1时,起燃温度T50=110oC,完全转化温度T99=220oC.XRD和H2-TPR结果表明,在CeO2-MnOx催化剂中只出现立方相萤石结构CeO2的特征衍射峰,没有出现MnOx物种的特征衍射峰;Mn离子进入CeO2晶格形成的Ce-Mn-O固溶体,有利于提高催化剂表面的活性氧物种的活性,乃至催化剂活性.

Catalytic Combustion of Vinyl Chloride Emission over CeO2-MnOx Catalyst

CeO2-MnOx catalyst samples with different Mn/(Ce+Mn) molar ratios (0, 1/4, 1/2, 3/4, and 1) prepared by the citric acid (CA) sol-gel method were studied for catalytic combustion of vinyl chloride (VC) emission. The effects of preparation conditions and operation parameters on the catalytic performance of CeO2-MnOx were investigated. The catalyst samples were characterized by N2 adsorption, X-ray diffraction (XRD), and H2 temperature-programmed reduction (H2-TPR). In the catalytic combustion of VC over CeO2-MnOx, the products containing HCl, CO2, and H2O were produced and there were no byproducts such as chlorohydrocarbons and chlorine. The CeO2-MnOx catalyst with the molar ratio of CA:Mn:Ce = 0.30:0.50:0.50 showed the best catalytic performance and had better operating flexibility over the ranges of gas hourly space velocity (GHSV) of 10000–30000 h-1 and VC concentration of 0.05%–0.15%. The temperatures at 50% con-version (110 oC) and at 99% conversion (220 oC) were achieved at VC concentration of 0.1% and GHSV of 15000 h-1. XRD characterization indicated that only the characteristic diffraction peaks of CeO2 with the cubic fluorite structure appeared and no characteristic diffraction peaks of MnOx species appeared over CeO2-MnOx catalyst. XRD and H2-TPR results indicated that Mn ions were incorporated into the CeO2 lattice to form Ce-Mn-O solid solution, which was favorable for improving the reactivity of active oxygen species on the catalyst surface and thereby enhanced the catalyst activity.