负载型CeO_2/OMS-2催化剂对VOCs的催化氧化性能

Catalytic oxidation performance of supported CeO_2/OMS-2 catalysts for VOCs

采用回流法合成了OMS-2,同时以OMS-2为载体,采用浸渍法负载CeO_2制备了Ce/OMS-2催化剂,运用X射线衍射、拉曼光谱、BET、H_2-TPR和NH_3-TPD等方法对催化剂进行表征,并考察CeO_2/OMS-2催化剂催化氧化二氯甲烷和乙酸乙酯的性能。结果表明,CeO_2的加入并未改变OMS-2较好的八面体分子筛结构,CeO_2的晶粒很小且以高分散的形式存在;负载CeO_2的OMS-2催化剂比表面积都有增大趋势;随着CeO_2负载量的增加,低温和高温的还原峰都先向低温方向偏移再向高温方向偏移;随着CeO_2负载量的增加,高温处强酸性峰先向低温方向偏移再向高温方向偏移。反应活性结果表明,CeO_2/OMS-2催化剂活性比载体OMS-2的活性好,随着铈负载量的增加,催化活性先升高再降低,其中,CeO_2负载质量分数为1.0%(1.0Ce/OMS-2)时催化剂效果最好,这可能是由于铈的加入活化了OMS-2中的氧,影响了整体催化剂的酸性,进而影响反应性能。

OMS-2 was synthesized using a reflux method, and CeO2/OMS-2 catalysts were prepared by the impregnation method. The as-prepared catalysts were characterized by XRD, Raman, BET, H2-TPR and NI-I3-TPD techniques. The performance of CeOJOMS-2 catalysts for catalytic oxidation of dichlo- romethane and ethyl acetate were investigated. XRD results indicated that the octahedral molecular sieve structure of OMS-2 was not changed with the addition of CeO2 and CeO2 particles were highly dispersed on the surface of OMS-2. BET results showed that the surface area of the catalyst increased with the addi- tion of CeO2. H2-TPR results indicated that with the increase of CeO2 loadings,low temperature and high temperature reduction peaks first shifted to low temperature and then to high temperature. NH3-TPD results indicated that with the increase of Ce02 loadings, high temperature desorption peak assigned to strong acid first shifted to low temperature and then to high temperature. The results of reaction activity showed that the activity of Ce/OMS-2 catalysts were better than that of OMS-2 support. The highest reac-tivity was obtained over 1. OCe/OMS-2 catalyst（ Ce02 loading mass fraction 1.0% ）, probably due to the enhanced oxygen mobility and the weakened acidity of the catalyst by the addition of Ce02.