Synergistic performance between oxidizability and acidity/texture properties for 1,2-dichloroethane oxidation over (Ce,Cr)xO2/zeolite catalysts
Synergistic performance between oxidizability and acidity/texture properties for 1,2-dichloroethane oxidation over (Ce,Cr)xO2/zeolite catalysts
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DOI：
10.1016/j.ces.2015.05.024
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发表时间：
2015-09
影响因子：
4.7
通讯作者：
Peng Yang;Zhinan Shi;Fei Tao;Shanshan Yang;R. Zhou
中科院分区：
文献类型：
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作者：
Peng Yang;Zhinan Shi;Fei Tao;Shanshan Yang;R. Zhou
(Ce采用沉积-沉淀法制备了Ce/Cr摩尔比为4：1，（Ce，Cr）xO 2与分子筛质量相当的（Ce，Cr）xO 2/分子筛催化剂，并对1，2-二氯乙烷深度催化氧化反应进行了考察。基于T90%的值（90%转化率温度）时，催化剂活性依次为（Ce，Cr）xO 2/HZSM-5（230 °C）>（Ce，Cr）xO 2/H-BETA（243 °C）>（Ce，Cr）xO 2/USY（247 °C）>（Ce，Cr）xO 2/H-MOR（253 °C），比（Ce，Cr）xO 2和母体分子筛有明显提高，表明（Ce，Cr）xO 2与沸石之间存在协同效应。这种协同作用是由于分子筛的强酸性中心首先促进了1，2-二氯乙烷的吸附和脱氯化氢反应，而（Ce，Cr）xO 2的强氧化性中心则有利于反应物、中间体和副产物的深度氧化，并有利于催化剂表面焦炭和Cl的减少。其中，（Ce，Cr）xO 2/HZSM-5的催化活性和耐久性最好，这也与其特殊的交叉孔结构有关。此外，虽然苯或水的存在降低了催化剂在反应初期的活性，但（Ce，Cr）xO 2/HZSM-5在反应后期表现出良好的稳定性。
(Ce,Cr)xO2/zeolite catalysts with Ce/Cr molar ratio of 4:1 and equivalent mass of (Ce,Cr)xO2and zeolite are prepared by a deposition–precipitation method, and tested for deep catalytic oxidation of 1,2-dichloroethane. Based on the values ofT90%(temperature at which 90% conversion is obtained), the catalytic activity decreases in the order of (Ce,Cr)xO2/HZSM-5 (230 °C)>(Ce,Cr)xO2/H-BETA (243 °C)>(Ce,Cr)xO2/USY (247 °C)>(Ce,Cr)xO2/H-MOR (253 °C), which is improved obviously than (Ce,Cr)xO2and parent zeolites, indicting the existence of synergistic effect between (Ce,Cr)xO2and zeolites. This synergy is resulted from that the strong acid sites of the zeolites firstly promotes 1,2-dichloroethane adsorption and dehydrochlorination, while the strong oxidative sites of (Ce,Cr)xO2is in favor of the deep oxidation of the reactants, the intermediates and byproducts as well as the reduction of coke and Cl accumulation on the catalyst surface. Especially, (Ce,Cr)xO2/HZSM-5 represents the best catalytic activity and durability, which is also related to its special intersectional pore structure. Moreover, though the presence of benzene or water decreases the catalytic activity in the initial stage because of the competitive adsorption on active sites, (Ce,Cr)xO2/HZSM-5 represents good durability during the prolonged reaction time.