稀土修饰ZSM-5对氯代甲烷制备低碳烯烃的催化性能

以稀土硝酸盐为前躯体，采用等体积浸渍法制备了一系列稀土修饰ZSM 5催化剂(RE/ZSM 5)；利用XRD、N2吸附 脱附、SEM、NH3 TPD等手段表征了所制备RE/ZSM 5的物理化学性质，并考察了其对氯甲烷制低碳烯烃(MeXTO)反应的催化性能。结果表明，稀土修饰可以调节ZSM 5的酸性，降低催化剂的酸量和酸强度，从而提高催化剂催化MeXTO的稳定性和产物中低碳烯烃选择性。在一系列RE/ZSM 5中，Ce/ZSM 5在MeXTO反应中表现出较高的催化活性，得到较高低碳烯烃选择性，同时具有相对较长的使用寿命。在450℃、质量空速045 h-1条件下，2Ce/ZSM 5催化MeXTO的氯甲烷转化率高达976%，总的低碳烯烃选择性达776%；反应52 h后，低碳烯烃收率仍维持在43%。

Catalytic Performance of Rare Earth Modified ZSM-5 in Chloromethane Conversion to Lower Olefins

A series of rare earth modified ZSM-5 catalysts (RE/ZSM 5) were prepared by impregnation method with rare earth nitrates as precursors. The physiochemical properties of the prepared RE/ZSM-5 catalysts were characterized by XRD, N2adsorption desorption, SEM and NH3 TPD, and their catalytic performances for chloromethane to lower olefins (MeXTO) were systematically investigated. The results showed that rare earth modification could reduce the acid amount and acid strength of ZSM-5, which was in favor of increasing selectivity to lower olefins and catalyst lifetime. Among RE/ZSM 5, Ce/ZSM 5 exhibited the longest catalytic life in MeXTO and highest olefins selectivity could be obtained. Under the conditions of 450℃ and 045 h-1, chloromethane conversion and selectivity to lower olefins were 97.6% and 77.6%, respectively. Notably, the yield of lower olefins was still as high as 43% after 52 h reaction.