甲醇制丙烯过程中ZSM-5催化剂的失活行为

DEACTIVATION OF ZSM-5 CATALYSTS DURING METHANOL-TO-PROPYLENE PROCESS

采用IR、TG、低温N2-吸附等手段对用于甲醇制丙烯(MTP)反应的高硅小晶粒ZSM-5催化剂的结焦和失活过程进行研究。结果表明,ZSM-5催化剂具有良好的水热稳定性;分子筛孔道中的可溶性结焦物主要以三甲基苯为主,含量存在一个积累过程,并在48 h达到最大值,随后保持相对稳定;分子筛表面积炭堵塞孔道是导致催化剂失活的主要原因,即积炭量随反应时间延长而持续增加,当其外表面容纳不了更多的积炭时,形成的积炭物质将堵塞沸石孔口,从而使得催化剂在770 h后突然失活。

The coke formation and deactivation process of high silica ZSM-5 catalyst with small particle size used in the reaction of methanol to produce propylene were studied by IR, TG and N2-adsorption techniques. The results showed that the ZSM-5 catalyst was of good hydrothermal stability. The soluble coke in ZSM-5 channels was mainly consisted of three substituted benzenes, which accumulated sharply in the reaction initial period and reached its maximum at reaction time of 48 h and then remained nearly unchanged for the most reaction period. It was the carbon deposition that caused the deactivation of the ZSM-5 catalyst. As the ZSM-5 exterior surface could not accommodate any more carbon coke, the newly formed coke would block the pore of ZSM-5 and subsequently resulted in a sharp deactivation of the catalyst after a long run time of 770 h.