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

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.