Dealumination behavior of ZSM-5 type zeolite containing alkaline earth metal

摘要

ZSM-5 type zeolites containing alkaline earth metals (M-HZSM-5) were prepared under various synthesis conditions and their hydrothermal stability was investigated.It was found that the average crystal size of M-HZSM-5 can be easily controlled by addition of H_3BO_3 with no reduction of the amount of alkaline earth metal occluded.It was also found that the hydrothermal stability of M-HZSM-5 evaluated by steaming at 600 deg C depends upon not the crystal size but the amount of the alkaline earth metal occluded.Ca-,Sr- and Ba-HZSM-5 showed the higher hydrothermal stability,and Ca- and Sr-HZSM-5 exhibited the high selectivity to light olefins in methanol conversion even after steaming at 600 deg C for 7 days.