New insight into the inductive effect of various seeds on the template-free synthesis of ZSM-5 zeolite

It is of great significance to clarify the roles that various seeds play in the induced synthesis of target zeolites from a viewpoint of topological structure. Zeolites, including ZSM-5, beta, mordenite, ZSM-35, ZSM-22, SSZ-13, SSZ-24 and analcite, were used as seeds for the template-free synthesis of ZSM-5. It was found that zeolites with lower framework density and identical composite building units (CBUs) and secondary building units (SBUs) could be used as seeds for the successful synthesis of ZSM-5. Zeolites (ZSM-5, beta, mordenite, ZSM-35 and ZSM-22) having identical CBUs and SBUs to ZSM-5 were capable of accelerating the crystallization of ZSM-5, whereas zeolites (SSZ-13 and SSZ-24) lacking identical CBUs and SBUs could act as seeds to synthesize ZSM-5 zeolite only if they possessed lower framework density than ZSM-5. As such, zeolites possessing simultaneously identical CBUs and/or SBUs and low framework density had a strong inductive effect in template-free synthesis of ZSM-5.