Effects of Steam-Assisted Crystallization Synthesis Conditions on the Mesopore Properties of Hierarchical ZSM-5

摘要

Zeolites are crystalline microporous aluminosilicates that are widely used because of their repeating microporous structure. However, diffusion of molecules throughout the micropores is hindered by mass transfer limitation. Hierarchical zeolites have been synthesized as a means to eliminate these mass transfer limitations while maintaining shape selectivity due to the micropores.1-3 Widely reported post synthesis methods have been used for introducing mesopores within the zeolite crystals by desilication4 and dealumination by steaming.2 However, the major drawback to these methods is the inability to control mesopore formation and a limitation in SiO2/Al2O3 ratios. Subsequently, constructive techniques have employed structure-directing agents (dual templating) in direct or two-step synthesis pathways.5