Mesoporogen-free synthesis of hierarchically porous ZSM-5 below 100 °C.

The molecular diffusion with zeolites is somewhat limited, particularly for bulky molecules because zeolites only have micropores, which, in turn, limit their use as catalysts. Generation of hierarchically porous ZSM-5 with micro and mesopores has been a rational solution for overcoming this problem. The conventional method for synthesizing hierarchically porous ZSM-5 generally requires high-temperature heating in the presence of an organic structure-directing agent (OSDA) and a mesopore-generating agent (mesoporogen). Herein, we report a new method for the synthesis of hierarchically porous ZSM-5, which leads to the synthesis at low temperature in the presence of a reduced amount of OSDA and in the absence of any mesoporogen. The OSDA seems to play an additional role as a scaffolding agent for mesopore generation. Our study also showed that the control of the molar composition is essential for the crystallization of hierarchically porous-ZSM-5. [ABSTRACT FROM AUTHOR]