Rapid solvent-free synthesis of nano-sized ZSM-5 with a low Si/Al ratio at 90 °C

Nano-sized ZSM-5 zeolites with wide framework Si/Al ratios are highly desired in the petrochemical and other fields, whereas their synthesis suffers from cost, efficiency and environmental issues. Herein, a new protocol is proposed for the rapid synthesis of ZSM-5 with a low Si/Al ratio at a low temperature. That is, preparing a solid mixture by grinding solid raw materials with a liquid seed and crystallizing the mixture under solvent-free conditions at 90 degrees C. It is proved that the liquid seed not only accelerates the zeolite crystallization but also boosts the incorporation of Al into the zeolite framework. It is found that the ZSM-5 zeolite with a Si/Al ratio of 36 and an ultra-small crystal size (ca. 25 nm) can be synthesized within 30 hours at 90 degrees C and a framework Si/Al ratio of 28 can be reached at this temperature in this way. This ZSM-5 zeolite exhibited better catalytic performance in the reaction of methanol to olefins compared to that synthesized by the conventional hydrothermal method.

Automated summary

A new protocol for the rapid synthesis of ZSM-5 zeolites with a low Si/Al ratio at a low temperature has been proposed in this study. The liquid seed used in the synthesis not only accelerates zeolite crystallization but also enhances the incorporation of Al into the zeolite framework. The synthesized ZSM-5 zeolite exhibited better catalytic performance compared to the conventionally hydrothermally synthesized one.