An efficient synthetic route to accelerate zeolite synthesis: Via radicals

The energy-efficient and green synthesis of zeolites that are highly demanded in the chemical industry has been a focus for decades. Here we report a highly efficient radical-route to accelerate the synthesis of zeolites via using sodium persulfate (denoted as SPS) as an additive in the hydrothermal reaction system of SiO₂-TPAOH-H₂O. The hydrothermal synthesis of highly crystalline silicalite-1 was shortened to 16 h from 24 h in the presence of 0.02 M SPS. Electron paramagnetic resonance (EPR) was used to characterize the radical species induced by SPS. More importantly, as compared with the conventional synthetic system, highly crystalline silicalite-1 can be synthesized with only half of the amount of organic structure-directing agents in the presence of SPS. With this route, we can not only speed up the hydrothermal crystallization of a silicalite-1 zeolite but also greatly reduce the usage of organic structure-directing agents. This radical-route demonstrates an efficient and green route for the synthesis of zeolites.