(61c) Broadening the Scope of Fluoride-Free Siliceous Zeolite Synthesis
Dry gel conversion (DGC) has been used in the past for the fluoride-free synthesis pure silica forms of BEA, MFI and TON frameworks. In the case of BEA framework, DGC is the only known method to synthesize the pure silica form without the use of hydrogen fluoride. Herein we report the use of the DGC technique for the fluoride-free synthesis of siliceous CHA and STT zeolites for the first time. 29Si MAS NMR studies were used to understand the synthesis mechanism involved and the insights gained were used to improve the synthesis technique. In addition, we propose a new metric for analyzing siliceous zeolites and also that the uniqueness of the DGC technique allows it to be used as a general technique for the fluoride-free synthesis of a number of new siliceous zeolites.
 Vattipalli, V.; Paracha, A. M.; Hu, W.; Chen, H.; Fan, W. Angew. Chem. Int. Ed. 2018, 57, 3607 â3611.