Synthesis of high silica SSZ-13 in fluoride-free media by dry gel conversion method

摘要

Chabazite SSZ-13 has attracted wide attention due to its physiochemical properties and excellent potential as a catalyst for various application. In this study, pure phase SSZ-13 CHA zeolite with wide range of Si/Al ratio has been synthesized in a fluoride-free media by dry gel conversion method where the conversion of SSZ-13 from aluminosilicates precursor gel occurs under water vapor. The difference between products produced by conventional hydrothermal synthesis method and the new method has been investigated and characterized with XRD, SEM, XRF, and N-2 adsorption. Pure SSZ-13 with wide range of Si/Al up to 182 was obtained by dry gel conversion method while pure SSZ-13 with higher Si/Al ratio than 20 with similar starting gel composition could not synthesized by hydrothermal synthesis method. Our work has demonstrated that dry gel conversion method was an effective method to synthesize pure SSZ-13 with a wide range of Si/Al ratio under fluoride media-free condition.