Synthesis and characterisation of sod-, can-and jbw-type structures by hydrothermal reaction of kaolinite at 200oc

Abstract

Low-silica zeolitic materials like SOD, CAN and JBW crystallized after hydrothermal transformation of kaolinite in the system Na₂O–Al₂O₃–SiO₂–H₂O at 200oC, with or without the addition of a structure-directing agent. The synthesis products were characterized by XRD, SEM, FTIR, ²⁹Si and ²⁷Al MAS-NMR and TGA. After dissolution of kaolinite in alkaline medium, co-crystallization of SOD and CAN, likely via a metastable LTA intermediate, was followed by a transformation to JBW-type structure.