High temperature phase transformations of cation exchanged zeolites: A new route for synthesis of aluminosilicate materials

Abstract

Thermal conversion of zeolites (LTA, SOD, TAU, and GIS) exchanged with monovalent counter ions (Li+, Na+, K+, Rb+, Cs+, NH4+, Ag+, and Tl+) is investigated from ambient temperature to 1400°C The new aluminosilicate phases such as α-eucryplite, Ag-carnegieite as well as KAlSiO4-ANA and CsAlSiO4-ANA are synthesized by this treatment. The mechanisms of phase transformations are elucidated by X-ray, DTA/DSC, and 29Si and 27Al MAS NMR methods. The temperature dependent electric conductivity measurements show that synthesized Ag-carnegieite possesses superionic characteristics whereas β-eucryptite can be classified as a good ionic conductor.