Preparation and structural characterization of disordered Na-gallosilicate zeolite with natrolite framework and its K+ and NH4+ exchanged analogues

Abstract

We report first time preparation and crystal structure of NH₄⁺ exchanged form of highly disordered gallosilicate zeolite with natrolite framework (NAT) by ion exchange method from K-gallosilicate zeolite with natrolite framework. K⁺ exchanged form was obtained by ion exchange with hydrothermally prepared highly disordered sodium gallosilicate zeolite with natrolite framework. Phase purity, degree of ion exchange, particle morphology, elemental mapping and thermal behaviour of Na-, K-, NH₄-gallosilicate zeolites were investigated using various instrumental techniques. Crystal structures of Na-, K-, NH₄-gallosilicate zeolites were obtained by Rietveld analysis of powder X-ray diffraction data collected using synchrotron source of X-rays. Refined structural models of hydrated Na-, K-, NH₄-gallosilicate zeolites were compared. NH₄-gallosilicate zeolite was calcined at 450 °C to obtain its H-form. The structure collapse of H-gallosilicate zeolite with natrolite framework is commented finally based on the structural characterization data.