Original paper

Crystallization of a basic sodalite under hydrothermal conditions studied by MAS-NMR, XRD and DTA/DTG

Mundus, Carsten; Müller-Warmuth, Werner; Buhl, Josef-Christian

European Journal of Mineralogy Volume 8 Number 2 (1996), p. 231 - 240

36 references

published: Apr 26, 1996
manuscript accepted: Nov 20, 1995
manuscript received: Jun 16, 1995

DOI: 10.1127/ejm/8/2/0231

BibTeX file

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Abstract

Abstract Hydrothermal syntheses in the system Na2O-SiO2-Al2O3-H2O, using cristobalite, corundum and mullite as starting substances, show simultaneous crystallization of basic hydrosodalite with basic cancrinite. The samples are characterized relative to their composition and the structure of the resulting products by 29Si and 27Al MAS-NMR spectroscopy in combination with thermal analysis and powder X-ray diffraction. By extending the reaction times up to 240 h, two different mechanisms could be identified at 423 and 473 K: at elevated temperature, the formation of cancrinite starts earlier and the reaction rate is increased. In both cases, crystallization of the products is accompanied by a transformation of the cancrinite into sodalite.

Keywords

sodalitesreaction kinetics27Al and 29Si solid state NMR