Hydrothermal syntheses of zeolite N from kaolin: Fid-Bau Portal

Hydrothermal syntheses of zeolite N from kaolin

Mackinnon, Ian D.R. / Millar, Graeme J. / Stolz, Wanda

Abstract Zeolite N, an EDI type framework structure with ideal chemical formula K12Al10Si10O40Cl2·5H2O, was produced from kaolin between 100°C and 200°C in a continuously stirred reactor using potassic and potassic+sodic liquors containing a range of anions. Reactions using liquors such as KOH, KOH+KX (where X=F, Cl, Br, I, NO3, NO2), K2X (where X=CO3), KOH+NaCl or NaOH+KCl were complete (>95% product) in less than 2h depending on the batch composition and temperature of reaction. With KOH and KCl in the reaction mixture and H2O/Al2O3 ~49, zeolite N was formed over a range of concentrations (1M<[KOH]<18M) and reaction times (0.5h<t<60h). At higher temperatures or higher KOH molarity, other potassic phases such as kalsilite or kaliophyllite formed. In general, temperature and KOH molarity defined the extent of zeolite N formation under these conditions. The introduction of sodic reagents to the starting mixture or use of one potassic reagent in the starting mixture reduced the stability field for zeolite N formation. Zeolite N was also formed using zeolite 4A as a source of Al and Si albeit for longer reaction times at a particular temperature when compared with kaolin as the source material.

Highlights ► Hydrothermal synthesis of zeolite N using kaolinite as source of Al and Si. ► A range of potassic salts with kaolinite over 100°C to 200°C produces zeolite N. ► Limited addition of sodic salts in presence of potassium can produce zeolite N. ► Formation conditions at shorter times and lower temperatures than earlier work. ► Zeolite 4A as source of Al and Si at longer reaction times produces zeolite N.