engleski

Thermal Transformation of Various Potassium Aluminosilicate Precursors

The isothermal amorphization of potassium exchanged zeolite A and recrystallization of the formed amorphous phase as well as the crystallization of the X-ray amorphous K-aluminosilicates (prepared in two ways: (A) by ion-exchange of sodium ions from zeolitic Na-aluminosilivate gel with the alkaline cation K resulting in K-gel(A) and (B)by direct precipitation from the corresponding K-aluminate and K-silicate solutions resulting in K-gel(B)) at three different temperatures were investigated by powder X-ray diffraction method. Phase analysis of the transformation/crystallization process have shown that: pure crystalline tetragonal leucite crystallizes from K-gel(A) in the temperature range from 1423 to 1483 K, where pure hexagonal kalsilite crystalizes from K-gel(B) and K-exchanged zeolite A in the temperature range between 1423 and 1483 K and 1258 and 1298 K, repactively.

Temperature-induced transformation; Zeolite KA; Amorphous aluminosilicate; kalsilite; Leucite

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