SYNTHESIS AND CHARACTERIZATION OF KALSIO4 POLYMORPHS ON THE SIO2-KALO2 JOIN .2. THE END-MEMBER OF ANA TYPE OF ZEOLITE FRAMEWORK

High-temperature phase transformations of K-LTA zeolite were investigated in the temperature range 800-1500 degrees C. The nanostructured KAlSiO4 precursor was prepared at 850 degrees C and after annealing at 1000 degrees C, the first polymorph of KAlSiO4, synthetic kaliophilite was formed. With increasing temperature, the following polymorphs were synthesized: kalsilite (1100 degrees C), low KAlSiO4-O-1 (1200 degrees C), KAlSiO4-ANA (1300 degrees C), and high KAlSiO4-O-2 at (1430 degrees C). Synthetic kaliophilite and KAlSiO4-ANA phases are the new polymorphs in the system studied. Consequently, the KAlSiO4-ANA phase is the ANA-type end member of the zeolite framework having the ratio Si/Al = 1. From XRD powder patterns a distorted leucite unit cell for a KAlSiO4-ANA phase was calculated: a(0) = 13.638(6) Angstrom, b(0) = 13.811(8) Angstrom, c = 13.817(9) Angstrom, alpha(0) = 99.98(4)degrees, beta(0) = 102.28(4)degrees, and gamma(0) = 62.80(4)degrees. Si-29 MAS NMR chemical shifts at -89.08 and -98.01 ppm suggest that the KAlSiO4-ANA phase has an ordered framework cation topology. (C) 1995 Academic Press, Inc.