Thermally induced phase transformation of Pb-exchanged LTA and FAU-framework zeolite to feldspar phases

Abstract

Thermally induced phase transformations of Pb-exchange LTA and FAU zeolites were from ambient temperature to 1300 °C. Both frameworks collapse into amorphous intermediate products after heating between 600 and 650 °C. Prolonged heating of the intermediate product over 1100 °C results in the formation of disordered Pb-feldsparLTA [a = 8.414 (4) Å, b = 13.048 (4) Å, c = 7.169 (4) Å, β = 115.35° (3)] and Pb-feldsparFAU [a = 8.422 (4) Å, b = 13.054 (4) Å, c = 7.173 (4) Å, β = 115.37° (3)] phases. The phase conversions within the investigated temperature range were followed by thermal (DTA, TGA, and DSC), XRPD, and Raman methods.