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

• The disorder Pb feldspar was synthesized with ZTIT method.
• The Rietveld method was used for determined structure.
• The Pb-feldsparLTA was refined (agreement factors R(F) = 6.39, R(B) = 6.91, Ch2 = 2.07 for the C2/m).
• The crystal structure of the Pb-feldsparFAU was refined (agreement factors: R(F) = 4.68, R(B) = 4.59, Ch2 = 2.08 for the C2/m).

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.

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