Thermal and hydrothermal stability of SAPO-5 and SAPO-37 molecular sieves

Abstract

The stability of the crystalline structure of SAPO-5 and SAPO-37 has been studied in a heating chamber from room temperature to 1 400 K. After template decomposition a lowering in crystal symmetry was observed for SAPO-37 but not for SAPO-5. The stability of the two SAPOs is very similar up to about 1 300 K in a dry or a water vapour-containing atmosphere. Below about 345 K in the presence of water, only SAPO-37 progressively loses its crystallinity simultaneously with a decrease in unit-cell parameter.