CHANGES UPON HEATING OF THE DISTRIBUTION OF AL, P-ATOMS AND SI-ATOMS IN THE SAPO-37 MOLECULAR-SIEVE

A drastic change in the environment of Si atoms in SAPO-37 after heating at 1173 K is seen in the Si-29 MAS NMR spectrum. This suggests a modification of the location of Si, Al and P atoms. Three main phases would coexist in large amounts in the faujasite structure, the SAPO-37 originating phase, pure SiO4 islands and an aluminosilicate phase comparable to Si-Al faujasite.