13-P-11-Structure change of molecular sieve SAPO-37 at high temperature studied by 27Al MQ MAS NMR

Publisher Summary This chapter describes the structure change of molecular sieve SAPO-37 at high temperature studied by aluminium ( 27 Al) multiple-quantum magic angle spinning nuclear magnetic resonance (MQ MAS NMR). When SAPO-37 is calcined at 1173 K, silicon (Si) atoms become mobile and detached from the framework to aggregate to form polymorph silica while Al-phosphorus (P) dense phase is formed, corresponding to a new Al signal, which can be distinguished by the 27 Al MQMAS spectrum. The move of atoms in SAPO-37 is the start of the collapse of the framework.