A solid-state NMR study of the formation of molecular sieve SAPO-34

摘要

This work examined the formation of a catalytically important microporous material, SAPO-34, in the presence of HF under hydrothermal synthesis conditions. The local environments of P, Al, F and Si atoms in several solid phases obtained at different stages of crystallization were characterized by several solid-state NMR techniques including 31{sup left}P, 27{sup left}Al, 19{sup left}F and 29{sup left}Si MAS, 27{sup left}Al triple-quantum MAS, 31{sup left}P{27{sup left}Al} transfer of populations in double-resonance, 27{sup left}Al{31{sup left}P} rotational-echo double-resonance (REDOR), 27{sup left}Al→31{sup left}P heteronuclear correlation spectroscopy, 31{sup left}P{19{sup left}F} and 27{sup left}Al{,9{sup left}F} REDOR as well as 1{sup left}H→31{sup left}P cross polarization. The NMR results provide the new insights into the formation of SAPO-34.