Solid-state NMR detection, characterization, and quantification of the multiple aluminum environments in US-Y catalysts by Al-27 MAS and MQMAS experiments at very high field

The detection of all of the aluminum present in steamed zeolite H-Y catalys ts by Al-27 MAS NMR at 14.4 T (600 MHz for H-1) end 18.8T (800 MHz for H-1) is reported. Further, it is shown that it is possible Al MAS and MQMAS NMR measurements to clearly identify four separate aluminum environments which are characteristic of these materials and to unambiguously assign their co ordinations. Average chemical shift and quadrupolar coupling parameters are used to accurately simulate the Al-27 MAS NMR spectra at 9.4 T (400 MHz fo r H-1), 14.4 T (600 MHz for H-1) and 18.8 T (800 MHz for H-1) in terms of t hese four aluminum environments. In addition, these:average chemical shift and quadrupolar coupling parameters are used to calculate peak positions in the Al-27 MQMAS isotropic dimension that are in good agreement with the ex perimental data acquired at 9.4 and 18.8 T.