²⁷Al (left) and ²⁹Si (right) MAS NMR spectra of (a) the parent NaY zeolite, (b) after dealumination with SiCl₄, (c) HCl washing and (d) finally desilication with NaAlO₂. The ²⁹Si NMR spectrum of NaY shows the deconvolution into five peaks corresponding to Si(nSi, 4-nAl) environments that was used to calculate the framework Si/Al ratio. Asterisks in ²⁷Al NMR spectra indicate spinning side bands.