High-resolution solid-state nuclear magnetic resonance studies of dealuminated zeolite Y

Abstract

The products of hydrothermal treatment of zeolite NH₄-Na-Y and of treatment of zeolite Na-Y with silicon tetrachloride vapour under different conditions were examined by ²⁹Si and ²⁷Al high-resolution solid-state n.m.r. with magic-angle spinning (m.a.s.n.m.r.) at high magnetic fields. ²⁹Si m.a.s.n.m.r. in combination with chemical analysis allowed the amount of framework and non-framework aluminium to be readily and quantitatively determined. However, not all non-framework aluminium is observed by ²⁷Al m.a.s.n.m.r. in most samples. Hydrothermal dealumination yielded materials with Si/Al ratios of up to 6.92, while the zeolite dealuminated with Si/Cl₄ had framework Si/Al ratios of up to 25 and contained little interstitial aluminium. M.a.s.n.m.r. is superior to X-ray diffraction as a method of determining zeolite composition.