Framework and extra-framework aluminium distribution in (NH4)2F6Si-dealuminated Y zeolites

(NH4)2F6Si-dealuminated Y zeolite was studied by means of NMR, X-ray diffraction, IR and X-ray photoelectron spectroscopic measurements, before and after deep-bed calcination. The presence of EFALVI and the existence of a gradient of framework silicon-to-aluminium ratio along the crystallite are discussed.