H(4)EDTA- and (NH4)(2)SiF6- liquid phase dealuminated Y zeolites (EDY
and FDY) and hydrothermally dealuminated Y zeolites (USY) were treated
with an aqueous solution of KOH. The products were characterized by u
sing XRD, n.m.r., FT i.r., SEM, and fast atom bombardment mass spectro
scopy (FABMS) techniques. A decrease of Si/Al ratios was observed in t
he basic solution-treated samples. The results clearly show that disso
lution of the surface of EDY and removal of silicon atoms from the fra
mework lattice of FDY occurs during basic solution treatment. Realumin
ation of ultrastable Y zeolite (USY) takes place through reinsertion o
f aluminum into the framework vacancies formed during hydrothermal tre
atment of NH4NaY or formed during a basic solution treatment of USY. (
C) Elsevier Science Inc. 1997.