Effect of High-Temperature Steam Treatment
on Structural Characteristics of Y-Type Zeolites
with Various Sodium Contents
A. A. Tantseva, A. N. Khazipova, G. F. Garieva, and B. I. Kutepov
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, Ufa, Bashkortostan, Russia
Received November 24, 2009
Abstract―The effect exerted by temperature of steam treatment and degree of exchange of Na
lattice parameters and texture of Y zeolites with the initial SiO
ratio 4.9 and 6.0 was determined.
INORGANIC SYNTHESIS AND INDUSTRIAL
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 12, pp. 2100–2105. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.A. Tantseva, A.N. Khazipova, G.F. Garieva, B.I. Kutepov, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 12,
The catalytic properties of Y zeolites are mainly
determined by the cation composition and SiO
molar ratio (silica ratio) of its crystalline skeleton .
The catalytic activity and stability of Y zeolites
increases with increasing silica ratio [2, 3]. This is
especially important for a zeolite catalyst used as
active component for cracking of oil fractions under
The most common method for raising silica ratio of
Y zeolite is the high-temperature steam treatment
(TST) including hydrolysis of tetrahedral aluminum
and its release from the zeolite lattice [2, 3]. Alumi-
num, released from the lattice, is present in the zeolite
in the form of off-lattice compounds that may be
located within the existing micropores or form deposits
on the outer surface of zeolite crystals [2, 4–6].
Dealumination causes lattice parameter of the zeolite
to decrease, because Si–O bond is shorter than the Al–
O bond. In its turn, reducing the average interatomic
distance contributes to the stability of the zeolite lattice
. The process of dealumination is accompanied by a
partial amorphization of the crystalline skeleton and
the formation of the secondary pore structure with a
pore radius of 10–20 Е [8, 9].
It was shown that the degree of the zeolite lattice
dealumination may be controlled by varying the
temperature and time of high-temperature steam
treatment and also by changing the degree of exchange
in the initial sample [10–14].
However, the above studies mainly discuss the effect
of high-temperature steam dealumination for Y
zeolites with the initial silica ratio to 4.5. Data on the
dealumination of Y zeolites with higher silica ratios is
very limited and contradictory.
We studied how the conditions of the high-
temperature steam dealumination affect the crystal
structure of Y zeolites with silica ratios more than 4.5
and various exchange degrees α
Samples under study were industrial NaY powder-
like zeolite (silica ratio 4.9) manufactured by
Salavatnefteorgsintez Open Joint-Stock Company for
cracking and a promising NaY zeolite (silca ratio 6.0)
synthesized without templates and additional
treatments [15, 16].
Zeolite samples with varied α
were prepared by
the ion-exchange. The ion exchange was carried out in
an isothermal reactor with vigorous agitation of a
zeolite suspension in an aqueous solution of
ammonium sulfate at 95°С for 1 h. It was shown
previously  that substitution of Na
zeolites without intermediate heat treatments can
proceed by no more than by 0.70, which is due to the
specificity of the localization of Na
in the crystal
lattice. Therefore, the samples were subjected to
several intermediate thermal treatments at 600°С in air.
The resulting samples contained from 8.0 to 0.1 wt % of
residual sodium (exchange degree from 0.32 to 0.99).