1070-4272/02/7508-1360 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 8, 2002, pp. 1360!1361. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 8, 2002,
Original Russian Text Copyright + 2002 by Pavlov, Makhamatkhanov, Kutepov, Kudasheva, Lebedev.
Synthesis of Mordenite with the Use
of Aluminum Sulfate Solutions
M. L. Pavlov, R. A. Makhamatkhanov, B. I. Kutepov,
F. Kh. Kudasheva, and Yu. A. Lebedev
Institute of Petrochemistry and Catalysis, Academy of Sciences of Bashkortostan Republic
and Ufa Scientific Center of Russian Academy of Sciences, Ufa, Bashkortostan, Russia
Received October 15, 2001; in final form, January 2002
Abstract-A procedure has been developed for synthesis of a mordenite-type zeolite with high phase purity
and high dispersity of crystals. The procedure is based on hydrothermal crystallization of aluminum-silicon
hydrogels prepared from aluminum sulfate solutions serving as a source of Al(III).
Commonly, a mordenite-type zeolite is obtained
using sodium aluminate solutions with Al
O concentrations of 1503200 and 2003230 g l
respectively, as aluminum-containing reagents. How-
ever, the metastability of these solutins results in that
the desired results are not always obtained. The com-
position of the reaction mixture can be disturbed in
storage or upon dilution with water owing to the pre-
cipitation of aluminum hydroxide . Coarse grains
of aluminum hydroxide can play the part of foreign
heterogeneous crystallization centers, which deterio-
rates the phase purity and the dispersion composition
of the resulting zeolite. Furthermore, a separate unit
for preparation of sodium aluminate solutions is re-
quired in commercial production of the zeolite.
In this communication, an industrially promising
version of mordenite-type zeolite synthesis, with alu-
minum sulfate solutions as aluminum-containing raw
material, is proposed.
The synthesis was carried out in an autoclave with
a stirrer and a sampler. The degree of crystallization
and the type of the resulting zeolite were determined
by X-ray phase analysis. The procedure for obtaining
and studying zeolites is described in  in more detail.
Preliminary experiments have shown that morde-
nite-type zeolite can be synthesized from reaction
mixtures containing (mol): (1.837.1)Na
O . Al
O, which were prepared
by mixing aqueous solutions of sodium silicate and
hydroxide, and also aluminum sulfate. The kinetics of
solid phase crystallization was studied for this range
of reaction mixture compositions at 1253170oC.
Kinetic curves describing mordenite crystallization
at 130oC are presented in Fig. 1. They are S-shaped,
which is characteristic of kinetic curves describing
the crystallization of zeolites.
Approximately 35 h is necessary for mordenite with
high degree (~100%) of crystallinity to be formed
(Fig. 1, curve 1). Raising the Na
ratio (mol :
mol) in the reaction mixture from 1.8 to 3.0 leads to
Fig. 1. Dependence of the degree of sample crystallinity,
a, on the time t of crystallization at 130oC of reaction mix-
tures obtained with the use of aluminum sulfate solution.
Reaction mixture (mol): (1, 2) xNa
O . Al
x:(1) 1.8, (2) 3.0.