Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 6, pp. 879−885.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © A.A. Lamberov, E.Yu. Sitnikova, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 6, pp. 938−944.
Inﬂ uence of the Structure and Composition of Zeolite NaX
on Carbon Dioxide Adsorption
under Dynamic Conditions
A. A. Lamberov
and E. Yu. Sitnikova
Kazan (Volga Region) Federal University, Kazan, Tatarstan, Russia
Kazan National Research Technological University, Kazan, Tatarstan, Russia
e-mail: email@example.com, firstname.lastname@example.org
Received October 5, 2012
Abstract—Using the X-ray diffraction analysis, emission spectral analysis, low-temperature nitrogen adsorp-
tion, and electron spin resonance methods, the dynamic sorption capacity in removal of carbon dioxide from gas
streams, exhibited by type NaX zeolite samples, was studied in relation to their phase and elemental compositions
and crystal and pore structure characteristics. It was found that the criteria determining the capacity of the zeolite
are the content of the crystalline phase, imperfection of the crystal structure as determined by the crystallite size
and the amount of iron isomorphously substituting the aluminum cations in the tetrahedral sites of the zeolite, and
the number of compensating sodium cations.
Selective treatment of gas streams from petrochemical
units and reﬁ neries is one of the most important stages
in their processing, because various impurities contained
in gas streams can deteriorate the quality of the products
and disturb the normal operation of the process units. For
example, to prevent freezing of the process equipment
and problems with its operation under low-temperature
gas separation conditions, rigid requirements are posed
on the gas streams being separated in terms of the content
of impurities capable of forming crystal hydrates and
ice jams at low temperatures. Among these impurities
is carbon dioxide whose content in an air stream prior
to low-temperature separation should not exceed 40–
50 ppm .
Currently, type NaX zeolites are extensively used
for selective removal of carbon dioxide impurities from
gas streams [2, 3]. One of the problems frequently en-
countered in commercial production of NaX zeolites is
insufﬁ cient reproducibility of operational characteristics,
in particular, of the dynamic adsorption capacity for
Here, we examined how the crystal and pore structure
characteristics and the composition of type NaX zeolites
inﬂ uence their sorption capacity in selective removal of
carbon dioxide from gas streams.
The objects of our study were commercial samples of
type NaX zeolite, prepared by the following procedure:
synthesis of a type NaX zeolite crystallite from the reac-
tion mixture comprised of sodium aluminate, silicate, and
hydroxide, followed by ﬁ ltration and drying; formation
of type NaX zeolite granules using natural kaolin clay as
binder; and heat treatment at 550–600°C of the resultant
granules exhibiting different sorption capacities in selec-
tive removal of carbon dioxide from gas streams.
As shown by X-ray diffraction examination (Fig. 1),
all the zeolite samples have virtually identical phase
compositions and are comprised of type NaX zeolite (the
main characteristic peak corresponding to the interplanar
spacing d/n = 14.25 Å) with a type Na-A zeolite impu-
rity (the main characteristic peak at d/n = 12.19 Å) [4,