ISSN 09655441, Petroleum Chemistry, 2016, Vol. 56, No. 3, pp. 197–204. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © E.V. Parkhomchuk, K.A. Sashkina, V.N. Parmon, 2016, published in Neftekhimiya, 2016, Vol. 56, No. 3, pp. 214–221.
197
The developed micropore system of the majority of
zeolites imposes significant diffusion limitations on
the rate of zeolitecatalyzed reactions involving mac
romolecular organic reagents [1]. For more effective
use of the active surface of a zeolite catalyst, an addi
tional system of larger pores of a given size, the so
called hierarchical micro–meso–macropore system,
is created in the material [2]. According to the results
of studies carried out in the last 10–15 years, hierar
chical zeolites are considerably more active than con
ventional microporous catalysts in petrochemical
alkylation, isomerization, and esterification reaction
[2–4] or in the reactions of complete oxidation of
organic compounds [5].
There is a great variety of methods known to date
for creating hierarchical pore structure of zeolites,
which can be roughly divided to two different routes,
the topdown and bottomup synthetic approaches [6,
7]. The former, topdown approach consists in treat
ment of an already crystallized zeolite by various
means, for example, with steam, acid, or alkali, and in
partial amorphization of the zeolite crystal framework
[8]. These types of treatment result in a material with
irregular porosity and a wide size distribution of meso
pores. There are also methods for creating a hierarchi
cal structure using the topdown approach that make
it possible to control more accurately the textural
characteristics of the material. These are, for example,
methods of structural modification of layered zeolites,
which include separation of zeolites into layers with
subsequent random layer packing, “delamination”, or
insertion of inorganic particles in interlayers, “pillar
ing” [9]. The second, “bottomup” approach suggests
modifying the conditions of hydrothermal (HT) crys
tallization of zeolite. Thus, by radically changing HT
synthesis parameters (temperature, time, and surfac
tant concentration in gel), it is possible to prepare zeo
lite nanocrystals and make on their basis one or
another material with desired textural characteristics
[10]. Introduction of supramolecular templates, for
example, polystyrene (PS) microspheres, during
hydrothermal crystallization of zeolites also leads to
the formation of an additional system of transport
pores in the material after the removal of organic com
ponents [11].
Ironcontaining zeolites exhibit high activity in
reactions of complete oxidation of organic com
pounds. However, the first attempts to obtain hierar
chical Fecontaining zeolites using polystyrene
microspheres resulted in composite zeolite materials
containing a large proportion of the amorphous phase
[12]. Despite the fact that such materials have shown
high effectiveness in reactions of complete catalytic
oxidation of large organic molecules with hydrogen
peroxide, the presence of the amorphous phase makes
New Heterogeneous Catalysts Based on Zeolites
with Hierarchical Pore System
E. V. Parkhomchuk
a–c
, K. A. Sashkina
a–c
, and V. N. Parmon
a, b
a
Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
b
Novosibirsk State University, Novosibirsk, Russia
c
Research and Education Center for EnergyEfficient Catalysis, Novosibirsk State University, Novosibirsk, Russia
email: ekaterina@catalysis.ru
Received November 16, 2015
Abstract—The results of synthesis and packing of crystallized ironcontaining nanosized zeolites of MFI
structure in dense and loose structures having different textural properties are reported. Data on the forma
tion of additional meso and macropores immediately during zeolite crystallization using polystyrene micro
spheres in the form of an aqueous suspension (latex) and as a dry template of closely packed particles are also
presented. Advantages and disadvantages of these procedures for preparing hierarchical ironcontaining MFI
structure zeolites have been compared. Values of the external surface area and the total pore volume of hier
archical Fesilicalites are significantly higher than those for a reference sample. Using the polymer template
to synthesize the hierarchical material consisting of zeolite nanocrystals makes it possible can significantly
reduce the synthesis time and simplify the preparation procedure.
Keywords: ironcontaining zeolites, synthesis, hierarchical pore system, micromesomacropores
DOI: 10.1134/S0965544116030105