Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 5, pp. 763−766.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
Nguen Man’ Tyong, Nguen Chan Khung, I.G. Ivanov, I.V. Baronin, E.G. Rakov, 2009, published in Zhurnal Prikladnoi Khimii, 2009,
Vol. 82, No. 5, pp. 711−714.
INORGANIC SYNTHESIS AND INDUSTRIAL
Fabrication of Catalysts for Synthesis of Carbon Nanotubes
by “Wet Burning” Method in Continuous Apparatus
Nguen Man’ Tyong, Nguen Chan Khung, I. G. Ivanov, I. V. Baronin, and E. G. Rakov
Mendeleev University of Chemical Engineering, Moscow, Russia
Received July 9, 2008
Abstract—Several reactor designs for continuous production of finely dispersed metal oxides by “wet burning”
were developed and tested. Basic dimensions of the reactors were determined on the basis of calculations of the
specific heat release and gas evolution, and laboratory prototypes of the reactors were fabricated and tested.
Catalytic pyrolysis of hydrocarbons is becoming
one of the principal methods for industrial production
of carbon nanotubes (CNT) and nanoﬁ bers . The
method employs metals-catalysts with nanosize particles
on metal oxide supports. The method of “wet burning,”
whose fundamentals are described in [2, 3], has found
comparatively wide application for fabrication of
catalysts of this kind. It was ﬁ rst used to synthesize
catalysts in .
The method consists in that a homogeneous aqueous
or organic solution containing nitrates of a metal-catalyst
(Fe, Co, Ni) and of a metal whose oxide serves as the
catalyst support (CaO, MgO, Al
) and a reducing agent
(urea, citric acid, glycine) is prepared. The solution is
placed in an open cup in a furnace heated to 500–550°C,
which results in that the solvent rapidly evaporates,
the solution is concentrated, and a strongly exothermic
reaction is initiated between the metal nitrates and the
reducing agents. The reaction accompanied by strong
gas evolution yields ﬁ nely dispersed oxides with a large
speciﬁ c surface area and homogeneous distribution of
the mixture components. In this way, mixed oxides, their
solid solutions, and salts (metallates) and composites can
The most widely used catalyst support is MgO .
The oxides CoO, NiO, and, possibly, FeO form with MgO
solid solutions and their reduction makes it possible to
release Co, Ni, and Fe in the form of nanosize particles
distributed in the MgO matrix.
In chemical essence, the starting mixture in the
wet-burning method is similar, before the initiation of
the reaction, to blasting powder, which conventionally
contains an oxidizing agent (potassium nitrate) and
reducing agents (sulfur), and the thermal mode of the
process is analogous to that of self-propagating high-
temperature synthesis. The speciﬁ c features of the “wet
burning” synthesis are the strong gas evolution and
heat release and the high rate (the reaction is complete
in minutes). This hinders performing the process in the
continuous mode, and, therefore, the process has been
described only in a batch variant with small portions of
A method for continuous production of catalysts for
CNT synthesis has been used only in a single study ,
in which the reaction was initiated by dispersion of the
starting solution in a burner ﬂ ame. An aqueous solution of
ethanol served as a solvent for making lower the solution
viscosity. The resulting ﬁ nely dispersed oxides (Fe,Mo/
MgO catalyst with an atomic ratio of 1.00 : 0.05 : 13.00
between the metals) were collected with an electrostatic
ﬁ lter. Despite having apparent advantages over the batch
variant, this process has shortcomings associated with
the difﬁ cult isolation of ﬁ nely dispersed particles from
strongly diluted gas ﬂ ows.
An analysis of the reactions used to obtain ﬁ nely
dispersed metal oxides and, in particular, catalysts for
CNT synthesis made it possible to suggest another method
for performing these reactions in the continuous mode 
and to develop several apparatus designs.