ISSN 1070-4272, Russian Journal of Applied Chemistry, 2016, Vol. 89, No. 11, pp. 1797−1805. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © A.V. Kadomtseva, A.M. Ob’’edkov, M. N. Semenov, B.S. Kaverin, S.A. Gusev,
2016, published in Zhurnal Prikladnoi Khimii, 2016, Vol. 89,
No. 11, pp. 1428−1437.
Synthesis of Catalyst Based on Sol Microspheres Coated
with Pyrolytic Tungsten and Study of Its Inﬂ uence
on Production of Metallic Germanium
A. V. Kadomtseva
*, A. M. Ob’’edkov
, M. N. Semenov
, B. S. Kaverin
, and S. A. Gusev
Nizhny Novgorod State Medical Academy, Ministry of Health of the Russian Federation,
pl. Minina & Pozharskogo 10/1, Nizhny Novgorod, 603005 Russia
Nizhny Novgorod State Technical University n.a. R.E. Alekseev, ul. Minina 24, Nizhny Novgorod, 603155 Russia
Razuvaev Institute of Organometallic Chemistry, ul. Tropinina 49, Nizhny Novgorod, 603137 Russia
Institute for Physics of Microstructures, Russian Academy of Sciences, der. Afonino, Nizhny Novgorod oblast, 603087 Russia
* e-mail: email@example.com
Received August 4, 2016
Abstract—Pyrolytic tungsten coatings were deposited onto the surface of sol microspheres with tungsten hexa-
carbonyl used as precursor. A method was developed for reduction of germanium tetrachloride in the presence of
a catalyst based on sol microspheres coated with pyrolytic tungsten. The method makes it possible to reduce the
process temperature and diminish the number of stages in production of germanium. The kinetic characteristics
of the catalytic reduction of germanium tetrachloride with hydrogen were determined.
Germanium is widely used in micro- and nanoelectronics,
photovoltaics, and modern semiconductor industry .
The world’s consumption of germanium increases year
by year and the price of germanium is rather high, about
$2000 per kilogram .
There exist several technologies for obtaining ger-
manium. The main of these, used in the industry, is the
chloride method based on the interaction of hydrochloric
acid with germanium concentrates to give germanium tet-
rachloride, which is subjected to hydrolysis to germanium
dioxide and hydrogen reduction to metallic germanium.
In addition, germanium can be obtained by thermal
decomposition of high-purity germanium hydride, which,
in turn, is produced by the electrochemical method in an
aqueous-alkaline solution containing germanium dioxide.
The methods for obtaining germanium, considered
above, have a number of important shortcomings: nearly
all the methods are nonselective, with a large amount
of by-products formed as a result, which require a
complicated and a costly puriﬁ cation technology [4, 5].
When new methods for obtaining germanium are
developed, it is necessary to aim for the minimum amount
of starting reagents and number of process stages, which
will make it possible to reduce the contamination of the
ﬁ nal product. The most promising in this regard is the
direct catalytic reduction of germanium tetrachloride
with hydrogen, which can reduce the number of stages
and lower the process temperature, with germanium and
hydrogen chloride formed as the ﬁ nal product.
It is promising to use metals, including transition
metals, as catalysts. According to the Sabatier principle,
for reaching the maximum rate of the heterogeneous
catalytic reaction, the interaction between the adsorbate
and the surface should be neither too strong, nor too weak.
In this context, it was found in the study that tungsten has
a high adsorption capacity with respect to hydrogen and
germanium tetrachloride, but it is not as strong as, e.g.,
that of platinum and palladium, which, in turn, determines
the possibility of using tungsten as a catalyst for reduction
of germanium tetrachloride with hydrogen.
Because nanodispersed metallic particles are
frequently unstable and tend to be agglomerated at high
temperatures, the tungsten-based catalyst was deposited
on an inert support.
We chose as a support hollow sol aluminosilicate
microspheres (SMs) formed in burning of coals at thermal