Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 9, pp. 1524−1528.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.A. Matveev, V.T. Kalinnikov, V.I. Zakharov, D.V. Maiorov, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 9,
OF SYSTEMS AND PROCESSES
Investigation of an Effect Exerted by Methods of Production
of Chromium(III) Oxides–Hydroxides
on Their Physicochemical Properties
V. A. Matveev, V. T. Kalinnikov, V. I. Zakharov, D. V. Maiorov
Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Resources,
Kola Scientiﬁ c Center, Apatity, Murmansk oblast, Russia
Received March 1, 2011
Abstract—Results of a research of physical and chemical properties of chromium(III) oxides-hydroxides are
reported produced from chromo-potassium alum by solid-phase hydrolysis and sol-gel method. Comparative
assessment of structural properties of chromium oxides–hydroxides obtained by various techniques was suggested
and the morphology was studied.
In recent years mesoporous oxide materials are of
a growing interest, in particular based on chromium
oxide, which, because of their unique physical and
chemical properties are widely used in the production of
catalysts, adsorbents, desiccants. Typically, metal oxides
are obtained by thermal treatment of their hydroxides.
One of the main methods of producing metal hydroxides
and mixed hydroxide compositions is their precipitation
from solutions of the salts under the action of bases [1,
2]. The problem of obtaining hydrate precipitates with
stable physical and chemical properties is complicated
by the fact that the hydrolysis of salts is accompanied
by difﬁ cult to control polymerization of aqua ions that
leads to a non-equilibrium distribution of particles of
polynuclear hydroxo complexes being formed. This is
one of the main reasons for non-repeatable results.
Recently developed solid-phase hydrolysis method
[3, 4], which is based on the assumption of the possibility
of the hydrolysis of metal salts which are crystalline in
the solid state, when the ions have minimal mobility,
under the action of an alkaline reagent (ammonia gas,
carbonates of alkali and alkaline earth metals, ammonium
carbonates). Theoretical basis for this assumption was
the fact that in the crystalline hydrate metal ion is in the
form of aqua complex, i.e., as in a solution each atom is
surrounded by water molecules, so there are objective
prerequisites for the hydrolysis by the mechanism of
deprotonation of water molecules coordinated around
the metal atom.
The goal of the study was carrying out the
physicochemical examinations to obtain chromium
oxide with stable physicochemical properties.
As a precursor we used chromo potassium alum
O] (CPA), of analytically
pure grade. When used sodium carbonate (Na
as a neutralizing agent solid-phase hydrolysis of CPA
was carried out carefully by mixing reagents with
their subsequent exposure at 90°C for 1 h. In the case
of use ammonia gas as a neutralizing agent the latter
was obtained by slow heating of concentrated (25–
) solution of hydrate and transmitted through
a layer of salts of 30–50 mm thickness. To control the
completeness of the reaction we suspended in water
an averaged sample of product of ammonia processing
and measured the pH. When pH reached not less than 8
the process was considered complete.
Products of the solid-phase hydrolysis was treated
with water at a temperature of 40–60°C for 10–15 min,
the resulting slurry was ﬁ ltered off, the precipitate of
amorphous hydrated chromium oxide (HCO) was
separated from a solution containing ammonium,