ISSN 0020ꢀ1685, Inorganic Materials, 2012, Vol. 48, No. 3, pp. 238–243. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.G. Burlakova, S.P. Shilkin, O.V. Kravchenko, N.N. Dremova, S.E. Kravchenko, A.V. Ivanov, B.M. Bulychev, 2012, published in Neorganicheskie
Materialy, 2012, Vol. 48, No. 3, pp. 290–296.
Activation of Metallic Aluminum
by Tin and Gallium Chlorides in Oxidation with Water
a
b
b
a
A. G. Burlakova , S. P. Shilkin , O. V. Kravchenko , N. N. Dremova ,
a
a
b
S. E. Kravchenko , A. V. Ivanov , and B. M. Bulychev
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
a
pr. Akademika Semenova 1, Chernogolovka, Moscow oblast, 142432 Russia
b
Faculty of Chemistry, Moscow State University, Moscow, 119992 Russia
eꢀmail: kgv@icp.ac.ru
Received July 18, 2011
Abstract—We have studied the effect of gallium chloride and tin chloride solutions on the water oxidation of
aluminum at SnCl concentrations of 0.68 and 6.32 wt %, GaCl3 concentrations of 0.56 and 2.67 wt %, and
2
MCln : Al(M = Sn, Ga; n = 2, 3) molar ratios from 0.017 to 0.3. The results indicate that, when aluminum is
oxidized in the presence of these salts, the reaction rate and hydrogen yield increase with reaction temperaꢀ
ture and salt concentration and reach the highest levels when a mixture of gallium and tin chlorides is used.
The reaction products are identified and the likely mechanism of the processes involved in the oxidation of
aluminum is discussed.
DOI: 10.1134/S0020168512020069
INTRODUCTION
EXPERIMENTAL
Starting reagents. In our preparations, we used
The activation of aluminum that makes it reactive
with water involves the rupture of the dense oxide film
on its surface and can be achieved in a variety of ways,
which can be classified according to the underlying
reaction type: nominally catalytic reactions, including
amalgamation [1, 2] and treatment of metallic alumiꢀ
num with galliumꢀbased liquid alloys [3–6], and stoꢀ
ichiometric metal oxidation reactions at high temperꢀ
atures [7] or in alkaline and acidic solutions [8]. To a
first approximation, the last reaction type can be
thought to include aluminum oxidation by solid crysꢀ
ASDꢀ4 aluminum metal (Purity Standard TU 48ꢀ5ꢀ
2
26ꢀ8, 99+% purity), commercially available pureꢀ
grade SnCl2 2H O, gallium and indium metals of
9.9+% purity, and other chemicals of reagent or anaꢀ
lytical grade. Tin chloride solutions were prepared by
dissolving SnCl2 2H О in water. The tin dioxide that
⋅
2
9
⋅
2
was present in the asꢀpurchased tin chloride and the
basic tin chloride that resulted from hydrolysis were
filtered off. The resultant solutions were analyzed for
Sn and Cl by standard techniques and then diluted
with distilled water to desired concentrations. Next,
talline hydrous salts, in which the water molecules the solution pH was measured. The pH of the tin chloꢀ
acquire acidic properties when coordinated to the ride solutions was 2–3, and that of the gallium chloꢀ
central atom [9]. Some salts, e.g., copper and tin ride solutions was 4–4.5. In the course of aluminum
chlorides, are reduced to the metals when reacting oxidation, the solution pH increased to 6, probably
with aluminum [9, 10], which suggests the formation because of the surface oxide film dissolution and aluꢀ
of an electrochemical pair. Since aqueous solutions minum hydroxide formation. An aqueous gallium
chloride solution was prepared by dissolving an excess
of metallic gallium in moderately heated 10% hydroꢀ
chloric acid, followed by decantation of the solution
containing the residual metal. Indium chloride was
prepared in a similar way. The gallium and indium
of a number of salts also promote aluminum oxidaꢀ
tion, a more complicated mechanism of the process
is possible: reaction of the metal with their hydrolysis
products.
In this context, it is of interest to investigate the chloride solutions were analyzed argentometrically for
effect of solutions of salts that possess the above possiꢀ chlorine. Gallium and indium were determined by
bilities, that is, to run the aluminum oxidation process atomic absorption in an acetylene–air flame, using the
in catalytic, electrochemical, and stoichiometric 287.4ꢀ and 303.9ꢀnm resonance lines and a deuterium
background corrector. The concentrations used to
activate solutions are listed in Table 1.
Experimental procedure and analytical techniques.
To a glass reaction vessel having a charging port and a
modes at salt contents within 10–15 mol % relative to
aluminum. These requirements are met, e.g., by galꢀ
lium(III) and tin(II) chlorides, whose behavior is the
subject of this study.
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