The Regular Features of Chlorine Formation
in the Systems NaCl–Me
T. A. Rozdyalovskaya, Yu. S. Chekryshkin, A. N. Chudinov, and A. A. Fedorov
Institute of Technical Chemistry, Russian Academy of Sciences, Ural Division, Perm, Russia
Received March 10, 2009
Abstract—The reaction of sodium, calcium, and zinc chlorides with atmospheric oxygen in the presence of
transition metal oxides and antimony oxide at temperatures exceeding the melting temperatures of chlorides
was studied. The content of chorine, product of oxidation of chloride ions in molten NaCl and CaCl
determined as a function of the polarization force of cations of transition metal oxides.
INORGANIC SYNTHESIS AND INDUSTRIAL
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 9, pp. 1510–1514. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © T.A. Rozdyalovskaya, Yu.S. Chekryshkin, A.N. Chudinov, A.A. Fedorov, 2009, published in Zhurnal Prikladnoi Khimii, 2009,
Vol. 82, No. 9, pp. 1414–1418.
The heterogeneous-catalytic oxidation used for
neutralization of chlorine-containing organic sub-
stances yields chlorine and hydrogen chloride, which
react with the components of a solid-phase catalyst and
cause its destruction or deactivation.
For certain molten catalytic compositions, the reac-
tion with Cl
and HCl is reversible , which can be
used in development and regeneration of catalysts.
Therefore, we studied the oxidation of chloride ions in
the Na(Ca, Zn)Cl
systems, where M
transition metal oxide and antimony(V) oxide.
The oxidation of halide ions in a melt of
metaphosphates in the presence of atmospheric oxygen
has been studied in [2, 3]. The reaction of Na(K)Cl
at 400–600°C in air can be used for syn-
thesizing sodium and potassium metavanadates [4–6].
A method has been proposed  to produce chlorine
and calcium oxide by oxidation of calcium chloride
with atmospheric oxygen at 800°C. The oxidation of
chloride ions with permanganate ions, including that
with joint action of ozone, has been studied in [8, 9].
The introduction of metaphosphates  and transition
metal oxides  into the NaCl melt promotes
oxidation of chloride ions.
We used in the experiments NaCl, ZnCl
(all of chemically pure
grade) and analytically pure CuO. The air (nitrogen)
was bubbled through the solution or passed over the
surface of the reaction mixture. The content of released
chlorine was determined iodometrically by passing it
through a solution of potassium iodide and titration of
the formed amount of I
with sodium thiosulfate
solution. The method of performing the experiments
has been described in detail in .
The X-ray phase analysis (XPA) was performed at
room temperature in air [Rigaku diffractometer D
radiation, λ = 1.5418 Å]. The
presence of certain elements in the reaction products
was confirmed by the thermal and flame atomic
absorption spectroscopies (GBC 908AA spectrometer).
In air flow, chlorine starts to separate from calcium
chloride at 380°C, i.e., below the melting point (T
772°C) and from ZnCl
it starts to separate above 400°C,
i.e., above the melting point (317°C). In an air flow of
2.5 l h
, no chlorine is separated from sodium chloride
at 800–820°C, whereas from ZnCl
, 0.00289 moles of
per 1 mole of ZnCl
is separated at 580°C in 8 h.
The amount of chlorine formed by the reaction of
calcium chloride with atmospheric oxygen at 700°C in
5 h is considerably less (0.00897 moles of Cl
1 mole of CaCl
The specific amount of chlorine (moles of Cl
1 mole of oxide) formed in the NaCl–V
, and NaCl–Cr
systems at 800°C is in-
dependent of concentration of the oxides in the range