II International Symposium on Carbon for Catalysis ABSTRACTS

SURFACE ELECTROCHEMISTRY OF CARBON IN IONIC MELTS
PP-I-2
Barbin N.M.
Institute of High-Temperature Electrochemistry, Ural Branch RAS, Ekaterinburg, Russia
Institute of Metallurgy, Ural Branch RAS, Ekaterinburg, Russia
E-mail: N.Barbin@ihte.uran.ru
Various carbon materials serve as anodes and cathodes during electrometallurgical
process in melts for production of nonferrous metals.
The present study deals with electrochemical reactions taking place on the surface of
glassy-carbon anodes in oxygen-containing melts.
In the NaCl-KCl-Li 2 O [1] oxide ions discharge in stages (reactions 1 and 2):
O 2− + xC – 2 e = C x O ads , (1)
O 2− + C x O ads − 2 e = CO 2 + (1 − x)C. (2)
The reaction (1) is the reaction of electrochemical adsorption and the reaction (2) is the
reaction of electrochemical desorption. Kinetic parameters of the reactions were determined
in Ref. [1].
The following reactions take place on the electrodes in the NaCl−KCl−Na 2 CO 3 melt [2, 3]:
2−
CO + CO − 2e =
3
2CO
( x / 2 + 2y) C − 2e = 3/ 2xCO 3yCO
2−
CO +
2
3
+
2−
CO + 1/ 2C − 2e =
3
3/ 2CO
2
, (3)
2
, (4)
, (5)
CO 2 −
3
+ 2C − 2e = 3CO . (6)
The reaction (4) is a combination of the reactions (5) and (6) with partial coefficients x and y.
The coefficients x and y are related as x = 2α/(1 + 2α) and y = 1/(1+2α) to the ratio of partial
pressures in the gaseous phase P(CO 2 )/P(CO) = α. The contribution of the reactions (5) and
(6) depends on the composition of the gaseous phase and, to some extent, the type of the
carbon material of the electrode.
The ionic reaction
4OH − + C =
2−
CO 3
+ O
2− + 4H ads (7)
takes place on glassy carbon in the NaOH-KOH melt [4].
The anodic polarization is accompanied by the electrochemical reaction
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