Diagrams Er-mKOH for Cobalt at 25-125 °C and at Total Pressure of 1-30 Bar

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Title:Diagrams Er-mKOH for Cobalt at 25-125 °C and at Total Pressure of 1-30 Bar
Creators:
Balej, Jan
Divisek, Jiri
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 62, 11, pp. 1663-1676
Uncontrolled Keywords:Cobalt oxo compounds, Corrosion, Alkaline water electrolysis

Abstract

Diagrams <i>E</i><sub>r</sub>-<i>m</i><sub>KOH</sub> for cobalt were calculated in the range of molality <i>m</i><sub>KOH</sub> = 2-18 mol kg<sup>-1</sup>, temperature <i>t</i> = 25-125 °C and total pressure <i>P</i> = 1-30 bar (0.1-3.0 MPa) on the basis of recent reliable data for individual reaction components. The water activity <i>a</i><sub>H<sub>2</sub>O</sub>, the equilibrium pressure of the water vapour <i>p</i><sub>H<sub>2</sub>O</sub> in or above the KOH solutions was considered. The results displayed differences from the original <i>E</i>-pH diagram for cobalt after Pourbaix. The direct oxidation of Co<sub>3</sub>O<sub>4</sub> to CoO<sub>2</sub> without any intermediate stage of Co(III) oxo compounds was found to be thermodynamically more favourable. Consideration of the reduced water activity in concentrated KOH solutions led to the finding that solid Co(OH)<sub>2</sub> can be dehydrated to CoO at elevated temperatures in contact with KOH solutions. With rising temperature, dehydration can occur at lower KOH molality. CoO<sub>2</sub>, not known in a pure form, was assumed to exist as a pure substance in mixtures with other solid Co oxo compounds in lower states of oxidation.

Title:Diagrams Er-mKOH for Cobalt at 25-125 °C and at Total Pressure of 1-30 Bar
Creators:
Balej, Jan
Divisek, Jiri
Uncontrolled Keywords:Cobalt oxo compounds, Corrosion, Alkaline water electrolysis
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:62
Number:11
Page Range:pp. 1663-1676
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19971663UNSPECIFIED
ID Code:1241
Item Type:Article
Deposited On:06 Feb 2009 17:07
Last Modified:06 Feb 2009 16:07

Citation

Balej, Jan; Divisek, Jiri (1997) Diagrams Er-mKOH for Cobalt at 25-125 °C and at Total Pressure of 1-30 Bar. Collection of Czechoslovak Chemical Communications, 62 (11). pp. 1663-1676. ISSN 0010-0765

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