The unusually high solubilities and thermal coefficients of solubility of the alkali metal hydroxides make them attractive candidates for high-temperature electrolytic processes to produce high-pressure hydrogen. The feasibility of using strong sodium hydroxide (to keep down the saturation pressure of the condensed phase) electrolysis (to facilitate the separation of the hydrogen from oxygen over a liquid phase) at high temperatures (to increase the energy efficiency by substitution of process heat for electric power) and to increase the production rate in a given cell (by increasing the specific conductance of the working fluid) is explored and discussed. Suggestions are made for future research.

1.
Fletcher
,
E. A.
,
1999
, “
Solarthermal and Solar Quasi-Electrolytic Processing and Separations: Zinc from Zinc Oxide as an Example
,”
Ind. Eng. Chem. Res.
38
, No.
6
, pp.
2275
2282
.
2.
Fletcher
,
E. A.
, and
Noring
,
J. E.
,
1983
, “
High Temperature Electrothermal Processing: Zinc from Zinc Oxide
,”
Energy (Oxford)
8
, No.
4
, pp.
247
254
.
3.
Wenthorf
,
R. H.
, and
Hanneman
,
R. E.
,
1974
, “
Thermochemical Hydrogen Generation
,”
Science
185
, p.
311
311
.
4.
Chao
,
R. E.
,
1974
, “
Thermochemical Water Decompression Processes
,”
Ind. Eng. Chem. Prod. Res. Dev.
13
, No.
2
, p.
94
94
.
5.
Fletcher
,
E. A.
, and
Moen
,
R. L.
,
1977
, “
Hydrogen and Oxygen from Water
,”
Science
197
, pp.
1050
1056
.
6.
Fletcher
,
E. A.
,
1999
, “
Solarthermal and Solar Quasi-Electrolytic Processing and Separations: Zinc from Zinc Oxide as an Example
,”
Ind. Eng. Chem. Prod. Res.
38
, No.
6
, pp.
2275
2282
.
7.
Steinfeld, A., Paul Scherrer Research Institute, Switzerland, private communication.
8.
S. Glasstone, 1946, “Textbook of Physical Chemistry, 2nd Ed., Van Nostrand, New York, p. 790.
9.
Keevil
,
N. B.
,
9142
, “
Vapor Pressures of Aqueous Solutions at High Temperatures
,”
J. Am. Chem. Soc.
64
, pp.
841
850
.
10.
Fletcher
,
E. A.
,
Macdonald
,
F. J.
, and
Kunnerth
,
D.
,
1985
, “
High Temperature Solar Electrothermal Processing-II Zinc from Zinc Oxide
,”
Energy (Oxford)
10
, pp.
1255
1272
.
11.
Palumbo
,
R. D.
, and
Fletcher
,
E. A.
,
1988
, “
High Temperature Solar Electrothermal Processing-III Zinc and Zinc Oxide from 1200–1675 K Using a Non-consumable Anode
,”
Energy (Oxford)
13
, pp.
319
332
.
12.
Washburn, E. W., 1928, International Critical Tables, Vol. III, 1st ed., National Research Council of the U.S.A., p. 370.
13.
Balaj
,
J.
,
1985
, “
Water Vapor Partial Pressures and Water Activities in Potassium and Sodium Hydroxide solutions over Wide Concentration and Temperature Ranges
,”
Int. J. Hydrogen Energy
10
, pp.
233
243
.
14.
Krumgal’z
,
B. S.
, and
Mashovets
,
V. P.
,
1964
, “
Vapor Pressure of NaOH Solutions of over 45 percent Concentration at Temperatures up to 400°
,”
Zh. Prikl. Khim. (S.-Peterburg)
37
, No.
12
, pp.
2750
2752
.
15.
Dibrov
,
au;G. Z.;Mal’tsev;,
A.
, and
Mashovets
,
V. P.
,
1964
, “
Saturated Vapor Pressure of Caustic Soda and Sodium Aluminate Solutions in the 25–350° Temperature Range over a Wide Range of Concentrations
,”
Zh. Prikl. Khim. (S.-Peterburg)
37
, No.
9
, pp.
1920
1929
.
16.
Von Antropoff
,
A.
, and
Somer
,
W.
,
1926
,
Z. Phys. Chem., Stoechiom. Verwandtschaftsl.
123
, p.
461
461
.
17.
Kiyama
,
R.
, and
Kitahara
,
S.
,
1957
, “
P-V-T Relations of Aqueous Sodium Hydroxide and its Causticity at High Temperatures and High Pressures
,”
Rev. Phys. Chem. Jpn.
27
, pp.
48
53
.
18.
Van Wylen, G. J, and Sonntag, R. E., 1986, Fundamentals of Classical Thermodynamics, 3rd Ed. Wiley, New York.
19.
Kuhn, A. T., 1971, Industrial Electrochemical Processes, Elsevier, New York.
20.
Anon, Caustic Soda Handbook, portions of which were made available to me by the Occidental Chemical Corporation Delaware Development Lab, Graph 9.
21.
Bolz, R. E., 1973, CRC Handbook of Tables for Applied Engineering Science, 2nd Ed. CRC Press, Cleveland, p. 102.
You do not currently have access to this content.