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Abstract

Component development for medium pressure, medium temperature water electrolysis comprises different techniques for cathode and anode activation and small scale (4 cm**2) pretesting and bench scale (36 cm**2) long-term testing. For the latter purpose a 1 kW pilot plant was constructed and ambient pressure and enhanced pressure experiments were performed from 1000 to 3000 hours and above this limit. Most important newly developed component is a nickel net backed porous oxide ceramic diaphragm. NiTiO-3, BaZrO-3, BaTiO-3 and CaTiO-3 were tested as oxide ceramic material and BaTiO-3 and CaTiO-3 selected eventually as the most appropriate materials with respect to raw material and processing costs and chemical and mechanical long-term stability. Both materials are optimally used in the form of Ni cermets. Diaphragms are prepared of large scale (60 x 60 cm**2), of high mechanical strength and by procedures which may be easily turned into industrial practice which exhibit under operation conditions surface specific resistances not exceeding 0.25 ohms x cm**2. Own data are supported by data obtained by Sodeteg and Gaz de France. Electrode activation is performed at cathodes by electrodeposition of Zn/Ni and Zn/Ni/Co alloys. These alloys can be leached in KOH and are further activated and stabilized by in-situ addition of molybdenum. Most effective anode activation is performed by in-situ deposition of Co-xO-yOH-z. Cathodic activation yields in 150 mV improvement and anodic activation in 80 mV improvement at 1 A/cm**2 at 90 degrees C and at 1 A/cm**2. Assembly technique of bench scale electrolyser cells assuring zero-gap geometry can be put into large-scale practice easily because of its intrinsic flexibility. Economic evaluation which takes into account wear and corrosion of constructive materials reveals, that operation temperature should not exceed 160 degrees C and that under optimal conditions hydrogen production may be performed with 20 to 25 % gain in energy efficiency resulting in hydrogen costs from electrolysis which are lower by approximately 20 % than for conventional electrolysis.

Additional information

Authors: HOFMANN H, TECHNISCHE HOCHSCHULE DARMSTADT (GERMANY);LUFT G, TECHNISCHE HOCHSCHULE DARMSTADT (GERMANY);WENDT H TECHNISCHE HOCHSCHULE DARMSTADT (GERMANY), TECHNISCHE HOCHSCHULE DARMSTADT (GERMANY)
Bibliographic Reference: EUR 9406 EN (1984) MF, 81 P., BFR 120, BLOW-UP COPY BFR 405, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
Record Number: 1989122099100 / Last updated on: 1987-01-01
Category: PUBLICATION
Available languages: en
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