Operating the nickel electrode with hydrogen-lean gases in the molten carbonate electrolysis cell (MCEC)
2016 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 41, 18692-18698 p.Article in journal (Refereed) Published
If a molten carbonate electrolysis cell (MCEC) is applied for fuel gas production it is important to know the polarization of the nickel electrode when operated at low concentration of hydrogen. Thus, the electrochemical performance of the Ni electrode was investigated under hydrogen-lean gases containing 1/24.5/24.5/50%, 1/49.5/24.5/25%, 1/24.5/49.5/25% and 1/49.5/49.5/0% H-2/CO2/H2O/N-2 in the temperature range of 600-650 degrees C and was then compared to the reference case with 25/25/25/25% H-2/CO2/H2O/N-2. The electrochemical measurements included polarization curve coupled with current interrupt, and electrochemical impedance spectroscopy. Polarization resistances of the Ni electrode obtained by the two different techniques agreed well. For the inlet gases containing low amounts of hydrogen the Ni electrode exhibited higher polarization losses than when using the reference case in the electrolysis cell. The electrochemical impedance measurements showed that both charge-transfer and mass-transfer polarizations were higher for hydrogen-lean gases at all measured temperatures. Except under the condition with 1/49.5/49.5% H-2/CO2/H2O at 650 degrees C, the Ni electrode exhibited lower mass-transfer polarization when compared to the reference case. Furthermore, the mass-transfer polarization was strongly dependent on temperature under H-2-lean gases, differing from the reference case when the temperature has almost no effect on mass-transfer polarization. The activation energy for hydrogen production was calculated to be in the range of 69 -138 kJ mol(-1) under all measured gases, indicating that the Ni electrode is under kinetic and/or mixed control in the MCEC.
Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 41, no 41, 18692-18698 p.
Hydrogen-lean gases, Molten carbonate electrolysis cell, Ni electrode, Polarization
Other Chemical Engineering
IdentifiersURN: urn:nbn:se:kth:diva-196592DOI: 10.1016/j.lihydene.2016.06.037ISI: 000385598300038ScopusID: 2-s2.0-84993508166OAI: oai:DiVA.org:kth-196592DiVA: diva2:1047700
3rd International Workshop on Molten Carbonates and Related Topics (IWMC), JUN 11-13, 2015, NE Univ, Shenyang, Peoples R China
QC 201611182016-11-182016-11-172016-11-18Bibliographically approved