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Syngas (CO-H2) production using high temperature micro-tubular solid oxide electrolysers
- Source :
- Electrochimica Acta. :565-577
- Publisher :
- Z. Published by Elsevier Ltd.
-
Abstract
- CO 2 and/or H 2 O were reduced to CO/H 2 in micro-tubular solid oxide electrolysers with yttria-stabilized zirconia (YSZ) electrolyte, Ni-YSZ cermet cathode and strontium(II)-doped lanthanum manganite (LSM) oxygen-evolving anode. At 822 °C, the kinetics of CO 2 reduction were slower (ca. −0.49 A cm −2 at 1.8 V) than H 2 O reduction or co-reduction of CO 2 and H 2 O, which were comparable (ca. −0.83 to −0.77 A cm −2 at 1.8 V). Performances were improved (−0.85 and −1.1 A cm −2 for CO 2 and H 2 O electrolysis, respectively) by substituting the silver current collector with nickel and avoiding blockage of entrances to pores on the inner lumen of micro-tubes induced by silver paste applied previously to decrease contact losses. The change in current collector materials increased ohmic potential losses due to substituting the lower resistance Ag with Ni wire, but decreased electrode polarization losses by 80–93%. For co-electrolysis of CO 2 and H 2 O, isotopically-labelled C 18 O 2 was used to try to distinguish between direct cathodic reduction of CO 2 and its Ni-catalysed chemical reaction with hydrogen from reduction of steam. Unfortunately, oxygen was exchanged between C 18 O 2 and H 2 16 O, enriching oxygen-18 in the steam and substituting oxygen-16 in the carbon dioxide, so the anode off-gas isotopic fractions were meaningless. This occurred even in alumina and YSZ tubes without the micro-tubular reactor, i.e. in the absence of Ni catalyst, though not in quartz tubes. Unfortunately, larger differences between the thermal expansion coefficients of quartz and YSZ precluded using a quartz tube to house the micro-tubular reactor. However, the kinetic results, CO/H 2 yields from off-gas analysis, diffusional considerations and model predictions of reactant and product gas adsorption on Ni suggested that syngas should be produced by electrochemical reduction of steam to H 2 , followed by its Ni-catalysed chemical reaction with CO 2 .
- Subjects :
- Electrolysis
Hydrogen
General Chemical Engineering
Inorganic chemistry
Oxide
chemistry.chemical_element
Electrochemistry
Cathode
law.invention
Anode
chemistry.chemical_compound
solid oxide electrolyser
CO2/H2O reduction
oxygen-18 isotopic labelling
chemistry
law
micro-tubular
Chemical Engineering(all)
Yttria-stabilized zirconia
Syngas
(reverse) water gas shift reaction
Subjects
Details
- Language :
- English
- ISSN :
- 00134686
- Database :
- OpenAIRE
- Journal :
- Electrochimica Acta
- Accession number :
- edsair.doi.dedup.....5ffe149a34a3c281239d56d8658382cd
- Full Text :
- https://doi.org/10.1016/j.electacta.2015.07.062