A model for gas phase mass transport on the porous nickel electrode in the molten carbonate electrolysis cell
(English)Manuscript (preprint) (Other academic)
A one-dimensional model based on the Maxwell-Stefan diffusion equations was applied to evaluate the effect of the reverse water-gas shift reaction and the influence of the gas phase mass transport on the performance of the porous nickel electrode in the molten carbonate electrolysis cell. The concentration gradients in the current collector are larger than in the electrode for the inlet gases not in equilibrium, due to the shift reaction taking place in the electrode. When the humidified gas compositions enter the current collector, the decrease of the shift reaction rate increases the electrode performance. The model well describes the polarization behavior of the Ni electrode in the electrolysis cell when the inlet gases have low contents of hydrogen. The mass-transfer limitations at low contents of water and carbon dioxide are captured in the model, but the effect on the electrode polarization, especially of carbon dioxide, is overestimated. Despite an overestimation in the calculations, the experimental data and the modeling results are still consistent in that carbon dioxide has a stronger effect on the gas phase mass transport than other components, i.e. water and hydrogen.
IdentifiersURN: urn:nbn:se:kth:diva-185432OAI: oai:DiVA.org:kth-185432DiVA: diva2:920577
QC 201604192016-04-182016-04-182016-04-20Bibliographically approved