Experimental Validation of Two‐Dimensional H₂O and CO₂ Co‐Electrolysis Modeling

Abstract

This work details an in‐house 2D electrochemical and thermal model of solid oxide electrolysis cell (SOEC) dedicated to the simultaneous electrolysis of steam and carbon dioxide. The apparent exchange current densities for both H2O and CO2 electrochemical reductions have been fitted on single electrolysis polarization curves obtained on a standard cathode supported cell (CSC). By using these values, predictive simulations have been performed in a co‐electrolysis mode. The results have been compared to experimental data obtained in the same conditions. A good agreement is found between the simulated points and the experimental polarization curves, meaning that the model stands to predict accurately the SOEC response in co‐electrolysis mode. Simulations have been performed to investigate co‐electrolysis mechanisms in terms of partial pressures, current densities, and overpotentials distributions along the cell. The relative influence of both water gas shift (WGS) reaction and CO2 electrolysis on the global CO production is also discussed.

Hydrogen production by high-temperature steam electrolysis

“…Performance in co-electrolysis mode is close to that in pure steam electrolysis, which validates this operation mode. Gas composition at the outlet has been measured by gas microchromatography and was found to be as expected (Aicart, Laurencin, Petitjean, & Dessemond, 2014). Thus, the composition of the gas produced can be tailored to be exactly what is requested for a catalytic reactor that produces synfuel Reytier, Di Iorio, Petit, et al, 2014).…”

Accurate predictions of H2O and CO2 co-electrolysis outlet compositions in operation

“…The experimental setup, sealing process and cermet reduction as well as the optimization of contact resistance before electrical measurements are described in details elsewhere [28]. Both anode and cathode gases are delivered to the cell from the center of the housing according to a radial coflow configuration.…”

“…This corresponds to gas conversion rates up to 64%. Additionally, the WGS reaction kinetics, implemented in the model [28] was validated by gas analyses at OCV. Finally, the evolution of the outlet composition in steady state operation was investigated over 288 h.…”

“…In a previous study [28,35], an in-house multiphysics 2D model devoted to co-electrolysis was presented and validated by comparing simulated and experimental polarization curves. To take into account the competition between the direct reduction of steam and the electrolysis of CO 2 , a "surface ratio" parameter was introduced [35].…”

“…To take into account the competition between the direct reduction of steam and the electrolysis of CO 2 , a "surface ratio" parameter was introduced [35]. By using the coelectrolysis modeling tool, the influence of the reverse WGS reaction over global CO production was also investigated.…”