Proton-conducting Electrolysis Cell Research Articles

Tuning the product selectivity of CO2/H2O co-electrolysis using CeO2-modified proton-conducting electrolysis cells

This work demonstrates surface engineering as an effective strategy to modulate the surface adsorption characteristics of reaction intermediates, hence promoting CO2/H2O co-electrolysis to produce CH4using PCECs.

Numerical Study on Biogas Refining System Combined with Proton-Conducting Solid Oxide Electrolyzer

Biogas is one of the most globally distributed carbon-neutral fuels to be used as a local biomass energy source for local society energy demand. However, since the biogas from organic waste is typically a mixture of 60% methane and 40% carbon dioxide, the biogas has a lower energy density compared with coal, oil, LNG, and etc. In this study, biogas refining system including methanation reactor and proton-conducting electrolysis cell has been proposed and investigated based on the numerical calculation including mass and heat balance analysis. Using this system, hydrogen and CO2 derived from electrolysis cell and biogas, respectively, will be converted into methane via methanation reaction. Carbon deposition is a well-known problem to be resolved when carbon-rich gas is supplied to the cell cathode. Based on the calculation results, the gas humidification was found to be necessary to prevent carbon deposition at the cathode inlet. However, carbon deposition was predicted to still occur at the cathode outlet even with the gas humidification when a conventional oxide-ion conducting electrolyte is applied to the electrolysis cell due to the enhanced carbon activity caused by oxide-ion transport from the cathode to the anode. In the case of the proton-conducting electrolyte, proton transport from the anode to the cathode was found to mainly promote reverse water-gas shift reaction and methanation reaction without any carbon deposition. Even though the calculation results should be verified by comparing with experimental results, the numerical study suggested that the biogas refining system combined with p-SOEC is a promising technology for generating carbon-neutral methane with a strongly suppressed risk of carbon deposition.

Numerical Study on Biogas Refining System Combined with Proton-Conducting Solid Oxide Electrolyzer

Biogas refining system including methanation reactor and proton-conducting electrolysis cell has been proposed and investigated based on the simulation including mass and heat balance analysis. Based on the calculation results, carbon deposition was predicted to still occur at the cathode outlet even with the gas humidification when a conventional oxide-ion conducting electrolyte is applied to the electrolysis cell due to the enhanced carbon activity caused by oxide-ion transport from the cathode to the anode. In the case of the proton-conducting electrolyte applied solid oxide electrolysis cell, proton transport from the anode to the cathode was found to mainly promote reverse water-gas shift reaction and methanation reaction without any carbon deposition. Even though the calculation results should be verified by comparing with experimental results, the numerical study suggested that the biogas refining system combined with p-SOEC is a promising technology for generating carbon-neutral methane with a strongly suppressed risk of carbon deposition.

Infiltration of Metal Catalysts for NH3 Synthesis in Protonic Ceramic Cells

The electrochemical synthesis of green NH3 representes a promising alternative to the conventional Haber-Bosch process, which currently relies on H2 mainly sourced from fossil fuels. Additionally, it compensates for the thermodynamic limitations of the ammonia synthesis reaction via the utilization of high pressures of 150-300 bar, resulting in high energy consumption. The prospect of solid state ammonia synthesis (SSAS) in proton conducting electrolysis cells (PCEC) has been the subject of increased interest recently [1]. It features steam in place of H2 as a reactant and the electrochemical activation of N2 at the hydrogen electrode (cathode) through the use of a catalyst. Possible candidates are metallic Ru or Fe, analogous to the thermocatalytic Haber-Bosch process.The implementation of the catalyst in the electrochemical cell is critical to the performance of the system. In order to augment the kinetics, high amounts of catalyst near the electrode-electrolyte interface are desired. Therefore, the microstructure of the electrode is of primary interest, as the void fraction of the layer must be large enough to enable a well-distributed deposition of catalyst particles. This may be achieved via the use of a pore-former, e.g. graphite powder, in the wet-route elaboration of the hydrogen electrode (see Fig. 1). However, modifications must not decrease the mechanical properties of the layer.The effect of various parameters (sintering conditions, thickness of the electrode layer, effect of additives to enhance wettability) on the final electrode structure were investigated, as well as the influence of the infiltration protocol (evacuation time, number of infiltration steps, drying procedure). The findings along with preliminary electrochemical characterizations will be discussed.[1] V. Kyriakou, I. Garagounis, E. Vasileiou, A. Vourros, M. Stoukides, Progress in the Electrochemical Synthesis of Ammonia, Catalysis Today, 286 (2017) 2-13. Figure 1

Electrochemical Ammonia Synthesis Using Mixed Protonic-Electronic Conducting Cathodes with Exsolved Ru-Nanoparticles in Proton Conducting Electrolysis Cells

Electrochemical synthesis of ammonia was performed at 500°C using a mixed protonic-electronic conducting cathode, Ru-doped BaCe0.9Y0.1O3 (BCYR) in a proton-conducting electrolysis cell (PCEC) using a BaCe0.9Y0.1O3 (BCY) electrolyte. Ru nanoparticles were formed in situ on the surface of the BCYR particles after a heat-treatment in a reducing atmosphere, as determined by TEM and XPS measurements. The BCYR cathode exhibited activity toward electrochemical ammonia formation, which indicates that the Ru nanoparticles were active sites for the electrochemical synthesis of ammonia. We found that altering the reduction temperature could be used to control the exsolved Ru-nanoparticle size; decreasing the Ru particle size contributes to an improvement in electrochemical ammonia formation due to an increased triple-phase-boundary active length. The ammonia formation rate per amount of exsolved Ru nanoparticles achieved with BCYR was higher than that achieved with a previously reported Ru-doped La1-xSrxTiO3 (LSTR) cathode. Our results suggest that the mixed protonic-electronic conduction in the BCYR cathode may contribute to the increased Ru-nanoparticles activity toward electrochemical ammonia synthesis. The dependence of the ammonia formation rate on the applied voltage and the reaction mechanism were discussed based on kinetic analysis.