(600h) Simultaneous Carbon Utilization and Alkane Conversion Using Solid Oxide Electrolytic Technology

U.S. coal plants have been essential in providing the U.S. with reliable low-cost electricity and will continue to be relied upon as base-load for the foreseeable future. Cost-effectively reducing carbon emissions from the existing U.S. coal-fired generation fleet is necessary for these assets to continue to play an important role in a carbon restricted economy. Carbon utilization is a methodology which could help offset the costs of carbon capture by converting the product CO₂ into valuable products. Carbon monoxide (CO) is an important industrial gas used in manufacturing bulk chemical precursors such as phosgene, commodity materials via carbonylation including aldehydes, ketones, carboxylic acids, anhydrides, esters, amides, imides, carbonates, ureas, and isocynanates. Industrial bulk CO is produced from separating CO from syngas (CO + H₂) generated from the steam methane reforming process.

Separation technologies such as cryogenic separation (i.e. cold box), pressure swing adsorption (PSA), membrane separation, and ammonium salt solution absorption are currently used to extract CO. Understandably, these processes are complex requiring large production facilities and huge capital investment. CO₂ electrolysis is a promising solution with several low-temperature solution based electrolyzers being studied. However, solid oxide electrolyzer cells (SOECs) operating at an elevated temperature provide greater cell/electrolysis efficiencies and the ability to use this technology to electrochemically convert CO₂ into CO/O₂ or CO₂/H₂O into syngas/O₂ has been shown over recent years [1–3].

Ohio University (OHIO) with funding from the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) Carbon Use and Reuse Program (DE-FE0031709) is developing a process that utilizes solid oxide electrolysis to simultaneously convert CO₂ into valuable products. As a preliminary study, the electrochemical conversion of CO₂ reduction to CO will be evaluated using an SOEC with H₂ as the anode fuel. Nickel and (La_0.80Sr_0.20)_0.95MnO_3-δ based electrodes, widely used in solid oxide fuel cells (SOFCs) [4] were chosen as the anode and cathode electrodes, respectively, for the SOEC used in this study. This presentation will discuss these results including experimental performance and process simulations as part of OHIO’s carbon utilization project.

[1] F. Bidrawn, G. Kim, G. Corre, J.T.S. Irvine, J.M. Vohs, R.J. Gorte, Efficient Reduction of CO2 in a Solid Oxide Electrolyzer, Electrochem. Solid-State Lett. 11 (2008) B167.

[2] L. Zhang, S. Hu, X. Zhu, W. Yang, Electrochemical reduction of CO2 in solid oxide electrolysis cells, Journal of Energy Chemistry. 26 (2017) 593–601.

[3] Y. Xie, J. Xiao, D. Liu, J. Liu, C. Yang, Electrolysis of Carbon Dioxide in a Solid Oxide Electrolyzer with Silver-Gadolinium-Doped Ceria Cathode, J. Electrochem. Soc. 162 (2015) F397.

[4] R. Mark Ormerod, Solid oxide fuel cells, Chemical Society Reviews. 32 (2003) 17–28.