(127c) Modular Electrocatalytic Processing for Simultaneous Carbon Utilization and Alkane Conversion

U.S. coal plants play an important role 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. Further, high purity CO (>99.99%) is used in electronics manufacturing. Industrial bulk CO is produced by separating CO from syngas (containing H₂) generated via steam methane reforming (SMR) using natural gas as the feedstock. The U.S. consumes approximately 300-400 MMscf/day of CO with an annual market value of nearly $2 billion.

Various separation technologies are used including cryogenic separation (i.e. cold box), pressure swing adsorption (PSA), membrane separation, and ammonium salt solution absorption. However, these processes are complex and capital intensive requiring larger production facilities. Although low temperature solution-based CO₂ electrolyzers are being studied, solid oxide electrolyzer cells (SOECs) operating at an elevated temperature provide greater cell/electrolysis efficiencies. The ability to utilize solid oxide electrolyzer cell (SOEC) 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 and ethane contained in wet natural gas into valuable products. OHIO’s SOEC process seeks to advance beyond these previous electrochemical CO₂ reduction concepts by utilizing intermediate-temperature operation (650-750°C) and utilizing an innovative cell design which incorporates oxidative dehydrogenation (ODH) of C₂₊ alkanes. Several transition metals and mixed metal oxides have been identified as suitable for solid oxide electrolysis of CO₂ and ODH of C₂₊ alkanes using first principles simulations [4] and experimental trials, respectively. This presentation will discuss recent results from OHIO’s carbon utilization project including experimental results and process simulations.

[1] F. Bidrawn, G. Kim, G. Corre, J. T. S. Irvine, J. M. Vohs, and R. J. Gorte, “Efficient Reduction of CO2 in a Solid Oxide Electrolyzer,” Electrochem. Solid-State Lett., vol. 11, no. 9, pp. B167–B170, Sep. 2008.

[2] L. Zhang, S. Hu, X. Zhu, and W. Yang, “Electrochemical reduction of CO2 in solid oxide electrolysis cells,” J. Energy Chem., vol. 26, no. 4, pp. 593–601, Jul. 2017.

[3] Y. Xie, J. Xiao, D. Liu, J. Liu, and C. Yang, “Electrolysis of Carbon Dioxide in a Solid Oxide Electrolyzer with Silver-Gadolinium-Doped Ceria Cathode,” J. Electrochem. Soc., vol. 162, no. 4, pp. F397–F402, Jan. 2015.

[4] X.-K. Gu, J. S. A. Carneiro, and E. Nikolla, “First-Principles Study of High Temperature CO2 Electrolysis on Transition Metal Electrocatalysts,” Ind. Eng. Chem. Res., vol. 56, no. 21, pp. 6155–6163, May 2017