A cyclic electrochemical strategy to produce acetylene from CO2, CH4, or alternative carbon sources

Joshua M. McEnaney, Brian A. Rohr, Adam C. Nielander, Aayush R. Singh, Laurie A. King, Jens K. Nørskov*, Thomas F. Jaramillo

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Electrochemical transformation of potent greenhouse gases such as COand CHto produce useful carbon-based products is a highly desirable sustainability goal. However, selectivity challenges remain in aqueous electrochemical processes as selective COreduction to desired products is difficult and electrochemical CHoxidation often proceeds at very low rates. The formation of C-C coupled products in these fields is particularly desirable as this provides a path for the production of high-value fuels and chemicals. We have developed a cyclic electrochemical strategy which can produce acetylene, a C-C coupled product, from such carbon sources and water, with favorable current density and selectivity. This strategy is exemplified with a lithium-mediated cycle: an active Lisurface is electrochemically generated from LiOH, the newly formed Lireacts with a carbon source to form Li2C2, and Li2Cis hydrolyzed to form acetylene and regenerate LiOH. We demonstrate this process primarily using COgas, achieving a current efficiency of 15% to acetylene (which represents 82% of the maximum based on stoichiometric production of oxygenated byproducts, e.g.LiCOand/or Li2O), as verified by gas chromatography and Fourier transform infrared radiation studies. We also explore CH4, CO, and C as alternative precursors in the acetylene synthesis. Notably, the use of graphitic carbon at higher temperatures resulted in over 55% current efficiency to acetylene, with opportunity for further optimization. Importantly, this cycling method avoids the formation of common side products observed during aqueous electrochemical COand CHredox reactions, such as H2, CO, HCO2, or CO2. Theoretical considerations elucidate the feasibility and general applicability of this cycle and the process steps have been characterized with specific electrochemical and materials chemistry techniques. The continued development of this strategy may lead to a viable route for the sustainable production of C-C coupled carbon fuels and chemicals.

Original languageEnglish
JournalSustainable Energy and Fuels
Volume4
Issue number6
Pages (from-to)2752-2759
ISSN2398-4902
DOIs
Publication statusPublished - 2020

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