Mechanism of Chlorine-Mediated Electrochemical Ethylene Oxidation in Saline Water

Minju Chung, Kyoungsuk Jin, Joy Shuang Zeng, Karthish Manthiram

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Chlorine as a redox mediator allows for the selective oxidation of ethylene to 2-chloroethanol, which converts to ethylene oxide in alkaline aqueous electrolyte. This strategy utilizes abundant saline water as an electrolyte and source of oxygen atoms for functionalization. We present a mechanistic study of ethylene oxidation in saline water using cobalt oxide nanoparticle catalysts. Electrochemical kinetic analysis and in situ X-ray absorption spectroscopy suggest that the resting state of the catalyst and the rate-determining step differ for the chlorine evolution reaction in the presence and absence of ethylene. In 0.6 M NaCl pH 8 electrolyte, which resembles seawater, the average current density was ∼60 mA/cm2 with a Faradaic efficiency of ∼41% toward ethylene functionalization. The use of synthetic and natural seawater achieved Faradaic efficiencies above 70%, while the partial current toward the product remained invariant. Further conversion of the initial product 2-chloroethanol into ethylene glycol was also demonstrated. We present a broader vision of harnessing saline water in electrochemical functionalization of organic molecules and coproduction of hydrogen.

Original languageEnglish
Pages (from-to)14015-14023
Number of pages9
JournalACS Catalysis
Volume10
Issue number23
DOIs
Publication statusPublished - 2020 Dec 4
Externally publishedYes

Keywords

  • chlorine-mediated
  • electrochemical ethylene oxidation
  • ethylene oxide
  • mechanistic studies
  • seawater utilization

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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