Title: Advances in the HCl gas-phase electrolysis employing an oxygen-depolarized cathode

Abstract

The electrolysis of HCl to form Cl₂ is an integral part of the production of polycarbonates and polyurethanes. In recent years, the direct gas-phase electrolysis was shown to be significantly more efficient than the current state-of-the-art process based on the oxidation of hydrochloric acid. Still, three phenomena significantly limit the performance and industrial applicability of this process and have so far only been investigated theoretically. Firstly, a limiting behavior in the HCl oxidation reaction was observed, which seems to be of purely kinetic origin. Secondly, also in the full-cell employing an oxygen depolarized cathode, a limiting behavior was detected, which however appears to have a different origin. Lastly, the performance of the oxygen reduction is significantly reduced in comparison to classical H₂ PEM fuel cells. The present work utilizes a combined experimental and theoretical approach to confirm that the HCl oxidation is purely reaction limited while the limiting behavior in the full-cell system employing an oxygen depolarized cathode is caused by flooding at low reactor temperatures and, lastly, that the reduced performance of the oxygen reduction reaction is a consequence of significant HCl crossover that can be mitigated by means of increased cathode humidification. These insights are furthermore used tomore » operate the HCl gas phase electrolyzer employing an oxygen depolarized cathode at current densities of more than 5000 A/m² for the first time, while also substituting the previously employed platinum based cathode catalyst with Rh_xS_y, decreasing the impact of HCl crossover and allowing for the lowest so far measured cell potentials over a wide interval of current densities.« less

Authors:

Bechtel, Simon; Crothers, Andrew R. ;

• Search DOE PAGES for author "Crothers, Andrew R."
• Search DOE PAGES for ORCID "0000-0003-4466-1057"

Weber, Adam Z. ;

• Search DOE PAGES for author "Weber, Adam Z."
• Search DOE PAGES for ORCID "0000-0002-7749-1624"

Kunz, Ulrich; Turek, Thomas ;

• Search DOE PAGES for author "Turek, Thomas"
• Search DOE PAGES for ORCID "0000-0002-7415-1966"

Vidaković-Koch, Tanja ;

• Search DOE PAGES for author "Vidaković-Koch, Tanja"
• Search DOE PAGES for ORCID "0000-0003-3896-3585"

Sundmacher, Kai

Publication Date:

Fri Jan 01 00:00:00 EST 2021

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1809263

Alternate Identifier(s):

OSTI ID: 1763704

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Published Article

Journal Name:

Electrochimica Acta

Additional Journal Information:

Journal Name: Electrochimica Acta Journal Volume: 365 Journal Issue: C; Journal ID: ISSN 0013-4686

Publisher:

Elsevier

Country of Publication:

United Kingdom

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Gas phase electrolysis; Chlorine; Electrochemical process; HCl oxidation; Limiting current