Abstract
This paper reports an experimental investigation into the effects of five process variables on the performance of a bench-scale continuous electrochemical reactor used in the reduction of CO2 to potassium formate, and interprets the data in terms of reactor engineering for a (speculative) industrial process for electro-reduction of CO2. The process variables: temperature, catholyte species, catholyte conductivity, cathode specific surface area and cathode thickness were studied, along with CO2 pressure and current density, in a set of factorial and parametric experiments aimed to unravel their main effects and interactions. These variables showed complex interdependent effects on the reactor performance, as measured by the current efficiency and specific energy for generation of formate (HCO −2 ). The “best” result has a formate current efficiency of 86% at a superficial current density of 1.3 kA m−2, with a product solution of 0.08 m KHCO2 and specific electrochemical energy of 260 kWh per kmole formate. The combined results indicate good prospects for process optimization that could lead to development of an industrial scale reactor.
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Abbreviations
- C :
-
catholyte composition
- CE:
-
current efficiency (dimensionless)
- E :
-
cathode potential (VSHE)
- E cell :
-
full-cell operating voltage (absolute value) (V)
- E o :
-
Standard equilibrium electrode potential (VSHE)
- GDE:
-
gas diffusion electrode
- i :
-
geometric (superficial) current density (kA m−2)
- i max :
-
maximum geometric (superficial) current density (kA m−2)
- Me:
-
cathode material
- P :
-
CO2 pressure (Bar(abs) or kPa(abs))
- P cathode :
-
cathode side pressure (kPa (abs))
- T :
-
temperature (K)
- t :
-
operating time (h)
- X 1, X 2, X 3 :
-
factorial variables defined in Tables 6, 9, 10, 13, 14, 16 and 17
- y :
-
volume fraction (i.e. mole fraction) in gas phase (dimensionless)
- τ:
-
thickness of 3D cathode (m)
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Acknowledgements
This work was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) and supported by the University of British Columbia.
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Li, H., Oloman, C. Development of a continuous reactor for the electro-reduction of carbon dioxide to formate – Part 1: Process variables. J Appl Electrochem 36, 1105–1115 (2006). https://doi.org/10.1007/s10800-006-9194-z
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DOI: https://doi.org/10.1007/s10800-006-9194-z