Traditional thermal amine gas scrubbing technology can be energy and capital intensive owing to the enthalpy of formation of amine-CO₂ complexes and the complexity in the process integration of a stripper column. An electrochemically mediated amine regeneration cycle in traditional gas scrubbing process has been proposed for post combustion CO₂ capture.¹² We take the advantage of competitive binding of amine with electroactive species, e.g. copper, to facilitate the desorption of CO₂ and regeneration of amine in a modular electrochemical reactor.³ We investigated the energy efficiency of this electrochemical process via bulk electrolysis of the electrolyte. The charges applied in electrochemical metal dissolution are compared quantitatively to gas desorption in the electrolyte. Our controlled volume analysis validates the efficacy of the proposed cycle. We benchmarked the polarization of metal electrodes with different metal-amine complexes using a rotating disk electrode. The Tafel expression of the kinetic data assists in gauging the rate of metal dissolution/plating and provides insight into effects of various anions. We examined the quality of metal deposits at different operating conditions using XPS. The surface composition of the electrodes account for long-term stability of the electrodes. These thermo and kinetic data afford qualitative comparison of cell-level performance in the amine regeneration cycle.

References:

1. M. C. Stern, F. Simeon, H. Herzog, and T. A. Hatton, Energy Environ. Sci., 6, 2505 (2013) http://xlink.rsc.org/?DOI=c3ee41165f.
2. M. C. Stern and T. A. Hatton, RSC Adv., 4, 5906 (2014) http://xlink.rsc.org/?DOI=c3ra46774k.
3. N. Jemaa, H. J. Walls, R. D. Noble, D. E. Wedman, and C. A. Koval, AIChE J., 39, 867–875 (1993).