An Electrochemically-mediated Gas Separation Process for Carbon Abatement

Abstract

This work describes a promising alternative to conventional thermal processes for absorber/desorber processing of for removal of CO[subscript 2] from flue gas streams at fossil fuel fired power plants. Our electrochemically-mediated amine regeneration (EMAR) process offers the advantages of an electrical system coupled with the desirable high output purities typical of amine sorbents that are difficult to achieve with most electric systems such as pressure-swing sorption, membrane separation, and oxy-fuel combustion. Preliminary experimental results are presented that demonstrate the feasibility of using ethylenediamine as the CO[subscript 2] sorbent and copper electro-cycling to isothermally modulate the amine affinity for CO[subscript 2]. Cupric ions entirely deactivate ethylenediamine at a ratio of 2:1 diamine to copper. Open-circuit potential measurements at 50°C indicate the required energy to desorb CO[subscript 2] and regenerate the ethylenediamine is 18 kJ/mole CO[subscript 2] under open-circuit conditions. Kinetic over-potentials are sufficiently low to ensure acceptable energy losses. Lower energies can be achieved by increasing the temperature or by changing the amine.