Faradaic electro-swing reactive adsorption for CO2 capture

Abstract

Carbon capture is one of the foremost methods for curtailing greenhouse gas emissions. Incumbent technologies are inherently inefficient due to thermal energy losses, large footprint, or degradation of sorbent material. We report a solid-state faradaic electro-swing reactive adsorption system comprising an electrochemical cell that exploits the reductive addition of CO₂ to quinones for carbon capture. The reported device is compact and flexible, obviates the need for ancillary equipment, and eliminates the parasitic energy losses by using electrochemically activated redox carriers. An electrochemical cell with a polyanthraquinone–carbon nanotube composite negative electrode captures CO₂ upon charging via the carboxylation of reduced quinones, and releases CO₂ upon discharge. The cell architecture maximizes the surface area exposed to gas, allowing for ease of stacking of the cells in a parallel passage contactor bed. We demonstrate the capture of CO₂ both in a sealed chamber and in an adsorption bed from inlet streams of CO₂ concentrations as low as 0.6% (6000 ppm) and up to 10%, at a constant CO₂ capacity with a faradaic efficiency of >90%, and a work of 40–90 kJ per mole of CO₂ captured, with great durability of electrochemical cells showing <30% loss of capacity after 7000 cylces.