(412a) Electrochemical Swing Process for Carbon Capture

Electrochemical Swing Process for Carbon Capture

The capture of carbon dioxide (CO₂) at low
concentrations (<1%) is of interest for power generation and other
industrial processes, as well as for ventilation of enclosed spaces. We report
a solid-state Faradaic electrochemical cell that exploits the reductive
addition of CO₂ to quinones for CO₂ capture.
The behavior of the cell is modulated by the introduction of CO₂ which
changes the reduction of quinone from two one-electron reductions to one
two-electron reduction. This results in a change in the potential window of the
cell and alters its charge-discharge behavior. An electrochemical cell with a
cathode, comprised of a polyanthraquinone-carbon nanotube composite, captures
CO₂ upon charging via the carboxylation of reduced quinones,
and releases CO₂ upon discharging. The novel cell architecture sandwiches
a polyvinylferrocene anode, which serves as both an electron source and sink
for the reduction and oxidation of quinones respectively, with two polyanthraquinone
cathodes, maximizing the cathode surface area exposed to gas, allowing for ease
of stacking of the cells in a device. The bench-scale prototype made
demonstrates capture of CO₂ from inlet streams of CO₂ concentrations
as low as 0.5% (5000 ppm) at a Faradaic efficiency of >90% and a work of 40-90
kJ per mole of CO₂ captured. This makes it an efficiency
improving addition to HVAC systems and cabin environmental control systems aboard
aircraft and vehicles.