Activated Carbon Fiber Felt Composites for the Direct Air Capture of Carbon Dioxide

Negative emission technologies to mitigate climate change require innovative solutions for the direct air capture (DAC) of CO2 from the atmosphere. K2CO3 readily reacts with CO2 to form KHCO3; however, bulk K2CO3 suffers from very slow sorption kinetics. By incorporating K2CO3 into activated carbon (AC) fiber felts, the sorption kinetics were significantly improved by increasing the surface area of K2CO3 in contact with air. The AC‐K2CO3 fiber composite felts are flexible, cheap, easy to manufacture, chemically stable, and show excellent DAC capacity and (de)sorption rates, with stable performance up to ten cycles. Cyclic testing was demonstrated with 4 h sorption and 0.5 h desorption intervals. The best composite felts collected an average of 478 µmol of CO2 per gram of composite during 4 h of exposure to ambient air (19% relative humidity) that had a CO2 concentration of 400‐450 ppm after regeneration at 125 °C in an air furnace. An increase in the dew point temperature from 0 °C to 12 °C decreased sorption performance of the composite felts by 40%.