Feasibility Study of Combining Direct Air Capture of CO2 and Methanation at Isothermal Conditions with Dual Function Materials

Abstract

The feasibility of employing dual function materials (DFM) for combined direct air capture (DAC) of CO2 followed by methanation is reported. Originally developed for point-source (i.e. power plant effluent) CO2 capture, the DFM is comprised of an alkaline adsorbent and catalytic metal supported on the same Al2O3 carrier. The DFM allows the capture and conversion of CO2 to occur using a single material and reactor at one temperature. Successful cyclic capture and methanation of 400 ppm CO2 at isothermal conditions (320 °C) has been demonstrated. Desorption of CO2 from the DFM at isothermal conditions was also explored; however, hydrogenation of the adsorbed CO2 more efficiently regenerates capture sites, enabling the DFM to maintain high CO2 capture capacity and produce methane through multiple cycles. Cyclic operation with the DFM is also possible in the presence of moisture, proving that DFM has further potential to be used for DAC scenarios.