Solar thermal swing adsorption on porous carbon monoliths for high-performance CO₂ capture

Utilizing solar energy for sorbent regeneration during the CO₂ swing adsorption process could potentially reduce CO₂ capture costs. This study describes a new technique—solar thermal swing adsorption (STSA) for CO₂ capture based on application of intermittent illumination onto porous carbon monolith (PCM) sorbents during the CO₂ capture process. This allows CO₂ to be selectively adsorbed on the sorbents during the light-off periods and thereafter released during the light-on periods due to the solar thermal effect. The freestanding and mechanically strong PCMs have rich ultramicropores with narrow pore size distributions, displaying relatively high CO₂ adsorption capacity and high CO₂/N₂ selectivity. Given the high CO₂ capture performance, high solar thermal conversion efficiency, and high thermal conductivity, the PCM sorbents could achieve high CO₂ capture rate of up to 0.226 kg ${}_{\mathrm{C}{\mathrm{O}}_2}$·kg_carbon⁻¹·h⁻¹ from a gas mixture of 20 vol.% CO₂/80 vol.% N₂ under STSA conditions with a light intensity of 1000 W·m⁻². In addition, the combination of STSA with the conventional vacuum swing adsorption technique further increases the CO₂ working capacity.