Rapid Steam-Assisted Temperature Swing Adsorption for Direct Air Capture Using a Rotary Adsorber

Direct air capture (DAC) of CO₂ is a key solution for balancing hard-to-abate carbon emissions and plays a crucial role in achieving net zero. Common DAC methods typically employ fixed bed reactors packed with granular adsorbents, which suffer from high gas pressure drop, poor heat and mass transfer, and long cycle durations. Additionally, multiple reactors are required for continuous operation, resulting in bulky systems and complex control. This study proposes a novel rotary adsorber-based DAC strategy, where powdered adsorbents are shaped into structured adsorbents, enabling rapid carbon capture in a single reactor via a steam-assisted temperature swing adsorption cycle. A ton-scale-potential DAC prototype was constructed. Experimental results exhibit a CO₂ capture rate of 50%-85%, producing high-purity CO₂ (>90%) with remarkable CO₂ productivity of 0.235-0.352 kg_CO2/kg_adsorbent/day. A mathematical model was developed to reveal the dynamic variations of key parameters within the rotor. On this basis, optimization strategies were proposed, showing that by implementing heat recovery, the total energy consumption of carbon capture could be reduced to 7.41-9.64 MJ/kg_CO2. Further enhancement of the adsorbent performance could lower the energy consumption to 2.50-3.14 MJ/kg_CO2. These findings demonstrate the rotary adsorber's outstanding carbon capture capability, offering an efficient and attractive DAC solution.