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 kgCO2/kgadsorbent/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/kgCO2. Further enhancement of the adsorbent performance could lower the energy consumption to 2.50-3.14 MJ/kgCO2. These findings demonstrate the rotary adsorber's outstanding carbon capture capability, offering an efficient and attractive DAC solution.