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

Area of Science:

• Environmental Science
• Chemical Engineering
• Materials Science

Background:

• Direct air capture (DAC) is vital for mitigating hard-to-abate emissions and achieving net zero goals.
• Conventional DAC methods using fixed beds have limitations, including high pressure drop, inefficient heat/mass transfer, and lengthy cycles.
• Current DAC systems often require multiple reactors, leading to complex operations and large footprints.

Purpose of the Study:

• To develop and evaluate a novel rotary adsorber-based direct air capture (DAC) strategy.
• To enable rapid CO2 capture in a single reactor using structured adsorbents and steam-assisted temperature swing adsorption.
• To assess the performance and energy efficiency of a ton-scale-potential DAC prototype.

Main Methods:

• Development of a rotary adsorber system utilizing powdered adsorbents shaped into structured forms.
• Implementation of a steam-assisted temperature swing adsorption (TSA) cycle for CO2 capture and release.
• Construction and testing of a ton-scale-potential DAC prototype.
• Mathematical modeling to analyze dynamic parameters within the rotary adsorber.

Main Results:

• Achieved a CO2 capture rate of 50%-85% with high-purity CO2 (>90%).
• Demonstrated significant CO2 productivity ranging from 0.235-0.352 kgCO2/kgadsorbent/day.
• Mathematical modeling provided insights into rotor dynamics for optimization.
• Proposed optimization strategies, including heat recovery, to reduce energy consumption to 7.41-9.64 MJ/kgCO2.

Conclusions:

• The rotary adsorber-based DAC offers a highly efficient and compact solution compared to traditional methods.
• Optimized energy consumption can be further reduced to 2.50-3.14 MJ/kgCO2 with enhanced adsorbent performance.
• This technology presents a viable and attractive approach for large-scale direct air capture of carbon dioxide.