(304a) Development of a Low-Cost Non-Amine Sorbent-Based Technology for Direct Air Capture of CO2

Worldwide emissions of CO₂ now exceed 40 Gt/yr annually, accelerating the greenhouse gas effect that has already increased global median temperature by 1°C. Negative emissions technologies (NET) must be rapidly developed and deployed in order to remove CO₂ from the atmosphere and limit the global temperature rise to <2°C. Direct air capture (DAC) of CO₂ is a promising NET, but the cost of capturing CO₂ via DAC remains too high ($300–1,500/tonne CO₂) to be a viable commercial solution. For sorbent-based DAC systems, the major cost contributor is the energy required to release CO₂ and regenerate the sorbent.

Susteon Inc. has developed a platform technology for DAC based on low-cost supported alkali-based sorbents with high CO₂ capture rate and capacity. Compared to conventional DAC using amine sorbents supported on high surface area solids (e.g., metal-organic frameworks), the alkali-based DAC sorbents developed by Susteon are capable of removing >70% of CO₂ from ambient air (~415 ppm) at an order-of-magnitude greater rate and releasing CO₂ under mild regeneration conditions. This enables significantly lower energy requirement for regeneration and allowing for the use of renewable electricity to provide low-temperature heat for desorption. Moreover, the presence of water (from the moisture in air) favorably impacts the DAC sorbent performance, representing another advantage over amine sorbents. Extensive experimental work demonstrates excellent sorbent regenerability and long-term, multi-cycle performance.

Susteon has explored multiple potential avenues for the DAC platform technology, including (i) the development of a novel reactor system to selectively heat the alkali adsorbent layer to facilitate CO₂ desorption while minimizing energy costs; and (ii) the development of a dual-functional material (DFM) to sequentially perform DAC and utilize the captured CO₂in situ to produce renewable natural gas (RNG). Altogether, the technologies developed by Susteon will significantly lower the overall cost of DAC.