Autothermal Sorbent Design

Direct air capture AC separates carbon dioxide from air using liquid or solid sorbents and can support carbon removal for emissions that cannot be avoided. However, DAC adoption has been limited by reported capital costs exceeding $200 per tonne of carbon dioxide and energy costs exceeding 500 MJ per tonne of carbon dioxide. Sorbent design involves competing requirements: carbon dioxide capacity, water-sorption behavior, and thermomechanical stability can be difficult to optimize simultaneously. Existing approaches may also require supporting structures, while DAC systems can depend on major thermal waste streams.

 

Researchers at Arizona State University have developed a novel autothermal sorbent design for direct air capture of carbon dioxide. This approach uses polymer architectures with distinct microdomains that separate mechanical reinforcement from carbon dioxide and water sorption functions. It combines moisture-swing carbon dioxide/water co-sorption sites with thermally active carbon dioxide sorption sites, with the aim of coupling hydration- and heat-mediated release mechanisms. The material design is intended to tune water-sorption behavior and carbon dioxide binding while maintaining thermomechanical stability during sorption and desorption cycling. The proposed sorbents may be formed in thin film, particle, or fiber formats to provide surface-area morphologies relevant to heat and mass transfer during regeneration.