Phosphonium-Based Anion Exchange Polymers for Moisture-Swing Direct Air Capture of CO2

Rising atmospheric carbon dioxide (CO₂) levels and the limitations of conventional capture methods such as high energy consumption, thermal instability, and costly regeneration have created a need for low-energy, durable, and efficient sorbents. Moisture-swing CO₂ capture offers a promising alternative, enabling CO₂ absorption under dry conditions and desorption upon exposure to humidity without requiring significant thermal input. However, existing anion exchange materials that are based on quaternary ammonium cations, often suffer from reduced stability and performance over repeated wet and dry cycles.

 

Researchers at Arizona State University have developed phosphonium-based anion exchange polymers specifically engineered for moisture-swing direct air capture (DAC) of CO₂. These polymers enable CO₂ to be absorbed from ambient air under dry conditions and released upon exposure to moisture. This method provides an energy efficient alternative to conventional thermal or pressure swing capture methods. This invention focuses on tailoring the polymer structure, particularly the cationic phosphonium groups, counter anions, and polymer backbone to optimize CO₂ binding strength, humidity driven release behavior, and long-term chemical stability. These Phosphonium-based polymers provide an opportunity to overcome the challenges facing convention capture methods by offering tunable ionic environments, enhanced CO₂ binding affinity, and improved structural robustness

 

This next generation approach enables sustainable and energy efficient carbon capture directly from the atmosphere.

 

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