Climatic Conditions and Amine Loading Impact the Performance of Laminate-Supported Poly(ethylenimine) Direct Air Capture Sorbents

Direct air capture (DAC) of CO₂ is a critical technology to combat climate change, offering a scalable approach to mitigate atmospheric CO₂ accumulation. Despite advancements in adsorbent materials, the performance of DAC systems remains highly sensitive to environmental conditions, such as temperature and humidity. Poly-(ethylenimine) (PEI)-functionalized silica has emerged as a promising sorbent due to its high CO₂ capacity and tunable properties. However, optimizing its performance across diverse climatic conditions requires a deeper understanding of how the PEI loading impacts the adsorption capacity and kinetics under varying temperatures and humidities. This study reports the CO₂ and H₂O adsorption kinetics and capacities, desorption behavior, and speciation of adsorbed CO₂ using silica/PEI adsorbents supported within expanded poly-(tetrafluoroethylene) (ePTFE) sheets across a wide range of temperatures and humidities, representing the diversity of climates found across the United States. With the obtained data, guidelines for selecting and optimizing PEI-loaded silica-based sorbents for DAC applications are developed. These findings provide a framework for tailoring sorbents to specific climatic scenarios, ensuring a reliable and efficient DAC performance.