New research could extend the life of key carbon-capturing materials

Researchers at Lawrence Livermore National Laboratory (LLNL), in collaboration with the Georgia Institute of Technology, have made a significant advance in understanding the impact of carbon dioxide (CO₂) on the stability of amine-functionalized porous solid materials, a crucial element of direct air capture (DAC) carbon capture technologies.

This new research, published in the Journal of the American Chemical Society and featured on the cover of the newspaper, highlights the complex interactions between CO₂ and poly(ethyleneimine) sorbents, providing important information that could improve the efficiency and sustainability of DAC systems.

“This study highlights the importance of considering all atmospheric components in the design of DAC processes and materials,” said Simon Pang, corresponding author and principal investigator of the project. “Our findings will be instrumental in the development of next-generation sorbents with improved durability, contributing to more efficient and cost-effective carbon capture solutions.”

Amine-based sorbents are at the forefront of DAC technology due to their exceptional ability to effectively capture CO₂ even in ultra-diluted conditions. However, the long-term stability of these materials poses a significant challenge, mainly due to their oxidative degradation.

The research team investigated the previously unresolved role of CO₂ in the process of oxidative degradation of these absorbents, reconciling the contradictory data in the existing literature. The study reveals that CO₂ exerts a non-monotonic effect on the oxidation kinetics of poly(ethyleneimine) absorbents, its impact varying considerably depending on temperature and CO₂ concentration.

“Our research highlights the dual role of CO₂ in the oxidation process,” said Sichi Li, lead author of the paper and co-investigator of the project. “On the one hand, CO₂ catalyzes critical oxidation reactions, while on the other hand, it reduces the mobility of the polymer branches, which slows down the propagation of radicals. These contrasting effects are key to understanding the complex degradation profiles we observed. »

The study’s findings go beyond reconciling existing literature, offering practical implications for the future of DAC technology. By identifying polymer side chain mobility and the presence of acidic environments as major factors accelerating oxidation, the research suggests new strategies to improve sorbent longevity. Potential solutions include the introduction of functional groups, additives, or oxide carriers with surface chemistry designed to reduce polymer mobility or neutralize acidic conditions, thereby mitigating the rate of oxidative degradation.