Porosity and hydrophilicity modulated quaternary ammonium-based sorbents for CO2 capture

Abstract

Quaternary ammonium (QA)-based polymeric sorbents are known to be effective for CO2 capture, especially from ultradilute streams like air. In this work, we address two major challenges in QA sorbent design for application in moisture-swing processes, porosity control and hydrophilicity modulation. Facilely substituting porous CO2-active components for non-porous ones can enhance the sorption kinetics by 4-fold compared to the state-of-art, and micro–mesoporous structures are identified as optimal porous structures. A method to modulate the hydrophilicity of QA-based sorbents is developed using controlled radical polymerization, incorporating fluorine-containing monomers. The CO2 sorption capacity and the tolerance towards moisture are simultaneously enhanced via adjustment of the structure and the content of fluorine-containing blocks. We postulate that porosity and hydrophilicity optimization can make QA-based sorbents adaptive to deployment of scalable moisture-swing processes in varied and complex atmospheric circumstances.