Transition of Ionic Liquid Solution into Microparticles with CO₂ for CO₂ Utilization and Storage

Underground CO2 storage is a key strategy for mitigating climate change by reducing greenhouse gas emissions. However, the heterogeneity of reservoirs poses challenges to effectively storing CO2 in designated spaces. In this study, an environmentally friendly CO2-responsive ionic liquid (IL) DA-Ch was synthesized by choline hydroxide (Ch) and dodecanedioic acid (DA) at a 2:1 mol ratio. The innovative system enhances the sweep efficiency and storage capacity of CO2 by enabling the transition of DA-Ch ILs aqueous solution from low-viscosity liquids (0.5 mPa·s at 0.1 mol/L) to solid microparticles upon CO2 introduction. After CO2 injection, DA precipitated again from the DA-Ch ILs aqueous solution with a volume mean particle size of micrometers, even under high-salinity conditions. This phase transition effectively plugs preferential flow channels, expanding CO2 storage space by 82% compared to conventional CO2 flooding. Our findings propose a novel, sustainable approach to address gas channeling challenges in subsurface CO2 storage, offering dual benefits for carbon sequestration and enhanced oil recovery.