Ionic Liquid Functionalizes the Metal Organic Framework for Microwave-Assisted Direct Air Capture of CO2

Sorbents for direct air capture (DAC) of CO2 typically employ a chemisorbing material that requires regeneration at elevated temperatures, which is an energy-intensive step. Here, we developed composites of metal organic framework (MOF) with a functional ionic liquid (IL) at 5, 20, and 35 wt % loading, capable of CO2 chemisorption and regeneration by moisture-swing coupled microwave (MW) irradiation. In dynamic breakthrough measurements, CO2 from synthetic air (500 ppm of CO2) was selectively absorbed (0.5 mmol/g at 30 degrees C) and then rapidly released (2-4 min) by dielectric heating at 60 degrees C. The developed IL/MOF composites demonstrate (1) targeted energy transfer to the IL domains where CO2 is released due to dielectric heating upon MW irradiation and (2) a fast desorption rate due to large surface area offered by the MOF architecture. This study establishes carbon capture through surface enhancement of a porous substrate with ILs for future DAC processes that can be powered by sustainable energy sources.