Water-Triggered Direct Air Capture by Strong Organic Bases.

Abstract

A key challenge for sorbent-mediated temperature-swing direct air capture remains to maximize the difference in CO2 loading under capture and regeneration conditions (i.e. the working capacity) while minimizing the thermal energy input required to alternate between the two equilibrium states. Herein, peralkylated guanidines were shown to capture close to 1 molar equivalent (or up 4.5 mol CO2/kg absorbent) directly from moist air (>60% RH) at room temperature and completely release the entire quantity of captured CO2 upon co-evaporation of water at 70 oC affording concentrated CO2 with a vapor content of 3 mol% and achieving a high working capacity with minimum temperature swing of 45 oC.