Developing non-aqueous slurry for CO2 capture

Abstract

The urgency of mitigating CO₂ emissions has become increasingly critical due to their detrimental effects on environmental sustainability and human health. Among emerging solutions, deep eutectic solvents (DESs) have garnered attention for their high CO₂ capture capacities. However, widespread application of DESs has been constrained by their inherent high viscosity and cost. To overcome these limitations, this study further explores the novel strategy, where cosolvent addition and immobilization are combined to develop a non-aqueous slurry for CO₂ capture with high efficiency. Here, [MEACl][EDA] with (1:5) molar ratio is mixed with ethylene glycol (EG) to form a non-aqueous DES solution, and the DES is further immobilized into the mesoporous silica to form a composite and then mixed with the DES-EG solution to make a slurry. The CO₂ capture tests demonstrated 15 wt.% capture capacity at 22 °C and 1 bar, and efficient sorption and desorption rates (0.34 and 0.38 mol CO₂/(kg sorbent·min) within the initial 2 min). The slurry also exhibited promising cyclic performance with 96.4 % recovery together with minimal solvent loss of 0.97 % and almost intact structure after 120 hr of heating at 110 °C. The improved capture capacity and kinetics, especially for desorption, as well as enhanced thermal stability of the non-aqueous system highlight its potential for industrial applications.