Efficient and Reversible Capture of CO2 in CO2-Binding Organic Liquids Formed by 1,1,3,3-Tetramethylguanidine and Glycerol Derivatives

Abstract

A class of CO2-binding organic liquids (CO2-BOLs) composed of 1,1,3,3-Tetramethylguanidine (TMG) and Glycerol (Gly) and Gly’s amino derivatives were developed for highly efficient and reversible CO2 capture. These CO2-BOLs exhibited high gravimetric CO2 solubility up to 0.196 g CO2·g–1 at 313.2 K and 1.0 atm, superior to most functionalized ILs and other absorbents. The influential factors of CO2 absorption, such as components of CO2-BOLs, absorption temperature, and CO2 partial pressure together with water contents were investigated, and the recyclability of CO2-BOLs was verified to be excellent. The absorption mechanism of CO2-BOLs was explored with the help of spectral analysis, quantum chemical calculation, and thermodynamic analysis. All the results revealed that chemisorption took place once these CO2-BOLs were exposed to CO2, and alkyl guanidine carbonates were produced. Besides, it is illustrated that introducing the amino group to Gly could reduce the nucleophilic reactivity of CO2-BOLs, along with the absorption enthalpy simultaneously.