Selective CO2 separation through physicochemical absorption by triazole-functionalized ionic liquid binary absorbents

Selective separation of CO2 from CH4-containing gases is crucial for the production of clean energy gases. In this work, the triazole anion-functionalized ionic liquids (TAFILs) consisting of cations with low molecular weight and triazole anion with N electronegative site were synthesized, and further combined with physical solvents to form the physicochemical absorbents. The results indicated that CO2 solubility of [Cho][Triz]/TMS (80 wt%/20 wt%) is not only equal to that of 30 wt% MEA solution at 40°C and 1 bar, but also its low enthalpy is -35.76 kJ/mol and less than half of 30 wt% MEA solution. Meanwhile, superhigh CO2/CH4 selectivity of 191.0 higher than reported absorbents is simultaneously obtained for [Cho][Triz]/TMS (80 wt%/20 wt%). Such great comprehensive performance of CO2 separation was attributed to relatively weak chemical and physical interaction between CO2 and TAFIL binary absorbents. This work may provide promising IL absorbents for CO2 capture applications from natural gases.