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

The selective separation of CO2 from CH4-containing gases is crucial to produce clean energy gases. In this study, triazole anion-functionalized ionic liquids (TAFILs) were designed by combining low molecular weight cations with triazole anions containing N electronegative site and further mixed with physical solvents to form physicochemical absorbents. The results indicated that [Cho][Triz]/TMS (80 wt%/20 wt%) not only absorbs 0.125 g CO2/g absorbent equal to that of 30 wt% MEA solution at 40 degrees C and 1 bar, but also has low enthalpy of -35.76 kJ/mol less than half of 30 wt% MEA solution. Simultaneously, a super high CO2/CH4 selectivity of 191.0, higher than most of the reported absorbents, is obtained for [Cho][Triz]/TMS solvents. Such great performance of CO2 separation was attributed to relatively weak chemical and physical interaction between CO2 and TAFIL binary absorbents. This study may provide novel promising ionic liquid absorbents for CO2 capture applications from clean energy gases.