An amine-functionalized strategy to enhance the CO2 absorption of type III porous liquids

Porous liquids (PLs) is a new material with two seemingly unrelated characteristics: porosity and liquidity. In this study, an amine functionalized strategy was proposed to enhance the CO2 absorption of Type III Porous Liquids. 2-Methylimidazole zinc salt (ZIF-8) modified by tetraethylenepentamine (TEPA) was chosen for providing porosities and the 1-Ethyl-3-methylimidazolium Bis(trifluoro-methanesulfonyl)-imide ([EMlm][NTf2]) was chosen as sterically hindered solvent, an amine-functionalized type Ⅲ porous liquids were reported. First, amine groups were successfully loaded on the ZIF-8. Then, the effect of amine loading on ZIF-8 was investigated. It was found the 30 TEPA@ZIF-8 nanoparticles were the optimum candidates based on CO2 absorption capacity and micropore analysis. Subsequently, the CO2 absorption capacity of absorbent was studied. 5-30TEPA@ZIF-8/[EMlm][NTf2] had a CO2 absorption capacity of 0.124 mmol g−1, which was 4.43 times higher than 5-0TEPA@ZIF-8/[EMlm][NTf2]. And the corresponding absorption rate increased by 745%. Three kinetics models were used for describing the absorption process, and the result showed the fractional-order kinetic model was the most accurate. Finally, the absorbent had a low heat absorption with a value of −1.38 kJ/mol. The CO2 absorption capacity lost just 4.3% after five cycles. All the results indicate the prepared porous liquids had an application potential in CO2 capture.