Highly Efficient CO₂ Capture by Polyethylenimine Plus 1-Ethyl-3-Methylimidazolium Acetate Mixed Absorbents

Abstract

In traditional amine-scrubbing CO2 capture technology, alkanolamines are diluted in physical solvents to retain the good fluidity of CO2-loaded absorbents, which suffers from high volatility of mixed absorbents and sacrifice of absolute CO2 capacities. Herein, we designed a novel class of mixed absorbents comprising of polyethylenimine (PEI) and 1-ethyl-3-methylimidazolium acetate ([emim][AcO]) for CO2 capture. PEI is a type of polymeric amine compound with high amine density and negligible volatility, acting as the key component for CO2 absorption. [emim][AcO] is a type of functionalized ionic liquid (IL) with chemical affinity to CO2, but its viscosity is low and does not increase drastically after CO2 absorption, acting as the diluent and supplementary component for CO2 absorption. With such formulation, all the components in designed absorbents are extremely low volatile and exhibit chemical affinity to CO2. In addition, the designed absorbents display fast CO2 absorption, high CO2 capacities, and good recyclability. It is believed that PEI + [emim][AcO] mixtures have promising application as alternatives to aqueous alkanolamines for CO2 capture.