CO2 capture from flue gas at high temperatures by new ionic liquids with high capacity

Abstract

Room-temperature ionic liquids (ILs) are widely investigated to capture CO2 from flue gas and can capture a large amount of CO2. However, almost all of the previous studies on the absorption of CO2 by ILs were carried out at low temperatures, less than 60 °C and even at room temperature. When the temperatures reach the real flue gas temperatures, from 110 °C to 140 °C, these ILs might hardly absorb CO2, as high temperatures decrease the CO2 capacity. Therefore, it is necessary to design new task specific ILs to capture CO2 at flue gas temperatures with high absorption capacity. In this work, a new type of polyamine based ILs were developed to absorb CO2 from simulated flue gas at high temperatures and ambient pressure with large absorption capacities up to 0.944 mole ratio or 0.176 mass ratio of CO2 to IL at 110 °C. These ILs could be easily synthesized by neutralization of polyamines and organic acids, and the number of amido groups on the ILs can be easily controlled. The CO2 absorption is influenced by temperature, CO2 volume fraction in the flue gas, and the number of amido groups on the ILs. Also a possible mechanism for the CO2 absorption has been proposed.