Kinetics of CO2 capture by ionic liquid—CO2 binding organic liquid dual systems

Abstract A dual system, which aims to combine the individual advantages of two different solvents, has been developed for CO 2 capture in order to intensify the process by reducing the reboiler duty. The dual system consisted of 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]) and 1.8-diazabicyclo 5.4.0 undec-7-ene (DBU) in 1-hexanol medium and the relevant kinetics were determined by using a stopped flow equipment. Based on pseudo-first-order reaction kinetics of CO 2 , the reaction was modeled by a modified termolecular reaction mechanism and rate constants and the activation energies of the [bmim][Tf2N]–DBU system were obtained. In addition, the absorption capacity and the initial absorption rate of the 10 wt% [bmim][Tf2N]-15 wt% DBU dual system were measured in a gas-liquid reactor at 303 K and 2 atm 0.815:1 mol ratio of CO 2 :DBU was achieved with this dual system – which approximately doubles the capacity of commercial alkanolamine solutions – and the initial CO 2 absorption rate of the dual system was found to be 3.500 × 10 −5  kmol/m 2 s. Reversibility of dual system was also briefly investigated by using Fourier transform infrared spectrometry.