A new phase-change solvent composed of diethylenetriamine, n-butanol and water for CO2 capture

Abstract

In this work, a new phase-change solvent composed of diethylenetriamine (DETA)/n-butanol/water is reported for CO2 capture. Screening of the absorption solvents, and the performance of absorption, desorption, and cyclic capacity are comprehensively investigated. The experimental results show that 30 wt% DETA/water systems exhibit excellent absorption performance. Accordingly, 30 wt% DETA/n-butanol/H2O system is used as a phase-change solvent for CO2 capture. The DETA/n-butanol/H2O mixture with mass ratio 3:4:3 shows better absorption performance compared to others of 3:1:6, 3:2:5, 3:3:4, 3:4:3, 3:5:2, and 3:6:1, and the equilibrium CO2 loading reaches up to 3.70 mol·kg−1 at 60 min, 313.15 K and 101 kPa. The 3:4:3 DETA/n-butanol/H2O system displays low heat duty with a relative heat duty of 61.4 %, and outstanding cyclic capacity (CC). CC increases by 47.6 % compared to the widely used 30 wt% aqueous monoethanolamine (MEA) solution. Finally, 13C NMR is used to determine the species before and after CO2 absorption. The mechanism of the phase transition is analyzed according to the species polarity which is estimated using Gaussian 09 W program.