A low energy-consuming phase change absorbent of MAE/DGM/H2O for CO2 capture

Abstract

The concept of phase change absorbents has been widely studied as a novel and low-energy consumption option for CO2 capture. This work screened diethylene glycol dimethyl ether (DGM) from 17 physical solvent species as a better phase change accelerator for absorbents of 2-(methylamino)ethanol (MAE)-physical solvent-H2O. Then, the optimized mass ratio of 30:49:21 for MAE-DGM-H2O solution was investigated with phase change behaviors, CO2 absorption–desorption performance, cyclic capacity, and energy consumption. The experimental results showed that the cyclic CO2 capacity reached 1.32 mol/L and the CO2-rich phase made up only 50.4 % of the total volume for the 30 wt%MAE-49 wt%DGM-21 wt%H2O, as well as its regenerative energy consumption was 40 % lower than that of 30 wt% monoethanolamine (MEA) solution. Also, the viscosity and surface tension gap of the CO2-rich phase and CO2-lean phase for the optimized absorbent were studied. It was observed that those gaps increase with the increasing mass ratio of DGM. In addition, the possible phase change mechanism was proposed by using the dipole moment values of components calculated by Gaussian (B3LYP/6-31G) coupled with 13C NMR spectra.