Phase change behavior and kinetics of CO2 absorption into DMBA/DEEA solution in a wetted-wall column

Abstract

Coal-fired flue gas is a major source of greenhouse gas CO2. Phase-change absorbents can be used to reduce energy consumption associated with regeneration during CO2 capture. In this study, N,N-dimethylbutylamine (DMBA) and N,N-dimethylbutylamine (DEEA) were mixed to develop phase-change absorbents, and the reaction kinetics of CO2 absorption in the absorbents were examined. A bubbling device was used to prepare phase-change absorbents with different CO2 loading levels. The physico-chemical parameters of the absorbents under different conditions were specified, and the changes in the CO2 loading of the upper and lower layers of the absorption solutions after a liquid–liquid separation were analyzed. A wetted-wall column was subsequently used to investigate the effects of temperature, CO2 loading, gas flow rate, and DMBA/DEEA composition ratio on CO2 absorption rate. This study determined that the flow velocity, reaction temperature, and CO2 loading affected the CO2 absorption rates to a certain extent. In addition, comparing the reactive properties of the 4M DMBA+2M DEEA and 2M DMBA+4M DEEA absorbents under the same experimental conditions revealed that the 4M DMBA+2M DEEA absorbent exhibited higher absorption rate and reaction stability. A kinetics model also indicated that the CO2 absorption of the phase-change absorbents used in this study was mainly affected by the liquid film diffusion process. This study contributes theoretically to the development of CO2 absorption technologies.