Advancing CO2 absorption and desorption by mass transfer promoters: Density difference adjustment based on spontaneous interfacial turbulence

Abstract

Amine-based chemical absorption for CO₂ capture gains superiorities in removal efficiency, CO₂ capacity and selectivity, but suffering from high energy consumption. Improvements on absorption – desorption performances could effectively tackle the regeneration energy and capital cost challenge. Recently, a new method of mass transfer promoters (MTPs) based on density-triggered interfacial turbulence has been proposed and confirmed to increase mass transfer rate by several fold. Guided by density difference principle, in this work, means of adjusting amine type, concentration and MTPs were investigated to regulate the absorption − desorption rate. Increasing amino group of amine molecule, amine concentration and MTPs concentration were found to enhance absorption rate by 5–7 fold resulted from the strengthening of density difference. The visualized experiments revealed the transition and reinforcement of interfacial turbulence driven by intensified density difference. Further the power function relationship between enhancement factor and parameters related with density driven Rayleigh-Bénard effect was established, providing guidance of predicting enhancement extent. The effects of MTPs on desorption performance were assessed in terms of desorption rate and cyclic CO₂ loading. Absorbents with MTPs possessed higher desorption rate and cyclic CO₂ loading with largest enhancement of 154 % and 159 % respectively, showing great potential for cost-effective CO₂ capture.