CO2 absorption enhancement by mass transfer promoters triggered interfacial turbulence

High energy consumption and capital cost is challenging to the chemical absorption of CO2 capture. A fast absorption rate for enhancement on absorption process is preferred to reduce equipment size and total cost. A new method of adding mass transfer promoters (MTPs) into absorbents has been proposed and attempted to enhance CO2 absorption. While the limited understanding of MTPs hinders practical application. In this work, to elaborate the requirements for MTPs and their enhancement mechanisms, various organic solvents were screened as candidates of MTPs and investigated the effect on absorption rate in monoethanolamine (MEA) systems. Organic solvents with low surface tension and density exhibited promotive effect on absorption rate, leading to 1 to 6-fold increase in absorption rate. A power function relation was established between enhancement extent and surface tension difference, density difference. Visualized experiments and diffusion coefficient calculation both directly uncovered transfer mode transition into spontaneous eddy diffusion, indicating the occurrence of interfacial turbulence. Influencing factors of chemical absorption, including MEA concentration, viscosity and temperature, were researched. By adjusting influencing factors, the interfacial turbulence can persistently affect mass transfer performance in CO2 absorption. It was concluded that properly increasing reactant concentration, temperature and decreasing viscosity could persistently improve absorption rate by enhancing interfacial turbulence.