Perspectives on the green hybrid blend of diethanolamine-glycerol for post-combustion carbon dioxide capture via a Y-type micro-reactor

Abstract

CO2 capture by aqueous primary and secondary alkanolamine solutions is a recognized technology in industrial CO2 separation processes. Yet, certain obstacles caused by high-energy consumption due to the amine regeneration demands, and the formation of thermally stable salts require to be overcome for the development of these solvents. In this paper, glycerol, as a beneficial by-product of biodiesel production, has been introduced as a second promising CO2 absorbent for aqueous diethanolamine solution in a Y-type micro-reactor with dimensions of 800 µm × 4 cm × 19 cm. The experiments of CO2 capture into the hybrid blend of DEA-Glycerol were investigated at ambient pressure and the operating temperature of 25–45 °C, volumetric gas flow rate of 100–300 ml/min, DEA concentrations of 1.5–2.5 M, and glycerol concentrations of 5–15%wt. Experimental results demonstrated that adding 10 wt% glycerol in the aqueous blend of 2.5 M DEA-Glycerol boosts the CO2 removal percentage, RP, up to 96.89%, and enhances the volumetric overall gas-phase mass transfer coefficient, KGaV, and volumetric mass transfer flux, NAaV, to 34.89 kmol/m3.h.kPa and 88.04 kmol/h.m3, respectively. Furthermore, based on the Box-Behnken statistical responses, under the constant concentration of 2 M of DEA, increasing the presence of glycerol from 5 to 10 wt% in the hybrid blend of DEA-Gly can intensify the CO2 RP, KGaV, and NAaV values by 2.12% and 8.66%, and 1.80%, respectively, illustrating the glycerol contribution on the CO2 capture process.