Mass Transfer Performance of CO2 Absorption into Aqueous Solutions of 4-Diethylamino-2-butanol, Monoethanolamine, and N-Methyldiethanolamine

The mass transfer performance of the absorption of CO2 in an aqueous solution of monoethanolamine was evaluated experimentally in a lab-scale absorber packed with high efficiency DX structured packing and compared with that of methyldiethanolamine (MDEA) as well as that of a newly developed tertiary amino alcohol, 4-diethylamino-2-butanol (DEAB). The absorption experiments were conducted at atmospheric pressure, using a feed gas mixture containing 14.9% CO2 and 85.1% nitrogen in an absorption column containing DX structured packing. The absorption performance was presented in terms of the CO2 removal efficiency, absorber height requirement, effective interfacial area for mass transfer, and overall mass-transfer coefficient (K G a v). In particular, the effects of parameters such as inert gas flow rate and liquid flow rate were compared for both DEAB and MDEA. The results show that the DEAB has a much higher removal efficiency for CO2 along the height of the column than MDEA. Also, the K G a v of DEAB was much higher than that for MDEA. For all the solvents, the K G a v increased as the liquid flow rate was increased. An empirical correlation for the mass transfer coefficient for the CO2-DEAB system has been developed as a function of the process parameters. In terms of comparison, the results show that the DEAB system provided an excellent overall mass transfer coefficient, which is higher than that of the MDEA system but less than that of MEA.