New Experimental Data on Equilibrium CO2 Loading into Aqueous 3-Dimethyl Amino-1-propanol and 1,5-Diamino-2-methylpentane Blend: Empirical Model and CO2 Absorption Enthalpy

Abstract

This research was targeted to determine the equilibrium CO2 loading in the novel aqueous 3-dimethyl amino-1-propanol (3-DMA-1-P) and 1,5-diamino-2-methylpentane (1,5-DA-2-MP) blend accomplished in the bubble absorption column of a lab-scale experimental setup. The experiments were conducted at a total concentration of the aqueous amine blend (CT) within 10-30 wt %, the weight fraction of 1,5-DA-2-MP in the amine blend (3-DMA-1-P + 1,5-DA-2-MP) in the range of 0.05-0.2, the temperature of the aqueous amine blend system from 293.15 to 323.15 K, and the partial pressure of CO2 ranging from 10.13 to 25.33 kPa, and all of these were executed at atmospheric pressure. The addition of a small quantity of activator 1,5-DA-2-MP revealed significant increase in the performance of CO2 absorption. Maximum CO2 loading αmax 0.97 mol CO2/mol amine was obtained by this blend under the operating condition of CT 10 wt %, w1,5-DA-2-MP 0.2, pCO2 20.27 kPa, T 313.15 K, and P 101.325 kPa. The empirical model for the equilibrium CO2 loading in the amine blend was developed with the correlation of the experimental data. The average absolute relative deviation % was 2.7 for this empirical model. The Gibbs Helmholtz equation was employed for calculation of the CO2 absorption enthalpy (-67.3 kJ/mol) for this amine blend, which was considerably lower than the absorption enthalpy (-83.7 kJ/mol) of conventionally used monoethanolamine. © 2020 American Chemical Society.