CO₂ Absorption into Aqueous Solutions of a Polyamine (PZEA), a Sterically Hindered Amine (AMP), and their Blends

Abstract

Among numerous techniques existing for reducing CO 2 emissions, CO 2 capture by absorption in aqueous alkanolamine solutions was specifically studied in this work. For the choice of the adequate amine solution, two major criteria must be taken into account: absorption performances (higher with primary and secondary amines) and energy costs for solvent regeneration (more interesting with tertiary and sterically hindered amines). The different types of amines can also be mixed in order to combine the specific advantages of each type of amines, an activation phenomenon being observed. Aqueous solutions of (piperazinyl-1)-2-ethylamine (PZEA, a polyamine known as absorption activator) and 1-amino-2-propanol (AMP, a sterically hindered amine), pure or mixed with other amines, are experimentally compared with respect to CO 2 removal performances by means of absorption test runs achieved in a special gas-liquid contactor at 25°C. The positive impact of addition of PZEA to monoethanolamine (MEA), N-methyldiethanolamine (MDEA), and AMP solutions was clearly highlighted. The absorption performances have also been satisfactorily simulated with coherent physicochemical data. IntroductionA wide variety of amine-based solvents can be used to absorb CO 2 , such as aqueous solutions of monoethanolamine (MEA) or N-methyldiethanolamine (MDEA), already studied in our previous work [1]. Blended alkanolamine solutions are also used to combine the advantages of each type of amine: the fast kinetics from primary and secondary alkanolamines and the high absorption capacity with low solvent regeneration cost from tertiary or sterically hindered amines (SHAs). In order to obtain better absorption performances, another possibility is to add to the aqueous amine solution an absorption activator such as piperazine leading to faster absorption kinetics [2][3][4][5].This work aimed actually at comparing the CO 2 absorption performances into several aqueous amine solutions and their blends. The amine solutions studied in this first step are: (piperazinyl-1)-2-ethylamine (PZEA), an absorption activator already tested by [6,7], and 1-amino-2-propanol (AMP), a sterically hindered amine. The absorption performances of these amines, blended with the classical alkanolamines MEA and MDEA, were here also tested.Data available in the literature related to amine systems of interest, i.e., containing AMP or MDEA, are quite widespread: (i) thermodynamical data relative to the solubility of CO 2 in amine solutions giving partial pressure of CO 2 as a function of CO 2 loading of the solution, e.g., in [8] for MDEA + AMP; (ii) kinetic data assessed from absorption test runs generally achieved in wetted wall columns for different amine mixtures: AMP + MEA [9,10], AMP + DEA [11], AMP + PZ [12], and PZEA + MDEA [7]. Influence of contact time, concentration of amines, and temperature are investigated, but no global comparison of efficiencies is possible.To our knowledge, the addition of PZEA to MEA or AMP was never considered in previous studies. As all our exp...

Amine Solutions for Biogas Upgrading: Ideal versus Non‐Ideal Absorption Isotherms

“…The effect of different amine concentrations on the CO 2 capturing efficiency was studied in [8,34], and it was confirmed that the efficiency increases with increasing amine concentration. However, industrial amine-treating systems, which are based on the application of MEA and DEA solutions, usually operate within the concentration range from 15 to 30 wt % [35][36][37].…”

CO2 capture from biogas: absorbent selection

“…3.1.5 Addition of piperazine. Utilization of systems based on the sterically hindered amines 16,17 and concentrated, aqueous piperazine (PZ) has been recently reported for CO 2 capture. 18 Piperazine acts as an activator in CO 2 absorption and plays a significant role in the improvement of mass transfer in any scrubbing process.…”

“…15 Aqueous PZ solutions have been investigated as absorbents per se and as an activator in amine solutions. [16][17][18][19] As potential ''green'' solvents, ionic liquids are currently under intensive research. Due to their unique properties, in particular frequently demonstrated negligible vapour pressure and high thermal stability, they have attracted a lot of interest.…”

Advances in Liquid Absorbents for CO2 Capture: A Review

“…Another activator, (piperazinyl-1)-2-ethylamine (PZEA) was investigated by Dubois et al 62 Pure PZEA and AMP as well as a mixture of the two with other amines are investigated to compare the performances for CO 2 absorption. The positive effect of the addition of PZEA in MEA, MDEA and AMP were clearly shown through the experiments, while the addition of AMP into MEA also showed interesting activation results.…”