Carbon Dioxide Absorption into Aqueous Blends of Methyldiethanolamine (MDEA) and Alkyl Amines Containing Multiple Amino Groups

Abstract

Alkyl amines, which have multiple amino groups, are used as activators to improve the CO2 absorption performances of aqueous methyldiethanolamine (MDEA) solutions. The aqueous MDEA blends consisted of 20% (w/w) of MDEA and 10% (w/w) of activators, which are 3-methylamino propylamine (MAPA), diethylenetriamine (DETA), triethylene tetramine (TETA), and tetraethylenepentamine (TEPA). Aqueous solutions of monoethanolamine (MEA; 30% (w/w)) and MDEA (30% (w/w)) are used as reference absorbents for comparison. The CO2 absorption performances of aqueous MDEA blends were investigated by measurements of absorption capacities, absorption rates, and heats of absorption. The MDEA blends have higher CO2 absorption capacities than MEA and MDEA. MDEA/TEPA shows the highest CO2 loading amount of 0.753 mol-CO2·mol-absorbent–1 at 313 K. In addition, the MDEA blends show high cyclic capacities (0.241–0.330 mol-CO2·mol-absorbent–1), the values of which are about 3 times higher than that of MEA. All MDEA blends show higher absorption fluxes than MDEA. The MDEA/MAPA showed the highest overall mass transfer coefficient of 3.351 × 103 mol·m–2·s–1·kPa–1, 8 times higher than that of MDEA (0.451 × 103 mol·m–2·s–1·kPa–1) and even higher than that of MEA (3.014 × 103 mol·m–2·s–1·kPa–1). The heats of absorption of the MDEA blends (57.21–59.53 kJ·mol-CO2 –1) are about 30% higher than that of MDEA and about 30% lower than that of MEA.

Exploiting an Alternative CO2 Absorption Process by Efficient Solvent Mixture

“…35 The 25% CO 2 fraction produces the largest mass transfer coefficient of 4.02kmol/m 2 /s/kPa, which is 34% higher typical 3kmol/m 2 /s/kPa of MEA absorption of CO 2 . 24 As the CO 2 fraction decreases to 5%, the mass transfer coefficient decreases by 10% against the 25% CO 2 fraction circumstance. This is because a higher CO 2 fraction provides a greater driving force for CO 2 dissolution, which is generated by higher partial pressure.…”

“…25 By considering the effects of the packing on mass transfer, it is required to revise the mass flux equation in the literature. 24 Hence, the interface mass flux N (mol/m 2 /s) is developed by including the porosity caused by the packing ε π ε π τ…”

“…Additionally, it is found that TAMH-TMS-EG produces higher mass transfer coefficient against the typical MEA. 24 This is possible because TAMH-TMS-EG provides greater enhancements according to reaction kinetics (eq 6) and wider CO 2 loading ranges (details in Discussion section). Meanwhile, taking temperature and position in column as fit parameters, the axial temperature is compared with the experimental data, which is shown in Figure 1c.…”

Simultaneous Sodium Hydroxide Production by Membrane Electrolysis and Carbon Dioxide Capture

“…Various technologies have been investigated for CO 2 capture including chemical absorption, physicochemical adsorption, and membrane separation . One of the effective methods for CO 2 removal usually employs postcombustion capture, which is a chemical absorption technology using aqueous solutions of alkanolamines or their mixtures . The CO 2 ‐rich absorbents after the absorption process need to be regenerated thermally by a desorption process in order to recycle the absorbents for continuous operation.…”

CO2 Absorption and Regeneration Using Amines with Different Degrees of Steric Hindrance

“…The research into carbon dioxide separation by chemical‐absorption processes has recently increased to prevent emissions and enhance carbon dioxide purification to be used, for example, in storage strategies. Over the last decade, the development of new chemical solvents used for carbon dioxide separation by gas‐liquid absorption has been centered on several fields such as the use of ionic liquids , , mixtures of amines , , or new sterically hindered amines (SHAs) , . Like ionic‐liquid‐based solvents, SHAs have interesting characteristics, such as low vapor pressure that prevents the emission and loss of solvent.…”