Promotion Mechanism for CO2 Absorption into Partially Carbonated Ammonia Solutions.

Determination of the Structural Features of Distinct Amines Important for the Absorption of CO2 and Regeneration in Aqueous Solution

“…Furthermore, since the ring of the pyrrolidine is little, this molecule can adopt a spatial organization in solution that favors the loading of CO 2 . Moreover, the low CO 2 loading noticed for primary amine ammonia might be associated with the formation of ammonium bicarbonate that limits the reaction at 0.5 mol of CO 2 /mol of ammonia. , Accordingly, Yeh and Bai 5 have also observed a weak loading value of 1.20 kg of CO 2 /kg of NH 3 (0.464 mol of CO 2 /mol of NH 3 ) for CO 2 absorption in an aqueous 7 wt % ammonia solution, at a 16 vol % CO 2 flow of 2 L/min at 25 °C. In the case of MEA, the low loading value observed for this primary alkanolamine might be due to the formation of a stable carbamate that limits its CO 2 absorption.…”

“…This reversible reaction is constituted by a series of intermediary endothermal-exothermal reactions which are limited to a maximal loading of 0.5 mol of CO 2 /mol of ammonia. 5,6 Moreover, another disadvantage associated with the use of ammonia is the difficultly in separating CO 2 and ammonia after the thermal decomposition of ammonium bicarbonate. 7 In addition, the sterically unhindered primary and secondary alkanolamines in aqueous solution react directly, instantaneously, and reversibly with CO 2 by forming an intermediate zwitterion that is deprotonated by amine giving carbamate through the reactions (2)-(4).…”

“…In general, the CO 2 absorption capacities for the amines depend on several factors including pH of the solution, basicity, concentration, and structural characteristics of amine. In particular, the reaction of aqueous primary amine solutions such as ammonia with CO 2 leads to the formation of ammonium bicarbonate as follows: This reversible reaction is constituted by a series of intermediary endothermal−exothermal reactions which are limited to a maximal loading of 0.5 mol of CO 2 /mol of ammonia. , Moreover, another disadvantage associated with the use of ammonia is the difficultly in separating CO 2 and ammonia after the thermal decomposition of ammonium bicarbonate …”

CO2 Capture and Crystallization of Ammonia Bicarbonate in a Lab-Scale Scrubber

“…Many scholars have studied the absorption of CO2 using an aqueous ammonia solution and have adopted different scrubbers for their studies, such as the stirred cell [4,17], sieve plate column [9], falling film [18], absorption column [19] and spray tower [20] scrubbers. In literature, the suitability of an absorber is determined by the level of the mass transfer coefficient.…”

Comparative study of chemical absorbents in postcombustion CO2 capture

“…Due to the presence of ionic species in theses multi-component volatile weak electrolyte systems [17,18], liquid and vapour properties were computed by the electrolyte NRTL method. Henry's law was used to calculate the solubility of CO 2 in water.…”