Reactive Absorption of Carbon Dioxide in l-Prolinate Salt Solutions

Abstract

Aqueous amino acid salt solutions are seen as more sustainable alternative CO 2 solvents compared to conventional alkanolamines. The absorption of CO 2 into aqueous solutions of potassium L-prolinate, over the temperature range of 290−303 K, was studied using a stirred cell. To compare the effect of potassium versus sodium as counterion, the absorption rates of CO 2 in sodium L-prolinate solutions were also determined. The amino acid salt concentration was varied between 0.5 and 3 mol dm −3 . Physicochemical properties such as density, viscosity, and physical solubility of N 2 O, required in the interpretation of absorption rate experiments, were determined separately. The obtained experimental reactive absorption fluxes were interpreted, using the pseudo-first-order approach, into intrinsic reaction kinetics. The potassium-based solvent showed, on average, a 32% higher reactivity toward CO 2 than the sodium equivalent. The kinetic data were correlated in a power-law reaction rate expression. The reaction order with respect to the amino acid was found to be between 1.40 and 1.44 for both L-prolinate salts, and the second order kinetic rate constant, k 2 , was calculated for the potassium salt to be 93.7 × 10 3 dm 3 ·mol −1 ·s −1 at 298 K with an activation energy of 43.3 kJ·mol −1 . L-Prolinate salts show higher chemical reactivity toward CO 2 than most of the aminoalcohols and amino acid salts.

Recent progress and new developments in post-combustion carbon-capture technology with amine based solvents

“…However, it was reported that using K provides a higher reactivity toward CO 2 than using Na (Majchrowicz et al, 2014). Amino acid salts have drawn a lot of attention from researchers in the field of CO 2 capture due to their many advantages.…”

Characteristics of Potassium Prolinate + Water + Ethanol Solution as a Phase Changing Absorbent for CO2 Capture

“…Only regenerating CO 2 -rich phase can reduce the evaporation of solvents and energy consumption. 5,6 Researchers have invested great interest for aqueous amino acid salts (AAS) and their precipitating systems (such as potassium of sarcosine, 7−11 lysine, 12,13 and proline 7,10,14,15 ) as alternative solvents, since AAS have fast kinetics with CO 2 , along with good properties such as good resistance to oxidation and low toxicity. However, the promising process using precipitating amino acid solvents for CO 2 capture has a limiting window of operation, where solid precipitation only occurred at higher concentrations and CO 2 partial pressures, for example, 4.0 M for potassium sarcosinate and 3.5 M for potassium prolinate at 293 K and 11.0 kPa CO 2 partial pressure.…”

“…16,17 Physicochemical properties are essential for kinetics of CO 2 absorption, simulation, and design of capture process. The solubility of CO 2 in aqueous amino acid salts such as lysinate, 12,13,18 prolinate, 12,14,15,19 and sarcosinate 9,10,20 has been widely reported recently. However, the data of density, viscosity, and CO 2 solubility for ProK/W/ Eth solutions have not been reported yet in literature.…”

Chemical kinetics of carbon dioxide in the blends of different amino acid salts and methyldiethanolamine

“…To design a CO 2 absorption plant that can accommodate the CO 2 ‐AAS systems, knowledge of their reaction kinetics is imperative. A number of researchers have studied the reactions kinetics of CO 2 with different AAS and found their kinetics to be comparable to that of the conventional amines 14‐19 …”

“…A number of researchers have studied the reactions kinetics of CO 2 with different AAS and found their kinetics to be comparable to that of the conventional amines. [14][15][16][17][18][19] Potassium salts of Glycine (KGly), a typical amino acid salt has generated significant interest as an alternative solvent for CO 2 capture. Structurally, it consists of a potassium ion connected to an amino carboxylic group ( Figure 1B).…”