Reactive Absorption of CO2 into Aqueous Mixtures of Methyldiethanolamine and Diethanolamine

Abstract

Abstract-The effect of mixing a tertiary amine, N,N-Methyldiethanolamine (MDEA), with a secondary amine, diethanolamine (DEA), on the kinetics of the reaction with carbon dioxide in aqueous media has been studied in a stirred cell reactor with a plane, horizontal gas-liquid interface. Temperature was varied from 293 to 313K over a range of blend composition and total mixture concentration ranging from one to two molars. The proposed model representing the reaction of CO 2 with the blends studied is found to be satisfactory in determining the kinetics of the involved reactions. This model is based on the zwitterion mechanism for the DEA and water hydration catalysis for MDEA. Blending MDEA with DEA results in observed pseudo-first-order reaction rate constant values (k o ) that are greater than the sum of the k o values of the respective single amines. This is due to the role played by MDEA in the deprotonation of the zwitterion of the other amine (DEA). Species concentration profile needed to fit the experimental data to the model to extract the kinetic parameters associated with the reactions was calculated using the modified Deshmukh-Mather model.

Piperazine and methyldiethanolamine interrelationships in CO2 absorption by aqueous amine mixtures. Part I: Saturation rates of single‐reagent solutions

“…Blended aminic absorbents containing MDEA have seen growing interest because they can combine the desirable properties of the individual components, in particular the high rate of reaction of the primary or secondary amine and the low enthalpy of reaction of the tertiary amine; for example, MEA/MDEA or DEA (diethanolamine)/MDEA mixed absorbents have been studied. In these cases, primary or secondary amine concentration compared to MDEA concentration has to be quite high to have a notable enhancement in the CO 2 absorption rate.…”

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

“…Contrary to the observed reaction order, Kumar et al 12 reported the reaction order for potassium salts to be in the range of 1 to 1.5 at 285 to 305 K. This high reaction order observed for both KTau and KGly in blended solutions indicates the effect of multiple bases in the deprotonation of the zwitterion. 34 Hence, the observed experimental pseudo-first-order rate constants were then analyzed using both the zwitterion and termolecular mechanisms.…”

Reaction Kinetics of Carbon Dioxide in Aqueous Blends of N-Methyldiethanolamine and L-Arginine Using the Stopped-Flow Technique

“…The promoting effect of L-Arginine investigated in this work was also compared with that of the available data of MDEA-Glycine [42] and MDEA-DEA [58] systems at different temperatures and at the same overall concentration (1 M) as shown in Figure 13. For all three compared systems, the same 0.1 M of the promoter was added.…”