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

Abstract

In the present study, the reaction kinetics of carbon dioxide (CO2) with two blends of N-methyldiethanolamine; potassium salts of taurine and potassium salts of glycine were investigated. The experiments were performed using a stopped flow apparatus over a range of temperature varying from 293 to 313 K. The concentration of solution was varied from 0.2 to 0.8M in different proportions of potassium salts of taurine and glycine. For both cases, the overall reaction rate constant (kov) increased with increased temperature and amino acid salts proportions in the blends. Results also indicated that addition amino acid salts (AAS) could improve the overall reaction rate of methyldiethanolamine (MDEA) with CO2 by more than 100 times. The kinetics data were interpreted using the widely accepted mechanisms namely; zwitterion and termolecular mechanisms. An average absolute deviation of 8.8% was observed for both mechanisms applied to MDEA-KTau blend, while an AAD% of 7.4 and 7.2 were observed for the case of MDEA-KGly system when applying the zwitterion and termolecular mechanisms, respectively. The results showed that blends of MDEA and potassium salts amino acids react faster with CO2 compared to conventional amine systems. Hence, the use of both potassium salts of taurine and glycine as rate promotors can significantly enhance the reactivity of MDEA toward CO2.