Removal of carbon dioxide by absorption into blended amines: kinetics of absorption into aqueous AMP/HMDA, AMP/MDEA, and AMP/piperazine solutions

Abstract

The emissions of anthropogenic carbon dioxide (CO₂) are believed make a significant impact on global climate change. Hence, amine chemical absorption technology has been suggested to separate and recover CO₂. In this study, reaction rate constants between CO₂ and blended amines were determined by measuring their absorption rate for CO₂. The experiments were carried out to investigate the characteristics of CO₂ absorption by using additional absorbents such as hexamethylenediamine (HMDA), N-methyldiethanolamine (MDEA) or piperazine blended into 2-amino-2-methyl-1-propanol (AMP) in an agitated vessel. The absorption rates of CO₂ into aqueous blended amine solutions were measured. Additive concentrations of 1, 3, and 5 wt% were added for each 30 wt% AMP solution. The results showed that the addition of HMDA, MDEA or piperazine into AMP increased the absorption rate as compared to AMP alone. Of these additives, HMDA showed the most enhancement in the reaction rate of AMP. The reaction rate constants of HMDA, MDEA and piperazine blended into AMP at 303–343 K were given by k_H = 3.84 × 10¹⁰exp(−5361/T), k_M = 6.60 × 10⁹exp(−4959/T), and k_P = 9.09 × 10⁹exp(−5058/T), respectively.