The Kinetics Investigation of CO2 Absorption into TEA and DEEA Amine Solutions Containing Carbonic Anhydrase

Tertiary amines have been used as alternative absorbents for traditional primary and secondary amines in the process of carbon capture. However, the carbon dioxide (CO2) absorption rates in these kinds of amine are relatively slow, which implies greater investment and construction costs and limits the large-scale application of carbon capture. Carbonic anhydrase (CA) is considered to be an ideal homogeneous catalyst for accelerating the rate of CO2into aqueous amine solution. In this work, CO2absorption combining CA with two single aqueous tertiary amines, namely triethanolamine (TEA) and 2-(diethylamino)ethanol (DEEA), was studied by use of the stopped-flow apparatus over temperature ranging from 293 to 313 K. The concentrations of selected aqueous amine solution and CA used in the experiment were ranging among 0.1–0.5 kmol/m3and 0–50 g/m3, respectively. Compared to the solution without the addition of CA, the pseudo first-order reaction rate in the presence of CA (k0,withCA) is significantly increased. The values ofk0,withCAhave been calculated by a new kinetics model. The results of experimental and calculatedk0,amineandk0,withCAin CO2-amine-H2O solutions were also investigated, respectively.Keywords:carbon capture;CO2absorption;carbonic anhydrase;reaction kinetics