Abstract
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 CO2 into aqueous amine solution. In this work, CO2 absorption 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/m3 and 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 of k0,withCA have been calculated by a new kinetics model. The results of experimental and calculated k0,amine and k0,withCA in CO2-amine-H2O solutions were also investigated,respectively.
Highlights
IntroductionCarbon dioxide (CO2 ) absorption using chemical absorption with traditional aqueous amine solution, such as monoethanolamine (MEA) and diethanolamine (DEA), is a terminal processing technology that can be deployed on a large scale in coal-fired power plants [1]
Carbon dioxide (CO2 ) absorption using chemical absorption with traditional aqueous amine solution, such as monoethanolamine (MEA) and diethanolamine (DEA), is a terminal processing technology that can be deployed on a large scale in coal-fired power plants [1].there are a number of existing drawbacks, such as very high energy consumption during CO2 desorption process [2]
The kinetic constants under the catalysis of Carbonic anhydrase (CA) were investigated and the results showed that the pseudo first-order reaction rate (k0,amine ) catalyzed by CA is significantly increased as compared to the absence of CA
Summary
Carbon dioxide (CO2 ) absorption using chemical absorption with traditional aqueous amine solution, such as monoethanolamine (MEA) and diethanolamine (DEA), is a terminal processing technology that can be deployed on a large scale in coal-fired power plants [1]. With the deepening of research, tertiary amines such as methyldiethanolamine (MDEA), triethanolamine (TEA) and 2-(diethylamino)ethanol (DEEA) were proposed as alternative solvents for MEA due to their lower energy consumption for carbon capture [5]. Though there is lower energy consumption for the desorption process in these kinds of tertiary amine solvents, the relatively slow absorption rate of CO2 in the absorber means that the better absorber is needed to meet the demand for carbon capture. The experimental kinetics data of CO2 with aqueous amine solution catalyzed by CA over temperature ranging from 293 to 313 K were collected. A new kinetics model of CA-catalyzed absorption of CO2 in aqueous tertiary amine solutions was established and used to compare with experimental date
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