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Kinetics of Carbon Dioxide Absorption into N-methyldiethanoloamine Solutions
| Content Provider | Semantic Scholar |
|---|---|
| Author | Pohorecki, Ryszard |
| Copyright Year | 2002 |
| Abstract | The kinetics of carbon dioxide absorption in aqueous solutions of N-methyldiethanoloamine (MDEA) as well as in aqueous solutions mixtures of MDEA and 2-ethylaminoethanol (EAE) has been investigated. Measurements of the absorption rate were carried out in a stirred vessel of known interfacial area under atmospheric pressure at the temperature of 20°C. The ranges of parameters used were as follows: stirrer speed: 40 – 80 rpm; concentration of MDEA: 10, 20 and 30 mass %; concentration of EAE: 5, 10 and 15 mass %. The values of the reaction rate constant between CO2 and MDEA were determined and compared with the literature data. It was found that the addition of EAE significantly increases the absorption rate. INTRODUCTION Absorption methods are the most wide-spread in commercial practice of industrial gas purification. CO2 and H2S removal methods are of special importance because these compounds are present as impurities in many gaseous mixtures. A number of gas purification processes using absorption methods exists. These processes are based on either physical dissolution of gases in liquids or on dissolution combined with chemical reaction in the liquid phase. The cost of purifying a gaseous mixture is generally very high. In the ammonia production the synthesis gas contains considerable amounts of CO2 (10 – 20%). For the removal of CO2 from those gas BENFIELD process is most wide-used. In this process CO2 is absorbed into aqueous NaHCO3/Na2CO3 solutions, containing diethanolamine (DEA) at temperature 70 115°C and under elevated pressure (2.0 – 2.5 MPa). Our earlier works [1-4] were aimed at improving this process and making it more effective economically and technically. BASF developed a method of the removal of CO2 from the synthesis gas using aqueous N-methyldiethanolamine (MDEA) solutions, containing suitable activator (also amine) [5]. Many studies on the kinetics of the reaction of CO2 in aqueous MDEA solutions have been reported, but there are still some discrepancies as to the values of the reaction rate constant and at to the influence of the amine concentration on these values. The aim of the present work was to determine the values of the reaction rate constant in the system: CO2 – aqueous MDEA solutions. As the first step, measurements of the kinetics of CO2 absorption into aqueous MDEA solutions were carried out in a stirred vessel. The measurements of the absorption of CO2 into aqueous MDEA solutions containing 2-ethylaminoethanol (EAE) were also carried out. The investigations presented here are a part of a wider research program aimed at developing new absorbents for the removal of CO2 from the synthesis gas in the industrial process of the ammonia production. KINETICS OF CO2 ABSORPTION INTO AQUEOUS ALKANOLAMINE SOLUTIONS Danckwerts [6] reintroduced the reaction mechanism proposed originally by Caplow [7] which describes the reaction between CO2 and primary or secondary alkanolamines via the formation of a zwitterion followed by the removal of the proton by a base, B (the base may be water or OH ̄): |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://folk.ntnu.no/skoge/prost/proceedings/distillation02/dokument/1-5.pdf |
| Alternate Webpage(s) | http://www.nt.ntnu.no/users/skoge/prost/proceedings/distillation02/dokument/1-5.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
