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A Comparative Study of the CO2 Absorption in Some Solvent-Free Alkanolamines and in Aqueous Monoethanolamine (MEA)

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journal contribution
posted on 13.06.2016, 00:00 authored by Francesco Barzagli, Fabrizio Mani, Maurizio Peruzzini
The neat secondary amines 2-(methylamino)­ethanol, 2-(ethylamino)­ethanol, 2-(isopropylamino)­ethanol, 2-(benzylamino)­ethanol and 2-(butylamino)­ethanol react with CO2 at 50–60 °C and room pressure yielding liquid carbonated species without their dilution with any additional solvent. These single-component absorbents have the theoretical CO2 capture capacity of 0.50 (mol CO2/mol amine) due to the formation of the corresponding amine carbamates and protonated amines that were identified by the 13C NMR analysis. These single-component absorbents were used for CO2 capture (15% and 40% v/v in air) in two series of different procedures: (1) batch experiments aimed at investigating the efficiency and the rate of CO2 capture; (2) continuous cycles of absorption–desorption carried out in packed columns with absorption temperatures brought at 50–60 °C and desorption temperatures at 100–120 °C at room pressure. A number of different amines and experimental setups gave CO2 capture efficiency greater than 90%. For comparison purposes, 30 wt % aqueous MEA was used for CO2 capture under the same operational conditions described for the solvent-free amines. The potential advantages of solvent-free alkanolamines over aqueous MEA in the CO2 capture process were discussed.