Determination of the liquid-phase speciation in the MDEA-H2O-CO2 system

AbstractAqueous solutions of alkanolamines are commonly used in CO2 capture processes. To describe these complex processes rigorous mass transfer models are needed, in which all mass transfer, kinetics and thermodynamics are incorporated correctly. To improve the quality of the thermodynamic models, not only commonly used P-α (CO2 partial pressure versus CO2 liquid loading) experimental data, but also liquid phase speciation data are important. Speciation data of amine-H2O-CO2 data are very scarce in literature. In this work speciation data of MDEA-H2O-CO2 have been determined experimentally with a Fourier Transform Infra-Red spectrometer (FTIR) at ambient temperature. After several calibration lines were prepared, the speciation of this system was determined online in the FTIR. The experimental data presented in this work were well in line with speciation from open literature

Kinetics of absorption of carbon dioxide in aqueous amine and carbonate solutions with carbonic anhydrase

<p>In the present work the absorption of carbon dioxide in aqueous N-methyldiethanolamine (MDEA) and aqueous sodium carbonate with and without carbonic anhydrase (CA) was studied in a stirred cell contactor in the temperature range 298-333 K. The CA was present as free enzyme and is compared to the opportunity to immobilise CA on particles and on fixed packing. Based on the results with MDEA and sodium carbonate, the observed kinetics as a function of the free enzyme concentration are described. These results were incorporated into the Procede Process Simulator (Arendsen et al., 2012) to determine the impacts of the kinetic benefit of CA on commercial absorber sizing for carbon dioxide capture from flue gases. Based on simulations performed, CA in the absorption solution can provide substantial benefits for reducing absorber sizing with these normally kinetically limited, but energy efficient solvents. It was also shown that CA immobilised to fixed packing material is not a viable option for using CA in a carbon dioxide capture process. (C) 2012 Elsevier Ltd. All rights reserved.</p>