ISBN 978-3-8439-2444-3

978-3-8439-2444-3, Reihe Verfahrenstechnik

Anna-Katharina Kunze
Intensified reactive absorption processes for CO2 separation using enzyme accelerated solvents

221 Seiten, Dissertation Technische Universität Dortmund (2015), Softcover, A5

Zusammenfassung / Abstract

CO2 capture is one approach to reduce anthropogenic CO2 emissions. State of the art is reactive CO2 absorption using the solvent monoethanolamine, but the high energy amount for solvent regeneration and the formation of harmful degradation products make process intensification for CO2 separation necessary. This work approaches process intensification for CO2 separation by applying a biocatalyst, namely the enzyme carbonic anhydrase, to accelerate the rate determining reaction in reactive CO2 absorption using potassium carbonate and methyldiethanolamine.

First, laboratory scale experiments showed chemical capability of these enzyme accelerated reactive solvents. The operating window in terms of temperature and pH influence on performance and stability of carbonic anhydrase dissolved in the solvents was defined. Second, a packed absorption column at pilot plant scale was standardised in terms of hydrodynamics and mass transfer performance. Third, the technical feasibility of enzyme accelerated reactive solvents in industrially relevant absorption equipment was shown in this pilot plant. The enzyme performance was not limited by the technical equipment. Furthermore, no undesired side effects like foaming, aggregation or precipitation were observed. Therewith, the transfer of carbonic anhydrase performance for CO2 capture from laboratory scale to pilot scale was demonstrated successfully. A rate-based process model was set up and validated based on systematic mass transfer measurements. Finally, scenarios in which the conceptual process design supports the application of carbonic anhydrase in reactive absorption were investigated, e.g. enzyme immobilisation in the absorber, phase separation in a CO2 rich and lean stream after the absorber as well as gas membrane application.

This thesis demonstrates the application of enzymes in reactive absorption processes and displays strategies of carbonic anhydrase integration in the process beyond solvent substitution. Thus, this works contributes to the process maturity of the application of enzymes, here carbonic anhydrase, in reactive absorption and in fluid separations in general.