ISBN 9783843935562

978-3-8439-3556-2, Reihe Verfahrenstechnik

Mathias Leimbrink
Enzymatic Reactive Absorption

270 Seiten, Dissertation Technische Universität Dortmund (2018), Softcover, A5

Zusammenfassung / Abstract

CO2 capture technologies are considered as an important prerequisite to substantially reduce industrial CO2 emissions. Reactive absorption with monoethanolamine represents the state of the art technology, but its deployment is limited because of energy-intense solvent regeneration. While alternative solvents like tertiary amines can overcome these drawbacks, slow reaction rates constitute a new challenge. One approach to increase reaction rates is mixing with fast-absorbing amines, e.g., piperazine, but the favorable thermodynamic properties are impaired.

Concerted process intensification is enabled by enzymatic reactive absorption, using the enzyme carbonic anhydrase, because reaction rates are accelerated while conserving favorable thermodynamic properties. Consequently, enzymatic reactive absorption has the potential for a step change in CO2 capture processes, as demonstrated in this work.

The core of the thesis is the experimental investigation of the enzymatic reactive absorption across different scales with respect to identifying and optimizing key operating parameters and exploring different forms of enzyme application. Process analysis, based on validated rate-based models, revealed that low temperatures (25 °C) and a 30 wt.% concentration of the tertiary amine N-methyldiethanolamine are favorable enzymatic operating conditions and allow decreasing the energy requirement to 2.13 MJ per kg of CO2, which is a nearly 40 % improvement compared to the conventionally applied monoethanolamine solvent. Dissolved enzymes showed the highest absorption rates, however immobilized enzyme can offer advantages by allowing continued use of thermal solvent regeneration without damaging the biocatalyst.

In addition, new contacting equipment and innovative materials were considered for process intensification of enzymatic reactive absorption. Substantially more compact and flexible processes were achieved due to enlarged and stabilized volume-specific interfacial area, offering savings in space and capital costs.

A portfolio of innovative and efficient enzymatic reactive absorption processes represents the central achievement of this thesis, serving as a contribution to future development of more energy-efficient and intensified CO2 capture processes.