ISBN 9783843918756

978-3-8439-1875-6, Reihe Verfahrenstechnik

Sebastian Heitmann
Membrane-Assisted Downstream Processing for Biobutanol Purification

219 Seiten, Dissertation Technische Universität Dortmund (2014), Softcover, A5

Zusammenfassung / Abstract

The biotechnological manufacturing of biobutanol (n-butanol) offers the possibility to expand the production of bulk chemicals and fuel additives to a renewable basis. A main drawback of this process is the butanol toxicity towards production strains, which limits the product concentrations in the fermentation broth. One method for overcoming this limitation is the application of pervaporation for a continuous product removal from the fermentation. By integrating a fermentation with a pervaporation, butanol can be continuously removed from the fermentation and the fermentation efficiency can be increased.

To evaluate the potential of pervaporation for the separation of butanol from aqueous mixtures, experimental studies were carried out. Membranes made from poly(dimethylsiloxane) and poly(ether block amide) were tested in this study. The influence of important process parameters such as the feed concentration, the temperature and the permeate pressure has been analysed. In addition, the pervaporation of by-products like acetone, ethanol, 1,3-propanediol or butyric and acetic acid was investigated.

Based on the experimental results model-based process analyses were carried out. The economic competitiveness of pervaporation-assisted distillation for butanol recovery processes was assessed and compared with conventional distillation processes. Sensitivity analyses were employed to identify the most important process parameters and to evaluate the impact of by-products on the purification costs. The results of these studies facilitate the identification of future targets for membrane permeabilities and selectivities for butanol, to render a pervaporation-assisted recovery process economically competitive to conventional distillation.

To improve the separation properties of conventional polymeric pervaporation membranes, ionic liquids (ILs) were immobilized in the active separation layer of polymeric membranes. Different concepts for IL immobilization were experimentally analysed. By the immobilization of ILs with tetracyanoborate anion in membranes the advantageous mass transfer properties of these supported ionic liquid membranes (SILMs) relative to polymer membranes have been proven.