© Fraunhofer CBP

Product separation and downstream processing

This area includes the process engineering development of processes for the processing of product mixtures and is, by its very nature, closely linked to the other research areas at Fraunhofer IGB and CBP.

For customer-specific applications, new tailor-made downstream processes are developed, scaled and evaluated. In doing so, we evaluate and optimize the industrial feasibility of the processes already on a laboratory scale.

Example: Separation and purification of furan derivatives from coupling streams containing lignocellulose#

Two-phase mixture of water and furfural
© Fraunhofer CBP
Two-phase mixture of water and furfural (right), obtained by depolymerization of lignocellulose and separation by distillation.

Biobased furan derivatives, such as 2,5-furandicarboxylic acid (FDCA), are increasingly gaining in importance, in particular as biogenic building blocks for polymer applications. The Fraunhofer Center for Chemical-Biotechnological Processes CBP is conducting intensive research into the separation and purification of furan derivatives from process water of the hydrothermal conversion of raw materials containing lignocellulose, using a variety of thermal, mechanical and physico-chemical separation methods. Intensive research and development has been carried out in projects including those funded by the German Federal Ministry of Education and Research (BMBF), ”KomBiChemPro” and ”BBChem”, and the project ”SteamBio”, funded by the EU.

 

Separation by cross-flow membrane filtration

We use cross-flow membrane systems to separate off the dissolved and undissolved constituents. The aim is to separate polymers from monomers and to reduce the water content to optimize the purification process energetically. Cross-flow membrane filtration also plays a central role in the separation of temperature-sensitive substances, such as 5-hydroxymethylfurfural (5-HMF) and formic acid. Furfural derivatives can also be successfully separated from the process water using rectification, which we have demonstrated at the pilot scale with a throughput of 2.5 kg/h. Investigations into liquid-liquid extraction and adsorption/desorption revealed targeted separation of the carboxylic acids from furan derivatives. In this case, we were able to successfully demonstrate the essential feasibility of separating furan derivatives in process waters from hydrothermal conversion up to the 100-liter scale.

Tubular ceramic membrane
© Fraunhofer CBP
Tubular ceramic membrane in the cross-flow membrane system.
Flat-sheet membrane module
© Fraunhofer CBP
Flat-sheet membrane module in the cross-flow membrane system.
Product sample
© Fraunhofer CBP
Product samples purified from process water using a polymer membrane, from left to right: educt sample, permeate, concentrate.

Reference projects#

 

KomBiChemPro – fine and platform chemicals from wood by combined chemical-biotechnological processes

The aim is to combine various development activities for the material use of lignocellulose-containing biomass in an integrated biorefinery concept.