Downstream processing

The field of downstream processing includes the development of processes for separation and purification of product mixtures and is naturally closely interrelated with the other areas at Fraunhofer CBP.

New tailor-made processing methods for the separation and purification are developed, scaled-up and evaluated to provide customized applications.

Current R&D topics

  • Production of high-quality extractives from secondary and side streams of the renewable raw materials processing process industry by liquid-liquid extraction with organic solvents or at high pressures with liquid propane and supercritical carbon dioxide
  • Downstream processing of fermentation solutions and extraction of fine chemicals
  • Extraction of organic components from process streams through extraction / distillation, filtration
  • Separation and purification of furan derivatives from lignocellulosic coupling streams
  • Extraction of high-quality substances from algal biomass

Range of services

Downstream processing and product conditioning are a decisive factor in the efficiency of the entire process chain and at Fraunhofer CBP these are integrated directly into the process development as unit operations.

Our step-by-step approach covers the conception of suitable processes, the simulation and modeling of separation processes via ASPEN and their representation on the technical and pilot scale. At the same time the industrial practicability of the processes is already evaluated at the laboratory scale and then optimized.

These trials enable us to make product samples available to our partners and customers for technical application tests.

In parallel to the process, analytical methods are employed to evaluate the material composition of the product solutions.



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


Research Infrastructure


Chemical and combined processes