Downstream processing

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

Current issues

  • Extraction of phytosterols from side streams of pulp production by means of liquid-liquid extraction with organic solvents or under high pressures with liquid propane and supercritical carbon dioxide
  • Extraction of organic components from process wastewater by thermochemical conversion of biomass and subsequent extraction / distillation
  • Development of alternative fractionation and separation methods for the extraction of recyclable materials from oil seed
  • Downstream processing of fermentation solutions and extraction of fine chemicals
  • Extraction of high-quality substances from algal biomass

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