UNRAVEL – UNique Refinery Approach to Valorise European Lignocellulosics

Lignocellulose represents a large proportion of the renewable raw materials on earth. The full utilization of lignocellulose as a raw material in the bioeconomy requires efficient and flexible processes of fractionation into the components cellulose, hemicellulose and lignin. In the BBI-EU project UNRAVEL, the novel FABIOLA™ organosolv digestion of lignocellulose was piloted for the first time. Acetone is used as the solvent. Compared to ethanol, it can be used at milder temperatures and the energy required for solvent recovery is reduced.

Successful scale-up of the flexible process

The concept was scaled up using the unique integrated pilot plant at Fraunhofer CBP. By integrating a pre-extraction step, it was possible to use complex feedstocks and residual materials such as birch wood with bark and branches or wheat straw. A mix of these raw materials was successfully processed as well. This demonstrated the flexibility of the process, which is a major advantage for industrial implementation.

Reprocessing and utilization of all three fractions

For the precipitation of lignin from the fractionation liquid, a process for continuous precipitation by evaporation of the solvent, patented jointly with the Max Planck Institute for Dynamics of Complex Technical Systems, was successfully transferred to the acetone process. After enzymatic hydrolysis of the cellulose, fermentation of the resulting glucose to acetone was successfully demonstrated on a 100-liter scale. The hemicellulose was fermented to xylic acid. The lignin was tested by the project partners CNRS and Soprema for applications in polyurethane foams and bitumen.

Outlook

The demonstration of the FABIOLA™ process at the CBP pilot plant provided promising results. If the techno-economic evaluation and life cycle assessment of the concept in the project are successful, the stage is set for industrial implementation.