Lignocellulose biorefinery

One focus in the field of biomass fractionation is on the pulping of lignocellulosic raw materials and their fractionation into their basic chemical components, lignin and sugar or fiber.

For the research and development of processing and fractionation technologies, a specially developed integrated pilot plant is available that enables pulping with organic solvents under increased pressures and temperatures, the so-called Organosolv technology.

Integrated pilot plant for pulping of lignocellulose

lignocellulose biorefinery pilot plant
© Fraunhofer CBP / Norbert Michalke
The pilot plant in Leuna is dismantling wood in its components.

The plant reproduces a large number of individual process steps for the production of fibrous materials, concentrated sugar solutions and lignin. Up to 70 kilograms of wood or 20 kilograms of stalks can be processed per batch. The facility was designed in such a way that the material and energy cycles are closed and therefore mass balances can be determined.


Organosolv process and products

The pilot plant includes a digester to separate the pulp from lignin and hemicellulose. The liquid phase is treated using a patented distillation process to precipitate the lignin.

The Organosolv lignin obtained has high-grade properties, making it suitable for applications in pharmaceuticals or cosmetics, among others.

The remaining hemicellulose solution can be further processed by hydrolysis and the resulting sugar solution concentrated by evaporation to be used in fermentation as a nutrient for microorganisms or as a raw material for biofuels.


Thermal processing of different raw materials through universal design

Due to the universal design of the pilot plant, other pulping processes for lignocellulose can be optimized on a pilot scale in addition to the Organosolv process, e.g. aqueous hydrolysis and digestion using acid or the soda process. The process is fully automated and data documented for balancing the processes.

By using individual process engineering units in the plant, questions in the area of thermal separation technology and extraction can also be dealt with. There is strong interaction here with the "Downstream processing" field of competence.

Range of services

With our flexibly operable pilot plant and excellent equipment for conversion and processing procedures, we develop and scale biotechnological and chemical processes for the utilization of wood components up to application-relevant dimensions and support small and medium-sized companies in particular for faster product development and market launch.

  • Development and piloting of digestion processes for lignocelluloses
  • Recovery of lignocellulosic ingredients (extractives, hemicellulose, lignin, cellulose) with specific properties
    • Provision of organosolv lignin for e.g. thermoplastics, carbon fibers, but also cosmetic applications
    • Oxidation or base-catalytic cleavage of lignin (including organosolv lignin, kraft lignin) to aromatic monomer and oligomer building blocks
    • Provision of fibrous material, for example for the production of fiber composites
    • Extraction of other plant constituents such as bark extractives

Fractionation of lignocellulose with the Organosolv process

Simplified flow chart of the lignocellulose biorefinery pilot plant in Leuna.

Pilot plant process control

The core processes that can be represented in the pilot plant are shown in the simplified plant diagram. First lignocellulose is pulped in a 400-liter reactor at up to 200°C, whereby lignin and hemicelluloses dissolve in the solvent-water mixture.

The additional tanks and heat exchangers in the tank farm permit an efficient fractional washing of the feedstock under reaction conditions and the recovery of energy in the pulping process.

From the fractionation solution enriched with lignin and hemicelluloses, lignin is precipitated by adding water or distillation of the solvent, filtered off and, after washing, dried. The solvent used is recovered completely from the filtrate and the hemicellulose sugars remain as an aqueous solution.

The organic solvent used is recovered completely from the filtrate and the hemicellulose sugars remain as an aqueous solution. The solid, fibrous residue of the fractionation is isolated and washed, dewatered and, if necessary, enzymes are added and saccharified in specially designed stirred reactors at a high fiber concentration. After a filtration stage a glucose solution is obtained which is concentrated into a syrup to stabilize it.