The biorefinery

Replacing conventional raw material sources means replacing oil and gas with lignocellulose feedstock (LCF) as the main source of carbon. The estimated annual production of biomass by biosynthesis is 170 billion tonnes, and considering that approximately 75% of this mass is carbohydrate (mainly in the form of cellulose, starches and saccharose), 20% is lignin and 5% consists of other natural substances like fats (oils), proteins and other substances, priority should be given to finding an efficient means of accessing the carbohydrates, and processing them to form chemical staple stock and subsequently a refined product.

The use of sugar and vegetable fat

The research aim at the Fraunhofer ICT is to identify possibilities for the application of sustainable raw materials for the production of organic intermediate products and fine chemicals, and to enable technical implementation. An example of this is the conversion of fructose or glucose to hydroxymethylfurfural (HMF) and 2-furancarboxylic acid, as well as the breakdown of hydrogenated and non-hydrogenated vegetable fats into different fatty acids using water as a preferred solvent. These intermediate products form a basis for a broad field of applications:

In the future, HMF could be an important intermediate product in the manufacture of plastics (elastomers or thermosets), and fatty acids have potential for the production of additives in the plastic industry.

Where oils and fats are broken down, each triglyceride molecule yields one molecule of glycerine and three molecules of fatty acids. Large-scale processes such as the manufacture of biodiesel from rapeseed oil produce, for each 9 kg of biodiesel, approximately 1 kg aqueous crude glycerine as a byproduct, in concentrations < 15%. At the Fraunhofer ICT, process development is already being carried out for the bioconversion of crude glycerine into 1,3-propanediol, acrylic acid or allyl alcohol.

Lignin from lignocellulose has also been investigated; likewise, as yet, in very small quantities. Lignin (lat. lignum = wood) is found in most higher plants, and is a chemical component of the plant cell wall (polyphenol), forming, together with cellulose and polyose, the structure of the wood. The aim of current research at the ICT is to use subcritical and supercritical water to break down this natural polymer into its phenol monomers in a continuous process, enabling its use for example in the field of phenol resins.

Beside cellulose (as a polymer of glucose), chitin (the polymer of glucose acetamide) is also a potential raw material source. Current research in this field is concerned with processes for its targeted break down into monomers, to create a source of natural nitrogen for organic intermediate products.

Together with an industrial partner, the ICT has developed a process for the manufacture of biobased polyol and carboylic acids based on sugar.

New raw materials and new reactor concepts

The use of ultrasound and microwaves represents a new method of applying energy for the resource-efficient conversion of educts. Microwaves heat the reaction mixture, and ultrasound facilitates the emulsification of fat and water, which is necessary for the hydrothermal breakdown of fat. In a project context, the new methods were extensively tested, proving their technical viability. The economic viability of the new processes, another important factor, was also demonstrated. Now, further optimisation of the processes is necessary to enable technical implementation on a large-scale.