Reaction and separation techniques

Research work on reaction and separation techniques covers thermal, mechanical and chemical processing, with a particular focus on the separation of individual components and the manufacture of new products, for example via chemical reactions. The group offers the possibility of performing preliminary tests in vitro and/or on various plants, to demonstrate fundamental feasibility and carry out optimizations on this basis.

Membrane processes

Membrane filtration ranges from microfiltration through to reverse osmosis, from the laboratory scale up to 300 l units, and from dead end to cross flow. One potential application is water purification: depending on the membrane, larger particles or ions can be separated.

 

Rectification and distillation

A wide variety of equipment is available for the concentration of individual components. For example, high-temperature rectification is used to fractionate tall oil, enabling the separation of fatty and resin acids.

 

Extraction

One topic in this research area is separation through the addition of carbon dioxide, either as a supercritical fluid or in an aqueous solution. Examples of extraction using carbon dioxide include the extraction of organic binding agents from components or the extraction of phosphate from biosolids using carbonated water.

 

Crystallization

Crystallization is often a suitable process for obtaining a particularly high purity of more than 99.9 percent. When mixtures of substances cannot be sufficiently separated due to their solubility properties, similar boiling points or azeotropes, crystallization is an alternative method to achieve the desired separation.

 

Chemical reaction technology

Various reactions are investigated by adding catalysts or different fluids, or by increasing the pressure or temperature. One example is the cleavage of fats and oils. Biobased polymers can be synthesized from the resulting monomers.

 

The biorefinery – material recycling of renewable raw materials

Emphasis is placed on the extraction of lignin, hemicellulose and cellulose from wood fibers (lignocellulose) using the organosolv process, and the break-down of the lignin into phenol fractions. Work is also carried out on the synthesis of sugar derived products such as 5-HMF and furan dicarboxylic acid.

 

Hydrogenation and oxidation

Various high-pressure units at the Fraunhofer ICT enable hydrogenation or oxidation reactions to be carried out. For example, the hydrogenation of sugars enables the synthesis of sugar polyols, which can then act as cross-linking agents in polyurethane systems (e.g. rigid polyurethane foams).

 

Purification of tarry synthesis gases

CO/H2-rich synthesis gas obtained from biomass contains undesirable by-products such as tars. These tars can be catalytically transformed by a molten salt reactor, significantly reducing the tar content. Investigations of these transformation reactions are currently being carried out in a pilot plant in collaboration with the European Institute for Energy Research (EIFER).

 

Supercritical CO2 as a reaction and extraction medium

The decaffeination of coffee, the extraction of herbal substances or the degreasing of surfaces are just a few examples of the application of supercritical CO2 as a solvent. When highly exothermic reactions or reactions with oxidizing materials are carried out, the reaction in supercritical CO2 can be an attractive alternative to conventional syntheses.