Carbon recycling: Fraunhofer integrates research group

Carbon is a key raw material for countless everyday products. To date, the industry has largely utilised fossil raw material sources such as crude oil, natural gas or coal. Large quantities of CO₂ are released both during the production of these raw materials and at the end of the product's life when it is burnt. According to the Fraunhofer Institute for Ceramic Technologies and Systems (Fraunhofer IKTS), Germany alone burns around 47 million tonnes of this carbon-containing waste every year in thermal waste treatment and incineration plants. Thanks to precisely harmonised combinations of chemical recycling processes, up to 100 % of this waste should be recyclable and usable in new products in the future. This will turn waste into a valuable source of raw materials, for example for basic materials in the chemical industry.

At the new IKTS site in Freiberg, chemical recycling processes such as pyrolysis or gasification are being optimised and tested on a large technical scale. Plastics that cannot be mechanically recycled, biomass or mixed fossil waste are broken down into smaller molecules so that they can be reused as synthesis gases, monomers or other intermediate products in the chemical industry. To this end, the researchers operate a pyrolysis platform at the site and - in cooperation with the TU Bergakademie Freiberg - gasification plants to investigate various issues: Which waste fractions can be converted into which type of base materials? How do the processes have to be run in order to avoid corrosion or caking or to achieve a certain purity of the products? And finally, there is also the question of economic efficiency. In this way, various technologies can be adapted, evaluated and transferred into customer-specific solutions for the closure of carbon cycles for industrial partners.

These competences are to be expanded in the future. Prof Martin Gräbner, head of the new field office in Freiberg and professor of energy process engineering and chemical engineering at the TU Bergakademie Freiberg, explains: „We want to enable the most CO₂ low-emission, efficient and resource-conserving utilisation of carbon sources in the future. The basis for this must be electricity generated from renewable sources, for example in the form of green hydrogen via special synthesis processes. This is where we optimally tie in with the expertise at IKTS.

If the aforementioned recycling processes are combined with electrochemical conversion processes such as high-temperature electrolysis or synthesis processes such as Fischer-Tropsch synthesis, higher-quality products such as synthetic paraffin could be produced on the one hand and high efficiency levels could be achieved on the other.

Only the coupling of material, energy and heat flows in total would lead to process concepts that offer significant added value compared to previous approaches. Prof Alexander Michaelis, Institute Director of Fraunhofer IKTS, is delighted with the addition in Freiberg and describes the associated potential: „IKTS has many years of experience with technologies for hydrogen production and utilisation. Here, high-temperature electrolysis and Fischer-Tropsch synthesis are absolute core technologies. With the expanded expertise in the field of carbon cycle technologies, we are now in a position to provide new raw material and energy resources for a large industry.“

Mitteilungen Fraunhofer IKTS vom 12.01.2023