Chemistry in the cycle
A chemical industry that does not use fossil raw materials would avoid greenhouse gas emissions and waste. A circular economy in chemical production could achieve this goal. At the Max Planck Institute for Dynamics of Complex Technical Systems in Magdeburg, scientists are supporting this transformation with numerous projects.
Replacing fossil fuels with renewable alternatives could halt and perhaps even reverse the rise in CO2 concentrations in the atmosphere. Such defossilization is not synonymous with decarbonization, i.e., a move away from carbon-based products. CDS spokesperson Prof. Dr.-Ing. Sundmacher and his research group are working on various projects to keep the carbon contained in plastics, paints, and aviation and shipping fuels in the cycle.
In the future circular economy, intelligent process systems will manufacture products from renewable (biogenic) residues and plastic waste. Carbon dioxide will be captured from exhaust gases or extracted from the air and fed into chemical reactors, rather than further driving global warming as a greenhouse gas. Plastics recycling is another important part of the new circular economy. Currently, the majority is used for energy recovery, i.e., incinerated to generate heat. True chemical recycling has so far been virtually nonexistent. Kai Sundmacher and his team are working on improving the breakdown of plastic mixtures. "We are working on selectively extracting individual plastics from mixtures," explains Ruben Goldhahn, a scientist at the Magdeburg Institute.
The use of residues from renewable resources as raw materials is important to Kai Sundmacher to prevent further agricultural land from having to be reserved for the chemical industry. Lignin is one of these residues. It is left over from the processing of wood into pulp. This macromolecule is a source of aromatic compounds that have a wide variety of uses in chemistry, including in the synthesis of adhesives and plastics. "We are working on a process to extract lignin from the biomass before pulp production and to separate it from the other wood components, cellulose and hemicellulose," explains CDS member Hon. Prof. Dr. Liisa Rihko-Struckmann, who heads the "Life Cycle Assessment" team in Sundmacher's department.
Another current focus of the department is the use of CO2 as a raw material in the production of methane from CO2 and green hydrogen, which is produced through water electrolysis using electricity from renewable sources. This process releases a lot of heat, so temperature management is crucial, as it can't get too cold. To predict the temperature development in the reactor of this power-to-X process , a digital twin was developed. This virtual model of a reactor and its processes, which exchanges data with the plant but always stays slightly ahead of it.
CDS Director Prof. Dr. Peter Benner, with his Department of Numerical Methods in Systems and Control Theory, is significantly involved in the development of the digital twin. "Thanks to data-driven methods, we are increasingly finding dynamic models for such twins, allowing us to optimize, monitor, and control technical systems in real time," says the mathematician.
Computer-aided modeling is also necessary for the green transformation of chemistry. One of these models, developed by the group led by CDS spokesperson Prof. Dr.-Ing. Achim Kienle, focuses on the optimal biotechnological production of so-called polyhydroxyalkanoates (PHAs). These PHAs are a particularly sustainable alternative to plastics because they can be produced from biobased sources and are also biodegradable.
Kai Sundmacher envisions that the future of German chemical production will see waste as valuable materials for a chemical recycling economy.
To the official press release of the Max Planck Institute Magdeburg