Research to Business
Waste separation is the first step towards recycling recyclable waste according to the principle of circular economy. With a new pyrolysis process for chemical plastic recycling, KIT and ARCUS Greencycling Technologies are breaking new ground in recycling mixed plastic waste. (Image: RJA1988 / pixabay.com)
Waste separation is the first step towards recycling recyclable waste according to the principle of circular economy. With a new pyrolysis process for chemical plastic recycling, KIT and ARCUS Greencycling Technologies are breaking new ground in recycling mixed plastic waste. (Image: RJA1988 / pixabay.com)

Making chemical plastics recycling respectable

A pyrolysis process for the chemical recycling of mixed plastic waste has been developed at the KIT Institute for Technical Chemistry. ARCUS Greencycling Technologies GmbH relies on the procedure and is building a first demonstration to get more out of plastic waste in the future.

Since the 1990s, cans, cups and other packaging have been collected with the help of the yellow sack or yellow recycling bin. If recyclables are properly separated, they can be recycled and efficiently save resources as secondary raw materials. (Image: Letiha / pixybay.com)

Around 6 million tons of packaging waste end up in the recycling bin or the so-called yellow sack in Germany every year. 60 percent of this lightweight packaging is already recycled in order to comply with the principle of a circular economy. This means that waste is recycled so that the raw materials used are not lost after usage. Correct waste separation is what makes this recycling cycle for plastic waste possible at all. To achieve even better recycling rates for plastics in the future, KIT researchers have developed a promising solution: Chemical recycling of mixed plastic waste by thermochemical pyrolysis.

Forms of plastics recycling

"In conventional, mechanical recycling, pre-sorted plastic packaging is mechanically processed, leaving the chemical structure unchanged. Suitable for such a process are plastics from the packaging sector or residues from the production of plastic products that can be sorted by type. However, it becomes difficult when plastics cannot be separated by type or are contaminated by pollutants. In these cases, plastic waste has so far been recycled in waste incineration plants, at least for energetic recovery," Prof. Dieter Stapf, head of the Institute for Technical Chemistry (ITC) at KIT, explains the background.

So far, most consumer products do not use homogeneous plastics, but tailor-made materials and subcomponents for the respective application or highly functionalized engineering plastics and composite materials. Sooner or later, however, they all become waste. "This mix of materials in the waste pushes mechanical recycling to its limits. Separating and sorting becomes an unsolvable task and can no longer be achieved economically," explains Dr. Marco Tomasi Morgano. He contributed to the further development of the pyrolysis process during his PhD at KIT and is driving the industrialization of the process as Chief Technical Officer at ARCUS Greencycling Technologies since 2019. Chemical recycling enables plastic mixtures to be fed back into a resource-conserving cycle. Because marketable pyrolysis products, such as pyrolysis oil, are generated at the same time, the process is considered a feedstock recycling process for plastics.

Experimental setup of the screw pyrolysis reactor at the Institute for Technical Chemistry for the production of liquid and gaseous feedstocks from plastic waste that can be reused for chemical and petrochemical processes. (Image: KIT)

Chemical recycling at KIT

In the pyrolysis technical center of the ITC, Stapf's working group has been conducting research on the pyrolysis of a wide variety of organic materials for many years, focusing also on mixed plastic waste. "Recycling has a high impact on climate and resource conservation and encourages our process engineering research. We need solutions now to handle difficult waste," Prof. Stapf says. With their patented screw pyrolysis reactor, the researchers are pioneers in this field. In the special tray screw reactor, mixed plastics with particle sizes below 25 millimeters can be converted into their basic components – solid, liquid and gaseous raw materials – by pyrolysis.

In pyrolysis, the conditioned, previously shredded plastic waste from sorting residues of the yellow bin or from shredding plants for end-of-life vehicles is thermochemically treated with added additives such as sorbents and catalysts. The optimum pyrolysis temperatures and solids retention times in the reactor were determined at the institute for very different plastic mixtures. A special feature of the reactor is the downstream hot gas filtration: pyrolysis gases and vapors can be extracted directly and particle-free. The multi-stage condensation unit, consisting of heat exchangers and electrostatic separators, finally separates the condensable pyrolysis products, such as pyrolysis oil. The continuous reactor operation is largely automatic.

Schematic construction of the tray screw pyrolysis reactor: material feed, pyrolysis reactor with heater, hot gas filter, and condensation unit for gas purification. (Image: ITC / KIT)
Schematic construction of the tray screw pyrolysis reactor: material feed, pyrolysis reactor with heater, hot gas filter, and condensation unit for gas purification. (Image: ITC / KIT)

From experiment to pilot

Since 2018, KIT has been working together with ARCUS Greencycling Technologies GmbH to bring plastic pyrolysis to industrial application. Process engineer Dr. Tomasi Morgano emphasizes, "The process is intended to close the raw material cycle for plastic waste that has not been recyclable so far. I am very motivated by the fact that in my position at ARCUS I can now apply the knowledge I have built up in an industry-related way and contribute towards society in the process." ARCUS develops projects and technologies for the plastic recycling. The reactor technology of KIT therefore ideally complements the portfolio of the company based in Ludwigsburg.

Prof. Stapf specifies: "Within the scope of the cooperation, ARCUS has realized a pyrolysis plant based on KIT technology, with which mixed packaging waste can be recycled on an industrial scale. It was important that their end products are reusable." In order to scale up the existing procedure, some technical modifications were necessary with regard to process control, safety, and logistics. The KIT research team dealt with the technological issues of process engineering; ARCUS, on the other hand, took over the issues of plant construction, economic efficiency, and permission.

The plant developed has a modular design and is intended for decentralized use, e.g. in the vicinity of plants for the mechanical processing of lightweight packaging or commercial waste. ARCUS is currently building a demonstration plant at Industriepark Höchst in Frankfurt am Main, Germany, designed for a planned throughput of about 500 kg/h – including condensation, gas purification and power generation. Tomasi Morgano reports, "The permitting process was very complex because our plant brings together two sectors: waste treatment and chemistry. Therefore, I am glad that the construction is now on schedule." Establishing the process in the market is the declared goal for the coming years, without disregarding new developments such as bioplastics.

Construction of the pyrolysis PDU (Process Development Unit) of ARCUS Greencycling Technologies for the chemical recycling of mixed plastic waste. The demonstration plant is intended to recover raw and recyclable materials in a closed-loop process. (Image: ARCUS Greencycling Technologies GmbH)
Construction of the pyrolysis PDU (Process Development Unit) of ARCUS Greencycling Technologies for the chemical recycling of mixed plastic waste. The demonstration plant is intended to recover raw and recyclable materials in a closed-loop process. (Image: ARCUS Greencycling Technologies GmbH)

Facts & figures of the demonstration plant

  • 4000 Ton/Anno mixed plastic waste for a thermal power of 4.5 MW
  • Approx. 2500 Ton/Anno pyrolysis oil (brand name: ARCUS-Liquids)
  • Voll elektrischer Betrieb (Ofen, Kälte, etc.) für ca. 700 kW installierte elektrische Leistung
  • Gas engines each dual fuel (natural gas and pyrolysis gas) with a total electrical power of 600 kW with natural gas or 500 kW with pyrolysis gas
  • Over 650 measuring points for continuous monitoring, balancing and control of the plant

Extract recyclable raw materials

Pyrolysis is a young method to recover recyclables from plastic waste in a high-quality way and to make the chemical industry climate-neutral without fossil raw materials. The conversion processes in chemical recycling turns waste into liquid, gaseous and solid pyrolysis products: Mainly pyrolysis oils, which replaces natural petroleum as an input material for polymer chemistry. In addition, pyrolysis gases, coke and condensates can be produced as stand-alone products for petrochemical or power generation. "A closed cycle in which all plastic waste can be fully recycled is the ideal state, which still seems unattainable. With our plants, however, we are nevertheless providing a contribution. Every new recycling option is a step towards a better circular economy," summarizes process engineer Tomasi Morgano, looking forward with confidence to the initial operation of the demonstration plant.

Kontakt

Honored with the Lothar Späth Award 2021
With their modular plant concept for chemical plastics recycling, which is based on a pyrolysis process developed by KIT, the cooperation partners Arcus Greencycling Technologies and KIT became the second winner of the Lothar Späth Award on November 18, 2021. The award honors cooperative innovation partnerships between scientific institutions and commercial enterprises in Baden-Württemberg. The cooperation partners were awarded for recycling plastics as a raw material in the sense of the carbon cycle economy.

Dr. Daniela Späth-Zöllner, member of the jury and daughter of Lothar Späth, is pleased as laudator with the second place winners. From left to right: Dr. Daniela Späth-Zöllner, Julian Odenthal (Head of Business Development ARCUS Greencycling Technologies GmbH), Paulina Dyczewska (Process Engineer, ARCUS Greencycling Technologies GmbH), Daniel Odenthal (Founder ARCUS Greencycling Technologies GmbH), Prof. Dr.-Ing. Dieter Stapf (KIT), Dr. Ing. Marco Tomasi Morgano (Chief Technology Officer ARCUS Greencycling Technologies GmbH). (Image: Klaus Hepp)
Dr. Daniela Späth-Zöllner, member of the jury and daughter of Lothar Späth, is pleased as laudator with the second place winners. From left to right: Dr. Daniela Späth-Zöllner, Julian Odenthal (Head of Business Development ARCUS Greencycling Technologies GmbH), Paulina Dyczewska (Process Engineer, ARCUS Greencycling Technologies GmbH), Daniel Odenthal (Founder ARCUS Greencycling Technologies GmbH), Prof. Dr.-Ing. Dieter Stapf (KIT), Dr. Ing. Marco Tomasi Morgano (Chief Technology Officer ARCUS Greencycling Technologies GmbH). (Image: Klaus Hepp)

comments about this article

No comments

Write a comment

* These fields are required

Remember offer

No offers listed yet

This site uses third-party website tracking technologies to provide its services. I agree to this and can revoke or change my consent at any time with effect for the future.

Settings Refuse AcceptLegal NoticePrivacy Policy