Hundreds of millions of tonnes of plastic waste are generated worldwide every year. Scientists are working tirelessly on new methods to recycle a large proportion of this waste into high-quality products, and thus enable a genuine circular economy. However, current recycling practices fall short of this goal. Most plastic waste is recycled mechanically: shredded and then melted down. Although this process does result in new plastic products, their quality deteriorates with each recycling step.

An alternative to this is chemical recycling, which avoids loss of quality. This method involves breaking down long-chain plastic molecules (polymers) into their fundamental building blocks (monomers), which can be reassembled into new, high-quality plastics, creating a truly sustainable cycle.

Fuels from plastic waste

As the approach of chemical recycling develops, the initial focus is on breaking down these long polymer chains into shorter-chain molecules that can be used as liquid fuels, say, or lubricants. This gives plastic waste a second life as petrol, jet fuel or engine oil. Scientists at ETH Zurich have now laid down important foundations for developing this process. These enable the global scientific community to engage in more targeted and effective recycling development work.

Researchers in the group led by Javier Pérez-Ramírez, Professor of Catalysis Engineering, investigated how to break down polyethylene and polypropylene with hydrogen. Here, too, the first step is to melt the plastic in a steel tank. Gaseous hydrogen is then introduced into the molten plastic. A crucial step involves adding a powdered catalyst containing metals such as ruthenium. By carefully selecting a suitable catalyst, researchers can increase the efficiency of the chemical reaction, promoting the formation of molecules with specific chain lengths while minimizing by-products such as methane or propane.

Rotational speed and geometry are key

“The molten plastic is a thousand times thicker than honey. The key is how you stir it in the tank to ensure the catalyst powder and hydrogen get mixed right through,” explains Antonio José Martín, a scientist in Pérez-Ramírez’s group. Through experiments and computer simulations, the research team demonstrated that the plastic is best stirred using an impeller with blades parallel to the axis. Compared to a propeller with angled blades or a turbine-shaped stirrer, this results in more even mixing and fewer flow vortices. The stirring speed is equally crucial. It must be neither too slow nor too fast; the ideal speed is close to 1,000 revolutions per minute.

The researchers successfully developed a mathematical formula to describe the entire chemical recycling process with all its parameters. “It’s every chemical engineer’s dream to have a formula like this at hand for their process,” Pérez-Ramírez says. All scientists in the research field can now precisely calculate the effect of the stirrer’s geometry and speed.
With this formula, future experiments can focus on directly comparing different catalysts with the influence of mixing under control. In addition, the principles developed here are central for scaling up the technology from the laboratory to large recycling plants. “But for now, our focus remains on researching better catalysts for the chemical recycling of plastics,” Martín says.

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It enables the reuse of plastic waste that is too complex to process using mechanical recycling methods, but too valuable to dispose of. In chemical recycling, plastics are broken down into their chemical components and used as raw materials for the production of new plastics. This helps to reduce the consumption of fossil resources and prevent environmental pollution from plastic waste. At IFAT, Vecoplan informed experts about the measures it intends to take to intensify its expertise in this area in the long term and entered into a close strategic partnership with Pla.to Technology.

Pla.to Technology, based in Görlitz, offers durable and wear-resistant cleaning processes for economical used plastic recycling and already has 20 years of experience with established systems. This is the best basis for Vecoplan to enter into a strategic partnership in the field of cleaning. With the combination of Vecoplan’s high level of expertise in recyclable material processing and Pla.to’s experience in the various cleaning processes, customers will in future receive processing solutions from a single source. Over the past few years, the two partners have perfectly coordinated their proven technologies in various tests.

The collaboration aims at driving circularity in plastics value chains and the automotive industry. When no longer fit for use, tires are liquefied by means of chemical recycling and then processed into base chemicals and further into polycarbonates of high purity. These can then be used in various automotive applications, from parts of headlamps to radiator grilles.

As part of the collaboration, Neste turns liquefied discarded tires into a high-quality raw material for polymers and chemicals manufacturing and supplies it to Borealis. Borealis will then process the Neste-produced raw material into base chemicals phenol and acetone, which are supplied to Covestro. Covestro can use these materials to make polycarbonates. The share of recycled content is attributed via the mass balancing approach all the way to the final products using ISCC Plus certification.

The first products based on the collaboration are already available as each party has manufactured the first batch of their respective contribution to the project. Aside from polycarbonates, the project partners may also consider polyurethanes as a possible end product, which could also find its way into parts of the interior of a car. The companies emphasize that the potential to scale up these types of developments should be considered when setting ambitious targets for future EU regulations, such as the End-of-Life Vehicles Regulation.

Project Circle targets the remaining waste which cannot be mechanically recycled, by developing new technologies including dissolution, pyrolysis, and gasification.

The goal is to make all PVC waste recyclable and aim to have our first industrial unit ready by 2030. As part of this process, the company has launched two pilot plants in Jemeppe sur Sambre (Belgium), where Ineos Inovyn’s main R&D centre is located.

These units draw on Vinyloop’s technology experience from 2002 to 2018, and are designed to upgrade PVC dissolution technology which supports the recycling of complex PVC waste, including legacy additives.

Industry wide collaboration plays an important part of Project Circle and to support this, Ineos Inovyn has joined two Belgium consortiums. The first ‘CIRC-PVC’ covers the entire chain, from collecting PVC waste at construction-demolition sites to the production of rejuvenated PVC not containing legacy additives. This brings together industrial partners and experts from across different stages of the value chain: Entreprises Générales Louis Duchêne, Vanheede Environmental Logistics, ROVI-TECH, ECO-DEC, Avient Corporation’s Belgium site, Centexbel, the University of Liège and Ineos Inovyn.

The second consortium ‘DISSOLV’ will drive the development of PVC waste from flooring, carpets and tarpaulin applications which cannot be recycled today, due to the presence of textile fibers and legacy additives. Its members include Beaulieu International Group, Sioen Industries, Empire Carpets International, ExxonMobil, Centexbel and Ineos Inovyn.

At present, more than 40 plants for chemical recycling are in operation worldwide, while more than 100 further projects are being planned. This is one of the findings of Ecoprog’s latest market report.

Within the next two or three years, the introduction of chemical recycling will enter its decisive phase. There are several reasons for this. Firstly, according to project engineers, nearly 50 new plants for chemical recycling are supposed to become operational over the coming years, more than half of which are located in Europe. This process will show if technical solutions can be implemented as planned – and at the expected cost.

The decision on legal bases is at least equally important, especially in the EU. If the calculation of the recycling performance in the sense of ‚Fuel Use Exempt‘, which is the calculation methodology claimed by the chemical industry, established itself, this would allow, for instance, to count used pyrolysis oil, with almost equal mass, as recycled plastic. At the same time, it would be possible to ‚dilute‘ the pyrolysis oil with naphtha produced from fossil resources within the scope of larger-scale production processes. This would also have technical consequences, such as higher tolerances regarding impurities. In the case of a ‘Rolling Average’ approach, as claimed particularly by environmental associations and the material recycling industry, the quota of calculated amounts oftentimes would not even be half as high in practice. Subsequently, the economic importance of the calculation method is high, seeing that a debate on this subject is currently being carried out within the EU, above all, through the decision on implementation of the Single-Use Plastics Directive (SUPD).

Against the background of the still high dynamics in the chemical recycling market, ecoprog has updated its market report on chemical recycling in its third edition. In doing so, for the first time, some projects have been deleted from the tracking due to the lack of visible progress.

In total, the market study covers more than 40 active plants and more than 100 projects for chemical recycling, almost 20 of which are under construction. Altogether, the number of active plants as well as plants under construction has again increased compared to last year’s figures.

To the study

OMV will process feedstock supplied from Tomra Feedstock plants in its ReOil plants in Austria, while Borealis will process feedstock produced by Tomra at its mechanical recycling operations in Europe. The feedstock will be produced from mixed post-consumer plastic material otherwise lost to landfill and incineration at a first-of-its-kind sorting facility currently being developed in Germany.

Tomra is currently building a sorting plant in Germany that will have an input capacity of 80,000 metric tons per annum and be operational at the end of 2025. Tomra Feedstock has developed a process that transforms pre-sorted mixed post-consumer plastic waste – materials that would otherwise end up in incineration – sorted into clean fractions of specific polymer types. These fractions can then be further processed in mechanical and chemical recycling plants such as those run by OMV and Borealis.

The result of solid collaborative work with BIR national member associations, the paper highlights that chemical recycling needs careful consideration and well-informed, market-based policies to ensure that it complements rather than competes with traditional recycling methods.

Mechanical recycling must remain the preferred method on a large scale whereas chemical recycling should be used only for hard-to-recycle end-of-life plastics, insists the global federation of recycling industries.

This position paper on chemical recycling follows shortly after one on extended producer responsibility, which was published by BIR in November last year. Describing chemical recycling as “a nascent technology”, BIR urges caution in its deployment and calls for the introduction of a harmonized definition of chemical recycling that excludes fuel production.

Chemical recycling processes are extremely energy-intensive and some that are currently available produce more greenhouse gas emissions than primary production using fossil fuels during the production process, the position paper points out. For these and other reasons, chemical recycling should be used only for materials that mechanical recycling cannot efficiently or economically process, it argues.

In addition, chemical recycling should not be allowed to override the need for design for recycling, according to BIR. Policies should focus on eliminating hard-to-recycle plastics and on incentivizing the design of plastics for reuse or mechanical recycling, thus reducing the requirement for new resources, it says. Furthermore, it is added in the position paper, chemical recyclers should refrain from misusing mass balance accounting principles to fulfil recycled content objectives.

“A robust method for calculating the climate impacts of chemical recycling must be developed,” underlines BIR Director General Arnaud Brunet. “This should cover all emissions from the process, as well as overall energy usage and incineration of recovered hazardous waste. Furthermore, incentivizing the lower-carbon option of mechanical recycling would enable it to compete with lower-priced primary plastics and make the process more attractive for investment.”

Also responding to the publication of this latest position paper, BIR President Susie Burrage OBE underlines the importance of conveying the industry’s key messages on issues relating to recycling. “I am delighted that BIR dedicates resources to such important topics. I’m also extremely appreciative of the excellent collaboration with our national associations on this. It is vital that we continue to join forces in this way for the benefit of our members.”

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For the processing run, Neste sourced pyrolysis oil derived from discarded vehicle tires by Scandinavian Enviro Systems, a Swedish company developing technologies to recover materials from end-of-life products. The goal of Neste’s pilot run was to evaluate the potential of chemical recycling beyond plastic waste to potentially broaden the pool of waste streams that could be processed into high-quality products.

Just as with hard-to-recycle plastic waste, a large amount of tires today ends up in landfills or incineration at the end of their life cycle. The composition of tires as a mix of several materials makes them difficult to recycle with mechanical recycling methods. Hence, there is a strong case for using chemical recycling to help keep valuable materials in circulation – and Scandinavian Enviro Systems has developed a pyrolysis technology for extracting carbon black and oil from end-of-life tires.