Off the beaten track to make plastic industry fully circular

To make the plastic industry circular, we need innovative recycling technologies that yield a higher quality product. An interdisciplinary consortium of academic and industrial partners recently received funding within the National Growth Fund programme to help achieve this, using catalytic extrusion for chemical recycling. The team is led by assistant professor Ina Vollmer and includes, among others, process and technology provider Coperion.

In the Netherlands, the largest part of the plastic waste we produce is incinerated. Some of the plastics are recycled, of which only a small part is recycled at high quality. To boost recycling rates that yield a higher quality product, we need innovative technologies. While chemical recycling holds potential, it is still at an early stage of development. The partners within the consortium will join efforts to research and optimize the use of catalysts in existing chemical recycling methods.

To learn how catalysts can optimize the process, we need a scientific approach, and this is where Ina (Vollmer) comes in

Unlimited recycling

Many years ago, Coperion started to develop technology for recycling purposes. First, it focused on mechanical recycling, where plastics are sorted, shredded and melted. However, these methods result in lower-quality plastic over time. Today, the company also builds technology that enables chemical recycling of plastics. This method offers a way to turn plastic waste back into high-quality materials, which potentially allows for unlimited recycling. However, the process is energy-intensive and does not always result in high-quality product, yet.

Scientific approach

The use of catalysts could play a major role in tuning the quality of the final product and the efficiency of the process. However, according to Leonid Liber, sales engineer at Coperion, nobody knows exactly which effects the catalysts have. “To learn how these catalysts can optimize the process, we need a scientific approach, and this is where Ina comes in”, he says enthusiastically. “She will research the effect of catalysts systematically, changing one parameter at a time. It is a nice collaboration, which we need for this new kind of challenge.”

Off the beaten track

Vollmer is an assistant professor who researches various methods for chemical recycling. Only recently, she received an ERC Starting Grant and a Demonstrator Grant to expand her work.

To perform the experiments which are needed within this consortium, she will place an extruder from Coperion into her lab. This extruder consists of two large, co-rotating screws in a barrel that employ heat and friction to break down the plastic.

Extruders are used to feed the polymer to pyrolysis, in which the plastic is broken down into its chemical building blocks, using extremely high temperatures in the absence of oxygen. “However, in this project, we want to optimize the extrusion part so that we might not need to perform the pyrolysis afterwards. We want to convert the polymer already in the extruder. If that does not work, we still have very valuable insight into the preparation for pyrolysis, which can then be performed at lower temperatures, thus needing less energy.”

People think I am crazy bringing this machine in here, but I think it is a logical choice

Vollmer goes off the beaten track, bringing an industrial machine into her lab. “It took some effort to make it possible, because a twin screw extruder is a relatively large machine, even on lab scale”, she says. “People think I am crazy putting it here, but I think it is a logical choice. If we work with this equipment, reliable upscaling to large systems is possible.”

This is the full list of partners: Carboliq, Coperion, Ruhr University, Universiteit Maastricht, and Universiteit Utrecht.