POOL-IN-LOOP: Development of an energy-efficient depolymerization process for polyolefin-containing plastic waste with the help of catalysts for the direct production of polymers for virgin plastic

At a glance

• Every year, millions of tons of plastic waste are incinerated because the complex composition of the materials renders mechanical recycling impossible. Chemical recycling processes which break the plastics down into their components are both costly and energy-intensive.
• In the POOL-IN-LOOP project, the project partners are further developing a new chemical recycling technology aiming to increase the recovery of high-quality chemicals from plastic waste and reduce energy consumption at the same time.
• Fraunhofer IWES is developing a model which identifies potential load flexibility in the process chain and couples it to the green electricity offering.

The challenge

The Circular Economy Action Plan (CEAP), adopted by the European Commission in 2015, is a key building block for the implementation of the European Union’s Green Deal. However, plastic waste which is difficult to recycle is currently incinerated for the most part. In Germany alone, 4.33 million tons of the around 5.35 million tons of post-consumer plastic waste collected in 2019 were lost from the material cycle. This is predominantly due to the complex composition of the plastic waste. The mixture of foreign materials, associated materials, additives, and composite components with the actual polymers renders producing plastics of virgin material quality via mechanical recycling impossible.

Although heightened measures such as “design for recycling” and improved sorting and recycling processes are expected to increase the recovery rate for mechanical recycling, a wide range of plastic waste which is difficult to recycle will continue to be produced in the future. One available solution is chemical recycling, where plastics are broken down into their components, purified, and then fed into a repolymerization process. However, this process is both costly and energy-intensive.

The solution

This is where the POOL-IN-LOOP project comes in. The project partners are further developing a new depolymerization technology and transferring it to an industrial scale. The aim is to increase the recovery of high-value chemicals (HVC) from plastic waste from around 53 percent to more than 70 percent with less cost and effort involved.

This is achieved via a simplified process involving fewer intermediate steps and lower energy and material losses. Mixed plastic waste containing polyolefins is broken down with the help of catalysts, predominantly into gaseous olefins, which as monomers can be directly reused in the polymerization process. This process renders the energy-intensive steps of pyrolysis oil hydrogenation and a second splitting step unnecessary.

At the same time, the extent to which catalytic cracking can be operated in a load-flexible manner is also being investigated. To this end, Fraunhofer IWES, which is responsible for this subtopic, is utilizing weather data and the resulting electricity supply forecasts to adapt the production planning with its more or less energy-intensive subsections taking into account storage capacities. The goal is to utilize the new technology to develop a model which integrates wind energy into chemical processes practically in a site-specific manner. 

The added value

POOL-IN-LOOP enables the closing of material cycles, as residual material fractions, which had to be thermally recycled until now, can be recycled particularly efficiently into high-quality raw materials for the chemical and plastics industries. As wind energy and load flexibility are being integrated right from the development stage, the project is also becoming a model project for the decarbonization of the chemical industry.

Further information: KuRT | pool-in-loop (bmbf-kurt.de)