Depolymerisation: Recycling process in the ramp-up phase

Biovox actually stands for medical-grade bioplastics. But the Darmstadt-based start-up also wants to be a pioneer in medical-grade recyclates. These compounds should not be mass-balanced, but should actually be physically available. They are to be produced using the depolymerisation process at a partner company. Biovox founder Dr Julian Lotz will not reveal which company this is.

However, there are currently only a handful of companies in Europe that have developed various depolymerisation processes: These include start-ups such as Depoly and Gr3n, both from Switzerland, as well as Carbios from France and the Dutch company Ioniqa. All of them are recycling start-ups that have developed the corresponding process technology and are now in the process of bringing the process to industrial mass production together with partners. Most industrial pilot plants depolymerise PET from packaging and textiles. The recyclate has the same quality as virgin PET.

Depoly relies on hydrolysis for depolymerisation

Depoly is a spin-off of the Swiss Federal Institute of Technology Lausanne (EPFL), financed by BASF Venture Capital and Beiersdorf, among others. It converts post-consumer PET plastic waste into terephthalic acid (TPA) and monoethylene glycol (MEG) at room temperature by means of hydrolysis so that new PET plastic can be produced. Depoly currently operates a pilot plant for the production of 50 tonnes of recyclate per year, but is now building a plant with a capacity of 500 tonnes in Valais to demonstrate the scalability of its process. This pilot plant is scheduled to open in 2024.

Microwave-assisted hydrolysis at GR3n

GR3n, based in Chiasso/Switzerland, uses a process known as alkaline hydrolysis to produce virgin material from post-consumer and post-industrial PET waste. This process usually takes three to five hours at a temperature of 210 to 250 °C.

In GR3n's microwave-assisted hydrolysis reactors, TPA and MEG are extracted from bottles and textiles in less than ten minutes and at less than 200 °C. A prototype of the reactor is currently in use.

In July 2023, the company announced that it was setting up a joint venture with the Spanish engineering service provider Intecsa. Together, the two companies intend to build the first production plant for GR3n's depolymerisation process in Spain. It is to be designed for 40,000 tonnes and go into operation in 2027.

Enzymes instead of chemicals for depolymerisation in convertibles

Founded in 2011, the French start-up Carbios uses enzymes for hydrolysis that were first identified in compost. Cabrios has modified them so that they work at higher temperatures - at 60°C to be precise. The listed company has commissioned a demonstration plant with a capacity of 40,000 tonnes per year in Clermont-Ferrand on a site owned by tyre manufacturer Michelin in 2021.

The process is now to be industrialised together with PET global market leader Indorama Ventures. The plan is to build a plant with an estimated processing capacity of around 50,000 tonnes of post-consumer PET waste per year. It is scheduled to go into operation in 2025.

Gycolysis process in use at Ioniqa

Ioniqa, a spin-off from Eindhoven University of Technology in the Netherlands, uses the glycolysis process, which breaks down PET into the monomer BHET. The start-up calls the core technology Magnetic Smart Process (MSP). It uses magnetic nanocatalysts that can break down polycondensates, including PET, polyester, polyamide and polyurethane.

After depolymerisation, the material undergoes various separation steps at the plant. Coca-Cola, for example, has invested in the company. The Ioniqa factory in Geleen in the Netherlands now processes up to 10,000 tonnes of plastic per year for customers such as Indorama and Unilever.

None of the young companies are yet making a profit. They are all pinning their hopes on the sale of licences for their technology to large plastics manufacturers. Processing on a large scale is not our expertise, plastics manufacturers can do it better," says Tonnis Hooghoudt, CEO and founder of Ioniqa, for example.

Article from "medizin & technik" from 21/09/2023