Our next step to sustainability in the PET chain: chemical recycling
We now produce some 25 kilotons of PET pellets per year, which we can upcycle or adapt to the different specifications of our customers.
This mechanical recycling is successful, but it still leaves a lot of polyester waste unused. Heavy colored materials or mixed plastics are not suitable as feedstock for this process. That is why Cumapol has developed a continuous chemical recycling process. ‘We depolymerize the PET by adding a certain amount of glycol. Polymerization is an equilibrium reaction, and this way we shift it.’ The result is a low viscosity fluid, from which the dyes and other contaminants can be removed using activated carbon and/or distillation and crystallization.
‘This process works well in the lab, so now we are building a pilot plant to test it on a kilogram scale.’ The plant, a scaled down and adapted version of their PET production line, will be installed in the Cumapol premises in Emmen. When this is successful, the aim is to convert the production lines that are not used for the mechanical recycling. ‘So we will have a capacity of another 25 kilotons of PET from chemical recycling.’
Using this new technology, Cumapol can use different sources of recycled PET. ‘Food safety regulations mean we have to use 95 percent PET from food packaging for mechanical recycling. However, for chemical recycling we can use every kind of starting material including colored PET.’ And there is another option: during chemical recycling, the polymers are broken down to monomers. At that stage, bio based monomers could be added.
In about two years’ time, Marco Brons expects his company is ready to convert the remaining PET production lines for chemical recycling. This will bring total production to 50 kilotons per year. Compared to the 400 kilotons an average PET bottle factory uses, this may seem small. ‘Our niche is production of custom made polymers, for the national and international market. But we do hope that our technology will be adopted by larger producers.’