Aarhus, Denmark – Scientists at Aarhus University have developed an alternative technique for recycling polyurethane foam. It is able to recover up to 82% of the foam by weight.
Most chemical recycling techniques are only capable of recovering the polyol part, with Covestro’s pilot-scale process a notable exception. The Aarhus process also gives two components, a polyol and a diamine.
In the acidolysis process, the foam is heated to 220°C with a small amount of succinic acid. The reaction mixture is then filtered, with the polyol passing through the filter and the residue being caught by the filter. The recovered polyol, they said, has a comparable quality to virgin polyol, ready for turning into new PU.
A hydrolysis reaction can then be carried out on the solid part to recover a diamine. This can then be further transformed into new diisocyanate and used in PU production, they said.
The scientists claim the method should be easy to scale up for production scrap from foam manufacture. Further work will, of course, be required for PU waste from end-of-life foam, because of the sorting challenges involved.
They are now looking at whether the method can be applied to other forms of PU. They are also looking at the potential of reusing the succinic acid used in the process.
The work has been published in the journal Green Chemistry.
