New recycling opportunity for polystyrene

United States – US chemists have discovered a way to convert unwanted polystyrene back to styrene monomer, Professor Lanny Schmidt from the University of Minnesota in America has noted in sustainable chemistry journal ChemSusChem.

The process has the potential to render polystyrene recycling more economical by creating high-quality new materials instead of merely melting and remoulding contaminated plastics into low-value goods, he states. The latter approach can also cause the plastic to decompose, char and give off noxious gases, he adds.

The aim of Professor Schmidt’€™s team was to re-establish the original monomer to allow it to be reprocessed into either virgin plastic or other products. The process relies on a platinum or rhodium catalyst combined with cerium and supported on alumina spheres. As a result of the heat given off by the reaction of the particles as they pyrolyse into styrene, running costs are significantly reduced because no other heat input is necessary.

‘€˜To our surprise, we got up to 80% styrene monomer,’€™ Professor Schmidt remarks, adding that the lab-scale reactor using 1gram of catalyst is capable of processing up to 1 kg of polystyrene each day.

For more information, visit: www.research.cems.umn.edu/schmidt