US scientists discover way to recycle PE plastics into PP


Scientists in the United States have discovered a method that enables PE plastics to be converted into PP.

They also said that existing technology could be used for this process.


According to the scientists from University of Illinois Urbana-Champaign; University of California, Santa Barbara and chemical company Dow said that its method could help reduce greenhouse gases by the equivalent of taking 3 million cars off the road if 20% of PE-based plastic was treated by their process.

Essentially, it works by cutting each PE molecule many times to obtain very small pieces. A catalyst removes the hydrogen from the PE, which creates a reactive location on the chain. The chain is then split in two at this location, using a second catalyst, which caps the ends using ethylene. Finally, a third catalyst moves the reactive site along the PE chain so that the process can be repeated. All that is left are a large number of PP molecules.

UC Santa Barbara distinguished professor and Mellinchamp chair of sustainable catalytic processing Susannah Scott said: “Turning polyethylene into polypropylene, which can then be used to make a new polymer, is how we start to build a circular economy for plastics.

“Now that we have established the proof of concept, we can start to improve the efficiency of the process by designing catalysts that are faster and more productive, making it possible to scale up.

“Since our end product is already compatible with industry separation processes, better catalysts will make it possible to implement this breakthrough rapidly.”