Plastic vaporizing process could recycle bags and bottles indefinitely

A new process uses cheap catalysts to break down polyethylene and polypropylene into their building blocks, enabling common plastic objects to be turned into new products.

Plastic bottles and bags can be vaporized into chemical building blocks and turned into new plastics with all the properties of virgin material. There are hurdles still to overcome, but the new process is a big step towards a truly circular economy for plastic.

Around 5 billion tonnes of plastic has gone to landfill since the 1950s, and recycling efforts have only tackled 9 percent of what we've produced. With current techniques, plastics degrade in each recycling round and end up in landfill after only a few cycles through this process.

John Hartwig at the University of California, Berkeley, and his colleagues had previously developed a process that breaks down waste plastic into its constituent parts, but it relied on expensive metal catalysts iridium, ruthenium, and palladium, which were irrecoverably lost as part of the process. Hartwig says that the technique was “OK for an academic paper, for demonstration purposes, but nowhere near what you would need for something that could be conceived of ever becoming industrial.

Now, his team has discovered an improved process that works on both polyethylene, from which most plastic bags are made, and polypropylene, which is used to make harder objects, and it relies only on catalysts considered so common that they are essentially “dirt”, says Hartwig.