Transcript
Each year, 380 million tons of plastic are created worldwide. And many analysts predict production could quadruple to 1.5 billion tons of plastic as soon as 2050. That’s a big deal when you consider that more than 75 percent of these plastic materials are discarded after one use. Worse yet, many of them end up in our oceans and waterways, harming wildlife and spreading toxins.
While plastics can be melted and reprocessed, this type of recycling yields low-value materials that are not as structurally strong as the original material. Examples include down-cycling plastic bottles into a molded park bench. When left in the wild or landfills, plastics do not degrade because they have powerful carbon-carbon bonds.
Instead, they break up into small plastic fragments, known as microplastics. Whereas some people see these strong bonds as a problem, researchers working at Northwestern University, Argonne National Laboratory, and Ames Laboratory saw this as an opportunity.
They developed a new method for upcycling abundant, low-value plastics into high-quality liquid products, such as motor oils, lubricants, detergents, and even cosmetics.
The catalytic method delivers a “one-two punch” by removing plastic pollution from the environment and contributing to a circular economy. The findings published in the journal ACS Central Science have broad implications for shaping a future in which we can continue to benefit from plastic materials but do so in a way that is sustainable, less harmful to the environment, and potentially less harmful to human health.
The process uses a catalyst that consists of platinum nanoparticles, just two nanometers in size, deposited onto perovskite nanocubes; those nanocubes are 50-to-60 nanometers in size. The team chose perovskite because it is stable under high temperatures and pressures, as well as being exceptionally good for energy conversion.
To deposit nanoparticles onto the nanocubes, the team used atomic layer deposition, a technique developed at Argonne that allows precise control of nanoparticles.
Under moderate pressure and temperature, the catalyst breaks the plastic’s carbon-carbon bonds to produce high-quality liquid hydrocarbons. These liquids could be used in motor oil, lubricants, or waxes as well as further processed to make ingredients for detergents and cosmetics. This contrasts with today’s commercially available catalysts, which generated lower quality products with many short hydrocarbons, limiting the products’ usefulness.
Even better, this new catalytic method produces far less waste than methods that melt plastic or use conventional catalysts.
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