Good news! This could be a breakthrough!
"Researchers ... might have a way to largely skip sorting plastic. Their process uses an inexpensive catalyst that selectively breaks down the most common single-use kind of plastics into liquid oils and waxes that can be upcycled into lubricants and fuels. ...
The polyolefins ... are what trash bags, plastic wrap, squeeze bottles, and other disposable single-use packaging are made of. It's estimated that more than 220 million tons of polyolefin products are manufactured annually around the world – but only 1% to 10% of it is recycled globally, in part because this material is awfully hard to break down. ...
With its single-site design, the nickel-based catalyst preferentially cuts carbon-carbon bonds when used in plastic recycling processes. As such, it selectively breaks down only branched polyolefins for easier upcycling. It's especially remarkable because ... "polyolefins don’t have any weak links. Every bond is incredibly strong and chemically unreactive.”
This catalyst also happens to operate at a lower temperature and require less hydrogen gas to act on plastics. It also remains stable when exposed to polyvinyl chloride (PVC), a compound commonly found in pipes and flooring that contaminates plastics in the recycling process to the point where the entire batch becomes unusable and must be discarded. In fact, the inclusion of PVC actually accelerated the catalyst-driven process further. ..."
"... “Compared to other nickel-based catalysts, our process uses a single-site catalyst that operates at a temperature 100 degrees lower and at half the hydrogen gas pressure,” ... “We also use 10 times less catalyst loading, and our activity is 10 times greater. So, we are winning across all categories.” ...
Amazingly, not only did ... catalyst withstand PVC contamination, PVC actually accelerated its activity. Even when the total weight of the waste mixture is made up of 25% PVC, the scientists found their catalyst still worked with improved performance. This unexpected result suggests the team’s method might overcome one of the biggest hurdles in mixed plastic recycling — breaking down waste currently deemed “unrecyclable” due to PVC contamination. ..."
From the abstract:
"Current methods of processing accumulated polyolefin waste typically require harsh conditions, precious metals or high metal loadings to achieve appreciable activities.
Here we examined supported, single-site organonickel catalysts for polyolefin upcycling. Chemisorption of Ni(COD)2 (COD, 1,5-cyclooctadiene) onto Brønsted acidic sulfated alumina (AlS) yields a highly electrophilic Ni(I) precatalyst, AlS/Ni(COD)2, which is converted under H2 to the active AlS/NiIIH catalyst.
This single-site system exhibits unique hydrogenolysis selectivity that favours cleaving branched polyolefin C–C linkages, enabling the hydrogenolytic separation of polyethylene and isotactic polypropylene (iPP) mixtures.
Moreover, AlS/NiIIH remains highly selective and active for hydrogenolysis of iPP admixed with polyvinyl chloride, and the spent catalyst can be repeatedly regenerated by AlEt3 treatment.
Experimental mechanistic analysis and density functional theory modelling reveal a turnover-limiting C–C scission pathway featuring β-alkyl transfer and strong olefin binding. These results highlight the potential of nickel-based systems for the selective upcycling of complex plastic waste streams."
No-sort plastic recycling is near (original news release) "New catalyst could make mixed plastic recycling a reality"
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