by In a groundbreaking development, scientists at the Department of Energy’s Oak Ridge National Laboratory have created a new catalytic recycling process that has the potential to revolutionize the recycling of mixed plastics. Currently, a large percentage of consumer plastics end up in landfills or are incinerated, generating greenhouse gases and toxins. The traditional methods of recycling mixed plastics are costly and inefficient, making it more economical to produce new plastic products.
To address this issue, the scientists utilized careful chemical design, neutron scattering, and high-performance computing to develop a new multipurpose catalyst. This catalyst selectively and sequentially breaks down multiple polymers in mixed plastics into pristine monomers, which can be reused to create new plastics. This process has the potential to significantly reduce global plastic waste, including bottles, packaging, foams, and carpets.
The scientists compared the new multipurpose catalyst to using individual catalysts for each type of plastic. The results demonstrated that the new catalyst produced up to 95% fewer greenhouse gases, required up to 94% less energy input, and resulted in a reduction of up to 96% in fossil fuel consumption.
The catalyst, which is a tailored synthetic organocatalyst, can efficiently convert batches of mixed plastic waste into valuable monomers for reuse in commercial-grade plastics and other materials. This highly efficient chemical process offers a viable solution for closing the loop on recycling mixed plastics, replacing first-use monomers with recycled ones.
Currently, the majority of plastics are manufactured using fossil fuels and energy-intensive processes. Implementing this closed-loop recycling process globally could potentially reduce annual energy consumption by about 3.5 billion barrels of oil.
The organocatalyst developed by the scientists has proven to be effective in deconstructing multiple polymers, including those used in safety goggles, foams, water bottles, and ropes or fishing nets. These polymers make up more than 30% of global plastic production. Previously, no single catalyst had been able to effectively break down all these types of polymers.
The new process also offers environmental advantages by replacing harsh chemicals with a more sustainable method of deconstructing polymers. Additionally, the catalyst demonstrates good selectivity, thermal stability, nonvolatility, and low flammability. It is also effective in deconstructing multicomponent plastics, such as composites and multilayer packaging, which are becoming increasingly prevalent.
To confirm the formation of deconstructed monomers from waste plastics, the scientists utilized small-angle neutron scattering at Oak Ridge National Laboratory’s Spallation Neutron Source. This method allows for the characterization of the structure at different levels of detail.
The catalytic recycling process involves deconstructing the plastics at specific temperatures to separate the individual monomers, which can then be reused. The temperatures at which the different plastics deconstruct are as follows: polycarbonates at 266°F (130°C), polyurethanes at 320°F (160°C), polyethylene terephthalates at 356°F (180°C), and polyamides at 410°F (210°C). Other materials present in the plastics, such as additives, cotton, and plastic bags, remain intact due to their differing reactivity and can be recovered separately.
The deconstructed monomers and the organocatalyst are soluble in water, allowing for the removal of impurities, such as pigments, through filtration. The pure monomers can then be extracted and the catalyst can be reused for multiple deconstruction cycles by evaporating the water.
This new catalytic recycling process has the potential to revolutionize the recycling of mixed plastics, reducing environmental impact and promoting a more sustainable approach to plastic waste management. With its significant reductions in greenhouse gases, energy consumption, and fossil fuel consumption, this innovation paves the way for a brighter and more environmentally friendly future.
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- Source: Coherent Market Insights, Public sources, Desk research
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