Plastic bottles and packaging are being ground up with catalysts in a solvent-free milling process to break their tough polymer chains back into reusable chemical building blocks. Only 16% of the 380 million tonnes of plastic produced each year is currently recycled. The rest ends up in landfill or the environment, while demand for carbon-based chemicals is set to double within a decade. Existing recycling methods struggle with contaminated waste, produce low-value products, and consume large amounts of energy. This project uses mechanochemistry—chemical reactions driven by mechanical force rather than heat—combined with specially designed catalysts to lower the energy barrier for breaking polymer bonds. The team will demonstrate the process on PET (bottle plastic) before expanding to polyamides and polycarbonates. If successful, the approach could push plastic recycling rates toward 100% by turning waste directly into high-quality feedstocks for new plastics and chemicals. This would reduce reliance on fossil fuels for carbon-based materials, cut emissions from the chemical sector, and help close the loop on plastic waste. The project works with a waste management company and a process manufacturing centre to scale the technology beyond the lab.
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The accumulation of plastic wastes is a severe environmental challenge. Present estimates suggest that over 380 Mt plastics are produced annually worldwide, only 16% are currently recycled, while 150-200 Mt plastics are accumulated in landfill or leaked to the natural environment. On the other hand, the global demand for carbon-based chemicals and materials is expected to double in the next 10 years to over two billion tons, which we cannot simply still rely on sourcing from fossil fuels. We need to supply these feedstocks from recycling waste materials, such as plastics. However, until now, there remains significant challenge in bridging the gap between waste management and the resource demand for materials and commodity chemicals. The ultimate way to overcome this challenge is to close the loop by recovering the monomer feedstocks from waste, yet such chemical recycling cannot be easily achieved by traditional thermo-chemical processes, due to the poor tolerance to feedstock contamination, low economic value of products and sizable energy input. On this aspect, mechanochemistry, which utilises mechanical energy to initiate chemical reactions, has clear advantages over traditional thermochemical processes. These advantages arise from reactions taking place in a solventless, solid-state environment, with a high tolerance to variation feedstock qualities. Historically, this technique solely relies on supplying enough energy input to overcome the thermodynamic energy threshold of the chemical reactions. Yet plastics are made to last, therefore the polymer chemical bonds are difficult to break. Therefore, capitalising on the team’s strong background on catalysis and polymer processing, through building collaboration with the mechanochemical community in the UK, CirPla will demonstrate for the first time how catalysis + mechanochemistry can transform the plastic recycling and manufacturing sectors. The catalysts will decrease the activation energy of the polymer chain bond breaking, while mechanochemical conditions supply the energy required to drive the depolymerisation reaction. The effectiveness of this process will be demonstrated with a model plastic polyethylene terephthalate (PET, beverage bottles), with the scope of expanding to other plastics, such as polyamides and polycarbonates, in future studies. By collaborating with the world-unique EPSRC-Resonant Acoustic Mixing research facility led by Prof. Tomislav Frišcic in University of Brimingham, CirPla will push the frontier by: 1. Design effective nanoscale catalysts for maximum product yield; 2. Benchmark mechanochemical systems at different scales for up-scaling assessment; and 3. Understand reaction mechanism for further material and catalyst discovery. This research theme aligns with the UKRI’s strategic theme of “building a greener future”, Innovate UK Circular Plastics Network (UKCPN), and Materials and Manufacturing Vision 2050. Aiming to translate the research discovery for impact delivery beyond the project, CirPla is also closely linked with waste management company (Chambers) and the process manufacturing centre of excellence (CPI), for further technology scale-up and validation. When successfully developed, this new process has the potential to transform the plastic value chain and push towards 100% recycling rate. By sourcing the carbon feedstocks from waste stream as fossil fuel alternatives, it will also facilitate the decarbonisation and defossilisation of the chemical sector, thereby contributing towards a climate neutral circular economy.
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