Water enhances the conversion of polyolefins
into valuable fuels when using ruthenium catalysts,
offering a promising solution to global plastic wastePlastics are undeniably useful materials that have found their way into virtually all human activities. However, with yearly global plastic production exceeding 400 million tons, the environmental threat posed by increased plastic consumption and disposal, contributing to its pollution, is also bigger than ever. Considering that only one-tenth of all plastic waste is recycled, new technologies that can help tackle this growing problem are urgently required.
Catalytic recycling techniques, such as hydrogenolysis and hydrocracking, are emerging chemical processes that can break down plastic waste into simpler components using catalysts. Traditional recycling involves melting and remolding plastics into lower-quality materials, whereas catalytic recycling can convert plastics into valuable chemicals and fuels, enabling a more sustainable and efficient reuse. Though certainly promising, catalytic recycling methods need further refinements before they are ready for adoption on an industrial scale.
In a study published in Nature Communications, a research team led by Professor Insoo Ro of Seoul National University of Science and Technology, Korea, recently made a breakthrough discovery in the catalytic recycling of polyolefins, which comprise 55% of global plastic waste. As explained in their article, the researchers revealed the surprising benefits of adding water during polyolefin depolymerization when using ruthenium (Ru)-based catalysts.
After synthesizing and experimenting on various Ru-based catalysts on different supports, the team found that catalysts with both metal and acid sites exhibit dramatically improved conversion rates when water is added to the reaction mixture. “The addition of water alters the reaction mechanisms, promoting pathways that enhance catalytic activity while suppressing coke formation,” explains Dr. Ro, “This dual role improves process efficiency, extends catalyst lifespan, and reduces operational costs.”
The researchers investigated the reaction mechanisms in detail, shedding light on the effect of Ru content and the proximity and balance between metal and acid sites. Under optimal conditions, Ru/zeolite-Y catalysts showcased a 96.9% conversion rate for polyolefins.
Finally, to explore the viability of this type of catalytic recycling, the team conducted a techno-economic analysis and a life cycle assessment of the proposed approach. The results clearly underscored the potential of implementing a real commercial-scale process using Ru/zeolite-Y catalyst. “The addition of water not only enhances carbon efficiency, it improves economic and environmental performance, also increases the conversion of polyolefins to valuable fuels like gasoline and diesel,” highlights Dr. Ro. Adding further, he says, “this approach thus represents a viable alternative to conventional waste management practices and offers a solution to reduce landfill and ocean pollution caused by polyolefins—the largest contributor to plastic waste.”
Overall, this breakthrough in catalytic depolymerization could revolutionize how we deal with plastic pollution and help us efficiently deal with this serious environmental threat. The research team has high hopes that this technology will evolve over the next few years to the point that mixed plastic waste can be processed without pre-sorting, making recycling efforts more cost-effective and simpler to implement. “By demonstrating a sustainable and economic approach to transforming plastic waste into valuable resources, our research could help drive policy changes, inspire investment in advanced recycling infrastructure, and foster international collaborations to address the global plastic waste crisis. Over time, these advancements promise cleaner environments, reduced pollution, and a more sustainable future,” concluded Dr. Ro on an optimistic note.
- The paper Unraveling the role of water in mechanism changes for economically viable catalytic plastic upcycling was published in Nature Communications