In November last year, a research team led by Professor Insoo Ro from Seoul National University of Science and Technology made a “breakthrough discovery” regarding the catalytic recycling of polyolefins. Making up 55% of global plastic waste, the team has found benefits by adding water during polyolefin depolymerisation when using ruthenium (Ru)-based catalysts.
SEOULTECH
SEOULTECH adds water to ruthenium-based catalytic processes.
There is no denying how useful, and important, plastic materials have become in almost all human activities. But with yearly global plastic production sitting at over 400 million tons, and the environmental concerns that come along with that level of usage, reducing plastic pollution is just as important. Especially because only one-tenth of all plastic waste is recycled.
Hydrogenolysis, hydrocracking, and other catalytic recycling techniques help to break down plastic waste with simpler components using catalysts. While traditional recycling involves melting and re-moulding plastics and turning them into lower-quality materials, these new types of methods convert recycled plastics into valuable chemicals and fuels. More efficient uses can be found of these recycled plastics compared to traditional methods. However, more refinements are required before industrial rollouts can occur.
Professor Ro and his team tried synthesising and experimenting with a variety of Ru-based catalysts using different supports during their research. They found that catalysts with both metal and acid sites showed improved conversion rates when water was added to the reaction mixture.
“The addition of water alters the reaction mechanisms, promoting pathways that enhance catalytic activity while suppressing coke formation,” said Dr Ro. “This dual role improves process efficiency, extends catalyst lifespan, and reduces operational costs.”
The reaction mechanisms were particularly monitored as the researchers tried to understand the effect of Ru content and the distance and balance between metal and acid sites. Ru/zeolite-Y catalysts displayed a 96.9% conversion rate for polyolefins, under optimal conditions.
Additionally, a techno-economic analysis and life cycle assessment were conducted of this approach. The results provided insights into a real commercial-scale process of the proposed catalyst.
Dr Ro added, “The addition of water not only enhances carbon efficiency, it improves economic and environmental performance, and also increases the conversion of polyolefins to valuable fuels like gasoline and diesel. 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.”
The catalytic depolymerisation method could be game-changing as organisations try to resolve global plastic pollution levels. Dr Ro and his team hope that the solution will evolve until mixed plastic waste doesn’t need to be pre-sorted, making implementation simpler and recycling methods more cost-effective.
“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.