Plastics are valued for their strength and durability, but those same qualities make them difficult to break down. Global recycling systems rely heavily on mechanical processes that degrade polymer quality with each cycle, and chemical upcycling methods often struggle to access polymer chains efficiently. As a result, waste continues to accumulate, while microplastics spread through ecosystems and supply chains.
Researchers at the University of Delaware have reported a new catalyst design that could accelerate the transformation of plastic waste into liquid fuels. The team, led by Dongxia Liu, the Robert K. Grasselli Professor of Chemical and Biomolecular Engineering, developed a catalyst built from MXenes: two-dimensional nanomaterials; modified with silica pillars and ruthenium nanoparticles. Their work, shows that the catalyst significantly increases both the speed and selectivity of hydrogenolysis reactions.
Kamali, A., Little, J. M., Luo, S., Chen, A., Warty, A., Bhowmick, A., Moncada, J., Jahrman, E. P., Vance, B. C., Keum, J. K., Woehl, T. J., Chen, P.-Y., Vlachos, D. G., & Liu, D. (2025). Plastic-waste hydrogenolysis over two-dimensional MXene-supported ruthenium catalysts with tunable interlayer spacing. Chem Catalysis, 101459. https://doi.org/10.1016/j.checat.2025.101459
Hydrogenolysis involves breaking down polymer chains using hydrogen gas in the presence of a catalyst, producing smaller hydrocarbon molecules that can serve as liquid fuels. The challenge lies in enabling bulky polymer molecules, such as those in polyethylene, to access the catalyst’s active sites. In conventional catalysts, access is often restricted, leading to slower reactions and a wider mix of byproducts. The Delaware team addressed this by transforming MXene layers, which resemble the pages of a tightly closed book, into a more open structure. By inserting silica pillars between the layers, they created larger pores that allowed molten plastic to flow more easily. Ruthenium nanoparticles embedded in this space acted as active catalytic centers.
Dongxia Liu, Professor of Chemical and Biomolecular Engineering at UD’s College of Engineering stated,
“Instead of letting plastics pile up as waste, upcycling treats them like solid fuels that can be transformed into useful liquid fuels and chemicals, offering a faster, more efficient and environmentally friendly solution”.
When tested with low-density polyethylene (LDPE), a material used in items such as plastic bags and packaging films, the catalyst nearly doubled the reaction rate compared to earlier designs. Just as important, it improved selectivity, producing more liquid fuels while minimizing the formation of methane, a greenhouse gas often generated as a byproduct in similar processes. The researchers attribute this to the stabilization of ruthenium nanoparticles within the widened MXene layers, which created a more controlled catalytic environment.
The work highlights how careful engineering at the nanoscale can influence large-scale environmental outcomes. By opening pathways within MXene layers, the team demonstrated that it is possible not only to speed up conversion but also to enhance the quality of the products generated. Liu noted that treating plastics as a feedstock for fuel rather than as waste could provide a more sustainable alternative to disposal or low-value recycling.
The study represents a step forward for the University of Delaware’s Center for Plastics Innovation, which is supported by the U.S. Department of Energy. The center’s broader mission is to develop scalable technologies that convert plastic waste into valuable fuels and chemicals.
Looking ahead, the researchers intend to expand their work to other types of plastics to test the versatility of the catalyst design. They also recognize that scaling up from laboratory reactors to industrial volumes will bring challenges, from the cost of producing MXenes and sourcing ruthenium to ensuring the long-term stability of the catalyst. Assessments of the environmental and economic impacts of the process will also be necessary to determine its feasibility compared to existing recycling and fuel production methods.
While there is more work to be done, this advance underscores the potential for nanostructured catalysts to play a role in addressing the plastic waste problem. By converting polymers into liquid fuels more quickly and cleanly, the MXene-supported ruthenium system offers a new pathway that bridges chemical engineering innovation with sustainability goals.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
