Northwestern Researchers Develop Catalyst for No-Sort Plastic Recycling
Scientists at Northwestern University say they have developed a new catalyst that could eliminate one of the biggest hurdles in plastics recycling: the need to sort waste by resin type.
The nickel-based catalyst selectively breaks down polyolefins including polyethylene and polypropylene. But the process can handle mixed waste and even works in the presence of PVC.
"This could bypass the costly, labor-intensive step of pre-sorting polyolefin plastics," said Tobin Marks, senior author of the study published Sept. 2 in Nature Chemistry. "It makes recycling more efficient, practical and economically viable than current strategies."
The new method transforms low-value solid plastics into oils and waxes, which can be upcycled into higher-value products such as lubricants, fuels and candles. Researchers say the catalyst is inexpensive, stable, and can be regenerated for multiple cycles.
Northwestern chemist Yosi Kratish said the process also shows tolerance for other polymers, including nylon and fluoropolymers, and may be compatible with PET.
"Basically, almost everything in your refrigerator is polyolefin based," Kratish said. "If we don't have an efficient way to recycle them, they end up in landfills and in the environment, where they linger for decades before degrading into harmful microplastics."
Qingheng Lai, the study's lead author and a research associate in Marks' group, said the team began developing the catalyst in mid-2023. Lai added that the process is being advanced in collaboration with Dow Inc. and could offer a lower carbon footprint than existing chemical recycling methods.
"The key challenges ahead are scaling up catalyst production, testing the process at large scale, and expanding the range of mixed and post-consumer plastics the system can handle," Lai said in response to questions from Plastics News.
The work at Evanston, Ill.-based Northwestern is supported by the U.S. Department of Energy and Dow.