Scientists at Northwestern University, together with Purdue University, have unveiled a powerful new catalyst that could transform the way we recycle plastics. For decades, recycling has been limited by the need to carefully sort different types of plastics and thoroughly clean them. Even small amounts of contamination often ruined entire batches. Now, researchers report a nickel-based catalyst that overcomes these hurdles, recycling mixed and even dirty plastics with impressive efficiency.
Tackling Polyolefins, the Biggest Challenge
Polyolefins such as polyethylene and polypropylene dominate consumer plastics, appearing in milk jugs, condiment bottles, bags, and films. These plastics make up over 220 million tons of global production annually but are notoriously difficult to recycle because of their strong chemical bonds. In fact, less than 10 percent—and in some cases under 1 percent—ever get reused. Traditional methods require sorting and operate at extreme temperatures, making them costly and energy-intensive.
The Breakthrough with Nickel
The team’s new single-site nickel catalyst uses hydrogenolysis to selectively break down plastics at far lower temperatures and pressures than earlier systems. Unlike platinum or other precious metals, nickel is inexpensive and abundant, opening the door to large-scale applications. The catalyst not only requires less material but also shows ten times greater activity. Acting like a molecular scalpel, it can even distinguish between branched and unbranched polymers when both are present in a mixture.
Recycling Without Sorting or Cleaning
Perhaps the most surprising discovery is that the process tolerates contamination. Small amounts of polyvinyl chloride (PVC), usually considered a poison in recycling, actually help regenerate the catalyst. This means even dirty plastics or unsorted household trash could be fed into the process. The output is valuable oils and waxes that can be turned into fuels, lubricants, or everyday products like candles.
By eliminating the need for sorting and cleaning, this approach could redefine recycling. If scaled up, it offers a practical and affordable path to reducing plastic waste and moving toward a truly circular economy.
