In the United States, less than 9% of plastic waste is recycled. Instead, more than 75% of plastics waste ends up in landfills and up to 16% is burned, a process that releases toxic gases into the atmosphere. Researchers from the University of Delaware’s Center for Plastics Innovation (CPI) have developed a direct method to convert single-use plastic waste – plastic bags, yogurt containers, plastic bottles and bottle caps, packaging and more – to ready-to-use molecules for jet fuels, diesel and lubricants. The work, reported in a paper in Science Advances on Wednesday, April 21, focuses on using a novel catalyst and unique process to quickly break down these hardest-to-recycle plastics, known as polyolefins. Polyolefins account for 60 to 70% of all plastics made today.
The UD research team used a chemical process called hydrocracking to break down the plastic solids into smaller carbon molecules, then added hydrogen molecules on either end to stabilize the material for use. Catalytic cracking is not new. Refineries have used it to convert heavy crude oil into gasoline for years. The research team’s method, however, does more than just break the plastic down. It also converts the material into branched molecules that allow them to be more directly translated into an end product. ”This makes them ready-to-use molecules for high-value lubricant or fuel applications,” said Vlachos, who also directs the Delaware Energy Institute and the Catalysis Center for Energy Innovation at UD.
The catalyst itself is actually a hybrid material, a combination of zeolites and mixed metal oxides. Zeolites are known to have properties that make them good at creating branched molecules. Zeolites are found in things like water purification or softener systems and home detergents, where they counteract minerals like calcium and magnesium, making hard water softer and improving the laundry process. ”This innovative catalytic approach is a significant advance in our quest for depolymerization processes that involve less energy intensive pathways and generate highly specific breakdown targets, said CPI Director LaShanda Korley, Distinguished Professor of Materials Science and Engineering and Chemical and Biomolecular Engineering. ”This fundamental understanding opens up a new route toward plastics waste valorization.”
Source: Eurek Alert!
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