Many MindedRostock chemists dissolve plastic bags into building blocks for nylon
Chemists at the Leibniz Institute for Catalysis (LIKAT) in Rostock, Germany, have selectively converted polyethylene into dicarboxylic acids, which can serve as precursors for nylon (polyamide). Pieces of plastic, such as bag fragments, are placed in highly diluted nitric acid with hydrogen peroxide and heated to no more than 120°C. The polyethylene dissolves, and no catalyst is needed.
The work is led by group leader Dr. Esteban Mejía, with postdoctoral researcher Dr. Satyajit Panda, who has worked on it since April 2026. Heat must follow a specific regime. The conversion has several stages, and leaving intermediates too long yields a complex mixture. Earlier published work on this route used concentrated nitric acid at 180°C in a microwave and produced chains of 2 to over 40 carbons, suited to soap surfactants. The team has now narrowed that range to four to ten carbons.
The comparison is with pyrolysis, which runs at up to 600°C with a heavy energy and CO2 cost, and with oxidation routes that need explosive high pressure and precious-metal catalysts. Polyethylene and polypropylene make up about four-fifths of an estimated 400 million metric tons of plastic waste a year. Roughly 8 million metric tons of polyamide are made yearly, mainly from petroleum. A gentler route from waste to nylon feedstock could give discarded plastic real value and loosen a material's tie to oil.
The caveats are large. Nylon needs a dicarboxylic acid with exactly six carbons, and the product still spans four to ten. Selectivity must improve, the mechanism is not understood, and pilot-plant scale has not been reached. The JACS paper is still in preparation, funding has been applied for but not confirmed, and planned separation work with Dr. Udo Kragl is not yet done. A conference talk in Singapore is planned for December.
Source: Phys.org