The growing volume of plastic waste worldwide points to the need for end-of-life alternatives to traditional recycling. A novel upcycling process has been developed to convert some of these wastes into sustainable liquid fuels.

The conversion scheme is based on a new type of catalyst that overcomes the limitations of conventional offerings in attracting bulky polymers to active site. MXenes, a type of two-dimensional inorganic compound, were converted into mesoporous MXene-supported ruthenium catalysts, which offer larger, more open pores for plastic upcycling. Silica pillars were inserted to widen the space between MXene layers, allowing the polymers and intermediate compounds that form during the reaction to flow more easily.

The catalyst was tested with low-density polyethylene (LDPE), a plastic commonly used in shopping bags and plastic films, in a small pressurized reactor. The LDPE was combined with the catalyst and hydrogen gas and heated, resulting in a thick syrup. Reaction rates nearly two times faster than those previously reported for LDPE hydrogenolysis were documented. The high selectivity of the catalyst supported targeted production of liquid fuels while minimizing undesired byproducts like the greenhouse gas methane.

“We were able to produce a material that not only speeds the conversion but also improves the quality of the fuel products. This advance highlights the potential of nanostructured mesoporous catalysts to enhance plastic upcycling,” said the researchers.

This development achieved by researchers from the University of Delaware, University of Maryland, U.S. Army Combat Capabilities Development Command Army Research Laboratory, U.S. National Institute of Standards and Technology, Theiss Research and U.S. Oak Ridge National Laboratory is published in Chem Catalysis.