Researchers at Washington State University have developed one approach to recycling discarded plastics: turning them back into the petroleum products from which most of them came by using a process called hydrogenolysis. The scientists take polyethylene — which is better known as number 1 plastic — and apply heat, a chemical catalyst and solvents to break the material into jet fuel components or other hydrocarbon products. The process takes roughly an hour and a temperature of 220 degrees Celsius, or 428 degrees Fahrenheit, and converts 90% of the plastic into fuel. Researchers from the University of Washington and Pacific Northwest National Laboratory collaborated on the project.
“Converting waste plastics for fuel could significantly reduce the accumulated solid waste in landfills,” said Hongfei Lin, associate professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering at WSU, who led the study. “If the waste plastics are mismanaged, they will end up in oceans and slowly decompose to numerous microplastic particles, carrying contaminants and entering the food chain.”
Researchers have been using chemical recycling to turn plastics into fuel for many years, but the process can require temperatures of 300 degrees Celsius and much higher. The scientists from Washington employed a catalyst made from a rare metal called ruthenium that’s turned into nanoparticles and applied to a carbon substrate. The process also uses a common organic solvent.