While millions of tons of plastic are produced in the US each year, only around 9 percent is recycled, and that is largely due to the difficulties around reducing the material to useful building blocks for other products. A new chemical treatment developed by scientists at Washington State University (WSU) could help chip away at this problem – a treatment that's been demonstrated by turning the most commonly used plastic into jet fuel components within one hour.
The idea of using chemical reactions to convert plastics into the building blocks for jet fuel and similar products is one scientists have been exploring for some time. By taking the material and combining it with catalysts under high temperatures, it can be reduced to organic compounds called hydrocarbons, which are made up of hydrogen and carbon and act as the building blocks for different types of fuel.
Where this latest study breaks new ground is in the relatively moderate temperatures and short timeframe required to carry out this process. The WSU researchers were experimenting with the catalysts and conditions needed to convert polyethylene, the plastic used in everything from shopping bags to shampoo bottles, into hydrocarbons, and have come up with a new methodology.
Using a catalyst made from carbon and the silvery-white metal ruthenium, along with some commonly used solvents, the scientists were able to convert around 90 percent of the plastic into the components for jet fuel, and other hydrocarbons, within one hour. This took place at around 220 °C (428 °F), much friendlier – and more economically viable – conditions than the temperatures required for a similar process we looked at in 2019, of around 500 °C (932 °F).
“Before the experiment, we only speculated but didn’t know if it would work,” says study author Chuhua Jia. “The result was so good.”
Through their experimentation, the team found the process could be tweaked to produce building blocks for other high-value products, such as lubricants. This involved simply altering the temperature, the amount of catalyst used or the timeframe to change the end result.
“Depending on the market, they can tune to what product they want to generate,” says study author Hongfei Lin. “They have flexibility. The application of this efficient process may provide a promising approach for selectively producing high-value products from waste polyethylene.”
The researchers are now working to scale up this process with an eye on commercializing the technology, and hope to adapt it to tackle other forms of plastic waste.
“In the recycling industry, the cost of recycling is key,” Lin said. “This work is a milestone for us to advance this new technology to commercialization.”
The research was published in the journal Chem Catalysis.
Source: Washington State University
