Washington State University researchers have developed an innovative way to convert plastics to ingredients for jet fuel and other valuable products, making it easier and more cost effective to reuse plastics.
The researchers in their reaction were able to convert 90% of plastic to jet fuel and other valuable hydrocarbon products within an hour at moderate temperatures and to easily fine-tune the process to create the products that they want. Led by graduate student Chuhua Jia and Hongfei Lin, associate professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, they report on their work in the journal, Chem Catalysis.
In recent decades, the accumulation of waste plastics has caused an environmental crisis, polluting oceans and pristine environments around the world. As they degrade, tiny pieces of microplastics have been found to enter the food chain and become a potential, if unknown, threat to human health.
Plastics recycling, however, has been problematic. The most common mechanical recycling methods melt the plastic and re-mold it, but that lowers its economic value and quality for use in other products. Chemical recycling can produce higher quality products, but it has required high reaction temperatures and a long processing time, making it too expensive and cumbersome for industries to adopt. Because of its limitations, only about 9% of plastic in the U.S. is recycled every year.
In their work, the WSU researchers developed a catalytic process to efficiently convert polyethylene to jet fuel and high-value lubricants. Polyethylene, also known as #1 plastic, is the most commonly used plastic, used in a huge variety of products from plastics bags, plastic milk jugs and shampoo bottles to corrosion-resistant piping, wood-plastic composite lumber and plastic furniture.
For the process, the researchers used a ruthenium on carbon catalyst and a commonly used solvent. They were able to convert about 90% of the plastic to jet fuel components or other hydrocarbon products within an hour at a temperature of 220 degrees Celsius (428 degrees Fahrenheit), which is more efficient and lower than temperatures that would be typically used.