Convert waste plastics to jet fuel in an hour


Washington State University researchers have developed an advanced method to convert plastics to components for jet fuel and other valuable goods, which makes it easier and more cost effective to reuse plastics.

The researchers in their reaction were able to convert 90 percent of plastic to jet fuel and other valuable hydrocarbon products inside one hour at moderate temperatures and also to easily fine-tune the procedure to make the products they want. Led by grad student Chuhua Jia and Hongfei Lin, associate professor at the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, they report on their job in the journal, Chem Catalysis.

“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.”

In recent decades, the accumulation of waste plastics has caused an environmental crisis, polluting seas and pristine environments around the globe. As they hamper, miniature parts of microplastics are found to enter the food chain and eventually become a possible, if unfamiliar, threat to human health.

Plastics conversion, however, has been problematic. The most common mechanical recycling methods melt the plastic and re-mold it, but lowers its economical value and quality for use in different products. Chemical recycling may produce higher quality products, but it’s required high reaction temperatures and a very long processing time, making it too expensive and cumbersome for industries to embrace. Due to its limitations, only about 9 percent of plastic from 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 widely used plastic, used in a massive number 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 plus a commonly used solvent. They could convert about 90% of their plastic to jet fuel parts or other hydrocarbon products inside one hour at a temperature of 220 degrees Celsius (428 degrees Fahrenheit), which is significantly more efficient and lower than temperatures which could be typically utilized.

Jia was surprised to see just how nicely the solvent and catalyst functioned to convert plastics.

“Before the experiment, we only speculated but didn’t know if it would work,” he said. “The result was so good.”

Fixing processing conditions, like the temperature, time or amount of catalyst used, given the critically important step of being able to fine-tune the conversion process to create desired products, Lin said.

“Depending on the market, they can tune to what product they want to generate,” he said. “They have flexibility. The application of this efficient process may provide a promising approach for selectively producing high-value products from waste polyethylene.”

With support from the Washington Research Foundation, the researchers are working to accelerate the process for future commercialization. They also believe their conversion procedure could work effectively with different kinds of plastics.

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