A simple process to convert one of the most popular plastics into jet fuel could help fight the mountains of plastic waste rising in landfills around the world. Researchers from Washington State University reported the method in the journal Applied Energy.
Poly(ethylene terephthalate) (PET) is the ubiquitous plastic that is used to make grocery bags and water bottles. It can be recycled, but most all of it finds its way to landfills or litter in the environment. One reason for its abysmal recycling rates is that the reprocessed stuff just does not hold up in quality, making PET a very low-value waste.
Biological systems engineer Hanwu Lei and his colleagues decided to make jet fuel. They crushed PET waste such as water bottles, plastic bags, and milk jugs into tiny granules. Then they placed the granules on top of a bed of activated carbon in a reactor, which they heated to between 430–571ºC.
The activated carbon acts as a catalyst that helps break down the long hydrocarbon chains in the plastic, creating liquid hydrocarbon fuels. Once the process is complete, the catalyst can be separated and reused.
The researchers tried the experiment with seven types of commercial and homemade activated carbons. And they also tested the catalysts under different reaction conditions. The best setup yielded a mix of 85 percent jet fuel and 15 percent diesel fuel.
“We can recover almost 100 percent of the energy from the plastic we tested,” Lei said in a press release. “The fuel is very good quality, and the byproduct gasses produced are high quality and useful as well.”
According to the researchers, the method is easily scalable to work at a large processing facility.
Source: Yayun Zhang et al. Jet fuel production from waste plastics via catalytic pyrolysis with activated carbons. Applied Energy, 2019.
Photo: Bill Abbott, Flickr Creative Commons