Purdue University researchers have created a new chemical conversion technique that could turn 90 percent of polyolefin waste, a common form of plastic, into more beneficial products like clean fuels, pure polymers, naphtha and monomers.
The team incorporated both selective extraction and hydrothermal liquefaction in the new conversion process, so when the polyolefin plastic is converted into naphtha, it can be used as a feedstock for other chemicals or also further separated into specialty solvents or other products.
In the study, model polypropylene was converted into oil using supercritical water at temperatures between 380 and 500 degrees Celsius and 23 MPa pressure over a reaction time of 0.5-6 hours. They found that higher reaction temperatures or longer reaction times led to more gas products.
The researchers are working to optimize the process that will allow them to produce high-quality gasoline or diesel fuels and the conversion process is a net-energy positive and potentially has a higher energy efficiency and lower greenhouse gas emissions than incineration and mechanical recycling.