The innovation is called Low-Pressure Hydrothermal Processing. It promises an economically and environmentally safe way to transform polyolefin plastic, the most common form of plastic, into gasoline, diesel fuel and other high-value items. Developed by Linda Wang, the Maxine Spencer Nichols Professor in the Davidson School of Chemical Engineering, the research was published in a 2021 issue of the peer-reviewed journal Fuel.
The United Nations estimates that more than 8 million tons of plastics flow into the oceans each year. Of all the plastics produced over the past 65 years (8.3 billion tons), about 12% have been incinerated and only 9% have been recycled. The remaining 79% have gone into landfills or the oceans. The World Economic Forum predicts that by 2050, the oceans will hold more plastic waste than fish if the waste continues to be dumped into bodies of water.
“The key to solving this problem is to make it economically more attractive to collect and process the plastic waste stream into higher-value products at a significantly lower conversion cost,” said Dan Hasler, CEO of Hasler Ventures. “Current methods including incineration, pyrolysis and mechanical recycling have all proven to be ineffective or too costly, both financially and environmentally. They have not been able to draw the required private investment at a scale sufficient to divert the vast majority of the global 350 million tons of plastic waste produced annually from the landfill.
“We believe we can demonstrate first at pilot scale that hydrothermal processing is a less-expensive approach to produce fuels from plastic than from crude oil, making it a profitable venture to collect and process plastic, keeping it out of landfills and oceans.”
Purdue has put significant effort in this area for many years, said Mung Chiang, Purdueâs executive vice president for strategic initiatives and the John A. Edwardson Dean of the College of Engineering.
“Solving this plastic waste problem will greatly benefit the environment and future generations,” Chiang said.
The recently invented conversion process incorporates hydrothermal liquefaction and efficient separation. Once the plastic is converted into oil or naphtha, it can be used as a feedstock for other chemicals or further separated into monomers, specialty solvents, or other products. The clean fuels derived from the polyolefin waste generated each year can satisfy 4% of the annual demand for gasoline or diesel fuels. Some results of Wang’s study were published in ACS Sustainable Chemistry and Engineering in 2019 and Fuel in 2020 and 2021. A video about the process is available online.
Hasler Ventures is collaborating with American Resources Corp. (NASDAQ:AREC) to use its Indiana-based chromatography pilot plant, currently in development, to demonstrate the technology.
