Researchers at Worcester Polytechnic Institute (WPI) have discovered a new method to turn used cooking oil into chemicals that could be made into paint or, potentially, into plastic products. The discovery could help lessen reliance on petroleum and find a renewable alternative to it. The study was recently published in ACS Sustainable Chemistry & Engineering.
Until now, used cooking oil had mostly been treated as waste, with a fraction used to produce biodiesel fuel. Now the WPI team has expanded that work to an alternative technology. The innovation comes from the use of the catalyst ZSM-5, a different type of catalyst than had been used in past research.
The team started with palmitic acid, a saturated fat common in cooking oils and found naturally in olive, soybean, sunflower, and palm oils, and other natural products such as dairy and meat, as well as many skincare products. The researchers then added the catalyst and a small amount of water to the mixture.
“When you combine nano-scale catalysts and water, you get a sweet spot where you have a more rapid conversion and selectivity for these chemicals,” said Michael Timko, professor of chemical engineering.
They then turned up the heat—bringing the mixture to 400 degrees Celsius. The team used another common kitchen item—a pressure cooker—to keep the water from escaping the mixture by turning it into steam. “The pressure cooker doesn’t let steam out; it just keeps building up pressure, and when you do that, the properties of water change,” said Timko.
The interaction between the catalyst and the pressurized water promotes formation of industrial chemicals known as one-ring aromatics. Other components, such as pigments, are then added to the mixture, to make the paint.
The study originally began as a WPI undergraduate student’s Major Qualifying Project, the culmination of the university’s project-based education. Now, the research is getting closer to being available for real-world applications. The next steps for this project include evaluating the technology in a continuous process, as well incorporating cooking oil that has been used in the cooking process, rather than using a model compound.
Researchers from the University of Massachusetts, Syracuse University, Zoex Corporation, and the University of Bath (United Kingdom) contributed to the study, which was also partially funded by a National Science Foundation (NSF) grant to Syracuse University.