New Plastic Upcycling Technology: From Waste To Fuel for Less

With a recycling innovation for plastics, more may be produced with the same amount of precious metal ruthenium while also increasing conversion to valuable items. It will be presented at the American Chemical Society's autumn meeting in Chicago today, August 22, 2022.

The very low metal load is the main finding, according to the research team's leader, chemist Janos Szanyi of the Pacific Northwest National Laboratory (PNNL). "This greatly reduces the cost of the catalyst."

The new method, known as "upcycling," more effectively transforms plastics into valuable commodity chemicals. In addition, compared to other documented methods, it produces a lot less methane as a byproduct, a harmful greenhouse gas.

Postdoctoral research scientist Linxiao Chen, who presented the study at ACS, said, "It was really interesting to us that there had been no published work revealing this outcome. This study demonstrates the possibility of creating efficient, picky, and adaptable catalysts for the upcycling of plastic.

Recycling plastic offers a means to utilize the waste carbon that is currently clogging up landfills and beaches. Sara Levine's animation at Pacific Northwest National Laboratory's credit

In upcycling plastic, less metal is more.

Plastic trash made from petroleum is an undiscovered supply of carbon-based compounds that can be used as a building block for durable goods and fuels. Even though there are plenty of recycling bins available, relatively little plastic is actually recycled at the moment, mostly for logistical and financial reasons. Nevertheless, PNNL researchers are attempting to alter the dynamic by putting their knowledge of effectively rupturing molecular bonds to use.

The well-known hydrogenolysis reaction, which transforms hard-to-recycle plastics like polypropylene and polyethylene into tiny hydrocarbons with additional value, offers a viable method for recycling plastic waste. However, to make this process economically viable, efficient and selective catalysts are needed.

The research group discovered that lowering the amount of the pricey metal ruthenium actually increased the selectivity and efficiency of polymer upcycling. In a study that was recently published in the journal ACS Catalysis, it was demonstrated that the increase in efficiency occurred when the structure changed from an orderly array of particles to disordered rafts of atoms as a result of the low metal to support structure ratio.

The team was able to comprehend why less is more thanks to PNNL's track record of success with single-atom catalysts. By using well-established theory, the researchers were able to demonstrate that single atoms are really more efficient catalysts in this experimental work after observing the change from order to disorder at the molecular level.

The discovery was built on by Yong Wang, a professor of chemical engineering at Washington State University in Pullman and a fellow at PNNL Laboratory, who has studied single-atom catalysts and atom trapping.

The ability of single atoms or extremely small clusters to function as catalysts has drawn a lot of attention from the perspective of materials, according to Gutiérrez.

Chen also presented fresh research at ACS that examines how the support material might boost system effectiveness.

In order to substitute cerium oxide, Chen remarked, "We have looked into other readily available and less expensive support materials." We discovered that a chemically altered titanium oxide may allow for a more efficient and focused method for upcycling polypropylene.

The researchers are currently investigating how the presence of chlorine impacts the efficiency of the chemical conversion, in an effort to make the approach practicable for usage with mixed plastic recycling streams.

Oliver Y. Gutiérrez, a chemist and specialist in industrial catalysis, remarked, "We are looking into more difficult extraction conditions. "In an industrial upcycling process, chlorine from polyvinylchloride and other sources is used when there isn't a clean plastic source. The upcycling process for plastic can be contaminated by chlorine. We are interested in learning how chlorine affects our system.

Now that you know the basics, you might be able to turn waste plastic into valuable items instead of just polluting the environment.

Reference: Linxiao Chen, Laura C. Meyer, Libor Kovarik, Debora Meira, Xavier I. Pereira-Hernandez, Honghong Shi, Konstantin Khivantsev, Oliver Y. Gutiérrez, and János Szanyi, "Disordered, Sub-Nanometer Ru Structures on CeO2 are Highly Efficient and Selective Catalysts in Polymer Upcycling by Hydro

The Office of Science at the Department of Energy provided funding for the study. Additionally, the Advanced Photon Source, a user facility for the Office of Science run by Argonne National Laboratory for DOE, provided resources for this study.

By PACIFIC NORTHWEST NATIONAL LABORATORY