The proliferation of plastic products has created an environmental challenge: what should be done with unusable, discarded plastic waste that can harm the environment? Faculty from the Department of Chemical and Biological Engineering are working on a National Science Foundation (NSF)-funded project, Hydrogenolysis for Upcycling of Polyesters and Mixed Plastics, to address this serious environmental issue.
Denver Business Challenge Endowed Professor Will Medlin, James and Catherine Patten Endowed Professor Ryan Hayward, Assistant Professor Kayla Sprenger, Professor Michael Toney and their respective groups are collaborating on this project, which the NSF is funding through a $2 million grant.
“Figuring out how to deal with post-consumer plastic waste is a major societal problem,” Medlin said. “We were all independently interested in working on this problem, but were approaching it from different angles. Ryan is an expert on how plastics are formed and could be degraded, Mike is an expert on developing experimental tools to understand the interfaces between materials that arise in chemical upcycling of plastics, Kayla is an expert on computational modeling studies of similar interfaces and my group works on catalysts for depolymerization.”
Given the complexity of the problem, the researchers decided to combine their diverse yet complementary approaches to address problems in chemical upcycling. The Medlin group has been working on the conversion of biomass-derived polymers to renewable products for the last several years.
“Although plant-made polymers are certainly different from man-made plastics, some of the essential catalyst processes are quite similar,” Medlin said. “You’re trying to break apart a macromolecule into specific units that can be made into useful products. Extending our work to plastics upcycling made sense based on the group's general focus, and students are highly motivated to work on this critical environmental problem.”
The Hayward group will work on characterizing how the polymers in question are catalytically deconstructed — specifically how the polymers interact with the catalyst support surfaces and how the polymer chain lengths evolve as the reactions proceed.
“Enabling a shift to a more sustainable use of polymers, where the vast majority are recycled or converted to higher value products rather than being discarded after a single use is one of the most important challenges facing materials scientists today,” Hayward said. “We were very excited about the opportunity to join this team and to be able to work towards a very promising route toward deconstructing polymers into high value products.”
Toney said that his group will contribute research that focuses on the interfacial interactions between the catalyst, support and polymers as they react. This will require the development of new 'operando' experimental tools to observe the reactions in real-time.
“My research is largely motivated by helping to solve the sustainability challenges facing humanity by helping to develop new materials and processes,” Toney said. “Eliminating plastic waste is one such challenge perhaps most popularly seen by reports of ‘The Great Pacific Garbage Patch.’ This is my first research effort aimed at helping the team develop more effective methods to eliminate plastic waste.”
Medlin also credited Adjoint Professor Gregg Beckham as being a key part of the team. Beckham, who also works at NREL, will be contributing his expertise in plastics upcycling and conducting technoeconomic analyses of the processes the collaboration develops. Professor Andreas Heyden from the University of South Carolina will also conduct quantum mechanical simulations to understand the atomic-scale interactions between plastics and active catalysts, which will complement the Sprenger group’s efforts.
This grant was funded through the NSF Directorate for Engineering’s Emerging Frontiers in Research and Innovation program.