EPSCoR Research Fellows: NSF: Understanding the effects of tunable media on mass transport during catalytic conversion of polyolefins

The increasing production and low recyclability of legacy plastics, such as polyolefins, pose a significant environmental challenge. Despite ongoing development of chemical processes to convert waste polyolefins into valuable products, polyolefins’ long carbon chains, high melt viscosity, and low diffusivities create substantial reaction engineering issues. These issues lead to transport-limiting kinetics, low product selectivity, and low product yields. This fellowship project aims to explore how tunable media can improve the transport properties of the reaction medium and impact the catalytic conversion of polyolefins, notably polyethylene (PE), into hydrocarbon fuels. Using high-temperature and high-pressure in situ/operando spectroscopy tools, the team will study the transport properties of PE melt in the presence of CO2-tunable media and gather detailed molecular-level information on the transformations during catalytic conversion. This fellowship will promote partnerships between academic institutions, boost STEM workforce development, and strengthen the State of Kansas’ competitiveness to attract federal and industrial research funding. This Research Infrastructure Improvement (RII) EPSCoR Research Fellows project will provide a fellowship to an Assistant professor and training for a graduate student at the University of Kansas Center for Research Inc. This work will be conducted in collaboration with researchers at Washington University, St. Louis. Although supercritical CO2 is commonly used to reduce the viscosity of polymer solutions, its full potential in enhancing the catalytic transformation of waste polyolefins remains unexplored. The primary objectives of the fellowship project are to investigate how CO2-tunable media affect the transport properties of PE melt, and to determine the impact of CO2-tunable media on the catalytic conversion kinetics of PE. Pulsed Field Gradient (PFG) Nuclear Magnetic Resonance (NMR) will be leveraged to measure the diffusivities of PE melt, intermediates, and reactants within porous catalysts in the presence of sub- and supercritical CO2. Operando Magic-Angle Spinning (MAS) NMR will enable real-time monitoring of reactions, providing detailed molecular-level insights into the transformations during hydrocracking of PE across various catalysts and reaction conditions. Such knowledge is transformative, offering new design principles for optimizing conversion processes for waste polyolefins, which can be applied to other chemical processes and other postconsumer plastics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.