EFRI E3P: A novel sequential catalytic solvolysis process for deconstructing municipal waste plastics

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Municipal plastic solid wastes represent a large, untapped source of energy and chemicals. Upcycling discarded plastics into high-value products could result in economic savings of billions of dollars and minimize negative environmental impact. However, municipal plastic waste streams are a mixture of various incompatible polymers such as polyethylene, polypropylene, polyvinylchloride, polyethylene terephthalate, and polystyrene, as well as polymer additives, dyes, and contaminants. As a result, recovering high-quality plastic materials from mixed solid municipal wastes by physical sorting is a challenge. Thermochemical recycling of waste plastics is not economical since the current processes require intensive energy inputs and costly product upgrading. Therefore, energy-efficient catalytic deconstruction processes are needed to overcome the chemical and physical challenges of recycling mixed plastics. This project will develop an innovative waste plastics chemical upcycling process that selectively converts co-mingled waste plastics to valuable monomers and chemicals. It aims to promote a plastics circular economy and mitigate the negative environmental impact caused by accumulated plastic wastes. Education and outreach activities will be integrated with the research program to facilitate student and workforce development and encourage the participation of students from underrepresented groups in STEM.The proposed waste plastics deconstruction approach is centered around the sequential catalytic solvolysis (SeCatSol) process. The SeCatSol process is a novel technology being developed at Washington State University for the selective stage-by-stage deconstruction of an individual polymer or classes of polymers in a polymer mixture using robust organocatalysts and heterogeneous catalysts under mild conditions. The SeCatSol process is designed to address the grand challenge in the plastic industry: how to deconstruct co-mingled municipal waste plastics selectively. The SeCatSol process sequentially produces monomers or value-added chemical products in each catalytic conversion unit, providing a feasible “Chemical Sorting” method to upcycle the complex municipal plastic mixtures at a molecular level. A systematic team effort aims at developing highly selective catalysts and efficient solvents for the SeCatSol process. In particular, the advanced in-situ and operando characterization tools, such as NMR, ATR-FTIR, and Raman spectroscopy, will decipher the complexity of deconstructing waste plastics. Furthermore, novel predictive molecular computational methods will accelerate catalyst design and solvent selection. The proposed technology framework fits into a circular economic model that is restorative and regenerative by design. This project represents the transformative work required for the significant advancement of fundamental polymer science and engineering knowledge.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.