(612f) A Practical and Flexible Approach for Accurately Modeling the Pyrolysis of Waste Plastics

Pyrolysis is a promising pathway in establishing a circular economy for plastics by recycling plastic waste into valuable fuels and chemicals. In this study, the method of moments is applied to develop a practical model for the pyrolysis of the main plastics in waste feeds. However, modeling the complex behavior of thermal chemistry, especially for low molecular weight species, presents significant challenges due to the specialized nature of radical formation and stability. In this work, a set of moment equations characterizes the bulk distribution of polymer chain length degradation, with specific constitutive equations related to low molecular weight species to capture key features of the hydrogen shift and β-scission reactions that lead to preferential formation of specific products. The model is validated against experimental data and can accurately capture the pyrolysis process, including the temperature-dependent formation and evolution of the products, their overall yields, and the transition of polymer properties during degradation. This approach provides a practical model of plastic pyrolysis in a flowsheeting environment, facilitating the design and optimization of useful waste plastic recycling systems.