Methodology for integrating lumped kinetic models and decision-making frameworks to enhance sustainability of plastic waste pyrolysis

To effectively evaluate the feasibility of plastic waste via chemical routes such as pyrolysis, decision-makers need comprehensive economic and environmental assessments based on reliable sustainability metrics, which are derived from navigating complex interactions across multiple scales. Despite the extensive research in this field, a significant gap remains in linking these scales through a common working framework. This work presents a methodology, with steps and checklists that bridge laboratory experimental results to high-level decision-making, demonstrated using plastic waste pyrolysis to fuels. From the experimental laboratory data, a 4-lumped kinetic model was incorporated in 1D pseudo-homogeneous plug flow reactor model to predict the reactor performance. The reactor performance was examined by varying residence time, heat transfer coefficient, and wall temperature, focusing on their impact on product. The conditions that gave the lowest reactor energy consumption and maximum plastic throughput were selected for further analysis. Two process flow sheets were constructed around this case: one using gas products for heat supply and another producing LPG (C2–C3) with liquid products. The results from the developed processes are benchmarked against five systems from the literature using multicriteria analysis on annual cost, product sales, profit, and circularity. The study showed that using gas to supply heat in pyrolysis maximized circularity (DOCI = 0.6) due to resource efficiency, whereas selling LPG (C2–C3) along with the liquid products yields the highest profit 2.2 MM USD/y. Overall, the variability in results highlights the potential of this one common framework methodology toward making decision more visible right from laboratory investigation, addressing the lack of methodological integration across the scales including modeling gaps, and identifying the most sustainable option for plastic waste conversion.