(170c) Techno-Economics Analysis and Life Cycle Assessment for Pyrolysis of Mixed Waste Plastics

Catalytic fast pyrolysis (CFP) is a promising approach to convert mixed plastic waste stream into valuable chemicals. To guide research and development further towards commercialization of plastics pyrolysis, economics and environmental impacts must be considered. In this work, we present a conceptual process design with techno-economic analysis (TEA) and supply chain analysis using Aspen Plus and Materials Flows through Industry (MFI), wherein mixed plastics are thermally depolymerized, and the resulting vapors upgraded catalytically to produce a suite of aromatics, olefins, and pyrolysis – naphtha (py-naphtha).

The base case model predicts a minimum selling price (MSP) for BTX aromatics at a zero net present value (NPV) for an n^th plant with a 30-year plant life. The credits from the sale of multiple co-products significantly lower the overall costs. Feedstock cost, solvent cost, and discount rate are identified as key economic drivers through sensitivity analysis. A multivariate analysis was conducted to reflect the impact of fluctuations of WTI crude oil price on the different product and co-products obtained in this work. As catalyst research progresses, two scenarios based on high olefins and aromatics production were proposed, both of which show a potential reduction in MSP vis-à-vis the base case. Overall, this study suggests that research should prioritize ways to increase yields of industrially relevant products, minimize solvent loading, utilize low-value polymers such as films and flexibles that are currently discarded, and facilitate integration with petrochemical refineries.