(403h) Advancing Plastic Waste Recycling through Refinery-Compatible Poly-Crude: Insights from Techno-Economic and Life Cycle Analyses

Chemical recycling has emerged as a promising pathway for valorizing plastic waste by converting it into high-quality chemical products comparable to those derived from fossil resources. However, the development and deployment of these innovative solutions remain limited by the high energy, economic, and operational efficiencies of conventional petroleum refining¹. These advantages make it challenging for emerging recycling technologies to compete with fossil-based production on a scale. In this study, we propose an alternative approach in which plastic waste is transformed into a refinery-compatible feedstock, termed ‘poly-crude’. ‘Poly-crude’ is an energy-dense liquid that can be directly integrated into existing refinery processes, leveraging the refinery efficiencies while reducing the reliance on fossil resources. To produce poly-crude, we selected hydrocracking as the conversion pathway due to its ability to maximize plastic waste conversion into valuable liquid oil with high paraffinic content^2,3, aligning with the composition requirements of refinery feedstocks⁴.

Our work aims to develop an agile techno-economic and environmental assessment of poly-crude manufacturing at the early stage of technological development. First, we created a model that combines process insights from both chemical recycling technologies^5,6 and petroleum refining processes⁷, with hydrocracking reaction performance adapted from recent studies^3,8. In addition, we include the dilution of plastic waste into a suitable solvent before it enters the reactor to overcome extremely slow transport in polymer melts. The entire system was developed in Python as an open-source tool, leveraging the QSDsan package⁹. The techno-economic analysis (TEA) and life cycle assessment (LCA), were integrated into the same framework, enabling flexible evaluation of scenarios across varying reaction conditions and linking outcomes to key economic and environmental metrics. Uncertainty and sensitivity analyses were conducted to identify key drivers and assess the probability of sustainability outcomes.

Our results indicate that the economic viability of poly-crude manufacturing is most sensitive to poly-crude yield, hydrogen demand, and plastic waste concentration in the solvent. The LCA incorporated emission factors from the GREET model¹⁰ to determine the greenhouse gas (GHG) emissions. The environmental assessment identifies hydrogen demand, electricity consumption, and heating utilities as the primary contributors to the process’s GHG emissions. Building on these insights, we conducted scenario analysis under varying reaction conditions to explore how reaction performance influences both TEA and LCA outcomes. These analyses reveal key trade-offs between economic and environmental performance, offering valuable insights to guide future research. In particular, future development efforts should focus on optimizing reaction pathways and catalyst design to advance the development of sustainable poly-crude manufacturing.

References:

(1) Forman, G. S.; Divita, V. B.; Han, J.; Cai, H.; Elgowainy, A.; Wang, M. U.S. Refinery Efficiency: Impacts Analysis and Implications for Fuel Carbon Policy Implementation. Environ. Sci. Technol. 2014, 48 (13), 7625–7633. https://doi.org/10.1021/es501035a.

(2) Liu, S.; Kots, P. A.; Vance, B. C.; Danielson, A.; Vlachos, D. G. Plastic Waste to Fuels by Hydrocracking at Mild Conditions. Sci. Adv. 2021, 7 (17), eabf8283. https://doi.org/10.1126/sciadv.abf8283.

(3) Rorrer, J. E.; Ebrahim, A. M.; Questell-Santiago, Y.; Zhu, J.; Troyano-Valls, C.; Asundi, A. S.; Brenner, A. E.; Bare, S. R.; Tassone, C. J.; Beckham, G. T.; Román-Leshkov, Y. Role of Bifunctional Ru/Acid Catalysts in the Selective Hydrocracking of Polyethylene and Polypropylene Waste to Liquid Hydrocarbons. ACS Catal. 2022, 12 (22), 13969–13979. https://doi.org/10.1021/acscatal.2c03596.

(4) Munir, D.; Irfan, M. F.; Usman, M. R. Hydrocracking of Virgin and Waste Plastics: A Detailed Review. Renewable and Sustainable Energy Reviews 2018, 90, 490–515. https://doi.org/10.1016/j.rser.2018.03.034.

(5) Hernández, B.; Kots, P.; Selvam, E.; Vlachos, D. G.; Ierapetritou, M. G. Techno-Economic and Life Cycle Analyses of Thermochemical Upcycling Technologies of Low-Density Polyethylene Waste. ACS Sustainable Chem. Eng. 2023, 11 (18), 7170–7181. https://doi.org/10.1021/acssuschemeng.3c00636.

(6) Dutta, A.; Sahir, A.; Tan, E. Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbon Fuels: Thermochemical Research Pathways with In Situ and Ex Situ Upgrading of Fast Pyrolysis Vapors.

(7) Robinson, P. R.; Dolbear, G. E. Hydrocracking. In Springer Handbook of Petroleum Technology; Hsu, C. S., Robinson, P. R., Eds.; Springer Handbooks; Springer International Publishing: Cham, 2017; pp 713–776. https://doi.org/10.1007/978-3-319-49347-3_22.

(8) Celik, G.; Kennedy, R. M.; Hackler, R. A.; Ferrandon, M.; Tennakoon, A.; Patnaik, S.; LaPointe, A. M.; Ammal, S. C.; Heyden, A.; Perras, F. A.; Pruski, M.; Scott, S. L.; Poeppelmeier, K. R.; Sadow, A. D.; Delferro, M. Upcycling Single-Use Polyethylene into High-Quality Liquid Products. ACS Cent. Sci. 2019, 5 (11), 1795–1803. https://doi.org/10.1021/acscentsci.9b00722.

(9) Li, Y.; Zhang, X.; Morgan, V. L.; Lohman, H. A. C.; Rowles, L. S.; Mittal, S.; Kogler, A.; Cusick, R. D.; Tarpeh, W. A.; Guest, J. S. QSDsan: An Integrated Platform for Quantitative Sustainable Design of Sanitation and Resource Recovery Systems. Environ. Sci.: Water Res. Technol. 2022, 8 (10), 2289–2303. https://doi.org/10.1039/D2EW00455K.

(10) Wang, M.; Elgowainy, A.; Lee, U.; Bafana, A.; Banerjee, S.; Benavides, P.; Bobba, P.; Burnham, A.; Cai, H.; Gracida, U.; Hawkins, T.; Iyer, R.; Kelly, J.; Kim, T.; Kingsbury, K.; Kwon, H.; Li, Y.; Liu, X.; Lu, Z.; Ou, L.; Siddique, N.; Sun, P.; Vyawahare, P.; Winjobi, O.; Wu, M.; Xu, H.; Yoo, E.; Zaimes, G.; Zang, G. Green House, Regulated Emissions, and Energy Use in Technologies Model, 2021. https://greet.anl.gov/index.php?content=greetdotnet.