(2025) Chemical Engineering Journal_Sustainable production of methanol from waste expanded polystyrene via CO2-assisted catalytic pyrolysis-based process: Techno-economic analysis and life cycle assessment

Choi D.; Park J.; Lee J.; Kwon E.E.; Cho H.

(Elsevier B.V.) Chemical Engineering Journal ISSN: 13858947 Vol.525 Issue. Article No.170031 DOI: 10.1016/j.cej.2025.170031

Waste expanded polystyrene (EPS) has surged in marine environments, harming ecosystems and human health. Therefore, an appropriate disposal method is urgently required. This study proposes a sustainable approach for converting waste EPS into methanol (MeOH) based on CO₂-assisted catalytic pyrolysis. MeOH is regarded as next-generation low-carbon fuel in the maritime sector. Experimental investigations on catalytic pyrolysis of waste EPS demonstrated that presence of CO₂ enhanced syngas formation via gas-phase reactions with volatile matters. The syngas yield from catalytic pyrolysis of waste EPS under N₂ and CO₂ were 64.5 and 161.1 mmol, respectively. Based on these findings, two waste EPS-to-MeOH conversion processes involving catalytic pyrolysis under N₂ and CO₂ (Strategies A and B, respectively) were developed. Strategy B achieved 11,356 metric tons yr⁻¹ of MeOH productivity, approximately five times that of Strategy A (2,197 metric tons yr⁻¹). The levelized cost of production (LCOP) of MeOH was reduced in Strategy B ($1052 metric ton⁻¹) compared to Strategy A ($2098 metric ton−1). This highlights economic benefits of incorporating CO₂-assisted catalytic pyrolysis in waste EPS-to-MeOH process. To further enhance feasibility, Strategy B was modified by integrating syngas recycling and carbon capture and storage stages (Strategy C). This lowered the LCOP of MeOH to $463 metric ton⁻¹, comparable to those of bio-MeOH and e-MeOH. Strategy C exhibited highest eco-efficiency among three strategies, demonstrating that superior economics and lower environmental burdens. Moreover, Strategy C showed lower impacts than incineration and landfill in various categories, indicating that it is environmentally feasible alternative to conventional EPS disposal methods. © 2025

This work was supported by the Industrial Technology Innovation Program ( RS-2024-00507471 , Development and Demonstration of an Operations Optimization Platform for AI Driven Autonomous Manufacturing in Refinery and Petrochemical Processes) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).