Selective conversion of biodegradable polyester waste into BTX via HZSM-5-catalyzed hydropyrolysis: Life-cycle and techno-economic assessment

Biodegradable plastics are increasingly used but often fail to degrade efficiently, leaving their embedded carbon largely lost to landfill or incineration. Recovering this carbon as benzene, toluene, and xylenes (BTX) is attractive but challenging because aliphatic biodegradable polyesters are oxygen-rich and contain no aromatic rings. Here we establish a waste-to-BTX route based on HZSM-5 hydropyrolysis and evaluate its environmental and economic viability. Using poly (butylene adipate) (PBA) as a model, non-catalytic hydropyrolysis produced only non-aromatic oxygenates, mainly cyclopentanone, 1,3-butadiene, and tetrahydrofuran, whereas HZSM-5 converted this fragment pool into aromatics. At 600 °C, 0.3 MPa H 2 , and C/F = 4, the aromatic content increased from near zero to above 90%, corresponding to a total aromatics yield of 57.5%, with BTX accounting for 53.4%. Real biodegradable plastic wastes gave comparable BTX and naphthalene (BTXN) yields of 53.0-54.2%. A cradle-to-gate life-cycle assessment and techno-economic analysis, based on measured yields, benchmarked the process against fossil-based products. With grey hydrogen, the route reduced emissions by 46.1% and the minimum selling price (MSP) by 26.9% relative to fossil-based products, reaching 0.89 kg CO 2 -eq and 0.57 USD per kg BTX. Green hydrogen further reduced emissions to 0.77 kg CO 2 -eq per kg BTX but increased the MSP to 0.95 USD per kg. Process energy, feedstock cost, and hydrogen source are the key levers governing the carbon and cost performance of this biodegradable-plastic-to-BTX route.