Process-Level Decarbonization Pathways of Purified Terephthalic Acid (PTA) Production: A Life Cycle Assessment Approach

Purified terephthalic acid (PTA) is an extremely important bulk organic raw material; it plays a central connecting role in the PX–PTA–polyester industry chain, while its significant carbon intensity remains poorly quantified. Through process-level life cycle assessment (LCA) based on in situ industrial data, this study establishes a comprehensive material-energy inventory for PTA production. The results show that the total greenhouse gas (GHG) emissions of the entire PTA process reached 1600.9 kg of CO 2 eq·t −1 , exceeding those of common primary chemicals, like aromatics, butadiene and styrene. The end process of the PTA unit (PU) dominates GHG emissions, reaching 365.6 kg CO 2 eq·t −1 , accounting for 22.3%, driven by extra xylene input, various catalyst consumption, auxiliary chemicals, and energy intensity. After allocating steam-related emissions from coal-fired power stations, the GHG emissions of the PU rise to 400.9 kg CO 2 eq·t −1 . Sensitivity analysis demonstrates that replacing conventional hydrogen with green hydrogen slashes hydrogen-related global warming potential (GWP) contribution by 61.5%. In addition, a 10% increase in electricity, coal, or steam elevates system GWP by 0.80%, 0.036% and 2.48%, respectively. The findings demonstrate that energy structure optimization and green hydrogen integration represent decisive levers for PTA decarbonization, providing data-driven insights for industrial transition under a carbon reduction policy framework.