Hydrolysis in PET Alcohol Salt Systems: Exploration of Novel Catalytic Pathways

The production and disposal of polyester fibers have been rapidly increasing, highlighting the urgent need for green and efficient recycling technologies to promote fiber resource circularity. Although the conventional alkaline hydrolysis method for polyester offers a simple process, its reliance on strong alkaline media and high-temperature conditions leads to severe equipment corrosion, high energy consumption, and significant secondary pollution risks, greatly limiting its large-scale application. In this study, an innovative ethanol-sodium carbonate (EtOH-Na₂CO₃) synergistic catalytic system was developed. By leveraging the cooperative effects of an organic–inorganic hybrid solvent, PET was efficiently depolymerized under mild conditions. The results indicate that when the alcohol-to-water ratio was optimized to 1:1 (v/v), the catalyst loading (Na₂CO₃/PET) was set at 2:3 (w/w). The reaction was conducted at 150 °C for 105 min; PET was completely converted, achieving a terephthalic acid (TPA) yield of up to 98%, five times higher than that of traditional non-alcoholic systems. Moreover, this method was also applicable to colored polyester fibers, producing TPA that met industrial-grade standards. These findings demonstrate the great potential of this approach for large-scale applications. This study not only elucidates the synergistic catalytic mechanism of the organic–inorganic hybrid solvent system but also establishes a technological bridge from fundamental research to industrial application. It provides an innovative strategy for the closed-loop management of chemical fibers. It offers a novel solution for the high-value recovery of complex fiber waste, thereby facilitating the deep integration of green chemical processes and circular economy models.

Graphical Abstract