Exploring Mg-Al Bimetallic Oxide Catalysts for Efficient Terephthalic Acid Recovery From Polyethylene Terephthalate

Abstract

The escalating demand for plastics has necessitated advancements in plastic recycling technologies. This study examines the development of heterogeneous metal catalysts aimed at improving the hydrolysis performance of polyethylene terephthalate (PET), a commonly used plastic, and enhancing the conversion efficiency for the efficient production of terephthalic acid (TPA). A series of Mg-Al bimetallic oxide with varying Mg and Al ratios were synthesized and employed as catalysts for the hydrolysis of PET under various conditions, including reaction temperature (80°C–220°C), reaction time (10–300 min), and solvent ratio. Optimization of the process revealed that the optimal conditions for catalytic hydrolysis were achieved at 200°C, 300 min, using a Mg-Al-1 catalyst and a solvent ratio of 5:5 ethanol to water, resulting in a PET conversion efficiency of 95.6% and a TPA yield of 80.3%. Over 70% TPA yield could be generated after first hydrolysis without regeneration. Under hydrothermal conditions, polyethylene glycol instead of ethylene glycol was found after reaction, as identified by liquid chromatography–mass spectrometry (LC–MS). This study offers a sustainable and feasible pathway for TPA recovery from PET, contributing to the advancement of recycling technologies.