One-Step Synthesized Solid Acid Catalyst with High Zr Content for Efficient and Green PET Degradation in Supercritical CO2

Solid acid will be an ecofriendly and efficient catalyst for the hydrolysis of polyethylene terephthalate (PET). Very highly Zr-doped MFI-structured zeolites as catalysts for PET hydrolysis were successfully synthesized for the first time. Comprehensive characterizations confirmed the successful incorporation of Zr into the framework. To comprehend the role of Zr within the framework, density functional calculations were employed to investigate its impact on the surface properties and hydrolysis processes. The results demonstrated that Zr d-orbitals enhance Lewis acidity of the catalyst by contributing to the formation of zeolite's lowest unoccupied molecular orbitals. The interaction between the model molecule and the catalyst surface was enhanced by doping Zr, leading to electron redistribution toward the surface direction on the carbonyl oxygen of model molecule. Consequently, the carbonyl carbon developed a partial positive charge, and the hydrolysis reaction was promoted. The experimental results validated that the Zr-doped catalyst exhibited a 64% enhancement in the reaction rate.