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Two-Dimensional Hybrid Framework Based on Weakley-Type POM as a Heterogeneous Catalyst for Glycolysis of PET and
Jie Fu1, Haiyan An1, Yaying Zhang1
1College of Chemistry, Dalian University of Technology, Dalian116023, P. R. China.
None:
The widespread application of polyester plastics has led to significant environmental challenges. To address these challenges, it is imperative to develop heterogeneous catalysts for the chemical recycling of polyester plastics into high-value monomers. In this study, we synthesized one 2D hybrid constructed from a Weakley-type POM: H10[Zn(bdyl)(H2O)]{[Zn(bdyl)2][Zn(bpy)2]2[Zn(H2O)(bpy)2]2[Zn4(H2O)2(PW9O34)2]}{[Zn(bpy)]2[Zn4(H2O)2(PW9O34)2]}·11H2O (1, bpy = 2,2'-bipyridine; bdyl = 2,2'-bipyridinyl), which can heterogeneously catalyze the recycling of polyethylene terephthalate (PET) and other polyester plastics, involving polybutylene terephthalate, bisphenol A polycarbonate, and polyethylene naphthalate. Structural analysis reveals that compound 1 contains two kinds of Weakley-type POM subunits, {[Zn(bpy)]2[Zn4(H2O)2(PW9O34)2]}6- and {[Zn(bdyl)2][Zn(bpy)2]2[Zn(H2O)(bpy)2]2[Zn4(H2O)2(PW9O34)2]}4-, which are connected together by binuclear {Zn2(bdyl)}2+ clusters to form a 2D layer. Remarkably, the rollover cyclometalation of 2,2'-bpy is first observed in the Zn-based complex. Compound 1 achieved complete conversion of PET within 20 min at 190 °C in an ethylene glycol (EG) solvent, affording bis(2-hydroxyethyl) terephthalate with a yield of 96.9%, together with structural stability and excellent recyclability. The catalytic mechanism demonstrates that Weakley-type POMs and Zn-organic complexes can activate PET and EG to rapidly convert PET to the monomer. Furthermore, compound 1 exhibited excellent catalytic performance in the glycolysis of real-world PET waste materials. This work provides one practical solution route to the management of polyester wastes.
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