A new strategy for PET depolymerization: Application of bimetallic MOF-74 as a selective catalyst

Area of Science:

• Materials Science
• Catalysis
• Polymer Chemistry

Background:

• Poly(ethylene terephthalate) (PET) waste poses significant environmental challenges.
• Current chemical recycling methods often use homogeneous catalysts that are difficult to separate and reuse.

Purpose of the Study:

• To investigate the efficacy of bimetallic MOF-74 as a heterogeneous catalyst for PET depolymerization.
• To explore the impact of different second metals within the MOF-74 structure on catalytic activity and monomer recovery.

Main Methods:

• Synthesis and characterization of bimetallic MOF-74 catalysts (Mg/M).
• Systematic investigation of various metal combinations (Co, Zn, Mn, Cu, Ni) and their ratios.
• Evaluation of catalytic activity, monomer yield, and catalyst stability through depolymerization experiments and HPLC analysis.

Main Results:

• MOF-74 (Mg/M) catalysts containing Co²⁺, Zn²⁺, and Mn²⁺ showed enhanced activity.
• The optimal catalyst, Mg-Mn MOF-74 (1:1 molar ratio), achieved complete PET depolymerization and 91.8% BHET yield in 4 hours.
• The catalyst demonstrated good stability over 5 reaction cycles and produced high-purity BHET.

Conclusions:

• Bimetallic MOF-74 is a highly effective heterogeneous catalyst for PET chemical recycling.
• The Mg-Mn MOF-74 (1:1) catalyst offers a sustainable solution for efficient BHET monomer recovery with recyclability.
• This approach facilitates easier separation and reuse compared to traditional homogeneous catalysts.