Optimization and Kinetic Evaluation for Glycolytic Depolymerization of Post-Consumer PET Waste with Sodium Methoxide

Area of Science:

• Chemical Engineering
• Polymer Chemistry
• Sustainable Materials

Background:

• Post-consumer polyethylene terephthalate (PET) waste poses a significant environmental challenge.
• Chemical recycling via glycolysis offers a route to recover valuable monomers.
• Developing efficient and cost-effective catalysts is crucial for sustainable PET recycling.

Purpose of the Study:

• To investigate sodium methoxide (MeONa) as a low-cost catalyst for PET glycolysis.
• To optimize reaction conditions using response surface methodology (RSM).
• To evaluate the catalytic performance of MeONa compared to traditional catalysts.

Main Methods:

• Glycolysis of PET using MeONa catalyst.
• Product characterization using GCMS, NMR, melting point, and DSC.
• Optimization of reaction parameters (temperature, molar ratios, time, particle size) via RSM and Box-Behnken design.
• Kinetic and thermodynamic analysis (van 't Hoff and Arrhenius plots).

Main Results:

• MeONa effectively catalyzes PET glycolysis to bis(2-hydroxyethyl) terephthalate (BHET).
• RSM optimization predicted 87% PET conversion under optimal conditions with <5% deviation.
• The reaction is endothermic with a ceiling temperature of 160 °C and activation energy of 130 kJ/mol.
• MeONa demonstrated comparable or superior performance to zinc and cobalt acetates, at lower cost and with improved environmental profile.

Conclusions:

• Sodium methoxide is a highly effective, low-cost, and environmentally friendly catalyst for PET glycolysis.
• The developed RSM model accurately predicts and optimizes PET conversion.
• MeONa presents a viable and sustainable alternative for the chemical recycling of PET waste, supporting circular economy principles.