Optimisation of PET glycolysis by applying recyclable heterogeneous organocatalysts

Fehér, Zsuzsanna; Kiss, Johanna; Kisszékelyi, Péter; Molnár, János; Huszthy, Péter; Kárpáti, Levente; Kupai, József

doi:10.1039/d2gc02860c

Cited by 33 publications

(24 citation statements)

References 52 publications

(78 reference statements)

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“…The glycolysis of post-consumer PET waste is carried out in the presence of a transesterification catalyst. In the literature, various catalysts have been reported that include metal acetates (cobalt, lead, zinc, and manganese), [18][19][20] less efficient sodium carbonate and sodium bicarbonate, 21 titanium phosphate, 22 deep eutectic solvents, 23 organic catalysts, 24 heterogeneous catalysts, [25][26][27][28] and ionic liquids of zinc and copper acetate. 29 The most active glycolysis catalyst is zinc acetate, but as a heavy metal, zinc is toxic to the environment.…”

Section: Introductionmentioning

confidence: 99%

Sodium ethoxide as an environmentally benign and cost-effective catalyst for chemical depolymerization of post-consumer PET waste

2023

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Section: Introductionmentioning

confidence: 99%

Sodium ethoxide as an environmentally benign and cost-effective catalyst for chemical depolymerization of post-consumer PET waste

2023

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“…Alternative catalysts include nanoparticles, ionic liquids, light metal salts, zeolites, organocatalysts, and deep-eutectic solvents. [13][14][15][24][25][26] Most recently, the use of protic ionic salts as catalysts in the depolymerization of PET has removed the metal component of the catalyst, resulting in products that are more benign. 20,27 Blending polymers together provides an additional pathway to use polymers at their end of life.…”

Section: Introductionmentioning

confidence: 99%

The structural evolution of poly(ethylene terephthalate) oligomers produced via glycolysis depolymerization

Moncada

Dadmun

2023

J. Mater. Chem. A

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“…Besides homogeneous metal salt-based catalysts, now heterogeneous catalysts are also widely used for PET glycolysis. Fehér et al demonstrated that organocatalyst-modified silica gels are efficient for PET glycolysis achieving a non-isolated BHET yield of 88.5% under optimum conditions (190 °C, 1.7 h,) by handling only 384 mg of PET substrate in a reaction vial [ 15 ]. Recently Kim et al reported the glycolysis of PET waste into BHET using oyster shell-derived catalysts with a BHET yield of 68.6% at 195 °C [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

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

2023

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Glycolysis of post-consumer polyethylene terephthalate (PET) waste is a promising chemical recycling technique, back to the monomer, bis(2-hydroxyethyl) terephthalate (BHET). This work presents sodium methoxide (MeONa) as a low-cost catalyst for this purpose. BHET product was confirmed by gas chromatography-mass spectrometry (GCMS), Nuclear Magnetic Resonance (NMR) Spectroscopy, melting point, and Differential Scanning Calorimetry (DSC). It was shown, not surprisingly, that PET conversion increases with the glycolysis temperature. At a fixed temperature of 190 °C, the response surface methodology (RSM) based on the Box-Behnken design was applied. Four independent factors, namely the molar ratio of PET: MeONa (50–150), the molar ratio of ethylene glycol to PET (EG: PET) (3–7), the reaction time (2–6 h), and the particle size (0.25–1 mm) were studied. Based on the experimental results, regression models as a function of significant process factors were obtained and evaluated by analysis of variance (ANOVA), to predict the depolymerization performance of MeONa in terms of PET conversion. Coefficient of determination, R2 of 95% indicated the adequacy for predicted model. Afterward, the regression model was validated and optimized within the design space with a prediction of 87% PET conversion at the optimum conditions demonstrating a deviation of less than 5% from predicted response. A van ‘t Hoff plot confirmed the endothermic nature of the depolymerization reaction. The ceiling temperature (TC = 160 °C) was calculated from Gibbs’ free energy. A kinetic study for the depolymerization reaction was performed and the activation energy for MeONa was estimated from the Arrhenius plot (EA = 130 kJ/mol). The catalytic depolymerization efficiency of MeONa was compared under similar conditions with widely studied zinc acetate and cobalt acetate. This study shows that MeONa’s performance, as a glycolysis catalyst is promising; in addition, it is much cheaper and environmentally more benign than heavy metal salts. These findings make a valuable contribution towards the chemical recycling of post-consumer PET waste to meet future recycling demands of a circular economy.

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Optimisation of PET glycolysis by applying recyclable heterogeneous organocatalysts

Abstract: Chemical depolymerisation, or solvolysis, can be a sustainable plastic recycling method, as a circular economy can be achieved by recovering the pure monomers. Polyethylene terephthalate (PET) is a ubiquitous plastic...

Cited by 33 publications

References 52 publications

Sodium ethoxide as an environmentally benign and cost-effective catalyst for chemical depolymerization of post-consumer PET waste

Sodium ethoxide as an environmentally benign and cost-effective catalyst for chemical depolymerization of post-consumer PET waste

The structural evolution of poly(ethylene terephthalate) oligomers produced via glycolysis depolymerization

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

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