Kinetic modelling and mechanism elucidation of catalyst-free dimethyl terephthalate hydrolysis process intensification by reactive distillation

• Published in: Journal of cleaner production Vol. 477; p. 143867
• Main Authors: Lavrič, Žan, Kojčinović, Aleksa, Yarulina, Irina, Stepanski, Manfred, Likozar, Blaž, Grilc, Miha
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.10.2024
• Subjects: Hydrolysis; Kinetic modelling; PET recycling; Process optimization; Reactive distillation; Hydrolysis; Reactive distillation; Process optimization; PET recycling; Kinetic modelling
• ISSN: 0959-6526
• DOI: 10.1016/j.jclepro.2024.143867

Polyethylene terephthalate (PET) is a widely used thermoplastic polymer in the packaging and materials industries, and is predicted to have continuous market growth in the future. Methods such as glycolysis and methanolysis of PET have been identified as promising approaches in sustainable chemical recycling of PET. The latter produces dimethyl terephthalate (DMT), which can be easily hydrolyzed to terephthalic acid (TPA) at elevated temperatures and pressures, and further reused for PET production. The aim of this study was to develop a kinetic model for the hydrolysis of dimethyl terephthalate, using the experimental data. Various reaction conditions (temperature, pressure, time) have been investigated and used to calculate the activation energies and reaction rate constants, while the variation in reactor setup with methanol (MeOH) removal was conducted to show its detrimental effect on the efficiency of the reaction and selectivity towards terephthalic acid. The first reaction step of DMT to monomethyl terephthalate (MMT) is relatively irreversible, while the second reaction step of MMT to TPA ceases, as soon as the equilibrium is reached. Highest yields of TPA (76.7 %) were obtained after 40 min at 265 °C, with MeOH removal, and the activation energy was calculated to be 95 and 64 kJ mol−1 for the first and second hydrolysis reaction step, respectively. [Display omitted] •Kinetics of dimethyl terephthalate (DMT) hydrolysis during reactive distillation.•Reversible reaction between monomethyl terephthalate (MMT) and terephthalic acid (TPA).•The removal of methanol (MeOH) from the reaction mixture improves the final TPA yield.•Carbon balance loss is attributed to unavoidable sublimation of TPA during reactive distillation.