Page 7 - 《橡塑技术与装备》英文版2025年12月

SPECIAL AND COMPREHENSIVE REVIEW

Exploration of the process of depolymerizing waste

PET bottlesusing ethylene glycol

Yu Yang, Shen Guoliang, Xu Tiejun*, Wen Ruiyang
(School of Petrochemical Engineering, Shenyang University of Technology, Liaoyang 111003, Liaoning, China)

Abstract: PET (polyethylene terephthalate), as a thermoplastic with excellent performance, is widely
used. However, due to its difficulty in decomposing in the environment, it poses a certain burden on the
environment, and the recycling and reuse of PET have received more attention. This experiment studied a
new type of green, environmentally friendly, and non-toxic silanol catalyst for the depolymerization of waste
PET bottles using ethylene glycol to produce BHET [bis(2-hydroxyethyl) terephthalate]. The effects of reaction
temperature, reaction time, and catalyst dosage on the yield of depolymerization product BHET were
emphatically investigated. The results showed that at 200 ℃ , with a reaction time of 3 hours and a mass ratio
of ethylene glycol:PET:catalyst is 4:1:0.04, the yield of reaction product BHET could reach 84%.
Key words: waste PET; ethylene glycol; depolymerization; catalyst
Classification number: TQ323.41 Article number: 1009-797X (2025) 12-0001-04
Document code: B DOI: 10.13520/j.cnki.rpte.2025.12.001

0 Introduction a kind of new environmentally friendly and non-toxic
Poly (ethylene terephthalate) (PET) is a thermoplastic catalyst and non-toxic ethylene glycol were studied for
polyester material with good performance. It has good depolymerization of waste PET bottles.
transparency, gas barrier performance, mechanical
properties and solvent resistance, and is non-toxic and 1 Reagents and instruments
tasteless. It is widely used as fiber, engineering plastics, 1.1 Reagents used in the experiment
beverage bottles, etc. [1~8] .The chemical inertness of PET Silicates (Tianjin Damao Analytical Pure);Organic
makes it difficult to decompose in nature, so its widespread solvent (analytical grade from Shenyang Xinxing Reagent
use imposes a significant burden on the environment. Factory);Ethylene glycol (analytical grade from Shenyang
Countries around the world attach great importance to the Xinxing Reagent Factory);PET (discarded plastic
recycling and reuse of PET. bottles);Distilled water.
The recycling methods of PET mainly include 1.2 Instruments used in the experiment
physical recycling and chemical recycling.At present, Four necked flask;H2T-A+200 electronic balance
physical recycling methods cannot effectively remove (HZ Electronic Technology Co., Ltd. USA);Electric
impurities, control side reactions, and the quality of heating sleeve (DRT-TW Zhengzhou Changcheng Science
regenerated products is low. Chemical recycling mainly and Trade Co., Ltd.);Drying oven (Dalian Experimental
includes pyrolysis, methanolysis, hydrolysis, ammonolysis, Equipment Factory);Blender;Nicolet 5700 Infrared
ethylene glycol hydrolysis, etc. [9-15] .Due to limitations in Spectrometer (USA).
reaction time and the use of catalysts or solvents, there
may be potential pollution to the environment or human Biography: Yu Yang (1997-), master's degree holder, mainly
engaged in research on resource recycling and green chemistry
health.Therefore, large-scale application is difficult, so
processes.
Vol.51，2025 ·1·