Microwave-Assisted Catalytic Glycolysis of Poly(ethylene terephthalate) By Using Ionic Liquids

Poly(ethylene terephthalate) (PET)  was widely used for beverage bottles, electrical/electronic instruments and household wares. As a consequence of dramatically increasing consumption, recycling of post-consumer PET products has become an important environmental opportunity for sustainable usage in society. The presented study is aiming to investigate the use of ionic liquids as catalysts for the glycolysis of PET. A series of novel ionic liquids using 1-butyl-3-methylimidazolium chloride (BMIMCl) and zinc halides (ZH) as precursor with different molar ratios was first synthesized. The glycolysis of PET by microwave-assisted method using the synthesized ionic liquids as catalysts and glycol as solvent was also studied. The influences of the type of zinc halide, the molar ratio of BMIMCl:ZH, the dosage of ionic liquid and solvent, reaction time and reaction time on the yield of recovered terephthalic acid were investigated. The synthesized ionic liquids and the glycolysis product were characterized by X-ray diffractometer, infrared spectrometric analyzer, ¹H NMR, differential scanning calorimeter and DSC. The results showed that the synthesized ionic liquids exhibited higher catalytic activity for the glycolysis of PET by microwave-assisted method．The halogen anion has a key influence on the glycolysis of PET. A study on the recycling of the ionic liquid shows that it could be used repeatedly. A mechanism of the degradation of PET was proposed and the kinetics of the reaction was needed further investigated.