Hydrolysis of PET by Combining Direct Microwave Heating with High Pressure

The direct hydrolysis of waste poly(ethylene terephthalate) (PET) was carried out in a high pressure reactor under microwave heating condition. Microwave irradiation enhanced the diffusion of water into the PET matrix by the effect of the structure relaxation and therefore resultantly the degradation rate of PET became high compared with the state of the conventional heating. The complete degradation of PET by direct hydrolysis was achieved for 30 min at high reaction temperature (223-232oC) and high pressure (2.3-3.0 MPa) under the microwave heating condition. Although the use of HCl catalyst in the acid hydrolysis of PET decreased the yield of terephthalic acid (TPA) at the low HCl concentration region, the complete degradation of PET could be achieved for 15 min at the HCl concentration of 1.0 wt%.