Catalytic Hydrothermal Depolymerization and Kinetics of Nylon6

Depolymerization of nylon6 to e-caprolactam was carrid out with environmental-friendly heteropolyacid catalyst at temperatures between 553K and 603K,under different pressures of 6.4 MPa～12.8 MPa in water medium. The products of depolymerization were analysed qualitatively and quantitatively by means of infrared spectroscopy(FT-IR),thermo gravimetric(TG),liquid chromatography-mass spectrometry(LC/MS)and high performance liquid chromatography(HPLC). The results indicate that the main depolymerized product is e-caprolactam. Remnants solid product is undepolymerized nylon6 and the liquid products containe a little 6-aminocaproic acid and oligomer. The highest yield of e-caprolactam is 77.96% at 583K under 85min.Compared with no catalyst,the depolymerization rate and yield of e-caprolactam is high under catalytic condition. Temperature and time also have important effect on depolymerization reaction. Catalytic depolymerization kinetic at different reaction conditions was studied,where the reaction activation energy was evaluated to be 77.38 kJ/mol.