Kinetic analysis for hydrothermal depolymerization of nylon 6

We investigated the influences of reaction temperature, time and water density. We also investigated the reaction rate and reaction scheme which is necessary to industrialize this process from the result of hydrolysis of nylon 6 in sub- and supercritical water. The reactions were carried out at temperatures between 573 and 673 K under the estimated pressures of up to 35 MPa (water amount charged in a reactor 0.83-3.79 g/5 cm³ - reactor) for reaction times of 5-60 min. The main products of hydrolysis of nylon 6 by sub- and supercritical water are ?-caprolactam and ?-aminocaproic acid. Based on our experimental results, the reaction scheme of nylon 6 decomposition is represented. Nylon 6 was decomposed into ?-aminocaproic acid by hydrolysis followed by cyclodehydration to ?-caprolactam or decomposition further to lower molecules. At each reaction conditions, the k₁ and k₂ values were determined and the activation energy was calculated.