Decomposition of polyamide via slow pyrolysis: Effect of heating rate and operating temperature on product yield and composition

摘要

Degradation of the polyamide (Nylon) was reported and analyzed via thermo-gravimetric analysis (TGA) for the determination of degradation temperature range and reported to be in between 420 - 520 degrees C. For batch pyrolysis experiments, 100 g sample was pyrolyzed in a temperature range between 475 - 650 degrees C with an initial increment of 25 degrees C up to 550 degrees C and later with an increment of 50 degrees C upto 650 degrees C to recover valuable pyrolysis products. Effect of process temperature and heating rate on the product yield and its composition was reported. TGA study was performed at 5, 10, 20, and 40 degrees C/min and stated that the nylon degrades in a single step whereas the increase in heating rate shifts the degradation temperature towards the higher side. At a lower heating rate, the recovered pyrolytic oil has a lower density and high volume compared to high heating rates, while at higher operating temperature and heating rate, the oil yield is higher. The products recovered in the range of 85-88 % oil, 12-14 % gas and a negligible amount of char. Online FTIR analysis was performed to identifying the functional groups present in the evolved vapour species while the condensable oil analysis was also reported. The gases obtained were also characterized at all optimum temperature for all heating rates. In addition, the kinetic parameters were analyzed via model-free methods (Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Kissinger, Starink, Vyzovkin and Friedman) and model-based approach (Coats-Redfern method (CRM)) and reported a high resemblance. Contracting sphere model was said to be followed during the degradation for all methods, and thermodynamic properties were also reported.