Insight into waste polyurethane pyrolysis pathways: Mechanism functions analysis and in-situ coupling online monitoring

Abstract

Pyrolysis is one of the promising techniques to recycle organic resources and remove hazardous substances during the treatment of waste polyurethane (WPU) in refrigerator. However, knowledges on pyrolysis mechanism and pathways from WPU to complex products are insufficient, limiting its application for producing high-valued oil and gas. Here, this study applied the mechanism functions analysis and in-situ coupling online monitoring for the insightful illustration of WPU pyrolysis process. The results suggested that the pyrolysis mechanism function calculated by Šesták-Berggren method was expressed as: , indicating that the WPU pyrolysis was controlled by the combined processes of diffusion, nucleation and phase boundary reactions. Moreover, the online TG-FTIR-MS and in-situ FTIR analysis for pyrolysis intermediates detection demonstrated that WPU pyrolysis began with the rupture of urethane bonds in WPU to produce isocyanates and polyols. Then, the polyols decomposed into the small molecular polyols, ethers, alkanes and alkenes, where the further decomposition of isocyanates led to the formation of aniline and its derivatives. The results offered the theoretical basis for converting waste to fuels and high-valued products through pyrolysis techniques.