Synergistic effects in the Co-pyrolysis of waste tires, plastics, and corn stalks: Kinetic and thermodynamic analyses for enhanced resource utilization

Abstract

In this study, the co-pyrolysis of corn stalks (Cs) with various polymer waste materials, including waste tires (WTs), waste plastics (WPs), and their blends (WTs/WPs), is investigated. Thermogravimetric analysis (TGA), kinetic models (FWO, Starink, DAEM), and pyrolysis tube furnace equipment are utilized for a comprehensive evaluation and analysis of pyrolysis and co-pyrolysis. The results indicate that the addition of Cs during pyrolysis significantly reduces the pyrolysis temperature of WTs, WPs, and their blends by 35.1–245.7 °C. Kinetic analysis reveals that the actual activation energy of WTs/WPs (235.5 kJ/mol) is lower than the theoretical prediction (239.2 kJ/mol). Theoretical thermogravimetric and derivative thermogravimetric (TG-DTG) curves show distinct peaks indicative of positive synergism, confirming the beneficial interaction between WTs and WPs. However, other mixed samples (WTs/Cs, WPs/Cs and WTs/WPs/Cs) display varying degrees of negative synergism due to the presence of oxygen-containing functional groups (C-O-C and O-H). Pyrolysis experiments in a tube furnace demonstrate that the positive synergistic effect enhances the pyrolysis oil yield, with the actual oil yield of WTs/WPs (60.15 wt%) exceeding the expected theoretical value (58.03 wt%). In contrast, the negative synergistic effect observed in WPs/Cs and WTs/WPs/Cs is more conducive to gas production. The findings of this study provide theoretical and parametric support for the co-pyrolysis of solid waste products, aiming to reduce energy consumption, enhance oil production rates, and address limitations.