A comprehensive understanding on industrial waste oil pyrolysis upgrading process: Physicochemical properties, pyrolytic behavior, kinetics, and thermodynamics

A growing interest has turned to in research to convert waste oil into sustainable energy. Under such circumstances, it was fundamental to investigate the physicochemical properties, pyrolytic characteristics, kinetics and thermodynamics for industrial waste oil (IWO) non-isothermal pyrolysis via multiple analyses. Results indicated that the high density (0.87 g/cm³) and viscosity (17.64 Pa·s@30 °C) for IWO were mainly attributed to the obvious heavy fraction proportion (∼20 %) and component deterioration. It mainly underwent the cracking stage with major mass loss (70 wt%), while the residue was attributed to the coking process. Besides, an obvious influence was presented for heating rate on pyrolytic behaviors, involving threshold, peak, and termination temperatures, maximum mass loss rate, and heat flow variation. Moreover, differential and integral model-free methods were comparatively applied to determine kinetic parameter variation with conversion, and the calculated pyrolytic activation energies were respectively 146.08–322.70 kJ/mol and 102.15–284.20 kJ/mol. For specific conversions, the pre-exponential factor obviously compensated for the activated energy, and Pearson correlation analysis further supported to these findings. Furthermore, the change in thermodynamic parameters with conversion and heating rate revealed endothermic and non-spontaneous for IWO pyrolysis. Via this research, it would enrich the understandings on the thermal decomposition and utilization of waste oil into sustainable energy.