Co-pyrolysis kinetics of sewage sludge and oil shale thermal decomposition using TGA–FTIR analysis

Abstract TGA–FTIR system was equipped under N2 for the kinetics behavior characteristics of sewage sludge (SS) and oil shale (OS) blends during co-pyrolysis. The SS was blended with OS in the range of 10–90 wt.%, and then heated from 105 °C to 1000 °C at 10, 20 and 30 °C/min under N2 atmosphere with a flow rate of 80 ml/min. Two model-free methods, Kissinger–Akhira–Sunose (KAS) method and Starink method, were used to study their co-pyrolysis kinetics. There existed promoting effects on the degradation of oil shale during co-pyrolysis. The absorption of hydrocarbon became stronger with adding 10% SS. The best proportion of SS was selected as 10% due to better pyrolysis performance of OS and lower apparent activation energy (253.6 kJ/mol obtained by Starink, 253.3 kJ/mol obtained by KAS). The results afford a theoretical groundwork for the co-pyrolysis technology of SS and OS and the development of their thermochemical conversion systems.