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

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.