Thermo-Kinetic and Synergistic Evaluation of Catalytic Co-Pyrolysis of Coal-Sewage Sludge Using Thermogravimetric Analysis (TGA)/Derivative Thermogravimetry (DTG) Analysis

This study investigates the utilization of sewage sludge (SS) and low-rank coal (C) for the purpose of energy recovery by co-pyrolysis. Pyrolysis process is performed through thermogravimetric analysis and derivative thermogravimetry. The thermo-kinetic parameters are determined by applying the Coats-Redfern technique's using F1, F1.5, D1, and S1 reaction mechanistic models. The analysis determines that (Sample E), consisting of 80% coal and 20% SS, is the most effective. It demonstrates a low activation energy (Ea) of around 20.5 kJ/mol and 17.7 kJ/mol for models F1 and S1, respectively. These low Ea values are due to the high volatile content and inherent inorganic minerals in SS, which make the decomposition reactions easier. As the concentration of SS in the mixes increases, the Ea decreases. Furthermore, the mean reactivity (Rm.r) and pyrolysis factor (Pf) were analyzed to further assess the thermal behavior of the fuel blends. The addition of 2% Sr2TiFeO6 catalyst loading to optimum blend, i.e. CP2 leads to a maximum weight loss of 19.2% in the primary pyrolysis zone, while Ea decrease from 20.5 kJ/mol to 13.6 kJ/mol for Model F1. The study's findings highlight the promising potential of catalytic co-pyrolysis of coal-sludge for improved energy recovery.