Catalytic Co-Pyrolysis of Low Rank Coal and Sewage Sludge Blends : An Insight into Kinetic, Synergetic and Thermodynamic Parameters /

Abstract

Increasing sewage sludge (SS) production requires research and development to reduce economic and environmental difficulties connected with its current treatment. This study examined coal and sewage sludge (C-SS) blends through GCV, FTIR, and were co-pyrolyzed in thermogravimetric analyzer (TGA). TGA and DTG curves were used to investigate copyrolysis process. Coats-Redfern method is used to analyses kinetics using four models F1, F1.5, D1 and S1. Kinetic analysis of C-SS blends shows that in the first temperature range=(150-400 °C), C-SS blends activation energy (Ea) increases with increasing SS content. Models F1 and S1 for optimum blend (blend E) have the lowest Ea values at around 6.01 kJ/mol and 5.09 kJ/mol, respectively. In the second temperature range (400-600 °C), Ea drops as SS proportion of blends increases, blend E had Ea nearly 20.5 kJ/mol for model F1 and 17.7 kJ/mol for model S1 in this range. Catalytic co-pyrolysis of the optimal blend shows that an increase in catalyst concentration reduces weight loss. In the second decomposition range (400-600 °C), CP2 loses the most weight (15.1%). For model F1, the observed Ea for the best blend was 20.5 kJ/mol, but it drops to 13.6 kJ/mol for CP2. In third decomposition range (650-750 °C), char development is sustained with a slight decline. model F1 shows that Ea goes down from 32.4 kJ/mol for optimal blend to 17.2 kJ/mol for CP2. Catalysts promote stability and char production. Entropy values of catalytic co-pyrolysis imply that catalyst addition helps to create compounds with well-defined molecular structure.