Pyrolysis and co-pyrolysis of cattle manure, rape straw, and their blend: Physicochemical characterization, kinetic triplets, reaction mechanism, and thermodynamic analysis

Abstract

Cattle manure (CM) and rape straw (RS) are typical agricultural wastes. In present study, pyrolysis and co-pyrolysis of CM, RS, and their blend (MM) were studied by thermogravimetric experiments at different heating rates (10, 20, and 30 °C/min). The kinetic analysis was carried out using three iso-conversional methods, Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO). The average apparent activation energies (Eα) values calculated by FR, KAS, and FWO methods were 181.82 kJ/mol, 176.09 kJ/mol, and 196.50 kJ/mol for CM, 221.55 kJ/mol, 204.91 kJ/mol, and 215.08 kJ/mol for RS, and 314.35 kJ/mol, 294.08 kJ/mol, and 304.33 kJ/mol for MM. The overall pyrolysis processes of CM, RS, and MM followed the diffusional and order of reaction models by the master-plots method. Thermodynamic parameters indicated the non-spontaneous and endothermic characteristics of the CM, RS, and MM pyrolysis. The kinetic and thermodynamic analysis will provide critical information for the safe and efficient design of pyrolysis reactors with CM, RS, and MM as feedstocks.