Study on thermochemical characteristics properties and pyrolysis kinetics of the mixtures of waste corn stalk and pyrolusite

As an alternative energy source for fossil energy, use of biomass pyrolysis to reduce pyrolusite is of great significance for energy conservation, emission reduction and environmental protection. Kinetics and thermodynamics of reducing pyrolusite using biomass pyrolysis was studied using thermogravimetric analysis analysis. Five non-isothermal methods, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Distributed Activation Energy Model, Starink and Friedman, were employed to calculate the pyrolysis kinetics and thermodynamic parameters. The results showed that pyrolusite reduction by biomass pyrolysis can be divided into four stages: drying stage (30–175 °C), rapid pyrolysis reduction stage (175–350 °C), slow pyrolysis reduction stage (350–680 °C) and char formation stage (680–900 °C). The apparent activation energy, reaction enthalpy, Gibbs free energy and entropy change of pyrolusite reduction by biomass pyrolysis was calculated ranges from 170 to 180 kJ/mol, 164 to 174 kJ/mol, 136.97 to 137.25 kJ/mol and 45.67 to 61.91 J/mol·K, respectively. This work provides theoretical basis and practical guidance for the reduction of pyrolusite by waste corn stalk.