Understanding pyrolysis mechanisms of corn and cotton stalks via kinetics and thermodynamics

The kinetics and thermodynamics of biomass pyrolysis are crucial in its design, optimization and industrial application. The physicochemical characterization, kinetic and thermodynamic analyses of corn and cotton stalks pyrolysis are performed. Nonisothermal thermogravimetric analysis (TGA) with four heating rates (4, 8, 16 and 32 K min−1) is employed to experimentally investigate their pyrolysis kinetic behaviors. The effective activation energy values obtained by isoconversional kinetic analysis vary significantly with the reacted fraction and the average values are 206.2 and 207.4 kJ mol−1 for the pyrolysis of corn and cotton stalks, respectively. The changes in Gibbs free energy, enthalpy and entropy for them are evaluated and the results indicate that corn and cotton stalks pyrolysis is nonspontaneous processes and requires external energy to be thermally decomposed and that their endothermicity and reactivity increase as their pyrolysis processes proceed. The results can be helpful in better understanding the reaction mechanisms and extending the application of corn and cotton stalk pyrolysis.