Determination of the Bioenergy Potential of Brazilian Pine-Fruit Shell via Pyrolysis Kinetics, Thermodynamic Study, and Evolved Gas Analysis

Abstract

This work provides the first study about the evaluation of the bioenergy potential of lignocellulosic waste from Brazilian pine-fruit shell (Araucaria angustifolia). Physicochemical characterization, evolved gas from pyrolysis, and kinetic and thermodynamic studies were performed. A thermogravimetric analyzer was used for the pyrolysis experiments, where the runs were performed under an inert atmosphere of nitrogen at temperatures ranging from room temperature to 850 °C at different low heating rates (5, 10, 20, and 30 °C min−1). The physicochemical characterization of Brazilian pine-fruit shell showed good applicability for the gasification process due to the high fixed carbon content. Similarly, the pyrolysis experiments and FTIR-evolved gas analysis indicate its great potential for use as a solid biofuel. The kinetic study showed that the Kissinger–Akahira–Sunose method (e = 0.07–0.11%) had a smaller relative error, when compared with the methods of Friedman (e = 5.12–28.89%), Flynn–Wall–Ozawa (e = 0.26–1.21%), and Starink (e = 0.17%), and it was comparable to the Vyazovkin method (e = 0.08–0.09%). Furthermore, the conversion rate curves obtained from kinetic parameters showed a satisfactory behavior, with a high regression coefficient (R2 ≥ 0.9165), thus demonstrating the great applicability of the parameters for the design and optimization of the thermochemical system. The endothermic and nonspontaneous process was observed, based on the positive ΔH, positive ΔG, and positive ΔS values of Brazilian pine-fruit shell. The pyrolysis of Brazilian pine-fruit shell has been identified as a viable alternative for bioenergy generation, acting as a solution for the final disposal of this agricultural waste biomass.