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Prospecting pecan nutshell pyrolysis as a source of bioenergy and bio-based chemicals using multicomponent kinetic modeling, thermodynamic parameters estimation, and Py-GC/MS analysis

2021; Elsevier BV; Volume: 153; Linguagem: Inglês

10.1016/j.rser.2021.111753

1879-0690

Guilherme Davi Mumbach, José Luiz Francisco Alves, Jean Constantino Gomes da Silva, Michele Di Domenico, Santiago Arias, José Geraldo A. Pacheco, Cintia Marangoni, Ricardo Antônio Francisco Machado, Ariovaldo Bolzan,

Lignin and Wood Chemistry

This work reports the first detailed investigation of the physicochemical properties of the pecan nutshell waste (PNS) and its suitability for pyrolytic conversion into bioenergy and bio-based chemicals based on the kinetic triplet, thermodynamic parameters, and Py-GC/MS analysis. The pyrolysis behavior of PNS was assessed using a thermogravimetric analyzer at five heating rate programs under an oxygen-free atmosphere. The Asym2Sig deconvolution function showed that pyrolysis of PNS might be successfully modeled as three parallel devolatilization events (R 2 > 99%), which are categorized as the devolatilization of hemicellulose (DE-HC), devolatilization of cellulose (DE-CL), and devolatilization of lignin (DE-LG). The activation energy was obtained for each devolatilization event by concurrent use of four isoconversional methods (Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink), with average values in the range of 100.3–109.0 kJ mol −1 for DE-HC, 124.3–135.3 kJ mol −1 for DE-CL, and 357.1–398.9 kJ mol −1 for DE-LG. Calculations using the compensation effect method indicated pre-exponential factor values of 5.50 × 10 8 min −1 for DE-HC, 1.32 × 10 9 min −1 for DE-CL, and 4.86 × 10 18 min −1 for DE-LG. It is inferred that the DE-CL corresponds to a geometrical contraction reaction model while the DE-HC and DE-LG follow order-based reaction models. Finally, the summative kinetic interpretation was successfully obtained based on multiple kinetic triplets, providing a useful mathematical tool able to describe the pyrolysis behavior of PNS. From the thermodynamic viewpoint, PNS has significant potential for application as raw material for bioenergy production. Also, the condensable fraction of the volatile products derived from pecan nutshell pyrolysis is a potential source of valuable bio-based chemicals. • First detailed investigation on pecan nutshell (PNS) bioenergy from pyrolysis. • Pyrolytic behavior of PNS proceeds via three parallel independent reactions. • Characterization of pyrolysis volatile products using Py-GC/MS analysis. • A summative kinetic expression reproduces the PNS pyrolysis concerning temperature. • PNS is an attractive feedstock for bioenergy and bio-based chemicals.