Potential of macauba endocarp (Acrocomia aculeate) for bioenergy production: Multi-component kinetic study and estimation of thermodynamic parameters of activation

Abstract

This work provides the first insights on the bioenergy potential of macauba endocarp (Acrocomia aculeate) based on the pyrolysis kinetics and thermodynamic parameters of activation. The kinetic triplet was obtained from non-isothermal thermogravimetric data by using four isoconversional methods, kinetic compensation effect, and master-plots method. The pyrolysis behavior of macauba endocarp was modeled with three independent parallel reactions, describing the devolatilization of pseudo-hemicellulose, pseudo-cellulose and pseudo-lignin, with average activation energies of 90.2 − 99.5, 113.6 − 123.9 and 153.0 − 167.3 kJ mol−1, respectively. Based on the pre-exponential factors, the devolatilization of both pseudo-hemicellulose and pseudo-cellulose occurred through surface reactions (≤ 109 min−1), while pseudo-lignin devolatilized through a simpler chemistry reaction (> 109 min−1). The master-plots method results showed that the devolatilization of pseudo-hemicellulose and pseudo-cellulose followed R-type models, while the devolatilization of pseudo-lignin followed an F-type model. The thermodynamic analysis indicated that macauba endocarp is a viable feedstock for bioenergy production. The summative kinetic expression proposed from the kinetic results was able to reproduce and predict with excellence the experimental behavior of macauba endocarp pyrolysis (R2 > 0.99 and Fit > 95.50%). This work's insights provide a new reference for future applications of macauba endocarp as an attractive and environmentally friendly alternative for bioenergy production.