Effect of torrefaction on pinewood pyrolysis kinetics and thermal behavior using thermogravimetric analysis.

Highlights • Volatiles of pinewood torrefied at 250 °C (PW250) was reduced by only 4% (wt). • Devolatilization and heat transfer performances of PW250 were enhanced. • PW250 contained more cellulose and higher crystallinity degree. • Pyrolysis of pinewood (PW) followed D3 model while PW250 mainly followed D1 model. Abstract Torrefaction is a promising pretreatment technology for biomass thermochemical conversion. In this study, pinewood (PW) and PW250 (torrefied at 250 °C) were prepared for pyrolysis. Torrefaction was carried out in a fixed bed reactor and the pyrolysis was studied by thermogravimetric analyzer using six different heating rates. The results showed that the content of hemicellulose in biomass decreased while cellulose and lignin increased after torrefaction. Moreover, the C-O peaks of torrefied biomass was strengthened in FTIR spectrum and the crystallinity degree was enhanced according to XRD analysis. The performance of devolatilization and heat transfer were improved for PW250 while the volatiles only decreased by only 4%. Activation energy was calculated by three iso-conversion methods. It was found that the PW followed D3 diffusion model, while the PW250 followed D1 diffusion model and tended to higher order reaction model at high conversions. In addition, the thermodynamic parameters were compared. [ABSTRACT FROM AUTHOR]