Torrefaction under mechanical pressure of 10–70 MPa at 250 °C and its effect on pyrolysis behaviours of leucaena wood

In this study, torrefaction under mechanical pressure of 10–70 MPa at 250 °C was proposed as a pretreatment method and its effect on pyrolysis behaviours of Leucaena (LC) was examined at 900 °C. It was found that the mechanical pressure applied during torrefaction could significantly increase the char yield at 900 °C. The char yield increased from 18.7% for Raw to 26.4% and 27.5% for MP40 and MP70, respectively. The %C of biochar prepared from MP40 (MP40-900) was 86.5%, whereas the %C of biochar prepared from raw (Raw-900) was 82.6%. From TG-MS analyses during the pyrolysis of MP, a large amount of oxygen was removed as H2O and CO2. The analyses of tars produced from MP showed higher fraction of acids and furans compared with tar produced from Raw. Furthermore, the mechanism of the pyrolysis of LC torrefied under mechanical pressure was discussed.