Impact of torrefaction on properties of Miscanthus × giganteus relevant to gasification

• The optimal torrefaction conditions for Miscanthus × giganteus are 250 °C and 30 min.
• The torrefied M × G has lower moisture and hemicellulose content as well as lower ratio of O/C.
• Torrefied biomass showed more porous structure with larger specific surface area and higher content of alkali metals.

Miscanthus × giganteus (M × G) was torrefied to improve its thermal and physical properties prior to thermal conversion. Torrefaction was undertaken at a series of temperatures from 230 to 290 °C for residence times varying from 10 to 30 min and the product biomass was characterized in terms of it is suitability as a feedstock for gasification. The properties of the torrefied M × G were improved following treatment. In particular the terrified biomass showed reduced moisture and hemicellulose content a lower ratio of O/C, a more porous structure with larger specific surface area as well as higher content of alkali metals. All these features have positive effect on gasification reactivity suggesting that the torrefaction process is promising pretreatment method for biomass to combine with gasification or co-firing.