Detailed identification and quantification of the condensable species released during torrefaction of lignocellulosic biomasses

• Condensable species released by torrefaction of four biomasses were analysed.
• The mean quantification rate of the condensable species is 77 wt.%.
• 85 condensable species are identified by GC–MS.
• Temperature and nature of biomass strongly influence yields of condensable species.
• Terpenes and terpenoids in pine are identified by adsorption on SPME fibre.

Torrefaction is a mild thermal pretreatment which improves biomass properties and releases condensable species. Condensable species released during torrefaction of pine, ash wood, miscanthus and wheat straw at 250, 280 and 300 °C were investigated. A fixed-bed reactor was used for the laboratory scale experiments. A micro-GC, Karl Fischer titrator and GC-MS were used to analyse incondensable gases, water and other condensable species, respectively. The overall mass balance ranged from 96 to 103 wt.%. The quantification rate of condensable species was on average 77 wt.%. In addition to the major species usually reported in the literature – water, acetic acid, 2-propanone,1-hydroxy- – we show that large amounts of some anhydrosugars were produced. Additionally, 85 condensable species were identified. Among these species, many terpenes and terpenoids in pine were identified by adsorption on SPME fibre. Finally, the influence of temperature and of the nature of biomass on the yields of condensable species was highlighted.