Torrefaction of agriculture and forestry biomass using TGA-FTIR-MS

Abstract

The torrefaction of agriculture (switchgrass and timothy) and forestry (spruce and pine) biomass was studied using simultaneously thermogravimetric analyzer (TGA) coupled with Fourier transform infrared (FTIR), and mass spectrometer (MS). The chemical functional groups present in the gases were identified by FTIR and the quantification of gaseous products was determined using MS at different torrefaction temperatures ranging from 200 to 290 °C. TG-FTIR and TGMS techniques are paired to refine the identification of gases. TGA results showed that the behavior of the agricultural and forestry biomass was not the same due to their composition variation. The decomposition of switchgrass took place at a lower temperature than other biomass. Both switchgrass and timothy have two peaks of degradation rate compared to only one peak present for forestry biomass. The FTIR analysis indicated that most of the chemical compositions present in the biomass are decomposed at torrefaction temperature of 290 °C. The mass spectrometric analysis at torrefaction temperature 200 and 230 °C quantified the degradation of combustible gases: Ch4, C2H4, CO, and O2 around 20–30 %, whilst at torrefaction temperature 260 and 290 °C the degradation of combustible gases was more than 30 %. Moreover, all gaseous products evolved from the torrefaction of agricultural and forestry biomasses were almost similar in characteristics, but varied in proportions.