PY-GC/MS studies to evaluate the effect of torrefaction temperature on pyrolysis products of Douglas fir and hybrid poplar wood

The effect of torrefaction temperature on the semi-quantitative yield of pyrolysis products from Douglas fir wood (DFW) and hybrid poplar wood (HPW) was investigated. The torrefaction temperatures tested were 250°C, 270°C, 290°C, 310°C, 330°C, 350°C, and 380°C using the CDS pyro-probe interface. Samples were torrefied for 1 min prior to pyrolysis at 500°C. Major ions were analyzed for identification of pyrolytic compounds. Fragments generated from cellulose, hemicellulose, and lignin were identified, and the semi-quantitative yields were obtained for different torrefaction temperatures. The yields of most pyrolytic compounds decreased greatly above 310°C. HPW generated more fragmentation products and less anhydrosugars and guaiacyls than DFW. The torrefaction pretreatment did not affect the production of levoglucosan at relatively low temperatures, but the yield of this compound decreased dramatically above 310°C. Our results suggest that at torrefaction temperatures below 310°C, dehydration and cross-linking reactions are negligible. At higher temperatures, secondary reactions responsible for the decrease in the yield of some volatile compounds and the formation of extra char are accelerated. © 2014 American Society of Agricultural and Biological Engineers