Effect of Pyrolysis Temperature and Sulfuric Acid During the Fast Pyrolysis of Cellulose and Douglas Fir in an Atmospheric Pressure Wire Mesh Reactor

The goal of this study is to better understand important reactions responsible for the suppression of anhydrosugars during the pyrolysis of microcrystalline Avicel, ball-milled Avicel, levoglucosan, cellobiosan, and Douglas fir at varied pyrolysis conditions (heating rate 100 °C/s, temperature 300–500 °C, H 2 SO 4 addition 0–0.6 wt %) in an atmospheric pressure wire mesh reactor. Pyrolysis of levoglucosan at 300 °C yielded 67 wt % of itself, indicating that this is a reactive molecule. Pyrolysis of cellobiosan at 300 °C resulted in the production of relatively large quantities of an unidentified compound (estimated in 22 wt %) and a solid residue (18 wt %) with small quantities of levoglucosan. This result suggests that cellobiosan is an important intermediate for char formation during cellulose pyrolysis. When sulfuric acid (0.04 wt %) was added in small amounts to the control and ball-milled cellulose, the yield of levoglucosan decreased and 1,6-anhydrogulcofuranose was formed through accelerated dehydration reactions. In the case of the Douglas fir, an increase in levoglucosan yield (from 30 to 40 wt %) may occur via mitigation of cellulose–lignin interactions in this material or through passivation of the remaining AAEMs (0.013 wt %). At higher acid concentrations the levoglucosan yield decreases, likely due to the acceleration of cellulose dehydration reactions.