Characteristics and Mechanism of Soot Formation during the Fast Pyrolysis of Biomass in an Entrained Flow Reactor

To understand the effects of biomass origin and temperature on the characteristics of soot formation from biomass, fast pyrolysis of wheat straw and sawdust was performed in an entrained flow reactor in the temperature range of 900–1300 °C. The produced soot, permanent gas, and tar were sampled and characterized by transmission electron microscopy (TEM) and gas chromatography/gas chromatography–mass spectroscopy (GC/GC-MS) with respect to yield, morphology, structure, and composition. Moreover, soot formation was modeled in a plug flow reactor (PFR) with a detailed reaction mechanism. Results indicate that the woody biomass produced a significant higher quantity of soot (0.34%–6.30% (dry biomass, db)) than that from straw (0.28%–2.40% (db)), and the woody soot has a more ordered structure. The reason for this was primarily ascribed to the combined effects of high contents of lignin, cellulose, and low content of ash in woody biomass. The carbonization of soot occurred at about 1100 °C when primary spheric...