Experimental Study of Volatile Products Generated by Ring-Opening Reactions during Syringol Pyrolysis

Ring-opening reactions to support the formation of CO, CO2 and C1-C5 light hydrocarbons (C1-C5 LHs) is one important pathway in vapor-phase reactions during lignin pyrolysis. Syringyl structure is rich in primary volatile products generated from lignin pyrolysis, and inevitably involved in vapor-phase reactions. However, there is less available information to elucidate the mechanism of syringol pyrolysis. In this work, syringol was pyrolyzed in a tubular reactor at 550-950 oC (0.5s) and at 750 oC(0.1-4.2 s). Distributions of volatile products from syringol pyrolysis were quantified by online GCs, focused on CO, CO2, C1-C5 LHs, phenols, light oxygenated compounds and aromatic products. Syringol was decomposed dramatically above 750 oC with residence time 0.5 s. Main volatile products were CO, CO2 and C1-C5 LHs, which were possibly formed by ring-opening reactions of syringol. C1-C5 LHs were consumed to support the formation of aromatic hydrocarbons. Detailed data were provided in this communication, and is significant to theoretically investigate the process of syringol pyrolysis with the aim to elucidate the pyrolysis mechanism of syringyl structure during lignin pyrolysis.