Effects of heating rate on the evolution of bio-oil during its pyrolysis

• Published in: Energy conversion and management 2018-05, Vol.163, p.420-427
• Main Authors: Xiong, Zhe, Wang, Yi, Syed-Hassan, Syed Shatir A., Hu, Xun, Han, Hengda, Su, Sheng, Xu, Kai, Jiang, Long, Guo, Junhao, Berthold, Engamba Esso Samy, Hu, Song, Xiang, Jun
• Format: Article
• Language: English
• Subjects: Aromatics; Bio-oil; Biomass; Coke; Cyclotron resonance; Decomposition reactions; Fluorescence; Fluorescence spectroscopy; Fourier transforms; Gas chromatography; Heating; Heating rate; High temperature; Low temperature; Macromolecules; Mass spectroscopy; Natural gas; Oil; Organic chemistry; Polymerization; Pyrolysis; Synthesis gas; Tar; Vegetable oils; Yield
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2018.02.078

•Slow heating rates promote primary reactions during bio-oil pyrolysis.•Fast heating rate promote the secondary cracking of vapor.•A proposed reaction mechanism of bio-oil pyrolysis is provided.•The characteristics of primary and secondary products varied with the heating rate. Bio-oil from the fast pyrolysis of biomass can be converted to solid carbon materials, chemicals and syngas by various thermochemical conversion methods. As a first step in all of these processes, bio-oil undergoes drastic components changes due to its exposure to the elevated temperature. Understanding the effects of heating rate on bio-oil transformation during its pyrolysis is therefore crucial for effective utilization of bio-oil. In this study, a bio-oil sample produced from the fast pyrolysis of rice husk at 500 °C was pyrolyzed in a fixed-bed reactor at temperatures between 300 and 800 °C at three different heating rates: fast (≈200 °C/s), medium (≈20 °C/s), and slow (≈0.33 °C/s). In addition to the quantification of coke and tar yields, the tar was characterized with an ultraviolet (UV) fluorescence spectroscopy, a gas chromatography/mass spectrometer (GC/MS) and a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Our results indicate that slow heating rates promote polymerization of bio-oil components, particularly at low temperatures ( 500) were also promoted at fast heating rates via the more intense secondary reactions.