Sequential pyrolysis of willow SRC at low and high heating rates – Implications for selective pyrolysis

• Published in: Fuel (Guildford) 2012-03, Vol.93, p.692-702
• Main Authors: Greenhalf, C.E., Nowakowski, D.J., Harms, A.B., Titiloye, J.O., Bridgwater, A.V.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bio-oil; Bubbling; Catechol; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fast pyrolysis; Fuels; Heating rate; Inverse; Mass spectroscopy; Pyrolysis; Py–GC–MS; Reactors; Slow pyrolysis; TGA; Willow
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2011.11.050

► We compared fast and slow pyrolysis of willow short rotation coppice (SRC). ► Analytical sequential pyrolysis was used to investigate product distribution. ► Pyrolysis temperature and heating rate influence product distribution. ► Bio-oil composition differs between fast and slow laboratory scale pyrolysis. The main aim of the work is to investigate sequential pyrolysis of willow SRC using two different heating rates (25 and 1500°C/min) between 320 and 520°C. Thermogravimetric analysis (TGA) and pyrolysis – gas chromatography – mass spectroscopy (Py–GC–MS) have been used for this analysis. In addition, laboratory scale processing has been undertaken to compare product distribution from fast and slow pyrolysis at 500°C. Fast pyrolysis was carried out using a 1kg/h continuous bubbling fluidized bed reactor, and slow pyrolysis using a 100g batch reactor. Findings from this study show that heating rate and pyrolysis temperatures have a significant influence on the chemical content of decomposition products. From the analytical sequential pyrolysis, an inverse relationship was seen between the total yield of furfural (at high heating rates) and 2-furanmethanol (at low heating rates). The total yield of 1,2-dihydroxybenzene (catechol) was found to be significant higher at low heating rates. The intermediates of catechol, 2-methoxy-4-(2-propenyl)phenol (eugenol); 2-methoxyphenol (guaiacol); 4-Hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde) and 4-hydroxy-3-methoxybenzaldehyde (vanillin), were found to be highest at high heating rates. It was also found that laboratory scale processing alters the pyrolysis bio-oil chemical composition, and the proportions of pyrolysis product yields. The GC–MS/FID analysis of fast and slow pyrolysis bio-oils reveals significant differences.