Pyrolysis of Suncheon-Bay wild reed over zeolite catalysts

The catalytic fast pyrolysis of wild reed was carried out over HZSM-5 zeolite catalysts with two different SiO₂/Al₂O₃ ratios, 23 and 280. The effects of the pyrolysis temperature and catalyst on the bio-oil yield were examined using a laboratory-scale batch-type quartz reactor for the pyrolysis experiments over the temperature range, 440-560°C. The highest bio-oil yield was obtained between 520°C and 560°C depending on the catalytic conditions. The bio-oil yields obtained from catalytic pyrolysis were generally lower than those obtained from non-catalytic pyrolysis because of the cracking of large-molecular-mass products into gaseous species. Further experiments were carried out using the pyrolysis-gas chromatography/mass spectrometry at 550°C for the in-situ analysis of the species distribution of the product bio-oil. Regardless of the use of catalyst, oxygenates were the most abundant products from the pyrolysis of wild reed, followed by phenolics. The fraction of total oxygenates was reduced considerably when pyrolysis was carried over HZSM-5(23). Unlike the other oxygenate species, the production of furans was promoted by catalytic reforming. Furans produced during the pyrolysis process were apparently converted to aromatics upon the catalytic reforming over HZSM-5(23) owing to its large number of strong Brønsted acid sites. Large-molecular-mass oxygen-containing phenolics were converted by catalytic reforming to small-molecular-mass oxygen-free phenolics and aromatics via cracking, dehydration, and deoxygenation. The catalytic effect of HZSM-5(280) was much smaller than that of HZSM-5(23) in every respect owing to its small number of Brønsted acid sites. Another significant change made by catalytic reforming was the increase in the fraction of aromatics. In particular, when pyrolysis was performed over HZSM-5(23), the fraction of aromatics was 14%, whereas they were not produced from non-catalytic pyrolysis.