Page 121 - Advances in bioenergy (2016)

In a similar work, Aho et al. 30,36 loaded a BFB pyrolysis reactor with various catalysts (beta,
Y, ZSM-5, and mordenite) and observed that the catalyst structure influenced the composition
of the bio-oils but not the yield. Pyrolysis in the presence of a zeolite catalyst resulted in a bio-
oil yield ranging between 43.5 and 52.7 wt%. A higher selectivity for organics was observed
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that was directly related to more H O and CO production. Li et al. also used a BFB pyrolysis
2
reactor with a packed bed for the upgrading of the pyrolysis vapors with an FCC catalyst
producing a bio-oil with lower amounts of acids (14.5–3.021 wt%) and increased amounts of
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aromatic hydrocarbons (0.488–16.795 wt%). Park et al. also tested the second stage
approach using a BFB pyrolysis reactor and a fixed bed for the vapor upgrading. Among the
catalysts tested (HZSM-5, HY, Ga/HZSM-5, and Ga/HY), HZSM-5 was more effective at
upgrading the bio-oil than HY. Deoxygenation was achieved mainly by conversion of oxygen to
H O, CO, and CO .
2
2
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Wang et al. attempted to produce light aromatic hydrocarbons from biomass by catalytic
pyrolysis using a BFB pyrolyis reactor with CoMo-S/Al O in the catalyst bed and achieved a
2 3
maximum yield of benzene, toluene, xylene, and naphthalene of about 6.3 wt% at 590°C. Zhang
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et al. also used a BFB pyrolysis reactor with HZSM-5 catalyst achieving a 56.8 wt% liquid
yield with very low oxygen content in the organic fraction (14.69 wt%). The H–C and O–C of
the oil was 1.51 and 0.15 respectively, whereas its higher heating value (HHV) was
34.6 MJ/kg. The HZSM-5 catalyst reduced concentrations of ketones and phenols and caused a
dramatic increase in aromatics in the bio-oil (7.62–74.22 wt%). The same group recently
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tested FCC in a BFB pyrolysis reactor. The optimal catalyst to biomass ratio was 1:10 for
fresh FCC and 1:5 for spent FCC, resulting in the first case (fresh FCC) in lower maximum oil

yields (11.8 wt%) than when using the spent FCC (18 wt%). Increasing catalyst mass led to
increased hydrocarbons in the oil, whereas it was concluded that less C and O were
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transferred to the oil in the presence of the catalyst. Finally, Hew et al. performed catalytic
cracking of bio-oil with HZSM-5 in a batch reactor and obtained 91.67 wt% of organic liquid
product and 46.67 wt% of gasoline range product.