Pilot scale oxidative fast pyrolysis of sawdust in a fluidized bed reactor: A biorefinery approach

Oxidative fast pyrolysis of sawdust was performed in a pilot scale fluidized bed system (3 kg/h) under stabilized experimental conditions (0.20 equivalence ratio and 550 °C). Experiments were performed in non-catalytic and catalytic (ZSM-5) mode. During non-catalytic fast pyrolysis, bio-oil (∼38 wt%), bio-char (∼12 wt%) and pyro-gas (∼50 wt%) were obtained; in contrast, for catalytic fast pyrolysis bio-oil, bio-char and pyro-gas yields were ∼44 wt%, ∼4 wt% and ∼52 wt% respectively. The obtained bio-oil was characterized through CHNSO, NMR (¹H and ¹³C NMR), FT-IR and GC-MS techniques. GC-MS analysis of the bio-oil shows it is a mixture of ∼21 chemical compounds. Furthermore, NMR (¹H and ¹³C NMR) and FT-IR results indicates presence of hydrocarbon, alcohol, phenol and aldehyde in the bio-oil. The TGA of bio-char shows that it is stable up to 950 °C. The activation energies (E_a) of sawdust and bio-char are found to be 112.3 kJ/mol and 46.92 kJ/mol respectively. FT-IR analysis of bio-char clearly revealed removal of functionalized organic compounds during devolatilization of sawdust. In addition, GC analysis of pyro-gas suggests that it is a mixture of N₂ (35.55 vol%), CO (34.49 vol%), CO₂ (16.80 vol%), H₂ (4.54 vol%), O₂ (4.25 vol%), and CH₄ (4.41 vol%).