Investigation on direct deoxygenation of bio-oil during biomass fast pyrolysis with CaO in a fluidized bed reactor

Direct deoxygenation effect of CaO on bio-oil from biomass pyrolysis was studied in a fluidized bed experimental apparatus. Bio-oil was produced at reaction temperature of 520℃ and carrier-gas flow-rate of 8000L/h using white pine alone and white pine accompanied with CaO, respectively. The result shows that the oxygen contents of the organic components in the bio-oils are 39.38%, 39.15%, 39.04% and 32.29% for white pine alone and white pines with 1, 2, 4 times of CaO added, respectively. With 4 times CaO added, the oxygen content of the organic components decreases by 18.0% (relative variation). Detailed GC-MS analysis indicates that the relative contents of high-oxygen containing levoglucosan, formic acid, acetic acid, etc. are greatly reduced with CaO-adding, implying the existence of the oxygen-capture path of “high-oxygen containing intermediates” in biomass pyrolysis process. Furthermore, the species of furfural is derived from dehydration reactions, and the increase in the relative content demonstrates that CaO-adding can also catalyze the dehydration reactions.