In this paper,we sought to elucidate the relationships between biomass feedstock type and the suitability of their
fast-pyrolysis bio-oils for hydrodeoxygenation (HDO) upgrading. Switchgrass, Eucalyptus benthamii, and equine
manure feedstocks were pyrolyzed into bio-oil using a continuous fast-pyrolysis system. We also synthesized
variations of switchgrass bio-oil using catalytic pyrolysismethods (HZSM-5 catalyst or tail-gas recycle method).
Bio-oil samples underwent batch HDO reactions at 320 °C under ~2100 psi H2 atmosphere for 4 h, using Pt, Ru, or
Pd on carbon supports. Hydrogen consumption was measured and correlated with compositional trends. The
resulting organic, aqueous, and gas phaseswere analyzed for their chemical compositions.Mass balances indicate
little coke formation. Switchgrass bio-oil over Pt/C performed the best in terms of hydrogen consumption efficiency,
deoxygenation efficiency, and types of upgraded bio-oil compounds. Eucalyptus feedstocks consistently
consumed more than twice the normal amount of hydrogen gas per run, primarily due to the elevated syringol
content. Catalytically pyrolyzed bio-oils deoxygenated poorly over Pt/C but hydrogenated more extensively
than other oils. Although the relative deoxygenation (%DOrel) varied based on feedstock and catalyst, the absolute
deoxygenation (%DOabs) depended only on the overall yield. The total extent of upgrading (hydrogenation+ deoxygenation)
remained independent of feedstock and catalyst.