Compositional Changes during Hydrodeoxygenation of
Biomass Pyrolysis Oil
- Publication date
- Publisher
Abstract
Hydrodeoxygenation
(HDO) is usually considered as a promising process
for upgrading biomass pyrolysis oil (PO) to bio-fuels. However, cognition
of HDO is inhibited by the complexity of the PO and upgraded products.
In this study, a PO and its upgraded pyrolysis oil (UPO) samples were
analyzed by nuclear magnetic resonance, gas chromatography/mass spectrometry,
and electrospray ionization Fourier transform ion cyclotron resonance
mass spectrometry (ESI FT-ICR MS). ESI FT-ICR MS revealed the most
abundant compounds in PO were O<sub>2</sub>–O<sub>18</sub> species
with double bond equivalent (DBE) values of 0–22. After HDO,
oxygen numbers gradually shifted to a range of O<sub>1</sub>–O<sub>10</sub>, and DBE number also progressively decreased. The major
oxygen compounds such as carbonyls, carboxylic acids, ethers, carbohydrates,
and alcohols were significantly changed with respect to relative content
and molecular composition. Lignin polymers were depolymerized after
reduction of the carbonyl and methoxy groups. For HDO, hydrogenation
of carbonyls, carbohydrates, and furans occurred under 150 °C.
Dehydration, hydrodeoxygenation, and dehydration–hydrogenation
reactions were initiated at 210 °C. Decarboxylation and decarbonylation
required higher temperatures (>300 °C)