571 / 2019-01-19 13:40:52

In situ hydrodeoxygenation of model compounds in the aqueous phase for bio-oil upgrading

Hydrodeoxygenation; Hydrothermal liquefaction; Bio-oil aqueous phase; Model compounds

全体主题 > 节能、联产、热泵

Bio-oil derived from lignocellulosic biomass via pyrolysis/liquefaction consists of hundreds oxygen-containing compounds, of which phenolics and aldehydes are very unstable compounds in the bio-oil that can react with lots of different chemical compositions, resulting in polymerization and poor fuel properties. Hydrodeoxygenation (HDO) of oxygenated compounds is a promising upgrading method to convert the unstable oxygenated compounds to more stable compounds. In this paper, HDO of model compounds (phenol, guaiacol and furfural) was investigated in an autoclave at 370 篊 with NiS-MoS dispersed catalyst using bio-oil aqueous phase as the solvent. Zero-valent aluminum (ZV-Al) produced hydrogen in situ for the HDO of model compounds via redox reactions in the aqueous phase. Effects of reaction time and ZV-Al to bio-oil aqueous ratio (hydrogen amount) on the HDO of model compounds were investigated, and results showed that the reaction time and the ZV-Al to bio-oil aqueous ratio had positive effects on the conversion of the model compounds. As the reaction time prolonged, the conversion ratios of phenol, guaiacol and furfural were increased from 50.90%, 69.73% and 62.75% at 15 min to 75.87%, 84.80% and 83.555 at 60 min, respectively. When the ZV-Al to bio-oil aqueous phase ratio was increased from 0 to 2/25 g/mL, the conversion of phenol, guaiacol and furfural were increased from 40.01%, 43.61% and 51.40% to 75.87%, 84.80% and 88.84%, respectively. After HDO, the phenol was mainly converted into cyclohexanone, cyclohexanol, cyclohexene and cyclohexane. The guaiacol was mainly converted into catechol, phenol and methoxybenzene. The furfural was mainly converted into furan, furfuryl alcohol, cyclopentanone and cyclopentanol. The conversion pathway of oxygen-containing functional groups in model compounds was investigated. Hydrodeoxygenation, methyl transfer and methyl substitution reactions were mainly occurred in phenols, while hydrogenation, decarbonylation and isomerization were dominated in the furfural conversion process.