In situ catalytic hydrogenation of model compounds and biomass-derived phenolic compounds for bio-oil upgrading

The renewable phenolic compounds produced by directional liquefaction of biomass are a mixture of complete fragments decomposed from native lignin. These compounds are unstable and difficult to use directly as biofuel. Here, we report an efficient in situ catalytic hydrogenation method that can convert phenolic compounds into saturated cyclohexanes. The process has high potential for production of hydrocarbon transportation fuels. In the in situ catalytic hydrogenation system, phenolic compounds were converted into cyclohexanol derivatives (that can be efficiently converted into cyclohexane-hydrocarbon fuels by acid-catalyzed dehydration) with a conversion yield 98.22 wt% under mild conditions (220 °C for 7 h with Raney Ni). The in situ catalytic hydrogenation of phenolic compounds, using methanol as a liquid hydrogen donor, was found to be superior to traditional hydrogenation using external hydrogen gas. The in situ hydrogenation of phenolic compounds was coupled with aqueous-phase reforming of methanol. The conversion of guaiacol and target product yields were significantly higher than by traditional hydrogenation.