Unlocking Biomass Energy: Lignin to Fuel

Plant biomass is largely composed of cellulose, hemicellulose, and lignin. Lignin has been the hard nut to crack. It is the glue holding biomass together, and tends to gum up many chemical processes that try to extract the energy from biomass. Researchers at Peking University may have developed a better process for breaking lignin down to hydrocarbon fuels.

The researchers used near-critical water as a solvent and treated the white birch sawdust over a series of active carbon supported catalysts (Ru/C, Pd/C, Rh/C, and Pt/C) under modest pressures of H2 under varying conditions. Treatment of the sawdust in a mixture of dioxane and near-critical water (364°C and 190 atm) in a ratio of 1:1 combined with 1 wt% H3PO4 over Pt/C and Rh/C catalysts yielded about 45 wt% monomers (very close to the calculated maximum) and 12 wt% dimers. The catalysts can be reused directly after reaction without any apparent deactivation.

Following extraction, the monomers and the dimers were transferred to the second step for conversion into alkanes and methanol. _Read more at GCC

These catalysts are rather expensive, and may later be replaced by custom-made nanocatalysts made of more common materials such as carbon. The yields for this procedure are not optimal, so much work remains. Still, this process is an alternative to gasification, which tends to break biomass down more than necessary, only to be forced to build liquid fuels almost from component atoms.

More on this process from New Scientist

We will need to follow this line of research to monitor progress.