Hydrodeoxygenation of lignin model compounds over a copper chromite catalyst

The hydrodeoxygenation of benzyl alcohol, phenol, anisole, o-cresol, catechol, guaiacol, and vanillyl alcohol were carried out from 150 to 275 °C at 50 bar H2 with a CuCr2O4·CuO catalyst in a decalin solvent. The hydroxymethyl group of benzyl alcohol was found to be highly reactive towards hydrogenolysis to form toluene. Demethoxylation of anisole to form benzene was found to be the primary reaction pathway in contrast to demethylation and transalkylation reactions, which are more prevalent for conventional hydrotreating catalysts. The hydroxyl group of phenol strongly activated the aromatic ring towards hydrogenation forming cyclohexanol which was subsequently dehydrated and hydrogenated to form cyclohexane. Reaction networks of increasing complexity were devised for the major functional groups and integrated to describe the most complex molecule studied, vanillyl alcohol.

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► Reaction networks were determined for lignin model compounds conversion over copper.
► Demethoxylation was found to be a leading deoxygenation reaction.
► Hydroxyl/methoxy groups were found to activate the aromatic ring hydrogenation.
► Methyl groups stabilized the aromatic group against hydrogenation.