Palladium-Nafion SAC-13 catalysed depolymerisation of lignin to phenols in formic acid and water

Guaiacol, pyrocatechol and resorcinol, were isolated and quantified as the major products from catalytic pyrolysis of lignin of various origin. The novel procedure utilises formic acid as the hydrogen source in combination with a palladium catalyst and Nafion® SAC-13 as a solid acid catalyst with water as reaction medium. The reaction is conducted at moderate pyrolysis temperature and short reaction time. Several palladium based catalysts and different types of lignin were investigated. The lignins and the model compounds demonstrated various chemical behaviour, under identical reaction conditions; various phenols were formed from the lignins, while the model compounds were hydrodeoxygenated, demethylated and demethoxylated.

► Depolymerisation of lignin to phenols.
► Water as solvent, formic acid, as hydrogen source, palladium catalyst and Nafion SAC-13 as solid recyclable super acid.
► Relative low temperature and short reaction time.
► Guaiacol, pyrocatechol and resorcinol as main phenols.
► Pd/C and Pd Lindlar among best Pd-based catalysts.