External Solvent‐Free Catalytic Hydrodeoxygenation of Softwood Lignin to Aromatics over Carbon–ZrO₂ Supported Ni/MoS₂ Catalysts

Abstract This work aims to convert black liquor‐ derived softwood lignin into industrially vital aromatic compounds by catalytic hydrodeoxygenation (HDO), without the use of external solvent. Lignin melts serve as the solvent itself under HDO conditions. Activated carbon supported NiMoS₂ catalysts are prepared by a water/oil micro–emulsion method and the required support acidity is tailored by addition of ZrO₂ (10–50%) to the support. The maximum deoxygenation of 82.2% is observed along with a monomer yield of 69.1% in 3 h reaction time, when 10% ZrO₂ is added to the carbon support. The yield of monomers is distributed in the following order: alkyl phenolics (23.1%) > guaiacolics (18.1%) > aromatic hydrocarbons (17.5%) > alkanes (10.5%). Interestingly, aromatic hydrocarbons yield increases with increase in time. The catalyst is found to be stable, without any significant loss in the activity and product selectivity when tested for up to five reaction cycles.