Supported Amphiphilic Hybrid Ionic Liquid Phosphomolybdates on ZrO ₂ for Catalytic Conversion of Lignin to Aromatic Compounds

Lignin, a crucial renewable biomass component, represents a high-value pathway for achieving efficient biomass utilization. However, its complex and stable structure hinders the development of effective lignin depolymerization catalysts. In this study, the water-soluble H₃PMo₁₂O₄₀ was combined with [Bmim]⁺ to form hydrophobic [Bmim]₃PMo, which was supported on ZrO₂ at various weight ratios to prepare [Bmim]₃PMo@ZrO₂ catalysts. These catalysts demonstrate excellent activity in lignin oxidative depolymerization, selectively producing monomeric phenolics (methyl vanillate, vanillin, methyl syringate, syringaldehyde). The 40 wt % [Bmim]₃PMo@ZrO₂ catalyst achieves optimal performance with 88.5% lignin conversion and 12.4 wt % phenolic yield. Two-dimensional nuclear magnetic resonance heteronuclear single quantum coherence (2D HSQC NMR) analysis confirms that the catalyst effectively cleaves the critical β-O-4 linkages in lignin. Furthermore, [Bmim]₃PMo@ZrO₂ has excellent reusability with stable performance over five cycles. These findings establish [Bmim]₃PMo@ZrO₂ as a promising lignin valorization candidate, inspiring efficient catalyst design for producing high-value aromatic compounds.