Supported Amphiphilic Hybrid Ionic Liquid Phosphomolybdates on ZrO2 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.