Boosting H₂O₂ utilization efficiency in benzene hydroxylation to phenol via isolated single VO₄ site on hydrophobic poly(ionic liquid)-derivative

Hydrogen peroxide (H₂O₂)-mediated benzene hydroxylation is one of the most attractive avenues towards green synthesis of phenol, a crucial industrial feedstock. Nonetheless, it remains one challenge to explore efficient catalysts, especially the one allowing high H₂O₂ utilization efficiency to fulfill the safety production. In this work, isolated single VO₄ sites were constructed on the hydrophobic poly(ionic liquid)-derivative through copolymerization of dinuclear imidazolyl ionic liquid and polyhedral oligomeric silsesquioxane (POSS), ion change with ammonium metavanadate (NH₄VO₃), and the pyrolysis under moderate temperature. The combination of V(IV) single sites and a hydrophobic surface made the catalyst effectively catalyzing the phenol synthesis from benzene oxidation with H₂O₂, giving phenol selectivity above 99 %, H₂O₂ utilization efficiency of 92 %, and turnover frequency (TOF) beyond 900 h⁻¹. The catalyst was stably recycled and exhibited broad substrate compatibility. The pyrolysis step strengthened both stability and activity, significantly contributing to the high catalytic efficiency.