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

Abstract

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.