Hydroxylation of benzene to phenol over heteropoly acid H5PMo10V2O40 supported on amine-functionalized MCM-41

Abstract

Supported catalysts with Keggin type heteropoly acids (H₅PMo₁₀V₂O₄₀) loaded onto amine-functionalized MCM-41 for the catalytic hydroxylation of benzene to phenol with H₂O₂ were prepared by a wet impregnation method. The effects of the preparation conditions on the properties and activity of the supported catalysts were fully investigated. The results showed that the catalyst retained the mesoporous structure of MCM-41 and H₅PMo₁₀V₂O₄₀ was dispersed uniformly on the surface of the amine-functionalized MCM-41. Meanwhile, the reusability and catalytic performance of the catalyst were affected by two key factors, i.e., the interaction between the heteropoly acid and the surface of MCM-41, and the hydrophobicity of the catalyst since they decide the leaching of H₅PMo₁₀V₂O₄₀ and the adsorption of benzene. The catalyst with H₅PMo₁₀V₂O₄₀ loaded onto amine-functionalized MCM-41, which was prepared using ethanol as the solvent, exhibited the highest phenol yield (20.4%), a turnover frequency value of 20.3 h⁻¹ and good reusability. We believe this work offers an effective and facile strategy for the preparation of a new catalyst for hydroxylation of benzene to phenol.