Organometallic-polyoxometalate hybrid based on V-Schiff base and phosphovanadomolybdate as a highly effective heterogenous catalyst for hydroxylation of benzene

A novel organometallic-polyoxometalate hybrid has been prepared by anion-exchange of V Schiff base functionalized ionic liquid with V-containing Keggin-type polyoxometalate. The hybrid solid with two types of catalytic active V components demonstrates remarkable capability for heterogeneous hydroxylation of benzene with excellent phenol yield 19.6% and 100% selectivity. After reaction, the catalyst can be simply recovered by filtration and reused at least 4 times without the change of catalyst structure. The synergistic effect between metal Schiff base complex and polyoxometalate plays an important role in the promotion of catalytic activity. (C) 2013 Elsevier B.V. All rights reserved.