Direct immobilization of self-assembled polyoxometalate catalyst in layered double hydroxide for heterogeneous epoxidation of olefins

We present a novel method for the fabrication of immobilized polyoxometalate catalysts that directly use a self-assembled polyoxometalate solution without isolation and purification. Specifically, self-assembled [WZn3(ZnW9O34)(2)](12-) catalyst can be selectively immobilized into layered double hydroxides in the presence of undesired anions. The material thus obtained demonstrates high dispersion and good hydrothermal stability. The heterogenized catalyst exhibits excellent activity (turnover frequency up to 18,000 h(-1) at 50 degrees C) in the epoxidation of allylic alcohols with aqueous H2O2 and can be readily recycled with no apparent loss of performance. (c) 2008 Elsevier Inc. All rights reserved.