Immobilization of Heteropolyacid Nanoparticles within SBA-3 mesoporous silica

Catalysis by heteropolyacids (HPA) and related polyoxometalate is a field of increasing importance [1]. Pure heteropoly acids, generally containing at least four different types of elements, that have unique physicochemical properties such as strong Brønsted acidity, reversible multielectron redox transformations, activation of molecular oxygen and hydrogen peroxide, high proton mobility across their discrete ionic structure, etc. These properties make HPA promising acid, redox, and bifunctional catalyst in homogeneous as well as in heterogeneous systems [2]. Many efforts have been dedicated to utilize mesoporous materials as nanoreactors for preparation of monodispersed uniform nanoparcticles and production of heterogeneous and selective catalysts [3-5]. Efficient heterogeneous catalysts may be designed by encapsulation of PMo into silica matrix via grafting method. In this way, mesopores or channels are regarded as hosts and PMo nanoparticles as guests in the host–guest chemistry.SBA-3 is a hexagonal mesoporous molecular sieve (P6m) which has been noticed to contain some micropores [6]. It is synthesized under strong acidic conditions, using cetyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS) as surfactant and silica source.In this work, SBA-3 mesoporous silica, with high surface area, is applied as a host to incorporate H3PMo12O40 heteropolyacid. The resulting material was characterized via XRD, SEM, and FT-IR analyses