Design of active molybdenum oxides: β-MoO3 and/or silicomolybdic acid supported on mesoporous MCM-41 catalysts

A silicomolybdic acid (SMA) supported on mesoporous MCM-41 catalyst was successfully prepared by an impregnation with a molybdic acid solution via ion exchange of a Na2MoO4 · 2H2O solution. On the other hand, β-MoO3, the metastable phase of molybdenum oxide, was predominantly generated on MCM-41 by use of the molybdic acid solution adjusted by nitric acid and was anchored by the formation of SMA on the support. The molybdic acid is an attractive precursor to design either SMA or β-MoO3 as well as to stabilize them on MCM-41 by the formation of SMA. Those catalysts showed interesting performances in partial oxidation of methane to formaldehyde by molecular oxygen.