Nano-supported metal oxides as a new type of catalyst structure

Nano-supported metal oxide catalysts were self-assembled through surfactant templating, the use of ZrO ₂ nanoparticles (NP) and either ammonium meta-tungstate or ammonium metavandate. The resultant nano-WO ₃/ZrO ₂ and nano-V ₂O ₅/ZrO ₂ catalysts were found by in situ Raman and UV-visible to possess unique surface metal oxide species that were extensively polymerized with bridging M-O-M bonds and almost no terminal M=O bonds. The surface WO _x species on the ZrO ₂ NP exhibited about a 10-fold increase in their acidic activity for methanol dehydration to dimethyl ether compared to conventional supported WO ₃/ZrO ₂ catalysts. In contrast, the surface VO _x species on the ZrO ₂ NP exhibited about a 10-fold decrease in their redox activity for methanol oxidation to formaldehyde compared to conventional supported V ₂O ₅/ZrO ₂ catalysts, which may find application for oxidation reactions at elevated temperatures where over-oxidatlon was a concern. Novel surface metal oxide molecular structures that possess unique acidic and redox catalytic properties were self-assembled on ZrO ₂ NP to yield a new class of supported metal oxide catalysts. This is an abstract of a paper presented at the 227th ACS National Meeting (Anaheim, CA 3/28/2004-4/1/2004).