(716d) Investigation of Gold-Metal Oxide Interface: Active Site for Selective Oxidation

Gold nanoparticles supported onto metal oxides have potential for selective oxidation of alkanes, but catalytic performance has to be improved for practical applications. A logical point of attack is the active site, but both the specific active site of gold and the role of the support are unresolved. However, it is commonly agreed that the location of the active site is at the interface of gold (Au) and the support (metal oxide) for oxidation reactions. Two important parameters will be investigated at the interface: nuclearity and nature of the metal-oxide at the gold-metal oxide interface. In order to study this interface a synthesis scheme to control local environment of the Au particles must be developed.

            We have developed a scheme where polymethylhydrosiloxane (PMHS) is modified with an amine precursor, N-methyl-aza-2,2,4-trimethylsilacyclopentane, which was used to bind and stabilize the Au particles. Using the modified PMHS, Au nanoparticles were prepared by addition of Au precursor, chloro(tetrahydrothiophene)gold (I), which were reduced using hydrosiloxane. At a ligand:Au ratio of 10, particles less than 4nm in size were obtained with high loading (>7%). Titanium-oxo precursors were also incorporated onto amine functionalized PMHS at different loadings to study the effect of the presence of the metal oxide for selective oxidation of propane. For future work, different types of metal-oxo species and different nuclearities will be incorporated onto PMHS and their catalytic effects would be studied.