Controlled Generation of TiO_x–Au Interface Using Titanium Molecular Complex Bearing Pyridyl Anchors: Synthesis, Characterization and Catalysis

Interfacial perimeter sites between metal and support are often important for catalysis. A mononuclear titanium siloxy complex III, Ti(acac)₂[OSiC₆H₅N(OCH₃)₂]₂ was synthesized to generate TiO_x units of different degrees of clustering to decorate Au nanoparticles. Two different methods of preparation were examined; one was to deposit III onto Au/SiO₂ and the other was to form III-covered Au nanoparticle first before deposition onto SiO₂. The former method generated more highly dispersed TiO_x units, while larger domains of TiO₂ were formed with the latter method, as deduced by UV–vis and XAS characterization. A model was proposed to explain how TiO_x dispersity could be related to the preparative procedures. These samples were further tested as catalysts in selective oxidation of propane in a stream of O₂ and H₂. They exhibited different product selectivities. The sample with more dispersed TiO_x units were more selective for acetone formation versus propene formation. The results confirmed the important role of both the Au–TiO_x interface at the perimeter and the extent of Ti isolation in the TiO_x phase in the reaction.