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

Abstract

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 TiOx 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 TiOx 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 TiOx 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 TiOx units were more selective for acetone formation versus propene formation. The results confirmed the important role of both the Au–TiOx interface at the perimeter and the extent of Ti isolation in the TiOx phase in the reaction.