(231d) Effects of Synthetic Variations On the Dispersion of Pt Catalysts Supported On Aluminum-Modified TiO2

TiO₂ is a popular catalyst support because it is stable, versatile, non-toxic, and relatively inexpensive. We have focused on producing high surface area Al-stabilized anatase TiO₂ supports of controlled pore diameters with surface areas up to 490 m²/g. While TiO₂ is commonly used to support Pt, it is not well understood how synthetic variations affect the final structure and dispersion of the Pt. Therefore, previous studies have used laborious and often ineffective ‘trial and error’ methods to develop stable support materials and catalysts. Development during the past 3-4 decades of sophisticated surface and high energy spectroscopy techniques has enabled effective approaches based on scientific understanding of the structure of doped nanomaterials, which is the key to efficient design of stable high surface area materials. Through statistically designed experiments and EXAFS/XANES analysis, we have examined the effects of varying synthetic parameters on the bonding of Pt metal clusters dispersed on Al-TiO₂. Here we present insight into why some methods of preparation lead to better dispersion of the Pt, with dispersions ranging from 12%-53%. Understanding how sensitive the metal cluster structure and metal cluster-support interactions are to synthetic variations will help us predict the efficiency of dispersing Pt in TiO₂ supports and enable us to rationally design better TiO₂-supported Pt catalysts.