Interaction Between Pt(acac)2 and Alumina Surfaces Studied by XAS

The anchoring and decomposition mechanisms of platinum(II) bis-acetylacetonate on alumina surfaces are studied by X-ray absorption spectroscopy at the platinum LIII edge. A distinction is made between highly reactive surfaces which are partially dehydroxylated and exhibit coordinatively unsaturated surface sites, and deactivated surfaces which are covered by a monolayer of OH groups. The samples are studied after three stages of a wet impregnation synthesis: after drying at room temperature, drying at 120 °C and calcination at 350 °C. The XANES signal and the filtered EXAFS signals of the first and second coordination shells around platinum were analyzed. Two different mechanisms are discussed for the two types of supports.