Characterization and Reactivity Analysis of Hydrogen Adspecies on Platinum Nano-particles Supported on Alumina

Abstract

The dispersion state of Pt nano-particles supported on Al₂O₃ was investigated by gas chemisorption. The amount of H₂ chemisorption was larger than that of CO over the entire range of Pt dispersion. Pt dispersion beyond 100 % was estimated for Pt/Al₂O₃ with nano-sized Pt particles by H₂ chemisorption. FT-IR measurements of hydrogen species adsorbed on Pt/Al₂O₃ with different Pt dispersions revealed that hydrogen species dissociatively adsorbed on Pt nano-particles and spilled over onto Al₂O₃. Hydrogen species dissociatively adsorbed on Pt nano-particles were highly reactive with NO at room temperature, leading to the formation of N₂. In contrast, hydrogen species spilled over onto the fringes of Pt particles reacted with NO to form N₂O.