Synthesis and Microscopic Characterization of Dendrimer-Derived Ru/Al2O3 Catalysts

Fourth generation poly(amidoamine) dendrimers have been used to template and stabilize Ru nanoparticles in solution. UV-visible spectroscopic results indicate that Ru³⁺ ions from a RuCl₃ precursor can complex with functional groups within the dendrimer structure. Subsequent reduction of the Ru³⁺ ions yields finely dispersed Ru nanoparticles with a narrow particle size distribution. These dendrimer-stabilized nanoparticles were deposited onto an alumina support and thermally activated to remove the dendrimer “shell”, as indicated by in situ Fourier transform infrared (FTIR) spectroscopic measurements. High resolution transmission electron microscopy (HRTEM) measurements indicate that the resulting Ru/Al₂O₃ catalyst has a smaller mean metal particle size and a narrower particle size distribution than a similar catalyst prepared by a traditional wet impregnation from the same RuCl₃ precursor.