Metal nanoparticles have received much interest for their application in catalysis due to high surface-to-volume ratios resulting in more available active sites. Ideally these catalysts are heterogeneous and allow for facile separation from the catalytic reaction mixture making them ideal for industrial application. Dispersed metal nanoparticles are explored due to their high reactivity in solution and are stabilized by surfactants and polymers. However, it is difficult to determine whether or not a catalyst is truly heterogeneous as a certain degree of leaching from the metal nanoparticle is inevitable. Determining the mechanisms involved in nanocatalysis is also a challenge. In this study, a series of dispersed palladium nanocatalysts in the Suzuki reaction with phenylboronic acid and bromobenzene were characterized before and after catalysis to determine what changes occur. Samples where characterized before and after the catalytic reaction by XPS, SEM, and EDS to monitor changes in particle size and composition. Reaction mixtures after catalysis were analyzed by ICP-MS for leached palladium species to determine if concentrations were high enough for homogeneous catalysis to take place. The dispersed palladium nanoparticles studied experienced growth during the catalytic process and a significant amount of leaching. XPS analysis indicates the presence of aromatic species on the particle surface after the catalytic reaction. The aromatic species is likely biphenyl, the product of the catalytic reaction, as the presence of boron and bromine was not found in XPS and EDS analysis.
| Identifer | oai:union.ndltd.org:vcu.edu/oai:scholarscompass.vcu.edu:etd-3200 |
| Date | 09 June 2010 |
| Creators | Broderick, Meghann |
| Publisher | VCU Scholars Compass |
| Source Sets | Virginia Commonwealth University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | © The Author |
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