Study of the influence of organic ligands on the reactivity of gold nanoparticles

Abstract

Metal nanoparticles have received great attention in catalysis due to new reactivity, often not seen in the corresponding bulk materials, and high selectivity in catalytic reactions. In general, gold catalysts have been most studied for its excellent selectivity in oxidation reactions, but this metal at nanoscale has unique properties that can be exploited in a number of other reactions. The preparation of metallic nanoparticles generally involves three basic components: a metal precursor, a reducing agent and a stabilizer. The stabilizer is generally an organic molecule, which has the function of stopping the growth process of the nanoparticles, allowing the size control, but it adsorbs on the surface of the material. The interaction of the stabilizer with the metal nanoparticle certainly plays a very important role for applications in catalysis, as well as other processes involving ligands that can activate or poison the metal surfaces. Ligands are known as selectivity enhancers in classical heterogeneous catalysis (blocking non-selective sites), but rarely used as promoters to increase activity. Very little has been studied to date on the role of organic ligands used in the preparation of gold nanoparticles for applications in catalysis, and even less about possible effects of adding organic promoters. In this research project, we will study the catalytic activity of supported gold nanoparticles and the activation and deactivation processes involving adsorbed ligands on their surfaces. We hope that these ligands can stimulate new reactivity and selectivity in industrially interesting reactions, such as catalytic hydrogenations. (AU)