Bimetallic Au-Pd and Ag-Pd Clusters Synthesised by $\gamma $ or Electron Beam Radiolysis and Study of the Reactivity/Structure Relationships in the Selective Hydrogenation of Buta-1,3-Diene

Abstract

Résumé -Agrégats bimétalliques Au-Pd et Ag-Pd synthétisés par réduction radiolytique : étude des relations réactivité/structure en hydrogénation sélective du buta-1,3-diène -Des catalyseurs Ag-Pd et Au-Pd (sous forme d'alliage ou de structure coeur-coquille) ont été synthétisés par réduction radiolytique (rayons gamma ou faisceau d'électrons). L'étude de l'hydrogénation sélective de buta-1,3-diène par ces différents nanoagrégats déposés sur alumine a permis de déterminer les effets de la composition et de la structure sur les performances catalytiques. Les nanoagrégats Au-Pd et Ag-Pd montrent des propriétés catalytiques très différentes : alors que l'activité en hydrogénation est modifiée dans des systèmes Au-Pd sans changement de sélectivité dans la formation des butènes, d'importantes variations de sélectivité sont observées pour les nanoagrégats Ag-Pd déposés sur alumine. Abstract -Bimetallic Au-Pd and Ag-Pd Clusters Synthesised by γ γ or Electron Beam Radiolysis and

Synthesis of Au–Pd bimetallic nanoparticles under energetic irradiation fields

“…The scale bar in conventional TEM images is irradiation such as g-ray irradiation (40 Gy/min). This trend is quite similar to the results for the irradiation-synthesized Au-Pt, Au-Pd systems, which have been reported by (Remita et al, 2003(Remita et al, , 2005Redjala et al, 2006). In case of low dose rate irradiation, as the reduction rate is very small, the growth of nanoparticles tends to occur easily.…”

“…Through the transmission electron microscope (TEM) observation and ultraviolet-visible (UV-vis) measurements, Remita et al (2003Remita et al ( , 2005 have already reported the synthesis of bimetallic nanoparticles such as Au-Pt, Au-Pd, and so on in various kinds of irradiation fields. They have concluded that the dose rate is an important factor to control the particle size and structures (Remita et al, 2003(Remita et al, , 2005Redjala et al, 2006). To study the dose rate effect on the size and structure of irradiationsynthesized nanoparticles more clearly, we made annular darkfield scanning transmission electron microscopy (ADF-STEM) observations with energy-dispersive X-ray spectroscopy (EDS) measurements for Au-Pd nanoparticles synthesized for various kinds of irradiation as well as conventional transmission electron microscope observations and ultraviolet-visible measurements.…”

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

“…With the Ag-promoted catalysts, C 1 and C 5 + selectivities were slightly improved at all loadings [28]. Thus, the presence of a weakly hydrogenating metal [29], Ag, did not adversely affect selectivity to a significant degree, even when excessive amounts of promoter were added [28].…”

Chemical Preparation of Supported Bimetallic Catalysts. Gold-Based Bimetallic, a Case Study

“…Au-Pd nanoparticles were produced by radiolysis, then adsorbed on an alumina support [98]. The aqueous solution containing HAuCl 4 and Pd(NO 3 ) 2 was irradiated under a N 2 atmosphere in the presence of PVA as stabilizing agent and of 2-propanol as scavenger of oxidizing OH‚ radicals.…”