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Structure and Catalytic Properties of Nano-Sized Alumina Supported Platinum and Palladium Particles Synthesized by Reaction in Microemulsion

Masatomo Yashima ; Lena K. L. Falk (Institutionen för experimentell fysik, Mikroskopi och mikroanalys) ; Anders Palmqvist (Institutionen för material- och ytkemi, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Krister Holmberg (Institutionen för material- och ytkemi, Teknisk ytkemi ; Kompetenscentrum katalys (KCK))
Journal of Colloid and Interface Science (0021-9797). Vol. 268 (2003), 2, p. 348-356.
[Artikel, refereegranskad vetenskaplig]

Mixtures of nanosized platinum and palladium particles have been prepared by reduction of salt-containing microemulsion droplets using hydrazine as the reducing agent. To avoid possible negative effects of the presence of sulfur compounds during the preparation the microemulsion was made using the sulfur-free nonionic polyoxyethylene 4 lauryl ether surfactant. Transmission electron microscopy showed that the as-prepared mixtures contained crystalline platinum particles of fairly homogeneous size (20 to 40 nm) with adsorbed amorphous palladium particles 2 to 5 nm in size. Catalyst samples were prepared by depositing the nanoparticles on a γ-Al2O3 support followed by heating in air at 600 °C. Alloyed particles of platinum and palladium with sizes ranging from 5 to 80 nm were obtained during the heating. The majority of the particles had the fcc structure and their compositional range was dependent upon the Pt:Pd molar ratio of the microemulsion. A catalyst prepared from a microemulsion with a 20:80 Pt:Pd molar ratio showed the highest catalytic activity for CO oxidation, while pure platinum and palladium catalysts showed higher sulfur resistance. These results differ from the performance of conventional wet-impregnated catalysts, where a 50:50 Pt:Pd molar ratio resulted in the highest catalytic activity as well as the highest sulfur resistance.

Nyckelord: Microemulsion; Alloyed nanoparticles; Platinum; Palladium; Catalysis; Electron microscopy; CO oxidation; Catalyst preparation; Nanoparticle synthesis



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Denna post skapades 2011-01-15. Senast ändrad 2016-10-03.
CPL Pubid: 134024

 

Institutioner (Chalmers)

Institutionen för experimentell fysik, Mikroskopi och mikroanalys (1997-2004)
Institutionen för material- och ytkemi, Teknisk ytkemi (2002-2004)
Kompetenscentrum katalys (KCK)

Ämnesområden

Materialvetenskap
Nanovetenskap och nanoteknik
Hållbar utveckling
Yt- och kolloidkemi
Oorganisk kemi

Chalmers infrastruktur