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Palladium-platinum powder catalysts manufactured by colloid synthesis
- Source :
- Journal of Molecular Catalysis A: Chemical. 238:56-62
- Publication Year :
- 2005
- Publisher :
- Elsevier BV, 2005.
-
Abstract
- Unsupported Pd, Pt and PdPt bimetallic catalysts were prepared in different atomic ratios using methods of colloid chemistry. They were characterized by XPS, UPS and TEM. Four subsequent treatments with O2 and H2 up to T = 603 K were applied in the preparation chamber of the electron spectrometer and before the catalytic runs. Platinum strongly hindered the oxidation of palladium in the bimetallic samples indicating an alloying of the two components. The H2 treatment after O2 led to rather clean metals. These treatments up to 603 K decreased the Pt enrichment near to the surface found by XPS, destroying presumably the Pt islands on the surface of a Pd-rich matrix. The particle composition approached thus a homogeneous metal mixture. The catalytic behavior was tested in the hydrogenative ring opening reaction of cis- and trans-methyl-ethylcyclopropane (MECP) at 373 K. The product ratios 2-methylpentane/3-methylpentane (2MP/3MP) and 2-methylpentane/n-hexane (2MP/nH) were used to characterize the ring-opening pattern of the samples. The bimetallic catalysts revealed higher activity and completely different selectivities than the monometallic Pt and Pd. Moreover, the 2MP/3MP ratio from trans-MECP and 2MP/nH ratio from cis-MECP increased as the surface Pt enrichment decreased. PdPt catalysts were cleaner than Pd or Pt, their activity higher and selectivity closer to random C–C rupture, due, very likely, to the presence of active Pd–Pt ensembles.
- Subjects :
- Chemistry
Process Chemistry and Technology
Inorganic chemistry
chemistry.chemical_element
Nanoparticle
Heterogeneous catalysis
Catalysis
Metal
Colloid
Transition metal
X-ray photoelectron spectroscopy
visual_art
visual_art.visual_art_medium
Particle size
Physical and Theoretical Chemistry
Platinum
Bimetallic strip
Palladium
Subjects
Details
- ISSN :
- 13811169
- Volume :
- 238
- Database :
- OpenAIRE
- Journal :
- Journal of Molecular Catalysis A: Chemical
- Accession number :
- edsair.doi.dedup.....d5adc208d49950dc0c44955cd1c7b6de