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Dendrimer templates for heterogeneous catalysts: Bimetallic Pt–Au nanoparticles on oxide supports

Paper ID Volume ID Publish Year Pages File Format Full-Text
48375 46504 2008 11 PDF Available
Title
Dendrimer templates for heterogeneous catalysts: Bimetallic Pt–Au nanoparticles on oxide supports
Abstract

Polyamidoamine (PAMAM) dendrimers were used to template Pt, Au, and bimetallic Pt–Au dendrimer encapsulated nanoparticles (DENs) in solution. Adjusting the solution pH allowed for slow, spontaneous adsorption of the nanoparticles onto silica, alumina, and titania. After dendrimer removal, the catalysts were characterized with infrared spectroscopy of adsorbed CO and tested with CO oxidation catalysis. Infrared spectroscopy of the monometallic Pt catalysts showed a slight shift in the CO stretching frequency for the different supports. For the bimetallic catalysts, infrared spectra showed CO adsorbed on both Pt and on Au sites. Spectra collected during CO desorption showed substantial interactions between the two bands, confirming the presence of bimetallic particles on all the supports. The bimetallic catalysts were found to be more active than the monometallic catalysts and had lower apparent activation energies. The titania supported Pt–Au catalyst was resistant to deactivation during an extended treatment at 300 °C. Correlations between IR spectra and catalytic activity showed differences between the mono- and bimetallic materials and implicated a bimetallic Pt–Au ensemble at the catalytic active site. This is the first study to show that DENs are appropriate precursors for studying support effects on catalysis by metal nanoparticles, although the magnitude of the effects were small.

Keywords
Catalyst preparation; Dendrimer encapsulated nanoparticles; PAMAM dendrimers; Pt catalysts; Au catalysts; Pt–Au catalysts; Bimetallic catalysts; CO adsorption; Infrared spectroscopy of adsorbed CO; Nanoparticle preparation; Support effects
First Page Preview
Dendrimer templates for heterogeneous catalysts: Bimetallic Pt–Au nanoparticles on oxide supports
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 81, Issues 3–4, 24 June 2008, Pages 225–235
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis