fulltext.study @t Gmail

Synthesis of highly dispersed palladium alumina supported particles: Influence of the particle surface density on physico-chemical properties

Paper ID Volume ID Publish Year Pages File Format Full-Text
44588 46044 2006 11 PDF Available
Title
Synthesis of highly dispersed palladium alumina supported particles: Influence of the particle surface density on physico-chemical properties
Abstract

Complexation with nitrite ions in aqueous medium was used to prepare highly dispersed Pd° particles supported on alumina. It has been possible to obtain catalysts with different Pd loading keeping the particle size lower than 1 nm as shown by HRTEM, chemisorption, or extended X-ray absorption fine structure (EXAFS) characterizations, and as a consequence with different particle surface density. We observed that electronic properties measured by IR(CO) or X-ray photoelectron spectroscopy (XPS) measurements are strongly influenced by this last parameter and that the origin of these variations can be related to the different strengths of the interactions of the palladium precursor with the alumina surface sites as shown by low temperature CO adsorption followed by FTIR spectroscopy. On increasing Pd loading, saturation of unsaturated Lewis surface sites follows their acid strength: the more acidic ones are the first to react as germination sites, followed by the medium and finally the weaker sites. These different interactions may explain the variation of electronic properties of such small reduced particles which appears to be very sensitive to the chemical nature of their initial germination site on the oxide support. On the other hand, no such effects were observed on changing the type of alumina (δ or γ) support, in agreement with the principle of the synthesis method which tends to limit strong interaction with the support. Comparison with Pd° particles with the same particle size and particle surface density but prepared with the well known grafting of acetylacetonate precursor shows marked differences in terms of electronic properties followed by CO FTIR. This result illustrates the possibility to prepare highly dispersed Pd particles with different physico-chemical properties.

Keywords
Palladium; Heterogeneous catalyst preparation; Nano particles; Alumina; Particle surface density
First Page Preview
Synthesis of highly dispersed palladium alumina supported particles: Influence of the particle surface density on physico-chemical properties
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 312, 8 September 2006, Pages 1–11
Authors
, , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us