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Palladium Carbide Formation in Pd/C Catalysts and its Effect on Adsorption, Absorption and Catalytic Behavior

Published online by Cambridge University Press:  15 February 2011

Nalini Krishnankutty  and
M. A. Vannice
Nalini Krishnankutty
Affiliation:
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802 (Current Address: Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802)
M. A. Vannice
Affiliation:
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802
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Abstract

The presence of PdCx, a metastable palladium carbide phase, was detected in Pd dispersed on high surface area carbon blacks using a Pd acetylacetonate precursor. TEM and XRD measurements indicated well dispersed Pd after reduction at 573 K; however, hydride formation and chemisorption of gases was suppressed on these catalysts and this was accompanied by lattice expansion of Pd as seen from XRD. Cleaning pretreatments with O2 slightly contracted the Pd lattice and enhanced hydride formation and chemisorption, while a 673 K reduction gave normal hydride ratios and Pd lattice parameters although chemisorption was still suppressed. Pd lattice expansion and suppression of hydride formation and chemisorption are attributed to carbon atoms present both in the bulk and on the Pd surface. The performance of these catalysts in probe reactions was consistent with this model of C contamination of the Pd surface and bulk.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 368: Symposium T – Synthesis and Properties of Advanced Catalytic Materials , 1994 , 81
Copyright
Copyright © Materials Research Society 1995

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References

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