Authors: Cécile Thomazeau Tivadar Cseri Laure Bisson Julie Aguilhon Doan Pham Minh Cédric Boissière Olivier Durupthy Clément Sanchez
Publish Date: 2012/08/02
Volume: 55, Issue: 11-13, Pages: 690-699
Abstract
In the field of catalysis by metals a new insight for the nanodesign of supported heterogeneous catalysts is the tailoring of metallic nanoparticles In this work wellfaceted monometallic nanoparticles Pd Pt Ni exposing mostly the 111 crystallographic facet are obtained in aqueous solution and are deposited on an alumina support The involved mechanisms of nanoparticles formation are determined and are evidenced to be different as a function of the nature of the metal In the case of palladium the mechanism consists in an oriented attachment of palladium nanoparticles leading to the energetically most favourable stacking of nanoparticles at the origin of the early differentiation of the nanoparticles shapes and of the formation of the wellfaceted palladium nanoparticles In the case of platinum the mechanism seems to be a combination of aggregation of already reduced nuclei and direct reduction depending on the experimental conditions In the case of the less reductible metal nickel wellfaceted nanoparticles are not obtained during the synthesis and only a thermal activation under hydrogen can engender their formation The impact of the 111 crystallographic facet for platinum and nickel is very important and induces a drastic increase of selectivity towards olefins formation with a selectivity close to the one of a palladium catalyst which is the most selective metal for the selective hydrogenation of polyunsaturated hydrocarbons
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