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Article Dans Une Revue Journal of Catalysis Année : 2012

Deoxygenation mechanisms on Ni-promoted MoS2 bulk catalysts: A combined experimental and theoretical study

M. R. de Brimont
  • Fonction : Auteur
Celine Dupont
A. Daudin
  • Fonction : Auteur
C. Geantet
Pascal Raybaud

Résumé

Through a combined experimental and density functional study, we investigate the deoxygenation of ethyl heptanoate catalyzed by three relevant unsupported (bulk) transition metal sulfide catalysts: MoS2, Ni3S2 and Ni-promoted MoS2 (with various Ni/Mo ratio). Two pathways compete for this reaction: hydrodeoxygenation (HDO) and decarboxylation/decarbonylation (DCO). It is shown experimentally that the presence of Ni either in the NiMoS mixed phase or in the Ni monosulfide phase may change the selectivity between the HDO and DCO pathway. To understand the origin of this selectivity, we study the deoxygenation pathways of two relevant intermediates: carboxylic acid and aldehyde. In particular, DFT calculations highlight that the aldehyde decarbonylation occurs via its dehydrogenation into the alkanoyl and/or ketene intermediates on the Ni3S2 (111) surface. These pathways are found to be more favorable on Ni3S2 than on MoS2-based catalysts. This trend is explained by the presence of Ni-3 triangular facets on Ni3S2 (111) enhancing the formation of the unsaturated alkanoyl and/or ketene intermediates as well as the CO product. We finally propose a detailed analysis of the promoting effect of Ni on MoS2, when present in the NiMoS structure. (C) 2011 Elsevier Inc. All rights reserved.

Dates et versions

hal-00700172 , version 1 (22-05-2012)

Identifiants

Citer

M. R. de Brimont, Celine Dupont, A. Daudin, C. Geantet, Pascal Raybaud. Deoxygenation mechanisms on Ni-promoted MoS2 bulk catalysts: A combined experimental and theoretical study. Journal of Catalysis, 2012, 286, pp.153-164. ⟨10.1016/j.jcat.2011.10.022⟩. ⟨hal-00700172⟩
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