The complexity of dispersed sulfide catalysts has hindered establishingunequivocal structure activity relationships during catalytic action despitegroundbreaking results with model catalysts. The present contribution investigatesthe hydrogenation of phenanthrene as a model compound to characterize activessites of Ni-promoted MoS2/?-Al2O3 catalysts. Detailedkinetic informations were obtained at 573-623 K and 60 bar H2 in atrickle bed reactor. The physicochemical properties of the catalysts wereextensively characterized combining in situspectroscopic characterization of surface structure and acidity with probemolecules (CO, 4,6-dimethylpyridine) and X-ray absorption spectroscopy. Theaddition of Ni to MoS2/?-Al2O3 increases theconversion rates and shifts the selectivity towards more saturated products. Theobserved increase of the reactivity is related to a higher rate of H2activation, a higher steady state concentration of SH groups at the edges ofthe slabs and a higher adsorption constant of the adsorbed aromatic moleculeson Ni-decorated sites at the edges of MoS2 slabs. The reactivity ofthe SH groups and concentration study allows to quantitatively understand andpredict catalyst performance. Potential and limitations to improve thesecatalysts for hydrogenation will be discussed.

Active sites for hydrogenation of aromatic hydrocarbons on Ni-Mo sulfides

248th National Meeting (2014)

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