Hydrogenation of aromatics over supported noble metal catalysts ex organometallic complexes

In the present work, organometallic complexes were used as metal precursors for the synthesis of sulphur-resistant noble metal catalysts. The catalysts were tested in the hydrogenation reaction of diesel model-type molecules. Dibenzothiophene (DBT) was used as the source of sulphur. The organometallic-based catalysts activity was compared with the activity displayed by a commercial Pt/Al2O3 hydrogenation catalyst. Comparable activity results were obtained when the reaction was carried in the presence of sulphur containing molecules. However, the organometallic-based catalysts were only active once the ligands had been removed from the metal coordination sphere, thus allowing the reactant molecules to adsorb on the metallic surface centres. Accordingly, the major advantage of this methodology may lie in improved metallic dispersion, which will be reflected in catalysts with greater sulphur resistance, rather than in the electronic or steric effects ascribed to organometallic precursors. (C) 2003 Published by Elsevier B.V.