ABSTRACT
A conventional Μο82/γ-Α120 3 hydroprocessing catalyst has been tested in hydrogenation of conjugated dienes and of toluene and in hydrodenitrogenation of pyridine to probe the influence of elements like phosphorus, fluorine or alkaline ions added into the catalyst formulation. The activity depends on the nature and concentration of the additive and also on the temperature (TR) at which the catalysts have been submitted to hydrogen after sulfidation but prior the tests for creating coordinative unsaturated sites
(CUS). The results suggest that the additives directly interact with the MoS2 supported phase by poisoning the sites and/or by blocking the labile sulfur species which are progressively removed during the activation pretreatment under H2. As a consequence, the studied additives influence both the local structure of the sites of the MoS2 phase as well as their number.
