HYDROGENATION OF OLEFINS ON A MOS2/GAMMA-AL2O3 CATALYST - ROLE OF P, F AND ALKALINE CATION ADDITIVES

The reactivity of mono- and di-olefins has been studied on a MoS2-gamma-Al2O3 hydroprocessing catalyst pretreated under H-2 at various temperatures. The conjugable or hindered di-olefins are less reactive than the conjugated homologous molecules. Dienes were however much more reactive than monoethylenic compounds. In presence of additives (i.e. P, F and alkaline cations), the activities and selectivities of diene hydrogenations were found to depend on the nature and concentration of the additive. In general, the overall hydrogenation activities are in the order Mo > Mo-Na > Mo-P > Mo-Cs > Mo-F. The change in the product distribution (selectivities in mono/dihydrogenation and hydrogenation/isomerization) suggests that some of the additive acts directly on the active sites of the MoS, phase by poisoning and/or hy blocking the labile sulfur removal during the activation treatment under H-2.