HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF PHOSPHORUS-CONTAINING MOS2/AL2O3 HYDROTREATING CATALYSTS

A series of sulfided molybdenum catalysts supported on alumina and modified with various amounts of phosphorus, previous or simultaneously to the molybdenum impregnation, has been studied by high resolution transmission electron microscopy. The results show that the addition of phosphorus (P2O5 > 4 wt.- %) to the catalysts with low molybdenum content (8 wt.-% MoS2) promotes the formation of single and double layered MoS2 when the phosphorus and the molybdenum are impregnated simultaneously. In contrast, the addition of phosphorus previous to the molybdenum impregnation leads to higher stacking of the MoS2 crystallites and promotes the formation of partially sulfided MoO3 particles. In catalysts with high molybdenum content (14 wt.-% MoO3), phosphorus addition prevents the agglomeration of the MoS2 particles induced by high sulfiding temperature.