Performance of NiMoS/Al2O3 prepared by sonochemical and chemical vapor deposition methods in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

Abstract

Different types of NiMoS/Al₂O₃ catalysts were prepared by a combination of sonochemical synthesis and chemical vapor deposition (CVD) methods. The performance of the prepared catalysts in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was compared with that of catalysts prepared using the impregnation method. Ni that was selectively added to the MoS₂ surface by CVD promoted the HDS activity to a greater extent than Ni added by impregnation, particularly for the direct-desulfurization (DDS) route of the reaction. This was attributed to the former method allowing an intimate interaction between the added Ni and the MoS₂ surface, as confirmed by the XPS analysis of the catalysts. NiMoS/Al₂O₃ prepared by a combination of two methods, sonochemical and CVD, showed improvement in activity over the catalyst prepared by impregnation. Moreover, the hydrogenation (HYD) activity of the former catalyst was significantly higher than that of the latter due to the dominant effect of sonochemical synthesis on the activity. The improvement in activity was greater for the HDS of 4,6-DMDBT than for the HDS of DBT.