The removal of sulfur from petroleum fractions is receiving increasing interest due to new environmental legislation requiring the further reduction of sulfur content. Hydrodesulfurization process is the most used method for removal of sulfur component. Traditional hydrodesulfurization catalysts are Mo or W (sulfided state) supported on alumina and in some cases promoted by Ni or Co. However, these catalysts are unable to achieve the deep hydrodesulfurization and there is a need for working on more active catalysts. It can be noted that for deep desulfurization of gasoline and other petroleum fractions, the employed catalysts performance can be improved by different methods. It can be carried out by increasing of active sites by using catalyst modifiers. Two of the efficient candidates in literature are fluorine and phosphorous. Different methods have been reported for the preparation of Mo sulfide nanoparticles. However, the use of ultrasonic irradiation have been proven to be an effective way for synthesis of these catalysts. For achievement of suitable catalyst for HDS process, this research was planed in Reactor and Catalysis Research Center of Sahand University of technology. At first, in this research a series of nanocatalysts promoted by fluorine and phosphorous have been synthesized via impregnation and ultrasonic techniques.

The results obtained from XRD, FESEM, BET and FTIR analysis showed that preparation method and second promoter have a great influence on the physicochemical properties of catalyst such as specific surface area and morphology. Consequently, activity tests, in hydrodesulfurization process (using thiophene as a model sulfur component in fractional petroleum) showed that concentration of unreactant thiophene decrease when using of secondary promoter and ultrasound method. In impregnation method activity of promoted CoMo/Al2O3 catalyst by fluorine was higher than NiMo/Al2O3.