Study On Unsupported Metal Sulfide Catalysts

With the increasing enhancement requirement of environmental protection, there are moreand more strict with sulfur content in diesel oil in countries around the world, the deepdesulfurization of diesel oil has become urgently request for enterprises. Production of lowsulfur clean or ultraclean diesel can effectively reduce the sulfur content of exhaust emissionand sulfur concentration of pollutants in the atmosphere, so as to reduce environmentalprotection pressure caused by the increasing demands of diesel oil.Hydordesulfurization(HDS) is still the key to produce the high quality fuel with low sulfurcontent. Hydrogenation catalyst is the kernel of the hydrodesulfurization process. In the work,two kinds of unsupported MoS2hydrodesulfurization catalysts and their precursor, nano-sizedMoO3, were synthesized using a novel hydrothermal reduction method mainly, as well asprecursor Co3O4, and the bimetallic CoMo sulfide catalyst was synthesized preliminarily.Infrared spectroscopy was employed to characterize the compounds and the structure of thecatalysts; X-ray diffraction was utilized to ascertain the structure of the catalysts; N2-physicaladsorption-desorption was used to determine the specific surface area and mean particle sizeof the catalysts; additionally, the morphology catalysts were investigated by SEM and TEM;the composition distribution was also examined using EDS. The influences of hydrothermaltreatment temperature, reaction time, and pH value of reactants on the growth morphology ofMoO3、MoS2and Co3O4were systematically investigated. The hydrogenation desulfurizationperformance of unsupported molybdenum sulfide catalysts was evaluated by takingdibenzothiophene (DBT) as model compounds on a high-pressure micro reactor. Finally thehydrogenation desulfurization effects of the reaction temperature and reaction pressure wereinvestigated. The experimental results showed that the best hydrodesulfurization reactionconditions were as follow for the MoS2-A1sample:360℃of temperature,6.0MPa ofpressure,600of ratio of hydrogen to oil (volume ratio),2.0h-1of LHSV. Under this condition,the desulfurization rate reached78.23%.