SELECTIVE HYDRODESULFURIZATION OF 4,6-DIMETHYL DIBENZOTHIOPHENE IN THE MAJOR PRESENCE OF NAPHTHA LENE OVER MOLYBDENUM BASED BINARY AND TERTIARY SULFIDES CATALYSTS

摘要

It has been clarified in previous papers that the sufficient desulfurization of the refractory sulfur species in the diesel fuel such as 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene (4,6-DMDBT) should be achieved in its sulfur level of 0.05 % which is currently regulated. Such refractory species have been proved to be de-sulfurized through the hydrogenation of one or both phenyl rings in the substrate to moderate the steric hindrance of methyl groups located in the neighbours of the sulfur atom. Hydrogenation of neighboring phenyl rings should competitive with the aromatic partners in the hydrogenation step, being severely hindered. The diesel fuel tends to be more aromatic due to crude of more aromaticity and more blending of the craked oil.In the present study, the catalytic activities of CoMo and NiMo of different contents of Co or Ni and Ru-CoMo / Al_2O_3 were examined for the desulfurization of 4,6-DM-DBT in decane and decane with naphthalene to find selective catalysts which desulfurize 4,6-DMDBT in the presence of naphthalene through preferential hydrogenation through its phenyl ring. The key step is assumed to be the hydrogenation step of 4,6-DMDBT in the competition with naphthalene. Ru was the selected as the third component of metal promoter which was added to CoMo / Al_2O_3, since sulfur atom in 4,6-DMDBT can be a prefereable anchor to the nobel metal sulfide in competition with the aromatic hydrocarbon. Characterization of Ru-CoMo / Al_2O_3 using XPS, XRD and HR-EM to find the origin of the selectivity for the desulfurization in the aromatic hydrocarbons.