CATALYTIC ACTIVITIES OF NIMO AND COMO AL2O3 OF VARIABLE NI AND CO CONTENTS FOR THE HYDRODESULFURIZATION OF 4,6-DIMETHYLDIBENZOTHIOPHENE IN THE PRESENCE OF NAPHTHALENE/

The catalytic activities of NiMo/Al2O3 and CoMo/Al2O3 with a variable content of Ni and Co, respectively, were examined for the hydrodesulfu rization (HDS) of refractory sulfur species, 4,6-dimethyldibenzothioph ene (4,6-DMDBT), in decane with naphthalene. Naphthalene of 10 wt.-% s everely retarded the HDS of 4,6-DMDBT over the series of NiMo catalyst s. Hydrogenation of naphthalene dominated over the series of NiMo cata lysts, suppressing the HDS of 4,6-DMDBT over the catalysts. CoMo catal ysts were superior to the NiMo catalysts for the HDS activities of 4,6 -DMDBT with less retardation of the aromatic partner, providing the hi ghest activity at Co content of 1 wt.-% in 15 wt.-% of Mo, although th e former catalysts were inferior to the latter ones for the hydrogenat ion activities of the aromatic partner. The valence states of metals w ere observed by X-ray photoelectron spectra (XPS) to discuss the activ e sites for the hydrogenation especially selective to the sulfur speci es.