Xiaoliang Ma

Deep hydrodesulfurization of diesel fuel: Design of reaction process and catalysts

Abstract Deep hydrodesulfurization (HDS) of diesel fuel oil was designed based on the recognition that alkyl dibenzothiophenes such as 4-methyl-and 4,6-dimethyldibenzothiophenes were the main target for deep HDS. Multi-stage and fractional HDS were very effective to achieve satisfactory HDS in terms of both sulfur level and fluorescent color of desulfurized oil. Catalysts with the selective hydrogenation of refractory sulfur species in major aromatic partners and isomerization-disproportionation of their alkyl groups prior to HDS were also designed to promote the desulfurization of such sulfur species.

Determination of sulfur compounds in non-polar fraction of vacuum gas oil

Abstract Sulfur compounds in the non-polar fraction, which represents 73 wt% of total sulfur in a vacuum gas oil (VGO), were analysed by sulfur-selective ligand exchange chromatography combined with high-performance liquid chromatographic (h.p.l.c.) separation on the basis of aromatic ring number, with subsequent capillary g.c.-mass spectrometry for identification. Quantification was achieved by independent h.p.l.c. separation based on aromatic ring number followed by capillary gas chromatography with a sulfur-selective flame photometric detector. These methods were very effective in isolating the sulfur compounds from complex mixtures of high-boiling hydrocarbon compounds and for separating the sulfur compounds according to aromatic ring number. The structures and concentrations of > 100 sulfur compounds in the non-polar fraction of the VGO were determined Alkyl benzo[b]thiophenes, dibenzo[b,d]thiophenes, benzonaphthothiophenes and phenanthro[4,5-b,c,d]thiophenes were found to be major sulfur species existing in the non-polar fraction of the VGO.

Three-stage deep hydrodesulfurization and decolorization of diesel fuel with CoMo and NiMo catalysts at relatively low pressure

Three-stage deep desulfurization of diesel fuel was performed using CoMo in the first stage and NiMo in the other two stages under H2 at 2.9 M Pa. The first and second stages were carried out at higher temperature for sufficient desulfurization of benzothiophenes and dibenzothiophenes respectively, and the third stage was carried out at lower temperature to remove the fluorescent colour from the desulfurized oil. A sulfur content of < 200 ppmw was achieved as well as decolorization. The influence of the reaction conditions in the different stages on hydrodesulfurization and fluorescent colour development and removal were examined in detail.

Catalytic activities of NiMo and CoMoAl2O3 of variable Ni and Co contents for the hydrodesulfurization of 4,6-dimethyldibenzothiophene in the presence of naphthalene

Abstract The catalytic activities of NiMo Al 2 O 3 and CoMo Al 2 O 3 with a variable content of Ni and Co, respectively, were examined for the hydrodesulfurization (HDS) of refractory sulfur species, 4,6-dimethyldibenzothiophene (4,6-DMDBT), in decane with naphthalene. Naphthalene of 10 wt.−% severely retarded the HDS of 4,6-DMDBT over the series of NiMo catalysts. Hydrogenation of naphthalene dominated over the series of NiMo catalysts, suppressing the HDS of 4,6-DMDBT over the catalysts. CoMo catalysts were superior to the NiMo catalysts for the HDS activities of 4,6-DMDBT with less retardation of the aromatic partner, providing the highest activity at Co content of 1 wt.−% in 15 wt.−% of Mo, although the former catalysts were inferior to the latter ones for the hydrogenation activities of the aromatic partner. The valence states of metals were observed by X-ray photoelectron spectra (XPS) to discuss the active sites for the hydrogenation especially selective to the sulfur species.