| With world high-quality crude oil reserves being depleted, the crude oil reserves have a trend of becoming heavier and degraded. On the other hand, in order to alleviate oil shortages, the coal tars, shale oils and oil sand asphalts are considered as potential supplements of crude oils. However, the coal tars, shale oils and oil sand asphalts contain large amounts of aromatics. Excessive aromatics not only lower the combustibility of fuels, but also produce hazardous particulates and cause environmental pollution. Hence, deeply removing aromatics has become increasingly important. Hydrodearomatization (HDA) is the most effective way to remove aromatics. Petroleum industry today mostly uses the transition metal sulfide catalysts, but the activity of this type of catalyst is too low to adapt for deeply removing large quantities of polynuclear aromatics. Noble metal catalysts have high HDA activities, but they are liable to be poisoned by sulfides in liquid fuels. As a result, the new catalyst which has higher HDA activity must be developed; also, the sulfur resistance of noble metal must be improved. On the other hand, although there are a lot of research works about the effects of S-containing compounds on hydrogenation and HDA, the research works about the effects of N-containing compounds on HDA and catalyst are rare. In order to solve these problems, naphthalene andα/β-methylnaphthalene were chosen as the model compounds of liquid fuels. The new catalytic material nickel phosphide was applied in hydrogenation of the aromatics which were mentioned previously, the HDA activity of nickel phosphide was studied; the reaction mechanism and the effects of N-containing compound (quinoline) on catalyst were investigated, too. The catalysts were characterized by XRD, TEM, N2 adsorption, CO chemisorption, Py-IR, and XPS. A series of Pd-Pt bimetallic catalysts with different Pd/Pt molar ratios were prepared, and the relationship between Pd/Pt molar ratio and catalyst's sulfur resistance was studied. The main contents and results are as follows:A series of Ni2P/SiO2 catalysts with different Ni/P molar ratio and loading in the oxidic precursors were prepared by an in-situ reduction method. Their catalytic performances were evaluated in aromatics hydrogenation. The optimal initial Ni/P ratio is 1.25 and the optimal loading of NiO and P2O5 is 30 wt%. On this catalyst, the naphthalene conversion is up to 100%, the selectivity to decalin is up to 92.1%; theα/β-methylnaphthalene conversions are up to 96.0% and 99.0%, the selectivity to 1-methyldecalin and 2-methyldecalin are up to 27.0% and 82.6%. These values are all higher than those on sulfided Ni-W catalyst. The reaction rate constant of naphthalene yield tetralin k1 is 0.80 min-1, the reaction rate constant of tetralin yield decalin k2 is 0.84 min-1, the ratio of k1/k2 is 0.95. Cis-decalin can be isomerized to trans-decalin on active sites of Ni2P/SiO2.The competitive adsorptions ofα-andβ-methylnaphthalene hinder naphthalene hydrogenation, and naphthalene has negligible effects onα/β-methylnaphthalene hydrogenation. The adsorptive capacities ofα-andβ-methylnaphthalene are far higher than that of naphthalene, and the adsorptive capacity ofα-methylnaphthalene is a little higher than that ofβ-methylnaphthalene. Quinoline and its hydrogenation intermediate products hinder naphthalene hydrogenation, while naphthalene hinders tetrahydroquinoline yielding decahydroquinoline. The addition of dibenzothiophene leads to a decline of naphthalene conversion, which may be attributed to irreversible adsorption of S on catalyst surface.Bimetallic Pd-Pt (Pd:Pt=1:1;1:4;4:1) catalysts supported on SiO2-Al2O3 were prepared by immersion method. Their hydrogenation activities and sulfur resistances were analyzed and compared. Results showed that, the Pd-Pt (Pd:Pt=4:1) catalyst showed the highest activity and selectivity to full hydrogenation products. On this catalyst, the naphthalene conversion and selectivity to decalin are up to 98.2% and 93.6%, respectively,α-andβ-methylnaphthalene conversions are up to 97.5% and 98.2%, the selectivity to 1-methyldecalin and 2-methyldecalin are up to 18.5% and 73.0%. The order of naphthalene hydrogenation rate on Pd, Pt and Pd-Pt (Pd:Pt=4:1) follow the sequence:υPd-Pt(4:1)>υPd>υPt. The hydrogenation activity of Pd-Pt (Pd:Pt=4:1) catalyst is still the highest in the presence of dibenzothiophene.
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