| 2 | ELUCIDATION OF HYDRODESULFURIZATION AND HYDROGENATION MECHANISMS USING RADIOISOTOPE TRACER METHODS显示文摘To meet the specification of sulfur and aromatic contents in diesel fuel, it is necessary for refiners to develop a new catalyst with high activity of hydrodesulfurization and hydrogenation. In the present study, the properties of noble metal catalysts for hydrodesulfurization and hydrogenation in the presence of sulfur compounds have been investigated. The hydrogenation activity of phenanthrene (PHE) on single noble metal and double noble metal catalysts—Pt/Al 2O 3, Pd/Al 2O 3 and Pd Pt/Al 2O 3 in the presence of dibenzothiophene (DBT) was perforrned in a fixed bed flow reactor. The Pt based catalysts revealed the similar HDS activities and higher HYD activity compared with convertional Mo based ca talysts . The maximum activity was obtained around 320 ℃ for both catalyst types. The Pt based catalysts produced perhydrophenanthrene as a major product at the maximum activity in the hydrogenation of PHE while the Mo based catalysts produced octahydrophenanthrene. A 35 S radioisotope pulse tracer method ( 35 S RPTM) was used to estimate the behavior of sulfur on the working catalysts and to clarity the differences between Pt and Mo based catalysts. Very little amount of labile sulfur was accumulated on the Pt and Pd catalysts in the HDS of [ 35 S]DBT (PtS 0.25 or PdS 0.25 ). This indicates that the mechanism of DBT HDS on noble metal catalysts is significantly different from that on conventional Mo based catalysts where Mo is present as MoS 2 less than 60% of which can be labile in the case of Co Mo/Al 2O 3. Another Ru Cs/Al 2O 3 catalysts were also prepared and the behavior of sulfur on the working catalyst was compared with those of Mo based catalysts and Pt and Pd catalysts. The values of labile sulfur in the HDS reaction for Ru Cs catalysts approximately correspond to RuS 0.5-0.74 . These amounts of labile sulfur are much higher than those for Pt and Pd catalysts. The result suggests that the oxidation state of Ru species is present between the oxidation states of Pt or Pd and Mo, and can change in the wide range during the HDS reaction, different from PtS 0.25 (PdS 0.25 ) and MoS 2 which is unchangeable under the usual HDS conditions. From the approach of using [ 35 S]H 2S it was found that the labile sulfur was hardly formed during the presulfiding procedure but was formed only during the actual HDS. This is also a unique character of Ru catalysts. | Atsushi ISHIHARA, Wei hua QIAN, Toshiaki KABE (Department of Chemical Engineering Faculty of Technology, Tokey University of Agriculture and Technology, 2 24 1 Nakacho, Koganei, Tokyo 184 8588, Japan) | 2001 | 石油学报(石油加工)2001，17，1： | 0 |
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