PETR 126 |
| Transition metal phosphides were recently reported [1-3] as a new class of HDS catalysts with fascinating performance during HDS reactions. Many reports [1, 2] indicated that the HDS activity of phosphides can be improved by the introduction of sulfur during HDS process. In the present work, a successive sulfidation-reduction approach was used to prepare MoP/MCM-41 and WP/MCM-41 HDS catalysts. The catalysts prepared by the novel procedure exhibited higher activity compared to the catalysts prepared by the traditional temperature-programmed reduction method. The phosphide precursors supported over MCM-41 were prepared by pore-volume impregnation method. The conversion of the precursors to the metal phosphides contains two steps: the precursors were firstly sulfided with H2S and then reduced with H2. The samples were denoted as MoP/MCM-41(S) and WP/MCM-41(S), respectively. For comparison, the phosphides prepared by the traditional reduction procedure [2] were also prepared, and were denoted as MoP/MCM-41(D) and WP/MCM-41(D), respectively. Fig. 1 shows the variations of the HDS activities of molybdenum phosphides at 300oC and tungsten phosphides at 320oC as a function of reaction time. It can be seen that the activities of all the fresh catalysts dropped sharply, and then leveled off after few hours. The phosphides prepared by sulfidation-reduction procedure exhibited higher DBT conversion than their counterparts. As shown in Fig. 2, selectivities toward the formation of cyclohexylbenzene (CHB) and bicyclohexyl (BCH), the hydrogenation products, all increased markedly over MoP/MCM-41(S) and WP/MCM-41(S), suggesting that the hydrogenation activity of MoP/MCM-41 and WP/MMC-41 can be improved by using the novel sulfidation-reduction procedure.
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Chemistry of Petroleum and Emerging Technologies
9:00 AM-12:00 PM, Thursday, August 23, 2007 Boston Park Plaza -- White Hill Rm, Oral
Division of Petroleum Chemistry |
