R&D on Hydrogen Production by Autothermal Reforming

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At the oil refinery, the hydrodesulfurization reactor operates with hydrogen partial pressure at 2.0-3.0 MPa for light fraction and at a high pressure of 10.0 MPa or greater for heavy fraction. Nevertheless, with the small-scale fuel cell power generation system, including power for household use, atmospheric pressure must be considered in terms of the High-Pressure Gas Control Law, the Electric Utility Law, and so on. In the present research, therefore, the following two points were assumed for desulfurization reaction. 1. The raw material is kerosene on the market (with 50 massppm sulfur component). 2. The reaction pressure is atmospheric pressure. The purpose of the initial investigation, therefore, was to determine desulfurization performance of active metals at atmospheric pressure. The constituents and configurations of catalysts used in evaluating activity are listed in Table 3.5.2. Desulfurization catalyst A is a regular extrusion-mold-type hydrodesulfurization catalyst. Desulfurization catalyst B was prepared by having precious metal, the active metal, retained in globular-shaped alumina, the carrier. Desulfurization catalyst C was obtained by molding base metal and zinc oxide in columnar-shaped tablets. A microreactor was used in evaluating the hydrodesulfurization activity of these three catalysts. Prior to the hydrodesulfurization reaction, desulfurization catalyst A filled in the reactor underwent preliminary sulfurization for 2 hrs at 350°C via 5% hydrogen sulfide/hydrogen gas; desulfurization catalysts B and C underwent hydrogenation pretreatment reduction for 2 hrs at 350°C under conditions of hydrogen flow. 3.5.2 Impact of Catalytically Active Metals Figure 3.5.1 presents the results of an evaluation of the hydrodesulfurization activity of each catalyst in kerosene on the market with the H2/oil ratio at 100 and the reaction temperature at 250°C. The desulfurization activity of these three catalysts with LHSV = 10 can be expressed in relative terms from reaction speed constant. When the activity of desulfurization catalyst A is taken as 100, that of desulfurization catalyst B becomes 250 and that of desulfurization catalyst C, 773, revealing that the activity of desulfurization catalyst C is the highest. Table 3.5.1: Properties of Raw Material Kerosene Used Distillation (°C) IBP 152 Density g/cm 3 0.791 10% 170 Composition Aroma % 22.4 20% 177 Olefin % 0.2 30% 185 14 Saturation % 77.4 40% 192 Sulfur component massppm 50 50% 201 60% 210 70% 221 80% 234 90% 248 EP 275
Table 3.5.2: List of Catalysts for Investigation of Kerosene Hydrodesulfurization Catalyst Constituent Configuration Catalyst A Hydrodesulfuization catalyst on market Extrusion molded products Catalyst B Precious metals Globular shape Catalyst C Base metals Columnar shaped tablets Relative activity value Catalyst A Catalyst B Catalyst C Figure 3.5.1: Evaluation Results for Hydrodesulfurization Activity 3.5.3 Impact of Catalyst Adjustment Conditions Desulfurization catalyst C is catalyst in which base metal components and metal oxides have been molded into columnar tablets. In order to investigate the impact of catalyst preparation conditions on hydrodesulfurization activity, four types of catalyst (Table 3.5.3) with different active metal load weight were prepared by means of the impregnation and co-precipitation methods. Using these catalysts, tests to evaluate activity were conducted with LHSV = 0.25 and reaction temperature at 300°C so as to clarify initial deterioration in activity. The results are shown in Figure 3.5.2. The performance of catalyst prepared by the impregnation method was such that the Sp value exceeded 0.2 massppm in catalyst with low metal retention magnitude for about 100 hrs and in catalyst with high metal load weight, for about 450 hrs. In catalyst prepared by the co-precipitation method, on the other hand, the Sp value did not exceed 0.2 massppm for up to 500 hrs irrespective of the active metal magnitude. In order to determine the amount of hydrogen required for reaction in the catalyst system, an investigation was made in which the hydrogen supply volume was modified over 100 hrs after reaction startup. The results are shown in Figure 3.5.3. With the H2/oil ratio at 50 or above, the Sp value was low irrespective of catalyst preparation method, but when the ratio fell below 50, it was found that the catalyst’s desulfurization activity drops sharply. Given this fact, it is conjectured that the H2/oil ratio must be at least 50 in this catalyst system. Table 3.5.3: List of C-type Catalysts Catalyst name Preparation method Metal load weight Catalyst C-1 Impregnation Low Catalyst C-2 Impregnation High Catalyst C-3 Co-precipitation Low Catalyst C-4 Co-precipitation High 15
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Page 3 and 4: Figure 3.1.2: O2/C Ratio vs S/C Rat
Page 5 and 6: Figure 3.2.1: ATR-FPS Flow Diagram
Page 7 and 8: Table 3.2.2: Heat Balance Received
Page 9 and 10: Figure 3.3.3. It was recognized tha
Page 11 and 12: 3.4.2 Reforming Reactivity of Norma
Page 13: 3.4.4 Reforming Reactivity of Each
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R&D on Hydrogen Production by Autothermal Reforming

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