JP2004230317A - Desulfurization catalyst and desulfurization method for hydrocarbon, and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a desulfurization catalyst solving problems wherein sulfur contained in fuel must be sufficiently removed, as a noble metal or copper in a catalyst in various processes for producing fuel hydrogen for a fuel cell and in a catalyst used for a negative electrode of the fuel cell, is used in a reduced state, and sulfur must be effectively removed in a low pressure condition in order to incorporate a desulfurization device into the fuel cell system. <P>SOLUTION: Sulfur content in a hydrocarbon containing sulfur can be removed to 0.1 mass ppm or less by the desulfurization catalyst containing 30-80 mass% nickel oxide, 10-70 mass% zinc oxide and 0.1-40 mass% alumina, which are obtained by baking a catalyst precursor formed by coprecipitating components containing nickel and zinc using at least one kind of alumina selected from γ-alumina, β-alumina and pseudo boehmite as a core. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００４３】
（実施例３）
図１の燃料電池システムにおいて、脱硫器５に、実施例１で得られた触媒（１）を充填して、１号灯油（硫黄濃度：２３質量ｐｐｍ）を燃料とし、発電試験を行なった。１５０時間の運転中、脱硫器は正常に作動し、触媒の活性低下は認められなかった。脱硫条件は、温度１８０℃、常圧、水素流通なし、ＬＨＳＶ＝０．５ｈ^−１であった。
このとき水蒸気改質にはＲｕ系触媒を用い、Ｓ／Ｃ＝３、温度７００℃、ＬＨＳＶ＝５ｈ^−１の条件で、シフト工程（反応器１０）では銅−亜鉛系触媒を用い、２００℃、ＧＨＳＶ＝２０００ｈ^−１の条件で、一酸化炭素選択酸化工程（反応器１１）ではＲｕ系触媒を用い、Ｏ_２／ＣＯ＝３、温度１５０℃、ＧＨＳＶ＝５０００ｈ^−１の条件で運転を行った。燃料電池も正常に作動し電気負荷１５も順調に運転された。
【図面の簡単な説明】
【図１】本発明の燃料電池システムの一例を示す概略図である。
【符号の説明】
１ 水タンク
２ 水ポンプ
３ 燃料タンク
４ 燃料ポンプ
５ 脱硫器
６ 気化器
７ 改質器
８ 空気ブロアー
９ 高温シフト反応器
１０ 低温シフト反応器
１１ 一酸化炭素選択酸化反応器
１２ アノード
１３ カソード
１４ 固体高分子電解質
１５ 電気負荷
１６ 排気口
１７ 固体高分子形燃料電池
１８ 加温用バーナー[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydrocarbon desulfurization catalyst. The present invention also relates to a method for desulfurizing a hydrocarbon containing sulfur using the catalyst. Furthermore, the present invention relates to a fuel cell system provided with a desulfurization device filled with the catalyst.
[0002]
[Prior art]
A fuel cell has a feature that high efficiency can be obtained because a change in free energy due to a fuel combustion reaction can be directly taken out as electric energy. In addition, the elimination of harmful substances has led to the development of various applications. In particular, polymer electrolyte fuel cells are characterized by high power density, compactness, and operation at low temperatures.
[0003]
Generally, a gas containing hydrogen as a main component is used as a fuel gas for a fuel cell. The raw material is a natural gas, a hydrocarbon such as LPG, naphtha, kerosene, or an alcohol such as methanol or ethanol, or dimethyl ether. And the like. These raw materials containing carbon and hydrogen are reformed by treating them with steam at a high temperature on a catalyst, partially oxidized with oxygen-containing gas, and self-heat recovery type reforming reaction in a system where steam and oxygen-containing gas coexist. Is basically used as fuel hydrogen for a fuel cell.
[0004]
However, since elements other than hydrogen also exist in these raw materials, it is inevitable that impurities derived from carbon are mixed in the fuel gas to the fuel cell. For example, carbon monoxide poisons a platinum-based noble metal used as an electrode catalyst of a fuel cell, so that if carbon monoxide is present in fuel gas, sufficient power generation characteristics cannot be obtained. In particular, a fuel cell operated at a lower temperature has a stronger carbon monoxide adsorption and is more susceptible to poisoning. Therefore, in a system using a polymer electrolyte fuel cell, it is essential that the concentration of carbon monoxide in the fuel gas be reduced.
[0005]
For this reason, a method is adopted in which carbon monoxide in a reformed gas obtained by reforming a raw material is reacted with steam to convert it into hydrogen and carbon dioxide, and a trace amount of remaining carbon monoxide is removed by selective oxidation. .
The fuel hydrogen, which is finally removed to a sufficiently low concentration of carbon monoxide, is introduced into the fuel cell cathode, where it is converted to protons and electrons on an electrocatalyst. The generated protons move to the anode side in the electrolyte, and react with oxygen together with the electrons that have passed through the external circuit to generate water. The electrons pass through an external circuit to generate electricity.
[0006]
In the process of reforming the raw material until the production of fuel hydrogen for fuel cells and removing carbon monoxide, and the catalyst used for the cathode electrode, noble metals or copper are often used in a reduced state, and such a state is used. In this case, the sulfur acts as a catalyst poison, which causes a problem that the catalytic activity of the hydrogen production process or the battery itself is reduced, and the efficiency is reduced.
Therefore, it is considered that it is indispensable to sufficiently remove the sulfur contained in the raw material in order to use the catalyst used in the hydrogen production process and the electrode catalyst with the original performance.
The so-called desulfurization process, which basically removes sulfur, is performed at the very beginning of the hydrogen production process. Immediately after that, it is necessary to reduce the sulfur concentration to a level at which the catalyst used in the reforming step is sufficiently functional, and this is usually 0.1 ppm by mass or less.
[0007]
Until now, as a method of removing the sulfur content of fuel cell materials, a desulfurization catalyst is used to hydrodesulfurize hard-to-desulfurize organic sulfur compounds, convert them to hydrogen sulfide that is once easily adsorbed and removed, and treat with an appropriate adsorbent. The way you thought was appropriate. However, in general hydrodesulfurization catalysts, the hydrogen pressure is increased. However, when used in fuel cell systems, the technical development at atmospheric pressure or at most 1 MPa is progressing. At present, it cannot be handled by the system.
[0008]
For this reason, a catalyst system capable of sufficiently exhibiting a desulfurization function even in a low pressure system has been studied. For example, a method of producing hydrogen by steam reforming kerosene desulfurized with a nickel-based desulfurizing agent has been proposed (for example, see Patent Documents 1 and 2). However, this method has a process limitation that the temperature range in which desulfurization is possible is 150 to 300 ° C. Further, proposals have been made on copper-zinc-based desulfurization catalysts (for example, see Patent Documents 3 and 4). However, even though this catalyst is used at relatively high temperatures, although carbon deposition is small, its desulfurization activity is lower than that of nickel, so it is possible to desulfurize light hydrocarbons such as natural gas, LPG, and naphtha. Is insufficient. In addition, a method using activated carbon or a chemical solution for performing a desulfurizing action has been proposed (see Patent Document 5). However, although this catalyst is shown to have a desulfurization effect at room temperature at startup, the raw material is limited to a gas at room temperature. Although a nickel-zinc catalyst has been proposed (see Patent Document 6), it is assumed that the catalyst is used under the coexistence of hydrogen and under pressure. Under the non-existence of hydrogen, the nickel content is small and the catalyst performance is reduced. .
[0009]
[Patent Document 1]
JP-A-1-188404
[Patent Document 2]
JP-A-1-188405
[Patent Document 3]
JP-A-2-302302
[Patent Document 4]
JP-A-2-302303
[Patent Document 5]
JP-A-1-143155
[Patent Document 6]
JP 2001-622297 A
[0010]
[Problems to be solved by the invention]
As described above, the raw material reforming until the production of fuel hydrogen for fuel cells, each step of carbon monoxide removal, the catalyst used for the cathode electrode is often used in a reduced state of noble metal or copper, etc., In such a state, the sulfur acts as a catalyst poison, lowering the catalytic activity of the hydrogen production process or the battery itself, and lowering the efficiency. Therefore, it is indispensable to sufficiently remove the sulfur contained in the raw material in order to use the catalyst used in the hydrogen production step and the electrode catalyst at the original performance. In addition, it is necessary to effectively desulfurize hard-to-desulfurize substances under low pressure conditions.
[0011]
[Means for Solving the Problems]
As a result of intensive studies on such problems, the present inventors have found a catalyst that efficiently desulfurizes sulfur contained in hydrocarbons, and have completed the present invention. The present invention also provides a desulfurization method using the specific catalyst, and a fuel cell system having a desulfurization device using the catalyst.
[0012]
That is, a first aspect of the present invention is to obtain a catalyst precursor obtained by calcining a catalyst precursor obtained by forming a component containing nickel and zinc using at least one alumina selected from γ-alumina, β-alumina and pseudoboehmite as a nucleus by a coprecipitation method. The present invention relates to a hydrocarbon desulfurization catalyst containing 30 to 80% by mass of nickel oxide, 10 to 70% by mass of zinc oxide and 0.1 to 40% by mass of alumina.
[0013]
A second aspect of the present invention relates to a hydrocarbon desulfurization method, wherein the sulfur-containing hydrocarbon is desulfurized to a sulfur concentration of 0.1 mass ppm or less using the catalyst.
[0014]
Further, a third aspect of the present invention is a desulfurization apparatus having a reaction section filled with the catalyst, for desulfurizing a hydrocarbon containing sulfur, and converting the hydrocarbon desulfurized by the desulfurization apparatus into hydrogen as a main component. The present invention relates to a fuel cell system having at least a reformer for reforming a fuel gas to be used.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The desulfurization catalyst of the present invention is obtained by calcining a catalyst precursor obtained by forming a component containing nickel and zinc using alumina as a core by a coprecipitation method.
As the alumina, at least one selected from γ-alumina, β-alumina and pseudo-boehmite is used.
The particle size of the alumina used is preferably 1000 μm or less, preferably 500 μm or less, more preferably 200 μm or less in the form of a powder. If the particle size of alumina is larger than 1000 microns, it will be difficult for alumina itself to exist uniformly in the system, and uniform precipitation on alumina will be inhibited. The lower limit of the particle size is not particularly limited, but is usually 1 nm or more, and preferably a powdery one composed of particles of 10 nm or more.
[0016]
The coprecipitation method of forming a component containing nickel and zinc using alumina as a nucleus is, specifically, suspending alumina in an aqueous solution of a nickel compound and a zinc compound and mixing a base with the suspension, or Alumina is suspended in an aqueous solution of the above, and an aqueous solution of a nickel compound and a zinc compound are mixed with the suspension to form a catalyst precursor by causing precipitation of the nickel compound and the zinc compound on the alumina.
As the nickel compound and the zinc compound, chlorides, nitrates, sulfates, organic acid salts, hydroxides and the like can be used. Specifically, nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, nickel hydroxide, zinc chloride, zinc nitrate, zinc sulfate, zinc acetate, zinc hydroxide and the like are preferable.
As the base, an aqueous solution of ammonia, sodium carbonate, sodium hydrogen carbonate, potassium carbonate or the like can be used.
[0017]
After a nickel compound and a zinc compound are precipitated on alumina using alumina as a nucleus, the generated precipitate product (catalyst precursor) is filtered and washed with ion-exchanged water or the like. Insufficient washing leaves chlorine, nitric acid traces, sulfuric acid traces, acetic acid traces, sodium, potassium, etc. on the catalyst and adversely affects the catalytic performance. When washing cannot be sufficiently performed with ion-exchanged water, an aqueous solution of a base such as ammonia, sodium carbonate, sodium hydrogen carbonate, or potassium carbonate may be used as the washing solution. In this case, it is preferable to wash the precipitated product first with an aqueous solution of a base, and then with ion-exchanged water.
After washing the precipitated product, the precipitated product is ground and then dried. After drying, baking is performed subsequently. If washing after precipitation is insufficient, washing may be performed again after firing. Also in this case, ion-exchanged water or an aqueous solution of the aforementioned base can be used.
[0018]
The drying method is not particularly limited, and includes, for example, natural drying in air, degassing drying under reduced pressure, and the like. Usually, drying is performed in an air atmosphere at 100 to 150 ° C. for 5 to 15 hours. The firing method is not particularly limited, and firing is usually performed in an air atmosphere at 200 to 600 ° C, preferably 250 to 450 ° C, for 0.1 to 10 hours, and preferably for 1 to 5 hours. desirable.
[0019]
The catalyst of the present invention obtained by calcining the above-mentioned catalyst precursor contains nickel oxide, zinc oxide and alumina as constituent components.
The content of nickel oxide in the catalyst is 30 to 80% by mass, preferably 40 to 80% by mass, and more preferably 45 to 80% by mass. When the content of nickel oxide in the catalyst is less than 30% by mass, the catalytic performance becomes insufficient. On the other hand, if the content of nickel oxide in the catalyst exceeds 80% by mass, the dispersibility of nickel is reduced, and not only is the catalyst performance reduced, but it is economically undesirable.
The content of zinc oxide in the catalyst is 10 to 70% by mass, preferably 10 to 60% by mass, more preferably 15 to 50% by mass. When the content of zinc oxide in the catalyst is less than 10% by mass, the catalytic performance becomes insufficient. When the content exceeds 70% by mass, the nickel content relatively decreases, and the catalytic performance decreases.
The content of alumina in the catalyst is 0.1 to 40% by mass, preferably 0.5 to 35% by mass, and more preferably 1 to 30% by mass. When the content of alumina in the catalyst is less than 0.1% by mass, the catalytic performance becomes insufficient, and when it exceeds 40% by mass or more, the nickel content relatively decreases, and the catalytic performance decreases.
[0020]
When the catalyst prepared by the above method is used, it can be used for the reaction as it is, but a reduction treatment with hydrogen or the like may be performed as a pretreatment. The temperature is desirably 150 to 500 ° C, preferably 250 to 400 ° C, and the time is 0.1 to 15 hours, preferably 2 to 10 hours.
[0021]
The shape of the catalyst of the present invention is not particularly limited, and the catalyst obtained as a powder may be used as it is, or may be tablet-molded and formed into a molded product. After the pulverization, the catalyst may be sized to an appropriate range. Further, it may be an extruded catalyst. In molding, a suitable binder may be added. The binder is not particularly limited, and carbon black, alumina, silica, titania, zirconia, or a composite oxide thereof can be used. The upper limit of the amount of the binder is usually 50% by mass or less, preferably 30% by mass or less. The lower limit is not particularly limited as long as it can exhibit the function as a binder, and is usually 1% by mass or more, preferably 5% by mass or more.
[0022]
A second aspect of the present invention is a method for desulfurizing a hydrocarbon, comprising desulfurizing a hydrocarbon containing sulfur to a sulfur concentration of 0.1 mass ppm or less using the first catalyst of the present invention. In particular, the desulfurization method of the present invention is characterized in that the sulfur concentration can be reduced to 0.1 mass ppm or less under the non-existence of hydrogen.
The hydrocarbon containing sulfur used in the present invention is not particularly limited, and examples thereof include methane, ethane, propane, butane, natural gas, LPG, naphtha, gasoline, kerosene, and mixtures thereof. In addition, hydrogen may be contained in the raw material hydrocarbon, and various alcohols, ethers and the like may be contained. Further, these raw material hydrocarbons may be liquid or gas.
These hydrocarbons used in the present invention contain a trace amount of sulfur, and the amount varies depending on the production method, but usually contains more than 0.1 mass ppm and 100 mass ppm or less of sulfur. I have. In addition, the sulfur content of the present invention is a general term for various kinds of sulfur, inorganic sulfur compounds, and organic sulfur compounds usually contained in these hydrocarbons.
[0023]
The pressure in the desulfurization reaction is preferably a low pressure in the range of normal pressure to 1 MPa, and particularly preferably normal pressure to 0.2 MPa, in consideration of the economy and safety of the fuel cell system. The reaction temperature is not particularly limited as long as it is a temperature at which the sulfur concentration is reduced, but it is preferable that the reaction is effectively performed from room temperature in consideration of the start of the apparatus, and also in the steady state. 10 ° C to 450 ° C is preferred. More preferably, 15 ° C to 350 ° C, particularly preferably, 20 ° C to 300 ° C is employed. If the SV is too high, the desulfurization reaction does not easily proceed, while if the SV is too low, the size of the apparatus increases, so that the SV is set to a suitable range. When using a liquid material, 0.01 to 15 hours ^-1 Is preferably in the range of 0.05 to 5 h ^-1 Is more preferable, and 0.1 to 3 h ^-1 Is particularly preferred. 100 to 10000h when using gas fuel ^-1 Is preferably in the range of 200 to 5000 h ^-1 Is more preferable, and 300 to 2000 h ^-1 Is particularly preferred. The desulfurization method of the present invention is characterized in that desulfurization can be performed under the condition that hydrogen is not present, but a small amount of hydrogen may be introduced. The flow rate of hydrogen at that time is, for example, 0.05 to 1.0 NL per 1 g of the hydrocarbon raw material.
[0024]
Although the form of the desulfurization apparatus using the desulfurization method of the present invention is not particularly limited, for example, a flow-type fixed bed system can be used. As the shape of the desulfurization device, any known shape depending on the purpose of each process such as a cylindrical shape and a flat plate shape can be adopted.
[0025]
By using the desulfurization catalyst of the present invention, the sulfur concentration of the hydrocarbon containing sulfur can be reduced to 0.1 mass ppm or less under the non-existence condition of hydrogen. The sulfur concentration is measured by an ultraviolet fluorescence method.
The hydrocarbon desulfurized to a sulfur concentration of 0.1 mass ppm or less is then subjected to a reforming step, a shift step, a carbon monoxide selective oxidation step, and the like, and the generated hydrogen-rich gas is used as a fuel for a fuel cell. Can be.
[0026]
The reforming step is not particularly limited, but steam reforming, in which the raw material is treated with steam at a high temperature over a catalyst, reforming, partial oxidation with an oxygen-containing gas, and coexistence of steam and an oxygen-containing gas For example, an autothermal reforming for performing a self-heat recovery type reforming reaction in a system to be used can be used.
Although the reaction conditions for the reforming are not limited, the reaction temperature is preferably from 200 to 1000C, particularly preferably from 500 to 850C. The reaction pressure is preferably normal pressure to 1 MPa, particularly preferably normal pressure to 0.2 MPa. LHSV is 0.01-40h ^-1 Is preferred, and particularly 0.1 to 10 h ^-1 Is preferred.
[0027]
The mixed gas containing carbon monoxide and hydrogen obtained at this time can be directly used as a fuel for a fuel cell in the case of a solid oxide fuel cell. Further, it can be suitably used as a source of hydrogen for fuel cells for fuel cells that require removal of carbon monoxide, such as phosphoric acid fuel cells and polymer electrolyte fuel cells.
[0028]
The production of hydrogen for a fuel cell can be performed by a known method, for example, by performing a shift step and a carbon monoxide selective oxidation step.
The shift step is a step in which carbon monoxide and water are reacted to convert them into hydrogen and carbon dioxide, and include, for example, a mixed oxide of iron-chromium, a mixed oxide of copper-zinc, platinum, ruthenium, and iridium. The catalyst is used to reduce the carbon monoxide content to 2 vol% or less, preferably 1 vol% or less, and more preferably 0.5 vol% or less.
The reaction conditions for the shift reaction are not necessarily limited depending on the composition of the reformed gas used as a raw material, but the reaction temperature is preferably from 120 to 500 ° C, and particularly preferably from 150 to 450 ° C. The pressure is preferably normal pressure to 1 MPa, particularly preferably normal pressure to 0.2 MPa. GHSV is 100 ~ 50,000h ^-1 Is preferable, and especially 300 to 10000h ^-1 Is preferred. Usually, the mixed gas in this state can be used as fuel in the phosphoric acid type fuel cell.
[0029]
On the other hand, in the polymer electrolyte fuel cell, it is necessary to further reduce the concentration of carbon monoxide, and thus it is desirable to provide a step of removing carbon monoxide. This step is not particularly limited, and various methods such as an adsorption separation method, a hydrogen separation membrane method, and a carbon monoxide selective oxidation step can be used. It is particularly preferable to use a carbon monoxide selective oxidation step. In this step, using a catalyst containing iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold, etc., 0.5 to 10 times the remaining carbon monoxide mole number. The concentration of carbon monoxide is reduced by selectively converting carbon monoxide to carbon dioxide by adding oxygen in a molar amount, preferably 0.7 to 5 times, and more preferably 1 to 3 times. The reaction conditions of this method are not limited, but the reaction temperature is preferably from 80 to 350 ° C, particularly preferably from 100 to 300 ° C. The pressure is preferably normal pressure to 1 MPa, particularly preferably normal pressure to 0.2 MPa. GHSV is 1000-50,000h ^-1 Is preferable, and especially 3000 to 30000h ^-1 Is preferred. In this case, the concentration of carbon monoxide can be reduced by reacting the coexisting hydrogen with the coexisting hydrogen to generate methane.
[0030]
A third aspect of the present invention is a desulfurization apparatus that has a reaction section filled with the first desulfurization catalyst of the present invention, desulfurizes hydrocarbons containing sulfur, and converts the hydrocarbons desulfurized by the desulfurization apparatus. And a fuel cell system having at least a reformer for reforming a fuel gas containing hydrogen as a main component.
[0031]
Hereinafter, an example of this fuel cell system will be described with reference to FIG.
The raw fuel in the fuel tank 3 flows into the desulfurizer 5 via the fuel pump 4. At this time, if necessary, a hydrogen-containing gas from the carbon monoxide selective oxidation reactor 11 can be added. The desulfurizer 5 is filled with the desulfurization catalyst of the present invention. The fuel desulfurized in the desulfurizer 5 is mixed with water from the water tank 1 through the water pump 2, introduced into the vaporizer 6 and sent to the reformer 7.
[0032]
The reformer 7 is heated by a heating burner 18. As the fuel for the heating burner 18, the anode off-gas of the fuel cell 17 is mainly used, but the fuel discharged from the fuel pump 4 can be supplemented as needed. As a catalyst filled in the reformer 7, a nickel-based, ruthenium-based, rhodium-based catalyst or the like can be used.
The gas containing hydrogen and carbon monoxide produced in this manner is sequentially passed through a high-temperature shift reactor 9, a low-temperature shift reactor 10, and a carbon monoxide selective oxidation reactor 11, so that the concentration of carbon monoxide is reduced. Is reduced so as not to affect the characteristics of Examples of catalysts used in these reactors include an iron-chromium catalyst for the high-temperature shift reactor 9, a copper-zinc catalyst for the low-temperature shift reactor 10, and a ruthenium-based catalyst for the carbon monoxide selective oxidation reactor 11. Etc. can be given.
[0033]
The polymer electrolyte fuel cell 17 comprises an anode 12, a cathode 13, and a polymer electrolyte 14. The fuel gas containing high-purity hydrogen obtained by the above-described method is provided on the anode side, and the air blower is provided on the cathode side. The air sent from 8 is introduced after performing appropriate humidification processing if necessary (humidifier is not shown). At this time, a reaction in which hydrogen gas becomes protons and emits electrons proceeds at the anode, and a reaction at which oxygen gas obtains electrons and protons to become water proceeds at the cathode. In order to promote these reactions, platinum black and activated carbon-supported Pt catalyst or Pt-Ru alloy catalyst are used for the anode, and platinum black and activated carbon-supported Pt catalyst are used for the cathode. Usually, both the anode and cathode catalysts are formed into a porous catalyst layer together with polytetrafluoroethylene, a low molecular weight polymer electrolyte membrane material, activated carbon and the like, if necessary.
[0034]
Then, the porous catalyst layers are laminated on both sides of a polymer electrolyte membrane known by trade names such as Nafion (manufactured by DuPont), Gore (manufactured by Gore), Flemion (manufactured by Asahi Glass), and Aciplex (manufactured by Asahi Kasei). An MEA (Membrane Electrode Assembly) is formed. Furthermore, the fuel cell is assembled by sandwiching the MEA with a separator having a gas supply function made of a metal material, graphite, carbon composite, or the like, a current collection function, and particularly a drainage function that is important for the cathode. The electric load 15 is electrically connected to the anode and the cathode. The anode off-gas is consumed in the heating burner 18. The cathode off-gas is exhausted from the exhaust port 16.
[0035]
【The invention's effect】
By using the desulfurization catalyst of the present invention, the sulfur-containing hydrocarbon can be desulfurized under the non-existence condition of hydrogen, and the sulfur concentration can be reduced to 0.1 mass ppm or less, and the obtained fuel gas is particularly solid. It can be suitably used in a fuel cell system using a polymer fuel cell.
[0036]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0037]
(Example 1)
62.7 g of nickel acetate tetrahydrate (special grade of commercial reagent) and 14.5 g of zinc acetate dihydrate (special grade of commercial reagent) were dissolved in ion-exchanged water, and commercially available γ-alumina (particles) was added to 1200 ml of an aqueous solution A1. After suspending 6.7 g of the mixture and stirring for 30 minutes, 37.1 g of sodium carbonate (special grade of commercial reagent) was dissolved in ion-exchanged water, and 450 ml of an aqueous solution B1 was added dropwise with stirring at room temperature. A precipitate formed. After the precipitate was washed with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then calcined at 360 ° C. for 4 hours to obtain 27 g of calcined powder. The composition of the fired powder is NiO / ZnO / Al ₂ O ₃ = 61% by mass / 17% by mass / 22% by mass.
The resulting calcined powder was tableted and sized to a particle size of 1.0 to 1.4 mm. ³ Into a flow-type reaction tube having a diameter of 1.27 cm, reduced in a hydrogen stream at 350 ° C. for 3 hours, and then reacted at 180 ° C. and LHSV = 0.5 h. ^-1 , A desulfurization test of JIS No. 1 kerosene (sulfur concentration: 49 mass ppm) was conducted under the non-existence condition of hydrogen, and the sulfur concentration of the produced kerosene after 200 hours is shown in Table 1.
[0038]
(Example 2)
98.5 g of nickel nitrate hexahydrate (special grade of commercial reagent) and 26.5 g of zinc nitrate hexahydrate (special grade of commercial reagent) were dissolved in ion-exchanged water, and 150 ml of aqueous solution A2 was converted to sodium carbonate (special grade of commercial reagent). 47.7 g was dissolved in ion-exchanged water to make 400 ml, and dropped into an aqueous solution B2 in which 1.6 g of commercially available pseudoboehmite (particle size: about 50 μm) was suspended at 40 ° C. with stirring to form a precipitate. . After the precipitate was washed with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 360 ° C. for 4 hours to obtain 31 g of calcined powder. The composition of the fired powder is NiO / ZnO / Al ₂ O ₃ = 75% by mass / 22% by mass / 3% by mass.
The resulting calcined powder was tableted and sized to a particle size of 1.0 to 1.4 mm. ³ Into a flow-type reaction tube having a diameter of 1.27 cm, reduced in a hydrogen stream at 350 ° C. for 3 hours, and then reacted at 180 ° C. and LHSV = 0.5 h. ^-1 , A desulfurization test of JIS No. 1 kerosene (sulfur concentration: 49 mass ppm) was conducted under the non-existence condition of hydrogen, and the sulfur concentration of the produced kerosene after 200 hours is shown in Table 1.
[0039]
(Comparative Example 1)
90.7 g of nickel acetate tetrahydrate (special grade of commercial reagent) and 14.8 g of zinc acetate dihydrate (special grade of commercial reagent) were dissolved in ion-exchanged water, and commercially available γ-alumina (particles) was added to 1200 ml of an aqueous solution A3. After suspending 0.9 g of a solution having a diameter of about 80 μm and stirring for 30 minutes, 33.6 g of sodium carbonate (special grade of commercial reagent) was dissolved in ion-exchanged water. Was formed. After the precipitate was washed with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then calcined at 360 ° C. for 4 hours to obtain 30 g of calcined powder. The composition of the fired powder is NiO / ZnO / Al ₂ O ₃ = 81% by mass / 16% by mass / 3% by mass.
The resulting calcined powder was tableted, and the catalyst was sized to a particle size of 1.0 to 1.4 mm. ³ Into a flow-type reaction tube having a diameter of 1.27 cm, reduced in a hydrogen stream at 350 ° C. for 3 hours, and then reacted at 180 ° C. and LHSV = 0.5 h. ^-1 , A desulfurization test of JIS No. 1 kerosene (sulfur concentration: 49 mass ppm) was conducted under the non-existence condition of hydrogen, and the sulfur concentration of the produced kerosene after 200 hours is shown in Table 1.
[0040]
(Comparative Example 2)
25.3 g of nickel acetate tetrahydrate (special grade of commercial reagent) and 44.3 g of zinc acetate dihydrate (special grade of commercial reagent) were dissolved in ion-exchanged water, and commercially available γ-alumina (particles) was added to 1200 ml of an aqueous solution A4. 7.5 g) were suspended, and after stirring for 30 minutes, 23.6 g of sodium carbonate (special grade commercial reagent) was dissolved in ion-exchanged water, and 450 ml of an aqueous solution B4 was added dropwise with stirring at room temperature. A precipitate formed. After the precipitate was washed with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then calcined at 360 ° C. for 4 hours to obtain 28 g of calcined powder. The composition of the fired powder is NiO / ZnO / Al ₂ O ₃ = 24% by mass / 52% by mass / 24% by mass.
The resulting calcined powder was tableted and sized to a particle size of 1.0 to 1.4 mm. ³ Into a flow-type reaction tube having a diameter of 1.27 cm, reduced in a hydrogen stream at 350 ° C. for 3 hours, and then reacted at 180 ° C. and LHSV = 0.5 h. ^-1 , A desulfurization test of JIS No. 1 kerosene (sulfur concentration: 49 mass ppm) was conducted under the non-existence condition of hydrogen, and the sulfur concentration of the produced kerosene after 200 hours is shown in Table 1.
[0041]
(Comparative Example 3)
103.4 g of nickel nitrate hexahydrate (special grade of commercial reagent) and 27.8 g of zinc nitrate hexahydrate (special grade of commercial reagent) were dissolved in ion-exchanged water, and 150 ml of aqueous solution A5 was converted to sodium carbonate (special grade of commercial reagent). ) 50.1 g was dissolved in ion-exchanged water and added dropwise to a 400 ml aqueous solution B5 with stirring at 40 ° C to form a precipitate. After the precipitate was washed with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 360 ° C. for 4 hours to obtain 31 g of calcined powder. The composition of the fired powder is NiO / ZnO / Al ₂ O ₃ = 78% by mass / 22% by mass / 0% by mass.
The resulting calcined powder was tablet-molded and sized to a particle size of 1.0 to 1.4 mm. ³ Into a flow-type reaction tube having a diameter of 1.27 cm, reduced in a hydrogen stream at 350 ° C. for 3 hours, and then reacted at 180 ° C. and LHSV = 0.5 h. ^-1 , A desulfurization test of JIS No. 1 kerosene (sulfur concentration: 49 mass ppm) was conducted under the non-existence condition of hydrogen, and the sulfur concentration of the produced kerosene after 200 hours is shown in Table 1.
[0042]
[Table 1]

[0043]
(Example 3)
In the fuel cell system shown in FIG. 1, the desulfurizer 5 was filled with the catalyst (1) obtained in Example 1, and a power generation test was performed using No. 1 kerosene (sulfur concentration: 23 mass ppm) as fuel. During the operation for 150 hours, the desulfurizer operated normally, and no decrease in the activity of the catalyst was observed. The desulfurization conditions were as follows: temperature 180 ° C., normal pressure, no hydrogen flow, LHSV = 0.5 h ^-1 Met.
At this time, a Ru-based catalyst was used for steam reforming, S / C = 3, temperature 700 ° C., LHSV = 5h ^-1 In the shift step (reactor 10), a copper-zinc catalyst was used in the shift step (reactor 10) at 200 ° C. and GHSV = 2000 h. ^-1 In the conditions for the selective oxidation of carbon monoxide (reactor 11), a Ru-based catalyst is used ₂ / CO = 3, temperature 150 ° C, GHSV = 5000h ^-1 The operation was performed under the following conditions. The fuel cell also operated normally, and the electric load 15 was operated smoothly.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing one example of a fuel cell system of the present invention.
[Explanation of symbols]
1 water tank
2 water pump
3 Fuel tank
4 Fuel pump
5 desulfurizer
6 vaporizer
7 Reformer
8 Air blower
9 High temperature shift reactor
10 Low temperature shift reactor
11 Selective oxidation reactor for carbon monoxide
12 Anode
13 Cathode
14 Solid polymer electrolyte
15 Electric load
16 Exhaust port
17 polymer electrolyte fuel cell
18 Burner for heating

Claims (3)

30 to 80% by mass of nickel oxide obtained by calcining a catalyst precursor formed by coprecipitation with a component containing nickel and zinc using at least one alumina selected from γ-alumina, β-alumina and pseudoboehmite as a core , A hydrocarbon desulfurization catalyst comprising 10 to 70% by mass of zinc oxide and 0.1 to 40% by mass of alumina. A hydrocarbon desulfurization method comprising desulfurizing a hydrocarbon containing sulfur to a sulfur concentration of 0.1 mass ppm or less using the catalyst according to claim 1. A desulfurization device having a reaction section filled with the catalyst according to claim 1 and desulfurizing a hydrocarbon containing sulfur, and converting the hydrocarbon desulfurized by the desulfurization device into a fuel gas containing hydrogen as a main component. A fuel cell system having at least a reformer for reforming.

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