JP5324205B2 - Hydrocarbon desulfurization agent and method for producing the same, kerosene desulfurization method, fuel cell system - Google Patents

Abstract

The hydrocarbon desulfurizing agent contains a porous inorganic oxide, nickel and/or a nickel oxide, zinc oxide, cobalt and/or a cobalt oxide, and molybdenum and/or a molybdenum oxide. The content of the porous inorganic oxide is 10-30 mass%, the content of the nickel and/or the nickel oxide is 45-75 mass%, and the content of the zinc oxide is 3-40 mass% in terms of oxide, based on the total mass of the desulfurizing agent. According to the invention, it is possible to provide a hydrocarbon desulfurizing agent and a manufacturing method thereof with which sufficient desulfurizing capability can be sustained over a long period of time even when a starting material fuel such as kerosene is desulfurized under low-pressure conditions or in the absence of hydrogen, as well as provide a kerosene desulfurization method which utilizes said desulfurizing agent and a fuel cell system.

Description

  The present invention relates to a hydrocarbon desulfurization agent and a method for producing the same, a method for desulfurizing kerosene, and a fuel cell system.

  In recent years, new energy technology has attracted attention due to environmental problems, and fuel cells are attracting attention as one of the new energy technologies. A fuel cell has a feature that high energy efficiency can be obtained because a free energy change caused by a combustion reaction of fuel can be directly taken out as electric energy. In addition to the fact that it does not emit harmful substances, it is being developed for various uses. In particular, polymer electrolyte fuel cells are characterized by high power density, compactness, and operation at low temperatures.

  In general, a gas mainly composed of hydrogen is used as a fuel gas for a fuel cell. As a raw fuel for obtaining a fuel gas containing hydrogen, natural gas, hydrocarbons such as LPG, naphtha and kerosene, alcohols such as methanol and ethanol, ethers such as dimethyl ether, and the like are used. These raw fuels contain carbon and hydrogen, and in a system in which the raw material undergoes a reforming reaction on a catalyst with steam, a partial oxidation reaction with an oxygen-containing gas, or a system in which steam and oxygen-containing gas coexist. By performing the reforming reaction of the self-heat recovery type, a gas containing hydrogen and carbon monoxide is generated, and further through a process of reducing or removing carbon monoxide, a fuel gas for a fuel cell can be obtained.

  The raw fuel often contains a sulfur compound as an impurity when it is derived from petroleum, and as an odorant for detecting leakage when it is natural gas or the like. When these raw fuels are used, it is inevitable that sulfur-containing compounds are mixed in the fuel hydrogen produced therefrom. In a fuel cell system, in each step of raw fuel reforming process for producing fuel hydrogen from raw fuel, removal of carbon monoxide in a gas containing hydrogen, and as a cathode electrode catalyst in power generation process, noble metal or copper A metal catalyst such as is often used in a reduced state. The sulfur compound acts as a catalyst poison for these metal catalysts, reduces the activity of the catalyst in the hydrogen production process or power generation process, and reduces the efficiency of the fuel cell system. Therefore, it is necessary to sufficiently remove sulfur contained in raw fuel so that the catalyst used in the hydrogen production process, and further the electrode catalyst in the power generation process can be used stably for a long time with its original performance. Indispensable.

  Since the concentration of sulfur in the raw fuel for fuel cells needs to be reduced to the extent that the catalyst used in the reforming process functions sufficiently, the desulfurization process for removing sulfur in the raw fuel is basically a hydrogen production process. It is provided before the process. Conventionally, the sulfur concentration in the raw fuel treated in the desulfurization process has been said to be 0.1 mass ppm or less or 0.05 mass ppm (50 mass ppb) or less as a sulfur atom. The required performance has become strict, and it has been required to be 0.02 mass ppm (20 mass ppb) or less.

  Conventionally, as a method for desulfurizing raw fuel for fuel cells, a hydrodesulfurization catalyst is used to hydrodesulfurize a difficult-to-desulfurize organic sulfur compound to convert it into hydrogen sulfide that can be easily adsorbed and removed, and then treated with an appropriate adsorbent. It has been considered that the method to do is suitable. However, while a general hydrodesulfurization catalyst requires high hydrogen pressure, in the field of fuel cell systems, since it aims at technical development that makes the hydrogen pressure atmospheric pressure or at most about 1 MPa, The current situation is that a desulfurization process using a hydrodesulfurization catalyst cannot be applied as it is.

As a desulfurization method in a fuel cell power generation system, for example, a method for producing hydrogen by steam reforming kerosene desulfurized with a nickel-based desulfurizing agent has been proposed (Patent Documents 1 and 2 below). Also, copper-zinc desulfurizing agents (Patent Documents 3 and 4 below), nickel-zinc desulfurizing agents (Patent Document 5 below), nickel-based desulfurizing agents with molybdenum added (Patent Document 6 below), activated carbon and zeolite It is proposed to use a desulfurizing agent (Patent Document 7 below) containing copper, silver, zinc, molybdenum, iron, cobalt, nickel, or a mixture thereof.
JP-A-1-188404 Japanese Patent Laid-Open No. 1-188405 JP-A-2-302302 JP-A-2-302303 JP 2001-62297 A JP 2007-254275 A JP-T-2006-511678

  However, even if it is a desulfurization agent of the above-mentioned patent documents 1-7, when it uses for a desulfurization process of raw fuel in low-pressure conditions or under non-coexistence of hydrogen in a fuel cell system which uses hydrocarbons as raw fuel However, there is a problem that sufficient desulfurization performance cannot be exhibited, or that the desulfurization performance decreases with long-term use. Therefore, when these desulfurization agents are used, it is difficult to stably operate the fuel hydrogen production process and power generation process at the latter stage of the desulfurization process for a long time. Note that the activity of the desulfurizing agent can be improved to some extent by raising the temperature in the desulfurization process, but in this case, the life of the desulfurizing agent is shortened due to the occurrence of coking due to the temperature rise, etc. It is not a solution. In addition, some of the conventional desulfurization agents show a certain degree of desulfurization performance against light hydrocarbons such as natural gas, LPG, naphtha, etc., but are not always sufficient for heavier kerosene. Not shown.

  The present invention has been made in view of such circumstances, and its purpose is to provide sufficient desulfurization performance even when desulfurizing raw fuel such as kerosene under low pressure conditions or in the absence of hydrogen. An object of the present invention is to provide a desulfurizing agent that can be maintained over a period of time, a method for producing the same, a desulfurizing method for kerosene using the desulfurizing agent, and a fuel cell system.

  In order to solve the above problems, the hydrocarbon desulfurization agent of the present invention comprises a porous inorganic oxide, nickel and / or nickel oxide, zinc oxide, cobalt and / or cobalt oxide, molybdenum and / or oxidation. Molybdenum, based on the total mass of the desulfurizing agent, in terms of oxide, the content of the porous inorganic oxide is 10 to 30% by mass, and the content of nickel and / or nickel oxide is 45 to 45%. It is 75 mass%, and the content of zinc oxide is 3 to 40 mass%.

  Since the hydrocarbon desulfurization agent of the present invention has the above-described configuration, it can be used not only for light hydrocarbons such as natural gas, LPG, and naphtha but also for heavier kerosene even under low pressure conditions or in the absence of hydrogen. For example, it has an effect of exhibiting sufficient desulfurization performance and maintaining the desulfurization performance over a long period of time.

  The hydrocarbon desulfurization agent of the present invention preferably further contains phosphorus oxide.

  Moreover, it is preferable that the hydrocarbon desulfurization agent of the present invention contains silica as a porous inorganic oxide.

  The method for producing a hydrocarbon desulfurization agent according to the present invention is a first method in which a coprecipitate is produced from a solution or suspension containing a nickel compound, a zinc compound and a porous inorganic oxide and / or a precursor thereof. A cobalt compound and a molybdenum compound are supported on the coprecipitate after washing in the step, the second step of sequentially washing, drying and firing the coprecipitate obtained in the step and the first step. A third step of obtaining a support, and drying and firing are sequentially performed on the support obtained in the third step, and a porous inorganic oxide, nickel and / or nickel oxide, zinc oxide, cobalt and / or Cobalt oxide and molybdenum and / or molybdenum oxide, the content of the porous inorganic oxide is 10 to 30% by mass in terms of oxide based on the total mass of the desulfurizing agent, and the nickel And / or a fourth step of obtaining a hydrocarbon desulfurization agent having a nickel oxide content of 45 to 75 mass% and a zinc oxide content of 3 to 40 mass%. To do.

  According to the method for producing a hydrocarbon desulfurization agent of the present invention, a desulfurization agent having excellent desulfurization performance as described above can be obtained effectively.

  In the third step, it is preferable to further carry a phosphorus compound on the coprecipitate.

  The solution or suspension in the first step preferably contains silica and / or its precursor as the porous inorganic oxide and / or its precursor.

  The present invention also provides a kerosene desulfurization method comprising contacting the hydrocarbon desulfurization agent of the present invention with a liquid phase kerosene.

  According to the kerosene desulfurization method of the present invention, the desulfurization performance of the hydrocarbon desulfurization agent of the present invention with respect to kerosene is further improved by bringing the hydrocarbon desulfurization agent of the present invention into contact with the liquid phase kerosene. Can be made.

The method for desulfurizing kerosene according to the present invention is to contact the desulfurizing agent and liquid kerosene as described above. The conditions in this case are as follows: temperature 0 to 400 ° C., pressure 0.1 to 1.1 MPa, liquid It is preferable to select within a range of a space velocity of 0.01 to 100 hr ⁻¹ .

  The present invention also includes a desulfurization section that desulfurizes the raw fuel by bringing the raw fuel containing hydrocarbons into contact with the hydrocarbon desulfurization agent of the present invention, and a modification that reforms the fuel desulfurized by the desulfurizer. A shift reaction unit that generates fuel gas by reducing carbon monoxide in the fuel after reforming by the reformer by a shift reaction, and a power generation unit that generates power using the fuel gas. A fuel cell system is provided.

  According to the fuel cell system of the present invention, since desulfurization of raw fuel in the desulfurization section is performed using the hydrocarbon desulfurization agent of the present invention, raw fuel such as kerosene is desulfurized under low pressure conditions or in the absence of hydrogen. Even in this case, sufficient desulfurization performance can be maintained for a long period of time. As a result, reforming by a reformer, reduction of carbon monoxide in a shift reaction unit and a selective oxidation reaction unit of carbon monoxide provided as necessary, and stable power generation with fuel gas in a power generation unit can be performed for a long time. It becomes possible.

  As described above, according to the present invention, even when raw fuel such as kerosene is desulfurized under low pressure conditions or in the absence of hydrogen, a desulfurization agent capable of maintaining sufficient desulfurization performance over a long period of time and A production method thereof, a method of desulfurizing kerosene using the desulfurizing agent, and a fuel cell system are provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The hydrocarbon desulfurization agent of the present invention (hereinafter also referred to as “the desulfurization agent of the present invention”) includes a porous inorganic oxide, nickel and / or nickel oxide, zinc oxide, cobalt and / or oxidation. Cobalt, molybdenum and / or molybdenum oxide, based on the total mass of the desulfurizing agent, the content of porous inorganic oxide is 10 to 30% by mass in terms of oxide, nickel and / or nickel oxide Is 45 to 75% by mass, and zinc oxide is 3 to 40% by mass. Here, the desulfurizing agent referred to in the present invention has a function of adsorbing a sulfur compound contained in a hydrocarbon, a function of converting a sulfur compound into a sulfur compound that is more easily adsorbed, and a converted one. Those having the function of adsorbing sulfur compounds and those having two or more of these functions are included.

  The content of nickel and / or nickel oxide (hereinafter collectively referred to as “nickel component”) contained in the desulfurizing agent of the present invention is 45 on the basis of the total mass of the desulfurizing agent in terms of nickel oxide (NiO). It is -75 mass%, Preferably it is 50-70 mass%. When the content is less than 45% by mass, the desulfurization performance becomes insufficient due to the insufficient amount of the nickel component. On the other hand, when the content exceeds 75% by mass, the content of the porous inorganic oxide is relatively reduced, the specific surface area of the desulfurizing agent is reduced, and the dispersion of the nickel component and the like is reduced. As a result, the desulfurization performance is insufficient.

  The content of zinc oxide contained in the desulfurizing agent of the present invention is 3 to 40% by mass, preferably 5 to 30% by mass, based on the total mass of the desulfurizing agent, as zinc oxide (ZnO). preferable. When the content is less than 3% by mass, when desulfurizing raw fuel such as kerosene, the production of carbonaceous material on the desulfurizing agent is suppressed by suppressing the formation of bicyclic aromatic compounds in the raw fuel. The effect of suppressing the zinc component is not sufficiently exhibited, and the desulfurization performance due to deposition of the carbonaceous material is likely to decrease with time. On the other hand, when it exceeds 40% by mass, the desulfurization performance becomes insufficient due to the relatively small content of nickel component and porous inorganic oxide.

  Content of a porous inorganic oxide is 10-30 mass% on the basis of the total mass of a desulfurization agent, Preferably it is 15-30 mass%. When the content is less than 10% by mass, the desulfurization performance becomes insufficient due to a decrease in the specific surface area of the desulfurization agent. On the other hand, when it exceeds 30 mass%, desulfurization performance becomes inadequate due to relatively low contents of nickel component and zinc component.

The content of molybdenum and / or molybdenum oxide contained in the desulfurizing agent of the present invention is 1 to 30% by mass based on the total mass of the desulfurizing agent in terms of molybdenum oxide (MoO ₃ ), preferably 2 to 2. 25% by mass. When the content is less than 1% by mass, the desulfurization performance decreases. On the other hand, when it exceeds 30 mass%, the dispersion state of a molybdenum component falls and desulfurization performance also falls.

  Moreover, content of cobalt and / or cobalt oxide is 0.1-10 mass% in the said reference | standard in conversion of cobalt oxide (CoO), Preferably it is 0.1-5 mass%. When the content is less than 0.1% by mass, the hydrodesulfurization performance decreases. On the other hand, when it exceeds 10 mass%, the dispersion state of a cobalt component will fall and desulfurization performance will fall too.

The desulfurizing agent of the present invention preferably contains phosphorus oxide in addition to the metal and / or metal oxide. By containing phosphorus oxide, the durability time during which desulfurization performance can be maintained is improved. The content of phosphorus oxide is preferably 0.01 to 10% by mass and more preferably 0.1 to 5% by mass in terms of niolin pentoxide (P ₂ O ₅ ). When the content is less than 0.01% by mass, the effect of adding phosphorus oxide tends not to be sufficiently obtained. On the other hand, when the content exceeds 10% by mass, no further improvement in the effect of addition is observed.

  The desulfurizing agent of the present invention contains a porous inorganic oxide. As the porous inorganic oxide, at least one of silica, alumina, boria, magnesia, zirconia, titania and manganese oxide, a mixture thereof, and a composite oxide composed of these components are preferably used. In particular, silica is preferable from the viewpoint of suppressing the deposition of a carbonaceous substance on the catalyst and improving the durability for maintaining the desulfurization performance.

  The method for producing the desulfurizing agent of the present invention is not particularly limited, and may be produced by a method in which other components are supported on the porous inorganic oxide by a method such as an impregnation method, and the porous inorganic oxide or a precursor thereof. In the presence of the body, by co-precipitation of these components from the solution containing the nickel component and zinc component, the resulting coprecipitate is loaded with a cobalt component, a molybdenum component and, if necessary, a phosphorus component by a method such as impregnation. It may be manufactured. From the viewpoint of obtaining an excellent dispersed state with a high nickel content, a method including a step of coprecipitation of the nickel component and the zinc component in the presence of the porous inorganic oxide or a precursor thereof is preferable. Hereinafter, this method will be described in detail.

  The step of co-precipitation of nickel and zinc components in the presence of a porous inorganic oxide is performed by mixing a porous inorganic oxide or a precursor thereof in an aqueous solution of a nickel compound and a zinc compound, and dropping a base into the mixture. Alternatively, a porous inorganic oxide or a precursor thereof is mixed in an aqueous base solution, and an aqueous solution of a nickel compound and a zinc compound is dropped into the mixed solution to form a coprecipitate composed of the nickel compound and the zinc compound as a porous inorganic material. Form on oxide.

  As the nickel compound and zinc compound, respective 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.

  Taking the case of using silica as the porous inorganic oxide as an example, at least one selected from silica powder, silica sol, and silica gel is preferably used. These average particle diameters are preferably 1 to 100 nm, more preferably 1 to 25 nm.

  As the base, an aqueous solution of ammonia, sodium carbonate, sodium hydrogen carbonate, potassium carbonate or the like can be used.

  A coprecipitate composed of a nickel compound and a zinc compound is formed on the porous inorganic oxide, and then the generated solid is filtered and washed with ion-exchanged water or the like. Insufficient washing leaves chlorine, nitrate radical, sulfate radical, acetate radical, sodium ion, potassium ion, etc. on the catalyst, which adversely affects the performance of the desulfurization agent. When ion-exchanged water cannot be sufficiently washed, an aqueous solution of a base such as ammonia, sodium carbonate, sodium hydrogen carbonate, or potassium carbonate may be used as the washing liquid. In this case, it is preferable to first wash the solid with an aqueous base solution and then wash with ion-exchanged water. In particular, since sodium ions adversely affect the performance of the desulfurization agent, it is desirable to perform washing until the residual sodium amount is 0.1% by mass or less, preferably 0.05% by mass or less.

  The solid after washing is pulverized and then dried. The drying method is not particularly limited, and examples thereof include heat drying in air, degassing drying under reduced pressure, and spray drying. When drying by heating in an air atmosphere, drying is preferably performed at 100 to 150 ° C. for 5 to 15 hours.

  After drying, firing is performed. The firing method is not particularly limited, and it is usually desirable to perform firing in an air atmosphere at 200 to 600 ° C., preferably 250 to 450 ° C. for 0.1 to 10 hours, preferably 1 to 5 hours. By firing, at least a part of the nickel component becomes nickel oxide and the zinc component becomes zinc oxide. In addition, when washing | cleaning of the solid substance after coprecipitation operation is inadequate, you may wash again after baking. In this case, ion-exchanged water or an aqueous solution of the above-mentioned base can be used. The composition containing nickel oxide / zinc oxide / porous inorganic oxide obtained as described above is hereinafter referred to as “coprecipitated fired product”.

  Next, a molybdenum component, a cobalt component, and, if necessary, a phosphorus component are supported on the coprecipitation fired product. As a loading method, a method of impregnating the coprecipitated fired product by a usual method using a solution in which each of the above components is dissolved, preferably an aqueous solution, is preferably employed. The solution of each component may be impregnated individually, or impregnation may be performed with a solution containing all components.

  As the molybdenum component contained in the impregnation solution, compounds such as molybdenum trioxide and ammonium molybdate are preferably used. As the cobalt component, compounds such as cobalt oxide, cobalt carbonate, cobalt nitrate, cobalt acetate, and cobalt chloride are preferably used. As the phosphorus component, various phosphoric acids are preferably used. When the solubility of the molybdenum component in the impregnating solution is low, it is preferable to add phosphoric acid to the solution in terms of improving the solubility. Alternatively, an organic acid such as malic acid may be added to the impregnation solution to improve the solubility of the molybdenum component.

  It is preferable that the impregnated material is dried and then calcined. Preferred methods and conditions for drying and firing are the same as those for drying and firing a solid obtained by coprecipitation from the nickel component, zinc component and porous inorganic oxide component.

  When the desulfurizing agent prepared by the above method is used, it can be used for desulfurization as it is, but it is preferable to perform a reduction treatment with hydrogen or the like as a pretreatment. The reduction treatment is carried out under a hydrogen flow at a temperature of 150 to 500 ° C., preferably 250 to 400 ° C., for 0.1 to 15 hours, preferably 2 to 10 hours.

  The shape of the desulfurizing agent of the present invention is not particularly limited, and the desulfurizing agent obtained as a powder may be used as it is, or may be formed into a molded product by tableting, or the molding thereof. The body may be sized to an appropriate range after pulverization. Furthermore, it can also be set as an extrusion molding. In molding, an appropriate binder may be added. The binder is not particularly limited, but alumina, silica, titania, zirconia, carbon black, or a mixture thereof is used. The addition amount of the binder is usually 30% by mass or less, preferably 10% by mass or less, based on the total mass of the desulfurizing agent and the binder. The lower limit of the addition amount is not particularly limited as long as it is an amount that can exhibit the function as a binder. The addition amount is usually 0.5% by mass or more, preferably 1% by mass or more. A molding aid made of an organic material can also be used.

  Examples of the hydrocarbon to be desulfurized using the desulfurizing agent of the present invention include natural gas, LPG, naphtha, and kerosene. Of these, kerosene is preferred.

  The kerosene used as a raw material in the method for desulfurizing kerosene of the present invention is a kerosene containing a sulfur content, and the sulfur content contained in the raw material kerosene is 0.1 to 30 ppm by mass, preferably 1 to 25 ppm by mass. More preferably, it is 5-20 mass ppm. The sulfur content in the present invention is a general term for various types of sulfur, inorganic sulfur compounds, and organic sulfur compounds that are usually contained in hydrocarbons, and the concentration is represented by the ratio of the mass of the sulfur atom to the mass of kerosene. . The lower the sulfur content contained in kerosene, the better. However, desulfurization of sulfur to less than 0.1 ppm by mass in a normal petroleum refining process is not preferable because it increases equipment costs and operating costs. On the other hand, when the sulfur content exceeds 30 mass ppm, the desulfurization agent of the present invention used in the desulfurization method of the present invention is not preferable because it cannot maintain the desulfurization performance in a short time. In addition, it is preferable that the kerosene used for general uses other than a fuel cell can be used as a raw material.

  In the method for desulfurizing kerosene according to the present invention, it is preferable that kerosene is brought into contact with the desulfurizing agent according to the present invention in a liquid phase. When kerosene is brought into contact with the desulfurization agent of the present invention in a gas phase or a gas-liquid mixed phase, the desulfurization performance is lowered in a short time due to deposition of the carbonaceous material on the desulfurization agent, which is not preferable. On the other hand, when kerosene is brought into contact with the desulfurization agent of the present invention in the liquid phase, deposition of carbonaceous substances is suppressed, and desulfurization performance is maintained for a long time.

The operating pressure in the desulfurization method of kerosene of the present invention is preferably a low pressure in the range of 0.1 MPa (normal pressure) to 1.1 MPa (absolute pressure) in consideration of the economy and safety of the fuel cell system. The pressure is preferably 0.7 MPa. The reaction temperature is not particularly limited as long as it lowers the concentration of sulfur, but it is preferable to work effectively from a low temperature in consideration of the start of the equipment, and also in consideration of the steady state. 0 ° C to 400 ° C is preferable. More preferably, 0 ° C to 300 ° C, particularly preferably 100 ° C to 260 ° C is employed. By selecting such conditions, kerosene can be kept in a liquid phase. If the LHSV is too high, the desulfurization efficiency is lowered. On the other hand, if the LHSV is too low, the apparatus becomes large. Preferably in the range of 0.01～15H ^-1 as LHSV, more preferably in the range of 0.05~5h ^-1, range 0.1～3H ^-1 it is particularly preferred. The desulfurization method of the present invention is characterized by sufficient desulfurization even in the absence of hydrogen, 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 kerosene.

  Although the form of the desulfurization apparatus used for the desulfurization method of this invention is not specifically limited, For example, a flow-type fixed bed system can be used. The shape of the desulfurization device can be any known shape depending on the purpose of each process, such as a cylindrical shape or a flat plate shape.

  In the desulfurization method of the present invention, the sulfur concentration of kerosene containing the above-described sulfur content can be reduced to 20 mass ppb or less under non-coexisting conditions of hydrogen. In addition, the value quantified by the gas chromatography (GC-SCD) method with a chemiluminescence sulfur detector is used for the sulfur content concentration here.

  It has been clarified that desulfurization of kerosene in the absence of hydrogen using the desulfurizing agent of the present invention proceeds by the following two mechanisms. That is, in the first mechanism, the sulfur compound in kerosene is adsorbed as it is to the desulfurizing agent of the present invention. On the other hand, in the second mechanism, hydrogen having high reactivity is generated from the hydrocarbon having a naphthene ring structure contained in kerosene by the dehydrogenation reaction by the catalytic action of the desulfurizing agent of the present invention. Due to the catalytic action of the desulfurizing agent, the sulfur compound in kerosene is converted to hydrogen sulfide by the hydrodesulfurization reaction, and the hydrogen sulfide is adsorbed by the desulfurizing agent of the present invention. When the desulfurizing agent of the present invention is used, the second mechanism is superior to the first mechanism, which is considered to enable the desulfurizing agent of the present invention to maintain high desulfurization performance for a long time. It is done.

  The kerosene desulfurized to a sulfur concentration of preferably about 20 mass ppb or less is then subjected to a reforming step, a shift reaction step, and a carbon monoxide selective oxidation step, if necessary, to convert the produced hydrogen-rich gas into a fuel cell. It can be used as a fuel.

The reforming process is not particularly limited, but steam reforming in which the raw material is reformed with steam at a high temperature on a catalyst, partial oxidation with an oxygen-containing gas, and steam and an oxygen-containing gas coexist. In such a system, autothermal reforming that performs a self-heat recovery type reforming reaction can be used. In addition, although the reaction conditions of a modification | reformation process are not limited, 200-1000 degreeC of reaction temperature is preferable, and 500-850 degreeC is especially preferable. The reaction pressure is preferably from normal pressure to 1 MPa, and particularly preferably from normal pressure to 0.2 MPa. LHSV is preferably 0.01 to 40 h ⁻¹ , particularly preferably 0.1 to 10 h ⁻¹ .

  The mixed gas containing carbon monoxide and hydrogen obtained by the reforming step can be used as a fuel for a fuel cell as it is in the case of a solid oxide fuel cell. Also, for fuel cells that require removal of carbon monoxide, such as phosphoric acid fuel cells and polymer electrolyte fuel cells, the mixed gas can be suitably used as a raw material for hydrogen for the fuel cell. .

The shift reaction step is a step of reacting carbon monoxide with water to convert it into hydrogen and carbon dioxide. Using the contained catalyst, the carbon monoxide content is reduced to 2 vol% or less, preferably 1 vol% or less, more preferably 0.5 vol% or less. Although the reaction conditions for the shift reaction are not necessarily limited by the reformed gas composition or the like used as a raw material, the reaction temperature is preferably 120 to 500 ° C, particularly 150 to 450 ° C. The pressure is preferably normal pressure to 1 MPa, particularly preferably normal pressure to 0.2 MPa. GHSV is preferably 100~50000h ^-1, especially 300～10000H ^-1 are preferred. In the shift reaction step, two reactors of a high temperature shift reactor and a low temperature shift reactor may be provided in series. A catalyst having iron-chromium as an active component is preferably used for the high temperature shift reactor, and a catalyst having copper-zinc as the active component is preferably used for the low temperature shift reactor. Usually, in the phosphoric acid fuel cell, the mixed gas in this state can be used as fuel.

In a polymer electrolyte fuel cell, since it is necessary to further reduce the carbon monoxide concentration, it is desirable to provide a step of further 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 method can be used. It is particularly preferable to use a carbon monoxide selective oxidation method. In the carbon monoxide selective oxidation step, a catalyst containing iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, zinc, silver, gold, etc. is used, and 0.5 to The carbon monoxide concentration is reduced by adding 10 moles, preferably 0.7-5 moles, more preferably 1-3 moles of oxygen and selectively converting carbon monoxide to carbon dioxide. Although the reaction conditions of this method are not limited, the reaction temperature is preferably 80 to 350 ° C, particularly preferably 100 to 300 ° C. The pressure is preferably normal pressure to 1 MPa, particularly preferably normal pressure to 0.2 MPa. GHSV is preferably 1000~50000h ^-1, especially 3000～30000H ^-1 are preferred. In this case, the carbon monoxide concentration can be reduced by reacting with the coexisting hydrogen simultaneously with the oxidation of carbon monoxide to generate methane.

  An example of the fuel cell system will be described below with reference to FIG.

  The raw fuel (kerosene) in the fuel tank 3 flows into the desulfurizer 5 through the fuel pump 4. At this time, if necessary, the hydrogen-containing gas from the carbon monoxide selective oxidation reactor 11 or the low temperature shift reactor 10 can be added. The desulfurizer 5 is filled with the desulfurizing agent of the present invention. The raw fuel desulfurized in the desulfurizer 5 is mixed with water from the water tank 1 through the water pump 2, then introduced into the vaporizer 6 and fed into the reformer 7.

  The reformer 7 is heated by a heating burner 18. Although the anode off gas of the fuel cell 17 is mainly used as the fuel for the heating burner 18, the raw fuel discharged from the raw fuel pump 4 can be supplemented as necessary. As the catalyst filled in the reformer 7, a catalyst containing a metal such as nickel, ruthenium, or rhodium can be used.

  The gas containing hydrogen and carbon monoxide produced in this way is passed through the high temperature shift reactor 9, the low temperature shift reactor 10, and the carbon monoxide selective oxidation reactor 11 in order, so that the carbon monoxide concentration is adjusted to the fuel cell. It is reduced to the extent that it does not affect the characteristics of

  The polymer electrolyte fuel cell 17 comprises an anode 12, a cathode 13, and a solid polymer electrolyte 14, and a fuel gas containing high-purity hydrogen obtained by the above method is provided on the anode side, and an air blower is provided on the cathode side. If necessary, air sent from 8 is introduced after appropriate humidification treatment (a 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 in which oxygen gas obtains electrons and protons to become water proceeds at the cathode. In order to promote these reactions, platinum black, activated carbon-supported platinum catalyst or platinum-ruthenium alloy catalyst or the like is used for the anode, and platinum black, activated carbon-supported platinum catalyst or the like is used for the cathode. Usually, both the anode and cathode catalysts are used in a composite with a porous catalyst layer together with polytetrafluoroethylene, a low molecular weight polymer electrolyte membrane material, activated carbon or the like as required.

  Next, polymer electrolytes known under trade names such as Nafion (registered trademark, manufactured by DuPont), Gore (registered trademark, manufactured by Gore), Flemion (registered trademark, manufactured by Asahi Glass), Aciplex (registered trademark, manufactured by Asahi Kasei), etc. The porous catalyst layer is laminated on both sides of the membrane to form an MEA (Membrane Electrode Assembly). Further, the fuel cell is assembled by sandwiching the MEA with a separator made of a metal material, graphite, carbon composite, etc., having a gas supply function, a current collection function, particularly an important drainage function in 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 discharged from the exhaust port 16.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
Example 1
36.9 g of nickel nitrate hexahydrate (commercial reagent grade) and 10.6 g of zinc nitrate hexahydrate (commercial reagent grade) are dissolved in ion-exchanged water, and 350 ml of an aqueous solution (hereinafter referred to as “A1 solution”). Got. On the other hand, 22.6 g of sodium carbonate (commercial reagent grade) is dissolved in ion-exchanged water, mixed with 23.4 g of commercially available silica sol (particle size: about 7 nm) (silica content: 16.0 g), "B1 liquid") was obtained. The A1 liquid and B1 liquid were mixed at 80 ° C. with stirring to form a precipitate. After washing the precipitate with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then fired at 300 ° C. for 3 hours to obtain a fired powder. The composition of the calcined powder was NiO / ZnO / SiO ₂ = 60.9 mass% / 17.4 mass% / 21.7 mass% in terms of oxide, and the residual Na was 0.05 mass% or less.

  Next, molybdenum and cobalt were supported on 15 g of the product by the following method. 2.2 g of molybdenum trioxide (special grade for commercial reagent) and 0.47 g of cobalt carbonate (special grade for commercial reagent) were dissolved in ion-exchanged water and impregnated and supported on a 80 ° C. hot water bath. The obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 300 ° C. for 3 hours.

The fired powder obtained was molded by an extrusion molding method to obtain a cylindrical desulfurization agent having a diameter of 1.0 mmφ, and 3 cm ³ of the desulfurization agent was filled in a flow-type reaction tube having a diameter of 1.27 cm, Reduction was performed at 360 ° C. for 5 hours. Subsequently, JIS No. 1 kerosene (sulfur content concentration) at a reaction temperature of 220 ° C. at which the kerosene is in a liquid phase, a reaction pressure of 0.25 MPa (gauge pressure), LHSV = 12.0 h ⁻¹ , and in the absence of hydrogen. : 4 mass ppm, aromatic content part: 19.0 vol%, bicyclic: 0.4 vol%, tricyclic: 0.1 vol%). The product oil was sampled downstream of the reaction tube, and the time for the sulfur content in the sampled product oil to break through 20 mass ppb was defined as 20 ppb breakthrough time. The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 1. The sulfur concentration in the product oil was quantified by gas chromatography with a chemiluminescence sulfur detector (GC-SCD) method.
(Example 2)
Nickel nitrate hexahydrate (commercial reagent special grade) 43.7 g and zinc nitrate hexahydrate (commercial reagent special grade) 5.3 g were dissolved in ion-exchanged water, and 350 ml of an aqueous solution (hereinafter referred to as “A2 liquid”). Got. On the other hand, 23.5 g of sodium carbonate (commercial reagent grade) is dissolved in ion-exchanged water, mixed with 23.4 g of commercially available silica sol (particle size: about 10 nm) (silica content: 16.0 g), "B2 liquid") was obtained. A2 liquid and B2 liquid were mixed at 80 degreeC, stirring, and precipitation was formed. After washing the precipitate with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then fired at 300 ° C. for 3 hours to obtain a fired powder. The composition of the calcined powder was NiO / ZnO / SiO ₂ = 70.3% by mass / 8.5% by mass / 21.2% by mass in terms of oxide, and the residual Na was 0.05% by mass or less.

  Next, molybdenum, cobalt, and phosphorus were supported on 15 g of the product by the following method. 0.6 g of molybdenum trioxide (special grade for commercial reagent), 0.1 g of cobalt carbonate (special grade for commercial reagent) and 0.1 g of phosphoric acid (special grade for 85% concentration commercial reagent) are dissolved in ion-exchanged water and placed on a water bath at 80 ° C. Was impregnated and supported. The obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 300 ° C. for 3 hours.

The obtained fired powder was shaped and reduced by the same method as in Example 1, and a desulfurization test of kerosene was performed under the same conditions as in Example 1. The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 1.
(Comparative Example 1)
By the same operation as in Example 1, a fired powder made of NiO / ZnO / SiO ₂ was obtained in the form of an oxide having the same composition as in Example 1.

The calcined desulfurization test was carried out under the same conditions as in Example 1 except that molybdenum and cobalt components were not supported on the obtained calcined powder and molded and reduced by the same method as in Example 1. . The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 1.
(Comparative Example 2)
In the same operation as in Example 2, a fired powder made of NiO / ZnO / SiO ₂ was obtained in the form of an oxide having the same composition as in Example 2.

The calcined desulfurization test was carried out under the same conditions as in Example 1 except that molybdenum and cobalt components were not supported on the obtained calcined powder and molded and reduced by the same method as in Example 1. . The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 1.
(Comparative Example 3)
By the same operation as in Example 1, a fired powder made of NiO / ZnO / SiO ₂ was obtained in the form of an oxide having the same composition as in Example 1.

  Next, molybdenum was supported on 15 g of the product by the following method. 2.1 g of molybdenum trioxide (commercial reagent special grade) was dissolved in ion-exchanged water and impregnated and supported on a 80 ° C. hot water bath. The obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 300 ° C. for 3 hours.

The obtained fired powder was shaped and reduced by the same method as in Example 1, and a desulfurization test of kerosene was performed under the same conditions as in Example 1. The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 2.
(Comparative Example 4)
In the same operation as in Example 2, a fired powder made of NiO / ZnO / SiO ₂ was obtained in the form of an oxide having the same composition as in Example 2.

  Next, molybdenum was supported on 15 g of the product by the following method. 2.1 g of molybdenum trioxide (commercial reagent special grade) was dissolved in ion-exchanged water and impregnated and supported on a 80 ° C. hot water bath. The obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 300 ° C. for 3 hours.

The obtained fired powder was shaped and reduced by the same method as in Example 1, and a desulfurization test of kerosene was performed under the same conditions as in Example 1. The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 2.
(Comparative Example 5)
Copper nitrate hexahydrate (commercial reagent special grade) 38.3 g and zinc sulfate hexahydrate (commercial reagent special grade) 5.3 g were dissolved in ion-exchanged water to make 350 ml (hereinafter referred to as “A3 solution”). ) 20.2 g of sodium carbonate (commercial reagent special grade) was dissolved in ion-exchanged water and mixed with 32.8 g of commercially available silica sol (particle size: about 7 nm) (silica content 22.4 g) to make 300 ml (hereinafter referred to as “B3 Liquid ”). The A3 liquid and B3 liquid were mixed at 80 ° C. with stirring to form a precipitate. After washing the precipitate with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then fired at 300 ° C. for 3 hours to obtain a fired powder. The composition of the baked powder was CuO / ZnO / SiO ₂ = 60.4% by mass / 8.7% by mass / 30.7% by mass in terms of oxide, and the residual Na was 0.05% by mass or less.

The obtained fired powder was shaped and reduced by the same method as in Example 1, and a desulfurization test of kerosene was performed under the same conditions as in Example 1. The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 2.
(Comparative Example 6)
Copper nitrate hexahydrate (commercial reagent special grade) 38.3 g was dissolved in ion-exchanged water to obtain 350 ml of an aqueous solution (hereinafter referred to as “A4 solution”). 17.9 g of sodium carbonate (commercial reagent special grade) is dissolved in ion-exchanged water and mixed with 42.2 g (silica content: 28.9 g) of a commercially available silica sol (particle size: about 7 nm) to make 300 ml (hereinafter referred to as “B4 Liquid ”). The A4 liquid and B4 liquid were mixed at 80 ° C. with stirring to form a precipitate. After washing the precipitate with ion-exchanged water, the obtained cake was pulverized, dried at 120 ° C. for 10 hours, and then fired at 300 ° C. for 3 hours to obtain a fired powder. The composition of the fired powder was CuO / SiO ₂ = 60.5% by mass / 39.5% by mass in terms of oxide, and the residual Na was 0.05% by mass or less.

  Next, molybdenum was supported on 15 g of the product by the following method. 2.1 g of molybdenum trioxide (commercial reagent special grade) was dissolved in ion-exchanged water and impregnated and supported on a 80 ° C. hot water bath. The obtained cake was pulverized, dried at 120 ° C. for 10 hours, and calcined at 300 ° C. for 3 hours.

  The obtained fired powder was shaped and reduced by the same method as in Example 1, and a desulfurization test of kerosene was performed under the same conditions as in Example 1. The composition of the desulfurizing agent and the 20 ppb breakthrough time are shown in Table 2.

From the results of Tables 1 and 2, it is clear that the desulfurizing agent of the present invention has an improved 20 ppb breakthrough time in the absence of hydrogen as compared with the conventional desulfurizing agent.
(Reference Examples 1-8)
In Reference Examples 1 to 8, each calcined powder having a NiO / ZnO / SiO ₂ composition was obtained in the oxide conversion shown in Table 3 as follows. In the same manner as in Example 1, a precipitate was formed by mixing an aqueous solution of nickel nitrate and zinc nitrate adjusted to a predetermined concentration and a solution obtained by mixing silica sol with an aqueous solution of sodium carbonate adjusted to a predetermined concentration. . Each obtained precipitate was washed, pulverized, dried and fired in the same manner as in Example 1, and each fired powder having each composition consisting of NiO / ZnO / SiO ₂ in terms of oxides shown in Table 3 Got.

  Next, the calcined powders of Reference Examples 1 to 8 were each formed into a disk tablet by a tableting method without supporting molybdenum and cobalt components, and this was roughly crushed, and the particle size was 1.2 by sieving. The hydrogen reduction treatment was performed in the metal tube by the same operation as in Example 1 except that the thickness was set to ˜2.0 mm and the reduction time was 3 hours. 0.2 g of each of the obtained desulfurizing agents was charged into a stainless steel autoclave reactor having an internal volume of 200 mL under a nitrogen atmosphere.

  Next, a model raw material in which benzothiophene (reagent special grade) was dissolved in normal dodecane (reagent special grade) so that the content as a sulfur atom on a solution basis was 200 ppm by mass was prepared. Then, 50 mL of this was charged into the autoclave reactor under a nitrogen atmosphere, heated to an internal temperature of 200 ° C., and reacted under stirring in a nitrogen atmosphere at normal pressure for 2 hours. After completion of the reaction, the reactor was cooled to room temperature, and the sulfur concentration in the reaction solution was quantified by the GC-SCD method, thereby calculating the amount of sulfur atoms adsorbed in each desulfurization agent. The results are shown in Table 3.

[Power generation test]
In the fuel cell system of FIG. 1, the desulfurizer 5 was filled with the desulfurization agent obtained in Example 1, and No. 1 kerosene (sulfur concentration: 27 mass ppm) was used as the fuel to conduct a power generation test. During the operation for 200 hours, the desulfurizer operated normally and no decrease in the activity of the desulfurizing agent was observed. The desulfurization conditions were a temperature of 220 ° C., 0.25 MPa (gauge pressure), no hydrogen flow, and LHSV = 0.5 h ⁻¹ . At this time, a catalyst mainly composed of ruthenium is used for steam reforming, and a shift reaction step (reactor 10) is performed under the conditions of S / C (steam / carbon ratio) = 3, temperature 700 ° C., and LHSV = 1h ^−1. Then, using a copper-zinc mixed oxide catalyst, under the conditions of 200 ° C. and GHSV = 2000 h ⁻¹ , in the carbon monoxide selective oxidation step (reactor 11), a catalyst containing ruthenium as a main component is used, and O ₂ / CO = 3. Operation was performed under conditions of a temperature of 150 ° C. and GHSV = 5000 h ⁻¹ . The fuel cell also operated normally and the electric load 15 was operated smoothly.

It is the schematic which shows an example of the fuel cell system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water tank 2 Water pump 3 Raw fuel tank 4 Raw fuel pump 5 Desulfurizer 6 Vaporizer 7 Reformer 8 Air blower 9 High temperature shift reactor 10 Low temperature shift reactor 11 Carbon monoxide selective oxidation reactor 12 Anode 13 Cathode 14 Polymer electrolyte 15 Electric load 16 Exhaust port 17 Polymer electrolyte fuel cell 18 Heating burner

Claims (9)

  A porous inorganic oxide, nickel and / or nickel oxide, zinc oxide, cobalt and / or cobalt oxide, molybdenum and / or molybdenum oxide, and oxide based on the total mass of the desulfurizing agent In terms of conversion, the content of the porous inorganic oxide is 10 to 30% by mass, the content of nickel and / or nickel oxide is 45 to 75% by mass, and the content of zinc oxide is 3 to 40%. A desulfurizing agent for hydrocarbons, characterized in that it is in mass%.   The hydrocarbon desulfurization agent according to claim 1, further comprising phosphorus oxide.   The hydrocarbon desulfurization agent according to claim 1 or 2, wherein silica is contained as the porous inorganic oxide. A first step of forming a coprecipitate from a solution or suspension containing a nickel compound, a zinc compound and a porous inorganic oxide and / or precursor thereof;
A second step of sequentially washing, drying and firing the coprecipitate;
A third step of obtaining a support by supporting a cobalt compound and a molybdenum compound on the coprecipitate after baking in the second step;
The support is sequentially dried and fired, and contains a porous inorganic oxide, nickel and / or nickel oxide, zinc oxide, cobalt and / or cobalt oxide, molybdenum and / or molybdenum oxide, The content of the porous inorganic oxide is 10 to 30% by mass, and the content of the nickel and / or nickel oxide is 45 to 75% by mass in terms of oxides based on the total mass of the desulfurizing agent. A fourth step of obtaining a hydrocarbon desulfurization agent having a zinc oxide content of 3 to 40% by mass;
A process for producing a hydrocarbon desulfurization agent, comprising:   The method for producing a hydrocarbon desulfurization agent according to claim 4, wherein a phosphorus compound is further supported on the coprecipitate in the third step.   6. The solution or suspension in the first step contains silica and / or a precursor thereof as the porous inorganic oxide and / or a precursor thereof. Method for producing a hydrocarbon desulfurization agent.   A method for desulfurizing kerosene, comprising contacting the hydrocarbon desulfurization agent according to any one of claims 1 to 3 with liquid phase kerosene. 8. The desulfurization agent and the kerosene are brought into contact under the conditions of a temperature of 0 to 400 [deg.] C., a pressure of 0.1 to 1.1 MPa, and a liquid space velocity of 0.01 to 100 hr < ^-1 >. Kerosene desulfurization method. A desulfurization section for desulfurizing the raw fuel by bringing the raw fuel containing hydrocarbon into contact with the hydrocarbon desulfurization agent according to any one of claims 1 to 3;
A reforming section for reforming fuel after desulfurization by the desulfurizer;
A shift reaction unit for generating fuel gas by reducing carbon monoxide in the fuel after reforming by the reformer by a shift reaction;
A power generation unit that generates power using the fuel gas;
A fuel cell system comprising:

Images