JP6701778B2 - Method for producing hydrogen by reforming hydrocarbons, apparatus for producing hydrogen, operating method for fuel cell, and operating apparatus for fuel cell - Google Patents

Description

  The present invention uses a hydrocarbon reforming catalyst to reform hydrocarbons such as methane with steam and convert them into gases such as hydrogen and carbon monoxide. The present invention relates to an apparatus, an operating method and an operating apparatus for a fuel cell using the hydrogen production method.

  Hydrogen is expected as a raw material for new energy, and is used in hydrogen production equipment for hydrogen stations, fixed fuel cell systems, etc., which are expected to spread to homes, small and medium-sized businesses, etc. On-site manufacturing is being considered. Currently, hydrogen stations and household fuel cells produce hydrogen from natural gas, LNG, city gas, LPG, kerosene, etc. as raw materials, but since catalysts carrying precious metal elements are generally used, It is a very expensive system.

  In order to popularize these hydrogen production systems, it is important to reduce the price of the production system, and among them, the price of the reforming catalyst for producing hydrogen from fuel occupies a large proportion. In other words, it is thought that reducing the amount of precious metals used and achieving lower prices together with further improving the performance of the reforming catalyst will lead to the promotion of the spread of hydrogen production systems. Therefore, there is a demand for a reforming catalyst in which the amount of the precious metal used is significantly reduced from a reforming catalyst using a noble metal, and a reforming catalyst using a less expensive element.

  As an inexpensive metal element, for example, nickel is one of the elements that has the possibility. Conventionally, a nickel/alumina-based catalyst (for example, refer to Patent Document 1) that is most often used as a hydrocarbon reforming catalyst has an alumina phase changed to an α-alumina phase in a high temperature region, and crystal growth also progresses. Therefore, there is a problem that the specific surface area of the catalyst sharply decreases, and the reaction activity correspondingly decreases.

  Further, since these catalysts contain a large amount of nickel and carbon deposition is likely to occur on the catalyst surface, potassium or calcium is often added as an alkaline component in order to prevent it (Patent Document 2, reference). In this case, there is a problem that the potassium compound is scattered in the reaction device, the pipe, and the like during the use of the catalyst, causing corrosion. In addition, the above catalyst has a large amount of nickel supported, but the degree of dispersion is low, and the active metal is coarsely deposited. Therefore, there is a problem that it is difficult to proceed with the reforming reaction at a high reaction rate, and when reforming a hydrocarbon containing a sulfur compound that has a poisoning effect, a stable reaction between the active metal and sulfur is required. Since a compound is produced and is greatly affected by sulfur poisoning, there is a problem that the catalytic activity is significantly reduced.

  On the other hand, a method using a heat-resistant carrier which is made into a composite oxide by adding other components to alumina has also been reported. For example, a substance prepared by impregnating alumina with lanthanum, lithium or strontium (see, for example, Patent Documents 3 to 5) and a substance prepared by coprecipitating hydroxides of rare earth salts with alumina (Patent Document 6). , Etc.), and a spinel-based substance obtained by adding magnesia to alumina and firing it (see Patent Document 7, etc.). All of these carriers are prepared on the assumption that a porous carrier is first prepared, and the nickel active ingredient is supported in the pores of the porous body by an impregnation method. Since there is a limit, it is inferior in terms of catalytic activity.

  As a conventional noble metal-based catalyst, a catalyst in which ruthenium, platinum, rhodium or the like is supported on alumina or the like as a catalyst carrier is known. These catalysts have the characteristic of suppressing the precipitation of carbon by utilizing the physical properties of the noble metal component, so that they have less carbon precipitation and maintain their activity more easily than the above nickel-based catalysts. .. However, since these catalysts also have a drawback that they are easily poisoned by sulfur compounds, a hydrocarbon having a sulfur compound reduced to a ppb level is usually subjected to a reforming reaction through a desulfurization step (see Patent Document 8). ..

  On the other hand, as a method for producing an oxide containing nickel, magnesium, and aluminum, a precipitation agent (mainly a hydrotalcite structure) is generated from an aqueous solution in which each metal component is dissolved, and then the material is fired. Is disclosed in Non-Patent Document 1 and Patent Document 9. The one disclosed in Non-Patent Document 1 reacts methane with oxygen by using a catalyst produced by using a precipitate from a solution containing nickel, magnesium, and aluminum as a partial oxidation catalyst of methane. Then, the method of manufacturing synthesis gas is proposed. Further, Patent Document 9 proposes a hydrocarbon reforming method for obtaining one or both of synthesis gas and hydrogen from a hydrocarbon raw material (gas and tar) containing a sulfur compound and a reforming substance. No mention is made of the effect when the hydrogen sulfide concentration contained in the raw material is higher than 0 ppm and lower than 20 ppm.

  Furthermore, due to the recent global warming problem, the use of biomass, which is one of the carbonaceous raw materials, has been attracting attention as an effective means of reducing carbon dioxide emissions, and researches on high-efficiency energy conversion of biomass have been conducted in various places. .. Further, from the viewpoint of securing energy resources in recent years, research on effective utilization of coal, which has been vigorously carried out in the past, has been reviewed for practical use.

  For the method of gasifying the tar generated by carbonization of the biomass in that, producing crude gas (unrefined gas) and utilizing the sensible heat, especially, the catalytic reforming reaction of tar using a catalyst is performed. Various investigations have been made centering on Patent Document 7 and the like, but like the decomposition reaction of the coal-derived tar, it is not always sufficient from the viewpoint of catalytic activity and catalyst regeneration.

  On the other hand, also in the fuel cell system, the hydrogen production process by reforming hydrocarbons is an important process in the fuel cell system, and also accounts for a large proportion in the cost of the entire device. A conventional fuel cell system is composed of, for example, a desulfurization process, a reforming reaction process, a shift reaction process, and a CO selective oxidation process as studied in Patent Document 10, and effectively uses exhaust heat and gas in the system. Etc. are also introduced, and a part of hydrogen after the CO selective oxidation step is added to the gas before desulfurization to carry out the hydrodesulfurization reaction. The added hydrogen becomes hydrogen sulfide by the desulfurization reaction.

Japanese Examined Patent Publication No. 59-044346 JP-A-58-076487 JP, 08-134456, A US Pat. No. 5,516,359 JP, 2000-054852, A JP, 2003-055671, A JP, 2005-053972, A JP, 2006-045049, A JP 2004-000900 A JP, 2004-082033, A

F. Basile et al. , Stud. Surf. Sci. Catal. , Vol. 119 (1998)

The technique described in Patent Document 9 is effective for a sulfur compound-containing source gas containing a large amount of hydrogen gas, but when a sulfur compound-containing source gas containing no hydrogen gas or only a small amount is used, It has been found by the study of the inventors that even when a raw material gas having a low sulfur compound content of 20 ppm or less is used, catalyst deterioration occurs during long-term use.
In view of the above-mentioned conventional state of the art, the present invention is more cost-effective than precious metal-based catalysts, for example, nickel, magnesium, and using a catalyst mainly composed of alumina, containing a sulfur compound such as hydrogen sulfide. Method for producing hydrogen by reforming hydrocarbon, hydrogen producing apparatus, and hydrogen producing method for suppressing catalyst deterioration due to sulfur poisoning when converting a raw material gas of a hydrocarbon to be used as a fuel such as hydrogen or carbon monoxide An object of the present invention is to provide an operating method and an operating device of a fuel cell using the method.

  The present inventors pay attention to a catalyst mainly containing nickel, magnesium, and alumina, which can reduce the cost as compared with an expensive noble metal-based catalyst, and the elements and compositions constituting the catalyst and the catalyst during the reaction. Focusing on the reactivity with the gas that comes in contact with the gas, the reforming method and the reforming device have been thoroughly studied.

  As a result, conventional catalyst loading methods have been used as a method for producing catalysts that convert tar and light hydrocarbons such as methane contained in and accompanying crude gas during the thermal decomposition of carbonaceous raw materials into chemical substances mainly containing hydrogen and carbon monoxide. Unlike the method, fine precipitation of active species metal is possible and high-speed reaction is possible, and since the precipitated active metal is firmly bound to the matrix (matrix), sintering (coarsening) is difficult and activity reduction can be suppressed. It has been found that the solid phase crystallization method having various characteristics such that the precipitated active species metal can be re-dissolved in the matrix again by firing and the sintering can be suppressed can be regenerated.

  Specifically, for example, nickel element, which is an active species, is previously compounded with alumina, magnesia, etc., which forms a matrix, and nickel metal is finely deposited on the oxide surface from the oxide matrix by a reduction treatment before the reaction on the cluster. In addition, by further containing hydrogen gas in the raw material gas, in an atmosphere of a high concentration of sulfur components that can become catalyst poisoning, from heavy hydrocarbons such as tar and light hydrocarbons such as methane, The present inventors have found that it is possible to suppress activity deterioration due to sulfur poisoning when converting to light chemical substances such as hydrogen and carbon monoxide, which led to the implementation of the hydrocarbon reforming method and reforming apparatus of the present invention. It is a thing.

(1) Using a steam reforming reaction catalyst, a source gas containing a sulfur compound and a hydrocarbon is reformed to generate a first reformed gas containing hydrogen and carbon monoxide from the hydrocarbon. A method for producing hydrogen by reforming hydrocarbons, which comprises a reforming step,
The catalyst for steam reforming reaction, a precipitant is added to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and to the precipitate, alumina powder and water, Alternatively, alumina sol is added and mixed to produce a mixture, and the mixture is produced by a catalyst production process including at least drying and calcination,
A part of the first reformed gas containing hydrogen generated in the hydrocarbon reforming step is returned to the raw material gas in the hydrocarbon reforming step, or hydrogen is newly added to the hydrocarbon reforming step. A method for producing hydrogen by reforming hydrocarbons, characterized by being introduced into a raw material gas in a quality process.
(2) The ratio of hydrogen in the initial raw material gas is less than 10 mol% with respect to the molar concentration of hydrocarbons in the raw material gas,
Before reforming, after returning a part of the first reformed gas containing the generated hydrogen into the raw material gas, or after newly introducing hydrogen into the raw material gas in the reforming step. The reforming of hydrocarbon according to (1), wherein the ratio of hydrogen in the raw material gas is 10 to 100 mol% with respect to the molar concentration of hydrocarbon in the raw material gas before the reforming. Method for producing hydrogen by.
( 3 ) The production of hydrogen by reforming hydrocarbons according to ( 1 ) or (2) , wherein the catalyst production step includes calcining the precipitate after the formation of the precipitate. Method.
( 4 ) The steam reforming reaction catalyst is produced by further adding a cerium compound to the mixed solution, and cerium oxide fine particles are present on the surface of the catalyst ( 1 ) to (3). A method for producing hydrogen by reforming the hydrocarbon according to any one of 1 .
( 5 ) The raw material gas containing the sulfur compound and hydrocarbon is selected from natural gas, LNG, shale gas, city gas, or LPG, (1) to ( 4 ). Of producing hydrogen by reforming hydrocarbons of.
( 6 ) The method further includes a shift reaction step of causing a shift reaction of the first reformed gas produced in the hydrocarbon reforming step to increase a ratio of hydrogen in the first reformed gas,
At least one of a part of the first reformed gas containing hydrogen generated in the hydrocarbon reforming step and a part of the second reformed gas after the shift reaction step is used as the hydrocarbon. The method for producing hydrogen by reforming hydrocarbon according to any one of (1) to ( 5 ), characterized in that the hydrogen is returned to the raw material gas in the reforming step.
( 7 ) The proportion of hydrogen in the initial source gas is less than 10 mol% with respect to the molar concentration of hydrocarbons in the source gas,
At least one of a part of the first reformed gas generated in the hydrocarbon reforming step and a part of the second reformed gas after the shift reaction step is reformed with the hydrocarbon. The ratio of hydrogen in the raw material gas before reforming after returning to the raw material gas in the step is 10 to 100 mol% with respect to the molar concentration of hydrocarbons in the raw material gas before reforming. ( 6 ) A method for producing hydrogen by reforming hydrocarbon according to ( 6 ).
( 8 ) A method for operating a fuel cell, which uses the method for producing hydrogen by reforming hydrocarbons according to ( 6 ),
Selective carbon monoxide for converting the carbon monoxide in the second reformed gas into carbon dioxide by passing the second reformed gas after the shift reaction step through a carbon monoxide selective oxidation reactor. Oxidation reaction step,
Further comprising a fuel cell operation step of operating the fuel cell by introducing the third reformed gas after the carbon monoxide selective oxidation reaction step into the polymer electrolyte fuel cell as a fuel gas,
At least one of a part of the second reformed gas after the shift reaction step and a part of the third reformed gas after the carbon monoxide selective oxidation reaction step is subjected to the carbonization. A method of operating a fuel cell, which comprises returning to the raw material gas in a hydrogen reforming step.
( 9 ) The ratio of hydrogen in the initial raw material gas in the method for producing hydrogen by reforming hydrocarbon is less than 10 mol% with respect to the molar concentration of hydrocarbon in the raw material gas,
In the hydrogen production method, at least one of a part of the first reformed gas generated in the hydrocarbon reforming step or a part of the second reformed gas after the shift reaction step, The ratio of hydrogen in the raw material gas before reforming after returning to the raw material gas in the hydrocarbon reforming step is 10 to 10 with respect to the molar concentration of hydrocarbons in the raw material gas before reforming. It is 100 mol%, The operating method of the fuel cell as described in ( 8 ) characterized by the above-mentioned.
( 10 ) A precipitation agent is added to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and alumina powder and water or alumina sol is added to the precipitate. Using a catalyst for steam reforming reaction produced by a catalyst production process comprising mixing and producing a mixture, and at least drying and calcining the mixture,
From a feed gas containing sulfur compounds and hydrocarbons, and reforming reaction unit to produce a first reformed gas containing hydrogen, carbon monoxide, carbon dioxide,
Shift reaction means for converting carbon monoxide contained in the first reformed gas into carbon dioxide,
A carbon monoxide selective oxidation reaction means for converting carbon monoxide contained in the second reformed gas after passing through the shift reaction means into carbon dioxide,
An apparatus for producing hydrogen, comprising means for circulating a part of hydrogen contained in at least one reformed gas after the shift reaction means or after passing through the carbon monoxide selective oxidation reaction means to the reforming reaction means.
( 11 ) The proportion of hydrogen in the initial source gas is less than 10 mol% with respect to the molar concentration of hydrocarbons in the source gas,
The raw material gas in the hydrocarbon reforming means has a means for circulating a part of hydrogen contained in at least one reformed gas after passing through the reforming reaction means or the shift reaction means to the reforming reaction means. And a control means for controlling the ratio of hydrogen in the raw material gas before reforming to 10 to 100 mol% with respect to the molar concentration of hydrocarbons in the raw material gas before reforming. ( 10 ) The hydrogen producing apparatus as described in ( 10 ).
(12) A precipitant is added to the mixed solution of the water supply means, the raw material gas supply means, and the nickel compound and the magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and to the precipitate, Hydrocarbons filled with a catalyst for steam reforming reaction produced by a catalyst production process including adding alumina powder and water or alumina sol and mixing them to produce a mixture, and at least drying and firing the mixture. A reformer, heating means for heating the reformer, a shift reactor, a carbon monoxide selective oxidation reactor, and a polymer electrolyte fuel cell operating device of a fuel cell,
Further, a pipe for introducing water supplied from the water supply means, a raw material gas containing a sulfur compound and hydrocarbons supplied from the raw material gas supply means into the reformer, and discharged from the reformer. A pipe for introducing a first reformed gas into the shift reactor, a pipe for introducing a second reformed gas discharged from the shift reactor into the carbon monoxide selective oxidation reactor, and A pipe for introducing the third reformed gas discharged from the carbon selective oxidation reactor into the polymer electrolyte fuel cell;
A heat exchanger for exchanging heat between the pipe introduced into the reformer and the pipe introduced into the shift reactor;
At least one of a part of the second reformed gas discharged from the shift reactor and a part of the third reformed gas discharged from the carbon monoxide selective oxidation reactor is treated with the water. And a pipe for introducing the raw material gas into a pipe for introducing the reformer into the reformer.

According to the present invention, even in a hydrogen sulfide-containing gas in which hydrogen is hardly contained in the raw material gas, the catalyst deterioration due to sulfur poisoning is constantly suppressed, and light hydrocarbons such as methane in the gas are converted to hydrogen. It becomes possible to convert into chemical substances such as carbon monoxide and carbon monoxide.
In particular, in natural gas, LNG, shale gas, city gas, LPG, etc., a light hydrocarbon such as methane in a gas containing hydrogen sulfide, which is a poisoning substance of the catalyst, and a chemical such as hydrogen or carbon monoxide. In a reforming method and a reforming apparatus for a hydrocarbon using a reforming catalyst having high activity and high carbon deposition resistance that can be converted into a substance, a part of generated hydrogen is circulated to a raw material gas for a reforming reaction. As a result, it becomes possible to constantly suppress the catalyst deterioration due to sulfur poisoning.

It is a schematic diagram showing an example of a fuel cell system using the hydrogen manufacturing method of the present invention.

Hereinafter, the present invention will be described in more detail with reference to specific examples.
The hydrocarbon reforming catalyst (also referred to as "steam reforming reaction catalyst") that can be used in the present invention has nickel as a functional catalyst as a main active component, and heavy hydrocarbons such as tar and methane. The light hydrocarbons can be used to catalyze the reforming reaction between water vapor and carbon dioxide existing in the gas or introduced from the outside.

The catalyst preferably contains (1) nickel, magnesium, cerium, and aluminum as constituent elements, (2) does not contain more than 5% by mass of an alumina phase (alumina as a single compound), and (3) at least one composite. It can be a metal oxide containing an oxide, and preferably mainly containing a crystal phase of NiMgO, MgAl ₂ O ₄ , and CeO ₂ .

  This catalyst has a large surface area because the above nickel metal is finely dispersed in clusters on the surface of the catalyst even in the presence of a high concentration of hydrogen sulfide, which becomes a catalyst poisoning substance, in the hydrocarbon-containing gas, Therefore, even if the active metal particles are poisoned during the reaction, the adsorbed sulfur or sulfided metal reacts with hydrogen during the reaction and is desorbed as hydrogen sulfide, or new active metal particles are finely precipitated from the matrix. Therefore, it is considered that it is unlikely to be affected by the activity reduction due to sulfur poisoning. From this matrix compound, active metal particles can be deposited in the form of fine clusters in a hydrogen reducing atmosphere.

  In addition, among the components such as alumina and magnesia compounded with nickel element, magnesia is a basic oxide, and by possessing the function of adsorbing carbon dioxide, it reacts with the precipitated carbon on the main active component element. It is thought that the catalyst surface can be kept clean and the catalyst performance can be stably maintained for a long period of time because it plays the role of oxidizing and removing as carbon monoxide.

Alumina functions as a binder for keeping the compound matrix stable, and also functions as a metal oxide containing NiMgO and a crystal phase of Ni _x Mg _1-x Al ₂ O ₄ as a catalyst, and contains a sulfur compound. Even if the hydrocarbon is reformed, the catalytic activity can be stably maintained for a long period of time. Here, the crystal phase of Ni _X Mg _1-X Al ₂ O ₄ coprecipitates from a mixed solution containing a nickel compound and a magnesium compound to form a hydrate precipitate, and after the precipitate is formed, aluminum precipitate is formed. Add and mix the components, dry and calcine, or by coprecipitation from a mixed solution containing a nickel compound, a magnesium compound and an aluminum compound, a hydrate precipitate is formed, and the precipitate is dried and calcined. This is the crystalline phase that can be obtained. These crystal phases cannot be distinguished by X-ray diffraction measurement or the like, but may be only NiAl ₂ O ₄ or MgAl ₂ O ₄ .

  In the present specification, the "light hydrocarbons" include C1-C4 methane, ethane, ethylene, propane, propylene, normal butane, isobutane, etc. contained in natural gas, LNG, shale gas, city gas, LPG, etc. Indicates a hydrocarbon. The higher the carbon number, the easier it is to decompose, so high activity can be obtained, but in reality, methane, ethane, and propane, which have a large content in the raw material gas such as natural gas, LNG, shale gas, city gas, and LPG, are used. Preferably. By circulating a part of the hydrogen after the reforming reaction in these raw material gases, the raw material gas can be stably converted into hydrogen, carbon monoxide or the like even when the raw material gas is brought into contact with the catalyst while containing the sulfur compound.

  Here, as a general sulfur compound concentration, mercaptans such as tertiary butyl mercaptan (TBM) and sulfides such as dimethyl sulfide (DMS) are used as odorants for city gas and LPG. Therefore, city gas and LPG contain sulfur compounds at a concentration of about 3 ppm or less. Natural gas also contains hydrogen sulfide of several to several tens of ppm, though it varies depending on the production area. It is considered that any of the sulfur compounds decomposes on the active site of the catalyst, and sulfur can become a poisoning substance.

  In the reforming reaction of light hydrocarbons such as methane, steam reforming reaction and dry reforming reaction proceed between light hydrocarbons and steam or carbon dioxide, and they are converted into gas mainly composed of hydrogen and carbon monoxide. It

  In the conventional hydrocarbon reforming reaction, the sulfur compounds contained in the raw material gas are reduced infinitely through a desulfurization process so that the activity of the reforming catalyst is not lowered by sulfur. Therefore, if there is no desulfurization step, even if only a few ppm of the sulfur compound is contained, the catalyst activity will be lost in a short period of time due to sulfur poisoning.

  In the method for producing hydrogen by reforming hydrocarbons according to the present invention, a part of the reformed gas containing hydrogen generated in the reforming step is returned to the raw material gas before the reforming step or new hydrogen is reformed. By adding to the raw material gas before the quality process, poisoning by sulfur can be suppressed. This is considered to be because the hydrogen contained in the raw material gas causes the sulfur adsorbed at the active site of the catalyst to react with hydrogen, resulting in the elimination of sulfur as hydrogen sulfide. It is thought that this is because it is possible to proceed in parallel. Further, in the fuel cell system, a part of the reformed gas after the shift reaction and the reformed gas after the carbon monoxide selective oxidation reaction in which the hydrogen concentration is further increased is fed into the raw material gas before the reforming process. It is more efficient to put it back.

  A part of the reformed gas containing hydrogen generated in the hydrocarbon reforming step, the shift reaction step, or the carbon monoxide selective oxidation reaction step is returned to the raw material gas in the hydrocarbon reforming step, or is newly added. When hydrogen is added to the raw material gas before the reforming process, the reformed gas after the reforming process (first reformed gas), the reformed gas after the shift reaction process (second reformed gas), The reformed gas (third reformed gas) after the selective oxidation reaction step, the total amount of hydrogen to be newly added, the molar concentration of hydrogen added is 10 to the molar concentration of hydrocarbons in the raw material gas. It is preferably 100 mol% (or 9 to 50 mol% as the hydrogen concentration in the raw material gas (hydrogen + hydrocarbon)), and 40 to 100 mol% (or the hydrogen concentration in the raw material gas (hydrogen + hydrocarbon)). 28.5-50 mol%) is more preferable. When the flow rate of hydrogen is the same as the flow rate of hydrocarbons in the raw material gas, 100 mol% (or 50% as the hydrogen concentration in the raw material gas (hydrogen + hydrocarbon)) with respect to the molar concentration of hydrocarbons in the raw material gas. Mol%) can be calculated. When the hydrocarbon concentration in the raw material gas is not known in advance, the hydrocarbon concentration can be measured using a hydrogen flame ionization detection method or the like. Further, when the hydrogen concentration in the raw material gas is not known in advance, it can be measured by gas chromatography or the like.

  When the molar concentration of hydrogen added is less than 10 mol% with respect to the molar concentration of hydrocarbons in the raw material gas, there is almost no effect of reducing sulfur poisoning by hydrogen, which is not preferable. In addition, when hydrogen is required at the latter stage of the whole system such as a fuel cell system, it is necessary to consider the efficiency of the whole system, but the molar concentration of added hydrogen is the molar concentration of hydrocarbons in the source gas. When the amount is more than 100 mol% with respect to the concentration, it is not preferable because it is necessary to circulate 25% by volume or more of the produced reformed gas in the raw material gas.

  The hydrocarbon reforming catalyst used in the present invention produces a precipitate by using a precipitant in a mixed solution of a nickel compound and a magnesium compound, and the alumina powder and water or alumina sol is added to the precipitate. The catalyst is preferably produced by mixing to form a mixture, and drying and calcining the mixture.

  Alternatively, in the hydrocarbon reforming catalyst used in the present invention, a precipitant is added to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and the precipitate is It is preferable that the catalyst is produced by calcining and adding the alumina powder and water or alumina sol to the calcined precipitate to form a mixture, and drying and calcining the mixture.

  Further, when cerium is contained in the hydrocarbon reforming catalyst, it is preferable to mix the cerium compound with the solution at the same timing as the nickel compound and the magnesium compound, but alumina powder and water, or alumina sol is added and mixed. The mixture may be formed by mixing and then impregnated with a cerium compound.

  Further, a hydrocarbon reforming catalyst used in the present invention is produced by using a precipitant in a mixed solution of a nickel compound, a magnesium compound and an aluminum compound to form a precipitate, and drying and firing the precipitate. May be.

  As a method of at least drying and baking the mixture, (1) a method of drying and baking, (2) a method of drying, crushing and baking, (3) a method of drying, crushing, molding and baking, (4) drying, There are methods of calcination, pulverization, molding and firing, or (5) methods of drying, pulverization, calcination, pulverization, molding and firing.

The mixture may be dried by any general drying method regardless of the temperature conditions and the drying means. If necessary, the dried mixture may be roughly crushed and then calcined. If the precipitate after drying remains powdery by drying using a fluidized bed or the like, coarse pulverization is not necessary.
In addition, it is preferable to remove water by filtration before drying the mixture, because the labor for subsequent drying can be reduced and the energy required for drying can be reduced. Furthermore, it is more preferable to wash the precipitate after filtration with pure water or the like because the amount of impurities can be reduced.

  Further, the firing of the above mixture can be performed in the air. The ambient temperature may be in the range of 700 to 1300°C. More preferably, the ambient temperature is 900 to 1150°C. If the calcination temperature is high, sintering of the mixture proceeds and the strength of the catalyst increases, but on the other hand, the specific surface area decreases and the catalyst activity decreases, so it is desirable to determine the balance between the two. After calcination, it can be used as a catalyst as it is, or it can be molded by press molding or the like and used as a molded product. A calcination and molding step can be added between the drying and firing, and a pulverization step can be added between the calcination and molding step if the mixture needs to be granulated before molding. it can. In that case, calcination may be performed in air at about 400 to 650° C., and molding may be performed by press molding or the like.

  The hydrocarbon reforming catalyst that can be used in the present invention is different from the one obtained by physically forming a coprecipitate of nickel and magnesium and then physically mixing alumina powder with the fired powder and molding and firing the mixture. , By wet mixing alumina powder and water, or alumina sol to the nickel and magnesium precipitate, the water containing the alumina component became a highly homogeneous mixture between the nickel and magnesia coprecipitate. Preferably obtained. The reason is that the mixture is dried and calcined, or dried, calcined, crushed, molded, and calcined to form a sintered body in which the compound of nickel and magnesium and alumina are uniformly distributed, and the nickel magnesia crystal phase is formed. It is considered that it is possible to obtain a molded product having a high activity and a small amount of carbon precipitation because the Ni particles are further refined and the Ni particles precipitated therefrom are highly finely dispersed. Also, a coprecipitate of nickel, magnesium and aluminum can be dried, molded and fired to form a sintered body in which nickel, magnesium and alumina are homogeneously distributed. Since it is finely dispersed, it is considered possible to obtain a molded product having high activity and a small amount of carbon deposition.

  More specifically, when preparing a mixed solution of a nickel compound and a magnesium compound, it is preferable to use each metal compound having high solubility in water. For example, not only inorganic salts such as nitrates, sulfates and chlorides, but also organic salts such as acetates are preferably used. Particularly preferred are nitrates or acetates, which are considered to leave little impurities that may poison the catalyst after calcination. As the precipitating agent used when forming a precipitate from those solutions, any precipitating agent can be used as long as it changes the pH of the above solution from neutral to basic in which nickel and magnesium are mainly precipitated as hydroxides to basic. be able to. Among them, potassium carbonate aqueous solution, sodium carbonate aqueous solution, ammonia aqueous solution, urea solution and the like are preferably used. Further, when coprecipitating aluminum at the same time, like nickel compounds and magnesium compounds, not only inorganic salts such as nitrates, sulfates and chlorides, which have high solubility in water, but also organic salts such as acetates. Is also preferably used. Particularly preferred are nitrates or acetates, which are considered to leave little impurities that may poison the catalyst after calcination.

  Furthermore, the hydrocarbon reforming catalyst used in the present invention preferably has a nickel content of 1 to 50 mass% as a main active component. When it is 1% by mass or more, nickel reforming performance can be sufficiently exhibited. When the content is 50% by mass or less, the contents of magnesium, cerium, and aluminum forming the matrix can be appropriately maintained, and the concentration of nickel metal deposited on the catalyst is high and avoids coarsening. it can. For this reason, it is possible to avoid performance deterioration over time under the reforming reaction conditions.

  The magnesium content is preferably 1 to 45% by mass. When the amount is 1% by mass or more, the property of the basic oxide of magnesia can be easily utilized, the carbon deposition of hydrocarbons can be suppressed, and the catalytic performance can be easily maintained for a long period of time. When it is 45% by mass or less, the content of other nickel, cerium, and aluminum can be appropriately maintained, and the reforming activity of the catalyst can be sufficiently exhibited. Further, when the magnesium content is less than 1% by mass, the nickel concentration in the solid solution of magnesium and nickel becomes high, so that the nickel particles precipitated from the solid solution phase are likely to be coarsened, and the nickel after the hydrocarbon reforming reaction The amount of carbon deposited on the catalyst tends to increase.

  The content of cerium is preferably 1 to 40% by mass. When the content is 1% by mass or more, it is possible to prevent the precipitation of nickel from nickel magnesia that is difficult to occur due to the oxygen storage capacity of cerium oxide. When the content is 40% by mass or less, the ratio of nickel, which is the main active component, and magnesia that suppresses carbon deposition can be maintained in an appropriate range, and the reforming activity of the catalyst can be sufficiently exhibited.

The content of alumina is preferably 5 to 60% by mass. If it is less than 5% by mass, the nickel magnesia (NiMgO) phase will be the main ceramics, and the proportion of the MgAl ₂ O ₄ phase will be small. When it is molded, the catalyst strength tends to be extremely low. If it exceeds 60% by mass, as a result, the proportion of nickel, which is the main active component, and magnesia that suppresses carbon deposition decreases, and there is a possibility that the reforming activity of the catalyst may not be sufficiently exhibited.

  The reforming catalyst has a nickel content of 1 to 35% by mass, a magnesium content of 1 to 35% by mass, a cerium content of 3 to 35% by mass, and a converted alumina content of 10 to 50% by mass. Is more preferable. Further, the alumina here can be added to the oxide of nickel and magnesium in the state of alumina powder or alumina sol, or can be added by coprecipitation with nickel and magnesium.

  When the alumina sol is added, it is preferable to use alumina particles having an average particle size of 100 nm or less. Alumina having such a particle size can be grasped from the particle size distribution using a laser diffraction type particle size distribution measuring device (for example, Mastersizer 3000 manufactured by Malvern Instruments Ltd.).

  In addition, when the alumina powder is added, it is preferable that the particle diameter be as small as possible, for example, an average particle diameter of 100 μm or less is suitable, and water and the like are added at the time of mixing and used in a slurry form. Also in this case, in order to confirm the particle size distribution of the alumina particle size, a Coulter type particle size distribution measuring device (for example, Multisizer 4 manufactured by Beckman Coulter, etc.) can be used in addition to the above-mentioned laser diffraction type particle size distribution measuring device.

Further, in order to adjust the content of each metal species to fall within the above range, it is preferable to prepare each starting material in advance by calculation. Note that once the catalyst has the target component composition, it may be prepared with the compounding amount at that time thereafter.
Further, in addition to the above-mentioned elements, unavoidable impurities mixed in during the catalyst manufacturing process or other components whose catalyst performance does not change may be contained, but it is desirable to prevent impurities from mixing in as much as possible.

  A method called an inductively coupled plasma method (ICP) can be used as a method for measuring the content of each metal species constituting the reforming catalyst. Specifically, after crushing the sample, an alkali melting agent (for example, sodium carbonate, sodium borate, etc.) is added to heat and melt in a platinum crucible, and after cooling, the whole amount is dissolved in a hydrochloric acid solution under heating. When the solution is inserted into an ICP analysis device, the sample solution is atomized and thermally excited in the high temperature plasma state inside the device, and when it returns to the ground state, an emission spectrum of a wavelength peculiar to the element is generated. Also, it is possible to qualitatively and quantitatively determine the contained element species and amount from the strength.

  Here, the reforming catalyst that can be used in the present invention may be in any form of powder or a molded body, and in the case of a molded body, a spherical shape, a cylindrical shape, a ring shape, a wheel shape, a granular shape. Etc., or a honeycomb substrate of metal or ceramics coated with a catalyst component. When used in a fixed bed, granulation, extrusion molding, press molding, tablet molding and the like are preferably used as the molding method, but the molding method is not particularly limited thereto.

  In addition, a method for reforming light hydrocarbons using a reforming catalyst that can be used in the present invention includes a natural gas, LNG, shale gas, city gas, and LPG after the catalyst is reduced or after the catalyst is reduced. It can be a method of reforming hydrocarbons by contacting light hydrocarbons such as methane contained in etc. with a mixed gas with steam added from the outside, producing hydrogen, carbon monoxide, carbon dioxide gas. can do.

  In the method for producing hydrogen of the present invention, it is preferable to reduce the reforming catalyst used. Also, by circulating a portion of the produced hydrogen into the raw material gas and mixing it with light hydrocarbons, the sulfur on the catalyst reacts with hydrogen during the reaction and is desorbed as hydrogen sulfide, so sulfur poisoning It is possible to suppress deterioration due to.

  On the other hand, in the reforming reaction of hydrocarbons, carbon deposition of hydrocarbons may occur on the catalyst surface, and the carbon deposition causes a decrease in activity due to pore clogging of the catalyst or surface coating. Normally, the steam/carbon ratio (S/C) is set to a high value so that such carbon precipitation does not occur, but even if the S/C is low and the carbon precipitation causes a decrease in activity, the The water vapor of the reaction can burn carbon. At that time, it is considered that the steam oxidizes nickel, which is the active metal of the catalyst, but the presence of hydrogen in the source gas can reduce the nickel.

  Here, the conditions for reducing the catalyst are not particularly limited as long as nickel particles, which are the active metal, are deposited in the form of fine clusters from the catalyst in a relatively high temperature and reducing atmosphere. For example, in a gas atmosphere containing at least one of hydrogen, carbon monoxide, and methane, in a gas atmosphere in which steam is mixed with the reducing gas, or in an atmosphere in which an inert gas such as nitrogen is mixed with these gases, Good.

  The reduction temperature is preferably 600°C to 1000°C, more preferably 700 to 900°C. Here, the catalyst layer temperature can be measured by inserting a K-type thermocouple near the center of the catalyst layer. The reduction time depends on the amount of the catalyst to be charged, and is preferably, for example, 30 minutes to 2 hours, but may be any time required for the reduction of the entire charged catalyst, and is not particularly limited to this condition. Absent.

  As the reforming reactor, a fixed bed type, a fluidized bed type, a moving bed type, etc. are preferably used, and in order to understand the temperature of the catalyst bed, depending on the size of the reactor, one to several points of K type are used. It is desirable to insert a thermocouple or the like to measure the temperature. The inlet temperature of the catalyst layer is preferably 600 to 950°C. If the inlet temperature of the catalyst layer is lower than 600° C., the catalytic activity when reforming the hydrocarbon into a gas mainly containing hydrogen and carbon monoxide is hardly exhibited, which is not preferable. On the other hand, if the inlet temperature of the catalyst layer exceeds 900° C., the reforming reactor and the apparatus become expensive because of the need for heat resistant structure, which is economically disadvantageous. Further, the inlet temperature of the catalyst layer is more preferably 650 to 900°C.

  Further, the reforming catalyst used in the present invention can stably proceed the reforming reaction even in an atmosphere in which a sulfur compound such as hydrogen sulfide coexists, but the lower the sulfur compound concentration in the gas, the lower the concentration. It is preferable because it is not poisoned. Particularly, a concentration of 10 ppm or less is preferable. Further, a concentration of 5 ppm or less is more preferable.

  On the other hand, the hydrocarbon reforming catalyst contained in the reforming reactor is such that when the hydrocarbon reforming reaction is carried out, the carbon deposited on the catalyst surface or the sulfur derived from the sulfur compound contained in the gas is the catalyst. The performance of the catalyst deteriorates due to the adsorption to nickel, nickel deposited as metal fine particles on the catalyst surface, or part of cerium oxide being sulfided.

  Therefore, as a method of regenerating the deteriorated catalyst, air is introduced into the reforming reactor, carbon on the catalyst surface is burned by the reaction between oxygen and carbon contained in the air, and is removed as carbon dioxide. It is possible to remove some of the sulfur in nickel and cerium oxide that have become sulfides as sulfur dioxide to return nickel to the matrix. Further, by contacting hydrogen with the catalyst to reduce it, the sulfur remaining on the catalyst surface can be reduced and removed as hydrogen sulfide, and at the same time, nickel metal fine particles can be precipitated from the matrix to restore the catalyst activity.

  Here, the temperature at which the catalyst and the air are brought into contact with each other is preferably such that the temperature of the catalyst layer measured by inserting a K-type thermocouple near the center of the catalyst layer is 500° C. or higher at which carbon can be burned. On the other hand, the temperature at which sulfur is oxidized and desorbed as sulfur dioxide needs to be 800° C. or higher, but unless the material of the reforming reactor or the pipe is made of an expensive heat-resistant alloy, the catalyst layer temperature is about 830 to protect the equipment. Since it is not possible to raise the temperature above 0°C, only a small amount of sulfur can be removed by regeneration with air.

Further, when the air is brought into contact with the catalyst on which carbon is deposited, the combustion of carbon is an exothermic reaction, so the catalyst temperature rises rapidly. It is not preferable to raise the temperature of the catalyst layer to about 830° C. or more in terms of equipment protection unless the material of the reforming reactor and the pipe is an expensive heat-resistant alloy. When the temperature of the catalyst layer is likely to reach 830° C. or higher due to heat generation, it is preferable to reduce the amount of introduced air or increase the amount of introduced nitrogen. Further, it is more preferable that the removal of carbon by air is performed at a catalyst layer temperature of 500 to 800°C. In this step, since it is only necessary to remove carbon, the carbon dioxide concentration at the outlet of the catalyst layer is monitored by an analyzer such as a mass spectrometer, gas chromatograph, infrared CO ₂ analyzer, etc., and the carbon dioxide concentration becomes 0.5% or less. If so, it can be judged that the carbon was almost removed.

After the removal of carbon deposits on the surface of the catalyst by the air is completed and after purging with an inert gas such as nitrogen, the temperature at which hydrogen is brought into contact with the catalyst and reduced is 600° C. or higher at which sulfur can be removed. preferable. Sulfur remaining on the catalyst after combustion with air can be desorbed sufficiently quickly as H ₂ S at a temperature of 600° C. or higher. This hydrogen reduction step is also preferably performed at 700° C. or higher for the purpose of precipitating nickel metal fine particles that become active species in the reforming reaction from the nickel magnesia phase, and the upper limit of the temperature is the removal of sulfur and the removal of nickel metal fine particles. Considering precipitation, 800° C. or lower is sufficient.

  On the other hand, it is possible to remove the deposited carbon and the sulfur on the catalyst by introducing water vapor instead of air, but it is much slower than the rate of removal by regeneration with air and reduction with hydrogen.

  Next, a fuel cell system using the hydrogen production apparatus of the present invention will be described in detail with reference to specific examples. FIG. 1 is a schematic diagram showing an example of a suitable fuel cell system of the present invention.

  In FIG. 1, fuel from a fuel supply source 3 is mixed with water from a water tank 1 through a water pump 2 through a fuel pump 4, and then introduced into a heat exchanger (vaporizer) 5 to be vaporized and modified. It is sent to the pouch 6.

  As the reforming catalyst of the reformer 6, a precipitation agent is used in a mixed solution of a nickel compound and a magnesium compound to form a precipitate, and alumina powder and water or alumina sol is added to and mixed with the precipitate. To produce a mixture, and the catalyst produced by drying and calcining the mixture is used. Alternatively, the reforming catalyst was prepared by adding a precipitant to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, calcining the precipitate, and calcining the precipitate. A catalyst produced by adding alumina powder and water or alumina sol to the precipitate and mixing them to form a mixture, and drying and calcining the mixture is used. Alternatively, the reforming catalyst comprises adding a precipitant to a mixed solution of a nickel compound, a magnesium compound and an aluminum compound to coprecipitate nickel, magnesium and aluminum to produce a precipitate, and drying and calcining the precipitate. The catalyst produced by

These catalysts are molded into a spherical shape, a cylindrical shape, a ring shape, a wheel shape, a granular shape, etc., and filled in the reformer. The steam/carbon ratio (S/C) sent to the reformer 6 is preferably set to 0.3 to 10, more preferably 1 to 5, and further preferably 2 to 3.5. The space velocity (SV) of the inflowing fuel (fuel + water vapor) is preferably GHSV (Gas Hourly Space Velocity) in terms of the catalyst amount of the above filling, standard temperature/pressure conversion, preferably 100 to 100000 h ^-1 , more preferably 500~50000h ^-1, more preferably set in a range of 1000~10000h ^-1. The reformer reaction tube is heated by the burner 7 using the fuel from the fuel tank and the anode off gas as fuel, and is preferably in the range of 400 to 1000°C, more preferably 500 to 900°C, and further preferably 600 to 800°C. Adjusted.

  The reformed gas containing hydrogen, carbon monoxide, and carbon dioxide produced in this manner is passed through the high temperature shift reactor 8, the low temperature shift reactor 9, and the carbon monoxide selective oxidation reactor 10 sequentially, The carbon monoxide concentration is reduced to such an extent that it does not affect the characteristics of the fuel cell. Examples of catalysts used in these reactors are an iron-chromium catalyst for the high temperature shift reactor 8, a copper-zinc catalyst for the low temperature shift reactor 9, and a ruthenium catalyst for the carbon monoxide selective oxidation reactor 10. Examples thereof include catalysts, platinum-based catalysts and gold-based catalysts.

  Here, in order to suppress the catalyst deterioration due to sulfur poisoning in the reforming reaction, a part of the reformed gas passes through the reformed gas circulation line 20 in the latter stage of the heat exchanger after the reforming reaction and before the reforming process. The hydrogen is returned to the raw material gas, or hydrogen is newly added from the hydrogen addition line 19 to the raw material gas before the reforming process (before the heat exchanger 5) and mixed. Alternatively, from the subsequent stage of the low temperature shift reactor 9 via the post-shift reaction gas circulation line 21 or from the subsequent stage of the carbon monoxide selective oxidation reactor 10 via the post-carbon monoxide selective oxidation reaction gas circulation line 22 A part of the quality gas is returned to and mixed with the raw material gas before the reforming process (before the heat exchanger 5). At least one of newly added hydrogen, a part of the reformed gas after the reforming reaction, a part of the reformed gas after the shift reaction, and a part of the reformed gas after the carbon monoxide selective oxidation reaction Although there is no problem even if it is used, it is preferable to effectively utilize the gas generated by the reaction rather than newly adding hydrogen. When the reformed gas after the shift reaction or the reformed gas after the selective oxidation reaction of carbon monoxide, which has a particularly high hydrogen concentration, is used, even if the return ratio is smaller than that after the reformed gas after the reforming reaction is used. It is preferable because the hydrogen concentration of the pre-reforming gas can be increased.

  In addition, a part of the reformed gas containing generated hydrogen, a part of the reformed gas after the shift reaction step, or a part of the reformed gas after the carbon monoxide selective oxidation reaction step is used to reform hydrocarbons. The molar concentration of hydrogen when returning to the raw material gas in the step or newly adding hydrogen to the raw material gas before the reforming step is the reformed gas after the reforming step, the reformed gas after the shift reaction step, The total amount of reformed gas and hydrogen newly added after the selective oxidation reaction step is 10 to 100 mol% (or the hydrogen concentration in the source gas (hydrogen + hydrocarbon)) with respect to the molar concentration of the hydrocarbon in the source gas. Is preferably 9 to 50 mol%), and more preferably 40 to 100 mol% (or 28.5 to 50 mol% as the hydrogen concentration in the source gas (hydrogen+hydrocarbon)). Here, when the flow rate of hydrogen is the same as the flow rate of hydrocarbons in the raw material gas, 100 mol% (or hydrogen in the raw material gas (hydrogen+hydrocarbon)) with respect to the molar concentration of hydrocarbons in the raw material gas. The concentration can be calculated as 50 mol %). If the hydrocarbon concentration in the gas is not known in advance, the concentration can be measured using a hydrogen flame ionization detection method or the like. If the hydrogen concentration is not known in advance, it can be measured by gas chromatography or the like. The hydrogen concentration is less than 10 mol% with respect to the molar concentration in the raw material gas (the proportion of hydrogen in the initial raw material gas, that is, the proportion of hydrogen gas originally present in the raw material gas is less than 10 mole %). If so, hydrogen has almost no effect of reducing sulfur poisoning, which is not preferable. Further, when the hydrogen concentration is more than 100 mol% with respect to the molar concentration in the raw material gas, it is necessary to circulate 25% by volume or more of the produced reformed gas, which is preferable considering the efficiency of the entire system. Absent.

  The solid polymer fuel cell 12 comprises an anode 13, a cathode 14, and a solid polymer electrolyte 15, and the fuel gas containing the high-purity hydrogen obtained by the above method is present on the anode side and the air is on the cathode side. The air sent from the blower 11 is introduced after performing an appropriate humidification treatment (a humidifier is not shown) if necessary.

  At this time, in the anode 13, a reaction in which hydrogen gas becomes a proton and releases an electron proceeds, and in the cathode 14, a reaction in which oxygen gas obtains an electron and a proton and becomes water proceeds. In order to accelerate these reactions, platinum black, Pt catalyst or Pt—Ru alloy catalyst supporting activated carbon, etc. are used for the anode 13, and platinum black, Pt catalyst supporting activated carbon, etc. are used for the cathode 14, respectively. Normally, both the anode and cathode catalysts are molded into a porous catalyst layer together with polytetrafluoroethylene, a low molecular weight polymer electrolyte membrane material, activated carbon, etc., if necessary.

  Next, polymer electrolyte membranes known by trade names such as Nafion (registered trademark) manufactured by DuPont, Gore Select (registered trademark) manufactured by Gore, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., and Aciplex (registered trademark) manufactured by Asahi Kasei Co., Ltd. The porous catalyst layers are laminated on both sides to form a 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, and particularly a drain function which is important for the cathode. The anode off gas is burned in the burner 7, used for heating the reforming tube, and then discharged. The cathode off gas is discharged from the exhaust port 16.

  Here, in the fuel cell system, if the desulfurization step is omitted, and if the reforming catalyst has sulfur poisoning resistance, it may adversely affect the downstream shift catalyst, carbon monoxide selective oxidation catalyst, anode, etc. There is. The copper-zinc catalyst used for the low temperature shift reaction catalyst is much cheaper than the reforming catalyst and has the ability to adsorb sulfur, and can serve as both the shift reaction at low temperature and the sulfur trap. When the shift reaction activity decreases, the low temperature shift reaction catalyst may be replaced.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the conditions in the Examples are one condition example adopted to confirm the feasibility and effects of the present invention. It is not limited to the example. The present invention can employ various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention. In addition, Example 8, Example 9, Example 10, Example 11, and Example 12 are reference examples.

<Experimental example 1>
(Comparative Example 1)
Precisely weigh 3.32 g of nickel nitrate hexahydrate and 26.38 g of magnesium nitrate hexahydrate so that the molar ratio of each metal element of nickel nitrate and magnesium nitrate is 0.1:0.9. Then, it was dissolved in 500 mL of pure water at 60° C. to prepare a mixed aqueous solution heated to 60° C. To this mixed aqueous solution, 15.8 g of potassium carbonate was precisely weighed, dissolved in 250 mL of pure water at 60° C., and the potassium carbonate aqueous solution heated to 60° C. was slowly added to about 250 mL/min to add nickel and magnesium to water. It was coprecipitated as an oxide and sufficiently stirred at about 400 rpm with a stirring blade. After that, stirring was continued for about 1 hour while maintaining the temperature at 60° C. for aging, suction filtration was performed, and washing and suction filtration were performed several times with pure water at 80° C. The temperature of each aqueous solution was measured by inserting an alcohol thermometer into the aqueous solution. For confirmation of washing, it can be confirmed that the pH of the filtrate is neutral with a portable pH meter or a pH test paper.

Then, the obtained precipitate was dispersed in pure water of about 400 mL of pure water, and alumina sol was added so as to be 50% by mass as alumina, and sufficiently mixed at about 350 rpm with a stirring blade. The mixture was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and heated at about 50° C. under reduced pressure to evaporate water. The mixture of nickel, magnesium and alumina solidified in the eggplant flask was transferred to an evaporation dish and dried at an ambient temperature of 120° C. for about 24 hours. Then, the mixture was crushed in a mortar, the powder was transferred to a crucible, and the mixture was baked at an atmospheric temperature of 950° C. in the air for about 20 hours to obtain about 10 g of a catalyst in which Ni _0.1 Mg _0.9 O was mixed with alumina at 50 mass %. The powder of the obtained catalyst was press-molded into a tablet of 20 mmφ using a pressure molding machine, and the press-molded body was roughly crushed to adjust the particle size to 0.5 to 1.0 mm using a sieve. The components of the obtained catalyst are shown in Table 1 together with the respective examples and comparative examples. However, with the total amount of the catalyst being 100% by weight, nickel and magnesium as the metal by weight and alumina as the oxide by weight% were shown. ing.

  Using 0.08 ml of the catalyst obtained above, the reaction tube made of quartz and having an inner diameter of 6 mmφ and a length of 500 mm was fixed by sandwiching it with quartz wool so as to be located at the center, and a sheath type K type catalyst was placed at the center of the catalyst layer. A thermocouple was inserted and these fixed bed reaction tubes were set at the center of the electric furnace.

Before starting the reforming reaction, first, the temperature of the catalyst layer was raised to 800° C. in a nitrogen atmosphere, and then reduction treatment was performed for 30 minutes while flowing hydrogen at 100 ml/min. Then, at 800° C., a city gas reforming reaction for a fuel cell was simulated to obtain a concentration of 14 ml of methane and 3 ppm of H ₂ S at atmospheric pressure, and the concentration of (steam mole number)/(carbon of methane above) An experiment was conducted for 24 hours at a reaction pressure of 0.1 MPa while introducing pure water as water vapor at 42 ml/min with a precision pump so that the number of moles)=3. Here, H ₂ S was used as a catalyst poisoning substance because of the ease of handling in experiments. The space velocity (SV: Space Velocity), which represents the gas introduction rate per catalyst volume under these conditions, is 40,000 h ^-1, which is about 10 times the flow rate of hydrogen production conditions in a normal fuel cell system, and accelerated test conditions. Becomes

  After removing the water content of the produced gas from the reforming reactor through an ice temperature trap, a TCD gas chromatograph (Yanaco G2800, column: inner diameter 2 mmφ, length 4 m, SHIN CARBON ST, column temperature 120° C., TCD detection Gas analysis was performed by using a container (140° C., Ar carrier). The activity of the reforming reaction was evaluated based on the methane conversion rate, and calculated from the concentration of each gas component in the outlet gas by the following formula. The reaction that occurs in the present invention produces hydrogen, carbon monoxide, and carbon dioxide from methane and steam.

Table 1 shows the element contents, H ₂ /(CH ₄ +H ₂ S), H ₂ /(H ₂ +CH ₄ +H ₂ S), and the methane conversion rate. Although the content (mass %) of each element shown in Table 1 is a calculated value, a method called an inductively coupled plasma method (ICP) can be used as a method for measuring an actually measured value. Specifically, after crushing the sample, an alkali melting agent (for example, sodium carbonate, sodium borate, etc.) is added to heat and melt in a platinum crucible, and after cooling, the whole amount is dissolved in a hydrochloric acid solution under heating. When the solution is inserted into an ICP analysis device, the sample solution is atomized and thermally excited in the high temperature plasma state inside the device, and when it returns to the ground state, an emission spectrum of a wavelength peculiar to the element is generated. Also, it is possible to qualitatively and quantitatively determine the contained element species and amount from the strength.

  Regarding the methane conversion rate in Comparative Example 1, as shown in Table 1, the methane conversion rate became 0% after 20 hours. It was also found that under the condition that the raw material gas does not contain hydrogen, the activity becomes zero in a short time due to sulfur poisoning.

(Example 1)
The same reduction treatment was performed using the same catalyst as in Comparative Example 1, and in the reforming reaction, the amount of methane, H ₂ S, and steam was unchanged, and the amount of H ₂ was changed relative to CH ₄ (H ₂ S: 3 ppm). H ₂ was introduced at a rate of 1.2 ml/min so that the total amount was 9 mol %. Therefore, the same procedure as in Comparative Example 1 was performed except that the SV was 40500 h ⁻¹ . As a result, as shown in Table 1, the methane conversion was 0 mol% after the reaction for 22 hours, but the life was slightly extended.

(Example 2)
Under the same conditions as in Example 1, the amount of _{H 2 CH 4 (H 2 S} : 3ppm) changed so that the proportion of 14 mol% with respect to, the introduction of H ₂ in 2 ml / min. Therefore, the same procedure as in Comparative Example 1 was performed except that the SV was 41,000 h ^-1 . As a result, as shown in Table 1, the methane conversion rate after the reaction for 24 hours was significantly improved to 41.5 mol %.
It was found that the molar concentration of H ₂ is preferably 0.1 times or more that of the source gas (CH ₄ ).

(Example 3)
Under the same conditions as in Example 1, the amount of CH ₄ in _{H 2 (H 2 S: 3ppm} ) changed so that the proportion of 43 mol% with respect to, the introduction of H ₂ at 6.0 ml / min. Therefore, the same procedure as in Comparative Example 1 was performed except that the SV was 44000 h ⁻¹ . As a result, as shown in Table 1, it was found that the methane conversion rate was further improved to 48.2 mol% as compared with Example 2, and sulfur poisoning was suppressed.

(Example 4)
Under the same conditions as in Example 1, the amount of _{H 2 CH 4 (H 2 S} : 3ppm) changed so that the proportion of 100 mol% relative to, and H ₂ introduced at 14.0 ml / min. Therefore, the same procedure as in Comparative Example 1 was performed except that the SV was 50000 h ⁻¹ . As a result, as shown in Table 1, it was found that the methane conversion rate was further improved to 58.2 mol% as compared with Example 2 and sulfur poisoning was suppressed.

(Example 5)
Under the same conditions as in Example 1, the amount of CH ₄ in _{H 2 (H 2 S: 3ppm} ) changed so that the proportion of 150 mol% relative to, and H ₂ introduced at 21.0 ml / min. Therefore, the same procedure as in Comparative Example 1 was performed except that the SV was 55,000 h ⁻¹ . As a result, as shown in Table 1, the methane conversion was further improved to 58.8 mol% as compared with Example 2, but it was found that sulfur poisoning can be suppressed at a level almost equal to that in Example 4. However, considering the effective use of the generated H ₂ , it is desirable that the amount of H ₂ introduced is equal to or less than the amount of the raw material gas introduced, because circulating excess H ₂ also leads to energy loss. It was

<Experimental example 2>
(Example 6)
In Example 3, the catalyst was prepared by mixing Ni _0.1 Mg _0.9 O with alumina in an amount of 10% by mass, the raw material gas was 12 ml of city gas, and the number of (steam moles)/(moles of carbon in city gas)=3. While introducing pure water as water vapor with a precision pump at 42 ml/min, H ₂ was introduced at 5.2 ml/min so that the amount of H ₂ was 43 mol% with respect to city gas. Evaluations were carried out under the same conditions as in Example 3 except that the experiment was carried out at a reaction pressure of 0.1 MPa for 50 hours.

Table 2 shows the content of elements, H ₂ /city gas, H ₂ /(H ₂ +city gas), and methane conversion rate in city gas. Here, the components of city gas include TBM in addition to 89.6 mol% of methane, 5.6 mol% of ethane, 3.4 mol% of propane, 1.4 mol% of butane. As a result, it was found that even after 50 hours, the methane conversion rate in city gas could be kept at 65.4 mol %, sulfur poisoning could be suppressed, and high activity could be retained.

(Comparative example 2)
In Example 6, except that no H ₂ introduced to the raw material gas was performed in the same manner as in Example 6. As a result, it was confirmed that the catalyst activity became zero at 42 h.

<Experimental example 3>
(Comparative example 3)
In the catalyst preparation, nickel nitrate hexahydrate and 2.63 g of nickel nitrate hexahydrate and cerium nitrate were used so that the molar ratio of each metal element of nickel nitrate, cerium nitrate and magnesium nitrate was 0.1:0.1:0.8. -3.92 g of hexahydrate and 18.54 g of magnesium nitrate hexahydrate were precisely weighed and dissolved in 500 mL of pure water at 60°C to prepare a mixed aqueous solution heated to 60°C. To this mixed aqueous solution, 12.5 g of potassium carbonate was precisely weighed, dissolved in 250 mL of pure water at 60° C., and the potassium carbonate aqueous solution heated to 60° C. was slowly added at about 250 mL/min to add nickel, cerium, magnesium. Was co-precipitated as a hydroxide and sufficiently stirred at about 400 rpm with a stirring blade. After that, stirring was continued for about 1 hour while maintaining the temperature at 60° C. for aging, suction filtration was performed, and washing and suction filtration were performed several times with pure water at 80° C. The temperature of each aqueous solution was measured by inserting an alcohol thermometer into the aqueous solution. For confirmation of washing, it can be confirmed that the pH of the filtrate is neutral with a portable pH meter or a pH test paper.

Then, the obtained precipitate was dispersed in pure water of about 400 mL of pure water, and alumina sol was added so as to be 50% by mass as alumina, and sufficiently mixed at about 350 rpm with a stirring blade. This mixture was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and heated at about 50° C. under reduced pressure to evaporate water. The mixture of nickel, cerium, magnesium and alumina solidified in the eggplant flask was transferred to an evaporation dish and dried at an ambient temperature of 120° C. for about 24 hours. Then, after crushing in a mortar, the powder was transferred to a crucible and fired at an atmospheric temperature of 950° C. for about 20 hours to obtain about 10 g of a catalyst in which Ni _0.1 Ce _0.1 Mg _0.8 O was mixed with 50% by mass of alumina. The obtained catalyst powder was press-molded into tablets of 20 mmφ using a pressure molding machine, and the press-molded body was roughly crushed to adjust the particle size to 0.5 to 1.0 mm using a sieve. The components of the obtained catalyst are shown in Table 3, and the total amount of the catalyst is 100% by mass, and the mass% of nickel, cerium, and magnesium as the metal and the mass% of alumina as the oxide are shown.

  The catalyst thus obtained was subjected to a reforming reaction in the same manner as in Comparative Example 1. As a result, as shown in Comparative Example 3 in Table 3, the conversion rate became zero at the time of reaction for 15 hours. Although the details are unknown, it is known that cerium adsorbs water vapor preferentially, and oxygen derived from water vapor promotes the oxidation of nickel, which is an active metal, and synergizes with the deterioration due to sulfur poisoning, resulting in activity deterioration. Is believed to have accelerated.

(Example 7)
Using the catalyst containing cerium prepared in Comparative Example 3, the reaction was carried out under the same conditions as in Example 4. As a result, as shown in Table 3, it was found that the methane conversion rate was improved to 59.5 mol% and sulfur poisoning could be suppressed.

<Experimental example 4>
(Example 8)
In preparing the catalyst, 3.32 g of nickel nitrate hexahydrate and magnesium nitrate were used so that the molar ratio of each metal element of nickel nitrate, magnesium nitrate, and aluminum nitrate was 0.054:0.485:0.462.・26.38 g of hexahydrate and 36.79 g of aluminum nitrate nonahydrate were precisely weighed and dissolved in 500 mL of pure water at 60°C to prepare a mixed aqueous solution heated to 60°C. To this mixed aqueous solution, 29.4 g of potassium carbonate was precisely weighed, dissolved in 250 mL of pure water at 60° C., and the potassium carbonate aqueous solution heated to 60° C. was slowly added to about 250 mL/min to add nickel, magnesium, and aluminum. Was co-precipitated as a hydroxide and sufficiently stirred at about 400 rpm with a stirring blade. After that, stirring was continued for about 1 hour while maintaining the temperature at 60° C. for aging, suction filtration was performed, and washing and suction filtration were performed several times with pure water at 80° C. The temperature of each aqueous solution was measured by inserting an alcohol thermometer into the aqueous solution. For confirmation of washing, it can be confirmed that the pH of the filtrate is neutral with a portable pH meter or a pH test paper.

After that, the obtained precipitate was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and heated to about 50° C. under reduced pressure to evaporate water. The mixture of nickel, magnesium and alumina solidified in the eggplant flask was transferred to an evaporation dish and dried at an ambient temperature of 120° C. for about 24 hours. Then, after crushing in a mortar, the powder is transferred to a crucible and fired at an atmospheric temperature of 950° C. for about 20 hours in the air, and the same molar number of nickel as the catalyst obtained by mixing 50% by mass of alumina with Ni _0.1 Mg _0.9 O. About 10 g of a catalyst containing magnesium, magnesium and aluminum was obtained. The powder of the obtained catalyst was press-molded into a tablet of 20 mmφ using a pressure molding machine, and the press-molded body was roughly crushed to adjust the particle size to 0.5 to 1.0 mm using a sieve. The components of the obtained catalyst are shown in Table 3, and the total amount of the catalyst is 100 mass %, and the mass% of nickel and magnesium as the metal and the mass% of alumina as the oxide are shown.

  The catalyst thus obtained was subjected to a reforming reaction in the same manner as in Example 4. As a result, as shown in Example 8 of Table 4, it was found that the conversion was 55.6 mol% at the time of reaction for 24 hours, and that sulfur poisoning could be suppressed as in Example 4.

(Example 9)
In the preparation of the catalyst of Example 8, nickel nitrate hexahydrate was mixed with nickel nitrate hexahydrate so that the molar ratio of each metal element of nickel nitrate, magnesium nitrate and aluminum nitrate was 0.091:0.822:0.087. 983 g, 47.479 g of magnesium nitrate hexahydrate, 7.358 g of aluminum nitrate nonahydrate were precisely weighed, and the same molar number as the catalyst obtained by mixing 10% by mass of alumina with Ni _0.1 Mg _0.9 O was used. About 10 g of a catalyst containing nickel, magnesium and aluminum was obtained.

  The catalyst thus obtained was subjected to a reforming reaction in the same manner as in Example 4. As a result, as shown in Example 9 of Table 4, the conversion was 91.4 mol% at the time of 24 h reaction and 63.4 mol% at the time of 60 h reaction, and sulfur poisoning can be suppressed and high activity can be maintained. all right.

<Experimental example 5>
(Comparative example 4)
The aqueous solution of nickel nitrate was impregnated in alumina powder to 20% by mass, and the oxide was transferred to an evaporation dish and dried at 120° C. for about 24 hours. Then, the powder was transferred to a crucible and dried in air at 500° C. for about 20 hours. A reaction test was conducted in the same manner as in Comparative Example 1 except that the nickel/alumina catalyst was obtained by performing time calcination. The amount of Ni supported was 20% by mass. As a result, as shown in Comparative Example 4 in Table 5, the conversion rate became zero at the time of the reaction for 10 hours. It has been found that, in the conventional catalyst, if H ₂ is not mixed with the raw material gas, even if Ni is contained in an amount of 20 mass %, it is deteriorated in a short time due to sulfur poisoning.

(Example 10)
The aqueous solution of nickel nitrate was impregnated in alumina powder to 20% by mass, and the oxide was transferred to an evaporation dish and dried at 120° C. for about 24 hours. Then, the powder was transferred to a crucible and dried in air at 500° C. for about 20 hours. A reaction test was performed in the same manner as in Example 4 except that the nickel/alumina catalyst was obtained by performing time calcination. The amount of Ni supported was 20% by mass. As a result, as shown in Example 10 in Table 5, it was found that 41 mol% was maintained even at the time of the reaction for 24 hours and remained almost constant thereafter. By mixing of H ₂ in the feed gas, sulfur adsorbed on Ni is promoted desorption as H _{2 S} by H _2, it is considered because poisoning is suppressed during the reaction.

(Comparative Example 5)
Aqueous acetylacetonatoluthenium solution was transferred to alumina powder, and the oxide that had been impregnated to 1% by mass was transferred to an evaporation dish and dried at 120°C for about 24 hours. Evaluation was carried out under the same conditions as in Comparative Example 1 except that the Ru/alumina catalyst was obtained by calcining for about 20 hours. As a result, as shown in Table 6, the methane conversion rate was 11.3 mol %. Since it is a noble metal, it has higher activity than that of Comparative Example 1, but activity deterioration due to sulfur poisoning occurred similarly.

(Example 11)
A Ru/alumina catalyst was obtained in the same manner as in Comparative Example 5, and a reaction test was conducted in the same manner as in Example 4. As a result, as shown in Table 6, the methane conversion was 38.2 mol%. It was found that the same effect can be obtained with the noble metal catalyst.

(Comparative example 6)
The acetylacetonato platinum aqueous solution was transferred to an alumina powder by impregnating the oxide with 1% by mass into an evaporation dish and dried at 120°C for about 24 hours, and then the powder was transferred to a crucible at 500°C in air. Evaluation was carried out under the same conditions as in Comparative Example 1 except that Pt/alumina catalyst was obtained by carrying out calcination for about 20 hours. As a result, as shown in Table 7, the methane conversion rate was 15.3 mol %. Since it is a noble metal, it has higher activity than Comparative Example 1, but activity deterioration due to sulfur poisoning occurred similarly.

(Example 12)
A Pt/alumina catalyst was obtained in the same manner as in Comparative Example 5, and a reaction test was conducted in the same manner as in Example 4. As a result, as shown in Table 7, the methane conversion rate was 46.2 mol%. It was found that the same effect can be obtained with the noble metal catalyst.

<Experimental example 6>
(Example 13)
In Example 4, the catalyst was prepared by mixing Ni _0.1 Mg _0.9 O with 10% by mass of alumina, and propane gas (98 mol% of propane, 0.4 mol% of ethane, 1.6 mol% of isobutane, and sulfur) was used as a raw material gas. Minute water is introduced by a precision pump as water vapor at 51.5 ml/min so that 5.7 ml of (8 ppm) and (molar number of water vapor)/(molar number of carbon in the above simulated city gas)=3, The experiment was conducted at a reaction pressure of 0.1 MPa for 24 hours. Here, 8 ppm of sulfur was added to the propane gas as an odorant. Furthermore, except that H ₂ was introduced at 5.7 ml/min so that the amount of H ₂ was 100 mol% with respect to propane gas, and the experiment was performed at a reaction pressure of 0.1 MPa for 50 hours. All were performed and evaluated under the same conditions as in Example 4.

Table 8 shows the element contents, H ₂ /propane gas, H ₂ /(H ₂ +propane gas), and the propane conversion rate. As a result, it was found that the propane conversion could be maintained at 58.3 mol% even after 50 hours, and sulfur poisoning was suppressed and high activity could be maintained by adding H ₂ even if the raw material was propane gas.

(Comparative Example 7)
In Example 13, except that no H ₂ introduced to the raw material gas was performed in the same manner as in Example 13. As a result, it was confirmed that the activity became zero at 45 hours.

<Experimental example 7>
(Example 14)
In the fuel cell system having the configuration shown in FIG. 1, a test was conducted using city gas as a fuel. At this time, the reformer 6 was filled with the catalyst used in Example 6, the raw material gas to be introduced had a (water vapor mole number)/(carbon mole number in city gas) of 3, and further, monoxide A part of the gas after the carbon selective oxidation reaction was circulated so that the amount of H ₂ was 43 mol% with respect to the city gas, and the SV was set to 3000 h ⁻¹ . Further, the high temperature shift reactor and the low temperature shift reactor are filled with Fe ₂ O ₃ /Cr ₂ O ₃ catalyst and Cu/ZnO catalyst, and the carbon monoxide selective oxidation reactor is filled with Ru/Al ₂ O ₃ catalyst. Filled. Analysis of the gas at the anode inlet showed that it contained 75% hydrogen (excluding steam). During the test period (500 h), the reformer operated normally, no reduction in catalyst activity was observed, and the fuel cell also operated normally.

(Comparative Example 8)
In the fuel cell system having the configuration shown in FIG. 1, the same test as in Example 8 was conducted except that a part of the gas after the carbon monoxide selective oxidation reaction was not circulated. As a result, the activity of the reforming catalyst was reduced by sulfur poisoning, and after 500 hours, the hydrogen in the gas at the anode inlet was reduced to 35 mol% (excluding steam) or less.
From the above results, it was found that by circulating a part of the generated hydrogen to the reforming reaction, activity deterioration due to sulfur poisoning was suppressed and stable operation was possible.

  According to the present invention, in natural gas, LNG, shale gas, city gas, LPG, etc., light hydrocarbons such as methane in the gas containing hydrogen sulfide, which is a poisoning substance of the catalyst, are converted into hydrogen, carbon monoxide, etc. In a hydrocarbon reforming method and reforming apparatus that uses a reforming catalyst having high activity and high carbon deposition resistance that can be converted to other chemical substances, a part of generated hydrogen is circulated as a raw material gas for the reforming reaction. By doing so, it becomes possible to constantly suppress the catalyst deterioration due to sulfur poisoning. Therefore, the present invention has high industrial applicability.

1 water tank 2 water pump 3 fuel supply source 4 fuel pump 5 heat exchanger (vaporizer)
6 Reformer 7 Heating Burner 8 High Temperature Shift Reactor 9 Low Temperature Shift Reactor 10 Carbon Monoxide Selective Oxidation Reactor 11 Air Blower 12 Solid Polymer Fuel Cell 13 Anode 14 Cathode 15 Solid Polymer Electrolyte 16 Exhaust 17 Hydrogen Supply source 18 Blower for hydrogen 19 Hydrogen addition line 20 Recycled gas circulation line 21 Shift reaction gas circulation line 22 Carbon monoxide selective oxidation gas circulation line

Claims (12)

A hydrocarbon reforming step of reforming a raw material gas containing a sulfur compound and a hydrocarbon using a steam reforming reaction catalyst to generate a first reformed gas containing hydrogen and carbon monoxide from the hydrocarbon. A method for producing hydrogen by reforming a hydrocarbon, comprising:
The catalyst for steam reforming reaction, a precipitant is added to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and to the precipitate, alumina powder and water, Alternatively, alumina sol is added and mixed to produce a mixture, and the mixture is produced by a catalyst production process including at least drying and calcination,
A part of the first reformed gas containing hydrogen generated in the hydrocarbon reforming step is returned to the raw material gas in the hydrocarbon reforming step, or new hydrogen is reformed into the hydrocarbon. A method for producing hydrogen by reforming hydrocarbons, characterized by being introduced into a raw material gas in a quality process. The proportion of hydrogen in the initial source gas is less than 10 mol% with respect to the molar concentration of hydrocarbons in the source gas,
Before reforming, after returning a part of the first reformed gas containing the generated hydrogen into the raw material gas, or after newly introducing hydrogen into the raw material gas in the reforming step. 2. The reforming of hydrocarbon according to claim 1, wherein the ratio of hydrogen in the raw material gas is 10 to 100 mol% with respect to the molar concentration of hydrocarbon in the raw material gas before the reforming. Method for producing hydrogen by. The method for producing hydrogen by reforming hydrocarbons according to claim 1 or 2 , wherein the catalyst production step includes calcining the precipitate after the formation of the precipitate. The steam reforming reaction catalyst, to the mixed solution, further manufactured by adding a cerium compound, any one of claims 1 to 3, characterized in that the cerium oxide microparticles in the catalyst surface is present A method for producing hydrogen by reforming the hydrocarbon according to 1. Raw material gas containing a hydrocarbon with the sulfur compound, natural gas, LNG, shale gas, city gas, or reformed hydrocarbons according to any one of claims 1-4, characterized in that it is selected from LPG Quality of hydrogen production method. Further comprising a shift reaction step of causing a shift reaction of the first reformed gas generated in the hydrocarbon reforming step to increase a ratio of hydrogen in the first reformed gas,
At least one of a part of the first reformed gas containing hydrogen generated in the hydrocarbon reforming step and a part of the second reformed gas after the shift reaction step is used as the hydrocarbon. method for producing hydrogen by reforming a hydrocarbon according to any one of claims 1 to 5, characterized in that return in the feed gas in the reforming process of. The proportion of hydrogen in the initial source gas is less than 10 mol% with respect to the molar concentration of hydrocarbons in the source gas,
At least one of a part of the first reformed gas generated in the hydrocarbon reforming step and a part of the second reformed gas after the shift reaction step is reformed with the hydrocarbon. The ratio of hydrogen in the raw material gas before reforming after returning to the raw material gas in the step is 10 to 100 mol% with respect to the molar concentration of hydrocarbons in the raw material gas before reforming. The method for producing hydrogen by reforming hydrocarbon according to claim 6 , characterized in that. A method for operating a fuel cell, which uses the method for producing hydrogen by reforming hydrocarbon according to claim 6 .
Selective carbon monoxide for converting the carbon monoxide in the second reformed gas into carbon dioxide by passing the second reformed gas after the shift reaction step through a carbon monoxide selective oxidation reactor. Oxidation reaction step,
Further comprising a fuel cell operation step of operating the fuel cell by introducing the third reformed gas after the carbon monoxide selective oxidation reaction step into the polymer electrolyte fuel cell as a fuel gas,
At least one of a part of the second reformed gas after the shift reaction step and a part of the third reformed gas after the carbon monoxide selective oxidation reaction step is subjected to the carbonization. A method of operating a fuel cell, which comprises returning to the raw material gas in a hydrogen reforming step. The ratio of hydrogen in the initial source gas in the method for producing hydrogen by reforming hydrocarbon is less than 10 mol% with respect to the molar concentration of hydrocarbon in the source gas,
In the hydrogen production method, at least one of a part of the first reformed gas generated in the hydrocarbon reforming step or a part of the second reformed gas after the shift reaction step, The ratio of hydrogen in the raw material gas before reforming after returning to the raw material gas in the hydrocarbon reforming step is 10 to 10 with respect to the molar concentration of hydrocarbons in the raw material gas before reforming. It is 100 mol%, The operating method of the fuel cell of Claim 8 characterized by the above-mentioned. A precipitant is added to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and the precipitate is mixed with alumina powder and water or alumina sol. Using a catalyst for steam reforming reaction produced by a catalyst production process comprising producing a mixture and drying and calcining the mixture at least,
From a feed gas containing sulfur compounds and hydrocarbons, and reforming reaction unit to produce a first reformed gas containing hydrogen, carbon monoxide, carbon dioxide,
Shift reaction means for converting carbon monoxide contained in the first reformed gas into carbon dioxide,
A carbon monoxide selective oxidation reaction means for converting carbon monoxide contained in the second reformed gas after passing through the shift reaction means into carbon dioxide,
An apparatus for producing hydrogen, comprising means for circulating a part of hydrogen contained in at least one reformed gas after the shift reaction means or after passing through the carbon monoxide selective oxidation reaction means to the reforming reaction means. The proportion of hydrogen in the initial source gas is less than 10 mol% with respect to the molar concentration of hydrocarbons in the source gas,
The raw material gas in the hydrocarbon reforming means has a means for circulating a part of hydrogen contained in at least one reformed gas after passing through the reforming reaction means or the shift reaction means to the reforming reaction means. And a control means for controlling the ratio of hydrogen in the raw material gas before reforming to 10 to 100 mol% with respect to the molar concentration of hydrocarbons in the raw material gas before reforming. The apparatus for producing hydrogen according to claim 10 , wherein: A water supply means, a raw material gas supply means, and a precipitant is added to a mixed solution of a nickel compound and a magnesium compound to coprecipitate nickel and magnesium to produce a precipitate, and to the precipitate, an alumina powder and Reforming of hydrocarbons filled with a catalyst for steam reforming reaction produced by a catalyst production process including adding water or alumina sol and mixing to form a mixture, and at least drying and calcining the mixture. And a heating means for heating the reformer, a shift reactor, a carbon monoxide selective oxidation reactor, and a fuel cell operating device comprising a polymer electrolyte fuel cell,
Further, a pipe for introducing water supplied from the water supply means, a raw material gas containing a sulfur compound and hydrocarbons supplied from the raw material gas supply means into the reformer, and discharged from the reformer. A pipe for introducing a first reformed gas into the shift reactor, a pipe for introducing a second reformed gas discharged from the shift reactor into the carbon monoxide selective oxidation reactor, and A pipe for introducing a third reformed gas discharged from the carbon selective oxidation reactor into the polymer electrolyte fuel cell;
A heat exchanger for exchanging heat between the pipe introduced into the reformer and the pipe introduced into the shift reactor;
At least one of a part of the second reformed gas discharged from the shift reactor and a part of the third reformed gas discharged from the carbon monoxide selective oxidation reactor is treated with the water. And a pipe for introducing the raw material gas into a pipe for introducing the raw material gas into the reformer.

Images