JP6460879B2 - Regeneration method for tar-containing gas reforming catalyst - Google Patents

Description

  The present invention relates to a method for regenerating a tar-containing gas reforming catalyst.

  The steel industry is an energy-intensive industry that accounts for about 10% of Japan's total energy consumption. However, about 40% of the waste heat in the blast furnace integrated steelmaking process is unused waste heat. Of this unused waste heat, although it is relatively easy to recover, the high-temperature unrefined COG (coke oven gas, hereinafter referred to as “crude COG”) generated from the coke oven as a heat source that has not been used in the past has been revealed. Have a fever. As a technique for recovering the sensible heat of the crude COG, a method mainly using indirect heat recovery has been proposed. For example, in Patent Documents 1 and 2, a sensible heat is provided by providing a heat transfer pipe inside a coke oven riser pipe or between a riser pipe part and a gas collection pipe part, and circulating a heat medium inside the heat transfer pipe. Is disclosed. However, in these methods, tar, light oil and the like accompanying the coarse COG generated from the coke oven adhere to the outer surface of the heat transfer tube, and the densification of the deposit proceeds by carbonization / aggregation. The problem of reduced exchange efficiency is inevitable. As a technique for solving these problems, Patent Document 3 discloses that a catalyst such as crystalline aluminosilicate and crystalline silica is applied to the outer surface of the heat transfer tube, and deposits such as tar are removed through these catalysts with a low molecular weight. Is disclosed in which the heat transfer efficiency is stably maintained. However, this method also does not go beyond the indirect heat recovery technology of coarse COG sensible heat. Further, this method does not consider at all whether or not the decomposition products of heavy hydrocarbons such as tar become light hydrocarbons that can be easily used as gas fuel or the like. Furthermore, the influence of the deterioration over time of the decomposition activity due to the catalytically toxic sulfur compound components such as high-concentration hydrogen sulfide contained in the crude COG has not been studied.

Conventionally, the sensible heat of the high temperature gas is indirectly recovered or not used at all, and in most cases, the cooled gas is used after various treatments. Because the crude COG has sensible heat, but the sulfur compound content exceeds 2000 ppm, the reactive gas as described above is directly converted into chemical energy by introducing a chemical reaction in the presence of a catalyst. This is because the technology was considered to be extremely difficult to realize from the viewpoint of catalytic reaction design related to the decomposition reaction of heavy hydrocarbons such as tar. Therefore, until now, there have been few reports on techniques for converting a reactive gas generated at a high temperature into chemical energy by directly introducing a chemical reaction using sensible heat in the presence of a catalyst.
Some have been studied as described in Patent Document 4. However, the catalyst disclosed in Patent Document 4 cannot be said to have sufficient reforming activity. In addition, the energy conversion catalyst is generally produced by a supporting method in which an active metal species is supported from the outside on a porous ceramic carrier such as silica and alumina, but it is difficult to increase the dispersibility of the supported metal component by that method. Also susceptible to sulfur poisoning and carbon deposition. For this reason, it has been difficult to produce a catalyst suitable for the cracking reaction of a condensed polycyclic aromatic-based tar that is likely to cause carbon deposition in an atmosphere containing the above-described high-concentration sulfur compound. Further, when the performance is deteriorated by reacting once and then air combustion is performed for regeneration, sintering of the supported metal particles is likely to occur, and it is difficult to reproduce the activity by regeneration.
On the other hand, in Patent Document 5 and Non-Patent Document 1, a precipitate (mainly forming a hydrotalcite structure) is formed from an aqueous solution in which each metal component is dissolved as an oxide containing nickel, magnesium and aluminum. The fired material is then disclosed. However, these materials have insufficient reforming activity and a large amount of carbon deposition, and have problems for practical use.

  Furthermore, in recent years, due to the global warming problem, the use of biomass, which is one of carbonaceous raw materials, has attracted attention as an effective means of reducing carbon dioxide emissions, and research on high-efficiency energy conversion of biomass has been conducted in various places. Yes. In addition, from the viewpoint of securing energy resources in recent years, research on effective utilization of coal, which has been vigorously performed in the past, has been reviewed for practical use. Under such circumstances, in Patent Document 6 and the like, a method of gasifying tar generated by dry distillation of biomass to generate crude gas (unrefined gas) and utilizing the sensible heat, particularly tar using a catalyst. Various studies have been made focusing on the catalytic reforming. However, like the coal-derived tar decomposition reaction, it is not always sufficient from the viewpoint of catalyst activity and catalyst regeneration.

In Patent Documents 7 and 8, it is generated when a carbonaceous raw material such as coal or biomass is thermally decomposed, and contains tar containing mainly heavy chain hydrocarbons and condensed polycyclic aromatic hydrocarbons as well as hydrogen sulfide. High-concentration tar-containing gas (crude gas or refined gas, etc.) is converted into light chemicals such as methane, carbon monoxide, and hydrogen in the presence of a catalyst without using an expensive platinum group. A tar-containing gas reforming catalyst, a method for producing the same, a tar reforming method, and a method for regenerating a tar-containing gas reforming catalyst have been studied. Specifically, a method for removing carbon and sulfur by contacting water vapor or air at 800 ° C. in regeneration of the catalyst when the catalyst activity deteriorates is described.
The inventors examined the catalyst regeneration methods described in Patent Documents 7 and 8 in detail by repeatedly performing the reforming reaction and regeneration many times. As a result, it was found that in the catalyst regeneration methods described in Patent Documents 7 and 8, when steam is used as the regeneration gas, it takes time to remove the precipitated carbon. In addition, it was found that when air was used as the regeneration gas, the heat generated by carbon combustion was intense, and even when air was introduced at 800 ° C., the temperature rose to 830 ° C. or more due to carbon combustion. When the catalyst temperature is about 830 ° C. or more, unless the material of the catalyst reactor is an expensive special alloy, that is, a material such as ordinary SUS316, there is a problem that the material strength is insufficient. Therefore, it has been found that in order to suppress the increase in the catalyst temperature, it is necessary to suppress the air introduction flow rate, and there is a problem that it takes time to burn carbon. Conventionally, steam is mainly used as shown in Patent Documents 7 and 8 because sulfur is easily removed from a poisoned catalyst. In addition, for the reason that the reaction is performed at the same temperature as the reforming reaction or the reduction reaction, the temperature has not been controlled even when the air is contacted.

Japanese Patent Publication No.59-44346 JP 58-76487 A JP-A-8-134456 JP 2003-55671 A Japanese Patent Laid-Open No. 50-4001 JP 2005-53972 A International Publication No. 2010/035430 International Publication No. 2010/134326

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

  The tar contained in or accompanied by tar containing gas (unrefined gas) containing hydrogen sulfide, which is a catalyst poisoning substance generated during pyrolysis of carbonaceous raw materials such as coal and biomass, is converted into light chemicals in the presence of the catalyst. The reforming catalyst (tar-containing gas reforming catalyst) used for the treatment for chemical energy conversion that converts to a fuel composition mainly composed of methane, carbon monoxide, hydrogen, etc. Performance deteriorates (activity deterioration). It is an object of the present invention to provide a method for regenerating a tar-containing gas reforming catalyst that regenerates such a catalyst for reforming whose activity has deteriorated (recovers the catalyst performance).

  The present inventors diligently studied a method for regenerating the catalyst by paying attention to the elements constituting the catalyst, the composition thereof, and the reactivity between the catalyst after performance deterioration and air or hydrogen. As a catalyst to convert tar contained in or accompanied by crude gas during pyrolysis of carbonaceous raw materials into light chemical substances mainly composed of methane, carbon monoxide, hydrogen, etc., solid phase crystallization method is different from conventional loading method We focused on the catalyst produced. The catalyst produced by this solid-phase crystallization method is capable of (1) high-speed reaction because it is possible to finely precipitate active species, and (2) the precipitated active metal is firmly bonded to the matrix (matrix). Therefore, it is difficult to sinter (coarse), and the activity deterioration can be suppressed. (3) The precipitated active species metal can be re-dissolved in the matrix by firing, so that regeneration that can suppress sintering is possible. Has characteristics.

As a result of the study, the present inventors have a high concentration atmosphere of a sulfur component that can be sulfur poisoning, and in a severe situation including a large amount of a component that easily causes carbon deposition such as heavy hydrocarbons such as tar, Converts heavy hydrocarbons into light chemicals such as methane, carbon monoxide, hydrogen, etc., removes carbon by air from the above catalyst whose performance has deteriorated due to carbon deposition and sulfur poisoning, and removes sulfur by reduction treatment with hydrogen As a result, it has been found that nickel metal can be finely precipitated in a cluster form again on the oxide surface from the oxide matrix. The fine precipitation of nickel metal as described above is achieved by using a catalyst in which nickel element as an active species is compounded in advance with alumina, magnesia, or the like as a matrix. This is thought to be due to the fine precipitation in clusters.
In addition, when regenerating the catalyst, when air is introduced in a state where the catalyst layer temperature is 800 ° C., the catalyst layer temperature rapidly rises to 1000 ° C. or more, which is the firing temperature, and the specific surface area of the catalyst decreases. , Leading to catalyst degradation. It is important for the inventors to maintain the catalyst layer temperature at 400 to 800 ° C. when introducing air, and to maintain the catalyst layer temperature at 600 to 800 ° C. during reduction with hydrogen. I found.

The gist of the present invention is as follows.
(1) A method for regenerating a catalyst for reforming a tar-containing gas poisoned with sulfur, wherein a precipitant is added to a mixed solution of a nickel compound and a magnesium compound, and nickel and magnesium are coprecipitated and precipitated. A mixture is formed by adding alumina powder and water or alumina sol to the precipitate and mixing the mixture to produce a mixture, and the mixture is produced at least by a catalyst production process that is dried and calcined, and deposited on the surface. The catalyst which has been subjected to carbon deposition and sulfur poisoning by contacting with a tar-containing gas containing sulfur in a state in which at least a part of the nickel thus obtained has been reduced with hydrogen is maintained at a temperature of 400 to 800 ° C. while maintaining the temperature of the catalyst layer. And an air contact step for contacting the catalyst, and hydrogen gas is contacted with the catalyst while maintaining the temperature of the catalyst layer at 600 to 800 ° C. after the air contact step. The method of reproducing tar-containing gas reforming catalyst, comprising a hydrogen gas contacting step of.
(2) The method for regenerating a tar-containing gas reforming catalyst according to (1), wherein the temperature of the catalyst layer is maintained at 400 to 750 ° C. in the air contact step.
(3) The method for regenerating a tar-containing gas reforming catalyst according to (1) or (2), wherein in the catalyst production step, the precipitate is calcined after the precipitate is generated.
(4) The method for regenerating a tar-containing gas reforming catalyst according to any one of (1) to (3), wherein the catalyst contains cerium.

  According to the present invention, tar contained in or associated with a tar-containing gas containing high-concentration hydrogen sulfide such as biomass gasification gas or crude COG is converted into a light chemical substance in the presence of a catalyst, and methane, carbon monoxide When a reforming catalyst with high activity and high carbon deposition resistance that can be converted into a fuel composition mainly composed of hydrogen is deteriorated by the deposited carbon and sulfur poisoning, the deposited carbon and sulfur in the catalyst are efficiently used. Can be removed. As a result, since the catalyst can be used repeatedly over a long period of time, stable operation of the tar-containing gas reforming facility becomes possible.

It is a figure which shows the example of the flow in the case of manufacturing a catalyst, reforming | reforming tar containing gas using the manufactured catalyst for tar containing gas reforming, and regenerating | regenerating the catalyst in which performance deteriorated. It is a desorption gas molecule spectrum in the regeneration reaction by air of the catalyst after the tar reforming reaction. It is a desorption gas molecule spectrum in the reduction reaction by hydrogen of the catalyst for tar reforming from which carbon deposited was removed by air. It is a desorption gas molecule spectrum in the regeneration reaction by steam of the catalyst after the tar reforming reaction.

  Hereinafter, a method for regenerating a tar-containing gas reforming catalyst according to an embodiment of the present invention will be described. The regeneration method of the tar-containing gas reforming catalyst according to the present embodiment reforms the high-temperature tar-containing gas generated when the carbonaceous raw material is pyrolyzed, and mainly uses hydrogen, carbon monoxide, and methane. The present invention relates to a method for regenerating a reforming catalyst when the performance of the reforming catalyst to be converted into gas deteriorates due to sulfur poisoning.

  The “carbonaceous raw material” in the present embodiment is a raw material containing carbon that is pyrolyzed to produce tar. Specifically, it refers to a wide range of carbon containing constituent elements such as coal and biomass and plastic containers and packaging. Of these, “biomass” refers to woody biomass such as forest land residue, thinned wood, unused trees, wood sawn residue, construction waste, or secondary products such as wood chips and pellets, recycled Paper biomass such as waste paper that can no longer be reused as paper, herbaceous biomass such as weeds harvested in parks, rivers, and roads, as well as Sasa and Susuki, food waste biomass such as straw, rice straw, Agricultural residues such as straw and rice husk, sugar resources such as sugarcane, starch resources such as corn, and resource crops such as oil and fat such as rapeseed, sludge, livestock excrement, etc.

  In addition, “tar” generated when pyrolyzing a carbonaceous raw material is an organic compound that is liquid at room temperature and contains 5 or more carbons, although the properties differ depending on the raw material to be pyrolyzed. It refers to a mixture of hydrocarbons and cyclic hydrocarbons. Specifically, in the case of pyrolysis of coal, for example, condensed polycyclic aromatics such as naphthalene, methylnaphthalene, phenanthrene, pyrene, and anthracene are the main components. In the case of thermal decomposition of woody waste, for example, benzene, toluene, naphthalene, indene, anthracene, phenol and the like are the main components. In the case of thermal decomposition of food waste, for example, in addition to the above, a hetero compound containing a different element such as nitrogen element in a 6-membered ring or 5-membered ring such as indole or pyrrole is also included. However, it is not particularly limited to them. Pyrolysis tar exists in a gaseous state at a high temperature immediately after pyrolysis.

Further, the tar reforming reaction in which tar is catalytically decomposed and gasified is a reaction for converting heavy hydrocarbon-based tar into light chemical substances such as methane, carbon monoxide, and hydrogen. The reaction route is complicated and not always clear, but it is possible to consider hydrogenation reaction, steam reforming reaction, dry reforming reaction, etc. that can occur in tar-containing gas or with hydrogen, water vapor, carbon dioxide, etc. introduced from outside. It is done.
Since these series of reactions are endothermic reactions, when applied to an actual machine, a gas having high sensible heat entering the reactor is reformed in the catalyst layer, and the temperature is lowered at the outlet. However, when reforming heavy hydrocarbon components such as tar with higher efficiency, the heat of combustion that burns some hydrocarbon components by introducing air or oxygen into the catalyst layer as necessary. Thus, the reforming reaction can be further advanced while maintaining the temperature of the catalyst layer to some extent.

  As a method for generating the tar-containing gas, a coke oven is generally used when coal is used as a raw material, and an externally heated rotary kiln, moving bed furnace, fluidized bed furnace, or the like can be used when biomass is used as a raw material. However, it is not particularly limited to these.

The method for regenerating a tar-containing gas reforming catalyst according to the present embodiment is such that when the catalyst produced by the catalyst production process deteriorates in performance due to carbon deposition and sulfur poisoning in reforming the tar-containing gas, The present invention relates to a method for restoring (reproducing) performance.
As shown in FIG. 1, the tar-containing gas reforming catalyst is produced in the catalyst production process, and then the catalytic activity is enhanced by reducing the oxidized nickel with hydrogen gas (hydrogen reduction) (reduction). Process). The catalyst with enhanced catalytic activity is used for reforming the tar-containing gas (reforming step). Since the catalyst used for reforming the tar-containing gas deteriorates due to carbon deposition and sulfur poisoning, the catalyst with deteriorated performance is brought into contact with air and hydrogen gas to regenerate (air contact process and hydrogen gas contact process). ). The catalyst that has undergone the air contact step and the hydrogen gas contact step is used for reforming the tar-containing gas again after undergoing a reduction step as necessary.

  Hereinafter, each process will be described in detail with specific examples.

(A) Catalyst Production Process In the catalyst production process, a tar-containing gas reforming catalyst (hereinafter sometimes simply referred to as a catalyst) used in the method for regenerating a tar-containing gas reforming catalyst according to this embodiment is produced.

In the catalyst production process, the catalyst is produced by the following solid phase crystallization method.
Specifically, a precipitate is generated using a precipitant in a mixed solution of a nickel compound and a magnesium compound and the catalyst is mixed with alumina powder and water or alumina sol. And the mixture is dried and fired. Alternatively, a precipitant is added to a mixed solution of a nickel compound and a magnesium compound, and nickel and magnesium are co-precipitated to generate a precipitate. After the generation, the precipitate is calcined, and the calcined precipitate In addition, alumina powder and water or alumina sol are added and mixed to form a mixture, and the mixture is dried and fired. When cerium is included, it is preferable to mix the cerium compound into the solution at the same timing as the nickel compound and the magnesium compound, but after adding and mixing alumina powder and water or alumina sol, a cerium compound is formed. May be impregnated.
When adding alumina as a powder, the smallest possible particle size is preferred. For example, the average particle size is preferably 100 micrometers or less, and water or the like is added during mixing to be used in a slurry form. When adding alumina as an alumina sol, it is preferable to use alumina particles having an average particle size of 100 nanometers or less.

Methods for drying and firing the mixture include (a) drying and firing, (b) drying, grinding and firing, (c) drying, grinding, molding and firing, (d) drying, calcining, grinding, molding and Examples include firing, or (e) drying, pulverization, calcination, pulverization, molding, and firing.
Here, as a method for drying the above mixture, any general drying method may be used regardless of the temperature or the drying method. The mixture after drying may be fired after roughly pulverizing as necessary. However, coarse pulverization is not necessary when the precipitate after drying is kept in powder form by drying the fluidized bed or the like.
It is preferable to filter before drying the mixture. Furthermore, it is more preferable to wash the precipitate after filtration with pure water or the like. In the case of filtration, it is possible to reduce the labor of drying and reduce the energy required for drying. Moreover, when it wash | cleans with a pure water etc., the amount of impurities can be reduced.

The mixture can be fired in air, and the firing temperature may be in the range of 700 to 1300 ° C. More preferably, it is 900-1150 degreeC. When the calcination temperature is high, sintering of the mixture proceeds and the strength increases, but on the other hand, the catalytic activity decreases because the specific surface area decreases. Therefore, it is desirable to determine the balance in consideration.
After calcination, it can be used as a catalyst as it is, but it can be molded by press molding or the like and used as a molded product. A calcining and molding process can also be added between drying and baking. Furthermore, between the calcination and the molding process, if it is necessary to form a powder before molding, it may be molded after pulverization. In that case, calcining may be performed at about 400 to 650 ° C. in the air, and molding may be performed by press molding or the like.

  Here, the catalyst may be in the form of a powder or a molded body. In the case of a molded body, any of a spherical shape, a cylindrical shape, a ring shape, a wheel shape, a granular shape, and a metal or ceramic honeycomb substrate coated with a catalyst component may be used. When used in a fluidized bed, it is preferable to use one formed by spray drying or the like. When used on a fixed bed or moving bed, granulation, extrusion molding, press molding, tableting molding, or the like is suitably used as the molding method, but is not particularly limited thereto.

  As described above, by mixing alumina powder and water or alumina sol with nickel and magnesium precipitates, the moisture containing the alumina component is a highly homogeneous mixture between nickel and magnesia coprecipitates. Can be formed. Therefore, the mixture is dried and fired, or dried, calcined, pulverized, molded and fired 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 more It is considered that a molded product having a high activity and a small amount of carbon deposition can be obtained because Ni particles that are further refined and precipitated therefrom are highly finely dispersed. For this reason, the tar-containing gas reforming catalyst used in the method for regenerating a tar-containing gas reforming catalyst according to the present embodiment simply forms alumina co-precipitate after the formation of a coprecipitate of nickel and magnesium, and physically adds alumina powder to the calcined powder. It is different from what was mixed and molded and fired.

  More specifically, when preparing a mixed solution of a nickel compound and a magnesium compound, it is appropriate to use each metal compound having high solubility in water. For example, not only inorganic salts such as nitrate, sulfate and chloride, but also organic salts such as acetate are preferably used. Particularly preferred are nitrates or acetates, which are thought to be less likely to leave impurities that may become catalyst poisoning after calcination. In addition, any precipitant used to form a precipitate from these solutions can be used as long as it changes the pH of the solution from neutral to basic, in which nickel and magnesium are mainly precipitated as hydroxides. Can do. Among these, for example, an aqueous potassium carbonate solution, an aqueous sodium carbonate solution, an aqueous ammonia solution, or a urea solution is preferably used.

The catalyst produced by the above-described method has (1) nickel, magnesium and aluminum as constituent elements, preferably further contains cerium, and (2) does not contain more than 5% by mass of alumina phase (alumina as a single compound). (3) In the case of containing at least one complex oxide (preferably NiMgO, MgAl ₂ O ₄ ) and cerium, it mainly contains a crystal phase of CeO ₂ .

In the above-described catalyst, nickel functions as a main active component that causes the reforming reaction to proceed with water vapor, hydrogen, and carbon dioxide that are present in the gas or introduced from outside.
Of the components compounded with nickel element, magnesia is a basic oxide and possesses the function of adsorbing carbon dioxide, so that it reacts with the precipitated carbon on the main active component element to form carbon monoxide. It plays a role in removing oxidation. Therefore, it seems that it contributes to keeping the catalyst surface clean and keeping the catalyst performance stable for a long period of time. Alumina functions as a binder that keeps the compound matrix stable, and is separated from each crystal phase on the surface by finely dividing the crystal phase containing nickel and magnesium and dispersing it in an oxide solid phase. It is considered that the active species nickel particles are small and fulfill the function of being in a highly dispersed state.

  The catalyst contains the metal oxide as described above. Further, from this matrix compound, active metal particles can be precipitated in a fine cluster form under a reducing atmosphere. That is, in the above catalyst, nickel metal is finely dispersed in clusters on the catalyst surface, so that the surface area is large, and even if the active metal particles are poisoned during the reaction in a reducing atmosphere, new active metal particles are removed from the matrix. Since it precipitates finely, it is considered that even when high concentration hydrogen sulfide coexists in the tar-containing gas, it is hardly affected by the activity deterioration due to sulfur poisoning.

The tar-containing gas reforming catalyst used in the method for regenerating a tar-containing gas reforming catalyst according to the present embodiment has a nickel content of 1 to 50% by mass as a main active component and a magnesium content of 1 to 1%. It is 45 mass%, and it is preferable that content of an alumina is 20-80 mass%. When a catalyst contains cerium, it is preferable that content of cerium is 1-40 mass%.
Alumina here is the content added to the oxides of nickel and magnesium in the form of alumina powder or alumina sol, not the amount contained in the catalyst as a single compound.

  In the above catalyst, when the nickel content is 1% by mass or more, the nickel reforming performance can be sufficiently exhibited. In addition, when the nickel 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 coarse. You can avoid that. For this reason, it can suppress that performance deteriorates with time in reforming reaction. Therefore, it is preferable that nickel content is 1-50 mass%. More preferably, it is 1-35 mass%.

  When the magnesium content is 1% by mass or more, it is easy to take advantage of the properties of the basic oxide possessed by magnesia. Therefore, it is possible to suppress the carbon deposition of hydrocarbons and easily maintain the catalyst performance for a long period of time. When the magnesium content is less than 1% by mass, the nickel concentration in the solid solution of magnesium and nickel becomes high, so the nickel particles precipitated from the solid solution phase are likely to be coarsened, and the catalyst after the reforming reaction of the tar-containing gas The amount of carbon deposition on the top tends to increase. Further, when the magnesium content is 45% by mass or less, the contents of other nickel, cerium, and aluminum can be appropriately maintained, and the catalyst reforming activity can be sufficiently exhibited. Therefore, the magnesium content is preferably 1 to 45% by mass. More preferably, it is 1-35 mass%.

When the content of alumina is less than 20% by mass, the ceramic is mainly composed of a nickel magnesia (NiMgO) phase, the proportion of the MgAl ₂ O ₄ phase is reduced, and the Ni MgO phase does not become finer and Ni particles precipitated therefrom are large. There is a case. In this case, the activity is lowered or the strength is remarkably lowered when molded. Moreover, when the content of alumina exceeds 80% by mass, the ratio of magnesia which suppresses nickel and carbon deposition, which are main active components, is low, and there is a possibility that the reforming activity of the catalyst cannot be sufficiently exhibited. Therefore, the content of alumina is preferably 20 to 80% by mass.

  When the content of cerium is 1% by mass or more, it is possible to prevent nickel from being hardly precipitated from nickel magnesia due to the oxygen storage ability of cerium oxide. Moreover, when the content of cerium is 40% by mass or less, the proportion of magnesia that suppresses nickel and carbon deposition, which are main active components, can be maintained in an appropriate range, and the reforming activity of the catalyst is sufficiently exhibited. be able to. Therefore, it is preferable to contain 1-40 mass% of cerium. More preferably, it is 3-35 mass%.

In order to adjust the content of each metal species to be in the above range, it is preferable to prepare each starting material in advance by calculation. In addition, once the catalyst has the target component composition, it may be prepared by blending at that time thereafter.
Further, in addition to the above elements, impurities mixed in the catalyst manufacturing process or other components that do not change the catalyst performance may be included, but it is desirable that impurities are not mixed as much as possible.

  As a method for measuring the content of each metal species constituting the catalyst, a method called an inductively coupled plasma method (ICP) can be used. Specifically, after pulverizing the sample, an alkali melting agent (for example, sodium carbonate, sodium borate, etc.) is added and heated and melted in a platinum crucible. After cooling, the whole amount is dissolved in a hydrochloric acid solution under heating. When the solution is inserted into the ICP analyzer, the sample solution is atomized and thermally excited in the high-temperature plasma state in the device, and when this returns to the ground state, an emission spectrum with an element-specific wavelength is generated. In addition, the contained element type and amount can be qualitatively and quantitatively evaluated from the strength.

(B) Reduction step In the reduction step, the oxidized nickel is reduced with hydrogen to form fine metal particles with respect to the catalyst produced by the solid phase crystallization method as described above, thereby enhancing the catalytic activity.
Here, in a relatively high temperature and reducing atmosphere, nickel particles that are active metals precipitate from the catalyst in the form of fine clusters. Therefore, the conditions for reducing the catalyst are not particularly limited. . However, for example, in a gas atmosphere containing at least one of hydrogen, carbon monoxide, and methane, in a gas atmosphere in which water vapor is mixed with these reducing gases, or in an atmosphere in which an inert gas such as nitrogen is mixed with those gases. It may be. The reduction temperature is preferably such that the temperature of the catalyst layer is 600 ° C to 1000 ° C, and more preferably 700 to 900 ° C. 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 catalyst to be charged, and is preferably 30 minutes to 2 hours, for example. However, it may be a time required for the entire packed catalyst to be reduced, and is not limited to this condition. Absent.
When the source gas contains a large amount of hydrogen gas (for example, 30% by volume or more), it can also serve as a reduction process at the initial stage of the reforming process. That is, when a large amount of hydrogen gas is contained in the source gas, the reduction step may not be provided.
Further, when reforming is performed using the regenerated catalyst, the hydrogen gas contact step can also serve as the reduction step. In this case, it is not necessary to provide a separate reduction step before the reforming step. .

(C) Reforming process In the reforming process, a large amount of hydrogen sulfide generated when the carbonaceous raw material is pyrolyzed using the catalyst produced in the catalyst production process and reduced with hydrogen in the reduction process as necessary. Lightly composed mainly of hydrogen, carbon monoxide, and methane by highly efficiently reforming heavy hydrocarbons such as tar that accompany the condensed polycyclic aromatic-based tar-containing gas that contains carbon and easily causes carbon deposition Convert to chemical.
Since the condensed polycyclic aromatic-based tar is highly reactive at high temperatures immediately after dry distillation, it is light and highly efficient by contacting finely dispersed and highly active nickel metal having a high specific surface area. It is thought that it is converted to hydrocarbon and decomposed.

  In the reforming step, hydrogen, carbon dioxide or steam present in the gas or introduced from the outside to the tar-containing gas generated when the carbonaceous raw material is thermally decomposed in the presence of the catalyst or after reduction of the catalyst. Is contacted to reform and gasify the tar in the tar-containing gas. The reforming catalyst is preferably reduced before the reforming step, but it may not be reduced because the reduction may proceed during the reforming reaction. Accordingly, in the presence of the catalyst, or after reducing the catalyst, a gas mixture containing the steam and air or oxygen introduced from the outside is brought into contact with the tar-containing gas generated when the carbonaceous raw material is thermally decomposed. The tar in the tar-containing gas is reformed and gasified.

As the catalytic reactor for reforming, a fixed bed type, a fluidized bed type, a moving bed type, or the like is preferably used. When reforming, it is desirable to measure the temperature by inserting a K-type thermocouple or the like at one to several points in accordance with the size of the reactor so that the temperature of the catalyst layer can be understood. For example, when the catalyst layer (reactor) is large, the catalyst layer cannot be regarded as a homogeneous mixed layer. Therefore, it is preferable to measure three locations near the catalyst layer inlet, near the center, and near the outlet.
When reforming, the catalyst layer inlet temperature is preferably 600 to 950 ° C. When the inlet temperature of the catalyst layer is less than 600 ° C., there is a concern that the catalytic activity when tar is reformed to light hydrocarbons mainly composed of hydrogen, carbon monoxide, and methane is hardly exhibited. On the other hand, when the inlet temperature of the catalyst layer exceeds 900 ° C., the reformer becomes expensive because, for example, a heat resistant structure is required, which is economically disadvantageous. More preferably, the inlet temperature of the catalyst layer is 650 to 900 ° C.
It is possible to proceed the reaction at a relatively high temperature when the carbonaceous raw material is coal, and at a relatively low temperature when it is a woody biomass, papermaking biomass, food waste biomass, or the like.
Hereinafter, the regulation of the catalyst layer temperature in the present embodiment is that when the catalyst layer is large, in the reduction step, near the center of the catalyst layer, in the reforming step, and in the air contact step and hydrogen gas contact step described later, near the catalyst layer inlet Refers to temperature. This is because heat generated by the reaction between the catalyst and hydrogen is small in the reduction process, but heat is absorbed in the reforming process, and heat generation is large in the air contact process and the hydrogen gas contact process, and the catalyst layer is unlikely to have a uniform temperature distribution. . On the other hand, when the catalyst layer is small and can be regarded as a uniform mixed layer, the representative point near the center is indicated.

If the above-described catalyst is used, a tar-containing gas produced by pyrolyzing or partially oxidizing a carbonaceous raw material has a very high hydrogen sulfide concentration, such as a high-temperature coke oven gas discharged from a coke oven. Even so, the tar can be reformed and gasified.
Here, the thermal decomposition or partial oxidation specifically means dry distillation or producing a tar-containing gas by oxidizing only a part of a carbonaceous raw material for gasification. In the current coke oven, raw coal is filled in the furnace, and then heated and dry-distilled to produce coke. The accompanying coke oven gas is generated from the so-called riser pipe at the top of the furnace with cold water (ammonia water). ) Is sprayed and cooled, and then collected in a dry main tube. However, although the gas component has a sensible heat of about 800 ° C. in the coke oven riser pipe, it is rapidly cooled to 100 ° C. after the spraying with water, and the sensible heat can be used effectively. Absent. Therefore, if this sensible heat can be used effectively and heavy hydrocarbon components such as tar can be converted into fuel components such as light hydrocarbons such as hydrogen, carbon monoxide, and methane, it will not only lead to energy amplification but also be generated there. If the process of producing reduced iron by applying it to iron ore becomes possible, for example, if the volume of reducing gas produced is greatly amplified, carbon dioxide emissions generated in the blast furnace process that currently reduces iron ore with coke Can be significantly reduced. If reforming is performed using the above-mentioned catalyst, the coke oven gas, which has sensible heat generated in the coke oven, is brought into contact with the reforming catalyst, and reforming is performed by effectively using gas sensible heat, and hydrogen It can be converted into fuel components such as light hydrocarbons such as carbon monoxide and methane.

  When the above-described catalyst is used, the reforming reaction proceeds stably even in a hydrogen sulfide atmosphere. However, the lower the hydrogen sulfide concentration in the gas, the better because it is not poisoned. In particular, the hydrogen sulfide concentration in the gas is preferably 4000 ppm or less. More preferably, it is 3000 ppm or less.

  The tar-containing gas reforming catalyst built into the catalytic reactor is a catalyst that deposits carbon on the catalyst surface during the conversion from tar to light chemicals mainly composed of hydrogen, carbon monoxide, and methane, or the thermal decomposition. The sulfur component contained in the pyrolysis gas obtained in the process is adsorbed on the catalyst, or nickel that has precipitated as metal fine particles on the catalyst surface or part of cerium oxide is converted to sulfide. Degraded performance. The catalyst performance deterioration refers to a reduction in the decomposition rate of tar and a reduction in the amount of light chemical substances such as hydrogen, carbon monoxide, and methane produced by reforming the tar. When the tar decomposition rate is as low as less than 30% or the hydrogen amplification rate is less than 1.2, it is desirable to regenerate the catalyst.

(D) Air contact step and hydrogen gas contact step In the air contact step and hydrogen gas contact step, a catalyst (tar-containing gas reforming catalyst) produced by the above-described method and having performance deteriorated in the reforming step is regenerated.
At the time of regeneration, an air contact step of removing the deposited carbon on the catalyst by bringing the catalyst having deteriorated performance into contact with air in a state where the temperature of the catalyst layer is maintained at 400 to 800 ° C., followed by the catalyst layer. And a hydrogen gas contact step in which hydrogen gas is brought into contact with the catalyst to remove sulfur. In the regeneration method of the tar-containing gas reforming catalyst according to the present embodiment, the air contact step of removing carbon by contacting air and the hydrogen gas contact step of removing sulfur by contacting hydrogen gas are separated. , It is characterized by performing step by step.
According to the regeneration method, the performance of the nickel magnesia catalyst can be recovered, so that stable operation for a long period of time becomes possible.
The hydrogen gas contact step in the regeneration method can also serve as a reduction step.

In the air contact step, the temperature at which the catalyst and air are brought into contact with each other is preferably 400 ° C. or higher at which the carbon can be combusted at the temperature of the catalyst layer. FIG. 2 shows that the catalyst is carbon desorbed after the tar reforming reaction and sulfur poisoned, and the catalyst is heated at 5 ° C./min and desorbed while 20% O ₂ / He balance gas simulating air is circulated. The profile which analyzed gas with the mass spectrometer is shown. From FIG. 2, it can be seen that the temperature required for carbon to burn and desorb as carbon dioxide quickly enough is 400 ° C. or higher. On the other hand, unless the material of the catalyst reactor or piping is made of an expensive heat-resistant alloy, the temperature of the catalyst layer cannot be increased to about 830 ° C. or more for equipment protection. For this reason, the carbon removal by air is preferably performed in a stepwise manner, and is preferably performed at 800 ° C. or lower. More preferably, it is 750 degrees C or less. By setting it as 750 degrees C or less, while suppressing energy consumption, while protecting equipment, such as a reactor, thermal runaway etc. by combustion heat can also be suppressed. In this process, it is only necessary to remove carbon, and the carbon dioxide concentration at the outlet of the catalyst layer is monitored with an analyzer such as a mass spectrometer, gas chromatograph, infrared CO ₂ analyzer, etc., so that the carbon dioxide concentration becomes 0.5% or less. If so, it is judged that the carbon has been almost removed. In addition, an appropriate time may be calculated from the amount of catalyst and the amount of air introduced in advance, and the regeneration time using air may be determined in advance.
When air is brought into contact with the catalyst on which carbon is deposited, the catalyst layer temperature rapidly rises due to the combustion of carbon, which is an exothermic reaction. As long as the material of the catalyst reactor and piping is not an expensive heat-resistant alloy, it is not preferable to raise the temperature to about 830 ° C or higher for equipment protection. It is preferable to increase the amount of nitrogen introduced.
On the other hand, the temperature at which sulfur is oxidized and desorbed as sulfur dioxide must be 800 ° C. or higher. However, unless the material of the catalyst reactor or piping is made of an expensive heat-resistant alloy, the catalyst layer temperature cannot be increased to about 830 ° C. or more for equipment protection. Therefore, very little sulfur can be removed by air.

In the above air contact step, the removal of the deposited carbon on the catalyst is completed, and after purging the catalyst layer and the piping with an inert gas such as nitrogen, a hydrogen gas contact step is performed in which hydrogen gas is brought into contact with the catalyst. The temperature (reduction temperature) of the catalyst layer in the hydrogen gas contacting step is preferably 600 ° C. or higher at which sulfur can be removed. FIG. 3 shows a profile obtained by analyzing the H ₂ S desorbed with a mass spectrometer by raising the temperature of the catalyst at 5 ° C./min while flowing hydrogen through the catalyst after combustion with air. It can be seen that the 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 gas contact step also has the purpose of precipitating nickel metal fine particles that become active species in the tar reforming reaction from the nickel magnesia phase, and is more preferably performed at 700 ° C. or higher. On the other hand, considering the removal of sulfur and the precipitation of nickel metal fine particles, the reduction temperature is sufficient to be 800 ° C. or lower.

In the air contact step, it may be possible to remove precipitated carbon and sulfur on the catalyst by introducing water vapor instead of air. However, as shown in FIG. 4, when the deposited carbon and the sulfur on the catalyst are removed by water vapor, the CO ₂ desorption is slightly observed at a high temperature of 750 ° C. or higher, and the desorption as H ₂ S is a high temperature. Only a very small amount can be seen. Therefore, it can be said that the rate at which the deposited carbon and the sulfur on the catalyst are removed by the water vapor is very slow compared to the rate at which it is removed by combustion with air and reduction with hydrogen. Therefore, it is not preferable to remove precipitated carbon and sulfur on the catalyst by introducing water vapor instead of air.

  As described above, according to the method for regenerating a tar-containing gas reforming catalyst according to the present embodiment, it is possible to regenerate a catalyst whose performance has deteriorated. Specifically, air is introduced into the catalyst reactor, the carbon on the catalyst surface is burned by the reaction of oxygen and carbon contained in the air, removed as carbon dioxide, and nickel that has become sulfide on the catalyst surface In addition, some of the sulfur in the cerium oxide can be removed as sulfur dioxide, and nickel can be returned to the matrix. Furthermore, by bringing hydrogen into contact with the catalyst and reducing it, 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 recover the catalytic activity.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
Example 1
First, a catalyst was produced in the following manner.
Nickel nitrate and magnesium nitrate are precisely weighed so that the molar ratio of each metal element (nickel: magnesium) is 1: 9, and a mixed aqueous solution heated to 60 ° C. is prepared. A warm aqueous potassium carbonate solution was added. As a result, nickel and magnesium were coprecipitated as hydroxides and sufficiently stirred with a stirrer. The temperature of the aqueous solution was measured by inserting an alcohol thermometer into the aqueous solution. Thereafter, the mixture was aged by continuing stirring for a certain time while maintaining the temperature of the mixed aqueous solution at 60 ° C., and then suction filtration was performed, followed by sufficient washing with 80 ° C. pure water. The precipitate obtained after washing was placed in a beaker and alumina sol was added. Next, what was sufficiently mixed in a mixer equipped with stirring blades was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and sucked with stirring to evaporate water. Transfer the nickel, magnesium, and aluminum compound adhering to the wall of the eggplant-shaped flask to an evaporating dish, dry it at an air atmosphere temperature of 120 ° C, calcine it at an air atmosphere temperature of 600 ° C, and then use a tableting machine to powder the powder to a diameter of 15 mm And molded into a ring shape having an inner diameter of 5 mm and a height of 15 mm to obtain a molded body. The molded body was fired at 950 ° C. in an air atmosphere to prepare a catalyst molded body in which 50% by mass of Ni _0.1 Mg _0.9 O was mixed with aluminum as alumina.
The above catalyst 60L was packed in a fixed bed reactor made of SUS310 and installed in an electric furnace with K-type thermocouples inserted at three locations near the inlet, near the center, and near the outlet of the catalyst layer.
Before starting the reforming reaction, each temperature of the catalyst layer was first raised to 800 ° C. in a nitrogen atmosphere in the reactor, and then subjected to a reduction treatment for 30 minutes while flowing hydrogen gas at 15 Nm ³ / h.
Thereafter, COG generated from the coke oven was introduced into the fixed bed reactor without purification. The tar concentration in COG was about 60 g / m ³ and the hydrogen sulfide concentration was about 3000 ppm. Although COG also contains water vapor, water vapor was added from the outside in order to further improve the reforming activity. At this time, water vapor was added so that the number of moles of carbon derived from tar and hydrocarbons in COG was doubled (water vapor / carbon = 2). The first reforming reaction was carried out for 6 hours at a space velocity (SV) of 500 h- ¹ .
Gas analysis before and after the reaction was performed, and tar decomposition rate and hydrogen amplification rate were determined by the following methods.
For pre- and post-reaction gas analysis, gas pre-treatment equipment (Shimadzu Corporation) is passed through a triple-type gas cleaning bottle filled with water and a thread-wound filter for removing tar that adversely affects the analyzer from the inlet and outlet of the catalyst layer. It was extracted with a pump (manufactured by CFP-8000). After the moisture was removed from the extracted gas with a cooler, H ₂ , N ₂ , O ₂ , CO, CO ₂ , CH ₄ , C ₂ H ₄ , C and the like were obtained using a quadrupole mass spectrometer (Proline, manufactured by AMETEK). ₂ H ₆ was analyzed every 3 seconds. In addition, H ₂ , N ₂ , CO, CO ₂ , CH ₄ , C ₂ H ₄ , C ₂ H ₆ , and H ₂ S are continuously obtained every 12 minutes by TCD and FID gas chromatograph (AG-1 manufactured by Round Science). Analyzed.
Further, gas sampling before and after the catalytic reactor is performed off-line, and tar concentration, moisture concentration, H ₂ , CO, CO ₂ , CH ₄ , C ₂ H ₄ , C ₂ H ₆ , H ₂ S, and benzene in the gas , Toluene and xylene were analyzed. The tar concentration in the gas is determined by sucking the gas from the inlet and outlet of the catalyst layer for a certain period of time, collecting the tar component in the gas through a pentagonal gas washing bottle filled with dichloromethane, and then removing the dichloromethane. The components were evaluated by quantification. And the tar decomposition rate was calculated | required from the ratio of the mass of the tar component in catalyst layer exit gas with respect to the mass of the tar component in catalyst layer entrance gas collected by the said method. The H ₂ (hydrogen) amplification factor was calculated by (Equation 1).
Hydrogen amplification factor (−) = (H ₂ moles in reformed COG) / (H ₂ moles in COG) (Formula 1)

As a result, as shown in Table 1, in the first reforming reaction, the tar decomposition rate was 53.4% and the hydrogen amplification rate was 1.8 on average over 6 hours.
After the reforming reaction for 6 hours, the introduction of COG and steam was stopped, and at the same time, each temperature of the catalyst layer was lowered to 500 ° C. while purging with nitrogen of 50 Nm ³ / h. When the inside of the catalyst reactor and piping could be sufficiently purged and the temperature of the catalyst layer decreased to 500 ° C., the regeneration of the catalyst was started.
First, the catalyst was brought into contact with air in the following manner. That is, the nitrogen flow was decreased to 20 Nm ³ / h, and 10 Nm ³ / h introducing air. When the temperature near the inlet of the catalyst layer starts to rise and the CO ₂ concentration starts to rise by gas analysis using a mass spectrometer at the outlet of the catalyst reactor, it can be confirmed that carbon in the catalyst layer starts to burn. When the catalyst layer temperature was likely to exceed 800 ° C., the air flow rate was decreased and the N ₂ flow rate was increased to 30 Nm ³ / h. When the temperature near the catalyst layer inlet decreases, the temperature near the center of the catalyst layer starts to increase next, and when the temperature near the center of the catalyst layer starts to decrease, the temperature near the catalyst layer outlet further starts to increase. When such adjustment is performed for about 1 hour, the air temperature of 15 Nm ³ / h and nitrogen of 15 Nm ³ / h have been lowered so that each temperature of the catalyst layer approaches the set temperature of 500 ° C. Each temperature was increased to 600 ° C. Thereafter, the temperature was raised to 750 ° C. by 50 to 100 ° C. while observing each temperature of the catalyst layer. Moreover, the air flow rate was finally increased to 30 Nm ³ / h while gradually increasing the air flow rate and lowering the nitrogen flow rate. At the end of 5 hours, confirm that the carbon dioxide concentration at the outlet of the catalyst layer reached 0.4%, stop the first introduction of air, and purge with nitrogen of 50 Nm ³ / h The temperature of the catalyst layer was raised to 800 ° C.
Subsequently, reduction treatment was performed by bringing hydrogen gas into contact with the catalyst in the following manner. That is, after sufficiently purging with nitrogen, reduction treatment was performed for 30 minutes while flowing hydrogen gas at 15 Nm ³ / h.
Then, after regeneration by the above method, the second reforming reaction was performed under the same conditions as the first reforming reaction. As a result, in the second reforming reaction, tar decomposition was 51.7% and hydrogen amplification rate was 1.8 on average over 6 hours, and the activity was restored to the same activity as the first activity performed with a fresh catalyst. It was.
After the second reforming reaction, regeneration was performed under the same conditions as the first regeneration. Then, the third reforming reaction was performed under the same conditions as the first and second times. As a result, in the third reforming reaction, the tar decomposition rate was 50.4% and the hydrogen amplification rate was 1. The activity was restored to almost the same activity as the first activity performed with a fresh catalyst. Thereafter, when the same steps were repeated, as shown in Table 1, the activity in the 4th to 5th reforming reactions was also able to express almost the same performance as the first activity. In other words, by regenerating the catalyst under the above conditions using the above catalyst, the activity of the catalyst whose performance has deteriorated can be recovered, and the tar reforming reaction in COG can be performed stably for a long period of time. I understood.

(Example 2)
The catalyst was manufactured as follows.
Nickel nitrate, cerium nitrate, and magnesium nitrate were precisely weighed so that the molar ratio of each metal element (nickel: cerium: magnesium) was 1: 1: 8, and a mixed aqueous solution heated to 60 ° C. was prepared. A potassium carbonate aqueous solution heated to 60 ° C. was added. As a result, nickel, magnesium and cerium were coprecipitated as hydroxides and sufficiently stirred with a stirrer. The temperature of the aqueous solution was measured by inserting an alcohol thermometer into the aqueous solution. Thereafter, the mixture was aged for a certain period of time while being kept at 60 ° C., and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C. The precipitate obtained after washing was placed in a beaker and alumina sol was added. Next, what was sufficiently mixed in a mixer equipped with stirring blades was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and sucked with stirring to evaporate water. Transfer the nickel, magnesium, cerium, and aluminum compound adhering to the wall of the eggplant-shaped flask to an evaporating dish, dry it at an air atmosphere temperature of 120 ° C, calcine it at an air atmosphere temperature of 600 ° C, and then use a tableting machine to measure the powder It was molded into a ring shape having a size of 15 mm, a height of 15 mm, and an inner diameter of 5 mm to obtain a molded body. The molded body was fired at 950 ° C. in an air atmosphere to prepare a catalyst molded body in which Ni _0.1 Ce _0.1 Mg _0.8 O was mixed with 50% by mass of aluminum as alumina.
Using the catalyst, the reforming reaction and regeneration were repeated in the same manner as in Example 1.
Table 2 shows the tar decomposition rate and hydrogen amplification rate of the reforming reaction (from the first to the fifth).

As shown in Table 2, in the first reforming reaction, the tar decomposition rate was 64.1% and the hydrogen amplification rate was 2.0 on average over 6 hours. In addition, the activity in the 2nd to 5th reforming reactions could exhibit almost the same performance. That is, according to the regeneration method of the present invention, it was found that the catalytic activity can be recovered and the tar reforming reaction in COG can be performed stably for a long period of time.
In addition, compared with Example 1, the tar decomposition rate and the hydrogen amplification rate were improved. That is, it was found that the tar decomposition rate and the hydrogen amplification rate are higher when the catalyst contains cerium.

(Example 3)
Using the catalyst used in Example 2, the first reforming reaction was carried out in the same manner as in Example 1. As a result, as shown in Table 3, the tar decomposition rate was 64.2% and the hydrogen amplification rate was 2.0 on a 6 hour average, which was almost the same as in Example 2.

After the reforming reaction for 6 hours, the introduction of COG and steam was stopped, and at the same time, each temperature of the catalyst layer was lowered to 400 ° C. while purging with nitrogen of 50 Nm ³ / h. When the inside of the catalyst reactor and piping could be sufficiently purged and the temperature of the catalyst layer decreased to 400 ° C., regeneration of the catalyst was started.
First, the catalyst was brought into contact with air in the following manner. That is, the nitrogen flow was decreased to 20 Nm ³ / h, and 10 Nm ³ / h introducing air. When the temperature near the inlet of the catalyst layer starts to rise and the CO ₂ concentration starts to rise by gas analysis using a mass spectrometer at the outlet of the catalyst reactor, it can be confirmed that carbon in the catalyst layer starts to burn. When it was likely to exceed 830 ° C., the air flow rate was decreased and the N ₂ flow rate was increased to 30 Nm ³ / h. When the temperature near the catalyst layer inlet decreases, the temperature near the center of the catalyst layer starts to increase next, and when the temperature near the center of the catalyst layer starts to decrease, the temperature near the catalyst layer outlet further starts to increase. When such adjustment is performed for about 1 hour, the air temperature of 15 Nm ³ / h and nitrogen of 15 Nm ³ / h have been lowered so that each temperature of the catalyst layer approaches the set temperature of 500 ° C. Each temperature was increased to 600 ° C. Thereafter, the temperature was raised to 800 ° C. by 100 ° C. while observing each temperature of the catalyst layer. Moreover, the air flow rate was finally increased to 30 Nm ³ / h while gradually increasing the air flow rate and lowering the nitrogen flow rate. When 5 hours had finally passed, it was confirmed that the carbon dioxide concentration at the outlet of the catalyst layer was 0.4%, and the first introduction of air was stopped and purged with 50 Nm ³ / h of nitrogen.
Subsequently, reduction treatment was performed by bringing hydrogen gas into contact with the catalyst in the same manner as in Example 1.
Then, after regeneration by the above method, the second reforming reaction was performed under the same conditions as the first reforming reaction. As a result, in the second reforming reaction, the tar decomposition rate was 62.5% and the hydrogen amplification rate was 1.9 on average over 6 hours, and the activity was restored to the same activity as the first activity performed with a fresh catalyst. It was. Thereafter, when the same steps were repeated, as shown in Table 3, the activity in the third to fifth reforming reactions was able to develop almost the same performance as the first activity. That is, even if the temperature of the catalyst layer is lowered to 400 ° C. in the air contact step and the reaction is carried out at a temperature up to 800 ° C., the catalytic activity can be recovered and the tar reforming reaction in COG can be performed stably for a long period of time. all right.

(Example 4)
The catalyst was manufactured as follows.
Nickel nitrate and magnesium nitrate are made to have a molar ratio of each metal element of 1: 9, and a precipitate of nickel and magnesium is dried at an air atmosphere temperature of 120 ° C., coarsely pulverized, and calcined at 600 ° C. in an air atmosphere. The resulting product was crushed and placed in a beaker, and alumina sol was added. The other steps were the same as in Example 1.
Using the catalyst, the reforming reaction and regeneration were repeated in the same manner as in Example 1. Table 4 shows the tar decomposition rate and hydrogen amplification rate of the reforming reaction (from the first to the fifth).

  As shown in Table 4, the first reforming reaction had a tar decomposition rate of 53.4% and a hydrogen amplification rate of 1.8 on average over 6 hours. In addition, the activity in the 2nd to 5th reforming reactions could exhibit almost the same performance. That is, in the preparation of the catalyst, even if a catalyst obtained by drying and calcining the coprecipitate of nickel and magnesia before mixing the alumina is used, the catalytic activity is recovered by regeneration, and the tar reforming reaction in COG is prolonged. It was found that it can be performed stably for a period.

(Example 5)
In the catalyst preparation, nickel nitrate, cerium nitrate, and magnesium nitrate were adjusted so that the molar ratio of each metal element was 1: 1: 8, and the precipitates of nickel, magnesium, and cerium were dried at an air atmosphere temperature of 120 ° C. to be coarse. The same procedure as in Example 1 was performed except for the step of pulverizing and calcination at 600 ° C. in an air atmosphere, crushing, putting in a beaker, and adding alumina sol.
Using the catalyst, the reforming reaction and regeneration were repeated in the same manner as in Example 1. Table 5 shows the tar decomposition rate and hydrogen amplification rate of the reforming reaction (from the first to the fifth).

  As shown in Table 5, in the first reforming reaction, the tar decomposition rate was 63.2% and the hydrogen amplification rate was 2.0 on average over 6 hours. In addition, the activity in the 2nd to 5th reforming reactions could exhibit almost the same performance. That is, even when the catalyst contains cerium, the catalyst activity can be achieved by regeneration even if the coprecipitate of nickel, magnesium, and cerium is dried and calcined before mixing the alumina in the preparation of the catalyst. It was found that the tar reforming reaction in COG can be carried out stably for a long period of time.

(Example 6)
Using the same catalyst as in Example 1, the same amount of catalyst as in Example 1 was charged to the same reactor. After filling, before starting the reforming reaction, each 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 gas at 15 Nm ³ / h. Thereafter, as in Example 1, COG generated from the coke oven was introduced unpurified. However, in this example, unlike Example 1, water vapor was not added from the outside. Therefore, in the present Example, water vapor | steam was only the water | moisture content contained in COG, and it was water vapor / carbon = 0.8 by molar ratio. When the reforming reaction is performed under such conditions, the amount of carbon deposition increases.
Using the catalyst, the reforming reaction and regeneration were repeated in the same manner as in Example 1. Table 6 shows the tar decomposition rate and hydrogen amplification rate of the reforming reaction (from the first to the fifth).

  As shown in Table 6, the first reforming reaction had a tar decomposition rate of 45.2% and a hydrogen amplification rate of 1.5 on average over 6 hours. In addition, the activity in the 2nd to 5th reforming reactions could exhibit almost the same performance. That is, even if the reforming reaction is performed under such a condition that the amount of carbon deposition becomes large, according to the regeneration method of the present invention, the catalytic activity is recovered and the tar reforming reaction in COG is performed stably for a long period of time. I found out that I could do it.

(Example 7)
Using the same catalyst as in Example 2, the reforming reaction and regeneration were repeated in the same manner as in Example 6. Table 7 shows the tar decomposition rate and hydrogen amplification rate of the reforming reaction (from the first to the fifth).

  As shown in Table 7, in the first reforming reaction, the tar decomposition rate was 55.2% and the hydrogen amplification rate was 1.7 on average over 6 hours. The activity in the 2nd to 5th reforming reactions was almost the same. That is, even in a reforming reaction under conditions where the amount of carbon deposition is large, according to the regeneration method of the present invention, the catalytic reforming can be recovered and the tar reforming reaction in COG can be performed stably for a long period of time. I understood. Further, it was found that even in the reforming reaction under conditions where the amount of carbon deposition increases, the tar decomposition rate and the hydrogen amplification rate increase when cerium is contained.

(Example 8)
First, a catalyst was produced in the following manner.
A mixed aqueous solution heated to 60 ° C. was prepared by accurately weighing nickel nitrate and magnesium nitrate so that the molar ratio of each metal element was 1: 9, and inserting an alcohol thermometer into the aqueous solution to measure the temperature. Prepared. To this mixed aqueous solution, an aqueous potassium carbonate solution heated to 60 ° C. was added. As a result, nickel and magnesium were coprecipitated as hydroxides and sufficiently stirred with a stirrer. Thereafter, the mixture was aged for a certain period of time while being kept at 60 ° C., and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C. The precipitate obtained after washing was placed in a beaker and alumina sol was added. Next, what was sufficiently mixed in a mixer equipped with stirring blades was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and sucked with stirring to evaporate water. Transfer the nickel, magnesium, and aluminum compound adhering to the wall of the eggplant-shaped flask to an evaporating dish, dry at an air atmosphere temperature of 120 ° C, calcine at an air atmosphere temperature of 600 ° C, and then use a compression molding machine to powder the tablets with a diameter of 3 mm The product was press-molded into a tablet to obtain a tablet-molded body. The molded body was fired at 950 ° C. in an air atmosphere to prepare a catalyst molded body in which 50% by mass of Ni _0.1 Mg _0.9 O was mixed with aluminum as alumina.
20 mL of the above catalyst was used and fixed with quartz wool so as to be positioned in the center of a reaction tube calorized on SUS316. Further, a K-type thermocouple was inserted at the center position of the catalyst layer, and these fixed bed reaction tubes were set at predetermined positions.
Before starting the reforming reaction, the temperature in the vicinity of the center of the catalyst layer was first raised to 800 ° C. in a nitrogen atmosphere, and then reduction treatment was performed for 30 minutes while flowing hydrogen gas at 100 mL / min.
Then, as a simulated gas for coke oven gas, a gas containing hydrogen: nitrogen = 1: 1, 2,000 ppm of H ₂ S and a simulated substance of tar generated during coal dry distillation, it is actually contained in tar and has a viscosity at room temperature. 1-methylnaphthalene (1-MN), which is a low liquid substance, was introduced into the reaction tube at a flow rate of 0.017 g / min with a precision pump. In addition, pure water is introduced into the reaction tube at a flow rate of 0.1 g / min with a precision pump so that S / C = 3, and each gas is adjusted and introduced so that the total becomes 170 mL / min. The first reforming reaction was performed for 8 hours at 800 ° C. with a space velocity (SV) of 500 h ⁻¹ .
Unreacted 1-methylnaphthalene, naphthalene, and moisture are removed via the room temperature trap and ice temperature trap, and the product gas discharged from the outlet is injected online into the TCD and FID gas chromatograph (HP 6890 made by Hewlett-Packard). And analyzed. The 1-MN decomposition rate (decomposition rate of 1-methylnaphthalene), which is the degree of reaction of the reforming reaction, was judged by methane selectivity, CO selectivity, CO ₂ selectivity, and the carbon deposition rate deposited on the catalyst. The selectivity of each gas was calculated by the following (Expression 2) to (Expression 4) from the concentration of each component in the outlet gas.
CH ₄ selectivity (%) = (volume amount of CH ₄ ) / (C amount of supplied 1-methylnaphthalene) × 100 (Formula 2)
CO selectivity (%) = (volume of CO) / (C amount of supplied 1-methylnaphthalene) × 100 (Formula 3)
CO ₂ selectivity (%) = (volume amount of CO ₂ ) / (C amount of supplied 1-methylnaphthalene) × 100 (Formula 4)
Moreover, the carbon deposition rate was calculated from (Formula 5) using the weight reduction amount when it heated up under air circulation using the thermogravimetric analyzer (Shimadzu Corporation TGA-50H).
Carbon deposition rate (%) = (weight reduction amount) / (carbon deposition catalyst weight) × 100 (Formula 5)
In addition, the ratio of the outlet hydrogen gas volume to the inlet hydrogen gas volume (hydrogen amplification factor) is also shown.
The results are shown in Table 8.

As shown in Table 8, in the first reforming reaction, the tar decomposition rate is 67.8%, CH ₄ selectivity is 2.6%, CO selectivity is 26.5%, and CO ₂ selectivity is 8 hours average. The carbon deposition rate was 24.1%, the carbon deposition rate was 2.5%, and the hydrogen amplification rate was 2.0.
After the reforming reaction for 8 hours, the introduction of the gas was stopped and the temperature of the catalyst layer was lowered to 500 ° C. while purging with nitrogen at 100 mL / min. When the catalyst reactor and piping could be sufficiently purged and the catalyst layer temperature dropped to 500 ° C., regeneration of the catalyst was started.
First, the catalyst was brought into contact with air in the following manner. That is, the nitrogen flow rate was reduced to 40 mL / min, and air was introduced at 10 mL / min. When the temperature of the catalyst layer starts to rise and the CO ₂ concentration starts to rise in the gas analysis by the CO ₂ analyzer at the outlet of the catalyst reactor, it can be confirmed that the carbon in the catalyst layer has started to burn. When it was likely to exceed 800 ° C., the air flow rate was reduced and the N ₂ flow rate was increased to 50 mL / min. When such adjustment is performed for about 30 minutes, the catalyst layer temperature has decreased to approach the set temperature of 500 ° C. even when the air is 25 mL / min and nitrogen is 25 mL / min. Was raised. Thereafter, the temperature was raised to 750 ° C. by 50-100 ° C. while observing the catalyst layer temperature. In addition, the air flow rate was finally increased to 50 mL / min while the air flow rate was gradually increased and the nitrogen flow rate was decreased. When 3 hours finally passed, confirm that the carbon dioxide concentration at the catalyst layer outlet became 0.4%, stop the introduction of air and complete the first contact of air with the catalyst The temperature of the catalyst layer was raised to 800 ° C. while purging with nitrogen at 100 mL / min.
Subsequently, reduction treatment was performed by bringing hydrogen gas into contact with the catalyst in the following manner. That is, after sufficiently purging with nitrogen, reduction treatment was performed for 30 minutes while flowing hydrogen gas at 100 mL / min.
Then, after regeneration by the above method, the second reforming reaction was performed under the same conditions as the first reforming reaction. As a result, in the second reforming reaction, the 1-MN decomposition rate was 65.3%, the CH ₄ selectivity was 2.5%, the CO selectivity was 24.6%, and the CO ₂ selectivity was 22 on average for 8 hours. The carbon deposition rate was 2.9%, and the hydrogen amplification rate was 1.9. That is, the activity recovered to the same activity as the first activity performed with a fresh catalyst.
Further, after the second reforming reaction, regeneration (air contact + reduction with hydrogen gas) was performed under the same conditions as the first regeneration. The third reforming reaction was performed under the same conditions as in the first and second times. As a result, in the third reforming reaction, the 1-MN decomposition rate was 69.1%, the CH ₄ selectivity was 2.9%, the CO selectivity was 25.3%, and the CO ₂ selectivity was 23 on average for 8 hours. The carbon deposition rate was .6%, the carbon deposition rate was 2.4%, and the hydrogen amplification rate was 2.0, indicating almost the same activity again as the first activity performed with a fresh catalyst.
Thereafter, the same process was repeated, and a total of five reforming reactions were performed. As shown in Table 8, even in the fourth to fifth reforming reactions, almost the same performance as that of the first time could be exhibited. That is, even in the 1-MN reforming reaction test simulating COG in the laboratory, like the actual COG reaction, according to the regeneration method of the present invention, the catalytic activity is recovered and the tar reforming reaction in COG is prolonged. It was found that it can be performed stably for a period.

Example 9
First, a catalyst was produced in the following manner.
In catalyst preparation, nickel nitrate, cerium nitrate, and magnesium nitrate were precisely weighed so that the molar ratio of each metal element was 1: 1: 8, and an alcohol thermometer was inserted into the aqueous solution, and measurement was performed at 60 ° C. To prepare a mixed aqueous solution. To this mixed aqueous solution, an aqueous potassium carbonate solution heated to 60 ° C. was added. As a result, nickel, magnesium and cerium were coprecipitated as hydroxides and sufficiently stirred with a stirrer. Thereafter, the mixture was aged for a certain period of time while being kept at 60 ° C., and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C. The precipitate obtained after washing was placed in a beaker and alumina sol was added. Next, what was sufficiently mixed in a mixer equipped with stirring blades was transferred to an eggplant-shaped flask, attached to a rotary evaporator, and sucked with stirring to evaporate water. Transfer the nickel, magnesium, cerium, and aluminum compound adhering to the wall of the eggplant-shaped flask to an evaporating dish, dry it at an air atmosphere temperature of 120 ° C, and calcin it at an air atmosphere temperature of 600 ° C. Was pressed into a tablet shape to obtain a tablet-molded body. The molded body was fired at 950 ° C. in an air atmosphere to prepare a catalyst molded body in which Ni _0.1 Ce _0.1 Mg _0.8 O was mixed with 50% by mass of aluminum as alumina. Using the catalyst, the reforming reaction and regeneration were repeated in the same manner as in Example 8. The results are shown in Table 9.

As shown in Table 9, in the first reforming reaction, the tar decomposition rate was 82.1%, CH ₄ selectivity was 3.3%, CO selectivity was 31.5%, and CO ₂ selectivity was 8 hours average. 27.6%, the carbon deposition rate was 3.5%, and the hydrogen amplification rate was 2.1. In addition, the activity in the 2nd to 5th reforming reactions could exhibit almost the same performance. That is, even in the 1-MN reforming reaction test simulating COG in the laboratory, the catalytic reforming can be recovered and the tar reforming reaction in COG can be performed stably for a long period of time as in the case of the actual COG reaction. all right. Further, even in a 1-MN reforming reaction test simulating COG in a laboratory, it was found that the decomposition rate and the hydrogen amplification rate were higher when cerium was contained.

(Comparative Example 1)
A reforming test was conducted in the same experimental manner as in Example 7, using a naphtha primary reforming catalyst (SC11NK; Ni-20 mass% supported alumina) manufactured by Sud Chemie as one of the industrial catalysts prepared by the impregnation support method. went. The results are shown in Table 10.

As shown in Table 10, the first reforming reaction has an average of 8 hours, 1-MN decomposition rate is 45.4%, methane selectivity is 2.5%, CO selectivity is 4.2%, CO _{2 The} selectivity was 5.9%, the carbon deposition rate was 32.8%, and the hydrogen amplification rate was about 1.3.
The industrial catalyst had a low conversion rate of 1-MN to a gas component (12.6%), while the carbon deposition rate was very high. Since the carbon deposition rate is very high, the catalyst life is short.
Further, in the same manner as in Example 8, the reforming reaction and regeneration were repeated. The catalyst activity did not recover even after regeneration, and the performance decreased with each reforming. This is considered to be because the catalytically active particles caused sintering by large combustion heat due to high temperature or long-term oxidation treatment.

(Comparative Example 2)
A first reforming reaction was performed under the same conditions as in Example 8 using the same catalyst as in Example 9.
Thereafter, the introduction of gas was stopped, and the catalyst layer was purged with nitrogen at 100 mL / min while maintaining the temperature of the catalyst layer at 800 ° C. When the catalyst reactor and piping were sufficiently purged, the catalyst layer temperature was not noticed and contact of air with the catalyst was started. When the nitrogen flow rate was reduced to 40 mL / min and air was introduced at 10 mL / min, the catalyst layer temperature began to rise rapidly and the catalyst layer temperature exceeded 1100 ° C. After that, after the high temperature state continued for about 1 hour, when the temperature dropped to 900 ° C. or lower, the ratio of air was increased, and when air was finally 25 mL / min and nitrogen was 25 mL / min, finally 3 hours passed, After confirming that the carbon dioxide concentration at the catalyst layer outlet was 0.3%, the introduction of air was stopped and the first contact with air was completed.
After purging with nitrogen at 100 mL / min and sufficiently purging, reduction treatment was performed for 30 minutes while flowing hydrogen gas at 100 mL / min.
Then, the second reforming reaction was performed under the same conditions as the first reforming reaction. As a result, as shown in Table 10, in the second reforming reaction, the 1-MN decomposition rate was 63.5%, the methane selectivity was 2.5%, the CO selectivity was 21.7%, and the CO ₂ selectivity was The activity was greatly reduced to 16.3%, the carbon deposition rate was 5.2%, and the hydrogen amplification rate was about 1.8. This is considered to be because the time during which the temperature of the catalyst is higher than the firing temperature is longer due to the combustion heat of carbon, and the specific surface area of the catalyst is reduced.
After the second reforming reaction, regeneration was performed in the same manner as in the first, and then the third reforming reaction was performed. As a result, as shown in Table 11, the activity was further reduced. Moreover, the catalyst reactor also became high temperature due to overheating of the catalyst layer, which caused deformation.
From the above results, it has been found that when the temperature of the catalyst layer when air is introduced becomes high, the catalyst is deteriorated and further an abnormality is caused to the apparatus.

(Example 10)
By using a rotary kiln as a dry distillation furnace, supplying waste wood chips (classified to 5 cm or less), which is a raw material of woody biomass, to a rotary kiln maintained at a furnace temperature of 800 ° C. at a rate of 10 kg / h, and biomass distillation, The contained gas was generated.
45 L of the same catalyst as in Example 5 was packed in the catalyst reactor, and installed in an electric furnace with K-type thermocouples inserted at three locations near the inlet, near the center, and near the outlet of the catalyst layer. The biomass tar-containing gas was supplied to a reactor in which each temperature of the catalyst layer was maintained at 800 ° C. so as to be 10 Nm ³ / h, and the reforming reaction was continued for 8 hours. In addition, the reduction process for 30 minutes was performed by hydrogen 5Nm < ³ > / h before raw material injection | throwing-in.
Tar and gas were sampled from the catalytic reactor inlet and outlet. Gas was quantitatively analyzed by an online TCD gas chromatograph, and tar was quantitatively analyzed offline. The tar decomposition rate and the hydrogen amplification rate were determined in the same manner as in Example 1. The catalyst inlet gas composition was close to coke oven gas, and hydrogen, CO, CO ₂ and CH ₄ were the main components. Moreover, it confirmed that hydrogen sulfide which is a poisonous substance was contained about 25 ppm. Furthermore, since about 16% of moisture was contained in the building waste materials, the moisture was volatilized and contained as water vapor.
The results are shown in Table 12.

As shown in Table 12, the first reaction had a tar decomposition rate of 93.8% and a hydrogen amplification rate of 6.5.
After the first reforming reaction, the temperature of the rotary kiln and the catalyst layer was simultaneously reduced to 500 ° C. while the supply of the raw material was stopped and purged with 10 Nm ³ / h of nitrogen. When the inside of the rotary kiln, the catalyst reactor, and the piping could be sufficiently purged and each temperature of the catalyst layer decreased to 500 ° C., the contact of air with the catalyst was started. That is, the nitrogen flow rate was reduced to ^{5 Nm} 3 / h, and ^{2 Nm} 3 / h introducing air. When the temperature in the vicinity of the catalyst layer inlet starts to increase and the CO ₂ concentration starts to increase in the gas analysis by the gas chromatograph at the outlet of the catalyst reactor, it can be confirmed that the carbon in the catalyst layer starts to burn. Therefore, when it was likely to exceed 800 ° C., the air flow rate was reduced and the N ₂ flow rate was increased to 10 Nm ³ / h. When the temperature near the catalyst layer inlet decreases, the temperature near the center of the catalyst layer starts to increase next, and when the temperature near the center of the catalyst layer starts to decrease, the temperature near the catalyst layer outlet further starts to increase. When such adjustment is performed for about 1 hour, the air temperature of 5 Nm ³ / h and nitrogen 5 Nm ³ / h have decreased so that each temperature of the catalyst layer approaches the set temperature of 500 ° C. Each temperature of the catalyst layer was raised to 600 ° C. Thereafter, the temperature was raised to 750 ° C. by 50 to 100 ° C. while observing each temperature of the catalyst layer. Further, the air flow rate was gradually increased and the nitrogen flow rate was lowered, and finally the air flow rate was set to 10 Nm ³ / h. When 4 hours finally passed, it was confirmed that the carbon dioxide concentration at the outlet of the catalyst layer became 0.5%, the introduction of air was stopped, and the first contact of air with the catalyst was completed. .
Then, the temperature of the catalyst layer was raised to 800 ° C. while purging with nitrogen 30 Nm ³ / h. After sufficiently purging, reduction treatment was performed for 30 minutes while flowing hydrogen at 5 Nm ³ / h.
Then, the second reforming reaction was performed under the same conditions as the first reforming reaction. As a result, the second reforming reaction had a tar decomposition rate of 91.2% and a hydrogen amplification rate of 6.3, which was almost the same activity as the first activity performed with a fresh catalyst.
After the second reforming reaction, regeneration was performed under the same conditions as the first regeneration. The third reforming reaction was performed under the same conditions as in the first and second times. As a result, in the third reforming reaction, the tar decomposition rate was 88.7% and the hydrogen amplification rate was 6.1, which was almost the same activity as the first activity performed with a fresh catalyst. Thereafter, the same process was repeated and the reforming reaction was performed 5 times in total. As shown in Table 12, the activity in the 4th to 5th reforming reactions was almost the same. That is, according to the regeneration method of the present invention, it was found that even when used in the reforming reaction with biomass tar-containing gas, the activity of the catalyst can be recovered and the reforming reaction can be performed stably for a long period of time.

(Comparative Example 3)
At the time of regeneration, the reforming reaction and regeneration were performed under the same conditions as in Example 8, except that water vapor was contacted instead of contacting the catalyst. The results are shown in Table 13.

As shown in Table 13, the first reforming reaction is the same as the first in Example 8, with an average of 8 hours, the 1-MN decomposition rate is 67.8%, the CH ₄ selectivity is 2.6%, and the CO selectivity is Was 26.5%, the CO ₂ selectivity was 24.1%, the carbon deposition rate was 2.5%, and the hydrogen amplification factor was 2.0. After the reforming reaction for 8 hours, the introduction of the gas was stopped and the temperature of the catalyst layer was lowered to 500 ° C. while purging with nitrogen at 100 mL / min. When the catalyst reactor and piping could be sufficiently purged and the catalyst layer temperature dropped to 500 ° C., the catalyst was brought into contact with water vapor. That is, the nitrogen flow rate was reduced to 35 mL / min, and water vapor was introduced at 15 mL / min. When the temperature of the catalyst layer starts to rise and the CO ₂ concentration starts to rise in the gas analysis by the CO ₂ analyzer at the outlet of the catalyst reactor, it can be confirmed that the carbon in the catalyst layer has started to burn. In the case of water vapor, the calorific value is not so large because the burning rate of carbon is slow. Therefore, even when the water vapor is 25 mL / min and the nitrogen is 25 mL / min, the catalyst layer temperature has been lowered to approach the set temperature of 500 ° C., so the catalyst layer temperature was increased to 600 ° C. Thereafter, the temperature was raised to 750 ° C. by 50-100 ° C. while observing the catalyst layer temperature. Further, the water vapor flow rate was gradually increased and the nitrogen flow rate was lowered, and finally the water vapor flow rate was 50 mL / min. The carbon dioxide concentration at the catalyst layer outlet finally reached 0.5% when 18 hours had passed. Here, the introduction of water vapor was stopped, and the first regeneration with water vapor was completed.
After purging with nitrogen at 100 mL / min and sufficiently purging, reduction treatment was performed for 30 minutes while flowing hydrogen gas at 100 mL / min.
Then, the second reforming reaction was performed under the same conditions as the first reforming reaction. As a result, in the second reforming reaction, the 1-MN decomposition rate was 62.1%, the CH ₄ selectivity was 2.9%, the CO selectivity was 25.1%, and the CO ₂ selectivity was 21 on average for 8 hours. The carbon deposition rate was 0.7%, the carbon deposition rate was 3.2%, and the hydrogen amplification rate was 1.9. The activity recovered to the activity close to that of the first activity performed with a fresh catalyst. After the second reforming reaction, regeneration (contact with steam and reduction with hydrogen gas) was performed under the same conditions as in the first regeneration, but it took 19 hours for contact with steam to the catalyst.
The reforming reaction and regeneration after the third time were repeated in the same manner. As a result, as shown in Table 13, the activity could be recovered to 90% or more even in the third to fifth reforming reactions. However, it has been found that when steam is used, the degree of recovery of activity is slightly inferior to that when air is used, and further, the regeneration time takes a long time.

(Comparative Example 4)
At the time of regeneration, the same procedure as in Example 9 was performed except that water vapor was used instead of air.
The results are shown in Table 14.

As shown in Table 14, the first reforming reaction is the same as the first in Example 9, with an 8-hour average tar decomposition rate of 82.1%, CH ₄ selectivity of 3.3%, and CO selectivity of 31.5%, CO ₂ selectivity was 27.6%, carbon deposition rate was 3.5%, and hydrogen amplification rate was 2.1. In addition, the activity in the second to fifth reforming reactions was able to express a relatively high 1-MN decomposition rate of 90% or more with respect to the activity of the fresh catalyst. However, as in Comparative Example 3, it was found that 18-20 hours were required for one regeneration time when steam was used for regeneration. Therefore, regeneration with steam requires a long time for carbon removal, and the proportion of regeneration time in a long-term repeated operation (repetition of reforming and regeneration) increases. That is, it can be said that the time for generating the reformed gas is small and inefficient.

Claims (4)

A method for regenerating a sulfur-poored tar-containing gas reforming catalyst,
A precipitant is added to a mixed solution of a nickel compound and a magnesium compound, and nickel and magnesium are co-precipitated to form a precipitate. To the precipitate, alumina powder and water or alumina sol are added and mixed. By producing a mixture, and contacting the mixture with a tar-containing gas containing sulfur in a state in which at least a part of nickel deposited on the surface is hydrogen-reduced and produced by at least a drying and calcining catalyst production process An air contact step in which air is brought into contact with the carbon-deposited and sulfur-poisoned catalyst while maintaining the temperature of the catalyst layer at 400 to 800 ° C .;
A hydrogen gas contact step that is performed after the air contact step, and in which hydrogen gas is brought into contact with the catalyst while maintaining the temperature of the catalyst layer at 600 to 800 ° C.
A method for regenerating a tar-containing gas reforming catalyst, characterized in that   2. The method for regenerating a tar-containing gas reforming catalyst according to claim 1, wherein the temperature of the catalyst layer is maintained at 400 to 750 ° C. in the air contact step.   The method for regenerating a tar-containing gas reforming catalyst according to claim 1 or 2, wherein, in the catalyst manufacturing step, the precipitate is calcined after the precipitate is generated.   The method for regenerating a tar-containing gas reforming catalyst according to any one of claims 1 to 3, wherein the catalyst contains cerium.

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