JP5659532B2 - Catalyst for reforming tar-containing gas, method for producing the same, and method for reforming tar-containing gas - Google Patents

Description

  The present invention is a method for reforming a tar-containing gas generated when a carbonaceous raw material is pyrolyzed, and a method for reforming a tar-containing gas that converts to a gas mainly composed of hydrogen, carbon monoxide, and methane, The present invention relates to a method for producing a reforming catalyst for tar-containing gas used therein, and a regeneration method when the reforming catalyst for tar-containing gas is deteriorated.

  The steel industry is an energy-intensive industry that accounts for about 10% of Japan's total energy consumption, but about 40% of the blast furnace integrated steelmaking process is unused waste heat. Among them, as a heat source that is easy to recover but has not been conventionally used, there is sensible heat of high-temperature unrefined COG (coke oven gas, hereinafter, crude COG) generated from a coke oven.

  As a technique for recovering sensible heat of crude COG, methods mainly using indirect heat recovery have been proposed in Patent Documents 1 and 2, and a heat transfer tube inside a coke oven ascending pipe or between an ascending pipe part and a collecting pipe part And a method of recovering sensible heat by circulating a heat medium inside the heat transfer tube is disclosed.

  However, in these methods, tar, light oil, etc. accompanying the COG generated on the outer surface of the heat transfer tube, and densification due to carbonization / aggregation proceed, and the problem of deterioration in heat transfer efficiency over time and heat exchange efficiency is inevitable. is there.

  As a technique for solving these problems, a catalyst such as crystalline aluminosilicate or crystalline silica is applied to the outer surface of the heat transfer tube, and deposits such as tar are decomposed into low molecular weight hydrocarbons via the catalyst to transfer the catalyst. Patent Document 3 discloses a method for stably maintaining thermal efficiency.

  However, this method also does not go out of the indirect heat recovery technology of crude COG sensible heat, and whether the decomposition products of heavy hydrocarbons such as tar become light hydrocarbons that can be easily used as gas fuel, etc. , Not considered at all. 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.

  There are few technologies that use sensible heat for reactive gases generated at high temperatures to directly convert chemical energy into chemical energy in the presence of a catalyst. Conventionally, the sensible heat of the hot gas is indirectly recovered or not used at all, and the cooled gas is used in various treatments.

  However, although crude COG has sensible heat, the sulfur compound content exceeds 2000 ppm, so the use of sensible heat is extremely realized from the viewpoint of catalytic reaction design for the decomposition reaction of heavy hydrocarbons such as tar. Is considered difficult.

  As described in Patent Document 4, this examination has been performed conventionally, but the reforming activity is not always sufficient. Moreover, since the energy conversion catalyst is susceptible to sulfur poisoning and carbon deposition, it is a catalyst suitable for the decomposition reaction of tars mainly composed of condensed polycyclic aromatic compounds that easily cause carbon deposition in an atmosphere containing the above-mentioned high concentration sulfur compound. It was difficult to manufacture.

  In addition, once the reaction has progressed and the performance has deteriorated, air combustion for regeneration can easily cause sintering of the supported metal particles, which makes it difficult to reproduce the activity by regeneration. It was.

Impurities (H ₂ S, COS, aromatic hydrocarbons, tar, dust, etc.) contained in the crude COG are purified by conventional methods (eg, Patent Document 5) (hereinafter referred to as purified COG) It has been used as a raw material for fuel and chemical synthesis.

  When constructing a methanol synthesis plant using coke oven gas, low-grade hydrocarbons and aromatic hydrocarbons remain at a low concentration in conventional refined gas. May cause poison. In order to avoid this, a production system is disclosed in which synthesis gas is produced by a reformer after performing pre-reforming using a commercially available catalyst (for example, Patent Document 6).

  However, the catalyst used in the reformer for producing the subsequent synthesis gas is not mentioned, and the reforming catalyst for crude COG and purified COG has not been studied.

  On the other hand, many studies have been made on methane reforming catalysts generally used as hydrocarbon reforming raw materials.

  For example, as a partial oxidation catalyst for methane, as in Non-Patent Document 1, as a catalyst produced from a solution of nickel, magnesium, and aluminum via a precipitate, a catalyst for reforming with methane steam or carbon dioxide, As in Patent Document 7, an oxide composed of nickel, magnesium, and calcium includes at least one of Group 3B element, Group 4A element, Group 6B element, Group 7B element, Group 1A element, and lanthanoid element. The catalyst which mixed this is examined.

  In addition, as a steam reforming catalyst with lower hydrocarbons mainly composed of methane, as disclosed in Patent Document 8, magnesium, aluminum and nickel are used as constituent elements, and alkali metals, alkaline earth metals, Zn and Co are used. Catalysts containing one or more elements selected from, Ce, Cr, Fe, and La have been studied.

  Further, as in Non-Patent Document 2, magnesia and Ni supported catalysts for ceria zirconia compounds, as well as Ni supported catalysts for ceria, zirconia, and ceria zirconia compounds for the tri-reforming reaction of methane with carbon dioxide, steam and oxygen. It is being considered.

  On the other hand, as a catalyst for generating hydrogen for fuel cells from a relatively low hydrocarbon containing sulfur in a raw material such as city gas, isooctane, kerosene, propane, etc., it is composed of aluminum and magnesium as in Patent Document 9. As the porous carrier, an oxide of at least one element selected from silicon, zirconium, cerium, titanium, aluminum, yttrium, scandium, a group 1A element, and a group 2A element has been studied.

  Further, as a hydrogen production catalyst from lower hydrocarbons such as propane, butane, city gas, etc., as disclosed in Patent Document 10, a catalyst containing magnesium, aluminum, nickel as a constituent element and containing silicon has been proposed and disclosed. Yes.

  However, the hydrocarbons that are the targets of these catalysts are all lower and chain hydrocarbons, and the sulfur content that can be a catalyst poison contained in the raw material is shown in Patent Document 9. However, it is limited to those of 50 ppm or less. These known catalysts have not been studied at all for reforming heavy hydrocarbons such as tar in a gas atmosphere containing a high concentration of sulfur in the tar-containing gas.

  Due to the global warming problem in recent years, the use of biomass, which is one of carbonaceous raw materials, has attracted attention as an effective means for reducing carbon dioxide emissions, and research on high-efficiency energy conversion of biomass is being conducted. 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.

  Among these, the method of gasifying tar generated by dry distillation of biomass to generate crude gas (unrefined gas) and utilizing its sensible heat is particularly focused on catalytic reforming of tar using a catalyst. In addition, as in Patent Document 11, a noble metal is used and it is expensive and uneconomical, and various studies have been made including Patent Document 12 and the like, but the problem is that the catalyst life is short.

Japanese Patent Publication No.59-44346 JP 58-76487 A JP-A-8-134456 JP 2003-55671 A JP 2000-248286 A JP 2008-239443 A JP 2000-469 A JP 2006-61760 A JP 2007-31396 A JP 2008-18414 A JP 2005-53972 A JP 2007-229548 A

F. Basile et al., Stud. Surf. Sci. Catal., Vol. 119 (1998) C. Song et al., Catalysis Today, Vol. 98 (2004)

  The present invention has been made in view of the above circumstances, and is generated when a carbonaceous raw material such as coal or biomass is pyrolyzed, and is derived from heavy chain hydrocarbons, condensed polycyclic aromatic hydrocarbons, and the like. The tar-containing gas such as crude gas or refined gas containing hydrogen sulfide at a high concentration is converted into light chemicals such as carbon monoxide and hydrogen stably in the presence of a catalyst. It is an object of the present invention to provide a reforming catalyst for tar-containing gas, a method for producing the same, and a reforming method for tar-containing gas.

  For the tar-containing gas containing hydrogen sulfide at a high concentration, which is generated when coal or biomass is pyrolyzed, the present inventors contact a crude gas or purified gas containing hydrogen sulfide at a high concentration with the catalyst, Alternatively, the inventors studied diligently about a method for converting hydrocarbon components in gas into light chemical substances such as carbon monoxide and hydrogen.

  As a result, nickel, magnesium, a metal element (at least one element selected from Ti, Zr, Ca, W, Mn, Zn, Sr, Ba, Ta) as a catalyst, and silicon or aluminum as necessary. By using a metal oxide as a constituent element, even if reforming a crude gas or a refined gas containing a high concentration of hydrogen sulfide and containing a large amount of tar consisting of condensed polycyclic aromatic hydrocarbons, etc., sulfur is added to the catalyst. The inventors have found that it is difficult to cause a decrease in activity and carbon deposition due to poisoning and can be stably converted into light chemical substances such as carbon monoxide and hydrogen, and have made the invention.

  Further, as a result of further intensive studies, the present inventors have found that a nickel compound, a magnesium compound, and a metal compound (the metal is at least one selected from Ti, Zr, Ca, W, Mn, Zn, Sr, Ba, Ta) Active precipitate metal by adding a silicon component or an aluminum component and at least drying and calcining at the time of the coprecipitation or after the formation of the precipitate. Is capable of high-speed reaction, and since the precipitated active metal is firmly bonded to the matrix (matrix), it is difficult to sinter (coarse), suppress the decrease in activity, and further precipitate The inventors have focused on solid-phase crystallization methods having various characteristics such that the active species metal can be occluded again into the matrix by firing and can be regenerated.

  The reducing element in the tar-containing gas is prepared by compounding the active element nickel element in advance with silica or alumina, magnesia, etc. as a matrix, and further coexisting with a metal element having a higher affinity for sulfur than nickel. By contacting with a gas or a reducing gas before reaction, nickel metal can be finely deposited on the oxide surface from the oxide matrix on the cluster.

  The present inventors preferentially adsorb sulfur to the added metal element to protect nickel and protect the influence of sulfur poisoning even in an atmosphere with a high concentration of sulfur components that can be sulfur poisoning. Even under harsh conditions that contain a large amount of components such as tar and heavy hydrocarbons that are prone to carbon precipitation, the active metal has a large surface area, making heavy hydrocarbons highly efficient and light hydrocarbons. The present inventors have found a production method that can be converted into the present invention.

  As a result of further intensive studies, the inventors of the present invention produced a precipitate by coprecipitation from a solution containing a nickel compound, a magnesium compound, and a metal compound, and the coprecipitate was dried and fired to obtain nickel, magnesium, and The oxide of the metal element is generated, and the oxide is mixed with silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water. The catalyst produced by at least drying and calcining the mixture has a high reforming activity of the tar-containing gas and can be reformed for a long time. Even if the catalyst performance deteriorates due to carbon deposition or sulfur poisoning, Or it can be regenerated by contacting with at least one of the air, and the regenerated catalyst has been found to retain the performance before the deterioration, And they accomplished the present invention according to the method for modifying tar-containing gas thereby enabling stable operation.

  As a result of further intensive studies, the inventors have added a precipitant to a mixed solution of a nickel compound, a magnesium compound, a metal compound, and a silicon compound or an aluminum compound, so that nickel, magnesium, a metal element, and silicon or A catalyst produced by coprecipitation of aluminum to produce a precipitate, and at least drying and calcining the precipitate has a high reforming activity of the tar-containing gas and can be reformed for a long time. Even if the catalyst performance deteriorates due to sulfur poisoning, it can be regenerated by bringing it into contact with at least one of water vapor and air, and it has been found that the regenerated catalyst retains the performance before deterioration. Thus, an invention relating to a method for reforming a tar-containing gas that enables stable operation over a longer period of time has been made.

  As a result of further intensive studies, the inventors of the present invention applied a solution of nickel compound, magnesium compound, and metal compound from the outside using silica or alumina as a carrier, and dried and fired, or dried, crushed and fired. The catalyst produced in this way has high reforming activity of the tar-containing gas and can be reformed for a long time. Even if the catalyst performance deteriorates due to carbon deposition or sulfur poisoning, it contacts with water vapor or air. It is possible to regenerate the catalyst, and it is found that the regenerated catalyst retains almost the performance before deterioration, and relates to a method for reforming a tar-containing gas that enables stable operation for a longer period of time. Invented the invention.

  As a result of further intensive studies, the present inventors have conducted reforming of a tar-containing gas for a long time, and even if the catalyst performance deteriorates due to carbon deposition or sulfur poisoning, It is possible to regenerate by contacting at least one of the above, and the regenerated catalyst finds that the performance before the deterioration is almost maintained, and a tar-containing gas that enables stable operation for a longer period of time. An invention relating to this reforming method has been achieved.

  The gist of the present invention is as follows.

(1) aM · bNi · cMg · dO
A catalyst for reforming a tar-containing gas that is a composite oxide represented by:
a, b, and c satisfy a + b + c = 1, 0.02 ≦ a ≦ 0.98, 0.01 ≦ b ≦ 0.97, and 0.01 ≦ c ≦ 0.97,
d is a value at which oxygen and positive elements are electrically neutral;
A tar-containing gas reforming catalyst, wherein M is at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta.

  (2) The tar-containing gas reforming catalyst according to (1), wherein at least one oxide selected from silica, alumina, and zeolite is added to the composite oxide.

(3) (1) or (2) modifying the method of of any of the tar-containing gas tar-containing gas, which comprises using a reforming catalyst.

( 4 ) Hydrogen, carbon dioxide, and water vapor in the tar-containing gas generated when the carbonaceous raw material is pyrolyzed in the presence of the tar-containing gas reforming catalyst or in the presence of the catalyst after reduction. The method for reforming a tar-containing gas as described in ( 3 ) above, wherein the tar-containing gas is reformed and gasified by contacting.

( 5 ) The tar-containing gas generated when the carbonaceous raw material is pyrolyzed in the presence of the tar-containing gas reforming catalyst or in the presence of the catalyst after the reduction, hydrogen, carbon dioxide,
The method for reforming a tar-containing gas according to ( 3 ) or ( 4 ), wherein the tar-containing gas is reformed and gasified by contacting at least one of water vapor.

(6) The reforming of the tar-containing gas according to (4) or (5) , wherein an oxygen-containing gas is further added to at least one of the hydrogen, carbon dioxide, and water vapor so as to contact the tar-containing gas. Method.

(7) The method for reforming a tar-containing gas according to any one of (3) to ( 6 ), wherein the tar-containing gas is a tar-containing gas containing hydrogen sulfide .

( 8 ) The method for reforming a tar-containing gas according to any one of ( 3 ) to ( 7 ), wherein the tar-containing gas is a carbonized gas generated when carbon is carbonized.

( 9 ) The method for reforming a tar-containing gas according to any one of ( 3 ) to ( 8 ), wherein the tar-containing gas is a coke oven gas discharged from a coke oven.

( 10 ) Any of the above ( 3 ) to (7), wherein the tar-containing gas is a dry distillation gas generated when dry distillation of at least one of woody biomass and food waste biomass A method for reforming tar-containing gas.

( 11 ) The method for producing the tar-containing gas reforming catalyst according to (1),
A precipitate is formed by coprecipitation from a mixed solution containing at least a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta. A method for producing a catalyst used for reforming a tar-containing gas, comprising producing a catalyst comprising a composite oxide containing nickel, magnesium, and a metal element by drying and calcining the precipitate.

( 12 ) The method for producing the tar-containing gas reforming catalyst according to (2 ) ,
A precipitate is formed by coprecipitation from a mixed solution containing at least a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta. At the time of the coprecipitation or after the formation of the precipitate, a silicon or aluminum component is added to obtain a mixture containing nickel, magnesium, a metal element, and silicon or aluminum, and the mixture is at least dried and fired, A method for producing a catalyst used for reforming a tar-containing gas, comprising producing a catalyst comprising a mixture containing magnesium, a metal element, and an oxide of silicon or aluminum.

( 13 ) The method for producing the tar-containing gas reforming catalyst according to (2 ) ,
A precipitating agent is added to a mixed solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, Ta, nickel, magnesium And a metal element are co-precipitated to form a precipitate, and then the precipitate is dried and calcined to produce an oxide of nickel, magnesium, and a metal element. Water or silica sol or alumina powder and water, or alumina sol or zeolite powder and water are mixed to form a mixture, and then the mixture is at least dried and calcined to produce a catalyst. A process for producing a catalyst used for reforming a tar-containing gas, characterized in that

( 14 ) Production of a catalyst for reforming a tar-containing gas according to ( 13 ), wherein the mixture is dried, pulverized and calcined, or dried, calcined, pulverized, molded and calcined to produce a catalyst. Method.

( 15 ) The method for producing the tar-containing gas reforming catalyst according to (2 ) ,
A precipitant is added to a mixed solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta, and nickel, magnesium, and After the metal element is coprecipitated to form a precipitate, silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water are added to the precipitate and mixed. A method for producing a catalyst used for reforming a tar-containing gas, characterized in that a catalyst is produced by producing a mixture by at least drying and calcining the mixture.

( 16 ) The production of the catalyst for reforming a tar-containing gas according to ( 15 ), wherein the mixture is dried, pulverized and calcined, or dried, calcined, pulverized, molded and calcined to produce a catalyst. Method.

( 17 ) The method for producing the tar-containing gas reforming catalyst according to (2 ) ,
Adding a precipitant to a mixed solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, Ta, nickel, After coprecipitation of magnesium and metal elements to form a precipitate, silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water are added to the precipitate. To produce a mixture, and then at least dry and calcine the mixture, and further mix silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water. Then, after the second mixture is produced, the catalyst is produced by at least drying and calcining the second mixture, thereby reforming the tar-containing gas. Process for preparing a catalyst employed.

( 18 ) The reforming of the tar-containing gas according to ( 17 ), wherein the catalyst is produced by drying, pulverizing and calcining, or drying, calcination, pulverizing, molding, and calcining the second mixture. For producing a catalyst for use.

( 19 ) The method for producing a tar-containing gas reforming catalyst according to (2 ) ,
Add a precipitant to a mixed solution of a metal compound containing at least one element selected from nickel compounds, magnesium compounds, Ti, Zr, W, Mn, Zn, Sr, Ba, Ta, and silicon compounds or aluminum compounds Then, nickel, magnesium, a metal element, and silicon or aluminum are co-precipitated to form a precipitate, and the precipitate is at least dried and calcined to produce a catalyst. The manufacturing method of the catalyst used for quality.

( 20 ) The tar-containing gas reforming catalyst according to ( 19 ), wherein the precipitate is dried, pulverized and calcined, or dried, calcined, pulverized, molded and calcined to produce a catalyst. Production method.

( 21 ) The method for producing a tar-containing gas reforming catalyst according to (2 ) ,
Using a silica or alumina as a carrier, each solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, Ta is externally applied. A method for producing a catalyst used for reforming a tar-containing gas, wherein the catalyst is attached to the carrier and dried and calcined or dried, crushed and calcined to produce a catalyst.

( 22 ) After carrying out the method for reforming a tar-containing gas according to any one of ( 3 ) to ( 10 ), the catalyst whose performance is deteriorated by at least one of carbon deposition and sulfur poisoning is added to at least steam or air. A method for reforming a tar-containing gas, wherein the catalyst is regenerated by contacting any of them and used again as the catalyst for tar reforming.

  According to the present invention, tar-containing gas generated when coal or biomass is pyrolyzed can be stably converted into light chemical substances such as carbon monoxide and hydrogen. In particular, even if the tar-containing gas contains a high concentration of hydrogen sulfide in the tar-containing gas, it is brought into contact with the catalyst as it is without desulfurization treatment to reform the tar in the crude gas or in the purified gas. Thus, the tar-containing gas can be stably converted to light chemical substances such as carbon monoxide and hydrogen.

  For example, even for crude COG containing about several tens of ppm to 2000 ppm of hydrogen sulfide, tar-containing gas such as purified COG or biomass dry distillation gas, the catalyst of the present invention enables high-efficiency and stable light chemicals through a reforming reaction. Conversion to a substance and production of a reforming catalyst can be performed.

  Further, according to one aspect of the present invention, after reforming the tar-containing gas, the catalyst is regenerated by bringing at least one of water vapor and air into contact with the catalyst after the reaction, and the regenerated catalyst is again tar-containing. It can be used for gas reforming, and stable operation is possible for a long time while suppressing deterioration of catalyst performance.

It is the figure which showed roughly the part from which coke oven gas is discharged | emitted from a coke oven.

  Hereinafter, the present invention will be described in more detail with reference to specific examples.

The tar-containing gas reforming catalyst of the present invention is a composite oxide containing nickel, magnesium, and a metal compound as constituent metals. The metal element of the metal compound is at least one element selected from Ti, Zr 2 , W 2 , Mn, Zn, Sr, Ba, Ta. The composite oxide may contain silicon or aluminum as a constituent element as required.

  Nickel functions as a main active component that causes heavy hydrocarbons to proceed with the reforming reaction with water vapor, hydrogen, or carbon dioxide present in the gas or introduced from the outside. Even when high-concentration hydrogen sulfide coexists in the tar-containing gas, the nickel metal is finely dispersed in clusters on the catalyst surface to increase the surface area, and in a reducing atmosphere, active metal particles are poisoned during the reaction. New active metal particles are finely precipitated from the matrix (solid solution phase with magnesia) even if it is applied, so it is considered that the active metal particles are hardly affected by the decrease in activity due to sulfur poisoning.

  From this matrix compound, active metal particles can be precipitated in a fine cluster under a reducing atmosphere. In addition, the condensed polycyclic aromatic-based tar is also highly reactive at a high temperature immediately after dry distillation, and is highly dispersed by contact with highly active nickel metal having a finely dispersed and high specific surface area. It is thought that it is efficiently converted to light hydrocarbons and decomposed. In addition, since the precipitated nickel is firmly bonded to the matrix compound, it is considered that the aggregation (sintering) between the nickel particles is suppressed, and the catalytic activity is hardly lowered even during a long-time reaction. .

  Among the components compounded with nickel element, magnesium is present as an oxide and exhibits basicity. Therefore, it has a function of adsorbing carbon dioxide, and reacts with precipitated carbon derived from hydrocarbons on the main active component element to exert a role of oxidizing and removing as carbon monoxide. As a result, it seems that the catalyst surface can be kept clean and the catalyst performance can be stably maintained for a long period of time.

The metal element (at least one selected from Ti, Zr 2 , W 2 , Mn, Zn, Sr, Ba, and Ta) does not necessarily have to be dissolved in the nickel-magnesium solid solution oxide. When present in the vicinity of the nickel-magnesium solid solution oxide phase, nickel-magnesium is preferentially adsorbed with sulfur by exhibiting high sulfur affinity even under a high-concentration sulfur atmosphere in the tar-containing gas. It is presumed that the nickel finely precipitated from the solid solution oxide phase is protected from sulfur and plays a role of exhibiting the original function of nickel.

  Silica, alumina, or zeolite not only serves as a carrier as a reaction field, but also partially plays a role such as finely dividing an oxide crystal phase containing nickel and magnesium by reacting with a nickel magnesium compound. Fulfill. As a result, the active species nickel deposited on the surface from each crystal phase is in a highly dispersed state, and in particular, the unevenly-distributed portion of nickel that tends to be the starting point of carbon deposition is not easily formed, and exhibits high carbon precipitation resistance. It is presumed that it also functions.

  The carbonaceous raw material referred to in the present invention is a raw material containing carbon that is pyrolyzed to produce tar, and refers to a wide range of materials containing carbon as a constituent element, such as coal and biomass and plastic containers and packaging. Biomass refers to forest land residues, thinned wood, unused trees, lumber residue, construction waste, woody waste such as rice straw, or secondary products such as wood chips and pellets, and recycled This refers to papermaking waste such as waste paper that can no longer be reused as paper, food residues such as agricultural residues and potatoes, and activated sludge.

  Tar generated when pyrolyzing a carbonaceous raw material differs in properties depending on the raw material to be pyrolyzed, but is an organic compound that is liquid at room temperature and contains 5 or more carbons. It refers to a mixture of group hydrocarbons. If it is pyrolysis of coal, for example, condensed polycyclic aromatics such as naphthalene, phenanthrene, pyrene, anthracene, etc. are the main components, and if pyrolysis of wood waste, for example, benzene, toluene, naphthalene, Indene, anthracene, phenol, etc. are the main components, and if it is the thermal decomposition of food waste, for example, in addition to the above, hetero compounds containing different elements such as nitrogen in 6-membered rings or 5-membered rings such as indole, pyrrole, etc. Although it is included, it is not limited to them in particular. Pyrolysis tar exists in a gaseous state at a high temperature immediately after pyrolysis. In purified COG cooled to approximately room temperature, it exists in the form of a mist.

  For pyrolysis of carbonaceous raw materials, a coke oven is generally used when coal is used as a raw material, and an external heating rotary kiln, moving bed furnace, fluidized bed furnace, etc. can be used when biomass is used as a raw material. However, it is not particularly limited to these.

  The reforming reaction of a tar-containing gas that gasifies by catalytic cracking of the tar-containing gas is a reaction that converts tar, which is a heavy hydrocarbon, into light chemical substances such as methane, carbon monoxide, and hydrogen. Although the reaction route is complicated and not always clear, hydrogenation reaction, steam reforming reaction, dry reforming reaction that may occur in tar-containing gas or between hydrogen, water vapor, carbon dioxide, or oxygen introduced from outside Etc. are considered.

  Since these series of reactions are endothermic reactions, when applied to an actual machine, the gas having high sensible heat entering the reactor is reformed in the catalyst layer and the temperature is lowered at the outlet. When reforming heavy hydrocarbon components such as tar with higher efficiency, combustion that partially burns hydrogen or hydrocarbon components by introducing air or oxygen into the catalyst layer as necessary It is possible to further advance the reforming reaction while maintaining the temperature of the catalyst layer to some extent with heat.

  Next, a method for producing the tar-containing gas reforming catalyst of the present invention will be described.

The reforming catalyst for tar-containing gas of the present invention is a composite oxide containing nickel, magnesium and a metal element (herein, the metal element is from Ti, Zr , W , Mn, Zn, Sr, Ba, Ta). At least one selected), and can be produced by coprecipitation from a solution of a nickel compound, a magnesium compound, and a metal compound, and at least drying and baking the precipitate.

  The reforming catalyst for tar-containing gas of the present invention may be an oxide obtained by adding at least one oxide selected from silica, alumina and zeolite to the composite oxide. The reforming catalyst generates a precipitate by coprecipitation from a solution of a nickel compound, a magnesium compound, and a metal compound, and at the time of coprecipitation of the metal compound or after the formation of the precipitate, An aluminum component is added to form a mixture containing nickel, magnesium, a metal element, and silicon or aluminum, and the mixture can be produced by at least drying and firing.

  As another method, a precipitant is added to a mixed solution of a nickel compound, a magnesium compound, and a metal compound to coprecipitate nickel, magnesium, and a metal element to form a precipitate, and the precipitate is dried and dried. Baking to produce oxides of nickel, magnesium and metal elements, and adding silica powder and water, silica sol, alumina powder and water, alumina sol, or zeolite powder and water to the oxide. It can be produced by mixing to form a mixture, which is at least dried and calcined. In this method, the mixture can be baked after being dried and pulverized, or baked after being dried, calcined, pulverized and molded.

  As another method, a precipitant is added to a mixed solution of a nickel compound, a magnesium compound, and a metal compound to coprecipitate nickel, magnesium, and a metal element to generate a precipitate, and silica powder is added to the precipitate. And water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water are mixed to form a mixture. After the mixture is at least dried and fired, the silica powder and water are further mixed. Or a silica sol or alumina powder and water, or an alumina sol or zeolite powder and water are mixed to form a second mixture, and the second mixture is produced by at least drying and firing. it can. In this method, the mixture can be baked after being dried and pulverized, or baked after being dried, calcined, pulverized and molded.

  As another method, a precipitant is added to a mixed solution of a nickel compound, a magnesium compound, a metal compound, and a silicon or aluminum compound, and nickel, magnesium, a metal element, and silicon or aluminum are co-precipitated to form a precipitate. And the mixture can be produced by at least drying and baking. In this method, the precipitate can be baked after being dried and pulverized, or baked after being dried, calcined, pulverized and molded.

  The drying of the precipitate in each production method may be a general drying method regardless of the temperature or the drying method. The co-precipitate after drying may be fired after roughly pulverizing if necessary (if the precipitate after drying is kept in powder form by drying such as fluidized bed, coarse pulverization is not necessary. is there).

  Filtration prior to drying of the precipitate is preferable because it can reduce the labor of drying. Furthermore, it is more preferable to wash the precipitate after filtration with pure water or the like because the amount of impurities can be reduced.

  Firing of the mixture can be performed in air, and the temperature may be in the range of 700 to 1300 ° C. When the calcination temperature is high, sintering of the mixture proceeds and the strength increases, but the specific surface area decreases and the catalytic activity decreases. Therefore, it is desirable to determine the balance in consideration.

  A calcination or molding step can be added between the drying and the calcination. In that case, the calcination may be performed in air at about 400 to 800 ° C., and the molding may be performed by press molding or the like. After calcination, it can be used as it is as a catalyst, or it can be molded by press molding or the like and used as a molded product.

  As another method, a solution containing a nickel compound, a magnesium compound and a metal compound can be produced by supporting it on powder, granules, molded silica or an alumina carrier. In the process, each compound can be prepared on the surface of the carrier by a conventional impregnation method such as an incipient wetness method or an evaporation to dryness method. The method for supporting each element may be a simultaneous impregnation method in which a solution containing all the elements is supported at once, or after impregnating a solution containing a part of each compound, A sequential impregnation method in which a solution containing a compound is impregnated once or plural times may be used.

  The catalyst precursor thus prepared is dried at 50 to 150 ° C. to remove water or the organic solvent. At that time, when an organic solvent is used, it is desirable to recover and reuse the organic solvent from the economical aspect. Subsequently, it can prepare by baking the obtained catalyst precursor dried product. The final calcination temperature is preferably appropriately determined in consideration of the thermal decomposition temperature and speed of each compound, the specific surface area, the strength of the molded body, and the like.

  By using a catalyst produced by such a production method, it is a tar-containing gas mainly composed of a condensed polycyclic aromatic that contains a large amount of hydrogen sulfide generated when the carbonaceous raw material is thermally decomposed and is liable to cause carbon deposition. However, the accompanying heavy hydrocarbon such as tar can be reformed with high efficiency and converted into light hydrocarbons mainly composed of hydrogen and carbon monoxide.

  In addition, when the catalyst performance deteriorates, by contacting at least one of water vapor or air with the catalyst at a high temperature, the deposited carbon and adsorbed sulfur on the catalyst can be removed to recover the catalyst performance, Stable operation is possible.

  The reforming catalyst for the tar-containing gas produced by this production method has a carrier surface layer part in the support method and the entire material in the other methods. The metal element and the silicon or aluminum component are between the nickel and magnesium components. To form a highly homogeneous mixture. Therefore, the mixture is dried and fired, or dried, calcined, pulverized, molded and fired to form a sintered body in which nickel and magnesium and a metal element, silicon or aluminum are uniformly distributed, and the nickel magnesia crystal phase. Is further refined, and Ni particles precipitated therefrom are highly finely dispersed. Therefore, it is expected that a molded product having a high activity and a small amount of carbon deposition can be obtained.

  Among these production methods, when preparing a solution of a nickel compound, a magnesium compound, a metal compound, and a silicon or aluminum compound, it is appropriate to use each metal compound having high solubility in water. For example, not only inorganic salts such as nitrates, carbonates, sulfates and chlorides, but also organic salts such as acetates are suitably used. Particularly preferred are nitrates, carbonates or acetates, which are thought to be less likely to retain impurities that can become catalyst poisons after calcination.

  The precipitant used when forming a precipitate from these solutions changes the pH of the solution from neutral to basic where nickel, magnesium, metal elements, and silicon or aluminum precipitate mainly as hydroxides. Anything can be used. For example, a potassium carbonate aqueous solution, a sodium carbonate aqueous solution, a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution, an ammonia aqueous solution, a urea solution, or the like is preferably used.

  By using the tar-containing gas reforming catalyst produced by the above method, it contains a large amount of hydrogen sulfide generated when the carbonaceous raw material is pyrolyzed, and is a condensed polycyclic aromatic-based tar that easily causes carbon precipitation. Even with contained gases, it exhibits high carbon precipitation resistance, and the accompanying heavy hydrocarbons such as tar are reformed with high efficiency, resulting in light chemical substances mainly composed of carbon monoxide and hydrogen, with little deterioration over time. It can be converted to stable.

  In the tar-containing gas reforming method of the present invention, the reforming reaction proceeds stably even in a hydrogen sulfide-containing atmosphere. However, the lower the hydrogen sulfide concentration in the gas, the better the poisoning. The hydrogen sulfide concentration in the gas is preferably 4000 ppm or less, and more preferably 3000 ppm or less.

  Furthermore, in the tar-containing gas reforming catalyst used in the tar-containing gas reforming method of the present invention, the nickel content as the main active component is preferably 1 to 97 atomic weight% with respect to the whole reforming catalyst. When the nickel content is less than 1 atomic weight%, the nickel reforming performance is not sufficiently exhibited. If the nickel content exceeds 97 atomic%, the content of magnesium, silicon, or aluminum that forms the matrix is small, so the concentration of nickel metal deposited on the catalyst is high and coarsening is likely. There is a risk of deterioration over time.

  The magnesium content is preferably 1 to 97 atomic%. When the magnesium content is less than 1 atomic weight%, the properties of the basic oxide of magnesia cannot be utilized, so that it is difficult to suppress carbon deposition of hydrocarbons and it is difficult to stably maintain the catalyst performance for a long period of time. Furthermore, since the nickel concentration in the solid solution of magnesium and nickel is high, nickel particles precipitated from the solid solution phase are likely to be coarsened, which may increase the amount of carbon deposited on the catalyst after the reforming reaction of the tar-containing gas. is there. When the magnesium content exceeds 97 atomic weight%, the content of other nickel, metal element, silicon or aluminum decreases, so that the catalyst may not be able to fully exhibit the reforming activity.

  The content of the metal element is preferably 2 to 98 atomic%. If the content of the metal element is less than 2 atomic weight%, sulfur poisoning of nickel deposited from nickel magnesia due to the sulfur adsorption ability of the metal oxide tends to be difficult to avoid. If the content of the metal element exceeds 98 atomic%, the proportion of magnesia that suppresses nickel and carbon deposition, which are the main active components, is low, and the catalyst reforming activity may not be sufficiently exhibited.

  The content of silicon or alumina is preferably 20 to 80% by mass. When the content of silicon or alumina is less than 20% by mass, it becomes a ceramic mainly composed of nickel magnesia, and when molded, the strength tends to be remarkably lowered. When the content of silicon or alumina exceeds 80% by mass, the ratio of magnesia that suppresses nickel and carbon deposition, which are main active components, is low, and thus there is a possibility that the reforming activity of the catalyst cannot be exhibited sufficiently.

  Further, when silicon or alumina is used as the carrier, it is preferable to appropriately adjust the pore volume and the pore diameter in consideration of the surface area and the strength, and particularly the shape or the like in the case of a molded body.

  The reforming catalyst of the present invention is more preferably produced so that the nickel content is 1 to 80 atomic%, the magnesium content is 1 to 90 atomic%, and the metal element content is 2 to 50 atomic%.

  The reforming catalyst of the present invention may be in any form of powder, granule, or molded body. In the case of a molded body, spherical, cylindrical, ring-shaped, wheel-shaped, granular, etc. Any of a honeycomb substrate coated with a catalyst component may be used.

  In order to prepare the content of each metal species so as to be in the above range, it is preferable to prepare each starting material in advance by calculation. Once the catalyst has the target component composition, it can be prepared by blending at that time.

  In addition to the above elements, inevitable impurities mixed in the catalyst manufacturing process or the like may be included within the range not impairing the characteristics of the present invention, and other components that do not change the catalyst performance may be included. Is desirable.

  A scanning high frequency inductively coupled plasma method (ICP) was used as a method for measuring the content of each metal species constituting the reforming catalyst. 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 injected 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 a wavelength unique to the element is generated. In addition, the element type and amount can be qualitatively and quantitatively determined from the strength.

  The tar-containing gas reforming method using the catalyst of the present invention is a tar generated when a carbonaceous raw material is pyrolyzed in the presence of the above-mentioned tar-containing gas reforming catalyst or in the presence of a catalyst after reduction. Hydrogen, carbon dioxide, and water vapor in the contained gas are brought into contact with each other to reform and gasify the tar-containing gas.

  Further, the tar-containing gas generated when the carbonaceous raw material is thermally decomposed in the presence of the tar-containing gas reforming catalyst or in the presence of the catalyst after the reduction, at least one of the hydrogen, carbon dioxide, and water vapor. Is added from the outside to reform and gasify the tar-containing gas.

  A tar gasification reaction in which tar in a tar-containing gas is gasified by catalytic reforming has a complicated reaction route and is not necessarily clear. However, for example, the formula 1 It is considered that the conversion reaction to light hydrocarbons such as methane proceeds by hydrogenolysis of the condensed polycyclic aromatic in tar as represented by (Formula 1 describes the case where only methane is produced).

_{C m H n + (2m-} n / 2) H 2 → mCH 4 ( Equation 1)

  Conversion reaction to hydrogen and carbon monoxide by dry reforming of condensed polycyclic aromatics in tar as represented by Formula 2 with carbon dioxide introduced from tar-containing gas or externally proceeds To do.

_{C m H n + m / 2CO} 2 → mCO + n / 2H 2 ( Equation 2)

  Steam reforming and a water gas shift reaction as represented by Formula 3 proceed in the tar-containing gas or with water vapor introduced from the outside. The reaction proceeds in the same manner for hydrocarbon components other than tar in the tar-containing gas.

_{C m H n + 2mH 2 O} → mCO 2 + (m + n / 2) H 2 ( Equation 3)

  Therefore, when producing a high calorie gas such as methane, it is desirable to add hydrogen from the outside. Further, when producing hydrogen or carbon monoxide, it is desirable to add carbon dioxide from the outside. Furthermore, when producing more hydrogen, it is desirable to add water vapor from the outside. For hydrocarbon components other than tar, the reaction proceeds according to the above formulas 1 to 3.

  The tar-containing gas reforming catalyst is preferably reduced, but it does not need to be reduced because the reduction proceeds during the reaction. In particular, when the tar-containing gas reforming catalyst requires a reduction treatment before the reaction, since the active metal nickel particles are precipitated in the form of fine clusters from the catalyst of the present invention, the reduction condition is relatively high temperature and reduction. If it is a sex atmosphere, there is no particular limitation.

  For example, in a gas atmosphere containing at least one of hydrogen, carbon monoxide, and methane, in a gas atmosphere in which water is added to these reducing gases, or in an atmosphere in which an inert gas such as nitrogen is mixed into these gases. There may be. The reduction temperature is preferably 500 ° C. to 1000 ° C., for example. The reduction time depends on the amount of catalyst to be charged, and is preferably, for example, 30 minutes to 4 hours. However, the time required for reducing the entire packed catalyst may be any time and is particularly limited to this condition. is not.

  As the catalyst reactor, a fluidized bed format or moving bed format is suitably used when the catalyst is powder, and a fixed bed format or moving bed format is suitably used when the catalyst is a molded body. The inlet temperature of the catalyst layer is preferably 500 to 1000 ° C, and more preferably 550 to 1000 ° C. When the inlet temperature of the catalyst layer is less than 500 ° C., the catalytic activity at the time of reforming tar and hydrocarbon to light hydrocarbons mainly composed of hydrogen and carbon monoxide is hardly exhibited, which is not preferable. When the inlet temperature of the catalyst layer exceeds 1000 ° C., it is economically disadvantageous because the reformer becomes expensive, for example, a heat resistant structure is required. 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 biomass.

  Even if the tar-containing gas generated by pyrolyzing or partially oxidizing the carbonaceous raw material is a tar-containing gas having a very high hydrogen sulfide concentration such as crude COG discharged from the coke oven, The tar and hydrocarbons inside can be reformed and gasified. Pyrolysis or partial oxidation specifically refers to 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, coke is produced by filling the furnace with raw coal and then heating and dry distillation. As shown in FIG. 1, coke oven gas generated concomitantly is collected in a dry main 4 that is an air collecting tube after spraying cold water 2 (ammonia water) from an ascending pipe 1 at the top of the furnace and cooling it. Despite having a sensible heat of about 800 ° C. in the riser 1 of the coke oven 3, the gas component is rapidly cooled to 100 ° C. or less after spraying with the water 2 and effectively uses the sensible heat. Not done.

  If this sensible heat can be used effectively and the tar-containing gas can be converted into fuel components such as light hydrocarbons such as hydrogen and carbon monoxide, it will lead to energy amplification. Furthermore, if the reducing gas volume produced there is greatly amplified, for example, if a process for producing reduced iron by applying it to iron ore becomes possible, the current blast furnace process for reducing iron ore by coke will be possible. There is a possibility that the generated carbon dioxide emissions can be greatly reduced.

  In addition, it can be converted into a useful gas, not just used for conventional fuel applications, and it can lead to higher energy use by converting it to synthesis gas suitable for direct reduction of iron ore. is there.

The tar contained in the crude COG changes with time from the coke oven charging to the start of the kiln, and fluctuates in the range of about 0.1 to 150 g / Nm ³ . The above-mentioned crude COG is cooled by spraying water 2 with a riser pipe of a coke oven, collected by a dry main 4, and then purified COG by a conventional method is treated with a primary cooler, a tar extractor, an electric dust collector, etc. However, there is approximately 0.01 to 0.02 g / Nm ³ of tar. Subsequent final cooler was purified naphthalene be about 0.2-0.4 g / Nm ^3, includes the degree 5 to 10 g / Nm ³ gas oil fraction even after the scrubber process.

  If the purified COG, which is the tar-containing gas, can be converted into fuel components such as light hydrocarbons such as hydrogen and carbon monoxide, as with the conversion of crude COG, reduction of carbon dioxide emissions and conversion to useful materials other than fuel Etc. can be expected.

  The tar-containing gas reforming catalyst incorporated in the catalytic reactor is carbon deposited on the catalyst surface during thermal conversion from tar and hydrocarbon components to light chemicals mainly composed of hydrogen and carbon monoxide, or thermal decomposition. When the sulfur component contained in the pyrolysis gas obtained in the process is adsorbed on the catalyst, the performance of the catalyst deteriorates. The deteriorated catalyst can be obtained by introducing water vapor into the catalytic reactor and removing the carbon on the catalyst surface by the reaction of water vapor and carbon, or removing sulfur adsorbed on the catalyst in the form of hydrogen sulfide by the reaction of water vapor and sulfur. It is possible to play.

  Also, by introducing some or all of the water vapor into air, the carbon on the catalyst surface is removed by the combustion reaction of oxygen and carbon in the air, or the sulfur adsorbed on the catalyst is removed by the reaction of oxygen and sulfur. Thus, the catalyst can be regenerated. The entire amount of the regenerated catalyst can be reused, or a part of the regenerated catalyst can be replaced with a new catalyst.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  Nickel, magnesium, and the metal elements shown in Table 1 were precisely weighed so that the atomic weight percentages were 10%, 80%, and 10%, respectively, and a mixed aqueous solution was prepared by heating at 60 ° C. A warm potassium carbonate aqueous solution was added to coprecipitate nickel, magnesium and metal elements as hydroxides, and the mixture was 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 is dried at 120 ° C. and coarsely pulverized, and then baked (calcinated) at 600 ° C. in the air, and then pulverized into a 3 mmφ tablet using a compression molding machine. Press molding was performed to obtain a tablet molding. The molded body was fired in air at 1100 ° C. to prepare a catalyst molded body made of Ni _0.1 M _0.1 Mg _0.8 O.

This catalyst was used at 60 cm ³ and fixed with quartz wool so as to be located at the center of the SUS reaction tube, a 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 reactor was heated to 800 ° C. under a nitrogen atmosphere, and then reduced for 30 minutes while flowing hydrogen gas at 100 mL / min. After that, as a simulated gas for coke oven gas (crude gas), hydrogen: nitrogen = 1: 1, H ₂ S = 2000 ppm, each gas was adjusted and introduced so that the total was 125 mL / min. The reaction was carried out for 8 hours to evaluate the catalyst performance.

  Moreover, as a simulated substance for tar generated during coal dry distillation, 1-methylnaphthalene, which is a liquid substance that is actually contained in tar and has a low viscosity at room temperature, is used as a representative substance, and a flow rate of 0.025 g / min with a precision pump. Into the reaction tube.

  Further, pure water was introduced into the reaction tube at a flow rate of 0.1 g / min with a precision pump so that S / C = 3. The product gas discharged from the outlet was passed through a room temperature trap and an ice temperature trap to remove naphthalene and moisture, respectively, and then injected into gas chromatography (HP 6890 manufactured by Hewlett-Packard) to perform TCD and FID analysis.

Degree of reaction of the reforming reaction (decomposition rate methylnaphthalene), the methane selectivity, CO selectivity, CO ₂ selectivity was determined by carbon deposition rate deposited on the catalyst. They were calculated by the following formula from the concentration of each component in the outlet gas.

Methane selectivity (%) = (volume of CH ₄ ) / (of 1-methylnaphthalene supplied
C supply amount) x 100

CO selectivity (%) = (volume of CO) / (of 1-methylnaphthalene supplied
C supply amount) x 100

CO ₂ selectivity (%) = (volume of CO ₂ ) / (of 1-methylnaphthalene supplied
C supply amount) x 100

Carbon precipitation rate (%) = (weight of precipitated carbon) / (of 1-methylnaphthalene supplied
C supply amount) x 100

  Further, the ratio of the hydrogen gas volume at the outlet to the hydrogen gas volume at the inlet (hydrogen amplification factor) is also shown.

From the results of Table 1 (No. 3 is a reference example) , the decomposition reaction of 1-methylnaphthalene, which is a simulated tar, progresses even under an atmosphere containing H ₂ S concentration of 2000 ppm, nickel, magnesium, And it turns out that the catalyst of the complex oxide which consists of each metal element of Table 1 is strong in sulfur poisoning resistance, has high carbon precipitation resistance, and is excellent in decomposition | disassembly activity of simulated tar.

  To a solution prepared by accurately weighing nickel nitrate, zirconium nitrate oxide, and magnesium nitrate so that the atomic weight percentage of each metal element is 10%, 10%, and 80%, respectively, A potassium carbonate aqueous solution heated to 0 ° C. was added to coprecipitate nickel, zirconium and magnesium 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 dried at 120 ° C. and coarsely pulverized, then baked (calcinated) at 600 ° C. in the air, crushed, put in a beaker, added with alumina sol, and a mixer equipped with stirring blades The mixture that had been sufficiently mixed in was transferred to a flask made of eggplant, attached to a rotary evaporator, and sucked with stirring to evaporate water.

The nickel, magnesium, and alumina compounds attached to the flask wall are transferred to an evaporating dish, dried at 120 ° C, calcined at 600 ° C, and then pressed into a 3mmφ tablet using a compression molding machine. Molded to obtain a tablet. The molded body was fired in air at 950 ° C. to prepare a catalyst molded body in which 50% by mass of alumina was mixed with Ni _0.1 Zr _0.1 Mg _0.8 O.

The catalyst 60 cm ³ was fixed with quartz wool so as to be located at the center of the SUS reaction tube, a thermocouple was inserted at the center of the catalyst layer, and the reaction tube was set at a predetermined position.

Before starting the reforming reaction, the reactor was heated to 800 ° C. under a nitrogen atmosphere, and then reduced for 30 minutes while flowing hydrogen gas at 100 mL / min. After that, as a simulated gas for coke oven gas (crude gas), hydrogen: nitrogen = 1: 1, H ₂ S was introduced by adjusting each gas so that the concentration shown in Table 1 was 125 mL / min in total, and under normal pressure The reaction was carried out at each temperature shown in Table 1 for 8 hours to evaluate the catalytic activity. The rest was performed in the same manner as in Example 1.

No. in Table 2 From the results of 10 to 14, the decomposition reaction of 1-methylnaphthalene, which is a simulated tar, has progressed even in an atmosphere containing H ₂ S at a high concentration of 2000 ppm. It turns out that it is strong in toxicity.

In particular, as the reaction temperature rises, the decomposition rate (methane selectivity + CO selectivity + CO ₂ selectivity + carbon deposition rate) is high, sulfur poisoning resistance is high, and even under severe conditions with high carbon deposition properties, 1- It can be seen that the decomposition reaction of methylnaphthalene proceeds.

No. From the results of 13, 16, and 17, it can be seen that as the H ₂ S concentration is lowered, the influence of sulfur poisoning is reduced and the decomposition rate is further improved. Since the hydrogen amplification rate also increased with the increase in the decomposition rate of the simulated tar, it is considered that the hydrogen combined with the carbon constituting 1-methylnaphthalene was converted into hydrogen molecules along with the decomposition by the catalyst.

  Further, the carbon deposition rate is a relatively low value, and becomes lower as the temperature rises. It was also found that the entire reforming reaction was decomposed almost entirely in a high temperature region of 800 ° C. or higher.

  Nickel nitrate, titanium nitrate, and magnesium nitrate were precisely weighed so that the atomic weight percentage of each metal element was 10%, 10%, and 80%, and a mixed aqueous solution was prepared by heating at 60 ° C. A heated aqueous potassium carbonate solution was added, and the mixture was sufficiently stirred with a stirrer. Thereafter, with the temperature kept at 60 ° C., the mixture was aged for a certain period of time and then subjected to suction filtration, and then thoroughly washed with pure water at 80 ° C.

After that, the precipitate is added to the precipitate so that the alumina sol becomes 50% by mass as alumina, and mixed well with a mixer equipped with a stirring blade. Then, the mixture is transferred to an eggplant flask and attached to a rotary evaporator and sucked with stirring. As a result, water was evaporated. The nickel, magnesium, titanium, and alumina compounds adhering to the flask wall are transferred to an evaporating dish, dried at 120 ° C, ground in a mortar, and calcined at 600 ° C. To obtain a tablet-molded body. The molded body was fired in air at 950 ° C. to prepare a catalyst molded body in which 50% by mass of alumina was mixed with Ni _0.1 Ti _0.1 Mg _0.8 O.

  Except for the preparation method of this catalyst molded body, all of No. 2 in Example 2. As a result of the reforming experiment for 8 hours in the same manner as No. 12, the decomposition rate of the simulated tar is 88.5%, the carbon deposition rate is 9.3%, the hydrogen amplification rate is 2.5 times, and stable. As a result, it was confirmed that it possessed a very high reforming activity and exhibited a relatively low carbon deposition rate.

  It was prepared by a method of preparing a precipitate from an aqueous solution containing nickel, magnesium, barium, and aluminum using a precipitating agent and firing it. That is, nickel nitrate, magnesium nitrate, barium nitrate, and aluminum nitrate are made to have an atomic weight ratio of nickel, barium, and magnesium metal elements of 1: 1: 8, which is the same as in Example 2, and 50% by mass as alumina. A potassium carbonate aqueous solution heated to 60 ° C. was added to a solution prepared by mixing and precisely weighing and mixing in pure water at 60 ° C. as in Example 1, and the mixture was sufficiently stirred with a stirrer.

  Thereafter, with the temperature kept at 60 ° C., the mixture was aged for a certain period of time, and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C. Thereafter, the precipitate is transferred to an evaporating dish, dried at 120 ° C., pulverized in a mortar, and calcined at 600 ° C., and then press-molded in the same manner as in Example 2 using a compression molding machine to obtain a tablet molding. It was. The molded body was fired in air at 950 ° C. to prepare a catalyst molded body.

  Except for the preparation method of this catalyst molded body, all of No. 2 in Example 2. As a result of the reforming experiment for 8 hours in the same manner as No. 12, the decomposition rate of the simulated tar was 88.7%, the carbon deposition rate was 8.5%, and the hydrogen amplification rate was 2.5 times. As in Example 2, it was confirmed that it had stable and very high reforming activity and exhibited a low carbon deposition rate.

As a reference example, a mixed aqueous solution of nickel nitrate, magnesium nitrate, and calcium nitrate, which is a precursor of nickel oxide, magnesium oxide, and calcium oxide, is preliminarily calcined at 1200 ° C. for 3 hours. , Calcium, and magnesium so that the atomic weight ratio of the metal elements is 1: 1: 8 which is the same as in Example 2, impregnated so as to be 80% by mass as alumina, and dried at 110 ° C. for 12 hours. Firing was carried out at 3 ° C. for 3 hours to prepare a catalyst molded body.

  Except for the preparation method of this catalyst molded body, all of No. 2 in Example 2. As a result of the modification experiment for 8 hours in the same manner as No. 12, the decomposition rate of the simulated tar is 88.5%, the carbon deposition rate is 6.6%, and the hydrogen amplification rate is 2.5 times. As in Example 2, it was confirmed that it had stable and very high reforming activity and exhibited a low carbon deposition rate.

As a reference example, a molded catalyst was prepared in the same manner as in Example 5 except that silica (surface area: about 100 m 2 / g) calcined at 1200 ° C. for 3 hours was used instead of alumina. This molded catalyst was obtained as No. 2 of Example 2. As a result of the reforming experiment for 8 hours in the same manner as in No. 12, the decomposition rate of the simulated tar was 87.6%, the carbon deposition rate was 7.2%, and the hydrogen amplification rate was 2.5 times. Similar to 2, it was confirmed that it had a very high reforming activity stably and exhibited a low carbon deposition rate.

  Except for using tungsten in place of zirconium, everything was the same as in Example 2 so that the atomic weight ratio of nickel, tungsten and magnesium metal elements was 1: 1: 8, which was the same as in Example 2, and alumina was 50% by mass. It prepared so that it might become.

  This catalyst was designated as No. 2 of Example 2. As a result of conducting the reforming experiment for 8 hours under the conditions of 12, the decomposition rate of the simulated tar was 87.9%, the carbon deposition rate was 9.6%, and the hydrogen amplification rate was 2.5 times. In the same manner as above, it has been confirmed that it has stable and very high reforming activity and exhibits a low carbon deposition rate.

  Except for using manganese in place of zirconium, everything was the same as in Example 2 so that the atomic weight ratio of nickel, manganese and magnesium metal elements was 1: 1: 8 which was the same as in Example 2, and 50% by mass of alumina. It prepared so that it might become.

  This catalyst was designated as No. 2 of Example 2. As a result of the reforming experiment for 8 hours under the conditions of 12, the decomposition rate of the simulated tar was 88.1%, the carbon deposition rate was 9.8, and the hydrogen amplification rate was 2.5 times. Similarly, it has been confirmed that it has stable and very high reforming activity and exhibits a low carbon deposition rate.

  Except for using zinc in place of zirconium, the same procedure as in Example 2 was performed so that the atomic weight ratio of nickel, zinc and magnesium metal elements was 1: 1: 8, which was the same as in Example 2, and 50% by mass of alumina. It prepared so that it might become.

  This catalyst was designated as No. 2 of Example 2. As a result of conducting the reforming experiment for 8 hours under the conditions of 12, the decomposition rate of the simulated tar was 88.0%, the carbon deposition rate was 10.1%, and the hydrogen amplification rate was 2.5 times. In the same manner as above, it has been confirmed that it has stable and very high reforming activity and exhibits a low carbon deposition rate.

  Except for using strontium instead of zirconium, the same procedure as in Example 2 was performed so that the atomic weight ratio of nickel, strontium, and magnesium was 1: 1: 8, which was the same as in Example 2, and 50% by mass of alumina. It prepared so that it might become.

  This catalyst was designated as No. 2 of Example 2. As a result of the reforming experiment for 8 hours under the condition of 12, the decomposition rate of the simulated tar was 88.0%, the carbon deposition rate was 10.0%, and the hydrogen amplification rate was 2.5 times. In the same manner as above, it has been confirmed that it has stable and very high reforming activity and exhibits a low carbon deposition rate.

  Except for using tantalum instead of zirconium, the same procedure as in Example 2 was performed so that the atomic weight ratio of nickel, tantalum, and magnesium was 1: 1: 8, which was the same as in Example 2, and 50% by mass of alumina. It prepared so that it might become.

  This catalyst was designated as No. 2 of Example 2. As a result of the reforming experiment for 8 hours under the condition of 12, the decomposition rate of the simulated tar was 87.9%, the carbon deposition rate was 10.3%, and the hydrogen amplification rate was 2.5 times. In the same manner as above, it has been confirmed that it has stable and very high reforming activity and exhibits a low carbon deposition rate.

Except for using 30 cm ^{3 of} a catalyst calcined at 950 ° C. so that the mass% of each metal element and alumina in the oxides of nickel, magnesium, zirconium and aluminum are as shown in Tables 3 and 4, as in Example 2. A catalyst was prepared. As experimental conditions, No. 2 in Example 2 was used. Evaluation was performed under 12 conditions. The results are shown in Tables 3 and 4.

  As a result of Tables 3 and 4, the smaller the Ni content as the main active component, the lower the decomposition rate of 1-methylnaphthalene, the lower the hydrogen amplification rate, and the Ni mass of less than 1% by mass. In the case of 17, both the decomposition rate and the hydrogen amplification rate were low. On the other hand, the higher the Ni content, the higher the decomposition rate and the hydrogen amplification rate. However, the Ni mass exceeds 50 mass%. In the case of 29, the carbon deposition amount was large.

  No. 20 and no. When 25 was compared, even if the Ni content was almost equivalent, the catalyst activity was higher when the alumina component was larger due to the difference in the alumina content. This is presumably because the alumina component finely divided the nickel magnesia compound phase, the size of the Ni metal particles precipitated during the reduction was reduced, and the reaction surface area was increased.

  Moreover, the larger the Mg content, the lower the carbon deposition rate. Furthermore, even if the Ni content was almost equivalent, the catalyst activity was higher when the Zr content was larger due to the difference in the Zr content.

In exactly the same manner as in Example 2, a catalyst fired powder in which 50% by mass of alumina was mixed with Ni _0.1 Zr _0.1 Mg _0.8 O was obtained, and the powder was press-molded into a 20 mmφ tablet using a compression molding machine, The body was prepared. The molded body was roughly pulverized in a mortar, and then adjusted to 1.0 to 2.8 mm using a sieve.

In the same manner as in Example 2, this catalyst was not reduced at all using a fixed bed reactor, and No. 2 in Example 2 was used. The reforming reaction of the simulated tar was performed under 12 reaction conditions. As a result, the methane selectivity was 2.5%, the CO selectivity was 55.6%, the CO ₂ selectivity was 24.8%, the carbon deposition rate was 5.8%, and the decomposition rate was 88.7%. The hydrogen amplification factor was 2.2 times. Thus, the catalyst obtained by this preparation method is a simulated tar without being subjected to a reduction treatment in advance even under severe conditions where it is highly susceptible to sulfur poisoning and has high carbon deposition properties. It can be seen that the decomposition reaction of 1-methylnaphthalene proceeds.

The catalyst was prepared and evaluated in the same manner as in Example 2 except that the reaction temperature was 800 ° C., the H ₂ S concentration was 2000 ppm, and H ₂ O, CO ₂ and O ₂ were introduced so as to satisfy the conditions shown in Table 5. It was. The results are shown in Table 5. Here, C in _{H 2 O / C, CO 2} / C and _O 2 / C indicates the C supply amount of the supplied methylnaphthalene.

表５の結果、外部からＨ_２ＯやＣＯ_２やＯ_２を導入することにより、実施例２のＮｏ．１２の結果と比較すると、改質反応が進むことが確認された。なお、Ｏ_２を導入する場合、Ｈ_２ＯによるスチームリフォーミングやＣＯ_２によるドライリフォーミングの吸熱を燃焼熱で熱補償できるため、実際の反応器を想定した場合、非常に有効な手法である。また、Ｏ_２を導入することにより炭素析出率がさらに低下した。

As a result of Table 5, by introducing H ₂ O, CO ₂ or O ₂ from the outside, No. 2 in Example 2 was obtained. Compared with the result of 12, it was confirmed that the reforming reaction proceeds. In addition, when introducing O ₂ , the heat absorption of steam reforming by H ₂ O and dry reforming by CO ₂ can be compensated by combustion heat, so this is a very effective method when an actual reactor is assumed. . Moreover, the carbon deposition rate further decreased by introducing O ₂ .

  A batch furnace capable of simulating a coke oven is charged with 80 kg of charging coal used in an actual coke oven and heated to match the actual coke oven to generate actual coke oven gas and accompanying actual tar. It was. The gas was collected with a suction pump and used in the experiment. A reaction tube is placed inside an electric furnace heated to a reaction temperature of 800 ° C., and a ring-shaped catalyst having the same composition as in Example 2 is placed in the center, and hydrogen flows at 10 NL / min. Then, after the reduction for 2 hours, the catalytic cracking activity of the actual coke oven gas and the accompanying real tar was continuously evaluated for 5 hours by flowing the gas collected from the batch furnace to the catalyst layer.

  The inlet gas flow rate was 10 NL / min, and the catalyst filling amount was about 1 L. The inlet gas composition was confirmed by gas chromatography to be almost the same as the actual coke oven gas. Further, it was confirmed that 2400 to 2500 ppm of hydrogen sulfide was contained in the gas.

  The tar decomposition rate was evaluated by sampling and weighing gas from the inlet and outlet of the catalyst layer. As a result, the tar decomposition rate reached 89% on average and the hydrogen amplification rate reached 2.5 times on average. The tar decomposition rate is the ratio of the tar mass in the catalyst layer outlet gas to the tar mass in the catalyst layer inlet gas.

After allowing the reaction to proceed for 8 hours under the conditions of Example 1, the charging of the raw materials was stopped, N ₂ 60 mL / min as the carrier gas, and H ₂ O as a gas equivalent of 60 mL / min were supplied, and the catalyst layer The temperature was maintained at 800 ° C. for 5 hours to remove carbon and sulfur deposited on the catalyst. After that, when the starting of the raw material was newly started under the same conditions as in Example 1, it was confirmed that 90% or more of the activity before regeneration was exhibited. In addition, the hydrogen concentration in the reformed gas in this test was high, and it was confirmed that hydrogen, carbon monoxide, and methane were converted to the main gas.

As in Example 16, the reaction was continued for 8 hours under the conditions of Example 1, and then the starting materials were stopped, N ₂ 60 mL / min and air 60 mL / min were supplied as carrier gases, and the catalyst layer The temperature was maintained at 800 ° C. for 2 hours to remove carbon and sulfur deposited on the catalyst. After that, when the starting of the raw material was newly started under the same conditions as in Example 1, it was confirmed that 90% or more of the activity before regeneration was exhibited. In addition, the hydrogen concentration in the reformed gas in this test was high, and it was confirmed that hydrogen, carbon monoxide, and methane were converted to the main gas.

  Using 1 g of the catalyst prepared in the same manner as in Example 2, cedar flour (about 0.2 mm, C: 51.1%, H: 5.9%, O: 42. 5%, N: 0.1%, ash content: 0.3%).

Cedar flour was continuously supplied from the top of the fixed bed reactor using N ₂ as a carrier gas. The reaction temperature was controlled by a thermocouple attached to the reactor outer wall. The flow rate of the product gas was measured with a soap film flow meter, and the gas composition was analyzed using a gas chromatograph. The gas chromatograph used was Shimadzu CG-14B, and H ₂ was analyzed using TCD (Molecular Sieve 13X), and the other products were analyzed using FID (Gas Cropac 54). I went there.

The reactor used was a dual bed system in which the reforming catalyst and char (deposited solid carbon component) were stored separately. As an advantage of the dual bed system, the char life and ash generated during the gasification of biomass are not brought into direct contact with the catalyst, so that the catalyst life can be extended. Moreover, the composition of the product gas can be made more useful by not gasifying the char that only becomes CO ₂ even if it is burned. A dewar with ice was installed downstream of the reactor to trap steam and tar.

  The test conditions are as follows.

Reforming catalyst amount: 1 g
Cedar powder supply rate: 60 mg / min (C: 2191 μmol / min, H: 3543 μmol / min, O: 1475 μmol / min),
Carrier gas N ₂ : 60 mL / min, H ₂ O / C = 0.5 (H ₂ O: 1110 μmol / min),
Reaction time: 15 minutes,
Hydrogen reduction: 500 ° C., 30 minutes.

The performance of the reforming catalyst was judged by the tar decomposition rate (Tar-conv.%), The H ₂ production rate of the outlet gas, and the hydrogen composition in the outlet gas, and these were calculated by the following formula. The production rate, gas composition, and inlet tar (Tar) amount of the biomass gasification gas generated under the test conditions are as shown in Table 6, and the concentration of hydrogen sulfide contained in the gas was about 20 ppm.

coke% = (C atomic weight in coke) / (total C atomic weight of supplied biomass)
× 100

char% = (C atomic weight in char) / (Total C atomic weight of supplied biomass)
× 100

  tar% = (100- (C-conv.%)-(char%)-(coke%))

Inlet Tar amount (mg · min ⁻¹ ) = Inlet tar% × (of supplied biomass
Total C supply speed)

Outlet Tar amount (mg · min ⁻¹ ) = Outlet tar% × (of supplied biomass
Total C supply speed)

Tar-conv. % = (1- (Exit Tar amount mg · min ⁻¹ ))
/ (Inlet Tar amount mg · min ⁻¹ ) × 100

  The coke is carbon deposited on the surface of the reforming catalyst, and the char is a fixed carbon content generated by pyrolysis of biomass and remaining without being gasified.

  The measuring method of C atomic weight in coke and C atomic weight in char is as follows.

(C atomic weight in coke)
(1) After the reforming test for 15 minutes, the supply of biomass is stopped, and N ₂ is added to the reactor to drive off the gas in the reactor.
(2) O ₂ is added from the upper part of the reactor 1, and the amount of CO and CO ₂ generated during combustion of char generated in the reforming catalyst is measured with a gas chromatograph.
(3) Calculate the amount of C atoms in the char from the amount of CO and CO ₂ generated.

(C atomic weight in char)
(1) After the measurement of the amount of C in coke is completed, the addition of O ₂ from the top of the reactor is stopped, and O ₂ from the bottom of the reactor is added.
(2) The amount of CO and CO ₂ generated during char combustion is measured with a gas chromatograph in the same manner as the measurement of C content in coke.
(3) Calculate the amount of C atoms in the char from the amount of CO and CO ₂ generated.

  In the fixed bed reactor as described above, the reforming test was conducted for 15 minutes at the temperatures of 550, 600 and 650 ° C. as shown in Table 1. The results of the production rate, gas composition, outlet Tar amount and decomposition rate are obtained. Compared with Table 6, the tar decomposition rate (Tar-conv.) Is high and hydrogen is greatly amplified at any reaction temperature (hydrogen It was confirmed that gas production rate or hydrogen gas composition) and highly active performance were exhibited.

As the reforming apparatus using purified COG, equipment having a reformed gas flow rate of about 400 Nm ³ / h was used in the same test plant except that the scale of a normal hydrogen production plant was reduced.

  Four catalyst-packed reaction tubes of about 80 mmφ and about 10 m were installed in the reforming furnace, and the catalysts formed in the same ring shape as in Example 15 were used as reforming catalysts there. 25 kg, a total of about 100 kg was filled.

  A burner installed on the ceiling of the reforming furnace is ignited, the inside of the furnace is heated by a downfire method in which the flame is directed downward, and the reaction tube is heated by the radiant heat to raise the temperature to a predetermined temperature. did. The high-temperature exhaust gas was passed through a heat exchanger to heat purified COG as a raw material gas. Further, steam was used as a modifier, and pure water was heated by a boiler, and then heated steam by heat exchange with the exhaust gas from the reforming furnace and introduced from the upper part of the reaction tube together with purified COG.

Prior to the reaction, after setting the condition of nitrogen gas to about 900 ° C. and normal pressure, switch to a gas in which water vapor is mixed from nitrogen to hydrogen (water vapor molar ratio / hydrogen molar ratio = 7) for reduction treatment. And held at about 200 Nm ³ / h for 3 hours. The obtained reformed gas was cooled with a cooler installed at the outlet of the reaction tube, and after removing water with a water separator, the gas composition was analyzed by gas chromatography.

The raw material gas used here was subjected to the concentration of hydrogen sulfide by a desulfurization apparatus filled with an iron oxide (Fe ₂ O ₃ ) -based commercial catalyst (manufactured by Zude Chemie, N-IDS) after the purified COG purified by a conventional method. What was desulfurized to about 0.5 ppm was used.

The raw material gas thus desulfurized and the water vapor as the modifier are each set so that the ratio (S / C) of the number of moles of water vapor to the number of carbon moles of the hydrocarbon component in the raw material gas is 1. About 260 Nm ³ / h and about 80 Nm ³ / h (equivalent to about 60 kg / h) were introduced into the reaction tube. The reaction temperature and pressure were adjusted so that the outlet temperature and pressure of the reaction tube were about 900 ° C. and normal pressure, and the operation was performed for about 1000 hours. As a result, a synthesis gas of about 400 Nm ³ / h could be stably obtained as the reformed gas.

[Comparative example]
In the same experimental method as in Example 2, No. 2 in Example 2 was used. When a reforming test was carried out using a naphtha primary reforming catalyst (SC11NK; Ni-20 mass% supported alumina) manufactured by Sued Chemie, which is one of industrial catalysts, as a catalyst under the conditions of 12, a methane selectivity was 2.5. %, CO selectivity was 4.2%, CO ₂ selectivity was 5.9%, carbon deposition rate was 32.8%, decomposition rate was 45.4%, and hydrogen amplification rate was 1.3 times.

  Therefore, the industrial catalyst had a low conversion rate of 1-methylnaphthalene to a gas component (12.6%), but a very high carbon deposition rate. An industrial catalyst has a very high carbon deposition rate, and thus there is a possibility that the catalyst life is short. Even if the regeneration process is performed after the reaction, it is necessary to perform the oxidation process for a high temperature or for a long period of time. Is done.

[Comparative Example 2]
The same test equipment as in Example 15 was used, and the evaluation was performed by installing the industrial catalyst (SC11NK) used in Comparative Example 1 in the reaction tube under the same conditions. As a result, the tar decomposition rate was only 22% and the hydrogen amplification rate was about 1.5 times, and it was found that the industrial catalyst had a low tar decomposition rate even when evaluated under actual coke oven gas and actual tar.

[Comparative Example 3]
In the same manner as in Example 2, a nickel and magnesium precipitate was prepared, filtered, washed and dried, and then fired in air at 950 ° C. to obtain a nickel and magnesia compound. Thereafter, the alumina powder was weighed to 50% by mass, and both were physically mixed using a mortar. The mixture was molded and baked by the same experimental method as in Example 2, and then No. 2 in Example 2. The activity was evaluated under the same conditions as in No. 12. As a result, the catalytic activity was such that the decomposition rate of 1-methylnaphthalene was about 66.7%, and the hydrogen amplification rate was 1.6 times, that is, medium.

  According to the present invention, tar-containing gas generated when coal or biomass is pyrolyzed can be stably converted into light chemical substances such as carbon monoxide and hydrogen. Furthermore, after reforming the tar-containing gas, it is possible to regenerate the catalyst by contacting at least one of water vapor or air with the catalyst after the reaction, and use the regenerated catalyst again for reforming the tar-containing gas. This enables stable operation over a long period of time while suppressing deterioration of catalyst performance. Therefore, heat sources that have not been used in the steel industry in particular can be used, and industrial applicability is great.

1 Ascending pipe 2 Aqueous water (ammonia water)
3 Coke oven 4 Dry main

Claims (22)

aM ・ bNi ・ cMg ・ dO
A catalyst for reforming a tar-containing gas that is a composite oxide represented by:
a, b, and c satisfy a + b + c = 1, 0.02 ≦ a ≦ 0.98, 0.01 ≦ b ≦ 0.97, and 0.01 ≦ c ≦ 0.97,
d is a value at which oxygen and positive elements are electrically neutral;
A tar-containing gas reforming catalyst, wherein M is at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta.   The tar-containing gas reforming catalyst according to claim 1, wherein at least one oxide selected from silica, alumina, and zeolite is added to the composite oxide. Method of modifying a tar-containing gas, which comprises using a reforming catalyst of tar-containing gas any crab according to claim 1 or 2. In the presence of the tar-containing gas reforming catalyst or in the presence of the catalyst after reduction, hydrogen, carbon dioxide, and water vapor in the tar-containing gas generated when the carbonaceous raw material is pyrolyzed are brought into contact with each other. The method for reforming a tar-containing gas according to claim 3 , wherein the tar-containing gas is reformed and gasified. In the presence of the tar-containing gas reforming catalyst or in the presence of the catalyst after reduction, the tar-containing gas generated when the carbonaceous raw material is pyrolyzed is at least one of hydrogen, carbon dioxide, and water vapor from the outside. The method for reforming a tar-containing gas according to claim 3 or 4 , wherein the tar-containing gas is reformed and gasified by bringing the gas into contact therewith. 6. The method for reforming a tar-containing gas according to claim 4, wherein an oxygen-containing gas is further added to at least one of the hydrogen, carbon dioxide, and water vapor so as to contact the tar-containing gas. The method for reforming a tar-containing gas according to any one of claims 3 to 6, wherein the tar-containing gas is a tar-containing gas containing hydrogen sulfide. The method for reforming a tar-containing gas according to any one of claims 3 to 7 , wherein the tar-containing gas is a carbonized gas generated when coal is carbonized. The method for reforming a tar-containing gas according to any one of claims 3 to 8 , wherein the tar-containing gas is a coke oven gas discharged from a coke oven. The tar-containing gas according to any one of claims 3 to 7, wherein the tar-containing gas is a carbonized gas generated when carbonized biomass or at least one of food waste biomass is dry-distilled. Gas reforming method. A method for producing a tar-containing gas reforming catalyst according to claim 1,
A precipitate is formed by coprecipitation from a mixed solution containing at least a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta. A method for producing a catalyst used for reforming a tar-containing gas, comprising producing a catalyst comprising a composite oxide containing nickel, magnesium, and a metal element by drying and calcining the precipitate. A method for producing a tar-containing gas reforming catalyst according to claim 2 ,
A precipitate is formed by coprecipitation from a mixed solution containing at least a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta. At the time of the coprecipitation or after the formation of the precipitate, a silicon or aluminum component is added to obtain a mixture containing nickel, magnesium, a metal element, and silicon or aluminum, and the mixture is at least dried and fired, A method for producing a catalyst used for reforming a tar-containing gas, comprising producing a catalyst comprising a mixture containing magnesium, a metal element, and an oxide of silicon or aluminum. A method for producing a tar-containing gas reforming catalyst according to claim 2 ,
A precipitating agent is added to a mixed solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, Ta, nickel, magnesium And a metal element are co-precipitated to form a precipitate, and then the precipitate is dried and calcined to produce an oxide of nickel, magnesium, and a metal element. Water or silica sol or alumina powder and water, or alumina sol or zeolite powder and water are mixed to form a mixture, and then the mixture is at least dried and calcined to produce a catalyst. A process for producing a catalyst used for reforming a tar-containing gas, characterized in that 14. The method for producing a catalyst for reforming a tar-containing gas according to claim 13 , wherein the catalyst is produced by drying, pulverizing and firing, or drying, calcination, grinding, molding and firing. A method for producing a tar-containing gas reforming catalyst according to claim 2 ,
A precipitant is added to a mixed solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, and Ta, and nickel, magnesium, and After the metal element is coprecipitated to form a precipitate, silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water are added to the precipitate and mixed. A method for producing a catalyst used for reforming a tar-containing gas, characterized in that a catalyst is produced by producing a mixture by at least drying and calcining the mixture. 16. The method for producing a catalyst for reforming a tar-containing gas according to claim 15 , wherein the catalyst is produced by drying, pulverizing and firing, or drying, calcination, grinding, molding and firing. A method for producing a tar-containing gas reforming catalyst according to claim 2 ,
Adding a precipitant to a mixed solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, Ta, nickel, After coprecipitation of magnesium and metal elements to form a precipitate, silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water are added to the precipitate. To produce a mixture, and then at least dry and calcine the mixture, and further mix silica powder and water, or silica sol, or alumina powder and water, or alumina sol, or zeolite powder and water. Then, after the second mixture is produced, the catalyst is produced by at least drying and calcining the second mixture, thereby reforming the tar-containing gas. Process for preparing a catalyst employed. 18. The catalyst for reforming a tar-containing gas according to claim 17 , wherein the catalyst is produced by drying, pulverizing and firing, or drying, calcination, pulverizing, molding and firing the second mixture. Manufacturing method. A method for producing a tar-containing gas reforming catalyst according to claim 2 ,
Add a precipitant to a mixed solution of a metal compound containing at least one element selected from nickel compounds, magnesium compounds, Ti, Zr, W, Mn, Zn, Sr, Ba, Ta, and silicon compounds or aluminum compounds Then, nickel, magnesium, a metal element, and silicon or aluminum are co-precipitated to form a precipitate, and the precipitate is at least dried and calcined to produce a catalyst. The manufacturing method of the catalyst used for quality. 20. The method for producing a catalyst for reforming a tar-containing gas according to claim 19 , wherein the catalyst is produced by drying, pulverizing and firing, or drying, calcination, pulverizing, molding and firing. . A method for producing a tar-containing gas reforming catalyst according to claim 2 ,
Using a silica or alumina as a carrier, each solution of a nickel compound, a magnesium compound, and a metal compound containing at least one element selected from Ti, Zr, W, Mn, Zn, Sr, Ba, Ta is externally applied. A method for producing a catalyst used for reforming a tar-containing gas, wherein the catalyst is attached to the carrier and dried and calcined or dried, crushed and calcined to produce a catalyst. 11. After carrying out the method for reforming a tar-containing gas according to any one of claims 3 to 10, the catalyst whose performance has been deteriorated due to at least one of carbon deposition and sulfur poisoning is subjected to at least one of water vapor and air. A method for reforming a tar-containing gas, wherein the catalyst is regenerated and used again as the tar reforming catalyst.

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