JP2018202410A - N2O decomposition catalyst structure, method for producing the same, and N2O removal apparatus having the N2O decomposition catalyst structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a long life by suppressing deterioration of N2O decomposition function even when the operating temperature is high, and to have N2O removing ability even when the operating temperature is low. It is an object of the present invention to provide a catalyst structure for decomposition, a method for producing the same, and an N2O removing device having the catalyst structure for N2O decomposition. A catalyst structure for N2O decomposition comprises a carrier having a porous structure composed of a zeolite-type compound and at least one metal oxide contained in the carrier, and the carriers communicate with each other. The metal oxide is present in at least the passage of the carrier. [Selection diagram] Fig. 1

Description

The present invention, N ₂ having a porous support and N N _{2 O} decomposition catalyst structure and a manufacturing method thereof and a iron oxide that functions as a _{2 O} decomposition catalyst structure, as well as the N _{2 O} decomposing catalyst structure for The present invention relates to an O removing device.

N ₂ O is contained in exhaust gas from a sewage sludge incinerator, exhaust gas from a thermal power plant, exhaust gas from automobiles, and the like. N ₂ O is a gas having a strong greenhouse effect and has a greenhouse effect 310 times that of carbon dioxide. Accordingly, there is a demand for reduction of N ₂ O emission into the atmosphere.

In order to reduce N ₂ O emission, N ₂ O is decomposed and then released into the atmosphere. Examples of the N ₂ O decomposition catalyst include iron oxide, platinum, cobalt, cobalt oxide, copper, copper oxide, nickel, nickel oxide, and various metals and metal oxides.

As a structure of the N ₂ O decomposition catalyst, a catalyst packed bed filled with a pellet-shaped iron-zeolite catalyst is disclosed (Patent Document 1). As described above, the N ₂ O decomposition catalyst may be used while being supported on a support such as zeolite.

However, conventional N ₂ O decomposition catalysts such as iron oxide and platinum have a problem that the catalyst activity is suppressed by aggregation in a carrier under a high temperature environment. In addition, the platinum catalyst has a problem that it is expensive compared to a catalyst such as iron oxide. On the other hand, although a catalyst such as iron oxide is cheaper than a platinum catalyst, the reaction start temperature is as high as 300 ° C. with respect to 100 ° C. of platinum, and there is a problem that the catalyst tends to aggregate at the reaction start temperature.

International Publication No. 2011/114609

However, in the catalyst structure as described above, since the catalyst particles are supported on or near the surface of the support, the force received from the fluid containing N ₂ O during N ₂ O decomposition, the temperature during the decomposition reaction, etc. Due to the influence, the catalyst particles move within the carrier, and aggregation (sintering) between the catalyst particles easily occurs. If the catalyst particles agglomerate, the effective surface area of the catalyst is reduced and the catalyst activity is reduced, so the life is shorter than usual. Therefore, the catalyst structure itself must be replaced and regenerated in a short period of time. In addition, there are problems that the replacement work is complicated and resource saving cannot be achieved. Further, when the temperature use of the catalyst structure is in the cold state, since the activity of N 2 _O decomposition catalyst decreases, N 2 _O removal capability can not be obtained.

The object of the present invention is to realize a long life by suppressing the degradation of the N ₂ O decomposition function even when the use temperature is high, and has N ₂ O removal ability even when the use temperature is low. N 2 _O decomposition catalyst structure and method of manufacturing the same, and to provide a N _{2 O} removal device having the N _{2 O} decomposing catalyst structure.

As a result of intensive studies to achieve the above object, the inventors of the present invention comprise a porous structure carrier composed of a zeolite-type compound, and at least one metal oxide present in the carrier, The carrier has a passage communicating with each other, and the metal oxide is present in at least the passage of the carrier, so that a decrease in the catalytic activity of the metal oxide can be suppressed and a long life can be realized. It has been found that a catalyst structure for ₂ O decomposition can be obtained, and the present invention has been completed based on such knowledge.

That is, the gist configuration of the present invention is as follows.
[1] a porous support composed of a zeolite-type compound;
At least one metal oxide inherent in the support;
With
The carrier has passages communicating with each other;
A catalyst structure for N ₂ O decomposition, wherein the metal oxide is present in at least the passage of the carrier.
[2] The passage includes any one of a one-dimensional hole, a two-dimensional hole, and a three-dimensional hole defined by a skeleton structure of the zeolite-type compound, and the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. The catalyst structure for N ₂ O decomposition according to the above [1], wherein the catalyst has a diameter-expanded portion different from any of the above, and the metal oxide is present at least in the diameter-expanded portion. body.
[3] The N _{2 portion according} to [2], wherein the enlarged diameter portion communicates a plurality of holes constituting any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. Catalyst structure for O decomposition.
[4] The catalyst structure for N ₂ O decomposition according to the above [2] or [3], wherein the metal oxide is metal oxide fine particles.
[5] The N ₂ O decomposition according to the above [4], wherein an average particle diameter of the metal oxide fine particles is larger than an average inner diameter of the passage and not more than an inner diameter of the expanded portion. Catalyst structure.
[6] The metal element (M) of the metal oxide fine particles is contained in an amount of 0.5 to 2.5% by mass with respect to the catalyst structure for N ₂ O decomposition, 4] or the catalyst structure for N ₂ O decomposition according to [5].
[7] The catalyst structure for N ₂ O decomposition according to any one of [4] to [6], wherein the metal oxide fine particles have an average particle size of 0.1 nm to 50 nm.
[8] The catalyst structure for N ₂ O decomposition according to the above [7], wherein the metal oxide fine particles have an average particle size of 0.5 nm to 14.0 nm.
[9] The ratio according to any one of [4] to [8] above, wherein the ratio of the average particle diameter of the metal oxide fine particles to the average inner diameter of the passage is 0.06 to 500. Catalyst structure for ₂ O decomposition.
[10] The catalyst structure for N ₂ O decomposition according to [9], wherein a ratio of an average particle diameter of the metal oxide fine particles to an average inner diameter of the passage is 0.1 to 45 .
[11] The catalyst for N ₂ O decomposition according to [10], wherein a ratio of an average particle diameter of the metal oxide fine particles to an average inner diameter of the passage is 1.7 to 4.5. Structure.
[12] The average inner diameter of the passage is 0.1 nm to 1.5 nm,
The catalyst structure for N ₂ O decomposition according to any one of [2] to [11] above, wherein an inner diameter of the expanded portion is 0.5 nm to 50 nm.
[13] The catalyst structure for N ₂ O decomposition according to any one of the above [1] to [12], further comprising at least one other metal oxide held on the outer surface of the support body.
[14] The content of the at least one metal oxide present in the support is greater than the content of the at least one other metal oxide held on the outer surface of the support. The catalyst structure for N ₂ O decomposition according to the above [13].
[15] The catalyst structure for N ₂ O decomposition according to any one of [1] to [14], wherein the zeolite-type compound is a silicate compound.
[16] An N ₂ O removal apparatus having the N ₂ O decomposition catalyst structure according to any one of [1] to [15].
[17] A firing step of firing a precursor material (B) obtained by impregnating a precursor material (A) with a metal-containing solution into a porous structure carrier composed of a zeolite-type compound;
A hydrothermal treatment step of hydrothermally treating the precursor material (C) obtained by firing the precursor material (B);
It characterized by having a method for producing a N 2 _O decomposition catalyst structure.
[18] The N _{2 according} to the above [17], wherein a nonionic surfactant is added in an amount of 50 to 500% by mass with respect to the precursor material (A) before the firing step. A method for producing a catalyst structure for O decomposition.
[19] Before the firing step, the precursor material (A) is impregnated with the metal-containing solution by adding the metal-containing solution to the precursor material (A) in a plurality of times. The method for producing a catalyst structure for N ₂ O decomposition according to [17] or [18] above,
[20] When the precursor material (A) is impregnated with the metal-containing solution before the firing step, the amount of the metal-containing solution added to the precursor material (A) is changed to the precursor material. In terms of the ratio of silicon (Si) constituting the precursor material (A) to the metal element (M) contained in the metal-containing solution added to (A) (atomic ratio Si / M), and adjusting so that 10 to 1000, the [17] the method for producing a ~ [19] _{N 2} O decomposition catalyst structure according to any one of.
[21] The method for producing a catalyst structure for N ₂ O decomposition according to [17], wherein in the hydrothermal treatment step, the precursor material (C) and a structure directing agent are mixed.
[22] The method for producing a catalyst structure for N ₂ O decomposition according to [17], wherein the hydrothermal treatment step is performed in a basic atmosphere.

According to the present invention, even when the use temperature is high, the N ₂ O decomposition function can be prevented from lowering and the life can be extended, and even when the use temperature is low, the N ₂ O removal ability is achieved. A catalyst structure for N ₂ O decomposition, a method for producing the same, and an N ₂ O removal apparatus having the catalyst structure for N ₂ O decomposition can be provided.

FIG. 1 schematically shows the internal structure of a catalyst structure for N ₂ O decomposition according to an embodiment of the present invention. FIG. 1 (a) is a perspective view (partially cross-sectional view). 1 (b) is a partially enlarged sectional view. FIG. 2 is a partially enlarged cross-sectional view for explaining an example of the function of the catalyst structure for N ₂ O decomposition of FIG. 1, FIG. 2 (a) is a sieving function, and FIG. It is a figure to do. FIG. 3 is a flowchart showing an example of a method for producing the N ₂ O decomposition catalyst structure of FIG. FIG. 4 is a schematic view showing a modification of the N ₂ O decomposition catalyst structure of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Configuration of catalyst structure for N ₂ O decomposition]
FIG. 1 is a diagram schematically showing a configuration of a catalyst structure for N ₂ O decomposition according to an embodiment of the present invention, wherein (a) is a perspective view (a part is shown in a cross section), (b). FIG. Note that the N ₂ O decomposition catalyst structure in FIG. 1 shows an example, and the shape, dimensions, and the like of each component according to the present invention are not limited to those in FIG.

As shown in FIG. 1 (a), a catalyst structure 1 for N ₂ O decomposition comprises a porous structure carrier 10 composed of a zeolite-type compound and at least one N ₂ O present in the carrier 10. A metal oxide which is a catalytic material for decomposition, preferably metal oxide fine particles 20.

In the N ₂ O decomposition catalyst structure 1, the plurality of metal oxide fine particles 20, 20,... Are enclosed within the porous structure of the support 10. Details of the metal oxide fine particles 20 will be described later.

  The carrier 10 has a porous structure and, as shown in FIG. 1 (b), preferably has a plurality of holes 11a, 11a,. Here, the metal oxide fine particles 20 are present in at least the passage 11 of the carrier 10, and are preferably held in at least the passage 11 of the carrier 10.

With such a configuration, the movement of the metal oxide fine particles 20 in the carrier 10 is restricted, and aggregation of the metal oxide fine particles 20 and 20 is effectively prevented. As a result, the reduction of the effective surface area as the metal oxide fine particles 20 can be effectively suppressed, and the catalytic activity of the metal oxide fine particles 20 that is the catalyst material for N ₂ O decomposition lasts for a long time. That is, according to the catalyst structure 1 for N ₂ O decomposition, it is possible to suppress a decrease in catalyst activity due to aggregation of the metal oxide fine particles 20, and to extend the life of the catalyst structure 1 for N ₂ O decomposition. . Further, N by 2 _O service life of the cracking catalyst structure 1, it can be reduced frequency of replacement of the N 2 _O decomposing catalyst structure 1, significant waste of spent N _{2 O} decomposition catalyst structure 1 Can be reduced to save resources.

Usually, when the catalyst structure for N ₂ O decomposition is used in a fluid containing N ₂ O, there is a possibility of receiving an external force from the fluid. In this case, if the metal oxide fine particles 20 are merely held on the outer surface of the carrier 10, there is a problem that the metal oxide fine particles 20 are easily detached from the outer surface of the carrier 10 due to an external force from the fluid. On the other hand, in the catalyst structure 1 for N ₂ O decomposition, the metal oxide fine particles 20 are present in at least the passage 11 of the carrier 10, so that the metal oxide is oxidized from the carrier 10 even if affected by the external force due to the fluid. The object fine particles 20 are not easily detached. That is, when the N ₂ O decomposition catalyst structure 1 is in the fluid, the fluid flows into the passage 11 from the hole 11a of the carrier 10, and therefore the speed of the fluid flowing in the passage 11 is determined by the flow resistance ( The frictional force) is considered to be slower than the speed of the fluid flowing on the outer surface of the carrier 10. Due to the influence of the flow path resistance, the pressure that the metal oxide fine particles 20 held in the passage 11 receive from the fluid is lower than the pressure that the metal oxide fine particles receive from the fluid outside the support 10. Therefore, separation of the metal oxide fine particles 20 existing in the carrier 10 can be effectively suppressed, and the catalytic activity of the metal oxide fine particles 20 that is a catalyst material for N ₂ O decomposition can be stably maintained over a long period of time. Is possible. The flow path resistance as described above is considered to increase as the passage 11 of the carrier 10 has a plurality of bends and branches and the inside of the carrier 10 has a more complicated and three-dimensional structure. .

  Further, the passage 11 includes any one of a one-dimensional hole, a two-dimensional hole, and a three-dimensional hole defined by a skeleton structure of the zeolite type compound, and the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. Preferably, the metal oxide fine particles 20 are present at least in the enlarged diameter portion 12 and are at least included in the enlarged diameter portion 12. More preferably. As used herein, a one-dimensional hole means a tunnel-type or cage-type hole forming a one-dimensional channel, or a plurality of tunnel-type or cage-type holes forming a plurality of one-dimensional channels (a plurality of one-dimensional holes). Channel). A two-dimensional hole refers to a two-dimensional channel in which a plurality of one-dimensional channels are two-dimensionally connected. A three-dimensional hole refers to a three-dimensional channel in which a plurality of one-dimensional channels are three-dimensionally connected. Point to. Thereby, the movement of the metal oxide fine particles 20 in the carrier 10 is further regulated, and the separation of the metal oxide fine particles 20 and the aggregation of the metal oxide fine particles 20 and 20 can be more effectively prevented. The inclusion means a state in which the metal oxide fine particles 20 are encapsulated in the carrier 10. At this time, the metal oxide fine particles 20 and the carrier 10 do not necessarily need to be in direct contact with each other, and another substance (for example, a surfactant or the like) is present between the metal oxide fine particles 20 and the carrier 10. The metal oxide fine particles 20 may be indirectly held on the carrier 10 with the intervening state.

  FIG. 1B shows a case where the metal oxide fine particles 20 are enclosed by the enlarged diameter portion 12, but the present invention is not limited to this configuration, and the metal oxide fine particles 20 are partially expanded. You may hold | maintain at the channel | path 11 in the state protruded outside the diameter part 12. As shown in FIG. Further, the metal oxide fine particles 20 may be partially embedded in a portion of the passage 11 other than the enlarged diameter portion 12 (for example, an inner wall portion of the passage 11), or may be held by fixing or the like. Moreover, it is preferable that the enlarged diameter part 12 is connecting the some hole 11a and 11a which comprise either of the said one-dimensional hole, the said two-dimensional hole, and the said three-dimensional hole. Thereby, since a separate passage different from the one-dimensional hole, the two-dimensional hole, or the three-dimensional hole is provided in the inside of the support 10, the catalytic function of the metal oxide fine particles 20 can be exhibited more.

  The passage 11 is formed in a three-dimensional manner inside the carrier 10 including a branch portion or a merge portion, and the enlarged diameter portion 12 is preferably provided in the branch portion or the merge portion of the passage 11. .

The average inner diameter _DF of the passage 11 formed in the carrier 10 is calculated from the average value of the short diameter and the long diameter of the hole 11a constituting any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. The thickness is 0.1 nm to 1.5 nm, preferably 0.5 nm to 0.8 nm. Further, the inner diameter _DE of the enlarged diameter portion 12 is, for example, 0.5 nm to 50 nm, preferably 1.1 nm to 40 nm, and more preferably 1.1 nm to 3.3 nm. The inner diameter D _E of the enlarged diameter section 12 depends on for example the pore size of which will be described later precursor material (A), and the average particle diameter D _C of the metal oxide particles 20 to be inclusion. The inner diameter _DE of the enlarged diameter portion 12 is a size that can enclose the metal oxide fine particles 20.

The carrier 10 is composed of a zeolite type compound. Therefore, even if the use temperature of the catalyst structure 1 for N ₂ O decomposition is low and sufficient catalytic activity cannot be obtained, N ₂ O contained in the fluid is zeolite type due to the adsorption ability of the zeolite type compound. Adsorbed on the compound, N ₂ O is removed from the fluid.

  Zeolite type compounds include, for example, zeolites (aluminosilicates), cation exchange zeolites, silicate compounds such as silicalite, zeolite related compounds such as aluminoborate, aluminoarsenate, germanate, molybdenum phosphate, etc. And phosphate-based zeolite-like substances. Among these, the zeolite type compound is preferably a silicate compound.

  The framework structure of zeolite type compounds is FAU type (Y type or X type), MTW type, MFI type (ZSM-5), FER type (ferrierite), LTA type (A type), MWW type (MCM-22) , MOR type (mordenite), LTL type (L type), BEA type (beta type), etc., preferably MFI type, more preferably ZSM-5. In the zeolite type compound, a plurality of pores having a pore size corresponding to each skeleton structure are formed. For example, the maximum pore size of the MFI type is 0.636 nm (6.36 mm), and the average pore size is 0.560 nm (5.60 mm). is there.

Hereinafter, the metal oxide fine particles 20 that are N ₂ O decomposition catalyst materials will be described in detail.

And when the metal oxide fine particles 20 are primary particles, but there is a case where a secondary particle in which primary particles are formed by aggregation, the average particle diameter D _C of the metal oxide fine particles 20 are preferably passage 11 The average inner diameter D _F is larger than the inner diameter D _E of the expanded diameter portion 12 (D _F <D _C ≦ D _E ). Such metal oxide fine particles 20 are preferably present in the enlarged diameter portion 12 in the passage 11, and movement of the metal oxide fine particles 20 in the carrier 10 is restricted. Therefore, even when the metal oxide fine particle 20 receives external force from the fluid or when the use temperature of the catalyst structure 1 for N ₂ O decomposition is high, the metal oxide fine particle 20 moves within the carrier 10. It is possible to effectively prevent the metal oxide fine particles 20, 20,... Existing in each of the enlarged diameter portions 12, 12,. .

The average particle diameter _{D C} of the metal oxide particles 20, in either case of the primary particles and the secondary particles is preferably 0.1 nm to 50 nm, less than more preferably 0.1nm or 30 nm, further Preferably they are 0.5 nm-14.0 nm, Most preferably, they are 1.0 nm-3.3 nm. The ratio of the average particle diameter _{D C} of the metal oxide fine particles 20 to the average inner diameter _{D F} of the passage 11 _(D C / D _F) is preferably from 0.06 to 500, more preferably 0.1 to 45 More preferably, it is 1.1-45, Most preferably, it is 1.7-4.5. The metal element of the metal oxide particles 20 (M) is preferred to be contained at 0.5 to 2.5 mass% relative to _{N 2} O decomposition catalyst structure 1, _{N 2} O for degradation More preferably, the content is 0.5 to 1.5% by mass with respect to the catalyst structure 1. For example, when the metal element (M) is Co, the content (mass%) of the Co element is {(mass of Co element) / (mass of all elements of the catalyst structure 1 for N ₂ O decomposition)} × 100.

  The metal oxide fine particles 20 may be composed of a metal oxide. For example, the metal oxide fine particles 20 may be composed of a single metal oxide or a mixture of two or more metal oxides. Also good. In this specification, the “metal oxide” (as a material) constituting the metal oxide fine particles 20 is an oxide containing one kind of metal element (M) and two or more kinds of metal elements (M). This is a generic name for oxides containing one or more metal elements (M).

Examples of such metal oxides include cobalt oxide (CoO _x ), nickel oxide (NiO _x ), iron oxide (FeO _x ), copper oxide (CuO _x ), zirconium oxide (ZrO _x ), and cerium oxide (CeO _x ). ), Aluminum oxide (AlO _x ), niobium oxide (NbO _x ), titanium oxide (TiO _x ), bismuth oxide (BiO _x ), molybdenum oxide (MoO _x ), vanadium oxide (VO _x ), chromium oxide (CrO _x ) , Zinc oxide (ZnO _x ), and the like, and any one or more of the above are preferably used as a main component.

The ratio of silicon (Si) constituting the carrier 10 to the metal element (M) constituting the metal oxide fine particles 20 (atomic number ratio Si / M) is preferably 10 to 1000, and preferably 50 to 200. It is more preferable that If the ratio is greater than 1000, the activity as a catalytic material for N ₂ O decomposition may not be sufficiently obtained, such as low activity. On the other hand, when the ratio is less than 10, the ratio of the metal oxide fine particles 20 becomes too large, and the strength of the carrier 10 tends to decrease. The metal oxide fine particles 20 referred to here are metal oxide fine particles that are held or supported inside the carrier 10 and do not include metal oxide fine particles attached to the outer surface of the carrier 10.

[Catalytic activity of catalyst structure for N ₂ O decomposition]
As described above, the N ₂ O decomposition catalyst structure 1 includes a support 10 having a porous structure and at least one metal oxide fine particle 20 inherent in the support 10. The catalyst structure 1 for N ₂ O decomposition exhibits catalytic activity corresponding to the metal oxide fine particles 20 when the metal oxide fine particles 20 existing in the carrier 10 come into contact with a fluid. Specifically, the fluid that has contacted the outer surface 10 a of the N ₂ O decomposition catalyst structure 1 flows into the carrier 10 from the hole 11 a formed in the outer surface 10 a and is guided into the passage 11, and is then passed through the passage 11. It moves through and goes out of the catalyst structure 1 for N ₂ O decomposition through the other hole 11a. In a path in which the fluid moves through the passage 11, a reaction corresponding to the catalytic activity of the metal oxide fine particles 20 (N ₂ O decomposition reaction) by contacting with the metal oxide fine particles 20 existing in the passage 11. Occurs. Further, the N ₂ O decomposition catalyst structure 1 has molecular sieving ability because the carrier 10 has a porous structure.

First, the molecular sieving ability of the N ₂ O decomposition catalyst structure 1 will be described with reference to FIG. 2A as an example where the fluid is a gas containing N ₂ O. As shown in FIG. 2A, N ₂ O molecules having a size smaller than the hole diameter of the hole 11 a, in other words, smaller than the inner diameter of the passage 11 can flow into the carrier 10. On the other hand, the non-N ₂ O molecules 15 having a size exceeding the hole diameter of the holes 11 a cannot flow into the carrier 10. Thus, when the fluid contains a plurality of types of compounds, the reaction of the compound that cannot flow into the carrier 10 is restricted, and the compound that can flow into the carrier 10 can be reacted.

Of the compounds produced in the carrier 10 by the reaction, only compounds composed of molecules having a size equal to or smaller than the pore diameter of the pores 11a can go out of the carrier 10 through the pores 11a and are obtained as reaction products. On the other hand, a compound that cannot go out of the carrier 10 through the holes 11a can be put out of the carrier 10 if converted into a compound composed of molecules of a size that can go out of the carrier 10. . Thus, a specific reaction product can be selectively obtained by using the catalyst structure 1 for N ₂ O decomposition.

In the N ₂ O decomposition catalyst structure 1, metal oxide fine particles 20 are included in the enlarged diameter portion 12 of the passage 11 as shown in FIG. When the average particle diameter D _C of the metal oxide fine particles 20 is larger than the average inner diameter D _F of the passage 11 and smaller than the inner diameter D _E of the expanded diameter portion 12 (D _F <D _C <D _E ), the metal A small passage 13 is formed between the oxide fine particles 20 and the enlarged diameter portion 12. Therefore, as shown by the arrow in FIG. 2B, the fluid that has flowed into the small passage 13 comes into contact with the metal oxide fine particles 20. Since each metal oxide fine particle 20 is enclosed by the enlarged diameter portion 12, movement within the carrier 10 is restricted. Thereby, aggregation of metal oxide fine particles 20 and 20 in the carrier 10 is prevented. As a result, a large contact area between the metal oxide fine particles 20 and the fluid can be stably maintained.

When the N ₂ O molecules flowing into the passage 11 come into contact with the metal oxide fine particles 20, the N ₂ O molecules are decomposed into N ₂ and O ₂ by an oxidative decomposition reaction by oxygen in the metal oxide fine particles 20. For example, when iron oxide contained in the metal oxide fine particles 20 is used as a catalyst, when the N ₂ O molecules flowing into the passage 11 come into contact with the iron oxide fine particles, the N ₂ O molecules are oxidized by the oxidation reaction of oxygen in the iron oxide fine particles. By being decomposed into N ₂ and O ₂ , the concentration of N ₂ O contained in the gas can be reduced.

From the above, since the catalyst reaction start temperature of the metal oxide fine particles 20 such as iron oxide is as high as 300 ° C., even if the use temperature of the catalyst structure 1 for N ₂ O decomposition becomes high, the metal oxide fine particles 20 Since aggregation is prevented, a decrease in the N ₂ O decomposition function of the metal oxide fine particles can be suppressed. That is, even when sufficient catalytic activity cannot be obtained under conditions where the use temperature of the catalyst structure 1 for N ₂ O decomposition is low, the N ₂ O contained in the fluid is It is removed from the fluid by being adsorbed by the zeolite type compound, and even if the use temperature of the catalyst structure 1 for N ₂ O decomposition is increased, the decrease in the N ₂ O decomposition function can be suppressed. the N _{2 O} contained in the supplied fluid during adsorbed N _{2 O} and pyrolysis can be removed.

Further, an N ₂ O removing device may be formed using the N ₂ O decomposition catalyst structure 1. By using the N ₂ O decomposition catalyst structure 1 according to the above embodiment, it is possible to obtain an N ₂ O removing device that exhibits the same effect as described above.

[Method for producing catalyst structure for N ₂ O decomposition]
FIG. 3 is a flowchart showing a method for producing the N ₂ O decomposition catalyst structure 1 of FIG. Hereinafter, an example of a method for producing a catalyst structure for N ₂ O decomposition will be described, taking as an example the case where the catalyst substance present in the carrier is metal oxide fine particles.

(Step S1: Preparation process)
As shown in FIG. 3, first, a precursor material (A) for obtaining a porous support composed of a zeolite-type compound is prepared. The precursor material (A) is preferably a regular mesoporous material, and can be appropriately selected according to the type (composition) of the zeolite-type compound constituting the support of the catalyst structure for N ₂ O decomposition.

Here, when the zeolite type compound constituting the support of the catalyst structure for N ₂ O decomposition is a silicate compound, the regular mesoporous material has a one-dimensional pore having a pore diameter of 1 to 50 nm, A compound composed of a Si—O skeleton that is uniform in size in two or three dimensions and regularly developed is preferable. Such regular mesoporous materials can be obtained as various composites depending on the synthesis conditions. Specific examples of the composites include, for example, SBA-1, SBA-15, SBA-16, KIT-6, FSM- 16, MCM-41, etc., among which MCM-41 is preferable. The pore diameter of SBA-1 is 10 to 30 nm, the pore diameter of SBA-15 is 6 to 10 nm, the pore diameter of SBA-16 is 6 nm, the pore diameter of KIT-6 is 9 nm, and the pore diameter of FSM-16 is 3 -5 nm, MCM-41 has a pore diameter of 1-10 nm. Examples of such regular mesoporous materials include mesoporous silica, mesoporous aluminosilicate, and mesoporous metallosilicate.

  The precursor material (A) may be a commercially available product or a synthetic product. When the precursor material (A) is synthesized, it can be performed by a known method for synthesizing regular mesoporous materials. For example, a mixed solution containing a raw material containing the constituent elements of the precursor material (A) and a templating agent for defining the structure of the precursor material (A) is prepared, and the pH is adjusted as necessary. Hydrothermal treatment (hydrothermal synthesis) is performed. Thereafter, the precipitate (product) obtained by hydrothermal treatment is recovered (for example, filtered), washed and dried as necessary, and further calcined to form a regular mesoporous material in powder form. A precursor material (A) is obtained. Here, as a solvent of the mixed solution, for example, water, an organic solvent such as alcohol, or a mixed solvent thereof can be used. Moreover, although a raw material is selected according to the kind of support | carrier, for example, silica agents, such as tetraethoxysilane (TEOS), fumed silica, quartz sand, etc. are mentioned. Further, as the templating agent, various surfactants, block copolymers and the like can be used, and it is preferable to select according to the type of the synthesized compound of regular mesoporous materials. For example, when preparing MCM-41 A surfactant such as hexadecyltrimethylammonium bromide is preferred. The hydrothermal treatment can be performed, for example, in a sealed container at 80 to 800 ° C., 5 hours to 240 hours, and treatment conditions of 0 to 2000 kPa. The baking treatment can be performed, for example, in air at 350 to 850 ° C. for 2 to 30 hours.

(Step S2: impregnation step)
Next, the prepared precursor material (A) is impregnated with the metal-containing solution to obtain the precursor material (B).

The metal-containing solution may be a solution containing a metal component corresponding to the metal element (M) (for example, metal ion) constituting the metal oxide fine particles of the catalyst structure for N ₂ O decomposition. It can be prepared by dissolving a metal salt containing the metal element (M). Examples of such metal salts include metal salts such as chlorides, hydroxides, oxides, sulfates, nitrates, etc. Among them, nitrates are preferable. As the solvent, for example, water, an organic solvent such as alcohol, or a mixed solvent thereof can be used.

  The method of impregnating the precursor material (A) with the metal-containing solution is not particularly limited. For example, the precursor material (A) is stirred while stirring the powdery precursor material (A) before the firing step described later. It is preferable to add the metal-containing solution in small portions in multiple portions. Further, from the viewpoint of facilitating the penetration of the metal-containing solution into the pores of the precursor material (A), a surfactant as an additive is added in advance to the precursor material (A) before adding the metal-containing solution. It is preferable to add it. Such an additive has a function of coating the outer surface of the precursor material (A), suppresses the metal-containing solution added thereafter from adhering to the outer surface of the precursor material (A), and the metal It is considered that the contained solution is more likely to enter the pores of the precursor material (A).

  Examples of such additives include nonionic surfactants such as polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, and polyoxyethylene alkylphenyl ether. Since these surfactants have a large molecular size and cannot penetrate into the pores of the precursor material (A), they do not adhere to the inside of the pores, and the metal-containing solution penetrates into the pores. It is thought not to interfere. As a method for adding the nonionic surfactant, for example, it is preferable to add 50 to 500% by mass of the nonionic surfactant with respect to the precursor material (A) before the firing step described later. When the addition amount of the nonionic surfactant to the precursor material (A) is less than 50% by mass, the above-described inhibitory action is hardly exhibited, and the nonionic surfactant is added to the precursor material (A) at 500. Addition of more than% by mass is not preferable because the viscosity increases excessively. Therefore, the addition amount of the nonionic surfactant with respect to the precursor material (A) is set to a value within the above range.

The amount of the metal-containing solution added to the precursor material (A) is the amount of the metal element (M) contained in the metal-containing solution impregnated in the precursor material (A) (that is, the precursor material (B It is preferable to adjust appropriately in consideration of the amount of the metal element (M) contained in (). For example, before the firing step described later, the addition amount of the metal-containing solution added to the precursor material (A) is the metal element (M) contained in the metal-containing solution added to the precursor material (A), In terms of the ratio of silicon (Si) constituting the precursor material (A) (atomic number ratio Si / M), it is preferably adjusted to be 10 to 1000, and adjusted to be 50 to 200. It is more preferable. For example, when a surfactant is added as an additive to the precursor material (A) before the metal-containing solution is added to the precursor material (A), the addition of the metal-containing solution to be added to the precursor material (A) By converting the amount to 50 to 200 in terms of the atomic ratio Si / M, the metal element (M) of the metal oxide fine particles is 0.5 to 2 to the catalyst structure for N ₂ O decomposition. It can be contained at 5% by mass. In the state of the precursor material (B), the amount of the metal element (M) present in the pores is the same as the metal concentration of the metal-containing solution, the presence or absence of the additive, and other conditions such as temperature and pressure. If so, it is roughly proportional to the amount of the metal-containing solution added to the precursor material (A). The amount of the metal element (M) present in the precursor material (B) is proportional to the amount of the metal element constituting the metal oxide fine particles present in the support of the catalyst structure for N ₂ O decomposition. Therefore, by controlling the amount of the metal-containing solution added to the precursor material (A) within the above range, the metal-containing solution can be sufficiently impregnated inside the pores of the precursor material (A), and thus The amount of the metal oxide fine particles contained in the support of the catalyst structure for N ₂ O decomposition can be adjusted.

  After impregnating the precursor material (A) with the metal-containing solution, a cleaning treatment may be performed as necessary. As the cleaning solution, water, an organic solvent such as alcohol, or a mixed solution thereof can be used. In addition, it is preferable to impregnate the precursor material (A) with a metal-containing solution and perform a cleaning treatment as necessary, followed by a drying treatment. Examples of the drying treatment include natural drying overnight or high temperature drying at 150 ° C. or lower. In addition, the regular mesopores of the precursor material (A) are obtained by performing the baking treatment described later in a state where a large amount of moisture contained in the metal-containing solution and the moisture of the cleaning solution remain in the precursor material (A). Since the skeletal structure as a substance may be broken, it is preferable to dry it sufficiently.

(Step S3: Firing step)
Next, the precursor material (B) obtained by impregnating the precursor material (A) for impregnating the porous material structure composed of the zeolite type compound with the metal-containing solution is calcined to obtain the precursor material (C). Get.

  The firing treatment is preferably performed, for example, in the air at 350 to 850 ° C. for 2 to 30 hours. By such a baking treatment, the metal component impregnated in the pores of the regular mesoporous material grows in crystal, and metal oxide fine particles are formed in the pores.

(Step S4: Hydrothermal treatment process)
Next, a mixed solution in which the precursor material (C) and the structure directing agent are mixed is prepared, and the precursor material (C) obtained by firing the precursor material (B) is hydrothermally treated, and N ₂ A catalyst structure for O decomposition is obtained.

The structure directing agent is a templating agent for defining the skeleton structure of the support of the catalyst structure for N ₂ O decomposition, and for example, a surfactant can be used. The structure directing agent is preferably selected according to the skeleton structure of the support of the catalyst structure for N ₂ O decomposition, for example, tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), tetrapropylammonium bromide (TPABr) And the like are preferable.

  Mixing of the precursor material (C) and the structure directing agent may be performed during the main hydrothermal treatment step, or may be performed before the hydrothermal treatment step. Moreover, the preparation method of the said mixed solution is not specifically limited, A precursor material (C), a structure directing agent, and a solvent may be mixed simultaneously, or precursor material (C) and structure prescription | regulation are carried out to a solvent. After each agent is dispersed in each solution, each dispersion solution may be mixed. As the solvent, for example, water, an organic solvent such as alcohol, or a mixed solvent thereof can be used. In addition, the pH of the mixed solution is preferably adjusted using an acid or a base before hydrothermal treatment.

Hydrothermal treatment can be performed by a well-known method, for example, it is preferable to perform in 80-800 degreeC, 5 hours-240 hours, and processing conditions of 0-2000 kPa in an airtight container. The hydrothermal treatment is preferably performed in a basic atmosphere. Although the reaction mechanism here is not necessarily clear, by performing hydrothermal treatment using the precursor material (C) as a raw material, the skeleton structure of the precursor material (C) as a regular mesoporous material gradually collapses. While maintaining the position of the metal oxide fine particles inside the pores of the precursor material (C) in general, a new skeletal structure (porous) as a support for the catalyst structure for N ₂ O decomposition is obtained by the action of the structure directing agent. Quality structure) is formed. The catalyst structure for N ₂ O decomposition thus obtained comprises a porous structure carrier and metal oxide fine particles present in the carrier, and the carrier has a plurality of pores communicating with each other due to the porous structure. A metal oxide fine particle is present in the channel of the carrier. In the present embodiment, in the hydrothermal treatment step, a mixed solution in which the precursor material (C) and the structure directing agent are mixed is prepared and the precursor material (C) is hydrothermally treated. The precursor material (C) may be hydrothermally treated without mixing the precursor material (C) and the structure directing agent.

It is preferable that the precipitate (catalyst structure for N ₂ O decomposition) obtained after the hydrothermal treatment is washed, dried and calcined as necessary after collection (for example, filtration). As the cleaning solution, water, an organic solvent such as alcohol, or a mixed solution thereof can be used. Examples of the drying treatment include natural drying overnight or high temperature drying at 150 ° C. or lower. In addition, if the calcination treatment is performed in a state where a large amount of moisture remains in the precipitate, the skeleton structure as a support of the catalyst structure for N ₂ O decomposition may be broken. Moreover, a baking process can be performed on the process conditions of 350-850 degreeC and 2 to 30 hours, for example in the air. By such a calcination treatment, the structure directing agent adhering to the N ₂ O decomposition catalyst structure is burned out. Further, N 2 _O decomposition catalyst structure can also be depending on the intended use, used as it is without being calcined precipitate after recovery. For example, when the environment in which the catalyst structure for N ₂ O decomposition is used is a high-temperature environment in an oxidizing atmosphere, the structure directing agent is burned out by being exposed to the environment for a certain period of time and is the same as the case where the firing treatment is performed. Therefore, the catalyst structure for N ₂ O decomposition can be used as it is.

[Modification of N ₂ O Decomposition Catalyst Structure]
FIG. 4 is a schematic diagram showing a modification of the N ₂ O decomposition catalyst structure 1 of FIG.
1 shows a case where the catalyst structure 1 for N ₂ O decomposition includes a support 10 and metal oxide fine particles 20 inherent in the support 10, but is not limited to this configuration. For example, FIG. As shown in FIG. 4, the N ₂ O decomposition catalyst structure 2 may further include other metal oxide fine particles 30 held on the outer surface 10 a of the support 10.

The other metal oxide fine particles 30 are substances that exhibit one or more catalytic capabilities. The catalytic ability of the other metal oxide fine particles 30 may be the same as or different from the catalytic ability of the metal oxide fine particles 20. When both of the metal oxide fine particles 20 and 30 are substances having the same catalytic ability, the material of the other metal oxide fine particles 30 may be the same as the material of the metal oxide fine particles 20, May be different. According to this configuration, it is possible to increase the content of N _{2 O} decomposition catalyst material retained N 2 _O decomposition catalyst structure 2, further promoting the catalytic activity of the N 2 _O decomposing catalyst material be able to.

In this case, the content of the metal oxide fine particles 20 inherent in the carrier 10 is preferably larger than the content of the other metal oxide fine particles 30 held on the outer surface 10 a of the carrier 10. Thereby, the catalytic ability of the metal oxide fine particles 20 held inside the carrier 10 becomes dominant, and the catalytic ability of the catalytic material for N ₂ O decomposition is stably exhibited.

Further, in the present invention, N _{2 O} removal device having the N _{2 O} decomposing catalyst structure is provided. Such an N ₂ O removing device is capable of reducing the N ₂ O concentration by decomposing N ₂ O molecules into N ₂ and O ₂ using the N ₂ O decomposition catalyst structure. It does not specifically limit and the reactor etc. which are normally used can be used. By using the N ₂ O decomposition catalyst structure according to the present invention for such an N ₂ O removal apparatus, the N ₂ O removal apparatus can also exhibit the same effects as described above.

Above, exemplary N _{2 O} decomposition catalyst structure and method of manufacturing the same according to the embodiment of the present invention, as well as have been described N _{2 O} removal device having the N _{2 O} decomposing catalyst structure for the present invention the above-described embodiment The present invention is not limited to the above, and various modifications and changes can be made based on the technical idea of the present invention.

(Examples 1 to 384)
[Synthesis of Precursor Material (A)]
A mixed aqueous solution in which a silica agent (tetraethoxysilane (TEOS), manufactured by Wako Pure Chemical Industries, Ltd.) and a surfactant as a templating agent was mixed was prepared, pH was adjusted as appropriate, and 80 to 80 in a sealed container. Hydrothermal treatment was performed at 350 ° C. for 100 hours. Thereafter, the produced precipitate is filtered off, washed with water and ethanol, and further calcined in air at 600 ° C. for 24 hours to obtain a precursor material (A) having the types and pore sizes shown in Tables 1 to 8. Obtained. The following surfactants were used according to the type of the precursor material (A) (“type of precursor material (A): surfactant”).
MCM-41: hexadecyltrimethylammonium bromide (CTAB) (manufactured by Wako Pure Chemical Industries, Ltd.)
・ SBA-1: Pluronic P123 (manufactured by BASF)

[Preparation of precursor materials (B) and (C)]
Next, a metal salt containing the metal element (M) is dissolved in water according to the metal element (M) constituting the metal oxide fine particles of the types shown in Tables 1 to 8, and a metal-containing aqueous solution is obtained. Was prepared. The following metal salts were used according to the type of metal oxide fine particles (“metal oxide fine particles: metal salt”).
CoO _x : Cobalt nitrate (II) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.)
NiO _x : Nickel (II) nitrate hexahydrate (Wako Pure Chemical Industries, Ltd.)
FeO _x : Iron (III) nitrate nonahydrate (manufactured by Wako Pure Chemical Industries, Ltd.)
ZnO _x : zinc nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.)

  Next, the metal-containing aqueous solution is added to the powdery precursor material (A) in small portions in small portions, and dried at room temperature (20 ° C. ± 10 ° C.) for 12 hours or more to obtain the precursor material (B). Got.

  In addition, when the condition of the presence or absence of the additive shown in Tables 1 to 8 is “Yes”, polyoxyethylene (15) as an additive with respect to the precursor material (A) before adding the metal-containing aqueous solution A pretreatment of adding an aqueous solution of oleyl ether (NIKKOL BO-15V, manufactured by Nikko Chemicals Co., Ltd.) was performed, and then the metal-containing aqueous solution was added as described above. In the case of “None” in the presence or absence of the additive, the pretreatment with the additive as described above is not performed.

  Moreover, the addition amount of the metal-containing aqueous solution added to the precursor material (A) is the ratio of silicon (Si) constituting the precursor material (A) to the metal element (M) contained in the metal-containing aqueous solution ( The numerical values when converted to the atomic ratio (Si / M) were adjusted to the values shown in Tables 1-8.

  Next, the precursor material (B) impregnated with the metal-containing aqueous solution obtained as described above was baked in air at 600 ° C. for 24 hours to obtain a precursor material (C).

[Synthesis of catalyst structure]
The precursor material (C) obtained as described above and the structure directing agent shown in Tables 1 to 8 are mixed to prepare a mixed aqueous solution, and 80 to 350 ° C. and Tables 1 to 8 in a sealed container. Hydrothermal treatment was performed under the conditions of pH and time shown in FIG. Thereafter, the formed precipitate is filtered off, washed with water, dried at 100 ° C. for 12 hours or more, and further calcined in air at 600 ° C. for 24 hours. Catalyst structures having fine oxide particles were obtained (Examples 1 to 384).

(Comparative Example 1)
In Comparative Example 1, cobalt oxide powder (II, III) (manufactured by Sigma Aldrich Japan Godo Kaisha) having an average particle size of 50 nm or less was mixed with MFI type silicalite, and on the outer surface of silicalite as a carrier, A catalyst structure to which cobalt oxide fine particles were adhered was obtained.

(Comparative Example 2)
In Comparative Example 2, MFI type silicalite was synthesized by the same method as Comparative Example 1 except that the step of attaching the cobalt oxide fine particles was omitted.

[Evaluation]
Various characteristics of the catalyst structures of the above examples and the silicalite of the comparative example were evaluated under the following conditions.

[A] Cross-sectional observation With respect to the catalyst structures of the above examples and the cobalt oxide fine particle-attached silicalite of Comparative Example 1, an observation sample was prepared by a pulverization method, and a transmission electron microscope (TEM) (TITA G2, manufactured by FEI) was used. Using this, cross-sectional observation was performed. As a result, in the catalyst structures of the above examples, it was confirmed that the metal oxide fine particles were inherently held inside the support made of silicalite or zeolite. On the other hand, in the silicalite of Comparative Example 1, the metal oxide fine particles were only attached to the outer surface of the carrier and were not present inside the carrier.

  Moreover, about the catalyst structure whose metal oxide is iron oxide fine particles (FeOx) among the said Example, a cross section is cut out by FIB (focused ion beam) processing, SEM (SU8020, Hitachi High-Technologies Corporation make), EDX (X-Max, manufactured by Horiba, Ltd.) was used for cross-sectional elemental analysis. As a result, Fe element was detected from inside the support. From the result of cross-sectional observation by the TEM and SEM / EDX, it was confirmed that iron oxide fine particles were present inside the carrier.

[B] Average inner diameter of carrier passage and average particle diameter of catalyst substance In the TEM image taken by cross-sectional observation performed in the above evaluation [A], arbitrarily select 500 passages of the carrier, The short diameter was measured, the inner diameter was calculated from the average value (N = 500), and the average inner diameter was further calculated as the average inner diameter _DF of the carrier passage. Similarly, for the catalyst material, 500 catalyst materials are arbitrarily selected from the TEM image, each particle size is measured (N = 500), an average value thereof is obtained, and the average of the catalyst materials is determined. I was having a particle diameter _{D C.} The results are shown in Tables 1-8.

  Moreover, in order to confirm the average particle diameter and dispersion state of a catalyst substance, it analyzed using SAXS (small angle X-ray scattering). The SAXS measurement was performed using Spring-8 beam line BL19B2. The obtained SAXS data was fitted with a spherical model by the Guinier approximation method, and the particle size was calculated. The particle size was measured for a catalyst structure in which the metal oxide was iron oxide fine particles. Further, as a comparison object, commercially available iron oxide fine particles (manufactured by Wako) were observed and measured with an SEM.

  As a result, in the commercial product, iron oxide fine particles of various sizes are randomly present in the particle size range of about 50 nm to 400 nm, whereas the average particle size obtained from the TEM image is 1.2 nm to 2.0 nm. In the catalyst structure of each Example, a scattering peak having a particle size of 10 nm or less was detected in the SAXS measurement results. From the SAXS measurement result and the cross-sectional measurement result by SEM / EDX, it was found that a catalyst substance having a particle size of 10 nm or less was present in the carrier in a very dispersed state with a uniform particle size.

[C] Relationship between the addition amount of the metal-containing solution and the amount of metal included in the support The addition amount of atomic ratio Si / M = 50, 100, 200, 1000 (M = Co, Ni, Fe, Zn) Then, a catalyst structure in which metal oxide fine particles were included in the inside of the support was prepared, and then the amount of metal (mass%) included in the support of the catalyst structure prepared in the above addition amount was measured. . In this measurement, the catalyst structure having an atomic ratio of Si / M = 100, 200, 1000 is the same as the catalyst structure having an atomic ratio of Si / M = 100, 200, 1000 in Examples 1 to 384, respectively. The catalyst structure having an atomic ratio Si / M = 50 was prepared by adjusting the amount of addition of the metal-containing solution by the method described above, except that the amount of addition of the metal-containing solution was changed. = 100, 200, 1000 It was prepared by the same method as the catalyst structure.

  The amount of metal was determined by using ICP (high frequency inductively coupled plasma) alone or a combination of ICP and XRF (fluorescence X-ray analysis). XRF (energy dispersive X-ray fluorescence spectrometer “SEA1200VX”, manufactured by SSI Nanotechnology Co., Ltd.) was performed under the conditions of a vacuum atmosphere, an acceleration voltage of 15 kV (using a Cr filter), or an acceleration voltage of 50 kV (using a Pb filter). . XRF is a method of calculating the abundance of a metal by fluorescence intensity, and a quantitative value (mass% conversion) cannot be calculated with XRF alone. Therefore, the amount of metal in the catalyst structure added with metal at Si / M = 100 was quantified by ICP analysis, and the amount of metal in the catalyst structure added with metal at Si / M = 50 and less than 100 was determined by XRF measurement results. And calculated based on the ICP measurement results.

  As a result, it was confirmed that the amount of metal included in the catalyst structure increased as the amount of the metal-containing solution added increased at least in the atomic ratio Si / M in the range of 50 to 1000. It was.

[D] Performance Evaluation The catalytic ability (performance) of the catalyst material was evaluated for the catalyst structures of the above examples and the silicalite of the comparative example. The results are shown in Tables 1-8.

(1) Catalytic activity The catalytic activity was evaluated under the following conditions.

First, 0.5 g of the catalyst structure is charged into an atmospheric pressure flow reactor to form a catalyst layer, and a reaction gas having the following gas composition is adjusted to a space velocity of 10,000 hr ⁻¹ at a reaction temperature of 350 ° C. Nitrous oxide (N ₂ O) decomposition activity was measured.

<Composition of synthesis gas>
N ₂ O: 300 ppm, NO: 50 ppm, CO ₂ : 300 ppm, O ₂ : 16%, H ₂ O: 10%, N ₂ : balance

  After completion of the reaction, the collected product gas was subjected to component analysis by gas chromatography mass spectrometry (GC / MS). Note that TRACE 1310GC (manufactured by Thermo Fisher Scientific Co., Ltd., detector: thermal conductivity detector) was used as a product gas analyzer.

The concentration of nitrous oxide in the synthesis gas on the inlet side and outlet side of the catalyst layer was measured with a gas chromatograph, and the N ₂ O decomposition rate was calculated according to the following equation.
N ₂ O decomposition rate (%) = 100 × (catalyst layer inlet side N ₂ O concentration−catalyst layer outlet side N ₂ O concentration) / catalyst layer inlet side N ₂ O concentration

  Nitrous oxide decomposition performance after 20 hours from the introduction of the synthesis gas was measured.

In this example, when the N ₂ O decomposition rate (%) is 75% or more, it is determined that the catalytic activity (N ₂ O resolution) is excellent, and “◎” is 60% or more and less than 75%. In the case where the catalytic activity is good, “◯” is judged, and in the case where the catalytic activity is 55% or more and less than 60%, the catalytic activity is not good, but the acceptable level is acceptable, “Δ”, and 55 The case where it was less than% was judged that the catalyst activity was inferior (impossible), and was set as “x”.

(2) Durability (life)
The durability was evaluated under the following conditions.

First, the catalyst structure used in the evaluation (1) was collected and heated at 650 ° C. for 12 hours to produce a heated catalyst structure. Next, an N ₂ O decomposition reaction was performed by the same method as in the evaluation (1) using the obtained catalyst structure after heating.

Based on the obtained analysis results, the N ₂ O decomposition rate was determined by the same method as in the evaluation (1). Furthermore, compared with the above decomposition rate by the catalyst structure before heating (decomposition rate obtained in the above evaluation (1)), it was compared how much the above decomposition rate by the catalyst structure after heating was maintained. . Specifically, the yield of the compound by the catalyst structure after the heating (the present evaluation (2)) relative to the yield of the compound by the catalyst structure before the heating (the yield obtained in the evaluation (1)). The percentage (%) of the yield obtained in step 1) was calculated.

In this embodiment, (N _{2 O} decomposition rate obtained in this evaluation (2)) said N _{2 O} decomposition rate by the catalyst structure after heating, N _{2 O} decomposition ratio of the compounds according to the catalyst structure before heating Compared to the yield (decomposition rate of N ₂ O determined in the above evaluation (1)), when it is maintained at 80% or more, it is judged that durability (heat resistance) is excellent, “◎”, 60% The case where the durability (heat resistance) is maintained is less than 80% and the durability (heat resistance) is determined to be good, and the case where the durability is maintained from 40% to less than 60% is not good. It was determined that the product was at a pass level (possible), and “Δ”, and when it was less than 40%, the durability (heat resistance) was determined to be inferior (impossible), and “x” was assigned.

  In addition, about Comparative Examples 1-2, the same performance evaluation as said evaluation (1) and (2) was performed. In addition, the comparative example 2 is a support | carrier itself, and does not have a catalyst substance. Therefore, in the performance evaluation, only the support of Comparative Example 2 was filled instead of the catalyst structure. The results are shown in Table 8.

As is apparent from Tables 1 to 8, the catalyst structures (Examples 1 to 384) in which the catalyst substance was confirmed to be retained inside the support by cross-sectional observation were simply put on the outer surface of the support. Compared with the catalyst structure (Comparative Example 1) that is only attached and the carrier itself (Comparative Example 2) that does not have any catalytic substance, it exhibits excellent catalytic activity in the decomposition reaction of N ₂ O. As a result, it was found to be excellent in durability.

Further, the relationship between the amount of metal (mass%) included in the support of the catalyst structure measured in the evaluation [C] and the catalytic activity in the evaluation (1) was evaluated. The evaluation method was the same as the evaluation method performed in “(1) Catalytic activity” in [D] “Performance evaluation”. As a result, in each Example, the addition amount of the metal-containing solution added to the precursor material (A) is 50 to 200 in terms of the atomic ratio Si / M (the metal element of the metal oxide fine particles with respect to the catalyst structure) It was found that the catalyst activity tends to be improved in the decomposition reaction of N ₂ O when the content of (M) is 0.5 to 2.5 mass%.

On the other hand, the catalyst structure of Comparative Example 1 in which the catalyst material is attached only to the outer surface of the carrier is a catalyst in the decomposition reaction of N ₂ O as compared with the carrier of Comparative Example 2 that does not have any catalyst material. Although the activity was improved, the durability as a catalyst was inferior to the catalyst structures of Examples 1 to 384.

From the above results, it can be inferred that the catalyst structure for N ₂ O decomposition according to the present invention exhibits excellent catalytic activity in the decomposition reaction of N ₂ O and is excellent in durability as a catalyst.

1 N ₂ O decomposition catalyst structure for 10 carriers 10a outer surface 11 passages 11a hole 12 enlarged diameter portion 20 the metal oxide particles 30 metal oxide fine particles D _C average particle diameter D _F average inner diameter D _E inner diameter

Claims (22)

A porous structure carrier composed of a zeolite-type compound;
At least one metal oxide inherent in the support;
With
The carrier has passages communicating with each other;
The catalyst structure for N ₂ O decomposition, wherein the metal oxide is present in at least the passage of the carrier. The passage is any one of a one-dimensional hole, a two-dimensional hole, and a three-dimensional hole defined by a skeleton structure of the zeolite-type compound, and any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. and a different diameter portion also, and the metal oxide, characterized in that it is present in at least the enlarged diameter portion, N _{2 O} decomposition catalyst structure according to claim 1. 3. The N ₂ O decomposition catalyst according to claim 2, wherein the enlarged-diameter portion communicates a plurality of holes constituting any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. Structure. The catalyst structure for N ₂ O decomposition according to claim 2 or 3, wherein the metal oxide is metal oxide fine particles. The catalyst structure for N ₂ O decomposition according to claim 4, wherein an average particle diameter of the metal oxide fine particles is larger than an average inner diameter of the passage and not more than an inner diameter of the expanded portion. . The metal element (M) of the metal oxide fine particles is contained in an amount of 0.5 to 2.5% by mass with respect to the catalyst structure for N ₂ O decomposition. _2. A catalyst structure for N ₂ O decomposition as described in 1. The catalyst structure for N ₂ O decomposition according to any one of claims 4 to 6, wherein the metal oxide fine particles have an average particle diameter of 0.1 nm to 50 nm. The catalyst structure for N ₂ O decomposition according to claim 7, wherein an average particle diameter of the metal oxide fine particles is 0.5 nm to 14.0 nm. 9. The N ₂ O decomposition apparatus according to claim 4, wherein a ratio of an average particle diameter of the metal oxide fine particles to an average inner diameter of the passage is 0.06 to 500. Catalyst structure. The N ₂ O decomposition catalyst structure according to claim 9, wherein a ratio of an average particle diameter of the metal oxide fine particles to an average inner diameter of the passage is 0.1 to 45. 11. The catalyst structure for N ₂ O decomposition according to claim 10, wherein a ratio of an average particle diameter of the metal oxide fine particles to an average inner diameter of the passage is 1.7 to 4.5. An average inner diameter of the passage is 0.1 nm to 1.5 nm,
12. The catalyst structure for N ₂ O decomposition according to claim 2, wherein an inner diameter of the expanded portion is 0.5 nm to 50 nm. The catalyst structure for N ₂ O decomposition according to any one of claims 1 to 12, further comprising at least one other metal oxide held on the outer surface of the support. 14. The content of the at least one metal oxide inherent in the support is greater than the content of the at least one other metal oxide retained on the outer surface of the support. _2. A catalyst structure for N ₂ O decomposition as described in 1. The catalyst structure for N ₂ O decomposition according to any one of claims 1 to 14, wherein the zeolite-type compound is a silicate compound. Having _{N 2} O decomposition catalyst structure according to any one of claims 1 to 15, _{N 2} O removal device. A firing step of firing the precursor material (B) obtained by impregnating the precursor material (A) with a metal-containing solution to obtain a porous structure carrier composed of a zeolite-type compound;
A hydrothermal treatment step of hydrothermally treating the precursor material (C) obtained by firing the precursor material (B);
It characterized by having a method for producing a N 2 _O decomposition catalyst structure. 18. The N ₂ O decomposition catalyst according to claim 17, wherein a nonionic surfactant is added in an amount of 50 to 500 mass% with respect to the precursor material (A) before the firing step. Manufacturing method of structure. Before the firing step, the precursor material (A) is impregnated with the metal-containing solution by adding the metal-containing solution to the precursor material (A) in a plurality of times. the method of _{N 2} O decomposition catalyst structure according to claim 17 or 18. When the precursor material (A) is impregnated with the metal-containing solution before the firing step, the amount of the metal-containing solution added to the precursor material (A) is changed to the precursor material (A). 10 to 1000 in terms of the ratio of silicon (Si) constituting the precursor material (A) to the metal element (M) contained in the metal-containing solution added to (atom ratio Si / M) and adjusting so that the manufacturing method of the N _{2 O} decomposing catalyst structure according to any one of claims 17 to 19. The method for producing a catalyst structure for N ₂ O decomposition according to claim 17, wherein in the hydrothermal treatment step, the precursor material (C) and a structure directing agent are mixed. The method for producing a catalyst structure for N ₂ O decomposition according to claim 17, wherein the hydrothermal treatment step is performed in a basic atmosphere.

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