阅读说明：本技术 合成气体制造用催化剂结构体、具备该合成气体制造用催化剂结构体的合成气体制造装置以及合成气体制造用催化剂结构体的制造方法 (Catalyst structure for synthesis gas production, synthesis gas production apparatus provided with same, and method for producing catalyst structure for synthesis gas production ) 是由 增田隆夫 中坂佑太 吉川琢也 加藤祯宏 福岛将行 高桥寻子 马场祐一郎 关根可织 于 2018-05-31 设计创作，主要内容包括：本发明提供一种催化活性的降低得以抑制、能高效地制造包含一氧化碳和氢的合成气体的合成气体制造用催化剂结构体以及具备该合成气体制造用催化剂结构体的合成气体制造装置。本发明的合成气体制造用催化剂结构体(1)是在制造包含一氧化碳和氢的合成气体时使用的合成气体制造用催化剂结构体(1),其具备：多孔质结构的载体(10),由沸石型化合物构成；以及至少一种催化剂物质(20),存在于载体(10)内,载体(10)具有相互连通的通道(11),催化剂物质(20)为金属微粒,存在于载体(10)的至少通道(11)。(The invention provides a catalyst structure for synthesis gas production, which can suppress a decrease in catalytic activity and can efficiently produce a synthesis gas containing carbon monoxide and hydrogen, and a synthesis gas production apparatus provided with the catalyst structure for synthesis gas production. A catalyst structure (1) for synthesis gas production according to the present invention is a catalyst structure (1) for synthesis gas production used in the production of synthesis gas containing carbon monoxide and hydrogen, and comprises: a porous support (10) composed of a zeolite-type compound; and at least one catalyst substance (20) present in the carrier (10), the carrier (10) having channels (11) communicating with each other, the catalyst substance (20) being a metal particulate present in at least the channels (11) of the carrier (10).)

1. A catalyst structure for synthesis gas production, which is used for producing a synthesis gas containing carbon monoxide and hydrogen,

the catalyst structure for producing synthesis gas comprises:

a porous support composed of a zeolite-type compound; and

at least one catalyst species present within the support,

the carrier has channels that are in communication with each other,

the catalyst material is a metal particulate present in at least the channels of the support.

2. The catalyst structure for synthesis gas production according to claim 1, wherein,

the metal fine particles are fine particles made of at least one metal selected from the group consisting of rhodium (Rh), ruthenium (Ru), iridium (Ir), palladium (Pd), platinum (Pt), iron (Fe), cobalt (Co), and nickel (Ni).

3. The catalyst structure for synthesis gas production according to claim 1 or 2, wherein the catalyst structure is a catalyst structure for synthesis gas production,

the channel has: any one of one-dimensional pores, two-dimensional pores, and three-dimensional pores defined by the framework structure of the zeolite-type compound; and a diameter expanding portion which is different from any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole, and which is provided with a hole having a diameter larger than that of the hole having the one-dimensional hole

The catalyst substance is present at least in the diameter-enlarged portion.

4. The catalyst structure for synthesis gas production according to claim 3, wherein,

the diameter expanding portion communicates a plurality of holes constituting any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole with each other.

5. The catalyst structure for synthesis gas production according to claim 3 or 4, wherein,

the metal fine particles have an average particle diameter larger than an average inner diameter of the channel and equal to or smaller than an inner diameter of the enlarged diameter portion.

6. The catalyst structure for synthesis gas production according to any one of claims 1 to 5, wherein,

the metal element (M) of the metal fine particles is contained in an amount of 0.5 to 2.5 mass% relative to the synthesis gas production catalyst structure.

7. The catalyst structure for synthesis gas production according to any one of claims 1 to 6, wherein,

the metal fine particles have an average particle diameter of 0.08 to 30 nm.

8. The catalyst structure for synthesis gas production according to claim 7, wherein,

the metal fine particles have an average particle diameter of 0.4 to 11.0 nm.

9. The catalyst structure for production of synthesis gas according to any one of claims 1 to 8, wherein,

the ratio of the average particle diameter of the metal fine particles to the average inner diameter of the channel is 0.05 to 300.

10. The catalyst structure for synthesis gas production according to claim 9, wherein,

the ratio of the average particle diameter of the metal fine particles to the average inner diameter of the channel is 0.1 to 30.

11. The catalyst structure for synthesis gas production according to claim 10, wherein,

the ratio of the average particle diameter of the metal fine particles to the average inner diameter of the channel is 1.4 to 3.6.

12. The catalyst structure for production of synthesis gas according to any one of claims 3 to 11, wherein,

the average inner diameter of the channel is 0.1 nm-1.5 nm,

the inner diameter of the diameter-expanded portion is 0.5nm to 50 nm.

13. The catalyst structure for production of synthesis gas according to any one of claims 1 to 12, wherein,

the catalyst also comprises at least one other catalyst material retained on the outer surface of the support.

14. The catalyst structure for synthesis gas production according to claim 13, wherein,

the at least one catalyst species is present in the support in an amount greater than the amount of the at least one other catalyst species retained on the outer surface of the support.

15. The catalyst structure for production of synthesis gas according to any one of claims 1 to 14, wherein,

the zeolite-type compound is a silicate compound.

16. A synthesis gas production apparatus comprising the catalyst structure for synthesis gas production according to any one of claims 1 to 15.

17. A method for producing a catalyst structure for synthesis gas production, comprising:

a firing step of firing a precursor material (B) obtained by impregnating a precursor material (a) with a metal-containing solution, the precursor material (a) being used for obtaining a support having a porous structure made of a zeolite-type compound;

a hydrothermal treatment step of subjecting a precursor material (C) obtained by firing the precursor material (B) to hydrothermal treatment; and

and a step of subjecting the precursor material (C) after the hydrothermal treatment to a reduction treatment.

18. The method for producing a catalyst structure for synthesis gas production according to claim 17, wherein the catalyst structure is a catalyst structure for synthesis gas production,

before the firing step, 50 to 500 mass% of a nonionic surfactant is added to the precursor material (A).

19. The method of producing a catalyst structure for synthesis gas production according to claim 17 or 18, wherein the catalyst structure is a catalyst structure for synthesis gas production,

the metal-containing solution is added to the precursor material (a) in a plurality of portions before the firing step, whereby the precursor material (a) is impregnated with the metal-containing solution.

20. The method for producing a catalyst structure for synthesis gas production according to any one of claims 17 to 19, wherein the catalyst structure is a catalyst structure for synthesis gas production,

when the precursor material (A) is immersed in the metal-containing solution before the firing step, the amount of the metal-containing solution added to the precursor material (A) is adjusted so that the atomic ratio Si/M, which is the ratio of silicon (Si) constituting the precursor material (A) to the metal element (M) contained in the metal-containing solution added to the precursor material (A), is 10 to 1000.

21. The method for producing a catalyst structure for synthesis gas production according to claim 17, wherein the catalyst structure is a catalyst structure for synthesis gas production,

in the hydrothermal treatment step, the precursor material (C) is mixed with a structure-directing agent.

22. The method for producing a catalyst structure for synthesis gas production according to claim 17, wherein the catalyst structure is a catalyst structure for synthesis gas production,

the hydrothermal treatment step is performed in an alkaline environment.

Technical Field

The present invention relates to a catalyst structure for synthesis gas production used when a synthesis gas containing carbon monoxide and hydrogen is produced by bringing a methane-containing gas into contact with carbon dioxide, a synthesis gas production apparatus provided with the catalyst structure for synthesis gas production, and a method for producing the catalyst structure for synthesis gas production.

Background

In recent years, as a measure against global warming, a technique (dry reforming) of bringing carbon dioxide, which is a causative substance of global warming, into contact with methane and converting the carbon dioxide into a synthetic gas containing carbon monoxide and hydrogen has been attracting attention.

As a catalyst used in producing such a synthesis gas, for example, patent document 1 discloses a catalyst using an oxygen-deficient perovskite-type composite oxide containing Mn, a predetermined alkaline earth metal, or the like as a carrier and nickel as a supported metal.

However, the reaction of contacting carbon dioxide with methane to convert the carbon dioxide into a synthesis gas containing carbon monoxide and hydrogen needs to be carried out at a high temperature of 800 ℃ or higher. In the catalyst disclosed in patent document 1, since the metal is supported on the surface of the carrier, the catalyst particles are aggregated at a high temperature, so that the catalytic activity is liable to be lowered, and the catalytic activity is not sufficient.

As a method for suppressing the adhesion of catalyst particles to each other and increasing the specific surface area of the catalyst particles, for example, patent document 2 discloses a method in which after the catalyst particles are fixed to the surface of a base material, oxidation treatment and reduction treatment are performed under predetermined conditions.

Disclosure of Invention

Problems to be solved by the invention

However, even in the catalyst structure disclosed in patent document 2 in which the catalyst particles are fixed to the surface of the substrate, the catalyst structure is disposed in a high-temperature reaction site, and the catalytic activity is lowered. Therefore, in order to regenerate the catalytic function, it is necessary to perform the oxidation treatment and the reduction treatment again, and the operation becomes complicated.

An object of the present invention is to provide a catalyst structure for synthesis gas production, which can suppress a decrease in catalytic activity and can efficiently produce a synthesis gas containing carbon monoxide and hydrogen, a synthesis gas production apparatus provided with the catalyst structure for synthesis gas production, and a method for producing the catalyst structure for synthesis gas production.

Technical scheme

As a result of intensive studies to achieve the above object, the present inventors have found the following facts, and have completed the present invention based on the findings, and have obtained a catalyst structure for synthesis gas production, comprising: a porous support composed of a zeolite-type compound; and at least one catalyst substance present in the carrier, the carrier having channels communicating with each other, the catalyst substance being a fine metal particle, and being present in at least the channels of the carrier, whereby a decrease in catalytic activity is suppressed, and a synthesis gas containing carbon monoxide and hydrogen can be efficiently produced.

That is, the gist of the present invention is as follows.

[1] A catalyst structure for synthesis gas production, which is used for producing a synthesis gas containing carbon monoxide and hydrogen, the catalyst structure comprising: a porous support composed of a zeolite-type compound; and at least one catalyst substance present in the carrier, the carrier having channels communicating with each other, the catalyst substance being a metal particulate present in at least the channels of the carrier.

[2] The catalyst structure for synthesis gas production according to item [1], wherein the metal fine particles are fine particles made of at least one metal selected from the group consisting of rhodium (Rh), ruthenium (Ru), iridium (Ir), palladium (Pd), platinum (Pt), iron (Fe), cobalt (Co), and nickel (Ni).

[3] The catalyst structure for synthesis gas production according to [1] or [2], wherein the channel has: any one of one-dimensional pores, two-dimensional pores, and three-dimensional pores defined by the framework structure of the zeolite-type compound; and an expanded diameter portion different from any of the one-dimensional pores, the two-dimensional pores, and the three-dimensional pores, and the catalyst substance is present at least in the expanded diameter portion.

[4] The catalyst structure for synthesis gas production according to item [3], wherein the diameter-enlarged portion connects a plurality of holes constituting any one of the one-dimensional holes, the two-dimensional holes, and the three-dimensional holes.

[5] The catalyst structure for producing synthesis gas according to any one of [3] and [4], wherein an average particle diameter of the fine metal particles is larger than an average inner diameter of the channels and is equal to or smaller than an inner diameter of the enlarged diameter portion.

[6] The catalyst structure for synthesis gas production according to any one of the above [1] to [5], characterized by containing the metal element (M) of the metal fine particles in an amount of 0.5 to 2.5 mass% relative to the catalyst structure for synthesis gas production.

[7] The catalyst structure for synthesis gas production according to any one of the above [1] to [6], wherein the metal fine particles have an average particle diameter of 0.08nm to 30 nm.

[8] The catalyst structure for production of synthesis gas according to the above [7], wherein the metal fine particles have an average particle diameter of 0.4nm to 11.0 nm.

[9] The catalyst structure for synthesis gas production according to any one of the above [1] to [8], wherein a ratio of an average particle diameter of the fine metal particles to an average inner diameter of the channels is 0.05 to 400.

[10] The catalyst structure for synthesis gas production according to item [9], wherein a ratio of an average particle diameter of the fine metal particles to an average inner diameter of the channels is 0.1 to 30.

[11] The catalyst structure for synthesis gas production according to item [10], wherein a ratio of an average particle diameter of the fine metal particles to an average inner diameter of the channels is 1.4 to 3.6.

[12] The catalyst structure for synthesis gas production according to any one of the above [3] to [11], wherein the average inner diameter of the channel is 0.1nm to 1.5nm, and the inner diameter of the expanded diameter portion is 0.5nm to 50 nm.

[13] The catalyst structure for synthesis gas production according to any one of the above [1] to [12], further comprising at least one other catalyst substance held on the outer surface of the carrier.

[14] The catalyst structure for producing synthesis gas according to item [13], wherein a content of the at least one catalyst substance present in the carrier is larger than a content of the at least one other catalyst substance held on the outer surface of the carrier.

[15] The catalyst structure for synthesis gas production according to any one of the above [1] to [14], wherein the zeolite-type compound is a silicate compound.

[16] A synthesis gas production apparatus comprising the catalyst structure for synthesis gas production according to any one of [1] to [15 ].

[17] A method for producing a catalyst structure for synthesis gas production, comprising: a firing step of firing a precursor material (B) obtained by impregnating a precursor material (a) with a metal-containing solution, the precursor material (a) being used for obtaining a support having a porous structure made of a zeolite-type compound; a hydrothermal treatment step of subjecting a precursor material (C) obtained by firing the precursor material (B) to hydrothermal treatment; and a step of subjecting the precursor material (C) after the hydrothermal treatment to a reduction treatment.

[18] The method for producing a catalyst structure for synthesis gas production according to item [17], wherein 50 to 500 mass% of a nonionic surfactant is added to the precursor material (A) before the firing step.

[19] The method of producing a catalyst structure for synthesis gas production according to any one of [17] and [18], wherein the metal-containing solution is impregnated into the precursor material (A) by adding the metal-containing solution to the precursor material (A) a plurality of times before the firing step.

[20] The method for producing a catalyst structure for synthesis gas production according to any one of [17] to [19], wherein, when the metal-containing solution is impregnated into the precursor material (A) before the firing step, the amount of the metal-containing solution added to the precursor material (A) is adjusted so that the ratio (atomic ratio Si/M) of silicon (Si) constituting the precursor material (A) to a metal element (M) contained in the metal-containing solution added to the precursor material (A) is 10 to 1000 in terms of the ratio.

[21] The method of producing a catalyst structure for synthesis gas production according to item [17], wherein the precursor material (C) is mixed with a structure-directing agent in the hydrothermal treatment step.

[22] The method of producing a catalyst structure for synthesis gas production according to item [17], wherein the hydrothermal treatment step is performed in an alkaline environment.

Advantageous effects

According to the present invention, it is possible to provide a catalyst structure for synthesis gas production that can suppress a decrease in catalytic activity and efficiently produce a synthesis gas containing carbon monoxide and hydrogen, and a synthesis gas production apparatus provided with the catalyst structure for synthesis gas production.

Drawings

Fig. 1 is a schematic view showing an internal structure of a catalyst structure for synthesis gas production according to an embodiment of the present invention, in which fig. 1(a) is a perspective view (partially shown in cross section) and fig. 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 synthesis gas production in fig. 1, fig. 2(a) is a view for explaining the sieve function, and fig. 2(b) is a view for explaining the catalytic ability.

Fig. 3 is a flowchart showing an example of a method for producing the catalyst structure for synthesis gas production shown in fig. 1.

Fig. 4 is a schematic view showing a modification of the catalyst structure for synthesis gas production of fig. 1.

Detailed Description

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

[ constitution of catalyst Structure ]

Fig. 1 is a view schematically showing the structure of a catalyst structure for synthesis gas production (hereinafter, simply referred to as "catalyst structure") according to an embodiment of the present invention, fig. 1(a) is a perspective view (partially shown in cross section), and fig. 1(b) is a partially enlarged sectional view. The catalyst structure in fig. 1 is an example thereof, and the shape, size, and the like of each component of the present invention are not limited to fig. 1.

As shown in fig. 1(a), the catalyst structure 1 includes: a porous support 10 made of a zeolite-type compound; and at least one catalyst material 20 present within the support 10.

In the catalyst structure 1, the plurality of catalyst substances 20 and 20 … … are included in the porous structure of the support 10. The catalyst substance 20 may be a substance having a catalytic ability (catalytic activity), and specifically may be a metal fine particle. The metal fine particles will be described in detail later.

The carrier 10 has a porous structure, and preferably has channels 11 communicating with each other by forming a plurality of holes 11a and 11a … …, as shown in fig. 1 (b). Here, the catalyst substance 20 is present in at least the channel 11 of the carrier 10, and is preferably held in at least the channel 11 of the carrier 10.

With this configuration, the movement of the catalyst substance 20 in the carrier 10 is restricted, and the aggregation of the catalyst substances 20 and 20 is effectively prevented. As a result, the decrease in the effective surface area of the catalyst material 20 can be effectively suppressed, and the catalytic activity of the catalyst material 20 can be maintained for a long period of time. That is, according to the catalyst structure 1, it is possible to suppress a decrease in catalytic activity due to aggregation of the catalyst substance 20, and to extend the life of the catalyst structure 1. Further, by extending the life of the catalyst structure 1, the frequency of replacement of the catalyst structure 1 can be reduced, the amount of the used catalyst structure 1 to be discarded can be greatly reduced, and resources can be saved.

In general, when the catalyst structure is used in a fluid, an external force may be applied from the fluid. In this case, if the catalyst substance is attached only to the outer surface of the carrier 10, there is a problem that the catalyst substance is easily detached from the outer surface of the carrier 10 under the influence of an external force from the fluid. In contrast, in the catalyst structure 1, the catalyst substance 20 is held in at least the channels 11 of the carrier 10, and therefore, even if an external force is applied from the fluid, the catalyst substance 20 is not easily detached from the carrier 10. Namely, it is considered that: when the catalyst structure 1 is in a fluid, the fluid flows into the channels 11 from the pores 11a of the carrier 10, and therefore the velocity of the fluid flowing through the channels 11 is lower than the velocity of the fluid flowing through the outer surfaces of the carrier 10 due to flow path resistance (frictional force). Due to the influence of such flow path resistance, the catalyst substance 20 held in the channel 11 receives a lower pressure from the fluid than the catalyst substance outside the carrier 10. Therefore, the catalyst substance 20 present in the carrier 11 can be effectively inhibited from being detached, and the catalytic activity of the catalyst substance 20 can be stably maintained for a long period of time. It should be noted that: the more the channels 11 of the carrier 10 have a plurality of bends and branches, the more complicated and three-dimensional structure is inside the carrier 10, and the larger the flow path resistance as described above is.

Furthermore, the channel 11 preferably has: any one of one-dimensional pores, two-dimensional pores, and three-dimensional pores defined by the framework structure of the zeolite-type compound; and an enlarged diameter portion 12, different from any of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole, in which case the catalyst substance 20 is preferably present at least in the enlarged diameter portion 12, and more preferably included at least in the enlarged diameter portion 12. This further restricts the movement of the catalyst substance 20 within the carrier 10, and thus, the catalyst substance 20 can be more effectively prevented from being detached and the catalyst substances 20 and 20 can be more effectively prevented from being aggregated with each other. Inclusion means a state in which the catalyst substance 20 is contained in the carrier 10. In this case, the catalyst substance 20 and the carrier 10 do not necessarily need to be in direct contact with each other, and the catalyst substance 20 may be indirectly held by the carrier 10 in a state where another substance (for example, a surfactant or the like) is interposed between the catalyst substance 20 and the carrier 10. The one-dimensional hole as used herein means a tunnel-type or cage-type hole in which one-dimensional channels are formed, or a plurality of tunnel-type or cage-type holes (a plurality of one-dimensional channels) in which a plurality of one-dimensional channels are formed. In addition, the two-dimensional hole refers to a two-dimensional hole formed by two-dimensionally connecting a plurality of one-dimensional holes, and the three-dimensional hole refers to a three-dimensional hole formed by three-dimensionally connecting a plurality of one-dimensional holes.

Fig. 1(b) shows a case where the catalyst substance 20 is enclosed in the enlarged diameter portion 12, but the present invention is not limited to this configuration, and the catalyst substance 20 may be present in the passage 11 in a state where a part thereof protrudes to the outside of the enlarged diameter portion 12. The catalyst substance 20 may be partially embedded in a portion of the channel 11 other than the enlarged diameter portion 12 (for example, an inner wall portion of the channel 11), or may be held by adhesion or the like in a portion of the channel 11 other than the enlarged diameter portion 12 (for example, an inner wall portion of the channel 11).

Further, the enlarged diameter portion 12 preferably communicates a plurality of holes 11a, 11a constituting any one of the one-dimensional hole, the two-dimensional hole, and the three-dimensional hole. Thus, since another channel different from the one-dimensional hole, the two-dimensional hole, or the three-dimensional hole is provided in the carrier 10, the function of the catalyst material 20 can be further exerted.

Further, it is preferable that the channel 11 is three-dimensionally formed inside the carrier 10 so as to include a branching portion or a merging portion, and the diameter-expanding portion 12 is provided in the branching portion or the merging portion of the channel 11.

The average inner diameter D of the channel 11 formed in the carrier 10_FThe average value of the minor axis and the major axis of the pores 11a constituting any one of the one-dimensional pores, the two-dimensional pores, and the three-dimensional pores is, for example, 0.1nm to 1.5nm, preferably 0.5nm to 0.8 nm. Further, the inner diameter D of the enlarged diameter portion 12_EFor example, 0.5nm to 50nm, preferably 1.1nm to 40nm, and more preferably 1.1nm to 3.3 nm. Inner diameter D of enlarged diameter portion 12_EFor example, the pore diameter of the precursor (A) described later and the average particle diameter D of the catalyst substance 20 to be included_C. The inner diameter DE of the enlarged diameter portion 12 is a size capable of enclosing the catalyst substance 20.

The support 10 is composed of a zeolite-type compound. Examples of the zeolite-type compound include: silicate compounds such as zeolite (aluminosilicate), cation-exchanged zeolite, and silicalite (silicalite); zeolite-like compounds such as aluminoborate, aluminoarsenate, germanate and the like; phosphate-based zeolite-like substances such as molybdenum phosphate; and the like. Among them, the zeolite-type compound is preferably a silicate compound.

The framework structure of the zeolite-type compound is selected from 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 pore diameters corresponding to respective framework structures are formed, and for example, the maximum pore diameter of MFI type is 0.636nm

Average pore diameter of 0.560nm

The catalyst substance 20 will be described in detail below.

The catalyst substance 20 is a metal particulate. There are: the case where the fine metal particles are held in the channel 11 in the state of primary particles; and the case where the fine metal particles are held in the passage 11 in a state of secondary particles formed by the aggregation of the primary particles. In either case, the average particle diameter D of the metal fine particles_CAre each preferably larger than the average inner diameter D of the channel 11_FAnd is not more than the inner diameter D of the enlarged diameter part 12_E(D_F<D_C≤D_E). Such a catalyst substance 20 is preferably included in the diameter-enlarged portion 12 in the channel 11, and movement of the catalyst substance 20 in the carrier 10 is restricted. Thus, even when the catalyst substance 20 receives an external force from a fluid, the movement of the catalyst substance 20 in the carrier 10 is suppressed, and the catalyst substances 20 and 20 … … included in the respective enlarged diameter portions 12 and 12 … … of the channels 11 dispersedly arranged in the carrier 10 can be effectively prevented from contacting each other.

Further, the average particle diameter D of the metal fine particles_CIn both the primary particles and the secondary particles, the particle size is preferably 0.08 to 30nm, more preferably 0.08 to less than 25nm, still more preferably 0.4 to 11.0nm, and particularly preferably 1.2 to 2.6 nm. Further, the average particle diameter D of the metal fine particles_CRelative to the mean internal diameter D of the channel 11_FRatio (D)_C/D_F) Preferably 0.05 to 300, more preferably 0.1 to 30, and further preferablyPreferably 1.1 to 30, and particularly preferably 1.4 to 3.6.

In addition, when the catalyst substance 20 is a metal fine particle, it is preferable that the metal element (M) of the metal fine particle is contained in an amount of 0.5 to 2.5 mass% with respect to the catalyst structure 1, and it is more preferable that the metal element (M) of the metal fine particle is contained in an amount of 0.5 to 1.5 mass% with respect to the catalyst structure 1. For example, in the case where the metal element (M) is Ni, the content (mass%) of the Ni element is represented by { (mass of Ni element)/(mass of all elements of the catalyst structure 1) } × 100.

The metal fine particles may be composed of a metal that is not oxidized, and may be composed of a single metal or a mixture of two or more metals, for example. In the present specification, "metal" constituting (as a material of) the metal fine particles means a single metal containing one metal element (M) and a metal alloy containing two or more metal elements (M), and is a generic term for metals containing one or more metal elements.

Examples of such metals include: rhodium (Rh), ruthenium (Ru), iridium (Ir), palladium (Pd), platinum (Pt), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), chromium (Cr), cerium (Ce), copper (Cu), magnesium (Mg), aluminum (Al), nickel (Ni), and the like, and preferably any one or more of these as a main component. In particular, the metal fine particles are preferably fine particles composed of at least one metal selected from the group consisting of rhodium (Rh), ruthenium (Ru), iridium (Ir), palladium (Pd), platinum (Pt), iron (Fe), cobalt (Co), and nickel (Ni) from the viewpoint of catalytic activity, and more preferably at least one metal selected from the group consisting of rhodium (Rh), ruthenium (Ru), iridium (Ir), and nickel (Ni) from the viewpoint of both price and performance, and particularly preferably nickel (Ni).

The ratio (atomic ratio Si/M) of silicon (Si) constituting the carrier 10 to the metal element (M) constituting the metal fine particles is preferably 10 to 1000, and more preferably 50 to 200. If the above ratio is more than 1000, the activity is low, and the effect as a catalyst substance may not be sufficiently obtained. On the other hand, if the ratio is less than 10, the ratio of the metal fine particles becomes too large, and the strength of the carrier 10 tends to decrease. The metal fine particles 20 referred to herein are fine particles present or carried in the carrier 10, and do not include metal fine particles adhering to the outer surface of the carrier 10.

[ function of catalyst Structure ]

As described above, the catalyst structure 1 includes: a support 10 having a porous structure; and at least one catalyst material 20 present within the support. The catalyst structure 1 exhibits a catalytic ability corresponding to the function of the catalyst substance 20 when the catalyst substance 20 present in the carrier 10 comes into contact with a fluid. Specifically, the fluid that contacts the outer surface 10a of the catalyst structure 1 flows into the inside of the carrier 10 from the holes 11a formed in the outer surface 10a, is guided into the channels 11, moves through the channels 11, and flows out of the catalyst structure 1 through the other holes 11 a. In the path of the fluid moving through the inside of the channel 11, it comes into contact with the catalyst substance 20 held in the channel 11, whereby a catalytic reaction corresponding to the catalyst substance 20 occurs. In addition, the catalyst structure 1 has a molecular sieve ability because the support has a porous structure.

First, the molecular sieve capacity of the catalyst structure 1 will be described by taking a case where the fluid is a methane-containing gas and carbon dioxide as an example, with reference to fig. 2 (a). The methane-containing gas is a mixed gas containing methane and a gas other than methane. Further, the methane-containing gas and the carbon dioxide may be contacted with each other in order with respect to the catalyst structure 1, or may be contacted with each other simultaneously.

As shown in fig. 2(a), a compound (for example, methane or carbon dioxide) composed of molecules having a size equal to or smaller than the pore diameter of the pores 11a, in other words, equal to or smaller than the inner diameter of the channels 11 can flow into the carrier 10. On the other hand, the gas component 15 composed of molecules having a size larger than the pore diameter of the pores 11a cannot flow into the carrier 10. In this way, when the fluid contains a plurality of compounds, the reaction of the compounds that cannot flow into the carrier 10 is limited, and the compounds that can flow into the carrier 10 can be reacted. In the present embodiment, the reaction of methane with carbon dioxide is performed.

Among the compounds generated in the carrier 10 by the reaction, only a compound composed of molecules having a size not larger than the pore diameter of the pores 11a can be obtained as a reaction product by flowing out of the carrier 10 through the pores 11 a. On the other hand, if the compound that cannot flow out of the carrier 10 through the pores 11a is converted into a compound composed of molecules having a size that can flow out of the carrier 10, the compound can flow out of the carrier 10. By using the catalyst structure 1 in this manner, a specific reaction product can be selectively obtained. In the present embodiment, specifically, methane and carbon dioxide are reacted to obtain a synthesis gas containing carbon monoxide and hydrogen as a reaction product.

In the catalyst structure 1, as shown in fig. 2(b), the catalyst substance 20 is enclosed in the enlarged diameter portion 12 of the channel 11. Average particle diameter D of catalyst substance 20 (metal fine particles)_CGreater than the average internal diameter D of the channel 11_FAnd is smaller than the inner diameter D of the diameter-expanded portion 12_EIn the case of (D)_F<D_C<D_E) Small channels 13 are formed between the catalyst material 20 and the diameter-enlarged portion 12. Therefore, as shown by the arrows in fig. 2(b), the fluid flowing into the small channel 13 comes into contact with the catalyst substance 20. Since each catalyst substance 20 is contained in the enlarged diameter portion 12, the movement of the catalyst substance in the carrier 10 is restricted. This prevents the catalyst substances 20 in the carrier 10 from aggregating with each other. As a result, a large contact area between the catalyst substance 20 and the fluid can be stably maintained.

In the present embodiment, by using the catalyst structure 1, a synthesis gas containing carbon monoxide and hydrogen can be produced from a methane-containing gas and carbon dioxide as raw materials. This catalytic reaction proceeds at a high temperature of 800 ℃ or higher, for example, but the catalyst substance 20 is not easily affected by heating because it is present in the carrier 10. As a result, the decrease in catalytic activity is suppressed, and the life of the catalyst structure 1 can be extended.

[ method for producing catalyst Structure ]

Fig. 3 is a flowchart showing a method for manufacturing the catalyst structure 1 of fig. 1. An example of a method for producing a catalyst structure will be described below, taking as an example a case where the catalyst substance 20 present in the carrier is a fine metal particle.

(step S1: preparation Process)

As shown in fig. 3, first, a precursor material (a) for obtaining a support having a porous structure made of a zeolite-type compound is prepared. The precursor material (a) is preferably a regular mesoporous substance, and may be appropriately selected depending on the kind (composition) of the zeolite-type compound constituting the carrier of the catalyst structure.

Here, when the zeolite-type compound constituting the carrier of the catalyst structure is a silicate compound, the regular mesoporous material is preferably a compound composed of an Si — O framework in which pores having pore diameters of 1nm to 50nm are uniform in one-dimensional, two-dimensional, or three-dimensional size and regularity develops. Such a regular mesoporous material is obtained as various compositions according to synthesis conditions, and specific examples of the compositions include: SBA-1, SBA-15, SBA-16, KIT-6, FSM-16, MCM-41 and the like, wherein MCM-41 is preferred. The pore diameter of SBA-1 is 10nm to 30nm, the pore diameter of SBA-15 is 6nm to 10nm, the pore diameter of SBA-16 is 6nm, the pore diameter of KIT-6 is 9nm, the pore diameter of FSM-16 is 3nm to 5nm, and the pore diameter of MCM-41 is 1nm to 10 nm. Examples of such a regular mesoporous material include: mesoporous silica, mesoporous aluminosilicates, mesoporous metallosilicates, and the like.

The precursor (a) may be any of commercially available products and synthetic products. In the case of synthesizing the precursor material (a), a known method for synthesizing a mesoporous substance having regularity may be employed. For example, a mixed solution containing a raw material containing a constituent element of the precursor material (a) and a template agent for specifying the structure of the precursor material (a) is prepared, and hydrothermal treatment (hydrothermal synthesis) is performed by adjusting the pH as necessary. Then, the precipitate (product) obtained by the hydrothermal treatment is recovered (e.g., filtered), washed and dried as necessary, and further fired, whereby the precursor material (a) as a powdery regular mesoporous substance can be obtained. Here, as the solvent of the mixed solution, for example, water, an organic solvent such as alcohol, or a mixed solvent thereof can be used. The raw material is selected depending on the kind of the carrier, and examples thereof include: silica agents (silica agents) such as Tetraethoxysilane (TEOS), fumed silica, and silica sand. Further, as the template agent, various surfactants, block copolymers and the like can be used, and it is preferable to select the template agent according to the kind of the composition of the ordered mesoporous substance, and for example, in the case of preparing MCM-41, a surfactant such as cetyltrimethylammonium bromide is preferable. The hydrothermal treatment may be carried out, for example, in a closed vessel under the treatment conditions of 80 to 800 ℃ for 5 to 240 hours and 0 to 2000 kPa. The firing treatment may be performed, for example, in air at 350 to 850 ℃ for 2 to 30 hours.

(step S2: impregnation step)

Next, the prepared precursor material (a) is immersed in a metal-containing solution to obtain a precursor material (B).

The metal-containing solution may be a solution containing a metal component (for example, metal ion) corresponding to the metal element (M) constituting the metal fine particles, and for example, may be prepared by dissolving a metal salt containing the metal element (M) in a solvent. Examples of such metal salts include: chlorides, hydroxides, oxides, sulfates, nitrates, etc., among which nitrates are preferred. Examples of the solvent include water, organic solvents such as alcohols, and mixed solvents thereof.

The method for immersing the metal-containing solution in the precursor material (a) is not particularly limited, and for example, it is preferable to add the metal-containing solution in small amounts at a time in a plurality of times while stirring the powdery precursor material (a) before the firing step described later. In addition, from the viewpoint that the metal-containing solution more easily penetrates into the inside of the pores of the precursor material (a), it is preferable to add a surfactant as an additive in advance before adding the metal-containing solution to the precursor material (a). Consider that: such an additive has an effect of covering the outer surface of the precursor material (a), and suppresses the metal-containing solution added later from adhering to the outer surface of the precursor material (a), so that the metal-containing solution more easily penetrates into the pores of the precursor material (a).

Examples of such additives include: and nonionic surfactants such as polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether and polyoxyethylene alkylphenyl ethers. Consider that: these surfactants have large molecular sizes and cannot penetrate into the pores of the precursor material (a), and therefore do not adhere to the inside of the pores and do not inhibit the metal-containing solution from penetrating into the pores. As a method of adding the nonionic surfactant, for example, it is preferable to add 50 to 500 mass% of the nonionic surfactant to the precursor material (a) before the firing step described later. If the amount of the nonionic surfactant added to the precursor material (a) is less than 50 mass%, the above-described inhibiting effect is hardly exhibited, and if the amount of the nonionic surfactant added to the precursor material (a) is more than 500 mass%, the viscosity is excessively increased, which is not preferable. Thus, the amount of the nonionic surfactant added 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 preferably adjusted as appropriate in consideration of the amount of the metal element (M) contained in the metal-containing solution to be impregnated into the precursor material (a) (that is, the amount of the metal element (M) to be present in the precursor material (B)). For example, the amount of the metal-containing solution added to the precursor material (a) before the firing step described later is preferably adjusted so that the ratio (atomic ratio Si/M) of silicon (Si) constituting the precursor material (a) to the metal element (M) contained in the metal-containing solution added to the precursor material (a) is 10 to 1000, more preferably 50 to 200. 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 metal element (M) of the metal fine particles can be contained in an amount of 0.5 to 2.5 mass% with respect to the catalyst structure 1 by setting the amount of the metal-containing solution added to the precursor material (a) to 50 to 200 in terms of an atomic ratio Si/M. In the state of the precursor material (B), if the metal concentration of the metal-containing solution, the presence or absence of the additive, other conditions such as temperature and pressure are the same, the amount of the metal element (M) present in the pores thereof is substantially proportional to the amount of the metal-containing solution added to the precursor material (a). Further, the amount of the metal element (M) present in the precursor material (B) is in proportional relation to the amount of the metal element constituting the metal fine particles present in the carrier of the catalyst structure. Therefore, by controlling the amount of the metal-containing solution added to the precursor material (a) to be in the above range, the metal-containing solution can be sufficiently impregnated into the pores of the precursor material (a), and the amount of the metal fine particles to be present in the support of the catalyst structure can be adjusted.

After the metal-containing solution is impregnated in the precursor material (a), a cleaning treatment may be performed as needed. As the cleaning solution, water, an organic solvent such as alcohol, a mixed solvent thereof, or the like can be used. Further, it is preferable that the metal-containing solution is immersed in the precursor material (a) and, after a cleaning treatment is performed as necessary, a drying treatment is further performed. Examples of the drying treatment include natural drying at about evening primrose, and high-temperature drying at 150 ℃. When the firing treatment described later is performed in a state where a large amount of moisture contained in the metal-containing solution and moisture in the cleaning solution remain in the precursor (a), the skeleton structure of the ordered mesoporous material as the precursor (a) may be broken, and therefore, it is preferable to sufficiently dry the precursor (a).

(step S3: firing Process)

Next, a precursor material (B) obtained by impregnating a precursor material (a) for obtaining a support having a porous structure made of a zeolite-type compound with a metal-containing solution is fired to obtain a precursor material (C).

The firing treatment is preferably carried out in air at 350 to 850 ℃ for 2 to 30 hours, for example. By the firing treatment, the metal component impregnated into the pores of the ordered mesoporous material is subjected to crystal growth to form fine metal particles 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 subjected to hydrothermal treatment to obtain a catalyst structure.

The structure-directing agent is a template agent for defining the framework structure of the support of the catalyst structure, and for example, a surfactant can be used. The structure-directing agent is preferably selected according to the skeletal structure of the support of the catalyst structure, and is preferably a surfactant such as tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), tetrapropylammonium bromide (TPABr), or the like.

The mixing of the precursor material (C) and the structure directing agent may be performed during the hydrothermal treatment step or may be performed before the hydrothermal treatment step. The method for preparing the mixed solution is not particularly limited, and the precursor material (C), the structure-directing agent, and the solvent may be mixed at the same time, or the precursor material (C) and the structure-directing agent may be dispersed in the solvent in the form of separate solutions, and then the respective dispersed solutions may be mixed. Examples of the solvent include water, organic solvents such as alcohols, and mixed solvents thereof. The mixed solution is preferably adjusted in pH by using an acid or an alkali in advance before the hydrothermal treatment.

The hydrothermal treatment can be carried out by a known method, and is preferably carried out in a closed vessel under treatment conditions of 80 to 800 ℃ for 5 to 240 hours and 0 to 2000kPa, for example. Further, the hydrothermal treatment is preferably performed in an alkaline environment.

Although the reaction mechanism is not necessarily clear here, when the precursor material (C) is used as a raw material and subjected to hydrothermal treatment, the skeleton structure of the fine pore substance in the regularity as the precursor material (C) is gradually broken, but the position of the metal fine particles in the pores of the precursor material (C) is substantially maintained, and a new skeleton structure (porous structure) serving as a support of the catalyst structure is formed by the action of the structure-directing agent. The catalyst structure thus obtained comprises: the carrier has a porous structure, and metal fine particles present in the carrier, and the carrier further has channels through which a plurality of pores communicate with each other due to the porous structure of the carrier, and at least a part of the metal fine particles are present in the channels 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 subjected to the hydrothermal treatment.

It is preferable that the precipitate (catalyst structure) obtained after the hydrothermal treatment is recovered (for example, filtered), and then subjected to a washing treatment, a drying treatment, and a firing treatment as necessary. As the cleaning solution, water, an organic solvent such as alcohol, a mixed solvent thereof, or the like can be used. Examples of the drying treatment include natural drying at about evening and high-temperature drying at 150 ℃. When the calcination treatment is performed in a state where a large amount of water remains in the precipitate, the skeleton structure of the carrier serving as the catalyst structure may be broken, and therefore, it is preferable to sufficiently dry the catalyst structure. The firing treatment may be performed, for example, in air at 350 to 850 ℃ for 2 to 30 hours. By such a firing treatment, the structure directing agent attached to the catalyst structure is burned off. The catalyst structure may be used as it is without subjecting the recovered precipitate to firing treatment depending on the purpose of use. For example, when the environment in which the catalyst structure is used is a high-temperature environment such as an oxidizing environment, the structure directing agent is burned off by exposure to the use environment for a certain period of time. In this case, since the same catalyst structure as that obtained by the firing treatment can be obtained, the firing treatment need not be performed.

The above-described production method is an example of a case where the metal element (M) contained in the metal-containing solution to be impregnated into the precursor material (a) is a metal species (for example, noble metal) that is not easily oxidized.

When the metal element (M) contained in the metal-containing solution to be impregnated into the precursor (a) is a metal species (for example, Fe, Co, Ni, or the like) that is easily oxidized, it is preferable to perform a reduction treatment on the precursor (C) after the hydrothermal treatment step. When the metal element (M) contained in the metal-containing solution is a metal species that is easily oxidized, the metal component is oxidized by the heat treatment in the steps (steps S3 to S4) after the impregnation treatment (step S2). Therefore, the metal oxide fine particles are present in the carrier formed by the hydrothermal treatment step (step S4). Therefore, in order to obtain a catalyst structure in which fine metal particles are present in the carrier, it is preferable that the collected precipitate is subjected to a firing treatment after the hydrothermal treatment, and further subjected to a reduction treatment in a reducing atmosphere such as hydrogen gas. By performing the reduction treatment, the metal oxide fine particles present in the carrier are reduced to form metal fine particles corresponding to the metal element (M) constituting the metal oxide fine particles. As a result, a catalyst structure in which fine metal particles are present in the carrier can be obtained. Such a reduction treatment may be performed as needed, and for example, when the use environment of the catalyst structure is a reduction environment, the metal oxide fine particles are reduced by exposure to the use environment for a certain period of time. In this case, since the same catalyst structure as that obtained by the reduction treatment can be obtained, the reduction treatment need not be performed.

[ modified example of catalyst Structure 1]

Fig. 4 is a schematic diagram showing a modification of the catalyst structure 1 of fig. 1.

The catalyst structure 1 in fig. 1 includes the carrier 10 and the catalyst substance 20 present in the carrier 10, but is not limited to this configuration, and for example, as shown in fig. 4, the catalyst structure 2 may further include at least one other catalyst substance 30 held on the outer surface 10a of the carrier 10.

The catalyst material 30 is a material that exerts one or more catalytic capabilities. The catalytic ability of the other catalyst material 30 may be the same as or different from that of the catalyst material 20. When both the catalyst substances 20 and 30 have the same catalytic ability, the material of the other catalyst substance 30 may be the same as or different from the material of the catalyst substance 20. According to this configuration, the content of the catalyst substance held by the catalyst structure 2 can be increased, and the catalytic activity of the catalyst substance can be further promoted.

In this case, it is preferable that the content of the catalyst substance 20 present in the carrier 10 is larger than the content of the other catalyst substance 30 held on the outer surface 10a of the carrier 10. As a result, the catalytic ability of the catalyst substance 20 held in the carrier 10 becomes dominant, and the catalytic ability of the catalyst substance is stably exhibited.

The catalyst structure according to the embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications and changes can be made based on the technical idea of the present invention.

For example, a synthesis gas production apparatus including the catalyst structure may be provided. Examples of the production apparatus include CO by dry reforming₂Reforming equipment, and the like. The catalyst structure can be used for a catalytic reaction using such a synthesis gas production apparatus.

That is, the synthesis gas containing carbon monoxide and hydrogen can be synthesized by supplying carbon dioxide and methane to the catalyst structure, and for example, the same effects as described above can be obtained by using the catalyst structure in a synthesis gas production apparatus and performing a synthesis process on carbon dioxide and methane in the synthesis gas production apparatus.