Composite, composite production method, and catalyst structure

Abstract

A composite comprising: a skeleton having a porous structure and containing a crystalline SiO2 compound; and fine particles within the skeleton that comprise metal oxide fine particles or metal fine particles.

Description

Composite, method for producing the composite, and catalyst structure

[0001] The present disclosure relates to composites and methods for making composites, and catalyst structures.

[0002] Zeolite-based technologies are being investigated in a variety of fields.

[0003] As crude oil becomes heavier, desulfurized heavy oil and desulfurized heavy light oil obtained by hydrodesulfurizing heavy oil in a hydrodesulfurization unit such as a direct desulfurization unit or an intermediate desulfurization unit are further cracked to increase the production of desulfurized naphtha, desulfurized kerosene, desulfurized light oil, etc. In this hydrocracking process, a hydrocracking catalyst containing a specific ratio of zeolite and a porous inorganic oxide has been proposed.

[0004] Furthermore, Patent Document 1 describes a honeycomb structure for purifying exhaust gases such as automobile exhaust gases. The honeycomb structure of Patent Document 1 contains zeolite and an inorganic binder, and is configured by bonding a plurality of columnar honeycomb units, each of which includes a plurality of cells extending from a first end face to a second end face along the longitudinal direction and partitioned by cell walls, via an adhesive layer.

[0005] The catalysts described above are utilized in the form of molded catalysts obtained by kneading zeolite or the like with a binder such as alumina and molding the mixture into a predetermined shape, or structured catalysts obtained by adhering zeolite or the like to the surface of a support such as an inert metal or metal oxide.

[0006] However, such catalysts are not suitable for high temperature reactions, especially H ２ In reactions that add or generate O, large density changes occur. When a catalyst experiences density changes, the volume of the catalyst changes, which can lead to problems such as cracks in molded catalysts and peeling of zeolite from the support in structured catalysts. As such, it is difficult to maintain the structure of molded catalysts and structured catalysts, making it difficult to carry out a predetermined reaction stably and safely over a long period of time.

[0007] JP 2011-56328 A

[0008] An object of the present disclosure is to provide a composite and a method for producing the same, which can suppress density changes at high temperatures and enable a predetermined reaction to be carried out stably and safely over a long period of time, as well as a catalyst structure using the composite.

[0009] [1] Crystalline SiO ２ [2] A composite comprising a porous skeleton containing a compound, and particles containing metal oxide particles or metal particles present within the skeleton. ２ The composite according to the above [1], wherein the compound is at least one compound selected from the group consisting of cristobalite, tridymite, quartz, stishovite, and coesite. [3] The crystalline SiO ２ The composite according to [1] or [2] above, wherein the abundance ratio of the compound is 40% or more. [4] The composite according to any one of [1] to [3] above, wherein the average particle size of the fine particles is 0.08 nm or more and 50.00 nm or less. [5] The composite according to any one of [1] to [4] above, wherein the average particle size of the metal oxide fine particles is 0.10 nm or more and 50.00 nm or less. [6] The composite according to any one of [1] to [4] above, wherein the average particle size of the metal fine particles is 0.08 nm or more and 30.00 nm or less. [7] Fischer-Tropsch synthesis, steam reforming, dry reforming, partial oxidation reforming, methanol reforming, methanol synthesis, hydrocracking, catalytic cracking, hydrodesulfurization, ammonia cracking, ammonia synthesis, CO shift reaction, reverse shift reaction, exhaust gas purification, fluid catalytic cracking, N ２ O decomposition, CO treatment, NO decomposition, volatile organic substance synthesis, volatile organic substance removal, NO ｘ The composite according to any one of the above [1] to [6], which is used for reduction, dehydrogenation of alkanes, olefin synthesis, or aromatic synthesis. [8] A catalyst structure obtained by using the composite according to any one of the above [1] to [7]. [9] A catalyst structure obtained by using the composite according to any one of the above [1] to [7], in which the metal oxide fine particles or the fine particles containing the metal fine particles are SiO ２ The precursor material having a structure encapsulated in a hydroxyl-based framework is ２

[10] A method for producing a composite, comprising heat-treating the composite in a high-temperature atmosphere in the presence of O. ２The method for producing a composite according to the above [9], wherein the framework is zeolite.

[0010] According to the present disclosure, it is possible to provide a composite and a method for producing the composite, which are capable of suppressing density changes at high temperatures and carrying out a predetermined reaction stably and safely over a long period of time, as well as a catalyst structure using the composite.

[0011] FIG. 1 is an image of the pellet obtained using the composite of Comparative Example 1 after the catalytic activity test.

[0012] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0013] The present inventors have focused on the fact that the cause of large density changes caused by high-temperature reactions is a phase change in the crystal structure. The present inventors have investigated the components contained in the framework that constitutes the composite, and have found that crystalline SiO ２ The inventors have discovered that by forming a compound, it is possible to control the change in the crystal structure of the framework, which is accompanied by a change in density at high temperatures, and to carry out a predetermined reaction stably and safely over a long period of time, and have completed the present disclosure based on this finding.

[0014] [Configuration of the composite] The composite of the embodiment is a crystalline SiO ２ The composite material comprises a porous skeleton containing a compound, and particles containing metal oxide particles or metal particles present within the skeleton.

[0015] The framework constituting the composite is made of one or more types of crystalline SiO ２ The crystalline SiO2 contained in the framework has a porous structure. ２ The compound is not a zeolite, i.e., it is not crystalline SiO ２ The compounds do not include zeolites.

[0016] The composite contains one or more fine particles. The fine particles include metal oxide fine particles or metal fine particles and are present within the framework. The fine particles may be primary particles or secondary particles formed by aggregation of primary particles.

[0017] The microparticles exert one or more functions, either alone or in cooperation with the framework. Examples of such functions include catalytic function, luminescent function, fluorescent function, light absorption function, and identification function. The microparticles are preferably, for example, catalytic substances having catalytic function. When the microparticles are catalytic substances, the framework is a carrier that supports the catalytic substances.

[0018] Specific applications relating to the catalytic function of the composite include Fischer-Tropsch synthesis, steam reforming, dry reforming, partial oxidation reforming, methanol reforming, methanol synthesis, hydrocracking, catalytic cracking, hydrodesulfurization, ammonia decomposition, ammonia synthesis, CO shift reaction, reverse shift reaction, exhaust gas purification, fluid catalytic cracking, N ２ O decomposition, CO treatment, NO decomposition, volatile organic substance synthesis, volatile organic substance removal, NO ｘ These include reduction, dehydrogenation of alkanes, olefin synthesis, and aromatic synthesis.

[0019] The skeleton has a porous structure and thus has a large number of pores, including through-holes and bottomed pores. The microparticles present inside the skeleton communicate with the outside of the skeleton through one or more pores.

[0020] Crystalline SiO that constitutes the framework ２ The compound has a porous structure. The plurality of particles are made of crystalline SiO ２ Inherent in the compound. Crystalline SiO ２ The compounds are zeolites such as silicalite and SiO, which are different from amorphous silica. ２ Therefore, the complex can be used in high temperature reactions, especially H ２ Even if exposed to a reaction that adds or generates O, the resulting crystalline SiO ２ The density change of the compound is reduced or crystalline SiO ２ Since no change in density of the compound occurs, changes in density of the framework due to changes in the crystal structure of the framework can be suppressed.

[0021] Therefore, when the composite is applied to a molded catalyst, cracks in the molded catalyst can be suppressed, and when the composite is applied to a structured catalyst, peeling from the support can be suppressed, and the structure can be stably maintained for a long period of time. As a result, even when the composite is used industrially, clogging of the reaction tube in the reaction system can be suppressed while maintaining its strength for a long period of time, and the composite can therefore perform a predetermined reaction stably and safely for a long period of time.

[0022] From the viewpoint of reducing density changes under high temperature environments, crystalline SiO ２ The compound is preferably at least one compound selected from the group consisting of cristobalite, tridymite, quartz, stishovite, and coesite, more preferably at least one compound selected from the group consisting of cristobalite, tridymite, and quartz, and even more preferably cristobalite. Such compounds are structurally stable even under high temperature environments.

[0023] In addition, crystalline SiO ２ The abundance ratio of the compound is preferably 40% or more, more preferably 65% ​​or more, and even more preferably 95% or more. ２ As the abundance ratio of the compound increases, the structure becomes more stable even under high temperature and other conditions.

[0024] The framework contains crystalline SiO ２ In addition to the compounds, components such as zeolite-type compounds may also be included.

[0025] The zeolite-type compound has a porous structure and molecular sieving ability. The plurality of fine particles may be present within the zeolite-type compound. The zeolite-type compound has a plurality of pores formed therein, which provide interconnected passages. The fine particles may be present in the passages of the zeolite-type compound, and are preferably held at least in the passages of the zeolite-type compound.

[0026] This structure restricts the movement of the particles within the zeolite-type compound, effectively preventing the particles from agglomerating together. As a result, the reduction in the effective surface area of ​​the particles can be effectively suppressed, and the function of the particles can be maintained for a long period of time. In other words, the deterioration of the function due to the aggregation of the particles can be suppressed, and the life of the composite can be extended. Furthermore, the extended life of the composite can reduce the frequency of replacement of the composite, significantly reducing the amount of used composite discarded, thereby conserving resources.

[0027] Examples of zeolite-type compounds include silicate compounds such as zeolite (aluminosilicate), cation-exchanged zeolite, and silicalite, zeolite-related compounds such as aluminoborates, aluminoarsenates, and germanates, and phosphate-based zeolite-like substances such as molybdenum phosphate. Of these, silicate compounds are preferred as zeolite-type compounds.

[0028] 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., with MFI type being preferred, and ZSM-5 being more preferred. Zeolite-type compounds have multiple pores formed therein, each with a pore size corresponding to the respective framework structure; for example, the maximum pore size of the MFI type is 0.636 nm (6.36 Å) and the average pore size is 0.560 nm (5.60 Å).

[0029] Crystalline SiO ２ The abundance ratio of the compounds can be measured by XRD (X-ray diffraction) under the following conditions. The following is an example of calculating the abundance ratio of cristobalite. Measurement conditions: Measurement is performed by a reflection method using a D8 ADVANCE (manufactured by Bruker) device, an X-ray light source (target: Cu), and a LYNXEYE / SSD160 detector (one-dimensional semiconductor). Cristobalite peak: peak at about 22° MFI zeolite peak: peak at about 8° Crystalline SiO ２ Abundance ratio of compound = (crystalline SiO ２Peak height of compound) / (crystalline SiO ２ (Peak height of compound + peak height of MFI zeolite) × 100

[0030] Crystalline SiO ２ If the peak of the compound overlaps with the peak of another substance, it is crystalline SiO ２ The peak angle of the compound is not the above peak angle, but the peak angle of crystalline SiO ２ It is sufficient to select a peak angle specific to the compound. The peak to be selected is preferably a high peak that can be separated from peaks derived from other crystalline substances. Therefore, the above peaks are only examples, and the abundance ratio can be determined from the ratio of the peak heights calculated by a known method using the peaks derived from each crystalline substance.

[0031] Usually, when a composite is used in a fluid (for example, heavy oil or reformed gas such as NOx), it may be subjected to an external force from the fluid. In this case, if the fine particles are held in an adhered state only on the outer surface of the skeleton, there is a problem that the fine particles are easily detached from the outer surface of the skeleton due to the influence of the external force from the fluid. In contrast, in the composite of the embodiment, the fine particles are held in an adhered state only on the outer surface of the skeleton, that is, the fine particles are easily detached from the outer surface of the skeleton due to the influence of the external force from the fluid. ２ The fine particles are present in the compound and / or at least in the passages of the zeolite-type compound. Therefore, even if the composite is subjected to an external force from a fluid, the fine particles are unlikely to be detached from the framework. Furthermore, when the composite is in a fluid, the fluid acts to dissolve the crystalline SiO ２ In the case of compounds, the particles flow into the interior through the pores, while in the case of zeolite-type compounds, the particles flow into the channels through the pores. ２ It is believed that the speed of the fluid flowing through the pores of the compound and the channels of the zeolite-type compound is slower than the speed of the fluid flowing on the outer surface of the composite due to flow resistance (frictional force). Due to the influence of such flow resistance, the pressure exerted by the fluid on the particles inside the framework is lower than the pressure exerted by the fluid on the particles present on the outer surface of the framework. Therefore, the separation of the particles inside the framework can be effectively prevented, and the function of the particles can be stably maintained for a long period of time.

[0032] In order to prevent the microparticles contained in the framework from being released, it is preferable that the microparticles have an average particle size larger than the average pore size of the framework. In particular, it is preferable that the framework has an average pore size of 0.05 nm or more and 25.00 nm or less. Furthermore, it is preferable that the average particle size of the microparticles is 0.08 nm or more and 50.00 nm or less.

[0033] Furthermore, the passages of the zeolite-type compound preferably have 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 portion different from any of the one-dimensional pores, two-dimensional pores, and three-dimensional pores. The one-dimensional pores referred to here refer to tunnel- or cage-type pores forming a one-dimensional channel, or multiple tunnel- or cage-type pores (multiple one-dimensional channels) forming multiple one-dimensional channels. The two-dimensional pores refer to two-dimensional channels formed by connecting multiple one-dimensional channels two-dimensionally, and the three-dimensional pores refer to three-dimensional channels formed by connecting multiple one-dimensional channels three-dimensionally.

[0034] More specifically, the one-dimensional, two-dimensional, and three-dimensional pores of zeolite-type compounds refer to the pore structures specific to each type of zeolite that are published in the Database of Zeolite Structures. The enlarged portion of zeolite-type compounds refers to pore structures that are not published therein.

[0035] The average particle size of the microparticles is preferably larger than the average pore sizes of the one-dimensional, two-dimensional, and three-dimensional pores defined by the zeolite-type compound. The microparticles are preferably present at least in the expanded diameter portion, and more preferably are included at least in the expanded diameter portion.

[0036] This further restricts the movement of the microparticles within the framework, making it possible to more effectively prevent the microparticles from detaching or agglomerating together. The inclusion of the microparticles in the expanded diameter section refers to a state in which the microparticles are encapsulated within the zeolite-type compound. In this case, the microparticles and the zeolite-type compound do not necessarily need to be in direct contact with each other; the microparticles may be indirectly held by the zeolite-type compound with another substance (e.g., a surfactant) interposed between them.

[0037] The particles contained in the zeolite-type compound may be present in the passage with some of them protruding outside the enlarged diameter portion, or may be partially embedded or held by adhesion in a portion of the passage other than the enlarged diameter portion (e.g., the inner wall portion of the passage).

[0038] Furthermore, the expanded diameter portion of the zeolite-type compound preferably connects the plurality of pores constituting any one of the one-dimensional pores, the two-dimensional pores, and the three-dimensional pores, thereby providing separate passages different from the one-dimensional pores, the two-dimensional pores, and the three-dimensional pores within the zeolite-type compound, thereby enabling the microparticles to exhibit their functions more effectively.

[0039] Preferably, the passages are formed three-dimensionally within the zeolite-type compound, including branching or confluence portions, and the enlarged diameter portion is provided at the branching or confluence portion of the passages.

[0040] The average inner diameter of the passages formed in the zeolite-type compound is calculated from the average of the minor and major axes of the pores constituting any one of the one-dimensional, two-dimensional, and three-dimensional pores, and is, for example, 0.1 nm to 25.0 nm, preferably 0.5 nm to 5.0 nm. The inner diameter of the expanded diameter portion of the zeolite-type compound is, for example, 0.5 nm to 50.0 nm, preferably 1.1 nm to 40.0 nm, and more preferably 1.1 nm to 3.3 nm. The inner diameter of the expanded diameter portion depends, for example, on the pore size of the precursor material (A) described below and the average particle size of the microparticles to be encapsulated. The inner diameter of the expanded diameter portion is large enough to encapsulate the microparticles.

[0041] The average particle size of the fine particles is preferably greater than the average inner diameter of the passages and less than or equal to the inner diameter of the expanded diameter sections. Within the passages, these fine particles are preferably enclosed by the expanded diameter sections, further restricting their movement within the zeolite-type compound. Therefore, even when the fine particles are subjected to an external force from the fluid, their movement within the zeolite-type compound is further suppressed, effectively preventing contact between the fine particles enclosed by the expanded diameter sections dispersed in the passages.

[0042] When the particles present in the framework are metal oxide particles, the average particle size of the metal oxide particles, whether primary or secondary, is preferably 0.10 nm to 50.00 nm, 0.10 nm to less than 30.00 nm, 0.50 nm to 14.00 nm, or 1.00 nm to 12.00 nm. The ratio of the average particle size of the metal oxide particles to the average inner diameter of the passages of the zeolite compound is preferably 0.06 to 500.00, more preferably 0.10 to 36.00, even more preferably 1.10 to 36.00, and particularly preferably 1.70 to 4.50.

[0043] The metal oxide fine particles preferably contain 0.5% to 2.5% by mass of the metal element (M) in the composite, and more preferably 0.5% to 1.5% by mass of the composite. For example, when the metal element (M) is Co, the content (% by mass) of Co is expressed by {(mass of Co element) / (mass of all elements in the composite)}×100.

[0044] The metal oxide microparticles may be composed of a metal oxide, for example, may be composed of a single metal oxide, or may be composed of a mixture of two or more metal oxides. In this specification, the "metal oxide" (as a material) constituting the metal oxide microparticles means an oxide containing one metal element (M) and a composite oxide containing two or more metal elements (M), and is a general term for oxides containing one or more metal elements (M).

[0045] Examples of such metal oxides include cobalt oxide (CoOｘ ), nickel oxide (NiO ｘ ), iron oxide (FeO ｘ ), copper oxide (CuO ｘ ), silver oxide (AgO Ｘ ), zirconium oxide (ZrO ｘ ), 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 ), magnesium oxide (MgO), calcium oxide (CaO), gallium oxide (GaO Ｘ ) and the like, and it is preferable to use one or more of the above as the main component.

[0046] When the particles present in the framework are metal particles, the average particle size of the metal particles, whether primary or secondary, is preferably 0.08 nm or more and 30.00 nm or less, 0.08 nm or more and less than 25.00 nm, 0.40 nm or more and 11.00 nm or less, or 0.80 nm or more and 11.20 nm or less. The ratio of the average particle size of the metal particles to the average inner diameter of the passages of the zeolite compound is preferably 0.05 or more and 300.00 nm or less, more preferably 0.10 or more and 30.00 nm or less, even more preferably 1.10 or more and 30.00 nm or less, and particularly preferably 1.40 or more and 3.60 nm or less.

[0047] The metal element (M) of the metal fine particles is preferably contained in an amount of 0.5 mass % or more and 2.5 mass % or less relative to the composite, and more preferably 0.5 mass % or more and 1.5 mass % or less relative to the composite.

[0048] The metal microparticles may be composed of any non-oxidized metal, and may be composed of, for example, a single metal or a mixture of two or more metals. In this specification, the term "metal" (as a material) constituting the metal microparticles means a simple metal containing one metal element (M) and a metal alloy containing two or more metal elements (M), and is a general term for metals containing one or more metal elements.

[0049] Examples of such metals include platinum (Pt), rhodium (Rh), palladium (Pd), ruthenium (Ru), nickel (Ni), cobalt (Co), molybdenum (Mo), tungsten (W), iron (Fe), chromium (Cr), cerium (Ce), copper (Cu), silver (Ag), magnesium (Mg), aluminum (Al), zirconium (Zr), and gallium (Ga). It is preferable to use one or more of the above as the main component.

[0050] From the viewpoint of durability, the fine particles are preferably metal oxide fine particles.

[0051] [Function of the Composite] When the microparticles present in the framework come into contact with a fluid, the composite exhibits a function corresponding to the microparticles. Specifically, a fluid that comes into contact with the outer surface of the composite flows into the framework through pores formed on the outer surface, moves through the framework, and exits the framework through other pores formed on the outer surface. When the fluid comes into contact with the microparticles along the path it travels through the framework, a reaction corresponding to the function of the microparticles (e.g., a catalytic reaction) occurs. Furthermore, because the framework has a porous structure, the composite has molecular sieving ability.

[0052] First, the molecular sieving ability of the composite will be described using an example in which the fluid is a liquid containing benzene, propylene, and mesitylene. Compounds (e.g., benzene, propylene) composed of molecules with sizes smaller than the pores or pores can penetrate the framework. On the other hand, compounds (e.g., mesitylene) composed of molecules with sizes larger than the pores or pores cannot penetrate the framework. In this way, when the fluid contains multiple types of compounds, the reaction of compounds that cannot penetrate the framework is restricted, and compounds that can penetrate the framework can be reacted.

[0053] Of the compounds produced within the framework by the reaction, only compounds composed of molecules with a size equal to or smaller than the pores or holes can escape to the outside of the framework and are obtained as reaction products. On the other hand, compounds that cannot escape to the outside of the framework through the pores or holes can escape to the outside of the framework if they are converted into compounds composed of molecules of a size that can escape to the outside of the framework. In this way, by using a complex, a specific reaction product can be selectively obtained.

[0054] In addition, in the zeolite-type compound, the fine particles are preferably enclosed in the expanded diameter portion of the passage. When the average particle size of the fine particles is larger than the average inner diameter of the passages in the zeolite-type compound and smaller than the inner diameter of the expanded diameter portion, small passages are formed between the fine particles and the expanded diameter portion. The fluid that enters the small passages comes into contact with the fine particles. Because the fine particles are enclosed in the expanded diameter portion, their movement within the zeolite-type compound is restricted. This prevents the fine particles from agglomerating within the zeolite-type compound framework. As a result, a large contact area between the fine particles and the fluid can be stably maintained.

[0055] Next, a case where the fine particles have a catalytic function will be described. As an example, the fine particles may be iron oxide (FeO ｘThis section describes the case where dodecylbenzene, a heavy oil, is infiltrated into the framework of the composite. When dodecylbenzene infiltrates the framework, it undergoes an oxidative decomposition reaction, decomposing into various alcohols and ketones. Furthermore, benzene, a light oil, is produced from one of the decomposition products, a ketone (here, acetophenone). This indicates that the iron oxide particles function as a catalyst in the oxidative decomposition reaction. In this way, the composite can be used to convert heavy oil into light oil. Conventionally, hydrocracking using hydrogen was used to convert heavy oil into light oil. In contrast, the composite eliminates the need for hydrogen. Therefore, it can be used to convert heavy oil into light oil even in areas where hydrogen supply is difficult. Furthermore, eliminating the need for hydrogen reduces costs and is expected to promote the use of heavy oil, which has not been fully utilized until now.

[0056] Furthermore, when the composite is used as a catalyst, the composite may be used in the form of a powder, but is preferably used in the form of a catalyst structure using the composite. The catalyst structure may be a molded body obtained by molding a predetermined amount of the composite in a predetermined mold, or may be obtained by attaching a predetermined amount of the composite to the surface of a support. In this case, the catalyst structure may contain various additives in addition to the composite.

[0057] [Method for Producing Composite] Next, a method for producing a composite according to an embodiment will be described. In the method for producing a composite according to an embodiment, fine particles containing metal oxide fine particles or metal fine particles are formed by SiO ２ The precursor material having a structure encapsulated in a hydroxyl-based framework is ２ The composite is heat-treated in a high-temperature atmosphere in the presence of O. This precursor material is precursor material (D) described below. The composite produced by the composite production method of the embodiment is the composite of the above embodiment.

[0058] (Step S1: Preparation Step) First, crystalline SiO ２ A precursor material (A) for obtaining a porous structure skeleton containing a compound is prepared. The precursor material (A) is preferably an ordered mesoporous substance, and is a crystalline SiO 2 that constitutes the skeleton of the composite.２ It can be appropriately selected depending on the type of compound.

[0059] The ordered mesoporous material is preferably a compound having an Si—O skeleton in which pores having a diameter of 1 nm to 50 nm are uniformly sized and regularly developed in one, two, or three dimensions. Such ordered mesoporous materials can be obtained as various synthetic products depending on the synthesis conditions. Specific examples of synthetic products include SBA-1, SBA-15, SBA-16, KIT-6, FSM-16, and MCM-41, with MCM-41 being particularly preferred. The pore diameter of SBA-1 is 10 nm to 30 nm, that of SBA-15 is 6 nm to 10 nm, that of SBA-16 is 6 nm, that of KIT-6 is 9 nm, that of FSM-16 is 3 nm to 5 nm, and that of MCM-41 is 1 nm to 10 nm. Examples of such regular mesoporous materials include mesoporous silica, mesoporous aluminosilicate, and mesoporous metallosilicate.

[0060] The precursor material (A) may be either a commercially available product or a synthetic product. The precursor material (A) can be synthesized using a known method for synthesizing regular mesoporous materials. For example, a mixed solution containing raw materials containing the constituent elements of the precursor material (A) and a templating agent for defining the structure of the precursor material (A) is prepared, the pH is adjusted as necessary, and hydrothermal treatment (hydrothermal synthesis) is performed. The precipitate (product) obtained by the hydrothermal treatment is then recovered (e.g., filtered), washed and dried as necessary, and calcined to obtain the powdered regular mesoporous material, precursor material (A). The solvent for the mixed solution can be, for example, water, an organic solvent such as alcohol, or a mixture thereof. The raw materials are selected depending on the type of framework, and examples include silica agents such as tetraethoxysilane (TEOS), fumed silica, and quartz sand. Furthermore, various surfactants, block copolymers, etc. can be used as the templating agent, and it is preferable to select one depending on the type of synthesized ordered mesoporous material. For example, when preparing MCM-41, a surfactant such as hexadecyltrimethylammonium bromide is suitable. The hydrothermal treatment can be carried out, for example, in a sealed container under treatment conditions of 80°C to 800°C, 5 hours to 240 hours, and more than 101 kPa to 2000 kPa. The calcination treatment can be carried out, for example, in air under treatment conditions of 350°C to 850°C, and 2 hours to 30 hours.

[0061] (Step S2: Impregnation Step) Next, the prepared precursor material (A) is impregnated with a metal-containing solution to obtain a precursor material (B).

[0062] The metal-containing solution may be any solution containing a metal component (e.g., metal ion) corresponding to the metal element (M) constituting the metal oxide microparticles or metal microparticles of the composite, and can be prepared, for example, by dissolving a metal salt containing the metal element (M) in a solvent. Examples of such metal salts include chlorides, hydroxides, oxides, sulfates, and nitrates, with nitrates being preferred. Examples of solvents that can be used include water, organic solvents such as alcohols, and mixtures thereof.

[0063] The method for impregnating the precursor material (A) with the metal-containing solution is not particularly limited. For example, it is preferable to add the metal-containing solution in small amounts in multiple batches while stirring the powdered precursor material (A) before the calcination step described below. Furthermore, from the viewpoint of making it easier for the metal-containing solution to penetrate into the pores of the precursor material (A), it is preferable to add a surfactant as an additive to the precursor material (A) before adding the metal-containing solution. It is believed that such an additive has the function of coating the outer surface of the precursor material (A), preventing the metal-containing solution added thereafter from adhering to the outer surface of the precursor material (A), making it easier for the metal-containing solution to penetrate into the pores of the precursor material (A).

[0064] Examples of such additives include nonionic surfactants such as polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, and polyoxyethylene alkylphenyl ether. These surfactants have large molecular sizes and cannot penetrate the pores of the precursor material (A). Therefore, they do not adhere to the pores and do not prevent the metal-containing solution from penetrating the pores. A preferred method for adding the nonionic surfactant is, for example, adding 50% to 500% by mass of the nonionic surfactant to the precursor material (A) before the firing step described below. If the amount of nonionic surfactant added to the precursor material (A) is less than 50% by mass, the suppression effect described above is difficult to achieve. Adding more than 500% by mass of the nonionic surfactant to the precursor material (A) is undesirable because the viscosity increases too much. Therefore, it is preferable to set the amount of nonionic surfactant added to the precursor material (A) within the above range.

[0065] Furthermore, it is preferable to appropriately adjust the amount of the metal-containing solution added to the precursor material (A) taking into consideration the amount of the metal element (M) in the metal-containing solution impregnated into the precursor material (A) (i.e., the amount of the metal element (M) to be contained in the precursor material (B)). For example, before the firing step described below, the amount of the metal-containing solution added to the precursor material (A) is preferably adjusted so that 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) (atomic number ratio Si / M) is 10 or more and 1000 or less, more preferably 50 or more and 200 or less. For example, if a surfactant is added as an additive to precursor material (A) before adding the metal-containing solution to precursor material (A), the amount of metal-containing solution added to precursor material (A) can be adjusted to 50 to 200 in terms of atomic ratio Si / M, thereby allowing the metal element (M) of the metal oxide microparticles or metal microparticles to be contained in an amount of 0.5 to 2.5 mass% relative to the composite. In the state of precursor material (B), the amount of metal element (M) present within its pores is roughly proportional to the amount of metal-containing solution added to precursor material (A), provided that the metal concentration of the metal-containing solution, the presence or absence of the additive, and other conditions such as temperature and pressure are the same. Furthermore, the amount of metal element (M) present in precursor material (B) is proportional to the amount of metal element constituting the metal oxide microparticles or metal microparticles present in the framework of the composite. 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 into the pores of the precursor material (A), and ultimately, the amount of metal oxide microparticles or metal microparticles present in the framework of the composite can be adjusted.

[0066] After the precursor material (A) has been impregnated with the metal-containing solution, a washing treatment may be carried out as necessary. The washing solution may be water, an organic solvent such as alcohol, or a mixture of these. Furthermore, after the precursor material (A) has been impregnated with the metal-containing solution and washed as necessary, it is preferable to further carry out a drying treatment. Examples of the drying treatment include natural drying overnight or high-temperature drying at 150°C or less. If the calcination treatment described below is carried out while a large amount of moisture contained in the metal-containing solution or the washing solution remains in the precursor material (A), the framework structure of the precursor material (A) as a regular mesoporous substance may be destroyed, so thorough drying is preferable.

[0067] (Step S3: Firing Step) Next, precursor material (B) obtained by impregnating precursor material (A) with the metal-containing solution is fired to obtain precursor material (C).

[0068] The calcination treatment is preferably carried out in air at a temperature of 350° C. to 850° C. for 2 hours to 30 hours, for example. Such calcination treatment causes crystal growth of the metal component impregnated in the pores of the ordered mesoporous material, forming metal oxide fine particles in the pores.

[0069] (Step S4: Hydrothermal Treatment Step) Next, a mixed solution is prepared by mixing the precursor material (C) and a structure-directing agent, and the precursor material (C) is subjected to hydrothermal treatment to form a porous SiO 2 nanoparticle having a plurality of metal oxide fine particles present in the channels. ２ A precursor material (D) which is a base framework is obtained.

[0070] The structure directing agent is SiO ２ The structure-directing agent is a template agent for defining the skeleton structure of the skeletal body, and a surfactant can be used, for example. ２ It is preferable to select a surfactant depending on the skeletal structure of the base skeleton, and for example, surfactants such as tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), and tetrapropylammonium bromide (TPABr) are suitable.

[0071] The precursor material (C) and the structure-directing agent may be mixed during the hydrothermal treatment step or before the hydrothermal treatment step. The method for preparing the mixed solution is not particularly limited. The precursor material (C), the structure-directing agent, and the solvent may be mixed simultaneously, or the precursor material (C) and the structure-directing agent may be dispersed in separate solutions in the solvent, and then the respective dispersion solutions may be mixed. Examples of solvents that can be used include water, organic solvents such as alcohol, and mixtures of these. The pH of the mixed solution is preferably adjusted using an acid or a base before the hydrothermal treatment.

[0072] The hydrothermal treatment can be carried out by a known method, and is preferably carried out in a sealed container under treatment conditions of 80° C. to 800° C., 5 hours to 240 hours, and more than 101 kPa to 2000 kPa. The hydrothermal treatment is also preferably carried out in a basic atmosphere.

[0073] Furthermore, in the above-mentioned hydrothermal treatment step, a mixed solution is prepared by mixing the precursor material (C) with the structure-directing agent, and the precursor material (C) is then hydrothermally treated. However, this is not limiting, and the precursor material (C) may be hydrothermally treated without mixing the precursor material (C) with the structure-directing agent.

[0074] The precipitate obtained after the hydrothermal treatment, precursor material (D), is preferably recovered (e.g., filtered) and then washed, dried, and calcined as necessary. Water, an organic solvent such as alcohol, or a mixture thereof can be used as the washing solution. Examples of drying treatment include natural drying overnight or high-temperature drying at 150°C or lower. Note that performing a calcination treatment while the precipitate still retains a large amount of moisture may destroy the skeletal structure of precursor material (D), so thorough drying is preferred. Furthermore, the calcination treatment can be carried out in air, for example, at 350°C to 850°C for 2 hours to 30 hours. Such a calcination treatment burns off the structure-directing agent attached to precursor material (D). Depending on the intended use, the recovered precipitate of precursor material (D) may not necessarily be calcined.

[0075] (Step S5: Reduction Step) Step S5 is an optional step. ２ The precursor material (D) which is a skeletal body is subjected to a reduction treatment under a reducing gas atmosphere such as hydrogen gas. The reduction treatment reduces the metal oxide particles to form metal particles corresponding to the metal elements that constitute the metal oxide particles. In this way, a porous SiO 2 film having a plurality of metal particles present in the channels is formed. ２ The precursor material (D) is a porous SiO ２ It is preferable that the precursor material (D) contains metal fine particles having an average particle size larger than the pore size of the framework. The method for obtaining the precursor material (D) is not limited to the above-mentioned method.

[0076] (Step S6: Heat Treatment Step) Next, the metal oxide fine particles obtained in step S4 are treated with SiO ２ The precursor material having a structure in which metal particles are encapsulated in a SiO skeletal body, or the metal particles obtained in step S5 ２ Regarding the precursor material having a structure encapsulated in a H-based framework, ２ A composite can be obtained by heat treatment in a high-temperature atmosphere in the presence of O.

[0077] The precursor material (D) can be heat-treated by H ２ From the viewpoint of easily controlling the high-temperature atmosphere in which O is present, ２ It is preferable to carry out a heat treatment at 100°C or higher and 1500°C or lower in an atmosphere in the presence of O. Among these, it is preferable to carry out a dry reforming treatment, a treatment by a partial oxidation method which is a similar reforming reaction system, a steam reforming pretreatment, or a water vapor treatment in which a gas having a predetermined water content (such as nitrogen gas) is passed through the precursor material (D) heated at 100°C or higher and 1500°C or lower for 24 hours or longer.

[0078] Porous SiO ２ The framework may be zeolite or amorphous silica.

[0079] The heat treatment in step S6 reduces the amount of SiO in the porous structure of the precursor material (D). ２A part or all of the framework is crystalline SiO ２ The compound undergoes a phase change.

[0080] In the composite obtained in step S6, the particles present within the framework are metal oxide particles. Furthermore, by subjecting the composite obtained in step S6 to a reduction treatment in an atmosphere of a reducing gas such as hydrogen gas, a composite having a framework with metal particles present within it can be obtained. This reduction treatment reduces the metal oxide particles present within the framework, forming metal particles corresponding to the metal elements that constitute the metal oxide particles.

[0081] [Modifications of the Composite] In the above, an example in which the composite comprises microparticles internal to the framework (hereinafter also referred to as internal microparticles) has been described, but the composite may further comprise at least one microparticle held on the outer surface of the framework (hereinafter also referred to as external microparticles). The external microparticles include metal oxide microparticles or metal microparticles.

[0082] The outer microparticles are substances that exhibit one or more functions. The functions of the outer microparticles may be the same as or different from the functions of the internal microparticles. Specific examples of the functions of the outer microparticles are the same as the functions of the internal microparticles, and it is preferable that the outer microparticles have a catalytic function, in which case the outer microparticles are catalytic substances. Furthermore, when both the outer microparticles and the internal microparticles are substances that have the same function, the material of the outer microparticles may be the same as or different from the material of the internal microparticles. This configuration can increase the content of microparticles held in the composite, further promoting the function of the microparticles.

[0083] According to the embodiment described above, crystalline SiO ２ By using a compound as a structural component of the framework, it is possible to control the change in the crystalline structure of the framework, which is accompanied by a change in density at high temperatures, and the complex can therefore carry out a predetermined reaction stably and safely over a long period of time.

[0084] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure.

[0085] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0086] Example 1 Synthesis of Precursor Material (A) A mixed aqueous solution was prepared by mixing a silica agent (tetraethoxysilane (TEOS), manufactured by Wako Pure Chemical Industries, Ltd.) with a surfactant as a template agent, and the pH was adjusted appropriately. The solution was then subjected to hydrothermal treatment at 100°C for 100 hours in a sealed container. The resulting precipitate was then filtered, washed with water and ethanol, and calcined in air at 600°C for 24 hours to obtain precursor material (A), which was MCM-41. The surfactant used was hexadecyltrimethylammonium bromide (CTAB) (manufactured by Wako Pure Chemical Industries, Ltd.).

[0087] [Preparation of Precursor Materials (B) and (C)] Next, a metal salt containing Ni was dissolved in water to prepare a metal-containing aqueous solution. The metal salt used was NiOx: nickel (II) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.). The metal-containing aqueous solution was then added in small amounts to powdered precursor material (A) in multiple batches, followed by drying at 105°C for 12 hours or more to obtain precursor material (B).

[0088] Before the addition of the metal-containing aqueous solution, the precursor material (A) was subjected to a pretreatment in which an aqueous solution of polyoxyethylene (15) oleyl ether (NIKKOL BO-15V, manufactured by Nikko Chemicals Co., Ltd.) was added as an additive, and then the metal-containing aqueous solution was added as described above.

[0089] The amount of the metal-containing aqueous solution added to the precursor material (A) was adjusted so that the ratio of silicon (Si) constituting the precursor material (A) to the metal element (M) contained in the metal-containing aqueous solution (atomic number ratio Si / M) would be 100.

[0090] Next, the precursor material (B) impregnated with the metal-containing aqueous solution obtained as described above was calcined in air at 600° C. for 24 hours to obtain a precursor material (C).

[0091] [Synthesis of Precursor Material (D)] The precursor material (C) obtained as described above was mixed with tetrapropylammonium bromide (TPABr) (Tokyo Chemical Industry Co., Ltd.), which is a structure-directing agent, to prepare a mixed aqueous solution. The pH was adjusted to 7.0 in a sealed container, and then hydrothermal treatment was carried out at 150°C for 72 hours. Thereafter, the resulting precipitate was 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 to obtain a precursor material (D) having a framework having an MFI zeolite structure and metal oxide fine particles.

[0092] [Synthesis of Composite] Next, 0.2 g of precursor material (D) was placed in a fixed-bed flow reactor and subjected to reduction treatment at 750°C for 90 minutes under a hydrogen gas flow. Next, as shown in Table 1, precursor material (D) was heated to 800°C, and nitrogen gas with a water content of 1% was passed through precursor material (D) at a rate of 10 ml / min, and steam treatment was performed for 90 days. In this way, the composite of Example 1 was obtained.

[0093] Example 2 As shown in Table 1, the composite of Example 2 was obtained in the same manner as in Example 1, except that precursor material (D) was heated to 800°C, nitrogen gas having a water content of 6% was passed through precursor material (D) at a rate of 10 ml / min, and water vapor treatment was performed for 8 days.

[0094] (Example 3) As shown in Table 1, the composite of Example 3 was obtained in the same manner as in Example 1, except that precursor material (D) was heated to 900°C, nitrogen gas having a water content of 2% was passed through precursor material (D) at a rate of 10 ml / min, and water vapor treatment was performed for 7 days.

[0095] Comparative Example 1 Ruthenium (Ru) fine particles were supported on silicalite-1 by impregnation. Silicalite-1 was supported with a Ru nitrate solution (Ru 50 g / L: Tanaka Kikinzoku Co., Ltd.) to a concentration of 2 wt %, and a composite was obtained in which Ru fine particles were attached to the outer surface of silicalite-1 as a framework.

[0096] [Measurements and Evaluations] The precursor materials (D) and composites obtained in the above Examples and Comparative Examples were subjected to the following measurements and evaluations. The results are shown in Table 1.

[0097] [1] Structure of Precursor Material (D) The structure of precursor material (D) was analyzed using an inductively coupled plasma (ICP) emission spectrometer and an XRD device. As a result, precursor material (D) was found to be an MFI zeolite encapsulating nickel oxide fine particles, and contained 1 wt % of Ni, the metal element of the nickel oxide fine particles, relative to precursor material (D).

[0098] [2] Catalytic Activity Test As a catalytic activity test of the composite, a dry reforming reaction was carried out using each composite synthesized above. Specifically, as shown in Table 1, a mixed gas was passed through the composite heated to a predetermined temperature at a predetermined flow rate for a predetermined time to carry out a dry reforming reaction. The produced gas was quantitatively analyzed using GC-TCD and GC-FID, and the CO ２ The conversion rate (%) was measured. The increase or decrease in catalytic activity of the composite was measured on the first day. ２ Conversion rate at 7 days ２ The conversion rate was subtracted from the calculated value.

[0099] [3] Composite Structure The composite was observed using a TEM before and after the catalytic activity test, and the average particle size of the nickel or ruthenium particles was measured. Furthermore, an XRD device was used to analyze the structure of the composite before and after the catalytic activity test, and the abundance ratio of cristobalite contained in the composite was measured. The change in the abundance ratio of cristobalite before and after the catalytic activity test was ranked as follows: ×: The difference in the abundance ratio of cristobalite before and after the catalytic activity test was 30% or more. ○: The difference in the abundance ratio of cristobalite before and after the catalytic activity test was 3% or more but less than 30%. ⊚: The difference in the abundance ratio of cristobalite before and after the catalytic activity test was less than 3%.

[0100]

[0101] As shown in Table 1, in Examples 1 to 3, crystalline SiO ２Since fine particles were present inside the porous structured skeleton containing the compound cristobalite, changes in the cristobalite abundance ratio were suppressed even when the composite was exposed to high temperatures. These results suggest that even when the composite is applied to a molded catalyst or a structured catalyst, density changes at high temperatures can be suppressed and a predetermined reaction can be carried out stably and safely over a long period of time. On the other hand, in Comparative Example 1, the skeleton of the composite was made of crystalline SiO ２ Contains no compounds and is crystalline SiO ２ The particles were present inside the zeolite, which was not a compound. As a result, when the composite was exposed to high temperatures, the zeolite transformed into cristobalite, and the cristobalite content increased, resulting in a large change in density.

[0102] FIG. 1 shows an image of a pellet obtained by pressure molding a predetermined amount of the composite synthesized in Comparative Example 1 after a catalytic activity test. ２ The pellets of Comparative Example 1, in which fine particles were present on the periphery of the zeolite that was not a compound, were partially cracked.

Claims

1. Non-zeolite crystalline SiO ２ a porous framework containing a compound and a zeolite-type compound; Fine particles including metal oxide fine particles or metal fine particles present in the framework; Equipped with The crystalline SiO 2 compound is at least one compound selected from the group consisting of cristobalite, tridymite, quartz, stishovite, and coesite; The fine particles are a composite having an average particle size larger than the average pore size of the framework.

2. A porous structured framework made of a crystalline SiO 2 compound; Fine particles including metal oxide fine particles or metal fine particles present in the framework; Equipped with The crystalline SiO ２ The complex, wherein the compound is at least one compound selected from the group consisting of cristobalite, tridymite, quartz, stishovite, and coesite.

3. The crystalline SiO ２ The complex according to claim 1, wherein the abundance ratio of the compound is 40% or more.

4. The composite according to claim 1 , wherein the microparticles have an average particle size of 0.08 nm or more and 50.00 nm or less.

5. The composite according to claim 1 , wherein the metal oxide fine particles have an average particle size of 0.10 nm or more and 50.00 nm or less.

6. The composite according to claim 1 , wherein the average particle size of the metal particles is 0.08 nm or more and 30.00 nm or less.

7. Fischer-Tropsch synthesis, steam reforming, dry reforming, partial oxidation reforming, methanol reforming, methanol synthesis, hydrocracking, catalytic cracking, hydrodesulfurization, ammonia decomposition, ammonia synthesis, CO shift reaction, reverse shift reaction, exhaust gas purification, fluid catalytic cracking, N ２ O decomposition, CO treatment, NO decomposition, volatile organic substance synthesis, volatile organic substance removal, NO ｘ 13. The complex of claim 1 used in reduction, dehydrogenation of alkanes, olefin synthesis or aromatic synthesis.

8. A catalyst structure comprising the composite according to any one of claims 1 to 7.

9. A method for producing the complex according to claim 1, comprising the steps of: The metal oxide particles or the particles containing metal particles are SiO ２ The precursor material having a structure encapsulated in a H-based framework is ２ A method for producing a composite, comprising heat treating the composite in a high-temperature atmosphere in the presence of O.

10. The SiO ２ The method for producing a composite according to claim 9 , wherein the framework is a zeolite.