Catalyst and method for manufacturing the same, catalyst precursor and method for manufacturing the same, and light reflection preventive material and method for manufacturing the same

Abstract

To provide a catalyst and a method for manufacturing the catalyst, a catalyst precursor and a method for manufacturing the precursor, and a light reflection preventive material and a method for manufacturing the material.SOLUTION: A catalyst precursor includes a phyllosilicate coated body formed of carrier consisting of silicon-containing inorganic material, and phyllosilicate coating at least a part of the surface of the carrier, where metal ion constituting the phyllosilicate is one or more types of ion selected from nickel, cobalt and iron. A catalyst is formed by reducing the catalyst precursor. A light reflection preventive material includes a phyllosilicate coated body formed of carrier consisting of a silicon-containing inorganic material, and phyllosilicate coating at least a part of the surface of the carrier, where metal ion constituting the phyllosilicate is lithium ion and furthermore one or more types of ion selected from nickel, cobalt, copper, zinc and iron.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a catalyst and a method for producing the same, a catalyst precursor and a method for producing the same, and an anti-reflection material and a method for producing the same, which use a phyllosilicate. [Background technology]

[0002] A method for modifying the surface of silica by growing phyllosilicates (layered silicates) on the surface of silica has been disclosed (Patent Document 1). Cations exist between the layers of phyllosilicates, and these can be exchanged and incorporated with metal ions or cationic surfactants. Utilizing this property, it has been proposed to hydrophobize the surface of silica particles, which are originally hydrophilic, by incorporating, for example, a cationic surfactant having a long-chain alkyl group. Hydrophobized silica particles can be used, for example, as fillers for dispersion in various resin materials and cosmetic compositions. Phyllosilicates are expected to be used in a variety of other applications. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6029052 [Non-patent literature]

[0004] [Non-Patent Document 1] Z. Bian, S. Kawi, Journal of CO2 Utilization, 18, 345-352 (2017). [Non-patent document 2] Z. Wu, et al., ACS Catal. 9, 2693-2700 (2019). [Non-patent document 3] Segeun Jang. et al., ACS Appl. Mater. Interfaces 2017, 9, 44038-44044. [Non-patent document 4] Seungmuk Ji, et al., ACS Appl. Mater. Interfaces 2013, 5, 10731-10737. Summary of the Invention [Problem to be solved by the invention]

[0005] An example of the application of the phyllosilicate disclosed by the present inventors is a catalyst in which a catalytic metal is supported on the phyllosilicate. In recent years, hydrogen has been attracting attention as a clean energy source to combat climate change. The steam reforming (SRM) reaction of natural gases such as methane used in the production of hydrogen is the main reaction, accounting for 48% of the world's hydrogen production. This reaction often uses a nickel catalyst in which nickel nanoparticles of approximately 1 to several tens of nanometers are supported on the surface of a support. In general, the smaller the nickel particle size, the higher the activity, as more of the metal particle surface, which is the active site for the catalytic reaction, is exposed. Nickel catalysts are inexpensive and highly active, but they suffer from a tendency to lose activity due to factors such as sintering, where the metal aggregates in high-temperature environments, reducing the active sites on the metal surface, and side reactions that cause carbon to deposit and cover the metal surface, reducing the active sites. To solve this problem, Ni-Co alloying of nanoparticles has been proposed (Non-Patent Document 1), and a change in the electronic state of nickel due to the addition of cobalt has also been reported (Non-Patent Document 2). However, these have not necessarily led to a satisfactory solution.

[0006] Furthermore, one example of the application of the phyllosilicate disclosed by the present inventors is the use of the nano-sized fine structure formed by the phyllosilicate as an anti-reflection material. Conventional anti-reflection materials use a moth-eye structure as a nano-sized microstructure. The refractive index of the moth-eye structure changes continuously from the surface to the bottom, so light incident on the surface is refracted and guided to the bottom, where it is absorbed, without being reflected. Methods for forming a moth-eye structure on a substrate surface are roughly divided into a top-down method (e.g., Non-Patent Document 3) and a bottom-up method (e.g., Non-Patent Document 4). Both methods are methods for forming a moth-eye structure on the surface of a flat substrate, and no consideration has been given to forming a fine structure on the surface of amorphous carrier particles.

[0007] The present invention has been made in view of the above circumstances, and provides a catalyst and a method for producing the same, a catalyst precursor and a method for producing the same, and an anti-reflection material and a method for producing the same, all of which use phyllosilicate. [Means for solving the problem]

[0008] [1] A catalyst precursor comprising a phyllosilicate coating formed from a support made of a silicon-containing inorganic material and a phyllosilicate coating that covers at least a portion of the surface of the support, wherein the metal ions constituting the phyllosilicate are one or more ions selected from nickel, cobalt, and iron. [2] A catalyst comprising a phyllosilicate coating formed from a carrier made of a silicon-containing inorganic material and a phyllosilicate coating covering at least a portion of the surface of the carrier, wherein the metal ions constituting the phyllosilicate are one or more ions selected from nickel, cobalt, and iron, and the metal ions have been reduced to form metals. [3] A method for producing the catalyst precursor according to [1], comprising a step of causing a hydrothermal reaction in a reaction liquid containing a nickel salt, a cobalt salt, water, urea, and a support made of a silicon-containing inorganic material to obtain a catalyst precursor in which at least a portion of the surface of the support is coated with a phyllosilicate, and the proportions of each component mixed in the reaction liquid are such that the molar ratio of nickel is 0.001 to 0.700 and the molar ratio of cobalt is 0.001 to 0.700 relative to 1.000 moles of the support. [4] A method for producing the catalyst according to [2], comprising the steps of obtaining a catalyst precursor by the production method of [3], and heating the catalyst precursor in an atmosphere of inert gas and hydrogen gas to obtain a catalyst in which the metal ions contained in the catalyst precursor are reduced to form a metal. [5] A light-reflection preventing material comprising a phyllosilicate coating formed of a carrier made of a silicon-containing inorganic material and a phyllosilicate coating that covers at least a portion of the surface of the carrier, An anti-reflection material, wherein the metal ions constituting the phyllosilicate are lithium ions and one or more ions selected from nickel, cobalt, copper, zinc, and iron. [6] The anti-reflection material according to [5], wherein the carrier is silicon particles. [7] A method for producing the anti-reflection material described in [5], comprising a step of inducing a hydrothermal reaction in a reaction liquid containing a metal salt, water, urea, and a carrier made of a silicon-containing inorganic material, and coating at least a portion of the surface of the carrier with a phyllosilicate, and the hydrothermal reaction is caused by heating the reaction liquid at 60 to 150°C. [Effects of the Invention]

[0009] The catalyst and catalyst precursor of the present invention and the method for producing them can be used, for example, in the production of hydrogen gas by steam reforming of natural gas. According to the light-reflection preventing material and the method for producing the same of the present invention, a light-reflection preventing material having new optical properties can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows XRD patterns of catalyst precursors prepared in Examples. [Figure 2] 1 is a graph showing the change over time in hydrogen gas generated by the steam reforming reaction of methane gas using a catalyst prepared in an example. [Figure 3] FIG. 1 is a comparison of TEM images of catalysts prepared in Examples before and after catalytic testing. [Figure 4]FIG. 1 is a diagram comparing the XRD patterns of the catalysts and catalyst precursors prepared in the examples. [Figure 5] FIG. 1 is a schematic diagram showing the layer structure of hectorite. [Figure 6] 1 shows XRD patterns of Zn silicates produced in Test Examples A1 to A5. [Figure 7] 1 shows the measurement results of the blackness (L*) of the Zn silicates produced in Test Examples A1 to A5. [Figure 8] 1 shows the results of measuring the diffuse reflectance spectrum in the visible light region of the Zn silicate prepared in Test Example A1. [Figure 9] 1 is an SEM image of the Zn silicate produced in Test Example A1. [Figure 10] FIG. 1 is a diagram comparing the XRD patterns of the Zn silicate prepared in Test Example A5 before and after adsorption of a cationic surfactant. [Figure 11] 10 is an SEM image of the sample prepared in Comparative Test Example a1. [Figure 12] 1 shows the measurement results of the blackness (L*) of the Co silicates produced in Test Examples B1 to B4. [Figure 13] 1 shows the results of measuring the diffuse reflectance spectra in the visible light region of the Co silicates produced in Test Examples B1 to B4. [Figure 14] 1 shows the measurement results of the blackness (L*) of the Ni silicates produced in Test Examples C1 to C4. [Figure 15] 1 shows the results of measuring the diffuse reflectance spectra in the visible light region of the Ni silicates produced in Test Examples C1 to C4. [Figure 16] 1 is an SEM image of the Zn silicate produced in Test Example C4. [Figure 17] FIG. 1 is a graph comparing the blackness (L*) of the Mg silicate prepared in the reference test with the blackness of samples prepared in other test examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Catalyst, catalyst precursor, and method for producing the same> A catalyst precursor according to a first aspect of the present invention includes a phyllosilicate coating formed from a support made of a silicon-containing inorganic material and a phyllosilicate coating at least partially covering the surface of the support. The metal ions contained in the phyllosilicate are one or more ions selected from nickel, cobalt, and iron. These metal ions are preferably divalent ions.

[0012] The silicon-containing inorganic material constituting the support is preferably silica (SiO2) or silicon (Si). The support is preferably made of porous fine particles. From the viewpoint of increasing the contact efficiency with the surrounding reactive materials, the average particle diameter of the support is preferably 1 nm to 100 μm, more preferably 1 nm to 1000 nm, and even more preferably 1 nm to 100 nm. Here, the average particle diameter is defined as the average value of the diameters (major axes) of 20 or more randomly selected fine particles observed in an electron microscope photograph.

[0013] Phyllosilicates (also called layered silicates) that coat the surface of a support can be grown directly on the surface of the support using the sacrificial template method (T. Okada, J. Phys. Chem. C, 116, 21864-21869 (2012)). Using the desired metal ions as the material, silicon (Si) contained in the support is partially dissolved as silicate anions by hydroxide ions generated by hydrolysis of urea in a hydrothermal environment. This, along with the metal ions and hydroxide ions contained in the solution, become the raw materials for the phyllosilicate, which then crystallizes and grows on the surface of the support. The phyllosilicate thus formed has a layered structure consisting of silica and metal oxide layers. For example, a reaction solution containing nickel salt, cobalt salt, urea, porous silica, and water can be thoroughly mixed and heated to form a phyllosilicate containing Ni ions and Co ions (i.e., a Ni, Co oxide layer) that coats at least a portion of the surface of a porous silica support through a hydrothermal reaction.

[0014] The molar ratio of the metal components to be added to the reaction solution is preferably in the following range, where the carrier silica or silicon is taken as 1.000, since this further enhances catalytic activity. The molar ratio of nickel is, for example, 0.001 to 0.700, preferably 0.005 to 0.300, more preferably 0.010 to 0.200, even more preferably 0.020 to 0.090, and most preferably 0.030 to 0.070. The molar ratio of cobalt is, for example, 0.001 to 0.700, preferably 0.005 to 0.300, more preferably 0.010 to 0.200, even more preferably 0.020 to 0.090, and most preferably 0.030 to 0.070. Here, the metal content ratio expressed as (molar ratio of nickel / molar ratio of cobalt) is preferably 0 to 10, more preferably 0.5 to 5.0, further preferably 0.8 to 2.0, and most preferably 1.0 to 1.5.

[0015] The content of urea added to the reaction solution is preferably within the following range, where silica or silicon is taken as a standard of 1.000, because hydroxide ions generated by hydrolyzed urea cause partial dissolution as silicate anions. That is, the molar ratio of urea to silica or silicon is, for example, 0.01 to 10, and most preferably 0.5 to 2.

[0016] Examples of the metal salt to be added to the reaction solution include one or more selected from the group consisting of nickel(II) nitrate, nickel(II) chloride, nickel(II) acetate, cobalt(II) nitrate, cobalt(II) chloride, cobalt(II) acetate, iron(II) nitrate, iron(II) chloride, iron(II) acetate, cobalt(III) chloride, cobalt(III) nitrate, cobalt(III) acetate, iron(III) chloride, iron(III) nitrate, and iron(III) acetate.

[0017] The heating temperature of the reaction liquid containing all the materials is, for example, preferably 100 to 180°C, more preferably 120 to 160°C. The reaction time at the above heating temperature can be completed within, for example, about 12 to 72 hours. The urea in the reaction solution is completely hydrolyzed to form ammonia, and when this is completely consumed, the reaction naturally terminates. The reaction solution is then cooled to obtain the catalyst precursor of the first embodiment, in which at least a portion of the surface of the support is coated with a phyllosilicate. The metal in the obtained phyllosilicate is in an ionic state (e.g., Ni 2+ , Co 2+ divalent metal ions such as The method for cooling the reaction solution is not particularly limited, and examples thereof include a method in which the reaction vessel containing the reaction solution is placed in an ice bath to rapidly cool it.

[0018] The catalyst precursor obtained by the above hydrothermal reaction is washed appropriately with water, alcohol, etc., and then dried to obtain a clean catalyst precursor.

[0019] The catalyst precursor is then heated in the presence of hydrogen gas to reduce the metal ions contained in the phyllosilicate of the catalyst precursor to metal, thereby obtaining the catalyst of the first embodiment. The reduction of metal ions with hydrogen gas can be carried out according to a conventional method, for example, by heating at 700 to 900°C, preferably 750 to 850°C, for about 1 hour while supplying inert gases, nitrogen gas and hydrogen gas.

[0020] ≪Light reflection prevention material≫ A second aspect of the present invention is a silicate-coated body comprising a phyllosilicate coated body formed from a support made of a silicon-containing inorganic material and a phyllosilicate coating covering at least a portion of the surface of the support. From the viewpoint of the applications described below, the metal ions constituting the phyllosilicate are preferably lithium ions and one or more ions selected from nickel, cobalt, copper, zinc, and iron. The use of the silicate-coated body of this embodiment is not particularly limited, but it is useful as an anti-reflection material, similar to conventional anti-reflection materials (light reflection reducing materials) having a moth-eye structure.

[0021] The silicon-containing inorganic material constituting the carrier is preferably silica (SiO2) or silicon (Si) from the viewpoint of ease of production, and silicon, which is a material that is inherently close to black, is more preferable for use as an anti-reflection material. The carrier may also be called a substrate.

[0022] The Si content relative to the total mass of the carrier is, for example, preferably 60 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and may be 100 mass%. The Si content of cutting waste from Si wafers generated during the manufacturing process of semiconductor parts is said to be 99.9 mass% or more, and this may be used as the material of this embodiment.

[0023] The shape of the support is not particularly limited, and examples thereof include ingots, plates, rods, gravels, granules, powders, etc. The average particle size of the particles constituting the powder is, for example, 1 μm to 1000 μm. Here, the average particle size of the particles is the average value of the major axes of 20 randomly selected particles measured using a magnifying observation means such as a microscope.

[0024] The coverage of the phyllosilicate with respect to the total surface area of ​​the support is, for example, preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, most preferably 95% or more, and may even be 100%. Here, the coverage of the support can be determined from an SEM image of the silicate-coated body. Typically, the uncoated area is a smooth surface, and the coated area is a rough surface with a microstructure formed by crystal growth.

[0025] At least a portion of the phyllosilicate constituting the silicate coating of this embodiment is preferably a hectorite-like layered silicate (however, the metal element contained is not limited to Mg.) In other words, the phyllosilicate of this embodiment is preferably a layered silicate similar to known hectorite in which the Mg element constituting known hectorite is substituted with one or more selected from nickel, cobalt, copper, zinc, and iron.

[0026] Generally, hectorite-like layered silicates show characteristic peaks in the XRD pattern of the layer structure of hectorite, a known clay mineral, and elemental mapping by EDX (energy dispersive X-ray spectroscopy) confirms the presence of at least Mg element in the layers. The ideal composition of hectorite is (M y ) y+ -[(Mg 6-x Li x ) oct (Si8) tet O 20 (OH)4] y- In the formula, M represents an interlayer cation such as sodium, x represents a number from 0 to 0.6, and y represents an integer from 0 to 0.6.

[0027] The layer structure of hectorite is shown in Figure 5. Hectorite consists of silicate layers in which SiO4 tetrahedron sheets are condensed above and below MgO6 octahedron sheets, and exchangeable cations (generally Na + It has a structure incorporating hydrated alkali metal ions such as MgO6. 2+ Some of the ions are Li + By isomorphously substituting with ions, the silicate layers become negatively charged. When a hydrothermal reaction is carried out as in the example described below, the ammonia produced by the hydrolysis of urea is converted into NH4 + Since it is incorporated between silicate layers as Na + This is different from hectorite, which incorporates Na + The term "hectorite-like layered silicate" is not limited to the cations, but also includes cases where the cations are other than the cations.

[0028] The silicate-coated body of this embodiment may have any of the following cross-sectional structures in the thickness direction. Structure 1) A structure in which an intermediate layer containing SiO2 and / or modified SiO2 is present on the surface of a support, and an outermost layer containing a hectorite-like layered silicate is present on the surface of the intermediate layer. Structure 2) A structure in which an outermost layer containing a hectorite-like layered silicate is present on the surface of the carrier (a structure in which an intermediate layer is substantially absent).

[0029] When a Si support is used as the support, a SiO2 film is formed on the surface of the Si support by natural oxidation, so structure 1) is more practical. Furthermore, in the method for producing a silicate-coated body described below, Si and / or SiO2 on the substrate surface are hydrolyzed during the hydrothermal reaction to form orthosilicic acid, which becomes a component of the hectorite-like layered silicate, making structure 1) more likely to be obtained.

[0030] In structure 1), the thickness of the intermediate layer is, for example, 1 to 100 nm. In Structure 1) and Structure 2), the thickness of the outermost layer containing the hectorite-like layered silicate is, for example, 10 to 1000 nm. The thickness of the intermediate layer and the outermost layer can be confirmed by a transmission electron microscope (TEM).

[0031] The blackness (L * ) can be any desired value within the range of 20 to 90, for example. The blackness of pure Si is 38.7, and blackness below 38.7 appears darker than pure Si, while blackness above 38.7 appears whiter than pure Si. The further the blackness is from 38.7, the more different the color is from pure Si. The blackness (L * ) is preferably 20 to 30 when a deep black color is required for use as an anti-reflection material.

[0032] The blackness (L * ) is the lightness index (L * ) The portion of the silicate-coated body of this embodiment where the blackness is measured is the surface including the area coated with phyllosilicate.

[0033] The reflectance of visible light in a part of the wavelength range of 400 to 700 nm irradiated onto the silicate-coated body of this embodiment may be higher than the reflectance of silicon alone.

[0034] The reflectance of visible light irradiated onto the silicate-coated body of this embodiment over the entire range or a part of the wavelength of 400 to 700 nm is preferably lower than the reflectance of silicon alone. When the reflectance is low, the body appears dark, exhibiting a matte black color, which is particularly useful in applications as an anti-reflection material.

[0035] <Method for manufacturing anti-reflective material> Another aspect of the present invention is a method for producing a silicate-coated body, which comprises a step of inducing a hydrothermal reaction in a reaction liquid containing a metal salt, water, urea, and a support made of a silicon-containing inorganic material, thereby coating at least a portion of the surface of the support with a phyllosilicate. When the silicate-coated body is used as an antireflection material, this method can be referred to as a method for producing an antireflection material. This production method can produce the phyllosilicate coated body of the second embodiment.

[0036] The metal salts to be added to the reaction solution are a Li salt and a divalent metal salt (hereinafter referred to as X 2+ It is preferable that X is one or more of the following: 2+ When a magnesium salt is used as the cation exchanger, a hectorite-like layered silicate having an ideal composition close to that of hectorite can be formed. In this embodiment, a metal salt capable of supplying one or more ions selected from nickel, cobalt, copper, zinc, and iron is preferred instead of the magnesium salt.

[0037] The molar ratio of each component blended in the reaction solution is based on the known homogeneous nucleation reaction conditions for hectorite (Li:Mg:urea:silicon=1.4:5.3:8.0:8.0). In this embodiment, X is used instead of Li and Mg in the above-mentioned standard. 2+ The compounding ratio of urea and silicon is set to 100%. The standard Mg is the amount of X 2+ Corresponds to. Here, when the compounding ratio of silicon is fixed at 100%, the compounding ratio of Li is preferably 1 to 100%, and X 2+ The compounding ratio of is preferably 1 to 100%, and the compounding ratio of urea is preferably 1 to 100%. For example, the compounding ratio of Li is 1 to 10%, and X 2+ A combination in which the blending ratio of is 1 to 10% and the blending ratio of urea is 20 to 40% can be cited. Li and X 2+ The difference in the compounding ratio is preferably ±20% or less, more preferably ±10% or less, and even more preferably ±5% or less.

[0038] Blackness (L * ), but in order to obtain a silicate coating with a blackness lower than that of Si alone (i.e., an increased blackness), the compounding ratio of silicon is 100%, and the compounding ratio of Li, X 2+ The blending ratio of each of the urea and the urea is preferably as follows: The blending ratio of Li is preferably 1 to 30%, more preferably 1 to 20%, and even more preferably 1 to 10%. X 2+ The blending ratio is preferably 1 to 30%, more preferably 1 to 20%, and even more preferably 1 to 10%. The blending ratio of urea is preferably 1 to 60%, more preferably 5 to 50%, further preferably 10 to 40%, and particularly preferably 20 to 40%. Li and X 2+ The difference in the compounding ratio is preferably ±20% or less, more preferably ±10% or less, and even more preferably ±5% or less.

[0039] The reaction solution containing all the ingredients is thoroughly mixed and heated, causing a hydrothermal reaction to occur spontaneously. The heating temperature is, for example, in the range of 60 to 150°C, and the material is X. 2+ The heating temperature can be set within the above range in 10°C or 5°C increments, for example, to 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C, by appropriately combining the lower and upper limits. Of these, a temperature of 70 to 90°C is preferred, as this makes it easier to obtain a silicate-coated body suitable for use as an antireflection material.

[0040] The reaction time at the above heating temperature is in the range of 6 to 72 hours. 2+ It is preferable to set the reaction time appropriately depending on the type of material. The reaction time can be set within the above range in 6-hour or 3-hour increments, for example, 12 hours, 18 hours, 24 hours, 32 hours, 40 hours, 48 ​​hours, 54 hours, 60 hours, or 66 hours, by appropriately combining the lower and upper limits. Of these, 40 to 54 hours is preferred because it makes it easier to obtain a silicate-coated body suitable for use as an antireflection material.

[0041] The reaction naturally terminates when all of the urea in the reaction solution is hydrolyzed to ammonia and consumed. The reaction solution is then cooled to obtain a silicate-coated body in which phyllosilicate is formed on at least a portion of the surface of the support. The method for cooling the reaction solution is not particularly limited, and examples thereof include a method in which the reaction vessel containing the reaction solution is placed in an ice bath to rapidly cool it.

[0042] Examples of the Li salt to be added to the reaction solution include LiF, LiCl, LiBr, etc. Among these, LiF is preferred because fluoride ions have a particularly strong mineralizing effect. Other metal salts (X 2+ Examples of the metal salt that supplies the cations (metal salts that supply the cations) are preferably those that can supply one or more divalent ions selected from nickel, cobalt, copper, zinc, and iron, and examples thereof include nitrates, chlorides, hydroxides, and oxides containing these metal ions. Specific preferred examples include one or more selected from the group consisting of nickel (II) nitrate, nickel (II) chloride, nickel (II) acetate, cobalt (II) nitrate, cobalt (II) chloride, cobalt (II) acetate, copper (II) nitrate, zinc (II) nitrate, iron (II) nitrate, nickel (II) chloride, copper (II) chloride, zinc (II) chloride, iron (II) chloride, iron (II) chloride, iron (II) chloride, iron (II) acetate, cobalt (III) chloride, cobalt (III) nitrate, cobalt (III) acetate, iron (III) chloride, iron (III) nitrate, and iron (III) acetate. The content of water relative to the total mass of the reaction liquid in which the materials are mixed can be, for example, 80 to 98 mass %. The content of silicon relative to the total mass of the reaction liquid containing the various materials can be, for example, 1 to 10 mass %.

[0043] The silicate-coated body obtained by the above hydrothermal reaction is washed appropriately with water, alcohol, etc., and then dried to obtain a clean silicate-coated body.

[0044] The phyllosilicate contained in the silicate-coated body contains exchangeable cations, and therefore can adsorb, for example, a cationic surfactant. Specifically, by contacting the silicate-coated body with an aqueous solution containing the cationic surfactant for about 1 to 24 hours, a complex in which the cationic surfactant is adsorbed to the phyllosilicate is obtained.

[0045] The type of cationic surfactant is not particularly limited, and for example, a hydrophobic composite can be obtained by adsorbing a long-chain alkyl cationic surfactant having one or more long-chain alkyl groups. From the viewpoints of imparting hydrophobicity and facilitating the adsorption reaction, the number of carbon atoms in the alkyl group constituting the long-chain alkyl group is preferably 10 or more, more preferably 12 to 20, and even more preferably 15 to 18.

[0046] The phyllosilicate in the silicate-coated body obtained by the above-described manufacturing method is believed to contain ammonium ions derived from the raw material urea. In other words, the phyllosilicate has a high affinity for ammonium ions, allowing it to easily adsorb long-chain alkylammonium salts. Examples of long-chain alkylammonium salts include long-chain monoalkyl short-chain trialkylammonium salts and long-chain dialkyl short-chain dialkylammonium salts. Here, the number of carbon atoms in each short-chain alkyl group is preferably 1 to 3, more preferably 1 to 2. The counter anion can be a halide ion such as bromine. [Example]

[0047] The effects of the present invention will be made clearer by the following examples. Note that the present invention is not limited to the following examples, and can be practiced by making appropriate modifications within the scope of the present invention.

[0048] <Creating a catalyst> [Preparation of catalyst precursor] 0.25g of urea, 0.102g of Ni(NO3)2 hexahydrate, 0.102g of Co(NO3)2 hexahydrate, 10.9mL of deionized water, and 0.388g of porous silica particles (AGC Si-Tech, Model H-33, average particle size 3μm) were mixed and stirred for 2 minutes with 45kHz ultrasonic waves, followed by 30 minutes of stirring with a rotating stir bar to obtain a reaction solution. In this formulation, the molar ratio of silica:Ni:Co was 1.000:0.050:0.050. Next, the reaction solution obtained above was heated in a rotary autoclave at 150°C for 48 hours, and then cooled on ice for 2 hours. The reaction product was then collected by centrifugation, washed with water and ethanol, and dried to obtain a catalyst precursor.

[0049] [XRD pattern observation] Observation of the XRD pattern of the catalyst precursor revealed a single (060) reflection peak, which followed Vegard's rule, indicating that Ni and Co ions were dissolved in the octahedral sheets of the phyllosilicate (Figure 1).

[0050] [Reduction of catalyst precursor] 0.1 g of catalyst precursor was pressed into tablets using a mold, and these were then sized on a sieve. The resulting granules were placed in a horizontal glass tube (reaction tube) and expanded from downstream to upstream to a length of 25 mm to form a catalyst layer, leaving a space above the catalyst layer for gas to flow. The downstream and upstream ends of the catalyst layer were packed with quartz wool to secure the catalyst layer. Note that quartz sand was not mixed in this test, but it may be mixed in as per standard methods to increase the volume of the catalyst layer and fill the reaction tube with quartz sand to increase the contact efficiency with the gas. Next, nitrogen gas, an inert gas, was supplied to the reaction tube at a flow rate of 137.6 mL / min, and the temperature was raised to 800°C. Hydrogen gas was then supplied at a flow rate of 30 mL / min, and a hydrogen reduction treatment was carried out for 1 hour to reduce the metals in the catalyst precursor and obtain the desired catalyst.

[0051] [Catalyst Test] The reactor was then cooled to a temperature of 750°C at the outlet, and nitrogen gas was supplied for 30 minutes to fill the reactor. The SRM test was then carried out for 3 hours. The conditions for the SRM test were: catalyst bed length 25 mm, nitrogen gas supply rate 137.6 mL / min, methane gas supply rate 12.4 mL / min, steam supply rate 0.030 g / min (He pressure feed), space velocity SV = 1.3 × 10 4 In order to prevent water from flowing into the analyzer connected downstream, the supply of water vapor was started 5 minutes after the start of the methane supply. The results of the SRM test confirmed the activity of the catalytic reaction (CH4 + H2O → CO + 3H2) that generates hydrogen from the supplied methane and water (Figure 2). Note that in the results shown, the high hydrogen gas concentration up to about 10 minutes after the start of the test indicates that the hydrogen gas adsorbed on the catalyst during the hydrogen reduction process has been desorbed, and is not thought to indicate high catalytic activity. Although the results are not shown, the generation of carbon dioxide was confirmed, suggesting that the water-gas shift reaction was also occurring at the same time.

[0052] [Comparison before and after catalyst test] To confirm the differences between the catalyst immediately before the catalytic test (referred to as B-r800) and the catalyst after the catalytic test (referred to as B-r800-S), a comparison was made using a transmission electron microscope (Figure 3). No significant differences were observed, and no carbon deposition was confirmed. Furthermore, the XRD patterns of both catalysts were also observed, but no significant differences were confirmed (Figure 4). In the XRD patterns shown, "H33" represents porous silica, "B" represents the catalyst precursor, "B-r800" represents the reduced catalyst, and "B-r800-S" represents the catalyst after the catalytic test.

[0053] <Conclusion> It was confirmed that the catalyst according to the present invention has catalytic activity for producing carbon monoxide and hydrogen gas from methane gas and water vapor. It was also found that the particle structure and chemical structure of the catalyst do not change before and after the catalytic reaction, demonstrating good durability of the catalytic function. Furthermore, it was suggested that the strong interaction between the metal and the support makes it difficult for metal migration or sintering (thermal denaturation) to occur during the catalytic reaction, that oxygen species with a high affinity for Co remove carbon, which can be a catalyst poison, and that the change in the electronic state of Ni due to the addition of Co contributes to the above catalytic properties.

[0054] ≪Light reflection prevention material≫ <Znシリケート> [Test Example A1] 0.5 g of Si powder (purity 99.9% or higher) was added to a mixed aqueous solution (10 ml) of LiF, ZnCl, and urea, and dispersed by ultrasonic stirring. The dispersion was then kept at 80 °C in a Teflon (registered trademark) cylindrical container for 48 hours. After the reaction, the container was rapidly cooled in an ice bath. After rapid cooling, the precipitate obtained by centrifugation was washed with ethanol and dried (50°C) to obtain the desired phyllosilicate coating containing Zn ions (sometimes referred to as Zn silicate).

[0055] The amounts of LiF, ZnCl2, and urea contained in the mixed aqueous solution prepared in this test example were based on the standard conditions known to produce hectorite by hydrothermal reaction (mixing 8.0 mol of Si at a molar ratio of Li:Mg:urea = 1.4:5.3:8.0). Specifically, the mixture was mixed at a molar ratio of Li:Zn:urea = 0.07:0.27:2.4 at 8.0 mol of Si. The molar ratio of the mixed water was 1.3 x 10 2 It was. Here, the molar ratios of the actual blending relative to the reference conditions were Li 5.0% (=0.07 / 1.4), Zn 5.1% (=0.27 / 5.3), and urea 30% (=2.4 / 8).

[0056] [Test Example A2] Zn silicate was obtained in the same manner as in Test Example A1, except that the heating temperature for the hydrothermal reaction was 60°C. [Test Example A3] Zn silicate was obtained in the same manner as in Test Example A1, except that the heating temperature for the hydrothermal reaction was 100°C. [Test Example A4] Zn silicate was obtained in the same manner as in Test Example A1, except that the heating temperature for the hydrothermal reaction was 120°C. [Test Example A5] Zn silicate was obtained in the same manner as in Test Example A1, except that the heating temperature for the hydrothermal reaction was 150°C.

[0057] <xrd> The results of measuring the X-ray diffraction patterns of the samples obtained in Test Examples A1 to A5 are shown in Fig. 6. In the figure, the broken line indicates that diffraction peaks characteristic of soconite-like layered silicate were observed. It was confirmed that the target phyllosilicate coating was obtained at any heating temperature from 60 to 150 °C.

[0058] <Degree of blackness> For the samples obtained in Test Examples A1 to A5, the degree of blackness (L * ) based on the color system defined in JIS Z8781-4:2013 was measured using the integrating sphere attachment ISR2600 attached to an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600i). Specifically, after directly applying a solid sample onto the surface of a barium sulfate molded product, the diffuse reflection spectrum obtained by measurement with the above measuring instrument was processed with dedicated software (Shimadzu Corporation, LabSolutions UV-Vis Color) to measure the degree of blackness (L * ). The measurement results are shown in Fig. 7. L * The smaller the measured value of, the lower the lightness and the higher the degree of blackness. Incidentally, the measured value of the degree of blackness (L * ) of the Si powder (purity 99.9% or more) used as a raw material is 38.7.

[0059] <Diffuse reflection spectrum in the visible light region> For the sample obtained in Test Example A1, the diffuse reflection spectrum in the visible light region was measured. Specifically, the sample was applied onto the surface of a barium sulfate molded product and measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600i). The results are shown in Fig. 8. "P-Si" noted in the figure is the measurement result of the Si powder (purity 99.9% or more) used as a raw material, and "ME-Si" is the measurement result of Reference Test Z1 described later.

[0060] <SEM image> The SEM image of the sample obtained in Test Example A1 is shown in Fig. 9. It was found that small particles of scaly crystals characteristic of zinc silicate aggregated spherically.

[0061] <Adsorption of cationic surfactants> 0.1 g of the sample from Test Example A5 was mixed with 30 mL of a water / ethanol solution (volume ratio = 1 / 1) and 0.094 g of dimethyldistearylammonium bromide. The mixture was ultrasonically stirred and then further stirred with a magnetic rotary stirrer for 24 hours at room temperature to allow the cationic surfactant to adsorb onto the sample, resulting in a composite sample. The composite sample was then collected by centrifugation, washed with a water / ethanol solution, and dried to obtain a powder composite sample. The XRD spectrum of this composite sample showed that the 001 diffraction peak of the hectorite-like layered silicate was shifted to a lower angle compared to the spectrum before composite formation (Figure 10). This result indicated that dimethyldistearylammonium ions had been incorporated between the hectorite-like layers.

[0062] [Comparative test example a1] We attempted to produce Zn silicate in the same manner as in Test Example A1, except that LiF was not added to the reaction solution for the hydrothermal reaction. The blackness of the resulting sample was measured, and although not shown, the measured value was significantly higher than that of Test Example A1. Examination of an SEM image of this sample (Figure 11) confirmed that the formation of a microstructure consisting of phyllosilicate on the surface of the Si particles was poor. We concluded that even when the hydrothermal reaction was carried out in the absence of Li ions, the phyllosilicate did not sufficiently coat the Si particles.

[0063] <Coシリケート> [Test Examples B1 to B4] A phyllosilicate coated body containing Co ions (sometimes referred to as Co silicate) was obtained in the same manner as in Test Example A1, except that Co(NO3)2 was used in place of ZnCl2 in the same molar ratio and the heating temperature for the hydrothermal reaction was 80°C, 100°C, 120°C, or 150°C.

[0064] The XRD patterns of the obtained samples were measured, and although not shown, diffraction peaks characteristic of hectorite-like layered silicates were observed in all the samples. The blackness (FIG. 12) and the diffuse reflectance spectrum in the visible light region (FIG. 13) of each of the obtained samples were measured in the same manner as described above. When the SEM image of Test Example B1 (heating temperature 80° C.) was examined, it was found that the surfaces of the Si particles were covered with scale-like or thorn-like crystals similar to those of Test Example A1 (not shown). Test Example B4 (heating temperature 150°C) was tested in the same manner as Test Example A5, and adsorption of the cationic surfactant was confirmed.

[0065] <Niシリケート> [Test Examples C1 to C4] A phyllosilicate coating containing Ni ions (sometimes referred to as Ni silicate) was obtained in the same manner as in Test Example A1, except that Ni(NO3)2 was used in place of ZnCl2 in the same molar ratio and the heating temperature for the hydrothermal reaction was 80°C, 100°C, 120°C, or 150°C.

[0066] The XRD patterns of the obtained samples were measured, and although not shown, diffraction peaks characteristic of hectorite-like layered silicates were observed in all the samples. The blackness (FIG. 14) and the diffuse reflectance spectrum in the visible light region (FIG. 15) of each of the obtained samples were measured in the same manner as described above. When the SEM image of Test Example C1 (heating temperature 80° C.) was examined, it was found that the surfaces of the Si particles were covered with scale-like or thorn-like crystals similar to those of Test Example A1 (not shown). When the SEM image of Test Example C4 (heating temperature 150°C) was examined, it was found that the surfaces of the Si particles were covered with scale-like or thorn-like crystals similar to those of Test Example A1 (Figure 16). The height of the scale-like or thorn-like crystals was higher than in the other test examples, or the refractive index of the phyllosilicate was higher than in the other test examples, which was thought to be the reason why the blackness was particularly lower than in the other test examples. Test Example C4 (heating temperature 150°C) was tested in the same manner as Test Example A5, and adsorption of the cationic surfactant was confirmed.

[0067] <Mgシリケート> [Reference Test Z1] A phyllosilicate coated body containing Mg (sometimes referred to as Mg silicate, and in this example, sometimes referred to as "ME-Si") was prepared in the same manner as in Test Example A1, except that MgCl was used in place of ZnCl at the same molar ratio and the heating temperature for the hydrothermal reaction was set to 150°C. The ME-Si obtained here had the best blackness (L) of any of the materials compared in the inventors' previous research. * =27.3). [Reference Test Z2] Mg silicate was obtained in the same manner as in Reference Test Z1, except that the heating temperature for the hydrothermal reaction was 120°C. [Reference Test Z3] Mg silicate was obtained in the same manner as in Reference Test Z1, except that the heating temperature for the hydrothermal reaction was 100°C. [Reference Test Z4] Mg silicate was obtained in the same manner as in Reference Test Z1, except that the heating temperature for the hydrothermal reaction was 80°C.

[0068] The blackness of each sample was measured in the same manner as above, and the results are shown in Figure 17 together with the results of other test examples.

[0069] <Conclusion> The Zn silicate, Co silicate, and Ni silicate according to the present invention generally have a lower degree of blackness than the Mg silicate of the reference example, and are excellent as anti-reflection materials.

[0070] The phyllosilicate coating of the silicate-coated body of the present invention changes the blackness of the carrier surface, imparting a blackness higher than that of the carrier surface. The silicate-coated body of the present invention can be used, for example, as an anti-reflection material, but can also be used as a pigment added to cosmetics, paints, resin compositions, etc. Furthermore, since the crystals forming the coating have a layered structure and contain cations between the layers, the silicate-coated body of the present invention can also be used as a cation adsorbent or cation exchanger. As illustrated in the examples, the surface of the silicate-coated body can be made lipophilic by adsorbing a cationic surfactant with a long alkyl group.< / xrd>

Claims

1. A catalyst precursor comprising a phyllosilicate coating formed from a support made of a silicon-containing inorganic material and a phyllosilicate coating on at least a portion of the surface of the support, A catalyst precursor, wherein the metal ions constituting the phyllosilicate are one or more ions selected from nickel, cobalt, and iron.

2. A catalyst comprising a phyllosilicate coating formed from a support made of a silicon-containing inorganic material and a phyllosilicate coating at least partially covering the surface of the support, A catalyst in which the metal ions constituting the phyllosilicate are one or more ions selected from nickel, cobalt, and iron, and the metal ions are reduced to form metals.

3. 10. A method for producing the catalyst precursor of claim 1, comprising: The method includes a step of causing a hydrothermal reaction in a reaction liquid containing a nickel salt, a cobalt salt, water, urea, and a support made of a silicon-containing inorganic material, to obtain a catalyst precursor in which at least a portion of the surface of the support is coated with a phyllosilicate, The method for producing a catalyst precursor, wherein the proportions of the components mixed in the reaction solution are such that the molar ratio of nickel is 0.001 to 0.700 and the molar ratio of cobalt is 0.001 to 0.700 relative to 1.000 moles of the support.

4. A method for producing the catalyst of claim 2, comprising: Obtaining a catalyst precursor by the production method of claim 3; and heating the catalyst precursor in an atmosphere of inert gas and hydrogen gas to reduce the metal ions contained in the catalyst precursor to obtain a metal catalyst. Catalyst manufacturing method.

5. A light-reflection preventing material comprising a phyllosilicate coating formed of a carrier made of a silicon-containing inorganic material and a phyllosilicate coating that coats at least a portion of the surface of the carrier, The metal ions constituting the phyllosilicate are lithium ions and at least one ion selected from nickel, cobalt, copper, zinc, and iron.

6. The light-reflection preventing material according to claim 5 , wherein the carrier is silicon particles.

7. A method for producing the light-antireflection material according to claim 5, The method includes a step of inducing a hydrothermal reaction in a reaction liquid containing a metal salt, water, urea, and a support made of a silicon-containing inorganic material, and coating at least a portion of the surface of the support with a phyllosilicate, The hydrothermal reaction is caused by heating the reaction solution at 60 to 150°C. A manufacturing method for anti-reflection material.

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