Powder and method for producing powder

Abstract

To provide a powder having a novel porous structure that has never been seen before. SOLUTION: The powder contains aluminosilicate particles having a molar ratio of SiO2 content to Al2O3 content of 2.1 or more, and the aluminosilicate particles include nanotube particles.

Description

[Technical Field]

[0001] The present invention relates to powders. More specifically, the present invention relates to powders comprising aluminosilicate particles. The present invention also relates to methods for producing the powders. [Background technology]

[0002] Patent Document 1 discloses a powder containing granules formed by aggregation of halloysite containing halloysite nanotubes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 079556 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a powder having a novel porous structure that has not been previously found, and a method for producing the powder. [Means for solving the problem]

[0005] As a result of extensive research to achieve the above object, the present inventors discovered that by setting the molar ratio of the SiO2 content to the Al2O3 content within a predetermined range, a powder having a novel porous structure can be obtained, and thus completed the present invention.

[0006] That is, the present invention provides the following [1] to

[15] . [1] A powder containing aluminosilicate particles in which the molar ratio of the SiO content to the AlO content is 2.1 or more, The powder, wherein the aluminosilicate particles comprise nanotube particles. [2] The powder according to [1], wherein the aluminosilicate particles have pores with a pore diameter of more than 8 nm and not more than 200 nm. [3] The powder according to [1] or [2], wherein the aluminosilicate particles have first pores derived from the nanotube particles and second pores different from the first pores. [4] The powder according to any one of [1] to [3], wherein the aluminosilicate particles have pores with a pore size of 8 nm or less. [5] The powder according to any one of [1] to [4], wherein the aluminosilicate particles have pores with a pore size of 8 nm or less and pores with a pore size of more than 8 nm and 200 nm or less. [6] The powder according to any one of [1] to [5], wherein the aluminosilicate particles have first pores derived from the nanotube particles and having a pore size of more than 8 nm and not more than 200 nm, second pores different from the first pores and having a pore size of more than 8 nm and not more than 200 nm, and pores having a pore size of 8 nm or less. [7] BET specific surface area is 50m 2 The powder according to any one of [1] to [6], wherein the powder has a molecular weight of 1000 or more. [8] The total pore volume is 0.40 cm 3 The powder according to any one of [1] to [7], wherein the powder has a molecular weight of 1.0 or more. [9] The volume of the micropore is 0.01 cm 3 The powder according to any one of [1] to [8], wherein the powder has a molecular weight of 1000 or more.

[10] The amount of water vapor adsorbed is 120 cm at a relative pressure of 0.9. 3 The powder according to any one of [1] to [9], wherein the powder has a molecular weight of 1000 or more.

[11] The adsorption amount of toluene vapor is 40 cm at a relative pressure of 0.9. 3 The powder according to any one of [1] to

[10] , wherein the powder has a molecular weight of 1.001 or more.

[12] The powder according to any one of [1] to

[11] , wherein the amount of NH3 desorption measured by temperature programmed desorption at 400°C or higher is 4.0 μmol / g or more.

[13] The powder according to any one of [1] to

[12] , which has an adsorption amount of methylene blue of 40 mg / g or more.

[14] The powder according to any one of [1] to

[13] , having an average particle size of 0.5 to 200 μm.

[15] A powder containing aluminosilicate particles is calcined at 600 to 900 ° C to obtain a calcined powder; A powder manufacturing method comprising subjecting the calcined powder to an acid treatment, the aluminosilicate particles include nanotube particles; A method for producing a powder, wherein the aluminosilicate particles have a molar ratio of SiO2 content to Al2O3 content of less than 2.1. [Effects of the Invention]

[0007] According to the present invention, a powder having a novel porous structure can be provided, and also a method for producing the powder can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] This is a TEM image of metahalloysite nanotube particles. [Figure 2] TEM image of acid-treated metahalloysite nanotube particles. [Figure 3] 1 is an XRD chart of a calcined powder and an uncalcined powder. [Figure 4] 1 is a graph showing the relationship between the acid treatment temperature and SiO2 / Al2O3 after the acid treatment. [Figure 5] This shows the relationship between SiO2 / Al2O3 and BET specific surface area of ​​powders prepared by adjusting the acid treatment conditions for sintered powders in which the sintering temperature in the sintering process was set to 900°C. [Figure 6] This shows the results of the BET specific surface area when adjusting SiO2 / Al2O3 and changing the firing temperature in the post-firing process. [Figure 7] This shows the total pore volume when adjusting SiO2 / Al2O3 and changing the firing temperature in the post-firing process. [Figure 8] This shows the results of analyzing the pore size distribution by the BJH method for powder that was post-sintered at 500°C. [Figure 9] This shows the results of analyzing the pore size distribution by the BJH method for powder that was post-sintered at 900°C. [Figure 10] This is an SEM image of the calcined powder (SiO2 / Al2O3=2.0) before acid treatment. [Figure 11] This is an SEM image of the calcined powder (SiO2 / Al2O3=2.0) before acid treatment. [Figure 12] This is an SEM image of powder (SiO2 / Al2O3=13.7) that was post-fired at 900°C. [Figure 13] This is an SEM image of powder (SiO2 / Al2O3=13.7) that was post-fired at 900°C. [Figure 14] This shows the results of analyzing the pore size distribution by the GCMC method for powder that was post-sintered at 500°C. [Figure 15] This shows the results of analyzing the pore size distribution by the GCMC method for powder that was post-sintered at 900°C. [Figure 16] 1 shows the water adsorption isotherm for the powder that was post-calcined at 500°C. [Figure 17] 1 shows the water adsorption isotherm for the powder that was post-calcined at 900°C. [Figure 18] 1 shows the adsorption isotherm of toluene for the powder that was post-calcined at 500°C. [Figure 19] 1 shows the adsorption isotherm of toluene for the powder post-calcined at 900°C. [Figure 20] This shows the results of NH3-TPD measurement of powders that were post-calcined at 500°C. [Figure 21] This shows the results of NH3-TPD measurement of powders that were post-calcined at 900°C. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0010] [Powder] The powder of the present invention contains aluminosilicate particles having a molar ratio of SiO2 content to Al2O3 content of 2.1 or more. The aluminosilicate particles include nanotube particles.

[0011] The content of the aluminosilicate particles is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total mass of the powder of the present invention. There is no particular upper limit to the content of the aluminosilicate particles in the powder of the present invention, and it may be 100% by mass based on the total mass of the powder. In other words, the powder of the present invention may consist of aluminosilicate particles.

[0012] In the aluminosilicate particles contained in the powder of the present invention, the molar ratio of the SiO2 content to the Al2O3 content (hereinafter simply referred to as "SiO2 / Al2O3") is 2.1 or more. The SiO2 / Al2O3 ratio in the aluminosilicate particles can be adjusted appropriately depending on the application of the powder, but is preferably 2.5 or more, more preferably 3.0 or more, and even more preferably 5.0 or more, in order to increase the BET specific surface area described below. There are no particular upper limits for the SiO2 / Al2O3 ratio, but examples include 10,000 or less and 1,000 or less, with 500 or less being preferred, 300 or less being more preferred, and 200 or less being even more preferred. SiO2 / Al2O3 is determined by X-ray fluorescence (XRF) analysis. Specifically, analysis is performed by XRF under the following conditions, and the SiO2 / Al2O3 ratio is calculated from the obtained SiO2 and Al2O3 contents. Equipment used: ZSX Primus IV (Rigaku Corporation) Pretreatment method: Glass bead method using Li2B4O7 flux Quantitative method: Refractories Technology Association standard sample for X-ray fluorescence analysis (clay brick standard sample series) and calibration curve method using other reagents

[0013] The aluminosilicate particles contained in the powder of the present invention include nanotube particles. The aluminosilicate particles may be composed of a single nanotube particle, or may be secondary particles containing nanotube particles as primary particles, i.e., aluminosilicate granules containing nanotube particles. When the aluminosilicate particles are aluminosilicate granules, there are no particular limitations as long as they contain nanotube-shaped particles as primary particles, and they may contain particles other than nanotube-shaped particles as primary particles. The content of nanotube-shaped particles in the aluminosilicate granules is preferably 50 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more, based on the total mass of the aluminosilicate granules. The upper limit of the content of nanotube-shaped particles is not particularly limited, and may be 100 mass% based on the total mass of the aluminosilicate granules. In other words, the aluminosilicate granules may be granules formed by aggregation of nanotube-shaped particles.

[0014] The aluminosilicate particles contained in the powder of the present invention preferably have pores derived from the nanotube particles. The nanotube particles are preferably particles derived from halloysite nanotubes, which will be described later. Halloysite is a clay mineral represented by Al2Si2O5(OH)4·2H2O or Al2Si2O5(OH)4. That is, the SiO2 / Al2O3 (molar ratio) in halloysite is generally 2.0. Halloysite generally exhibits a variety of shapes, such as tubular (hollow tubular), spherical, angular nodular, plate-like, and sheet-like shapes. The inner diameter (diameter of the tube pore) of a halloysite nanotube particle, which is a tubular (hollow tubular) halloysite, is, for example, about 10 to 20 nm. It is generally said that the outer surface of a halloysite nanotube particle is mainly made of silicate (SiO2) and the inner surface is mainly made of alumina (Al2O3).

[0015] In addition, particles derived from halloysite nanotubes are a concept that includes halloysite nanotube particles and particles obtained by subjecting halloysite nanotube particles to the treatment described below (hereinafter also referred to as "modified halloysite nanotube particles"), and modified halloysite nanotube particles are preferred. Examples of modified halloysite nanotube particles include metahalloysite nanotube particles obtained by calcining halloysite, and acid-treated metahalloysite nanotube particles obtained by subjecting metahalloysite nanotube particles to an acid treatment, with acid-treated metahalloysite nanotube particles being preferred. The aluminosilicate particles contained in the powder of the present invention may include halloysite nanotube particles and modified halloysite nanotube particles, or may include two or more types of modified halloysite nanotube particles. The method for obtaining the modified halloysite nanotube particles and the physical properties of the modified halloysite nanotube particles will be described in detail later.

[0016] The preferred properties of the powder of the present invention will be described below, followed by a description of the method for obtaining the powder of the present invention.

[0017] <pores> The aluminosilicate particles contained in the powder of the present invention preferably have pores. The pores preferably have a pore diameter of more than 8 nm and not more than 200 nm. The presence or absence of pores can be confirmed by measuring an adsorption isotherm. Specifically, a nitrogen adsorption isotherm is obtained, and the nitrogen adsorption isotherm is analyzed using the BJH (Barrett-Joyner-Halenda) method. A plot (Log differential pore volume distribution) is created with pore diameter on the horizontal axis and differential pore volume on the vertical axis, thereby confirming the presence or absence of pores in the above pore diameter range. The measurement conditions for obtaining the nitrogen adsorption isotherm will be described in detail in the Examples section below. The same applies to the other measurement conditions below.

[0018] The aluminosilicate particles contained in the powder of the present invention preferably have first pores derived from the nanotube particles and second pores different from the first pores. The first pores preferably correspond to the tube pores of the nanotube particles. The second pores preferably correspond to the interparticle voids of the nanotube particles contained in the aluminosilicate particles (preferably aluminosilicate granules). The pore diameters of the first pores and the second pores are preferably both in the range of more than 8 nm to 200 nm, and preferably both in the range of 10 to 100 nm. The pore diameter of the first pores is preferably in the range of 10 to 20 nm. It is also preferable that the Log differential pore volume distribution analyzed by the BJH method shows two or more pore diameter peaks in the above range. In aluminosilicate granules, a pore size peak corresponding to the interparticle voids (secondary pores) of the nanotube particles is often observed. The presence or absence of pores with a pore diameter of more than 8 nm and not more than 200 nm, and the presence or absence of first pores and second pores can also be confirmed by observing aluminosilicate particles (preferably aluminosilicate granules) with a scanning electron microscope (SEM). When the surface of the aluminosilicate granules is observed with an SEM, the presence of first pores derived from the tubular structure of the nanotube particles can be confirmed, and when the cross section of the aluminosilicate granules is observed with an SEM, the presence of second pores can be confirmed. For example, the cross section of the aluminosilicate granules can be observed by cutting the aluminosilicate granules with a focused ion beam (FIB) to obtain a sample and then observing the sample.

[0019] The aluminosilicate particles contained in the powder of the present invention preferably have third pores with a pore diameter of 8 nm or less. The third pores with a pore diameter of 8 nm or less may be present together with the pores with a pore diameter of more than 8 nm and less than 200 nm. That is, the aluminosilicate particles contained in the powder of the present invention may have third pores with a pore diameter of 8 nm or less and pores with a pore diameter of more than 8 nm and less than 200 nm. Furthermore, the aluminosilicate particles contained in the powder of the present invention may have the first pores with a pore diameter of more than 8 nm and less than 200 nm, the second pores with a pore diameter of more than 8 nm and less than 200 nm, and the third pores with a pore diameter of 8 nm or less. The aluminosilicate particles contained in the powder of the present invention may not have the second pores but may have the first pores and the third pores. An embodiment in which the aluminosilicate particles do not have the second pores includes an embodiment in which the aluminosilicate particles are not granules. The presence or absence of third pores with a pore size of 8 nm or less can be confirmed by performing a so-called t-plot analysis of the nitrogen adsorption isotherm to confirm the presence or absence of micropores with a size of less than 2 nm, or by fitting the nitrogen adsorption isotherm using the Grand Canonical Monte Carlo (GCMC) method to obtain a pore size distribution. The third pores having a pore size of 8 nm or less are present in, for example, acid-treated metahalloysite nanotube particles, so that when aluminosilicate particles contain acid-treated metahalloysite nanotube particles, the aluminosilicate particles have third pores having a pore size of 8 nm or less. Note that general halloysite nanotube particles do not have third pores having a pore size of 8 nm or less. The third pores having a pore diameter of 8 nm or less are preferably, for example, 0.6 to 5 nm. The third pores having a pore diameter of 8 nm or less may have multiple peaks in the pore diameter range of 8 nm or less in the pore diameter distribution obtained by the above method.

[0020] The aluminosilicate particles (preferably aluminosilicate granules) contained in the powder of the present invention may have pores with a pore size of more than 200 nm. The pores with a pore size of more than 200 nm may be present together with at least one of the pores with a pore size of more than 8 nm and 200 nm or less and the third pores with a pore size of 8 nm or less. The presence or absence of pores with a pore diameter of more than 200 nm can be confirmed by observing the surface of aluminosilicate particles (preferably aluminosilicate granules) using the SEM described above. In this specification, the size (pore diameter) of pores with a pore diameter of more than 200 nm is defined as the diameter of the pores observed from the surface of the aluminosilicate particles (preferably aluminosilicate granules). When the shape of the pores is not a perfect circle, the maximum diameter is defined as the pore diameter of pores with a pore diameter of more than 200 nm. The pore diameter of pores with a pore diameter of more than 200 nm is preferably 0.3 μm or more, more preferably 0.5 μm or more. There is no particular upper limit to the pore diameter of the pores with a pore diameter of more than 200 nm, but it is often 10 μm or less, and preferably 5 μm or less. The pore size of the pores having a diameter of more than 200 nm is often 99% or less, preferably 90% or less, or may be 70% or less of the diameter (maximum diameter) of the aluminosilicate granules. The pore size of the pores having a diameter of more than 200 nm is often 1% or more, preferably 5% or more, 10% or more, or may be 30% or more of the diameter (maximum diameter) of the aluminosilicate granules.

[0021] The third pores with a pore size of 8 nm or less are nano-spaces in a range close to the molecular size, and can function as specific reaction sites and specific adsorption sites for molecules. When the aluminosilicate particles have third pores with a pore size of 8 nm or less, the powder of the present invention can be used, for example, as a catalyst, a catalyst support, an adsorbent, etc.

[0022] Furthermore, pores with a diameter of more than 8 nm and not more than 200 nm are a region encompassing mesopores (2 nm to less than 50 nm) and macropores (50 nm or greater). Compared to the third pores with a diameter of 8 nm or less, they are believed to have superior mass transport properties and contribute to rapid reactions and adsorption, making them suitable for applications similar to those described above. Furthermore, the inclusion of the third pores with a diameter of 8 nm or less is believed to enable even better performance. The first pores are believed to originate from the pores of nanotube-shaped particles and have a tubular structure of a predetermined length, which is expected to enable them to function as shape-selective catalysts that selectively act on the shape of molecules, etc. Furthermore, when the third pores with a diameter of 8 nm or less and the first pores are present, the third pores with a diameter of 8 nm or less are believed to be formed on at least one of the inner and outer walls of the nanotubes with a tubular structure of a predetermined length, which is believed to enable even better performance. The catalytic action is not limited to the surface of the aluminosilicate particles, but the diffusion within the particles is improved, and the entire aluminosilicate particle is involved in the reaction, which is expected to have effects such as an improved reaction rate and improved catalyst durability. In addition, by placing the protein serum albumin in the pores in the above region, it is thought that it could be used as a synthesis site for pharmaceuticals and other products that is similar to the environment inside the body.In addition, it could be applied to the food industry (for example, to adsorb and remove unnecessary proteins generated during the production process of seasonings, etc.). Furthermore, the pores in the mesopore region (2 nm or more and less than 50 nm) can cause molecular adsorption accompanied by liquefaction due to capillary condensation, and can exhibit large adsorption amounts, and therefore can also function as adsorbents (e.g., moisture absorbents) that repeatedly adsorb and desorb, as well as sustained-release materials, etc.

[0023] Pores with a diameter of more than 200 nm are believed to be able to adsorb larger objects, thereby contributing to the promotion of adsorption and reaction of solid substances. For example, pores with a diameter of more than 200 nm can capture dust, viruses, bacteria, pollen, etc., and cause them to react (e.g., inactivate). In addition, pores with a diameter of more than 200 nm have excellent diffusion properties, which can further promote mass transfer when used in the above applications.

[0024] Furthermore, the powder of the present invention may simultaneously have third pores with a pore diameter of 8 nm or less and pores with a pore diameter of more than 8 nm and less than 200 nm, and may also have pores with a pore diameter of more than 200 nm. The powder of the present invention having both of the above pores has a novel multimodal nanospace structure, and the powder of the present invention having such a nanospace structure is expected to promote unexplored chemical reactions and has the potential to open up new technologies in fields such as the environment, energy, food, and medicine.

[0025] The advantages of having the above-mentioned pores are merely examples, and it goes without saying that the powder of the present invention can be used in general applications as a porous material. The formation of each of the above pores and the adjustment of each of the pores can be controlled by the procedure and conditions of the manufacturing method described later.

[0026] <Specific surface area> The specific surface area (BET specific surface area) of the powder of the present invention is 50 m 2 / g or more is preferable, and 100m 2 / g or more is more preferable, and 200m 2 The upper limit of the BET specific surface area is not particularly limited, but for example, it is 1000 m 2 / g or less, and 600m 2 / g or less in most cases. The BET specific surface area can be determined by applying the BET method to a nitrogen adsorption isotherm.

[0027] When the powder of the present invention has the above BET specific surface area, it can be suitably used as, for example, a catalyst, a catalyst support, an adsorbent, and the like. The BET specific surface area can be adjusted by the procedure and conditions of the production method described later.

[0028] <Pore volume> The total pore volume of the powder of the present invention is 0.40 cm 3 / g or more is preferable, and 0.50 cm 3 / g or more is more preferable, and 0.60cm 3 The upper limit of the total pore volume is not particularly limited, but for example, 2.00 cm 3 / g or less, 1.20cm 3 / g or less in most cases. The total pore volume is calculated from the adsorption amount at a relative pressure of 0.99 from the nitrogen adsorption isotherm using the following formula: Vp=V / 22414×Mg / ρg Vp: total pore volume up to relative pressure (0.99) V: Adsorption amount at relative pressure (0.99) 22414:Volume of gas per mole Mg: Molecular weight of adsorbate (N2) (28.013) ρg: Density of adsorbate (N2) (0.808)

[0029] When the powder of the present invention has the above total pore volume, it can be suitably used as, for example, a catalyst, a catalyst support, an adsorbent, a sustained-release material, and the like. The total pore volume can be adjusted by the procedure and conditions of the production method described later.

[0030] In addition, when the powder of the present invention has micropores (less than 2 nm), the volume of the micropores is less than 0.01 cm 3 / g or more is preferable, and 0.02 cm 3 / g or more is more preferable, and 0.04cm 3 / g or more is more preferable, and 0.08 cm 3 The upper limit of the volume of the micropores is not particularly limited, but for example, it is 0.5 cm 3 / g or less, and 0.2cm 3 / g or less in most cases. The volume of the micropores is determined by analysis using the t-plot method. The volume of the micropores can be adjusted by the procedure and conditions of the manufacturing method described later.

[0031] <Water vapor adsorption amount> The water vapor adsorption amount of the powder of the present invention is 120 cm at a relative pressure of 0.9. 3 / g or more is preferable, and 200cm 3 / g or more is more preferable, and 300cm 3 The upper limit of the water vapor adsorption amount is not particularly limited, but for example, it is 2000 cm at a relative pressure of 0.9. 3 / g or less, and 1000cm 3 / g or less in most cases. The amount of water vapor adsorption at a relative pressure of 0.9 is obtained from the water vapor adsorption isotherm at 25°C.

[0032] When the powder of the present invention has the above water vapor adsorption amount, it is suitably used, for example, as a catalyst, a catalyst carrier, a humidity conditioner, a sustained-release material, etc. It is also suitably used as an adsorbent utilizing its hydrophilicity. The amount of water vapor adsorption can be adjusted by the procedure and conditions of the production method described later.

[0033] <Toluene vapor adsorption amount> The toluene vapor adsorption amount of the powder of the present invention is 40 cm at a relative pressure of 0.9. 3 / g or more is preferable, and 50cm 3 / g or more is more preferable, and 60cm 3 The upper limit of the toluene adsorption amount is not particularly limited, but for example, it is 200 cm at a relative pressure of 0.9. 3 / g or less, and 150cm 3 / g or less in most cases. The amount of toluene vapor adsorption at a relative pressure of 0.9 was obtained from the adsorption isotherm of toluene vapor at 25°C.

[0034] When the powder of the present invention has the above-mentioned toluene vapor adsorption amount, it can be suitably used as, for example, a catalyst, a catalyst support, an adsorbent, and the like. The amount of toluene vapor adsorption can be adjusted by the procedure and conditions of the production method described later.

[0035] <Solid acid amount> The amount of NH desorption from the powder of the present invention measured by temperature programmed desorption at 400°C or higher is preferably 4 μmol / g or more, more preferably 5 μmol / g or more, and even more preferably 10 μmol / g or more. There is no particular upper limit to the amount of NH desorption, but it can be, for example, 1000 μmol / g or less, and is often 500 μmol / g or less. The amount of NH3 desorption at 400° C. or higher by the temperature programmed desorption method can be obtained by measurement at 100 to 800° C. The detailed measurement method is as described in the Examples section below. The amount of NH3 desorbed at temperatures above 400°C by the temperature programmed desorption method is thought to correspond to the amount of solid acid with a relatively high acid strength.

[0036] When the powder of the present invention has the above-mentioned amount of NH3 desorption, it can be suitably used as, for example, a catalyst that utilizes a solid acid, a catalyst support, a dual-function catalyst, an adsorbent, and the like. Furthermore, when the powder of the present invention contains aluminosilicate granules, it can be said that the powder of the present invention can be easily applied to catalytic reactions using a flow method. The amount of NH3 released can be adjusted by the procedure and conditions of the production method described later.

[0037] <Amount of methylene blue adsorbed> The methylene blue adsorption amount of the powder of the present invention is preferably 40 mg / g or more, more preferably 50 mg / g or more, and even more preferably 60 mg / g or more. There is no particular upper limit to the methylene blue adsorption amount, but it can be, for example, 200 mg / g or less, and is often 100 mg / g or less. The above methylene blue adsorption amount indicates the amount of methylene blue adsorbed per gram of the powder of the present invention. The amount of methylene blue adsorbed per gram of powder is calculated from the concentration of the methylene blue solution before it comes into contact with the powder (pre-contact concentration), the concentration of the methylene blue solution obtained by stirring the powder and methylene blue solution overnight and then subjecting the solution to solid-liquid separation in a centrifuge (post-contact concentration), the amount of methylene blue solution used, and the amount of powder added. The concentration of methylene blue is measured from the absorbance at 664.5 nm.

[0038] When the powder of the present invention has the above-mentioned adsorption amount of methylene blue, it can be suitably used as an adsorbent for dyes, cationic ions, etc. The amount of methylene blue adsorbed can be adjusted by the procedure and conditions of the production method described later.

[0039] <Metahalloysite nanotube particles> The metahalloysite nanotube particles that may be contained in the above-mentioned aluminosilicate particles refer to nanotube-shaped halloysite in which the OH of halloysite represented by Al2Si2O5(OH)4 has been dehydrated, resulting in a low crystallinity, and metahalloysite is a term that has traditionally been used generally or customarily to represent a variant of halloysite. The metahalloysite nanotube particles are obtained by firing the halloysite nanotube particles at a predetermined temperature. The predetermined temperature is preferably 600°C or higher. The upper limit of the predetermined temperature is preferably 925°C or lower, more preferably 900°C or lower.

[0040] <Acid-treated metahalloysite nanotube particles> In this specification, acid-treated metahalloysite nanotube particles refer to those obtained by subjecting metahalloysite nanotube particles to acid treatment as described above. In the acid-treated metahalloysite nanotube particles, the Al2O3 content is often reduced by the acid treatment compared to before the acid treatment. For example, aluminosilicate particles containing acid-treated metahalloysite nanotube particles are likely to satisfy the above-mentioned SiO2 / Al2O3 requirement. In the acid-treated metahalloysite nanotube particles, pores other than the pores corresponding to the inner diameter of the halloysite nanotube particles are often generated by the acid treatment. The acid-treated metahalloysite nanotube particles preferably have third pores with a pore diameter of 8 nm or less.

[0041] Figure 1 shows a transmission electron microscope (TEM) image of metahalloysite nanotube particles (before acid treatment, SiO2 / Al2O3 = 2.0, calcined at 900°C), and Figure 2 shows a TEM image of acid-treated metahalloysite nanotube particles (SiO2 / Al2O3 = 6.3, dried at 110°C). In the metahalloysite nanotube particles (Figure 1), there is little difference in contrast in the tube wall, and it can be seen that the wall thickness is uniform. In contrast, in the acid-treated metahalloysite nanotube particles (Figure 2), a clear difference in contrast is observed in the tube wall, and the white-colored areas in Figure 2 can be said to correspond to empty voids, which are therefore thought to contain pores (third pores with a pore diameter of 8 nm or less) (see the Examples section below). The above TEM images were taken using a JEOL "JEM-ARM200F" equipped with a cold cathode field emission electron gun (Cold-FEG) at an accelerating voltage of 20 kV.

[0042] Furthermore, as a result of investigations by the present inventors, it was found that the physical properties of the acid-treated metahalloysite nanotube particles obtained vary depending on the firing temperature when the metahalloysite nanotube particles are obtained. The firing temperature for the metahalloysite nanotube particles is preferably within the above-mentioned range, and can be adjusted appropriately depending on the desired physical properties of the powder. Furthermore, the conditions for the acid treatment when obtaining acid-treated metahalloysite nanotube particles can be adjusted as appropriate depending on the physical properties of the desired powder. The physical properties, such as the specific surface area, of the powder of the present invention containing aluminosilicate particles including acid-treated metahalloysite nanotube particles can be adjusted as appropriate by the temperature of the acid treatment, the time of the acid treatment, the type of acid used, the acid concentration, and the amount of treated powder relative to the acid. The physical properties of the powder can also be adjusted by the number of acid treatments. For example, repeated acid treatment can increase the SiO2 / Al2O3 ratio. Furthermore, the acid-treated metahalloysite nanotube particles may be further subjected to a calcination treatment after the acid treatment. The calcination treatment also makes it possible to adjust the physical properties of the powder of the present invention, such as the specific surface area. Furthermore, the calcination treatment makes it possible to adjust the moisture content of the powder of the present invention. For details of the relationship between conditions such as acid treatment conditions and physical properties such as the specific surface area of ​​the powder of the present invention, please refer to the production method and examples described later.

[0043] <Other components and other particles> In the powder of the present invention, the aluminosilicate particles may contain components other than the nanotube particles. For example, the aluminosilicate particles may contain a catalytic component that drives a desired reaction. The catalytic component may be supported on the aluminosilicate granules or nanotubular particles as particles, or as clusters of single atoms or several atoms. The catalytic component may also be supported on the aluminosilicate granules and nanotubular particles. The elements contained in the catalyst component are not particularly limited and can be selected depending on the desired reaction. Examples of elements contained in the catalyst component include Group 1 elements to Group 17 elements, and often contain transition metal elements or rare earth elements. The type of element contained in the catalyst component may be one type, or two or more types. The above-mentioned catalyst component is a concept that includes not only a catalyst component that promotes the desired reaction, but also so-called co-catalysts that promote the progress of the desired reaction. Known catalyst components can be used, and known methods can be appropriately used to support the catalyst components.

[0044] In the powder of the present invention, the aluminosilicate particles may contain a medicinal component as a component other than the nanotube particles. The medicinal component is not particularly limited, and examples thereof include known deodorant components, antibacterial components, bactericidal components, and pharmaceutical components.

[0045] Furthermore, the aluminosilicate particles (preferably aluminosilicate granules) may contain particles (other particles) other than the nanotube particles, as described above. The other particles are not particularly limited, but examples thereof include magnetic particles, colorant particles, and drug particles. For example, when the aluminosilicate granules contain magnetic particles, the aluminosilicate granules can be collected by magnetic force.

[0046] <Characteristics of powder> The average particle size of the powder of the present invention is not particularly limited and may be appropriately selected depending on the application, but is, for example, 0.5 to 200 μm, preferably 1 to 100 μm. The powder of the present invention may be granulated before use. The size of the granulated powder is preferably 5 mm or less. The granulated powder may be subjected to at least one of crushing and pulverization to adjust the average particle size. The average particle size is measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII) manufactured by Microtrac Bell.

[0047] The powder of the present invention also preferably has a breaking strength of 5.0 MPa or more for the aluminosilicate particles (preferably aluminosilicate granules). When the aluminosilicate particles (preferably aluminosilicate granules) contained in the powder of the present invention have the above breaking strength, pores with diameters of more than 8 nm and not more than 200 nm (e.g., first pores and second pores, particularly the second pores) are likely to be maintained. Therefore, when the aluminosilicate particles (preferably aluminosilicate granules) contained in the powder of the present invention have the above breaking strength, they are less likely to be broken during handling, pretreatment (e.g., dispersion treatment), and composite treatment (e.g., kneading with resin), and the pores can be maintained. On the other hand, common porous materials such as silica gel, mesoporous silica, and activated carbon often have low particle breaking strength, and the particles may be broken during the above-mentioned operations, making it impossible to maintain the pore structure. The breaking strength is more preferably 6.0 MPa or more, and even more preferably 7.0 MPa or more. There is no particular upper limit to the breaking strength, and it is, for example, 60.0 MPa or less, preferably 50.0 MPa or less, and more preferably 45.0 MPa or less.

[0048] The breaking strength of the aluminosilicate particles (preferably aluminosilicate granules) is measured by a compression test using a microcompression tester, and is the average value of five test results. More specifically, the powder of the present invention (aluminosilicate particles (preferably aluminosilicate granules)) is first used as a sample. A very small amount of this sample is scattered on the sample stage (lower pressure plate) of a microcompression tester MCT-510 (manufactured by Shimadzu Corporation), and a compression test is performed on each sample particle to determine its breaking strength. Typically, the average value of five test results (breaking strength) is used as the breaking strength of the powder. The breaking strength is calculated by measuring the diameters of each sample particle in the X and Y directions on the sample stage, taking the average value as the particle size of each sample particle, and using the following formula (1). (1) Cs = 2.48 × P / (πd 2 ) In equation (1), Cs is the breaking strength (unit: MPa), P is the breaking test force (unit: N), and d is the diameter of the sample particle (unit: mm).

[0049] It is also preferable that the powder of the present invention has a hydrated breaking strength of 80% or more of the above-mentioned breaking strength when the aluminosilicate particles (preferably aluminosilicate granules) are hydrated by immersion in pure water for 24 hours. The hydrated breaking strength may be the same value as the above-mentioned breaking strength, i.e., 100%. When the hydrated breaking strength is excellent, the pore structure is easily maintained even in applications where the powder comes into contact with aqueous solutions, etc., which is preferable. The wet breaking strength is measured in the same manner as in the above method for measuring breaking strength, except that the sample is aluminosilicate particles (preferably aluminosilicate granules) that have been immersed in pure water for 24 hours to become hydrated.

[0050] [Powder uses] The powder of the present invention can be used in a wide variety of applications. In addition to the applications described above, examples of applications include, but are not limited to, cosmetics, coloring materials, precision polishing particles, magnetic materials, deodorizing agents, antibacterial agents, water purification agents, food, fermentation, pharmaceuticals, and artificial enzymes. The powder of the present invention is also suitable as a filler or coating material that imparts properties such as light weight, heat insulation, or sound absorption.

[0051] [Powder manufacturing method] The powder manufacturing method of the present invention involves calcining a powder containing aluminosilicate particles at 600 to 900°C to obtain calcined powder, and then subjecting the calcined powder to an acid treatment. The aluminosilicate particles include nanotube particles, and the molar ratio of the SiO2 content to the Al2O3 content is less than 2.1. The molar ratio of the SiO2 content to the Al2O3 content is often 1.8 or more, and may be 1.9 or more. Hereinafter, the process of obtaining fired powder by firing at 600 to 900°C will also be referred to as the "firing process", and the process of subjecting the fired powder to acid treatment will also be referred to as the "acid treatment process". Hereinafter, the powder containing aluminosilicate particles to be subjected to the firing step will also be referred to as "unfired powder." Furthermore, the aluminosilicate particles containing nanotube particles contained in the unfired powder will also be referred to as "unfired particles." The following describes preferred and optional procedures for producing the powder of the present invention.

[0052] The unsintered particles preferably contain nanotube particles as primary particles. The method for obtaining unsintered powder (unsintered particles) is not particularly limited. For example, unsintered powder may be obtained by crushing or pulverizing powder containing nanotube-shaped particles to an appropriate size. Alternatively, the solvent component may be removed from a slurry containing nanotube-shaped particles by drying to obtain a molded body, and the molded body may be crushed to an appropriate size to obtain unsintered powder, or the slurry may be dried to obtain unsintered powder. Alternatively, unsintered powder (unsintered granules) may be obtained by spray-drying a slurry containing nanotube-shaped particles. Alternatively, unsintered powder (unsintered granules) may be obtained by subjecting a slurry containing nanotube-shaped particles to fluidized bed drying or freeze-drying. In particular, it is preferable to perform a spray drying process on a slurry containing nanotube particles to obtain an unsintered powder, since this makes it easier to obtain the powder of the present invention having second pores corresponding to the interparticle voids of the nanotube particles described above. That is, the method for producing a powder of the present invention preferably includes a spray drying step in which a slurry containing nanotube particles is subjected to a spray drying treatment to obtain an unsintered powder. The nanotube particles preferably include halloysite nanotube particles. Note that the spray drying step described below is an embodiment in which the nanotube particles include halloysite nanotube particles.

[0053] The spray drying process includes a slurry preparation process for obtaining a slurry containing nanotube particles, and a powder preparation process for carrying out spray drying. In the slurry preparation step, for example, a slurry containing water and nanotube particles (halloysite nanotube particles) is obtained. The powder preparation step may be, for example, a step of spray-drying the slurry prepared in the slurry preparation step to obtain a powder. The method for preparing powder from the slurry is not limited to spray drying, and may be, for example, fluidized bed drying (ball-containing fluidized bed drying). Suitable methods for obtaining the unsintered powder include, for example, the methods described in paragraphs

[0011] to

[0029] of WO 2018 / 079556.

[0054] By adjusting the procedure and conditions for obtaining the unsintered powder, the particle size of the unsintered granules in the obtained unsintered powder can be adjusted. The average particle size of the unsintered powder is preferably 0.5 to 200 μm. The average particle size of the unsintered powder can be adjusted depending on the purpose, and methods for adjusting the average particle size include crushing and pulverization.

[0055] <Firing process> In the powder production method of the present invention, the unsintered powder is fired at 600 to 900° C. to obtain a fired powder. It is believed that firing at such a firing temperature modifies the nanotube particles contained in the aluminosilicate particles. When halloysite nanotube particles are used as the nanotube particles, it is believed that the crystal water in the halloysite nanotube particles is released and they change into metahalloysite nanotube particles. In this case, no change in the shape of the tubes is observed in many cases. Furthermore, when aluminosilicate granules are used as the aluminosilicate particles, firing at such a firing temperature increases the strength and makes it easier to maintain the granular structure before firing.

[0056] The above-mentioned slurry may contain a surfactant to adjust the dispersion state and viscosity, and may also contain template particles made of an organic material to form pores with a diameter of more than 200 nm. When the slurry contains the above-mentioned components, the above-mentioned components may remain in the uncalcined powder obtained by spray drying or the like. However, these organic substances can be removed by calcining the powder in an air atmosphere or the like.

[0057] The calcination temperature can be adjusted appropriately depending on the desired physical properties of the resulting powder. From the viewpoint of obtaining a powder with a larger SiO2 / Al2O3 ratio, the calcination temperature is preferably 800 to 900°C. By setting the calcination temperature within the above range, Al2O3 is easily leached in the subsequent acid treatment step, and the SiO2 / Al2O3 ratio tends to increase (see Examples below). Furthermore, the above physical properties can be controlled by the degree of SiO2 / Al2O3 (see Examples below).

[0058] The firing time is not particularly limited, and is, for example, 0.5 to 4 hours, preferably 1 to 2 hours. The firing atmosphere is not particularly limited, and examples thereof include air and nitrogen atmospheres, with air being preferred. Alternatively, the firing atmosphere may be an atmosphere with a higher oxygen content than air. As described above, when the firing atmosphere is air or an atmosphere with a higher oxygen content than air, it is easy to remove template particles composed of surfactants and organic substances. The average particle size of the fired powder is preferably 0.5 to 200 μm. The average particle size of the fired powder can be adjusted depending on the purpose, and methods for adjusting the average particle size include crushing and pulverization.

[0059] <Acid treatment process> In the powder production method of the present invention, the calcined powder is subjected to an acid treatment. When the calcined powder is subjected to acid treatment, the Al2O3 component is primarily leached from the aluminosilicate particles containing nanotube-shaped particles, resulting in the powder of the present invention (a powder containing aluminosilicate particles with a molar ratio of SiO2 content to Al2O3 content of 2.1 or more). The acid treatment refers to a process in which the calcined powder is brought into contact with an acid treatment solution. Here, the external shape of the nanotube shape is hardly changed by the acid treatment (see Figures 1 and 2). The inventors have found that Al2O3 is less likely to be leached even when aluminosilicate particles containing nanotube-shaped particles are subjected to an acid treatment step without undergoing a calcination step. The mechanism behind this is not entirely clear, but is speculated as follows. That is, although nanotube-shaped particles (halloysite nanotube particles) are relatively stable against acid, when they undergo a calcination step, the water of crystallization in the nanotube-shaped particles (halloysite nanotube particles) is eliminated, causing them to become amorphous. At this time, although no change in the shape of the nanotube-shaped particles as a whole is observed, the coordination number of Al changes, and in particular, five-coordinated Al is generated, which is thought to make the Al component more susceptible to leaching by acid. To verify the above hypothesis, measurements were carried out using solid-state nuclear magnetic resonance (Solid-state Nuclear Magnetic Resonance) ( 27 Al (DDMAS method), it was confirmed that a peak corresponding to five-coordinated Al appeared in the aluminosilicate particles after the calcination process, which was hardly observed before the calcination process. Furthermore, it was confirmed that the peak corresponding to the above-mentioned five-coordinated Al preferentially decreased after the acid treatment process.

[0060] The acid treatment liquid used in the acid treatment is preferably a liquid containing water and an acidic component, that is, an acidic aqueous solution. The acidic treatment liquid may be any conventionally known aqueous acid solution, including inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as oxalic acid and acetic acid. The acidic treatment liquid may contain two or more acids. That is, the acidic treatment liquid may be a mixed acid. The acid concentration in the acid treatment solution is not particularly limited as long as the target amount of Al2O3 is leached, but from the viewpoint of shortening the acid treatment time, it is preferably 0.1 mol / L or more, more preferably 1.0 mol / L or more, and even more preferably 2.0 mol / L or more. The upper limit of the acid concentration in the acid treatment solution is not particularly limited, but may be, for example, 12.0 mol / L or less. The type of acid contained in the acidic treatment solution can be appropriately selected depending on the desired physical properties, cost, and the like. In addition, it is preferable that the equipment for carrying out the acid treatment is made of a material that is corrosion-resistant to the acid contained in the acid treatment solution, for the parts that may come into contact with the acid treatment solution.

[0061] In the acid treatment, an example of a method for contacting the calcined powder with the acid treatment solution is to place the calcined powder in the acid treatment solution and stir the acid treatment solution. In the acid treatment, it is preferable that the calcined powder be dispersed in the acid treatment solution in order to more uniformly leaching Al2O3 from the aluminosilicate particles. The stirring method is not particularly limited, and for example, the acid treatment solution and the calcined powder may be placed in a tank equipped with stirring blades and stirred. Stirring makes it easy to maintain the dispersion state of the calcined powder in the acid treatment solution. Alternatively, the dispersion state of the calcined powder may be maintained by shaking. The ratio of the mass of the acid treatment solution to the mass of the calcined powder can be set as appropriate, but may be, for example, 5 to 100, and preferably 10 to 50. When the ratio is large, leaching of Al2O3 tends to be more easily promoted. The temperature of the acid treatment solution during acid treatment can be set as appropriate, for example, from 10 to 100° C., and preferably from 20 to 90° C. Increasing the temperature of the acid treatment solution during acid treatment tends to facilitate leaching of Al2O3. The acid treatment time can be adjusted appropriately depending on the desired SiO2 / Al2O3 and the desired physical properties described above, as well as the type of acid treatment liquid used, the ratio of the mass of the acid treatment liquid to the mass of the fired powder, the temperature of the acid treatment liquid, etc., but is, for example, 10 minutes to 48 hours, and preferably 30 minutes to 12 hours. The acid treatment step is preferably carried out in an apparatus equipped with a cooler for cooling and refluxing the evaporated acid treatment liquid.

[0062] In the acid treatment step, impurity components other than Al2O3 contained in the aluminosilicate particles (for example, Fe2O3, CaO, MgO, K2O, and Na2O) may be leached.

[0063] When aluminosilicate granules containing halloysite nanotube particles are used as the unsintered granules contained in the unsintered powder used in the powder manufacturing method of the present invention, aluminosilicate granules containing acid-treated metahalloysite nanotube particles as primary particles are obtained through the firing step and the acid treatment step. As described above, the acid-treated metahalloysite nanotube particles often have third pores with a pore size of 8 nm or less. Surprisingly, even when halloysite nanotube particles are subjected to a calcination step and an acid treatment step to obtain acid-treated metahalloysite nanotube particles, the pores derived from the halloysite nanotube particles are maintained (see Examples below). Furthermore, in the powder production method of the present invention, the pores derived from the interparticle voids of the nanotube particles, which are confirmed before the calcination step and the acid treatment step, are maintained (see Examples below). That is, in the powder production method of the present invention, the first pores corresponding to the tube pores of the halloysite nanotube particles and the second pores derived from the interparticle voids of the nanotube particles, which are confirmed before the calcination step and the acid treatment step, are maintained.

[0064] <Cleaning process> The method for producing a powder of the present invention may include a step of washing the obtained powder (washing step). The washing step is preferably carried out between the acid treatment step and the post-calcination step described below, or between the acid treatment step and the drying step described below. The washing step makes it possible to remove the acid treatment solution in which Al2O3 has dissolved, and the like, from the obtained powder. The washing step is preferably a step of contacting the obtained powder with a washing liquid. Examples of the washing liquid include water. The water is preferably purified water (e.g., distilled water, ion-exchanged water, reverse osmosis water, etc.).

[0065] The method for contacting the obtained powder with the washing liquid may be the same as that for the acid treatment step. After contacting the powder with the washing liquid, the powder is separated from the washing liquid. The separation method is not particularly limited, and known methods can be applied, such as sedimentation separation and filtration separation. Sedimentation separation utilizes gravity or centrifugal force to separate the liquid and powder due to the difference in specific gravity. Filtration separation involves separating the powder from the liquid by trapping the powder in a filter or the like and passing the liquid through the filter. Filtration separation may be dead-end filtration or cross-flow filtration.

[0066] The washing step may be carried out repeatedly. For example, after the powder is separated from the washing liquid by the above method, the separated powder is again brought into contact with the washing liquid and the washing step is repeated. The washing step may be repeated, for example, until the conductivity of the filtrate reaches a predetermined level.

[0067] <Drying process> In the method for producing a powder of the present invention, it is preferable to perform a drying treatment on the obtained powder (for example, the powder obtained in the acid treatment step or the powder obtained in the washing step). The drying method is not particularly limited, and known methods such as static drying and fluidized drying can be applied. In addition, spray drying, fluidized bed drying, freeze drying, etc. may be applied to the powder-containing slurry. These methods can be applied even when solid-liquid separation of the slurry is difficult. Furthermore, according to these methods, powder can be obtained directly from the slurry. The drying temperature is usually 200°C or lower.

[0068] <Post-firing process> The method for producing a powder of the present invention may further include a step of calcining the obtained powder (for example, the powder obtained in the acid treatment step, the powder obtained in the washing step, or the powder obtained in the drying step) (post-calcination step). The specific firing method can be the same as that of the firing step described above. The firing temperature in the post-firing step is preferably more than 200° C. and not more than 1100° C., more preferably 300 to 1000° C. The preferred firing atmosphere is the same as that of the firing step described above. In the post-firing step, the physical properties of the powder described above can be adjusted by changing the firing temperature (see the examples below). For example, it has been found that increasing the temperature in the post-firing step tends to decrease the values ​​of the physical properties described above. Therefore, by adjusting the conditions of each step and the firing temperature in the post-firing step, the physical properties described above can be controlled to desired values. Furthermore, post-firing can impart heat resistance up to the temperature range in which the post-firing is performed. For example, if the post-firing temperature is set higher than the environment in which the powder of the present invention is used, it is expected that the powder of the present invention will be less likely to denature when used and will have improved durability. Therefore, it is also preferable to select the post-firing temperature depending on the environment in which the powder of the present invention will be used.

[0069] Although the physical properties change as described above when the post-calcination process is performed, the pores (first pores) derived from the nanotube particles, the pores (second pores) derived from the interparticle voids of the nanotube particles, and the third pores with a pore diameter of 8 nm or less possessed by the acid-treated metahalloysite nanotube particles are often maintained (see the examples below).

[0070] In the powder production method of the present invention, it is also preferable to mix particles (template particles) of a material that will disappear in the calcination or acid treatment step with the slurry used in the spray drying step. When the slurry containing the template particles is subjected to the spray drying step, aluminosilicate granules containing template particles and nanotube-shaped particles are obtained. When the powder containing such aluminosilicate granules is subjected to the calcination and acid treatment steps, the template particles are removed, and pores corresponding to the shape of the template particles (e.g., pores with a diameter of more than 200 nm) are generated. By adjusting the size, shape, and amount of the template particles, as well as the spray drying conditions, it is possible to generate pores of the desired shape (e.g., pores with a diameter of more than 200 nm). Template particles of materials that disappear during the firing step are not particularly limited, but examples thereof include resin particles, carbon particles, etc. Template particles of materials that disappear during the acid treatment step are not particularly limited, but examples thereof include magnesium oxide particles, calcium carbonate particles, zinc oxide particles, etc. [Example]

[0071] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0072] [Unfired powder] Unsintered powder to be subjected to the firing step was obtained by the following procedure.

[0073] <Raw material halloysite> As the raw material halloysite, halloysite manufactured by APPLIED MINERALS (product name: DRAGONITE-HP) was used.

[0074] <Slurrying> Raw halloysite, water, and anionic polymer surfactant (Poise 532A, Kao Corporation) were placed in a high-speed mixer (Ultra Homo Mixer UHM-20 (20 liters), manufactured by Nippon Seiki Seisakusho Co., Ltd.) and treated at 10,000 rpm for 10 minutes to obtain a slurry (solids concentration: 40% by mass) in which the raw halloysite was dispersed in water. The content of the anionic polymer surfactant was 1.9% by mass relative to the total solids content of the slurry.

[0075] <Centrifugation> The slurry was allowed to settle naturally for two hours to remove coarse particles, and the resulting slurry was then centrifuged at a centrifugal force of 2500 G for 10 minutes using a centrifuge (Kubota Shoji Co., Ltd., High-Speed, Large-Capacity Refrigerated Centrifuge Model 7000) to separate the slurry into a sedimented phase containing impurities such as quartz and coarse particles, and a dispersed phase containing suspended nanotubes.

[0076] <Spray drying> A dispersed phase (slurry) containing nanotubes and having a solid content of 25.1% was spray-dried using a spray dryer to obtain a powder (unfired powder) of aluminosilicate particles (aluminosilicate granules) having an average particle size of 6.0 μm. The spray dryer used was an L-8i spray dryer manufactured by Okawara Kakoki Co., Ltd. The slurry was supplied in fixed amounts into the drying chamber using a pump, and the slurry was atomized (sprayed) and dried. The contact method between the hot air and the sprayed droplets was a parallel flow type, with both the hot air and the sprayed droplets flowing downward. The spray drying conditions are as follows: Atomization method: Four-fluid nozzle method Spray air pressure: 0.20 MPa Slurry supply rate: 2.6 kg / h ·Inlet temperature: 190℃ ·Outlet temperature: 88℃ The unsintered powder was a powder containing aluminosilicate granules containing halloysite nanotube particles as primary particles. In the following examples, the unsintered powder obtained by the above procedure (also referred to as "unsintered powder 1") was used as the unsintered powder.

[0077] [Relationship between firing temperature in the firing process and the amount of Al2O3 leaching] Unsintered powder 1 was fired at each temperature shown in Table 1 below to obtain fired powder (firing step). For firing, an electric furnace with a siliconite heating element was used, and the temperature was raised at a rate of 4°C / min, and the temperature shown in Table 1 below was maintained for 1 hour, followed by furnace cooling. The XRD charts of each calcined powder and uncalcined powder are shown in Figure 3. In Figure 3, the uncalcined powder is described as "uncalcined," and each calcined powder is described by its calcination temperature. As can be seen in Figure 3, only the crystalline phase of halloysite was observed in the unsintered powder. When fired at 600°C, the half-width of each diffraction peak increased, indicating low crystallinity. At 800°C and 900°C, almost no diffraction peaks were observed, indicating amorphousness. On the other hand, at 950°C and 1000°C, it can be seen that γ-Al2O3 was formed.

[0078] The measurement conditions for obtaining the XRD chart shown in FIG. 3 are as follows: Equipment used: X-ray diffraction analyzer D8ADVANCE (manufactured by BRUKER) Measurement X-ray: CuKα Tube voltage: 35kV ·Tube current: 40mA ·Optical system: Concentration method Detector: One-dimensional semiconductor detector Scan range: 2~70° Scan step: 0.021° Scan speed: 4deg / min

[0079] The SiO2, Al2O3, and Fe2O3 contents of each calcined powder were determined using the XRF method described above, and the SiO2 / Al2O3 ratio was calculated using the method described above. The SiO2, Al2O3, and Fe2O3 contents are normalized to 100% as the value excluding ignition loss, which corresponds to water content. Furthermore, the BET specific surface area and total pore volume of each of the obtained fired powders were measured. The detailed measurement conditions are as described below. The measurement results of the calcined powder before the acid treatment are shown in Table 1.

[0080] Next, each of the fired powders and unfired powders shown in Table 1 was subjected to an acid treatment. For the acid treatment, hydrochloric acid (acid treatment solution) of the following concentration was used. The acid treatment was carried out by placing the calcined or uncalcined powder and the acid treatment solution in a glass beaker and stirring with a PTFE stirring blade. The acid treatment was carried out by heating the glass beaker with a mantle heater and controlling the liquid temperature to the following temperature. After the acid treatment, solid-liquid separation was performed by suction filtration, and then a process of dispersing in ion-exchanged water and a process of solid-liquid separation (washing process) were repeatedly performed using ion-exchanged water until the conductivity of the filtrate reached the value specified below. After the washing step, the product was dried at 110°C to obtain a powder. The obtained powders were subjected to the same measurements as for the sintered powders. The measurement results for the obtained powders are shown in Table 2.

[0081] <Acid treatment conditions> Acid treatment solution: 2 mol / L hydrochloric acid Liquid temperature: 60℃ Duration: 2 hours Ratio of the mass of acid treatment solution to the mass of calcined or uncalcined powder (acid treatment solution / powder): 25 Filtrate conductivity at the end of washing: 1mS / m

[0082] [Table 1]

[0083] [Table 2]

[0084] The results in Table 2 show that when uncalcined powder was subjected to acid treatment, the SiO2 / Al2O3 ratio did not change. In addition, there was little change in the BET specific surface area and total pore volume before and after acid treatment. On the other hand, the powder obtained by calcining at 600 to 900°C and then acid treatment (powder of the present invention) showed an increase in SiO2 / Al2O3. At the same time, it was confirmed that the BET specific surface area and total pore volume also increased significantly. On the other hand, the SiO2 / Al2O3 ratio did not change in the powders obtained by calcining at 950°C and 1000°C and then acid treatment. In addition, the BET specific surface area and total pore volume also showed little change before and after the acid treatment. It was also confirmed that the powder obtained by firing at 600 to 900°C and then acid treatment had a lower Fe2O3 content.

[0085] If the mass loss due to the acid treatment is taken as the amount of Al2O3 eluted into the acid treatment solution, it was confirmed that the amount of Al2O3 loss calculated from the Al2O3 content in each powder measured by XRF roughly coincided with the amount of Al2O3 eluted. Therefore, it is believed that the Al2O3 component is mainly leached in the acid treatment.

[0086] <Nitrogen adsorption isotherm> In the present invention, nitrogen adsorption isotherms were obtained under the following conditions and procedures, and various analyses were carried out. First, the powder was pretreated, and then the nitrogen adsorption and desorption isotherms were measured using a constant volume method under the following conditions: The equilibrium waiting time is the waiting time after the adsorption equilibrium state is reached. ·Adsorption temperature: 77K Nitrogen cross section: 0.162nm 2 Saturated vapor pressure: Actual measurement Equilibration wait time: Until the pressure change over 500 seconds is within 0.2% of the pressure gauge reading Pretreatment device: BELPREP-vacII (Microtrack, manufactured by BEL) Measurement device: BELSORP-MaxII (Microtrack BEL) Analysis software: BELMaster Version 6.4.0.0 (Microtrack, BELMaster) For samples fired at temperatures above 500°C, pretreatment involved vacuum degassing at 300°C for 8 hours, while for samples fired at temperatures below 500°C, pretreatment involved vacuum degassing at 170°C for 3.5 hours.

[0087] BET specific surface area [m 2 / g] was determined by applying the BET method to the nitrogen adsorption isotherm. Total pore volume [cm 3 / g] was determined by the method described above. The pore volume distribution from about 2.6 nm to about 200 nm was determined from the nitrogen adsorption isotherm by applying the BJH method using the FHH standard curve.

[0088] [Relationship between acid treatment conditions and amount of Al2O3 leached] The calcined powder (SiO2 / Al2O3=2.0) obtained by calcining at a temperature of 900°C in the calcination step described above was subjected to acid treatment under different acid treatment conditions. Specifically, the acid treatment was performed by changing the concentration of hydrochloric acid in the acid treatment solution and the temperature of the acid treatment solution so as to correspond to the plots in Fig. 4. The treatment time was 2 hours, and the mass ratio of the acid treatment solution to the mass of the fired powder was 25, and the acid treatment was performed in the same manner as described above. FIG. 4 is a graph showing the relationship between the acid treatment temperature and SiO2 / Al2O3 after the acid treatment.

[0089] As shown in Figure 4, it was confirmed that the SiO2 / Al2O3 ratio in the obtained powder can be adjusted by adjusting the acid treatment conditions. Furthermore, as shown in the results below, each physical property can be adjusted by adjusting the SiO2 / Al2O3 ratio.

[0090] [Relationship between SiO2 / Al2O3 and BET specific surface area] As described above, the SiO2 / Al2O3 ratio can be controlled by adjusting the acid treatment conditions. That is, by adjusting various conditions in the acid treatment, such as the acid concentration and temperature, the SiO2 / Al2O3 ratio of the resulting powder can be controlled. It can also be understood that the SiO2 / Al2O3 ratio of the resulting powder can be controlled by the acid treatment time and the mass ratio of the acid treatment solution to the mass of the calcined powder. Figure 5 shows the relationship between the SiO2 / Al2O3 ratio and the BET specific surface area of ​​powders prepared by adjusting the acid treatment conditions for the sintered powder (SiO2 / Al2O3 = 2.0) prepared at a sintering temperature of 900°C in the above-mentioned sintering process. The powder data shown in Figure 5 was obtained by measuring the powder obtained by adjusting the SiO2 / Al2O3 ratio by the acid treatment conditions, and then washing and drying (110°C) in the same manner as above.

[0091] From the results shown in Fig. 5, it can be seen that the BET specific surface area changes according to SiO2 / Al2O3. That is, it can be understood that the BET specific surface area can be adjusted by adjusting SiO2 / Al2O3.

[0092] [Relationship between post-firing and each physical property] <BET specific surface area> As described above, first, for the fired powder (SiO2 / Al2O3 = 2.0) with the firing temperature in the above firing process set to 900 °C, the acid treatment conditions were changed to perform acid treatment, and a powder with adjusted SiO2 / Al2O3 was obtained. For each powder with adjusted SiO2 / Al2O3, further firing was performed (post-firing process), and the BET specific surface area and total pore volume of the obtained powder were measured. The firing temperature in the post-firing process was 500, 900, 1000, and 1100 °C, and the holding time at each temperature was 1 hour. Fig. 6 shows the results of the BET specific surface area when adjusting SiO2 / Al2O3 and changing the firing temperature in the post-firing process. In addition, Fig. 7 shows the results of the total pore volume when adjusting SiO2 / Al2O3 and changing the firing temperature in the post-firing process. The results of the powder dried at 110 °C are also shown simultaneously assuming that the temperature of the post-firing process is 110 °C.

[0093] As can be seen from the results of Fig. 6 and Fig. 7, it was confirmed that the BET specific surface area and total pore volume can also be controlled by the firing temperature in the post-firing process. In addition, in the post-firing process, firing is performed at 500 to 1000 °C, and it can be seen that a certain BET specific surface area and total pore volume are maintained even when firing is performed at each temperature. Then, it is expected that the pore structure of the powder of the present invention will be maintained even in the temperature range corresponding to the post-firing process. Comparing powder dried at 110°C with powder calcined at 500°C, it can be seen that the BET specific surface area and total pore volume change very little when calcined at 500°C. On the other hand, when post-calcination is performed at 900°C or higher, the BET specific surface area and total pore volume tend to decrease, but the higher the SiO2 / Al2O3 ratio, the smaller the decrease, and it can be seen that the higher the SiO2 / Al2O3 ratio, the easier it is to maintain the pore structure (higher heat resistance). Therefore, the BET specific surface area and total pore volume of the powder of the present invention can be controlled by adjusting the calcination temperature in the calcination step, the acid treatment conditions, and the calcination temperature in the post-calcination step, and it is believed that the powder is particularly suitable for use as a catalyst, catalyst support, adsorbent, etc. Furthermore, the powder of the present invention maintains its pore structure even in high-temperature environments, and therefore can withstand use in high-temperature environments, making it useful as a catalyst and catalyst support for reactions in high-temperature environments.

[0094] <Pore size distribution (BJH method)> Of the powders that had undergone the above post-calcination, the powders that had been post-calcined at 500°C and the powders that had been post-calcined at 900°C were analyzed for pore size volume distribution using the BJH method. The results are shown in Figures 8 and 9. The results for the powders that had been calcined at 900°C (SiO2 / Al2O3 = 2.0) before the acid treatment are also shown in each figure.

[0095] 8 and 9, it was confirmed that the obtained powder had pores with diameters of more than 8 nm and not more than 200 nm. Furthermore, the results in Fig. 8 and 9 suggest that there are two types of pores in the above region. SEM images of the powder (SiO2 / Al2O3=2.0) calcined at 900°C before acid treatment are shown in Figures 10 and 11. SEM images of the powder (SiO2 / Al2O3=13.7) calcined at 900°C after acid treatment are shown in Figures 12 and 13. Figure 11 is an observation image at a higher magnification than Figure 10, and Figure 13 is an observation image at a higher magnification than Figure 12. The above SEM observation images were acquired using a Sigma 500 manufactured by Carl Zeiss Microscopy Ltd. 10 and 11 show that the calcined powder before acid treatment contains aluminosilicate granules formed by aggregations of metahalloysite nanotube particles. Therefore, the peaks in the 10 to 20 nm region seen in Figures 8 and 9 are thought to represent pores corresponding to the tube pores of the metahalloysite nanotube particles, and the peaks in the region over 20 nm are thought to represent peaks corresponding to the voids between the metahalloysite nanotube particles. Furthermore, comparing the SEM observation images in Figures 10 and 11 with those in Figures 12 and 13, it can be said that there is no change in shape due to the firing process, acid treatment process, and post-firing process. Therefore, even in the powder (SiO2 / Al2O3=13.7) that was post-firing at 900°C, the two peaks seen in Figures 8 and 9 are thought to be the peak corresponding to the pores corresponding to the tube pores of the nanotube-like particles (acid-treated metahalloysite nanotube particles) and the peak corresponding to the interparticle voids of the nanotube-like particles (acid-treated metahalloysite nanotube particles), respectively.

[0096] Furthermore, when powders with SiO2 / Al2O3 ratios higher than 13.7 were also observed with an SEM, it was found that there was no change in the shape of the nanotube particles, as shown in Figures 12 and 13.

[0097] The amount of pores (cm) corresponding to the above two peaks 3 8 and 9, it can be seen that the pore volume per mass cm ( / g) tends to increase with an increase in the SiO2 / Al2O3 molar ratio. This is thought to be due to a decrease in the true density of the nanotube particles caused by a decrease in the amount of Al2O3 (an increase in the amount of SiO2), since there is no change in the appearance of the nanotube particles before and after acid treatment. In other words, the pore volume cm (cm) per mass 3It is thought that the pores before the acid treatment have not changed. Furthermore, the rise from around 3 nm to the small pore diameter side seen in the samples after acid treatment in FIGS. 8 and 9 is thought to suggest the presence of micropores.

[0098] <Micropore volume> The powders obtained by acid treatment and those that were post-calcined, as shown in Table 2 below, were analyzed using t-plots to calculate the micropore volume of each below 2 nm. The Harkins-Jura-BEL.t standard curve from Microtrack-Bell was used to calculate the micropore volume. The results are shown in Table 2. Note that no micropores were observed in the powder calcined at 900°C (SiO2 / Al2O3 = 2.0) that was not acid treated. The t-plot analysis was performed using nitrogen adsorption isotherms. The acid-treated powder (110°C) was degassed in vacuum at 170°C for 3.5 hours, while the other post-calcined powders (500°C and 900°C) were degassed in vacuum at 300°C for 8 hours.

[0099] [Table 3]

[0100] The results shown in Table 3 confirm that the acid treatment results in a micropore volume, that is, the formation of micropores.

[0101] <Pore size distribution (GCMC method)> Of the powders that were post-sintered, the pore size area distribution was analyzed by GCMC for the powders that were post-sintered at 500°C and the powders that were post-sintered at 900°C. The results are shown in Figures 14 and 15. Data for the 900°C-sintered powder (SiO2 / Al2O3 = 2.0) that was not acid-treated is also shown in each figure. Note that the results are offset in Figures 14 and 15. The analysis by the GCMC method was carried out under the following conditions. The GCMC method, which enables consistent analysis from micropores to mesopores and macropores, performs simulations by determining parameters such as pore diameter, pore shape, adsorbed molecules, and adsorbent surface atoms. Analysis using the GCMC method was performed under the following conditions, which allowed the simulated adsorption isotherm to approximate the actual adsorption isotherm. Model (assumed pore shape): Pore ​​shape: Cylinder Surface elements: NSSO (kernel assuming the sample surface is non-uniform) PSD fitting (pore size distribution): Selected distribution function: No assumption ds (surface atomic size of adsorbent): 0.28 nm Def.pore size: Solid and Fluid Def.pore size (Pore size definition recommended by Microtrac-Bell Corporation. The actual molecular diameter is not a hard sphere, and the pore size is defined as the midpoint of the distance at which the adsorbate overlaps the surface atoms.)

[0102] 14 and 15, it was confirmed that acid treatment generates third pores with a pore size of 8 nm or less. The above analysis results correspond to the analysis results of the micropore volume. Therefore, it can be said that the powder of the present invention obtained by acid treatment according to the above procedure also has third pores with a pore size of 8 nm or less. 14, it can be seen that when post-baking is performed at 500°C, there are four types of third pores with a diameter of 8 nm or less: pores with a diameter of approximately 3 nm, pores with a diameter of approximately 2 nm, pores with a diameter of approximately 1 nm, and pores with a diameter of 1 nm or less. On the other hand, when post-baking is performed at 900°C, the results shown in Fig. 15 indicate that when post-baking is performed, there are four types of third pores with a diameter of 8 nm or less: pores with a diameter of approximately 3 nm, pores with a diameter of approximately 2 nm, and some pores with a diameter of approximately 1 nm, but no pores with a diameter of 1 nm or less. Therefore, it was shown that the pore size distribution as described above can be controlled by the post-calcination temperature.

[0103] <Water vapor adsorption> In the present invention, a water vapor adsorption isotherm was obtained under the following conditions and procedures, and various analyses were carried out. First, the powder was pretreated (vacuum degassing at 300°C for 8 hours), and then the adsorption / desorption isotherm with water vapor was measured using a constant volume method under the following conditions: The equilibrium waiting time is the waiting time after the adsorption equilibrium state is reached. ·Adsorption temperature: 298.15K (25℃) ·Adsorbate: Pure water ·Saturated vapor pressure: 3.169kPa (25℃) Equilibration time: 500 seconds (time after pressure change reaches a predetermined value) Pretreatment device: BELPREP-vacII (Microtrack, manufactured by BEL) Measurement device: BELSORP-aqua3 (Microtrack BEL) Analysis software: BELMaster Version 6.4.0.0 (Microtrack, BELMaster) Of the powders that were post-calcined, water vapor adsorption isotherms were obtained for the powders that were post-calcined at 500°C and the powders that were post-calcined at 900°C. The results are shown in Figures 16 and 17. Data for the 900°C-calcined powder (SiO2 / Al2O3 = 2.0) that was not acid-treated is also shown in each figure. The amount of water vapor adsorbed at a relative pressure of 0.9 is summarized in Table 4 below. 3 (STP) / g) is the amount of water vapor adsorption per 1 g of powder, converted into the gas volume at 0°C and 101.325 kPa. The amount of water vapor adsorption at a relative pressure of 0.9 shown in Table 4 was calculated by linear interpolation from two measurement points before and after the relative pressure of 0.9.

[0104] [Table 4]

[0105] From the results shown in FIGS. 16 and 17 and Table 4, it was confirmed that the powder of the present invention is excellent in the amount of water adsorption at a relative pressure of 0.9. Furthermore, in Figure 16, the slope of the amount of water adsorbed against the relative pressure is large in the relative pressure range of about 0.3 to 0.5, and in Figure 17, the slope is large in the relative pressure range of about 0.4 to 0.6. From this, it is considered that the material is useful as a humidity control material in each relative pressure range. Furthermore, it was confirmed from the results shown in FIGS. 16 and 17 and Table 3 that the water adsorption characteristics change depending on the SiO2 / Al2O3 and post-baking temperature. Furthermore, since water molecules are thought to preferentially adsorb to hydrophilic sites, it is speculated that the hydrophilic silanol groups (Si-OH) generated upon desorption of Al are influencing this.

[0106] <Toluene vapor adsorption> Of the powders that were post-calcined, toluene vapor adsorption isotherms were obtained for the powders that were post-calcined at 500°C and the powders that were post-calcined at 900°C. The results are shown in Figures 18 and 19. Data for the 900°C-calcined powder (SiO2 / Al2O3 = 2.0) that was not acid-treated is also shown in each figure. The toluene vapor adsorption isotherm was obtained under the following conditions and procedures, and various analyses were carried out. First, the powder was pretreated (vacuum degassing at 300°C for 8 hours), and then the adsorption / desorption isotherm with toluene vapor was measured using a constant volume method under the following conditions: The equilibrium waiting time is the waiting time after the adsorption equilibrium state is reached. ·Adsorption temperature: 298.15K (25℃) Adsorbate: Toluene ·Saturated vapor pressure: 3.822kPa (25℃) Equilibration wait time: Pressure change within 0.2% of pressure gauge reading over 500 seconds Pretreatment device: BELPREP-vacII (Microtrack, manufactured by BEL) Measurement device: BELSORP-MaxII (Microtrack BEL) Analysis software: BELMaster Version 6.4.0.0 (Microtrack, BELMaster) Table 5 below summarizes the amount of toluene vapor adsorbed at a relative pressure of 0.9. 3 (STP) / g) is the amount of toluene adsorbed per 1 g of powder, converted into the gas volume at 0°C and 101.325 kPa.

[0107] [Table 5]

[0108] From the results shown in FIGS. 18 and 19 and Table 5, it was confirmed that the powder of the present invention was excellent in the amount of toluene vapor adsorbed at a relative pressure of 0.9. 18 and 19, the slope of the adsorption amount versus relative pressure is steep in the region where the relative pressure is around 0.1 (the region where adsorption in micropores is likely to occur), indicating that the powder of the present invention has the property of easily capturing low concentrations of toluene. Therefore, the powder of the present invention can be said to be useful as a catalyst, catalyst support, adsorbent, etc. involved in reactions of organic substances. Furthermore, it was confirmed from the results shown in FIGS. 18 and 19 and Table 5 that the toluene adsorption characteristics change depending on the SiO2 / Al2O3 and the post-calcination temperature. Furthermore, since toluene molecules are thought to preferentially adsorb to lipophilic sites, it is speculated that lipophilic siloxane bonds (Si-O-Si), which are thought to have been formed as a result of Al desorption and post-calcination, are influencing this.

[0109] In addition, solid-state nuclear magnetic resonance measurements ( 29 Si (CPMAS method) was performed, and it was found that before acid treatment (SiO2 / Al2O3 = 2.0), Q 2 =Si(OSi)2OH2, Q 3 =Si(OSi)3OH, and Q 4On the other hand, in the powders that were post-calcined at 500 °C after acid treatment (SiO2 / Al2O3 = 13.7 and 189.0), the peak corresponding to the above Q 2 , Q 3 and Q 4 A peak corresponding to The above results suggest that silanol groups and siloxane bonds were formed in the powders that were post-calcined at 500°C after acid treatment (SiO2 / Al2O3 = 13.7 and 189.0).

[0110] From the results of the water adsorption amount, the toluene adsorption amount, and the solid-state nuclear magnetic resonance measurement, it can be said that the powder of the present invention has hydrophilic adsorption sites and hydrophobic adsorption sites and is capable of capturing various molecules. Furthermore, since the powder of the present invention can be said to have unique microscopic spaces, it is thought that the powder of the present invention is also useful as a sustained-release material.

[0111] <Properties of solid acids> Of the powders that had undergone the above post-calcination, the powders that had been post-calcined at 500°C and the powders that had been post-calcined at 900°C were evaluated for their solid acid properties. For comparison, the same evaluation was also performed on the powder (SiO2 / Al2O3 = 2.0) that had been calcined at 900°C before the acid treatment. The results are shown in Table 6 below and in Figures 20 and 21. The evaluation was carried out by ammonia temperature programmed desorption (hereinafter also referred to as "NH3-TPD") under the following conditions. Equipment used: Fully automatic thermal desorption spectrometer (TPD-1-ATw, manufactured by Microtrack Bell) Sample amount: approx. 50 mg Measurement range: 100~800℃ Detector: Quadrupole mass spectrometer Detected fragment: m / z 16 The measurement program for NH3-TPD is as follows: Pretreatment: The temperature is raised from room temperature to 500°C at 10°C / min, held at 500°C for 1 hour, and then naturally cooled to 100°C over approximately 1.5 hours. During this time, He gas is circulated at 50 mL / min. NH3 adsorption: After reaching 100°C, maintain the temperature at 100°C for 30 minutes. During this time, He gas containing 0.5% by volume of NH3 gas is passed through at 100 mL / min. Desorption of excess NH3: The temperature is maintained at 100°C, and He gas is passed through at 50 mL / min for 30 minutes. Temperature-programmed desorption measurement: The temperature is raised from 100°C to 800°C at 10°C / min. During this time, He gas is passed through at 50 mL / min.

[0112] FIG. 20 shows the results of NH3-TPD measurement of powders post-sintered at 500°C, and FIG. 21 shows the results of NH3-TPD measurement of powders post-sintered at 900°C. A solid acid is a solid that has spots called acid sites on its surface that exhibit acidity. NH3 molecules adsorbed on acid sites with weak acid strength tend to desorb at low temperatures, while NH3 molecules adsorbed on acid sites with strong acid strength tend to desorb at high temperatures. The amount of NH3 molecules desorbed by heating corresponds to the amount of acid sites in the solid acid. From the results shown in FIGS. 20 and 21, it is apparent that there are peaks near 200° C. and near 500° C., suggesting the presence of weak and strong acid sites. Table 6 shows the analysis of the amount of NH3 molecules desorbed from the measurement results shown in Figures 20 and 21, and shows the total amount, the amount desorbed at 200°C or higher, the amount desorbed at 300°C or higher, and the amount desorbed at 400°C or higher.

[0113] [Table 6]

[0114] The results shown in Table 6 suggest that the powder of the present invention has a higher amount of desorption at high temperatures (e.g., 400°C or higher) than the calcined powder before acid treatment, suggesting the appearance of acid sites with strong acid strength. Also, since the total amount of desorption is higher than that of the calcined powder before acid treatment, it can be said that the powder of the present invention tends to have a higher amount of acid (number of acid sites). On the other hand, it was confirmed that the solid acidity and acid strength can be adjusted by adjusting the SiO2 / Al2O3 and post-calcination temperature. The powder of the present invention is also useful as a solid acid catalyst because it has strong acid sites from which NH molecules do not desorb even at 400°C. Furthermore, the powder of the present invention allows the amount of solid acid and acid strength (solid acid properties) to be adjusted according to the desired reaction.

[0115] <Catalytic properties> The catalytic properties were evaluated using powders with different SiO2 / Al2O3 ratios obtained by acid treatment and washing under various conditions and dried at 110°C, as well as powders obtained by post-calcining the dried powders at 500°C and at 900°C. For comparison, the catalytic properties were also evaluated using powders calcined before acid treatment (900°C calcination) and commercially available zeolite powder. Although the powder calcined at 900°C before acid treatment was not post-calcined, the results are listed in the 110°C column in Table 7 for convenience. The catalytic properties were evaluated by proceeding with a solid acid catalytic reaction according to the following procedure and evaluating the yield. First, a reaction solution was prepared by adding 0.5 mmol of glycerin tributyrate to 2.5 mL of methanol, and the solution was placed in a pressure-resistant glass reactor. To the reaction solution, 0.1 g of the catalyst sample was added, and the mixture was heated to 180° C. and stirred for 4 hours to cause the following transesterification reaction to proceed, thereby obtaining the target compound ((t) in the following formula).

[0116] [ka]

[0117] After stirring, the target compound was quantitatively determined by gas chromatography to determine the yield. The analytical conditions were as follows. The results are shown in Table 7. Analytical equipment: GC-2010 (Shimadzu Corporation) Column: Restek Rtx-5MS capillary column Column length: 30m ·Inner diameter: 0.25mm Film thickness: 0.25 μm

[0118] [Table 7]

[0119] The results shown in Table 7 confirm that the powder of the present invention has superior catalytic properties compared to the powder before the acid treatment. It was also confirmed that the powder of the present invention has high catalytic properties compared to commercially available zeolites. The reason why the powder of the present invention exhibits such excellent catalytic properties is believed to be that not only the properties of the solid acid but also the properties of the pore structure and surface properties are simultaneously involved. When the powder of the present invention is used as a catalyst for reactions other than those described above, the optimum physical properties may differ. As described above, the powder of the present invention can control various characteristics and physical properties, allowing the physical properties to be adjusted according to the intended application. The physical properties of the powder of the present invention can be controlled by the SiO2 / Al2O3 ratio, post-calcination temperature, etc., as described above.

[0120] <Methylene blue adsorption> The amount of methylene blue adsorbed was measured using the method described above for the powder that had been acid-treated, washed, and dried at 110°C, the powder that had been post-calcined at 500°C, and the powder that had been post-calcined at 900°C. The results are shown in Table 8 below. For comparison, the same measurement was carried out on powder fired at 900°C (SiO2 / Al2O3 = 2.0) before acid treatment, and the amount of methylene blue adsorbed was found to be 36.5 mg / g.

[0121] [Table 8]

[0122] The results shown in Table 8 confirm that the powder of the present invention has a large adsorption capacity for methylene blue and is useful as an adsorbent (e.g., a cation adsorbent), etc. Furthermore, since the powder of the present invention can adsorb dyes, it can be said to be useful as a dye or coloring material.

[0123] The powder of the present invention is a powder (novel spatial material) having a novel porous structure that simultaneously has pores derived from nanotubes (e.g., 10 to 20 nm) and micropores other than the pores derived from nanotubes (e.g., four types of pores of approximately 3 nm, approximately 2 nm, approximately 1 nm, and 1 nm or less). The powder of the present invention is not limited to the applications for which measurements were specifically performed in the examples, and can be used in a variety of applications, including, for example, the applications described above.

Claims

1. Al ２ O ３ SiO content ２ A powder containing aluminosilicate particles in which the molar ratio of the content of The powder, wherein the aluminosilicate particles comprise nanotube particles.

2. The powder according to claim 1 , wherein the aluminosilicate particles have pores with a pore size of more than 8 nm and not more than 200 nm.

3. The powder according to claim 2 , wherein the aluminosilicate particles have, as the pores, first pores derived from the nanotube particles and second pores different from the first pores.

4. The powder according to claim 1 , wherein the aluminosilicate particles have pores with a pore size of 8 nm or less.

5. 2. The powder according to claim 1, wherein the aluminosilicate particles have pores with a pore size of 8 nm or less and pores with a pore size of more than 8 nm and 200 nm or less.

6. 2. The powder according to claim 1, wherein the aluminosilicate particles have first pores derived from the nanotubular particles and having a pore diameter of more than 8 nm and not more than 200 nm, second pores different from the first pores and having a pore diameter of more than 8 nm and not more than 200 nm, and pores having a pore diameter of 8 nm or less.

7. BET specific surface area is 50m ２ The powder according to any one of claims 1 to 6, wherein the solubility is 1 / g or more.

8. The total pore volume is 0.40 cm ３ The powder according to any one of claims 1 to 6, wherein the solubility is 1 / g or more.

9. The volume of the micropores is 0.01 cm ３ The powder according to any one of claims 1 to 6, wherein the solubility is 1 / g or more.

10. The amount of water vapor adsorbed is 120 cm at a relative pressure of 0.

9. ３ The powder according to any one of claims 1 to 6, wherein the solubility is 1 / g or more.

11. The adsorption amount of toluene vapor is 40 cm at a relative pressure of 0.

9. ３ The powder according to any one of claims 1 to 6, wherein the solubility is 1 / g or more.

12. NH measured by thermal desorption spectroscopy at temperatures above 400°C ３ The powder according to any one of claims 1 to 6, wherein the amount of desorption is 4.0 µmol / g or more.

13. The powder according to any one of claims 1 to 6, wherein the amount of methylene blue adsorbed is 40 mg / g or more.

14. The powder according to any one of claims 1 to 6, having an average particle size of 0.5 to 200 µm.

15. A powder containing aluminosilicate particles is calcined at 600 to 900°C to obtain a calcined powder; A powder manufacturing method comprising: subjecting the calcined powder to an acid treatment; the aluminosilicate particles include nanotube particles; The aluminosilicate particles are Al ２ O ３ SiO content ２ The method for producing a powder, wherein the molar ratio of the content of is less than 2.1.

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