JP2010138021A - Porous silica particle and producing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide porous silica particles being useful as a carrier, having an interparticle gap structure inside and having highly uniform pore diameters. <P>SOLUTION: The porous silica particles having the interparticle gap structure inside, an average particle diameter (PD) of 0.5-50 μm and a specific surface area of 30-250 m<SP>2</SP>/g are satisfied with such three requirements (1)-(3) that (1) the range of a pore volume is 0.10-0.25 cc/g, (2) the range of a pore diameter (D1) corresponding to a peak value in a pore diameter distribution (wherein, X axis is pore diameter; and Y axis is the differentiated value of pore volume by pore diameter) is 2-50 nm and (3) the total volume of pores having a pore diameter range of (D1)×0.75-(D1)×1.25 nm is 80% or more of the total volume of the pores. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to porous silica particles useful as a support for catalysts or adsorbents. Specifically, the present invention relates to a porous silica particle comprising an aggregate of a large number of fine particles and having voids between the particles, and a method for producing the same.

  A technique for preparing an aggregate of fine particles by spray-drying silica fine particles is known. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 61-270201) discloses a colloid liquid containing primary particles having an average particle diameter of 250 nm or less. A technique for preparing inorganic silica particles having an average particle diameter of 1 to 20 μm by spray drying is disclosed.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-160907) discloses an inorganic material having an average particle diameter of 2 to 250 nm by further coating an oxide layer on a fine particle aggregate obtained by spray drying a colloidal solution. Spherical porous particles are disclosed which are composed of an aggregate of inorganic silica particles having an average particle diameter of 1 to 100 μm where silica particles are collected and an oxide-based layer covering the aggregate.
JP 61-270201 A JP 2002-160907 A

An object of the present invention is to provide porous silica particles that are useful as support particles and that have an interparticle void structure inside and have high uniformity in pore diameter.

The first invention of the present application is a porous silica particle having an interparticle void structure inside, the average particle diameter (PD) of the porous silica particle is 0.5 to 50 μm, and the specific surface area is 30 to 250 m. ² / g, and the porous silica particles satisfy the following requirements 1) to 3).
1) Range in which pore volume is 0.10 to 0.25 cc / g 2) Peak pore diameter in pore diameter distribution (X axis: pore diameter, Y axis: value obtained by differentiating pore volume by pore diameter) D1) is in the range of 2 to 50 nm 3) The total pore volume of pores having pore diameters in the range of (D1) × 0.75 to (D1) × 1.25 nm is 80% or more of the total pore volume

In the second invention of the present application, the porous silica particles have an average particle diameter (D) of 10 to 50 nm, a sphericity of 0.9 to 1, and a particle diameter variation coefficient (CV value) of 2 to 10%. The porous silica particles are characterized by being composed of spherical aggregates of spherical silica particles having a particle size distribution of a monodisperse phase in the range of the above.

A third invention of the present application is the porous silica particle, wherein a porosity of the porous silica particle is in a range of 5 to 50%.

A fourth invention of the present application is the porous silica particle, wherein a particle size distribution of the spherical silica fine particle indicates a monodispersed phase.

5th invention of this application is a manufacturing method of the porous silica particle containing each process of following (A), (B), and (C).
(A): A dispersion of spherical silica fine particles having an average particle size of 10 to 50 nm is subjected to centrifugal separation to separate coarse particles, and the particle size variation coefficient (CV value) is adjusted to a range of 2 to 10%. Step (B) for preparing a spherical silica fine particle dispersion having a monodispersed diameter distribution: A step of preparing a spherical silica fine particle aggregate by spraying a spray liquid containing the spherical silica fine particle dispersion treated in the previous step in an air stream. (C): A step of heat-treating the spherical silica fine particle aggregate obtained in the previous step within a temperature range of 150 to 600 ° C.

The sixth invention of the present application is characterized by performing the following steps (D), (E), and (F) following the steps (A), (B), and (C): Is a method for producing porous silica particles.
(D): Following the previous step, the spherical silica fine particle aggregate is dispersed in water and / or an organic solvent to prepare a dispersion of the spherical silica fine particle aggregate (E): the spherical silica prepared in the previous step The step of surface-treating the spherical silica fine particle aggregate by adding the following i) or ii) to the dispersion of the fine particle aggregate i) Acid or alkali ii) Acid or alkali and represented by the following general formula Organosilicon compound and / or partial hydrolyzate thereof General formula: R _n Si (OR ′) _4-n
[However, R and R ′ are hydrocarbon groups selected from an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a vinyl group or an acrylic group, and n is 0, 1, 2 or 3 Is an integer. ]
(F): Following the previous step, the spherical silica fine particle aggregate is separated from the dispersion of the spherical silica fine particle aggregate, dried, and then heated at 100 to 300 ° C. under atmospheric pressure or reduced pressure.

  7th invention of this application is a manufacturing method of the said porous silica particle characterized by the spray liquid used at the said (B) process containing a silicic acid liquid other than spherical silica fine particles.

  The eighth invention of the present application is a carrier particle comprising the porous silica particles.

  The porous silica particles according to the present invention have an interparticle void structure inside, and have particularly high pore diameter uniformity. For example, when a catalyst material made of metal fine particles is supported on carrier particles, the metal fine particles are aggregated, and the catalyst activity tends to be reduced due to aggregation. Since the porous silica particles of the present invention have high uniformity of pore diameter as described above, it can be said that such agglomeration of metal fine particles hardly occurs. In addition, since the porous silica particles of the present invention are sharply controlled in pore diameter, it is expected to be selectively supported according to the size of the catalyst material to be supported.

1. Porous silica particles The porous silica particles according to the present invention are porous silica particles having an interparticle void structure therein, and the average particle diameter (PD) of the porous silica particles is 0.5. A porous silica particle characterized by having a surface area of ˜50 μm, a specific surface area of 30 to 250 m ² / g, and the porous silica particles satisfy the requirements 1) to 3) below.
1) Range in which pore volume is 0.10 to 0.25 cc / g 2) Peak pore diameter in pore diameter distribution (X axis: pore diameter, Y axis: value obtained by differentiating pore volume by pore diameter) D1) is in the range of 2 to 50 nm 3) The total pore volume of pores having pore diameters in the range of (D1) × 0.75 to (D1) × 1.25 nm is 80% or more of the total pore volume

The interparticle void structure is usually constituted by self-assembly and / or self-assembly of particles, and the porous silica particles of the present invention have an average particle diameter of 10 to 50 nm and a sphericity of 0.9 to 0.9. The spherical aggregate is formed by agglomeration of spherical silica particles having a uniform particle diameter in the range of 1.
The inter-particle void structure of the porous silica particles according to the present invention has a pore diameter (D1) of a peak value particularly in a pore diameter distribution (X axis: pore diameter, Y axis: a value obtained by differentiating pore volume by pore diameter). The total pore volume of pores having a pore diameter within a range of 2 to 50 nm and further within a range of (D1) × 0.75 to (D1) × 1.25 nm is 80% or more of the total pore volume. It is something to take. This promotes the tendency of the catalyst or the like to be sufficiently dispersed and supported on the porous silica particles. Moreover, reaction selectivity can be imparted to the catalyst carrier on which the catalyst is supported. This is due to the fact that the shape of the particles forming the pores is spherical and the particle diameter is uniform, and the pores formed are also present in a dispersed state with a uniform pore diameter. It is guessed.

  About the average particle diameter of the porous silica particle which concerns on this invention, the range of 0.5-50 micrometers is preferable. According to the production method of the present invention described later, spherical and uniform porous silica particles can be obtained within this range. According to the production method of the present invention, it is not easy to prepare porous silica particles having an average particle diameter of less than 0.5 μm. When the average particle diameter exceeds 50 μm, irregular shapes are easily generated according to the production method of the present invention, which is not desirable. In addition, about the average particle diameter of a porous silica particle, the range of 5-30 micrometers is recommended suitably. The average particle diameter of the porous silica particles is measured by a centrifugal sedimentation method, and the specific measurement method is described in [1B] “Measurement method of average particle diameter by centrifugal sedimentation method” in Examples. I wrote.

About the specific surface area of the porous silica particle which concerns on this invention, the range of 30-250 m < ² > / g is preferable. When the specific surface area is less than 30 m ² / g, when used as a carrier, it is necessary to use a large amount of the carrier, which is economically disadvantageous. On the other hand, if the specific surface area exceeds 250 m ² / g, the reaction product may be re-adsorbed and the reaction efficiency may be lowered, and the strength of the spherical aggregate becomes insufficient, which is not preferable.

The porous silica particles according to the present invention have a pore volume in the range of 0.10 to 0.25 cc / g. When the pore volume is less than 0.10 cc / g, when used as a carrier, the amount of metal fine particles that act as a catalyst is reduced, so that it is necessary to use a large amount of carrier, economically. It is disadvantageous. When the pore volume exceeds 0.25 cc / g, the strength of the spherical aggregate becomes insufficient. A preferable range of the pore volume is 0.12 to 0.20 cc / g.
The pore volume can be determined by a constant volume gas adsorption method using nitrogen, and the pore distribution and pore diameter (peak value) can be determined by the BJH method.

In the porous silica particles according to the present invention, the interparticle void structure of the porous silica particles according to the present invention has a pore size distribution (X axis: pore diameter, Y axis: a value obtained by differentiating the pore volume with the pore diameter). The total pore volume of pores having a pore diameter (D1) having a peak value in the range of 2 to 50 nm and a pore diameter in the range of (D1) × 0.75 to (D1) × 1.25 nm. However, it is necessary to be 80% or more of the total pore volume.
When the pore diameter (D1) is less than 2 nm, it is not easy to ensure the necessary pore volume. When the pore diameter (D1) exceeds 25 nm, a decrease in particle strength may cause a practical problem. About the range of a pore diameter (D1), the range of 3-15 nm is desirably recommended.
When the total pore volume of pores having pore diameters in the range of (D1) × 0.75 to (D1) × 1.25 nm is less than 80% of the total pore volume, the pore diameter distribution is non-uniform In other words, the stress tends to concentrate on relatively large pores, and problems such as practically low strength are likely to occur. As a more preferable ratio of the total pore volume to the total pore volume, 85% or more is recommended.

The porous silica particles according to the present invention preferably have a porosity in the range of 5 to 50%. The porous silica particles of the present invention can exhibit excellent particle breaking strength even with a porosity in this range. If the porosity is less than 5%, the amount of the substance that can be supported becomes small, which is not practical. If the porosity exceeds 50%, the strength of the particles may not be maintained, which is not desirable. About the porosity, the range of 10 to 30% is desirably recommended.

Spherical aggregate The porous silica particle according to the present invention is composed of a spherical aggregate of spherical silica fine particles as described above. Here, the average particle diameter of the spherical silica fine particles is preferably in the range of 10 to 50 nm. When the average particle size is less than 10 nm, the particle size is too small, the pore volume due to the gaps between the inorganic silica fine particles is reduced, and the practicality of the supporting particles is reduced. When the average particle diameter exceeds 50 nm, the pore volume increases, but the bonding force between the fine particles is weak and it is difficult to obtain an aggregate of spherical silica fine particles. A more preferable average particle diameter of the spherical silica fine particles is in the range of 10 to 48 nm.

In the present application, the average particle diameter of the spherical silica fine particles means an average particle diameter measured by a dynamic light scattering method or an average particle diameter measured by an image analysis method.
The same applies to “spherical silica fine particles (a)” and “spherical silica fine particles (b)” described later. About the measuring method of the average particle diameter by the dynamic light scattering method, it described in [1A] "The measuring method of the average particle diameter by the dynamic light scattering method" of an Example. Further, the average particle size measurement method by the image analysis method was measured by the average particle size measurement method described in [5] “Measurement of particle size distribution” in Examples.

The spherical silica fine particles need to have a high sphericity without containing irregular shaped particles such as rod-shaped, slanted-ball-shaped, elongated, beaded, or egg-shaped. In the present invention, the term “spherical” means that the sphericity is in the range of 0.90 to 1.00. Here, the sphericity is the maximum diameter (DL) and the short diameter (DS) orthogonal to each of any 50 particles in a photographic projection obtained by photographing with a transmission electron microscope. Mean ratio (DS / DL). When the sphericity is less than 0.90, it cannot be said that the fine particles are spherical, and may include those corresponding to the irregular shaped particles.

  The porous silica particles of the present invention using spherical silica fine particles having a sphericity of 0.90 to 1.00 as the spherical silica fine particles can exhibit excellent particle breaking strength. In particular, aligning the sphericity of spherical silica fine particles at 0.90 or more greatly affects the strength of the porous silica particles.

  Examples of the spherical silica fine particles include silica fine particles such as oxide sol disclosed in JP-A-5-132309, composite silica fine particles containing an organic group disclosed in JP-A-10-454043, and JP-A-7- It is possible to apply composite silica fine particles having voids inside the particles disclosed in Japanese Patent No. 133105, but when the sphericity is not reached, so-called hydrothermal treatment is performed to reduce the sphericity to 0. After adjusting to the range of .90 to 1.00, it can be used as spherical silica fine particles. Examples of the hydrothermal treatment conditions include a method of performing treatment at a temperature of 100 to 200 ° C. for 1 to 24 hours. It is also recommended to use an autoclave for the hydrothermal treatment.

  When the particle size distribution of the spherical silica fine particles is monodispersed, it is recommended that the particle size variation coefficient (CV value) of the spherical silica fine particles is desirably in the range of 2 to 10%. When the particle size variation coefficient is less than 2%, it is more desirable for the present invention, but it is not easy to obtain spherical silica fine particles having a particle size distribution of that level. When the particle diameter variation coefficient exceeds 10%, the degree of monodispersion decreases, and the effect of the present invention decreases. A range of 2 to 7% is recommended for the range of the particle variation coefficient.

  As a method for producing such a spherical aggregate of spherical silica fine particles, a conventionally known method can be employed, and examples thereof include a microcapsule method, an emulsification method, an oil method, and a spray method. Among them, the method for producing true spherical fine particles disclosed in Japanese Patent Publication No. 3-43201, Japanese Patent Publication No. 2-61406, etc. filed by the applicant of the present application is true spherical even if the starting inorganic silica fine particles are not spherical. Inorganic silica fine particle aggregates can be obtained, and the production process is not complicated and the economy is excellent. This preferable manufacturing method will be described later.

Surface treatment In the porous silica particles according to the present invention, a spherical aggregate formed by agglomerating the spherical silica fine particles may be subjected to a surface treatment if desired. The surface treatment needs to be performed within a range in which the pore volume range and the pore diameter range can be maintained. By such surface treatment, the strength of the particles can be improved.
When used as a carrier, it has the effect of increasing affinity with the substance to be carried and enhancing the carrying power. Moreover, when using as an adsorbent, the effect which raises selectivity and raises the adsorption efficiency of the target adsorbate is anticipated.

When surface treatment is performed by adding acid or alkali and an organic silicon compound represented by the following general formula and / or a partial hydrolyzate thereof to spherical silica fine particles, a silica-based coating layer having an organic functional group is formed. .
General formula: R _n Si (OR ′) _4-n
[However, R and R ′ are hydrocarbon groups selected from an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a vinyl group or an acrylic group, and n is 0, 1, 2 or 3 Is an integer. ]

2. Method for Producing Porous Silica Particles The method for producing spherical porous particles of the present invention is characterized by including the following steps (A), (B) and (C).

(A) Centrifugation treatment A dispersion of spherical silica fine particles having an average particle size of 10 to 50 nm is prepared, and centrifugal treatment is performed to separate coarse particles, and the particle size variation coefficient (CV value) is 2 to 10%. By adjusting to the range, a spherical silica fine particle dispersion in which the particle size distribution exhibits a monodisperse phase is prepared.

  Regarding the centrifugal separation conditions, it is usually recommended that the spherical silica fine particle dispersion has a solid content concentration of 1 to 50% by mass and a centrifugal force of 500 to 20000 G.

  In addition, when the particle diameter variation coefficient (CV value) is in the range of 2 to 10% in advance and the spherical silica fine particle dispersion liquid whose particle diameter distribution is a monodisperse phase is obtained and used as a raw material, it can be omitted. Become.

(B) Preparation of spherical silica fine particle aggregate A spray liquid containing a spherical silica fine particle dispersion is sprayed into an air stream to prepare a spherical silica fine particle aggregate. As the solvent of the spherical silica fine particle dispersion, water or an organic solvent is used. As the organic solvent, monohydric alcohols such as ethanol, propanol and butanol, polyhydric alcohols such as ethylene glycol, and the like can be used.

  The spray liquid may contain a silicic acid liquid as desired in addition to the spherical silica fine particle dispersion. By adding a silicic acid solution to the spherical silica fine particle dispersion as a spray solution, there is an effect of increasing the strength of the particles. The addition amount of the silicic acid solution is preferably 1.3 or more in [mass of spherical silica fine particles] / silicic acid solution (in terms of silica). If it is less than 1.3, the ratio of the silica derived from the silicic acid solution becomes excessive, and the tendency for the porosity to decrease increases.

  The concentration of the spray liquid is preferably in the range of 2 to 60% by weight, particularly 4 to 50% by weight in terms of solid content. When the solid content concentration of the spray liquid is less than 2% by weight, it is difficult to obtain an aggregate. When the concentration of the spray solution exceeds 60% by weight, the spray solution becomes unstable and it becomes difficult to obtain a spherical aggregate. Moreover, the spray-drying mentioned later cannot be performed continuously, and the yield of an assembly falls.

The spray drying method of the spray liquid is not particularly limited as long as the above-described aggregate can be obtained, and conventionally known methods such as a rotating disk method, a pressure nozzle method, and a two-fluid nozzle method can be employed. In particular, the two-fluid nozzle method disclosed in Japanese Examined Patent Publication No. 2-61406 is preferable because it can obtain spherical silica fine particle aggregates having a uniform particle size distribution and can easily control the average particle size. .
The drying temperature at this time varies depending on the concentration of the spherical silica fine particle dispersion, the processing speed, and the like, but when a spray dryer is used, for example, the inlet temperature of the spray dryer is 100 to 300 ° C., and the outlet temperature is 40 to 100 ° C. Etc. are preferable. More preferably, an inlet temperature of 210 to 250 ° C. and an outlet temperature of 50 to 55 ° C. are recommended. Although it depends on the shape or scale of the spraying device, the spraying speed is, for example, in the range of 0.1 L / hour to 3 L / hour.

(C) Heat treatment of spherical silica fine particle aggregates In order to increase the binding strength of the spherical silica fine particle aggregates obtained in the step (B) with the spherical silica fine particles or the gel component, in a temperature range of 150 to 600 ° C. Heat treatment. When the heat treatment temperature is less than 150 ° C., the effect of improving the binding force is not recognized, and when it exceeds 600 ° C., there is a possibility that the spherical silica fine particle aggregate may shrink, and the voids of the finally obtained spherical porous particles become small, It is not preferable.

Following the steps (A), (B), and (C), the following steps (D), (E), and (F) may be performed as desired.

(D) Preparation of spherical silica fine particle aggregate dispersion The spherical silica fine particle aggregate obtained in step (C) is allowed to cool or cool to room temperature to 40 ° C. and dispersed in water and / or an organic solvent to disperse the spherical silica fine particle aggregate. Prepare the solution. As the organic solvent, monohydric alcohols such as ethanol, propanol and butanol, polyhydric alcohols such as ethylene glycol, and the like can be used. The concentration of the dispersion is preferably in the range of 0.1 to 40% by weight, particularly 0.5 to 20% by weight in terms of the concentration of the spherical silica fine particle aggregate converted to an oxide. On the other hand, when the concentration exceeds 40% by weight, the aggregates easily aggregate in the step (D), which is not preferable.

(E) Surface treatment The following i) or ii) is added to the aggregate dispersion obtained in the step (D) to perform a surface treatment on the outer surface of the spherical silica fine particle aggregate.
i) Acid or alkali ii) Acid or alkali and an organosilicon compound represented by the following general formula and / or a partial hydrolyzate thereof General formula: R _n Si (OR ′) _4-n
[However, R and R ′ are hydrocarbon groups selected from an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a vinyl group or an acrylic group, and n is 0, 1, 2 or 3 Is an integer. ]

  In the case of i), an acid or alkali aqueous solution is usually used. The type of acid or alkali is not particularly limited, and examples include an aqueous hydrochloric acid solution, an aqueous boric acid solution, and an aqueous ammonium solution.

  The acid or alkali in the case of ii) is defined as in the case of i). Specific examples of the organosilicon compound represented by the general formula include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, and methyltrimethylsilane. Ethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, 3,3,3-trifluoropropyl Trimethoxysilane, methyl-3,3,3-trifluoropropyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxytripropyl Limethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldi Ethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ -Aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, trimethylsilanol Methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane and the like.

  In addition, although the acid or alkali added with an organosilicon compound and / or its partial hydrolyzate also functions as a catalyst for hydrolysis, a catalyst for hydrolysis may be added if desired. When a basic catalyst such as an alkali metal hydroxide, aqueous ammonia, or an amine is used as the hydrolysis catalyst, these basic catalysts can be removed after hydrolysis and used as an acidic solution. Moreover, when preparing a hydrolyzate using acidic catalysts, such as an organic acid and an inorganic acid, it is preferable to remove an acidic catalyst by ion exchange etc. after a hydrolysis. In addition, it is desirable to use the obtained hydrolyzate of the organosilicon compound in the form of an aqueous solution. Here, the aqueous solution means a state in which the hydrolyzate has transparency without being clouded as a gel.

  In addition, although the compound whose n is 0 with an organosilicon compound can be used as it is, since the compound whose n is 1-3 is poor in hydrophilicity, it can mix uniformly with a reaction system by hydrolyzing beforehand. It is preferable to make it. For the hydrolysis, a well-known method can be adopted as a hydrolysis method of these organosilicon compounds.

  Along with the above silicon compound and / or its partial hydrolyzate or silicic acid solution, a precursor metal salt of an inorganic oxide other than the oxide described above is added to form an oxide and an inorganic oxide other than the oxide. An oxide-based layer can also be formed. As the raw material of the inorganic oxide other than the oxide, an alkali-soluble inorganic compound is preferably used. The above-described alkali metal salt or alkaline earth metal salt of an oxo acid of a metal or nonmetal, an ammonium salt, a quaternary salt. Mention may be made of ammonium salts.

(F) Heat treatment Further, the spherical silica fine particle aggregate is separated from the dispersion of the spherical silica fine particle aggregate obtained in the step (E), dried, and then heated at 100 to 300 ° C. under atmospheric pressure or reduced pressure. Thus, porous silica particles are obtained.

[1A] Method for Measuring Average Particle Diameter by Dynamic Light Scattering Method Regarding the average particle diameter of spherical silica fine particles, the sample oxide sol is diluted with 0.58% ammonia water to adjust the oxide concentration to 1% by mass. And the average particle diameter was measured using the following particle size measuring apparatus.

[Particle size measuring device]
Laser particle analyzer (manufactured by Otsuka Electronics Co., Ltd., laser particle size analysis system: LP-510 model PAR-III, measurement principle: dynamic light scattering method, measurement angle 90 °, photo detector 2 inch photomultiplier tube, measurement range 3 nm to 5 μm 、 Light source He-Ne laser 5mW 632.8nm 、 Temperature adjustment range 5 ～ 90 ℃ 、 Temperature adjustment system Peltier element (cooling) 、 Ceramic heater (heating) 、 Cell 10mm square plastic cell 、 Measurement object: colloidal particles)
In addition, about the average particle diameter of the spherical silica fine particle prepared by the synthesis example 2-1, the synthesis example 2-2, and the synthesis example 2-3, it measured with the measuring method of the average particle diameter described in the postscript [5].

[1B] Method for measuring average particle diameter by centrifugal sedimentation method Regarding the average particle diameter of the porous silica particles, first, a dispersion of porous silica particles (water or 40 mass% glycerin solvent, solid content concentration 0.1 to 5). % By weight) is dispersed in an ultrasonic generator (Iuch, US-2) for 5 minutes. Further, from a dispersion whose concentration has been adjusted moderately by adding water or glycerin, the dispersion is taken into a glass cell (size of 10 mm in length, 10 mm in width, and 45 cm in height), and a centrifugal sedimentation type particle size distribution analyzer (Horiba) The average particle diameter was measured using a mill manufactured by CAPA-700.
Further, the average particle diameter of the spherical aggregate of spherical silica fine particles was measured in the same manner.

[2] Method for Measuring Specific Gravity Regarding the specific gravity of the porous silica particles, first, 10 g of a sample is collected in a crucible and dried at 110 ° C. for 2 hours. Next, after cooling with a desiccator, 3 to 4 g is put into a 25 ml pycnometer, distilled water is added and suspended, vacuum deaeration is performed at 60 mmHg for 1 hour, and the temperature is adjusted in a 25 ° C. constant temperature bath. Distilled water is added to the mark of the pycnometer to adjust the volume, and the sample volume (ml) is calculated from the difference between the pycnometer volume (25 ml) and the distilled water volume (ml). The specific gravity was determined from the weight (g) of the added sample and the calculated volume (ml).

[3] Method for Measuring Porosity The porosity of the porous silica particles was calculated from the following equation using the specific gravity determined in [2] above.
100- [specific gravity of porous silica particles determined in [2] above] / [specific gravity of silica] × 100 = porosity (%)

[4] Measuring method of sphericity Arbitrary 50 in the photographic projection figure obtained by photographing a sample oxide sol at a magnification of 250,000 times with a transmission electron microscope (H-800, manufactured by Hitachi, Ltd.) About each particle | grain, ratio (DS / DL) of the largest diameter (DL) and the short diameter (DS) orthogonal to this was measured, and those average values were made into sphericity.

[5] Measurement of particle size distribution Particles were photographed (magnification: 250,000 times) using a scanning electron microscope (manufactured by JEOL Ltd., JSM-5300 type), and an image analyzer was used for 250 particles of this image. (Asahi Kasei Co., Ltd., IP-1000) was used to measure the average particle size and calculate the coefficient of variation (CV value) regarding the particle size distribution. Specifically, the particle diameter of each of 250 particles was measured, and the average particle diameter and the standard deviation of the particle diameter were determined from the measured values, and calculated from the following formula.
Coefficient of variation (CV value) = (particle diameter standard deviation (σ) / average particle diameter (D _n )) × 100 (%)

[6] Measuring method of pore volume and pore diameter With respect to the pore volume of the porous silica particles, 10 g of a sample was taken in a crucible, dried at 300 ° C. for 1 hour, then placed in a desiccator and cooled to room temperature. 0.15 g was sampled in a glass cell, and nitrogen gas was adsorbed to the sample while vacuum degassing using Belsorp mini II (made by Nippon Bell Co., Ltd.), and desorbed. From the adsorption isotherm obtained, the relative pressure was 0.990. The pore volume at this point was determined, and the pore diameter (peak value) was calculated by the BJH method.

[Example 1]
Silica sol (manufactured by JGC Catalysts & Chemicals Co., Ltd .: Cataloid SI30, average particle size 12 nm, concentration 30% by weight) 1667 g of centrifuge (manufactured by Kokusan Co., Ltd., continuous high-speed centrifuge H-660) rotor (model: QNS, capacity) 1 L), and the solution was continuously passed through 7000 G at a rate of 400 g / min, and the liquid was continuously collected, whereby coarse particles were centrifuged. Coarse particles precipitated in the rotor.
The water-diluted product of silica sol collected (silica concentration 15% by mass) 2000 g was subjected to cation exchange and adjusted to pH = 2.0, and then a silicic acid solution (silica concentration 4.8% by mass) was added to [silica sol [Silica in the inside] / [Silica in the silicic acid solution] = 9/1, pure water was added and diluted so that the slurry concentration became 5%, and the slurry was prepared by stirring.

The obtained slurry was applied to a spray dryer, and in a dry air flow adjusted so that the inlet temperature was 240 ° C. and the outlet temperature was 50 to 55 ° C., the flow rate was 2 L / hr to one of the two-fluid nozzles, and the gas to the other nozzle Pressure was supplied at a flow rate of 0.75 MPa and spray-dried to obtain a powder composed of spherical silica fine particle aggregates.
This powder was calcined at 450 ° C. for 3 hours to obtain porous silica particles. The average particle size, specific surface area, pore volume, and pore size of the peak value in the pore size distribution of the porous silica particles are fine within the range of (D1) × 0.75 to (D1) × 1.25 [nm]. Table 1 shows the total pore volume of pores having a pore size, the average particle size and the particle size variation coefficient (CV value) of the spherical silica fine particles used as the raw material, and the production conditions of the porous silica particles. It measured similarly about Examples 2-4 and Comparative Examples 1-3.

[Example 2]
As silica sol, except for using a water-diluted product (silica concentration 30 mass%) of JGC Catalysts & Chemicals Co., Ltd .: Cataloid SI40 (average particle diameter 17 nm, silica concentration 40% by weight), in the same manner as in Example 1, Porous silica particles were obtained. The average particle diameter, specific surface area, pore volume, pore diameter of the peak value in the pore diameter distribution, and pore volume occupied by ± 25% of the pore diameter that maximizes the pore volume were measured as a result. Is shown in Table 1.

[Example 3]
As silica sol, the same method as in Example 1 was used except that a water-diluted product (silica concentration 30% by mass) of JGC Catalysts & Chemicals Co., Ltd .: Cataloid SI50 (average particle size 25 nm, concentration 50% by weight) was used. Thus, porous silica particles were obtained. Of the porous silica particles, the average particle diameter, specific surface area, pore volume, pore diameter at the peak value in the pore diameter distribution, and pores occupied by ± 25% of the pore diameter at which the pore volume is maximized The volume was measured and the results are shown in Table 1.

[Example 4]
The same procedure as in Example 1 was used except that a water-diluted product (silica concentration of 30% by mass) of Cataloid SI-45P (average particle size of 45 nm, concentration of 40% by weight) manufactured by JGC Catalysts & Chemicals, Ltd. was used as the silica sol. Porous silica particles were obtained. 50 g of these porous particles were dispersed in 200 g of ethanol, 7.5 g of 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd .; KBM-503) and 15 g of 1% aqueous ammonia were added, and the mixture was stirred at 50 ° C. for 15 hours. Heated. Thereafter, the porous particles were collected and dried at 150 ° C. The average particle diameter, specific surface area, pore volume, pore diameter of the peak value in the pore diameter distribution, and the pore volume occupied by ± 25% of the pore diameter that maximizes the pore volume are the surface treated porous silica particles. The results are shown in Table 1.

[Comparative Example 1]
Based on the method of Example 1 of JP-A-61-270201, a silica colloid solution prepared from sodium silicate solution and sulfuric acid and having a silica concentration of 30% and an average particle size of 7 nm was placed in one of two commercially available two-fluid nozzles at 5 kg / hr. The gas pressure was supplied to the other at a flow rate of 2 kg / hr, and the colloidal liquid was sprayed into the drying space in which the drying airflow flows. The temperature of the drying space where the colloidal liquid was sprayed was 40 ° C. and the humidity was 5.8%. True spherical particles having an average particle diameter of 8 μm and a particle size distribution of 0.5 to 16 μm were obtained. The average particle diameter, specific surface area, pore volume, pore diameter at the peak value in the pore diameter distribution, and pore volume occupied by ± 25% of the pore diameter at which the pore volume is maximized are measured. Is shown in Table 1.

[Comparative Example 2]
Based on the method of Example 2 of JP-A-61-270201, a silica colloid liquid having an average particle diameter of 12 nm was prepared. This liquid is adjusted with pure water so that the silica concentration is 5%, and is supplied to a spray dryer. In a dry air stream adjusted so that the inlet temperature is 240 ° C. and the outlet temperature is 50 to 55 ° C., the two-fluid nozzle One was supplied at a flow rate of 2 L / hr and a gas pressure was supplied to the other nozzle at a flow rate of 2 kg / hr and spray-dried to obtain a powder composed of spherical silica fine particle aggregates.

[Comparative Example 3]
As the silica sol, JGC Catalysts Chemical Co., Ltd. product: Cataloid SI80P (average particle size 80 nm, concentration 40 wt%) was used except that the water-diluted product (silica concentration 30 mass%) was used, and the centrifugation conditions were changed to 2120 G. In the same manner as in Example 1, porous silica particles were obtained. Of the porous silica particles, the average particle diameter, specific surface area, pore volume, pore diameter at the peak value in the pore diameter distribution, and pores occupied by ± 25% of the pore diameter at which the pore volume is maximized The volume was measured and the results are shown in Table 1.

The present invention is useful as a support for a catalyst or the like. In addition, it is also useful as a carrier for adsorbents, ultraviolet shielding materials, antimicrobial materials, enzymes and the like.

4 is a scanning electron micrograph (5,000 magnifications) of the porous silica particles obtained in Example 4. FIG. It is a pore size distribution diagram (X axis: pore diameter, Y axis: value obtained by differentiating pore volume by pore diameter) for the porous silica particles obtained in Examples 1 to 4.

Claims (8)

Porous silica particles having an interparticle void structure therein, wherein the porous silica particles have an average particle diameter (PD) of 0.5 to 50 μm, a specific surface area of 30 to 250 m ² / g, and the porous silica particles Porous silica particles, wherein the silica particles satisfy the following requirements 1) to 3):
1) Range in which pore volume is 0.10 to 0.25 cc / g 2) Peak pore diameter in pore diameter distribution (X axis: pore diameter, Y axis: value obtained by differentiating pore volume by pore diameter) D1) is in the range of 2 to 50 nm 3) The total pore volume of pores having pore diameters in the range of (D1) × 0.75 to (D1) × 1.25 nm is 80% or more of the total pore volume The porous silica particles are spherical silica fine particles having an average particle diameter (D) of 10 to 50 nm, a sphericity of 0.9 to 1, and a particle diameter variation coefficient (CV value) of 2 to 10%. 2. The porous silica particle according to claim 1, wherein the porous silica particle comprises a spherical aggregate in which spherical silica fine particles whose particle size distribution exhibits a monodisperse phase are aggregated. The porous silica particles according to claim 1 or 2, wherein the porosity of the porous silica particles is in the range of 5 to 50%. The porous silica particles according to any one of claims 1 to 3, wherein a particle size distribution of the spherical silica fine particles indicates a monodisperse phase. The manufacturing method of the porous silica particle containing each process of following (A), (B) and (C).
(A): A dispersion of spherical silica fine particles having an average particle size of 10 to 50 nm is subjected to centrifugal separation to separate coarse particles, and the particle size variation coefficient (CV value) is adjusted to a range of 2 to 10%. Step (B) for preparing a spherical silica fine particle dispersion having a monodispersed diameter distribution: A step of preparing a spherical silica fine particle aggregate by spraying a spray liquid containing the spherical silica fine particle dispersion treated in the previous step in an air stream. (C): A step of heat-treating the spherical silica fine particle aggregate obtained in the previous step within a temperature range of 150 to 600 ° C. 6. The method for producing porous silica particles according to claim 5, wherein the following steps (D), (E) and (F) are carried out following the steps (A), (B) and (C). .
(D): Following the previous step, the spherical silica fine particle aggregate is dispersed in water and / or an organic solvent to prepare a dispersion of the spherical silica fine particle aggregate (E): the spherical silica prepared in the previous step The step of surface-treating the spherical silica fine particle aggregate by adding the following i) or ii) to the dispersion of the fine particle aggregate i) Acid or alkali ii) Acid or alkali and represented by the following general formula Organosilicon compound and / or partial hydrolyzate thereof General formula: R _n Si (OR ′) _4-n
[However, R and R ′ are hydrocarbon groups selected from an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a vinyl group or an acrylic group, and n is 0, 1, 2 or 3 Is an integer. ]
(F): Following the previous step, the spherical silica fine particle aggregate is separated from the dispersion of the spherical silica fine particle aggregate, dried, and then heated at 100 to 300 ° C. under atmospheric pressure or reduced pressure.   The method for producing porous silica particles according to claim 5 or 6, wherein the spray liquid used in the step (B) contains a silicate liquid in addition to the spherical silica fine particles.   Carrier particles comprising the porous silica particles according to any one of claims 1 to 5.