JP6674624B2 - Method for producing porous silica, and porous silica and deodorant - Google Patents

Description

  The present invention relates to porous silica, a deodorant containing the same, and a method for producing porous silica.

Many studies have been reported on metal-containing porous silica. For example, "J. Ceram. Soc. Japan, 109, [10], 818-822 (2001)" by Li Ken, Masato Uehara, Naoya Enomoto, Junichi Hojo, etc. (1) Polyoxyethylene with the addition of hydrochloric acid [23] Dropping tetraethoxysilane and tetraethoxytitanium into an aqueous solution of lauryl ether to produce a porous body containing silica and titanium, and (2) firing after mixing mesoporous silica and zinc nitrate Describes that a porous body containing zinc oxide is produced.
JP-A-4-313348 discloses that a carrier is immersed in an organic solution of an organometallic compound, the organic compound is carried on the carrier, and the carried organometallic compound is converted into a corresponding metal or metal oxide. A method for producing a catalyst, which is a feature, is described.
Further, JP-A-2002-187712 discloses that a water-miscible organic solvent, an alkylamine and a silicate or a mixed solution containing a combination of a silicate and a metal salt soluble in a water-miscible organic solvent are stirred. Water or an acidic aqueous solution is added underneath, the resulting silica-alkylamine composite product is grown into spherical particles, and the alkylamine in the spherical particles is removed, and spherical porous silica and silica-metal composite particles Is described. The publication also describes that spherical porous silica and silica-metal composite particles can adsorb malodorous substances in mesopores and thus have a function as a deodorant.

JP-A-4-313348 JP 2002-187712 A

Xianying Li et al., J. Ceram. Soc. Japan, 109, [10], 818-822 (2001)

It is known that porous silica adsorbs basic odors such as ammonia, acidic odors such as acetic acid, and acetaldehyde-based odors by silanol groups on the silica surface. However, according to the findings of the present inventors, while a basic odor and an acidic odor are strongly adsorbed on silica, an acetaldehyde odor is relatively hardly adsorbed.
Therefore, an object of the present invention is to provide a porous silica, a deodorant, and a method for producing porous silica, which have high deodorizing power against acetaldehyde-based odor.

The present invention provides a step of mixing a surfactant, a metal salt, and a ligand component in an aqueous solution to form micelles containing a water-insoluble complex composed of a metal of a metal salt and a ligand component. After the step of generating micelles, a step of adding a silica source to the aqueous solution, and a step of adding the silica source, a step of adding a basic aqueous solution to the aqueous solution, and a step of adding the basic aqueous solution, Provided is a method for producing porous silica, comprising a step of collecting micelles and a step of baking the collected micelles to obtain porous silica.
Further, the present invention is a porous silica containing silica particles including primary particles having primary pores formed thereon, and cobalt-containing particles supported on the silica particles, wherein the particle diameter of the cobalt-containing particles is: A porous silica having a cobalt content of less than 20 nm, a cobalt content of 0.5 wt% or more in the porous silica, and a cobalt particle ratio of 70% or more.
The present invention also provides a deodorant containing the porous silica.

  According to the present invention, there is provided a porous silica, a deodorant, and a method for producing porous silica, which have high deodorizing power against acetaldehyde odor.

FIG. 1 is a diagram showing a TEM image of the porous silica of Example 1. FIG. 2 is a diagram showing a TEM image of the porous silica of Example 2. FIG. 3 is a view showing a TEM image of the porous silica of Comparative Example 1. FIG. 4 is a view showing a TEM image of the porous silica of Comparative Example 2. FIG. 5 is a view showing a TEM image of the porous silica of Comparative Example 4. FIG. 6 is a graph showing TG-DTA measurement results of the precursor in Example 1. FIG. 7 is a graph showing TG-DTA measurement results of the precursor in Comparative Example 1. FIG. 8 is a graph showing the results of the particle size distribution measurement in Example 1. FIG. 9 is a graph showing the results of the particle size distribution measurement in Example 3.

1. Porous Silica The porous silica of the present invention is a porous silica containing silica particles including primary particles having primary pores formed therein, and metal-containing particles supported on the silica particles.

  Silica particles have a function of adsorbing basic odors such as ammonia, acidic odors such as acetic acid, and acetaldehyde-based odors by silanol groups formed on the surface thereof. The primary pores formed in the primary silica particles are generally considered to have a pore diameter of 1 to 20 nm. Further, the silica particles preferably have secondary pores formed of particle gaps due to the bonding between the primary particles. Due to the existence of the coarse secondary pores, an effect of rapidly diffusing the gas to the primary pores present inside can be expected, which leads to an increase in the deodorizing capacity and the deodorizing speed.

  The metal-containing particles are supported on porous silica to oxidize and decompose acetaldehyde-based odor. By supporting the metal-containing particles on the silica particles, the acetaldehyde odor that could not be completely absorbed by silica alone can be oxidatively decomposed by the metal-containing particles, and the deodorizing ability can be enhanced. In addition, acetic acid generated by oxidative decomposition of acetaldehyde is adsorbed and deodorized by silanol groups present on the surface of the silica particles.

Examples of the metal of the metal-containing particles include at least one selected from the group consisting of zinc, silver, copper, manganese, and cobalt, and preferably cobalt.
The metal-containing particles have a particle size of less than 20 nm, preferably less than 15 nm, more preferably less than 10 nm. When the particle diameter of the metal-containing particles is small, the catalyst efficiency is increased, so that the deodorizing performance can be enhanced. Further, when colored metal-containing particles are supported on silica particles, the appearance of the porous silica may be impaired by coloring with the metal-containing particles. When the particle diameter of the metal-containing particles is small, even if the metal-containing particles are colored, the coloring of the porous silica can be made inconspicuous, and the appearance is not impaired.
Specifically, according to the present invention, the lightness L * of the porous silica can be 50 or more, preferably 60 or more. When the lightness is large, coloring when the present porous silica is kneaded with a resin or the like can be reduced, and by mixing a pigment, coloring can be performed to a desired color. Further, according to the present invention, the chroma of the porous silica can be 17 or less, preferably 15 or less.

The metal content in the porous silica is 0.5 wt% or more, and preferably 0.6 wt% or more.
The metal particle ratio of the porous silica is 70% or more, preferably 80% or more, more preferably 90% or more. Here, in the present specification, the “metal particle ratio” refers to the ratio of the mass of the metal supported without being doped to the silica to the total mass of the metal contained in the porous silica. The term “doped” refers to a state in which a metal is incorporated in the SiO ₄ skeleton of silica in such a manner as to replace a Si element.
According to the findings of the present inventors, it is important that the metal is supported in a particle state without being taken into the skeleton of the silica in order for the metal to exert the oxidative decomposition action of acetaldehyde. By setting the metal content in the porous silica to 0.5 wt% or more and the metal particle ratio to 70% or more, it is possible to reduce the content of the metal present in a form that does not contribute to the deodorizing ability of acetaldehyde. Thus, the ability as a deodorant can be improved.

Further, in the porous silica of the present invention, the specific surface area is preferably at least 500 m ² / g, more preferably at least 1000 m ² / g. Odors such as ammonia, acetic acid, and acetaldehyde are known to be chemically adsorbed by silanol groups on the silica surface, but since the number of silanol groups per unit area is almost constant, the deodorizing power per unit weight is improved. Therefore, it is necessary to increase the specific surface area.

  The porous silica of the present invention can be used by mixing with a resin. The porous silica of the present invention has high heat resistance because it is formed from silica and a metal-containing substance. As the resin, any conventionally known thermoplastic resin can be used as long as it is a melt-moldable thermoplastic resin. For example, low-, medium-, or high-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene , Isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer And the like. Polyolefin resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamide resins such as nylon 6, nylon 6,6, and nylon 6,10; polycarbonate resins. It is particularly preferable to use polyethylene, polypropylene, or polyester as the resin.

  The deodorant of the present invention contains the porous silica. The porous silica and the porous inorganic oxide may be mixed and used. Examples of the porous inorganic oxide include zeolite, silica gel, alumina, sepiolite, spherical silica, perlite, activated carbon (such as mineral activated carbon), which are aluminum and / or silicon oxide. The zeolite may be a synthetic zeolite or a natural zeolite (such as faujasite). The porous inorganic oxide preferably has heat resistance of the porous silica of 350 ° C. or higher and has heat resistance in the same temperature range so as not to impair the excellent heat resistance of the porous silica.

2. Method for Producing Porous Silica In the present invention, a method for producing the above-described porous silica is also devised. According to the production method described below, it is possible to obtain porous silica having a small metal-containing particle diameter and a high metal particle ratio.
Specifically, the production method of the present invention comprises:
(A) a step of mixing a surfactant, a metal salt and a ligand component in an aqueous solution to form a micelle containing a water-insoluble complex in which the ligand component is coordinated to the metal of the metal salt;
(B) a step of adding a silica source to the aqueous solution after the step of generating micelles;
(C) a step of adding a basic aqueous solution to the aqueous solution after the step of adding the silica source,
(D) a step of collecting the micelles after the step of adding the basic aqueous solution, and (E) a step of firing the collected micelles to obtain porous silica,
Contains.
Hereinafter, each step will be described in detail.

(A) Mixing of Surfactant, Metal Salt, and Ligand Component First, a surfactant and a metal salt are mixed in an aqueous solution to generate micelles. By mixing the surfactant and the metal salt, micelles containing the metal salt are produced. For example, micelles can be formed by stirring and mixing a metal salt and a surfactant in water at room temperature to 200 ° C. for 30 minutes to 24 hours. The aqueous solution may contain an organic solvent such as ethanol and toluene in addition to water.

  The surfactant is preferably neutral or cationic, more preferably an alkyl ammonium salt. The alkylammonium salt may have at least 8 carbon atoms, but preferably has 12 to 18 carbon atoms in view of industrial availability. Examples of the alkyl ammonium salt include hexadecyltrimethylammonium chloride, cetyltrimethylammonium bromide, stearyltrimethylammonium bromide, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, octadecyltrimethylammonium Chloride, didodecyldimethylammonium bromide, ditetradecyldimethylammonium bromide, didodecyldimethylammonium chloride, ditetradecyldimethylammonium chloride and the like. These surfactants may be used alone or in combination of two or more. The concentration of the surfactant in the aqueous solution is preferably 50 to 400 mmol / L, more preferably 50 to 150 mmol / L. The surfactant functions as a molecular template that forms micelles in water and electrostatically accumulates a silica source on the surface in a later step. The surfactant eventually disappears upon firing to form primary pores.

A metal salt is a substance that serves as a metal source. As the metal salt, for example, a fatty acid metal salt and a metal chloride can be used, and a fatty acid metal salt is preferable. The fatty acid metal salt is preferably a fatty acid metal salt having 8 to 24 carbon atoms, preferably 8 to 18 carbon atoms, and more preferably 12 to 18 carbon atoms. The fatty acid metal salt is not particularly limited, but includes, for example, octanoate, laurate, stearate and the like, and preferably stearate. These fatty acid metal salts may be used alone or in combination of two or more. The concentration of the fatty acid metal salt in the aqueous solution is preferably lower than the concentration of the surfactant, and more preferably 0.2 to 5 mmol / L.
By controlling the concentration of the metal salt in the aqueous solution and the type of the metal salt (such as a carbon chain when a fatty acid metal salt is used), the particle size of the metal particles in the finally obtained porous particles can be controlled. You can also.

Subsequently, by adding the ligand component to the aqueous solution, a water-insoluble complex in which the ligand component coordinates to the metal of the metal salt is formed. When the ligand component is not added, in the formed micelle, it is considered that most of the metal contained in the metal salt exists near the surface of the micelle. Alternatively, when the metal salt is a soluble salt such as cobalt chloride, the metal is considered to be hardly incorporated into the micelle. On the other hand, if a water-insoluble complex is formed by the addition of a ligand component, the formed complex is likely to be taken into micelles, which is a hydrophobic environment. That is, the metal existing near the surface of the micelle can be moved to the inside of the micelle.
When the metal salt is a hydrophobic salt such as cobalt stearate, the particle size of the micelle can be reduced by adding a ligand component, and as a result, the porous silica finally obtained is obtained. The particle diameter of the metal-containing particles contained therein can also be reduced.

  In order to form a water-insoluble complex, for example, after addition of the ligand component, stirring and mixing may be performed at room temperature to 200 ° C. for 30 minutes to 24 hours.

  The ligand component is not particularly limited as long as it is a compound which forms a complex insoluble in water with a metal. For example, a compound having an 8-quinolinol structure is preferably used. Examples of the compound having an 8-quinolinol structure include 8-quinolinol (also referred to as oxine), 5- (octyloxymethyl) -8-quinolinol, and the like.

As the ligand component, it is preferable to use a substance in which the complex formation constant of the insoluble complex in which the ligand component is coordinated to the metal is larger than the complex formation constant of the metal salt. When the complex formation constant of the insoluble complex is larger than the complex formation constant of the metal salt, the ligand component is easily coordinated with the metal, and the formation of the insoluble complex can be promoted. As a result, the amount of the complex taken into the micelle can be increased.
For example, according to the Chemical Handbook, Basic Edition, 5th revised edition, Maruzen (2004), the logarithm β1 of the complex formation constant of oxine cobalt (complex of 8-quinolinol and cobalt) is 11.52, and β2 is 22.82. . Regarding the numerical value of the complexation constant of the complex of cobalt and 5- (octyloxymethyl) -8-quinolinol, 5- (octyloxymethyl) -8-quinolinol has a structure in which an alkyl group is attached to the 5-position of 8-quinolinol. Since the alkyl group does not act as a coordinating group and does not substantially affect the stability of the metal chelate, it is considered that the value is equivalent to that of 8-quinolinol. The logarithm β1 of the complexation constant between cobalt and acetic acid is 0.60. Further, the logarithm β1 of the complex formation constant of cobalt stearate is considered to be about the same as that of acetic acid because the coordinating group is a carboxyl group. The complexation constant can be determined by measurement. In the equilibrium state, the complex concentration [ML _n ^{(a-nb) +} ], the free metal ion concentration [M ^{a +} ], and the ligand concentration [L ^b- ] are measured, and can be obtained from the following formula. .
M ^{a +} + nL ^b- → ML _n ^{(a-nb) +}
β _n = [ML _n ^{(a-nb) +} ] / [M ^{a +} ] [L ^b- ] ⁿ
Since the total concentration of the metal ion and the ligand is kept constant in the measurement system, the concentration of the complex and the free ligand or the concentration of the complex and the free metal ion is in a subordinate relationship, and the three variables are The two may be measured as a concentration or as a physical quantity (light absorption, electrical conductivity, optical rotation, etc.) proportional to the concentration.

  The addition amount of the ligand component is, for example, 2 to 5 molar equivalents, preferably 2 to 3 molar equivalents, relative to the metal of the metal salt.

  Incidentally, the ligand component may be added to the aqueous solution at the same time as the surfactant and / or the metal salt. However, preferably, after mixing the surfactant and the metal salt in the aqueous solution, the ligand component is added.

(B) Addition of silica source Subsequently, a silica source is added to the aqueous solution. By adding the silica source, the silica source accumulates on the micelle surface.
The silica source is preferably an alkoxysilane. Organic functional groups on the silicon atom are lost by hydrolysis and do not affect the structure of the composite. However, if the organic functional group is bulky, the hydrolysis rate will be slow and the synthesis time will be long. Therefore, preferred are tetraethoxysilane, tetramethoxysilane, tetra-n-butoxysilane, sodium silicate and the like. The silica source is more preferably tetraethoxysilane. These silica sources may be used alone or in combination of two or more. The concentration of the silica source in the aqueous solution is preferably from 0.2 to 1.8 mol / L, more preferably from 0.2 to 0.9 mol / L. When sodium silicate is used alone or in combination as a silica source, an operation of heating and refluxing at 200 ° C. or lower in an aqueous solution for 20 to 2 hours is performed. After hydrolysis (acid or neutral acceleration), the silica source is linked by a dehydration condensation reaction (basic acceleration) to form a silica wall in a step (D) described later.

(C) Addition of basic aqueous solution Subsequently, a basic aqueous solution is added. By the addition of the basic aqueous solution, the silica source accumulated on the micelle surface is dehydrated and condensed to form a silica wall.
Examples of the basic aqueous solution include aqueous solutions of sodium hydroxide, sodium carbonate, ammonia and the like. The basic aqueous solution is preferably an aqueous sodium hydroxide solution. These basic aqueous solutions may be used alone or in combination of two or more. The basic aqueous solution is added so that the pH of the dispersion is preferably 8 to 14, more preferably 9 to 11. The base accelerates the dehydration condensation reaction of the silica source. By rapidly making the solution basic while the silica source is sufficiently hydrolyzed, a dehydration condensation reaction is caused at once. As a result, the surface tension of the condensed portion increases, the silica wall becomes spherical, and the spheres are joined in multiple layers, causing spinodal decomposition (phase separation). These structures are frozen by chemical crosslinking to form secondary pores.
At this time, the complex incorporated into the micelle is hardly hydrolyzed and hardly incorporated into the silica skeleton.

(D) Recovery of micelles Subsequently, micelles are recovered as a precursor. For example, the precursor can be recovered by filtering and drying the micelle. The micelles are filtered, for example, by suction filtration, and washed repeatedly with water until the pH of the filtrate becomes 7. The micelles are dried by, for example, a drier or a vacuum drier, and sufficiently dried.
(E) Firing After recovering the micelles, the precursor is fired. By performing the baking, the organic components contained in the precursor are removed. That is, the surfactant is removed, and porous silica having pores is formed. Further, the organic component of the metal-containing substance (complex) taken into the precursor is removed, and the metal-containing particles are supported in the pores of the silica. Thereby, porous silica is obtained.
The firing is performed at a temperature equal to or higher than the decomposition temperature of the surfactant, and is preferably 400 to 600 ° C.

According to the above-mentioned method, by adding a ligand component, a metal derived from a metal salt can be converted into a water-insoluble complex, and can be taken into the micelle. As a result, the metal component is supported in a state of being encapsulated inside the micelle of the surfactant, and when the surfactant is eliminated by firing, the metal-containing particles are not taken into the SiO ₄ skeleton, and the metal-containing particles are converted into a porous silica material. Are preferentially distributed on the surface of the pores, and the metal particle ratio can be increased. Thus, the introduced metal can be expected to act effectively, and can be used not only for deodorants but also for other industrial uses such as catalysts, separators, and adsorbents. In addition, since the metal-containing particles are included in the pores, the original color of the metal is covered with the white color of silica, and the decrease in lightness generally caused when a colored metal is introduced can be suppressed, and deodorization can be achieved. Excellent appearance of agent.
Since the porous silica of the present invention has a complicated form in which spheres are bonded in multiple layers, it is difficult for the porous surface to be uniformly covered with the resin when kneaded with the resin. This is because the presence of the non-uniform particle gap makes it difficult for the resin to penetrate into the interior due to the maze effect. Therefore, in the resin molded article kneaded with the porous silica of the present invention, the diffusion rate of the odor to the deodorant is easily maintained, and it can be expected that the effect as the deodorant is maintained even after the resin kneading.

Further, according to the above-described method, by adding the ligand component, the size of the micelle can be reduced, and thereby, the particle diameter of the finally obtained metal particles can be reduced.
According to the findings of the present inventors, the complex formed by adding the ligand component has a decomposition temperature lower than the decomposition temperature of the metal salt. As a result, organic substances can be removed from the metal-containing substance in the precursor at a low firing temperature and in a short time.

(Test method)
(Specific surface area)
It was measured at a liquid nitrogen temperature by a one-point method using Flowsorb II2300 manufactured by Micromeritics.
(color)
L ^* value, a ^* value, and b ^* value were measured using SM color computer (SM-4) manufactured by Suga Test Instruments Co., Ltd. Lightness was calculated as L ^* value, and chroma was calculated as √ (a ^{* 2} + b ^{* 2} ). Brightness indicates that the larger the value, the whiter the color. The smaller the saturation, the more achromatic the color.
(Cobalt content)
Approximately 50 mg of the porous silica after calcination was accurately weighed and dissolved with 4 ml of hydrochloric acid, and then the metal concentration in the aqueous solution was measured by ICP-OES manufactured by Thermo Scientific. By treating with hydrochloric acid, it is considered that all the cobalt components contained in the porous silica are dissolved in hydrochloric acid, including the cobalt component (cobalt doped into silica) incorporated in the skeleton of the silica. Therefore, based on the measurement results, the total content of cobalt present in the porous silica was calculated as the cobalt content.
(Cobalt particle amount)
After the recovery (step E), about 0.5 g of the micelle (precursor) before calcination (step F) was weighed and washed seven times with a total of about 50 ml of ethanol. As a result, of the cobalt contained in the micelles, components not doped with silica were removed. As a washing operation, an operation of adding about 7 ml of ethanol to the sample and performing ultrasonic cleaning for 5 minutes, and then sedimenting a solid content by centrifugation and discarding the supernatant was performed seven times. Next, the solid content was vacuum-dried and then calcined at 570 ° C. for 5 hours to obtain porous silica. About 50 mg of the obtained sample was accurately weighed and dissolved with 4 ml of hydrochloric acid, and then the metal concentration in the aqueous solution was measured by ICP-OES manufactured by Thermo Scientific. Based on the measurement results, the “content of cobalt doped in silica” in the porous silica was calculated. Further, the content of cobalt not doped into silica in the porous silica was calculated as “cobalt particle amount” by the following formula.
(Formula 1): Cobalt particle amount = Cobalt content−Cobalt content of silica doped (cobalt particle ratio)
Based on the measurement results of the cobalt content and the amount of cobalt particles, using the following formula, the ratio of the mass of cobalt supported without being doped to silica with respect to the total mass of cobalt was calculated as `` cobalt particle ratio ''. .
(Formula 2): Cobalt particle ratio (%) = Cobalt particle amount / Cobalt content × 100
In Comparative Example 1, the cobalt was in the state of cobalt stearate, and extraction with ethanol or water was difficult, and it could not be quantified.
(Acetaldehyde deodorization test)
500 ml of odor was prepared. The initial concentration of acetaldehyde was 14 ppm or 750 ppm. After 50 mg of porous silica was put into the odor and stirred for a certain period of time, the concentration was measured using a gas detection tube 92L made by Gastech, and the deodorization rate was calculated from the comparison with the initial concentration. Under the condition that the initial concentration of the acetaldehyde concentration was 750 ppm, the same sample was subjected to the deodorization test twice, and the deodorization rate was calculated for each of the first and second times.
(TEM)
After embedding the porous silica in Quetol 812 (epoxy resin), it was ultra-thin sliced with an ultramicrotome, vacuum-deposited with carbon, and measured at 200 kV using JOEL JEM2010.

(Example 1)
Water, hexadecyltrimethylammonium chloride and cobalt stearate were added to a 300 ml beaker, and stirred at 100 ° C. for 1 hour to prepare an aqueous solution in which cobalt stearate was uniformly dispersed. Here, 8-quinolinol was added, and the mixture was further stirred at 100 ° C. for 1 hour. After cooling to room temperature, tetraethoxysilane was added and stirred until uniform. Next, an aqueous sodium hydroxide solution was added, and the stirrer was rotated at 1000 rpm and stirred for 20 hours. The molar ratio of the mixed solution was such that tetraethoxysilane: hexadecyltrimethylammonium chloride: cobalt stearate: 8- such that the amount of Co in the synthesized product was 1 wt% and 8-quinolinol was 3 molar equivalents with respect to Co. Quinolinol: water: sodium hydroxide = 1: 0.225: 0.0106: 0.0319: 125: 0.225. The solid product was separated from the obtained suspension by filtration, vacuum-dried at 80 ° C., and calcined at 570 ° C. for 5 hours to remove organic components.
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test. FIG. 1 shows a TEM image of the cross section. Further, as shown in FIG. 1, a structure in which particles having uniform primary pores (white dots) of 1 to 20 nm are obtained. Further, metal particles (black portions) of 5 to 10 nm are included. Note that, on the surface of the obtained composite, metal particles of about 5 nm as observed in a TEM image of the cross section were not observed.

(Example 2)
The synthesis was carried out in the same manner as in Example 1 except that 8-quinolinol was changed to 5- (octyloxymethyl) -8-quinolinol. The molar ratio of the mixed solution was such that tetraethoxysilane: hexadecyltrimethylammonium was used so that the amount of Co in the synthesized product was 1 wt% and 5- (octyloxymethyl) -8-quinolinol was 3 molar equivalents relative to Co. Chloride: cobalt stearate: 5- (octyloxymethyl) -8-quinolinol: water: sodium hydroxide = 1: 0.225: 0.0106: 0.0319: 125: 0.225. The solid product was separated from the obtained suspension by filtration, vacuum-dried at 80 ° C., and calcined at 570 ° C. for 5 hours to remove organic components.
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test. FIG. 2 shows a TEM image of the cross section. In FIG. 2, the same structure as in FIG. 1 can be confirmed.

(Example 3)
Synthesis was performed in the same manner as in Example 1 except that cobalt stearate was changed to cobalt chloride. The molar ratio of the mixed solution was such that tetraethoxysilane: hexadecyltrimethylammonium chloride: cobalt chloride: 8-quinolinol so that the amount of Co in the synthesized product was 1 wt% and the amount of 8-quinolinol was 3 molar equivalents relative to Co. : Water: sodium hydroxide = 1: 0.225: 0.0106: 0.0319: 125: 0.225. The solid product was separated from the obtained suspension by filtration, vacuum dried at 80 ° C., and calcined at 570 ° C. for 5 hours to remove organic components.
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test.

(Comparative Example 1)
Water, hexadecyltrimethylammonium chloride and cobalt stearate were added to a 300 ml beaker, and stirred at 100 ° C. for 1 hour to prepare an aqueous solution in which cobalt stearate was uniformly dispersed. After cooling to room temperature, tetraethoxysilane was added and stirred until uniform. Next, an aqueous sodium hydroxide solution was added, and the stirrer was rotated at 1000 rpm and stirred for 20 hours. The molar ratio of the mixed solution is such that tetraethoxysilane: hexadecyltrimethylammonium chloride: cobalt stearate: water: sodium hydroxide = 1: 0.225: 0.0106 so that the amount of Co in the synthesized product becomes 1 wt%. : 125: 0.225. The solid product was separated from the obtained suspension by filtration, vacuum dried at 80 ° C., and calcined at 570 ° C. for 5 hours to remove organic components.
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test. FIG. 3 shows a TEM image of the cross section. In FIG. 3, the same structure as in FIG. 1 can be confirmed, but the amount of particles is small, and the particle size is about 20 nm, which is larger than that in Example 1.

(Comparative Example 2)
It was synthesized in the same manner as in Comparative Example 1, except that cobalt stearate was changed to oxine cobalt. The molar ratio of the mixed solution is such that tetraethoxysilane: hexadecyltrimethylammonium chloride: oxine cobalt: water: sodium hydroxide = 1: 0.225: 0.0106: such that the amount of Co in the synthesized product becomes 1 wt%. 125: 0.225. The solid product was separated from the obtained suspension by filtration, vacuum dried at 80 ° C., and calcined at 570 ° C. for 5 hours to remove organic components.
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test. The oxine cobalt is prepared by mixing an ethanol solution of 8-quinolinol and an aqueous solution of cobalt nitrate at a mass ratio of 2: 1. After heating and mixing at 50 ° C. for 10 minutes, the precipitate is collected and dried at 130 ° C. The one obtained from the above was used. FIG. 4 shows a TEM image of the cross section. In FIG. 4, the same structure as in FIG. 1 can be confirmed, but the grain size is about 20 nm, which is larger than that in Example 1.

(Comparative Example 3)
A fired sample was obtained in the same manner as in Comparative Example 1 except that cobalt stearate was not added. The molar ratio of the mixed solution was tetraethoxysilane: hexadecyltrimethylammonium chloride: water: sodium hydroxide = 1: 0.225: 125: 0.225. 0.396 g of the powder obtained by calcining was collected in a 50 ml beaker, 0.4 ml of a 170 mmol / L aqueous solution of cobalt nitrate and 8 ml of water were added, dried at 100 ° C. under vacuum, and calcined at 350 ° C. for 2 hours. .
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test.

(Comparative Example 4)
It was synthesized based on the method described in Japanese Patent No. 4614196. Tetraethoxysilane was added to a 200 ml beaker, and the stirrer was rotated at 600 rpm and stirred, and cobalt chloride dissolved in ethanol was added. Next, octylamine was added, and the mixture was stirred for 10 minutes. Then, an aqueous hydrochloric acid solution was added, and the mixture was further stirred for 1 hour. The molar ratio of the mixed solution was tetraethoxysilane: octylamine: ethanol: cobalt chloride: hydrochloric acid: water = 1: 0.34: 1.18: 0.0105: 0.034: 38. The solid product was separated from the obtained suspension by filtration, vacuum-dried at 100 ° C., and calcined at 600 ° C. for 1 hour to remove organic components.
Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test. FIG. 5 shows a TEM image of the cross section. No particles were observed.
(Comparative Example 5)
It was synthesized in the same manner as in Comparative Example 1 except that cobalt stearate was changed to cobalt chloride. The molar ratio of the mixed solution was such that tetraethoxysilane: hexadecyltrimethylammonium chloride: cobalt chloride: water: sodium hydroxide = 1: 0.225: 0.0106: such that the amount of Co in the synthesized product was 1 wt%. 125: 0.225. Table 1 shows the evaluation results of the synthesized products. Table 2 shows the results of the deodorizing test.

As shown in Tables 1 and 2, Examples 1 and 2 had higher acetaldehyde deodorizing performance, had equal or higher brightness than Comparative Example 1, and had low coloration. Had a degree. Also, the metal particle diameter was small. That is, it is understood that by adding the ligand component, the metal particle diameter is reduced, and the deodorizing performance with respect to acetaldehyde can be increased without lowering the brightness. In addition, since Example 3 had higher deodorizing performance of acetaldehyde, lightness equal to or higher than that of Comparative Example 5, and low chroma as compared with Comparative Example 5, the effect of the addition of the ligand component was supported. Was done. Furthermore, in Example 3, the cobalt particle ratio was extremely high as compared with Comparative Example 5, and it was found that by adding a ligand component, cobalt could be supported on silica in a particle state without being doped into silica.
Further, Comparative Example 2 had about the same deodorizing performance with respect to acetaldehyde as Examples 1 to 3. However, Comparative Example 2 had a lower metal particle ratio, a larger metal particle diameter, and lower brightness than Examples 1 and 2. That is, according to the method of the present invention, by adding a metal salt and a ligand component, when a complex of a metal and a ligand component is directly mixed with a surfactant without using a metal salt, In comparison, it is understood that the metal particle ratio can be increased, the metal particle diameter can be reduced, and the brightness can be improved.
In Comparative Example 3, since cobalt was introduced using an aqueous solution of cobalt nitrate after firing, cobalt was not doped into silica, and the metal particle ratio is considered to be 100%. However, in Comparative Example 3, the deodorizing performance was low under the condition of low concentration of acetaldehyde. Further, the metal particle diameter was large and the brightness was low. In Comparative Example 3, it is considered that the catalyst efficiency was lowered and the deodorizing performance was lowered because the metal particle diameter was large.
In Comparative Example 4, the deodorizing performance under high-concentration acetaldehyde conditions was lower than Examples 1 to 3. It is considered that the reason for this is that Comparative Example 4 had a low cobalt particle rate and was susceptible to catalyst poisoning.

Table 1
* 1) Extraction experiments were difficult because cobalt stearate did not dissolve in water, ethanol, etc.
* 2) Values were calculated assuming that the Co content = the amount of particles.
* 3) The presence of particles could not be confirmed from TEM.

Table 2 Deodorization test results

(TG-DTA)
In Example 1 and Comparative Example 1, TG-DTA measurement was performed using the sample before firing. For the measurement, TGDTA 7220 manufactured by Hitachi High-Tech Science Corporation was used. The measurement was performed at a temperature range of 50 to 600 ° C. and a heating rate of 2.5 ° C./min while flowing air at 100 ml / min.
The result of Example 1 is shown in FIG. 6, and the result of Comparative Example 1 is shown in FIG. In FIG. 6, peak A (313.8 ° C.) indicates the decomposition of the surfactant, and peak B (396.2 ° C.) indicates oxine cobalt (Co (ox), which is a complex of cobalt and 8-quinolinol. 2) shows the decomposition of 2). On the other hand, in FIG. 7, peak C (311.4 ° C.) indicates the decomposition of the surfactant, and peak D (421.5 ° C.) indicates the decomposition of cobalt stearate (C18Co).
That is, in Comparative Example 1, in addition to the peak of the surfactant (311.4 ° C.), a peak was observed at a decomposition temperature of 421.5 ° C. of cobalt stearate (C18Co). On the other hand, in Example 1, the peak of cobalt stearate was not observed, and the peak was at the decomposition temperature (311.4 ° C.) of oxine cobalt (Co (ox) 2), which is a complex of cobalt and 8-quinolinol. It was observed. That is, it was found that by adding 8-quinolinol, 8-quinolinol coordinated with cobalt derived from cobalt stearate to form a complex.
The results also indicate that cobalt stearate was converted to oxine cobalt with a lower decomposition temperature. This indicates that, in Example 1, the organic component can be removed from the cobalt-containing substance (complex) present in the precursor at a lower temperature during firing.

(Particle size distribution measurement)
Subsequently, in order to examine the change in particle size due to the addition of the ligand component, the following aqueous solutions (A) to (C) were prepared, and the particle size distribution was measured using ELSZ-2000 manufactured by Otsuka Electronics Co., Ltd. went. The RI of the dispersion medium (water) was set to 1.3328, the viscosity was set to 0.8878, the temperature was set to 25 ° C., and the measurement was performed using a quartz cell.
Aqueous solution (A): hexadecyl ammonium chloride: water = 0.225: 125
Aqueous solution (B): hexadecyl ammonium chloride: cobalt stearate: water = 0.225: 0.0106: 125
Aqueous solution (C): hexadecyl ammonium chloride: cobalt stearate: water: 8-quinolinol = 0.225: 0.0106: 125: 0.0319.

  FIG. 8 shows the results of the particle size distribution measurement. The average particle size of the micelles in the aqueous solution (A) was 1.4 nm. The average particle size of the micelles in the aqueous solution (B) was 143.7 nm. The average particle size of the micelles in the aqueous solution (C) was 22.6 nm. From the comparison between the aqueous solutions (B) and (C), it was confirmed that the size of micelles was significantly reduced by adding 8-quinolinol. This suggests that the addition of 8-quinolinol converts cobalt stearate to oxine cobalt, resulting in smaller micelles and a reduction in the particle size of the metal particles in the final porous silica. ing.

The particle size distribution was measured in the same manner using cobalt chloride instead of cobalt stearate. Specifically, the following aqueous solutions (D) and (E) were prepared, and the particle size distribution was measured.
Aqueous solution (D); hexadecyl ammonium chloride: cobalt chloride: water = 0.225: 0.0106: 125
Aqueous solution (E); hexadecyl ammonium chloride: cobalt chloride: water: 8-quinolinol = 0.225: 0.0106: 125: 0.0319.

  FIG. 9 shows the results of the particle size distribution measurement of the aqueous solutions (A), (D) and (E). As described above, the average particle size of the micelles in the aqueous solution (A) was 1.4 nm. On the other hand, the average particle size of the micelles in the aqueous solution (D) was 2.2 nm. The average particle size of the micelles in the aqueous solution (E) was 25.3 nm. The average particle size of the micelles in the aqueous solution (B) is almost the same as that in the aqueous solution (A). Since cobalt chloride is a soluble salt, in the aqueous solution (B), it is considered that cobalt is hardly taken into micelles. On the other hand, in the aqueous solution (C) to which 8-quinolinol was added, the average particle size was large. This is presumably because the addition of 8-quinolinol formed a water-insoluble complex, incorporated the cobalt component into the micelles, and increased the average particle size of the micelles.

Claims (9)

Mixing a surfactant, a metal salt, and a ligand component in an aqueous solution to form micelles containing a water-insoluble complex in which the ligand component is coordinated with the metal of the metal salt;
After the step of generating the micelles, a step of adding a silica source to the aqueous solution,
After the step of adding the silica source, a step of adding a basic aqueous solution to the aqueous solution,
Collecting the micelles after the step of adding the basic aqueous solution,
Baking the collected micelles to obtain porous silica,
A method for producing porous silica, comprising:   The method for producing porous silica according to claim 1, wherein the complexation constant of the insoluble complex is larger than the complexation constant of the metal salt.   The method for producing porous silica according to claim 1, wherein the metal of the metal salt is at least one selected from the group consisting of cobalt, zinc, silver, copper, and manganese.   The method for producing porous silica according to any one of claims 1 to 3, wherein the metal salt is a fatty acid metal salt.   The method for producing porous silica according to any one of claims 1 to 4, wherein the metal salt is a metal chloride.   The method for producing porous silica according to any one of claims 1 to 5, wherein the ligand component is a compound having an 8-quinolinol structure.   The method for producing porous silica according to any one of claims 1 to 6, wherein the surfactant includes an alkyl ammonium salt. A basic odor, acidic odor, or acetaldehyde deodorant comprising porous silica,
The porous silica, seen containing silica particles comprising primary particles in which the primary pores are formed, and a cobalt-containing particles carried on the silica particles,
The particle diameter of the cobalt-containing particles is less than 20 nm,
Cobalt content of the porous silica in is not less than 0.5 wt%,
Cobalt particle ratio in the porous silica state, and are 70% or more,
The porous silica has a deodorization rate in an acetaldehyde deodorization test of 66% or more (initial concentration of acetaldehyde 14 ppm, humidity 50%, 50 ml of deodorant in 500 ml of odor and 30 minutes later),
The brightness of the porous silica is 50 or more,
The silica particles have secondary pores consisting of particle gaps due to the bonding between the primary particles,
The primary pore has a pore diameter of 1 to 20 nm,
Deodorants. The deodorant according to claim 8, wherein the chroma of the porous silica is 17 or less.