Porous silica doped with multiple types of metals and containing high copper content

Abstract

The present invention addresses the problem of providing a porous silica exhibiting an excellent deodorizing effect with respect to sulfur-containing odors. As a means for solving said problem, the porous silica according to the present invention is doped with multiple types of metals including copper, and has a copper content of 10 wt% or more. Examples of the metals, besides copper, that the porous silica is doped with include iron, aluminum, etc.

Description

Multimetal-doped porous silica containing high copper content

[0001] The present invention relates to porous silica doped with multiple metals, including a high content of copper.

[0002] It is well known that porous silica has a large specific surface area and pore volume and is therefore used in various fields as an adsorbent, humidity control agent, catalyst support, etc. In recent years, various attempts have been made to enhance the functionality of porous silica, and the present inventors have reported in Patent Document 1, as one of their research results, that porous silica doped with a metal X, which is manganese or copper, exhibits a deodorizing effect against sulfur-containing odors.

[0003] The porous silica doped with a metal X, which is manganese or copper, reported by the present inventors in Patent Document 1 is expected to be used as a material for deodorizing sulfur-containing odors remaining in hair after a perm treatment performed using a sulfur-containing compound such as cysteamine as a reducing agent. However, in recent years, there has been a demand for porous silica with an even stronger effect.

[0004] Japanese Patent Application Laid-Open No. 2020-15640

[0005] Therefore, an object of the present invention is to provide porous silica that exhibits an excellent deodorizing effect against sulfur-containing odors.

[0006] As a result of intensive research conducted by the inventors in light of the above points, they discovered that by doping porous silica with multiple types of metals, including a high content of copper, it is possible to achieve an excellent deodorizing effect against sulfur-containing odors, and that the deodorizing effect that has deteriorated with use can be restored by rinsing with water.

[0007] The porous silica of the present invention, which has been made based on the above findings, is, as set forth in claim 1, porous silica doped with multiple metals including copper, wherein the copper content is 10 wt % or more. Furthermore, the porous silica of claim 2 is the porous silica of claim 1, wherein the metal other than copper doped into the porous silica is at least one selected from the group consisting of iron, aluminum, zirconium, cobalt, and manganese. Furthermore, the porous silica of claim 3 is the porous silica of claim 1, wherein the metal other than copper doped into the porous silica is iron and / or aluminum. Furthermore, the porous silica of claim 4 is the porous silica of claim 1, wherein the content of the metal other than copper doped into the porous silica is 0.5 to 10 wt %. Furthermore, the deodorant of the present invention, as set forth in claim 5, contains the porous silica of claim 1 as an active ingredient.

[0008] According to the present invention, it is possible to provide porous silica that exhibits an excellent deodorizing effect against sulfur-containing odors.

[0009] 1 is a chart showing the diffraction peak spectra of metal-doped mesoporous silica produced in Example 1, Example 6, and Comparative Example 1 in the Examples.

[0010] The porous silica of the present invention is a porous silica doped with multiple metals including copper, and the copper content is 10 wt % or more. Here, "metal-doped porous silica" means porous silica in which a metal is incorporated by chemical bonding into the inorganic network consisting of siloxane bonds that constitutes the porous silica.

[0011] In the porous silica of the present invention, the content of copper doped in the porous silica is 10 wt % or more, and the upper limit thereof is, for example, 25 wt %.

[0012] Examples of metals other than copper that can be doped into porous silica include iron, aluminum, zirconium, cobalt, and manganese. These may be used alone or in combination of two or more. The content of the metal other than copper that can be doped into porous silica is, for example, 0.5 to 10 wt % (when two or more metals are used in combination, the total content of each metal). When two or more metals are used in combination, the content ratio between the metals may be, for example, 0.1 to 10 times the content of one metal relative to the content of the other metal.

[0013] The upper limit of the total amount of copper and metals other than copper doped into the porous silica is, for example, 30 wt %. Porous silica doped with a metal exceeding 30 wt % may be difficult to manufacture.

[0014] An example of porous silica is mesoporous silica in which pores (mesopores) having a diameter of 2 to 50 nm are regularly arranged.

[0015] The specific surface area of ​​the porous silica is, for example, 500 to 2000 m ２ / g is preferable in terms of maintaining durability.

[0016] Mesoporous silica doped with multiple metals including copper in a content of 10 wt % or more can be produced according to the following method, which is known per se, for example, as described in JP-A-2020-15640.

[0017] (Step 1) First, a surfactant and raw materials for doping mesoporous silica with multiple metals including copper in a content of 10 wt % or more are dissolved in a solvent, and the mixture is stirred at 10 to 200°C for 0.1 to 10 hours, for example, to form micelles in the surfactant.

[0018] The amount of surfactant dissolved in the solvent is, for example, 10 to 400 mmol / L, preferably 50 to 150 mmol / L, or, for example, 0.01 to 5.0 mol, preferably 0.05 to 1.0 mol, per 1 mol of the silica raw material added in Step 2 described below.

[0019] The surfactant may be a cationic surfactant, an anionic surfactant, or a nonionic surfactant, but is preferably a cationic surfactant such as an alkylammonium salt. The alkylammonium salt preferably has an alkyl group having 8 or more carbon atoms, and from the perspective of industrial availability, an alkyl group having 12 to 18 carbon atoms is more preferred. Specific examples of alkylammonium salts 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, and ditetradecyldimethylammonium chloride. The surfactant may be used alone or in combination of two or more.

[0020] The amount of raw materials (total amount of each raw material) dissolved in the solvent for doping mesoporous silica with multiple metals including copper in a content of 10 wt % or more is, for example, 0.001 to 0.5 mol, preferably 0.01 to 0.3 mol, per 1 mol of the silica raw material added in step 2 described below.

[0021] As a raw material for doping with copper, copper nitrate or copper chloride is preferably used (these may be used alone or in combination). As a raw material for doping with iron, iron chloride is preferably used. As a raw material for doping with aluminum, aluminum chloride is preferably used. As a raw material for doping with zirconium, zirconium oxychloride is preferably used. As a raw material for doping with cobalt, cobalt nitrate is preferably used. As a raw material for doping with manganese, manganese chloride is preferably used.

[0022] The solvent may be, for example, water, or a mixed solvent of water and a water-soluble organic solvent such as methanol, ethanol, diethylene glycol, or glycerin.

[0023] (Step 2) Next, the silica raw material is dissolved in the solution obtained in step 1 in which the surfactant forms micelles, for example, at room temperature, and the mixture is stirred until homogenous, allowing the silica raw material to accumulate on the surface of the surfactant micelles. The amount of silica raw material dissolved in the solution is, for example, 0.2 to 1.8 mol / L. Alternatively, when water or a mixed solvent of water and a water-soluble organic solvent is used as the solvent, the amount of silica raw material dissolved is, for example, 0.001 to 0.05 mol per 1 mol of water.

[0024] The silica raw material is not particularly limited as long as it forms an inorganic network consisting of siloxane bonds that constitute mesoporous silica by dehydration condensation. Specific examples of silica raw materials include tetraalkoxysilanes such as tetraethoxysilane, tetramethoxysilane, and tetra-n-butoxysilane, and sodium silicate. Tetraalkoxysilane is preferred, and tetraethoxysilane is more preferred. The silica raw materials may be used alone or in combination of two or more.

[0025] (Step 3) Next, the silica raw material accumulated on the surface of the surfactant micelles is dehydration-condensed to form an inorganic network composed of siloxane bonds that constitute mesoporous silica, and multiple types of metals, including copper, are incorporated into the inorganic network by chemical bonding. The dehydration-condensation of the silica raw material can be carried out, for example, by adding a basic aqueous solution to the system to raise the pH, followed by stirring at room temperature for at least one hour. The basic aqueous solution is preferably added so that the pH is 6 to 14 immediately after addition, and more preferably 8 to 12. If only an amount of basic aqueous solution is added that results in a pH below 6 immediately after addition, the dehydration-condensation of the silica raw material may be slow to proceed, or the metal may dissolve again even after being incorporated into the inorganic network. Specific examples of basic aqueous solutions include aqueous sodium hydroxide, aqueous potassium hydroxide, aqueous sodium carbonate, and aqueous ammonia, with aqueous sodium hydroxide being preferred. The basic aqueous solutions may be used alone or in combination of two or more.

[0026] (Step 4) Finally, the surfactant micelles obtained in step 3, which form an inorganic network on the surface of the mesoporous silica, comprised of siloxane bonds and incorporating multiple metals, including copper, by chemical bonding, are filtered and recovered as a precipitate, and the resulting mixture is dried, for example, at 30 to 120°C for 10 to 48 hours, followed by calcination at 400 to 600°C for 1 to 10 hours, to obtain mesoporous silica doped with multiple metals, including copper, in a desired content of 10 wt% or more. Rapid temperature rise from the drying temperature to the calcination temperature can result in the precipitation and contamination of metal oxide (e.g., copper oxide) particles, so the temperature should be raised slowly, preferably at a rate of 1°C / min or less, more preferably 0.5°C / min or less, and even more preferably 0.3°C / min or less. The mesoporous silica thus obtained, doped with multiple metals including copper in a content of 10 wt % or more, may be pulverized in a mixer or mill as necessary to have a desired particle size (for example, a median diameter of 0.01 to 100 μm).

[0027] The addition of raw materials to the system for doping mesoporous silica with multiple metals including copper at a content of 10 wt % or more is not limited to the mode of dissolving in a solvent together with a surfactant in step 1 above, but may be the mode of dissolving in a solution in step 2 or 3, as long as the silica raw material is dissolved in the solution until the formation of an inorganic network consisting of siloxane bonds that constitutes mesoporous silica by dehydration condensation in step 3 is completed.

[0028] In step 2, instead of dissolving the silica raw material in the solution in which the surfactant forms micelles obtained in step 1, a hydrolyzed solution of the silica raw material prepared from the silica raw material and an aqueous solution of an inorganic acid (for example, hydrochloric acid having a concentration of 0.001 to 0.1 M) may be added to the solution in which the surfactant forms micelles.

[0029] The porous silica of the present invention exhibits excellent deodorizing effect against sulfur-containing odors, since it is doped with copper in an amount of 10 wt% or more and metals other than copper.Therefore, the porous silica of the present invention can be used as a material for deodorizing the sulfur-containing odor remaining in hair after perm treatment using a sulfur-containing compound such as cysteamine as a reducing agent.In addition, after exerting its deodorizing effect, the porous silica of the present invention can be washed with water to restore the deodorizing effect that has deteriorated with use, so it can be molded into a filter shape or pellet shape by a method known per se and used repeatedly.

[0030] The present invention will be described in detail below with reference to examples, but the present invention should not be construed as being limited to the following description.

[0031] Example 1: Preparation of mesoporous silica doped with 10 wt% copper and 5 wt% iron (Part 1) Copper chloride, a raw material for doping mesoporous silica with copper, and iron chloride, a raw material for doping mesoporous silica with iron, were dissolved in water as a solvent and stirred at room temperature for 30 minutes. Tetraethoxysilane, a silica raw material, was further dissolved and stirred until homogeneous. This solution was then added to a solution prepared by dissolving hexadecyltrimethylammonium chloride, a surfactant, in water as a solvent and stirring at room temperature for 30 minutes. The solution was then stirred at room temperature for 30 minutes. A basic aqueous solution of sodium hydroxide was then added to the solution so that the pH immediately after addition was 11.5, and the mixture was stirred at room temperature for 3.5 hours. The resulting precipitate was collected by filtration and dried at 50°C for 24 hours. The temperature was then increased at a rate of 0.25°C / min and calcined at 500°C for 1 hour, yielding the target product as a green powder.

[0032] The amounts of hexadecyltrimethylammonium chloride as a surfactant, copper chloride as a raw material for doping mesoporous silica with copper, iron chloride as a raw material for doping mesoporous silica with iron, and water (including water constituting the sodium hydroxide aqueous solution) as a solvent per 1 mol of tetraethoxysilane as the silica raw material were as follows: hexadecyltrimethylammonium chloride: 0.225 mol, copper chloride: 0.1202 mol, iron chloride: 0.0683 mol, water: 125 mol. To prepare the sodium hydroxide aqueous solution as a basic aqueous solution, 0.8 mol of sodium hydroxide was used per 1 mol of tetraethoxysilane as the silica raw material.

[0033] Example 2: Preparation of mesoporous silica doped with 10 wt% copper and 5 wt% iron (Part 2) Hexadecyltrimethylammonium chloride as a surfactant, copper chloride as a raw material for doping mesoporous silica with copper, and iron chloride as a raw material for doping mesoporous silica with iron were dissolved in water as a solvent and stirred at room temperature for 30 minutes. Tetraethoxysilane as a silica raw material was then further dissolved and stirred until homogeneous. Next, a basic aqueous solution of sodium hydroxide was added so that the pH immediately after addition was 11.5, and the mixture was stirred at room temperature for 3.5 hours. The resulting precipitate was collected by filtration and dried at 50°C for 24 hours. The temperature was then increased at a rate of 0.25°C / min and calcined at 500°C for 1 hour, yielding the target product as a green powder. The amounts of hexadecyltrimethylammonium chloride used as a surfactant, copper chloride used as a raw material for doping copper into mesoporous silica, iron chloride used as a raw material for doping iron into mesoporous silica, tetraethoxysilane used as a silica raw material, sodium hydroxide, and water used as a solvent (including water constituting the sodium hydroxide aqueous solution) were the same as those used in Example 1.

[0034] Example 3: Preparation of mesoporous silica doped with 10 wt% copper and 5 wt% iron (Part 3). Tetraethoxysilane (a silica raw material) was dissolved in 0.01 M hydrochloric acid and stirred until homogeneous. This hydrolyzed solution of tetraethoxysilane was added to a solution prepared by dissolving hexadecyltrimethylammonium chloride (a surfactant), copper chloride (a raw material for doping mesoporous silica with copper), and iron chloride (a raw material for doping mesoporous silica with iron) in water as a solvent and stirring at room temperature for 30 minutes. The solution was then stirred at room temperature for 30 minutes. A basic aqueous solution of sodium hydroxide was then added to the solution so that the pH immediately after addition was 11.5, and the mixture was stirred at room temperature for 24 hours. The resulting precipitate was collected by filtration, dried at 100°C for 24 hours, and then heated at a rate of 0.25°C / min and calcined at 500°C for 1 hour to obtain the target product as a green powder. The amounts of hexadecyltrimethylammonium chloride used as a surfactant, copper chloride used as a raw material for doping copper into mesoporous silica, iron chloride used as a raw material for doping iron into mesoporous silica, tetraethoxysilane used as a silica raw material, sodium hydroxide, and water used as a solvent (including water constituting the sodium hydroxide aqueous solution and water constituting hydrochloric acid) were the same as those used in Example 1.

[0035] Examples 4 to 10: Preparation of mesoporous silica doped with various amounts of copper, iron, and / or aluminum Mesoporous silica doped with various amounts of copper, iron, and / or aluminum was prepared by the same method as that employed in Example 1. Aluminum chloride was used as the raw material for doping aluminum into mesoporous silica.

[0036] Comparative Example 1: Preparation of mesoporous silica doped with only copper at a content of 15 wt %. The same method as used in Example 1 was used to prepare the mesoporous silica.

[0037] Comparative Example 2: Preparation of mesoporous silica doped with only 5 wt% iron. The same method as in Example 1 was used to prepare the mesoporous silica.

[0038] Comparative Example 3: Preparation of mesoporous silica doped with only 2 wt% aluminum. The same method as in Example 1 was used to prepare the mesoporous silica.

[0039] Comparative Example 4: Preparation of mesoporous silica doped with 4 wt% copper and 5 wt% iron. The same method as in Example 1 was used to prepare the mesoporous silica.

[0040] Comparative Example 5: Preparation of mesoporous silica doped with 2 wt% copper and 2 wt% aluminum. The same method as in Example 2 was used to prepare the mesoporous silica.

[0041] Comparative Example 6: Preparation of mesoporous silica doped with 8 wt% copper and 2 wt% aluminum. The same method as in Example 1 was used to prepare the mesoporous silica.

[0042] The metal-doped mesoporous silicas produced in Examples 1 to 10 and Comparative Examples 1 to 6 are summarized in Table 1.

[0043]

[0044] The specific surface area and pore diameter were calculated by BJH calculation using a BELSORP MAX II model manufactured by Microtrackbell, Inc., where the nitrogen gas adsorption isotherm was measured at liquid nitrogen temperature using a multipoint method. The doping of the mesoporous silica with a metal was confirmed by analysis using an X-ray diffraction (XRD) device (Rigaku Corporation, SmartLab) to determine the absence of diffraction peaks attributable to metals not doped into the mesoporous silica (diffraction peaks of metal oxide particles formed and precipitated from metals not doped into the mesoporous silica). For example, the diffraction peak spectra of the copper- and iron-doped mesoporous silica produced in Example 1, the copper- and aluminum-doped mesoporous silica produced in Example 6, and the copper-only doped mesoporous silica produced in Comparative Example 1 are shown in Figure 1. The diffraction peak spectra of the copper- and iron-doped mesoporous silica produced in Example 1 and the copper- and aluminum-doped mesoporous silica produced in Example 6 do not contain the diffraction peaks attributable to copper not doped into the mesoporous silica (diffraction peaks of copper oxide particles generated and precipitated from the copper not doped into the mesoporous silica) that are present in the diffraction peak spectrum of the copper-only doped mesoporous silica produced in Comparative Example 1.

[0045] As shown in Table 1, the diffraction peak spectra of the copper- and iron-doped mesoporous silica produced in Example 4 and the copper- and aluminum-doped mesoporous silica produced in Example 7 do not contain any diffraction peaks attributable to copper not doped into the mesoporous silica, which are present in the diffraction peak spectrum of the copper-only mesoporous silica produced in Comparative Example 1. This means that, by doping iron with copper in Example 4 and by doping aluminum with copper in Example 7, it was possible to dope the mesoporous silica with 15 wt% copper, respectively, but that in Comparative Example 1, in which neither iron nor aluminum was doped with copper, it was not possible to dope the mesoporous silica with 15 wt% copper. This indicates that when doping mesoporous silica with a copper content of 10 wt% or more, by doping iron or aluminum with copper as a metal other than copper, it is possible to prevent copper oxide particles from being generated and precipitated from the copper not doped into the mesoporous silica and becoming mixed in.

[0046] Evaluation Experiment 1: Deodorizing Effect of Metal-Doped Mesoporous Silica Produced in Examples 1-10 and Comparative Examples 1-6 on Hydrogen Sulfide (Experimental Method) 0.2 g of each of the metal-doped mesoporous silicas produced in Examples 1-10 and Comparative Examples 1-6, 19.8 mL of water, and 26.4 g of 2 mm diameter alumina balls were placed in a 30 mL polypropylene (PP) container and wet-milled at 250 rpm for 2 hours to prepare a slurry. 1 mL of the prepared slurry was evenly distributed over 50 mg of silica wool, which was then dried at 160°C for 1 hour to produce silica wool surface-treated with metal-doped mesoporous silica. Two of the prepared silica wool surface-treated with metal-doped mesoporous silica were uniformly packed into a 1 cm diameter Teflon tube to a total length of 2 cm. A tube packed with silica wool surface-treated with metal-doped mesoporous silica was passed through at a flow rate of 1 L / min with 18 ppm hydrogen sulfide prepared using a permeator (PD-1C, manufactured by Gastec Corporation; the same applies hereinafter). The odor was collected at the outlet every 3 minutes, and the concentration of hydrogen sulfide contained in the odor was measured using a detector tube (Gastec Corporation 4LK, 4LB, or 4L, as appropriate; the same applies hereinafter). This measurement was continued until the concentration of hydrogen sulfide contained in the odor exceeded 9 ppm (i.e., until the deodorization rate fell below 50%), and the total amount of hydrogen sulfide adsorbed by the metal-doped mesoporous silica up to that point was determined. The deodorizing effect of the metal-doped mesoporous silica against hydrogen sulfide was evaluated based on the deodorizing capacity calculated by dividing the total amount of hydrogen sulfide adsorbed by the amount of metal-doped mesoporous silica supported on the silica wool. The total amount of hydrogen sulfide adsorbed into the metal-doped mesoporous silica was determined every three minutes by converting 3 L of the hydrogen sulfide concentration, calculated using the formula: 18 ppm - ((hydrogen sulfide concentration at the start of the three-minute count + hydrogen sulfide concentration at the end of the three-minute count) / 2), into mass and integrating it (in the first measurement, the "hydrogen sulfide concentration at the start of the three-minute count" was 18 ppm, and in the second and subsequent measurements, the "hydrogen sulfide concentration at the start of the three-minute count" was the "hydrogen sulfide concentration at the end of the three-minute count" in the previous measurement).The amount of metal-doped mesoporous silica supported on the silica wool was calculated by subtracting the weight (100 mg) of two pieces of silica wool before surface treatment from the weight of two pieces of silica wool whose surfaces had been treated with metal-doped mesoporous silica.

[0047] The experimental results are shown in Table 2. As is clear from Table 2, the metal-doped mesoporous silica produced in Examples 1 to 10 exhibited excellent deodorizing effects against hydrogen sulfide because they were doped with 10 wt % or more copper and iron or aluminum as a metal other than copper. The inferior deodorizing effect against hydrogen sulfide of the mesoporous silica doped only with copper produced in Comparative Example 1 was thought to be due to the generation and precipitation of copper oxide particles from the copper that was not doped into the mesoporous silica, as described above. However, the doping of iron or aluminum as a metal other than copper together with copper prevented the generation and precipitation of copper oxide particles, thereby significantly improving the deodorizing effect against hydrogen sulfide (for example, the deodorizing effects of the mesoporous silica doped with copper and iron produced in Example 4 and the mesoporous silica doped with copper and aluminum produced in Example 7 were four or more times greater than the deodorizing effect of the mesoporous silica doped with copper only produced in Comparative Example 1). This was an unexpected result for the inventors.

[0048]

[0049] Evaluation Experiment 2: Effect of Water Washing to Restore Deteriorated Deodorizing Effect Due to Use of Metal-Doped Mesoporous Silica Produced in Examples 1 to 10 (Experimental Method) 1 g of each of the metal-doped mesoporous silica produced in Examples 1 to 10 was placed in a 200 mL recovery flask, and 18 ppm hydrogen sulfide prepared in a permeator was sprayed onto the flask at a flow rate of 1 L / min overnight, thereby causing hydrogen sulfide to be adsorbed onto the metal-doped mesoporous silica. During the experiment, the recovery flask was rocked every few hours to agitate the metal-doped mesoporous silica in the flask, ensuring that hydrogen sulfide was evenly adsorbed. The next morning, the hydrogen sulfide concentration in the odorous gas in the recovery flask was measured every few hours using a detector tube. Since the hydrogen sulfide concentration remained constant, it was confirmed that the deodorizing effect of the metal-doped mesoporous silica against hydrogen sulfide had been broken through. The metal-doped mesoporous silica in the recovery flask was then washed by adding it to 300 mL of pure water and stirring it at 500 rpm for 3 hours, and then collected by suction filtration. The metal-doped mesoporous silica thus collected was dried at 160°C for 1 hour, and the deodorizing capacity was calculated according to the evaluation method used in Evaluation Experiment 1. Furthermore, 10 to 20 mg of the metal-doped mesoporous silica was accurately weighed out before and after washing with water, and 8 mL of 2 M hydrochloric acid was added and heated on a hot plate at 120°C for 1 hour to dissolve the silica. Ultrapure water was then added to make up to 250 mL, and the sulfur concentration in the resulting solution was measured using an inductively coupled plasma optical emission spectrometer (ICP-OES, manufactured by Thermo Scientific). Based on the measurement results, the sulfur contents of the metal-doped mesoporous silica before and after washing with water were calculated.

[0050] (Experimental Results) It was found that the deodorizing effect of the metal-doped mesoporous silica prepared in Examples 1 to 10, which had deteriorated with use, could be restored by rinsing with water. The deodorizing capacity after rinsing with water was 13.8 μg / mg for the mesoporous silica doped with 10 wt% copper and 5 wt% iron prepared in Example 1, and 11.9 μg / mg for the mesoporous silica doped with 10 wt% copper and 2 wt% aluminum prepared in Example 6. Both were higher than the deodorizing effect of the mesoporous silica doped with only 15 wt% copper prepared in Comparative Example 1 before use (8.3 μg / mg, as shown in Table 2). Furthermore, for example, the sulfur content of the mesoporous silica doped with 10 wt % copper and 5 wt % iron produced in Example 1 was 1.6 wt % before washing with water and 0.6 wt % after washing with water, and 63% of the sulfur content before washing was desorbed by washing with water. The mechanism by which such an effect is observed in the metal-doped mesoporous silica produced in Examples 1 to 10 is not entirely clear, but the inventors believe that the metal-doped mesoporous silica produced in Examples 1 to 10, for example, has a hydrophilized surface, and therefore the water used for washing easily desorbs hydrogen sulfide adsorbed on the hydrogen sulfide adsorption sites, thereby regenerating the hydrogen sulfide adsorption sites or forming new hydrogen sulfide adsorption sites, thereby restoring the deteriorated deodorizing effect.

[0051] Examples 11 to 18: Production of mesoporous silica doped with various amounts of copper and iron Mesoporous silica doped with the following amounts of copper and iron were produced by the same method as used in Example 1, and their deodorizing effect against hydrogen sulfide was evaluated by the method in Evaluation Experiment 1, and the effect of rinsing with water to restore the deodorizing effect that had deteriorated due to use was evaluated by the method in Evaluation Experiment 2.The copper- and iron-doped mesoporous silica produced in each of the Examples had the same effect as the copper- and iron-doped mesoporous silica produced in Examples 1, 4, and 5. (Example 11) Copper content: 11 wt%, iron content: 5 wt% (Example 12) Copper content: 12 wt%, iron content: 5 wt% (Example 13) Copper content: 13 wt%, iron content: 5 wt% (Example 14) Copper content: 14 wt%, iron content: 5 wt% (Example 15) Copper content: 16 wt%, iron content: 5 wt% (Example 16) Copper content: 17 wt%, iron content: 5 wt% (Example 17) Copper content: 18 wt%, iron content: 5 wt% (Example 18) Copper content: 19 wt%, iron content: 5 wt%

[0052] Examples 19 to 29: Preparation of mesoporous silica doped with various amounts of copper and aluminum Mesoporous silica doped with the following amounts of copper and aluminum was prepared by the same method as used in Example 1, and the deodorizing effect against hydrogen sulfide was evaluated by the method of Evaluation Experiment 1, and the effect of rinsing with water to restore the deodorizing effect that had deteriorated due to use was evaluated by the method of Evaluation Experiment 2. The copper- and aluminum-doped mesoporous silica prepared in all of these Examples had the same effect as the copper- and aluminum-doped mesoporous silica prepared in Examples 6 and 7. Aluminum chloride was used as the raw material for doping aluminum into the mesoporous silica. (Example 19) Copper content: 10 wt%, aluminum content: 5 wt% (Example 20) Copper content: 10 wt%, aluminum content: 8 wt% (Example 21) Copper content: 11 wt%, aluminum content: 2 wt% (Example 22) Copper content: 12 wt%, aluminum content: 2 wt% (Example 23) Copper content: 13 wt%, aluminum content: 2 wt% (Example 24) Copper content: 14 wt%, aluminum content: 2 wt% (Example 25) Copper content: 16 wt%, aluminum content: 2 wt% (Example 26) Copper content: 17 wt%, aluminum content: 2 wt% (Example 27) Copper content: 18 wt%, aluminum content: 2 wt% (Example 28) Copper content: 19 wt%, aluminum content: 2 wt% (Example 29) Copper content: 20 wt%, aluminum content: 2 wt%

[0053] INDUSTRIAL APPLICABILITY The present invention has industrial applicability in that it can provide porous silica that exhibits an excellent deodorizing effect against sulfur-containing odors.

Claims

1. Porous silica doped with multiple metals including copper, the copper content being 10 wt % or more.

2. The porous silica according to claim 1, wherein the metal other than copper doped into the porous silica is at least one selected from the group consisting of iron, aluminum, zirconium, cobalt, and manganese.

3. The porous silica according to claim 1, wherein the metal other than copper doped into the porous silica is iron and / or aluminum.

4. The porous silica according to claim 1, wherein the content of the metal other than copper doped in the porous silica is 0.5 to 10 wt %.

5. A deodorizer containing the porous silica according to claim 1 as an active ingredient.

Images