JP4708857B2 - Molded body, method for producing the same, and method for promoting oxidation reaction using the same - Google Patents

Description

The present invention relates to a molded article suitable for oxidizing an oxidizable substance, a method for producing the same, and a method for promoting an oxidation reaction using the molded article. In particular, the present invention relates to a gas, or a dust or mist in a gas. The present invention relates to a molded article containing an active negative charge oxygen atom suitable for oxidizing an oxidizable substance such as a chemical spore or a mold spore, a production method thereof, and a method for promoting an oxidation reaction using the molded article.

Some chemical substances in the air not only cause direct damage to the human body, but also dissolve in soil and water resources and have a great impact on the global environment. Conventionally, these harmful chemical substances have been separated and removed from the air by adsorption onto activated carbon or absorption into a liquid layer using an exclusion tower. In addition, mold spores that exist in the air as well as the above-mentioned chemical substances and damage human bodies, building materials or foods have been separated and removed from the air in the same manner as chemical substances.

However, such a method merely moves the chemical substance from the air to the solid phase or liquid phase, and it cannot be said that the harmfulness of the chemical substance is essentially eliminated. Mold spores cannot be killed by the above method, and the harmfulness cannot be essentially eliminated.

As an effective method for eliminating the harmfulness of chemical substances or mold spores, there are oxidation or decomposition treatment by combustion or ultraviolet irradiation, etc., but such a method uses a large amount of energy such as heat and light. Consumption increases the load on the global environment in another way.

The harmfulness of chemical substances in the air has been considered to be a problem for waste in the mining industry or exhaust gas of automobiles, but recently, volatile organic substances (VOC) and tobacco smoke generated from residential building materials. It has come to be regarded as a problem in familiar materials such as. In addition, mold spores are also regarded as a problem because mold can cause serious health damage.

As a method of eliminating the harmfulness of chemical substances or mold spores that have become familiar, it is desirable to use a treatment method that is as simple as possible. For example, an oxidation treatment method using oxygen in the air is considered suitable. However, it is necessary to activate relatively stable oxygen molecules in the air in order to be usable as an oxidizing agent.

In order to activate oxygen to produce so-called active oxygen, methods such as discharge plasma, combustion, and ultraviolet irradiation are used. Either method requires excessive energy, or always irradiates light containing ultraviolet rays such as sunlight. It must be a simple treatment method.

On the other hand, the oxygen ion radicals of O ₂ ⁻ and O ⁻ are one kind of active oxygen, and are known to play an important role in the oxidation process of organic substances and inorganic substances. In addition, extensive research has been conducted on O ₂ ⁻ adsorbed on the solid surface of an oxide compound (see Non-Patent Document 1).
J. et al. H. Lunsford, Catal. Rev. 8, 135, 1973, M.M. Che and A.A. J. et al. Tench, Adv. Catal, 32, 1, 1983.

In this research, O ₂ ⁻ is created by irradiating the surface of an oxide compound with high-energy radiation such as γ rays.

RO ₂ (R = alkali metal) is known as a crystal having O ₂ ⁻ as a constituent anion. However, since these compounds are easily decomposed at a low temperature of 300 ° C. or lower, oxidation promoters and sterilizers are used. It cannot be used for materials.

In 1970, H.C. B. Bartl et al., In 12CaO · 7Al ₂ O ₃ (hereinafter referred to as C ₁₂ A ₇ ) crystal, 2 out of 66 oxygen atoms in a unit cell containing 2 molecules are not included in the network, It claims to exist as “free oxygen” in the existing space in the cage (see Non-Patent Document 2).
H. B. Bartl and T.W. Scheller, Neues Jarhrb. Mineral. , Monash. 1970, 547.

Moreover, Hosono et al. 1 × 10 ¹⁹ pieces / cm in a C ₁₂ A ₇ crystal synthesized by solid phase reaction in air at a temperature of 1200 ° C. using CaCO ₃ and Al ₂ O ₃ or Al (OH) ₃ as raw materials. It was discovered from electron spin resonance measurement that about ³ O ₂ ⁻ was included, and a model was proposed in which a part of free oxygen exists in the gauge in the form of O ₂ ⁻ (non-patent document). Reference 3).
H. Hosono and Y. Abe, Inorg. Chem. 26, 1193, 1997.

C ₁₂ A ₇ is a stable oxide having a melting point of 1415 ° C. If it increases the amount of O ₂ ^{− included} and can be reversibly taken up and released, it can be used as an oxidation promoter or sterilizer. Can be expected to open up applications.

Hosono et al. Further studied C ₁₂ A ₇ that includes O ₂ ⁻ , and used CaCO ₃ , Ca (OH) ₂ or CaO, and Al ₂ O ₃ or Al (OH) ₃ as raw materials. O ₂ ⁻ and O ⁻ which are active oxygen species are obtained by baking to 1200 ° C. or more and less than 1415 ° C. in a dry oxidation atmosphere having an oxygen partial pressure of 10 ⁴ Pa or more and a water vapor partial pressure of 10 ² Pa or less to cause a solid phase reaction. C ₁₂ A ₇ which is included at a high concentration of 10 ²⁰ pieces / cm ³ or more is obtained (see Patent Document 1).
Japanese Patent Laid-Open No. 2002-3218.

However, when C ₁₂ A ₇ containing active oxygen species at a high concentration found by Hosono et al. Is used as it is, for example, O ₂ ⁻ or O ⁻ having a negative charge is solidified while being heated to a high temperature of 700 ° C. or higher. In order to draw out to the outside, it is necessary to apply an electric field, so that it has been difficult to apply to a simple treatment method of chemical substances or mold spores.

The present invention has been made in view of the above-described state of the art, and active oxygen that is stably included and stored (hereinafter simply referred to as “encapsulation”) in a C ₁₂ A ₇ solid is treated at room temperature. Provided are a material and a treatment method for efficiently oxidizing and removing the chemical substance by promoting the oxidation reaction of harmful chemical substances in the air or mold spores by being effectively used under normal pressure. It is for the purpose.

That is, the present invention contains 85% by volume or more of crystalline calcium aluminate represented by a composition formula of 12CaO · 7Al ₂ O ₃ and containing 1 × 10 ¹⁹ negative-charge oxygen atoms (O ⁻ ) or more / cm ^3. And it is a molded object characterized by relative density being 55 to 85%.

The present invention is preferably the above-mentioned formed body having a honeycomb structure.

The present invention is preferably the above-mentioned molded product which is formed in a film shape on a substrate.

In the present invention, a raw material powder having a Ca: Al molar ratio of 0.70: 1 to 1.40: 1 is molded to have a relative density of 50 to 80%, and then an oxygen partial pressure of 4 × 10 ^{4 is used.} In the method for producing a molded body, the heating is performed at 1000 ° C. to 1200 ° C. in an atmosphere of Pa or higher.

The present invention is a method for promoting an oxidation reaction, characterized in that an oxidizable substance is brought into contact with the molded article in an atmosphere containing 1% by volume or more of oxygen under a condition of 5 to 300 ° C.

Since the molded product of the present invention can generate active oxygen on the solid surface and / or in the air at a relatively low temperature of normal temperature to 300 ° C. and normal pressure as described later, for example, harmful in the air. It can be suitably used for applications such as easy oxidation, decomposition and removal of chemical substances, mold spores and the like.

Moreover, the manufacturing method of the molded object of this invention has the characteristic which can obtain the molded object with the said characteristic reliably and stably.

In addition, since the oxidation reaction promoting method of the present invention uses the molded article having the characteristics described above, it exhibits the characteristic that active oxygen can be generated at a relatively low temperature of normal temperature to 300 ° C. and normal pressure, compared with the prior art. Even under extremely mild conditions, it is possible to reliably promote the desired oxidation reaction.

The present inventors have, C ₁₂ O in A ₇ ^- or O ₂ ^- result of variously studied for the purpose of oxidizing the harmful oxidizable substances utilizing, O ^- seems has an important role In addition, if C ₁₂ A ₇ is used as it is, O ⁻ is stably embedded in the inside, and O ⁻ cannot be extracted to the outside unless an electric field is applied at a high temperature of 700 ° C. or higher, but the relative density is 55 to 85. %, It is possible to take out O ⁻ to the outside when the atmosphere is under specific conditions, and at 5 to 300 ° C. and 0.8 to 1.5 atm, which is milder than that of the prior art. The inventors have obtained the knowledge that an oxidizing substance can be oxidized and rendered harmless, and have reached the present invention.

That is, the present invention is a crystalline material represented by a composition formula of C ₁₂ A ₇ and containing 1 × 10 ¹⁹ atoms / cm ³ or more of negatively charged oxygen atoms (which represents O ⁻ based on the reason described later). The molded body is characterized in that it contains 85% by volume or more of calcium aluminate and has a relative density of 55 to 85%. When the above configuration is satisfied, the oxidizable substance can be easily oxidized even at a relatively low temperature (about 5 to 300 ° C.) near normal temperature and under normal pressure (0.8 to 1.5 atm).

O without the relatively low temperatures, yet electric field near room temperature ^- for reasons that can oxidize oxidizable substances out of the interior C ₁₂ A _7, the present inventors have molded a relative density of 55 to 85% When placed in an atmosphere containing a predetermined amount of oxygen as a body, the reaction represented by the following formula occurs between O ⁻ contained in C ₁₂ A ₇ and oxygen in the atmosphere, so that O ⁻ It is inferred that it can contact and react with oxidizable substances.
4O ^- (internal) + _{O 2} (in the atmosphere) → 2O ₂ ^- (internal) + 2O ^- (surface)
Incidentally, O ^- contact with oxidizable substances, although loss of negative charge in the C ₁₂ A ₇ is generated by reacting, C ₁₂ oxidizable substance and O in the A ₇ surface ^- a result of the reaction (oxidation) of The surplus electrons (e ⁻ ) are considered to be compensated by exchanging electrons as shown in the following formula with O ₂ ⁻ in C ₁₂ A ₇ .
O ₂ ^- (internal) + 3e ^- → 2O ^2- (internal)

In the present invention, the crystalline calcium aluminate represented by the composition formula of C ₁₂ A ₇ needs to be contained in the molded body in an amount of 85% by volume or more, and the above effect becomes clearer. It is preferable to contain above. Note that the C ₁₂ A ₇ other parts of the molded body may be any as long as it does not inhibit the effect of the invention, for example, amorphous calcium aluminate, C ₁₂ A ₇ It may be a crystalline calcium aluminate such as CaO.Al ₂ O ₃ (CA) and 3CaO.Al ₂ O ₃ (C ₃ A) which is different from the above.

As for the content of negatively charged oxygen atoms, in order that the oxidation reaction is clearly promoted, 1 × 10 ¹⁹ atoms / cm ³ or more is sufficient to achieve the object of the invention. × 10 ²⁰ pieces / cm ³ or more is preferable.

In the present invention, the relative density of the molded body is 55 to 85%. The relative density is a value obtained by dividing the bulk density of the molded body by the theoretical density of the crystals constituting the molded body, but when the molded body is composed of two or more kinds of crystals, the volume of each crystal. A ratio weighted value is used as a reference. The theoretical density (crystal density) of the C ₁₂ A ₇ crystal is 2.676 g / cm ³ , and when the molded body is composed only of C ₁₂ A ₇ crystals, the molded body having a relative density of 55 to 85% Indicates a molded body having a bulk density of 1.472 to 2.275 g / cm ³ .

The molded body of the present invention has a relative density of 55 to 85%, and at this time, the above-described effect occurs. The reason for this is estimated by the inventors as follows. When the relative density is 85% or less, the pores contained in the molded body are increased and these are connected to each other, and the ratio of pores communicating from the molded body surface, that is, open pores, is increased. For this reason, the surface area which can contact with an oxidizable substance also becomes large inside a molded object. Since the contact / reaction between O ⁻ and the oxidizable substance is considered to occur at or near the surface of the molded body, the contact / reaction is promoted by the increase in the surface area, and the effects of the present invention can be obtained. .

On the other hand, if the relative density is less than 55%, the strength of the molded product is remarkably reduced and handling becomes difficult. If the relative density exceeds 85%, the molded product becomes dense and the surface area is significantly reduced.・ The reaction does not proceed smoothly. For this reason, none of them is suitable for the present invention.

The molded body of the present invention may be a lump, but since the oxidation reaction occurs on the surface of the molded body, the area of the outer surface is preferably as large as possible. Therefore, a more preferable embodiment such as a honeycomb structure described later or a film-shaped formed body is achieved.

In the case of a honeycomb structure, the strength can be ensured at the outer peripheral portion, so that the inner partition wall contacting the oxidizable material is preferably as thin as possible in order to increase the surface area, but if it is too thin, it will be damaged during production. For this reason, it is preferable that the thickness of the internal partition which forms a honeycomb structure is 0.2-0.7 mm.

In the case of a film-shaped formed body, the strength can be ensured by the base material, so that it can be made thinner than the internal partition walls of the self-supporting honeycomb structure, and the thickness that is easy to form a film is actually 1 to 200 μm. The degree is preferably selected. As the base material, in view of the fact that the molded product is heated to 300 ° C. or less and more easily exerts its effect, it is desirable to have heat resistance, such as quartz, zirconia, mullite, alumina, magnesia, etc. Quartz is particularly preferable because it is resistant to thermal shock and is inexpensive.

Next, the manufacturing method of the molded object of this invention is demonstrated.

Examples of the Ca source material include limestone (CaCO ₃ ), slaked lime (Ca (OH) ₂ ), and quicklime (CaO). Examples of the Al source material include alumina (Al ₂ O ₃ ), aluminum hydroxide (Al (OH) ₃ ), bauxite, or aluminum residual ash. These Ca source and Al source may be used in combination. If the molar ratio of Ca: Al is 0.70: 1 to 1.40: 1, a material containing both Ca and Al from the beginning, such as amorphous calcium aluminate, CA and / or C It may be crystalline C ₁₂ A ₇ partially containing other calcium aluminate such as ₃ A. Of course, it may be composed of only crystalline C ₁₂ A ₇ . Among these, since it is easy to obtain and has high safety, a mixture of CaCO ₃ and Al ₂ O ₃ can be particularly preferably used.

The raw material may be molded as a powder as it is using a press molding machine or a cold isostatic press (CIP) machine, but in order to give strength and easy handling at the time of the green molded body before firing, You may mix | blend a binder as needed.

As the binder, substances such as polyvinyl alcohol, nitrocellulose, polyacrylic acid ester, polyvinyl butyral, polymethacrylic acid ester, ethyl cellulose, or methyl cellulose are used.

Binders include alcohols such as methanol, ethanol, isopropanol and n-butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as methyl acetate, ethyl acetate and butyl acetate, ethers such as dioxane and tetrahydrofuran , Organic solvents such as cellosolves such as methyl cellosolve and butyl cellosolve, hydrocarbons such as n-hexane and cyclohexane, chlorinated hydrocarbons such as chloroform and methylene chloride, aromatics such as toluene and xylene, and water It can be used as a mixed solution.

A clay or slurry raw material can be produced by mixing an appropriate amount of the solution with the raw material powder. When a green molded body having a complicated shape is formed, it can be formed by a casting method using a slurry raw material. In particular, in the case of a green molded body with a honeycomb structure, a clay-like raw material is used, and it is good to mold by an extrusion method. In the case of a film-like green molded body, a slurry-like raw material is used, and a dip coating method, a doctor blade method, It is good to mold.

The relative density of the green molded body is selected to be 50-80% unlike the final molded body. If it is less than 50%, the strength is small and it becomes difficult to handle the green molded body. On the other hand, if it exceeds 80%, the compact after heating becomes dense and the surface area is remarkably reduced, so that the reaction with the oxidizable substance does not proceed smoothly. For this reason, none is suitable for the present invention. In addition, the definition of the relative density referred to here is as described above. However, the theoretical density of the binder portion is 1.0 g / cm ³ regardless of the type.

The green molded body is heated to 1000 ° C. to 1200 ° C. in an atmosphere having an oxygen partial pressure of 4 × 10 ⁴ Pa or more. When the oxygen partial pressure is less than 4 × 10 ⁴ Pa or the heating temperature is less than 1000 ° C., the molded product contains only 1 × 10 ¹⁹ atoms / cm ³ of negatively charged oxygen atoms (O ⁻ ). On the other hand, when the heating temperature exceeds 1200 ° C., densification of the molded product proceeds and the relative density exceeds 85%, and the surface area is significantly reduced. For this reason, none is suitable for the present invention.

The molded body of the present invention generates negatively charged oxygen atoms (O ⁻ ) at a relatively low temperature (5-300 ° C.) and normal pressure (0.8-1.5 atm) near normal temperature, and oxidizes the oxidizable substance. Features that promote

When oxidizing the oxidizable substance, in the atmosphere containing 1% by volume or more of oxygen, when selecting a condition of 5 ° C. to 300 ° C., the gaseous, dusty or mist oxidizable substance is more This is preferable because it can be more reliably oxidized. The oxygen concentration in the atmosphere is more preferably 5% by volume or more.

(Examples 1 to 5) Calcium carbonate (CaCO ₃ ) powder and alumina (γ-Al ₂ O ₃ ) powder were mixed at a molar ratio of Ca: Al of Ca: Al = 6: 7 (≈0.86: 1). Then, using a mold and a hydraulic press, a pressure of 10 MPa was applied to produce a disk-shaped green molded body having a diameter of 50 mm and a thickness of 5 mm. The relative density of the green molded body determined from the size and weight of the disc and the true specific gravity of CaCO ₃ and γ-Al ₂ O ₃ was 65%.

The green molded body was heated at 1150 ° C. for 2 hours in an oxygen partial pressure of 8.1 × 10 ⁴ Pa. After cooling, a disk-shaped molded body was obtained. A part of the molded body was pulverized and subjected to X-ray diffraction measurement. As a result, 90% by volume of crystalline C ₁₂ A ₇ was contained, and the balance was 3CaO · Al ₂ O ₃ (C ₃ A). The measured ESR spectrum at room temperature and 77K, the intensity of each absorption bands _{O 2} ^- ion radical and O ^- was determined the concentration of ions radicals were respectively 1 × ¹⁰ 20 ^{cm -3.} Further, when the relative density of the molded product was determined from the dimensions, weight, and crystal density of C ₁₂ A ₇ and C ₃ A, it was 78%.

The molded body was inserted into a transparent quartz tube having an inner diameter of 45 mm so that the outer periphery of the molded body was in contact with the inner wall of the quartz tube, and the space between the outer periphery of the molded body and the inner wall of the quartz tube was sealed with a heat-resistant epoxy adhesive. From one end of the quartz tube, 50 ppm of acetaldehyde, which is a kind of VOC, and oxygen gas having a concentration shown in Table 1 were introduced, and a mixed gas consisting of argon gas was introduced into the balance. Next, after holding the quartz tube at room temperature or heating the quartz tube to a predetermined temperature, the gas pressure on the introduction side is increased to 0.12 MPa, and the molded body is moved to the other atmospheric pressure (0.10 MPa) side end of the quartz tube. The introduced gas was allowed to permeate through. A check valve is provided between the atmospheric pressure side end and the outside air so that the outside air pushed out by the gas permeating from the introduction side end does not flow back into the pipe again. When the argon gas concentration at the atmospheric pressure side end became substantially equal to the introduction side end, it was considered that the introduced gas had sufficiently permeated, and the acetaldehyde concentration at the atmospheric pressure end side at this point was measured. The results are shown in Table 1.

(Comparative Examples 1 to 5) In the same manner as in Example 1, from a CaCO ₃ powder and a γ-Al ₂ O ₃ powder, a green molded body having a diameter of 50 mm and a thickness of 5 mm and a relative density of 62% was obtained. Produced. This was heated at 1220 ° C. for 2 hours in an atmosphere with an oxygen partial pressure of 3 × 10 ⁴ Pa, and after cooling, a disk-shaped molded body was obtained. Further, when a part of the molded body was crushed and subjected to X-ray diffraction measurement, 80% by volume of crystalline C ₁₂ A ₇ was contained, and the balance was approximately the same amount (10% by volume) of C ₃ A and CA. Met. From the absorption band intensity ESR spectrum _{O 2} ^- ion radical and O ^- was determined the concentration of ions radicals were respectively 5 × ¹⁰ 18 ^{cm -3.} The relative density of the molded product was found to be 88% from the dimensions, weight, and crystal density of C ₁₂ A ₇ and C ₃ A and CA.

The molded body was loaded into the quartz tube in the same manner as in Example 1, a mixed gas of acetaldehyde, oxygen and argon was introduced from one end, and the concentration of acetaldehyde permeating the molded body at the other end was measured. did. These results are shown in Table 1.

(Example 6) The molar ratio of Ca: Al is 1.40: 1, these contain a total of 93.3% by mass as amorphous calcium aluminate, and the balance is SiO ₂ , TiO ₂ , Fe ₂ O ₃ or A powder composed of MgO or the like, ethanol, and polyvinyl butyral (# 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a binder are mixed at a mass ratio of 100: 100: 0.05. A slurry was prepared. Next, the slurry was used as a raw material, and cast molding was performed using a plaster mold to obtain a test tube-shaped green molded body having an outer diameter of 12 mm, a wall thickness of 1.5 mm, and a length of 200 mm. After drying at 80 ° C. for 6 hours, the relative density of the green molded body determined from the size and weight of the molded body and the true specific gravity of the powder was 54%.

The green molded body was heated at 1200 ° C. for 2 hours in an oxygen atmosphere of 9.5 × 10 ⁴ Pa to obtain a test tube-shaped molded body. This was partially pulverized and subjected to X-ray diffraction measurement. As a result, 87% by volume of crystalline C ₁₂ A ₇ was contained, and the balance was C ₃ A. The O ^- ion radical concentration determined from the intensity of the absorption band in the ESR spectrum is 3.5 × 10 ²⁰ cm ⁻³ , the size and weight, and the relative density of the compact from the crystal density of C ₁₂ A ₇ and C ₃ A. When calculated, it was 83%.

Inside this molded body, a mixed gas composed of 50 ppm of formaldehyde (HCHO), which is a kind of VOC, and 5% by volume of oxygen gas, and the balance consisting of argon gas was introduced. Subsequently, the gas pressure on the introduction side was increased to 0.15 MPa while maintaining the normal temperature, and the introduction gas was permeated to the outside of the molded body. When the outside of the test tube is immersed in a fluorine-based inert liquid (Audmont Co., Ltd., Galden LS230), the mixed gas permeating from the inside is collected on the liquid, and the HCHO concentration is measured. Met.

But heated in an oxygen atmosphere (Comparative Example 6) 2.0 × 10 4 ^Pa, were manufactured molded body tube shaped in the same manner as in Example 6, O ^- concentration of ion radicals of 1 × 10 A molded body of ¹⁸ cm ⁻³ was obtained. Using this, the HCHO concentration in the gas collected in the same manner as in Example 6 was 35 ppm.

(Example 7) After mixing calcium carbonate (CaCO ₃ ) powder and alumina (γ-Al ₂ O ₃ ) powder so that the molar ratio of Ca and Al is Ca: Al = 0.82: 1, The mixed powder, water, and methyl cellulose (MC) as a binder were mixed using a Henschel mixer so that the weight ratio was 100: 35: 16, to obtain a clay-like composition. Using an extrusion molding machine, this was a rectangular parallelepiped honeycomb-like green molded body having a square opening of 3 mm × 3 mm, a partition wall thickness of 1 mm, a cross-sectional dimension / shape of 43 mm × 43 mm, and a length of 120 mm. . This was dried 3 hours at 120 ° C., size, weight and CaCO _3, the relative density of the green compact obtained from the theoretical density of _gamma-Al 2 _{O 3} and MC was 57%.

The green molded body was heated at 1100 ° C. for 2 hours in an oxygen atmosphere of 9.0 × 10 ⁴ Pa to obtain a honeycomb-shaped molded body. This was partially pulverized and subjected to X-ray diffraction measurement. As a result, 97% by volume of crystalline C ₁₂ A ₇ was contained, and the balance was CaO · Al ₂ O ₃ (CA). The O ^- ion radical concentration determined from the intensity of the absorption band of the ESR spectrum was 4 × 10 ²⁰ cm ⁻³ , the size and weight, and the relative density of the molded body was determined from the crystal density of C ₁₂ A ₇ and CA. %Met.

A gas in which spore mold and spore mold were suspended in the air was allowed to pass through the honeycomb molded body at room temperature, and then introduced into a culture tank having a temperature of 25 ° C. and a relative humidity of 99% to culture the spores. As a result of observing the growth state of the mold produced on the surface after culturing with a stereomicroscope after 4 weeks, almost no mold growth was observed with a 50 × microscope.

(Comparative Example 7) A honeycomb-shaped molded body was manufactured in the same manner as in Example 7 except that the heating condition of the green molded body was set to an oxygen atmosphere of 2.0 × 10 ⁴ Pa and a temperature of 1220 ° C. This was carried out by partially grinding X-ray diffraction measurement, a crystalline C ₁₂ A ₇ of containing 80 vol%, the balance is CA, O was determined from intensity of the absorption bands of ESR spectra ^- ion radical The concentration was 5 × 10 ¹⁸ cm ⁻³ , the dimensions and weight, and the relative density determined from the crystal density of C ₁₂ A ₇ and CA was 86%. Using this, mold spores were cultured in the same manner as in Example 6. As a result, mold growth was clearly observed with the naked eye.

(Example 8) Calcium oxide (CaO) powder and γ-Al ₂ O ₃ powder were mixed so that the molar ratio of Ca to Al was Ca: Al = 0.82: 1. The powder was baked at 3 ° C. for 3 hours to obtain a white powder.

This was further heated at 1250 ° C. for 2 hours in an oxygen partial pressure of 8.1 × 10 ⁴ Pa. After cooling, a part of the sintered body was pulverized and subjected to X-ray diffraction measurement. As a result, C ₁₂ A ₇ Was 92% by volume, and the balance was a mixture of CA and C ₃ A. Moreover, when the density | concentration of O < ^- > ion radical was calculated ^| required from the intensity | strength of the absorption band of an ESR spectrum, it was 1 * 10 < ²⁰ > cm < ^-3 >.

The sintered body was wet pulverized in ethanol using a ball mill and dried to obtain a powder having a specific surface area of 2.1 m ² / g.

This powder was mixed with ethanol and polyvinyl butyral as a binder (manufactured by Denki Kagaku Kogyo Co., Ltd., # 3000-K) in a weight ratio of 100: 100: 0.05 to prepare a slurry. This slurry was applied to an opaque quartz cylinder having an outer diameter of 10 mm, an inner diameter of 8 mm, and a length of 300 mm by dip coating, followed by drying at 80 ° C. for 4 hours, and obtained from the thickness and weight of the coating film and the true specific gravity of the powder. The relative density of the coated film was 52%.

A quartz cylinder having a coating film was heated at 1100 ° C. for 3 hours in an oxygen atmosphere of 9.0 × 10 ⁴ Pa to obtain a film-like molded body having a thickness of 100 μm and using an opaque quartz cylinder as a base material. . When a part of the film was peeled off and X-ray diffraction measurement was performed, it was found that 95% by volume of crystalline C ₁₂ A ₇ was contained, and the balance was 5CaO.3Al ₂ O ₃ (C ₅ A ₃ ). The O ^- ion radical concentration determined from the intensity of the absorption band of the ESR spectrum is 5 × 10 ²⁰ cm ⁻³ , and the relative density is determined from the thickness and weight of the coating film and the crystal density of C ₁₂ A ₇ and C ₅ A _3. When calculated, it was 82%.

Thirty-seven compacts based on this opaque quartz cylinder were produced, bundled so that the cross section was a hexagon, and the outer periphery was fixed with a heat-resistant epoxy adhesive.

A flue was installed in a smoking room, and the bundle of the compacts was loaded with a filler sandwiched between the outer periphery of the bundle and the inner wall of the flue. Heterocycles such as organic acids, aldehydes, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, pyridine, furan, indole, etc., in the vicinity of the opening on the inside and outside of the smoking room of the molded product bundle when used in a smoking room When the total concentrations of VOCs such as compounds and polycyclic aromatic hydrocarbons were measured and compared by gas chromatography, the latter was 5% or less of the former.

(Comparative Example 8) A film-shaped molded article having a thickness of 100 µm was obtained in the same manner as in Example 8 except that the heating condition of the coating film was changed to an oxygen atmosphere of 2.0 x 10 ⁴ Pa and a temperature of 1220 ° C. When a part of the film was peeled off and X-ray diffraction measurement was performed, it contained 80% by volume of crystalline C ₁₂ A ₇ and the balance was C ₅ A ₃ . The O ^- ion radical concentration obtained from the intensity of the absorption band of the ESR spectrum is 8 × 10 ¹⁸ cm ⁻³ , and the relative density is determined from the thickness and weight of the coating film and the crystal density of C ₁₂ A ₇ and C ₅ A _3. When calculated, it was 88%.

In the same manner as in Example 8, a bundle of molded articles was prepared and loaded into the flue of the smoking room, and the total concentration of VOCs in the vicinity of the opening on the smoking room side and the outside of the smoking room was measured and compared. Was 80% of the former.

The molded article of the present invention can easily promote oxidation of oxidizable substances such as chemical substances and mold spores under normal temperature and pressure. Therefore, volatile organic substances (VOC) such as formaldehyde, which is a causative agent of sick house syndrome, cigarette smoke or mold spores can be oxidized and detoxified at normal temperature and pressure. It is useful because it can be used in various industries such as filters and materials for wall materials of houses.

According to the method for producing a molded article of the present invention, the molded article having the above characteristics can be provided reliably and stably, which is very useful industrially.

Since the oxidation reaction promoting method of the present invention uses the above-mentioned specific molded body, it can industrially detoxify and detoxify harmful oxidizable substances under mild conditions as compared with the prior art. Very useful.

Claims (5)

After molding a raw material powder having a Ca: Al molar ratio of 0.70: 1 to 1.40: 1 so that the relative density is 50 to 80%, an atmosphere having an oxygen partial pressure of 4 × 10 ⁴ Pa or more A crystalline calcium aluminate represented by a composition formula of 12CaO · 7Al ₂ O ₃ and containing 1 × 10 ¹⁹ negative atoms / cm ³ or more, characterized by heating to 1000 ° C. to 1200 ° C. Of 85% by volume or more and a method for producing a molded body having a relative density of 55 to 85%.   The method for producing a formed body according to claim 1, wherein the formed body is a honeycomb structure or a film-shaped formed body.   The molded object which can be obtained with the manufacturing method of the molded object of Claim 1 or 2. After molding a raw material powder having a Ca: Al molar ratio of 0.70: 1 to 1.40: 1 so that the relative density is 50 to 80%, an atmosphere having an oxygen partial pressure of 4 × 10 ⁴ Pa or more A crystalline calcium aluminate represented by a composition formula of 12CaO · 7Al ₂ O ₃ and containing 1 × 10 ¹⁹ negative atoms / cm ³ or more , which can be obtained by heating to 1000 ° C. to 1200 ° C. Contacting an oxidizable substance with a compact containing 85% by volume or more and having a relative density of 55 to 85% in an atmosphere containing 1% by volume or more of oxygen under a condition of 5 to 300 ° C. An oxidation reaction promoting method characterized by the above. The compacts according to claim 4 Symbol mounting oxidation reaction method for promoting a honeycomb structure also filmy forming body.