JP2003220318A - PHOTOCATALYST INORGANIC SHEET FOR EFFECTIVELY DECOMPOSING NOx - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncombustible/adsorbable/neutralizing photocatalyst inorganic sheet which decomposes/detoxifies NOX effectively. <P>SOLUTION: The photocatalyst inorganic sheet for effectively decomposing NOX is obtained by preparing a composite sheet in a semidrying condition or in a wet condition, calcining the resultant at 500°C or higher to impart the noncombustible property thereto using either one of an adsorbent or a metal oxide which has a NO<SB>2</SB>high retainability and a nitric acid binding ability, or both of them and all of organic pulp, a photocatalyst, an inorganic fiber, an inorganic supporting material forming component and a polymeric coagulant or a material group excluding one of the organic pulp, the polymeric coagulant and the adsorbent or the metal oxide among these materials. The obtained sheet has improved strength and decomposes/detoxifies NOX effectively. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photocatalytic inorganic sheet capable of decomposing NOx, which is a harmful substance of air pollution, by utilizing a photocatalytic reaction of titanium oxide, and more specifically, it holds an intermediate to be produced and promotes decomposition. At the same time, the photocatalyst with a high effect of remediating environmental pollution by separating nitric acid, which is a product of catalyst poison, from titanium oxide by adsorption and chemical reaction, preventing degradation of catalytic ability and efficiently and continuously decomposing NOx. The present invention relates to a supported inorganic sheet.

[0002]

2. Description of the Related Art In recent years, as vehicle traffic has increased, NOx-induced environmental pollution, asthma, and headache
It induces dizziness and has a serious adverse effect on daily life. It is eagerly desired to improve as early as possible for one day, but as a measure to improve it, we try to reduce NOx by planting trees with high NOx adsorption capacity on the road side or median strip, mixing titanium oxide with roadside additives, and kneading. Has been done. However, NO due to trees
The x absorption is not sufficient in a place with high NOx concentration such as a traffic jam area, and even if the titanium oxide is directly mixed with the roadside material, the NOx absorption capacity of the titanium oxide is low, so that sufficient effect cannot be obtained. There are problems such as secondary pollution due to NO ₂ generated by decomposition of OH and reduction of photocatalytic efficiency due to nitric acid, which is a major obstacle to practical use.

[0003]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that titanium oxide and A
By combining type zeolite, NOx absorption / concentration and NO ₂ emission prevention, CaO, MgO, ZnO,
Completed a photocatalyst inorganic sheet with high NOx removal ability and excellent durability to prevent reduction of titanium oxide photocatalytic ability by removing nitric acid by making metal oxides such as Al ₂ O ₃ coexist near titanium oxide. Came to do. That is, the present invention is: Presence of organic fiber such as pulp, inorganic adsorbent such as zeolite, metal hydroxide such as calcium hydroxide and magnesium hydroxide, photocatalyst such as titanium oxide and zinc oxide,
Add a suitable amount of water to a mixture of inorganic fibers such as ceramic fibers and glass fibers and inorganic sintered components such as silica gel and alumina sol, knead them well, and put this on a metal plate with many holes or on a filter cloth placed on the metal plate. 1. A method for producing a NOx highly decomposable photocatalyst inorganic sheet, which is uniformly spread as much as possible, squeezed, and heated to 500 ° C. or higher to remove organic substances and impart strength. A cationic flocculant such as polydiallyldimethylammonium chloride is added to organic fibers such as pulp, and then an inorganic adsorbent, a metal oxide such as calcium hydroxide, a photocatalyst and inorganic fibers, or an aqueous suspension of these four is added. Further, an anionic coagulant such as an anionic polyacrylamide is further added, and a wet sheet-formed sheet or a dried sheet is added with an inorganic sinter component such as alumina sol by an impregnation method or a spraying method and squeezed. 2. A method for producing a NOx highly decomposable photocatalytic inorganic sheet, which is heated to a temperature of ℃ or above to remove organic substances, A sheet containing no photocatalyst is first prepared in accordance with the methods 1 and 2 above, and the sheet is impregnated with a photocatalyst suspension such as titanium oxide sol and then dried.
The present invention relates to a method for producing a high-degradability photocatalytic inorganic sheet.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The constituent elements relating to the NOx highly decomposable photocatalytic inorganic sheet of the present invention and the method for producing the same are described in detail below.

Examples of the adsorbent according to the present invention include various zeolites, activated clay, zinc oxide, alumina, sepiolite, halloysite, and composites thereof.
In particular, zeolite can be adjusted in its pore size so as to maximize the adsorption efficiency according to various harmful substances, and A-type zeolite is advantageously used as a nitrogen oxide adsorbent.

Examples of the nitric acid removing agent used in the present invention include various metal hydroxides which are converted into metal oxides by firing. Ca (OH) ₂ and Mg are excellent in easiness of conversion.
Al that forms hydroxides of divalent metal ions such as (OH) ₂ and Zn (OH) ₂ and oxides that are stable and have low solubility
(OH) ₃ is advantageously used.

Examples of the photocatalyst of the present invention include metal oxides such as titanium oxide and cerium oxide. Titanium oxide excellent in stability, safety and photocatalytic high resolution is advantageously used.

Examples of the inorganic fibers according to the present invention include ceramic fibers, glass fibers, slag fibers, asbestos, etc., but ceramic fibers excellent in stability, safety and strength are advantageously used.

Examples of the inorganic support-forming component used in the present invention include alumina sol, silica sol, sodium phosphate and the like, and alumina sol having the optimum particle size and affinity with other materials is advantageously used.

The pulp of the present invention is a fibrous substance such as wood pulp, linter pulp, synthetic pulp, etc., and natural pulp which can contribute to a high yield of inorganic powder and is easily fibrillated is advantageously used. To be

For the semi-dry molding, a sheet molding machine for fiber board or cement board can be used. It is also possible to put a wire net or a filter cloth on a metal plate having a large number of holes, spread the kneaded raw material mixture on it as evenly as possible, and press it with a press for a test to make a sheet. The prepared sheet is fired in an electric furnace adjusted to a constant temperature of 500 ° C or higher,
An NOx highly decomposable photocatalytic inorganic sheet was obtained.

For the wet papermaking, a handmade paper making machine such as Japanese paper, a cylinder paper making machine, a fourdrinier paper making machine or a twin wire paper making machine can be used. The prepared sheet was impregnated or sprayed with a dispersion liquid of components for forming an inorganic support, and then fired in an electric furnace adjusted to a constant temperature of 500 ° C. or higher to obtain a NOx highly decomposable photocatalytic inorganic sheet.

[0013]

EXAMPLES Next, the present invention will be specifically described with reference to examples. Obviously, the present invention is not limited to the last section of the experimental conditions used in the examples shown below, in the light of common research knowledge in the field.

Example 1 1.0 part of wood pulp beaten to about 265 ml of CSF, zeolite A type (Wako Pure Chemical Industries, Ltd.,
A-4) 2.0 parts, calcium hydroxide 2.0 parts, titanium oxide (Ishihara Sangyo Co., Ltd., ST-31) 2.0 parts, ceramic fiber (Isolite Kogyo, Kaowool Bulk LS)
3.0 parts and 4.0 parts of alumina sol (Alumina sol-520 manufactured by Nissan Chemical Industries, Ltd.) and 7.0 parts of water were added,
Kneaded with a kneader. 8 on stainless plate with many holes
Place a 0 mesh wire mesh, spread the kneaded raw material on this as evenly as possible, and use a test press to remove 3.5 kP
a, it was clamped for 5 minutes. The NOx of Example 1 having a basis weight of about 250 g / m ² by firing the resulting sheet at 700 ° C. for 20 minutes
A high-degradability photocatalytic inorganic sheet was obtained.

[Example 2] The same method as in Example 1 was repeated except that the wood pulp in Example 1 was changed to 0 part.
The NOx highly decomposable photocatalytic inorganic sheet of Example 2 was prepared.

[Example 3] Example 3 was carried out in the same manner as in Example 1 except that zeolite A type was 3.0 parts, calcium hydroxide was 0 part, and titanium oxide was 3.0 parts. A NOx high-degradability photocatalytic inorganic sheet of No. 3 was prepared.

[Example 4] Example 4 was carried out in the same manner as in Example 1 except that zeolite A type was 0 part, calcium hydroxide was 3.0 parts, and titanium oxide was 3.0 parts. A NOx high-degradability photocatalytic inorganic sheet of No. 4 was prepared.

Example 5 While stirring 10 g of a 4% aqueous suspension of wood pulp beaten to about 265 ml of CSF,
25 g of 0.1% polydiallyldimethylammonium chloride aqueous solution was added, and after 3 minutes 1.2 g of zeolite A type,
65 g of an aqueous suspension containing 1.2 g of calcium hydroxide, 1.2 g of titanium oxide, and 1.5 g of ceramic fibers was added, and a 0.1% anionic flocculant (HH- manufactured by Kurita Water Industries Ltd.) was added.
351) 50 g was added, and 5 minutes later, JIS P 8209
A sheet was prepared according to the above procedure, and the sheet was impregnated with alumina sol, which is a dispersion liquid of components for forming an inorganic support. This is pressed and fired in the same manner as in Example 1, and Example 5
A highly decomposable photocatalytic inorganic sheet of NOx was obtained.

[Example 6] In the same manner as in Example 5, except that the amount of zeolite A used was 1.8 g, the amount of calcium hydroxide was 0 g, and the amount of titanium oxide was 1.8 g, the NOx content of Example 6 was increased. A degradable photocatalyst sheet was obtained.

[Example 7] The NOx content of Example 7 was increased in the same manner as in Example 5, except that 0 g of zeolite A type, 1.8 g of calcium hydroxide and 1.8 g of titanium oxide were used in Example 5. A degradable photocatalyst sheet was obtained.

Example 8 While stirring 10 g of a 4% water suspension of wood pulp beaten to about 265 ml of CSF,
25 g of 0.1% polydiallyldimethylammonium chloride aqueous solution was added, and after 3 minutes, 1.8 g of zeolite A type,
65 g of an aqueous suspension containing 1.8 g of calcium hydroxide and 1.5 g of ceramic fibers was added, and 50 g of 0.1% anionic flocculant (HH-351 manufactured by Kurita Water Industries Ltd.) was added, and after 5 minutes JIS. A sheet was prepared in accordance with P 8209, and the sheet was prepared by using titanium oxide sol (STS manufactured by Ishihara Sangyo Co., Ltd.
-01) was impregnated. This was pressed and fired in the same manner as in Example 1 to obtain a NOx highly decomposable photocatalytic inorganic sheet of Example 8.

[Example 9] In Example 8 except that 3.6 g of zeolite A type and 0 g of calcium hydroxide were used,
The NOx highly decomposable photocatalyst sheet of Example 9 was obtained in the same manner as in Example 8.

[Example 10] The same procedure as in Example 8 was repeated except that the amount of zeolite A was 0 g and the amount of calcium hydroxide was 3.6 g.
A highly decomposable photocatalyst sheet was obtained.

Comparative Example 1 1.0 part of wood pulp beaten to about 265 ml of CSF, zeolite Y type (manufactured by Tosoh Corporation,
HSZ-320NAA) 2.0 parts, magnesium hydroxide 2.0 parts, titanium oxide (made by Ishihara Sangyo Co., Ltd., ST-31)
2.0 parts, 3.0 parts of ceramic fibers (Isolite Kogyo, Kao Wool Bulk LS), 4.0 parts of alumina sol (Alumina sol-520 manufactured by Nissan Chemical Industries, Ltd.) and 7.0 parts of water were added, and the mixture was kneaded with a kneader. did. Place a wire mesh of 80 mesh on a stainless plate having holes at intervals of about 10 mm,
The kneaded raw material was spread thereon as evenly as possible, and was pressed at 3.5 kPa for 5 minutes using a handmade paper press. The resulting sheet is baked at 700 ° C for 20 minutes and the basis weight is about 250.
A NOx-decomposable photocatalytic inorganic sheet of Comparative Example 1 with g / m ² was obtained.

[Comparative Example 2] Comparative Example 2 was carried out in the same manner as Comparative Example 2 except that the zeolite Y type was 0 part, the magnesium hydroxide was 0 part, and the titanium oxide was 6.0 parts in Comparative Example 1. A NOx decomposable photocatalytic inorganic sheet was prepared.

[Comparative Example 3] Comparative Example 3 was carried out in the same manner as Comparative Example 1 except that the zeolite Y type was 3.0 parts, the magnesium hydroxide was 0 part, and the titanium oxide was 3.0 parts. The NOx decomposable photocatalytic inorganic sheet of Example 3 was prepared.

[Comparative Example 4] Comparative Example 1 is the same as Comparative Example 1 except that the zeolite Y type is 0 part, magnesium hydroxide is 3.0 parts, and titanium oxide is 3.0 parts. The NOx decomposable photocatalytic inorganic sheet of Example 4 was prepared.

[Comparative Example 5] While stirring 10 g of a 4% aqueous suspension of wood pulp beaten to about 265 ml of CSF,
25 g of 0.1% polydiallyldimethylammonium chloride aqueous solution was added, and after 3 minutes, 65 g of water suspension containing 3.6 g of titanium oxide and 1.5 g of ceramic fiber was added, and further 0.1% anionic flocculant (Kurita HH- manufactured by Kogyo Co., Ltd.
351) 50 g was added, and 5 minutes later, JIS P 8209
A sheet was prepared according to the above procedure, and the sheet was impregnated with alumina sol, which is a dispersion liquid of components for forming an inorganic support. This was pressed and fired in the same manner as in Example 1, and Comparative Example 5
A NOx decomposable photocatalytic inorganic sheet was obtained.

Comparative Example 6 While stirring 10 g of a 4% water suspension of wood pulp beaten to about 265 ml of CSF,
25 g of 0.1% polydiallyldimethylammonium chloride aqueous solution was added, and after 3 minutes, 1.8 g of zeolite Y type,
65 g of an aqueous suspension containing 1.8 g of titanium oxide and 1.5 g of ceramic fiber was added, and 50 g of 0.1% anionic flocculant (HH-351 manufactured by Kurita Water Industries Ltd.) was added, and after 5 minutes, JIS P Prepare a sheet according to 8209,
This was impregnated with alumina sol, which is a dispersion liquid of the inorganic support-forming component. This was pressed and fired in the same manner as in Example 1 to obtain a NOx decomposable photocatalytic inorganic sheet of Comparative Example 6.

Comparative Example 7 While stirring 10 g of a 4% aqueous suspension of wood pulp beaten to about 265 ml of CSF,
25 g of 0.1% polydiallyldimethylammonium chloride aqueous solution was added, and 3 minutes later, magnesium hydroxide 1.8 was added.
g, 1.8 g of titanium oxide, and 65 g of an aqueous suspension containing 1.5 g of ceramic fibers were added, and further 50 g of 0.1% anionic flocculant (HH-351 manufactured by Kurita Water Industries Ltd.) was added,
After 5 minutes, a sheet was prepared according to JIS P 8209 and impregnated with an alumina sol which is a dispersion liquid of components for forming an inorganic support. This was pressed and fired in the same manner as in Example 1 to obtain a NOx decomposable photocatalytic inorganic sheet of Comparative Example 7.

[Comparative Example 8] While stirring 10 g of a 4% aqueous suspension of wood pulp beaten to about 265 ml of CSF,
25 g of 0.1% polydiallyldimethylammonium chloride aqueous solution was added, and after 3 minutes, 1.8 g of zeolite Y type,
Magnesium hydroxide 1.8g, ceramic fiber 1.5g
65 g of a water suspension containing 0.1 g of 0.1% anionic flocculant (HH-351 manufactured by Kurita Water Industries Ltd.) was added, and after 5 minutes, a sheet was prepared according to JIS P 8209. Titanium oxide sol (made by Ishihara Sangyo Co., Ltd., STS
-01) was impregnated. This was pressed and fired in the same manner as in Example 1 to obtain a NOx decomposable photocatalytic inorganic sheet of Comparative Example 8.

[Comparative Example 9] A NOx decomposable photocatalytic inorganic sheet of Comparative Example 9 was prepared in the same manner as Comparative Example 8 except that the amount of zeolite Y type was 3.6 g and the amount of magnesium hydroxide was 0 g. Prepared.

[Comparative Example 10] NOx of Comparative Example 10 was the same as Comparative Example 8 except that the amount of zeolite Y type was 0 and the amount of magnesium hydroxide was 3.6 g.
A degradable photocatalytic inorganic sheet was prepared.

The NO values obtained in the above examples and comparative examples
The x-decomposable photocatalytic inorganic sheet was tested by the following method, and the results are shown in the table.

[Yield of Inorganic Material]
It was calcined for 20 minutes in an electric furnace at 00 ° C., and determined from the residual ash content.

[Strength of Inorganic Sheet] It was measured according to the compression strength test (ring crush method) Tappi T 818-87.

[Photocatalytic Decomposition] The nitrogen oxide concentration was measured using a nitrogen oxide measuring device (CLAD-1000A type, manufactured by Shimadzu Corporation). Simulated NOx was prepared by diluting 100 ppm NO to 0.25 ppm with air. This was conditioned to a relative humidity of 50% and continuously supplied to the device at a flow rate of 1.5 L / min. The sheets (25 × 75 mm) prepared in Examples and Comparative Examples were placed in a reaction chamber attached to the apparatus, and UV irradiation (0.3 mW / cm ² ) was performed. The measurement was continuously performed for 5 hours, and the photocatalytic resolution was evaluated from the amount of NO decomposed and the amount of NO ₂ generated during this period.

[0038]

【table】

[0039]

INDUSTRIAL APPLICABILITY The NOx high-resolution photocatalytic inorganic sheet prepared by the method of the present invention efficiently retains a photooxidation intermediate of NOx by a coexisting inorganic adsorbent, and further nitric acid reduces the photocatalytic effect produced by further oxidation. Is neutralized by reacting with the coexisting metal oxide, so that the photocatalytic reaction can be continued and can be used with high efficiency for a long period of time, which is very useful.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D048 AA06 AB03 BA07X BA41X                       CA06 EA01 EA04                 4G069 AA03 AA08 BA04B CA01                       CA10 CA13 DA05 EA07 FA01                       FB15 FB68 FB70

Claims (3)

[Claims] 1. A NOx highly decomposable photocatalytic inorganic sheet comprising an inorganic adsorbent, a photocatalyst, an inorganic fiber and an inorganic support-forming component. 2. An NOx highly decomposable photocatalyst inorganic sheet comprising a metal oxide, a photocatalyst, an inorganic fiber and an inorganic support-forming component. 3. A NOx highly decomposable photocatalyst inorganic sheet comprising an inorganic adsorbent, a metal oxide, a photocatalyst, an inorganic fiber and an inorganic support-forming component.