JP2001114519A - Porous titania, catalyst by using the same and method for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a porous titania showing an excellent catalyst activity in uses such as a denitration, etc., and a catalyst by using the same, and to provide a method for producing the same. SOLUTION: This porous titania having the anatase type crystal structure, 3-10 nm crystallite diameter, >=60% anatase crystallization ratio, >=10 m2/g BET specific surface area, >=0.05 cm3/g total void volume and >=0.02 cm3/g void volume of voids having >=1 nm void radius, is obtained by dissolving a titanium alkoxide with a solvent to obtain the titanium alkoxide solution, adding a mixed solvent consisting of water and a solvent to the titanium alkoxide solution for hydrolyzing, then polymerizing to obtain a polymer solution, and burning the polymer solution in the presence of a fatty acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a porous titania,
The present invention relates to a catalyst using the same and a method for producing the same. Specifically, when applied to denitration, oxidation of organic matter, decomposition of dioxin, and decomposition and removal of organic solvents, pesticides, surfactants, and the like, porous titania showing excellent activity,
The present invention relates to a catalyst using the same and a method for producing the same.

[0002]

2. Description of the Related Art A titania catalyst is known as a denitration catalyst for removing nitrogen oxides contained in exhaust gas from a refuse incinerator. Various improvements have been proposed for titania-based catalysts for the purpose of maintaining the catalytic activity for a long time. For example, JP-A-5-184923 discloses that
A titania-based catalyst can be obtained by heat-treating amorphous fibers made by the sol-gel method of hydrolyzing and gelling a mixed alkoxide solution of titanium alkoxide and a vanadium compound to precipitate crystals of anatase-type titanium oxide and vanadium oxide. Is described.

[0003]

However, the titania-based catalyst described in JP-A-5-184923 has a problem that its activity is low and its denitration performance is low.

An object of the present invention is to provide a porous titania exhibiting excellent catalytic activity in applications such as denitration, a catalyst using the same, and a method for producing the same.

[0005]

Means for Solving the Problems The present inventors have studied the improvement of the catalytic activity of porous titania, and have completed the present invention.

That is, the present invention has an anatase type crystal structure, a crystallite size of 3 nm to 10 nm, an anatase crystallization ratio of 60% or more, and a BET specific surface area of 10 m ² / g.
As described above, the volume of pores having a pore radius of 0.05 cm ³ / g or more and a pore radius of 1 nm or more is 0.02 cm ³ / g.
The present invention provides a porous titania characterized by the above.

The present invention provides a catalyst obtained by molding the above-mentioned porous titania.

Further, the present invention provides a titanium alkoxide solution obtained by dissolving a titanium alkoxide in a solvent, adding a mixed solution comprising water and a solvent to the titanium alkoxide solution, hydrolyzing and polymerizing the solution. And calcining the polymer solution in the presence of a fatty acid.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Titania has a composition formula of TiO ₂ , and its anatase type, rutile type and amorphous crystal structures are known. Among them, the porous titania of the present invention has an anatase type crystal structure. Here, the half width and the peak position of the (101) plane peak of anatase are determined by X-ray diffraction, and the Scherrer equation is used. It is required that the anatase crystallite diameter calculated by the above is 3 nm or more and 10 nm or less. The anatase crystallite diameter is preferably 5 nm or more, and more preferably 9 nm or less.

The second requirement for specifying the porous titania of the present invention is the anatase crystallization rate. The anatase crystallization rate is an index indicating the degree of phase transition of titania to anatase-type crystal and the degree of growth of anatase-type crystal, and the peak area of the (101) plane of anatase is determined by X-ray diffraction. , Can be calculated. In the present invention, it is required that the anatase crystallization rate be 60% or more. The anatase crystallization rate is 65% or more, and even 7
It is preferably at least 0%, at most 95%, more preferably at most 90%. When the porous titania according to the present invention has an anatase crystallization ratio of less than 60%, for example, the anatase crystallite size described above is 3 nm to 10 nm.
Even in the range of nm, it is difficult to exhibit sufficient activity as a catalyst.

Other requirements for specifying the porous titania of the present invention are the BET specific surface area, the total pore volume, and the volume of pores having a pore radius of 1 nm or more. In the present invention, BE
T specific surface area of 10 m ² / g or more, total pore volume of 0.05
It is required that the volume of pores having a pore radius of not less than cm ³ / g and not less than 1 nm is not less than 0.02 cm ³ / g. The BET specific surface area is 180 m ² / g or more, further 200 m ² / g, and the total pore volume is 0.2 cm ³ / g.
g or more, and the volume of pores having a pore radius of 1 nm or more is preferably 0.2 cm ³ / g or more. When the BET specific surface area is less than 10 m ² / g and the total pore volume is less than 0.05 cm ³ / g or the volume of pores having a pore radius of 1 nm or more is less than 0.02 cm ³ / g, excellent activity is obtained. Is difficult to obtain. The BET specific surface area, total pore volume and 1n
The volume of pores having a pore radius of not less than m can be measured by a continuous volume method using nitrogen gas.

The porous titania of the present invention comprises a crystallite size, a BET specific surface area, a total pore volume and an
m, and in addition to satisfying the requirements for the volume of pores having a pore radius of at least m, a distribution curve of the pore volume with respect to the pore radius shows a pore radius of 1 nm to 30 nm,
Preferably, it has a pore structure showing a maximum value in a range of 1 nm or more and 10 nm or less. In particular,
When the porous titania has a fibrous shape, by having this pore structure, the fibrous porous titania has excellent catalytic activity and sufficient tensile strength.
This fibrous porous titania usually has a tensile strength of about 0.5.
1 GPa or more, and the fiber diameter is about 2 μm to about 50 μm.

The porous titania may contain a catalyst component known for denitration applications and the like. The catalyst components include V, W, Al, As, Ni, Zr, Mo, Ru, M
Elements such as g, Ca, Fe, Cr and Pt are listed.

The porous titania according to the present invention is formed into various shapes such as a spherical shape, a ring shape, a honeycomb shape, and a sheet shape, so that, in addition to the denitration catalyst, the oxidation of organic substances,
It is a suitable catalyst for decomposing dioxin or decomposing and removing organic solvents, pesticides or surfactants in water.

According to the present invention, there is provided a porous material having a specific anatase crystallite size, a crystallization ratio, a BET specific surface area, and a specific volume of pores having a total pore volume and a pore radius of 1 nm or more. Titania is obtained, for example, by dissolving a titanium alkoxide in a solvent to obtain a titanium alkoxide solution, adding a mixed solution of water and a solvent to the titanium alkoxide solution, hydrolyzing and polymerizing to obtain a polymer solution, It can be obtained by a method in which the polymer solution is calcined in the presence of a fatty acid.

The titanium alkoxide used for producing the porous titania of the present invention is represented by the following formula (I): Ti (OR ₁ ) ₄ (I) [wherein R ₁ has ₁ to 4 carbon atoms. Represents an alkyl. There is a titanium alkoxide represented by, for example,
Titanium tetramethoxide, titanium tetraethoxide, titanium tetra n-propoxide, titanium tetraisopropoxide, titanium tetra n-butoxide, titanium tetra s
ec-butoxide and titanium tetra-tert-butoxide. Among them, application of titanium tetraisopropoxide is preferred. When R ₁ in the formula (I) is an alkyl having 5 or more carbon atoms, the resulting porous titania may have low mechanical strength.

As the solvent to be used, various solvents for dissolving the titanium alkoxide can be used. For example, alcohols,
There are ethers and aromatic hydrocarbons. The alcohol is represented by the following formula (II) R ₂ OH (II) [wherein R ₂ represents alkyl having 1 to 4 carbon atoms. And specific examples include ethanol, isopropyl alcohol and the like. Ethers include tetrahydrofuran, diethyl ether and the like. It is preferable that the solvent used for dissolving the titanium alkoxide and the solvent used for preparing a mixed solution consisting of water and the solvent added during the hydrolysis are of the same type. The amount of the solvent used for dissolving the titanium alkoxide is usually 0.5 to 1 mol of the titanium alkoxide.
Moles to 50 moles.

The fatty acid used is represented by the following formula (II)
I) R ₃ COOH (III) [In the formula (III), R ₃ represents hydrogen or a saturated or unsaturated hydrocarbon residue. ] Are exemplified.
Specific examples of saturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, Examples include pentadecylic acid, palmitic acid, heptadecylic acid, isostearic acid, nonadecanoic acid, arachinic acid, behenic acid, lignoceric acid, serotinic acid, heptacosanoic acid, montanic acid, melissic acid, and lacceric acid. Specific examples of unsaturated fatty acids include acrylic acid, crotonic acid, isocrotonic acid, undecylenic acid, oleic acid, elaidic acid, setreic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid , Stearic acid and the like. Among them, it is recommended to use a fatty acid represented by the formula (III), wherein R ₃ is a saturated or unsaturated hydrocarbon residue having 8 or more carbon atoms. The amount of the fatty acid in the polymer solution varies depending on the type and is not unique, but is usually 0.01 mol or more based on 1 mol of titanium alkoxide used for preparing the polymer solution.
Preferably it is 0.05 mol or more, and 0.5 mol or less,
Preferably it is at most 0.3 mol. If the amount of fatty acids is 0.0
If the amount is less than 1 mol, porous titania exhibiting excellent activity may not be obtained. If the amount of the fatty acid is more than 0.5 mol, the mechanical strength of the porous titania may decrease. The fatty acid may be present in a predetermined amount in the polymer solution at the time of baking, and may be present, for example, by a method of adding a fatty acid to a titanium alkoxide solution or a method of adding a fatty acid to a polymer solution. .

The fibrous porous titania according to the present invention will be described in detail below. This fibrous porous titania is obtained by dissolving a titanium alkoxide in a solvent, adding a mixed solution comprising water and a solvent to a titanium alkoxide solution, hydrolyzing and polymerizing the polymer, and forming a polymer in the titanium alkoxide solution. Producing (hereinafter referred to as "step"), dissolving the polymer in an organic solvent in which the polymer is soluble to obtain a polymer solution (hereinafter referred to as "step"), and the polymer solution as a spinning solution (Hereinafter referred to as a step) by spinning the precursor fiber, and a step of firing the precursor fiber (hereinafter referred to as a step).

The step is carried out by a method of adding a mixed solution of water and a solvent to a titanium alkoxide solution obtained by dissolving the titanium alkoxide represented by the formula (I) in a solvent, hydrolyzing the titanium alkoxide, and polymerizing the mixture. It can be carried out. Various solvents capable of dissolving titanium alkoxide can be applied to the solvent used for dissolving the titanium alkoxide and the solvent used for preparing the mixed solution to be added at the time of hydrolysis, for example, alcohols, ethers, There are aromatic hydrocarbons. The alcohol is represented by the formula (II). The mixed solution has a water concentration of about 1% by weight or more.
It is about 50% by weight, and its addition amount is usually in the range of 1.5 mol to 4 mol in terms of H ₂ O per mol of titanium alkoxide used as a raw material.

In the step, a mixed solution of water and a solvent is added to a titanium alkoxide solution obtained by dissolving the titanium alkoxide in a solvent under an atmosphere of an inert gas such as nitrogen, followed by hydrolysis and polymerization. Is preferred. When the fatty acid represented by the formula (III) is added, for example, a method of adding a predetermined amount of the fatty acid to the titanium alkoxide solution can be performed. However, when the amount of the fatty acid is more than 0.5 mol, it is difficult to obtain a fibrous porous titania having a sufficient tensile strength.

When the catalyst component is added, for example, V, W, Al, As,
Elements of Ni, Zr, Mo, Ru, Mg, Ca, Fe, Cr and Pt or compounds thereof are added. Examples of the compound include vanadium alkoxide, vanadyl alkoxide, triethoxy vanadyl, vanadium acetylacetonate, vanadium chloride, vanadium compound such as vanadyl chloride, tungsten alkoxide, tungsten compound such as tungsten chloride, alkyl aluminum, and aluminum alkoxide. Aluminum compounds, arsenic compounds such as arsenic chloride, nickel alkoxide, nickel compounds such as nickel chloride, zirconium alkoxide, zirconium acetylacetonate, zirconium butoxyacetylacetonate, zirconium compounds such as zirconium tetrabutoxide, molybdenum oxyacetylacetonate , Molybdenum compounds such as molybdenum chloride, ruthenium such as ruthenium chloride Um compounds, magnesium alkoxides, magnesium acetylacetonate, magnesium compounds such as magnesium chloride, calcium alkoxides,
Calcium compounds such as calcium chloride, iron compounds such as iron alkoxide, iron acetylacetonate and iron chloride, chromium compounds such as chromium alkoxide and chromium acetylacetonate, platinum compounds such as platinum acetylacetonate and platinum chloride, etc. Is mentioned. Here, vanadium alkoxide is vanadium methoxide, vanadium ethoxide, vanadium n-propoxide, vanadium isopropoxide, vanadium n-butoxide,
Vanadium sec-butoxide and vanadium ter
The term generically refers to t-butoxide and the like, and the same applies to other metal alkoxides. The amount of the catalyst component to be added varies depending on the application. For example, in the denitration application, the amount is 0.001% by weight to 50% by weight in terms of oxide based on the obtained titania catalyst. The catalyst component may be added by a method that allows a predetermined amount of the catalyst component to be present in the polymer solution at the time of calcination. For example, there is a method of adding to a titanium alkoxide solution or a method of adding to a polymer solution.

In the case where the polymer formed in the titanium alkoxide solution precipitates in the step, the solvent may be removed or partially removed, and then the concentration of the spinning solution may be adjusted. On the other hand, when the produced polymer does not precipitate in the titanium alkoxide solution, the concentration of the spinning solution may be directly adjusted.

In the hydrolysis and polymerization of the titanium alkoxide solution in the step, a mixed solution of water and a solvent is added, and the titanium alkoxide solution is refluxed.
It is preferable to carry out the reaction while distilling out the same amount of solvent as the amount of the solvent contained in the mixed solution to be added. By performing hydrolysis and polymerization by such a method, it is possible to suppress a decrease in titanium concentration in the titanium alkoxide solution after hydrolysis and polymerization.

The step can be carried out in an atmosphere of an inert gas such as nitrogen gas by a method in which the polymer obtained in the step is dissolved in an organic solvent in which the polymer is soluble. The organic solvent may be any as long as it dissolves fatty acids used in the production of porous titania, and includes alcohols such as ethanol and isopropyl alcohol, ethers such as tetrahydrofuran and diethyl ether, and aromatics such as benzene and toluene. And hydrocarbons. In addition, the fatty acid represented by the formula (III) and the catalyst component shown above can be added in a step, for example, a method of adding a predetermined amount of a fatty acid to a polymer solution, or a method of adding a polymer solution. It can be performed by a method of adding a predetermined amount of a catalyst component.

In the step, after the polymer obtained in the step is dissolved in an organic solvent to prepare a polymer solution, the polymer solution is removed by heating or reducing the pressure of the organic solvent, and the polymer solution is concentrated. It is preferable to prepare a spinning solution having a concentration of 50% by weight to 80% by weight. The viscosity of the obtained spinning solution at 40 ° C. is usually 10 poise (1 Pa ·
s) to 2000 poise (200 Pa · s), preferably 20 poise (2 Pa · s) to 1500 poise (150 P)
a · s).

The step can be performed by various spinning methods such as nozzle extrusion spinning, centrifugal spinning, and blow spinning of the spinning solution obtained in the step. The obtained precursor fiber may be stretched by a rotating roller or a high-speed air stream.

The step can be performed by firing the precursor fiber obtained in the step at 200 to 900 ° C.
Further, the precursor fiber is preferably subjected to a steam treatment before or during the firing. The steam treatment may be performed using a thermo-hygrostat, a baking furnace, or the like. Usually, the temperature of the steam treatment is 70 ° C. or higher, preferably 85 ° C. or higher.
The temperature is suitably not more than 00 ° C., and the partial pressure of water vapor is not less than 0.3 atm (0.03 MPa), preferably 0.5 atm (0.
05 MPa) or more, and the contact time is 30 minutes or more, preferably 1 hour or more, and more preferably 5 hours or more. When performing steam treatment at the time of baking, the treatment may be performed by adjusting the temperature rising rate while maintaining a predetermined humidity by a method of blowing steam into a baking furnace or a method of spraying water. In this case, the precursor fibers need only be maintained in an atmosphere having a water vapor partial pressure of 0.3 atm (0.03 MPa) or more between 70 and 300 ° C. for at least 30 minutes or more, and thereafter, a low water vapor partial pressure. It may be fired in an atmosphere.

In producing the porous titania of the present invention, a compound having active hydrogen may be added to the titanium alkoxide solution. Further, a silicon compound may be added to the titanium alkoxide solution or the spinning solution. Examples of the compound having active hydrogen include a compound represented by the following formula (IV): R ₄ COCH ₂ COR ₅ (IV) [In the formula (IV), R ₄ is alkyl or alkoxy having 1 to 4 carbon atoms, and R ₅ is 1 to 4 carbon atoms. Represents alkyl or alkoxy. The preferred are β-diketone compounds or alkyl salicylates represented by the formula: As the β-diketone compound, ethyl acetoacetate and isopropyl acetoacetate are preferable, and as the salicylic acid alkyl ester, ethyl salicylate and methyl salicylate are preferable.
The amount of the compound having active hydrogen is 0.05 mol or more, preferably 0.1 mol, per 1 mol of titanium alkoxide.
Mol or more, and suitably 1.9 mol or less, more preferably 1.0 mol or less. As the silicon compound, in the following formula _{(V) Si n O n-} 1 (OR 6) 2n + 2 (V) [Formula (V), R ₆ represents an alkyl having 1 to 4 carbon atoms, n
Represents one or more numbers. ] Are preferred. Among them, R ₆ in the formula (V) is ethyl and n is 4
A recommendation of ~ 6 is recommended.

[0030]

The porous titania of the present invention exhibits an excellent denitration action, and can be efficiently denitrated by using it as a catalyst. Further, when the catalyst according to the present invention is applied, denitration, oxidation of organic substances, decomposition of dioxins, decomposition and removal of organic solvents, pesticides or surfactants in water, and the like can be efficiently performed. Further, according to the porous titania of the present invention and the catalyst using the same, the required installation area of the catalyst can be reduced, and the exhaust gas treatment device such as a denitration device can be downsized.

According to the production method of the present invention, the porous titania can be easily produced.

[0032]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited by the examples. In the present invention, the anatase crystallite diameter, anatase crystallization ratio, BET specific surface area, and pore volume of porous titania were determined by the following methods. In the examples, fibrous porous titania is shown.

Anatase crystallite diameter: After crushing porous titania in a mortar, an X-ray diffraction spectrum was measured with an X-ray diffractometer RAD-IIA (manufactured by Rigaku Denki), and the half-width of the peak on the (101) plane was measured. β (radian) and the peak position θ (radian) of the (101) plane are obtained, and the crystallite diameter L is calculated by the following equation.
(Nm) was calculated. L = K · λ / (β · cos θ) [where K is a Scherrer constant of 0.94, and λ (nm) represents a measured X-ray wavelength (CuKα ray: 0.15406 nm). ]

Crystallization rate of anatase: After the porous titania was crushed in a mortar, the X-ray diffraction spectrum was measured with an X-ray diffractometer RAD-IIA (manufactured by Rigaku Denki), and the peak area S ₁ of the (101) plane was measured. And the crystallization rate A is calculated by the following equation.
(%) Was calculated. A = S ₁ / (S ₂ · x) [where S ₂ is a standard sample (trade name: STT-65C-
S, product of titanium industry), area of peak of (101) plane, x
Represents the molar fraction of titanium with respect to all constituent elements (excluding oxygen) in porous titania. ]

BET specific surface area (m ² / g), total pore volume (cm ³ / g), volume of pores having a pore radius of 1 nm or more (cm ³ / g): Porous titania in a mortar After pulverization, gas adsorption / desorption analyzer Omni Soap 36
0 (manufactured by COULTER), deaerated in vacuum under the conditions of a temperature of 130 ° C., a holding time of 6 hours, and a degree of vacuum of 6 × 10 ⁻⁵ Torr (8 mPa). A volume distribution curve was determined, and each was calculated from the distribution curve.

The denitration test was carried out using porous titania 0.2
g into a glass reaction tube with an inner diameter of 12 mm
mm, NO 100 ppm, N
A mixed gas containing 200 ppm of H ₃ , 10% of O ₂ , and 20% of H ₂ O at 200 ° C. is passed at a flow rate of 1 NL / min, and the NO concentration at the inlet and the NO concentration at the outlet of the reaction tube are measured by a NOx automatic meter ECL-. The measurement was carried out using a model 77A (manufactured by Yanagimoto Seisakusho), and the denitration rate (%) was calculated by the following equation. Denitration rate = (Inlet NO concentration-Outlet NO concentration) / Inlet NO concentration x 100

Example 1 225 g of titanium tetraisopropoxide (first-class reagent, manufactured by Wako Pure Chemical Industries) as a titanium alkoxide, and vanadium isopropoxide (manufactured by Nichia Corporation) 6 as a catalyst component
1.9 g and 10.3 g of ethyl acetoacetate (special grade reagent, manufactured by Wako Pure Chemical Industries) were dissolved in 77.8 g of isopropyl alcohol (special grade reagent, manufactured by Wako Pure Chemical Industries) as a solvent. After refluxing for an hour, a titanium alkoxide solution was prepared. At this time, the amount of the catalyst component to be added is 27% by weight as vandium oxide (V ₂ O ₅ ) based on the obtained fibrous porous titania. Also,
The addition amount of ethyl acetoacetate is 0.1 mol per 1 mol of titanium tetraisopropoxide. Then water 32.
7 g and 294.9 g of isopropyl alcohol were mixed to prepare a mixed solution having a water concentration of 10% by weight. The amount of this water is 2.3 per mole of titanium tetraisopropoxide.
0 mol.

The titanium alkoxide solution obtained above was refluxed in a nitrogen atmosphere, and at the same time, the mixed solution obtained above was added with stirring while distilling off the solvent. The solvent distillation rate and the solvent supply rate by the addition of the mixed solution were adjusted to be substantially equal. The addition time of the mixed solution was 96 minutes.

When 1.80 mol of the mixed solution was added to 1 mol of titanium tetraisopropoxide, precipitation of the polymer started in the titanium alkoxide solution, and when the whole amount of the mixed solution was added, the titanium alkoxide solution was converted into the polymer slurry. It became.

After the obtained polymer slurry was refluxed for 1 hour in a nitrogen atmosphere, the solvent was distilled off by heating, and the titanium concentration in the polymer slurry was 2.97 in terms of Ti.
It concentrated until it became × 10 ^-3 mol / g.

To the concentrated polymer slurry, 273 g of tetrahydrofuran (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added as an organic solvent in a nitrogen atmosphere, and the mixture was refluxed for 1 hour to dissolve the polymer. (Reagent, manufactured by Wako Pure Chemical Industries) 33.8 g was added, and the mixture was refluxed for 1 hour to obtain a polymer solution.

The obtained polymer solution was filtered through a fluorine resin membrane filter having a pore diameter of 3 μm in a nitrogen atmosphere, and then heated to distill a mixed solvent of isopropyl alcohol and tetrahydrofuran and concentrated to obtain 247 g of a spinning solution. Was. The viscosity of this spinning solution at 40 ° C. was 50 poise (5 Pa · s).

The spinning solution obtained above was kept at 40 ° C.
0 kg / cm ² (2 MPa) nitrogen gas with a pore size of 50 μm
Was extruded from a nozzle into an air atmosphere at 40 ° C. and a relative humidity of 60%, and wound up at a speed of 70 m / min to obtain a precursor fiber.

The obtained precursor fiber was heated at 85 ° C. and a relative humidity of 9
After steam treatment in a 5% constant temperature and humidity chamber for 15 hours, the temperature was increased at 200 ° C./hour, and calcined in air at 350 ° C. for 1 hour to have an anatase crystal structure and a fiber diameter of 15 μm.
Was obtained. Table 1 shows the physical properties of the obtained fibrous porous titania and the denitration rate when a denitration test was performed using the same.

Example 2 A fibrous porous titania was obtained in the same manner as in Example 1, except that the firing temperature was changed from 350 ° C. to 400 ° C. Table 1 shows the physical properties of the obtained fibrous porous titania and the denitration rate when a denitration test was performed using the same.

Example 3 A fibrous porous titania was obtained in the same manner as in Example 1, except that the firing temperature was changed from 350 ° C. to 300 ° C. Table 1 shows the physical properties of the obtained fibrous porous titania and the denitration rate when a denitration test was performed using the same.

Example 4 225 g of titanium tetraisopropoxide (first-class reagent, manufactured by Wako Pure Chemical Industries) as a titanium alkoxide, and vanadium isopropoxide (manufactured by Nichia Chemical Industry) 6 as a catalyst component
1.9 g and 20.6 g of ethyl acetoacetate (special grade reagent, manufactured by Wako Pure Chemical Industries) were dissolved in 67.5 g of isopropyl alcohol (special grade reagent, manufactured by Wako Pure Chemical Industries) as a solvent. After refluxing for an hour, a titanium alkoxide solution was prepared. At this time, the addition amount of the catalyst component is an amount that becomes 27% by weight as vanadium oxide (V ₂ O ₅ ) in the obtained fibrous porous titania. The addition amount of ethyl acetoacetate is 0.2 mol per 1 mol of titanium isopropoxide. Next, 35.5 g of water and 320.5 g of isopropyl alcohol were mixed to prepare a mixed solution having a water concentration of 10% by weight.

The titanium alkoxide solution obtained above was refluxed in a nitrogen atmosphere, and at the same time, the mixed solution obtained above was added with stirring while the solvent was distilled off. The solvent distillation rate and the solvent supply rate by the addition of the mixed solvent were adjusted to be substantially equal. The addition time of the mixed solvent is 101
Minutes.

When 2.07 mol of the mixed solution was added to 1 mol of titanium tetraisopropoxide, precipitation of a polymer started in the titanium alkoxide solution. When the entire mixed solution was added, the titanium alkoxide solution was converted into a polymer slurry. It became.

After the obtained polymer slurry was refluxed for 1 hour in a nitrogen atmosphere, the solvent was distilled off by heating, and the titanium concentration in the polymer slurry was 2.85 in terms of Ti.
It concentrated until it became × 10 ^-3 mol / g.

To a concentrated polymer slurry, 269 g of tetrahydrofuran (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added as an organic solvent in a nitrogen atmosphere, and the mixture was refluxed for 1 hour to dissolve the polymer. A solution prepared by dissolving 23.8 g of (reagent, Wako Pure Chemical Industries) in 23.8 g of tetrahydrofuran (reagent grade, Wako Pure Chemical Industries) was added and refluxed for 1 hour to obtain a polymer solution.

The obtained polymer solution was filtered through a fluorine resin membrane filter having a pore size of 3 μm in a nitrogen atmosphere, and then heated to distill a mixed solvent of isopropyl alcohol and tetrahydrofuran and concentrated to obtain 249 g of a spinning solution. Was. The viscosity of this spinning solution at 40 ° C. was 50 poise (5 Pa · s).

The obtained spinning solution is kept at 40 ° C.
The precursor fiber was extruded from a nozzle having a pore diameter of 50 μm into an air atmosphere at 40 ° C. and a relative humidity of 60% with a nitrogen gas of g / cm ² (2 MPa) to obtain a precursor fiber.

The obtained precursor fiber was heated to 85 ° C. and a relative humidity of 9
After steam treatment in a 5% constant temperature and humidity chamber for 15 hours, the temperature was increased at 200 ° C./hour, and calcined in air at 350 ° C. for 1 hour to have an anatase crystal structure and a fiber diameter of 15 μm.
Was obtained. Table 1 shows the physical properties of the obtained fibrous porous titania and the denitration rate when a denitration test was performed using the same.

Comparative Example 1 225 g of titanium tetraisopropoxide (first-class reagent, manufactured by Wako Pure Chemical Industries) as a titanium alkoxide, and vanadium isopropoxide (manufactured by Nichia Corporation) 6 as a catalyst component
1.9 g and 41.2 g of ethyl acetoacetate (special grade reagent, manufactured by Wako Pure Chemical Industries) were dissolved in 18.1 g of isopropyl alcohol (special grade reagent, manufactured by Wako Pure Chemical Industries) as a solvent. After refluxing for an hour, a titanium alkoxide solution was prepared. At this time, the addition amount of the catalyst component is an amount that becomes 27% by weight as vanadium oxide (V ₂ O ₅ ) in the obtained fibrous porous titania. The addition amount of ethyl acetoacetate is 0.4 mol per 1 mol of titanium isopropoxide. Next, 30.6 g of water and 275.8 g of isopropyl alcohol were mixed to prepare a mixed solution having a water concentration of 10% by weight.

The titanium alkoxide solution obtained above was refluxed in a nitrogen atmosphere, and at the same time, while the solvent was distilled off, the mixed solution prepared above was added with stirring. Next, after refluxing for 1 hour in a nitrogen atmosphere, the solvent was distilled off by heating as it was, and the Ti concentration was 3.27 × 1.
It was concentrated to 0 ^-3 mol / g.

To a concentrated polymer slurry, 271 g of tetrahydrofuran (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added as an organic solvent in a nitrogen atmosphere, and the mixture was refluxed for 1 hour to dissolve the polymer, and then refluxed for 1 hour. Thus, a polymer solution was obtained.

The obtained polymer solution was filtered through a fluorine resin membrane filter having a pore size of 3 μm in a nitrogen atmosphere, and then heated to distill a mixed solvent of isopropyl alcohol and tetrahydrofuran and concentrated to obtain 197 g of a spinning solution. Was. The viscosity of this spinning solution at 40 ° C. was 50 poise (5 Pa · s).

The obtained spinning solution is kept at 40 ° C.
The precursor fiber was extruded from a nozzle having a pore diameter of 50 μm into an air atmosphere at 40 ° C. and a relative humidity of 60% with a nitrogen gas of g / cm ² (2 MPa) to obtain a precursor fiber.

The obtained precursor fiber was heated at 85 ° C. and a relative humidity of 9
After steam treatment in a 5% constant temperature and humidity chamber for 15 hours, the temperature was increased at 200 ° C./hour, and calcined in air at 400 ° C. for 1 hour to have an anatase crystal structure and a fiber diameter of 15 μm. A fibrous porous titania was obtained. Table 1 shows the physical properties of the obtained fibrous porous titania and the denitration rate when a denitration test was performed using the same.

Comparative Example 2 A fibrous porous titania was obtained in the same manner as in Comparative Example 1, except that the firing temperature was changed from 400 ° C. to 300 ° C. Table 1 shows the physical properties of the obtained fibrous porous titania and the denitration rate when a denitration test was performed using the same.

[0062]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B01J 35/10 301 B01D 53/36 102D 102B (72) Inventor Miaki Takeuchi 5th Sokaicho, Niihama City, Ehime Prefecture No. 1 Sumitomo Chemical Co., Ltd. F-term (reference) 4D048 AA06 AB02 BA01X BA02X BA03X BA07X BA07Y BA08X BA22X BA23X BA23Y BA25X BA26X BA27X BA30X BA32X BA36X BA38X BB08 4G047 CA02 CB06 CB08 BA05 A05 BA08 A01 A08 A08 BC10A BC16A BC27A BC50A BC50B BC50C BC51A BC54A BC54B BC54C BC58A BC59A BC60A BC66A BC68A BC70A BC75A BE06A BE06B BE06C BE08A BE08B BE08C CA02 CA03 CA07 CA08 CA10 CA13 DA06 EA03X EA03 EC04 EC05 EC03 EC05

Claims (15)

[Claims] 1. An anatase type crystal structure having a crystallite size of 3 nm to 10 nm and an anatase crystallization ratio of 60 nm.
% Or more, BET specific surface area of 10 m ² / g or more, the total pore volume of 0.05 cm ³ / g or more, volume of pores having the above pore radius 1nm is 0.02 cm ³ / g or more Characterized porous titania. 2. The porous titania according to claim 1, having a BET specific surface area of 180 m ² / g or more. 3. The total pore volume is 0.2 cm ³ / g or more, and the volume of pores having a pore radius of 1 nm or more is 0.2
The porous titania according to claim 1 or 2, which has a density of at least cm ³ / g. 4. The porous titania according to claim 1, which is fibrous in shape. 5. A catalyst obtained by molding the porous titania according to claim 1. Description: 6. A titanium alkoxide solution is obtained by dissolving a titanium alkoxide in a solvent, a mixed solution comprising water and a solvent is added to the titanium alkoxide solution, and the mixture is hydrolyzed and polymerized to obtain a polymer solution. The method for producing porous titania according to claim 1, wherein the polymer solution is calcined in the presence of a fatty acid. 7. A titanium alkoxide solution is obtained by dissolving a titanium alkoxide in a solvent, a mixed solution comprising water and a solvent is added to the titanium alkoxide solution, and the mixture is hydrolyzed and polymerized to obtain a polymer solution. 2. The method for producing porous titania according to claim 1, wherein the polymer solution is subjected to steam treatment in the presence of a fatty acid, followed by firing. 8. A titanium alkoxide represented by the following formula (I): Ti (OR ₁ ) ₄ (I) wherein R ₁ represents alkyl having 1 to 4 carbon atoms. The method according to claim 6 or 7, wherein 9. The fatty acid is represented by the following formula (III): R ₃ COOH (III) wherein, in the formula (III), R ₃ represents hydrogen or a saturated or unsaturated hydrocarbon residue. The method according to any one of claims 6 to 8, wherein 10. A step of adding a mixed solution of water and a solvent to a titanium alkoxide solution obtained by dissolving a titanium alkoxide in a solvent, hydrolyzing and polymerizing the mixture, and forming a polymer in the titanium alkoxide solution. Dissolving the polymer in an organic solvent in which the polymer is soluble to obtain a spinning solution, spinning the spinning solution to obtain a precursor fiber, and firing the precursor fiber. The method for producing porous titania according to claim 1, wherein a fatty acid is added in the step or in the step. 11. The method according to claim 10, wherein the titanium alkoxide is represented by the formula (I). 12. The method according to claim 10, wherein the fatty acid is represented by the formula (III). 13. The method according to claim 10, wherein a catalyst component is added in the step or in the step. 14. The catalyst component is V, W, Al, As, N
14. The method according to claim 13, wherein the method is selected from i, Zr, Mo, Ru, Mg, Ca, Fe, Cr and Pt. 15. The method according to claim 10, wherein, in the step, the precursor fiber is subjected to steam treatment.