JPS6129775B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a shaped catalyst or a shaped carrier containing titanium oxide as a main component, a carrier obtained by the method, a catalyst obtained by using the carrier, a catalyst obtained by the method, and a method for producing a shaped catalyst using the catalyst. The present invention relates to a method for removing oxides. Catalysts or supports containing titanium oxide as a main component are widely known. For example, in JP-A-49-122473, Ti and Cu, Zn, Sn, Pb, Fe, P, Cr, Co,
A molded body of mixed oxide that combines Ni and V,
It is disclosed that the catalyst uses ammonia as a reducing agent and is very excellent as a catalyst for removing nitrogen oxides. Furthermore, JP-A-51-66277 discloses that a shaped titanium oxide carrier is excellent as a carrier for removing nitrogen oxides. Further, West German Publication No. 2,534,281 discloses that a catalyst in which V ₂ O ₅ is supported on a titanium oxide carrier is excellent in the reaction of oxidizing O-xylene to produce phthalic anhydride. Other various _TiO2
Catalytic systems with other metals or metal oxides are described in the Catalyst Handbook published by Jijinshokan. Furthermore, various methods for producing shaped titanium oxide carriers have been proposed prior to the present application. For example, the special public interest public in 1977-
43553, by adding aluminum powder to titanium oxide and firing at 800 to 900°C, and JP 51-67295, by mixing titanium oxide with alumina and acid and heating to a temperature below 800°C. In JP-A-51-67294, by mixing titanium oxide with an acid and heating it to a temperature below 800°C, in West German Publication-2554198, after firing the titanium oxide raw material at 400-800°C,
This is a method of producing a titanium oxide carrier by mixing titanium hydroxide, titania sol, and titanate ester, and then firing the mixture at 300 to 800°C. But according to one of these methods,
Although a shaped titanium oxide support with high mechanical strength can be obtained, the specific surface area and water absorption amount are small, making it unsuitable as a catalyst support. According to the method described above, a shaped titanium oxide support with a large specific surface area and water absorption amount can be obtained, but the mechanical strength of the titanium oxide support obtained by this method is insufficient for large catalyst tanks, especially in the case of a vertical type, since the inlet of the catalyst layer cannot be used. The falling distance from the catalyst to the bottom of the catalyst tank is long, and the titanium oxide support collapses due to collision. Also, relatively low temperature firing (600
C) to obtain a complex three-dimensional structure such as a honeycomb shape, this method cannot yield a molded product with mechanical strength that can withstand industrial use.
In order to improve these, the present inventors previously filed Japanese Patent Applications No. 154,606/1983 and Japanese Patent Application No. 89,429/1982 for a method for producing a catalyst or carrier containing titanium oxide as a main component. The feature of this application is that metatitanic acid obtained from the sulfuric acid method titanium oxide manufacturing process is used as a binder.
The purpose is to use a titanium hydroxide sol obtained by fixing H ₂ SO ₄ in the metatitanic acid with Ba salt and further peptizing it with hydrochloric acid. By the way, a carrier in which ceramic fibers are inserted into a molded carrier to internally reinforce the carrier, and a method for manufacturing the same, are disclosed in Japanese Patent Application Laid-open No. 4690-1983. However, when the above titanium hydroxide sol is used as a binder,
In the ceramic fibers disclosed in this specification, the ceramic fibers are attacked by the titanium hydroxide sol and cannot exhibit a sufficient reinforcing effect. Alternatively, the same can be said when exhaust gas containing sulfur oxides is treated using a catalyst obtained using the carrier according to the present invention. In view of the above facts, the present inventors have improved the method for producing a catalyst or carrier, which the present inventors previously filed as Japanese Patent Applications No. 51-89429 and 50-154606. We have found a method for obtaining a shaped catalyst or carrier having extremely high mechanical strength, high activity as a catalyst, and a large specific surface area and water absorption capacity as a carrier, and furthermore, They discovered that a catalyst using a carrier is suitable for decomposing nitrogen oxides into water and nitrogen by allowing ammonia to coexist in the exhaust gas containing nitrogen oxides, especially nitrogen oxides and sulfur oxides. . That is, a catalyst or carrier molding material mainly composed of titanium oxide and/or titanium hydroxide, high alkali-containing glass fiber and/or deposited refractory clay in the presence of titanium hydroxide sol,
By shaping, drying, and firing by any means, it is possible to obtain a molded body having extremely high mechanical strength, high activity as a catalyst, and a large specific surface area and water absorption amount as a carrier. In addition, in the above method, by mixing a catalyst substance as a subcomponent and/or a substance that becomes a catalyst component by calcination with the main component of the molding material, molding, drying, and calcination, it is possible to obtain a highly active catalyst with extremely high mechanical strength. . Furthermore, a catalyst in which a metal or metal oxide having nitrogen oxide decomposition activity by ammonia reduction, such as V, Fe, Cu, Co, Mo, W, etc., is supported on a titanium oxide support obtained by the above method, or the above-mentioned metal obtained by the above method. Alternatively, nitrogen oxides can be decomposed into harmless water and N ₂ at a high rate by contacting exhaust gas containing nitrogen oxides with ammonia added to a catalyst containing metal oxides. The present invention will be explained in detail below. The titanium hydroxide used in the present invention is, for example, metatitanic acid obtained from a sulfuric acid method titanium oxide production process, or orthotitanic acid obtained by neutralizing titanium sulfate, titanium tetrachloride, or the like. Which of these is used may be determined depending on the use of the carrier or catalyst. For example, when metatitanic acid is calcined, anatase-type titanium oxide is easily obtained, and this crystalline titanium oxide is suitable as a catalyst or carrier for removing nitrogen oxides, and when orthotitanic acid is calcined, rutile-type titanium oxide is easily obtained. ,
This crystalline titanium oxide is suitable as a catalyst for producing acetic acid from butene by gas phase oxidation. (Japanese Unexamined Patent Publication No. 49-94589) The same can be said of the titanium oxide used in the present invention. The titanium hydroxide sol used in the present invention is obtained by removing sulfuric acid coexisting in metatitanic acid obtained from the sulfuric acid method titanium oxide production process or fixing it as barium sulfate, and peptizing it with hydrochloric acid.
Barium chloride, which functions as both the sulfuric acid fixative and the peptizer, may also be added. The amount of titanium hydroxide sol added is suitably 1 to 50 wt% based on the weight of the catalyst or carrier as titanium oxide, and usually a catalyst or carrier having sufficient physical properties can be obtained with 5 to 20 wt% of each. Furthermore, titanium hydroxide sol is
By adding barium chloride to metatitanic acid in an amount less than the amount required to fix sulfuric acid and partially peptizing it, barium chloride can be present in the catalyst or carrier raw material. In addition, the titanium hydroxide sol used in the present invention plays a role as a binder that firmly binds particles of titanium oxide, catalytic material, etc. in the catalyst, and can hardly be obtained by simply mixing the catalytic material and the carrier material. The sol binds the two together, and the resulting catalyst system plays the role of exhibiting an excellent supporting effect. On the other hand, in the carrier, the sol serves as a binder that strengthens the bond between titanium oxide, etc., makes the fired product mechanically strong in the presence of the binder, and further improves the fired product. By using the powder obtained by pulverization, it is possible to obtain a molded product that has many macropores, has a small shrinkage rate, and is difficult to crack during impregnation. The high alkali content glass fiber used in the present invention is
It is an alkali-containing glass fiber in which N ₂ O + K ₂ O is 5 to 20 parts per 00 parts of glass fiber in terms of weight,
For example, C glass (8 to 12 parts of N ₂ O + K ₂ O), A
Glass (approximately 14.2 parts of N ₂ O + K ₂ O), G glass (approximately 11 parts of N ₂ O + K ₂ O), etc. can be used. Note that these glass fibers have strong acid resistance, and even when the titanium hydroxide sol used in the present invention is used as a binder, the glass fibers are not attacked and serve as a molded catalyst or an internal reinforcing material for the carrier. Further, the size of the fibers may be appropriately determined depending on the molding method or molding material. For example, in the case of the normal rolling granulation method, the fiber diameter is 1 to 10 μm, and the fiber length is 10 to 10 μm.
Approximately 1000 μ is preferable, and the amount added is 3 to 10 wt%.
is preferred. The sedimentary refractory clay used in the present invention is, for example, tributary rock, wood knot, frog's eye clay, etc. produced in Japan. These increase the plasticity of the molding material during molding, especially during extrusion molding, and make the molding material easier to form.
It plays the role of increasing the mechanical strength of the molded product by improving the packing of the molding material and eliminating distortion of the molded product. The amount of clay added is preferably 5 to 30 wt% based on the total weight of the catalyst or carrier material. The catalyst obtained using titanium oxide or the like described above is used in various reactions as described above, but is particularly suitable as a catalyst for selectively reducing nitrogen oxides to N ₂ and H ₂ O with NH ₃ . In the nitrogen oxide removal method of the present invention, the appropriate reaction temperature varies depending on the catalyst system or the presence or absence of sulfur oxides in the exhaust gas.
When V ₂ O ₅ -TiO ₂ does not contain sulfur oxides in the exhaust gas, the temperature is 150°C or higher, preferably 200°C or higher, and the catalyst system is Fe ₂ O ₃ -TiO ₂ and the exhaust gas does not contain sulfur oxides. is included, 250℃ or more preferably 300℃
That's all. In the present invention, the amount of ammonia coexisting is suitably 0.5 to 3 times the amount of nitrogen oxide in the processing gas. Preferably it is 0.5 to 1.5 times. The present invention will be specifically explained below using examples. Example 1 Component composition is TiO(OH) ₂ 40.4~49.0wt% (33~49.0wt% in terms of _TiO2 )
40wt%) H ₂ SO ₄ 2.0-3.2wt% (TiO ₂ standard 6.1-9.8wt%) H ₂ O 47.8-57.6wt% 1 kg of titanium oxide was extracted as titanium oxide from the titanium oxide manufacturing process using the sulfuric acid method. , barium chloride ( _BaCl2 .
After adding 42 g of 2H ₂ O) and 200 g of Kibushi clay to adjust the moisture content, the mixture was kneaded in a kneader, and then a honeycomb structure was obtained using an extruder equipped with a mold for extruding a honeycomb structure with a cell pitch of 5 m/m. The structure was dried at 100°C for 12 hours and then fired at 600°C for 3 hours to obtain a honeycomb shaped titanium oxide molded carrier. Example 2 1 kg of the metatitanic acid used in Example 1 was taken as titanium oxide, 42 g of barium chloride (BaCl ₂ 2H ₂ O) was added to the metatitanic acid, and the mixture was heated at 110°C.
After drying for 12 hours, it was fired at 600°C for 3 hours. The fired product was ground in a sample mill without a screen to obtain titanium oxide powder. 1 kg of titanium oxide powder, 100 g of frog's eye clay
C glass fibers having an average diameter of 200 μm and an average fiber length of 2 mm were dry mixed in a blender.
Take 100g of the above metatitanic acid as titanium oxide and add barium chloride ( _BaCl2 .
24 g of 2H ₂ O) was added and stirred sufficiently to obtain a titanium hydroxide sol. The titanium hydroxide sol was added to the above-mentioned dry mixture to adjust the moisture content, and then kneaded using a kneader. Thereafter, a honeycomb-shaped titanium oxide carrier was obtained in the same manner as in Example 1. Example 3 Titanium oxide powder 1 same as used in Example 2
100g of C glass fibers having an average diameter of 50μ and an average fiber length of 600μ were dry mixed in a blender. This mixed powder was used as titanium oxide obtained by diluting the titanium hydroxide sol used in Example 2 with water.
The titanium hydroxide sol was supplied to a marmerizer while being sprayed to obtain molded products with an average particle diameter of 5 mmφ. The molded product was dried at 110°C for 12 hours and then fired at 600°C for 3 hours to obtain a spherical titanium oxide support. Example 4 Titanium oxide powder similar to that used in Example 2
0.9 kg of vanadium pentoxide powder, 0.1 kg of vanadium pentoxide powder, and 100 g of C glass fiber similar to that used in Example 3 were dry mixed in a blender. This dry mixed powder was supplied to a marmerizer while spraying the titanium hydroxide sol used in Example 3, and the average particle size was 5 mmφ.
A molded product was obtained. After drying the molded product at 110℃ for 12 hours
The mixture was calcined at 500°C for 3 hours to obtain a spherical catalyst. Example 5 200 ml each of the titanium oxide carriers obtained in Example 1, Example 2, and Example 3 were dissolved in an aqueous solution containing 49 g of ammonium metavanadate and 140 g of oxalic acid, and the mixture was kept at 60° C. to prepare a panadil oxalate aqueous solution of 200 ml.
ml for 1 hour, then separate the carrier from the solution, drain the liquid, dry at 100°C for 12 hours, and incubate at 450°C for 1 hour.
The catalyst was fired for a period of time to obtain a catalyst in which vanadium pentoxide was supported on titanium oxide. Example 6 The catalysts obtained in Examples 1, 2, and 3 were
50mm Pyrex glass tube (to keep the outside warm)
was filled with an apparent volume of 86 ml, and brought into contact with the mixed gas having the composition shown in Table 1 below at a space velocity of 10,000 1/hr (room temperature equivalent) to determine the nitrogen oxide removal rate, ammonia decomposition rate, The N ₂ O byproduct rate was measured.
The results are shown in Table 2. Note that the nitrogen oxide removal rate and ammonia residual rate are expressed by the following formula. Γ Nitrogen oxide removal rate (%) = Nox concentration at catalyst layer inlet - Nox concentration at reaction tube outlet / Nox concentration at catalyst layer inlet x
100 Γ Ammonia residual rate (%) = _NH3 concentration at the reaction tube outlet/ _NH3 concentration at the catalyst layer inlet x 100

【table】

[Table] Reference example 1 Titanium oxide powder 0.9 similar to that used in Example 2
Kg, vanadium pentoxide powder 100g and average diameter 50μ,
100g of E-glass fibers having an average fiber length of 600μ were dry mixed in a blender. Thereafter, a spherical catalyst was obtained in the same manner as in Example 4. Reference Example 2 Example 6 using the spherical catalyst obtained in Reference Example 1
The reaction was carried out for 1000 hours under the same reaction conditions. Reference Example 3 The same amount of titanium hydroxide sol as in Example 2 was added to 1 kg of titanium oxide powder as in Example 2, and the same amount as in Example 2 was carried out to obtain a honeycomb-shaped titanium oxide carrier. Example 7 Regarding the catalysts or supports obtained in Example 1, Example 2, Example 3, Reference Example 1, and Reference Example 2, the compressive breaking strength (Kg), drop strength (%), and specific surface area ( ^m ) were compared in Table 3. However, ● Compressive fracture strength was determined using a Kiya hardness tester. In the case of a honeycomb-shaped molded body, pressure was applied in the axial direction. ●Drop strength, which is the survival rate of a non-destructive molded product when dropped from 4 m above the ground onto a steel plate set on the ground.

【table】

Claims (1)

[Claims] 1. In a method for producing a carrier containing titanium oxide as a main component, titanium oxide and/or titanium hydroxide and high alkali-containing glass fibers and/or deposited refractory clay are mixed in the presence of a titanium hydroxide sol by any means. A method characterized by forming, drying and firing. 2. In a method for producing a catalyst containing titanium oxide as a main component, titanium oxide and/or titanium hydroxide, a catalyst substance, and/or a substance that becomes a catalyst component by sintering, and a high alkali-containing glass fiber and/or deposited refractory clay are hydroxylated. A method characterized by forming, drying and sintering by any means in the presence of titanium sol.