JPS635136B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a spinel catalyst carrier (hereinafter simply referred to as spinel carrier). In general, catalyst supports, especially catalyst supports for automobiles, are
Spinel is required to have a certain degree of strength from the perspective of vibration resistance, low density from the perspective of warm-up of the catalyst bed, and a specific surface area above a certain level. Since it has excellent thermal stability and thermal stability, its use as a catalyst carrier is being considered. However, as the alumina raw material used to produce spinel, α-alumina or γ-
When using alumina, the desired strength cannot be obtained if fired at temperatures below 1400°C, while the activity of the resulting support is low when fired at temperatures above 1400°C, and at the same time it is not possible to obtain the desired specific surface area. It has the disadvantage that it is unsuitable for use in catalyst devices that vibrate strongly, such as in automobiles. The present invention aims to eliminate these drawbacks, and provides a method for producing a spinel carrier that has sufficiently high strength even at low firing temperatures, allows the specific surface area to be freely selected depending on the purpose of use, and has a large specific surface area as desired. It is related to. That is, the method for producing a spinel carrier according to the present invention involves mixing a magnesium compound with activated alumina containing ρ-alumina and/or χ-alumina as a part or main component, molding the mixture, and then molding the mixture in a humid atmosphere under saturated water vapor pressure. It is characterized by curing, followed by drying and firing. The alumina used in the present invention is activated alumina containing at least 10% by weight of ρ-alumina and/or χ-alumina obtained by dehydrating aluminum hydroxide using a suitable rapid drying method, depending on the processing conditions. In addition, when magnesium hydroxide or magnesium oxide is used as the magnesium compound in the method for producing a spinel carrier of the present invention, after molding, there is a step of curing in warm water or hot water at 200°C or less under saturated steam pressure in a humidified atmosphere. has. Further, when magnesium carbonate is used as the magnesium compound in the method for producing a spinel carrier of the present invention, after molding, there is a step of curing in a humid atmosphere under saturated steam pressure or in hot water at 120° C. or higher. Furthermore, in the firing step performed in the production method of the present invention, the firing temperature can be set to 1400°C or less. The present invention will be explained in detail according to the following examples. Example 1 By passing aluminum hydroxide (average particle size 50μ) produced by the Bayer process through high-temperature gas at 700°C for an extremely short period of time, approximately the amount of crystal water contained in aluminum hydroxide crystals was removed. 80% is dehydrated to form activated alumina, and the alumina is reduced to an average particle size of approximately 10μ.
After pulverizing, 50 parts by weight of magnesium hydroxide (average particle size (10μ)) was added to 100 parts by weight of the powder, mixed, and then the powder was fed into a dish-type granulator, and the powder was pulverized to a diameter of approximately The pellets were granulated into spheres of 3 to 4.5 mm.
This granulated product was cured for 20 hours under saturated steam pressure at 100℃, then dried at 200℃ for 3 hours, and then heated to 1000℃ for 3 hours.
A spinel carrier was obtained by firing for a time (this carrier was
-4). Example 2 In Example 1, the temperatures were 700, 800, 900, 1100,
Carriers were obtained in the same manner as in Example 1 except for firing at 1200, 1350, and 1450°C for 3 hours. 6,
A-7, A-8). Example 3 In Example 1, the temperatures were 25, 50, 75, 125,
The carriers were cured at 150, 175, 200, 225, and 250°C for 20 hours, and otherwise were obtained in the same manner as in Example 1. ―
5, B-6, B-7, B-8, B-9, B-10
). Example 4 Activated alumina was obtained in the same manner as in Example 1, and after pulverizing the alumina to an average particle size of 10μ, magnesium oxide (average particle size of 20μ) was added to 100 parts by weight of the powder.
After adding 36 parts by weight and mixing, feed the powder to a dish-type granulator and grind it to a diameter of about 3 to 4.5 mm while spraying water.
It was granulated into spherical shapes. This granulated product was cured for 20 hours under saturated steam pressure at 150°C, then dried at 200°C for 3 hours, and then calcined at 1000°C for 3 hours to obtain a spinel carrier (this carrier was designated as C-4). Example 5 In Example 4, the temperatures were 700, 800, 900, 1100,
The carriers were calcined at 1200, 1350, and 1450°C for 3 hours, and in the same manner as in Example 4. 6,
C-7, C-8). Example 6 In Example 4, the temperature was set to 25, 50, 75, 100,
Cured at 125, 175, 200, 225, and 250℃ for 20 hours each.
Other carriers were obtained in the same manner as in Example 4 (these carriers were D-1, D-2, D-3, D-4, and D-1, respectively).
-5, D-7, D-8, D-9, D-10). Example 7 Activated alumina was obtained in the same manner as in Example 1, and after pulverizing the alumina to an average particle size of 10μ, 87 parts by weight of magnesium carbonate (average particle size of about 1μ) was added to 100 parts by weight of the powder and mixed. After that, the powder is fed into a dish-type granulator, and while water is sprayed, it is sized to a diameter of about 3~
It was granulated into 4.5 mm spheres. This granulated product was cured for 20 hours under saturated steam pressure at 200℃, and then heated at 200℃ for 3 hours.
After drying for an hour, it was calcined at 1000°C for 3 hours to obtain a carrier (this carrier was designated as E-4). Example 8 In Example 7, the temperatures were 700, 800, 900, 1100,
Carriers were obtained by firing at 1200, 1350, and 1450°C for 3 hours each, and in the same manner as in Example 7. ,E-
7, E-8). Example 9 In Example 7, the temperatures were 25, 50, 75, 100,
Carriers were obtained in the same manner as in Example 7 except that they were cured at 125, 150, 175, 225, and 250°C for 20 hours. 4,
F-5, F-6, F-7, F-9, F-10). Example 10 Commercially available activated alumina (main component: ρ-alumina (content 90% by weight), Sumitomo Aluminum Smelting KK,
Using powder of product name KHP-2), magnesium hydroxide (average particle size
Add 52 parts by weight of 10μ), mix, feed the powder to a dish-type granulator, and spray it with water until it is about 3 to 4.5 parts in diameter.
It was granulated into spheres of mm size. This granulated product was cured for 20 hours under saturated steam pressure at 100°C. Thereafter, it was dried at 200°C for 3 hours and then calcined at 1000°C for 3 hours to obtain a carrier (this carrier was designated as G-1). Example 11 Aluminum hydroxide (average particle size: 50μ) produced by the Bayer process was passed through high-temperature gas at 500°C for an extremely short period of time to remove crystallization water contained in aluminum hydroxide crystals. After dehydrating 50% of the activated alumina and pulverizing it to an average particle size of 10μ, 41 parts by weight of magnesium hydroxide (average particle size 10μ) was added to 100 parts by weight of the powder and mixed, followed by dish-shaped granulation. The powder was fed into a machine and granulated into spheres with a diameter of about 3 to 4.5 mm while spraying with water. This granulated product was cured for 20 hours under saturated steam pressure at 100°C.
Thereafter, it was dried at 200°C for 3 hours and then calcined at 1000°C for 3 hours to obtain a carrier (this carrier was designated as H-1). Example 12 In Example 1, curing was performed at 125°C for 20 hours at a water vapor partial pressure lower than the saturated water vapor pressure.
Thereafter, it was dried at 200°C for 3 hours and calcined at 1000°C for 3 hours to obtain a carrier (this carrier was designated as I-1). Example 13 In Example 1, the granulated product was cured in hot water at 75°C for 20 hours, then dried at 200°C for 3 hours, and calcined at 1000°C for 3 hours to obtain a carrier. The carrier was J-1). Example 14 In Example 1, the granulated product was cured for 20 hours by immersing it in hot water at 125°C, then dried at 200°C for 3 hours, and then calcined at 1000°C for 3 hours to obtain a carrier. The carrier was K-1). Example 15 This example describes an example in which the mixing ratio of activated alumina and magnesium hydroxide in Example 1 was changed. All the products were manufactured under the same conditions as in Example 1 except that the mixing ratio of these was changed. In this case, supports were prepared by adding 10, 20, 30, 40, 60, 70, and 80 parts by weight of magnesium hydroxide to 100 parts by weight of activated alumina.
2, L-3, L-4, L-6, L-7, L-8). Example 16 This example describes examples in which the average particle size of magnesium oxide in Example 4 was changed to 1μ, 5μ, 20μ, and 50μ. Everything was produced under the same conditions as in Example 4 except that the particle size of the magnesium oxide raw material was changed (these supports were M-1, M-2, M-
4, M-5). Example 17 This example describes examples in which the average particle diameter of activated alumina in Example 4 was changed to 3μ, 5μ, 15μ, 30μ, and 40μ. Everything was produced under the same conditions as in Example 4 except that the particle size of activated alumina was changed (these supports were N-1, N-2, N-4, N-
5, N-6). Comparative Example 1 Based on JP-A No. 53-39281, the average particle size is 0.5,
Five types of α-alumina powders of 1, 2.5, 4, and 5μ were prepared, and magnesium oxide powder with an average particle size of 50μ was added to each of these powders, and 1% by weight of dextrin was added to the mixed powder. In addition, these were sufficiently mixed, and then a spherical granulated product having a diameter of about 3.5 mm was obtained using a marmerizer (tablet forming machine). Note that 280 parts by weight of α-alumina powder was added to 100 parts by weight of the above magnesium oxide. Next, the granulated product was dried at 100℃ for 12 hours without curing, and then dried at 1400℃.
The spinel carriers were fired for 10 hours (these carriers were named P-1, P-2, P-3, P-4, P-5).
). Comparative Example 2 Comparative Example 1 using α-alumina with an average particle size of 2.5μ
The carriers were obtained by granulating and drying in the same manner as above and firing at 800, 1000, and 1200°C for 3 hours each (these carriers were
1, Q-2, and Q-3). Comparative Example 3 Comparative Example 1 using α-alumina with an average particle size of 2.5μ
Obtain a granulated product in the same manner as 50, 100,
After curing for 20 hours under saturated steam pressure at 150 and 200℃,
It was dried at 200℃ for 3 hours and calcined at 1000℃ for 3 hours.
4). Comparative Example 4 Aluminum hydroxide was fired at 800℃ for 3 hours,
Using γ-alumina with an average particle size of 0.5μ, it was granulated and dried in the same manner as in Comparative Example 1.
The carriers were obtained by firing at 1200°C and 1400°C for 3 hours each.
4). Comparative Example 5 Comparative Example 1 using γ-alumina with an average particle size of 0.5μ
Granulate it in the same way as 50, 100, 150, 200, 250.
After curing for 20 hours under saturated water vapor pressure at 200℃
The carriers were dried for an hour and fired at 1000°C for 3 hours (these carriers were designated as T-1, T-2, T-3, T-4, and T-5). Next, the catalyst carrier (A
In order to evaluate the performance of ~T), tests were conducted on the following items: Bulk density The fired carrier was placed in a 100 ml measuring cylinder.
40 c.c. was filled while tapping, and the volume and weight of the carrier were measured. Compressive Strength Granulated products with a diameter of 2.83 mm to 4.00 mm were selected from the fired carrier, and 20 grains each were measured using a Kiya type hardness tester, and the average value was taken as the compressive strength. Specific surface area Measurement was performed based on the N ₂ adsorption method using an automatic specific surface area measuring device model 2200 manufactured by Shimadzu. Table 1 shows the evaluation results of the carriers produced based on each example.

【table】

【table】

[Table] In the above formula, evaluation is performed according to the following criteria: ○... Bulk density 1.0 or less Compressive strength 5 or more Specific surface area 5 or more △... Bulk density 1.0 or more Specific surface area 5-2 ×... Compressive strength 3 or less, or specific surface area 2 or less In the table above, the characteristics of the carriers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 are shown in the figure. In the figure, a is the crushing strength of the carrier of the present invention, b is the same bulk density, c is the same specific surface area,
d represents the crushing strength of the comparative carrier, e represents the bulk density, and f represents the specific surface area. Based on the evaluation results of the carrier shown in the table above, some considerations will be made below regarding the results of the raw materials, manufacturing process conditions, and carrier properties. (1) Effect of type of alumina source (Examples 1, 10, 11)
and Comparative Examples 1 and 4) Crystallization water of aluminum hydroxide of Example 1 was added to 80%
No gypsite was observed in activated alumina dehydrated to %, and ρ-alumina and χ-alumina were
Linearly recognized (total content 60% by weight), Examples
In activated alumina obtained by dehydrating the crystallization water of No. 11 to 50%, a large amount of gypsite was observed, and ξ-alumina and χ-alumina were also observed by X-ray (total content 20% by weight). Further, in Example 10, commercially available ρ-alumina was used. On the other hand, in the raw materials used in Comparative Examples 1 and 4, α-alumina and γ-alumina were respectively confirmed as the main components by X-ray analysis. As is clear from the results shown in the table, when produced using activated alumina mainly composed of ρ-alumina and/or χ-alumina, a spinene support with high crushing strength and high specific surface area can be obtained even when fired at a low temperature. And this is independent of the method of manufacturing ρ-alumina and/or χ-alumina. This is thought to be largely due to the hydration properties of the activated alumina used in the present invention. That is, when the spinel carrier was granulated and the product after curing was examined by X-ray diffraction, all of the products of the present invention (Examples 1, 10, 11, and 18) were boehmite (including pseudoboehmite). was observed, and the diffraction lines of boehmite were relatively broad when cured at temperatures below 200℃, whereas those using α- or γ-alumina as raw materials (Comparative Examples 1 and 4) were cured at 200℃ or below.
No boehmite was observed in X-rays during the following curing, and crystalline boehmite with sharp diffraction lines was observed at curing temperatures of 225°C and 250°C. As described above, there is a difference in the products produced especially during low temperature curing between the activated alumina used in the present invention and the activated alumina used in the comparative examples, and this seems to affect the performance of the obtained spinel carrier. Therefore, it is better to use alumina that easily forms boehmite during curing, that is, ρ- and/or χ-alumina, as the alumina source, to obtain a support that has higher strength and a larger specific surface area even when fired at a lower temperature. (2) Effect of particle size of alumina source (Example 17, Comparative Example 1) When the activated alumina of the present invention is used, as is clear from the table, the pore diameter, specific surface area, and crushability depend on the particle size of the raw material. The influence on strength, bulk density, etc. is extremely small, whereas when α-alumina is used, the pore diameter varies depending on the particle size of the raw material. This is considered to be because the activated alumina used in the present invention has holes in its particles through which water can escape, increasing its specific surface area. On the other hand, in the case of the comparative example,
Since there are few or no pores within the particles, the specific surface area is small. Thus, when the activated alumina of the present invention is used, even if it is desired to obtain a support with a large specific surface area, it is not necessary to correspondingly reduce the particle size of the alumina raw material. (3) Effect of the type of magnesia source (Examples 1 to 9) Magnesium hydroxide was used as the magnesia source.
Mg(OH) ₂ (Example 1), magnesium oxide MgO
(Example 4), magnesium carbonate (MgCO ₃ ) ₄ .
Using Mg(OH) _{2.5H 2} O (Example 7) and changing other production conditions, the performance of the obtained carrier was evaluated. As is clear from the table, if the manufacturing conditions are selected, a spinel support with high strength and a large specific surface area can be obtained, but when magnesium carbonate is used, Mg ₆ Al ₂ CO ₃ (OH) ₁₆ . A large amount of 4H ₂ O is produced, resulting in a decrease in strength. Conversely, when magnesium hydroxide and magnesium oxide are used and cured at high temperatures, Mg ₆ Al ₂ CO ₃・(OH) ₁₆・
This is not preferable because a large amount of 4H ₂ O is produced and the strength decreases. In the former case, a carrier with good performance can be obtained by curing at 120°C or higher; in the latter case, it is preferable to set the curing temperature to 200°C or lower. In this way, when the types of magnesia raw materials are different, it is necessary to select appropriate curing conditions. (4) Effect of particle size of magnesia raw material (Example 16) Almost no effect was observed due to particle size of magnesia raw material. (5) Mixing ratio of alumina and magnesia raw materials (Example 15) Almost no effect was observed due to changes in the mixing amounts of alumina and magnesia. However, although the bulk density slightly changes depending on the amount of magnesia mixed, these changes greatly depending on the granulation state, so it cannot be concluded that this is due to the change in the amount of both. (6) Effect of curing conditions (Examples 1, 12, 13, 14) As stated in (2) above, there is a preferable curing temperature range depending on the type of magnesia source. Regarding curing time, all examples are 20
Although the time was determined by the time, there is little difference between shorter and longer times than this, and the time can be selected appropriately depending on the curing temperature. Furthermore, with regard to the atmosphere during curing, there is little difference in performance of the resulting carriers, regardless of whether the curing is in a humidified atmosphere with a saturated water vapor pressure or below, under a saturated vapor pressure, or in hot water or hot water. (7) Firing conditions (Examples 1, 2, 4, 5, 7, 8) As is clear from the examples of the present invention, the bulk density, specific surface area, and pore diameter of the obtained carrier vary depending on the firing temperature. Since the calcination temperature varies greatly, it is possible to select a calcination temperature that provides suitable characteristics depending on the intended use of the carrier. The firing time and the atmosphere during firing can be selected in various ways, and their influence on the properties of the carrier is extremely small. As is clear from the above description, the method for producing the spinel carrier of the present invention allows the use of aluminum hydroxide, which is an inexpensive raw material, and does not require the use of fine alumina raw materials in order to obtain a spinel carrier with a large specific surface area. . Furthermore, by selecting the firing conditions, particularly the firing temperature, important properties as a carrier, such as specific surface area, can be changed as appropriate, and it is also possible to lower the firing temperature sufficiently. The spinel carrier obtained in this way has high strength and specific surface area, and relatively low bulk density, and although there are conventional spinel carriers that satisfy one or two of these characteristics, Since there was no carrier that simultaneously satisfied all the properties, its performance was greatly improved. The spinel support obtained by the present invention can be widely used as a catalyst support for automobile exhaust gas purification, a catalyst support for fuel reforming, various exhaust gas purification catalyst supports, adsorbents, chemical reaction catalyst supports, etc. , which is of great industrial value.

[Brief explanation of the drawing]

The figure is a graph showing the relationship between the calcination temperature and the characteristics (compressive strength, bulk density, specific surface area) of the catalyst carrier in the spinel carriers obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

Claims (1)

[Scope of Claims] 1. A magnesium compound is mixed with activated alumina containing ρ-alumina and/or χ-alumina as a part or main component, molded, and then cured in a humidified atmosphere under saturated water vapor pressure. A method for producing a spinel catalyst carrier, which comprises drying and firing. 2 Using magnesium hydroxide or magnesium oxide as a magnesium compound, after molding, in a humid atmosphere, under saturated steam pressure, in hot water or hot water.
The method according to claim 1, comprising the step of curing at 75° to 200°C. 3. The method according to claim 1, which uses magnesium carbonate as the magnesium compound and includes the step of curing at 120° C. or higher in a humid atmosphere, under saturated steam pressure, or in hot water after molding. 4 In the firing process after molding, the firing temperature is
The method according to claim 1, wherein the temperature is 1400°C or less.