JP2021151942A - Porous silica alumina particles and method for producing the same - Google Patents

Abstract

To provide porous silica-alumina particles having a high specific surface area and a high pore volume.SOLUTION: Amorphous porous silica-alumina particles having a small residual amount of alkali metal ions and mineral acid ions are provided by repeating a step of obtaining a mixture gel slurry through mixing of silica hydrogel with pseudo-boehmite alumina hydrate and washing and drying the mixture gel slurry.SELECTED DRAWING: None

Description

The present invention relates to porous silica-alumina particles having a high specific surface area and a high pore volume, and a method for producing the same.

Methods for preparing silica-alumina compositions are well known in the art, and the neutralization reaction method and the pH swing method are typical methods.

As a neutralization reaction (coprecipitation method, co-gelling method), as in Patent Documents 1 to 4, a solution of silica hydrogel and a metal salt is mixed, and an amorphous material containing the metal salt evenly inside is amorphous. Examples include preparation methods that allow the production of silica-alumina.

Further, as a pH swing method (immersion method), as in Patent Documents 5 and 6, amorphous silica is formed in a single container by changing the pH of the reaction mixture and thereby precipitating silica and alumina. -There is a preparation method that enables the production of alumina.

Special Publication No. 27-3989 Special Publication No. 31-1862 Special Publication No. 30-5963 Tokukousho 32-4-13 Gazette Special Table 2010-537808 Special Table 2016-502971

However, in the prior art, there is a problem that the porous silica alumina obtained from the preparation methods described in Patent Documents 1 to 6 ^{tends to have a relatively small specific surface area, that is, much smaller than 400 m 2 / g.} rice field.

Furthermore, there is a problem that the pore volume tends to be smaller than 1.0 ml / g.

An object of the present invention is to provide porous silica-alumina particles having a high specific surface area and a high pore volume, and a method for producing the same.

Against this technical background, the inventors have diligently studied to solve the above problems, and found that porous silica-alumina particles having a high specific surface area and a high pore volume can be obtained. It led to the development of the invention.
The present invention developed to solve the above problems and realize the above object is as follows. That is, the present invention is firstly a method for producing porous silica-alumina particles.
a. The process of obtaining a pseudo-boehmite alumina hydrate aqueous solution and
b. The process of obtaining an aqueous silica hydrogel solution and
c. The slurry obtained by mixing the pseudo-boehmite alumina hydrate aqueous solution and the silica hydrogel aqueous solution is adjusted to a pH range of 7.0 to 9.0, and the reaction is promoted at a temperature of 40 to 60 ° C. for 10 minutes to 2 hours. And the step of obtaining an aqueous solution of silica-alumina mixture
d. The first washing step of washing after the silica-alumina mixture cake 1 is obtained by filtering out the silica-alumina mixture aqueous solution.
e. A step of dispersing the silica-alumina mixture cake 1 in water, adjusting the pH to 8.0 to 12.0 at a temperature of 30 to 50 ° C., and then further heating to 80 ° C. or higher to obtain a silica-alumina gel slurry.
f. The first drying step of drying the silica-alumina gel slurry to obtain silica-alumina particles 1 and
g. The second washing step of suspending the silica-alumina particles 1 obtained by drying again, stirring the mixture, filtering the particles, and washing the silica-alumina particles 1 to obtain the silica-alumina particle cake 2.
h. We propose a method for producing porous silica-alumina particles, which comprises a second drying step of drying the silica-alumina particle cake 2 to obtain silica-alumina particles 2.

Secondly, the present invention is an amorphous porous silica-alumina particle.
The specific surface area SA measured by the BET method is in the range of ^{400 to 600 m 2 / g.}
The pore volume PV measured by the BJH method is in the range of 1.25 to 2.00 ml / g.
The average pore diameter PD measured by the BJH method is in the range of 8 to 20 nm.
Provided are porous silica-alumina particles characterized by a mass ratio of silica and alumina in the range of 2/98 to 70/30.

Note that the porous silica-alumina particles according to the present invention, further, an alkali metal ion (M ⁺⁾ containing 0.1 wt% in M _{2 O} in terms of the residual amount of the inorganic acid ion is 1.0 mass It is considered that% or less can be a more preferable solution.

An object of the present invention is to provide porous silica-alumina particles having a high specific surface area and a high pore volume as porous silica-alumina particles.

Hereinafter, preferred embodiments of the present invention will be described in detail.
[Porous Silica Alumina Particles]
The porous silica-alumina particles of the present invention (hereinafter, also simply referred to as “silica alumina particles”) are _{porous particles composed of silica (SiO 2} ) and alumina (Al ₂ O ₃ ), and have a high specific surface area and a high value. It is composed of an oxide having a pore volume.

The porous silica-alumina particles of the present invention are amorphous. Therefore, zeolite and the like, which are crystalline silica alumina, are not included in the silica alumina of the present invention. Whether or not the silica alumina of the present invention is amorphous can be determined from the X-ray diffraction pattern. Specifically, in the X-ray diffraction pattern obtained by X-ray diffraction measurement of the silica alumina of the present invention, a diffraction peak having a half-value total width of less than 1.0 ° in the range of 5 ° ≤ 2θ ≤ 50 ° must be shown. For example, it can be determined that the silica alumina of the present invention is amorphous.

In the silica-alumina particles obtained in the present invention, the ratio S / A of silica and alumina is in the range of mass ratio S / A: 2/98 to 70/30 converted by _{SiO 2} and Al ₂ O _{3, respectively.} Preferably, S / A is in the range of 5/95 to 65/35. If the alumina ratio is lower than S / A: 70/30, the amount of solid acid tends to decrease, and when the particles are used as a decomposition catalyst or the like, the required decomposition rate cannot be obtained. On the other hand, when the silica ratio is lower than S / A: 2/98, the specific surface area SA tends to be lower.

The specific surface area SA by the BET method of the obtained silica-alumina particles is in the range of 400-600m ² / g, preferably in the range of 420~550m ² / g. The reason for setting the lower limit is that when it is used as a decomposition catalyst, it is advantageous that the specific surface area SA is appropriately high from the viewpoint of contactability and reactivity with hydrocarbons. On the other hand, when the specific surface area SA ^{exceeds 600 m 2} / g, the pore diameter PD becomes too small, becomes smaller than the hydrocarbon molecule size of the reactant, and cannot diffuse into the pores, so that an effective reaction may not occur. ..

Further, the pore volume PV by the BJH method is in the range of 1.25 to 2.00 ml / g, preferably in the range of 1.30 to 1.90 ml / g. When the pore volume PV is less than 1.25 ml / g, there is less effective reaction field with hydrocarbon molecules. On the other hand, when the pore volume PV exceeds 2.00 ml / g, when used as a decomposition catalyst, the crushing strength or abrasion strength of the molded product becomes weak, and when it is filled in the reactor, powdering may occur and operation may not be possible. be.

The average pore diameter PD measured by the BJH method is in the range of 8 to 20 nm (80 to 100 Å), preferably in the range of 10 to 18 nm (100 to 180 Å). The reason for setting the lower limit is that if the average pore diameter PD is too small, there are many pores smaller than the hydrocarbon molecule size of the reactant, and the pores cannot be diffused, so that an effective reaction may not occur. On the other hand, the reason for setting the upper limit is that the specific surface area is lowered and the active site of the decomposition reaction is lowered.

The silica-alumina particles of the present application are also characterized by a small residual amount of positive and negative impurity ion components. Examples of the residual cation include alkali metal ions such as residual sodium ion and potassium ion. They alkali metal ions ^{(M +)} amount is 0.1 mass% in _{M 2} O in terms of, and preferably not more than 0.05 mass%. Further, the residual amount of inorganic acid ions such as sulfate ion and nitrate ion is 1.0% by mass or less, preferably 0.5% by mass or less. By reducing the impurity ion component, the poisoning of solid acid points and active metals is suppressed.

[Method for producing porous silica-alumina particles]
<A. Step to obtain pseudo-boehmite alumina hydrate aqueous solution>
<< a-1. Mixing process >>
Methods for preparing pseudo-boehmite alumina particles are widely known, and among them, a method of neutralizing an aluminum salt and / or an aluminate solution to form a precipitate of pseudo-boehmite alumina particles is preferable. As the aluminum salt, any aluminum salt such as aluminum sulfate, aluminum chloride, and aluminum nitrate can be used. Further, as the aluminate, any one such as sodium aluminate and potassium aluminate can be used. The neutralization reaction includes a method of adding an alkaline aqueous solution such as sodium hydroxide, potassium hydroxide, and aqueous ammonia to an aqueous aluminum salt solution, a method of adding an aqueous solution of an acid such as sulfuric acid, hydrochloric acid, and nitrate to an aqueous solution of aluminate, and an aluminum salt. Either of the methods of mixing the aqueous solution and the aluminate aqueous solution may be used, but from the viewpoint of production cost, the method of mixing the aluminum salt aqueous solution and the aluminate aqueous solution to obtain a pseudo-boehmite alumina hydrate aqueous solution is preferable. ..

<< a-2. Aging process >>
After mixing the two liquids to carry out a neutralization reaction, the pH of the solution is in the range of 7.0 to 10.0 in order to promote the reaction to pseudo-boehmite alumina hydrate (hereinafter, also referred to as “aging”). By adjusting the temperature in the range of 30 to 70 ° C., the reaction is promoted and pseudoboehmite alumina hydrate can be obtained. When the pH exceeds 10.0, a biasite phase having a small specific surface area is formed, which may reduce the activity of the finally produced catalyst. Further, when the pH is lower than 7.0, the pore volume of the finally obtained pseudo-boehmite alumina particles tends to decrease, which may make it difficult to produce pseudo-boehmite alumina particles suitable for the catalyst.

The aging temperature is preferably in the range of 30-70 ° C. When the temperature is 30 ° C. or lower, the particles tend to agglomerate strongly, and the pore volume of the powder obtained through the aging and drying step may become small. Further, at 70 ° C. or higher, biased light is likely to precipitate, which is not preferable. The aging time is preferably in the range of 5 to 120 minutes, preferably 10 to 100 minutes, more preferably 10 to 90 minutes. If it deviates from this range, the pore volume of the finally obtained pseudo-boehmite alumina particles may be 0.8 cc / g or less, and it may not be possible to use the pseudo-boehmite alumina particles for a catalyst. The aging time is not particularly limited, but it is preferably 120 minutes or less from the viewpoint of production efficiency. If the aging time is too long, the specific surface area of the finally obtained pseudo-boehmite alumina particles tends to be small.

<B. Step to obtain silica hydrogel aqueous solution>
The method for preparing the silica hydrogel is widely known, and among them, the pH during preparation is adjusted by adjusting the supply rate of the silicate aqueous solution and the acid, and the SiO ₂ concentration is the silicate aqueous solution having a predetermined concentration calculated in advance. It can be controlled by using and acid.
In the reaction, a silica hydrogel solution can be obtained by supplying an aqueous silicate solution and an acid at 10 to 100 ° C., preferably 20 to 95 ° C. with stirring in a reactor.

Any of sodium silicate No. 1, No. 2, No. 3, potassium silicate and other soluble silicate and diatomaceous earth can be used as the silicate.

The acid may be an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid or phosphoric acid, or an organic acid such as formic acid, but an inorganic acid is preferable.

The concentration of the silicate to be supplied is 30% by mass or less, preferably 10% by mass or less in terms of _{SiO 2.} The lower limit of the silicate concentration is not particularly set, but for example, if it is supplied in an amount of 5% by mass or more, it is preferable because a large volume compounding container and a large amount of water are not required to adjust the _{required amount of SiO 2.} .. On the other hand, the reason for setting the upper limit is that the agitator becomes overloaded due to the influence of a strong gel-like substance due to gelation caused by neutralization with an inorganic acid, and the stirrer cannot be stopped or sufficiently agitated.

According to the above-mentioned adjustment method, an aqueous silica hydrogel solution having ^{a specific surface area of 190 to 600 m 2 / g according to the BET method can be easily obtained.}

<C. Step to obtain silica-alumina mixture aqueous solution>
(The pseudo boehmite alumina hydrate aqueous solution and the silica hydrogel aqueous solution are mixed to obtain a silica-alumina particle mixture aqueous solution.)
A pseudo-bemite alumina hydrate aqueous solution having a solid content concentration adjusted to 1 to 5% by mass and a silica hydrogel aqueous solution having a solid content concentration adjusted to 5 to 10% by mass are mixed, and the pH is in the range of 7.0 to 10.0. , More preferably, the pH is adjusted to the range of 8.0 to 9.0, and the mixture is aged at a temperature of 40 to 60 ° C. for 10 minutes to 2 hours to obtain an aqueous solution of a silica-alumina mixture. When mixing these two liquids, a silica hydrogel aqueous solution may be added to the pseudo-bemite alumina hydrate aqueous solution, or a pseudo-bemite alumina hydrate aqueous solution may be added to the silica hydrogel aqueous solution.

<D. First cleaning process>
After the silica-alumina mixture aqueous solution obtained in the step c is filtered off, a silica-alumina mixture cake 1 is obtained. The mixture cake 1 is transferred to a washing container and washed with water at 50 to 70 ° C. to remove unreacted raw materials, contaminant ions and the like to obtain a silica-alumina mixture cake 1.

The temperature of the washing water is preferably in the range of 50 to 70 ° C., which is higher than room temperature, in order to improve the efficiency of removing unreacted raw materials and contaminant ions. The amount of water at 50 to 70 ° C. used here is preferably about 35 times the mass of the theoretically obtained silica-alumina particles for washing.

<E. Step to obtain silica-alumina gel slurry>
After the silica-alumina mixture cake 1 obtained in the step d was dispersed in water, the pH was adjusted to a range of 8.0 to 12.0, more preferably pH 8.5 to 11.5 at a temperature of 30 to 50 ° C. After that, the mixture is further heated to 80 ° C. or higher and stirred for 1 to 20 hours, more preferably 1 to 15 hours to accelerate the reaction from the silica-alumina mixture to the silica-alumina gel to obtain a silica-alumina gel slurry.
Here, since the purpose of heating at 80 ° C. or higher is to promote and complete the aging of the silica alumina gel, it may be carried out at normal pressure or under pressurized conditions such as an autoclave, and it is carried out under pressurized conditions. Therefore, there is an advantage that the processing time can be shortened.

<F. First drying process>
The silica-alumina gel slurry obtained in the step e is dried to obtain silica-alumina particles 1.

To dry to obtain silica-alumina particles 1, a spray dry or other commonly used drying device can be used. The drying temperature is not particularly limited, but if the temperature is too high, the phase transition from pseudoboehmite alumina to gamma-alumina is not preferable. Therefore, the inlet temperature is preferably 500 ° C. or lower and the outlet temperature is preferably 200 ° C. or lower, that is, the drying is preferably performed in the range of the inlet temperature of 300 to 500 ° C. and the outlet temperature of 130 to 200 ° C.

<G. Second cleaning process>
The silica-alumina particles 1 obtained in the step f are suspended again, stirred, filtered, and washed to obtain a silica-alumina particle cake 2.

In order to reduce the residual alkali metal ion concentration of the silica alumina particles 1 obtained in the step f, the suspension temperature is preferably in the range of 40 to 70 ° C., and the suspension is used. , It is preferable to perform filtration with an aqueous solution containing a water-soluble acidic substance. Examples of the water-soluble acidic substance used here include ammonium sulfate, ammonium nitrate, ammonium chloride and the like.

Further, in order to remove residual salts and the like after filtration, the silica-alumina particle cake 2 can be obtained by washing with warm water or the like containing a water-soluble basic substance and filtering. The temperature of the washing water is preferably in the range of 50 to 70 ° C., which is higher than room temperature, in order to improve the efficiency of removing unreacted raw materials and contaminant ions. As the water-soluble basic substance used here, for example, aqueous ammonia, hydroxide salt, carbonate, or hydrogen carbonate (the salt here means an alkali metal salt or an alkaline earth metal salt) is used. be able to.

<H. Second drying process>
The desired silica-alumina particles 2 can be obtained by drying the silica-alumina particle cake 2 after filtration obtained in the step g by the drying method described in the step f.

Further, depending on the residual amount of impurities such as contaminant ions, the steps f and / or g may be performed again after the step g, if necessary.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

<Measurement method or evaluation method>
The measurement method or evaluation method in the examples and the like is as follows.

(Each element, compound and metal components _{(Si, Al, Na, SO} 4 2-) method of measuring the content of)
3 g of the measurement sample was collected in a zirconia ball with a lid having a capacity of 30 ml, heat-treated (200 ° C., 20 minutes), calcined (700 ° C., 5 minutes), and then Na ₂ O ₂ : 2 g and NaOH: 1 g were added. Melted for 15 minutes. Further, _{25 ml of H 2} SO ₄ : and 200 ml of water were added and dissolved, and then diluted with pure water to 500 ml to prepare a sample. For the obtained sample, using an inductively coupled plasma (ICP) emission spectroscopic analyzer (ICPS-8100 manufactured by Shimadzu Corporation, analysis software ICPS-8000), the content of each component is measured on an oxide-equivalent mass basis. It was measured.

(Measuring method of pore volume PV and average pore diameter PD)
The pore volume PV and the average pore diameter PD were measured by BELSORP-mini Ver2.5.6 manufactured by Microtrac Bell Co., Ltd. Specifically, nitrogen gas is adsorbed on a sample that has been heat-treated at 500 ° C. for 2 hours while evacuating, and pores are formed by the desorption-side isotherm _{of the relative pressure (P / P 0 = 0.99) of the BJH method.} The volume PV (ml / g) and the average pore diameter PD (nm) were calculated.

(Measuring method of specific surface area SA)
For the measurement of specific surface area SA, about 30 mL of the measurement sample was collected in a porcelain crucible (B-2 type), heat-treated at a temperature of 500 ° C. for 2 hours, placed in a desiccator and cooled to room temperature, and the sample for measurement was taken. Got Next, 1 g of this sample was taken, and the specific surface area SA (m ² / g) of the sample was measured by the BET method using a fully automatic surface area measuring device (manufactured by Yuasa Ionics, Multisorb 12 type).

(Measuring method of average particle size)
The particle size distribution of the catalyst of Examples and the like was measured by a laser diffraction / scattering type particle size distribution measuring device (LA-300) manufactured by HORIBA, Ltd. Specifically, the sample was put into a solvent (water) so that the light transmittance was in the range of 70 to 95%, the circulation speed was 2.8 L / min, the ultrasonic irradiation was 3 minutes, and the number of repetitions was 30 times. It was measured under the conditions of. From the obtained particle size distribution, the median diameter (D50) was adopted as the average particle size.

(Measurement method of ignition loss, loss of ignition; hereinafter, also simply referred to as "ignition loss"))
The catalyst, which is the measurement sample, is calcined at 1000 ° C. for 1 hour, and is calculated from the amount of mass loss due to calcining.

(X-ray diffraction measurement conditions)
The X-ray diffraction of the silica-alumina particles was measured by MiniFlex manufactured by Rigaku Co., Ltd. The measurement conditions are as follows: the operating axis is 2θ / θ, the radiation source is CuKα, the voltage is 40 kV, the current is 15 mA, and the start angle: 2θ = 5 ° to the end angle: 2θ = 50 °. The sampling width was 0.020 ° and the scanning speed was 10.000 ° / min.
The criterion for determining amorphousness was that it did not show a diffraction peak with a full width at half maximum of less than 1.0 ° in the range of 5 ° ≤ 2θ ≤ 50 °.

[Example 1]
(Step a). Step to obtain pseudo-boehmite alumina hydrate aqueous solution 60 kg of water is filled in a 200 L stainless steel tank with a steam jacket, 25 mass% sodium gluconate aqueous solution: 24 g is added while stirring, and then Al ₂ O ₃ : 22.6 mass. %, Na ₂ O: 17.3 mass% sodium aluminate aqueous solution: 885 g was added, and then 24 mass% aluminum sulfate aqueous solution: 1408 g was added over 2 minutes to add a pseudo-bemite alumina seed slurry having a pH of 7.2. Was prepared. _Al 2 _O in the seed slurry 3: 22.6 _wt%, Na 2 O: 17.3% by mass aqueous sodium aluminate solution at a flow rate of 275 ml / min, a 23.6 mass% aluminum sulfate solution 488ml / min The mixture was added dropwise to the seed slurry at the same flow rate for 20 minutes while maintaining the temperature of 60 ° C. The pH of the finished slurry was 7.2. After stirring for 5 _minutes, Al ₂ O 3: 22.6 _wt%, Na 2 O: 2 hours stirring the pH at 17.3 wt% of aqueous sodium aluminate solution 642g at adjusted 60 ° C. to 8.8 Subsequently, a pseudo-boehmite alumina hydrate aqueous solution was prepared.

(Step b). Step to Obtain Silica Hydrogel Aqueous Solution 4.72 kg of sulfuric acid and 2.0 kg of pure water of 25% by mass were placed in a 40 L plastic tank and adjusted to 30 ° C. _{A sodium silicate solution having an 8.5 mass% SiO 2} concentration and a SiO ₂ / Na ₂ O molar ratio of 3.2 adjusted to 45 ° C. while stirring this sulfuric acid solution was added dropwise at a flow rate of 0.56 kg / min at 45 minutes. Then, the flow rate was reduced to 0.1 kg / min, and the sodium silicate solution was added dropwise to pH 4.0 for 30 minutes. After completion of the dropping, stirring was continued for 165 minutes to obtain an aqueous silica hydrogel solution. To this silica hydrogel, 400 ml of 15% concentrated aqueous ammonia was added to adjust the pH to 7.0, and the mixture was aged for 1 hour.

(Step c). Step to Obtain Silica-Alumina Mixture Aqueous Solution After stirring and mixing 78,191 g of the pseudo-bemite alumina hydrate aqueous solution and 893 g of the silica hydrogel aqueous solution, the pH is adjusted to 8.8 with 15% by mass of ammonia water, and the temperature is 40. Aqueous solution of silica-alumina mixture was obtained by aging at ~ 60 ° C. for 10 minutes.

(Step d). First Cleaning Step The silica-alumina mixture aqueous solution obtained in the step c is filtered off, and the filtered silica-alumina mixed cake 1a is washed with water at 60 ° C. and 105 L to remove sulfate ions and sodium ions. Was done. (Impurity content at this stage, Na ₂ O concentration in terms on a dry matter basis 0.1% by weight, _SO ^{4 2-concentration} was 2.1 wt%.)

(Step e). Step of Obtaining Silica Alumina Gel Slurry 7 kg of pure water at 60 ° C. was added to a weight of 23.0 kg of the silica-alumina mixture cake 1a obtained in the step d to adjust the silica-alumina concentration to 10% by mass, and then the mixture was stirred to form a slurry. The temperature of this slurry was 45 ° C. and the pH was 8.7. 1.8 L of 15 mass% aqueous ammonia was added to this slurry to adjust the pH to 10.8, and then the slurry was transferred to a 50 L closed tank equipped with a steam jacket and aged at 95 ° C. for 10 hours.

(Step f). First Drying Step After homogenizing the aging slurry obtained in the step e with an emulsifier, it is dried at an inlet temperature of 300 ° C. and an outlet temperature of 150 ° C. of a spray drying device to obtain silica alumina particles 1a having an average particle size of 70 μm. rice field.

(Step g). Second cleaning step With respect to the silica alumina particles 1a obtained in the step f, 300 g of the silica alumina particles 1a was suspended in 3000 g of ammonium sulfate at 60 ° C. at a concentration of 10% by mass based on a drying standard, stirred for 20 minutes, and then solid-liquid separated by a vacuum filter. Then, 3000 g of warm pure water at 60 ° C. was sprinkled on the remaining cake and resuspended. Subsequently, the pH was adjusted to 8.8 with 15% by mass of aqueous ammonia, the mixture was stirred for 20 minutes, and then solid-liquid separated with a vacuum filter to obtain a silica-alumina mixed cake 2a.

(Step h). Second Drying Step The silica-alumina particle cake 2a obtained in a stainless steel bat was taken out from the filter and dried at 130 ° C. overnight to obtain the desired silica-alumina particles I. Table 1 shows the chemical composition analysis and physical properties.

[Example 2]
(Steps a to c)
In the same manner as in Example 1, an aqueous solution of pseudo-boehmite alumina hydrate and an aqueous solution of silica hydrogel were obtained _{, 2400 g of slurry was weighed based on Al 2} O ₃ conversion standard, _{and 600 g was weighed based on SiO 2} conversion standard, and then stirred and mixed to obtain 15% by mass. The pH was adjusted to 8.8 with aqueous ammonia and aged for 10 minutes.
(Step d)
This mixed slurry was filtered and washed in the same manner as in Example 1. (The impurity content at this stage was Na ₂ O: 0.9% by mass and SO ₄ ^2- : 1.7% by mass based on the dry matter.)
(Steps e to h)
Subsequent treatment was carried out in the same manner as in Example 1 to obtain the desired silica-alumina particles II.

[Example 3]
(Steps a to c)
Pseudo-behimite alumina hydrate aqueous solution and silica hydrogel aqueous solution are obtained in the same manner as in Example 1, and 1800 _{g of slurry based on Al 2} O _{3 conversion standard and 1200 g of slurry based on SiO 2} conversion standard are weighed and mixed by stirring to 15% by mass. The pH was adjusted to 8.8 with aqueous ammonia and aged for 10 minutes.
(Step d)
This mixed slurry was filtered and washed in the same manner as in Example 1. (The impurity content at this stage was Na ₂ O: 1.8% by mass and SO ₄ ^2- : 1.1% by mass based on the dry matter.)
(Steps e to h)
Subsequent treatment was carried out in the same manner as in Example 1 to obtain the desired silica-alumina particles III.

[Example 4]
(Steps a to c)
Pseudo-behimite alumina hydrate aqueous solution and silica hydrogel aqueous solution are obtained in the same manner as in Example 1, and 1200 _{g of slurry based on Al 2} O _{3 conversion standard and 1800 g based on SiO 2} conversion standard are weighed and mixed by stirring to 15% by mass. The pH was adjusted to 8.8 with aqueous ammonia and aged for 10 minutes.
(Step d)
This mixed slurry was solid-liquid separated by a vacuum filter in the same manner as in Example 1, and washed with warm pure water. (The impurity content at this stage was Na ₂ O: 2.7% by mass and SO ₄ ^2- : 0.8% by mass based on the dry matter.)
(Steps e to h)
Subsequent treatment was carried out in the same manner as in Example 1 to obtain the desired silica-alumina particles IV.

[Example 5]
(Steps a to c)
Pseudo-behimite alumina hydrate aqueous solution and silica hydrogel aqueous solution are obtained in the same manner as in Example 1, and 1200 _{g of slurry based on Al 2} O _{3 conversion standard and 1800 g based on SiO 2} conversion standard are weighed and mixed by stirring to 15% by mass. The pH was adjusted to 8.8 with aqueous ammonia and aged for 10 minutes.
(Step d)
This mixed slurry was filtered and washed in the same manner as in Example 1. (The impurity content at this stage was Na ₂ O: 0.6% by mass and SO ₄ ^2- : 3.2% by mass based on the dry matter.)
(Steps e to h)
Subsequent treatment was carried out in the same manner as in Example 1 to obtain the desired silica-alumina particles V.

[Comparative Example 1]
* Method without using pseudo-boehmite alumina (steps a'to c')
4.72 kg of 25% by mass sulfuric acid and 2.0 kg of pure water were placed in a 40 L resin tank and adjusted to 30 ° C. _{While stirring this sulfuric acid solution, a sodium silicate solution having a SiO 2} concentration of 8.5 mass% adjusted to 45 ° C. and a SiO ₂ / Na ₂ O molar ratio of 3.2 was added at a flow rate of 0.56 kg / min for 45 minutes. Then, the flow rate was reduced to 0.1 kg / min, and the sodium silicate solution was added dropwise to pH 4.0 for 30 minutes. After completion of the dropping, stirring was continued for 165 minutes to obtain a silica hydrogel. To this silica hydrogel, 500 ml of aqueous ammonia having a concentration of 15% by mass was added, the pH was adjusted to 7.0, and the mixture was aged for 1 hour. The weight of the finished silica hydrogel is 35.54 kg. After transferring 1/2 of this to a tank with a 50 L steam jacket and adding 1 kg of pure water, the concentration of 23.6 mass% is maintained while keeping the slurry temperature in the tank at 45 ° C. 8.45 kg of aluminum sulfate solution was added with stirring for 5 minutes, and the pH after addition was 2.96. Next, 5.31 kg of a sodium aluminate solution having a concentration of 22.6 mass% Al ₂ O _{3 and a} concentration of 17.3 mass% Na ₂ O was added in 3 minutes to adjust the pH to 7.0, and then the mixture was stirred at 45 ° C. for 2 hours. Continued.
(Steps d to h)
After that, the silica-alumina mixture slurry was treated in the same manner as in Example 1 to obtain silica-alumina particles VI.

[Comparative Example 2]
(Steps a'to c')
35.54 kg of silica hydrogel was prepared in the same manner as in Comparative Example 1. Weigh 31.1 kg of this silica hydrogel sac, transfer it to a tank with a 50 L steam jacket, add 1 kg of pure water, and then maintain the slurry temperature in the tank at 45 ° C and maintain a 23.6% by mass concentration of aluminum sulfate solution. 4.22 kg was added with stirring for 5 minutes, and the pH after addition was 3.50. Next, _{2.66 kg of sodium aluminate solution of Al 2} O ₃ : 22.6 mass% and Na ₂ O: 17.3 mass% was added over 3 minutes to adjust the pH to 6.9, and then at 45 ° C. Stirring was continued for 2 hours.
(Steps d to h)
This silica-alumina mixture slurry was treated in the same manner as in Example 1 to obtain silica-alumina particles VII.

Sample No. adjusted above. The component compositions of I to VII, ignition loss LOI, pore volume PV, average pore diameter PD and specific surface area SA are summarized in Table 1. In addition, sample No. As a result of the X-ray diffraction measurement of I to VII, it has been confirmed that the particles are amorphous silica-alumina particles. Sample No. I to V have both a sufficient pore volume PV and a specific surface area SA, but the sample No. VI and VII have a small average pore diameter PD and an inferior pore volume PV.

Since the porous silica-alumina particles according to the present invention have a high pore volume and a high specific surface area, heat insulating properties can be expected. In addition to the above physical properties, since it is composed of silica-alumina and has a solid acid, it can be used as a catalyst for petroleum refining or an optical material, or as an additive to cosmetics, resin fillers, and surface coating materials (optical scattering, refraction). It can be applied to (for the purpose of rate adjustment, etc.).

Claims (3)

A method for producing porous silica-alumina particles.
a. The process of obtaining a pseudo-boehmite alumina hydrate aqueous solution and
b. The process of obtaining an aqueous silica hydrogel solution and
c. The slurry obtained by mixing the pseudo-boehmite alumina hydrate aqueous solution and the silica hydrogel aqueous solution is adjusted to a pH range of 7.0 to 9.0, and the reaction is promoted at a temperature of 40 to 60 ° C. for 10 minutes to 2 hours. And the step of obtaining an aqueous solution of silica-alumina mixture
d. The first washing step of washing after the silica-alumina mixture cake 1 is obtained by filtering out the silica-alumina mixture aqueous solution.
e. A step of dispersing the silica-alumina mixture cake 1 in water, adjusting the pH to 8.0 to 12.0 at a temperature of 30 to 50 ° C., and then further heating to 80 ° C. or higher to obtain a silica-alumina gel slurry.
f. The first drying step of drying the silica-alumina gel slurry to obtain silica-alumina particles 1 and
g. The second washing step of suspending the silica-alumina particles 1 obtained by drying again, stirring the mixture, filtering the particles, and washing the silica-alumina particles 1 to obtain the silica-alumina particle cake 2.
h. A method for producing porous silica-alumina particles, which comprises a second drying step of drying the silica-alumina particle cake 2 to obtain silica-alumina particles 2. Amorphous porous silica-alumina particles
The specific surface area SA measured by the BET method is in the range of ^{400 to 600 m 2 / g.}
The pore volume PV measured by the BJH method is in the range of 1.25 to 2.00 ml / g.
The average pore diameter PD measured by the BJH method is in the range of 8 to 20 nm.
Porous silica-alumina particles characterized by a mass ratio of silica and alumina in the range of 2/98 to 70/30. Further, an alkali metal ion ^{(M +)} containing 0.1 wt% in _{M 2} O in terms of,
The porous silica-alumina particles according to claim 2, wherein the residual amount of inorganic acid ions is 1.0% by mass or less.