Silica alumina and its manufacturing method

Abstract

Provided is silica-alumina with a high Bronsted acid amount and a manufacturing method for obtaining the silica-alumina. The silica-alumina has a Bronsted acid amount of more than 10 μmol / g and an isoelectric point in the range of 4.5 to 7.0. The method for producing silica-alumina includes an alumina slurry preparation step for preparing an alumina slurry, a silica slurry preparation step for preparing a silica slurry, a silica-alumina slurry preparation step for mixing the alumina slurry and the silica slurry to prepare a silica-alumina slurry, and a reaction step for reacting the silica-alumina slurry with an aluminum compound.

Description

[Technical field]

[0001] The present invention relates to silica-alumina and a method for producing the same. [Background technology]

[0002] Silica-alumina is a material that has been used for a long time in the field of catalyst technology. It has characteristic solid acid properties and a fine pore structure, and has been used as a catalyst support or active component by utilizing these properties.

[0003] It is known that the properties of silica alumina vary depending on the preparation method thereof. Preparation methods of silica alumina are well known in the art, and representative methods include the neutralization reaction method and the pH swing method.

[0004] As the neutralization reaction (coprecipitation method, cogelation method), there can be mentioned a preparation method in which a solution of silica hydrogel and a metal salt is mixed to produce amorphous silica-alumina containing the metal salt uniformly inside, as described in Patent Documents 1 to 4 and 7.

[0005] In addition, the pH swing method (immersion method) includes a preparation method that enables the production of amorphous silica-alumina in a single vessel by changing the pH of the reaction mixture, thereby precipitating silica and alumina, as described in Patent Documents 5 and 6. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 27-3989 [Patent Document 2] Special Publication No. 31-1862 [Patent Document 3] Special Publication No. 30-5963 [Patent Document 4] Special Publication No. 32-413 [Patent Document 5] Special Publication No. 2010-537808 [Patent Document 6] Special Publication No. 2016-502971 [Patent Document 7] JP 2021-151942 A [Non-patent literature]

[0007] [Non-Patent Document 1] Takayasu Shirasaki and Takayuki Todo, eds., "Catalyst Preparation," Kodansha, published November 10, 1974, p.22 [Non-Patent Document 2] CAEmeis, J. Catal., 141, 347-354 (1993) Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the conventional techniques, the preparation methods described in Patent Documents 1 to 7 have a problem in terms of controlling the solid acidity. In particular, there has been a demand for a preparation method for obtaining silica-alumina with a high Bronsted acidity.

[0009] In view of the above circumstances, an object of the present invention is to provide silica-alumina having a high Bronsted acid amount and a production method for obtaining the silica-alumina. [Means for solving the problem]

[0010] Under such technical background, the inventors have conducted intensive research to solve the above problems, and have found that a method for supporting alumina on the surface of silica-alumina can provide silica-alumina having a high Bronsted acidity, leading to the development of the present invention.

[0011] The present invention, which has been developed to solve the above problems and achieve the above objects, is as follows: First, the present invention provides silica-alumina having a Bronsted acid amount of more than 10 μmol / g and an isoelectric point in the range of 4.5 to 7.0. The silica alumina according to the present invention is (a) the amount of Lewis acid is 300 μmol / g or less; (b) the ratio of Bronsted acidity to Lewis acidity is greater than 0.035; (c) Brønsted acid density is 0.025 μmol / m 2 That is all, (d) in the pore distribution measured by a nitrogen adsorption method, the total pore volume is in the range of 1.00 mL / g or more and 2.20 mL / g or less; (e) in the pore distribution, the ratio of the volume of pores having a diameter of 10 nm or more to the total volume of pores is 60% or more; (f) Specific surface area is 250 m 2 / g or more, 600m 2 / g or less. (g) The silica content, calculated as SiO2, is in the range of 30% by mass or more and 70% by mass or less; This would be a more preferable solution.

[0012] Secondly, the present invention proposes a method for producing silica-alumina, comprising: an alumina slurry preparation step of preparing an alumina slurry; a silica slurry preparation step of preparing a silica slurry; a silica-alumina slurry preparation step of mixing the alumina slurry and the silica slurry to prepare a silica-alumina slurry; and a reaction step of reacting the silica-alumina slurry with an aluminum compound. [Brief description of the drawings]

[0013] [Figure 1] 1 is a graph showing an IR spectrum of silica alumina according to the present invention. [Diagram 2]1 is a graph showing the relationship between the difference in isoelectric point and the Bronsted acid amount of silica-alumina according to the present invention. [Diagram 3] 1 is a graph showing IR spectra (3500 cm −1 to 4000 cm −1 ) of silica alumina of Example 1 and Comparative Example 6. [Figure 4] 1 is a graph showing IR spectra (3750 cm −1 to 3800 cm −1 ) of silica alumina of Example 1 and Comparative Example 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Preferred embodiments of the present invention will now be described in detail. [Definition] In this embodiment, "silica" is a general term for silicon oxide, and silicon dioxide is included in silica. In the present embodiment, "alumina" is a general term for aluminum oxide, and aluminum oxide and alumina hydrate are included in alumina. In addition, pseudoboehmite, which is a type of alumina hydrate, is also included in alumina. In the present embodiment, the term "silica-alumina" is a general term for a mixture of silica and alumina, and crystalline aluminosilicates such as zeolites are not included in silica-alumina.

[0015] [Silica Alumina] The silica alumina having a large Bronsted acid amount (hereinafter also referred to as "acid amount B") according to the present embodiment will be described. Specifically, the silica alumina has a Bronsted acid amount of more than 10 μmol / g and an isoelectric point in the range of 4.5 to 7.0 (hereinafter also referred to as "the present silica alumina"). A detailed description will be given below.

[0016] The isoelectric point of the present silica-alumina is in the range of 4.5 to 7.0, since the present silica-alumina has alumina supported on its surface, it exhibits such an isoelectric point.

[0017] The silica content (SiO2 equivalent) of the present silica alumina is preferably in the range of 30 mass% or more and 70 mass% or less, more preferably in the range of 35 mass% or more and 65 mass% or less. The alumina content (Al2O3 equivalent) of the present silica alumina is preferably in the range of 30 mass% or more and 70 mass% or less, more preferably in the range of 35 mass% or more and 65 mass% or less. In general, it is known that the acid amount of silica alumina increases most when alumina occupies about 20 mass%. In contrast, the Bronsted acid amount of the present silica alumina increases even if the alumina content is in the above-mentioned range.

[0018] The specific surface area (hereinafter referred to as "SSA") of this silica alumina by the BET method is 250m 2 / g or more, 600m 2 / g or less. The specific surface area is preferably in the range of 300 m 2 / g or more, 550m 2 / g or less, and more preferably 350m 2 / g or more, 500m 2 It is particularly preferable that the specific surface area of ​​the silica-alumina is in the above-mentioned range, and the Brønsted acid density is high. A high Brønsted acid density is preferable because it increases the probability of contact with reactants in a catalytic reaction.

[0019] The pore volume (hereinafter also referred to as "PV") of this silica-alumina by the BJH method is preferably in the range of 1.00 mL / g or more and 2.20 mL / g or less. The pore volume is more preferably in the range of 1.20 mL / g or more and 2.00 mL / g or less, and particularly preferably in the range of 1.40 mL / g or more and 1.80 mL / g or less. When pores are used as reaction fields in catalytic reactions, the catalytic activity tends to increase as the pore volume increases. Furthermore, this silica-alumina has a ratio of the volume of pores with a pore diameter of 10 nm or more measured by the BJH method to the total pore volume (hereinafter referred to as "PV"). 10" is also called ". The pore volume ratio of the silica-alumina is preferably 60% by volume or more, and more preferably 65% ​​by volume or more. If the pore volume ratio is within this range, the diffusibility of the reactants in the catalytic reaction is improved, and the reactivity is likely to be high. In the present invention, the total volume of the pores having a pore diameter in the range of 2.4 nm or more and 192.4 nm or less is defined as the pore volume of the present silica-alumina, and the ratio of the volume of the pores having a pore diameter of 10 nm or more and 192.4 nm or less to this pore volume is defined as P 10 It was calculated as:

[0020] The Bronsted acid amount of the silica-alumina is more than 10 μmol / g, and is preferably 15 μmol / g or more. The upper limit of the Bronsted acid amount is not particularly limited, but may be 100 μmol / g or less, 75 μmol / g or less, or 50 μmol / g or less. Silica-alumina with a high Bronsted acid amount is suitable as a catalyst material used in reactions using Bronsted acids.

[0021] The amount of Lewis acid (hereinafter also referred to as "L acid amount") of the silica-alumina is preferably 300 μmol / g or less, more preferably 280 μmol / g or less. The lower limit of the amount of Lewis acid is not particularly limited, but may be 1 μmol / g or more, or may be 10 μmol / g or more. In a catalytic reaction using a Bronsted acid, the Lewis acid may promote a side reaction. Therefore, a silica-alumina having a small amount of Lewis acid is suitable as a catalyst material used in a reaction using a Bronsted acid. In addition, the molar ratio of the Bronsted acid to the Lewis acid (hereinafter also referred to as "B / L") is preferably more than 0.035, preferably 0.040 or more, and particularly preferably 0.050 or more. The upper limit of this molar ratio is not particularly limited, but may be 10 or less, 1 or less, or 0.5 or less.

[0022] The Bronsted acid density (hereinafter also referred to as "B acid density") of this silica alumina is 0.025 μmol / m 2 It is preferable that the concentration is 0.030 μmol / m or more.2 The upper limit of the Bronsted acid density is not particularly limited, but is preferably 1.000 μmol / m 2 or less, 0.500 μmol / m 2 or less, 0.100 μmol / m 2 Silica-alumina having a high Bronsted acid density is suitable as a catalyst material for use in reactions utilizing Bronsted acids.

[0023] The alumina contained in the silica-alumina is preferably pseudo-boehmite. Silica-alumina containing pseudo-boehmite tends to have a large pore volume and specific surface area. Whether the silica-alumina of the present invention contains pseudo-boehmite 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, if there are diffraction peaks at around 2θ=15°, 28°, 38°, and 49° corresponding to the Miller indices (020), (021), (130), and (150) of the boehmite structure, and the half-width of the Miller indices (130) and (150) is 1.0° or more, it can be determined that the silica-alumina contains pseudo-boehmite. In addition, if this half-width is less than 1.0, it can be determined that the silica-alumina contains crystalline boehmite. Furthermore, if the X-ray diffraction pattern does not show any other diffraction peaks with a half-width of less than 1.0° in the range of 5°≦2θ≦50°, it can be determined that the silica-alumina does not contain zeolite.

[0024] Since the present silica-alumina has a large Bronsted acidity, when it is used as a catalyst material for hydrocracking or catalytic cracking, the decomposition of the raw material is facilitated. The present silica-alumina acts as a catalyst by itself, but is preferably used as a material constituting a catalyst such as a carrier or a cocatalyst.

[0025] [Manufacturing method of Silica Lumina] In general, silica is known to contain Brønsted acids derived from silanols on the surface (e.g., Non-Patent Document 1). Also, alumina contains coordinatively unsaturated Al groups present on the surface of dehydrated alumina. 3+It is known that silica-alumina contains Lewis acid derived from. Therefore, it is possible to increase the Bronsted acid amount to some extent by increasing the content of silica contained in silica-alumina. In contrast, if the manufacturing method of this embodiment is used, silica-alumina with a high Bronsted acid amount can be obtained without increasing the content of silica. Hereinafter, the manufacturing method of silica-alumina according to this embodiment will be described in detail.

[0026] [Alumina slurry preparation process] The manufacturing method according to the present embodiment includes an alumina slurry preparation step. In this step, alumina slurry is prepared by dispersing a conventionally known alumina, such as hydrated alumina such as pseudoboehmite, boehmite, gibbsite, or bayerite, or aluminum oxide such as γ-alumina, χ-alumina, θ-alumina, or η-alumina, in a solvent. An alumina sol can also be used as the alumina slurry. The alumina in this step is preferably hydrated alumina, and more preferably pseudoboehmite. These aluminas prepared by a conventionally known preparation method may be used. Commercially available alumina may be purchased and dispersed in a solvent.

[0027] In the manufacturing method according to the present embodiment, by using pseudo-boehmite alumina having a large pore volume in the alumina slurry preparation step, silica-alumina having a large pore volume and a large Bronsted acid amount can be obtained. By using a manufacturing method including a preparation step of neutralizing an aluminum aqueous solution in which at least one of an aluminum salt and an aluminate is dissolved with a neutralizing agent to obtain a pseudo-boehmite precursor slurry, and an aging step of aging the pseudo-boehmite precursor slurry to obtain a pseudo-boehmite slurry, pseudo-boehmite with a large pore volume can be obtained.

[0028] The aluminum salt used in this preparation step may be any compound such as aluminum sulfate, aluminum chloride, aluminum nitrate, etc. The aluminate may be any compound such as sodium aluminate, potassium aluminate, etc.

[0029] In this mixing step, if the aluminum aqueous solution is acidic, a basic aqueous solution such as sodium hydroxide, potassium hydroxide, or ammonia water can be used as the neutralizing agent. If the aluminum aqueous solution is basic, an acidic aqueous solution such as sulfuric acid, hydrochloric acid, or nitric acid can be used as the neutralizing agent. In this case, a basic aqueous solution in which an aluminate is dissolved may be used as the basic aqueous solution, and an acidic aqueous solution in which an aluminum salt is dissolved may be used as the acidic aqueous solution. From the viewpoint of production cost, a method of preparing a pseudo-boehmite precursor slurry by mixing an acidic aqueous solution in which an aluminum salt is dissolved and a basic aqueous solution in which an aluminate is dissolved is preferred.

[0030] In this compounding step, the pH of the neutralized slurry obtained by mixing the aqueous solution with the neutralizing agent is adjusted to a range of 5.0 to 8.0, thereby obtaining a pseudo-boehmite precursor slurry. At this time, the temperature of the neutralized slurry is preferably adjusted to a range of 30°C to 70°C, more preferably to a range of 35°C to 65°C. By adjusting the temperature of the neutralized slurry to the above range, the pore volume of the pseudo-boehmite finally obtained becomes larger, and the purity of the pseudo-boehmite also becomes higher. Furthermore, after adjusting the temperature and pH of the neutralized slurry to the above range, this state is preferably maintained for a range of 5 minutes to less than 60 minutes, more preferably for a range of 5 minutes to 30 minutes. By shortening the holding time, the pore volume of the pseudo-boehmite finally obtained becomes larger.

[0031] In this compounding step, the pseudo-boehmite precursor slurry is further added with the aqueous solution containing the aluminum salt or the aqueous solution containing aluminum ions, and then aged to obtain pseudo-boehmite alumina having a high specific surface area and a large pore volume with a pore diameter of 10 nm or more. The concentration of aluminum contained in the aqueous solution is preferably in the range of 10 mass % or more and 25 mass % or less in terms of Al2O3. The aging is preferably performed at a temperature range of 40°C or more and 95°C or less, and more preferably at a temperature range of 50°C or more and 80°C or less. There is no particular limit to the aging time, but it is preferably 4 hours or less from the viewpoint of production efficiency.

[0032] In this alumina slurry preparation step, the alumina concentration of the alumina slurry is adjusted to a range of preferably 1 mass % or more and 20 mass % or less, and more preferably 1 mass % or more and 10 mass % or less, calculated as Al2O3. By adjusting the alumina concentration to such a range, the handleability of the alumina slurry is improved, and the production efficiency of silica-alumina is also increased.

[0033] [Silica slurry preparation process] The manufacturing method according to this embodiment includes a silica slurry preparation step. In this step, silica is dispersed in a solvent to prepare a silica slurry. For example, the silica slurry may be prepared by preparing a silica hydrogel using a conventionally known method and dispersing it in a solvent, or a commercially available silica powder may be dispersed in a solvent to prepare the silica slurry. At this time, the specific surface area of ​​the silica contained in the silica slurry is 200 m 2 / g or more, 700m 2 / g or less, and 2 / g or more, 600m 2 / g or less is more preferable. When silica having a specific surface area in the above range is used, the specific surface area of ​​the finally obtained silica alumina will be in an appropriate range. Also, silica sol can be used as the silica slurry.

[0034] In this step, the silica concentration of the silica slurry is preferably adjusted to a range of 10% by mass or more and 40% by mass or less, and more preferably adjusted to a range of 15% by mass or more and 35% by mass or less, calculated as SiO2. By adjusting the silica concentration to such a range, the handling property of the silica slurry is improved, and the production efficiency of silica alumina is also increased.

[0035] [Silica alumina slurry preparation process] The manufacturing method according to the present embodiment includes a silica-alumina slurry preparation step. In this step, the alumina slurry and the silica slurry obtained in the above step are mixed to prepare a silica-alumina slurry. At this time, the silica slurry may be added to the alumina slurry, the alumina slurry may be added to the silica slurry, or both may be added and mixed at the same time.

[0036] In this step, it is preferable to age the silica-alumina slurry. By aging the silica-alumina slurry, the Bronsted acid is easily expressed in the reaction step described below, and the Bronsted acid amount of the finally obtained silica-alumina is also easily increased. The temperature of the silica-alumina slurry during aging is preferably in the range of 30°C or more and 95°C or less, more preferably in the range of 35°C or more and 80°C or less. In addition, the retention time during aging is preferably in the range of 0.1 hours or more and 6 hours or less, more preferably in the range of 0.5 hours or more and 4 hours or less.

[0037] [Reaction process] The manufacturing method according to the present embodiment includes a reaction step. In this step, the silica-alumina slurry obtained in the above step is reacted with an aluminum compound. In this step, alumina is further supported on the surface of the silica-alumina, and this supported alumina reacts with the silica-alumina to generate a Bronsted acid, thereby obtaining silica-alumina with a high Bronsted acid content. In particular, the manufacturing method according to the present embodiment can obtain silica-alumina with a high Bronsted acid content even if the amount of alumina supported in this step is small.

[0038] In this step, it is preferable to support alumina on silica alumina so that the pH value is +0.3 or more relative to the isoelectric point of the silica alumina contained in the silica alumina slurry obtained in the above step. It is more preferable to support alumina so that the pH value is +0.5 or more relative to the isoelectric point. Inorganic oxide particles have an isoelectric point at which the zeta potential changes significantly when the pH value of the solution changes, and at a certain pH value, the surface potential becomes zero and no interfacial electrokinetic phenomenon such as electrophoresis is shown at all. For example, it is known that the isoelectric point of silica is about pH 2.5 and the isoelectric point of alumina is about pH 9.5. Therefore, the isoelectric point of silica alumina is in the range of pH value 2.5 or more and 9.5 or less, and the isoelectric point approaches pH value 9.5 by supporting alumina on the surface of silica alumina. In this way, by supporting alumina on the surface of silica alumina using the isoelectric point as an index, the Bronsted acid amount can be efficiently increased.

[0039] In this step, any compound such as aluminum sulfate, aluminum chloride, aluminum nitrate, etc. can be used as the aluminum compound. In addition, sodium aluminate, potassium aluminate, etc. can be used as the aluminate. These may be added directly to the silica-alumina slurry or may be added as an aqueous solution containing aluminum ions.

[0040] In this step, the silica-alumina slurry is preferably reacted with the aluminum compound after the temperature thereof is adjusted to a range of 30° C. or more and 70° C. or less, and more preferably reacted with the aluminum compound after the temperature thereof is adjusted to a range of 35° C. or more and 65° C. or less. By reacting the silica-alumina slurry with the aluminum compound under such conditions, silica-alumina having a large Bronsted acid amount is easily obtained.

[0041] By removing the solvent from the silica alumina slurry obtained in this step, silica alumina is obtained. For example, the solvent can be removed by a conventionally known method such as filtration or drying to obtain silica alumina. In the case of filtration, the silica alumina can be obtained by drying the silica alumina cake obtained by separating the solvent by a method such as reduced pressure filtration or filter press. Silica alumina can also be obtained by a method such as evaporation to dryness or spray drying. In the manufacturing method according to this embodiment, it is preferable to use spray drying. By using spray drying, powdered silica alumina with good flowability can be obtained. When spray drying is used, the inlet temperature of the spray dryer is preferably in the range of 150°C or more and 350°C or less. In addition, the outlet temperature of the spray dryer is preferably in the range of 80°C or more and 150°C or less.

[0042] The silica alumina obtained in this step may be washed as necessary. For example, the method of suspending the silica alumina in a solvent, washing, and filtering may be repeated. Here, the efficiency of washing can be improved by adjusting the temperature of the solvent to a range of 40°C or higher and 70°C or lower. Furthermore, the efficiency of washing can be further improved by dissolving ammonium sulfate, ammonium nitrate, ammonium chloride, etc. in the solvent. In addition, this washing may be performed after removing the solvent, or may be performed on the silica alumina slurry before removing the solvent.

[0043] The manufacturing method according to the present embodiment can provide silica-alumina having an optimum Bronsted acid amount for various catalytic reactions because the Bronsted acid amount can be finely adjusted. Therefore, the method shows excellent versatility as a method for manufacturing silica-alumina used as a catalyst material such as a carrier or a cocatalyst in catalytic reactions.

[0044] [Measurement method or evaluation method] The various measurements and evaluations were carried out as follows.

[0045] [1] Composition measurement method 3 g of the measurement sample was collected in a 30 mL zirconia bowl with a lid, heated (200 °C, 20 min), and sintered (700 °C, 5 min), after which 2 g of Na2O2 and 1 g of NaOH were added and melted for 15 min. Furthermore, 25 mL of H2SO4 and 200 mL of water were added to dissolve, and then the mixture was diluted with pure water to 500 mL to prepare a sample. The obtained sample was measured for the content of each component on an oxide-equivalent mass basis using an inductively coupled plasma (ICP) emission spectrometer (Shimadzu Corporation, ICPS-8100, analysis software ICPS-8000). The silica content was calculated in terms of SiO2, and the alumina content was calculated in terms of Al2O3.

[0046] [2] Method for measuring isoelectric point The isoelectric point was measured by pH titration using a Zetasizer Pro manufactured by Malvern Panalytical Co., Ltd. The measurement conditions were as follows: the solid concentration of the measurement sample was 0.1 mass%, the pH was adjusted using 0.1 mol / L HCl, 0.01 mol / L HCl, or 0.1 mol / L NaOH, and the measurement interval was set to pH value in 0.5 increments.

[0047] [3] Measurement method for specific surface area To measure the specific surface area, about 30 mL of the measurement sample was placed in a magnetic crucible (B-2 type), heated at 600°C for 2 hours, then cooled to room temperature in a desiccator to obtain a measurement sample. Next, 1 g of this sample was taken and the specific surface area of ​​the sample was measured by the BET single point method using a fully automatic surface area measuring device (Yuasa Ionics, Multisorb 12 type).

[0048] [4] Measurement method for pore volume and the proportion of pores 10 nm or larger The pore distribution of the measurement sample was measured using BELSORP-mini Ver2.5.6 manufactured by Microtrack-Bell Co., Ltd. Specifically, the measurement sample was heat-treated at 500°C for 2 hours while evacuating, and nitrogen gas was adsorbed onto the measurement sample, and the pore distribution was obtained from the desorption side isotherm of the relative pressure (P / P0 = 0.99) of the BJH method. From this pore distribution, the total volume of pores with pore diameters in the range of 2.4 nm to 192.4 nm was taken as the pore volume of the measurement sample, and the ratio of the pore volume with pore diameters of 10 nm to 192.4 nm was calculated.

[0049] [5] Solid acid property measurement After molding 50 mg of the sample powder into a disk of 20 mmΦ, it was placed in an IR cell connected to a vacuum line and subjected to evacuation treatment at 500 ° C for one hour. After evacuation treatment, the temperature was lowered to 150 ° C, and the IR (infrared absorption) spectrum of the sample disk was measured with FT / IR-4600 manufactured by JASCO Corporation. Next, pyridine was introduced, and after evacuating for 10 minutes at 150 ° C, the IR spectrum of the sample disk adsorbed with pyridine was measured in the same manner as described above. After that, the IR spectrum of the sample disk was subtracted from the IR spectrum of the sample disk adsorbed with pyridine to obtain the graph shown in Figure 1. As shown in Figure 1, the areas of the absorption peaks assigned to the Brönsted acid point (B) and Lewis acid point (L) were calculated. Based on the calculated absorption peak areas, the amount of Brönsted acid and the amount of Lewis acid were calculated by the method described in Non-Patent Document 2. In addition, the Brönsted acid density was calculated using the obtained amount of Brönsted acid and the specific surface area.

[0050] [6] X-ray diffraction measurements X-ray diffraction of silica alumina was measured using MiniFlex manufactured by Rigaku Corp. The measurement conditions were as follows: operation axis 2θ / θ, CuKα was used as the radiation source, the voltage was 40 kV, the current was 15 mA, the start angle was 2θ=5° and the end angle was 2θ=50°, the sampling width was 0.020°, and the scan speed was 10.000° / min. EXAMPLES

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0052] [Example 1] <Alumina slurry preparation process> A 200L stainless steel tank with a steam jacket was filled with 120 kg of hot water at 60°C, and 48 g of a 25% by mass sodium gluconate aqueous solution was added while stirring, and 1.77 kg of a 22% by mass sodium aluminate aqueous solution (manufactured by JGC Catalysts and Chemicals Co., Ltd.) was added with Al2O3 concentration conversion, and mixed for 5 minutes. Then, 2.95 kg of an aluminum sulfate aqueous solution (manufactured by JGC Catalysts and Chemicals Co., Ltd.) with an Al2O3 concentration conversion of 7% by mass was added, and stirred at 60°C for 5 minutes to prepare an alumina slurry precursor. 16.10 kg of the sodium aluminate aqueous solution and 29.80 kg of the aluminum sulfate aqueous solution were added simultaneously to the alumina slurry precursor over 40 minutes, and stirred for 5 minutes. Next, 3.85 kg of the sodium aluminate aqueous solution was added, and the mixture was aged at 60°C for 2 hours while stirring, and 0.53 kg of 15% ammonia water was added, and stirred for 5 minutes. Thereafter, the mixture was dehydrated using a flat filter, and the filtration residue was washed with warm water at 60° C. to obtain a washed cake. The washed cake was slurried to an alumina concentration of 7.2% by mass to obtain an alumina slurry.

[0053] <Silica slurry preparation process> Silica (average particle size = 12 μm, BET specific surface area = 480 m) was added so that the silica concentration was 33 mass%. 2 / g) was suspended in water to obtain a silica slurry.

[0054] <Silica alumina slurry preparation process> 0.16 kg of 15% ammonia water was added to 22.44 kg of the alumina slurry obtained in the above-mentioned process, and the mixture was stirred for 5 minutes. Then, 3.27 kg of the silica slurry obtained in the above-mentioned process was added, and the mixture was aged at 40° C. for 2 hours while stirring, to obtain a silica-alumina slurry with a solid content of 10.4% by mass. At this time, the isoelectric point of the silica-alumina contained in the silica-alumina slurry was 5.3.

[0055] <Reaction process> 10 kg of pure water was added to 10 kg of silica alumina slurry and heated to 40 ° C. Then, 0.29 kg of 25% by mass sulfuric acid was added to adjust the pH to 3, and after stirring for 5 minutes, 1.24 kg of aluminum sulfate aqueous solution with a concentration of 7% by mass in terms of Al2O3 was added. Then, 0.77 kg of 15% ammonia water was added and stirred for 10 minutes. Next, the solid content obtained by dehydrating with a flat filter was washed with hot water at 60 ° C. to obtain a washed cake. This washed cake was reslurried to a solid content concentration of 10.5% by mass, and then dispersed with a homogenizer, and dried with a spray dryer at an inlet temperature of 270 ° C. and an outlet temperature of 130 ° C. to obtain silica alumina 1. The manufacturing conditions are shown in Table 1 as Treatment No. 1. The obtained silica alumina 1 was subjected to the above-mentioned measurements and analyses. The results are shown in Table 2 as Silica Alumina No. 1. In addition, in the evaluation described above in [5], the IR spectrum of the sample disk to which pyridine had been adsorbed was subtracted, and the areas of the absorption peaks assigned to the Brønsted acid sites and Lewis acid sites were calculated. These are shown in Figure 1.

[0056] [Example 2] In the silica alumina slurry preparation step, the amount of 15% ammonia water added was changed from 0.16 kg to 0.27 kg, the aging temperature was changed from 40 ° C to 60 ° C, the amount of sulfuric acid added was changed from 0.29 kg to 0.24 kg, the amount of aluminum sulfate aqueous solution added was changed from 1.24 kg to 0.6 kg, and the amount of ammonia water added was changed from 0.77 kg to 0.42 kg. Except for these, silica alumina 2 was obtained in the same manner as in Example 1. The production conditions are shown in Table 1 as Process No. 2. The obtained silica alumina 2 was subjected to the above-mentioned measurements and analyses. The results are shown in Table 2 as Silica Alumina No. 2.

[0057] [Example 3] Silica alumina 3 was obtained in the same manner as in Example 2, except that in the reaction step, the amount of aluminum sulfate aqueous solution added was changed from 0.6 kg to 1.24 kg, and the amount of ammonia water added was changed from 0.42 kg to 0.73 kg. The production conditions are shown in Table 1 as Treatment No. 3. The obtained silica alumina 3 was subjected to the above-mentioned measurements and analyses. The results are shown in Table 2 as Silica alumina No. 3.

[0058] [Example 4] Silica alumina 4 was obtained in the same manner as in Example 1, except that in the reaction step, the amount of aluminum sulfate aqueous solution added was changed from 1.24 kg to 0.6 kg, and the amount of ammonia water added was changed from 0.77 kg to 0.73 kg. The production conditions are shown in Table 1 as Treatment No. 4. The obtained silica alumina 4 was subjected to the above-mentioned measurements and analyses. The results are shown in Table 2 as Silica alumina No. 4.

[0059] [Comparative Example 1: No reaction step of Example 2] The silica alumina slurry of Example 2 was dispersed using a homogenizer, and dried using a spray dryer at an inlet temperature of 270°C and an outlet temperature of 130°C to obtain silica alumina 5. The production conditions are shown in Table 1 as Process No. 5. The obtained silica alumina 5 was subjected to the above-mentioned measurements and analyses. The results are shown in Table 2 as Silica Alumina No. 5.

[0060] [Comparative Example 2: No reaction step of Example 1] The silica-alumina slurry of Example 1 was dispersed using a homogenizer, and dried using a spray dryer at an inlet temperature of 270°C and an outlet temperature of 130°C to obtain silica-alumina 6. The production conditions are shown in Table 1 as Process No. 6. The obtained silica-alumina 6 was subjected to the above-mentioned measurements and analyses. The results are shown in Table 2 as Silica-alumina No. 6.

[0061] [Table 1]

[0062] [Table 2]

[0063] Silica alumina 1 and 4 in process Nos. 1 and 4, in which alumina was supported on silica alumina 6 in process No. 6, had a higher isoelectric point than silica alumina 6, resulting in an increased Bronsted acid amount (● in Figure 2). In addition, silica alumina 2 and 3 in process Nos. 2 and 3, in which alumina was supported on silica alumina 5 in process No. 5, also had a higher isoelectric point than silica alumina 5, resulting in an increased Bronsted acid amount (▲ in Figure 2). These results demonstrated the effectiveness of the manufacturing method of supporting alumina on silica alumina. In addition, it was discovered that by controlling the isoelectric point of silica alumina within a specific range, the Bronsted acid amount can be increased without significantly changing the composition.

[0064] FT-IR (Fourier transform infrared absorption) measurements were carried out under the following conditions for silica-alumina 1 carrying alumina and silica-alumina 6 not carrying alumina. The results are shown in Figures 3 and 4.

[0065] <Condition> 25 mg of the sample powder was molded into a 20 mm diameter disk, which was then placed in an IR cell connected to a vacuum line and evacuated at 500°C for one hour. After evacuating, the disk was allowed to cool to room temperature, and the IR (infrared absorption) spectrum of the sample disk was measured using a JASCO FT / IR-6100. In order to remove water vapor and carbon dioxide from the measurement optical path and perform highly accurate measurements, high-purity nitrogen gas was supplied to the FT-IR interference chamber, sample chamber, and detector chamber. The obtained spectrum was subjected to baseline correction and weight correction based on 20 mg, and the spectra shown in Figures 3 and 4 were obtained.

[0066] The absorption band (3740 cm-1) derived from Si-OH is smaller in silica-alumina 1, which supports alumina, compared to silica-alumina 6, which does not support alumina. Also, the absorption band (3780 cm-1) derived from Al-OH is larger in silica-alumina 1. This proves that alumina is supported on the surface of silica-alumina. And, this alumina supported on the surface creates a Bronsted acid that is not present in conventional silica-alumina.

[0067] In this specification, the unit of volume "L" is 10 -3 m 3 Represents.

Claims

1. The Bronsted acid amount is more than 10 μmol / g; The isoelectric point is in the range of 4.5 to 7.

0. Silica alumina.

2. The silica-alumina according to claim 1, having a Lewis acid amount of 300 μmol / g or less.

3. 3. The silica-alumina according to claim 2, wherein the ratio of Bronsted acidity to Lewis acidity is greater than 0.

035.

4. Bronsted acid density is 0.025 μmol / m ２ The silica-alumina according to claim 3, wherein

5. 5. The silica-alumina according to claim 4, wherein the total pore volume is in the range of 1.00 mL / g or more and 2.20 mL / g or less in the pore distribution measured by a nitrogen adsorption method.

6. 6. The silica-alumina according to claim 5, wherein in the pore distribution, the ratio of pore volume of pores having a size of 10 nm or more to the total pore volume is 60% or more.

7. The specific surface area is 250 m ２ / g or more, 600m ２ The silica-alumina according to claim 6, wherein the silica-alumina content is in the range of 0.1 to 1.0 μm / g or less.

8. The silica alumina according to any one of claims 1 to 7, having a silica content in the range of 30 mass% or more and 70 mass% or less, calculated as SiO2.

9. an alumina slurry preparation step of preparing an alumina slurry; A silica slurry preparation step of preparing a silica slurry; a silica-alumina slurry preparation step of mixing the alumina slurry and the silica slurry to prepare a silica-alumina slurry; A reaction step of reacting the silica-alumina slurry with an aluminum compound. A method for producing silica alumina.

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