JP7740889B2 - Silica-alumina powder, method for producing silica-alumina powder, fluid catalytic cracking catalyst and method for producing the same - Google Patents

Description

The present invention relates to a silica-alumina powder that is used in fluid catalytic cracking catalysts and has excellent thermal stability, moderate acid density, and strong Lewis acid strength, and a method for producing the same. More specifically, the present invention relates to a fluid catalytic cracking catalyst containing silica-alumina that has a low coke yield and an excellent gasoline yield, and a method for producing the same.

The fluid catalytic cracking catalyst used in the fluid catalytic cracking (FCC) process of feedstock (hydrocarbon oil), such as atmospheric distillation residue, contains zeolite, a solid acid. Furthermore, to provide wear resistance when used in a fluidized state, a matrix component, such as silica alumina, which has the cracking activity for hydrocarbon oils, is added to the fluid catalytic cracking catalyst.

Silica-alumina generally refers to a mixture or composite oxide of silica and alumina. A mixture of silica and alumina means that silica and alumina are mixed physically without a chemical bond. In this case, the mixture of silica and alumina has a Lewis acid derived from the alumina. On the other hand, a composite oxide of silica and alumina means that silica and alumina are mixed via a chemical bond. In this case, the composite oxide of silica and alumina has a Bronsted acid derived from its crystal structure.

Silica-alumina has the characteristic that its acidic properties change depending on whether or not the silica and alumina are chemically bonded. Taking advantage of this characteristic, silica-alumina has long been used in various catalytic reactions. It is also manufactured using a variety of methods.

For example, Patent Document 1 discloses silica-alumina having a structure in which a silica layer is formed on the surface of alumina cores, a method for producing the same, and a hydrotreating catalyst.

Patent Document 2 also discloses a catalyst composition for fluid catalytic cracking of heavy oil, which contains, as a catalytic component, silica-alumina, which has a structure in which an alumina core has silica attached and bonded to its surface.

Patent Document 3 also discloses a silica-alumina composite oxide having a structure in which a silica layer is formed on the surface of an alumina particle serving as a nucleus, and a method for producing the same.

Patent Document 4 also discloses amorphous silica alumina with specified silica content, specific surface area, and acid content, and a method for producing the same.

Patent Document 5 also discloses a method for producing quasi-crystalline boehmite containing the additives in a uniformly dispersed state by combining an inexpensive quasi-crystalline boehmite precursor with an additive and aging the mixture.

Patent Document 6 also discloses porous composite particles comprising an aluminum oxide component, such as crystalline boehmite having an average crystallite size of about 20 to about 200 angstroms, and a residue of a crystal size growth inhibitor additive component, such as a silicate or phosphate, densely dispersed within the aluminum oxide component.

In addition, Non-Patent Documents 1 and 2 confirm the Lewis acid properties of silica alumina using CO adsorption FT-IR.

Japanese Patent Application Publication No. 06-127931 Japanese Patent Application Publication No. 08-071417 Japanese Patent Application Publication No. 09-255321 Japanese Patent Application Publication No. 11-157828 Special Publication No. 2003-507298 Special Publication No. 2003-517993 U.S. Pat. No. 5,569,325

Nature, Structure and Strength of the Acidic Sites of Amorphous Silica Alumina: An IR and NMR Study, J. Phys. Chem. B 2006, 110, pp15172-15185. IR Characterization of Homogeneously Mixed Silica-Alumina Samples and Dealuminated Y Zeolites by Using Pyridine, CO, and Propene Probe Molecules, J. Phys. Chem. C 2013, 117, pp14043-14050. C. A. Emeis, J. Catal., 141, 1993, 347-354.

Because silica-alumina has solid acidity, it is used in a variety of catalytic reactions, including as a fluid catalytic cracking catalyst and a hydrocracking catalyst. Fluid catalytic cracking, in particular, requires a catalyst with low coke production, and silica-alumina must have thermal stability and appropriate acid density and acid strength. However, the technologies disclosed in the above-mentioned Patent Documents 1 to 6 do not specify the crystallite size of boehmite as the alumina raw material before adding the silica source when producing silica-alumina, and are therefore unable to control the thermal stability or Lewis acid properties of silica-alumina.

Non-Patent Documents 1 and 2 confirm the Lewis acid properties of silica-alumina. However, only for silica-alumina containing 30% by mass or more of _SiO2 , a peak near 2230 cm ^-1 , indicating the presence of Lewis acids with strong acid strength, has been confirmed. As the silica ratio of silica-alumina increases, the specific surface area increases and the acid content decreases. Therefore, silica-alumina containing 20% by mass or more of _SiO2 cannot achieve sufficient acid density when used in a fluid catalytic cracking catalyst.

The present invention aims to provide a silica-alumina powder that is used in fluid catalytic cracking catalysts and has excellent thermal stability, moderate acid density, and strong Lewis acid strength, a method for producing the same, and a fluid catalytic cracking catalyst that contains the silica-alumina powder and has a low coke yield and an excellent gasoline yield.

The silica-alumina powder provided by the present invention has the following characteristics a to f:
a. Contains _SiO2 in the range of 8 to 20 mass%;
b. The crystallite size of the boehmite alumina (020) plane determined by X-ray diffraction is 10 to 50 nm;
c. The specific surface area of the silica-alumina powder is in the range of 90 to 230 m ² /g;
d. The acid density, which is the amount of acid per surface area, is in the range of 0.75 to 1.00 μmol/ ^m2 ;
e. In TG-DTA measurement (weight change-differential thermal analysis), the crystal transition temperature from boehmite alumina to gamma alumina is 470°C or higher;
f) In CO adsorption FT-IR measurement (measurement using a Fourier transform infrared spectrophotometer), a Lewis acid is present which exhibits a peak near 2230 cm ⁻¹ .

The method for producing a silica-alumina powder proposed by the present invention is a method for producing the silica-alumina powder, comprising:
(A) mixing an aqueous solution containing an alumina hydrate with an aqueous solution containing a silica precursor to prepare an aqueous solution A containing a silica-alumina precursor;
(B) adjusting the pH of the aqueous solution A containing the silica-alumina precursor obtained in the step (A) to 8.0 or more, and then heat-treating it at a temperature in the range of 70 to 180°C for 2 hours or more to obtain a silica-alumina slurry A;
(C) separating a solid content from the silica-alumina slurry A to obtain a silica-alumina powder,
The alumina raw material used in step (A) is a boehmite alumina having a crystallite diameter of 10 to 50 nm on the (020) plane as determined by X-ray diffraction,
The mass ratio of silica to alumina is adjusted to fall within the range of 8/92 to 20/80.

The fluid catalytic cracking catalyst according to the present invention is a fluid catalytic cracking catalyst containing the above-mentioned silica-alumina powder.

Further, the method for producing a fluid catalytic cracking catalyst according to the present invention comprises the steps of:
(1) A step of mixing the silica-alumina powder component, the binder component, the clay component (extender), the zeolite component, and the additives to obtain a mixed slurry;
(2) spray-drying the mixed slurry obtained in the step (1) to obtain dried particles;
(3) A step of washing and drying the dried particles obtained in the step (2) to obtain a fluid catalytic cracking catalyst.
Furthermore, instead of step (3),
(4) The process preferably includes a step of washing the dried particles obtained in the step (2) and then further exchanging the particles with a rare earth metal to obtain a rare earth metal-exchanged fluid catalytic cracking catalyst.

The present invention makes it possible to obtain a silica-alumina powder that has excellent thermal stability, moderate acid density, and strong Lewis acid strength when used in a fluid catalytic cracking catalyst. Therefore, a fluid catalytic cracking catalyst containing this silica-alumina powder can be used in the fluid catalytic cracking of hydrocarbon oils to achieve a low coke yield and an excellent gasoline yield.

1 is a graph showing the results of CO adsorption FT-IR measurement of silica-alumina powder according to an example of the present invention. 1 is a graph showing the results of CO adsorption FT-IR measurement of silica-alumina powder according to a comparative example.

The inventors have discovered that by using highly crystalline boehmite as the alumina hydrate, it is possible to obtain silica-alumina suitable for use in fluid catalytic cracking catalysts. The principle behind this is believed to be as follows: highly crystalline boehmite has a more regular arrangement, and the crystal planes that react with silica can be appropriately controlled, making it possible to develop specific strong acid sites in the silica-alumina. Furthermore, by using highly crystalline boehmite, the amount of acid per surface area of the silica-alumina increases and its thermal stability is improved, so when used as a fluid catalytic cracking catalyst, high activity can be expected over the long term.

<Silica alumina powder>
The silica-alumina powder of the present invention has the following properties:
a. Contains _SiO2 in the range of 8 to 20 mass%;
b. The crystallite size of the boehmite alumina (020) plane determined by X-ray diffraction is 10 to 50 nm;
c. The specific surface area of the silica-alumina powder is in the range of 90 to 230 m ² /g;
d. The acid density, which is the amount of acid per surface area, is in the range of 0.75 to 1.00 μmol/ ^m2 ;
e. In TG-DTA measurement (weight change-differential thermal analysis), the crystal transition temperature from boehmite alumina to gamma alumina is 470°C or higher;
f) In CO adsorption FT-IR measurement (measurement using a Fourier transform infrared spectrophotometer), a Lewis acid is present which exhibits a peak near 2230 cm ⁻¹ .

The silica-alumina powder according to the present invention is a non-zeolite substance. The silica component contained in the powder is in the range of 8 to 20 mass %, preferably 8 to 17 mass %, and more preferably 9 to 15 mass %. If the silica-alumina content is below the lower limit, the crystal transition temperature will be low, and further, in CO adsorption FT-IR measurement (measurement using a Fourier transform infrared spectrophotometer), a strong Lewis acid showing a peak near 2230 cm ⁻¹ will no longer be present, resulting in insufficient performance. On the other hand, if the silica-alumina content exceeds the upper limit, sufficient acid density cannot be obtained when used in a fluid catalytic cracking catalyst.

<Chemical composition (Al, Si, Na, S)>
Of the components of the fluid catalytic cracking catalyst of the present invention, the chemical compositions of Al, Si, and Na were measured by ICP (inductively coupled plasma) emission spectroscopy, and sulfur (S) was measured by a combustion method.

<Pyridine adsorption FT-IR measurement>
30 mg of silica-alumina powder was molded into a 20 mm diameter disk, which was then placed in an IR cell connected to a vacuum line and subjected to evacuation treatment at 500°C for 1 hour. After pretreatment, the temperature was lowered to 150°C, and the IR spectra of the sample disk before and after the introduction of pyridine vapor were measured using a JASCO FT/IR-4600. Quantitative determination of Bronsted acid sites and Lewis acid sites was performed based on the method described in Non-Patent Document 3.

<X-ray diffraction measurement conditions>
X-ray diffraction of the silica-alumina powder was measured using a MiniFlex manufactured by Rigaku Corporation. The measurement conditions were as follows: the operating axis was 2θ/θ, a CuKα source was used, and the measurement was performed continuously at a voltage of 40 kV and a current of 15 mA, from a starting angle of 2θ = 5° to an ending angle of 2θ = 90°, with a sampling width of 0.020° and a scan rate of 10,000°/min.
The crystallite diameter D of the boehmite-type alumina was calculated for the boehmite alumina (020) plane (2θ=14.0 to 15.0°) using the following Scherrer equation.
Crystallite diameter = (K × λ) / (β × cos θ)
K (shape factor): 0.9400
λ (X-ray wavelength): 0.15418nm
β (correction for line width broadening inherent to the device): Full width at half maximum θ: Bragg angle (°)

The silica-alumina powder according to the present invention preferably has a crystallite size of the boehmite alumina (020) plane of 10 to 50 nm, preferably 10 to 45 nm. If the crystallite size is below the lower limit, the silica-alumina used in a fluid catalytic cracking catalyst will not exhibit high thermal stability, sufficient acid density, or a strong Lewis acid strength that shows a peak near 2230 cm ^-1 in CO adsorption FT-IR measurement (measured using a Fourier transform infrared spectrophotometer). If the crystallite size exceeds the upper limit, the surface area and acid amount will be significantly reduced, resulting in a decrease in catalytic activity.

<BET specific surface area measurement>
The silica-alumina sample powder was pretreated at 500 °C for 1 hour in an inert gas atmosphere, and the adsorption and desorption amounts of _N2 were measured using a MacSorb-1220 manufactured by Mountech Co., Ltd. The specific surface area was calculated from the obtained desorption amount of _N2 based on the BET single-point method.
The specific surface area of the silica-alumina according to the present invention is set to 90 to 230 ^{m 2} /g, preferably 100 to 210 m ² /g.

<Acid density>
The acid density (μmol/m ² ), which is the amount of acid per surface area, was calculated from the sum (μmol/g) of the Bronsted acid amount and Lewis acid amount measured by the pyridine adsorption FT-IR and the BET specific surface area (m ² /g).
The acid density of the silica-alumina according to the present invention is 0.75 to 1.00 μmol/m ² , preferably 0.80 to 1.00 μmol/m ² , and more preferably 0.80 to 0.90 mol/m ^2. By ensuring an acid density within this range, sufficient catalytic activity can be obtained when used as a fluid catalytic cracking catalyst.

<TG-DTA (weight change-differential thermal analysis) measurement>
Using a TG-DTA (weight change-differential thermal analysis) apparatus (Thermo Plus TG8120) manufactured by Rigaku Corporation, the powder sample was heated at a rate of 10°C/min up to 1000°C while introducing air at a rate of 50 ml/min, and the thermal behavior of the powder sample was recorded. Alpha alumina was used as the standard material.
The crystal transformation temperature from boehmite alumina to gamma alumina in the silica alumina according to the present invention is set to 470° C. or higher. In this temperature range, it can be said that the silica alumina has high thermal stability.

<CO adsorption FT-IR measurement>
30 mg of silica-alumina powder was molded into a 20 mm diameter disk and placed in an IR cell connected to a vacuum line. The disk was then subjected to evacuation treatment at 500°C for 1 hour. After pretreatment, the temperature was lowered to -176°C, and an inert gas (He) was introduced at 100 Pa to bring the sample temperature closer to -176°C. The sample was then evacuated, and CO was gradually introduced at 1 Pa, 5 Pa, 5 Pa (second time), and 10 Pa to observe the changes in the IR spectrum resulting from the CO stretching vibration. Figures 1 and 2 show the difference spectra before and after the introduction of CO. The stronger the Lewis acid strength, the more the CO stretching vibration shifts to a higher wavenumber, and the appearance of a peak near 2230 cm ^-1 indicates the presence of a Lewis acid with strong acid strength.
The silica-alumina according to the present invention is characterized by the presence of a Lewis acid which exhibits a peak at around 2230 cm ⁻¹ in CO adsorption FT-IR measurement.

<Method of manufacturing silica-alumina powder>
The method for producing silica-alumina powder is as follows:
(A) mixing an aqueous solution containing an alumina hydrate with an aqueous solution containing a silica precursor to prepare an aqueous solution A containing a silica-alumina precursor;
(B) adjusting the pH of the aqueous solution A containing the silica-alumina precursor obtained in the step (A) to 8.0 or more, and then heat-treating it at a temperature in the range of 70 to 180°C for 2 hours or more to obtain a silica-alumina slurry A;
(C) a step of separating a solid content from the silica-alumina slurry A to obtain a silica-alumina powder;
and optionally washing and drying (calcining) the resulting product to obtain a silica-alumina powder.
The alumina raw material used in step (A) is a boehmite alumina having a crystallite diameter of 10 to 50 nm on the (020) plane as determined by X-ray diffraction,
The mass ratio of silica to alumina is adjusted to fall within the range of 8/92 to 20/80.

<Alumina raw material>
The alumina raw material preferably has a crystallite size of the (020) plane of boehmite alumina measured by X-ray diffraction in the range of 10 to 50 nm, preferably 10 to 45 nm. Below the lower limit, the crystallinity of the boehmite alumina is low, making it impossible to appropriately control the thermal stability and acid properties when used as a raw material for silica-alumina powder. Above the upper limit, the surface area of the boehmite alumina is low, and when used as a raw material for silica-alumina powder, the surface area and acidity decrease, resulting in a decrease in catalytic activity. Commercially available aluminas may be selected, or they may be prepared using an aqueous solution of an alkali metal aluminate or an aluminum salt.

For example, an aluminum sulfate aqueous solution is added to a sodium aluminate aqueous solution and stirred. The resulting alumina slurry is washed with warm water to adjust the _Na2O content of the washed alumina cake to 2% or less by dry weight and the _SO4 content to 1% or less by dry weight. The washed alumina cake is then dispersed in pure water to obtain a washed alumina slurry. An aqueous sodium hydroxide solution is then added to adjust the pH, and the mixture is aged while being stirred. After aging, the mixture is cooled to obtain a crystalline boehmite slurry.

<Silica precursor-containing aqueous solution>
In an embodiment of step (A) of the method for producing silica-alumina powder according to the present invention, an aqueous solution containing alumina hydrate is mixed with an aqueous solution containing a silica precursor. The source of the silica compound is preferably selected from the group consisting of silicic acid, silicic acid colloidal solution, water-soluble silicates, cationic silicon salts (such as hydrated sodium metasilicate), LUDOX (registered trademark, ammonia type or alkali type), and quaternary ammonium silicate. The silicic acid colloidal solution may be prepared using a method known to those skilled _in the art. A demineralized silicic acid solution is preferred as the silica compound. The source of this completely soluble silicon compound may be an orthosilicic acid solution ( _H2SiO4 , _H2O ) prepared by ion-exchanging a water-soluble alkali silicate on a resin.

<Process (A)>
A step of mixing an aqueous solution containing an alumina hydrate with an aqueous solution containing a silica precursor to prepare an aqueous solution A containing a silica-alumina precursor. The combination of an alumina compound with a completely soluble silica compound, or a partially soluble silica compound and an alumina compound, corresponds to contacting alumina species and silica species having specific sizes and chemical reactivities in the mixture of step (A) and controlling the interaction between the chemical species. Controlling the interaction in this way contributes to improving the homogeneity of the silica-alumina powder of the present invention. In this preparation method, the interaction activity between the silica species and alumina species may be controlled in any step before the heat treatment depending on the chemical properties of the alumina compound and silica compound used to prepare the silica-alumina powder. In one non-limiting example, the partially soluble alumina compound of hydrated aluminum type, Al ₂ O ₃ ·nH ₂ O (boehmite), may be mixed with a fully soluble silica compound of decationized orthosilicate type in an aqueous medium under various controlled synthesis conditions (pH, temperature, etc.), or the partially soluble alumina compound of hydrated alumina type, Al ₂ O ₃ ·nH ₂ O (boehmite), may be mixed with a commercially available fully soluble silica (Ludox®) colloidal solution during the forming process after machining. Following the mixing in step (A) of the silica-alumina powder preparation method, heat treatment is carried out in the presence of water (gas or liquid phase) to finally achieve the micrometer-level (or nanometer-level) homogeneity between the alumina and silica species required to obtain the acidity and texture characteristics of the silica-alumina powder used in fluid catalytic cracking of the present invention.

When preparing the aqueous solution in step (A), it is preferable to keep the temperature in the range of 10 to 60°C. Preparation at a temperature significantly outside this range is not preferable because a homogeneous reaction between the silica and alumina will not occur, and the silica-alumina will not exhibit high thermal stability, adequate acid density, or strong Lewis acid strength.

This applies to hydrated alumina powder, spray-dried hydrated alumina powder, dispersions and suspensions of hydrated alumina, and combinations thereof, prior to the addition of a compound containing partial or total silicon.

To increase the mesopore diameter of the final silica-alumina powder, as disclosed in U.S. Pat. No. 4,066,574, it is particularly effective to prepare an aqueous suspension or dispersion of an alumina component such as alumina monohydrate (an alumina compound partially soluble in an acidic medium) to obtain the mixture of step (1), subsequently neutralize the mixture with a basic solution (such as ammonia), and finally add the mixture simultaneously or sequentially to a completely soluble silica compound (such as a decationized orthosilicic acid solution). This suspension is mechanically homogenized by vigorously stirring, and optionally, the dry matter content is adjusted by filtration and rehomogenized. The product is then heat-treated and, simultaneously or sequentially, optionally shaped.

In the following description of the above method, the first "homogenization" of the mixture is often performed by mechanical processing. For example, when a product containing a solid fraction is used in the form of a liquid such as a suspension, a powder, or a filtered precipitate, the product is dispersed by vigorous stirring. Mechanical homogenization of dispersions is widely known to those skilled in the art. Homogenization may be performed by mechanical methods known to those skilled in the art, for example, using a batch reactor, continuous mixer, or mill. Mixing may be performed in a plug-flow reactor, particularly a static reactor. A Lightnin' reactor may also be used. A colloid mill such as an Ultraturrax® turbine or a Staro® turbine, or a Staro® colloid mill may also be used. A commercially available IKA® colloid mill may also be used.

<Process (B)>
- A step of adjusting the pH of the aqueous solution A containing the silica-alumina precursor obtained in the step (A) to 8.0 or higher, and then heat-treating it in a temperature range of 70 to 180°C for 2 hours or more to obtain silica-alumina slurry A. In step (B) of the method for preparing a silica-alumina powder of the present invention, the pH of the aqueous solution A obtained in the step (A) is adjusted to 8.0 or higher, and then heat-treating it in a temperature range of 70 to 180°C for 2 hours or more, thereby ensuring the homogeneity of the silica-alumina powder.
The pH of aqueous solution A in this step is 8.0 or higher, preferably in the range of 9.0 to 11.0. If the pH deviates excessively from this range, the silica and alumina do not react homogeneously, and the silica-alumina does not exhibit high thermal stability, a moderate acid density, or a strong Lewis acid strength, which is undesirable. Furthermore, the temperature of the aqueous solution is preferably in the range of 70 to 180°C. Below the lower limit, the reaction of the silica-alumina precursor becomes insufficient. Above the upper limit, dissolution of the silica-alumina proceeds, and the silica-alumina does not exhibit high thermal stability, a moderate acid density, or a strong Lewis acid strength, which is undesirable. That is, the solid obtained in step (A) is heat-treated by contacting it with water (gas phase or liquid phase). Heat treatment may be performed at any stage of the preparation. While this treatment may improve the mobility of the silica component, the present invention is not limited thereto. While there is no particular upper limit on the heat treatment time, it is preferable to set it to approximately 48 hours from an economical standpoint.

<Process (C)>
A step of cooling the aqueous solution that has been heat-treated in step (B) and separating the solid content to obtain a silica-alumina powder. This step involves washing and drying (calcining) to obtain a silica-alumina powder. Conventional methods can be used.

<Method of producing fluid catalytic cracking catalyst>
(1) A step of mixing the silica-alumina powder component, the binder component, the clay component (extender), the zeolite component, and the additives to obtain a mixed slurry;
(2) spray-drying the mixed slurry obtained in the step (1) to obtain dried particles;
(3) A method for producing a fluid catalytic cracking catalyst, comprising: a step of washing and drying the dried particles obtained in the step (2) to obtain a fluid catalytic cracking catalyst.
In addition, instead of step (3),
(4) A method for producing a fluid catalytic cracking catalyst, comprising the step of washing the dried particles obtained in the step (2) and then further exchanging the particles with a rare earth metal to obtain a rare earth metal-exchanged fluid catalytic cracking catalyst.

The method for producing a fluid catalytic cracking catalyst can be performed using the methods described in JP-A-2020-032350 and JP-A-2020-032352.

The following examples are provided to explain this example in more detail, but the present invention is not limited to these examples.

Example 1
Diluted water glass with a _SiO2 concentration of 5% by mass was subjected to ion exchange using a cation exchange resin to prepare a desalted silicic acid solution with a pH of 2.67. 1,440 g of desalted silicic acid solution with a _SiO2 concentration of 5% by mass was added to 1,750 g of pure water, and a 15% by mass aqueous ammonia solution was added to adjust the pH to 10.8. 810 g ( _Al2O3 concentration 80% by mass) of CATAPAL200 (manufactured by Sasol, shown as AA in Table 1, with a ( ₀₂₀ ) crystallite diameter of 22.5 nm and a specific surface area of 94 ^m2 /g) was added to the diluted silicic acid solution with a pH adjusted to 10.8, and the mixture was stirred at room temperature for 30 minutes. 15% by mass aqueous ammonia solution was then added to adjust the pH of the slurry to 10.8. The mixture was then loaded into an autoclave, heated to 180°C over 3 hours with stirring, and heat-treated for 8 hours to obtain silica-alumina slurry (1).

Silica-alumina slurry (1) was dried at 130°C for 10 hours and pulverized in a mixer. This powder was washed with warm water, then ion-exchanged with an aqueous ammonium sulfate solution and washed with warm water to obtain a washed cake. The washed cake was dried at 130°C for 10 hours to obtain silica-alumina powder S1. The physical properties of silica-alumina powder S1 are shown in Table 2-1, and the CO adsorption FT-IR spectrum is shown in Figure 1.

[Preparation of fluid catalytic cracking catalyst]
1,429 g of water glass ( _SiO2 concentration 17.5% by mass) and 571 g of sulfuric acid (adjusted to a concentration of 25% by mass, hereinafter the same) were added simultaneously and continuously to prepare 2,000 g of silica sol (an example of a silica-based binder) with a _SiO2 concentration of 12.5% by mass. To this silica sol, 1,625 g (dry basis) of kaolin clay, 250 g (dry basis) of silica alumina powder S1, and 375 g (dry basis) of ultra-stabilized Y-type zeolite powder ( _SiO2 / _{Al2O3 molar} ratio 7.1, unit crystallite size 2.440 nm, hereinafter the same) were added to prepare a mixed slurry. The mixed slurry was formed into droplets and spray-dried in a spray dryer with an inlet temperature of 250°C and an outlet temperature of 150°C to obtain spherical particles with an average particle size of 70 μm. The obtained spray-dried particles were washed with warm water, then subjected to ion exchange with an aqueous ammonium sulfate solution and an aqueous rare earth metal chloride solution, and washed with warm water to perform ion exchange treatment so that the RE ₂ O ₃ content was 1.0 mass %. Thereafter, the catalyst particles were dried in a dryer in an atmosphere of 150°C to obtain a fluid catalytic cracking catalyst C1.

Example 2
6,530 g of sodium aluminate aqueous solution ( _Al2O3 concentration 5% by mass) was added to 6,280 g of _{aluminum sulfate} aqueous solution ( _Al2O3 concentration 2.5% by mass) and stirred at 65°C for 1 hour to obtain an alumina slurry. The alumina slurry was then washed with warm water to adjust the _Na2O content of the washed alumina cake to 2% or less by dry mass and the _SO4 content to 1% or less by dry mass. Pure water was then added to the washed alumina cake to prepare a washed alumina slurry with _{an Al2O3} concentration of 12.5%, and a 48% by mass aqueous sodium hydroxide solution was added to adjust the pH to 11.5. The mixture was then aged at 95°C for 20 hours with stirring to obtain a crystalline boehmite slurry (hereinafter referred to as Slurry A, AB in Table 1) ((020) crystallite diameter: 10.7 nm, specific surface area: 178 ^m2 /g).

Diluted water glass with a _SiO2 concentration of 5% by mass was subjected to ion exchange with a cation exchange resin to prepare a desalted silicic acid solution with a pH of 2.67. 620 g of the 5% by mass desalted silicic acid solution was added with a 15% by _mass aqueous ammonia solution to adjust the pH to 10.8. Slurry A: 3100 g ( _Al2O3 concentration 9% by mass) of the desalted silicic acid solution adjusted to pH 10.8 was added and stirred at room temperature for 30 minutes. Then, the mixture was aged at 95°C for 8 hours while stirring to obtain silica alumina slurry (2).

Silica-alumina slurry (2) was prepared in the same manner as in Example 1 to obtain silica-alumina powder S2. The physical properties of silica-alumina powder S2 are shown in Table 2-1, and the spectrum of CO adsorption FT-IR measurement is shown in Figure 1.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst C2 was obtained by the same procedure as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder S2.

Example 3
A silica-alumina slurry (3) was obtained by the same procedure as in Example 2, except that the amount of desalted silicic acid solution having a _SiO2 concentration of 5% by mass was changed to 985 g.
Silica-alumina slurry (3) was prepared in the same manner as in Example 1 to obtain silica-alumina powder S3. The physical properties of silica-alumina powder S3 are shown in Table 2-1, and the spectrum of CO adsorption FT-IR measurement is shown in FIG.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst C3 was obtained by the same procedure as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder S3.

Example 4
The same operation as in Example 2 was carried out, except that the aging process of the mixed slurry of slurry A and desalted silicic acid solution adjusted to pH 10.8 was changed from 95 ° C. for 8 hours to 150 ° C. for 8 hours in an autoclave, to obtain silica alumina slurry (4).
Silica-alumina powder S4 was obtained from silica-alumina slurry (4) by the same procedure as in Example 1. The physical properties of silica-alumina powder S4 are shown in Table 2-1, and the spectrum of CO adsorption FT-IR measurement is shown in FIG.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst C4 was obtained by the same procedure as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder S4.

Example 5
According to the method described in EXAMPLE 4 of Patent Document 6, CATAPAL-A manufactured by Sasol was used as the alumina slurry raw material, the amount of alumina slurry added during the heat treatment was reduced by 70%, and after the addition of the alumina slurry was completed, the mixture was heated for 1 hour to prepare a crystalline boehmite slurry (hereinafter referred to as Slurry B, AC in Table 1) ((020) crystallite diameter: 39.0 nm, specific surface area: 85 m ² /g).

Diluted water glass with a _SiO2 concentration of 5% by mass was ion-exchanged with a cation exchange resin to prepare a desalted silicic acid solution with a pH of 2.67. 620 g of the 5% by mass desalted silicic acid solution was added with a 15% by _mass aqueous ammonia solution to adjust the pH to 10.8. Slurry B: 2536 g ( _Al2O3 concentration 11% by mass) of the desalted silicic acid solution adjusted to pH 10.8 was added and stirred at room temperature for 30 minutes. The mixture was then loaded into an autoclave, heated to 180°C over 3 hours with stirring, and heat-treated for 8 hours to obtain silica alumina slurry (5).

Silica-alumina slurry (5) was prepared in the same manner as in Example 1 to obtain silica-alumina powder S5. The physical properties of silica-alumina powder S5 are shown in Table 2-1, and the spectrum of CO adsorption FT-IR measurement is shown in Figure 1.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst C5 was obtained by the same procedure as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder S5.

(Comparative Example 1)
The physical properties of CATAPAL200 alumina manufactured by Sasol are shown as SA in Table 2-2, and the spectrum of CO adsorption FT-IR measurement is shown in FIG.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst CA was obtained by the same procedure as in Example 1, except that the silica-alumina slurry S1 was changed to alumina CATAPAL 200 (SA) manufactured by Sasol.

(Comparative Example 2)
Slurry A was dried at 130°C for 10 hours and pulverized in a mixer. This powder was washed with warm water, then subjected to ion exchange with an aqueous ammonium sulfate solution and washed with warm water to obtain a washed alumina cake. The washed alumina cake was dried at 130°C for 10 hours to obtain crystalline boehmite powder A. The physical properties of alumina powder A are shown as SB in Table 2-2, and the spectrum of CO adsorption FT-IR measurement is shown in Figure 2.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst (R2) was obtained in the same manner as in Example 1, except that the silica-alumina powder S1 was changed to alumina powder A (SB).

(Comparative Example 3)
A silica-alumina slurry (6) was obtained by the same procedure as in Example 2, except that the amount of desalted silicic acid solution having a _SiO2 concentration of 5% by mass was changed to 356 g.
Silica-alumina slurry (6) was prepared by the same procedure as in Example 1 to obtain silica-alumina powder SC. The physical properties of the silica-alumina powder SC are shown in Table 2-2, and the spectrum of the CO adsorption FT-IR measurement is shown in FIG.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst CC was obtained in the same manner as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder SC.

(Comparative Example 4)
Diluted water glass with a _SiO2 concentration of 5% by mass was subjected to ion exchange using a cation exchange resin to prepare a desalted silicic acid solution with a pH of 2.67. 1,440 g of desalted silicic acid solution with a _SiO2 concentration of 5% by mass was added with 1,696 g of pure water, and a 15% by mass aqueous ammonia solution was added to adjust the pH to 10.8. 864 g ( _Al2O3 concentration 75 wt%) of CATAPAL-A ((020) crystallite diameter 2.9 nm, specific surface area 266 ^m2 /g) manufactured by Sasol, shown as AC in Table ₁ , was added to the diluted silicic acid solution with a pH adjusted to 10.8 and stirred at room temperature for 30 minutes. 15% by mass aqueous ammonia solution was then added to adjust the pH of the slurry to 10.8. The mixture was then loaded into an autoclave, heated to 150°C over 2 hours and 30 minutes with stirring, and heat-treated for 8 hours to obtain a silica-alumina slurry (7).

Silica-alumina slurry (7) was prepared in the same manner as in Example 1 to obtain silica-alumina powder SD. The physical properties of silica-alumina powder SD are shown in Table 2-2, and the spectrum of CO adsorption FT-IR measurement is shown in Figure 2.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst CD was obtained in the same manner as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder SD.

(Comparative Example 5)
The physical properties of silica alumina SIRAL20 manufactured by Sasol are shown as SE in Table 2-2, and the spectrum of CO adsorption FT-IR measurement is shown in FIG.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst CE was obtained by the same procedure as in Example 1, except that the silica-alumina powder S1 was changed to silica-alumina SIRAL20 (SE) manufactured by Sasol.

(Comparative Example 6)
According to the method described in EXAMPLE 4 of Patent Document 7, CATAPAL-A manufactured by Sasol was used as the alumina slurry raw material, and after the addition of the alumina slurry was completed, heat treatment was carried out for 1 hour to prepare a crystalline boehmite slurry (hereinafter referred to as Slurry C, AE in Table 1) ((020) crystallite diameter: 67.3 nm, specific surface area: 52 m ² /g).

Diluted water glass with a _SiO2 concentration of 5% by mass was subjected to ion exchange with a cation exchange resin to prepare a desalted silicic acid solution with a pH of 2.67. 620 g of the 5% by mass desalted silicic acid solution was added with a 15% by _mass aqueous ammonia solution to adjust the pH to 10.8. Slurry C: 2536 g ( _Al2O3 concentration 11% by mass) of the desalted silicic acid solution adjusted to pH 10.8 was added and stirred at room temperature for 30 minutes. The mixture was then loaded into an autoclave, heated to 180°C over 3 hours with stirring, and heat-treated for 8 hours to obtain silica alumina slurry (8).

Silica-alumina slurry (8) was prepared in the same manner as in Example 1 to obtain silica-alumina powder SF. The physical properties of silica-alumina powder SF are shown in Table 2-2, and the spectrum of CO adsorption FT-IR measurement is shown in Figure 2.

[Preparation of fluid catalytic cracking catalyst]
A fluid catalytic cracking catalyst CF was obtained by the same procedure as in Example 1, except that the silica-alumina powder S1 was changed to the silica-alumina powder SF.

[Catalytic activity evaluation test]
For the catalysts of each Example and Comparative Example, a catalyst performance evaluation test was performed using an Advanced Cracking Evaluation Micro Activity Test (ACE-MAT) under the same crude oil and the same reaction conditions. However, before these performance evaluation tests were performed, nickel and vanadium were deposited on the surface of each catalyst in amounts of 1000 ppm by mass (the mass of nickel divided by the mass of the catalyst) and 2000 ppm by mass (the mass of vanadium divided by the mass of the catalyst), respectively, and then the catalyst was subjected to a pseudo-equilibration treatment by steaming.

The operating conditions for the activity evaluation test were as follows:
Feedstock: Desulfurized atmospheric residue (DSAR) of crude oil + desulfurized vacuum gas oil (DSVGO) (50 + 50)
Catalyst/throughput mass ratio (C/O): 3.75 and 5.00
Reaction temperature: 520°C
1) Conversion rate = 100 - (LCO + HCO)
2) Boiling point range of gasoline: 30 to 216°C
4) Boiling point range of LCO: 216 to 343°C (LCO: Light Cycle Oil)
5) Boiling point range of HCO: 343°C + (HCO: Heavy Cycle Oil)

The activity evaluation test results are shown in Table 3. The invention examples have lower coke yields than the comparative examples, and can be evaluated as fluid catalytic cracking catalysts with higher gasoline yields.

Claims (5)

A silica-alumina powder having the following characteristics a to f.
a. Contains _SiO2 in the range of 8 to 20 mass%;
b. The crystallite size of the boehmite alumina (020) plane determined by X-ray diffraction is 10 to 50 nm;
c. The specific surface area of the silica-alumina powder is in the range of 90 to 230 m ² /g;
d. The acid density, which is the amount of acid per surface area, is in the range of 0.75 to 1.00 μmol/ ^m2 ;
e. In TG-DTA measurement (weight change-differential thermal analysis), the crystal transition temperature from boehmite alumina to gamma alumina is 470°C or higher;
f) In CO adsorption FT-IR measurement (measurement using a Fourier transform infrared spectrophotometer), a Lewis acid is present which exhibits a peak near 2230 cm ⁻¹ . a step (A) of mixing an aqueous solution containing an alumina hydrate having a specific surface area of 85 to 178 ^{m 2} /g with an aqueous solution containing a silica precursor to prepare an aqueous solution A containing a silica-alumina precursor at 10 to 60°C;
a step (B) of adjusting the pH of the aqueous solution A obtained in the step (A) to 8.0 or more, and then heat-treating the aqueous solution A at 70 to 180°C for 2 hours or more to obtain a silica-alumina slurry A;
and (C) a step of obtaining a silica-alumina powder by separating a solid content from the silica-alumina slurry A,
When the alumina hydrate is subjected to X-ray diffraction analysis, the crystallite size of the boehmite alumina (020) plane is 10 to 50 nm,
the silica precursor is at least one of silicic acid, a silicic acid colloidal solution, a water-soluble silicate, a cationic silicon salt, Ludox ( registered trademark, ammonia type or alkali type), and a quaternary ammonium silicate;
In the step (A), the aqueous solution A is prepared so that the mass ratio of silica to alumina is 8/92 to 20/80. A fluid catalytic cracking catalyst containing the silica-alumina powder described in claim 1. A step (1) of mixing the silica-alumina powder component according to claim 1, a binder component, a clay component (extender), a zeolite component, and an additive to obtain a mixed slurry;
(2) spray-drying the mixed slurry to obtain dried particles;
and (3) washing and drying the dried particles to obtain a fluid catalytic cracking catalyst. Instead of the step (3),
5. The method for producing a fluid catalytic cracking catalyst according to claim 4, further comprising the step (4) of washing the dried particles and then exchanging them with a rare earth metal to obtain a rare earth metal-exchanged fluid catalytic cracking catalyst.