A catalytic cracking catalyst with abundant mesoporous structure and its preparation method

Abstract

A catalytic cracking catalyst with abundant mesoporous structure and its preparation method are disclosed. The catalyst, on a dry basis, comprises: 10-35 wt% mesoporous and macroporous alumina (calculated as alumina), 5-30 wt% acidifying binder (calculated as oxides), 2-20 wt% secondary binder (calculated as oxides), 20-60 wt% molecular sieve, and 5-50 wt% clay; the mesoporous and macroporous alumina is alumina with a pseudo-boehmite structure, having a total pore volume of 0.5-2.0 mL / g, wherein pores of 5-100 nm account for more than 80% of the total pore volume, with an average pore diameter of 5-30 nm and a specific surface area of ​​250-450 m² / g; the mass ratio of the acidifying binder to the mesoporous and macroporous alumina is 0.5-1.0. The catalytic cracking catalyst of this invention has abundant mesoporous structure. According to the low-temperature nitrogen adsorption method, the total pore volume is not less than 0.200 mL / g. The volume of macropores with a diameter of 2~100 nm accounts for more than 70% of the total pore volume, and the volume of mesopores with a diameter of 4~50 nm accounts for more than 60% of the total pore volume. Therefore, it has good wear resistance, enhanced heavy oil conversion capacity, and significantly improved coke selectivity.

Description

Technical Field

[0001] This invention belongs to the field of oil refining catalysts, and more specifically, relates to a catalytic cracking catalyst with abundant mesoporous structure and its preparation method. Prior Technology

[0002] The promulgation and implementation of carbon emission regulations and low-carbon fuel standards have significantly impacted the oil refining industry. Catalytic cracking units, as traditional equipment in oil refining, are major contributors to carbon dioxide emissions due to catalyst coking and regeneration. Therefore, reducing coke yield is the most effective means of reducing carbon emissions from catalytic cracking units. However, with the increasing trend towards heavier and lower-quality feedstocks, the coke yield of catalytic cracking catalysts remains high. Catalysts with mesoporous and macroporous structures facilitate the rapid diffusion of reactant and product molecules, reducing the formation of coke precursors, and simultaneously improving catalyst stripping performance while reducing strippable coke. Therefore, the development of catalytic cracking catalysts with abundant mesoporous and macroporous structures is imperative.

[0003] Heavy oil molecules have a diameter of approximately 3–10 nm. To eliminate diffusion limitations, the optimal pore size range for catalytic cracking catalysts is 2–6 times the diameter of heavy oil molecules, corresponding to a pore size range of 6–60 nm. However, traditional catalytic cracking catalysts have pore sizes smaller than 4 nm, which cannot meet the requirements for heavy oil cracking.

[0004] CN1436835A discloses a catalytic cracking catalyst and its preparation method. The catalyst contains 5-60 wt% mesoporous alumina, 5-60 wt% zeolite, 5-40 wt% binder, and 5-85 wt% clay. The average pore diameter of the mesoporous alumina is not less than 3 nm. The preparation method of the catalytic cracking catalyst is to mix the zeolite with the mesoporous alumina, binder, and clay evenly, and then obtain the catalyst through spraying, calcination, washing, and drying. However, the pore volume with a diameter greater than 2 nm in this catalytic cracking catalyst is still less than 0.2 mL / g.

[0005] CN106179476A discloses a catalytic cracking catalyst, its preparation method, and its application. The catalytic cracking catalyst contains 1-50% by weight of a mesoporous active material. The mesoporous active material has a pseudo-boehmite crystal phase structure, and its anhydrous chemical expression is: (0~0.2)Na₂O·(40~85)Al₂O₃·(10~55)SiO₂·(0.5~10)P₂O₅·(0.5~10)MxOy, where the metal M is selected from Mg, elements of Groups IIB, IIIB, IVB, and VIIB of the periodic table, and one or more of the lanthanide rare earth elements, and y is the highest oxidation state of metal M when it forms an oxide. The values ​​of x and y balance the oxidation states of M and O. It has low coke selectivity and high catalytic cracking activity in heavy oil catalytic cracking, and can obtain high diesel yield and low gasoline sulfur content. However, the prepared catalyst lacks a mesoporous and macroporous structure.

[0006] CN105688977A discloses a method for preparing a catalytic cracking catalyst containing boehmite. The method includes mixing a portion of boehmite with a silicon-containing solution and stirring for at least 15 minutes to prepare modified boehmite A; mixing modified boehmite A, the remaining boehmite B, and clay to prepare a matrix slurry containing boehmite; mixing the matrix slurry and a molecular sieve slurry, homogenizing, shaping, drying, and ion-exchange to obtain the catalytic cracking catalyst. The catalyst prepared by this method has a high macropore volume, with macropore diameters mainly distributed above 100 nm, lacking mesopore structures of 5–100 nm.

[0007] However, due to their poor adhesion, the direct addition of mesoporous and macroporous materials can affect catalyst strength, thus limiting the amount of such materials that can be added and resulting in a minimal increase in the mesoporous structure. Therefore, the preparation of catalytic cracking catalysts with abundant mesoporous structures and good wear resistance remains a research hotspot. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a catalytic cracking catalyst with abundant mesoporous structure and its preparation method. This catalytic cracking catalyst exhibits good wear resistance index, abundant mesoporous structure, strong heavy oil conversion capacity, and good coke selectivity.

[0009] On one hand, the present invention provides a composition for catalytic cracking, comprising, based on the dry weight of the composition: 10-35 wt% mesoporous alumina, 5-30 wt% acidifying binder, 2-20 wt% second binder, 20-60 wt% molecular sieve, and 5-50 wt% clay, wherein the mass ratio of the acidifying binder to the mesoporous alumina is 0.5-1.0; the mesoporous alumina is alumina with a pseudo-boehmite structure, its total pore volume is 0.5-2.0 mL / g, wherein the pore volume of pores with a pore size of 5-100 nm accounts for more than 80% of the total pore volume, its average pore size is 5-30 nm, and its specific surface area is 250-450 m² / g. Preferably, after spray drying and calcination, the composition has an abrasion index of no more than 3.0%·h⁻¹, more preferably 1.0-3.0%·h⁻¹, and a pore volume retention of 5-100 nm pores of 70% or higher, preferably 80%-100%; the pore volume retention of 5-100 nm pores = pore volume of 5-100 nm pores in the catalytic cracking catalyst / (pore volume of 5-100 nm pores in mesoporous and macroporous alumina × macroporous alumina content in the catalytic cracking catalyst).

[0010] In one embodiment, based on the dry weight of the composition, the composition comprises: 10-30% by weight of mesoporous alumina, 8-25% by weight of acidifying binder, 2-15% by weight of secondary binder, 30-45% by weight of molecular sieve, and 10-40% by weight of clay, wherein the mass ratio of the acidifying binder to the mesoporous alumina is 0.5-0.8; the mesoporous alumina is alumina with a pseudo-boehmite structure, its total pore volume is 0.7-1.5 mL / g, wherein the pore volume of pores with a pore size of 5-100 nm accounts for 80%-95% of the total pore volume, its average pore size is 6-20 nm, and its specific surface area is 300-400 m² / g.

[0011] In one embodiment, the acidified adhesive is selected from one or more of aluminum sol, silica sol, and silica-alumina sol, preferably aluminum sol or silica sol. The second adhesive is selected from one or more of acidified boehmite, silica sol, aluminum sol, silica-alumina sol, aluminum phosphate sol, and zirconium sol, preferably aluminum sol, silica sol, or acidified boehmite. The mass ratio of the acidified adhesive to the second adhesive is 0.5 to 5.0.

[0012] In one embodiment, the molecular sieve is selected from one or more of NaY type molecular sieves, high silica-alumina ratio Y zeolites (such as HY, REY, REHY, USY or REUSY) obtained by modifying NaY type molecular sieves, MFI type zeolites, and β zeolites.

[0013] In one embodiment, the clay is a variety of clays that can be used as catalyst components, such as kaolin, bentonite, montmorillonite, sepiolite, diatomite, etc.

[0014] On the other hand, the present invention also provides a method for preparing a catalytic cracking catalyst using the composition described in the present invention, comprising the following steps, which are preferably performed sequentially:

[0015] (1) Mix and stir the medium- and large-pore alumina, clay and all the required acidifying binder evenly to obtain the acidified slurry;

[0016] (2) Add the molecular sieve to the acidified slurry, mix and stir evenly to obtain a second slurry; and

[0017] (3) Add a second binder to the second slurry, mix and stir, spray dry and calcine the resulting mixed slurry to obtain the catalytic cracking catalyst of the present invention.

[0018] In one embodiment, according to the preparation method provided by the present invention, in step (1), 10-35% by weight of the medium- and macroporous alumina, 5-50% by weight of the clay, and 5-30% by weight of the acidifying binder are mixed with deionized water and slurried for a slurry time of not less than 15 min to obtain an acidified slurry, wherein the solid content of the obtained acidified slurry is 15-40% by weight.

[0019] In one embodiment, in step (2), 20-60% by weight of the molecular sieve is added to the acidified slurry, mixed and pulped for a pulping time of not less than 15 min to obtain a second slurry, the solid content of the second slurry being 15-40% by weight.

[0020] In one embodiment, in step (3), 2-20% by weight of the second adhesive is added to the second slurry, and the resulting mixed slurry has a solid content of 15-40% by weight.

[0021] According to a particularly preferred embodiment of the present invention, in the method for preparing a catalytic cracking catalyst using the composition described herein, no other acids are added. For the purposes of this invention, "no other acids are added" means that the acidification required for catalyst preparation is carried out entirely by the acidification binder described herein. Accordingly, in the method described herein, no other acids, such as conventionally used hydrochloric acid, are added, whether for acidification purposes or for other purposes.

[0022] In another aspect, the present invention also provides a catalytic cracking catalyst, which is prepared from the composition described in the present invention by the method described in the present invention.

[0023] In one embodiment, the catalytic cracking catalyst provided by the present invention has a rich mesoporous structure, and the total pore volume, as determined by low-temperature nitrogen adsorption method, is not less than 0.200 mL / g, preferably 0.200~0.300 mL / g, wherein the pore volume of meso-macropores with a pore size of 2~100 nm accounts for more than 70% of the total pore volume, preferably 75%~95%, and the pore volume of mesopores with a pore size of 4~50 nm accounts for more than 60% of the total pore volume, preferably 65%~85%.

[0024] Compared with existing technologies, this invention has the following advantages: On the one hand, existing technologies acidify mesoporous and macroporous alumina to improve catalyst wear performance; however, acidification leads to the disappearance of its original mesoporous and macroporous structure, reducing the catalyst's heavy oil conversion capacity and coke selectivity. On the other hand, existing technologies directly add mesoporous and macroporous alumina material to the catalyst without acidification to increase the macropore volume, but this results in poor catalyst wear performance. In contrast, the catalytic cracking catalyst preparation method of this invention retains the mesoporous and macroporous structure of the alumina, improving heavy oil conversion capacity and coke selectivity, while overcoming the adverse effects of mesoporous and macroporous alumina on catalyst strength.

[0025] Therefore, the catalytic cracking catalyst provided by this invention has abundant 4~50 nm mesoporous structures, good wear resistance, enhanced heavy oil conversion capacity, and significantly improved coke selectivity compared with traditional catalysts. Simple Explanation of the Diagram

[0026] Figure 1 is a pore distribution diagram of the macroporous alumina used in this invention. Figure 2 is a pore distribution diagram of the catalytic cracking catalyst prepared according to Example 1. Figure 3 shows the pore distribution of the catalytic cracking catalyst prepared according to Comparative Example 1. Implementation

[0027] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0028] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0029] This invention provides a composition for catalytic cracking, comprising, based on the dry weight of the composition, 10-35 wt%, preferably 10-30 wt%, of mesoporous alumina, 5-30 wt%, preferably 8-25 wt%, of an acidifying binder, 2-20 wt%, preferably 2-15 wt%, of a second binder, 20-60 wt%, preferably 30-45 wt%, of a molecular sieve, and 5-50 wt%, preferably 10-40 wt%, of clay; wherein the mass ratio of the acidifying binder to the mesoporous alumina is 0.5-1.0, preferably 0.5-0.8. The macroporous alumina refers to alumina with a pseudo-boehmite structure, a total pore volume of 0.5~2.0 mL / g, preferably 0.7~1.5 mL / g, wherein the pore volume of 5~100 nm pores accounts for more than 80% of the total pore volume, preferably 80%~95%, the average pore diameter is 5~30 nm, preferably 6~20 nm, and the specific surface area is 250~450 m² / g, preferably 300~400 m² / g. Preferably, after spray drying and calcination, the composition has an abrasion index of no more than 3.0%·h⁻¹, more preferably 1.0-3.0%·h⁻¹, and a pore volume retention of 5-100 nm pores of 70% or higher, preferably 80%-100%; the pore volume retention of 5-100 nm pores = pore volume of 5-100 nm pores in the catalytic cracking catalyst / (pore volume of 5-100 nm pores in mesoporous and macroporous alumina × macroporous alumina content in the catalytic cracking catalyst).

[0030] In one embodiment, the alumina having a pseudo-boehmite structure can be prepared according to the methods provided in US4010116 and US4206085, the entire contents of which are incorporated herein by reference.

[0031] In one embodiment, the acidified adhesive may be selected from one or more of aluminum sol, silica sol, and silica-alumina sol, preferably aluminum sol, and the second adhesive may be selected from one or more of acidified boehmite, silica sol, aluminum sol, silica-alumina sol, aluminum phosphate sol, and zirconium sol, preferably acidified boehmite.

[0032] In one embodiment, the molecular sieve may be selected from NaY type molecular sieves, high silica-alumina ratio Y zeolites obtained by modifying NaY type molecular sieves, such as REY, HY, REHY, USY, REUSY, MFI type zeolites, Beta zeolites, or one or more of these.

[0033] In one embodiment, the clay refers to various clays that can be used as catalyst components, such as kaolin, bentonite, montmorillonite, sepiolite, and diatomaceous earth. These clays are well known to those skilled in the art.

[0034] The present invention also provides a method for preparing a catalytic cracking catalyst using the composition described herein, comprising the following steps, which are preferably performed sequentially:

[0035] (1) Mix and stir the alumina with medium and large pore structures, clay and acidifying binder evenly to obtain acidifying slurry;

[0036] (2) Add the molecular sieve to the acidified slurry, mix and stir evenly to obtain a second slurry; and

[0037] (3) Add a second binder to the second slurry, mix and stir, spray dry and calcine the resulting mixed slurry to obtain the catalytic cracking catalyst of the present invention.

[0038] In one embodiment, according to the preparation method provided by the present invention, in step (1), alumina with medium and large pore structures, clay, acidified binder and deionized water are mixed and pulped for a pulping time of not less than 15 min, preferably 20 to 60 min, and the solid content of the resulting acidified slurry is 15 to 40% by weight.

[0039] In one embodiment, in step (2), molecular sieves are added to the obtained acidified slurry, and the mixture is stirred for a stirring time of not less than 15 min, preferably 20 to 60 min, and the solid content of the obtained second slurry is 15 to 40% by weight.

[0040] In one embodiment, in step (3), a second binder is added to the obtained second slurry, and the resulting mixed slurry has a solid content of 15-40% by weight.

[0041] In one embodiment, the spray drying and calcination are carried out according to existing methods, and there are no special requirements for this invention. The method also includes processes such as washing and drying after catalyst calcination, which can be carried out according to existing methods, and there are no special requirements for this invention.

[0042] This invention also provides a catalytic cracking catalyst, which is prepared from the composition described in this invention by the method described in this invention. The catalytic cracking catalyst provided by this invention has abundant mesoporous structure, and the total pore volume, as determined by low-temperature nitrogen adsorption, is not less than 0.200 mL / g, preferably 0.200~0.300 mL / g, wherein the pore volume of meso-macropores of 2~100 nm accounts for more than 70% of the total pore volume, preferably 75%~95%; and the pore volume of mesopores of 4~50 nm accounts for more than 60% of the total pore volume, preferably 65%~85%.

[0043] [Example]

[0044] The following embodiments will further illustrate the present invention, aiming to help readers better understand the essence of the present invention and its beneficial effects, but should not be construed as limiting the scope of the present invention.

[0045] The raw materials used to prepare the catalytic cracking catalyst in the following examples are described as follows: kaolin with a solid content of 76 wt%; alumina content in the alumina sol of 21.5 wt%; SiO2 content in the silica sol of 27.0 wt%; properties of conventional boehmite and mesoporous alumina are shown in Table 1; acidified boehmite with a solid content of 12.0 wt%, acidified with hydrochloric acid, with a molar ratio of acid (HCl) to alumina of 0.20 during acidification; the rare earth ultrastable Y zeolite REUSY used has a solid content of 85.0 wt%, a lattice constant of 24.51 Å, and, by weight percentage, a Na2O content of 1.6% and a RE2O3 content of 12.0%. Mesoporous alumina A~D were provided by Sinopec Catalyst Co., Ltd., and their properties are shown in Table 1. Table 1: Properties of Some Materials Sample Name thin diatomite Zhongda hole Alumina A Zhongda hole Alumina B Zhongda hole Alumina C Zhongda hole Alumina D Solid content, % 73.8 70.0 70.8 72.2 70.9 ACR,% 88.6 68.8 82.3 85.6 86.6 Al₂O₃ content, % 98.6 96.6 99.5 99.7 98.5 BET specific surface area, m² / g 231 307 385 389 386 Total pore volume, mL / g 0.42 0.95 1.0 0.9 1.1 5~100 nm pores as a percentage of total pore volume, 25 82 89 84 92 Average pore size, nm 4.9 7.5 15.0 18.2 14.3

[0046] The analysis and evaluation methods are explained as follows:

[0047] Specific surface area and pore volume analysis: An ASAP 2405N V1.01 automated adsorption analyzer from Micromeritics (USA) was used. The low-temperature static nitrogen adsorption capacity method was employed. The sample was degassed under vacuum at 1.33 × 10⁻² Pa and 300 °C for 4 h, using N₂ as the adsorption medium. The adsorption-desorption isotherm of the sample was measured at 77.4 K. The specific surface area of ​​the sample was calculated using the BET formula. The volume of N₂ adsorbed by the sample at a relative pressure p / p₀ = 0.98 was measured and converted to liquid nitrogen volume, i.e., the total pore volume. The micropore volume was calculated using the t-plot method. The difference between the two was the volume of mesopores (2–100 nm). The pore volumes of mesopores (4–50 nm) and mesopores (5–100 nm) were obtained using peak fitting.

[0048] Catalyst strength: A certain amount of catalyst is placed in a fixed device and milled under a constant airflow for 5 hours. The average percentage of wear in the last four hours (excluding the first hour) is called the catalyst wear index, expressed as % per hour. The method and standard are: airlift method Q / SYLS0518-2002.

[0049] Catalytic cracking catalyst evaluation: The catalytic cracking catalyst was pre-aged at 800℃ and 100% steam for 12 hours in a fixed-bed aging unit, and then evaluated in an ACE unit. The properties of the feedstock oil are shown in Table 8. The reaction temperature was 500℃, and the catalyst-to-oil weight ratio was 8.04. The conversion rate = gasoline yield + LPG yield + dry gas yield + coke yield, and the coke selectivity = coke yield / conversion rate.

[0050] Example 1

[0051] Add 142 g of kaolin and 114 g of mesoporous alumina A to 291 g of water, stir for 15 minutes, then add 279 g of aluminum sol and continue stirring for 60 minutes to obtain an acidified slurry. Add molecular sieve slurry (containing 155 g of REUSY molecular sieve with a solid content of 35% by weight) to the acidified slurry and continue stirring for 30 minutes to obtain a second slurry. Add 93 g of aluminum sol to the second slurry and continue stirring for 30 minutes. Spray dry the resulting total slurry to form a shape, then calcine at 500°C for 2 hours to obtain the catalytic cracking catalyst C1 described in this invention. The pore distribution of the obtained catalyst C1 is shown in Figure 2. The catalyst composition and properties are shown in Table 2.

[0052] Example 2

[0053] Add 153 g of kaolin and 86 g of mesoporous alumina B to 440 g of water, stir for 30 minutes, then add 186 g of alumina sol and continue stirring for 60 minutes to obtain an acidified slurry. Add molecular sieve slurry (containing 169 g of REUSY molecular sieve with a solid content of 38% by weight) to the acidified slurry and continue stirring for 40 minutes to obtain a second slurry. Add 333 g of acidified pseudoboehmite to the second slurry and continue stirring for 60 minutes. Spray dry the resulting total slurry to form a shape, then calcine at 500°C for 2 hours to obtain the catalytic cracking catalyst C2 described in this invention. The catalyst composition and properties are shown in Table 2.

[0054] Example 3

[0055] Add 100g of kaolin and 139g of mesoporous alumina C to 578g of water, stir for 20 minutes, then add 279g of alumina sol and 74g of silica sol, and continue stirring for 60 minutes to obtain an acidified slurry. Add molecular sieve slurry (containing 141g of REUSY molecular sieve with a solid content of 38% by weight) to the acidified slurry, and continue stirring for 60 minutes to obtain a second slurry. Add 111g of alumina sol to the second slurry, and continue stirring for 30 minutes. Spray dry the resulting total slurry to form a shape, and then calcine at 500℃ for 2 hours to obtain the catalytic cracking catalyst C3 described in this invention. The composition and properties of the catalyst are shown in Table 2.

[0056] Example 4

[0057] Add 153 g of kaolin, 56 g of mesoporous alumina D, and 149 g of alumina sol to 179 g of water, mix thoroughly, and stir for 90 minutes to obtain an acidified slurry. Add molecular sieve slurry (containing 179 g of REUSY molecular sieve with a solid content of 35% by weight) to the acidified slurry, and continue stirring for 60 minutes to obtain a second slurry. Add 500 g of acidified pseudoboehmite to the second slurry, and continue stirring for 60 minutes. Spray dry the resulting total slurry to form a shape, and then calcine at 550°C for 1.5 hours to obtain the catalytic cracking catalyst C4 described in this invention. The catalyst composition and properties are shown in Table 2.

[0058] Example 5

[0059] Add 63 g of kaolin and 169 g of mesoporous alumina D to 474 g of water, stir for 45 minutes, then add 372 g of alumina sol and continue stirring for 60 minutes to obtain an acidified slurry. Add molecular sieve slurry (containing 155 g of REUSY molecular sieve with a solid content of 35% by weight) to the acidified slurry and continue stirring for 60 minutes to obtain a second slurry. Add 74 g of silica sol to the second slurry and continue stirring for 30 minutes. Spray dry the resulting total slurry to form a shape, then calcine at 500°C for 2 hours to obtain the catalytic cracking catalyst C5 described in this invention. The catalyst composition and properties are shown in Table 2.

[0060] Compare with Example 1

[0061] In this comparative example, a conventional acidification method was used, in which mesoporous and macroporous alumina was first acidified with hydrochloric acid, and then a catalytic cracking catalyst was prepared.

[0062] 114 g of macroporous alumina A was added to 286 g of water and stirred for 15 minutes. Then, 16 g of 36% hydrochloric acid was added for acidification (at an acid-to-alumina mass ratio of 0.20), and the mixture was stirred for 60 minutes to obtain an acidified slurry. 142 g of kaolin was added to 138 g of water and stirred for 60 minutes. Then, molecular sieve slurry (containing 155 g of REUSY molecular sieve with a solid content of 35% by weight) was added, and the mixture was stirred for another 30 minutes to obtain a second slurry. The acidified slurry and the second slurry were mixed and stirred for 30 minutes, then 372 g of aluminum sol was added and mixed thoroughly for 60 minutes. The resulting slurry was spray-dried and calcined at 500℃ for 2 hours to obtain the control catalyst DC1. The pore distribution of the obtained catalyst DC1 is shown in Figure 3. The catalyst composition and properties are shown in Table 2.

[0063] Compare with Example 2

[0064] In this comparative example, mesoporous alumina was not pre-mixed with the acidifying binder and was used directly to prepare the catalytic cracking catalyst.

[0065] 114 g of macroporous alumina A and 142 g of kaolin were added to 811 g of water and stirred for 60 minutes to obtain an acidified slurry. Then, a molecular sieve slurry (containing 155 g of REUSY molecular sieve with a solid content of 35% by weight) was added and stirred for another 30 minutes to obtain a second slurry. 372 g of alumina sol was then added and mixed thoroughly for 30 minutes. The resulting total slurry was spray-dried and calcined at 500℃ for 2 hours to obtain the control catalyst DC2. The composition and properties of the catalyst are shown in Table 2.

[0066] Compare with Example 3

[0067] The catalytic cracking catalyst was prepared according to the method in Example 1 of CN1436835A.

[0068] 615 g of macroporous alumina A, 1555 g of REUSY molecular sieve, 1628 g of alumina sol, 2093 g of kaolin, and 9000 g of deionized water were thoroughly mixed and stirred for 2 hours. After homogenization, the mixture was spray-dried to form microspheres. The resulting microspheres were calcined at 450 °C for 0.5 hours to obtain the control catalyst DC3. The composition and properties of the catalyst are shown in Table 2. Table 2: Catalyst Composition and Properties Example 1 Example 2 Example 3 Example 4 Example 5 Compare with Example 1 Compare with Example 2 Compare with Example 3 catalyst C1 C2 C3 C4 C5 DC1 DC2 DC3 Medium and macroporous alumina, % 20 15 25 10 30 20 20 10 Kaolin, % 27 29 19 29 12 27 27 47 Acidified adhesive, % 15 10 20 8 20 -- -- -- Molecular sieve, % 33 36 30 38 33 33 33 33 Second adhesive, % 5 10 6 15 5 20 20 10 Solid content of acidified slurry, % 30 25 twenty two 35 twenty three -- -- -- Second slurry solid content, % 28 25 19 30 twenty four -- -- -- Total slurry solids content, % 27.5 22.9 27.4 24.2 23.7 25.0 25.0 25.0 Acidified adhesive to mesoporous gibbsite mass ratio 0.75 0.67 0.80 0.80 0.67 -- -- -- Wear index, m% / h 2.2 2.5 1.8 2.8 2.2 2.5 6.5 3.6 Total pore volume, mL / g 0.24 0.23 0.23 0.22 0.25 0.18 0.19 0.17 2-100 nm pore volume as a percentage of total pore volume, % 85 80 78 88 85 54 60 58 4-50 nm pore volume as a percentage of total pore volume, 79 72 70 80 75 48 50 44

[0069] Example 6

[0070] Catalysts C1-C5 prepared in Examples 1-5 and catalysts DC1-DC3 prepared in Comparative Examples 1-3 were pre-aged at 800°C and 100% steam for 12 hours in a fixed-bed aging unit, and then evaluated in an ACE unit. The properties of the feedstock oil are shown in Table 3. The reaction temperature was 500°C, and the catalyst-to-oil weight ratio was 8.02. Conversion rate = gasoline yield + LPG yield + dry gas yield + coke yield; total liquid yield = LPG yield + gasoline yield + diesel yield; coke selectivity = coke yield / conversion rate. The evaluation results are shown in Table 4. Table 3: Properties of Feedstock Oil crude oil Density (20℃), g / cm³ 0.9044 Refraction (20℃) 1.5217 Viscosity (100℃), mm² / s 9.96 Freezing point, ℃ 40 Aniline point, ℃ 95.8 C,m% H,m% S,m% N,m% 85.98 12.86 0.55 0.18 Residual char, m% 3.0 Distillation range, °C Initial boiling point 5% 10% 30% 50% 70% 90% 243 294 316 395 429 473 - Table 4: Evaluation Results Example 1 Example 2 Example 3 Example 4 Example 5 Compare with Example 1 Compare with Example 2 Compare with Example 3 Catalyst name C1 C2 C3 C4 C5 DC1 DC2 DC3 Produce Taste distributed% dry air 1.79 1.84 1.77 1.94 1.82 1.94 1.76 1.80 Liquefied gas 17.32 17.67 17.46 17.75 17.38 17.37 16.89 17.34 gasoline 53.07 54.29 52.66 53.47 52.94 52.12 51.64 51.34 diesel fuel 13.63 12.78 14.03 12.81 13.83 12.68 13.39 13.48 heavy oil 6.23 6.31 6.81 6.09 6.59 7.01 7.75 7.92 coke 7.96 7.11 7.27 7.94 7.44 8.88 8.57 8.12 Conversion rate, % 80.14 80.91 79.16 81.10 79.58 80.31 78.86 78.60 Total liquid yield, % 84.02 84.74 84.15 84.03 84.15 82.17 81.92 82.16 Coke selectivity, % 9.93 8.79 9.18 9.79 9.35 11.06 10.87 10.33

[0071] As shown in Table 2 and the accompanying figures, compared with Comparative Examples 1-3, the total pore volume and the proportion of macropores and mesopores in Examples 1-5 are significantly increased, while maintaining good wear resistance. Table 4 shows that, correspondingly, compared with catalysts DC1-DC3 prepared in Comparative Examples 1-3, catalysts C1-C5 prepared in the embodiments of the present invention have lower heavy oil yield, increased total liquid yield, lower coke yield, and significantly improved coke selectivity. Therefore, the catalytic cracking catalysts prepared in this invention possess abundant macropores and mesopores, resulting in excellent heavy oil cracking capability and good coke selectivity, while also exhibiting good catalyst strength.

[0072] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

[0073] none

Claims

1. A composition for catalytic cracking, comprising, on a dry weight basis: 10-35 wt% mesoporous alumina, 5-30 wt% a first binder, wherein the first binder is an acidifying binder, 2-20 wt% a second binder, 20-60 wt% molecular sieves, and 5-50 wt% clay, wherein the mass ratio of the acidifying binder to the mesoporous alumina is 0.5-1.0; the mesoporous alumina is alumina with a pseudoboehmite structure, having a total pore volume of 0.5-2.0 mL / g, wherein the pore volume of 5-100 nm pores accounts for more than 80% of the total pore volume, having an average pore size of 5-30 nm, and a specific surface area of ​​250-450 m² / g; wherein the composition, after spray drying and calcination, has an attrition index not greater than 3.0 %·h⁻¹, and the 5-100 nm pores have a specific surface area of ​​250-450 m² / g. The pore volume retention of the 5-100 nm pores is 70% or higher; the pore volume retention of the 5-100 nm pores is calculated as follows: Pore volume retention of 5-100 nm pores = pore volume of 5-100 nm pores in the catalytic cracking catalyst / (pore volume of 5-100 nm pores in mesoporous and macroporous alumina × macroporous alumina content in the catalytic cracking catalyst), where, The pH value of the acidified adhesive is 1.0-5.

0.

2. The composition as claimed in claim 1, wherein, Based on the dry weight of the composition, the composition comprises: 10-30% by weight of mesoporous alumina, 8-25% by weight of acidifying binder, 2-15% by weight of secondary binder, 30-45% by weight of molecular sieve, and 10-40% by weight of clay, wherein the mass ratio of the acidifying binder to the mesoporous alumina is 0.5-0.8; the mesoporous alumina is alumina with a pseudo-boehmite structure, its total pore volume is 0.7-1.5 mL / g, wherein the pore volume of 5-100 nm pores accounts for 80%-95% of the total pore volume, its average pore diameter is 6-20 nm, and its specific surface area is 300-400 m² / g.

3. The composition as claimed in claim 1, wherein, The acidified adhesive is in an aqueous form; the second adhesive may be the same as or different from the acidified adhesive.

4. The composition as claimed in claim 1, wherein, The acidified adhesive is selected from one or more of aluminum sol, silica sol, and silica-alumina sol, and the second adhesive is selected from one or more of acidified boehmite, silica sol, aluminum sol, silica-alumina sol, aluminum phosphate sol, and zirconium sol, and the mass ratio of the acidified adhesive to the second adhesive is 0.5 to 5.

0.

5. The composition as claimed in claim 4, wherein, The acidified adhesive is aluminum sol, and the second adhesive is acidified boehmite.

6. The composition as claimed in claim 1, wherein, The clay is selected from one or more of kaolin, bentonite, montmorillonite, sepiolite, and diatomite.

7. The composition as claimed in claim 1, wherein, The molecular sieve is selected from one or more of NaY molecular sieve, high silica-alumina ratio Y zeolite obtained by modifying NaY molecular sieve, MFI type zeolite, and β zeolite.

8. The composition as claimed in claim 7, wherein, The high silicon-to-alumina ratio Y zeolite obtained after modification of the NaY molecular sieve is HY, REY, REHY, USY, or REUSY.

9. A method for preparing a catalytic cracking catalyst using the composition of any one of claims 1-8, comprising the following steps performed sequentially: (1) mixing and stirring alumina with a mesoporous or macroporous structure, clay, and all the required acidifying binder and deionized water to obtain an acidified slurry; (2) adding a molecular sieve to the acidified slurry and mixing and stirring to obtain a second slurry; and (3) adding a second binder to the second slurry, mixing and stirring, and spray-drying and calcining the resulting mixed slurry.

10. The method as described in claim 9, wherein, Based on the dry weight of the catalyst, in step (1), 10-35% by weight of the medium- and macroporous alumina, 5-50% by weight of the clay, 5-30% by weight of the acidifying binder and deionized water are mixed and pulped for a pulping time of not less than 15 min to obtain an acidified slurry with a solid content of 15-40% by weight; in step (2), 20-60% by weight of the molecular sieve is added to the acidified slurry, mixed and pulped for a pulping time of not less than 15 min to obtain a second slurry with a solid content of 15-40% by weight; and / or in step (3), 2-20% by weight of the second binder is added to the second slurry, and the solid content of the resulting mixed slurry is 15-40% by weight.

11. The method as described in claim 9 or 10, wherein, No other acids are added in this method.

12. A catalytic cracking catalyst prepared from the composition of any one of claims 1-8 by the method of claim 9 or 10.

13. The catalytic cracking catalyst as claimed in claim 12, wherein, The total pore volume of the catalytic cracking catalyst, as determined by the low-temperature nitrogen adsorption method, is not less than 0.200 mL / g, wherein the pore volume of meso-macro pores with a pore size of 2~100 nm accounts for more than 70% of the total pore volume, and the pore volume of meso-pores with a pore size of 4~50 nm accounts for more than 60% of the total pore volume.

14. The catalytic cracking catalyst as claimed in claim 12 or 13, wherein, The total pore volume of the catalytic cracking catalyst, as determined by low-temperature nitrogen adsorption, is 0.200~0.300 mL / g; wherein the pore volume of meso-macropores with a pore size of 2~100 nm accounts for 75%~95% or 80%~95% of the total pore volume; and / or the pore volume of mesopores with a pore size of 4~50 nm accounts for 65%~85% of the total pore volume.

Images