A process for the preparation of a mesopore-rich catalytic cracking catalyst

Abstract

The present application belongs to the technical field of catalyst preparation, and relates to a preparation method of a catalytic cracking catalyst rich in mesopores, which adopts specific large-pore-volume pseudo-boehmite through a two-step homogenization method, in the first step, the specific large-pore-volume pseudo-boehmite is homogenized in a specific manner to obtain slurry A, in the second step, the remaining acidic binder and kaolin, molecular sieve are homogenized to obtain slurry B, and then the two slurries are mixed for molding. The method can use specific large-pore-volume pseudo-boehmite to prepare a heavy oil cracking catalyst suitable for high content of colloid and asphaltene and high carbon residue value, and the obtained catalyst can be applied to catalytic cracking, can enhance heavy oil conversion, reduce coke formation, improve gasoline yield and optimize product distribution.

Description

Technical Field

[0001] This invention belongs to the field of oil refining catalysts, specifically relating to a method for preparing a catalytic cracking catalyst with a rich mesoporous structure. Background Technology

[0002] In recent years, with the increasing severity and deterioration of crude oil, improving heavy oil conversion rate has become an effective means for the refining industry to adjust product structure and increase economic benefits. This has forced FCC catalysts to develop towards an open pore structure with more medium and large pores. However, it is usually difficult to achieve both a medium and large pore structure and a good wear index in FCC catalysts. Therefore, research on adjusting the pore structure of FCC catalysts and optimizing the preparation process of FCC catalysts through matrix components has emerged in large numbers.

[0003] As an important matrix component, the binder has a significant impact on the pore structure and strength of the cracking catalyst.

[0004] CN105983400A discloses a method for preparing a mesoporous alumina binder and its application in heavy oil catalytic cracking catalysts. This invention prepares a mesoporous alumina binder by introducing a triblock polymer template agent P123. Compared to traditional binders, this mesoporous alumina binder possesses a mesoporous channel structure, a large specific surface area, and a large pore volume. This allows for the construction of an effective meso-macropore stepped channel distribution in the resulting catalyst, increasing heavy oil conversion and light oil yield while decreasing coke and heavy oil yields. However, this method is complex and costly.

[0005] CN108262056A discloses a method for preparing a catalytic cracking catalyst with adjustable pore volume. By adding an alkaline substance to a slurry system containing acid-soluble pseudoboehmite acidic sol, the aggregation state of the colloidal particles is changed, thereby making it easier for the colloidal micelles to form more medium and large pores due to water evaporation during spray drying, thus increasing the pore volume of the catalyst.

[0006] The existing methods described above are difficult to create larger pores during the preparation process. For some heavy oils with low saturated hydrocarbon content, high asphaltenes content and carbon residue, and poor crackability, it is desirable for pseudoboehmite to have larger pore sizes. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing a catalytic cracking catalyst with abundant mesoporous structure. The catalyst prepared by this method has good wear resistance index and large pore volume, strong heavy oil conversion capacity and good coke selectivity.

[0008] This invention provides a method for preparing a catalytic cracking catalyst, comprising the following steps:

[0009] (1) Provide macroporous pseudoboehmite, wherein the macroporous pseudoboehmite has a relative crystallinity of 80-92%; the alumina obtained by calcining the macroporous pseudoboehmite at 600℃ for 3 hours has a specific surface area of ​​250-350 m², as measured by the low-temperature nitrogen adsorption capacity method. 2 / g, with a pore volume of 0.7-0.9mL / g, and pores with a diameter of 4-13nm accounting for 75-88% of the total pore volume; the relative crystallinity of the macroporous pseudoboehmite was measured by XRD method, see RIPP139-90, "Analytical Methods for Petrochemical Processes (RIPP Experimental Methods)", Science Press, 1990, edited by Yang Cuiding et al.

[0010] (2) The macroporous pseudoboehmite is mixed and stirred with deionized water, while stirring according to n(H) + Add acid to the slurry at a molar ratio of 0.08 to 0.15 for (Al2O3) and stir for 20 to 30 minutes. Then add the second acid binder at a ratio of 3:1 to 8:1 for the dry weight of macroporous boehmite to the dry weight of the second acid binder. Homogenize for 10 to 20 minutes to obtain slurry A.

[0011] (3) Molecular sieve, clay and deionized water are mixed and stirred evenly, then the third acidic binder is added and mixed, and homogenized for 10-20 minutes to obtain slurry B;

[0012] (4) Mix slurry A and slurry B under stirring, preferably stirring for 60 to 120 minutes, to obtain catalytic cracking catalyst slurry;

[0013] (5) The catalytic cracking catalyst slurry obtained in step (4) is spray-dried, calcined, washed and dried, for example, calcined, washed and dried in sequence to obtain the catalytic cracking catalyst containing macroporous pseudoboehmite.

[0014] In one embodiment, the macroporous pseudoboehmite contains Na2O (calculated as oxides) of no more than 0.05% by weight, for example 0.01-0.05% by weight, and sulfur (calculated as SO3) of no more than 0.5% by weight, for example 0.1-0.5% by weight.

[0015] According to the method for preparing the catalytic cracking catalyst of the present invention, the macroporous pseudoboehmite is prepared by a method comprising the following steps:

[0016] a. Prepare an aluminate solution, then mix it with an alkaline solution to obtain a neutralized slurry;

[0017] b. Optionally adjust the pH of the neutralized slurry;

[0018] c. Aging of neutralized slurry or neutralized slurry after pH adjustment;

[0019] d. The aged slurry is filtered and washed to obtain a filter cake;

[0020] e. The filter cake is dried.

[0021] In one embodiment, in the method for preparing macroporous pseudoboehmite, the process of obtaining the neutralized slurry in step a is a continuous co-current neutralization, with the neutralization pH value controlled at 8-10, preferably 8.5-9.5, the temperature at 45-75℃, and the residence time at 5-30 min.

[0022] In the method for preparing macroporous pseudoboehmite, step b involves adjusting the pH to 9.5-10.8, preferably 9.8-10.5. When the pH value in step a is 9.5-10, pH adjustment is not required.

[0023] In the aforementioned method for preparing macroporous boehmite, the aging conditions in step c are a temperature of 80-99℃ and a time of 2-30h; preferably, the aging temperature is 85-98℃ and the aging time is 4-24h.

[0024] In the aforementioned method for preparing macroporous pseudoboehmite, the aged slurry in step d is subjected to conventional filtration and washing methods such as vacuum filtration and plate and frame filtration.

[0025] In the aforementioned method for preparing macroporous boehmite, the drying process in step e can be carried out by flash drying, oven drying, spray drying, etc., with a drying temperature of 80-150℃.

[0026] In step e, drying is performed to obtain macroporous pseudoboehmite. Preferably, the macroporous pseudoboehmite has a relative crystallinity of 80-92%, and the Na2O content (based on oxides) is preferably 0.01-0.05% by weight, and the SO3 content is preferably 0.1-0.5% by weight (X-ray fluorescence spectroscopy analysis, see standard Q / SH 3360270-2018); the alumina obtained by calcining the macroporous pseudoboehmite at 600℃ for 3 hours has a specific surface area of ​​250-350 m², as measured by the low-temperature nitrogen adsorption capacity method. 2 / g, with a pore volume of 0.7-0.9mL / g, and pores with a diameter of 4-13nm accounting for 75-88% of the total pore volume, the pore size distribution was calculated using the BJH method.

[0027] According to the method for preparing catalytic cracking catalyst of the present invention, in step (2), the acid is selected from hydrochloric acid, nitric acid, sulfuric acid, oxalic acid and phosphoric acid.

[0028] The second acidic binder refers to one or more of the following: aluminum sol, acidic silica sol, ordinary acidified boehmite, aluminosilicate gel, and aluminum phosphate sol, preferably aluminum sol and ordinary acidified boehmite. The third acidic binder refers to one or more of the following: aluminum sol, acidic silica sol, ordinary acidified boehmite, aluminosilicate gel, and aluminum phosphate sol, preferably aluminum sol and ordinary acidified boehmite. The pH values ​​of the second and third acidic binders are each between 1.5 and 4.5.

[0029] The preferred ratio of the macroporous boehmite to the dry weight of the second acidic binder is 4:1 to 6:1.

[0030] According to the method for preparing catalytic cracking catalyst of the present invention, in step (3), the molecular sieve refers to NaY type molecular sieve or modified Y type molecular sieve, such as NaY, HY, REY, REHY, USY, REUSY and other types of high silica-alumina ratio Y zeolite, or one or more of them. Other types of high silica-alumina ratio Y zeolite include modified high silica-alumina ratio Y zeolite obtained by directly synthesizing high silica-alumina ratio Y zeolite and then modifying it.

[0031] The clay is any type of clay that can be used as a catalyst component, such as one or more of kaolin, bentonite, montmorillonite, sepiolite, and diatomaceous earth.

[0032] Preferably, the amounts of molecular sieve, macroporous boehmite material, binder, and clay are 100 parts by weight of the total weight of Y-type molecular sieve, macroporous boehmite material, binder, and clay on a dry basis, wherein the weight of Y-type molecular sieve is 20-40 parts, macroporous boehmite is 10-30 parts, binder including second binder and third acid binder is 6-20 parts, and clay is 10-64 parts.

[0033] The homogenization described in this invention is well known to those skilled in the art, and may include, for example, rapid stirring, stirring with a shearing machine, or grinding, such as ball milling.

[0034] In the catalyst preparation method provided by this invention, the spray drying and calcination are carried out according to existing methods, and this invention has no special requirements. The method also includes processes such as washing and drying of the catalyst after calcination, which can be carried out according to existing methods, and this invention has no special requirements.

[0035] Compared with the prior art, the inventors of this invention discovered during the research process that, in the process of preparing pseudoboehmite by the neutralization and precipitation method of sodium aluminate-aluminum sulfate solution, by precisely controlling the pH of the neutralization reaction, the pH of the aging slurry, the temperature and time of hydrothermal aging, etc., the pseudoboehmite prepared in this way has the advantages of large pore volume, concentrated pore distribution and low impurity content. The prior art cannot obtain pseudoboehmite with the characteristics of this invention.

[0036] The catalytic cracking catalyst preparation method disclosed in this invention involves synthesizing macroporous pseudoboehmite with a specific structure through a specific method. Then, by homogenizing the acid, an acidic second binder, and the macroporous pseudoboehmite in a certain proportion, not only is the binding property of the macroporous pseudoboehmite guaranteed, but the mesoporous and macroporous structure of the macroporous pseudoboehmite is also effectively preserved, reducing the destructive effect of moderately strong acids on the mesoporous and macroporous structure. Furthermore, by mixing the two slurries containing a third acidic binder, the binder particles are facilitated to fully enter the packing gaps between the components, tightly binding the catalyst components together, exhibiting characteristics similar to "double-sided tape." This results in a catalytic cracking catalyst with a good wear index and large pore volume, rich in mesopores, which is beneficial for the diffusion and mass transfer of heavy oil macromolecules within the catalyst channels. When applied to heavy oil catalytic cracking, this catalyst can significantly enhance heavy oil conversion capacity and improve coke selectivity.

[0037] This invention provides a catalytic cracking catalyst comprising macroporous boehmite, molecular sieves, a binder, and clay. The total pore volume of the catalytic cracking catalyst, measured by low-temperature nitrogen adsorption, is not less than 0.2 mL / g, and the pore volume by water droplet method is not less than 0.4 mL / g. The total pore volume refers to the pore volume of pores with a diameter not exceeding 100 nm, measured by low-temperature nitrogen adsorption. The macroporous boehmite has a relative crystallinity of 80-92%, a Na₂O content of 0.01-0.05 wt% and an SO₃ content of 0.1-0.5 wt% (based on oxides). The alumina obtained by calcining the macroporous boehmite at 600℃ for 3 hours has a pore volume of 0.7-0.9 mL / g and a specific surface area of ​​250-350 m². 2 / g, with a pore volume distribution of 4-13nm accounting for 75-88% of the total pore volume. The binder preferably includes a second acidic binder and a third acidic binder.

[0038] The catalytic cracking catalyst provided by the present invention has a pore volume of not less than 0.4 mL / g, for example, 0.42 to 0.50 mL / g, and is rich in mesopores.

[0039] The total pore volume of the catalytic cracking catalyst, as determined by the low-temperature nitrogen adsorption method, is preferably not less than 0.2 mL / g, for example, 0.22-0.30 mL / g.

[0040] The wear index of the catalytic cracking catalyst is not higher than 3%, for example, not higher than 2.5%.

[0041] Preferably, based on the dry weight of the catalytic cracking catalyst, the catalytic cracking catalyst contains 20-40% by weight of molecular sieve, 10-30% by weight of macroporous pseudoboehmite (calculated as alumina), 6-20% by weight of a second acidic binder and a third acidic binder, and 10-64% by weight of clay. The molecular sieve is preferably a Y-type molecular sieve.

[0042] For the low-temperature nitrogen adsorption method, refer to standards GB / T5816-1995 (measurement of specific surface area) and SH / T0572-1993 (measurement of pore size distribution).

[0043] This invention further provides an application of the aforementioned catalytic cracking catalyst in the catalytic cracking of hydrocarbon oils. A method for catalytic cracking using this catalyst includes contacting and reacting the hydrocarbon oil with the aforementioned catalytic cracking catalyst. In one embodiment, the reaction temperature is 470-530°C, the catalyst-to-oil ratio is 3-10, and the reaction time is 1-8 seconds. The reaction can be carried out in a riser reactor or a fluidized bed reactor. The hydrocarbon oil is a heavy oil, such as a heavy oil with high gum and asphaltenes content and a high carbon residue value.

[0044] The catalytic cracking catalyst preparation method provided by this invention can obtain a medium- and macroporous catalytic cracking catalyst with qualified strength and abundant mesoporous structure. When used for heavy oil conversion, this catalyst is beneficial to the diffusion and mass transfer of heavy oil macromolecules in the catalyst channels, resulting in strong heavy oil conversion capacity, good coke selectivity, and high gasoline yield. Attached Figure Description

[0045] Appendix Figure 1 These are pore size distribution diagrams of the catalysts prepared in Example 1 and Comparative Example 1. It can be seen that the catalytic cracking catalyst prepared in this invention is rich in mesoporous structures, and the mesoporous distribution is relatively concentrated. Detailed Implementation

[0046] The following examples will further illustrate the present invention and are intended 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.

[0047] The raw materials used in the preparation of the catalyst are described as follows: kaolin with a solid content of 76 wt%; alumina content in the alumina sol of 21.5 wt%, pH value of 2.37; acidified boehmite with a solid content of 12.0 wt%, acidified with hydrochloric acid, the molar ratio of acid (HCl) to alumina during acidification being 0.12; and the rare earth ultrastable Y zeolite REUSY with a solid content of 85.0 wt% and a cell constant of [missing information]. The content of Na2O is 1.6% by weight and the content of RE2O3 is 12.0% by weight.

[0048] The analysis and evaluation methods are explained below:

[0049] Industrial aluminum sulfate solution: Shandong Anbai Chemical Co., Ltd., with a concentration of 104 g / L based on alumina, a free acid concentration of 3 g H2SO4 / L, and a Fe2O3 concentration ≤150 mg / L;

[0050] NaOH: Sinopharm Group.

[0051] Na2CO3: Sinopharm Group.

[0052] Aluminum hydroxide: Guangxi Branch of Aluminum Corporation of China Limited, alumina content 64.0% (by weight).

[0053] Specific surface area and pore volume analysis: A Micromeritics ASAP 2405N V1.01 automated adsorption analyzer was used, employing the low-temperature static nitrogen adsorption capacity method. The sample surface area was 1.33 × 10⁻⁶ pores. -2 The sample was degassed under vacuum at 300℃ for 4 hours using N2 as the adsorption medium, and the adsorption-desorption isotherm was measured at 77.4K. The specific surface area of ​​the sample was calculated according to the BET formula, and the volume of N2 adsorbed by the sample at a relative pressure p / p0 = 0.98 was measured and converted into liquid nitrogen volume, i.e., total pore volume.

[0054] Water droplet method for measuring orifice volume: in accordance with standard NB / SH / T0955-2017.

[0055] Catalyst strength (wear index) measurement: A certain amount of catalyst is placed in a fixed device and polished 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. See standard Q / SYLS0518-2002.

[0056] 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 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.

[0057] Example 1

[0058] An aluminum sulfate solution with a concentration of 50.0 g / L (prepared from industrial aluminum sulfate solution) and a sodium aluminate solution with a concentration of 220 g / L Al2O3 and 227 g / L Na2O (obtained by reacting NaOH and aluminum hydroxide) were added concurrently to a neutralization reactor for neutralization reaction at a temperature of 60℃, a pH of 8.2, and a residence time of 20 min.

[0059] After neutralization, Na2CO3 solution was added to the slurry to adjust the pH to 9.6. The slurry was heated to 85℃ and held at that temperature for 3 hours. The aged slurry was then filtered using a vacuum filter and washed with deionized water at 90℃ to obtain a filter cake. The filter cake was spray-dried to obtain macroporous pseudoboehmite P1. P1 was calcined at 600℃ for 3 hours to obtain alumina Al. P1 has a pseudoboehmite structure, and Al has a γ-alumina phase. The physicochemical properties are shown in Table 1.

[0060] Take 41.7g of macroporous pseudoboehmite P1 with a solid content of 72% by weight and add it to 108g of deionized water, stir for 20min; add 3.6g of hydrochloric acid with a concentration of 36% by weight and stir for 30min for acidification; add 27.9g of alumina sol with a solid content of 21.5% by weight (the mass ratio of macroporous pseudoboehmite to alumina sol on a dry basis is 5:1), homogenize (using a shear homogenizer, model: T25 digital, manufacturer: IKA) for 15min to obtain slurry A;

[0061] Take 115.8g of kaolin with a solid content of 76% by weight, add 373.1g of deionized water and 46.5g of aluminum sol with a solid content of 21.5% by weight, stir for 30min, then add 77.6g of REUSY molecular sieve with a solid content of 85% by weight, homogenize for 15min to obtain slurry B;

[0062] Slurry A and slurry B were mixed under stirring for 90 minutes to obtain the final catalyst slurry. The slurry was then spray-dried, calcined at 550°C for 2 hours, and finally washed and dried to obtain the catalytic cracking catalyst CAT-1 of this invention. CAT-1 contains, on a dry basis, 33 wt% REUSY molecular sieve, 44 wt% kaolin, 15 wt% macroporous pseudoboehmite, and 8 wt% alumina sol.

[0063] Example 2

[0064] An aluminum sulfate solution with a concentration of 50.0 g / L (prepared from industrial aluminum sulfate solution) and a sodium aluminate solution with a concentration of 220 g / L Al2O3 and 227 g / L Na2O (obtained by reacting NaOH and aluminum hydroxide) were added concurrently to a neutralization reactor for neutralization reaction at a temperature of 55℃, a pH of 9, and a residence time of 20 min.

[0065] After neutralization, Na2CO3 solution was added to the slurry to adjust the pH to 10.2. The slurry was heated to 90℃ and held at that temperature for 6 hours. The aged slurry was then filtered using a vacuum filter and washed with deionized water at 90℃ to obtain a filter cake. The filter cake was spray-dried to obtain macroporous pseudoboehmite P2. P2 was calcined at 600℃ for 3 hours to obtain alumina A2. P2 has a pseudoboehmite structure, and A2 has a γ-alumina phase. The physicochemical properties are shown in Table 1.

[0066] Take 54.1g of macroporous pseudoboehmite P2 with a solid content of 74% by weight and add it to 146g of deionized water, stir for 20min; add 4.8g of 36% hydrochloric acid and acidify for 30min; add 46.5g of aluminum sol with a solid content of 21.5% by weight, wherein the mass ratio of macroporous pseudoboehmite to aluminum sol on a dry basis is 4:1, homogenize for 15min to obtain slurry A;

[0067] Take 105.3g of kaolin with a solid content of 76% by weight, add 339.2g of deionized water and 46.5g of aluminum sol with a solid content of 21.5% by weight, stir for 30min, then add 70.6g of REUSY molecular sieve with a solid content of 85% by weight, homogenize for 15min to obtain slurry B;

[0068] Slurry A and slurry B were mixed under stirring for 90 minutes to obtain the final catalyst slurry. The slurry was then spray-dried and calcined at 550°C for 2 hours. After washing and drying, the catalytic cracking catalyst CAT-2 of the present invention was obtained. The CAT-2 catalyst contained, on a dry basis, 30% by weight of REUSY molecular sieve, 40% by weight of kaolin, 20% by weight of macroporous pseudoboehmite, and 10% by weight of alumina sol.

[0069] Example 3

[0070] An aluminum sulfate solution with a concentration of 50.0 g / L (prepared from industrial aluminum sulfate solution) and a sodium aluminate solution with a concentration of 220 g / L Al2O3 and 227 g / L Na2O (obtained by reacting NaOH and aluminum hydroxide) were added concurrently to a neutralization reactor for neutralization reaction at a temperature of 50°C, a pH of 10.0, and a residence time of 20 min.

[0071] After neutralization, the slurry was heated to 95°C and held at that temperature for 5 hours without adjusting the pH with an alkaline solution. The aged slurry was then filtered using a vacuum filter and washed with deionized water at 90°C to obtain a filter cake. The filter cake was spray-dried to obtain boehmite P3. P3 was then calcined at 600°C for 3 hours to obtain alumina A3. P3 has a boehmite structure, and A3 has a γ-alumina phase. The physicochemical properties are shown in Table 1.

[0072] Take 62g of macroporous pseudoboehmite P3 with a solid content of 74% by weight, add 158g of deionized water, stir for 20min, add 5.3g of hydrochloric acid with a concentration of 36% by weight and acidify for 30min, add 25.6g of aluminum sol with a solid content of 21.5% by weight, wherein the mass ratio of macroporous pseudoboehmite to aluminum sol on a dry basis is 8:1, homogenize for 15min to obtain slurry A;

[0073] Take 92.1g of kaolin with a solid content of 76% by weight, add 296.8g of deionized water and 95.3g of aluminum sol with a solid content of 21.5% by weight, stir for 30min, then add 70.6g of REUSY molecular sieve with a solid content of 85% by weight, homogenize for 15min to obtain slurry B;

[0074] Slurry A and slurry B were mixed under stirring for 90 minutes to obtain the final catalyst slurry. The slurry was then spray-dried and calcined at 550°C for 2 hours. After washing and drying, the catalytic cracking catalyst CAT-3 of the present invention was obtained. The CAT-3 catalyst contained, on a dry basis, 30% by weight of REUSY molecular sieve, 35% by weight of kaolin, 22% by weight of macroporous pseudoboehmite, and 13% by weight of alumina sol.

[0075] Comparative Example 1

[0076] Commercially available boehmite from Shanxi Province was used as a control sample (DP1). A cracking catalyst was prepared according to the method described in Example 1. The resulting DCAT-1 catalyst contained 33 wt% REUSY molecular sieve, 44 wt% kaolin, 15 wt% DP1 boehmite, and 8 wt% alumina sol. DP1 was calcined at 600°C for 3 hours to obtain alumina DA-1.

[0077] Comparative Example 2

[0078] Macroporous boehmite P1 was used in catalyst preparation according to the following steps:

[0079] Take 41.7g of macroporous pseudoboehmite P1 with a solid content of 72% by weight and add it to 108g of deionized water, stir for 20min; add 27.9g of alumina sol with a solid content of 21.5% by weight (the mass ratio of macroporous pseudoboehmite to alumina sol on a dry basis is 5:1), homogenize for 15min to obtain slurry A;

[0080] Take 115.8g of kaolin with a solid content of 76% by weight, add 373.1g of deionized water and 46.5g of aluminum sol with a solid content of 21.5% by weight, stir for 30min, then add 77.6g of REUSY molecular sieve with a solid content of 85% by weight, homogenize for 15min to obtain slurry B;

[0081] Slurry A and slurry B were mixed under stirring for 90 minutes to obtain the final catalyst slurry. The slurry was then spray-dried, calcined at 550°C for 2 hours, and finally washed and dried to obtain the catalytic cracking catalyst DCAT-2 of this invention. On a dry basis, DCAT-2 contains 33 wt% REUSY molecular sieve, 44 wt% kaolin, 15 wt% macroporous pseudoboehmite, and 8 wt% alumina sol.

[0082] Comparative Example 3

[0083] Macroporous boehmite P1 was used in catalyst preparation according to the following steps:

[0084] Take 41.7g of macroporous pseudoboehmite P1 with a solid content of 72% by weight and add it to 108g of deionized water, stir for 20min. Add 3.6g of hydrochloric acid with a concentration of 36% by weight and acidify for 30min to obtain an acidified macroporous pseudoboehmite sample;

[0085] 115.8 g of kaolin with a solid content of 76 wt% was added to 373.1 g of deionized water and stirred for 20 min. Then, 77.6 g of REUSY molecular sieve with a solid content of 85 wt% was added, and stirring was continued for 20 min. Next, macroporous pseudoboehmite acidified sample was added and stirred for 20 min. Finally, 74.4 g of alumina sol with a solid content of 21.5 wt% was added, and stirring was carried out for 30 min to obtain the final catalyst slurry. This slurry was spray-dried and calcined at 550℃ for 2 h. After washing and drying, the catalytic cracking catalyst DCAT-3 of this invention was obtained. On a dry basis, the obtained DCAT-3 catalyst contained 33 wt% REUSY molecular sieve, 44 wt% kaolin, 15 wt% macroporous pseudoboehmite, and 8 wt% alumina sol.

[0086] Comparative Example 4

[0087] Macroporous boehmite P1 was used in catalyst preparation according to the following steps:

[0088] Take 41.7g of macroporous pseudoboehmite P1 with a solid content of 72% by weight and add it to 108g of deionized water, stir for 20min. Add 3.6g of 36% hydrochloric acid and acidify for 30min. Add 14g of alumina sol with a solid content of 21.5% by weight (dry basis mass ratio of macroporous pseudoboehmite to alumina sol is 10:1), homogenize for 15min to obtain slurry A.

[0089] Take 115.8g of kaolin with a solid content of 76% by weight, add 373.1g of deionized water and 60.5g of aluminum sol with a solid content of 21.5% by weight, stir for 30min, then add 77.6g of REUSY molecular sieve with a solid content of 85% by weight, homogenize for 15min to obtain slurry B.

[0090] Slurry A and slurry B were mixed under stirring for 90 minutes to obtain the final catalyst slurry. This slurry was then spray-dried, calcined at 550°C for 2 hours, and finally washed and dried to obtain the catalytic cracking catalyst DCAT-4 of this invention. The obtained DCAT-4 catalyst, on a dry basis, contains 33 wt% REUSY molecular sieve, 44 wt% kaolin, 15 wt% macroporous pseudoboehmite, and 8 wt% alumina sol.

[0091] Comparative Example 5

[0092] Macroporous boehmite P1 was used in catalyst preparation according to the following steps:

[0093] Take 41.7g of macroporous pseudoboehmite P1 with a solid content of 72% by weight and add it to 108g of deionized water, stir for 20min. Add 3.6g of 36% hydrochloric acid and acidify for 30min. Add 69.8g of alumina sol with a solid content of 21.5% by weight (dry basis mass ratio of macroporous pseudoboehmite to alumina sol is 2:1), homogenize for 15min to obtain slurry A.

[0094] Take 115.8g of kaolin with a solid content of 76% by weight, add 373.1g of deionized water and 4.65g of aluminum sol with a solid content of 21.5% by weight, stir for 30min, then add 77.6g of REUSY molecular sieve with a solid content of 85% by weight, homogenize for 15min to obtain slurry B.

[0095] Slurry A and slurry B were mixed under stirring for 90 minutes to obtain the final catalyst slurry. This slurry was then spray-dried, calcined at 550°C for 2 hours, and finally washed and dried to obtain the catalytic cracking catalyst DCAT-5 of this invention. The obtained DCAT-5 catalyst, on a dry basis, contains 33 wt% REUSY molecular sieve, 44 wt% kaolin, 15 wt% macroporous pseudoboehmite, and 8 wt% alumina sol.

[0096] Table 1 Properties of Boehmite

[0097]

[0098] Table 2. Composition and physicochemical properties of catalysts

[0099] Molecular sieve, weight % 33 30 30 33 33 33 33 33 Kaolin, weight % 44 40 35 44 44 44 44 44 Phobospore, % by weight 15 20 22 15 15 15 15 15 Aluminum sol, % by weight 8 10 13 8 8 8 8 8 Phobospore species P1 P2 P3 DP1 P1 P1 P1 P1 <![CDATA[Specific surface area, m 2 / g]]> 303 307 299 287 275 290 312 281 Total pore volume, mL / g 0.23 0.26 0.25 0.18 0.22 0.22 0.23 0.19 Water droplet volume, mL / g 0.42 0.45 0.44 0.37 0.41 0.42 0.43 0.36 Wear index, m% / h 2.1 2.2 2.7 1.7 5.5 6.7 5.1 1.8

[0100] As shown in Table 1, compared with the comparative example, the macroporous boehmite prepared by the present invention has a higher pore volume, higher pore size, and concentrated pore size distribution.

[0101] As can be seen from the data in Table 2, the catalyst containing macroporous boehmite according to the present invention has a high pore volume and good wear resistance.

[0102] Catalysts CAT1-CAT3 and DCAT1 and DCAT5 (DCAT2-DCAT4 were unable to undergo cracking due to insufficient strength) were pre-aged at 800°C with 100% steam for 17 hours in a fixed-bed aging unit, and then evaluated in an ACE unit. The properties of the feedstock are shown in Table 3. The reaction temperature was 500°C, and the catalyst-to-oil weight ratio was 8.04. The conversion rate was calculated as: 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.

[0103] Table 3 Properties of Feed Oil

[0104]

[0105] Table 4 Evaluation Results

[0106]

[0107]

[0108] Table 4 shows that, compared with the comparative examples, the catalysts CAT1-CAT3 prepared according to the embodiments of the present invention exhibit significantly lower heavy oil yield, significantly higher gasoline yield, lower coke yield, and significantly improved coke selectivity. This indicates that the catalytic cracking catalysts prepared according to the present invention possess excellent heavy oil cracking capability and good coke selectivity. It is evident that the catalytic cracking catalysts provided by the present invention, when used for converting feedstocks with high density, low saturated hydrocarbon content, high aromatic and asphaltenes content, and high residual carbon content, demonstrate significantly better conversion effects, higher conversion rates, significantly improved total liquid yield, higher gasoline yield, and significantly reduced coke selectivity.

Claims

1. A method for preparing a catalytic cracking catalyst, comprising the following steps: (1) Provide macroporous pseudoboehmite, wherein the macroporous pseudoboehmite has a relative crystallinity of 80-92%; the alumina obtained by calcining the macroporous pseudoboehmite at 600℃ for 3h has a specific surface area of ​​250-350 m², as measured by the low-temperature nitrogen adsorption capacity method. 2 / g, with a pore volume of 0.7-0.9mL / g, and pores with a diameter of 4-13nm accounting for 75-88% of the total pore volume; (2) Mix the macroporous pseudo-boehmite described in step (1) with deionized water and stir, while stirring according to n(H) + Acid is added to the slurry at a molar ratio of 0.08 to 0.15 for the amount of Al2O3, and the mixture is stirred. Then, the second acid binder is added at a ratio of 3:1 to 8:1 (dry weight of macroporous boehmite: dry weight of second acid binder). The mixture is homogenized for 10 to 20 minutes to obtain slurry A. The acid is one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and phosphoric acid. (3) Molecular sieve, clay and deionized water are mixed and stirred evenly, then the third acidic binder is added and mixed, homogenized, to obtain slurry B; (4) Mix slurry A and slurry B under stirring to obtain catalytic cracking catalyst slurry; (5) The catalytic cracking catalyst slurry obtained in step (4) is spray-dried and shaped, then calcined, washed and dried to obtain the catalytic cracking catalyst.

2. The method for preparing the catalytic cracking catalyst according to claim 1, characterized in that, The stirring in step (2) is for 20-30 minutes; the homogenization in step (3) is for 10-20 minutes; the stirring in step (4) is for 60-120 minutes.

3. The method for preparing the catalytic cracking catalyst according to claim 1, characterized in that, The macroporous pseudoboehmite is prepared by a method comprising the following steps: a. Prepare an aluminate solution, then mix it with an alkaline solution to obtain a neutralized slurry; b. Adjust or not adjust the pH value of the neutralized slurry; c. Aging of neutralized slurry or neutralized slurry after pH adjustment; d. The aged slurry is filtered and washed to obtain a filter cake; e. The filter cake is dried.

4. The method for preparing the catalytic cracking catalyst according to claim 3, characterized in that, The process of obtaining the neutralized slurry in step a is a continuous co-current neutralization, with the neutralization pH controlled at 8-10, the temperature at 45-75℃, and the residence time at 5-30 min; In step b, the pH of the neutralized slurry is adjusted to 9.5-10.8; The aging conditions in step c include: a temperature of 80-99℃ and a time of 2-30 hours; In step e, the drying temperature is 80-150℃.

5. The method for preparing the catalytic cracking catalyst according to claim 3 or 4, characterized in that, In step a, the pH value of the neutralized slurry is 8.5-9.5; in step b, the pH value of the neutralized slurry is adjusted to 9.8-10.

5.

6. The method for preparing the catalytic cracking catalyst according to claim 1 or 3, characterized in that, In step c, the aging temperature is 85-98℃ and the aging time is 4-24h.

7. The method for preparing the catalytic cracking catalyst according to claim 1 or 2, characterized in that, In step (2), the acid is either hydrochloric acid or nitric acid; the macroporous boehmite contains 0.01-0.05% Na2O and 0.1-0.5% SO3 by weight, calculated as oxides.

8. The method for preparing a catalytic cracking catalyst according to claim 1, characterized in that, The second and third acidic binders are each one or more of aluminum sol, silica sol, acidified pseudoboehmite, aluminosilicate gel, and aluminum phosphate sol; the molecular sieve is a NaY type molecular sieve or a Y-type molecular sieve obtained by modifying NaY.

9. The method for preparing a catalytic cracking catalyst according to claim 8, characterized in that, The molecular sieve is one or more of NaY, HY, REY, REHY, USY, and REUSY; the clay is one or more of kaolin, bentonite, montmorillonite, sepiolite, and diatomaceous earth.

10. The catalytic cracking catalyst prepared by the method according to claim 1, comprising a Y-type molecular sieve, a macroporous boehmite material, a binder, and clay, wherein the total pore volume of the catalytic cracking catalyst, measured by low-temperature nitrogen adsorption, is greater than 0.2 mL / g, and the attrition index is not higher than 3%, wherein the total pore volume is the pore volume with a pore diameter not exceeding 100 nm, measured by low-temperature nitrogen adsorption; the macroporous boehmite has a relative crystallinity of 80-92%; and the alumina obtained by calcining the macroporous boehmite at 600℃ for 3 h has a specific surface area of ​​250-350 m², measured by low-temperature nitrogen adsorption capacity method. 2 / g, with a pore volume of 0.7-0.9mL / g, and a pore volume distribution of 4-13nm accounting for 75-88% of the total pore volume; the pore size refers to the diameter, and the pore size distribution is calculated by the BJH method, wherein the binder includes a second acid binder and a third acid binder; on a dry basis, the weight ratio of the macroporous pseudoboehmite and the second acid binder is 3:1 to 8:

1.

11. The catalytic cracking catalyst according to claim 10, characterized in that, The catalytic cracking catalyst has a pore volume of not less than 0.4 mL / g and an attrition index of not more than 2.5% when tested by water droplet method.

12. The catalytic cracking catalyst according to claim 10, characterized in that, Based on the dry weight of the catalytic cracking catalyst, the catalytic cracking catalyst contains 20-40% by weight of molecular sieve, 10-30% by weight of macroporous boehmite (calculated as alumina), 6-20% by weight of binder, and 10-64% by weight of clay.

13. A catalytic cracking method, comprising: The hydrocarbon oil is reacted with the catalytic cracking catalyst obtained according to any one of claims 1 to 9 or the catalytic cracking catalyst according to any one of claims 10 to 12, wherein the hydrocarbon oil is a heavy oil with a high content of gum and asphaltenes and a high carbon residue value.

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