Zinc-modified aluminum sol, preparation method and application

Abstract

The present invention relates to the field of aluminum sol for catalytic cracking catalysts, and discloses a zinc-modified aluminum sol, a preparation method, and an application thereof. The preparation method comprises: (1) performing a first contact reaction on a zinc source and a first acid at a temperature of 20-90°C; (2) performing a second contact reaction on the feed liquid obtained in step (1) and the first aluminum source at a temperature of 50-80°C, and then adding a second acid to perform a third contact reaction; (3) performing a fourth contact reaction on the feed liquid obtained in step (2) and the second aluminum source, wherein the temperature of the fourth contact reaction is 60-80°C, to obtain a zinc-modified aluminum sol. The obtained zinc-modified aluminum sol product has better bonding properties as a binder for the catalyst, and can improve the catalytic activity of the catalyst in the heavy oil cracking reaction, effectively increasing the yield of BTX and light olefins.

Description

Technical Field

[0001] The present invention relates to the field of aluminum sol for catalytic cracking catalysts, and in particular to a zinc-modified aluminum sol and a preparation method and application thereof. Background Art

[0002] Between 2010 and 2020, demand for major petrochemical intermediates such as ethylene, propylene, and paraxylene increased by approximately 4% annually, a growth rate that paralleled changes in global GDP over the same period. Fuel demand, meanwhile, has roughly tracked population growth since 2010, at approximately 1%. According to the International Energy Agency, petrochemicals will rapidly become the largest driver of global oil consumption. To address this shift in oil consumption toward lower fuel oil demand and higher demand for petrochemicals, promoting the oil-to-chemical transition and developing catalytic cracking catalysts that increase the production of BTX and light olefins will be particularly important.

[0003] Research has found that introducing P and other elements into molecular sieves can improve their stability, cracking activity, and yields of light olefins such as propylene. Zn is also an important dehydrogenation active center in molecular sieves, but the two easily react during the preparation process, reducing the effectiveness of the metal active center and consuming valuable components.

[0004] Furthermore, the most common catalyst process in my country involves preparing a uniform slurry of binder, matrix, and active matrix, followed by spray drying. As the content of molecular sieves, the active component in catalysts, increases, the corresponding catalyst attrition index and sphericity have become crucial issues in catalyst preparation.

[0005] In view of the above problems, the present invention improves the preparation process of aluminum sol to enhance its bonding performance, and at the same time, introduces dehydrogenation active components to enhance the pre-cracking ability of the carrier to form a new type of dual-function catalyst. Summary of the Invention

[0006] The purpose of the present invention is to provide a zinc-modified aluminum sol and its preparation method and application. The zinc-modified aluminum sol product prepared by the preparation method has better bonding performance as a binder for the catalyst, and can improve the cracking activity of the catalytic cracking catalyst, effectively increasing the yield of BTX and light olefins.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a zinc-modified aluminum sol, comprising the following steps:

[0008] (1) contacting a zinc source with a first acid at a temperature of 20-60° C.;

[0009] (2) at a temperature of 60-80° C., subjecting the liquid obtained in step (1) and the first aluminum source to a second contact reaction, and then adding a second acid to conduct a third contact reaction;

[0010] (3) The slurry obtained in step (2) is subjected to a fourth contact reaction with a second aluminum source, wherein the temperature of the fourth contact reaction is 60-80° C. to obtain a zinc-modified aluminum sol.

[0011] The second aspect of the present invention provides a zinc-modified aluminum sol prepared by the method described in the first aspect.

[0012] The third aspect of the present invention provides the use of the zinc-modified aluminum sol described in the second aspect in a catalytic cracking catalyst.

[0013] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0014] (1) The zinc-modified aluminum sol product prepared by the method provided by the present invention is used as a component of a catalyst, which has the effect of improving the cracking activity of the catalytic cracking catalyst and effectively increasing the yield of BTX and light olefins;

[0015] (2) The zinc-modified aluminum sol product prepared by the method provided by the present invention has better bonding properties. As a binder for the catalyst, it can make the catalyst have the advantages of low wear index and high mechanical strength;

[0016] (3) The method provided by the present invention can effectively retain the dehydrogenation active components of the catalyst and inhibit their migration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The zinc-modified aluminum sol prepared in Example 1 of the present invention is 27 Al NMR spectrum;

[0018] Figure 2 The aluminum sol prepared in Comparative Example 1 of the present invention is 27 Al NMR spectrum. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0020] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0021] The first aspect of the present invention provides a method for preparing a zinc-modified aluminum sol, comprising the following steps:

[0022] (1) contacting a zinc source with a first acid at a temperature of 20-60° C.;

[0023] (2) at a temperature of 60-80° C., subjecting the liquid obtained in step (1) and the first aluminum source to a second contact reaction, and then adding a second acid to conduct a third contact reaction;

[0024] (3) The slurry obtained in step (2) is subjected to a fourth contact reaction with a second aluminum source, wherein the temperature of the fourth contact reaction is 60-80° C. to obtain a zinc-modified aluminum sol.

[0025] The preparation method of the present invention introduces Zn into the alumina sol, which, on the one hand, inhibits the migration of Zn species and, on the other hand, prevents the decrease in active center content caused by the reaction of Zn with phosphorus and other substances. Furthermore, the introduction of Zn consumes free chlorine, promoting the further polymerization of monomeric aluminum to form highly polymerized aluminum species, thereby improving the bonding properties of the resulting alumina sol. The alumina sol produced by the method provided by the present invention can enhance the cracking activity of the catalyst in catalytic cracking reactions, effectively increasing the yields of BTX and light olefins.

[0026] According to the present invention, the first aluminum source and the second aluminum source may be the same or different. In order to obtain a zinc-modified aluminum sol with better performance, preferably, the first aluminum source and the second aluminum source are each independently selected from at least one of aluminum ingots, aluminum sheets, aluminum chips, aluminum powder, aluminum hydroxide, aluminum chloride, aluminum nitrate, pseudo-boehmite, boehmite, bauxite and aluminum isopropoxide; further preferably, the first aluminum source and the second aluminum source are each independently selected from at least one of aluminum hydroxide, aluminum chloride, aluminum isopropoxide, aluminum sheets, aluminum chips and aluminum powder.

[0027] According to the present invention, the zinc source acts as a dehydrogenation active center, enabling the prepared aluminum sol to possess catalytic cracking activity and improving the catalyst's selectivity for light olefins in the catalytic cracking reaction. Preferably, the zinc source is selected from metallic zinc and / or a zinc-containing compound, preferably a zinc-containing compound.

[0028] According to the present invention, preferably, the zinc-containing compound is selected from at least one of zinc hydroxide, zinc chloride, zinc nitrate, zinc oxide, zinc acetate, zinc carbonate, zinc phosphate, zinc particles, monobasic zinc, and dibasic zinc, and more preferably at least one of zinc hydroxide, zinc chloride, zinc acetate, zinc carbonate, and zinc particles.

[0029] According to the present invention, preferably, the zinc source is calculated as zinc element, the first aluminum source and the second aluminum source are calculated as aluminum oxide, and the weight ratio of the zinc source: (first aluminum source + second aluminum source) is (0.01-0.1):1, and further preferably (0.02-0.08):1.

[0030] According to the present invention, preferably, the weight ratio of the first aluminum source: the second aluminum source is 1:(0.2-0.6), and more preferably 1:(0.2-0.5).

[0031] According to the present invention, preferably, the first acid and the second acid are each independently an inorganic acid. Preferably, the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid, and phosphoric acid, more preferably hydrochloric acid. In the present invention, when a mixture of the above acids is used, there is no particular limitation on the ratio of the acids in the mixture.

[0032] According to the present invention, the amount of the acid used is closely related to the amount of the aluminum source used. Preferably, the weight ratio of (first acid + second acid): aluminum is (0.8-1.5):1, more preferably (0.8-1.2):1, wherein the acid is calculated as acid radical, and the aluminum element here refers to total aluminum, that is, the sum of the aluminum elements in the first and second aluminum sources. Controlling the appropriate acid-to-aluminum ratio can increase the degree of polymerization of the aluminum species and reduce the impact of low pH on the crystallinity of the molecular sieve material.

[0033] According to the present invention, preferably, the weight ratio of the first acid to the second acid is (0.5-4):1.

[0034] According to the present invention, the acid is preferably in the form of an aqueous solution of the acid, which can be prepared by oneself or obtained commercially, as long as an aqueous solution of the acid with a suitable concentration is available. In the present invention, preferably, the concentration of the acid is 5-20% by weight, more preferably 12-18% by weight.

[0035] According to the present invention, in step (1), in the first contact reaction, the zinc source reacts with the first acid to form a mixed solution of zinc chloride and acid. Preferably, the first contact reaction lasts for 2-5 hours.

[0036] According to the present invention, in step (2), the first aluminum source is added to the product solution obtained in step (1) to carry out a second contact reaction, wherein the aluminum ions undergo preliminary hydrolysis in a zinc-rich environment. The product solution obtained in step (2) mainly contains aluminum monomers and oligomeric aluminum species such as dimer aluminum and trimer aluminum. Preferably, the second contact reaction lasts for 5-10 hours.

[0037] According to the present invention, in step (2), preferably, the third contact reaction is carried out at the same temperature as the second contact reaction. Preferably, the third contact reaction is carried out for 5-10 hours.

[0038] According to the present invention, in step (3), the second aluminum source can neutralize the remaining free chlorine and increase the degree of polymerization of the aluminum species in the fourth contact reaction to obtain a zinc-modified aluminum sol. Preferably, the fourth contact reaction lasts for 5-10 hours.

[0039] According to the present invention, to improve the uniformity of the contact reaction, preferably, the reactions in each step of the present invention are each independently carried out under stirring conditions. Conventional stirring methods can be used, such as mechanical stirring, magnetic stirring, etc. Preferably, in each step, the stirring speed is independently 300-500 rpm to ensure a more uniform and complete reaction.

[0040] According to the present invention, step (3) further comprises cooling the product system obtained from the fourth contact reaction, followed by filtration to obtain a zinc-modified aluminum sol product. The cooling and filtration can be performed in conventional manners, and the present invention is not particularly limited thereto.

[0041] The second aspect of the present invention provides a zinc-modified aluminum sol prepared by the method described in the first aspect.

[0042] According to the present invention, preferably, in the zinc-modified aluminum sol, the content of aluminum calculated as Al2O3 is 20-24 wt%, and the content of zinc calculated as ZnO is 0.2-2.5 wt%.

[0043] According to the present invention, preferably, the pH of the zinc-modified aluminum sol is 2.5-3.5; the aluminum-chlorine mass ratio is 1.2-1.6, more preferably 1.3-1.5; and the total acid content is 0.3-0.6 mmol / g, more preferably 0.35-0.5 mmol / g.

[0044] The third aspect of the present invention provides the use of the zinc-modified aluminum sol described in the second aspect in a catalytic cracking catalyst.

[0045] Using the zinc-modified alumina sol provided by the present invention as a catalyst binder offers improved bonding properties, resulting in a catalyst with a low wear index and high mechanical strength. Compared to directly loading Zn onto molecular sieves, introducing Zn into the alumina sol enhances the catalyst's cracking activity in catalytic cracking reactions, effectively increasing the yields of BTX and light olefins.

[0046] The present invention will be described in detail below by way of examples, but the scope of the present invention is not limited thereby. In the following examples and comparative examples,

[0047] The aluminum content, zinc content and aluminum-chlorine mass ratio in the prepared zinc-modified aluminum sol were determined using the method specified in RIPP34-90 of the Petrochemical Analytical Methods (RIPP Test Method);

[0048] The pH value of the zinc-modified aluminum sol was measured using a pH meter (manufacturer: Mettler-Toledo);

[0049] Zinc-modified aluminum sol 27 Al NMR spectra were measured using a nuclear magnetic resonance spectrometer (manufacturer: Bruker, model: AVANCE III 600WB);

[0050] The acid content of the zinc-modified aluminum sol was measured using a programmed temperature desorption instrument (manufacturer: Micromeritics, model: Autochem II 2920).

[0051] Example 1

[0052] (1) contacting 5 g of zinc particles with 280 g of 16 wt % hydrochloric acid at 50° C. and stirring at 500 rpm for a first contact reaction for 3 h;

[0053] (2) adding 50 g of aluminum flakes to the solution obtained in step (1), stirring at 75° C. for a second contact reaction for 8 h, then maintaining the temperature, adding 180 g of a 16 wt % hydrochloric acid solution and continuing stirring to carry out a third contact reaction for 8 h;

[0054] (3) 17 g of aluminum chips were added to the liquid obtained in step (2) above, and the fourth contact reaction was continued at 75°C with stirring for 10 hours. After the reaction was completed, the product was cooled to ambient temperature (25°C, the same below) and filtered to obtain a zinc-modified aluminum sol P1 having an aluminum content of 23.5 wt% (calculated as Al2O3) and a zinc content of 0.9 wt% (calculated as ZnO).

[0055] The pH value of P1 is 2.8, the aluminum-chlorine mass ratio is 1.5, and the total acid content is 0.5 mmol / g.

[0056] P1 27 Al NMR spectrum is shown in Figure 1 As shown, from Figure 1 It can be seen that there are characteristic peaks of tetracoordinate aluminum species of medium-polymerized aluminum at δ of 62.5 and 64.5, and a characteristic peak of tetracoordinate aluminum species of high-polymerized aluminum at δ of 70 (partially overlapping with the characteristic peak at δ of 65 in the figure), and there is no characteristic peak of monomeric aluminum at δ of 0. It can be seen that the Al element in P1 mainly exists in medium and high-polymerized forms, and basically does not contain monomeric aluminum.

[0057] Example 2

[0058] (1) contacting 5 g of zinc chloride and 5 g of zinc carbonate with 280 g of 16 wt % hydrochloric acid at 50° C., and performing a first contact reaction at a stirring rate of 500 rpm for 5 h;

[0059] (2) adding 50 g of aluminum flakes to the solution obtained in step (1), stirring at 75° C. for a second contact reaction for 8 h, then maintaining the temperature, adding 180 g of a 16 wt % hydrochloric acid solution and continuing stirring to carry out a third contact reaction for 8 h;

[0060] (3) 17 g of aluminum chips was added to the liquid obtained in step (2) above, and the fourth contact reaction was continued at 75° C. with stirring for 10 h. After the reaction, the product was cooled to ambient temperature (25° C., the same below) and filtered to obtain a zinc-modified aluminum sol P2 having an aluminum content of 23.6 wt.% (calculated as Al2O3) and a zinc content of 0.93 wt.% (calculated as ZnO).

[0061] The pH value of P2 is 2.9, the aluminum-chlorine mass ratio is 1.45, and the total acid content is 0.49 mmol / g.

[0062] P2 has similar 27 Al NMR spectrum.

[0063] Example 3

[0064] (1) contacting 5.2 g of zinc chloride and 6.5 g of zinc carbonate with 280 g of a 16 wt% aqueous solution of hydrochloric acid at 50° C., and performing a first contact reaction at a stirring rate of 500 rpm for 1 h;

[0065] (2) adding 50 g of aluminum flakes to the solution obtained in step (1), stirring at 75° C. for a second contact reaction for 8 h, then maintaining the temperature, adding 180 g of a 16 wt % hydrochloric acid solution and continuing stirring to carry out a third contact reaction for 8 h;

[0066] (3) 17 g of aluminum chips were added to the solution obtained in step (2) above, and the fourth contact reaction was continued at 75° C. with stirring for 10 h. After the reaction, the product was cooled to ambient temperature (25° C., the same below) and filtered to obtain zinc-modified aluminum sol P3 having an aluminum content of 23.5 wt.% (calculated as Al2O3) and a zinc content of 1.18 wt.% (calculated as ZnO).

[0067] The pH value of P3 is 3.0, the aluminum-chlorine mass ratio is 1.46, and the total acid content is 0.48 mmol / g.

[0068] P3 has similar 27 Al NMR spectrum.

[0069] Example 4

[0070] (1) contacting 5 g of zinc particles with 280 g of a 16 wt % aqueous solution of hydrochloric acid at 50° C., and performing a first contact reaction at a stirring rate of 500 rpm for 3 h;

[0071] (2) adding 50 g of aluminum flakes to the solution obtained in step (1), stirring at 75° C. for a second contact reaction for 8 h, then maintaining the temperature, adding 145 g of a mixed solution of 16 wt % hydrochloric acid and 30 g of 16 wt % phosphoric acid, and continuing stirring, to carry out a third contact reaction for 8 h;

[0072] (3) 17 g of aluminum chips were added to the liquid obtained in step (2) above, and the fourth contact reaction was continued at 75° C. with stirring for 10 h. After the reaction, the product was cooled to ambient temperature (25° C., the same below) and filtered to obtain zinc-modified aluminum sol P4 having an aluminum content of 23.5 wt.% (calculated as Al2O3) and a zinc content of 0.9 wt.% (calculated as ZnO).

[0073] The pH value of P4 is 2.7, the aluminum-chlorine mass ratio is 1.5, and the total acid content is 0.5 mmol / g.

[0074] P4 has similar characteristics to P1 27 Al NMR spectrum.

[0075] Comparative Example 1

[0076] 360 g of a 16 wt% hydrochloric acid solution was heated to 80°C, and 67 g of aluminum flakes were added. The temperature was maintained, and the reaction was carried out at a stirring rate of 500 rpm for 20 hours. After the reaction, the product was cooled to ambient temperature (25°C, the same below) and filtered to obtain aluminum sol D1 with a concentration of 20 wt% (calculated as Al2O3).

[0077] The pH value of D1 is 2.5, the aluminum-chlorine mass ratio is 1.2, and the total acid content is 0.33 mmol / g.

[0078] D1 27 Al NMR spectrum is shown in Figure 2 As shown, from Figure 2 It can be seen that there is a characteristic peak of tetracoordinate aluminum species of mesopolymeric aluminum at δ of 64.5, and a characteristic peak of monomeric aluminum at δ of 0.

[0079] Test Case

[0080] Alumina sols P1-P4 and D1 prepared in Examples 1-4 and Comparative Example 1 were used as binders to prepare catalytic cracking catalysts according to the following method A. A catalytic cracking catalyst was also prepared using D1 according to the following method B. The attrition index and catalytic activity of the prepared catalytic cracking catalysts were tested. Method A and method B comprise:

[0081] Method A: Kaolin and water are slurried, followed by the addition of acidified pseudo-boehmite (pseudo-boehmite is mixed with water and then acidified by adding hydrochloric acid under stirring until peptized), and stirred to obtain slurry A; ZSM-5 molecular sieve is slurried with water to obtain a molecular sieve slurry; slurry A and the molecular sieve slurry are added to alumina sols P1-P4 and D1, respectively, and stirred for 30 minutes to obtain a catalyst slurry (solid content 28 wt%). The catalyst slurry comprises, based on the dry weight of the catalyst slurry, 35 wt% ZSM-5 molecular sieve, 35 wt% kaolin, 10 wt% alumina sol (calculated as Al2O3), and 20 wt% pseudo-boehmite (calculated as Al2O3). The catalyst slurry is spray-dried, and the resulting catalyst microspheres are calcined at 550°C for 1.5 hours to obtain a catalytic cracking catalyst.

[0082] Method B: Kaolin and water are slurried, and then acidified pseudo-boehmite is added (pseudo-boehmite is mixed with water, and then hydrochloric acid is added thereto under stirring to acidify until it is in a peptized state), and stirred to obtain slurry A; ZSM-5 molecular sieve is saturated with zinc chloride (calculated as ZnO, the amount of zinc chloride added accounts for 0.09% of the total catalyst mass), calcined at 550°C for 1.5, and then slurried with water to obtain a molecular sieve slurry; slurry A and molecular sieve slurry are added to aluminum sol D1 in sequence, and stirred for 30 minutes to obtain a catalyst slurry (solid content is 28 weight%). In the catalyst slurry, based on the dry weight of the catalyst slurry, the content of ZSM-5 molecular sieve is 35 weight%, the content of kaolin is 35 weight%, the content of aluminum sol (calculated as Al2O3) is 10 weight%, and the content of pseudo-boehmite (calculated as Al2O3) is 20 weight%. The catalyst slurry was spray-dried, and the obtained catalyst microspheres were calcined at 550° C. for 1.5 h to obtain a catalytic cracking catalyst.

[0083] 1. Wear index test

[0084] The 4-hour wear index of the catalytic cracking catalyst prepared above was evaluated according to the method specified in RIPP 29-90 of the Petrochemical Analytical Methods (RIPP Test Method). The results are shown in Table 1.

[0085] Table 1

[0086] catalyst 4h wear consumption rate / % Wear index Catalyst prepared by P1 (using method A) 2.28 0.57 Catalyst prepared by P2 (using method A) 2.44 0.61 Catalyst prepared by P3 (using method A) 2.32 0.58 Catalyst prepared by P4 (using method A) 2.52 0.63 Catalyst prepared by D1 (using method A) 3.40 0.85 Catalyst prepared by D1 (using method B) 3.24 0.81

[0087] 2. Catalytic activity evaluation

[0088] The catalytic cracking catalyst prepared by using the above aluminum sol was hydrothermally aged at 800℃ with 100% steam for 17h, and then the n-tetradecane cracking activity was evaluated. The test conditions were: the reaction raw material was n-tetradecane, the catalyst loading was 2.5g, the reaction temperature was 550℃, and the volume space velocity was 1.93h -1 The agent-oil ratio (weight) was 1.6. The results are shown in Table 2.

[0089] Table 2

[0090]

[0091] It can be seen from Table 1 and Table 2 that the zinc-modified aluminum sol prepared by the method provided by the present invention has better bonding performance, which is reflected in the prepared catalyst having a lower wear index, thereby bringing higher mechanical strength.

[0092] Compared to the comparative example, the zinc-modified alumina sol provided by the present invention can improve the cracking activity of the catalyst in the catalytic cracking reaction, achieving higher yields of BTX and light olefins. Furthermore, compared to the conventional method of preparing the catalyst by directly loading Zn onto a molecular sieve, the present invention, by introducing Zn into the alumina sol and using it to prepare the catalyst, can achieve higher catalyst wear resistance and higher BTX and light olefin yields in the catalytic cracking reaction.

[0093] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing zinc-modified aluminum sol, characterized in that: The following steps are involved: (1) contacting the zinc source with the first acid at a temperature of 20-60° C.; (2) at a temperature of 60-80° C., subjecting the liquid obtained in step (1) and the first aluminum source to a second contact reaction, and then adding the second acid to conduct a third contact reaction; (3) subjecting the liquid obtained in step (2) to a fourth contact reaction with a second aluminum source, wherein the temperature of the fourth contact reaction is 60-80° C. to obtain a zinc-modified aluminum sol; The zinc source is calculated as zinc element, the first aluminum source and the second aluminum source are calculated as aluminum oxide, and the weight ratio of the zinc source: (first aluminum source + second aluminum source) is (0.01-0.1):1; The weight ratio of the first aluminum source to the second aluminum source is 1:(0.2-0.6); (First acid + second acid): The weight ratio of the aluminum element is (0.8-1.5): 1, wherein the acid is calculated as an acid radical; The first acid and the second acid are each independently an inorganic acid; the weight ratio of the first acid to the second acid is (0.5-4):

1.

2. The method according to claim 1, wherein The first aluminum source and the second aluminum source are each independently selected from at least one of aluminum ingots, aluminum sheets, aluminum chips, aluminum powder, aluminum hydroxide, aluminum chloride, aluminum nitrate, pseudo-boehmite, boehmite, bauxite and aluminum isopropoxide.

3. The method according to claim 2, wherein: The first aluminum source and the second aluminum source are each independently selected from at least one of aluminum hydroxide, aluminum chloride, aluminum isopropoxide, aluminum flakes, aluminum chips, and aluminum powder.

4. The method according to any one of claims 1 to 3, wherein: The zinc source is selected from metallic zinc and / or zinc-containing compounds.

5. The method according to claim 4, wherein The zinc source is a zinc-containing compound.

6. The method according to claim 5, wherein: The zinc-containing compound is selected from at least one of zinc hydroxide, zinc chloride, zinc nitrate, zinc oxide, zinc acetate, zinc carbonate, zinc phosphate, zinc particles, zinc monoacid, and zinc diacid.

7. The method according to claim 6, wherein: The zinc-containing compound is selected from at least one of zinc hydroxide, zinc chloride, zinc acetate, zinc carbonate and zinc particles.

8. The method according to claim 1, wherein The zinc source is calculated as zinc element, the first aluminum source and the second aluminum source are calculated as aluminum oxide, and the weight ratio of the zinc source: (first aluminum source + second aluminum source) is (0.02-0.08):1; And / or, the weight ratio of the first aluminum source: the second aluminum source is 1:(0.2-0.5).

9. The preparation method according to any one of claims 1 to 3, wherein The inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid and phosphoric acid.

10. The preparation method according to claim 9, wherein The inorganic acid is hydrochloric acid; And / or, the weight ratio of (first acid+second acid):aluminum element is (0.8-1.2):1, wherein the acid is calculated as acid radical.

11. The method according to any one of claims 1 to 3, wherein: The first contact reaction, the second contact reaction, the third contact reaction and the fourth contact reaction are each independently carried out under stirring conditions, and the stirring speed is each independently 300-500 rpm; And / or, the first contact reaction time is 2-5h; And / or, the second contact reaction time is 5-10h; And / or, the third contact reaction time is 5-10 hours; And / or, the fourth contact reaction time is 5-10 hours.

12. A zinc-modified aluminum sol prepared by the method according to any one of claims 1 to 11. 13 . The zinc-modified aluminum sol according to claim 12 , wherein the content of aluminum in the zinc-modified aluminum sol calculated as Al 2 O 3 is 20-24 wt %, and the content of zinc in the zinc-modified aluminum sol calculated as ZnO is 0.2-2.5 wt %. The zinc-modified aluminum sol according to claim 12 or 13, wherein the zinc-modified aluminum sol has a pH of 2.5-3.5, an aluminum-chlorine mass ratio of 1.2-1.6, and a total acid content of 0.3-0.6 mmol / g. 15 . The zinc-modified aluminum sol according to claim 14 , wherein the aluminum-chlorine mass ratio of the zinc-modified aluminum sol is 1.3-1.5; and the total acid content is 0.35-0.5 mmol / g.

16. Use of the zinc-modified aluminum sol according to any one of claims 12 to 15 in a catalytic cracking catalyst.

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