Alumina support containing spherical cavities and method for its preparation

Abstract

The application discloses an alumina carrier containing a spherical cavity and a preparation method thereof. The carrier comprises an inner core, a first layer outside the core, a second layer and a shell layer from the core to the outer surface; the inner core is a spherical alumina grain aggregate; the first and second layers outside the core are spherical grain and flaky grain aggregates, wherein the flaky grains are grown in situ in the spherical cavity formed by the spherical grains; and the shell layer is flaky grains grown in situ on the outer surface of the second layer. The preparation method is as follows: (1) rolling balls of pseudo-boehmite and a physical pore-expanding agent to obtain S0; (2) mixing pseudo-boehmite and activated carbon to obtain material W1, and rolling balls of W1 and S0 to obtain S1; (3) mixing pseudo-boehmite and activated carbon to obtain material W2, mixing W2 and S1, performing ball rolling molding, and immersing in an epoxy propane aqueous solution for sealed heat treatment to prepare the alumina carrier. The pore distribution of the alumina carrier is favorable for the diffusion of macromolecular reactants to the interior, and the alumina carrier is suitable for macromolecular heterogeneous catalyst reactions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material synthesis, and particularly relates to a spherical cavity-containing distributed alumina carrier and a preparation method thereof. BACKGROUND

[0002] Alumina materials are widely used as catalyst carriers in multiphase hydrogenation due to their high specific surface area, rich pore structure and good controllable acid-base properties. For hydrogenation of macromolecular materials such as heavy oil, diffusion of macromolecular materials through the pores to the active sites of the catalyst is the control step of the reaction. Therefore, the presence of appropriate macroporous structures in the catalyst can reduce the mass transfer resistance of the materials, improve the catalytic reaction efficiency, and prolong the service life of the catalyst. The pore structure of the catalyst largely depends on the properties of the carrier. The industrial alumina carrier has the problems of small pore size and poor space connectivity, which cannot meet the harsh requirements of processing heavy and poor quality distillates. Therefore, developing a macroporous alumina carrier with strong mass transfer capacity is one of the important routes for developing new and efficient heavy oil hydrogenation catalysts.

[0003] CN104646008A discloses a poor quality heavy oil hydrodesulfurization and demetallization catalyst and a preparation method thereof. The catalyst uses alumina as the carrier and VIB and VIII elements, especially Ni-Mo, as the active component. The pore volume of the catalyst is 0.61-0.70 mL / g, the specific surface area is 155-200 m 2 / g, and the average pore diameter is 13.0-18.0 nm. The preparation method of the catalyst is to treat the carrier particles after molding and calcination with an acid solution with continuously increasing concentration. Although this method can make the average pore diameter of the final catalyst gradually increase from the center to the surface of the catalyst particle, it is difficult to form large pores on the surface of the carrier by this treatment method.

[0004] CN106669853A discloses a preparation method of a spherical modified alumina carrier. The spherical modified alumina carrier has the following properties: having a double pore distribution, the pore diameter is 10-15 nm and 15-30 nm; wherein the pore distribution of 10-15 nm accounts for 35%-40% of the total pore volume, and the pore distribution of 15-30 nm accounts for 30%-35% of the total pore volume; the auxiliary agent accounts for 2%-5% in element amount based on the weight of the carrier, and the auxiliary agent concentration gradually increases from the center of the carrier particle to the outer surface, wherein the auxiliary agent content at 1 / 4R is 0.5wt%-1.0wt%, the auxiliary agent content at 1 / 2R is 1.5wt%-2.0wt%, and the auxiliary agent content at R is 2.5wt%-3.0wt%, wherein R is the radius of the carrier particle with the center of the spherical modified alumina carrier as the initial point; wherein the auxiliary agent is one of the following I, II and III combinations: I-fluorine and phosphorus, II-fluorine and boron, III-fluorine, phosphorus and boron. The alumina carrier prepared by the method has a gradient distribution of auxiliary agents, but the pore gradient distribution is poor, which is not conducive to the diffusion of macromolecular reactants. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides an alumina carrier containing spherical cavities and a preparation method thereof. The alumina carrier of the present application has a micrometer-scale pore size and content that increases from the center of the carrier to the outer surface. This pore structure is conducive to the diffusion of macromolecular reactants into the interior of the carrier and is suitable for use in macromolecular heterogeneous catalyst reactions, particularly in the field of heavy oil and residue hydroprocessing.

[0006] The alumina carrier containing spherical cavities of the present application is a spherical carrier, which includes an inner core, a first layer outside the core, a second layer outside the core, and a shell layer from the center of the sphere to the outer surface. The distance from the center of the sphere to the outer surface of the second layer outside the core is r;

[0007] The thickness of the inner core is 0.3r-0.5r, and the inner core is a spherical alumina grain aggregate. The size of the spherical alumina grains is 80-260 nm.

[0008] The thickness of the first layer outside the core is 0.1r-0.5r. This layer is a spherical alumina grain and flaky alumina grain aggregate, wherein the flaky alumina grains grow in situ in the spherical cavities formed by the spherical alumina grains. The size of the spherical cavities is 1-5 μm, the size of the flaky alumina grains is 100 nm-600 nm, the filling rate of the spherical cavities is 40%-80%, and the area ratio of the spherical cavities is 10%-30%.

[0009] The second layer outside the core has a thickness of 0.1r-0.5r, and is an aggregate of spherical alumina grains and flaky alumina grains, wherein the flaky alumina grains are in-situ grown in spherical cavities formed by the spherical alumina grains, the size of the spherical cavities is 5-10 μm, the size of the flaky alumina grains is 100 nm-600 nm, the filling rate of the spherical cavities is 40%-80%, and the area ratio of the spherical cavities is 25%-50%;

[0010] The shell layer is flaky alumina grains in-situ grown on the outer surface of the second layer outside the core, the size of the flaky alumina grains is 100 nm-600 nm, and the coverage rate is 85%-100%.

[0011] The filling rate refers to the percentage of the volume of the flaky alumina grains in the spherical cavities in the volume of the spherical cavities; the coverage rate refers to the percentage of the surface occupied by the flaky alumina grains on the outer surface of the second layer outside the core; and the area ratio of the spherical cavities refers to the percentage of the area of the spherical cavities in the cross section of the alumina carrier in the total area of the corresponding core layer.

[0012] In the alumina carrier, the flaky alumina grains in the shell layer accumulate to form open channels with a size of 40-300 nm, and the flaky alumina grains in the spherical cavities of the first layer and the second layer outside the core accumulate to form through channels with a size of 50-100 nm.

[0013] The specific surface area of the alumina carrier is 200-350 m 2 / g, and the pore volume is 0.6-1.2 mL / g.

[0014] The preparation method of the alumina carrier with spherical cavities comprises the following steps:

[0015] (1) mixing pseudo-boehmite and a physical pore-expanding agent to obtain a spherical precursor S0 by balling;

[0016] (2) mixing pseudo-boehmite and a first spherical activated carbon to obtain a material W1, and mixing the material W1 with the spherical precursor S0 to perform balling to obtain a spherical precursor S1;

[0017] (3) mixing pseudo-boehmite and a second spherical activated carbon to obtain a material W2, and mixing the material W2 with the spherical precursor S1 to perform balling, and then drying and calcining to obtain a precursor S2;

[0018] (4) sealing and heat-treating the precursor S2 in an aqueous propylene oxide solution, and performing solid-liquid separation on the treated material, and then drying and calcining the solid-phase material to obtain an alumina carrier with spherical cavities.

[0019] (4) sealing and heat-treating the precursor S2 in an aqueous propylene oxide solution, and performing solid-liquid separation on the treated material, and then drying and calcining the solid-phase material to obtain an alumina carrier with spherical cavities.

[0020] (4) sealing and heat-treating the precursor S2 in an aqueous propylene oxide solution, and performing solid-liquid separation on the treated material, and then drying and calcining the solid-phase material to obtain an alumina carrier with spherical cavities.

[0021] In the method of the present application, the pseudo-boehmite particles in steps (1), (2) and (3) are in the form of granules, which can be commercially available or prepared by methods such as acid precipitation, alkali precipitation, alcohol aluminum hydrolysis, etc. Preferably, the pseudo-boehmite has a pore size of greater than 10 nm. The pseudo-boehmite in steps (1), (2) and (3) can be the same or different, preferably the same.

[0022] In the method of the present application, the rolling ball forming is carried out in a rotary table forming machine, and the operating conditions of the rotary table forming machine are as follows: the inclination angle of the rotary table is 40-70°, and the rotation speed of the rotary table is 10-30 rpm; the forming time of the material in the rotary table is 5-120 min. A water solution containing a glue solvent is sprayed into the material during the forming process; the water solution containing the glue solvent is one or a mixture of several of the water solutions of nitric acid, phosphoric acid, oxalic acid and acetic acid, and the mass concentration of the solution is 1%-3%, preferably the water solution of acetic acid.

[0023] In the method of the present application, the physical pore-expanding agent in step (1) is an inorganic substance such as activated carbon, wood chips and carbon black, or an organic substance such as urea, propylene glycol glycerol, triethylene glycol, melamine, or a water-soluble organic polymer such as polyethylene glycol, polyethylene oxide, methyl cellulose, polyoxyethylene, polyacrylamide and starch. The mass ratio of the physical pore-expanding agent to the pseudo-boehmite is 1:100-3:100.

[0024] In the method of the present application, the first spherical activated carbon in step (2) has a diameter of 1-5 microns, which can be prepared by existing methods or purchased, and the mass ratio of the first spherical activated carbon to the pseudo-boehmite is 1:6.7-1:12.5.

[0025] In the method of the present application, the second spherical activated carbon in step (3) has a diameter of 5-10 microns, which can be prepared by existing methods or purchased, and the mass ratio of the second spherical activated carbon to the pseudo-boehmite is 1:4-1:6.7.

[0026] In the method of the present application, the drying temperature in step (3) is 100-160°C, and the drying time is 2-8 hours. The calcination is carried out in an oxygen atmosphere, the calcination temperature is 450-600°C, and the calcination time is 4-6 hours.

[0027] In the method of the present application, the mass percentage concentration of the propylene oxide aqueous solution in step (4) is 2.5%-12%, preferably 4%-8%, and the mass ratio of the amount of the propylene oxide aqueous solution to the alumina carrier precursor is 3:1-10:1, preferably 4:1-8:1.

[0028] The sealing heat treatment in step (4) is preferably carried out in a sealed autoclave, and is preferably two-step sealing heat treatment, i.e. first low-temperature sealing heat treatment at 60-100 ℃ for 1-4 hours, and then sealing heat treatment at 110-180 ℃, preferably 120-160 ℃, for 14-20 hours.

[0029] In the method of the present application, the drying temperature in step (4) is 100-160 ℃, the drying time is 2-8 hours, the calcination temperature is 500-750 ℃, and the calcination time is 4-6 hours, and the calcination is carried out in an oxygen-containing atmosphere, preferably air.

[0030] Compared with the prior art, the present application has the following advantages: in the preparation of the alumina carrier precursor, the particle size and the amount of the microspherical activated carbon are adjusted so that the microspherical activated carbon is distributed in a gradient in the radial direction of the carrier. During calcination of the carrier precursor, the microspherical activated carbon is removed by oxidation, and corresponding micropores are formed in the carrier, and the diameter and content of the micropores are distributed in a gradient, i.e. the size and content of the micropores increase from the center to the surface of the carrier. During the sealing hydrothermal treatment of the alumina carrier precursor in the propylene oxide aqueous solution, the propylene oxide is hydrolyzed to form an alcohol solution and make the solution weakly alkaline during the low-temperature sealing heat treatment. During the high-temperature sealing hydrothermal treatment, the alumina grains on the surface of the carrier and in the micropores grow in situ to form flaky alumina grains in the alkaline and alcohol solution. The flaky alumina on the surface of the carrier accumulates to form open pores with a diameter of 40-300 nm, and the flaky alumina in the micropores accumulates to form through pores with a diameter of 50-100 nm. This pore structure is beneficial to the diffusion of macromolecular reactants into the carrier, and this carrier material is particularly suitable for use as a heavy oil hydroprocessing catalyst carrier. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is an SEM image of the outer surface of the alumina carrier precursor prepared in Example 1.

[0032] Figure 2 Figure 2 is an SEM image of the cross section of the alumina carrier precursor prepared in Example 1.

[0033] Figure 3 is an SEM image of the outer surface of the alumina carrier prepared in Example 1.

[0034] Figure 4 Figure 4 is an SEM image of the cross section of the alumina carrier prepared in Example 1.

[0035] Figure 5 is an SEM image of the outer surface of the alumina carrier prepared in Comparative Example 2.

[0036] Figure 6 Figure 6 is an SEM image of the cross section of the alumina carrier prepared in Comparative Example 2. DETAILED DESCRIPTION

[0037] The technical solutions and technical effects of the present application are further illustrated below in combination with examples, but are not limited to the following examples. In the present application, wt% represents mass fraction.

[0038] The microstructure of the alumina carrier is characterized by a scanning electron microscope, and the specific operation is as follows: the microstructure of the carrier is characterized by a JSM-7500F scanning electron microscope, the acceleration voltage is 5KV, the acceleration current is 20µA, and the working distance is 8mm.

[0039] Micron spherical activated carbon preparation:

[0040] The micron spherical activated carbon used in the present application is prepared according to the method in the literature: Dalin, Li Wei, Wu Qiong, et al. Hydrothermal carbonization-CO2 activation of carboxymethyl cellulose to prepare micron spherical activated carbon [J]. Forest Chemistry and Industry, 2015, 35 (4): 21-27. The prepared micron spherical activated carbon has a diameter of 1-5 microns and 5-10 microns, respectively. Example 1

[0041] (1) 6 grams of methyl cellulose are uniformly mixed with 200 grams of pseudoboehmite, and the mixed material is placed in a rotary table forming machine for full mixing, the inclination angle of the rotary table is adjusted to 45º, and the rotary speed of the rotary table is 15 rpm; a 1% acetic acid aqueous solution is sprayed onto the material in the rotary table through a sprayer after mixing and contacting, the forming time of the material in the rotary table is 35 min, and a spherical precursor S0 is obtained;

[0042] (2) 7.5 grams of activated carbon with a diameter of 1-5 microns and 100 grams of pseudoboehmite are weighed, and the above materials are added to a kneading machine for full mixing. The mixed material and the spherical precursor S0 prepared in step (1) are placed in a rotary table forming machine for full mixing, the inclination angle of the rotary table is adjusted to 45º, and the rotary speed of the rotary table is 15 rpm; a 1% acetic acid aqueous solution is sprayed onto the material in the rotary table through a sprayer after mixing and contacting, the forming time of the material in the rotary table is 25 min, and a spherical precursor S1 is obtained;

[0043] (2) 7.5 grams of activated carbon with a diameter of 1-5 microns and 100 grams of pseudoboehmite are weighed, and the above materials are added to a kneading machine for full mixing. The mixed material and the spherical precursor S0 prepared in step (1) are placed in a rotary table forming machine for full mixing, the inclination angle of the rotary table is adjusted to 45º, and the rotary speed of the rotary table is 15 rpm; a 1% acetic acid aqueous solution is sprayed onto the material in the rotary table through a sprayer after mixing and contacting, the forming time of the material in the rotary table is 25 min, and a spherical precursor S1 is obtained;

[0044] (3) Take 20 grams of activated carbon with a diameter of 5-10 microns and 100 grams of pseudoboehmite, mix them well in a kneader. Put the mixed material and the spherical precursor S1 prepared in step (2) into a rotating disc forming machine, adjust the inclination of the rotating disc to 45° and the rotating speed to 15 rpm, spray 1% acetic acid solution onto the material in the rotating disc through a sprayer, mix and contact the material, and then form the material in the rotating disc for 25 minutes to obtain spherical precursor S2. Dry the obtained spherical precursor S2 at 140°C for 6 hours, and then calcine it at 500°C in an oxygen atmosphere for 6 hours to obtain an alumina carrier precursor. The scanning electron microscope image of the outer surface of the carrier is shown in Figure 1 , and the cross-sectional scanning electron microscope image is shown in Figure 2 .

[0045] (4) Take 100 grams of the alumina carrier precursor prepared in step (3), add 660 grams of 5.4% propylene oxide solution, and then put the mixed material into an autoclave. After sealing, put the autoclave into an oven, first seal and treat it at 75°C for 2.5 hours, then seal and treat it at 135°C for 17 hours, and then cool the material. After washing and filtering, dry the solid material at 140°C for 6 hours, and then calcine it at 600°C in an air atmosphere for 6 hours to obtain an alumina carrier A1. The properties of the carrier are shown in Table 1, the scanning electron microscope image of the outer surface of the carrier is shown in Figure 3 , and the cross-sectional scanning electron microscope image is shown in Figure 4 . Example 2

[0046] The same as in Example 1, except that the rolling ball forming time in step (1) is 45 minutes. The amount of micron spherical activated carbon added in step (2) is 9 grams, and the rolling ball forming time is 20 minutes. The amount of micron spherical activated carbon added in step (3) is 24 grams, and the rolling ball forming time is 15 minutes. The concentration of propylene oxide in step (4) is 6.6%, and the solution amount is 520 grams. During the hydrothermal treatment, first seal and treat it at 85°C for 2 hours, then seal and treat it at 145°C for 16 hours to obtain an alumina carrier A2. The properties of the carrier are shown in Table 1. Example 3

[0047] The same as in Example 1, except that the rolling ball forming time in step (1) is 40 minutes. The amount of micron spherical activated carbon added in step (2) is 12 grams, and the rolling ball forming time is 30 minutes. The amount of micron spherical activated carbon added in step (3) is 15 grams, and the rolling ball forming time is 10 minutes. The concentration of propylene oxide in step (4) is 4.5%, and the solution amount is 730 grams. During the hydrothermal treatment, first seal and treat it at 95°C for 1.5 hours, then seal and treat it at 155°C for 15 hours to obtain an alumina carrier A3. The properties of the carrier are shown in Table 1. Example 4

[0048] The same as example 1, except that the step (1) rolling ball forming time is 30 min. The step (2) microspherical activated carbon is added in an amount of 10.5 g, and the rolling ball forming time is 35 min. The step (3) microspherical activated carbon is added in an amount of 17 g, and the rolling ball forming time is 15 min. The step (4) propylene oxide concentration is 7.7%, and the solution amount is 430 g. During the hydrothermal treatment, first, it is treated at 65℃ for 3.5 hours, and then the temperature is increased to 125℃, and the treatment time is 18 hours. The alumina carrier A4 is prepared, and the carrier properties are shown in Table 1.

[0049] Comparative example 1

[0050] The same as example 1, except that the step (4) propylene oxide solution is replaced by an ammonia solution with the same mass concentration. The comparative alumina carrier A5 is prepared, and the carrier properties are shown in Table 1.

[0051] Comparative example 2

[0052] The same as example 1, except that the step (4) propylene oxide solution is replaced by an ethylene oxide solution with the same concentration. The comparative alumina carrier A6 is prepared, and the carrier properties are shown in Table 1. The scanning electron microscope image of the outer surface of the carrier is shown in Figure 5 , and the cross-sectional scanning electron microscope image is shown in Figure 6 .

[0053] Comparative example 3

[0054] The same as example 1, except that the step (4) propylene oxide concentration is 0.8%. The comparative alumina carrier A7 is prepared, and the carrier properties are shown in Table 1.

[0055] Comparative example 4

[0056] The same as example 1, except that the step (4) hydrothermal treatment is replaced by one-step hydrothermal treatment at a temperature of 65℃. The comparative alumina carrier A8 is prepared, and the carrier properties are shown in Table 1.

[0057] Table 1: Properties of alumina carriers

[0058] Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Carrier S1 S2 S3 S4 S5 S6 S7 S8 Specific surface area, m 2 / g]] 275 260 280 295 280 260 277 281 Pore volume, mL / g 0.89 0.91 0.87 0.93 0.84 0.81 0.85 0.87 10-30 nm pore content, % 58.9 60.1 51.3 62.7 39.9 38.1 41.2 43.3 Core thickness, r 0.35 0.46 0.42 0.32 0.36 0.37 0.35 0.36 First layer thickness outside the core, r 0.37 0.34 0.4 0.45 0.36 0.37 0.38 0.38 Spherical cavity area ratio of the first layer outside the core, % 12.5 15.2 17.1 16.3 13.6 12.7 13.2 12.9 Cavity filling rate of the first layer outside the core, % 46.3 47.1 45.8 50.2 — — — — Second layer thickness outside the core, r 0.28 0.20 0.18 0.23 0.28 0.26 0.27 0.26 Spherical cavity area ratio of the second layer outside the core, % 32.6 38.2 26.8 28.7 32.9 31.8 33.1 33.3 Cavity filling rate of the second layer outside the core, % 42.1 41.9 42.2 44.5 — — — — Coverage of flaky particles on the outer surface of the second layer outside the core, % 91.5 95.3 93.7 96.5 — — — —

[0059] From the data in Table 1 and Figures 1-6 It can be seen that, compared with the comparative examples, the alumina carrier prepared by the method of the present application has an open surface channel, and a large number of through channels are formed by the accumulation of flaky particles in the micron-level channels.

Claims

1. A spherically hollow-cored alumina carrier, characterized by: The alumina carrier is a spherical carrier, including a core, a first layer outside the core, a second layer outside the core and a shell layer from the core to the outer surface, and the distance from the core to the outer surface of the second layer outside the core is r; The thickness of the core is 0.3r-0.5r, and the core is a spherical alumina crystal grain aggregate, and the size of the spherical alumina crystal grain is 80-260nm; The thickness of the first layer outside the core is 0.1r-0.5r, and the layer is a spherical alumina crystal grain and a flaky alumina crystal grain aggregate, wherein the flaky alumina crystal grains are in-situ grown in the spherical cavity formed by the spherical alumina crystal grains, the size of the spherical cavity is 1-5μm, the size of the flaky alumina crystal grain is 100nm-600nm, the filling rate of the spherical cavity is 40%-80%, and the area ratio of the spherical cavity is 10%-30%; The thickness of the second layer outside the core is 0.1r-0.5r, and the layer is a spherical alumina crystal grain and a flaky alumina crystal grain aggregate, wherein the flaky alumina crystal grains are in-situ grown in the spherical cavity formed by the spherical alumina crystal grains, the size of the spherical cavity is 5-10μm, the size of the flaky alumina crystal grain is 100nm-600nm, the filling rate of the spherical cavity is 40%-80%, and the area ratio of the spherical cavity is 25%-50%; The shell layer is a flaky alumina crystal grain in-situ grown on the outer surface of the second layer outside the core, the size of the flaky alumina crystal grain is 100nm-600nm, and the coverage rate is 85%-100%; the flaky alumina crystal grains in the shell layer are stacked to form an open channel with a diameter of 40-300nm; the flaky alumina crystal grains in the spherical cavities of the first layer and the second layer outside the core are stacked to form a through hole with a diameter of 50-100nm; The preparation method of the alumina carrier containing a spherical cavity comprises the following steps: (1) mixing pseudo-boehmite and a physical pore-expanding agent, and rolling to form a spherical precursor S0; (2) mixing pseudo-boehmite and a first spherical activated carbon to obtain a material W1, mixing the material W1 with the spherical precursor S0, and rolling to form a spherical precursor S1; (3) mixing pseudo-boehmite and a second spherical activated carbon to obtain a material W2, mixing the material W2 with the spherical precursor S1, rolling, drying and calcining to obtain a precursor S2; (4) immersing the precursor S2 in an aqueous propylene oxide solution for sealed heat treatment, and then performing solid-liquid separation on the treated material, and drying and calcining the solid material to obtain an alumina carrier containing a spherical cavity; in step (4), the mass percentage concentration of the aqueous propylene oxide solution is 2.5%-12%, and the mass ratio of the aqueous propylene oxide solution to the alumina carrier precursor is 3:1-10:1; in step (4), the sealed heat treatment process comprises the following steps: first, low-temperature sealed heat treatment at 60-100℃ for 1-4 hours, and then sealed heat treatment at 110-180℃ for 14-20 hours.

2. The alumina support of claim 1, wherein: The specific surface area of the alumina support is 200-350 m 2 / g, and the pore volume is 0.6-1.2 mL / g.

3. A process for the preparation of a spherically hollow cavitated alumina support according to claim 1 or 2, characterized in that It comprises the following contents: (1) mixing pseudo-boehmite with a physical pore-expanding agent, and ball-rolling to form a spherical precursor S0; (2) mixing pseudo-boehmite with a first spherical activated carbon to obtain a material W1, mixing the material W1 with the spherical precursor S0, and ball-rolling to form a spherical precursor S1; (3) mixing pseudo-boehmite with a second spherical activated carbon to obtain a material W2, mixing the material W2 with the spherical precursor S1, and ball-rolling, then drying and calcining to obtain a precursor S2; (4) sealing and heat-treating the precursor S2 in an aqueous propylene oxide solution, and after the treatment, the material is subjected to solid-liquid separation, and the solid-phase material is dried and calcined to obtain an alumina carrier containing spherical cavities.

4. The method of claim 3, wherein: The pseudo-boehmite particles in steps (1), (2) and (3) are in a granular form, and the average pore diameter of the pseudo-boehmite is greater than 10 nm.

5. The method of claim 3, wherein: The ball-rolling is performed in a rotating disc forming machine, and the rotating operation conditions of the rotating disc forming machine are as follows: the inclination angle of the rotating disc is 40-70º, and the rotating speed of the rotating disc is 10-30 rpm; the forming time of the material in the rotating disc is 5-120 min; and an aqueous solution containing a glue solvent is sprayed into the material during the forming process; the aqueous solution containing the glue solvent is one or more of aqueous solutions of nitric acid, phosphoric acid, oxalic acid and acetic acid, and the mass concentration of the solution is 1%-3%.

6. The method of claim 3, wherein: The physical pore-expanding agent in step (1) is activated carbon, wood chips, carbon black, urea, propylene glycol glycerol, triethylene glycol, melamine, polyethylene glycol, polyethylene oxide, methyl cellulose, polyethylene oxide, polyacrylamide, starch, and the mass ratio of the physical pore-expanding agent to the pseudo-boehmite is 1:100-3:

100.

7. The method of claim 3, wherein: The first spherical activated carbon in step (2) has a diameter of 1-5 microns, and the mass ratio of the first spherical activated carbon to the pseudo-boehmite is 1:6.7-1:12.

5.

8. The method of claim 3, wherein: The second spherical activated carbon in step (3) has a diameter of 5-10 microns, and the mass ratio of the second spherical activated carbon to the pseudo-boehmite is 1:4-1:6.

7.

9. The method of claim 3, wherein: The drying temperature in step (3) is 100-160ºC, and the drying time is 2-8 hours; the calcination is performed in an oxygen atmosphere, the calcination temperature is 450-600ºC, and the calcination time is 4-6 hours.

10. The method of claim 3, wherein: The aqueous propylene oxide solution in step (4) has a mass percentage concentration of 2.5%-12%, and the mass ratio of the aqueous propylene oxide solution to the alumina carrier precursor is 3:1-10:

1.

11. The method of claim 3, wherein: The sealing and heat-treating process in step (4) is as follows: first, low-temperature sealing and heat-treating at 60-100ºC for 1-4 hours, and then sealing and heat-treating at 110-180ºC for 14-20 hours.

12. The method of claim 3, wherein: The drying temperature in step (4) is 100-160ºC, the drying time is 2-8 hours, the calcination temperature is 500-750ºC, and the calcination time is 4-6 hours, and the calcination is performed in an oxygen-containing atmosphere.

13. Use of the alumina carrier containing spherical cavities according to claim 1 or 2 in the field of heavy oil hydrogenation.

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