Alumina support of core-shell structure and method for preparing the same

Abstract

The application discloses an alumina carrier with a core-shell structure and a preparation method thereof. The alumina carrier is a three-layer spherical structure of "eggshell-egg white-egg yolk", the "eggshell" layer is a flaky alumina grain aggregate, and the "egg white" and "egg yolk" layers are mixed phases of the flaky alumina grain aggregate and the granular alumina aggregate. The preparation method of the alumina carrier is as follows: (1) preparing flaky pseudo-boehmite P1; (2) mixing pseudo-boehmite P2 and P1 to obtain a mixture H1, and performing ball rolling forming to obtain a spherical precursor S1; (3) mixing P2 and P1 to obtain a mixture H2, and then mixing S1 and H2 to perform ball rolling forming to obtain a spherical precursor S2; and (4) mixing P1 and S2, performing ball rolling forming, and then drying and calcining to obtain the alumina carrier. The alumina carrier has a gradient distribution of macropore content and pore size in the "eggshell-egg white-egg yolk" structure, and the alumina carrier is suitable for a high-metal-content heavy residual oil hydroprocessing process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of synthesis of alumina materials, and particularly relates to an alumina carrier with a core-shell structure and a preparation method thereof. BACKGROUND

[0002] At present, with the increasing of the heavy and poor quality of crude oil, oil refining enterprises are faced with the problem of processing and utilization of heavy and residual oil. Heavy and residual oil molecules have a complex three-dimensional structure. The space steric hindrance is often formed by the sulfur-containing aromatic side chain, which hinders the adsorption of sulfur atoms in five and six-membered rings by the active center of the catalyst. In the process of catalytic hydrogenation, heavy oil macromolecules are adsorbed and deposited on the surface or pore of the catalyst, which increases the internal diffusion resistance of the reaction and causes the apparent activity of the catalyst to decrease. At the same time, heavy and residual oil contains a large amount of coke precursors, which will generate coke and deposit in the pores under certain conditions, causing the active center of the catalyst to be poisoned. The internal diffusion of the catalyst becomes the control factor of the process of catalytic hydrogenation of heavy and residual oil, so the catalytic hydrogenation of heavy and residual oil requires a large-pore catalyst with a large pore size and pore volume to accommodate more carbon deposition, metal deposits and other substances, and to reduce the diffusion resistance encountered by macromolecules. The large pore size and pore volume of the catalyst mainly rely on the corresponding large-pore support.

[0003] Alumina is a commonly used catalyst carrier in the field of petroleum chemical industry. It has been widely used and has the largest amount of application due to its good mechanical stability, controllable specific surface area and pore structure, and low cost. However, the pore channel of the conventional alumina carrier is small. In order to meet the needs of heavy and residual oil hydrogenation treatment, the method of "expanding the pore" is usually used to improve the pore structure of the alumina carrier.

[0004] CN107913691A discloses an alumina carrier containing large pores and a preparation method thereof. First, pseudo-boehmite powder and sesbania powder are mixed uniformly in a kneader. Then, a butadiene-styrene rubber emulsion with a particle size of 10-500 nm is prepared, and an organic acid or an inorganic acid is added. Then, the acid solution containing the butadiene-styrene rubber emulsion is added to the pseudo-boehmite powder and sesbania powder and kneaded uniformly. After extruding, molding, drying and calcining, an alumina carrier containing large pores is obtained. The preparation process of the pore expander butadiene-styrene rubber emulsion is relatively complex. In addition, the surface and the inside of the carrier do not form a gradient pore channel, which is not conducive to the diffusion of residual oil reactant molecules to the inside.

[0005] 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 2The catalyst has a pore diameter of 13.0-18.0 nm, and the preparation method is to treat the carrier particles after molding and calcination with acid solutions with continuously increasing concentrations, which can make the average pore diameter of the final catalyst gradually increase from the center to the surface of the catalyst particles to a certain extent, but it is difficult to form larger pores on the surface of the carrier by this treatment. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides an alumina carrier with a core-shell structure and a preparation method thereof. The alumina carrier has a gradient distribution of macropore content and pore size in the form of an "eggshell-egg white-egg yolk" structure, and is suitable for heavy oil hydroprocessing with high metal (Ni, V) content.

[0007] The alumina carrier with a core-shell structure of the present application has a three-layer spherical structure of "eggshell-egg white-egg yolk", the "eggshell" layer is a flaky alumina grain aggregate, and the "egg white" and "egg yolk" layers are mixed phases of flaky alumina grain aggregates and granular alumina aggregates, wherein the mass ratio of flaky alumina grain aggregates to granular alumina aggregates in the "egg white" layer is 0.1:1-0.3:1, the mass ratio of flaky alumina grain aggregates to granular alumina aggregates in the "egg yolk" layer is 0.4:1-1.4:1, the thickness of the "eggshell" layer is 0.2r-0.5r, the thickness of the "egg white" layer is 0.3r-0.6r, and the thickness of the "egg yolk" layer is the balance, wherein r is the radius of the alumina carrier, i.e. the straight-line distance from the center of the sphere to the outer surface.

[0008] In the alumina carrier with a core-shell structure of the present application, the size of the flaky alumina grains is 100-800 nm, and the thickness is 25-80 nm; the grain size of the granular alumina grains is 20-100 nm.

[0009] The diameter of the alumina carrier with a core-shell structure of the present application is 2 mm-10 mm.

[0010] The specific surface area of the alumina carrier with a core-shell structure of the present application is 160-300 m 2 / g, the pore volume is 0.8-1.2 mL / g, the content of pores with a diameter of 10-20 nm accounts for 40%-60% of the total pore volume, the content of pores with a diameter of 50-100 nm accounts for 10%-20% of the total pore volume, and the content of pores with a diameter greater than 100 nm accounts for 8%-15% of the total pore volume.

[0011] The preparation method of the alumina carrier with a core-shell structure of the present application comprises the following contents:

[0012] (1) calcining aluminum nitrate, crushing and screening the calcined material, mixing the screened material with propylene oxide aqueous solution, and then performing hydrothermal treatment on the mixture, filtering, washing and drying the treated material to obtain flaky pseudo-boehmite P1;

[0013] (2) mixing pseudo-boehmite P2 with the flaky pseudo-boehmite P1 obtained in step (1) to obtain a mixture

[0014] H1, and then performing ball forming on the mixture H2 to obtain spherical precursor S1;

[0015] (3) mixing pseudo-boehmite P2 with the flaky pseudo-boehmite P1 obtained in step (1) to obtain a mixture

[0016] H2, and then mixing the spherical precursor S1 with the mixture H2 and performing ball forming to obtain spherical precursor S2;

[0017] (4) mixing the flaky pseudo-boehmite P1 with the spherical precursor S2, performing ball forming, and then drying and calcining to obtain an alumina carrier with core-shell structure.

[0018] In the method of the present application, the pseudo-boehmite P1 prepared in step (1) has the following properties: 1.0 < P1 ≤ 1.3, 1.1 < P2 ≤ 1.5, P1 = D(120) / D(031), and P2 = D(120) / D(020); D(120) represents the grain size of the crystal plane corresponding to the (120) peak in the XRD spectrum of the pseudo-boehmite crystal grains, D(120) is 75-105 Å; D(031) represents the grain size of the crystal plane corresponding to the (031) peak in the XRD spectrum of the pseudo-boehmite crystal grains, D(031) is 70-90 Å; D(020) represents the grain size of the crystal plane corresponding to the (020) peak in the XRD spectrum of the pseudo-boehmite crystal grains, D(020) is 60-70 Å; the 120 peak refers to the characteristic peak with 2θ of 25.5-29.9º in the XRD spectrum; the 031 peak refers to the characteristic peak with 2θ of 36.3-40.5º in the XRD spectrum; and the 020 peak refers to the characteristic peak with 2θ of 12.0-16.2º in the XRD spectrum, D = Kλ / (Bcosθ), K is the Scherrer constant, λ is the diffraction wavelength of the target material, B is the half-peak width of the diffraction peak, and θ is the diffraction angle.

[0019] In the method of the present application, the calcination temperature in step (1) is 450-650℃, and the calcination time is 4-8 hours.

[0020] In the method of the present application, the crushing particle size of the material in step (1) is greater than 100 mesh, preferably greater than 200 mesh.

[0021] In the method, the mass percentage concentration of the propylene oxide aqueous solution in step (1) is 2.5%-12%, preferably 4%-8%, and the mass ratio of the amount of the propylene oxide aqueous solution to the powder material is 3:1-10:1, preferably 4:1-8:1.

[0022] In the method, the hydrothermal treatment in step (1) is carried out in a sealed container, preferably an autoclave, the hydrothermal treatment temperature is 110-180℃, preferably 120-160℃, the treatment time is 4-8 hours, and the pressure in the sealed container during the hydrothermal treatment is autogenous pressure.

[0023] In the method, the drying temperature in step (1) is 100-160℃, and the drying time is 2-8 hours.

[0024] In the method, the pseudo-boehmite P2 particle morphology in step (2) is generally granular, which can be a commercially available product or a pseudo-boehmite prepared by an acid precipitation method, an alkali precipitation method, an alcohol aluminum hydrolysis method, etc., and preferably a pseudo-boehmite with a pore size greater than 10 nm.

[0025] In the method, the mass ratio of the flaky pseudo-boehmite P1 to the pseudo-boehmite P2 in step (2) is 1:9-1:4.

[0026] In the method, the ball forming in step (2) is carried out in a rotary table forming machine, the rotary table forming machine has a rotation operation condition that the inclination angle of the rotary table is 40-70º and the rotation speed of the rotary table is 10-30 rpm, and the forming time of the material in the rotary table is 10-120 min. The radius of the spherical precursor S1 is 0.2r-0.5r, where r is the radius of the final spherical aluminum oxide material, i.e. the straight-line distance from the center of the sphere to the outer surface. A water solution containing a glue solvent is sprayed into the material during the ball forming process; the water solution containing the glue solvent is one or a mixture of several of nitric acid, phosphoric acid, oxalic acid, and acetic acid aqueous solution, and the concentration of the solution is 1wt%-3wt%, preferably acetic acid aqueous solution.

[0027] In the method, the mass ratio of the flaky pseudo-boehmite P1 to the pseudo-boehmite P2 in step (3) is 3:2-3:7.

[0028] In the method, the rolling ball forming in step (3) is performed in a rotary table forming machine, and the rotary table forming machine has a rotation operation condition that the inclination angle of the rotary table is 40-70º and the rotation speed of the rotary table is 10-30 rpm; and the forming time of the material in the rotary table is 10-120 min. The radius of the spherical precursor S2 is 0.5r-0.8r, wherein r is the radius of the final spherical alumina material, i.e. the straight-line distance from the center of the sphere to the outer surface. A water solution containing a gelatinizing solvent is sprayed into the material during the rolling ball forming; the water solution containing the gelatinizing solvent is one or a mixture of several of water solutions of nitric acid, phosphoric acid, oxalic acid and acetic acid, and the concentration of the solution is 1wt%-3wt%, preferably the water solution of acetic acid.

[0029] In the method, the rolling ball forming in step (4) is performed in a rotary table forming machine, and the rotary table forming machine has a rotation operation condition that the inclination angle of the rotary table is 40-70º and the rotation speed of the rotary table is 10-30 rpm; and the forming time of the material in the rotary table is 10-60 min, and the diameter of the final sphere is adjusted according to requirements, generally being 5-10 mm. A water solution containing a gelatinizing solvent is sprayed into the material during the rolling ball forming; the water solution containing the gelatinizing solvent is one or a mixture of several of 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.

[0030] In the method, the drying time in step (4) is 1-8 hours, preferably 2-6 hours, and the drying temperature is 60℃-180℃, preferably 80℃-150℃; the calcination temperature is 350-800℃, preferably 500-650℃, and the calcination time is 2-6 hours, preferably 2-4 hours.

[0031] The core-shell structure alumina carrier of the application is suitable for the hydroprocessing process of heavy oil and residual oil, and is particularly suitable for the hydroprocessing process of heavy oil and residual oil with high metal (Ni, V) content.

[0032] The application also provides a hydroprocessing catalyst, which comprises the core-shell structure alumina carrier described above.

[0033] Compared with the prior art, the application has the following advantages:

[0034] The present application takes tabular pseudo-boehmite as raw material, controls the pore structure of the alumina carrier by regulating the content of the tabular pseudo-boehmite in different radial regions of the carrier, so that the prepared alumina carrier has a gradient distribution of macropore content and pore size distribution in the form of “eggshell-egg white-egg yolk”, that is, the surface layer is formed by the accumulation of tabular alumina to form larger pores, the middle layer has a high macropore content and a pore size, and the core layer has a smaller pore size. The pore structure is beneficial to the diffusion of macromolecular reactants into the carrier, and is particularly suitable for use as a carrier for heavy oil hydroprocessing catalysts with high metal (Ni, V) content. The hydroprocessing catalyst prepared by using the alumina as the carrier has larger surface pores, strong metal deposition resistance, and surface pores that are not easily blocked by metal and carbon deposition, which is beneficial to the diffusion of reactants into the catalyst, improves the reaction activity in the catalyst and improves the activity stability of the catalyst. The method for preparing tabular pseudo-boehmite has a simple process, the prepared pseudo-boehmite has a regular tabular grain structure, the pores formed by the accumulation of tabular grains are open, the content of pores with a size of 50-150 nm is high, and the tabular grains have good strength, so that the pores formed by the accumulation of tabular grains are not easily collapsed during the forming process, the pores formed by the accumulation of tabular grains are well preserved in the carrier, and the macropore content in the carrier is improved. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is an SEM image of the tabular pseudo-boehmite P1-1 prepared in Example 1.

[0036] Figure 2 is an XRD spectrum of the tabular pseudo-boehmite P1-1 prepared in Example 1.

[0037] Figure 3 is an SEM image of the material P1-6 prepared in Comparative Example 3. EMBODIMENT

[0038] The technical solutions and technical effects of the present application will be further illustrated below in combination with examples, but are not limited to the following examples. In the present application, wt% represents mass fraction.

[0039] BET method: N2 physical adsorption-desorption is used to characterize the pore structure of the carrier in the examples and comparative examples, and the specific operation is as follows: an ASAP-2420 type N2 physical adsorption-desorption instrument is used to characterize the pore structure of the sample. A small amount of sample is vacuum treated at 300℃ for 3-4 hours, and finally the product is placed in liquid nitrogen at low temperature (-200℃) for nitrogen adsorption-desorption test. The specific surface area is obtained according to the BET equation, and the distribution rate of pore volume and pore diameter below 30 nm is obtained according to the BJH model.

[0040] The scanning electron microscope is used to characterize the microstructure of the alumina carrier, and the specific operation is as follows: a JSM-7500F scanning electron microscope is used to characterize the microstructure of the carrier, the acceleration voltage is 5KV, the acceleration current is 20µA, and the working distance is 8mm.

[0041] X-ray diffraction (XRD) analysis was performed on a D / max-2500 full-automatic rotating target X-ray diffractometer produced by Japan Rigaku Corporation. A Cu target, a Kα radiation source, a graphite monochromator, a tube voltage of 40 kV, and a tube current of 80 mA were used.

[0042] Mercury intrusion method: The pore diameter distribution of the carriers in the examples and the comparative examples was characterized by using a mercury intrusion instrument. The pore distribution of the sample was characterized by using an American Micromeritics AutoPore 9500 full-automatic mercury intrusion instrument. After the sample was dried and weighed, it was loaded into an expansion gauge, and was degassed for 30 minutes under the vacuum condition given by the instrument, and was loaded with mercury. Subsequently, the expansion gauge was placed into a high-pressure kettle, and was exhausted. Then, the pressure was increased and the pressure was decreased. The mercury contact angle was 130°, and the mercury interfacial tension was 0.485 N·cm. -1 The distribution rate of the pore diameter of 100 nm or more was measured by the mercury intrusion method.

[0043] Most probable pore diameter determination: the pore diameter differential distribution curve was obtained by taking the pore diameter of the material as the abscissa and the change rate of the pore volume with the pore diameter as the ordinate, and the peak value in the curve was the most probable pore diameter.

[0044] In the present application, the determination method of the average pore diameter of the different layers from the outer surface layer to the center core of the catalyst particles, i.e., the "eggshell-egg white-egg yolk" different layers: first, the pore volume, the specific surface area, and the average pore diameter of the sample were determined by using the low-temperature nitrogen adsorption method (BET), then a certain amount of sample was placed in a catalyst attrition instrument, and the sample was ground, and a certain amount of quartz sand was added to increase the grinding speed. When the particle size of the sample is reduced to a certain extent after grinding, the weight loss of the sample is determined, and the pore structure is determined again. According to the relationship that the total pore volume and the specific surface area of the sample are equal to the sum of each part, the pore volume and the specific surface area of the ground part can be calculated, and 20-80 samples are determined to calculate the average pore diameter. Thus, the average pore diameters of the different layers from the outer surface layer to the center core are determined.

[0045] Preparation of the sheet-like pseudo-boehmite material P1: Example 1

[0046] (1) A proper amount of aluminum nitrate was placed in a crucible and was calcined at 500°C for 5.5 hours. The calcined material was ground and was sieved to obtain particles of 200 mesh or more;

[0047] (2) 100 grams of the sieved particles were weighed, and a propylene oxide aqueous solution with a mass concentration of 5.5% was added;

[0048] (2) 100 grams of the sieved particles were weighed, and a propylene oxide aqueous solution with a mass concentration of 5.5% was added;

[0049] 610 g, magnetic stirring for 30 minutes, then the mixture was transferred into an autoclave and sealed, heated at 145°C for 5.3 hours, after cooling, the solid was filtered, washed, dried at 120°C for 4 hours to obtain the pseudoboehmite P1-1. The microstructure of the sample was observed by scanning electron microscopy to be a sheet-like grain accumulation, the sheet-like grain size was 120-650 nm, and the thickness was 25-55 nm. The scanning electron microscopy image is shown in Figure 1 , the XRD spectrum is shown in Figure 2 , P1=1.07, P2=1.45, D(120) was 90 A, D(031) was 84 A, and D(020) was 62 A. Example 2

[0050] The same as Example 1, except that in step (1), the calcination temperature of aluminum nitrate was 550°C, and the calcination time was 6.5 hours. In step (2), the concentration of propylene oxide was 6.3%, the solution amount was 530 g, the hydrothermal treatment temperature was 130°C, and the treatment time was 6.0 hours. The pseudoboehmite P1-2 was prepared. The microstructure of the sample was observed by scanning electron microscopy to be a sheet-like grain accumulation, the sheet-like grain size was 140-680 nm, and the thickness was 30-65 nm. P1=1.10, P2=1.41, D(120) was 87 A, D(031) was 79 A, and D(020) was 62 A. Example 3

[0051] The same as Example 1, except that in step (1), the calcination temperature of aluminum nitrate was 450°C, and the calcination time was 7.5 hours. In step (2), the concentration of propylene oxide was 7.7%, the solution amount was 410 g, the hydrothermal treatment temperature was 125°C, and the treatment time was 7.5 hours. The pseudoboehmite P1-3 was prepared. The microstructure of the sample was observed by scanning electron microscopy to be a sheet-like grain accumulation, the sheet-like grain size was 135-700 nm, and the thickness was 30-60 nm. P1=1.14, P2=1.31, D(120) was 87 A, D(031) was 76 A, and D(020) was 66 A. Example 4

[0052] The same as Example 1, except that in step (1), the calcination temperature of aluminum nitrate was 650°C, and the calcination time was 4.5 hours. In step (2), the concentration of propylene oxide was 4.2%, the solution amount was 740 g, the hydrothermal treatment temperature was 155°C, and the treatment time was 4 hours. The pseudoboehmite P1-4 was prepared. The microstructure of the sample was observed by scanning electron microscopy to be a sheet-like grain accumulation, the sheet-like grain size was 125-650 nm, and the thickness was 25-65 nm. P1=1.18, P2=1.36, D(120) was 87 A, D(031) was 74 A, and D(020) was 64 A.

[0053] Comparative Example 1

[0054] Same as Example 1, except that in step (2) propylene oxide is replaced with the same amount of ethylene oxide. After hydrothermal treatment, no lamellar grains were observed in the microstructure of material P1-5. P1=1.06, P2=1.49, D(120) is 61Å, D(031) is 58Å, and D(020) is 41Å.

[0055] Comparative Example 2

[0056] Same as Example 1, except that aluminum nitrate is replaced with aluminum sulfate in step (1). After hydrothermal treatment, the solid material particles dissolve and are not separated to obtain the product.

[0057] Comparative Example 3

[0058] Same as Example 1, except that aluminum nitrate in step (1) is replaced with aluminum chloride. After hydrothermal treatment, no lamellar grains were observed in the microstructure of material P1-6. Scanning electron micrographs are shown below. Figure 3 P1=1.16, P2=1.63, D(120) is 81Å, ​​D(031) is 70Å, D(020) is 50Å.

[0059] Preparation of core-shell structured alumina materials: Example 5

[0060] Weigh 15 grams of the flaky pseudoboehmite P1-1 prepared in Example 1 and 100 grams of pseudoboehmite.

[0061] Alumina P2 (self-made by aluminum sulfate-sodium aluminate method, most probable pore size 12.5nm) was mixed evenly and then placed in a rotary molding machine for thorough mixing. The tilt angle of the rotary table was adjusted to 50º and the rotation speed was 15rpm. A 1% acetic acid aqueous solution was sprayed onto the material in the rotary table through a sprayer. After mixing and contact, the material was molded in the rotary table for 30 minutes to obtain a spherical precursor S1 with a diameter of 2.0-3.0mm.

[0062] (2) Weigh 100g of the flake-shaped boehmite P1-1 and 125g of the boehmite P2 prepared in Example 1. Mix the above materials evenly. After mixing, place the materials and the spherical precursor S1 prepared in step (1) into a turntable molding machine and mix them thoroughly. Adjust the tilt angle of the turntable to 45º and the rotation speed of the turntable to 12rpm. Spray a 1.2% acetic acid aqueous solution onto the materials in the turntable through a sprayer. After mixing and contact, the molding time of the materials in the turntable is 25min, and a spherical precursor S2 with a diameter of 4-5mm is obtained.

[0063] (3) The tabular pseudoboehmite P1-1 prepared in Example 1 and the spherical precursor S2 prepared in step (2) were mixed thoroughly in a rotary table forming machine. The inclination angle of the rotary table was adjusted to 40°, and the rotary speed of the rotary table was 10 rpm. An aqueous solution of acetic acid with a mass concentration of 1.3% was sprayed onto the material in the rotary table through a sprayer. After mixing and contacting, the material was formed in the rotary table for 20 min. Spherical material with a diameter of 6-8 mm was obtained. The spherical material was dried at 120°C for 4 h and then calcined at 650°C for 4 h to obtain a spherical alumina carrier S-1 with a core-shell structure. The properties of the carrier are shown in Table 1. Example 6

[0064] The same as Example 5, except that the tabular pseudoboehmite P1-1 in steps (1), (2) and (3) was replaced by tabular pseudoboehmite P1-2. The amount of the pseudoboehmite P2 added in step (1) was 70 g, and the amount of the pseudoboehmite P2 added in step (2) was 150 g. A spherical alumina carrier S-2 with a core-shell structure was obtained. The properties of the carrier are shown in Table 1. Example 7

[0065] The same as Example 5, except that the tabular pseudoboehmite P1-1 in steps (1), (2) and (3) was replaced by tabular pseudoboehmite P1-3. The amount of the pseudoboehmite P2 added in step (1) was 82 g, and the amount of the pseudoboehmite P2 added in step (2) was 82 g. A spherical alumina carrier S-3 with a core-shell structure was obtained. The properties of the carrier are shown in Table 1. Example 8

[0066] The same as Example 5, except that the tabular pseudoboehmite P1-1 in steps (1), (2) and (3) was replaced by tabular pseudoboehmite P1-4. The amount of the pseudoboehmite P2 added in step (1) was 62 g, and the amount of the pseudoboehmite P2 added in step (2) was 185 g. A spherical alumina carrier S-4 with a core-shell structure was obtained. The properties of the carrier are shown in Table 1.

[0067] Comparative Example 4

[0068] The same as Example 5, except that the tabular pseudoboehmite P1-1 in steps (1), (2) and (3) was replaced by the material P1-5 prepared in Comparative Example 1. A comparative spherical alumina carrier S-5 was prepared. The properties of the carrier are shown in Table 1.

[0069] Comparative Example 5

[0070] The same as Example 5, except that the tabular pseudoboehmite P1-1 in steps (1), (2) and (3) was replaced by the material P1-6 prepared in Comparative Example 3. A comparative spherical alumina carrier S-6 was prepared. The properties of the carrier are shown in Table 1.

[0071] Table 1 Properties of Alumina Carriers

[0072] Example 5 Example 6 Example 7 Example 8 Comparative Example 4 Comparative Example 5 Support S-1 S-2 S-3 S-4 S-5 S-6 Specific surface area, m 2 / g]] 187 206 172 220 163 168 Pore volume, mL / g 0.93 0.91 0.89 0.94 0.76 0.78 10-20 nm pore content, v% 47.3 49.6 44.2 53.1 60.1 62.4 50-100 nm pore content, v% 16.2 14.1 18.6 12.5 7.1 4.9 Pore content greater than 100 nm, v% 8.7 8.3 9.2 8.9 2.1 2.4 "Yolk" layer thickness, r 0.30 0.40 0.30 0.45 — — "Albumin" layer thickness, r 0.45 0.40 0.45 0.35 — — "Shell" layer thickness, r 0.25 0.20 0.25 0.20 — —

[0073] From the data in Table 1, it can be seen that the alumina carrier prepared by the method of the present application using the flaky pseudo-boehmite as raw material has higher content of pores of 50-100 nm and greater than 100 nm, which indicates that the pores formed by the accumulation of flaky pseudo-boehmite grains help to increase the content of large pores of the carrier and adjust the pore structure. The alumina carrier prepared by the comparative examples has lower content of pores of 50-100 nm and greater than 100 nm. Example 9

[0074] 50 grams of the alumina carrier prepared in Examples 5-8 and Comparative Examples 4-5 were respectively saturatedly impregnated with a Mo-Ni-P impregnation solution having a molybdenum oxide concentration of 9.7 g / 100 mL and a nickel oxide concentration of 2.4 g / 100 mL, and the impregnated materials were dried at 120°C for 6 hours, and the dried materials were calcined at 450°C in air for 6 hours, to prepare hydrogen demetallization catalysts Cat-1, Cat-2, Cat-3, Cat-4 and comparative hydrogen demetallization catalysts Cat-5, Cat-6.

[0075] The catalytic properties of the catalysts Cat-1-Cat-6 were evaluated on a fixed-bed residue hydrogenation reaction device using a certain vacuum residue as raw material, and the metal (Ni+V) content of the raw material oil was 232 μg / g. The reaction conditions were as follows: the reaction temperature was 385°C, the hydrogen partial pressure was 13.5 MPa, the liquid hourly space velocity was 0.45 h-1, and the hydrogen / oil volume ratio was 780. After 1000 hours of reaction, the content of each impurity in the generated oil was determined, the impurity removal rate was calculated, and the evaluation results are shown in Table 2. -1

[0076] Table 2 Comparison of hydrogenation properties of catalysts

[0077] Catalyst number Cat-1 Cat-2 Cat-3 Cat-4 Cat-5 Cat-6 Relative demetallization, % 137 129 131 135 100 96

[0078] As can be seen from the data in Table 2, the hydrogen demetallization catalyst prepared using the alumina of the present application as carrier is particularly suitable for use as a heavy residue hydroprocessing catalyst carrier with high content of metal (Ni+V) impurities, and the hydrogen demetallization catalyst prepared using the alumina as carrier has higher hydrogen demetallization activity.​

Claims

1. A core-shell structured alumina support, characterized by: The carrier is a "eggshell-egg white-egg yolk" three-layer spherical structure, the "eggshell" layer is a flaky alumina grain aggregate, the "egg white" and "egg yolk" layers are mixed phases of flaky alumina grain aggregates and granular alumina aggregates, the mass ratio of flaky alumina grain aggregates to granular alumina aggregates in the "egg white" layer is 0.1:1-0.3:1, the mass ratio of flaky alumina grain aggregates to granular alumina aggregates in the "egg yolk" layer is 0.4:1-1.4:1, the thickness of the "eggshell" layer is 0.2r-0.5r, the thickness of the "egg white" layer is 0.3r-0.6r, and the thickness of the "egg yolk" layer is the remainder, wherein r is the radius of the alumina carrier, i.e. the straight-line distance from the center of the sphere to the outer surface; the specific surface area of the alumina carrier is 160-300 m 2 / g, the pore volume is 0.8-1.2 mL / g, the content of channels with a diameter of 10-20 nm accounts for 40%-60% of the total pore volume, the content of channels with a diameter of 50-100 nm accounts for 10%-20% of the total pore volume, and the content of channels with a diameter greater than 100 nm accounts for 8%-15% of the total pore volume; the preparation method of the alumina carrier with a core-shell structure comprises the following steps: (1) calcining aluminum nitrate, crushing and screening the calcined material, mixing the screened material with an aqueous propylene oxide solution, and then performing hydrothermal treatment on the mixture; filtering, washing, and drying the treated material to obtain flaky pseudo-boehmite P1; (2) mixing pseudo-boehmite P2 with the flaky pseudo-boehmite P1 obtained in step (1) to obtain a mixture H1, and performing spherical rolling on the mixture to obtain a spherical precursor S1; (3) mixing pseudo-boehmite P2 with the flaky pseudo-boehmite P1 obtained in step (1) to obtain a mixture H2, and then mixing the spherical precursor S1 with the mixture H2 and performing spherical rolling to obtain a spherical precursor S2; (4) mixing the flaky pseudo-boehmite P1 with the spherical precursor S2, performing spherical rolling, and then drying and calcining to obtain an alumina carrier with a core-shell structure; in step (1), 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 powder material is 3:1-10:1; in step (1), the hydrothermal treatment is performed in a sealed container, the hydrothermal treatment temperature is 110-180°C, the treatment time is 4-8 hours, and the pressure in the sealed container during the hydrothermal treatment is autogenous pressure.

2. The core-shell structured alumina support according to claim 1, characterized in that: The flaky alumina has a grain size of 100-800 nm and a thickness of 25-80 nm; the granular alumina has a grain size of 20-100 nm.

3. The core-shell structured alumina support of claim 1, wherein: The core-shell structure alumina carrier has a diameter of 2 mm-10 mm.

4. A method for preparing the core-shell structure alumina carrier according to any one of claims 1-3, comprising the following steps: (1) calcining aluminum nitrate, crushing and sieving the calcined material, mixing the sieved material with an aqueous propylene oxide solution, and then performing hydrothermal treatment, and filtering, washing and drying the treated material to obtain flaky pseudo-boehmite P1; (2) mixing pseudo-boehmite P2 with the flaky pseudo-boehmite P1 of step (1) to obtain a mixture H1, and performing ball rolling to obtain spherical precursor S1; (3) mixing pseudo-boehmite P2 with the flaky pseudo-boehmite P1 of step (1) to obtain a mixture H2, and mixing the spherical precursor S1 with the mixture H2 and continuing the ball rolling to obtain spherical precursor S2; and (4) mixing the flaky pseudo-boehmite P1 with the spherical precursor S2, performing ball rolling, and then drying and calcining to obtain the core-shell structure alumina carrier.

5. The method of claim 4, wherein: The pseudo-boehmite P1 prepared in step (1) has the following properties: 1.0 6. The method of claim 4, wherein: The calcination temperature of step (1) is 450-650°C, and the calcination time is 4-8 hours.

7. The method of claim 4, wherein: The crushed particle size of the material of step (1) is greater than 100 mesh.

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

1.

9. The method of claim 4, wherein: The drying temperature of step (1) is 100-160°C, and the drying time is 2-8 hours.

10. The method of claim 4, wherein: The pseudo-boehmite P2 of step (2) has a granular particle morphology, and the pseudo-boehmite has a pore size greater than 10 nm.

11. The method of claim 4, wherein: The mass ratio of the flaky pseudo-boehmite P1 to the pseudo-boehmite P2 of step (2) is 1:9-1:

4.

12. The method of claim 4, wherein: The rolling ball forming of step (2) is carried out in a rotary table forming machine, and the rotary table forming machine has the following rotation operation conditions: the inclination angle of the rotary table is 40-70º, the rotation speed of the rotary table is 10-30 rpm; the forming time of the material in the rotary table is 10-120 min; and the radius of the spherical precursor S1 is 0.2r-0.5r, wherein r is the radius of the final spherical alumina material, i.e. the straight-line distance from the center of the sphere to the outer surface.

13. The method of claim 4, wherein: The mass ratio of the sheet-like pseudo-boehmite P1 to the pseudo-boehmite P2 in step (3) is 3:2-3:

7.

14. The method of claim 4, wherein: The rolling ball forming of step (3) is carried out in a rotary table forming machine, and the rotary table forming machine has the following rotation operation conditions: the inclination angle of the rotary table is 40-70º, the rotation speed of the rotary table is 10-30 rpm; the forming time of the material in the rotary table is 10-120 min; and the radius of the spherical precursor S2 is 0.5r-0.8r, wherein r is the radius of the final spherical alumina material, i.e. the straight-line distance from the center of the sphere to the outer surface.

15. The method of claim 4, wherein: The rolling ball forming of step (4) is carried out in a rotary table forming machine, and the rotary table forming machine has the following rotation operation conditions: the inclination angle of the rotary table is 40-70º, the rotation speed of the rotary table is 10-30 rpm; the forming time of the material in the rotary table is 10-60 min; and the diameter of the final sphere is 5-10 mm.

16. The method of claim 4, wherein: The drying time of step (4) is 1-8 hours, and the drying temperature is 60-180ºC; the calcination temperature is 350-800ºC, and the calcination time is 2-6 hours.

17. Use of the core-shell structured alumina carrier according to any one of claims 1-3 in a heavy oil and residual oil hydroprocessing process.

18. A hydroprocessing catalyst characterized by: The catalyst comprises the core-shell structured alumina carrier according to any one of claims 1-3.

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