A heavy oil hydrogenation protectant and a preparation method thereof

Abstract

The application discloses a heavy oil hydrogenation protective agent and a preparation method thereof. The protective agent comprises an alumina carrier containing spherical cavities, MoO3 and NiO. The outer surface and the spherical cavities of the alumina carrier containing micro-sized spherical cavities are in-situ grown with flaky alumina grains. The MoO3 content at the micro-sized spherical cavities is 9.0wt%-12.5wt%, and the NiO content is 2.3wt%-3.0wt%. The MoO3 and NiO content on the surface of the protective agent is lower than that in the interior. The preparation method is as follows: (1) mixing molybdenum-nickel modified activated carbon, pseudo-boehmite and water to obtain a slurry, performing solid-liquid separation on the slurry, kneading and forming, drying and calcining to prepare a precursor containing micro-sized cavities; (2) immersing the precursor containing micro-sized cavities into an epoxy propane aqueous solution to perform low-temperature and high-temperature heat treatment, performing solid-liquid separation, drying and calcining the solid-phase material to obtain an alumina carrier; and (3) immersing the alumina carrier into high-concentration and low-concentration molybdenum-nickel impregnation solutions in sequence to obtain the heavy oil hydrogenation protective agent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst preparation, and particularly relates to a heavy oil hydrogenation guard and a preparation method thereof. BACKGROUND

[0002] In the oil refining, petrochemical, chemical and other industries, especially in the fixed bed hydrogenation reactor for treating feedstock oil and gas containing more impurities such as residual oil and coal tar, the main solid deposits in the feedstock are carbon deposits and metal sulfides, part of which enters the pores of the catalyst, and the other part deposits on the outer surface of the catalyst particles. After long-term accumulation, the pressure drop of the catalyst bed gradually increases, eventually blocking the reactor. Therefore, in order to prolong the operation cycle of the industrial device and the service life of the main catalyst, a certain height of hydrogenation guard must be loaded on the main catalyst bed in the fixed bed hydrogenation reactor. The basic guiding ideology for developing new protective agents is to effectively filter, adsorb and remove various impurities such as carbon deposits, metal impurities and other impurities in the feedstock and reaction products to the greatest extent, to protect the main catalyst in the lower bed from local plugging and rapid increase in pressure difference, and ultimately to prolong the operation cycle of the industrial device.

[0003] CN106622307A discloses a hydrogenation guard, a preparation method and application thereof. The guard contains an active metal component and a modified hydrogenation catalyst carrier. The modified hydrogenation catalyst carrier is repeatedly impregnated and dried in sequence after hydrothermal treatment, and the last obtained dried product is calcined. In each impregnation process, the impregnation solution contains the same or different acidic additive compounds. The number of repetitions n is greater than or equal to 2, and when n is greater than or equal to 3, the temperature of each impregnation after drying is 20-150℃ higher than that of the adjacent previous impregnation after drying, and the time of each impregnation after drying is 1-10 hours longer than that of the adjacent previous impregnation after drying. This method can obtain a modified hydrogenation catalyst carrier with layered distribution of acidic additives, but the pore opening of the carrier surface is poor, which is not conducive to the diffusion of large molecular reactants in residual oil.

[0004] CN111821990A discloses a residue hydrogenation protectant carrier, a catalyst and a preparation method thereof, the carrier is a modified alumina-based carrier, the modified alumina-based carrier contains a modified element and a first hydrogenation active metal component; the modified alumina-based carrier comprises a main modified alumina and a rod-shaped modified alumina, the main modified alumina is alumina with micron-level channels, and at least part of the rod-shaped modified alumina is distributed on the outer surface of the main modified alumina and in the micron-level channels with a pore diameter D of 5-10 microns; the modified element is vanadium, and the first hydrogenation active metal component is molybdenum. The alumina carrier prepared by the method has better channel connectivity, but the bonding strength of the rod-shaped alumina grown on the surface and the main alumina needs to be further improved. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a heavy oil hydrogenation protectant and a preparation method thereof, the active metal distribution of the protectant cooperates with the carrier structure, effectively improving the ability of the hydrogenation protectant to remove Ca, Fe and Ni, V metal impurities in the heavy oil hydrogenation treatment process.

[0006] The heavy oil hydrogenation protectant of the present application comprises an alumina carrier containing spherical cavities, MoO3 and NiO; the outer surface and the spherical cavities of the alumina carrier containing micron-level spherical cavities have in-situ grown flaky alumina grains; the MoO3 content at the micron-level spherical cavities is 9.0wt%-12.5wt%, and the NiO content is 2.3wt%-3.0wt%;

[0007] In the heavy oil hydrogenation protectant of the present application, the MoO3 and NiO content on the surface of the hydrogenation protectant is lower than that in the interior of the hydrogenation protectant; the MoO3 content on the surface of the hydrogenation protectant is 4.0wt%-5.5wt%, and the NiO content is 1.0wt%-1.5wt%; the MoO3 content in the interior of the hydrogenation protectant is 7.5wt%-10.0wt%, and the NiO content is 1.8wt%-2.3wt%.

[0008] In the heavy oil hydrogenation protectant of the present application, the size of the flaky alumina grains is 100-600nm, the flaky alumina on the outer surface of the alumina carrier accumulates to form channels with a diameter of 40-300nm, the coverage rate of the flaky alumina on the outer surface of the alumina carrier is 85%-100%, wherein the coverage rate refers to the percentage of the surface occupied by the flaky alumina on the outer surface of the alumina carrier; the flaky alumina in the micron-level spherical cavities of the alumina carrier accumulates to form channels with a diameter of 50-100nm, and the filling rate of the flaky alumina in the micron-level spherical cavities is 40%-80%, wherein the filling rate refers to the percentage of the volume of the flaky alumina in the micron-level channels to the volume of the micron-level spherical cavities.

[0009] The heavy oil hydrogenation protective agent of the present application has a microspherical cavity with a diameter of 1-10 microns.

[0010] In the heavy oil hydrogenation protective agent of the present application, the alumina carrier containing the microspherical cavity accounts for 85wt%-95wt%, and MoO3 and NiO account for 5wt%-15wt% based on the weight of the hydrogenation protective agent.

[0011] The heavy oil hydrogenation protective agent of the present application further comprises spherical grains constituting the main body of the alumina carrier containing the microspherical cavity, and the size of the spherical grains is 100-250 nm.

[0012] The heavy oil hydrogenation protective agent of the present application can be prepared into a spherical shape, a cylindrical shape, a trilobal shape, a quadrilobal shape or other conventional catalyst shapes as needed.

[0013] The preparation method of the heavy oil hydrogenation protective agent of the present application comprises the following contents:

[0014] (1) impregnating microspherical activated carbon with a solution containing molybdenum and nickel, and then performing drying treatment to obtain molybdenum-nickel modified activated carbon;

[0015] (2) mixing the molybdenum-nickel modified activated carbon, pseudoboehmite and water to obtain a slurry, performing solid-liquid separation on the slurry, and then performing kneading, drying and calcination to obtain a precursor containing a microspherical cavity;

[0016] (3) immersing the precursor containing the microspherical cavity into an aqueous propylene oxide solution to perform low-temperature and high-temperature two-stage sealed heat treatment, performing solid-liquid separation on the treated material, and then performing drying and calcination on the solid-phase material to obtain an alumina carrier;

[0017] (4) sequentially immersing the alumina carrier obtained in step (3) with a high-concentration molybdenum-nickel impregnating solution and a low-concentration molybdenum-nickel impregnating solution, and then performing drying and calcination on the immersed material to obtain the heavy oil hydrogenation protective agent.

[0018] In the method of the present application, the solution containing molybdenum and nickel in step (1) can be an acid solution, an alkali solution or an aqueous solution of molybdenum and nickel, the molybdenum content in the solution is 1.0-4.5 g / 100 mL in terms of molybdenum oxide, the nickel content is 0.3-1.5 g / 100 mL in terms of nickel oxide, and the solution is used in an amount sufficient to completely impregnate the microspherical activated carbon, and the impregnation time is 0.5-4 hours.

[0019] In the method of the present application, the microspherical activated carbon in step (1) is spherical activated carbon with a diameter of 1-10 microns, which can be prepared by an existing method or purchased, and the drying temperature is 120-180°C and the drying time is 4-10 hours.

[0020] In the method, the mass ratio of the molybdenum-nickel modified activated carbon to the pseudoboehmite in step (2) is 1:3-1:5.5, and the mass ratio of liquid to solid in the slurry is 5:1-10:1.

[0021] In the method, the kneading and forming in step (2) is performed by a conventional method in the art, and drying is generally required before forming. During the forming process, an extrusion aid and a peptizing agent can be added as needed. The extrusion aid is pearl millet powder, and the addition amount is 0.1wt%-0.5wt% of the weight of the alumina carrier. The peptizing agent is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and oxalic acid, and the addition amount of the peptizing agent is 0.5wt%-1.5wt% of the weight of the alumina carrier. The drying temperature is 100-160°C, and the drying time is 4-10 hours. The calcination temperature is 450-700°C, and the calcination time is 4-6 hours. The calcination is performed in an oxygen-containing atmosphere. In the method, the concentration of the propylene oxide aqueous solution in step (3) is 2.5wt%-12wt%, preferably 4wt%-8wt%, and the mass ratio of the propylene oxide aqueous solution to the alumina carrier precursor is 3:1-10:1, preferably 4:1-8:1.

[0022] In the method, the sealed heat treatment in step (3) is performed in a closed container, and the closed container is preferably an autoclave. The two-stage sealed heat treatment process at low and high temperatures is as follows: first, sealed heat treatment at 60-100°C for 1-4 hours, and then sealed heat treatment at 110-180°C, preferably 120-160°C, for 14-20 hours.

[0023] In the method, the drying temperature in step (3) is 100-160°C, and the drying time is 2-8 hours. The calcination temperature is 700-900°C, and the calcination time is 4-6 hours. The calcination is performed in an oxygen-containing atmosphere, preferably an air atmosphere.

[0024] In the method, the high-concentration molybdenum-nickel impregnation solution in step (4) has a molybdenum content of 5.5%-12.5g / 100mL as an oxide and a nickel content of 1.2%-4.5g / 100mL as an oxide. The impregnation solution is used in an amount of 80%-90% of the saturated water absorption capacity of the alumina carrier. The low-concentration molybdenum-nickel impregnation solution has a molybdenum content of 4.5%-8.5g / 100mL as an oxide and a nickel content of 1.2-3.5g / 100mL as an oxide. The impregnation solution is used in an amount of 10%-20% of the saturated water absorption capacity of the alumina carrier.

[0025] In the method, the drying temperature in step (4) is 100-160°C, and the drying time is 2-8 hours. The calcination temperature is 450-550°C, and the calcination time is 4-6 hours.

[0026] The application of the heavy oil hydrogenation guard in heavy oil and residual oil hydrotreating is generally under the following conditions: reaction temperature 320-420 DEG C, hydrogen oil volume ratio 450-1000, liquid hourly space velocity 0.5-2.5 h -1 , operating pressure 10.5-14.5 MPa.

[0027] Compared with the prior art, the application has the following advantages:

[0028] The hydrogenation guard of the application has a special structure with flaky alumina distributed on the outer surface and in the cavity, the active metal distribution is well matched with the carrier structure, the cavity contains rich 50-100 nm pores and the active metal content is high, the surface of the guard is flaky alumina grain accumulation to form 40-300 nm open pores, the anti-metal deposition capacity is strong, which is beneficial to the diffusion of reactant molecules, especially the larger ones, to the inside of the catalyst, at the same time, the high active metal component content in the inside of the guard is beneficial to the removal of Ni, V and other metal impurities, and the low active metal component content on the surface is beneficial to the removal of Ca, Fe and other metal impurities in the residual oil raw material.

[0029] The hydrogenation guard with specific structure and precise metal distribution is obtained by specific hydrothermal environment and reaction conditions, so that the hydrogenation guard has strong Ca, Fe, Ni, V and other metal impurity removal capacity. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The surface SEM image of the alumina carrier precursor prepared in Example 1.

[0031] Figure 2 The cross-section SEM image of the alumina carrier precursor prepared in Example 1.

[0032] Figure 3 The surface SEM image of the alumina carrier prepared in Example 1.

[0033] Figure 4 The cross-section SEM image of the alumina carrier prepared in Example 1.

[0034] Figure 5 The surface SEM image of the alumina carrier prepared in Comparative Example 2.

[0035] Figure 6 The cross-section SEM image of the alumina carrier prepared in Comparative Example 2. DETAILED DESCRIPTION

[0036] The technical solutions and technical effects of the application will be further illustrated below in combination with examples, but are not limited to the following examples. In the application, wt% represents mass fraction.

[0037] 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 20uA, and the working distance is 8mm.

[0038] The content of active metal in the micro area of the catalyst is measured by a scanning electron microscope equipped with an energy dispersive X-ray spectrometer (EDAX), and the average value is obtained by randomly selecting 5 micro areas for composition determination, the acceleration voltage is 30KV, and the working distance is 8mm.

[0039] The content of active metal in the bulk phase refers to the content of metal MoO3 and NiO in the whole catalyst, and the content of molybdenum and nickel in the bulk phase of the catalyst is measured according to the method of ICP-AES determination of the content of metal elements in molybdenum and nickel series hydrogenation catalyst in Guangzhou Chemical Industry, 2021, 49, (17): 129-130.

[0040] The content of active metal on the surface refers to the content of metal MoO3 and NiO on the outer surface of the catalyst, and the composition is measured by adhering the catalyst particles to the scanning electron microscope sample table, and the outer surface is perpendicular to the electron beam direction of the scanning electron microscope.

[0041] The content of active metal in the internal refers to the content of metal MoO3 and NiO within 3 / 4r from the center of the catalyst cross section, and r is the radius of the catalyst cross section. When measuring, the catalyst particles are cut and adhered to the scanning electron microscope sample table, so that the cross section of the catalyst particles is perpendicular to the electron beam direction of the scanning electron microscope, and the composition is measured by a scanning electron microscope equipped with an energy dispersive X-ray spectrometer.

[0042] The content of active metal in the micron-sized cavity refers to the content of active metal in the pore formed after the micron-sized active carbon ball is calcined, and the composition in the region is measured by adhering the catalyst particles to the scanning electron microscope sample table, so that the cross section of the catalyst particles is perpendicular to the electron beam direction of the scanning electron microscope, and the composition is measured by a scanning electron microscope equipped with an energy dispersive X-ray spectrometer.

[0043] Preparation of micron spherical activated carbon:

[0044] The micron spherical activated carbon used in the method of the application is prepared according to the method in the literature: Dalinlin, Liwei, Wuqiong, et al. Preparation of micron spherical activated carbon by hydrothermal carbonization of carboxymethyl cellulose-CO2 activation [J]. Forest Products Chemistry and Industry, 2015, 35(4): 21-27. The diameter of the prepared micron spherical activated carbon is 1-10 microns.

[0045] Example 1

[0046] (1) Weigh 100g of the above micron-sized spherical activated carbon, immerse it in a molybdenum-nickel solution with a molybdenum oxide concentration of 2.2g / 100mL and a nickel oxide concentration of 0.5g / 100mL for 1 hour, filter the material after immersion, and dry the spherical activated carbon at 160℃ for 5 hours to obtain activated metal modified activated carbon.

[0047] (2) Weigh 100g of activated metal-modified activated carbon and 400g of boehmite from step (1), add 3000g of deionized water, and mechanically stir the mixture for 2 hours. After stirring, the material is separated into liquid and solid. The solid material is dried at 130℃ for 6 hours. Then, 2.5g of guar gum powder is added to the dried material and mixed evenly. An appropriate amount of 0.5% acetic acid solution is added and kneaded evenly. The mixture is then extruded into strips and dried at 130℃ for 8 hours. The strips are then calcined at 550℃ in an oxygen atmosphere for 5 hours to obtain the alumina carrier precursor S0. The scanning electron microscope image of the surface of the alumina carrier precursor is shown below. Figure 1 Cross-sectional scanning electron microscope image is shown below. Figure 2 .

[0048] (3) Weigh 100 g of the alumina carrier precursor from step (2), add 610 g of a 5.6% propylene oxide aqueous solution, transfer the mixture into a high-pressure reactor, seal it, and place the reactor in an oven. First, seal it at 80°C for 2 hours, then raise the temperature to 135°C and seal it for 17.5 hours. After cooling, wash and filter the material. Dry the solid material at 120°C for 6 hours and calcine it at 800°C for 5 hours to obtain the alumina carrier. The scanning electron microscope image of the outer surface of the carrier is shown in the figure. Figure 3 Cross-sectional scanning electron microscope image is shown below. Figure 4 .

[0049] (4) Weigh 100g of the alumina support from step (3) and place it in a spray impregnation pot. Spray the alumina support with 68mL of active component impregnation solution I with a molybdenum oxide concentration of 8.5g / 100mL and a nickel oxide concentration of 2.1g / 100mL. Then spray the alumina support with active component impregnation solution II with a molybdenum oxide concentration of 5g / 100mL and a nickel oxide concentration of 1.2g / 100mL until the support is saturated with adsorption. Dry the impregnated material at 120℃ for 5 hours and calcine at 450℃ for 5 hours to obtain the hydrogenation protection agent Cat-1. The properties of the catalyst are shown in Table 1.

[0050] Example 2

[0051] The same as Example 1, except that in step (1) the concentration of molybdenum oxide in the solution is 3.1 g / 100 mL and the concentration of nickel oxide is 0.6 g / 100 mL; in step (2) the amount of pseudoboehmite added is 450 g; in step (3) the concentration of propylene oxide is 6.6%, the amount of solution used is 500 g, and in the hydrothermal treatment, first the temperature is raised to 70°C and the treatment is carried out for 3 hours, then the temperature is raised to 145°C and the treatment is carried out for 16.5 hours; in step (4) the concentration of molybdenum oxide in the active component impregnation solution I is 8 g / 100 mL and the concentration of nickel oxide is 2 g / 100 mL, the amount of solution used is 64 mL, and the concentration of molybdenum oxide in the active component impregnation solution II is 5.4 g / 100 mL and the concentration of nickel oxide is 1.3 g / 100 mL, to obtain hydrogenation guard Cat-2, the properties of which are shown in Table 1.

[0052] Example 3

[0053] The same as Example 1, except that in step (1) the concentration of molybdenum oxide in the solution is 4 g / 100 mL and the concentration of nickel oxide is 0.9 g / 100 mL; in step (2) the amount of pseudoboehmite added is 350 g; in step (3) the concentration of propylene oxide is 7.3%, the amount of solution used is 460 g, and in the hydrothermal treatment, first the temperature is raised to 90°C and the treatment is carried out for 1.5 hours, then the temperature is raised to 125°C and the treatment is carried out for 19 hours; in step (4) the concentration of molybdenum oxide in the active component impregnation solution I is 9.5 g / 100 mL and the concentration of nickel oxide is 2.2 g / 100 mL, the amount of solution used is 72 mL, and the concentration of molybdenum oxide in the active component impregnation solution II is 4.5 g / 100 mL and the concentration of nickel oxide is 1.1 g / 100 mL, to obtain hydrogenation guard Cat-3, the properties of which are shown in Table 1.

[0054] Example 4

[0055] The same as Example 1, except that in step (1) the concentration of molybdenum oxide in the solution is 1.5 g / 100 mL and the concentration of nickel oxide is 0.4 g / 100 mL; in step (2) the amount of pseudoboehmite added is 500 g; in step (3) the concentration of propylene oxide is 4.5%, the amount of solution used is 700 g, and in the hydrothermal treatment, first the temperature is raised to 65°C and the treatment is carried out for 3.5 hours, then the temperature is raised to 155°C and the treatment is carried out for 15.5 hours; in step (4) the concentration of molybdenum oxide in the active component impregnation solution I is 7.5 g / 100 mL and the concentration of nickel oxide is 1.8 g / 100 mL, and the concentration of molybdenum oxide in the active component impregnation solution II is 6 g / 100 mL and the concentration of nickel oxide is 1.5 g / 100 mL, to obtain hydrogenation guard Cat-4, the properties of which are shown in Table 1.

[0056] Comparative Example 1

[0057] The same as Example 1, except that in step (3) the propylene oxide aqueous solution is replaced by an aqueous ammonia solution of the same mass concentration, to obtain comparative hydrogenation guard Cat-5, the properties of which are shown in Table 1.

[0058] Comparative Example 2

[0059] The same as Example 1 except that the propylene oxide aqueous solution in step (3) was replaced by an ethylene oxide solution of the same concentration to produce a comparative hydrogen protective agent Cat-6. The catalyst properties are shown in Table 1 and the corresponding scanning electron micrographs of the support surface are shown in Figure 5 Figure 6 .

[0060] Comparative Example 3

[0061] The same as Example 1 except that the propylene oxide concentration in step (3) was 1.5% to produce a comparative hydrogen protective agent Cat-7. The catalyst properties are shown in Table 1.

[0062] Comparative Example 4

[0063] The same as Example 1 except that the micron spherical activated carbon in step (1) was not modified with active metal but the same amount of active metal solution was added to the support during shaping to produce a comparative hydrogen protective agent Cat-8. The catalyst properties are shown in Table 1.

[0064] Comparative Example 5

[0065] The same as Example 1 except that the same amount of active component impregnation solutions I and II were mixed and then loaded by one-time impregnation during impregnation of the active metal component in step (4) to produce a comparative hydrogen protective agent Cat-9. The catalyst properties are shown in Table 1.

[0066] Table 1 Catalyst properties

[0067]

[0068] Continued Table 1 Catalyst properties

[0069]

[0070] From the data in Table 1 and the Figure 1 2 Figure 3 4 It can be seen that the hydrogen protective agent prepared by the method of the present application has wide surface pores and the pores formed by the stacking of sheet particles in the micron pores are well connected.

[0071] Example 5

[0072] The hydrogen protective catalysts Cat-1 to Cat-4 prepared by the present application and the comparative hydrogen protective catalysts Cat-5 to Cat-9 were respectively loaded into a fixed bed hydrogenation reactor and the raw materials (see Table 2) were treated under the following test conditions: reaction temperature 380°C, hydrogen / oil volume ratio 750, liquid hourly space velocity 1.1 h -1 ​​​​, hydrogen partial pressure 14.5 MPa, continuous operation 2000 hours, and the impurity removal properties are shown in Table 3.

[0073] Table 2 Properties of raw oil

[0074] Analysis item Residual oil Density (20°C), g / cm 3 ]] 0.98 Ni, pg / g 36.4 V, pg / g 89.7 Fe, pg / g 14.1 Ca, pg / g 16.1

[0075] Table 3 Evaluation results of catalyst

[0076]

[0077]

[0078] From the results in Table 3, it can be seen that the hydrogen protection catalyst prepared by the method of the present application has high removal rates of Ca and Fe and high removal rates of Ni and V, and the catalyst has good stability.

Claims

1. A heavy oil hydrotreating protectant, characterized in that: The alumina carrier includes a micron-sized spherical cavity, MoO3, and NiO. The outer surface and interior of the micron-sized spherical cavity of the alumina carrier are in situ grown with lamellar alumina grains. The MoO3 and NiO content on the surface of the hydrogenation protectant is lower than that inside the hydrogenation protectant. The lamellar alumina grain size is 100-600 nm. Lamellar alumina accumulates on the outer surface of the alumina carrier to form channels of 40-300 nm, and the lamellar alumina coverage on the outer surface of the alumina carrier is 85%-100%, where the coverage refers to the percentage of the outer surface of the alumina carrier occupied by lamellar alumina. Lamellar alumina accumulates in the micron-sized spherical cavity of the alumina carrier to form channels of 50-100 nm. The filling rate of alumina in the micron-sized spherical cavity is 40%-80%, wherein the filling rate refers to the percentage of the volume of the sheet alumina in the micron-sized channel to the volume of the micron-sized spherical cavity; the preparation method of the heavy oil hydrogenation protective agent includes the following: (1) impregnating micron-sized spherical activated carbon with a solution containing molybdenum and nickel, and then drying it to obtain molybdenum-nickel modified activated carbon; (2) mixing molybdenum-nickel modified activated carbon, boehmite and water to obtain a slurry, the slurry is separated into solid and liquid, kneaded into shape, dried and calcined to obtain a precursor containing micron-sized cavities; (3) immersing the precursor containing micron-sized cavities in an aqueous solution of propylene oxide for low-temperature and high-temperature two-stage sealed heat treatment, and after treatment, the material is separated into solid and liquid phases, and the solid phase material is separated into solid and liquid phases. After drying and calcination, an alumina carrier is obtained; (4) the alumina carrier obtained in step (3) is impregnated sequentially with a high-concentration molybdenum-nickel impregnation solution and a low-concentration molybdenum-nickel impregnation solution. After impregnation, the material is dried and calcined to obtain a heavy oil hydrogenation protectant; the sealing heat treatment in step (3) is carried out in a closed container. The two-stage sealing heat treatment process of low temperature and high temperature is as follows: first, sealing heat treatment at 60-100℃ for 1-4 hours, and then sealing heat treatment at 110-180℃ for 14-20 hours; the concentration of the propylene oxide aqueous solution in step (3) is 2.5wt%-12wt%, and the mass ratio of the propylene oxide aqueous solution to the alumina carrier precursor is 3:1-10:1; the molybdenum-containing material in step (1) The solution contains molybdenum (Mo) oxide at a concentration of 1.0-4.5 g / 100 mL and nickel at a concentration of 0.3-1.5 g / 100 mL. In the high-concentration molybdenum-nickel impregnation solution described in step (4), the Molybdenum content is 5.5%-12.5 g / 100 mL and the Nickel content is 1.2%-4.5 g / 100 mL. The amount of impregnation solution used is 80%-90% of the saturated water absorption capacity of the alumina carrier. In the low-concentration molybdenum-nickel impregnation solution, the Molybdenum content is 4.5%-8.5 g / 100 mL and the Nickel content is 1.2-3.5 g / 100 mL. The amount of impregnation solution used is 10%-20% of the saturated water absorption capacity of the alumina carrier.

2. The heavy oil hydrotreating protectant according to claim 1, characterized in that: The diameter of the micron-sized spherical cavity is 1-10 micrometers.

3. The heavy oil hydrotreating protectant according to claim 1, characterized in that: Based on the weight of the hydrogenation protective agent, the alumina support containing the spherical cavity is 85wt%~95%, and the MoO3 and NiO are 5wt%~15%.

4. The heavy oil hydrotreating protectant according to claim 1, characterized in that: It also includes spherical grains that constitute the main body of the alumina carrier containing spherical cavities, with a grain size of 100-250 nm.

5. The heavy oil hydrotreating protectant according to claim 1, characterized in that: Hydrogenation protectants come in spherical, cylindrical, clover-shaped, and four-leaf clover shapes.

6. A method for preparing a heavy oil hydrogenation protectant according to any one of claims 1 to 5, comprising the following steps: (1) impregnating micron-sized spherical activated carbon with a solution containing molybdenum and nickel, and then drying it to obtain molybdenum-nickel modified activated carbon; (2) mixing molybdenum-nickel modified activated carbon, boehmite and water to obtain a slurry, separating the slurry into solid and liquid, kneading it into shape, drying it and calcining it to obtain a precursor containing micron-sized cavities; (3) immersing the precursor containing micron-sized cavities into an aqueous solution of propylene oxide for two-stage sealing heat treatment at low temperature and high temperature, separating the material into solid and liquid, and drying and calcining the solid phase material to obtain an alumina carrier; (4) impregnating the alumina carrier obtained in step (3) sequentially with a high-concentration molybdenum-nickel impregnation solution and a low-concentration molybdenum-nickel impregnation solution, and drying and calcining the impregnated material to obtain a heavy oil hydrogenation protectant.

7. The method according to claim 6, characterized in that: The molybdenum and nickel-containing solution mentioned in step (1) has a molybdenum content of 1.0-4.5 g / 100 mL (calculated as molybdenum oxide) and a nickel content of 0.3-1.5 g / 100 mL (calculated as nickel oxide). The solution volume is sufficient to completely impregnate the micron-sized spherical activated carbon, and the impregnation time is 0.5-4 hours.

8. The method according to claim 6, characterized in that: The micron-sized spherical activated carbon mentioned in step (1) is spherical activated carbon with a diameter of 1-10 microns; the drying temperature is 120-180℃ and the drying time is 4-10 hours.

9. The method according to claim 6, characterized in that: The mass ratio of molybdenum-nickel modified activated carbon to boehmite in step (2) is 1:3-1:5.5, and the liquid-solid mass ratio in the slurry is 5:1-10:

1.

10. The method according to claim 6, characterized in that: The sealing heat treatment in step (3) is carried out in a closed container. The two-stage sealing heat treatment process of low temperature and high temperature is as follows: first, sealing heat treatment at 60-100℃ for 1-4 hours, and then sealing heat treatment at 110-180℃ for 14-20 hours.

11. The method according to claim 6, characterized in that: The drying temperature in step (3) is 100-160℃, the drying time is 2-8 hours, the calcination temperature is 700-900℃, the calcination time is 4-6 hours, and the calcination is carried out in an oxygen-containing atmosphere.

12. The method according to claim 6, characterized in that: In step (4), the high-concentration molybdenum-nickel impregnation solution contains 5.5%-12.5g / 100mL of molybdenum as oxide and 1.2%-4.5g / 100mL of nickel as oxide, and the amount of impregnation solution used is 80%-90% of the saturated water absorption capacity of the alumina carrier; in the low-concentration molybdenum-nickel impregnation solution, the molybdenum content is 4.5%-8.5g / 100mL of molybdenum as oxide and the nickel content is 1.2-3.5g / 100mL of nickel as oxide, and the amount of impregnation solution used is 10%-20% of the saturated water absorption capacity of the alumina carrier.

13. The method according to claim 6, characterized in that: The drying temperature in step (4) is 100-160℃, the drying time is 2-8 hours, the calcination temperature is 450-550℃, and the calcination time is 4-6 hours.

14. The application of the heavy oil hydrotreating protectant according to any one of claims 1 to 5 in heavy oil hydrotreating, wherein the application conditions are: reaction temperature 320-420℃, hydrogen-to-oil volume ratio 450-1000, and liquid hourly space velocity 0.5-2.5 h⁻¹. -1 Operating pressure: 10.5-14.5 MPa.

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