Pseudo-boehmite as well as preparation method and application thereof

Abstract

The invention provides pseudo-boehmite as well as a preparation method and application thereof, in a pore size distribution curve of alumina obtained by roasting the pseudo-boehmite at 480-650 DEG C for 2-6 hours, a pore distribution peak exists at the pore diameter of 3-5 nm, and the half-peak width of the pore distribution peak is 0.5-0.8 nm, preferably 0.6-0.8 nm; the most probable pore diameter is 4.0 to 4.4 nm, preferably 4.2 to 4.4 nm; the pore distribution of the alumina obtained by roasting the pseudo-boehmite at 480-650 DEG C for 2-6 hours is as follows: the pore volume of pores with the diameter of 3-5nm accounts for 8-25% of the total pore volume, preferably 12-25%; and the pore volume of pores with the pore diameter of 10-60 nm accounts for 53-73% of the total pore volume, preferably 55-65%. The alumina obtained by roasting and dehydrating the pseudo-boehmite is suitable for a hydrotreating process of a mixed raw material of straight-run distillate oil blended secondary processing oil.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalytic materials, and particularly relates to a pseudo-boehmite, a preparation method and application thereof. BACKGROUND

[0002] Alumina has the advantages of adjustable pore structure, large specific surface area, good adsorption performance, good surface activity and thermal stability, and is widely used as a catalyst carrier in petroleum chemical processes such as hydrogenation, cracking and dehydrogenation. The matching of the pore structure of the alumina carrier and the size of the reactant molecules has a relatively important influence on the activity and stability of the catalyst. Alumina carriers with a bimodal pore structure have a greater technical advantage in the processing of poor mixed raw materials: large pores are conducive to the full contact of reactant molecules, especially large molecules, with active centers, and at the same time provide convenience for the rapid desorption of product molecules, while small pores can provide a large specific surface area, which is conducive to improving the dispersion of the loaded active metal and is more conducive to the deep reaction of the reactants.

[0003] The existing technology mainly starts from the carrier forming process to prepare alumina carriers with a bimodal pore structure. CN107837797A discloses a preparation method of alumina small balls with a bimodal pore distribution, alumina small balls and a catalytic reforming catalyst. The preparation method comprises: mixing pseudo-boehmite dry glue powder, aluminum sol and water to perform peptization, to obtain an aluminum hydroxide sol, the aluminum / chlorine mass ratio of the aluminum sol being 1.0-1.4; mixing the obtained aluminum hydroxide sol with a gelatinizing agent solution, and then dropping into a hot oil column to form balls, taking out the formed small balls, and then washing, drying and calcining after aging. CN104437447A discloses an alumina carrier with a bimodal pore structure and a preparation method thereof. The carrier is characterized by mercury intrusion method, and has a pore volume of 0.8-1.2 milliliter / gram, a specific surface area of 120-400 square meters / gram, a pore volume of pores with a diameter of 6-30 nm accounting for 58-80% of the total pore volume, a pore volume of pores with a diameter of 10-30 nm being lower than 55% of the total pore volume, and a pore volume of pores with a diameter of 300-500 nm accounting for 10-35% of the total pore volume. The preparation method comprises mixing hydrated alumina P1 containing pseudo-boehmite and a modified product P2 of P1, and then forming, drying and calcining. 2

[0004] Pseudo-boehmite, as the main raw material for preparing alumina carriers, has an important influence on the pore structure of the alumina carrier and the pore structure of the catalyst. However, there are few studies on the preparation of alumina carriers with a bimodal pore structure starting from the pseudo-boehmite raw material and the application thereof in the heavy oil hydrogenation process. When the pseudo-boehmite in the prior art is used as a preparation material for alumina carriers and applied in the heavy oil hydrogenation process, the activity and stability of the catalyst need to be improved. SUMMARY ​

[0005] In view of the deficiencies in the prior art, the present application provides a pseudo-boehmite and a preparation method and application thereof. The alumina obtained by calcining and dehydrating the pseudo-boehmite is suitable for the hydrogenation treatment process of the mixed raw material of straight-run distillate oil and secondary processed oil.

[0006] The first aspect of the present application provides a pseudo-boehmite, wherein the pore size distribution curve of the alumina obtained by calcining the pseudo-boehmite at 480-650 DEG C for 2-6 h has a pore distribution peak at a pore diameter of 3-5 nm, the half-peak width is 0.5-0.8 nm, preferably 0.6-0.8 nm, and the most probable pore diameter is 4.0-4.4 nm, preferably 4.2-4.4 nm; the pore distribution of the alumina obtained by calcining the pseudo-boehmite at 480-650 DEG C for 2-6 h is as follows: the pore volume of the pores with a diameter of 3-5 nm accounts for 8-25%, preferably 12-25%, of the total pore volume; and the pore volume of the pores with a diameter of 10-60 nm accounts for 53-73%, preferably 55-65%, of the total pore volume.

[0007] In the pseudo-boehmite, the specific surface area of the alumina obtained by calcining the pseudo-boehmite at 480-650 DEG C for 2-6 h is 210-360 m 2 / g, preferably 230-350 m 2 / g; and the pore volume is 0.70-1.35 mL / g, preferably 0.78-1.30 mL / g.

[0008] The second aspect of the present application provides a preparation method of the above pseudo-boehmite, which comprises the following steps:

[0009] (1) contacting an aluminum-containing acidic solution and a sodium metaaluminate solution to perform a neutralization and gelation reaction; the pH value of the neutralization and gelation reaction is 4.6-6.7, preferably 4.8-6.5;

[0010] (2) adding an alkaline adjusting agent to the material obtained in step (2) to adjust the pH value to 6.9-7.9, preferably 6.9-7.7, further preferably 7.0-7.6, within 0.5-6 min, preferably 1-5 min, further preferably 2-4 min, and then performing an aging treatment;

[0011] (3) filtering and washing the slurry obtained by the aging treatment in step (2), and then drying to obtain the final pseudo-boehmite product.

[0012] In the above preparation method, the acidic aluminum-containing compound contained in the aluminum-containing acidic solution in step (1) is one or more of aluminum sulfate, aluminum nitrate and aluminum chloride solution; and the concentration of the aluminum-containing acidic solution is 2-8 g / 100 mL of Al2O3, preferably 3-7 g / 100 mL of Al2O3.

[0013] In the above preparation method, the preparation of the sodium metaaluminate solution in step (1) can use the existing technology in the art, and the concentration of the sodium metaaluminate solution is 12-30 g / 100 mL in terms of Al2O3.

[0014] In the above preparation method, the operating conditions of the neutralization gelation reaction in step (1) are as follows: the ratio of the amount of sodium metaaluminate solution (in terms of Al2O3) to the amount of the aluminic acid-containing solution (in terms of Al2O3) is 3-8; the neutralization gelation reaction temperature is 40-65°C, preferably 45-65°C; and the neutralization gelation reaction time is 30-60 min, preferably 35-55 min.

[0015] In the above preparation method, a polyhydric alcohol can also be introduced in step (1), and the introduction process is as follows: the polyhydric alcohol is added to the aluminic acid-containing solution, and then the solution is left to stand at a temperature of 25-45°C for 2-6 h, and then the neutralization gelation reaction is performed by contacting the solution with the sodium metaaluminate solution; the molar ratio of the amount of the polyhydric alcohol to the aluminum ions in the aluminic acid-containing solution is 0.05-0.15, preferably 0.06-0.12; and the polyhydric alcohol is one or more of sorbitol, dipropylene glycol and pentaerythritol.

[0016] In the above preparation method, the basic adjusting agent in step (2) is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate and sodium citrate.

[0017] In the above preparation method, the aging treatment in step (2) can be performed under constant temperature conditions or under temperature increasing conditions, and is preferably performed under temperature increasing conditions, and is further preferably performed under linear temperature increasing conditions; the upper limit of the temperature increasing is 75-95°C, preferably 75-90°C; and the temperature increasing time is controlled to be 0.5-3.0 h, preferably 1.0-2.5 h.

[0018] In the above preparation method, the filtration and washing in step (3) can use the existing technology as required, and the above process can be repeated, for example, the filtration and washing can be performed for multiple times.

[0019] In the above preparation method, the drying in step (3) can use static drying or dynamic drying; the drying temperature is 80-180°C, and the drying time is 2-8 h.

[0020] The third aspect of the present application provides a preparation method of a hydroprocessing catalyst, which comprises the following steps:

[0021] 1) performing a molding treatment on the pseudo-boehmite to obtain an alumina carrier;

[0022] 2) impregnating the alumina carrier with an active metal solution, and drying or drying and calcining to obtain the hydroprocessing catalyst.

[0023] In step 1) of the preparation method of the hydroprocessing catalyst, the molding can adopt any one of the means capable of realizing the molding of pseudo-boehmite in the prior art, such as kneading molding or roll molding; an auxiliary agent such as a peptizing agent, an extrusion aid, etc. can be added in the molding process, the peptizing agent can adopt one or more of nitric acid, oxalic acid, acetic acid, and propionic acid, and the extrusion aid can adopt cellulose and / or sesbania powder. The alumina carrier can be prepared into spherical, strip, tooth spherical, etc. according to requirements.

[0024] In step 2) of the preparation method of the hydroprocessing catalyst, the active metal in the active metal solution is a group ⅥB and / or group Ⅷ metal, wherein the group ⅥB metal is Mo and / or W, and the group Ⅷ metal is Ni and / or Co.

[0025] In step 2) of the preparation method of the hydroprocessing catalyst, the drying and calcination can adopt the conditions in the prior art, such as a drying temperature of 100-200℃, preferably 120-180℃, a drying time of 4-8h; a calcination temperature of 350-580℃, and a calcination time of 1-6h.

[0026] The fourth aspect of the present application provides the hydroprocessing catalyst obtained by the above preparation method. The content of the group ⅥB metal oxide in the hydroprocessing catalyst is 10-32wt%, and the content of the group Ⅷ metal oxide is 2-9wt% based on the weight of the catalyst.

[0027] The fifth aspect of the present application provides the application of the above hydroprocessing catalyst in a hydroprocessing process.

[0028] In the above application, the hydroprocessing process takes a mixed oil of straight-run distillate oil and secondary processing oil as the raw material; the straight-run distillate oil is one or more of normal three-line oil, vacuum tower top oil, reduced two-line oil, and reduced three-line oil; the secondary processing oil can be one or more of catalytic diesel oil, coking wax oil, deasphalted oil, and ebullated bed wax oil; the blending ratio of the secondary processing oil can be 5-40wt%, preferably 5-35wt%; the properties of the raw material are as follows: the density (20℃) is not less than 0.915g / mL, the sulfur content is not less than 2.0wt%, and the nitrogen content is not less than 1200mg / kg, preferably not less than 2000mg / kg.

[0029] In the above application, the operating conditions of the hydroprocessing process are as follows: the total reaction pressure is 6.0-18.0MPa, the volume space velocity is 0.3-3.2h -1 , the hydrogen / oil volume ratio is 400:1-1500:1, and the reaction temperature is 310-430℃.

[0030] Compared with the prior art, the pseudo-boehmite, the preparation method and the application thereof have the following advantages:

[0031] (1) The pseudo-boehmite provided by the present application has a mesopore / macropore hierarchical pore structure, and the alumina obtained by calcining and dehydrating the pseudo-boehmite has a pore distribution peak at a pore diameter of 3-5 nm and a concentrated pore size distribution. When the hydroprocessing catalyst prepared by using the pseudo-boehmite as a raw material is applied to a hydroprocessing process of a mixed raw material containing secondary processing oil, the catalyst has high activity and stability. In addition, the pseudo-boehmite provided by the present application can be directly used to prepare an alumina carrier with a bimodal pore structure, and the process of preparing the bimodal pore alumina carrier by using two or more kinds of pseudo-boehmite as required in the prior art is not needed, thereby reducing the production process and saving the preparation cost of the carrier.

[0032] (2) In the preparation method of the pseudo-boehmite provided by the present application, the aluminum-containing acidic solution and the sodium metaaluminate solution are first subjected to a neutralization gelation reaction under acidic conditions, and then a basic adjusting agent is rapidly added within a short time to adjust the pH value to a certain range, so that the reaction system conditions change rapidly, most of the aluminum hydroxide particles rapidly aggregate to form large particles, and then form macropores. However, since the pH value is near the isoelectric point, various charged particles are not enough to break the balance of the surface charges of all particles, so it is difficult to make all the aluminum hydroxide particles rapidly aggregate to form large particles, and thus a small part of the aluminum hydroxide particles are uniformly stacked to form relatively concentrated small pores. Further, a polyhydric alcohol can be introduced in the neutralization gelation reaction process. The polyhydric alcohol can interact with the hydroxyl groups on the surface of the aluminum hydroxide particles, adjust the aggregation rate of the aluminum hydroxide particles, and then adjust the pore structure of the product, thereby further improving the activity and stability of the hydroprocessing catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The pore size distribution diagram of the alumina obtained by calcining the pseudo-boehmite provided by the present application at 500℃ for 3h.

[0034] In the figure, 1 is Example 2, and 2 is Comparative Example 1. DETAILED DESCRIPTION

[0035] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to describe the technical features of the present application, but should not be considered as limiting the present application to the embodiments. The percentages involved are weight percentages.

[0036] In the method of the present application, the specific surface area and the pore volume are determined by a low-temperature nitrogen physical adsorption method on a Micromeritics TriStar II 3020 adsorption instrument. The sample is activated at 350℃ under vacuum for 3h, and the adsorption-desorption isotherm is determined at liquid nitrogen temperature. The pore size distribution of the sample is calculated by using the desorption curve.

[0037] Example 1

[0038] Take 392 g of aluminum sulfate dissolved in 1300 mL of distilled water, and uniformly add 12.3 g of sorbitol during stirring; after uniform stirring, stand for 4 h at 30°C. Then, adjust the temperature of the reaction system to 55°C, and simultaneously add the above solution and 15 g / 100 mL of sodium metaaluminate solution into the reaction container, the neutralization reaction time is 45 min, the pH value is 6.6, and the ratio of the amount of sodium metaaluminate solution added (in terms of Al2O3) to the amount of aluminum-containing acidic solution added (in terms of Al2O3) is 7.6. After the neutralization reaction is completed, quickly add 25 g / 100 mL of sodium carbonate solution within 2 min to adjust the pH to 7.9. Increase the temperature to 90°C, and keep the temperature constant at this temperature for 2 h. Then, filter the slurry to obtain a filter cake, and wash the filter cake by slurry for 3 times; finally, dry the filter cake at 120°C for 6 h to obtain a boehmite powder. Calcine at 500°C for 3 h to obtain the corresponding alumina AL-1, and the properties are shown in Table 1.

[0039] Example 2

[0040] Take 637 g of aluminum sulfate dissolved in 1300 mL of distilled water, and uniformly add 16.1 g of dipropylene glycol during stirring; after uniform stirring, stand for 4 h at 35°C. Then, adjust the temperature of the reaction system to 60°C, and simultaneously add the above solution and 22 g / 100 mL of sodium metaaluminate solution into the reaction container, the neutralization reaction time is 50 min, the pH value is 6.0, and the ratio of the amount of sodium metaaluminate solution added (in terms of Al2O3) to the amount of aluminum-containing acidic solution added (in terms of Al2O3) is 5.3. After the neutralization reaction is completed, quickly add 25 g / 100 mL of sodium carbonate solution within 1 min to adjust the pH to 7.5. Increase the temperature to 85°C, and keep the temperature constant at this temperature for 2 h. Then, filter the slurry to obtain a filter cake, and wash the filter cake by slurry for 3 times; finally, dry the filter cake at 120°C for 6 h to obtain a boehmite powder. Calcine at 500°C for 3 h to obtain the corresponding alumina AL-2, and the properties are shown in Table 1.

[0041] Example 3

[0042] Take 361 g of aluminum chloride dissolved in 1300 mL of distilled water, and uniformly add 21.8 g of dipropylene glycol during stirring; after uniform stirring, stand for 4 h at 40°C. Then, adjust the temperature of the reaction system to 45°C, and simultaneously add the above solution and 28 g / 100 mL of sodium metaaluminate solution into the reaction container, the neutralization reaction time is 35 min, the pH value is 5.4, the ratio of the added amount of sodium metaaluminate solution (in terms of Al2O3) to the added amount of aluminum-containing acidic solution (in terms of Al2O3) is 4.1. After the neutralization reaction is completed, adjust the pH to 6.9 by rapidly adding 15 g / 100 mL of sodium hydroxide solution within 5 min. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 80°C within 2.5 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120°C for 6 h to obtain a boehmite powder. The corresponding alumina AL-3 is obtained by calcining at 500°C for 3 h, and the properties are shown in Table 1.

[0043] Example 4

[0044] Take 361 g of aluminum chloride dissolved in 1300 mL of distilled water, and uniformly add 21.8 g of dipropylene glycol during stirring; after uniform stirring, stand for 4 h at 40°C. Then, adjust the temperature of the reaction system to 45°C, and simultaneously add the above solution and 28 g / 100 mL of sodium metaaluminate solution into the reaction container, the neutralization reaction time is 35 min, the pH value is 5.4, the ratio of the added amount of sodium metaaluminate solution (in terms of Al2O3) to the added amount of aluminum-containing acidic solution (in terms of Al2O3) is 4.1. After the neutralization reaction is completed, adjust the pH to 6.9 by rapidly adding 15 g / 100 mL of sodium hydroxide solution within 5 min. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 80°C within 2.5 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120°C for 6 h to obtain a boehmite powder. The corresponding alumina AL-3 is obtained by calcining at 500°C for 3 h, and the properties are shown in Table 1.

[0045] Example 5

[0046] Take 234 g of aluminum sulfate dissolved in 1300 mL of distilled water, and 20 g / 100 mL of sodium metaaluminate solution is added to the reaction vessel simultaneously, the temperature of the reaction system is 65 ℃, the neutralization pH value is 5.8, the neutralization reaction time is 55 min, the ratio of the amount of sodium metaaluminate solution added (calculated as Al2O3) to the amount of aluminum-containing acidic solution added (calculated as Al2O3) is 4.8. After the neutralization reaction is completed, 30 g / 100 mL of sodium carbonate solution is quickly added in 2.5 min to adjust the pH to 7.2. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 83 ℃ for 1.0 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120 ℃ for 6 h to obtain a boehmite powder. The corresponding alumina AL-5 is obtained by calcining at 500 ℃ for 3 h, and the properties are shown in Table 1.

[0047] Example 6

[0048] Take 482 g of aluminum sulfate dissolved in 1300 mL of distilled water, and 18 g / 100 mL of sodium metaaluminate solution is added to the reaction vessel simultaneously, the temperature of the reaction system is 50 ℃, the neutralization pH value is 4.8, the neutralization reaction time is 45 min, the ratio of the amount of sodium metaaluminate solution added (calculated as Al2O3) to the amount of aluminum-containing acidic solution added (calculated as Al2O3) is 3.3. After the neutralization reaction is completed, 40 g / 100 mL of sodium carbonate solution is quickly added in 3.0 min to adjust the pH to 7.7. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 75 ℃ for 3.0 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120 ℃ for 6 h to obtain a boehmite powder. The corresponding alumina AL-6 is obtained by calcining at 500 ℃ for 3 h, and the properties are shown in Table 1.

[0049] Comparative Example 1

[0050] Take 482 g of aluminum sulfate dissolved in 1300 mL of distilled water, and 18 g / 100 mL of sodium metaaluminate solution is added to the reaction vessel simultaneously, the temperature of the reaction system is 50 ℃, the neutralization pH value is 4.8, the neutralization reaction time is 45 min, the ratio of the amount of sodium metaaluminate solution added (calculated as Al2O3) to the amount of aluminum-containing acidic solution added (calculated as Al2O3) is 3.3. After the neutralization reaction is completed, 40 g / 100 mL of sodium carbonate solution is quickly added in 3.0 min to adjust the pH to 7.7. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 75 ℃ for 3.0 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120 ℃ for 6 h to obtain a boehmite powder. The corresponding alumina AL-6 is obtained by calcining at 500 ℃ for 3 h, and the properties are shown in Table 1.

[0051] Comparative Example 2

[0052] Take 482 g of aluminum sulfate dissolved in 1300 mL of distilled water, and 18 g / 100 mL of sodium metaaluminate solution is added to the reaction vessel simultaneously, the temperature of the reaction system is 50°C, the neutralization pH value is 4.8, the neutralization reaction time is 45 min, the ratio of the amount of sodium metaaluminate solution added (calculated as Al2O3) to the amount of aluminum-containing acidic solution added (calculated as Al2O3) is 3.3. After the neutralization reaction is completed, 30 g / 100 mL of sodium carbonate solution is quickly added in 2.0 min to adjust the pH to 8.5. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 75°C for 3.0 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120°C for 6 h to obtain a boehmite powder. The corresponding alumina DAL-2 is obtained by calcining at 500°C for 3 h, and the properties are shown in Table 1.

[0053] Comparative Example 3

[0054] Take 482 g of aluminum sulfate dissolved in 1300 mL of distilled water, and 18 g / 100 mL of sodium metaaluminate solution is added to the reaction vessel simultaneously, the temperature of the reaction system is 50°C, the neutralization pH value is 4.8, the neutralization reaction time is 45 min, the ratio of the amount of sodium metaaluminate solution added (calculated as Al2O3) to the amount of aluminum-containing acidic solution added (calculated as Al2O3) is 3.3. After the neutralization reaction is completed, 30 g / 100 mL of sodium carbonate solution is quickly added in 2.0 min to adjust the pH to 8.5. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 75°C for 3.0 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120°C for 6 h to obtain a boehmite powder. The corresponding alumina DAL-2 is obtained by calcining at 500°C for 3 h, and the properties are shown in Table 1.

[0055] Comparative Example 4

[0056] Take 482 g of aluminum sulfate dissolved in 1300 mL of distilled water, and 18 g / 100 mL of sodium metaaluminate solution is added to the reaction vessel simultaneously, the temperature of the reaction system is 50°C, the neutralization pH value is 4.8, the neutralization reaction time is 45 min, the ratio of the amount of sodium metaaluminate solution added (calculated as Al2O3) to the amount of aluminum-containing acidic solution added (calculated as Al2O3) is 3.3. After the neutralization reaction is completed, 30 g / 100 mL of sodium carbonate solution is quickly added in 2.0 min to adjust the pH to 8.5. Under the condition of linear temperature rise, the temperature is raised to the aging end temperature of 75°C for 3.0 h. Then, the slurry is filtered to obtain a filter cake, and the filter cake is washed by slurry for 3 times; finally, the filter cake is statically dried at 120°C for 6 h to obtain a boehmite powder. The corresponding alumina DAL-2 is obtained by calcining at 500°C for 3 h, and the properties are shown in Table 1.

[0057] Table 1 Properties of alumina powder prepared from pseudo-boehmite calcined at 500°C for 3h

[0058] Sample AL-1 AL-2 AL-3 AL-4 AL-5 AL-6 DAL-1 DAL-2 DAL-3 DAL-4 Specific surface area, m 2 / g]] 314 269 355 332 226 295 311 324 287 345 Pore volume, mL / g 1.21 0.87 1.32 1.10 0.72 0.98 1.02 1.07 0.92 0.94 Pore volume fraction of 3-5 nm pores, % 17.6 13.6 20.3 23.5 8.4 10.8 4.2 5.8 6.3 11.2 Pore volume fraction of 10-60 nm pores, % 60.3 61.8 57.8 53.0 71.8 66.4 52.1 58.7 57.4 54.2 Half-width of 3-5 nm pore distribution peak, nm 0.65 0.60 0.72 0.78 0.53 0.56 -- -- -- -- Most probable pore diameter of 3-5 nm pore distribution peak, nm 4.2 4.4 4.2 4.3 4.1 4.0 -- -- -- --

[0059] From the preparation process of the examples, it can be seen that the present application can realize the preparation of alumina powder with different pore volume and specific surface area. The prepared powder has high concentration of pore size distribution in the range of 3-5 nm, and also has abundant pore structure distribution in the range of 10-60 nm.

[0060] Example 7

[0061] 455 g of pseudo-boehmite powder AL-1 was uniformly mixed with 6.2 g of citric acid and 5.9 g of sesbania powder, and then 378 g of aqueous nitric acid solution (containing 7.5 g of nitric acid) was slowly and uniformly added. Then, the material was continuously rolled and pressed to become plastic, and was extruded into strips using a three-leaf clover plate with a diameter of 1.7 mm. The strips were dried at 120°C for 6 h, and were calcined at 550°C for 3 h. The obtained carrier was recorded as Z1. The same method was used to prepare carriers Z2, Z4, Z6, DZ1, DZ2, DZ3, and DZ4 using pseudo-boehmite powders AL-2, AL-4, AL-6, DAL-1, DAL-2, DAL-3, and DAL-4, respectively.

[0062] Example 8

[0063] The carriers Z2, Z4, and Z6 were used as catalyst carriers, and were impregnated with an equal volume of Mo- and Ni-containing solution for 4 h, and then were dried at 120°C for 4 h. The dried catalysts were calcined at 430°C for 3 h to obtain hydrogenation catalysts C2, C4, and C6, respectively. The physicochemical properties of the prepared catalysts are shown in Table 2.

[0064] Comparative Example 3

[0065] The carriers DZ1, DZ2, DZ3, and DZ4 were used as catalyst carriers, and were impregnated with an equal volume of Mo- and Ni-containing solution for 4 h, and then were dried at 120°C for 4 h. The dried catalysts were calcined at 430°C for 3 h to obtain hydrogenation catalysts DC1, DC2, DC3, and DC4, respectively. The physicochemical properties of the prepared catalysts are shown in Table 2.

[0066] Table 2 Physicochemical properties of the prepared catalysts

[0067] Catalyst C2 C4 C6 DC1 DC2 DC3 DC4 MoO3, wt.% 21.78 21.63 21.81 21.67 21.74 21.77 21.64 NiO, wt% 3.68 3.71 3.62 3.74 3.69 3.70 3.64

[0068] Example 9

[0069] The present example is an activity evaluation experiment of the catalyst. The catalyst activity test is carried out on a small hydrogenation device, and the catalyst evaluation conditions are as follows: the reaction pressure is 14.5 MPa, the volume space velocity is 1.2 h -1 -1, the hydrogen-oil volume ratio is 100:1, and the reaction temperature is 366 DEG C. The raw oil is obtained by mixing straight-run wax oil and deasphalted oil at a weight ratio of 80:20, the properties of the raw oil are shown in Table 3, and the evaluation results are shown in Table 4. As shown in the data in the table, the prepared hydroprocessing catalyst has better denitrification activity and stability.

[0070] Table 3 Properties of raw oil

[0071]

[0072]

[0073] Table 4 Catalyst activity evaluation results

[0074] Catalyst C2 C4 C6 DC1 DC2 DC3 DC4 Relative denitrogenation activity at 500 h, % 114 119 110 103 105 104 100 Relative denitrogenation activity at 1000 h, % 109 116 104 97 100 95 92

Claims

1. A pseudoboehmite characterized in that: The alumina obtained by calcining the pseudo-boehmite at 480-650℃ for 2-6h has a pore size distribution curve with a pore distribution peak at a pore diameter of 3-5nm, a half-peak width of 0.5-0.8nm, preferably 0.6-0.8nm, and a most probable pore diameter of 4.0-4.4nm, preferably 4.2-4.4nm; the pore distribution of the alumina obtained by calcining the pseudo-boehmite at 480-650℃ for 2-6h is as follows: the pore volume of pores with a diameter of 3-5nm accounts for 8-25%, preferably 12-25%, of the total pore volume; the pore volume of pores with a diameter of 10-60nm accounts for 53-73%, preferably 55-65%, of the total pore volume.

2. The pseudoboehmite according to claim 1, characterized in that: The alumina obtained by calcining the pseudo-boehmite at 480 to 650°C for 2 to 6 hours has a specific surface area of 210 to 360 m 2 / g, preferably 230 to 350 m 2 / g; and a pore volume of 0.70 to 1.35 mL / g, preferably 0.78 to 1.30 mL / g.

3. The method for preparing pseudoboehmite according to any one of claims 1 to 2, characterized in that: The preparation method comprises the following steps: (1) contacting an aluminum-containing acidic solution and a sodium metaaluminate solution to perform a neutralization and gelation reaction; the neutralization and gelation reaction has a pH value of 4.6-6.7, preferably 4.8-6.5; (2) adding a basic adjusting agent to the material obtained in step (2) to adjust the pH value to 6.9-7.9, preferably 6.9-7.7, further preferably 7.0-7.6, within 0.5-6min, preferably 1-5min, further preferably 2-4min, and then performing an aging treatment; (3) filtering, washing, and then drying the slurry obtained in the aging treatment of step (2) to obtain the final pseudo-boehmite product.

4. The method of claim 3, wherein: The aluminum-containing acidic solution in step (1) contains one or more of aluminum sulfate, aluminum nitrate, and aluminum chloride solution; the concentration of the aluminum-containing acidic solution is 2-8g / 100mL of Al2O3, preferably 3-7g / 100mL of Al2O3.

5. The method of claim 3, wherein: The concentration of the sodium metaaluminate solution in step (1) is 12-30g / 100mL of Al2O3.

6. The method of claim 3, wherein: The operating conditions of the neutralization and gelation reaction in step (1) are as follows: the ratio of the amount of sodium metaaluminate solution added (in terms of Al2O3) to the amount of aluminum-containing acidic solution added (in terms of Al2O3) is 3-8; the neutralization and gelation reaction temperature is 40-65℃, preferably 45-65℃; and the neutralization and gelation reaction time is 30-60min, preferably 35-55min.

7. The method of claim 3, wherein: In step (1), a polyhydric alcohol is also introduced, and the specific introduction process is as follows: the polyhydric alcohol is added to the aluminum-containing acidic solution, which is then statically placed at a temperature of 25-45℃ for 2-6h, and then the neutralization and gelation reaction is performed by contacting the solution with the sodium metaaluminate solution; the molar ratio of the amount of polyhydric alcohol added to the aluminum ions in the aluminum-containing acidic solution is 0.05-0.15, preferably 0.06-0.12; and the polyhydric alcohol is one or more of sorbitol, dipropylene glycol, and pentaerythritol.

8. The method of claim 3, wherein: The basic adjusting agent in step (2) is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and sodium citrate.

9. The method of claim 3, wherein: The aging treatment in step (2) is performed under constant temperature conditions or under temperature rising conditions, preferably under temperature rising conditions, further preferably under linear temperature rising conditions; the upper limit of the temperature rising is 75-95℃, preferably 75-90℃; and the temperature rising time is controlled to be 0.5-3.0h, preferably 1.0-2.5h.

10. The method of claim 3, wherein: The drying in step (3) is static drying or dynamic drying; the drying temperature is 80-180℃, and the drying time is 2-8h.

11. A process for the preparation of a hydroprocessing catalyst characterized by: The method comprises the following steps: 1) subjecting the pseudo-boehmite of any one of claims 1-2 to a shaping treatment to obtain an alumina carrier; 2) impregnating the alumina carrier with an active metal solution, and drying or drying and calcining to obtain a hydroprocessing catalyst.

12. The method of claim 11, wherein: In step 1), the shaping is kneading or rolling; a peptizing agent and a binder are added during the shaping; the peptizing agent is one or more of nitric acid, oxalic acid, acetic acid and propionic acid; the binder is cellulose and / or sesbania powder.

13. The method of claim 11, wherein: In step 2), the active metal in the active metal solution is a Group ⅥB and / or Group Ⅷ metal, wherein the Group ⅥB metal is Mo and / or W, and the Group Ⅷ metal is Ni and / or Co.

14. The method of claim 11, wherein: In step 2), the drying temperature is 100-200℃, preferably 120-180℃, and the drying time is 4-8h; the calcining temperature is 350-580℃, and the calcining time is 1-6h.

15. The hydroprocessing catalyst obtained by the preparation method of any one of claims 11-14.

16. The use of the hydroprocessing catalyst of claim 15 in a hydroprocessing process.

17. Use according to claim 16, characterized in that: The hydroprocessing process uses a mixture of straight-run distillate oil and secondary processing oil as the raw material; the straight-run distillate oil is one or more of normal three-line oil, vacuum tower top oil, reduced two-line oil and reduced three-line oil; the secondary processing oil is one or more of catalytic diesel oil, coking wax oil, deasphalted oil and ebullated bed wax oil; the blending ratio of the secondary processing oil is 5-40wt%, preferably 5-35wt%.

18. The use according to claim 17, characterized in that: The raw material has the following properties: the density (20℃) is not less than 0.915g / mL, the sulfur content is not less than 2.0wt%, and the nitrogen content is not less than 1200mg / kg, preferably not less than 2000mg / kg.

19. The use according to claim 16, characterized in that: The hydrotreating process operating conditions are as follows: total reaction pressure 6.0-18.0 MPa, volume space velocity 0.3-3.2 h -1 , hydrogen / oil volume ratio 400:1-1500:1, and reaction temperature 310-430°C.

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