A process for preparing a hydrofining catalyst

Abstract

The application discloses a preparation method of a hydrofining catalyst, and comprises the following steps: (1) adding deionized water into a gelatinization reaction tank, adding a solution containing W, Ni and Al into the gelatinization reaction tank, and dropping a basic precipitator into the reaction tank to perform a gelatinization reaction; the pH value is controlled by the basic precipitator to gradually increase from an initial value to a final value during the gelatinization reaction, a molybdenum-containing solution is added after each increase; the increasing times are 2-10, preferably 2-8; (2) continuously performing n times of aging on the slurry obtained in the step (1), adding 1 / n sodium metaaluminate solution during each aging process, filtering the slurry obtained after the aging to obtain solid material; the aging adopts a pH value gradually decreasing aging process; (3) drying, shaping, washing, drying, and calcining the solid material obtained in the step (2) to obtain the hydrofining catalyst. The catalyst prepared by the method is suitable for application in heavy distillate oil hydrodearomatization, ultra-deep hydrodesulfurization and denitrification reactions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst preparation, and particularly relates to a preparation method of a distillate oil hydrofining catalyst. BACKGROUND

[0002] Domestic oil refining enterprises have multiple sets of hydrofining devices, producing a large amount of diesel distillate products. In particular, with increasingly stringent environmental protection regulations, reducing diesel quantity is the direction of efforts, and oil conversion and oil special development. At present, in order to cope with the low aromatization trend in current oil quality upgrading, especially to solve the problem of multi-ring aromatic content limitation, and to achieve precise hydrogenation, the most fundamental way is still to start from the catalyst itself.

[0003] The combination of active metal components in the hydrogenation catalyst is better than the single component activity, and the hydrogenation saturation activity of the W-Ni combination in the combination of metal components is the best, and the hydrogenation denitrification of the Mo-Ni combination is the best. The bulk catalyst is the highest activity hydrogenation catalyst at present, and the active metal content reaches more than 70%. The bulk hydrogenation catalyst can get rid of the limitation of metal content, and can arbitrarily adjust the proportion of each active component in the catalyst to improve the hydrogenation performance of the catalyst. In the bulk catalyst, the size and distribution of metal oxide particles have a great influence on the distribution of hydrogenation active metals and the interaction between different hydrogenation active metals, which further affects the hydrogenation activity of the bulk catalyst. At the same time, the pore size and specific surface area of the catalyst also affect the hydrogenation activity of the bulk catalyst, and the smaller the pore size of the catalyst, the larger the molecular reactant cannot pass through the catalyst pores. The smaller the catalyst surface, the uneven distribution of active metals will cause disordered distribution of different hydrogenation active metals, and the high content of metals in the bulk catalyst will cause excessive accumulation of metal particles, which reduces the generation of active phase,

[0004] CN1951561A discloses a method for preparing a hydrogenation catalyst by co-precipitation, and the catalyst uses active metals Ni and W components to co-precipitate with a precipitator to form a Ni x W y O z The composite oxide precursor can be added with an aluminum salt solution, or the aluminum hydroxide can be directly added after gelation, and then mixed with MoO3 by beating, filtered, shaped, and activated to form the final catalyst. The bulk catalyst prepared by the method has small pore volume and specific surface area, and the active metal is excessively accumulated, which reduces the utilization rate of the active metal.

[0005] CN103861609A discloses a preparation method of a non-supported high-activity hydrogenation catalyst. An acidic solution A containing at least one Group VIII metal compound and an alkaline solution B containing at least one silicon source or aluminum source are slowly mixed into a precipitation reactor to perform a co-precipitation reaction at a temperature of 20-120°C and a pH value of 7-12. The obtained slurry is aged, filtered, washed, dried, shaped and calcined. The hydrogenation catalyst has a higher specific surface area and larger pore volume, but the reaction product has poor adhesion and can only be shaped into tablets, not into strips.

[0006] CN109692686A discloses a hydrofining catalyst and a preparation method thereof. The hydrofining catalyst is a bulk hydrofining catalyst. Mixed solution A and a precipitator are added into a reaction tank to perform a gelation reaction to generate a precipitate slurry I containing nickel, aluminum and tungsten. The obtained slurry I is aged. MoO3 is slurried with water to generate a MoO3 slurry. Mixed solution B and the precipitator are added into the aged slurry I in a concurrent manner to perform a gelation reaction to generate a precipitate slurry II containing nickel, molybdenum, tungsten and aluminum, which is then aged. The obtained material is dried, shaped, washed, dried again and calcined to obtain the hydrofining catalyst. Although the average stacking number of MoS2 / WS2 of the catalyst is 6.0-9.0 and the average length of MoS2 / WS2 layer is 4.0-6.5 nm by changing the gelation reaction conditions, the metal oxide particles are large and the content of surface active metal is low, which results in poor saturation effect on aromatic hydrocarbons in heavy oil.

[0007] CN102049265A, CN102451703A and CN106179380A disclose bulk hydrogenation catalysts. During calcination, a certain amount of gas is released, which changes the pore volume and specific surface area of the catalyst under the impact of the gas. However, the active metal is easily over-stacked under the action of the gas, and the generated oxide particles are large and uneven in size, which does not improve the utilization rate of surface active metal.

[0008] CN108786834A discloses a bulk phase hydrogenation catalyst and a preparation method thereof. The catalyst is a spherical particle, and the preparation process is divided into three steps: in the first step, an acidic solution I containing active metal, aluminum and ionic liquid is reacted with an alkaline I solution containing aluminum and active metal, and the pH value is adjusted to 9.0-11.0; in the second step, the reaction slurry obtained in the first step is reacted with an acidic solution II containing active metal, aluminum and ionic liquid, and the pH value is adjusted to 3.0-5.0; in the aging process, the alkaline II containing aluminum and active metal and the ionic liquid are continuously added, and the pH value is adjusted to 7.0-8.0; after aging, the catalyst is obtained by filtration, drying and calcination. Although the method has larger pore size, optimized pore size gradient distribution from inside to outside, effectively increases the pore size of the catalyst outside, and more active metal can be exposed to the surface of the catalyst channel, the oxide particles in the catalyst are relatively large, the active metal is prone to aggregation, the activity center of the catalyst is not effectively increased, and the obtained oxide material has poor adhesion, and can only be spheroidized.

[0009] In the existing bulk catalyst preparation technology by coprecipitation method, different precipitation methods and gel forming conditions have a great influence on the physical and chemical properties of the prepared catalyst, further affecting the distribution of hydrogenation active metals on the surface of the catalyst and the interaction relationship between different hydrogenation active metals. Therefore, how to uniformly disperse the active metals, increase the content of surface phase active metals and the density of active centers in the catalyst, improve the utilization rate of surface phase hydrogenation active metal components, and improve the mutual coordination between the active metals in the catalyst is the key to improving the hydrogenation performance of the bulk hydrogenation catalyst. SUMMARY

[0010] In view of the deficiencies of the prior art, the present application provides a preparation method of a hydrogenation catalyst. The method prepares a bulk hydrogenation catalyst, which has uniform active metal dispersion, uniform oxide particle size, high surface phase active site density, high hydrogenation saturation reaction performance, and is particularly suitable for application in heavy distillate oil hydrogenation de-aromatic, ultra-deep hydrogenation desulfurization and denitrification reactions.

[0011] The preparation method of the hydrogenation catalyst of the present application comprises the following contents:

[0012] (1) A solution containing W, Ni and Al is added to a gelation reaction tank, and an alkaline precipitant is dropped into the reaction tank for gelation reaction; during the gelation reaction process, the pH value is controlled by the alkaline precipitant to gradually increase from the initial value to the final value, and a molybdenum-containing solution is added after each increase; the number of increases is 2-10, preferably 2-8;

[0013] (2) The slurry obtained in step (1) is aged n times. 1 / n sodium aluminate solution is added during each aging process. The slurry obtained after aging is filtered to obtain solid material. The aging process adopts a pH value decreasing stepwise.

[0014] (3) The solid material obtained in step (2) is dried, shaped, washed, and then dried and calcined to obtain the hydrogenation refining catalyst.

[0015] In the method of the present invention, in the W, Ni and Al solution in step (1), the weight concentration of W as WO3 is 5-125 g / L, preferably 10-120 g / L, the weight concentration of Ni as NiO is 8-140 g / L, preferably 10-135 g / L, and the weight concentration of Al as Al2O3 is 5-95 g / L, preferably 8-90 g / L; wherein, when preparing the W, Ni and Al solution, the tungsten source is generally ammonium metatungstate, the aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride and aluminum acetate, and the nickel source is generally one or more of nickel sulfate, nickel nitrate and nickel chloride.

[0016] In the method of the present invention, the alkaline precipitant in step (1) is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, potassium carbonate or potassium bicarbonate, preferably sodium hydroxide solution and sodium carbonate solution, wherein the concentration of sodium hydroxide solution is 7wt% to 20wt% and the concentration of sodium carbonate solution is 5wt% to 17wt%.

[0017] In the method of the present invention, at the beginning of the gelation reaction in step (1), an alkaline precipitant is first used to control the initial pH value to 5.0 to 6.5, and the required time is 0.05 to 0.5 hours; the final pH value is 8.0 to 10.5, and the gelation reaction time is 0.5 to 2.5 hours.

[0018] In the method of the present invention, during the gelation reaction process described in step (1), the pH value increment is preferably kept constant at 0.05 to 0.8 hours after each increment. The pH value increment can be the same or different each time, but preferably the pH value increment is not greater than the previous pH value increment.

[0019] In the method of this invention, the molybdenum concentration (MoO3) in the molybdenum-containing solution in step (1) is 5–150 g / L, preferably 15–145 g / L. When preparing the molybdenum-containing solution, ammonium molybdate is generally used as the molybdenum source. The molybdenum-containing solution is added in portions according to the pH increments, and the volume of the molybdenum-containing solution added each time can be the same or different. The total amount of molybdenum-containing solution is determined based on the catalyst composition.

[0020] In the method of the present application, the weight concentration of Al (calculated as Al2O3) in the sodium metaaluminate solution in step (2) is 5-75 g / L, preferably 8-65 g / L. The sodium metaaluminate solution is divided into 2-8 portions by volume according to the number of additions.

[0021] In the method of the present application, the aging temperature in step (2) is 60-98℃, preferably 65-92℃.

[0022] In the method of the present application, the pH value in step (2) is gradually decreased in the aging process: the reaction slurry is dropped into 1 / n sodium metaaluminate solution for pH adjustment, the pH value is controlled at 11.5-13.5, and the aging time is 0.05-0.5 hour; then the pH value is adjusted to 8.5-10.5, and the aging time is 0.05-0.5 hour; finally the pH value is adjusted to 4.0-6.5, and the aging time is 0.05-0.5 hour, wherein n is an integer of 2-8.

[0023] In the aging process, in addition to using sodium metaaluminate solution for pH adjustment in the first stage, the acids and bases used for pH adjustment in the other stages can be inorganic salts, inorganic acids and inorganic bases containing no aluminum element, the inorganic acids can be hydrochloric acid and acetic acid, the inorganic bases can be one or more of sodium carbonate, sodium bicarbonate, ammonia water and sodium hydroxide, and the concentration and amount of the acid and base solutions can be adjusted according to the actual needs of preparation.

[0024] In the method of the present application, in step (2), the Al added by the sodium metaaluminate solution accounts for 5%-48% of the total Al (calculated as Al2O3) in the obtained hydrorefining catalyst, preferably 6%-45%.

[0025] In the method of the present application, the drying, shaping and washing in step (3) can be carried out by conventional methods in the art. The drying conditions are as follows: drying at 40-150℃ for 1-48 hours, preferably drying at 50-120℃ for 4-36 hours. The shaping process is well known in the field of catalyst preparation, and an extrusion aid and a peptizing agent are generally added in the extrusion process, the extrusion aid can be one or more of amaranth powder, carbon black, graphite powder or cellulose, and the peptizing agent is generally an acid solution containing one or more of hydrochloric acid, sulfuric acid and acetic acid, and the amount of the extrusion aid is 1wt%-10wt% of the total dry material. In the method of preparing the hydrorefining catalyst of the present application, the shape of the catalyst can be sheet, spherical, cylindrical strip or irregular strip (three-leaf clover, four-leaf clover) according to needs, and preferably cylindrical strip or irregular strip (three-leaf clover, four-leaf clover). The diameter of the catalyst can be 0.8-2.0 mm for a thin strip or >2.5 mm for a thick strip.

[0026] In the method of the present application, the calcination conditions in step (3) are as follows: calcination at 350-650℃ for 1-24 hours, preferably at 400-600℃ for 2-12 hours.

[0027] The present application also provides a hydrofining catalyst which is a bulk hydrofining catalyst, the hydrofining catalyst comprising a composite oxide of W, Mo, Ni and Al; the pore size distribution of the hydrofining catalyst being as follows: the pore volume of pores with a diameter of 6 nm or less accounts for 2-12% of the total pore volume, the pore volume of pores with a diameter of 6-10 nm accounts for 55-78% of the total pore volume, the pore volume of pores with a diameter of 10-15 nm accounts for 13-27% of the total pore volume, and the pore volume of pores with a diameter of 15 nm or more accounts for 5-22% of the total pore volume. The molar ratio of W / Mo is 1:13-10:1, preferably 1:11-9:1, and the molar ratio of Ni / (Mo+W) is 1:14-13:1, preferably 1:12-12:1; the ratio of the sum of the weight contents of the surface active metal components WO3 and NiO to the sum of the weight contents of the bulk active metal components WO3 and NiO is 2.8:1-7.0:1, preferably 3.5:1-6.5:1, and the ratio of the sum of the weight contents of the surface active metal components MoO3 and NiO to the sum of the weight contents of the bulk active metal components MoO3 and NiO is 2.8:1-6.2:1, preferably 3.0:1-5.7:1.

[0028] In the catalyst of the present application, the average particle size of the active metal oxide particles of tungsten, molybdenum and nickel is 9-14 nm. Preferably, the particle size distribution of the oxide particles is as follows: the number of particles with a particle size of less than 9 nm accounts for 3-18% of the total number of particles, the number of particles with a particle size of 9-14 nm accounts for 68-86% of the total number of particles, and the number of particles with a particle size of more than 14 nm accounts for 5-20% of the total number of particles.

[0029] The total content of Ni, W and Mo in the form of oxides in the hydrofining catalyst is 40-95%, preferably 50-90%, and the content of alumina is 5-60%, preferably 10-50%, based on the weight of the hydrofining catalyst.

[0030] The hydrofining catalyst has the following properties: a specific surface area of 200-510 m 2 / g, and a pore volume of 0.25-1.0 mL / g.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] 1. This invention uses a stepwise pH increment method to precipitate a solution containing W, Ni, and Al at a specific pH value, preventing the formation of large oxide particles during the gelation process. This ensures uniform dispersion of the active metals. The addition of Mo during the stepwise pH increment process is more conducive to the interaction between the active metals, greatly improving the hydrogenation activity of the catalyst.

[0033] 2. In this invention, the pH value is oscillated during aging, and sodium aluminate solution is added in stages. The pH oscillation dissolves the amorphous oxide in the oxide particles, and the addition of sodium aluminate solution modifies the size of the oxide particles. After n pH oscillations, the growth of oxide particles is controlled, making the oxide particles more uniform and exposing more active metals to the surface phase. This increases the macropores in the bulk catalyst, making it easier for large molecular reactants to pass through the pores. At the same time, the aluminum introduced by the sodium aluminate solution increases the surface hydroxyl groups, further enhancing the adhesion of the oxide and facilitating the formation of the bulk catalyst.

[0034] 3. The method for preparing hydrorefining catalyst of the present invention, through comprehensive control of the preparation steps and preparation conditions, results in a bulk catalyst with small and uniform metal oxide particles and high hydrogenation active sites on the catalyst surface, which improves the hydrogenation activity for treating heavy oil, especially beneficial to the aromatic saturation of heavy oil, effectively reducing the content of polycyclic aromatic hydrocarbons and increasing the cetane number. It is suitable for ultra-deep hydrodesulfurization, denitrification and dearomatication reactions of diesel fractions. Detailed Implementation

[0035] In this invention, the specific surface area and pore volume are determined by the cryogenic liquid nitrogen adsorption method, and the mechanical strength is determined by the lateral pressure method.

[0036] In this invention, the content of active metals on the surface of the catalyst is determined by X-ray photoelectron spectroscopy (XPS), and the content of active metals in the bulk of the catalyst is determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0037] In this invention, wt% is the mass fraction and v% is the volume fraction.

[0038] Example 1

[0039] Ammonium metatungstate, nickel chloride and aluminum chloride were added to dissolving tank 1 containing deionized water to prepare a W, Ni, Al-containing solution, in which the concentration of W (as WO3) was 60 g / L, the concentration of Ni (as NiO) was 48 g / L, and the concentration of Al (as Al2O3) was 36.4 g / L. Ammonium molybdate was added to dissolving tank 2 containing deionized water to prepare a Mo-containing solution, in which the concentration of Mo (as MoO3) was 40 g / L, and the solution was divided into 5 equal parts by volume. The Al content of the sodium aluminate solution was 30% of the total Al (as Al2O3) in the resulting hydrofining catalyst, and the solution was divided into 5 equal parts by volume. The W, Ni, Al-containing solution was placed in a reaction tank, and the reaction temperature was set at 60°C. The pH value was controlled at 5.2 by adding NaOH solution dropwise. The pH value was raised by 0.7 in 5 steps, and the final pH value at the end of the process was adjusted to 8.7. After each pH adjustment, one part of the Mo-containing solution was added, and the adjusted reaction slurry pH value was kept constant for 10 minutes. A precipitate slurry containing Ni, Mo, W and Al was formed. The resulting slurry was aged at a temperature of 76°C. The pH value was controlled at 13.1 by adding one part of the sodium aluminate solution at the beginning of the aging process. The pH value was controlled at 9.3 after 0.15 hours of aging, and at 5.0 after 0.2 hours of aging. The above process was repeated 5 times, and the aging process was completed. The aged slurry was filtered, and the filter cake was dried at 100°C for 8 hours. The dried material was crushed and extruded into strips. The extruded material was washed with deionized water until neutral at room temperature. The washed material was dried at 100°C for 8 hours, and the dried material was calcined at 530°C for 5 hours to obtain catalyst A. The composition and main properties of catalyst A are shown in Table 1.

[0040] Example 2

[0041] Ammonium metatungstate, ammonium molybdate and aluminum chloride were added to dissolving tank 1 containing deionized water to prepare a W, Ni, Al-containing solution, in which the concentration of W as WO3 was 42 g / L, the concentration of Ni as NiO was 64 g / L, and the concentration of Al as Al2O3 was 35.1 g / L. Ammonium molybdate was added to dissolving tank 2 containing deionized water to prepare a Mo-containing solution, in which the concentration of Mo as MoO3 was 40 g / L, and the Mo-containing solution was divided into 5 equal parts by volume. The Al in the sodium aluminate solution accounted for 35% of the total Al (as Al2O3) in the obtained hydrofining catalyst, and the sodium aluminate solution was divided into 6 equal parts by volume. The W, Ni, Al-containing solution was placed in a reaction tank, the reaction temperature was 65°C, and NaOH solution was added dropwise to control the pH value to 5.1. The pH value was raised by 0.9 each time, and the final pH value at the end of the process was adjusted to 9.6. After the pH value was adjusted each time, one part of the Mo-containing solution was added, and the adjusted reaction slurry pH value was kept constant for 12 minutes to form a precipitate slurry containing nickel, molybdenum, tungsten and aluminum. The obtained slurry was aged, the aging temperature was 80°C, and the pH value was controlled to 13.3 by adding one part of the sodium aluminate solution at the beginning of the aging process. The aging time was 0.15 hours, and then the pH value was controlled to 9.6. The aging time was 0.15 hours, and then the pH value was controlled to 5.3. The aging time was 0.15 hours, and the above process was repeated 6 times to complete the aging process. The aged slurry was filtered, the filter cake was dried at 120°C for 9 hours, was rolled and was extruded into a strip. The extruded material was washed with deionized water at room temperature until it was neutral. The washed and shaped material was dried at 80°C for 8 hours, and the dried material was calcined at 520°C for 5 hours to obtain catalyst B. The catalyst composition and main properties are shown in Table 1.

[0042] Example 3

[0043] Ammonium metatungstate, ammonium molybdate and aluminum chloride were added to dissolving tank 1 containing deionized water to prepare a W, Ni, Al-containing solution, in which the concentration of W as WO3 was 44 g / L, the concentration of Ni as NiO was 54 g / L, and the concentration of Al as Al2O3 was 40.5 g / L. Ammonium molybdate was added to dissolving tank 2 containing deionized water to prepare a Mo-containing solution, in which the concentration of Mo as MoO3 was 48 g / L, and the Mo-containing solution was divided into 6 equal parts by volume. The Al in the sodium aluminate solution accounted for 25% of the total Al (as Al2O3) in the obtained hydrofining catalyst, and the sodium aluminate solution was divided into 5 equal parts by volume. The W, Ni, Al-containing solution was placed in a reaction tank, the reaction temperature was 55°C, and NaOH solution was added dropwise to control the pH value to 5.1. The pH value was raised by 0.8 each time, and the final pH value at the end of the process was adjusted to 9.1. After each adjustment, one part of the Mo-containing solution was added, and the adjusted reaction slurry pH value was kept constant for 15 minutes to form a precipitate slurry containing nickel, molybdenum, tungsten and aluminum. The obtained slurry was aged, the aging temperature was 83°C, and the pH value was controlled to 12.9 by adding one part of the sodium aluminate solution at the beginning of the aging process. The aging time was 0.2 hours, then the aging pH value was controlled to 8.8, the aging time was 0.15 hours, then the pH value was controlled to 4.8, and the aging time was 0.15 hours. The above process was repeated 5 times to complete the aging process. The aged slurry was filtered, the filter cake was dried at 80°C for 10 hours, and then was rolled and extruded into strips. The extruded material was washed with deionized water at room temperature until neutral. The washed and shaped material was dried at 100°C for 10 hours, and then was calcined at 550°C for 4 hours to obtain catalyst C. The catalyst composition and main properties are shown in Table 1.

[0044] Example 4

[0045] Ammonium metatungstate, ammonium molybdate and aluminum chloride were added into dissolving tank 1 containing deionized water to prepare a W, Ni, Al-containing solution, in which the concentration of W (as WO3) was 68 g / L, the concentration of Ni (as NiO) was 40 g / L, and the concentration of Al (as Al2O3) was 34.7 g / L. Ammonium molybdate was added into dissolving tank 2 containing deionized water to prepare a Mo-containing solution, in which the concentration of Mo (as MoO3) was 36 g / L, and the Mo-containing solution was divided into 4 equal parts by volume. The Al in the sodium aluminate solution accounted for 38% of the total Al (as Al2O3) in the obtained hydrofining catalyst, and the sodium aluminate solution was divided into 7 equal parts by volume. The W, Ni, Al-containing solution was put into a reaction tank, the reaction temperature was 70°C, and NaOH solution was added dropwise to control the pH value to 5.8. The pH value was adjusted to 9.0 at the end of the reaction by 4 times of pH value increase, and the pH value was increased by 0.8 each time. After the pH value was adjusted to the adjusted value each time, one part of the Mo-containing solution was added, and the pH value of the adjusted reaction slurry was kept constant for 10 minutes to form a precipitate slurry containing Ni, Mo, W and Al. The obtained slurry was aged, the aging temperature was 80°C, and the pH value was controlled to 12.6 by adding one part of the sodium aluminate solution at the beginning of the aging. The aging time was 0.15 hours, then the pH value was controlled to 9.7, the aging time was 0.15 hours, then the pH value was controlled to 5.5, and the aging time was 0.2 hours. The above operation was repeated 7 times to end the aging. The aged slurry was filtered, the filter cake was dried at 110°C for 7 hours, was rolled and was extruded into a strip. The extruded material was washed with deionized water at room temperature until neutral. The washed and formed material was dried at 80°C for 9 hours, and the dried material was calcined at 530°C for 4 hours to obtain catalyst D. The catalyst composition and main properties are shown in Table 1.

[0046] Comparative Example 1

[0047] A reference catalyst E having the same composition as the catalyst of Example 1 of the present application was prepared, and the specific process was as follows:

[0048] Ammonium metatungstate, nickel chloride, ammonium molybdate and aluminum chloride were added into a dissolving tank 1 containing deionized water to prepare a mixed solution A, in which the concentration of W was 60 g / L as WO3, the concentration of Mo was 40 g / L as MoO3, the concentration of Ni was 48 g / L as NiO, and the concentration of Al was 52 g / L as Al2O3. Deionized water was added into a reaction tank, and the mixed solution A and a sodium hydroxide solution (10% by weight) were added into the reaction tank to perform a gelation reaction. The pH value of the reaction was controlled at 7.8, the reaction temperature was 60°C, the reaction time was 1.5 hours, and a precipitate slurry containing nickel, molybdenum, tungsten and aluminum was generated. The slurry was aged at an aging temperature of 80°C and an aging pH value of 8.5 for 2.8 hours. The aged slurry was filtered, the filter cake was dried at 100°C for 8 hours, and then was rolled and extruded into a strip. The wet strip was washed with deionized water at room temperature until neutral. Then, the washed wet strip was dried at 100°C for 10 hours. The dried material was calcined at 530°C for 5 hours to obtain a catalyst E. The catalyst composition and main properties are shown in Table 1.

[0049] Comparative Example 2

[0050] A catalyst F was prepared according to the preparation method disclosed in CN102451703A, and the catalyst composition was compared with that of the catalyst E of Example 1. The specific process was as follows:

[0051] Deionized water was added into a dissolving tank 1, and nickel chloride and ammonium metatungstate were dissolved to prepare a mixed working solution A, in which the concentration of W was 60 g / L as WO3, and the concentration of Ni was 48 g / L as NiO. Deionized water was added into a dissolving tank 2, and then sodium aluminate was dissolved to prepare an alkaline solution B, in which the concentration of Al was 52 g / L as Al2O3. Deionized water was added into a reaction tank, and the temperature was increased to 60°C. Solution A, solution B and CO2 were added into the reaction tank to perform gelation under stirring, the concentration of CO2 was 40 v%, the gelation temperature was 60°C, the gelation time was 1.5 hours, and the pH value of the gelation slurry was 7.8. The total amount of CO2 added during the gelation process was in a molar ratio of 3.5 to Al2O3 in the alkaline solution, the aging temperature was 80°C, the pH value during the aging was 8.5, and the aging time after the gelation was 2.8 hours. Then, the slurry was filtered, 600 ml of pure water and 40.3 g of molybdenum trioxide were added into the filter cake, and the mixture was stirred and uniformly dispersed. The filter cake was dried at 100°C for 8 hours, and then was rolled and extruded into a strip. The wet strip was washed with deionized water at room temperature until neutral. Then, the washed wet strip was dried at 100°C for 10 hours. The dried material was calcined at 530°C for 5 hours to obtain a catalyst F. The catalyst composition and main properties are shown in Table 1.

[0052] Comparative Example 3

[0053] According to the preparation method disclosed in CN106179380A, reference agent G with the same catalyst composition as that of Example 1 of the present application was prepared, and the specific process was as follows:

[0054] Nickel chloride and aluminum chloride solution were dissolved in deionized water respectively to prepare mixed solution A, in which the weight concentration of NiO was 48 g / L and the weight concentration of Al2O3 was 26 g / L. Ammonium metatungstate, ammonium molybdate and aluminum chloride solution were dissolved in deionized water respectively to prepare mixed solution B, in which the weight concentration of WO3 was 60 g / L, the weight concentration of MoO3 was 40 g / L, and the weight concentration of Al2O3 was 26 g / L. A 10% (by weight) sodium hydroxide solution was added to solution A under stirring, the gelation temperature was maintained at 60°C, the pH value was controlled at 7.8 at the end, and the gelation time was controlled at 60 minutes, to generate a slurry I containing nickel and aluminum precipitates. Deionized water was added to the reaction tank, and a 10% (by weight) sodium hydroxide solution and solution B were added to the reaction tank in parallel flow, the gelation temperature was maintained at 60°C, the pH value was controlled at 7.8 during the parallel flow gelation reaction process, and the gelation time was controlled at 60 minutes, to generate a slurry II containing tungsten, molybdenum and aluminum precipitates. The two kinds of slurry containing precipitates were mixed and aged, the aging time was 2.8 hours, the aging temperature was 80°C, and the pH value was controlled at 8.5, then filtered, and the filter cake was subjected to hydrothermal treatment under water vapor containing urea, the conditions of the hydrothermal treatment were as follows: the molar ratio of urea to the total amount of active metal atoms was 7:1, the temperature was 250°C, the pressure was 4.0 MPa, and the treatment time was 3 hours, the filter cake was dried at 100°C for 8 hours, rolled, and extruded into a strip. Then washed with deionized water to neutral at room temperature, then dried at 100°C for 10 hours, and calcined at 530°C for 5 hours, to obtain catalyst G. The catalyst composition, pore distribution and main properties are shown in Table 1.

[0055] Comparative Example 4

[0056] The same as Example 1, reference agent H was prepared, all the Al-containing solution was added at one time during the aging process of the slurry containing nickel, molybdenum, tungsten and aluminum precipitates, and a fixed value was used for the aging pH value, and the specific preparation process was as follows:

[0057] Ammonium metatungstate, nickel chloride and aluminum chloride were added to dissolving tank 1 containing deionized water to prepare a W, Ni, Al-containing solution, in which the concentration of W (as WO3) was 60 g / L, the concentration of Ni (as NiO) was 48 g / L, and the concentration of Al (as Al2O3) was 36.4 g / L. Ammonium molybdate was added to dissolving tank 2 containing deionized water to prepare a Mo-containing solution, in which the concentration of Mo (as MoO3) was 40 g / L, and the Mo-containing solution was divided into 5 equal parts by volume. The Al content in the sodium aluminate solution was 30% of the total Al (as Al2O3) in the resulting hydrorefining catalyst. The W, Ni, Al-containing solution was placed in a reaction tank, and the reaction temperature was 60°C. NaOH solution was added dropwise to control the pH value to 5.2. The pH value was raised by 0.7 in 5 steps, and the final pH value at the end of the reaction was adjusted to 8.7. The Mo-containing solution was added after each pH adjustment, and the pH value of the adjusted reaction slurry was kept constant for 10 minutes. A precipitate slurry containing Ni, Mo, W and Al was formed, and the resulting slurry was aged at 80°C and a pH value of 8.5 for 2.8 hours. The aged slurry was filtered, and the filter cake was dried at 100°C for 8 hours, crushed, and extruded into strips. The extruded product was washed with deionized water at room temperature until neutral. The washed product was dried at 100°C for 8 hours, and the dried product was calcined at 530°C for 5 hours to obtain catalyst H. The composition and main properties of the catalyst are shown in Table 1.

[0058] Comparative Example 5

[0059] Example 1 was repeated to prepare reference agent I, except that the W, Ni, Mo, Al-containing solution was prepared directly for the gelation reaction, and no Mo-containing solution was added during the pH change of the gelation reaction. The preparation process is as follows:

[0060] Ammonium metatungstate, nickel chloride, ammonium molybdate and aluminum chloride were added into a dissolving tank 1 containing deionized water to prepare a W, Ni, Mo, Al-containing solution, in which the weight concentration of W as WO3 was 60 g / L, the weight concentration of Ni as NiO was 48 g / L, the weight concentration of Mo as MoO3 was 40 g / L, and the weight concentration of Al as Al2O3 was 36.4 g / L. Sodium aluminate solution was prepared, in which Al accounted for 30% of the total Al (as Al2O3) in the obtained hydrofining catalyst, and was divided into 5 equal parts by volume. The W, Ni, Mo, Al-containing solution was put into a reaction tank, the reaction temperature was 60°C, and NaOH solution was added dropwise to control the pH value to 5.2. The pH value was raised by 0.7 each time, and the final pH value at the end of the reaction was adjusted to 8.7. After each time of pH value adjustment, the adjusted reaction slurry pH value was kept constant for 10 minutes. The obtained slurry containing nickel, molybdenum, tungsten and aluminum precipitates was aged, the aging temperature was 76°C, and the pH value was controlled to 13.1 by adding one part of the sodium aluminate solution at the beginning of the aging. The aging time was 0.15 hours, then the aging pH value was controlled to 9.3, the aging time was 0.2 hours, then the pH value was controlled to 5.0, the aging time was 0.2 hours, and the above operation was repeated 5 times to end the aging. The aged slurry was filtered, the filter cake was dried at 100°C for 8 hours, was rolled and was extruded into strips. The extruded product was washed with deionized water at room temperature until neutral. The washed product was dried at 100°C for 8 hours, and the dried product was calcined at 530°C for 5 hours to obtain catalyst I. The catalyst composition and main properties are shown in Table 1.

[0061] Comparative Example 6

[0062] Reference agent J was prepared according to Example 1, and the preparation process directly prepared a W, Ni, Mo, Al-containing solution to participate in the gelation reaction, and the gelation reaction was carried out at a fixed pH value. The specific preparation process was as follows:

[0063] Ammonium metatungstate, nickel chloride, ammonium molybdate and aluminum chloride were added into a dissolving tank 1 containing deionized water to prepare a W, Ni, Mo, Al-containing solution, in which the weight concentration of W (as WO3) was 60 g / L, the weight concentration of Ni (as NiO) was 48 g / L, the weight concentration of Mo (as MoO3) was 40 g / L, and the weight concentration of Al (as Al2O3) was 36.4 g / L. The Al in the sodium aluminate solution accounted for 30% of the total Al (as Al2O3) in the obtained hydrofining catalyst, and the sodium aluminate solution was divided into five equal parts by volume. The W, Ni, Mo, Al-containing solution was placed into a reaction tank, and the reaction temperature was 60°C. The sodium aluminate solution was added dropwise, and the pH value was controlled at 7.6 at the end of the reaction. The reaction time was 1.5 hours. A slurry of a nickel, molybdenum, tungsten and aluminum-containing precipitate was generated. The obtained slurry was aged, and the aging temperature was 76°C. During the aging, the pH value was controlled at 13.1 by adding the first part of the sodium aluminate solution. The aging time was 0.15 hours. Then, the pH value was controlled at 9.3, and the aging time was 0.2 hours. Subsequently, the pH value was controlled at 5.0, and the aging time was 0.2 hours. The above process was repeated five times, and the aging was completed. The aged slurry was filtered, and the filter cake was dried at 100°C for 8 hours. The dried filter cake was rolled and extruded into a strip. The extruded strip was washed with deionized water until neutral at room temperature. The washed extruded strip was dried at 100°C for 8 hours. The dried extruded strip was calcined at 530°C for 5 hours to obtain catalyst J. The catalyst composition and main properties are shown in Table 1.

[0064] Example 5

[0065] This example is an activity evaluation experiment of the catalysts of the present application, and comparative catalysts are used for comparison. The catalysts A, B, C and D of the present application and the comparative catalysts E, F, G, H and I were used for comparison and evaluation in a 200 mL small-scale hydrogenation device. In order to further evaluate the aromatic saturation capacity of the catalysts, a catalytic diesel oil with a high aromatic content was selected as the test raw material, and the main properties of the raw material are shown in Table 4. The catalyst activity evaluation process conditions were as follows: hydrogen partial pressure was 6.4 MPa, reaction temperature was 360°C, liquid hourly space velocity was 2.3 h -1, hydrogen oil volume ratio is 500:1, and the evaluation results are shown in Table 5. From Tables 1-3, it can be seen that the catalysts of the present application have smaller average particle size and uniform distribution of the oxide particles, more surface active metals, and larger pore size, as compared with the catalysts of the comparative examples. From Table 4, it can be seen that the feed oil used in the catalyst activity evaluation has high aromatic content, which will increase the difficulty of hydrogenation saturation, ultra-deep hydrodesulfurization, and denitrification of the feed oil. From the evaluation results shown in Tables 5-6, it can be seen that the catalysts of the present application not only have excellent hydrodesulfurization activity and hydrodenitrification activity, but also have excellent hydrogenation saturation performance, effectively reducing the aromatic content of the heavy distillate oil, and the polycyclic aromatic content is reduced more obviously. The catalysts of the present application have excellent hydrogenation saturation, hydrodesulfurization, and hydrodenitrification performance when used for processing heavy distillate oil, especially for processing poor-quality diesel oil fraction with high aromatic content and high processing difficulty, effectively reducing the polycyclic aromatic content and improving the cetane number of the diesel oil.

[0066] Table 1 Catalyst composition and properties prepared in examples and comparative examples

[0067] Catalyst No. A B C D E F NiO, wt% 24 32 27 20 24 24 WO3, wt.% 30 21 22 34 30 30 MoO3, wt.% 20 20 24 18 20 20 Al203, wt.% balance balance balance balance balance balance Specific surface area, m 2 / g]] 289 295 282 305 156 219 Pore volume, mL / g 0.426 0.440 0.416 0.451 0.225 0.258 Pore distribution < 6 nm 6.20 6.14 6.71 5.43 62.47 43.69 6 nm to 10 nm 62.12 62.56 61.95 62.84 18.54 30.84 10 nm to 15 nm 19.51 18.81 19.56 19.32 10.51 13.05 > 15 nm 12.17 12.49 11.78 12.41 8.48 12.42

[0068] Table 1 (continued)

[0069] Catalyst No. G H I J NiO, wt% 24 24 24 24 [WC, wt%] 30 30 30 30 MoO3, wt.% 20 20 20 20 Al203, wt.% balance balance balance balance Specific surface area, m 2 / g]]> 230 241 274 249 Pore volume, mL / g 0.342 0.365 0.391 0.351 Pore distribution < 6 nm 51.48 43.61 16.21 32.41 6 nm to 10 nm 31.34 35.33 58.01 38.52 10 nm to 15 nm 14.05 10.16 15.51 16.41 > 15 nm 3.13 10.90 10.27 12.66

[0070] Table 2 Weight content ratio of active metal oxides in catalyst surface phase and bulk phase

[0071] Catalyst No. A B C D Table phase I W+Ni Bulk phase I W+Ni ]]> 5.21 5.29 5.05 5.37 Table phase I Mo Ni Bulk phase I Mo Ni ]]> ​​ 4.04 4.09 3.99 4.18

[0072] Table 2 (continued)

[0073]

[0074] Table 3 Average particle size and particle size distribution of oxide particles of catalysts obtained in examples

[0075] Catalyst No. A B C D E F Average particle size of oxide particles, nm 11.1 11.8 11.5 11.3 26.5 28.9 Particle size distribution of oxide particles, % Particle size less than 9 nm 9.21 8.78 9.12 9.15 6.16 7.23 Particle size from 9 nm to 14 nm 78.25 77.41 77.67 78.03 13.22 11.15 Particle size greater than 14 nm 12.54 13.81 13.21 12.82 80.62 81.62

[0076] Table 3 (continued) Average particle size and particle size distribution of oxide particles of catalysts obtained in examples

[0077] Catalyst No. G H I J Average particle size of core-shell composite oxide particles, nm 28.6 18.3 13.1 19.5 Particle size distribution of core-shell composite oxide particles, % Particle size less than 9 nm 4.12 4.26 7.82 7.29 Particle size from 9 nm to 14 nm 10.83 25.68 76.84 21.32 Particle size greater than 14 nm 85.05 70.06 15.34 71.39

[0078] Table 4 Main properties of feed oil

[0079] Item Analysis result Density (20°C), g / cm 3 ]] 0.9291 Distillation range, °C 162-380 S, μg / g 14650 N, μg / g 842 Aromatics, wt% 70.6 Polycyclic aromatics, wt% 45.3 Cetane number ＜24

[0080] Table 5 Catalyst activity evaluation results

[0081]

[0082]

[0083] Table 5 continued

[0084]

[0085] Table 6 Content of different nitrogen compounds in the hydrofinished oil

[0086] Catalyst No. A B C D E F Nitrogen content in hydrofinished oil, μg / g 4.6 4.0 4.9 3.7 89.5 80.1 1-MCB, μg / g 2.4 2.1 2.5 2.1 39.6 36.2 1,8-BMCB, μg / g 1.3 1.1 1.4 0.9 28.8 25.4 1,4,8-TMCB, μg / g 0.9 0.8 1.0 0.7 21.1 18.5

[0087] Table 6 continued

[0088]

[0089]

Claims

1. A process for the preparation of a hydrofining catalyst, characterized in that The method comprises the following steps: (1) dropping an alkaline precipitant into a solution containing W, Ni and Al to perform a gelation reaction; during the gelation reaction, the pH value is controlled by the alkaline precipitant to gradually increase from an initial value to a final value, and a molybdenum-containing solution is added after each increase; the number of increases is 2-10; (2) continuously aging the slurry obtained in step (1) for n times, adding 1 / n sodium metaaluminate solution during each aging process, and filtering the slurry obtained after aging to obtain a solid material; wherein the aging process is a pH value gradually decreasing aging process; (3) drying, shaping, washing, drying again, and calcining the solid material obtained in step (2) to obtain a hydrofining catalyst; in step (1), the initial pH value controlled by the alkaline precipitant is 5.0-6.5, and the final pH value is 8.0-10.5; in the molybdenum-containing solution of step (1), the weight concentration of MoO3 is 5-150 g / L; when the molybdenum-containing solution is prepared, the molybdenum source is ammonium molybdate; the molybdenum-containing solution is added in several portions according to the number of pH value increases, the volume of the molybdenum-containing solution added each time is the same or different, and the total amount of the molybdenum-containing solution is determined according to the composition of the catalyst; in step (2), the pH value gradually decreasing aging process is as follows: the reaction slurry is dropped into 1 / n sodium metaaluminate solution to adjust the pH value to 11.5-13.5, and the aging time is 0.05-0.5 hours; then the pH value is adjusted to 8.5-10.5, and the aging time is 0.05-0.5 hours; finally, the pH value is adjusted to 4.0-6.5, and the aging time is 0.05-0.5 hours, wherein n is an integer of 2-8.

2. The method of claim 1, wherein: In the W, Ni and Al-containing solution of step (1), the weight concentration of WO3 is 5-125 g / L, the weight concentration of NiO is 8-140 g / L, and the weight concentration of Al2O3 is 5-95 g / L; when the W, Ni and Al-containing solution is prepared, the tungsten source is ammonium metatungstate, the aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride and aluminum acetate, and the nickel source is one or more of nickel sulfate, nickel nitrate and nickel chloride.

3. The method of claim 1, wherein: The alkaline precipitant of step (1) is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, potassium carbonate or potassium bicarbonate.

4. The method of claim 1, wherein: In the gelation reaction of step (1), the constant time after each increase is 0.05-0.8 hours.

5. The method of claim 1, wherein: In step (2), the weight concentration of Al2O3 in the sodium metaaluminate solution is 5-75 g / L, and the sodium metaaluminate solution is divided into 2-8 portions according to the number of additions.

6. The method of claim 1, wherein: In step (2), the aging temperature is 60-98 ℃.

7. The method of claim 1, wherein: In step (2), the Al added by the sodium metaaluminate solution accounts for 5%-48% of the total Al in the obtained hydrofining catalyst in terms of Al2O3.

8. The method of claim 1, wherein: In step (3), the drying conditions are as follows: drying at 40-150 ℃ for 1-48 hours; and the calcining conditions are as follows: calcining at 350-650 ℃ for 1-24 hours.

9. A hydrofmishing catalyst prepared by the process of any one of claims 1 to 8, characterized by: The catalyst is a bulk hydrogenation refining catalyst, the hydrogenation refining catalyst comprising a composite oxide of W, Mo, Ni and Al; the pore size distribution of the hydrogenation refining catalyst is as follows: the pore volume of pores with a diameter of 6 nm or less accounts for 2-12% of the total pore volume, the pore volume of pores with a diameter of 6-10 nm accounts for 55-78% of the total pore volume, the pore volume of pores with a diameter of 10-15 nm accounts for 13-27% of the total pore volume, and the pore volume of pores with a diameter of 15 nm or more accounts for 5-22% of the total pore volume; the molar ratio of W / Mo is 1:13-10:1, and the molar ratio of Ni / (Mo+W) is 1:14-13:1; the ratio of the sum of the weight contents of the surface active metal components WO3 and NiO to the sum of the weight contents of the bulk active metal components WO3 and NiO is 2.8:1-7.0:1, and the ratio of the sum of the weight contents of the surface active metal components MoO3 and NiO to the sum of the weight contents of the bulk active metal components MoO3 and NiO is 2.8:1-6.2:

1.

10. The catalyst of claim 9, wherein: The average particle size of the tungsten, molybdenum and nickel active metal oxide microparticles is 9-14 nm; the particle size distribution of the tungsten, molybdenum and nickel active metal oxide microparticles is as follows: the number of microparticles with a particle size of less than 9 nm accounts for 3-18% of the total number of microparticles, the number of microparticles with a particle size of 9-14 nm accounts for 68-86% of the total number of microparticles, and the number of microparticles with a particle size of more than 14 nm accounts for 5-20% of the total number of microparticles.

11. The catalyst of claim 9, wherein: The total content of Ni, W and Mo in the form of oxides is 40-95%, and the content of alumina is 5-60%, based on the weight of the hydrogenation refining catalyst.

12. The catalyst of claim 9, wherein: The hydrofining catalyst has a specific surface area of 200-510 m 2 / g and a pore volume of 0.25-1.0 mL / g.

13. The hydrogenation refining catalyst prepared by the method of any one of claims 1-8 is used in the hydrogenation de-aromatization, ultra-deep hydrodesulfurization and denitrification of heavy distillate oil.

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