Phosphorus-containing hydrofining catalyst and preparation method thereof

Abstract

The present invention discloses a phosphorus-containing hydrofining catalyst and a preparation method thereof. The catalyst comprises core-shell structured composite oxide particles, wherein the core phase is an amorphous composite oxide containing molybdenum, nickel and silicon, and the shell phase is an amorphous composite oxide containing tungsten, nickel, aluminum and phosphorus. The method is as follows: (1) A sodium molybdate solution, a solution containing Ni and Si, and a precipitant are gelled and aged to obtain a slurry; (2) Deionized water, an oily liquid and a phosphate ester are added into a reactor, CO2 gas is introduced, and a solution containing Ni and Al, a sodium tungstate solution, a precipitant, CO2 gas and the slurry are subjected to co-current gelling reaction and aged to generate a slurry; (3) The slurry is aged, subjected to solid-liquid separation, dried and formed; (4) The formed product is subjected to desalting treatment to obtain a bulk-phase hydrofining catalyst. The phosphorus-containing hydrofining catalyst of the present invention has a reasonable metal distribution and particle size, and has high hydrodesulfurization and hydrodenitrogenation reaction performance in the process of hydrofining distillate oil.

Description

Technical Field

[0001] The present invention relates to a phosphorus-containing hydrofining catalyst and a preparation method thereof. Background Art

[0002] The bulk-phase hydrogenation catalyst is currently the catalyst with the highest hydrogenation activity center. In the existing methods, the impregnation method and the kneading method are used to prepare the catalyst. Since relatively low-cost sodium-containing metal salt raw materials cannot be used, the catalyst preparation cost and the wastewater treatment cost are high. The co-precipitation method for preparing the catalyst can use relatively low-cost sodium-containing raw materials, which greatly reduces the catalyst preparation cost and the wastewater treatment cost. However, the introduction of a large amount of sodium ions makes it difficult to remove the sodium ions in the catalyst. Even if the number of washing times is increased (the increase in the number of washing times will reduce the crushing strength of the catalyst), only the sodium ions on the surface of the catalyst can be removed, and a large amount of sodium ions still remain in the precipitated material. The residual sodium ions result in poor adhesiveness of the material, and the unremoved sodium ions are not conducive to the formation of the catalyst pore structure, resulting in a small pore volume and pore diameter of the catalyst, and the reactant molecules cannot approach the surface of the catalyst to react. At the same time, although the active metal content in the bulk-phase hydrogenation catalyst prepared by the existing method is high, the high content of the active metal in the bulk-phase catalyst accumulates excessively on the surface of the catalyst, the metal oxide particles in the catalyst are larger, the formation of the active phase is reduced, the catalyst activity is lowered, and the utilization rate of the active metal of the catalyst is also affected, increasing the use cost of the catalyst. The disordered distribution of different hydrogenation active metals results in no good coordination effect between the active metals.

[0003] CN102451706A discloses a preparation method of a hydrogenation catalyst composition, in which a sodium aluminate solution, a mixed solution containing Ni and W component salts, and CO2 gas are subjected to a co-current reaction to form a precipitate. CN110038581A discloses a method for preparing a hydrofining catalyst. The hydrofining catalyst is prepared by two-step precipitation, and sodium tungstate alkaline solution and sodium molybdate alkaline solution are used as precipitants for precipitation respectively. Both of these methods use a large amount of sodium-containing salts as raw materials for the precipitation reaction, but the precipitate generated by this method contains a certain amount of sodium ions, the metal oxide particles are larger, and the residual sodium ions result in poor adhesiveness of the material. The residual sodium ions also make the pore volume and specific surface area of the catalyst not large.

[0004] CN106513006A discloses a preparation method of a bulk-phase hydrofining catalyst. The method includes: mixing a Ni compound with deionized water for pre-dispersion under an ultrasonic environment, then adding a Mo compound to form a Ni-Mo fine grain structure, then adding a W compound and a complexing agent for hydrothermal reaction, and then kneading and extruding the obtained active component powder with aluminum hydroxide dry gel, followed by drying and calcination to obtain the catalyst. The catalyst prepared by the method of the present invention has uniform dispersion among different active phase grains. The W source is embedded in the Ni-Mo framework structure. Microscopically, the Ni-W active phase is easily wrapped by the Ni-Mo active phase, rather than an oxide core-shell structure macroscopically. The pore volume is small, there are not many effective active phases, the metal oxide particles are large, and the removal efficiency of complex sulfur-containing compounds with high nitrogen content is limited. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a phosphorus-containing hydrofining catalyst and a preparation method thereof. The phosphorus-containing hydrofining catalyst of the present invention has a reasonable metal distribution and particle size, low preparation cost, and a clean and pollution-free preparation process. The catalyst has a large pore volume and pore diameter, and has high hydrodesulfurization and hydrodenitrogenation reaction performance during the hydrofining process of distillate oil.

[0006] The phosphorus-containing hydrofining catalyst of the present invention comprises core-shell structure composite oxide particles. Based on the mass of the core-shell structure composite oxide particles, the core phase is 20% - 90%, preferably 25% - 88%, and the shell phase is 10% - 80%, preferably 12% - 75%; wherein the core phase is an amorphous composite oxide containing molybdenum, nickel and silicon, and the shell phase is an amorphous composite oxide containing tungsten, nickel, aluminum and phosphorus; the average particle diameter of the catalyst particles is 7 - 12 nm, and the particle size distribution of the core-shell structure composite oxide particles is as follows: the number of particles with a particle size less than 7 nm accounts for 2% - 15% of the total number of particles, the number of particles with a particle size of 7 nm - 12 nm accounts for 66% - 88% of the total number of particles, and the number of particles with a particle size greater than 12 nm accounts for 3% - 21% of the total number of particles; the pore size distribution of the phosphorus-containing hydrofining catalyst is as follows: the pore volume of pores with a diameter of less than 4 nm accounts for 1% - 10% of the total pore volume, the pore volume of pores with a diameter of 4 - 10 nm accounts for 12% - 40% of the total pore volume, the pore volume of pores with a diameter of 10 - 15 nm accounts for 22% - 56% of the total pore volume, and the pore volume of pores with a diameter of more than 15 nm accounts for 18% - 45% of the total pore volume; the preferred pore size distribution is as follows: the pore volume of pores with a diameter of less than 4 nm accounts for 2% - 8% of the total pore volume, the pore volume of pores with a diameter of 4 - 10 nm accounts for 14% - 36% of the total pore volume, the pore volume of pores with a diameter of 10 - 15 nm accounts for 24% - 54% of the total pore volume, and the pore volume of pores with a diameter of more than 15 nm accounts for 20% - 42% of the total pore volume; the Na2O content in the catalyst is less than 0.12%, preferably less than 0.1%.

[0007] In the phosphorus-containing hydrofining catalyst of the present invention, the molar ratio of tungsten to nickel atoms in the shell phase is 1:22 to 8:1, preferably 1:20 to 5:1. The content of aluminum, calculated as Al2O3, accounts for 5% to 30% of the mass of the hydrofining catalyst, preferably 7% to 28%. The content of phosphorus, calculated as P2O5, accounts for 2% to 15% of the mass of the hydrofining catalyst, preferably 3% to 13%.

[0008] In the phosphorus-containing hydrofining catalyst of the present invention, the molar ratio of molybdenum to nickel atoms in the core phase is 1:28 to 12:1, preferably 1:22 to 10:1. The content of silicon, calculated as SiO2, accounts for 2% to 38% of the mass of the hydrofining catalyst, preferably 4% to 36%.

[0009] In the phosphorus-containing hydrofining catalyst of the present invention, the mass of NiO in the core phase accounts for 30% to 80% of the total mass of NiO in the hydrofining catalyst, and the mass of NiO in the shell phase accounts for 20% to 70% of the total mass of NiO in the hydrofining catalyst.

[0010] The specific surface area of the phosphorus-containing hydrofining catalyst of the present invention is 180 to 700 m 2 / g, and the pore volume is 0.30 to 0.90 mL / g.

[0011] The preparation method of the phosphorus-containing hydrofining catalyst of the present invention includes the following steps:

[0012] (1) Perform a first gelation reaction on a sodium molybdate solution, a solution containing Ni and Si, and a first precipitant. After the reaction, perform first aging to obtain a first slurry containing Ni, Si, and Mo;

[0013] (2) Add deionized water, an oily liquid, and a phosphate ester to a reactor, introduce CO2 gas to saturate the CO2 concentration in the reactor liquid, and then add a solution containing Ni and Al, a sodium tungstate solution, a second precipitant, and the first slurry to the reactor in a co-current manner for a second gelation reaction. After the reaction, perform second aging to generate a second slurry;

[0014] (3) Age the second slurry. After the aging is completed, perform solid-liquid separation. The solid phase undergoes drying and shaping processes to obtain a shaped product;

[0015] (4) Perform desalting treatment, washing, drying, and calcination on the shaped product to obtain a bulk hydrofining catalyst.

[0016] In the method of the present invention, in the sodium molybdate solution in step (1), the weight concentration of Mo calculated as MoO3 is 5 to 110 g / L, preferably 10 to 100 g / L.

[0017] In the method of the present invention, in the solution containing Ni and Si in step (1), the weight concentration of Ni calculated as NiO is 5-120 g / L, preferably 10-110 g / L, and the weight concentration of Si calculated as SiO2 is 2-80 g / L, preferably 4-70 g / L; when preparing the solution containing Ni and Si, generally, the nickel source is one or more of nickel sulfate, nickel nitrate, and nickel chloride, and the silicon source is one or more of sodium silicate, silica sol, etc.

[0018] In the method of the present invention, the first precipitating agent in step (1) can be an aqueous solution of a nitrogen-free basic compound, preferably sodium hydroxide, and the weight concentration of the first precipitating agent is 5%-30%. Those skilled in the art can determine the amount of the first precipitating agent according to actual needs.

[0019] In the method of the present invention, the conditions for the first gelation reaction in step (1) are: the reaction temperature is 30-90 °C, preferably 40-85 °C, the pH value is 7.0-11.0, preferably 7.2-10.0, and the gelation time is 0.2-2.5 hours, preferably 0.3-2.0 hours.

[0020] In the method of the present invention, the first aging conditions in step (1) are as follows: the aging temperature is 60-90 °C, preferably 65-85 °C, the pH value is 7.0-11.0, preferably 7.2-10.5, and the aging time is 0.3-2.5 hours, preferably 0.5-2.0 hours.

[0021] In the method of the present invention, in step (1), the weight of Ni introduced accounts for 30%-80%, preferably 35%-78%, of the total Ni weight in the hydrofining catalyst obtained in step (4). In step (2), the weight of Ni introduced accounts for 20%-70%, preferably 22%-65%, of the total Ni weight in the hydrofining catalyst obtained in step (4).

[0022] In the method of the present invention, in the solution containing Ni and Al in step (2), the weight concentration of Ni calculated as NiO is 5-110 g / L, preferably 10-100 g / L, and the weight concentration of Al calculated as Al2O3 is 2-95 g / L, preferably 5-85 g / L.

[0023] In the method of the present invention, in the sodium tungstate solution in step (2), the weight concentration of W calculated as WO3 is 4-140 g / L, preferably 6-120 g / L; in step (2), when preparing the solution containing Ni and Al, generally, the nickel source is one or more of nickel sulfate, nickel nitrate, and nickel chloride, and the aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride, and aluminum acetate.

[0024] In the method of the present invention, the ratio of the total mass of Mo calculated as MoO3, Ni calculated as NiO, and Si calculated as SiO2 in the first slurry to the total mass of W calculated as WO3, Ni calculated as NiO, and Al calculated as Al2O3 in the second slurry is 2:8 to 9:1, preferably 2.5:7.5 to 8.8:1.2.

[0025] In the method of the present invention, the second precipitating agent described in step (2) is an alkaline precipitating agent, preferably an aqueous solution of sodium carbonate and / or sodium bicarbonate. The weight concentration of the second precipitating agent is 5% to 40%. The amount of the second precipitating agent used can be determined by those skilled in the art according to actual needs.

[0026] In the method of the present invention, the volume ratio of the deionized water added in step (2) to the volume of the first slurry obtained in step (1) is 0.1:1 to 3:1.

[0027] In the method of the present invention, the volume concentration of CO2 gas introduced into the deionized water in step (2) is 70v% to 99v%, preferably 80v% to 95v%. After the CO2 concentration in the water is saturated by introducing CO2, it is preferably sealed. The molar ratio of the total amount of CO2 gas added to Al2O3 in the solution containing Ni and Al is 1:1 to 7:1.

[0028] In the method of the present invention, the oily liquid described in step (2) is an unsaturated higher fatty acid glyceride (vegetable oil), preferably one or more of peanut oil, rapeseed oil, cottonseed oil, sunflower oil, soybean oil, corn oil, tea oil, and olive oil. The volume ratio of the oily liquid to the deionized water is 1:60 to 1:4, preferably 1:40 to 1:6.

[0029] In the method of the present invention, the phosphate esters described in step (3) are one or more of octadecyl ether phosphate (O-5P), alkylphenol ether phosphate (TXP-4, TXP-10), isomeric tridecanol ether phosphate (E-1310P), lauryl alcohol ether phosphate (MOA-3P, MOA-9P), castor oil phosphate, octadecyl phosphate, and lauryl phosphate, preferably one or more of alkylphenol ether phosphate (TXP-4, TXP-10), isomeric tridecanol ether phosphate (E-1310P), lauryl alcohol ether phosphate (MOA-3P, MOA-9P), and castor oil phosphate. The molar ratio of the amount of the phosphate esters added to the total number of W atoms in the sodium tungstate solution in step (2) is 0.3:1 to 3.0:1, preferably 0.4:1 to 2.5:1.

[0030] In the method of the present invention, the conditions for the second gelation reaction in step (2) are as follows: the reaction temperature is 30 to 90 °C, preferably 40 to 85 °C; the initial pH value is controlled to be 10.0 to 14.0, preferably 10.5 to 13.5; the final pH value at the end is 7.0 to 8.5, preferably 7.2 to 8.3; the gelation reaction time is 0.5 to 6.0 hours, preferably 0.6 to 5.0 hours. Preferably, the pH value can be decreased in steps from the initial value to the final pH value. The method of decreasing in steps is to decrease the pH value to the required value for that time and keep the pH value of this reaction slurry constant until the start of the next decrease. The number of decreases is 2 to 10 times, preferably 2 to 8 times. Preferably, after each decrease, it is preferably kept constant for 0.1 to 1.2 hours. The amplitude of each decrease can be the same or different. Preferably, the decrease amplitude of the pH value for the current time is equal to or less than the decrease amplitude of the pH value for the previous time. The time used for each decrease process is from the start of the current decrease to the start of the next decrease. Further, it is the sum of the time used for each pH value decrease and the time of keeping the pH value constant at this time. The time used for each decrease process can be the same or different. Preferably, the time is the same.

[0031] In the method of the present invention, the second aging conditions in step (2) are as follows: the aging temperature is 40 to 90 °C, the aging time is 1 to 5 hours, and the pH value is 7.0 to 11.0. The aging is generally carried out under stirring conditions.

[0032] In the method of the present invention, the aging conditions in step (2) are preferably carried out in the following manner. The first step is atmospheric pressure aging: the aging temperature is 30 to 90 °C, preferably 40 to 80 °C, the aging time is 1 to 6 hours, preferably 1.2 to 5 hours, and the pH value is 6.5 to 10.0, preferably 7.0 to 9.0. The second step is high-pressure aging: the temperature is 100 to 195 °C, preferably 100 to 190 °C, the time is 0.1 to 3.5 hours, preferably 0.3 to 2.8 hours, the pressure is not less than 10 MPa, preferably 10 to 15 MPa, and the pH value is 10.0 to 13.0, preferably 10.0 to 12.5.

[0033] In the method of the present invention, mild conditions during the aging process in step (2) are more conducive to the formation of uniform particle sizes. During the aging process carried out in a closed environment, in the first step of aging, the material phase structure has formed regular bodies. In a closed environment, under the action of higher temperature and pressure, the microscopic morphology of the material changes, and the material phase changes from regular bodies to irregular bodies formed by the stacking of irregular flakes. This structural change causes sodium ions inside the material phase to transfer to the surface of the material phase, which is more conducive to the next desalting treatment, and is also conducive to increasing the specific surface area of the bulk catalyst, improving the pore structure, exposing more active metals on the catalyst surface, and generating more hydrogenation active centers on the catalyst surface.

[0034] In the method of the present invention, the solid-liquid separation described in step (3) generally adopts methods such as filtration and centrifugation. The drying temperature in step (3) is 50-140 °C, and the drying time is 0.5-24 hours.

[0035] In the method of the present invention, the forming process described in step (3) is well-known in the field of catalyst preparation. Generally, an extrusion aid and a peptizing agent are added during the extrusion forming process. The extrusion aid can be one or more of talc powder, carbon black, graphite powder, cellulose, etc. The peptizing agent is generally an acid solution containing one or more of hydrochloric acid, sulfuric acid, acetic acid, etc. The dosage of the extrusion aid accounts for 1wt%-10wt% of the total dry basis of the materials. The catalyst of the present invention can be prepared into shapes such as flakes, spheres, cylindrical bars, and special-shaped bars (clover, four-leaf clover), etc. according to needs.

[0036] In the method of the present invention, the desalting treatment process described in step (4): First, conduct curing, and then wash to remove the salts precipitated on the surface of the formed product. The curing conditions are a temperature of 5-100 °C, preferably a temperature of 10-90 °C, and a time of 10-100 hours, preferably 24-90 hours.

[0037] In the method of the present invention, the desalting treatment described in step (4) is preferably carried out as follows: In the first stage, the temperature is 60-90 °C, conduct curing for 5-60 hours, preferably 8-55 hours, to precipitate hydrated sodium ions and retain vacancies; in the second stage, the temperature is 10-30 °C, and the time is 1-48 hours, preferably 2-42 hours, to promote the retention and contraction of vacancies, increase the pore volume of the catalyst and have good mechanical strength, and then wash to remove the precipitated salts. The washing process can use solvents such as water and ethanol that have good solubility for sodium salts.

[0038] In the method of the present invention, the washing, drying, and calcination described in step (4) can adopt conventional conditions in the art. The drying conditions are as follows: drying at 40-150 °C for 1-48 hours, preferably drying at 50-120 °C for 4-36 hours. The calcination conditions are as follows: calcining at 350-650 °C for 1-24 hours, preferably the calcination conditions are as follows: calcining at 400-600 °C for 2-12 hours. Washing is generally carried out using deionized water or an ethanol solution until it is washed to neutral.

[0039] Application of the phosphorus-containing hydrofining catalyst of the present invention in the hydrofining reaction of inferior diesel. Among them, the inferior distillate oil is catalytic diesel, coking diesel, mixed diesel (a mixture of catalytic diesel, coking diesel, and straight-run diesel, with the mass percentage of catalytic diesel being greater than 30%), and vacuum gas oil.

[0040] Further, the conditions for the hydrofining reaction of inferior diesel are as follows: the reaction temperature is 330 - 400 °C, the reaction pressure is 2.5 - 17 MPa, the hydrogen-oil volume ratio is 250:1 - 1200:1, and the liquid hourly space velocity is 0.3 - 5.0 h -1 .

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1. The phosphorus-containing hydrofining catalyst of the present invention improves the distribution state of active metals at the nanoscale. That is, it is mainly composed of composite oxide containing tungsten, nickel and aluminum coating composite oxide particles containing molybdenum, nickel and silicon. This coating structure is different from this structure at the macroscopic level (such as millimeter level). Controlling the structure of the catalytic material at the micro level enables the overall performance of the catalyst to be broken through, improving the hydrodesulfurization performance of the catalyst. At the same time, a certain amount of acidic centers are formed at the junction of the core-shell structure of the catalyst, improving the ability of the catalyst to eliminate steric hindrance while carrying out the hydrodesulfurization reaction, and reducing the occurrence of side reactions such as excessive cracking. When sulfur- and nitrogen-containing distillate oil raw materials (especially distillate oil raw materials containing difficult-to-remove sulfur and nitrogen) are in contact with the hydrofining catalyst of the present invention, the desulfurization and denitrification activities are significantly improved. At the same time, the cracking reaction of the diesel fraction is reduced, avoiding the reduction of diesel yield. Moreover, the catalyst of the present invention can reduce the content of active metals while ensuring the desulfurization and denitrification activities, thereby reducing the preparation cost of the catalyst.

[0043] 2. In the method of the present invention, the pre-prepared molybdenum-nickel-silicon aging slurry, nickel-aluminum mixed solution, sodium tungstate solution and precipitant are added in parallel into a reaction tank containing water, oily liquid, CO2 and phosphate mixture, and the second gelation is carried out by the method of decreasing pH to form a gel, so that tungsten and nickel are precipitated on the molybdenum-nickel crystal grains uniformly and orderly, forming core-shell composite oxide particles with tungsten-nickel coating molybdenum-nickel, and the particle size is uniform. Phosphate has excellent oil emulsification effect. Its addition can not only reduce the particle size of the core-shell composite oxide particles, but also introduce the additive P. The intermediate formed between the additive phosphorus and the hydrogenation active metals at the junction of the core-shell is beneficial to improving the coordination effect between the hydrogenation active metals at the junction of the core-shell, and improving the cooperation effect of the active metal components of the catalyst. The addition of CO2 gas can promote the uniform thickness of the shell phase of the core-shell composite oxide particles. The hydrofining catalyst prepared thereby is applicable to the hydrofining reaction of heavy distillate oil (such as diesel), especially conducive to deep hydrodesulfurization and denitrification, and can also avoid reducing the diesel yield.

[0044] 3. In the method of the present invention, a low-cost catalyst is prepared by a cleaning method. Since soluble sodium salts are used as raw materials, a large amount of sodium ions are contained in the precipitate after gel formation. The presence of a large amount of sodium ions results in a smaller pore volume of the catalyst and difficulty in forming. The inventor retains the sodium salt in the material during the forming process and then performs desalination treatment on the formed material to remove the precipitated sodium salt. During this process, due to the occupancy effect of the sodium salt during the forming process, the vacancies after sodium removal are more conducive to the formation of the catalyst pore structure, and the pore distribution moves towards the direction of macropores, increasing the pore volume and pore diameter of the catalyst, improving the diffusion performance of the catalyst, and solving the problems of small pore volume and difficulty in forming of the bulk catalyst prepared from clean raw materials in the prior art. At the same time, the catalyst of the present invention has multiple active centers, uniform dispersion, high utilization rate, and good mechanical strength, greatly improving the desulfurization and denitrification capabilities of the bulk catalyst when processing heavy diesel fraction oil. During the catalyst preparation process, washing is only carried out during the desalination treatment process, reducing the number of washing times in the conventional catalyst preparation process and reducing the water consumption. Through the comprehensive control of the preparation steps and preparation conditions, the obtained core-shell composite oxide structure is more conducive to the desalination treatment of the material, and the formed composite oxide core-shell structure is more significant after the material undergoes desalination treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is the TEM image of catalyst B obtained in Example 2. SPECIFIC EMBODIMENTS

[0046] In the present invention, the specific surface area and pore volume are measured by the low-temperature liquid nitrogen adsorption method, and the mechanical strength is measured by the side pressure method. The specific surface area, pore volume, and pore diameter distribution are measured using an ASAP-2405 type BET nitrogen adsorption instrument; the crushing strength of the catalyst is measured using a ZQJ-2 intelligent particle strength tester.

[0047] In the present invention, for the core-shell composite oxide particles, the metal content in the composite oxides within the core and the shell and the thickness of the shell are measured by TEM transmission electron microscopy (JSM-2100 of Japan). Among them, the method for measuring the metal content in the composite oxides within the core and the shell: The core-shell composite oxide particles are uniformly mixed with liquid epoxy resin, and then an appropriate amount of curing agent is added. After stirring evenly, it is heated and cured to form solid particles. The solid particles are cut into thin slices with a thickness of 5-20 nm by an ultramicrotome. The obtained slices are placed in a transmission electron microscope for observation to find a core-shell structure with clear interfaces (cross-section). The diameter of the electron beam is adjusted through the condenser lens so that its diameter basically covers the entire contour of the core-shell structure, and an energy-dispersive spectroscopy (EDS) spectrum is collected. The intensity of the main energy peaks is recorded and corresponds to the actual content of each element in the known feedstock. The diameter of the electron beam is adjusted to be less than or close to the size of the core or the shell layer. According to the intensity of the energy peak corresponding to this element, it is compared with the peak intensity and the corresponding actual value in the case of full coverage, and the metal content in the composite oxides within the core and the shell at this time is calculated. In the core-shell structure, the thickness of the shell is identified and measured from the image of the transmission electron microscope, and the proportion of the thickness of the shell in the total thickness of the core-shell is the average value obtained by measuring 40-100 core-shell particles.

[0048] In the present invention, wt% is the mass fraction and v% is the volume fraction.

[0049] Example 1

[0050] Nickel chloride and sodium silicate were respectively added to the dissolution tank 1 filled with deionized water to prepare a solution containing Ni and Si. In the Ni and Si solution, the weight concentration of Ni calculated as NiO was 28 g / L, and the weight concentration of SiO2 was 30 g / L. Nickel chloride and aluminum chloride solution were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution containing Ni and Al. In the solution containing Ni and Al, the weight concentration of Ni calculated as NiO was 24 g / L, and the weight concentration of Al calculated as Al2O3 was 30 g / L. Among them, the mass ratio of Ni in the Ni and Si solution used in the reaction of this example to Ni in the Ni and Al solution used was 14:12. The solution containing Ni and Si was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 12%) and sodium molybdate solution (the weight concentration of Mo calculated as MoO3 was 36 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 62 °C, the pH value was controlled at 7.8 at the end of the reaction, and the gelation time was controlled at 1.2 hours. After the reaction ended, aging was carried out. The aging temperature was 78 °C, the aging pH value was controlled at 7.5, and aging was carried out for 1.8 hours to obtain the first slurry. First, 800 mL of deionized water, 60 mL of rapeseed oil and castor oil phosphate with a molar ratio of 1.3 to the total number of W atoms in sodium tungstate were added to the reaction tank 2. CO2 gas with a concentration of 88 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al was 3.0. Then, a 10 wt% sodium carbonate solution, the first slurry, the solution containing Ni and Al, and sodium tungstate solution (the weight concentration of W calculated as WO3 was 40 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 60 °C, the pH value was initially controlled at 13.0, and through 6 times of lowering the pH value, the final pH value at the end was adjusted to 7.6, and the pH value lowered each time was 0.9. After each time the pH value was lowered to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 10 minutes. After the second gelation reaction ended, aging began. The aging temperature was 78 °C, the pH value was controlled at 8.0, and the aging time was 2.5 hours to obtain the second slurry. The aged slurry was filtered, and the filter cake was dried at 100 °C for 7 hours, rolled, and extruded into a clover shape. The formed strips were cured at 70 °C for 50 hours, then the temperature was lowered to 20 °C and curing continued for 30 hours. It was washed with deionized water at room temperature until neutral. Then the wet strips were dried at 100 °C for 12.0 hours, and the dried material was calcined at 500 °C for 4 hours to obtain catalyst A. The catalyst composition and main properties are shown in Table 1.

[0051] Example 2

[0052] Nickel chloride and sodium silicate were respectively added to the dissolution tank 1 filled with deionized water to obtain a solution containing Ni and Si. In the Ni and Si solution, the weight concentration of Ni calculated as NiO was 52 g / L, and the weight concentration of SiO2 was 40 g / L. Nickel chloride and aluminum chloride solution were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution containing Ni and Al. In the solution containing Ni and Al, the weight concentration of Ni calculated as NiO was 20 g / L, and the weight concentration of Al calculated as Al2O3 was 16 g / L. Among them, the mass ratio of Ni in the Ni and Si solution used in the reaction of this example to Ni in the Ni and Al solution used was 26:10. The solution containing Ni and Si was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 12%) and sodium molybdate solution (Mo weight concentration calculated as MoO3 was 40 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 65 °C, the pH value was controlled at 8.0 at the end of the reaction, and the gelation time was controlled at 1.2 hours. After the reaction ended, aging was carried out. The aging temperature was 80 °C, the aging pH value was controlled at 8.1, and the aging time was 1.4 hours to obtain the first slurry. First, 600 mL of deionized water, 60 mL of corn oil, and alkylphenol ether phosphate (TXP-4) with a molar ratio of 2.1 to the total number of W atoms in the mixed solution B were added to the reaction tank 2. CO2 gas with a concentration of 90 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al was 4.8. Then, 11 wt% sodium carbonate solution, the first slurry, the solution containing Ni and Al, and sodium tungstate solution (W weight concentration calculated as WO3 was 22 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 70 °C, the pH value was initially controlled at 12.7, and by adjusting the pH value 6 times, the final pH value at the end was adjusted to 7.3, and the pH value adjusted each time was 0.9. After each adjustment to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 12 minutes. After the second gelation reaction ended, aging began. The aging temperature was 78 °C, the pH value was controlled at 8.5, and the aging time was 3.1 hours to obtain the second slurry. The aged slurry was filtered, and the filter cake was dried for the first time at 90 °C for 11 hours, rolled, and extruded into a clover shape. The formed strips were cured at a temperature of 62 °C for 45 hours, then the temperature was lowered to 23 °C and curing continued for 28 hours. Washed with deionized water to neutral at room temperature. Then the wet strips were dried at 110 °C for 9.0 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.

[0053] Example 3

[0054] Nickel chloride and sodium silicate were respectively added to the dissolution tank 1 filled with deionized water to prepare a solution containing Ni and Si. In the Ni and Si solution, the weight concentration of Ni calculated as NiO was 24 g / L, and the weight concentration of SiO2 was 26 g / L. Nickel chloride and aluminum chloride solution were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution containing Ni and Al. In the solution containing Ni and Al, the weight concentration of Ni calculated as NiO was 20 g / L, and the weight concentration of Al calculated as Al2O3 was 40 g / L. Among them, the mass ratio of Ni in the Ni and Si solution used in the reaction of this example to Ni in the Ni and Al solution used was 12:10. The solution containing Ni and Si was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 14%) and sodium molybdate solution (the weight concentration of Mo calculated as MoO3 was 36 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 55 °C, the pH value was controlled at 8.4 at the end of the reaction, and the gelation time was controlled at 1.2 hours. After the reaction ended, aging was carried out. The aging temperature was 78 °C, the aging pH value was controlled at 8.0, and the aging time was 1.8 hours to obtain the first slurry. First, 1000 mL of deionized water, 60 mL of peanut oil, and lauryl alcohol ether phosphate (MOA-9P) with a molar ratio of 0.8 to the total number of W atoms in the mixed solution B were added to the reaction tank 2. CO2 gas with a concentration of 88 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al was 2.4. Then, a 12 wt% sodium carbonate solution, the first slurry, the solution containing Ni and Al, and a sodium tungstate solution (the weight concentration of W calculated as WO3 was 44 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 55 °C, the initial pH value was controlled at 12.9, and through 7 times of lowering the pH value, the final pH value at the end was adjusted to 8.0. Each time the pH value was lowered by 0.7. After each time it was lowered to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 12 minutes. After the second gelation reaction ended, aging began. The aging temperature was 79 °C, the aging pH value was controlled at 8.1, and after aging for 2.6 hours, then the precipitate slurry continued to be aged under high pressure, the pressure was 13.4 MPa, the aging temperature was 170 °C, the aging time was 1.2 hours, and the aging pH value was 12.3 to obtain the second slurry. The aged slurry was filtered, and the filter cake was dried at 110 °C for 9 hours, rolled, and extruded into a clover shape. The formed strips were cured at a temperature of 69 °C for 70 hours. They were washed with deionized water to neutral at room temperature. Then the wet strips were dried at 90 °C for 10.0 hours, and the dried material was calcined at 540 °C for 5 hours to obtain catalyst C. The catalyst composition and main properties are shown in Table 1.

[0055] Example 4

[0056] Nickel chloride and sodium silicate were respectively added to the dissolution tank 1 filled with deionized water to prepare a solution containing Ni and Si. In the Ni and Si solution, the weight concentration of Ni calculated as NiO was 36 g / L, and the weight concentration of SiO2 was 34 g / L. Nickel chloride and aluminum chloride solution were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution containing Ni and Al. In the solution containing Ni and Al, the weight concentration of Ni calculated as NiO was 24 g / L, and the weight concentration of Al calculated as Al2O3 was 28 g / L. Among them, the mass ratio of Ni in the Ni and Si solution used in the reaction of this example to Ni in the Ni and Al solution used was 18:12. The solution containing Ni and Si was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 15%) and sodium molybdate solution (the weight concentration of Mo calculated as MoO3 was 28 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 70 °C, the pH value was controlled at 8.3 at the end of the reaction, and the gelation time was controlled at 0.9 hours. After the reaction ended, aging was carried out. The aging temperature was 80 °C, the aging pH value was controlled at 8.4, and the aging time was 1.9 hours to obtain the first slurry. First, 900 mL of deionized water, 70 mL of peanut oil, and isomeric tridecyl alcohol phosphate (E-1310P) with a molar ratio of 1.4 to the total number of W atoms in the mixed solution B were added to the reaction tank 2. CO2 gas with a concentration of 90 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al was 3.9. Then, a 14 wt% sodium carbonate solution, the first slurry, the solution containing Ni and Al, and sodium tungstate solution (the weight concentration of W calculated as WO3 was 36 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 53 °C, the initial pH value was controlled at 12.5, and through 5 times of lowering the pH value, the final pH value at the end was adjusted to 8.0, and the pH value lowered each time was 0.9. After each time it was lowered to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 13 minutes. After the second gelation reaction ended, aging started. The aging temperature was 83 °C, the aging pH value was controlled at 8.0, and the aging time was 2.4 hours. Then, the precipitate slurry was continuously aged under high pressure, the pressure was 13.0 MPa, the aging temperature was 180 °C, the aging time was 1.5 hours, and the aging pH value was 12.0. The second slurry was obtained. The aged slurry was filtered, and the filter cake was dried at 80 °C for 12 hours, rolled, and extruded into a clover shape. The formed strips were cured at a temperature of 82 °C for 46 hours, then the temperature was lowered to 22 °C and curing continued for 38 hours. It was washed with deionized water to neutral at room temperature. Then the wet strips were dried at 110 °C for 9.0 hours, and the dried material was calcined at 520 °C for 5 hours to obtain catalyst D. The catalyst composition and main properties are shown in Table 1.

[0057] Comparative Example 1

[0058] Prepare a reference agent E with the same catalyst composition as in Example 1. The specific process is as follows:

[0059] According to the catalyst composition of Example 1, dissolve nickel chloride, aluminum chloride, and sodium silicate in deionized water to prepare a mixed solution. The weight concentration of Ni calculated as NiO is 52 g / L, the weight concentration of Al calculated as Al2O3 is 36 g / L, and the weight concentration of SiO2 is 36 g / L. Add 500 mL of deionized water to the reaction tank, and simultaneously add a 10 wt% NaOH solution, a sodium molybdate solution (the weight concentration of Mo calculated as MoO3 is 36 g / L), a sodium tungstate solution (the weight concentration of W calculated as WO3 is 40 g / L), and the mixed solution into the reaction tank for gel formation. The gel formation temperature is maintained at 62 °C, the pH value at the end is controlled at 7.8, and the gel formation time is controlled at 1.2 hours to form a slurry containing nickel and tungsten precipitates. Then, aging is carried out. The aging time is 2.0 hours, the aging temperature is 78 °C, the pH value during aging is controlled at 7.5. After aging, the reaction slurry is filtered, and the filter cake is dried at 100 °C for 7 hours, rolled, and extruded into pellets. The formed product is washed with deionized water at room temperature, and no formed product is obtained after washing. Take the powder and dry it at 100 °C for 12 hours, and calcine it at 500 °C for 4 hours to obtain catalyst E. The catalyst composition and main properties are shown in Table 1.

[0060] Comparative Example 2

[0061] According to the method disclosed in CN102049295A, prepare a reference agent F with a catalyst composition similar to that of Example 1. The specific process is as follows:

[0062] After adding 1000 mL of deionized water to the dissolution tank, successively add nickel chloride, ammonium metatungstate, and aluminum chloride solution, and stir evenly to prepare a mixed solution. The weight concentration of Ni calculated as NiO is 52 g / L, the weight concentration of W calculated as WO3 is 40 g / L, and the weight concentration of Al calculated as Al2O3 is 54 g / L. Take 160 g of ammonium bicarbonate and prepare an aqueous solution with a molar concentration of 2.5 mol / L. Then, the mixed solution, the ammonium bicarbonate aqueous solution, and the precipitant 10% ammonia water are simultaneously added into the reaction tank filled with deionized water for gel formation. The gel formation pH value is 7.8, and the gel formation temperature is 62 °C. After gel formation, add a slurry containing SAPO-11 molecular sieve, age for 2 hours, the aging temperature is 78 °C, and the pH value during aging is controlled at 7.5. After aging, filter, add 600 mL of deionized water and 36 grams of molybdenum trioxide to the filter cake, stir evenly by pulping, filter, and the obtained filter cake is dried at 100 °C for 7 hours, then extruded into pellets, washed with deionized water until neutral, the wet pellets are dried at 100 °C for 12 hours, and calcined at 500 °C for 4 hours to obtain the final catalyst F. The composition and main properties are shown in Table 1.

[0063] The SAPO-11 molecular sieve used in the comparative example was the one adopted in CN102049295A and could be synthesized by conventional methods, such as hydrothermal crystallization method. Its properties were as follows: the molar ratio of SiO2 / Al2O3 was 0.85, the infrared acid amount was 0.9 mmol / g, the pore volume was 0.24 mL / g, the specific surface area was 250 m 2 / g, the particle size was 450 nm, and the crystallinity was 85%.

[0064] Comparative Example 3

[0065] According to the preparation method of Example 1 (without adding grease to the gel-forming tank during the second step of gel formation) and the catalyst composition, the reference agent G was prepared.

[0066] Nickel chloride and sodium silicate were respectively added to the dissolution tank 1 filled with deionized water to prepare a solution containing Ni and Si. In the Ni and Si solution, the weight concentration of Ni calculated as NiO was 28 g / L, and the weight concentration of SiO2 was 30 g / L. Nickel chloride and aluminum chloride solutions were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution containing Ni and Al. In the solution containing Ni and Al, the weight concentration of Ni calculated as NiO was 24 g / L, and the weight concentration of Al calculated as Al2O3 was 30 g / L. Among them, the mass ratio of Ni in the Ni and Si solution used in the reaction of this example to Ni in the Ni and Al solution used was 14:12. The solution containing Ni and Si was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 12%) and sodium molybdate solution (the weight concentration of Mo calculated as MoO3 was 36 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 62 °C, the pH value was controlled at 7.8 at the end of the reaction, and the gelation time was controlled at 1.2 hours. After the reaction ended, aging was carried out. The aging temperature was 78 °C, the aging pH value was controlled at 7.5, and the aging time was 1.8 hours to obtain the first slurry. First, 800 mL of deionized water and castor oil phosphate with a molar ratio of 1.3 to the total number of W atoms in sodium tungstate were added to the reaction tank 2. CO2 gas with a concentration of 88 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al was 3.0. Then, a 10 wt% sodium carbonate solution, the first slurry, the solution containing Ni and Al, and a sodium tungstate solution (the weight concentration of W calculated as WO3 was 40 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 60 °C, the initial pH value was controlled at 13.0, and by adjusting the pH value 6 times, the final pH value at the end was adjusted to 7.6, and the pH value adjusted each time was 0.9. After each adjustment to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 10 minutes. After the second gelation reaction ended, aging started. The aging temperature was 78 °C, the pH value was controlled at 8.0, and the aging time was 2.5 hours to obtain the second slurry. The aged slurry was filtered, and the filter cake was dried at 100 °C for 7 hours, rolled, and extruded into a clover shape. The formed strips were cured at 70 °C for 50 hours, then the temperature was lowered to 20 °C and curing continued for 30 hours. Washed with deionized water to neutral at room temperature. Then the wet strips were dried at 100 °C for 12.0 hours, and the dried material was calcined at 500 °C for 4 hours to obtain catalyst G. The catalyst composition and main properties are shown in Table 1.

[0067] Comparative Example 4

[0068] According to the preparation method of Example 1 (when preparing the mixed solution A, silicon was not added), the reference agent H was prepared.

[0069] Nickel chloride and aluminum chloride solutions were respectively added to the dissolution tank 1 filled with deionized water to prepare a solution A containing Ni and Al. The weight concentration of Ni in terms of NiO in the Ni and Al solution A was 28 g / L, and the weight concentration of Al2O3 was 30 g / L. Nickel chloride and aluminum chloride solutions were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution B containing Ni and Al. The weight concentration of Ni in terms of NiO in the Ni and Al solution B was 24 g / L, and the weight concentration of Al in terms of Al2O3 was 30 g / L. Among them, the mass ratio of Ni in the Ni and Al solution A used in the reaction of this example to Ni in the Ni and Al solution B was 14:12. The Ni and Al solution A was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 12%) and sodium molybdate solution (the weight concentration of Mo in terms of MoO3 was 36 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 62 °C, the pH value was controlled at 7.8 at the end of the reaction, and the gelation time was controlled at 1.2 hours. After the reaction ended, aging was carried out. The aging temperature was 78 °C, the aging pH value was controlled at 7.5, and the aging time was 1.8 hours to obtain the first slurry. First, 800 mL of deionized water, 60 mL of rapeseed oil, and castor oil phosphate with a molar ratio of 1.3 to the total number of W atoms in sodium tungstate were added to the reaction tank 2. CO2 gas with a concentration of 88 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the Ni and Al solution B was 3.0. Then, a 10 wt% sodium carbonate solution, the first slurry, the Ni and Al solution B, and a sodium tungstate solution (the weight concentration of W in terms of WO3 was 40 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 60 °C, the initial pH value was controlled at 13.0, and by adjusting the pH value 6 times, the final pH value at the end was adjusted to 7.6, and the pH value adjusted each time was 0.9. After each adjustment to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 10 minutes. After the second gelation reaction ended, aging started. The aging temperature was 78 °C, the pH value was controlled at 8.0, and the aging time was 2.5 hours to obtain the second slurry. The aged slurry was filtered, and the filter cake was dried at 100 °C for 7 hours, rolled, and extruded into a clover shape. The formed strips were cured at 70 °C for 50 hours, then the temperature was lowered to 20 °C and curing continued for 30 hours. Washed with deionized water to neutral at room temperature. Then the wet strips were dried at 100 °C for 12.0 hours, and the dried material was calcined at 500 °C for 4 hours to obtain catalyst H. The catalyst composition and main properties are shown in Table 1.

[0070] Comparative Example 5

[0071] According to the method of Example 1, according to the component content ratio of catalyst A in Table 1, catalyst I was prepared, and the formed strips were not subjected to desalting treatment.

[0072] Nickel chloride and sodium silicate were respectively added to the dissolution tank 1 filled with deionized water to prepare a solution containing Ni and Si. In the Ni and Si solution, the weight concentration of Ni calculated as NiO was 28 g / L, and the weight concentration of SiO2 was 30 g / L. Nickel chloride and aluminum chloride solutions were respectively added to the dissolution tank 2 filled with deionized water to prepare a solution containing Ni and Al. In the solution containing Ni and Al, the weight concentration of Ni calculated as NiO was 24 g / L, and the weight concentration of Al calculated as Al2O3 was 30 g / L. Among them, the mass ratio of Ni in the Ni and Si solution used in the reaction of this example to Ni in the Ni and Al solution used was 14:12. The solution containing Ni and Si was put into the reaction tank 1, and sodium hydroxide solution (weight concentration 12%) and sodium molybdate solution (the weight concentration of Mo calculated as MoO3 was 36 g / L) were dropped into the reaction tank 1 for the first gelation reaction. The gelation temperature was maintained at 62 °C, the pH value was controlled at 7.8 at the end of the reaction, and the gelation time was controlled at 1.2 hours. After the reaction ended, aging was carried out. The aging temperature was 78 °C, the aging pH value was controlled at 7.5, and the aging time was 1.8 hours to obtain the first slurry. First, 800 mL of deionized water, 60 mL of rapeseed oil, and castor oil phosphate with a molar ratio of 1.3 to the total number of W atoms in sodium tungstate were added to the reaction tank 2. CO2 gas with a concentration of 88 v% was introduced into the reaction tank solution to saturate the CO2 concentration in the reactor liquid. The total addition amount of CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al was 3.0. Then, a 10 wt% sodium carbonate solution, the first slurry, the solution containing Ni and Al, and a sodium tungstate solution (the weight concentration of W calculated as WO3 was 40 g / L) were added to the reaction tank 2 in parallel for the second gelation reaction. The gelation temperature was maintained at 60 °C, the pH value was initially controlled at 13.0, and through 6 downward adjustments of the pH value, the final pH value at the end was adjusted to 7.6, and the pH value decreased each time was 0.9. After each adjustment to the adjusted value, the pH value of the adjusted reaction slurry was kept constant for 10 minutes. After the second gelation reaction ended, aging began. The aging temperature was 78 °C, the pH value was controlled at 8.0, and the aging time was 2.5 hours to obtain the second slurry. The aged slurry was filtered, and the filter cake was dried at 100 °C for 7 hours, rolled, and extruded into a clover shape. It was washed with deionized water at room temperature, and no formed product was obtained after washing. The powder was taken and dried at 100 °C for 12.0 hours, and the dried material was calcined at 500 °C for 4 hours to obtain catalyst I. The catalyst composition and main properties are shown in Table 1.

[0073] Comparative Example 6

[0074] According to the preparation method disclosed in CN106513006A, a reference agent J with a catalyst composition similar to that of Example 1 of the present invention was prepared. The specific process is as follows:

[0075] Nickel carbonate was uniformly mixed with 300 ml of deionized water and then added into a 1 L high-pressure ultrasonic reactor. The ultrasonic frequency was set at 60 KHz, and the mixture was heated to 80 °C. After maintaining the temperature for 1 h, the ultrasonic frequency was reduced to 20 KHz, and the system temperature was raised to 120 °C. Ammonium molybdate and 3 g of polyvinylpyrrolidone were added. Then, 10 ml of 25 wt% ammonia water was added dropwise into the system. After maintaining the temperature for 2 h, the ultrasonic was turned off, and stirring was started at a speed of 300 revolutions per minute. Ammonium metatungstate was added, and then citric acid was added until the pH of the system reached 4.2. After maintaining the temperature for 2 h, the heating was turned off. After the system cooled to room temperature, the slurry was collected and subjected to spray drying. The inlet temperature and outlet temperature were controlled at about 200 °C and 100 °C respectively. The obtained dried powder was calcined in a muffle furnace at 330 °C for 3 h to obtain the active component powder. The active component powder was mixed with aluminum hydroxide dry gel, and then 10% dilute nitric acid aqueous solution was added for kneading and extrusion to obtain a strip. The strip was dried at 110 °C for 10 h and calcined in a muffle furnace at 400 °C for 5 h to obtain the reference agent J. The catalyst composition and main properties are shown in Table 1.

[0076] Comparative Example 7

[0077] According to the preparation method disclosed in CN1951558A, the reference agent K was prepared as follows:

[0078] Deionized water was added into a dissolution tank, and nickel chloride, ammonium metatungstate and aluminum chloride were added and dissolved to prepare an acidic working solution A. In solution A, the weight concentration of Ni calculated as NiO was 74.8 g / L, the weight concentration of W calculated as WO3 was 48.6 g / L, and the weight concentration of Al calculated as Al2O3 was 44 g / L. The pH value of solution A was 1.8. 350 mL of deionized water was added into a reaction tank, and the temperature was raised to 62 °C. Under stirring, solution A and 10 wt% ammonia water were added into the reaction tank in a parallel flow to form a gel. The gelation temperature was 62 °C, the gelation time was 1 h, and the pH value of the slurry during the gelation process was 8.5. After the gelation was completed, it was aged for 2 h at an aging temperature of 75 °C, and the pH value during aging was controlled at 7.6. Then it was filtered, and the filter cake was added with 600 mL of deionized water and 32.6 g of molybdenum trioxide, and slurried and stirred evenly, then filtered. The filter cake was dried at 100 °C for 7 h, rolled, and extruded into a cylindrical shape. It was washed with deionized water at room temperature until neutral. Then the wet strip was dried at 100 °C for 12 h and calcined at 500 °C for 4 h to obtain the catalyst K. The catalyst composition and main properties are shown in Table 1.

[0079] Example 5

[0080] This example is an experiment for evaluating the activity of the catalyst of the present invention and is compared with the catalysts of the comparative examples. As can be seen from the physical and chemical properties of the catalysts in Table 1, when there is a relatively large amount of sodium-containing raw materials in the preparation process, during washing, catalysts A, B, and C of the present invention and comparative catalysts F, G, H, J, and K are respectively used (comparative catalysts E and I become powders after washing and are not subjected to activity evaluation). A comparative evaluation test is carried out on a 200 mL small-scale hydrogenation device. Mixed diesel (the weight ratio of straight-run diesel, coker diesel, and catalytic diesel is 28:20:52) is used as the test raw material. The process conditions for catalyst activity evaluation are: hydrogen partial pressure is 6.4 MPa, reaction temperature is 365 °C, liquid hourly space velocity is 2.0 h -1 , the hydrogen-oil volume ratio is 500:1, and the main properties of the raw materials are shown in Table 4. The results of catalyst activity evaluation are shown in Table 5. The types of sulfides in the hydrofined oil are detected by gas chromatography-atomic emission detector (GC-AED), and the results are shown in Table 6.

[0081] As can be seen from Table 1, when the catalysts of the present invention use relatively large amounts of sodium-containing raw materials in the preparation process, after forming and then undergoing desalting treatment and washing, the catalysts have good crushing strength, while without desalting treatment, the formed catalyst bars become powders after washing.

[0082] As can be seen from the evaluation results, compared with the catalysts of the comparative examples, the catalysts of the present invention show high hydrodesulfurization activity when removing difficult-to-treat large molecular sulfides such as 4,6-DMDBT, have excellent ultra-deep hydrodesulfurization activity, and at the same time, the diesel products have good yields. When the reaction space velocity of the activity evaluation is increased, the catalysts of the present invention still have excellent ultra-deep desulfurization activity by increasing the reaction temperature. Comparing with the evaluation results of the comparative example catalysts, the catalysts of the present invention effectively reduce the influence of the high-temperature hydrogenation pathway by the thermodynamic equilibrium and have good temperature adaptability. The hydrofining catalyst of the present invention has a relatively large pore volume and specific surface area, and the pore size distribution is mainly concentrated above 10 nm. When the catalyst of the present invention is used for processing light distillate oils, especially for processing inferior diesel distillates, it has excellent ultra-deep hydrodesulfurization and denitrification performance.

[0083] Table 1 Composition and properties of catalysts prepared in examples and comparative examples

[0084] Catalyst Number A B C D NiO, wt% 26 36 22 30 <![CDATA[WO3, wt%]]> 20 11 22 18 <![CDATA[MoO3, wt%]]> 18 20 18 14 <![CDATA[SiO2, wt%]]> 15 20 13 17 <![CDATA[Al2O3, wt%]]> 15 8 20 14 <![CDATA[P2O5, wt%]]> 6 5 5 7 <![CDATA[Na2O, %]]> 0.081 0.078 0.080 0.066 <![CDATA[Specific surface area, m 2 / g]]> 298 314 293 299 Pore Volume, mL / g 0.413 0.438 0.404 0.417 Pore Distribution < 4nm 5.42 5.13 5.88 5.38 4nm - 10nm 21.82 20.73 22.81 21.62 10nm - 15nm 41.95 42.38 41.28 42.08 > 15nm 30.81 31.76 30.03 30.92 Mechanical Strength, N / mm 19.6 19.2 19.8 19.5

[0085] Table 1 (continued) Composition and properties of catalysts prepared in examples and comparative examples

[0086] Catalyst Number E F G H I J K NiO, wt% 26 26 26 26 26 26 37.4 <![CDATA[WO3, wt%]]> 20 20 20 20 20 20 24.3 <![CDATA[MoO3, wt%]]> 18 18 18 18 18 18 16.3 <![CDATA[SiO2, wt%]]> 18 4 15 - 15 - - <![CDATA[Al2O3, wt%]]> 18 28 15 30 15 36 22 <![CDATA[P2O5, wt%]]> - 4 6 6 6 - - <![CDATA[Na2O, %]]> 0.34 0.14 0.092 0.084 0.49 0.13 0.13 <![CDATA[Specific surface area, m 2 / g]]> 142 199 265 297 259 283 174 Pore Volume, mL / g 0.232 0.252 0.378 0.409 0.368 0.385 0.301 Pore Distribution < 4nm 62.81 22.82 10.92 5.71 13.86 38.21 46.87 4nm - 10nm 30.52 71.44 33.12 21.90 40.21 48.61 40.72 10nm - 15nm 4.37 4.50 36.63 41.86 30.51 7.28 8.26 > 15nm 2.30 1.24 19.33 30.53 15.42 5.90 4.15 Mechanical Strength, N / mm - 17.6 18.1 18.9 - 13.5 19.1

[0087] Table 2 Composition of composite oxides in the core and shell of the catalysts obtained in each example (based on the mass of the catalyst)

[0088] Catalyst Number A B C D G H I Composite Oxide Composition in Core NiO, wt% 14 26 12 18 18 14 14 <![CDATA[MoO3, wt%]]> 18 20 18 14 11 18 18 <![CDATA[SiO2, wt%]]> 15 20 13 17 10 - 15 <![CDATA[WO3, wt%]]> - - - - 7 - - <![CDATA[Al2O3, wt%]]> - - - - 4 15 - <![CDATA[P2O5, wt%]]> - - - - 2 - - Composite Oxide Composition in Shell NiO, wt% 12 10 10 12 8 12 12 <![CDATA[WO3, wt%]]> 20 11 22 18 13 20 20 <![CDATA[Al2O3, wt%]]> 15 8 20 14 11 15 15 <![CDATA[MoO3, wt%]]> - - - - 7 - - <![CDATA[SiO2, wt%]]> - - - - 5 - - <![CDATA[P2O5, wt%]]> 6 5 5 7 4 6 6

[0089] Table 3 Average particle size and particle size distribution of the catalyst core-shell composite oxide particles obtained in each example

[0090] Catalyst Number A B C D E F Average Particle Size of Core - Shell Composite Oxide, nm 8.3 8.1 8.5 8.2 33.6 23.8 Particle Size Distribution of Core - Shell Composite Oxide, % Particle Size Less than 7nm 5.84 5.71 5.26 5.74 3.32 4.05 Particle Size of 7nm - 12nm 83.43 84.53 83.12 83.64 16.13 23.81 Particle Size Greater than 12nm 10.73 9.76 11.62 10.62 80.55 72.14

[0091] Table 3 (continued) Average particle size and particle size distribution of the catalyst core-shell composite oxide particles obtained in each example

[0092] Catalyst Number G H I J K Average Particle Size of Core - Shell Composite Oxide, nm 30.5 9.6 10.2 24.4 19.4 Particle Size Distribution of Core - Shell Composite Oxide, % Particle Size Less than 7nm 3.23 5.20 5.12 8.93 8.42 Particle Size of 7nm - 12nm 20.41 83.56 79.65 25.23 30.35 Particle Size Greater than 12nm 76.36 11.24 15.23 65.84 61.23

[0093] Table 4 Main properties of the feedstock oil

[0094] Item Analysis Result <![CDATA[Density (20 °C), g / cm 3 > 0.8897 Distillation Range, °C 175-379 S, µg / g 13100 N, µg / g 922

[0095] Table 5 Catalyst evaluation process conditions and activity evaluation results

[0096] Catalyst Number A B C F G H J K <![CDATA[Generated oil density (20 °C), g / cm 3 > 0.8636 0.8634 0.8639 0.8656 0.8715 0.8654 0.8732 0.8707 S, µg / g 6.7 6.0 6.9 38.2 142.3 35.1 236.8 118.8 N, µg / g 2.1 1.8 2.3 16.4 70.2 12.9 112.8 62. 2 Diesel Yield, % 99.1 99.2 99.2 86.6 98.8 99.1 98.3 98.9

[0097] Table 6 Contents of different sulfides in the hydrofined oil

[0098] Catalyst Number A B C F G H J K Sulfur Content in Hydrofined Oil, µg / g 6.7 6.0 6.9 38.2 142.3 35.1 236.8 118.8 <![CDATA[C1-DBT, µg / g]]> 0 0 0 3.2 12.5 4.6 22.1 9.1 4 - MDBT, µg / g 1.3 1.1 1.3 8.1 30.1 5.2 52.2 25.4 6 - MDBT, µg / g 1.8 1.5 1.9 9.6 31.4 9.2 60.2 26.3 4,6 - DMDBT, µg / g 3.6 3.4 3.5 17.3 68.3 16.1 102.3 58.0

Claims

1. A phosphorus-containing hydrofining catalyst, characterized in that: It contains core-shell structured composite oxide particles. Based on the mass of the core-shell structured composite oxide particles, the core phase accounts for 20% - 90%, and the shell phase accounts for 10% - 80%. Among them, the core phase is an amorphous composite oxide containing molybdenum, nickel, and silicon, and the shell phase is an amorphous composite oxide containing tungsten, nickel, aluminum, and phosphorus. The average particle size of the catalyst particles is 7 - 12 nm, and the particle size distribution of the core-shell structured composite oxide particles is as follows: the number of particles with a particle size less than 7 nm accounts for 2% - 15% of the total number of particles, the number of particles with a particle size of 7 nm - 12 nm accounts for 66% - 88% of the total number of particles, and the number of particles with a particle size greater than 12 nm accounts for 3% - 21% of the total number of particles. The pore size distribution of the phosphorus-containing hydrofining catalyst is as follows: the pore volume of pores with a diameter of less than 4 nm accounts for 1% - 10% of the total pore volume, the pore volume of pores with a diameter of 4 - 10 nm accounts for 12% - 40% of the total pore volume, the pore volume of pores with a diameter of 10 - 15 nm accounts for 22% - 56% of the total pore volume, and the pore volume of pores with a diameter of more than 15 nm accounts for 18% - 45% of the total pore volume. The Na2O content in the catalyst is less than 0.12%.

2. The catalyst according to claim 1, wherein: The pore size distribution is as follows: the pore volume of pores with a diameter of less than 4 nm accounts for 2% - 8% of the total pore volume, the pore volume of pores with a diameter of 4 - 10 nm accounts for 14% - 36% of the total pore volume, the pore volume of pores with a diameter of 10 - 15 nm accounts for 24% - 54% of the total pore volume, and the pore volume of pores with a diameter of more than 15 nm accounts for 20% - 42% of the total pore volume.

3. The catalyst according to claim 1, characterized in that: The molar ratio of tungsten to nickel atoms in the shell phase is 1:22 - 8:

1. The content of aluminum, calculated as Al2O3, accounts for 5% - 30% of the mass of the hydrofining catalyst, and the content of phosphorus, calculated as P2O5, accounts for 2% - 15% of the mass of the hydrofining catalyst.

4. The catalyst according to claim 1, characterized in that: The molar ratio of molybdenum to nickel atoms in the core phase is 1:28 - 12:

1. The content of silicon, calculated as SiO2, accounts for 2% - 38% of the mass of the hydrofining catalyst.

5. The catalyst according to claim 1, wherein: The mass of NiO in the core phase accounts for 30% - 80% of the total mass of NiO in the hydrofining catalyst, and the mass of NiO in the shell phase accounts for 20% - 70% of the total mass of NiO in the hydrofining catalyst.

6. The catalyst according to claim 1, characterized in that: The specific surface area is 180 to 700 m 2 / g, and the pore volume is 0.30 to 0.90 mL / g.

7. A method for preparing a phosphorus-containing hydrofining catalyst according to any one of claims 1 to 6, characterized in that It includes the following steps: (1) Carry out a first gelling reaction on a sodium molybdate solution, a solution containing Ni and Si, and a first precipitant. After the reaction, perform first aging to obtain a first slurry containing Ni, Si, and Mo. (2) Add deionized water, an oily liquid, and a phosphate ester into a reactor, introduce CO2 gas to saturate the CO2 concentration in the reactor liquid, and then co-feed a solution containing Ni and Al, a sodium tungstate solution, a second precipitant, and the first slurry into the reactor to carry out a second gelling reaction. After the reaction, perform second aging to generate a second slurry. (3) Age the second slurry. After the aging is completed, carry out solid-liquid separation. The solid phase undergoes drying and forming processes to obtain a formed product. (4) Carry out desalting treatment on the formed product, wash, dry, and calcine it to obtain the hydrofining catalyst.

8. The method according to claim 7, wherein: In the sodium molybdate solution in step (1), the weight concentration of Mo calculated as MoO3 is 5 - 110 g / L; in the solution containing Ni and Si, the weight concentration of Ni calculated as NiO is 5 - 120 g / L, and the weight concentration of Si calculated as SiO2 is 2 - 80 g / L; the first precipitant is an aqueous solution of a nitrogen-free basic compound, and the weight concentration of the first precipitant is 5% - 30%.

9. The method according to claim 7, wherein: The conditions for the first gelation reaction in step (1) are: the reaction temperature is 30 - 90 °C, the pH value is 7.0 - 11.0, and the gelation time is 0.2 - 2.5 hours.

10. The method according to claim 7, characterized in that: The first aging conditions in step (1) are as follows: the aging temperature is 60 - 90 °C, the pH value is 7.0 - 11.0, and the aging time is 0.3 - 2.5 hours.

11. The method according to claim 7, characterized in that: In the solution containing Ni and Al in step (2), the weight concentration of Ni calculated as NiO is 5 - 110 g / L, and the weight concentration of Al calculated as Al2O3 is 2 - 95 g / L; in the sodium tungstate solution, the weight concentration of W calculated as WO3 is 4 - 140 g / L.

12. The method according to claim 7, wherein: The second precipitant in step (2) is a basic precipitant, selected from aqueous solutions of sodium carbonate and / or sodium bicarbonate, and the weight concentration of the second precipitant is 5% - 40%.

13. The method according to claim 7, characterized in that: The volume ratio of the deionized water added in step (2) to the volume of the first slurry obtained in step (1) is 0.1:1 - 3:

1.

14. The method according to claim 7, characterized in that: The volume concentration of the CO2 gas introduced into the deionized water in step (2) is 70 v% - 99 v%; after the CO2 in the water is saturated; the total addition amount of the CO2 gas and the molar ratio of Al2O3 in the solution containing Ni and Al is 1:1 - 7:

1.

15. The method according to claim 7, wherein: The oily liquid in step (2) is an unsaturated higher fatty acid glyceride, selected from one or more of peanut oil, rapeseed oil, cottonseed oil, sunflower seed oil, soybean oil, corn oil, tea oil, and olive oil.

16. The method according to claim 7, wherein: The volume ratio of the oily liquid to the deionized water is 1:60 - 1:

4.

17. The method according to claim 7, characterized in that: The phosphate esters in step (2) are one or more of octadecyl ether phosphate, alkylphenol ether phosphate, isomeric tridecanol ether phosphate, lauryl alcohol ether phosphate, castor oil phosphate, octadecyl phosphate, and lauryl phosphate; the molar ratio of the addition amount of the phosphate ester to the total number of W atoms in the sodium tungstate solution in step (2) is 0.3:1 - 3.0:

1.

18. The method according to claim 7, wherein: The conditions for the second gelation reaction in step (2) are: the reaction temperature is 30 - 90 °C, the pH value is initially controlled at 10.0 - 14.0, and the final pH value at the end is 7.0 - 8.5, and the gelation reaction time is 0.5 - 6.0 hours.

19. The method according to claim 18, characterized in that: The pH value is adjusted downward in steps from the initial value to the final pH value. The method of adjusting downward in steps is to adjust the pH value to the required value for that time and keep the pH value of this reaction slurry constant until the next downward adjustment starts. The number of downward adjustments is 2 - 10 times.

20. The method according to claim 7, characterized in that: The second aging conditions in step (2) are as follows: the aging temperature is 40 - 90 °C, the aging time is 1 - 5 hours, and the pH value is 7.0 - 11.

0.

21. The method according to claim 7, characterized in that: The aging conditions described in step (2) are carried out as follows. The first step is atmospheric pressure aging: the aging temperature is 30 - 90 °C, the aging time is 1 - 6 hours, and the pH value is 6.5 - 10.

0. The second step is high-pressure aging: the temperature is 100 - 195 °C, the time is 0.1 - 3.5 hours, the pressure is not less than 10 MPa, and the pH value is 10.0 - 13.

0.

22. The method according to claim 7, characterized in that: During the forming process described in step (3), an extrusion aid and a peptizing agent are added. The extrusion aid is one or more of sesbania powder, carbon black, graphite powder, or cellulose. The peptizing agent is an acid solution containing one or more of hydrochloric acid, sulfuric acid, and acetic acid. The dosage of the extrusion aid accounts for 1 wt% - 10 wt% of the dry basis of the total material.

23. The method according to claim 7, wherein: The desalting treatment process described in step (4): First, curing is carried out, and then washing is carried out to remove the salt precipitated on the surface of the formed product. The curing conditions are a temperature of 5 - 100 °C and a time of 10 - 100 hours.

24. The method according to claim 7, wherein: The desalting treatment described in step (4) is carried out as follows: In the first stage, the temperature is 60 - 90 °C for curing, and the time is 5 - 60 hours. In the second stage, the temperature is 10 - 30 °C, the time is 1 - 48 hours, and then washing is carried out to remove the precipitated salt.

25. Use of a phosphorus-containing hydrofining catalyst according to any one of claims 1 - 6 in the hydrofining reaction of inferior diesel oil.

26. The application according to claim 25, characterized in that: The conditions for the hydrofining reaction of inferior diesel are as follows: the reaction temperature is 330 - 400 °C, the reaction pressure is 2.5 - 17 MPa, the hydrogen-oil volume ratio is 250:1 - 1200:1, and the liquid hourly space velocity is 0.3 - 5.0 h -1 .

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