Preparation method of diesel oil hydrofining catalyst

Abstract

The invention discloses a preparation method of a diesel hydrofining catalyst, which comprises the following steps: (1) taking a mixed solution A as coprecipitation reaction bottom water, and dropwise adding a mixed solution B and an alkaline working solution into the mixed solution A in a parallel flow manner to obtain slurry D; the mixed solution A is an aqueous solution containing polyvinylpyrrolidone and nickel salt; the mixed solution B is a mixed solution containing sodium tungstate and sodium molybdate; (2) performing vacuum filtration on the slurry D to obtain a filter cake, and curing the filter cake; and (3) after the curing is finished, adding deionized water into the filter cake for vacuum filtration to obtain a sodium-removed filter cake, and then drying, forming and roasting to obtain the diesel oil hydrofining catalyst. According to the invention, the sodium-containing raw material which is low in price and environment-friendly is adopted, and through a specific impurity removal method and addition of a special auxiliary agent, the problems that a bulk phase catalyst is difficult to form, poor in strength and capable of inhibiting hydrogenation activity when the content of impurity sodium is high are solved, and meanwhile, the pore structure property and the dispersity and the utilization rate of active metal are well improved.

Description

Technical Field

[0001] The invention belongs to the field of hydrogenation catalyst preparation, and specifically relates to a method for preparing a diesel hydrogenation refining catalyst. Background Art

[0002] As environmental regulations become increasingly stringent, oil quality requirements are gradually increasing. After the sulfur content requirement for diesel quality upgrades has been reduced to below 10μg / g, the requirements for aromatic content are also becoming stricter. The most effective way to meet the requirements for oil quality upgrades is to use high hydrogenation activity catalysts. Therefore, as a fully metal phase bulk catalyst, its excellent hydrogenation performance is very suitable for diesel quality upgrades in refineries.

[0003] The preparation methods of hydrotreating catalysts can be divided into impregnation, kneading, beating, ion exchange and co-precipitation. Bulk catalysts are generally prepared by kneading or co-precipitation. The kneading method is difficult to obtain a catalyst with a high metal content due to the difficulty of molding. At the same time, due to the limitations of the preparation method, it is difficult to evenly mix the active metal components, which cannot promote the synergistic effect between the active metals, making it difficult for the catalyst to fully exert its activity.

[0004] The ionic reaction characteristics of the coprecipitation method allow the components to be mixed evenly; at the same time, it uses relatively low-priced sodium-containing raw materials, which greatly reduces the cost of catalyst raw materials and the cost of treating nitrogen-containing wastewater. However, the introduction of a large amount of sodium ions makes it difficult to remove the sodium ions in the catalyst. A large amount of sodium ions still exist in the precipitated material. The residual sodium ions cause the material to have poor adhesion and are difficult to form; the unremoved sodium ions are not conducive to the formation of the catalyst pore structure, resulting in a smaller pore volume and pore size of the catalyst; and too high a sodium content in the catalyst will reduce its hydrogenation activity.

[0005] CN1339985A discloses a method for preparing a mixed metal catalyst composition, and CN101153228A discloses a multi-metal bulk catalyst for ultra-deep hydrodesulfurization of diesel. The above patents all adopt a co-precipitation method to prepare hydrogenation catalysts, but the pore structures of the prepared catalysts are not ideal, and the pore volumes and pore diameters are small.

[0006] CN114471593A and CN114471594A both disclose a method for preparing a hydrorefining catalyst. This method also adopts a coprecipitation method for preparation, and performs a sodium salt removal treatment. This method selects to remove the sodium salt after the catalyst is extruded, but in the actual catalyst preparation process, when the sodium salt content is too high, the catalyst cannot be formed or the strength after forming is small, so when this method is used, there are certain requirements for the sodium content of the catalyst preparation raw material; at the same time, due to the presence of a large amount of sodium ions in the coprecipitation reaction product, this method will precipitate some sodium chloride crystals attached to its internal pores during the drying process of the coprecipitation reactant, which will also have an adverse effect on the formation of the catalyst pore structure.

[0007] CN109692693B discloses a hydrorefining catalyst and a preparation method thereof, wherein the method adopts a two-cocurrent precipitation method to prepare a mixed precipitate containing tungsten, molybdenum and nickel as active metals, and the steps of aging, drying, molding and roasting are performed in the process to successfully prepare the hydrorefining catalyst. However, the method fails to effectively control the particle size of the product during the cocurrent coprecipitation reaction, especially in the second cocurrent coprecipitation, the previous product slurry is coprecipitated again, which will cause the final product particles to aggregate excessively or the particle size to be uneven, thereby affecting the active metal distribution of the catalyst and affecting the pore structure, thereby affecting the hydrogenation activity of the catalyst. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a method for preparing a diesel hydrofining catalyst. The present invention adopts a low-cost and environmentally friendly sodium-containing raw material, solves the problems of difficult bulk catalyst molding, poor strength and inhibition of hydrogenation activity when the sodium impurity content is high, and improves the pore structure properties and the dispersion and utilization rate of active metals by using a specific impurity removal method and the addition of special additives.

[0009] The preparation method of the diesel hydrorefining catalyst of the present invention comprises the following contents: (1) Mixed solution A is used as the bottom water for the coprecipitation reaction, and mixed solution B and alkaline working solution are added dropwise to mixed solution A in parallel to perform a coprecipitation reaction, thereby obtaining slurry D; wherein mixed solution A is an aqueous solution containing polyvinyl pyrrolidone (PVP) and nickel salt; and mixed solution B is a mixed solution containing sodium tungstate and sodium molybdate; (2) vacuum filtering the slurry D, and curing the filter cake after obtaining it; (3) After the curing is completed, the filter cake is placed in a vacuum filter, and deionized water is added to the filter cake for the first vacuum filtration, and the filtration is stopped when there is no suspended liquid on the surface of the filter cake; deionized water is continued to be added for the second vacuum filtration, and the filtration is stopped when there is no suspended liquid on the surface of the filter cake; deionized water is added again for the third vacuum filtration, and the filtration is stopped when no filtrate drips, to obtain a sodium-free filter cake, which is then dried, formed, and calcined to obtain a diesel hydrotreating catalyst.

[0010] In the method of the present invention, the molar ratio of sodium molybdate to sodium tungstate in the mixed solution B of step (1) is 1:0.1-10, preferably 1:0.2-0.75; the concentration range of the mixed aqueous solution B is (in terms of the molar concentration of WO3+MoO3) 0.01-1 mol / L, preferably 0.1-0.8 mol / L.

[0011] In the method of the present invention, the number average relative molecular weight of PVP in the mixed solution A of step (1) is in the range of 2500 to 60000, preferably in the range of 5000 to 58000, such as the model of PVP: K12, K15, K17, K25 or K30, preferably the PVP model is K30; the mass concentration of PVP is 10 to 60 g / L, preferably 20 to 35 g / L.

[0012] In the method of the present invention, the nickel salt in the mixed solution A of step (1) needs to be a soluble nickel salt, such as one or more of nickel acetate, nickel nitrate or nickel chloride; the molar concentration of the nickel salt is 0.1-1.2 mol / L, preferably 0.5-0.8 mol / L, calculated as NiO.

[0013] In the method of the present invention, the alkaline working solution in step (1) is one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate solution, and the pH value of the alkaline working solution is not less than 11.5, preferably the pH value is 12-13.

[0014] In the method of the present invention, in the coprecipitation reaction of step (1), the amounts of mixed solution A and mixed solution B are determined according to the active metal ratio of the hydrorefining catalyst, and the active metal mass ratio is preferably (WO3+MoO3):NiO=1:0.4~1.

[0015] In the method of the present invention, in the coprecipitation reaction of step (1), the reaction pH is measured online, and during the reaction, the pH value of the reaction solution system is maintained in the range of 6.9 to 7.8, preferably 7.2 to 7.5, by controlling the dropping speed of the alkaline working solution.

[0016] In the method of the present invention, the coprecipitation reaction temperature in step (1) is 30-95° C., preferably 50-70° C.; the reaction time is 15-120 minutes, preferably 45-90 minutes.

[0017] In the method of the present invention, the curing conditions in step (2) are as follows: the ambient humidity is greater than 78%; the curing temperature is 25°C to 55°C, preferably 38°C to 48°C; the curing time is 0.5 to 3 hours, preferably 0.8 to 2 hours; the curing process can be carried out in any environment that meets the above conditions, preferably directly in a vacuum filtration device.

[0018] In the method of the present invention, after the curing in step (2), the water content of the filter cake is 75wt% to 95wt%, preferably 80wt% to 85wt%.

[0019] In the method of the present invention, the first vacuum filtration in step (3) is performed at a ratio of the mass of deionized water to the mass of the final catalyst preparation of 2 to 6:1, preferably 3 to 4:1.

[0020] In the method of the present invention, the second vacuum filtration in step (3) is performed at a ratio of the mass of deionized water to the mass of the final catalyst preparation of 0.5 to 2:1, preferably 0.8 to 1.5:1.

[0021] In the method of the present invention, the third vacuum filtration in step (3) is performed at a ratio of the mass of deionized water to the mass of the final catalyst preparation of 1 to 3:1, preferably 1.5 to 2:1.

[0022] In the method of the present invention, during the first, second and third vacuum filtration processes described in step (3), the deionized water cannot be stirred with the filter cake. After the deionized water is added above the filter cake, the vacuum filtration process can be carried out.

[0023] In the method of the present invention, the drying temperature in step (3) is 50-120° C., preferably 70-100° C.; the drying dry basis is controlled to be 38wt%-68wt%, preferably 40wt%-55wt%.

[0024] In the method of the present invention, the calcination temperature in step (3) is 300-550° C., preferably 400-500° C., and the calcination time is 6-12 hours.

[0025] The present invention provides a bulk hydrogenation refining catalyst, wherein the active components of the catalyst are oxides of tungsten, molybdenum and nickel, and the content of the active components is greater than 95wt%; and the sodium content in the catalyst is ≯0.1%.

[0026] The bulk hydrorefining catalyst of the present invention has a specific surface area of ​​240 to 420 m 2 / g, pore volume 0.28~0.45mL / g, catalyst strength 16.0~24.0N·mm -1 .

[0027] The catalyst needs to be sulfided when used. When the active center of the sulfidation hydrogenation is formed, nickel is more easily sulfided than tungsten and molybdenum, which easily leads to phase separation of nickel and tungsten (or molybdenum) during the sulfidation process, so that the outer surface of the active phase of the catalyst is in a nickel-rich state after sulfidation, thereby making tungsten (or molybdenum) at a disadvantage in the competitive adsorption process of the reaction, which is not conducive to the hydrogenation activity of the catalyst. The method of the present invention maintains a stable coprecipitation process by adding PVP to the bottom water of the reaction, and the formed mixed oxides of nickel, molybdenum and tungsten are more uniform, and will not cause the aggregation of nickel oxides. The sulfidation of nickel occurs during the formation of the Mo(W)S2 active phase, so that the outer surface of Mo(W)S2 is in a state where nickel and tungsten (or molybdenum) exist in a mixed state, thereby improving the utilization rate of the active metals of the catalyst. PVP plays a role in stabilizing the colloid particles and adjusting the particle size during the coprecipitation reaction, avoiding the generated product particles from being too large, causing the active metals to aggregate, or the reaction system being unstable, causing the generated particles to be of different sizes, thereby affecting the pore structure and hydrogenation activity of the catalyst.

[0028] The method of the present invention adopts clean, environmentally friendly and low-cost sodium-containing raw materials. The catalyst precursor generated by the coprecipitation reaction contains a large amount of sodium ions. The present invention removes the sodium ions within a short time after the preparation of the catalyst precursor is completed, thereby reducing the adsorption degree of the sodium ions on the catalyst increased due to the subsequent drying and extrusion treatment, making it easier to remove the impurities, and the impurity removal efficiency is high. At the same time, compared with traditional pulping washing, the curing and vacuum filtration washing in the present invention can take away the aqueous solution containing a large amount of impurity sodium in the precursor filter cake through a small amount of water, so as to meet the requirement that the sodium content in the filter cake is ≯0.1%, thereby reducing the number of washing times and greatly reducing the water consumption in the catalyst preparation process, and solving the problems that the catalyst precursor is difficult to shape when the sodium content is too high, the strength after shaping is small, and the influence on the hydrogenation activity of the catalyst.

[0029] In the curing process, the method of the present invention causes part of the hydrated sodium ions in the filter cake to precipitate from the filter cake and retain vacancies, thereby increasing the pore volume of the catalyst precursor. In step (3), the filter cake from which the sodium impurity has been removed is subjected to temperature-controlled drying, which has a significant pore expansion effect. During the drying process, the moisture in the filter cake is rapidly diffused outward in the form of water vapor, which impacts the pore structure, causing the pores inside the filter cake to become larger, and the pore distribution to move toward the macropore direction, thereby ultimately increasing the pore volume and pore diameter of the catalyst. At the same time, due to the removal of the sodium impurity, sodium chloride crystals will not be precipitated during the drying process and adhere to the pores inside the filter cake to affect the pore expansion, so the pore expansion effect during the drying process is more significant than that after the sodium impurity is removed after the catalyst is formed. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The PVP used in the following embodiments and comparative examples, model K30 is produced by Sinopharm Chemical Reagent Co., Ltd., and model K15 is produced by Meilun Biotechnology Co., Ltd. The catalyst test characterization method uses an Agilent inductively coupled plasma mass spectrometer (7700 ICP-MS) for elemental analysis; the catalyst specific surface area and pore size are measured on an American ASAP-2405 BET nitrogen adsorption instrument; the catalyst crushing strength is measured on a particle strength tester. Example 1

[0031] Prepare a mixed solution B of sodium molybdate and sodium tungstate: the molar concentration of sodium molybdate is 0.6mol / L, and the molar concentration of sodium tungstate is 0.2mol / L; prepare an alkaline precipitant sodium hydroxide solution, and the pH value of the solution is 13.0; prepare a mixed solution A: the concentration of nickel chloride is 0.6mol / L, and the PVP model is K30, with a concentration of 20g / L.

[0032] The mixed solution A was heated to 65°C and then reacted: the mixed solution B and the alkaline precipitant were added dropwise to the mixed solution A in parallel, the reaction temperature was 65°C, the reaction pH was measured online, and the pH was maintained in the range of 7.2 to 7.3. After 80 minutes, the reaction was completed to obtain a product slurry D.

[0033] Filter the slurry D to obtain the product filter cake for filter cake curing: the curing is directly carried out in a vacuum filter, the curing environment humidity is greater than 85%, the curing temperature is 45°C, the curing is 1.5 hours, and the moisture content of the filter cake after the curing is 85%; Add deionized water in a mass ratio of 4:1 to the final catalyst preparation to the top of the filter cake of the vacuum filter, and vacuum filter until there is no suspended liquid on the surface of the filter cake; continue to add deionized water in a mass ratio of 1:1 to the final catalyst preparation to the top of the filter cake, and vacuum filter until there is no suspended liquid on the surface of the filter cake; add deionized water in a mass ratio of 1.5:1 to the final catalyst preparation to the top of the filter cake again, and vacuum filter until there is no filtrate dripping from the filter cake, and the washing is completed.

[0034] The sodium-removed filter cake was dried at 90°C, and the drying was stopped when the filter cake base reached 50wt%; the cake was rolled and extruded into a clover-shaped strip; the strip was calcined at 500°C for 8h to obtain a diesel hydrorefining catalyst a, the main properties of which are shown in Table 1. Example 2

[0035] Prepare a mixed solution B of sodium molybdate and sodium tungstate: the molar concentration of sodium molybdate is 0.4mol / L, and the molar concentration of sodium tungstate is 0.3mol / L; prepare a mixed solution of alkaline precipitants sodium carbonate and sodium hydroxide, and the pH value of the solution is 12.5; prepare a mixed solution A: the concentration of nickel acetate is 0.8mol / L, the PVP model is K15, and the concentration is 30g / L.

[0036] The mixed solution A was heated to 70°C and then reacted: the mixed solution B and the alkaline precipitant were added dropwise to the mixed solution A in parallel, the reaction temperature was 70°C, the reaction pH was measured online, and the pH was maintained in the range of 7.4 to 7.5. After 70 minutes, the reaction was completed to obtain a product slurry D.

[0037] Filter the slurry D to obtain the product filter cake for filter cake curing: the curing is directly carried out in a vacuum filter, the curing environment humidity is greater than 80%, the curing temperature is 50°C, the curing is 1.2h, and the moisture content of the filter cake after the curing is 81%; Add deionized water in a mass ratio of 3:1 to the final catalyst preparation to the top of the filter cake of the vacuum filter, and vacuum filter until there is no suspended liquid on the surface of the filter cake; continue to add deionized water in a mass ratio of 1.2:1 to the final catalyst preparation to the top of the filter cake, and vacuum filter until there is no suspended liquid on the surface of the filter cake; add deionized water in a mass ratio of 1:1 to the final catalyst preparation to the top of the filter cake again, and vacuum filter until there is no filtrate dripping from the filter cake, and the washing is completed.

[0038] The sodium-removed filter cake was dried at 70°C and the drying was stopped when the filter cake base reached 54 wt%; the cake was rolled and extruded into a clover-shaped strip; the strips were calcined at 480°C for 9 h to obtain a diesel hydrotreating catalyst b, the main properties of which are shown in Table 1. Example 3

[0039] Prepare a mixed solution B of sodium molybdate and sodium tungstate: the molar concentration of sodium molybdate is 0.2mol / L, and the molar concentration of sodium tungstate is 0.2mol / L; prepare an alkaline precipitant sodium bicarbonate solution, and the pH value of the solution is 13.5; prepare a mixed solution A: the concentration of nickel nitrate is 0.4mol / L, and the PVP model is K30, with a concentration of 40g / L.

[0040] The mixed solution A was heated to 50°C and then reacted: the mixed solution B and the alkaline precipitant were added dropwise to the mixed solution A in parallel, the reaction temperature was 50°C, the reaction pH value was measured online, and the pH value was maintained in the range of 6.9 to 7.0. After 55 minutes, the reaction was completed to obtain a product slurry D.

[0041] Filter the slurry D to obtain the product filter cake and perform filter cake curing: the curing is directly carried out in a vacuum filter, the curing environment humidity is greater than 90%, the curing temperature is 35°C, the curing is 2.5 hours, and the moisture content of the filter cake after the curing is 92%; Add deionized water in a mass ratio of 5:1 to the final catalyst preparation to the top of the filter cake of the vacuum filter, and vacuum filter until there is no suspended liquid on the surface of the filter cake; continue to add deionized water in a mass ratio of 0.6:1 to the final catalyst preparation to the top of the filter cake, and vacuum filter until there is no suspended liquid on the surface of the filter cake; add deionized water in a mass ratio of 2:1 to the final catalyst preparation to the top of the filter cake again, and vacuum filter until there is no filtrate dripping from the filter cake, and the washing is completed.

[0042] The sodium-removed filter cake was dried at 110°C and the drying was stopped when the filter cake base reached 60wt%; the cake was rolled and extruded into a clover-shaped strip; the strips were calcined at 520°C for 5h to obtain a diesel hydrorefining catalyst c, the main properties of which are shown in Table 1. Example 4

[0043] Prepare a mixed solution B of sodium molybdate and sodium tungstate: the molar concentration of sodium molybdate is 0.3mol / L, and the molar concentration of sodium tungstate is 0.6mol / L; prepare an alkaline precipitant sodium hydroxide solution, and the pH value of the solution is 11.8; prepare a mixed solution A: the concentration of nickel chloride is 1.0mol / L, and the PVP model is K15, with a concentration of 15g / L.

[0044] The mixed solution A was heated to 80°C and then reacted: the mixed solution B and the alkaline precipitant were added dropwise to the mixed solution A in parallel, the reaction temperature was 80°C, the reaction pH was measured online, and the pH was maintained in the range of 7.1 to 7.2. After 100 minutes, the reaction was completed to obtain a product slurry D.

[0045] The slurry D was filtered to obtain the product filter cake for filter cake curing: the curing was directly carried out in a vacuum filter, the curing environment humidity was greater than 93%, the curing temperature was 54°C, the curing was 1.8 hours, and the moisture content of the filter cake after the curing was 77%; Add deionized water in a mass ratio of 2.5:1 to the final catalyst preparation to the top of the filter cake of the vacuum filter, and vacuum filter until there is no suspended liquid on the surface of the filter cake; continue to add deionized water in a mass ratio of 2.5:1 to the final catalyst preparation to the top of the filter cake, and vacuum filter until there is no suspended liquid on the surface of the filter cake; add deionized water in a mass ratio of 2.5:1 to the final catalyst preparation to the top of the filter cake again, and vacuum filter until there is no filtrate dripping from the filter cake, and the washing is completed.

[0046] The sodium-removed filter cake was dried at 60°C and the drying was stopped when the filter cake base reached 45wt%; the cake was rolled and extruded into a clover-shaped strip; the strip was calcined at 450°C for 11h to obtain a diesel hydrotreating catalyst d, the main properties of which are shown in Table 1.

[0047] Comparative Example 1 The other steps of this example are the same as those of Example 1, except that the auxiliary agent PVP is not added to solution A in this comparative example.

[0048] Finally, catalyst e was obtained, and its main properties are shown in Table 1.

[0049] Comparative Example 2 The other steps of this example are the same as those of Example 1, except that the concentration of the auxiliary agent PVP K30 added to solution A in this comparative example is 140 g / L.

[0050] Finally, catalyst f was obtained, and its main properties are shown in Table 1.

[0051] Comparative Example 3 The other steps of this example are the same as those of Example 1, except that the curing process of step (2) is not performed in this comparative example.

[0052] Finally, catalyst g was obtained, and its main properties are shown in Table 1.

[0053] Comparative Example 4 Prepare a mixed solution B of sodium molybdate and sodium tungstate: the molar concentration of sodium molybdate is 0.6mol / L, and the molar concentration of sodium tungstate is 0.2mol / L; prepare an alkaline precipitant sodium hydroxide solution, and the pH value of the solution is 13.0; prepare a mixed solution A: the concentration of nickel chloride is 0.6mol / L, and the PVP model is K30, with a concentration of 20g / L.

[0054] The mixed solution A was heated to 65°C and then reacted: the mixed solution B and the alkaline precipitant were added dropwise to the mixed solution A in parallel, the reaction temperature was 65°C, the reaction pH was measured online, and the pH was maintained in the range of 7.2 to 7.3. After 80 minutes, the reaction was completed to obtain a product slurry D.

[0055] The slurry D was filtered to obtain a product filter cake, and deionized water in a mass ratio of 6.5:1 to the final catalyst preparation was added to the filter cake for slurry washing. After completion, vacuum filtration was performed until no filtrate dripped from the filter cake, and washing was completed.

[0056] The sodium-removed filter cake was dried at 90°C and the drying was stopped when the filter cake base reached 50wt%; the cake was rolled and extruded into a clover-shaped strip; the formed strips were calcined at 500°C for 8h to obtain a diesel hydrorefining catalyst h, the main properties of which are shown in Table 1.

[0057] Comparative Example 5 Prepare a mixed solution B of sodium molybdate and sodium tungstate: the molar concentration of sodium molybdate is 0.6mol / L, and the molar concentration of sodium tungstate is 0.2mol / L; prepare an alkaline precipitant sodium hydroxide solution, and the pH value of the solution is 13.0; prepare a mixed solution A: the concentration of nickel chloride is 0.6mol / L, and the PVP model is K30, with a concentration of 20g / L.

[0058] The mixed solution A was heated to 65°C and then reacted: the mixed solution B and the alkaline precipitant were added dropwise to the mixed solution A in parallel, the reaction temperature was 65°C, the reaction pH was measured online, and the pH was maintained in the range of 7.2 to 7.3. After 80 minutes, the reaction was completed to obtain a product slurry D.

[0059] The slurry D was filtered to obtain a product filter cake, which was dried at 90°C. The drying was stopped when the filter cake base was 50wt%; the cake was rolled and extruded into a clover-shaped strip; the impurity sodium was removed according to the method disclosed in CN114471594A: the molded product was cured at 70°C for 50 hours, then the temperature was reduced to 20°C and the curing was continued for 30 hours. It was washed twice with clean water, and the ratio of deionized water to catalyst preparation mass was 6.5:1. The wet strip was dried at 80°C for 10 hours and calcined at 500°C for 8 hours to obtain diesel hydrofining catalyst i, and the main properties are shown in Table 1. Example 5

[0060] This example is an activity evaluation experiment of the catalyst of the present invention, and is compared with the catalyst of the comparative example. The comparative evaluation experiment was carried out on a 200mL small hydrogenation device using the catalysts a and b of the present invention and the catalysts of comparative examples e, f, g, h, and i.

[0061] The sulfidation process adopts wet sulfidation, adding carbon disulfide as sulfiding oil in aviation kerosene, and the amount of sulfiding agent used is 120% of the theoretical sulfur required for complete sulfidation of each active metal in the hydrorefining catalyst. The pre-sulfidation conditions are: firstly, the temperature is raised to 150℃, the hydrogen pressure is 8.0MPa, and the volume space velocity is 2.0h -1 , vulcanization time 4h; then temperature 230℃, hydrogen pressure 8.0MPa, volume space velocity 2.0h -1 , vulcanization time 4h; finally, temperature rise to 320℃, hydrogen pressure 8.0MPa, volume space velocity 2.0h -1 , vulcanization time 4h, vulcanization is completed.

[0062] Evaluation conditions: total reaction pressure 6.8MPa, hydrogen-oil volume ratio 500:1, volumetric space velocity 1.5h -1 , reaction temperature 360°C, feedstock oil properties are shown in Table 2, and Table 3 is the catalyst evaluation results.

[0063] From the evaluation results, it can be seen that the hydrogenation activities of catalysts a and b prepared by the present invention are better than those of the comparative examples, indicating that the catalysts prepared by the method of the present invention have good pore distribution, the pore volume and pore diameter of the catalysts are increased, and the addition of an appropriate amount of PVP during the reaction makes the particle size of the coprecipitated product uniform and suitable. At the same time, the oxides of nickel, molybdenum and tungsten are more uniform, and the subsequent sulfidation of nickel occurs during the formation of the Mo(W)S2 active phase, so that the outer surface of Mo(W)S2 is in a state of mixed existence of nickel and tungsten (or molybdenum), which improves the utilization rate of the active metals of the catalyst. Therefore, the hydrodesulfurization, denitrogenation and aromatic saturation performance of catalyst a are better than those of catalysts e and f. Comparative catalysts g, h and i were not subjected to the removal of impurity sodium according to a specific method. The evaluation results show that the method of the present invention has a good effect on the removal of sodium from the catalyst precursor and promotes the activity of the catalyst.

[0064] Table 1 Composition and properties of catalysts prepared in Examples and Comparative Examples Catalyst No. a b c d e f g h i Catalyst composition <![CDATA[MoO3,wt%]]> 50.0 40.0 25.0 20.0 50.0 50.0 50.0 50.0 50.0 <![CDATA[WO3,wt%]]> 16.7 30.0 25.0 40.0 16.7 16.7 16.7 16.7 16.7 NiO,wt% 33.3 30.0 50.0 40.0 33.3 33.3 33.3 33.3 33.3 Na, ppm 185 264 221 473 276 149 2443 25102 1535 <![CDATA[Specific surface area, m 2 / g]]> 387 395 372 364 394 406 384 343 376 Pore ​​volume, mL / g 0.412 0.427 0.416 0.389 0.396 0.383 0.403 0.311 0.398 Mechanical strength, N / mm 19.2 19.7 20.4 20.2 18.3 19.4 16.7 11.3 10.2 Table 2 Raw oil properties Crude oil Diesel Fuel <![CDATA[Density (20 °C) / g•cm -3 > 0.8607 Distillation range / ℃ (IBP~FBP) 205~381 <![CDATA[Sulfur / µg•g -1 > 14773 <![CDATA[Nitrogen µg•g -1 > 426 Aromatics, % 29.4 PAHs, % 14.3 Cetane Index 59.0 Table 3 Catalyst evaluation test results Catalyst No. a b e f g h i <![CDATA[Generated oil density (20 °C), g / cm 3 > 0.8348 0.8334 0.8362 0.8357 0.8350 0.8549 0.8368 S, µg / g 8.5 9.2 14.3 16.2 11.6 722.1 12.4 N, µg / g 1.7 1.7 3.8 3.9 2.1 144.3 2.2 Aromatics, wt% 14.5 14.2 15.1 16.6 14.8 22.8 14.9 PAHs, wt% 2.2 1.9 5.6 6.3 2.4 10.5 2.7 Cetane number 63.5 64.2 62.4 61.8 62.9 60.2 62.5

Claims

1. A method for preparing a diesel hydrorefining catalyst, Features The method comprises the following contents: (1) using mixed solution A as bottom water for coprecipitation reaction, and adding mixed solution B and alkaline working solution in parallel to mixed solution A for coprecipitation reaction to obtain slurry D; wherein mixed solution A is an aqueous solution containing polyvinyl pyrrolidone (PVP) and nickel salt; and mixed solution B is a mixed solution containing sodium tungstate and sodium molybdate; (2) vacuum filtering slurry D to obtain a filter cake and then curing the filter cake; (3) after curing, placing the filter cake in a vacuum filter, adding deionized water to the filter cake for the first vacuum filtration, and stopping the filtration when there is no suspended liquid on the surface of the filter cake; continuing to add deionized water for the second vacuum filtration, and stopping the filtration when there is no suspended liquid on the surface of the filter cake; adding deionized water again for the third vacuum filtration, and stopping the filtration when there is no filtrate dripping, to obtain a de-sodium filter cake, which is then dried, formed, and calcined to obtain a diesel hydrotreating catalyst.

2. The method according to claim 1, Features: In step (1), the molar ratio of sodium molybdate to sodium tungstate in the mixed solution B is 1:0.1-10, preferably 1:0.2-0.75; the concentration range of the mixed aqueous solution B is WO 3 +MoO 3 The molar concentration is 0.01 to 1 mol / L, preferably 0.1 to 0.8 mol / L.

3. The method according to claim 1, Features: The number average relative molecular weight of PVP in the mixed solution A of step (1) is in the range of 2500-60000, preferably in the range of 5000-58000, and the mass concentration of PVP is in the range of 10-60 g / L, preferably in the range of 20-35 g / L.

4. The method according to claim 1, Features: The nickel salt in the mixed solution A of step (1) needs to be a soluble nickel salt, and the molar concentration of the nickel salt is 0.1-1.2 mol / L in terms of NiO.

5. The method according to claim 1, Features: The alkaline working solution in step (1) is one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate solution. The pH value of the alkaline working solution is not less than 11.5, preferably 12-13.

6. The method according to claim 1, Features: In the coprecipitation reaction of step (1), the amount of mixed solution A and mixed solution B is determined by the active metal ratio of the hydrorefining catalyst, and the active metal mass ratio is preferably (WO 3 +MoO 3 ):NiO=1:0.4~1.

7. The method according to claim 1, Features: The pH value of the coprecipitation reaction in step (1) is 6.9-7.8; the reaction temperature is 30-95° C.; and the reaction time is 15-120 minutes.

8. The method according to claim 1, Features: The curing conditions of step (2) are as follows: ambient humidity is greater than 78%; curing temperature is 25°C to 55°C, preferably 38°C to 48°C; and curing time is 0.5 to 3 hours, preferably 0.8 to 2 hours.

9. The method according to claim 1, Features: After the curing in step (2), the water content of the filter cake is 75wt%~95wt%, preferably 80wt%~85wt%.

10. The method according to claim 1, Features: In the first vacuum filtration described in step (3), the ratio of the mass of deionized water to the mass of the final catalyst preparation is 2-6:

1.

11. The method according to claim 1, Features: In the second vacuum filtration described in step (3), the ratio of the mass of deionized water to the mass of the final catalyst preparation is 0.5~2:

1.

12. The method according to claim 1, Features: In the third vacuum filtration in step (3), the ratio of the mass of deionized water to the mass of the final catalyst preparation is 1-3:

1.

13. The method according to claim 1, Features: During the first, second and third vacuum filtration processes in step (3), the deionized water cannot be stirred with the filter cake.

14. The method according to claim 1, Features: The drying temperature in step (3) is 50-120° C., preferably 70-100° C.; the drying basis is controlled to be 38wt%-68wt%, preferably 40wt%-55wt%.

15. The method according to claim 1, Features: The calcination temperature in step (3) is 300-550° C., preferably 400-500° C., and the calcination time is 6-12 hours.