A process for the preparation of a diesel hydrofining catalyst

Abstract

The application discloses a preparation method of a diesel hydrofining catalyst, and comprises the following contents: (1) a mixed solution A is used as a coprecipitation reaction bottom water, a mixed solution B and an alkaline working solution are dropwise added into the mixed solution A in parallel flow to obtain a slurry D; the mixed solution A is an aqueous solution containing polyvinylpyrrolidone and a nickel salt; the mixed solution B is a mixed solution containing sodium tungstate and sodium molybdate; (2) the slurry D is vacuum filtered to obtain a filter cake, and the filter cake is aged; (3) after the aging is completed, deionized water is added into the filter cake to perform vacuum filtration, a sodium-removed filter cake is obtained, and then drying, shaping and calcination are performed to obtain the diesel hydrofining catalyst. The application adopts sodium-containing raw materials which are low in price and friendly to the environment, through a specific impurity removal method and the addition of a special additive, the problems of difficult shaping, poor strength and inhibition of hydrogenation activity of the bulk catalyst when the content of the impurity sodium is high are solved, and the pore structure properties and the dispersion and utilization rate of the active metal are improved.

Description

TECHNICAL FIELD

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

[0002] With the increasingly stringent environmental regulations, the quality requirements of oil products are gradually improved. After the sulfur content of diesel oil is regulated to be below 10 ppm, the requirement for aromatic content is also becoming more stringent. The most effective means to meet the requirements of oil product quality upgrading is to use high hydrogenation activity catalysts, and therefore the bulk catalysts with full metal phases are very suitable for diesel oil quality upgrading in refineries due to their excellent hydrogenation performance.

[0003] The preparation methods of hydrofining catalysts can be divided into impregnation method, kneading method, beating method, ion exchange method and coprecipitation method, and the bulk catalysts are generally prepared by the kneading method or the coprecipitation method. The kneading method is difficult to obtain a catalyst with high metal content due to the difficulty in forming. Meanwhile, due to the limitation of the preparation method, the components of active metals are difficult to be uniformly mixed, which cannot promote the synergistic effect between the active metals, so that the catalyst cannot fully exert its activity.

[0004] The coprecipitation method can uniformly mix the components due to the ion reaction characteristics, and the use of sodium-containing raw materials with relatively low price can greatly reduce the cost of catalyst raw materials and the treatment cost of nitrogen-containing wastewater. However, the introduction of a large amount of sodium ions makes it difficult to remove sodium ions from the catalyst, and a large amount of sodium ions still exist in the precipitated materials. The residual sodium ions result in poor adhesion of the materials, which are not easy to form. The unremoved sodium ions are not conducive to the formation of the pore structure of the catalyst, resulting in small pore volume and pore size of the catalyst. In addition, the high sodium content in the catalyst can reduce its hydrogenation activity.

[0005] CN1339985A discloses a preparation method of a mixed metal catalyst composition, and CN101153228A discloses a multi-metal bulk catalyst for diesel oil ultra-deep hydrodesulfurization. The above-mentioned patents all use the coprecipitation method to prepare the hydrogenation catalyst, but the pore structure of the prepared catalyst is not ideal, and the pore volume and pore size are small.

[0006] CN114471593A and CN114471594A both disclose a preparation method of a hydrofining catalyst. The method also uses the coprecipitation method for preparation, and a sodium salt removal treatment is performed. The method selects to remove the sodium salt after the catalyst is extruded into strips, but in the actual catalyst preparation process, the catalyst cannot be formed or has small strength when the sodium salt content is too high, so the method has certain requirements for the sodium content of the catalyst preparation raw materials. Meanwhile, due to the existence of a large amount of sodium ions in the coprecipitation reaction product, part of the sodium chloride crystals will be precipitated and attached to the internal pores during the drying process of the coprecipitation reaction product, which will also adversely affect the formation of the pore structure of the catalyst.

[0007] CN109692693B discloses a hydrofining catalyst and its preparation method, which uses a two-pass parallel flow precipitation method to prepare a mixed precipitate of tungsten, molybdenum and nickel as active metals, and successfully prepares the hydrofining catalyst by performing aging, drying, molding, calcination and other steps in the process. However, the particle size of the product generated in the parallel flow co-precipitation process cannot be effectively controlled in this method, especially when the previous product slurry is co-precipitated again in the second parallel flow co-precipitation, which can cause the transition aggregation of the final product particles or the uneven particle size, thereby affecting the active metal distribution of the catalyst and the pore structure, and thus affecting the hydrogenation activity of the catalyst. SUMMARY

[0008] In view of the problems existing in the prior art, the present application provides a preparation method of a diesel hydrofining catalyst. The present application uses a low-cost and environmentally friendly sodium-containing raw material, and solves the problems of difficult molding, poor strength and inhibition of hydrogenation activity of the bulk catalyst when the impurity sodium content is high by using a specific impurity removal method and adding a special additive, while the pore structure properties and active metal dispersion and utilization rate are also improved.

[0009] The preparation method of the diesel hydrofining catalyst of the present application comprises the following contents:

[0010] (1) The mixed solution A is used as the co-precipitation reaction bottom water, and the mixed solution B and the alkaline working solution are added into the mixed solution A in parallel flow to perform co-precipitation reaction, and a slurry D is obtained; wherein the mixed solution A is an aqueous solution containing polyvinylpyrrolidone (PVP) and nickel salt; the mixed solution B is a mixed solution containing sodium tungstate and sodium molybdate;

[0011] (2) The slurry D is vacuum filtered to obtain a filter cake, and the filter cake is aged;

[0012] (3) After the aging is completed, the filter cake is placed in a vacuum filter, deionized water is added to the filter cake to perform 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 continuously added to perform 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 to perform the third vacuum filtration, and the filtration is stopped when there is no filter liquid dripping, and a sodium-free filter cake is obtained, which is then dried, molded and calcined to obtain a diesel hydrofining catalyst.

[0013] In the method of the present application, 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 of the mixed aqueous solution B is 0.01-1 mol / L (based on the molar concentration of WO3+MoO3), preferably 0.1-0.8 mol / L.

[0014] In the method, the number average relative molecular weight of PVP in the mixed solution A in step (1) ranges from 2500 to 60000, preferably ranges from 5000 to 58000, for example, the type of PVP is K12, K15, K17, K25 or K30, preferably the type of PVP is K30; the mass concentration of PVP is 10-60 g / L, preferably 20-35 g / L.

[0015] In the method, the nickel salt in the mixed solution A in step (1) is a soluble nickel salt, for example, one or more of nickel acetate, nickel nitrate or nickel chloride; the molar concentration of the nickel salt, calculated as NiO, is 0.1-1.2 mol / L, preferably 0.5-0.8 mol / L.

[0016] In the method, 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 the pH value is 12-13.

[0017] In the method, the amount of the mixed solution A and the mixed solution B in the co-precipitation reaction in step (1) is determined according to the mass ratio of the active metals of the hydrorefining catalyst, preferably the mass ratio of (WO3+MoO3):NiO is 1:0.4-1.

[0018] In the method, the pH value of the reaction is measured on line in the co-precipitation reaction in step (1); the dropping speed of the alkaline working solution is controlled to keep the pH value of the reaction system in the range of 6.9-7.8, preferably 7.2-7.5.

[0019] In the method, the temperature of the co-precipitation reaction in step (1) is 30-95℃, preferably 50-70℃; the reaction time is 15-120 minutes, preferably 45-90 minutes.

[0020] In the method, the health preserving conditions in step (2) are as follows: the environmental humidity is greater than 78%; the health preserving temperature is 25-55℃, preferably 38-48℃; the health preserving time is 0.5-3 hours, preferably 0.8-2 hours; the health preserving process can be carried out in any environment meeting the above conditions, preferably directly in a vacuum filtration equipment.

[0021] In the method, the water content of the filter cake after the health preserving in step (2) is 75wt%-95wt%, preferably 80wt%-85wt%.

[0022] In the method, the ratio of the deionized water to the final catalyst preparation in the first vacuum filtration in step (3) is 2-6:1, preferably 3-4:1.

[0023] In the method, the second vacuum filtration in step (3) is performed at a ratio of deionized water mass to final catalyst preparation mass of 0.5-2:1, preferably 0.8-1.5:1.

[0024] In the method, the third vacuum filtration in step (3) is performed at a ratio of deionized water mass to final catalyst preparation mass of 1-3:1, preferably 1.5-2:1.

[0025] In the method, the deionized water in the first, second and third vacuum filtration in step (3) is not stirred with the filter cake, and the vacuum filtration is performed after the deionized water is added above the filter cake.

[0026] In the method, the drying temperature in step (3) is 50-120 DEG C, preferably 70-100 DEG C, and the dry basis is controlled to 38wt%-68wt%, preferably 40wt%-55wt%.

[0027] In the method, the calcination temperature in step (3) is 300-550 DEG C, preferably 400-500 DEG C, and the calcination time is 6-12 hours.

[0028] The present application provides a kind of body phase hydrogenation refining catalyst, and the active component of catalyst is the oxide of tungsten, molybdenum, nickel, and the content of active component is greater than 95wt%;Sodium content in catalyst ≯ 0.1%.

[0029] The specific surface area of the body phase hydrogenation refining catalyst of the present application is 240-420 m 2 / g, the pore volume is 0.28-0.45 mL / g, and the catalyst strength is 16.0-24.0 N·mm -1 .

[0030] The catalyst needs to be sulfided when used, and when the sulfided hydrogenation active center is sulfided, nickel is more easily sulfided than tungsten and molybdenum, which easily leads to the phase separation of nickel and tungsten (or molybdenum) during sulfidation, so that the outer surface of the active phase of the catalyst after sulfidation is in a nickel-rich state, thereby making tungsten (or molybdenum) at a disadvantage in the reaction competitive adsorption process, which is not conducive to the exertion of the hydrogenation activity of the catalyst. The method of the present application maintains the stability of the coprecipitation process by adding PVP in the reaction bottom water, and the mixed oxide of nickel, molybdenum and tungsten formed is more uniform, which does not cause the aggregation of nickel oxide. The sulfidation of nickel occurs in the process of forming Mo (W) S2 active phase, so that the outer surface of Mo (W) S2 is in a mixed state of nickel and tungsten (or molybdenum), which improves the utilization rate of active metals of the catalyst. PVP plays a role in stabilizing colloidal particles and adjusting particle size during the coprecipitation reaction process, avoiding the generation of excessively large product particles, causing the aggregation of active metals, or the generation of particles of different sizes due to the instability of the reaction system, thereby affecting the pore structure and hydrogenation activity of the catalyst.

[0031] The method of the present application simultaneously uses clean and environmentally friendly sodium-containing raw materials with low price, and the catalyst precursor generated by the coprecipitation reaction contains a large amount of sodium ions. The present application removes the sodium ions in a short time after the preparation of the catalyst precursor is completed, reduces the adsorption of sodium ions on the catalyst due to the increase in the drying and extrusion process, and is easier to remove. The impurity removal efficiency is high. Compared with traditional beating and washing, the aging and vacuum filtration washing in the present application can remove the aqueous solution containing a large amount of impurity sodium in the filter cake of the precursor by a small amount of water, so as to meet the requirement of sodium content ≯0.1% in the filter cake, reduce the washing frequency, and greatly reduce the water consumption in the catalyst preparation process. The problems of difficulty in forming, small strength after forming, and influence on the hydrogenation activity of the catalyst due to the high sodium content of the catalyst precursor are solved.

[0032] In the aging process of the method of the present application, part of the hydrated sodium ions in the filter cake are precipitated from the filter cake and vacancies are reserved. The pore volume of the catalyst precursor increases. In step (3), the filter cake from which the impurity sodium is removed is dried at a controlled temperature. The pore expansion effect is obvious. During the drying process, the water in the filter cake rapidly diffuses outward in the form of water vapor, which causes impact on the pore structure, resulting in that the internal pores of the filter cake become larger and the pore distribution moves to the direction of large pores. Finally, the pore volume and pore size of the catalyst increase. At the same time, due to the removal of the impurity sodium, no sodium chloride crystals are precipitated and attached to the internal pores of the filter cake during the drying process, which affects the pore expansion. Therefore, the pore expansion effect during the drying process is more obvious than the removal of impurity sodium after the catalyst is formed. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be clearly and completely described below in combination with specific embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. In the following examples and comparative examples, PVP, K30 type is produced by the Chemical Reagent Co., Ltd. of China National Pharmaceutical Group, and K15 type is produced by Melun Biotech Co., Ltd. Agilent inductively coupled plasma mass spectrometer (7700 ICP-MS) is used for element analysis in the catalyst testing and characterization method. The specific surface area and pore size of the catalyst are measured on the ASAP-2405 type BET nitrogen adsorption instrument in the United States. The crushing strength of the catalyst is measured on the particle strength tester. Example 1

[0034] A mixed solution B of sodium molybdate and sodium tungstate is prepared: the molar concentration of sodium molybdate is 0.6 mol / L, and the molar concentration of sodium tungstate is 0.2 mol / L. An alkaline precipitant sodium hydroxide solution is prepared, and the pH value of the solution is 13.0. A mixed solution A is prepared: the concentration of nickel chloride is 0.6 mol / L, and the concentration of PVP type K30 is 20 g / L.

[0035] The mixed solution A is heated to 65℃, and then the reaction is carried out by adding the mixed solution B and the alkaline precipitant into the mixed solution A in parallel flow, the reaction temperature is 65℃, the pH value of the reaction is measured on line, the pH value is kept in the range of 7.2-7.3, and the reaction is completed after 80 minutes to obtain product slurry D.

[0036] The product filter cake is obtained by filtering the slurry D, and then filter cake aging is carried out: the aging is directly carried out in a vacuum filter, the humidity of the aging environment is greater than 85%, the aging temperature is 45℃, the aging time is 1.5h, and the moisture content of the filter cake is 85% after the aging is completed;

[0037] Deionized water with a mass ratio of 4:1 to the final catalyst preparation is added above the filter cake of the vacuum filter, and vacuum filtration is carried out until there is no suspended liquid on the surface of the filter cake; deionized water with a mass ratio of 1:1 to the final catalyst preparation is continuously added above the filter cake, and vacuum filtration is carried out until there is no suspended liquid on the surface of the filter cake; deionized water with a mass ratio of 1.5:1 to the final catalyst preparation is added above the filter cake again, and vacuum filtration is carried out until there is no filter liquid dripping from the filter cake, and the washing is completed.

[0038] The desodified filter cake is dried at 90℃, and the drying is stopped when the dry basis of the filter cake is 50wt%; the filter cake is rolled and extruded into a three-leaf clover shape; the formed strip is calcined at 500℃ for 8h to obtain a diesel hydrofining catalyst a, and the main properties are shown in Table 1. Example 2

[0039] The mixed solution B of sodium molybdate and sodium tungstate is prepared: the molar concentration of sodium molybdate is 0.4mol / L, and the molar concentration of sodium tungstate is 0.3mol / L; the mixed solution of alkaline precipitant sodium carbonate and sodium hydroxide is prepared, and the pH value of the solution is 12.5; the mixed solution A is prepared: the concentration of nickel acetate is 0.8mol / L, and the concentration of PVP type K15 is 30g / L.

[0040] The mixed solution A is heated to 70℃, and then the reaction is carried out by adding the mixed solution B and the alkaline precipitant into the mixed solution A in parallel flow, the reaction temperature is 70℃, the pH value of the reaction is measured on line, the pH value is kept in the range of 7.4-7.5, and the reaction is completed after 70 minutes to obtain product slurry D.

[0041] The product filter cake is obtained by filtering the slurry D, and then filter cake aging is carried out: the aging is directly carried out in a vacuum filter, the humidity of the aging environment is greater than 80%, the aging temperature is 50℃, the aging time is 1.2h, and the moisture content of the filter cake is 81% after the aging is completed;

[0042] Add deionized water to the filter cake of the vacuum filter, with a mass ratio of 3:1 to the final catalyst preparation, vacuum filter until there is no suspended liquid on the surface of the filter cake; continue to add deionized water to the filter cake, with a mass ratio of 1.2:1 to the final catalyst preparation, vacuum filter until there is no suspended liquid on the surface of the filter cake; add deionized water to the filter cake again, with a mass ratio of 1:1 to the final catalyst preparation, vacuum filter until there is no filter liquid dripping from the filter cake, and the washing is completed.

[0043] Dry the desodiated filter cake at 70℃, stop drying when the dry basis of the filter cake is 54wt%; roll and extrude into a three-leaf clover shape; shape the strip and calcine at 480℃ for 9h to obtain diesel hydrofining catalyst b, the main properties of which are shown in Table 1. Example 3

[0044] 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 a basic precipitant sodium bicarbonate solution, with a solution pH value of 13.5; prepare a mixed solution A: the concentration of nickel nitrate is 0.4mol / L, and the PVP type is K30, with a concentration of 40g / L.

[0045] After the mixed solution A is warmed to 50℃, the reaction is carried out: the mixed solution B and the basic precipitant are added dropwise to the mixed solution A in parallel flow, the reaction temperature is 50℃, the reaction pH value is measured online, the pH value is kept in the range of 6.9~7.0, and the reaction is completed after 55 minutes to obtain product slurry D.

[0046] Filter the slurry D to obtain the product filter cake and carry out filter cake incubation: the incubation is directly carried out on the vacuum filter, the incubation environment humidity is greater than 90%, the incubation temperature is 35℃, the incubation time is 2.5h, and after the incubation is completed, the filter cake moisture content is 92%;

[0047] Add deionized water to the filter cake of the vacuum filter, with a mass ratio of 5:1 to the final catalyst preparation, vacuum filter until there is no suspended liquid on the surface of the filter cake; continue to add deionized water to the filter cake, with a mass ratio of 0.6:1 to the final catalyst preparation, vacuum filter until there is no suspended liquid on the surface of the filter cake; add deionized water to the filter cake again, with a mass ratio of 2:1 to the final catalyst preparation, vacuum filter until there is no filter liquid dripping from the filter cake, and the washing is completed.

[0048] Dry the desodiated filter cake at 110℃, stop drying when the dry basis of the filter cake is 60wt%; roll and extrude into a three-leaf clover shape; shape the strip and calcine at 520℃ for 5h to obtain diesel hydrofining catalyst c, the main properties of which are shown in Table 1. Example 4

[0049] A mixed solution B of sodium molybdate and sodium tungstate was prepared, in which the molar concentration of sodium molybdate was 0.3 mol / L and the molar concentration of sodium tungstate was 0.6 mol / L; a basic precipitant sodium hydroxide solution was prepared, in which the pH value of the solution was 11.8; and a mixed solution A was prepared, in which the concentration of nickel chloride was 1.0 mol / L and the concentration of PVP (type K15) was 15 g / L.

[0050] After the mixed solution A was heated to 80°C, the mixed solution B and the basic precipitant were added dropwise into the mixed solution A at a reaction temperature of 80°C, the pH value of the reaction was measured on line, the pH value was kept in the range of 7.1-7.2, and the reaction was completed after 100 minutes to obtain a product slurry D.

[0051] The product filter cake was obtained by filtering the slurry D and was subjected to filter cake incubation; the incubation was directly performed on a vacuum filter, the humidity of the incubation environment was greater than 93%, the incubation temperature was 54°C, the incubation time was 1.8 h, and the water content of the filter cake was 77% after the incubation was completed;

[0052] Deionized water in a mass ratio of 2.5:1 to the final catalyst preparation was added above the filter cake of the vacuum filter, and vacuum filtration was performed until there was no suspended liquid on the surface of the filter cake; deionized water in a mass ratio of 2.5:1 to the final catalyst preparation was continuously added above the filter cake, and vacuum filtration was performed until there was no suspended liquid on the surface of the filter cake; deionized water in a mass ratio of 2.5:1 to the final catalyst preparation was added again above the filter cake, and vacuum filtration was performed until there was no filter liquid drop on the filter cake, and the washing was completed.

[0053] The desodiated filter cake was dried at 60°C, the dry basis of the filter cake was 45 wt%, and the drying was stopped; the filter cake was rolled and extruded into a three-leaf clover shape; the formed strip was calcined at 450°C for 11 h to obtain a diesel hydrofining catalyst d, and the main properties are shown in Table 1.

[0054] Comparative Example 1

[0055] The other steps of this example were consistent with those of Example 1, except that no additive PVP was added to the solution A in this comparative example.

[0056] Finally, catalyst e was obtained, and the main properties are shown in Table 1.

[0057] Comparative Example 2

[0058] The other steps of this example were consistent with those of Example 1, except that the concentration of the additive PVP K30 added to the solution A in this comparative example was 140 g / L.

[0059] Finally, catalyst f was obtained, and the main properties are shown in Table 1.

[0060] Comparative Example 3

[0061] The other steps of this example were consistent with those of Example 1, except that no incubation process of step (2) was performed in this comparative example.

[0062] The final catalyst g was obtained, and its main properties are shown in Table 1.

[0063] Comparative Example 4

[0064] A mixed solution B of sodium molybdate and sodium tungstate was prepared, in which the molar concentration of sodium molybdate was 0.6 mol / L, and the molar concentration of sodium tungstate was 0.2 mol / L; a basic precipitant sodium hydroxide solution was prepared, and the pH value of the solution was 13.0; a mixed solution A was prepared, in which the concentration of nickel chloride was 0.6 mol / L, and the concentration of PVP K30 was 20 g / L.

[0065] After the mixed solution A was heated to 65°C, the reaction was carried out: the mixed solution B and the basic precipitant were added dropwise into the mixed solution A in parallel flow, the reaction temperature was 65°C, the reaction pH value was measured on line, the pH value was kept in the range of 7.2-7.3, and the reaction was completed after 80 minutes to obtain a product slurry D.

[0066] The product filter cake was obtained by filtering the slurry D, deionized water was added to the filter cake in a mass ratio of 6.5:1 to the final catalyst to be prepared for beating and washing, and after the end of the washing, vacuum filtration was carried out until no filtrate was dropped.

[0067] The desodium filter cake was dried at 90°C, and the drying was stopped when the dry basis of the filter cake was 50 wt%; the filter cake was rolled and extruded into a trilobal shape; the formed strip was calcined at 500°C for 8 h to obtain a diesel hydrofining catalyst h, and the main properties are shown in Table 1.

[0068] Comparative Example 5

[0069] A mixed solution B of sodium molybdate and sodium tungstate was prepared, in which the molar concentration of sodium molybdate was 0.6 mol / L, and the molar concentration of sodium tungstate was 0.2 mol / L; a basic precipitant sodium hydroxide solution was prepared, and the pH value of the solution was 13.0; a mixed solution A was prepared, in which the concentration of nickel chloride was 0.6 mol / L, and the concentration of PVP K30 was 20 g / L.

[0070] After the mixed solution A was heated to 65°C, the reaction was carried out: the mixed solution B and the basic precipitant were added dropwise into the mixed solution A in parallel flow, the reaction temperature was 65°C, the reaction pH value was measured on line, the pH value was kept in the range of 7.2-7.3, and the reaction was completed after 80 minutes to obtain a product slurry D.

[0071] The product filter cake was obtained by filtering the slurry D, dried at 90℃, and the filter cake dry base was 50wt% to stop drying; rolled and extruded into a three-leaf clover shape; and impurity sodium was removed according to the method disclosed in CN114471594A: after the shaped product was incubated at 70℃ for 50 hours, the temperature was reduced to 20℃, and incubation was continued for 30 hours. Washed twice with clean water, and the mass ratio of deionized water to catalyst preparation was 6.5:1. The wet strip was dried at 80℃ for 10 hours, and calcined at 500℃ for 8h to obtain a diesel hydrofining catalyst i, and the main properties are shown in Table 1. Example 5

[0072] This example is a catalyst activity evaluation experiment of the present application, and is compared with comparative example catalysts. The present application a, b catalysts and comparative example e, f, g, h, i catalysts are used to carry out comparative evaluation tests on a 200ml small hydrogenation device.

[0073] The vulcanization process adopts wet vulcanization, and carbon disulfide is added as a vulcanizing oil in aviation kerosene, and the amount of vulcanizing agent is 120% of the theoretical sulfur amount required for complete vulcanization of each active metal in the hydrofining catalyst. The pre-vulcanization conditions are: first, the temperature is raised to 150℃, the hydrogen pressure is 8.0MPa, the volume space velocity is 2.0h -1 , the vulcanization time is 4h; then the temperature is 230℃, the hydrogen pressure is 8.0MPa, the volume space velocity is 2.0h -1 , the vulcanization time is 4h; finally, the temperature is raised to 320℃, the hydrogen pressure is 8.0MPa, the volume space velocity is 2.0h -1 , the vulcanization time is 4h, and the vulcanization is completed.

[0074] The evaluation conditions are: total reaction pressure 6.8MPa, hydrogen oil volume ratio 500:1, volume space velocity 1.5h -1 , reaction temperature 360℃, and the properties of the raw oil are shown in Table 2, and Table 3 is the catalyst evaluation results.

[0075] From the evaluation results, it can be seen that the hydrogenation activity of the catalysts a and b prepared by the present application is better than that of the comparative examples, indicating that the catalyst prepared by the method of the present application has good pore distribution, the pore volume and pore size of the catalyst are increased, the addition of appropriate amount of PVP during the reaction makes the particle size of the coprecipitation product uniform and appropriate, and the oxides of nickel, molybdenum and tungsten are more uniform, the subsequent nickel vulcanization occurs in the process of forming Mo (W) S2 active phase, so that the outer surface of Mo (W) S2 exists in the mixed state of nickel and tungsten (or molybdenum), which improves the utilization rate of active metal of the catalyst, and therefore the hydrogenation desulfurization, denitrification and aromatic saturation performance of the catalyst a are better than those of the catalysts e and f. The catalysts g, h and i are not removed according to the specific method of impurity sodium, and the evaluation results show that the method of the present application has good effect on removing sodium from the catalyst precursor, and promotes the activity of the catalyst.

[0076] Table 1 Catalyst composition and properties of Examples and Comparative Examples

[0077] Catalyst no. a b c d e f g h i Catalyst composition MoO3, wt% 50.0 40.0 25.0 20.0 50.0 50.0 50.0 50.0 50.0 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 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

[0078] Table 2 Properties of raw oils

[0079] Feed oil Mixed diesel Density (20°C) / g•cm -3 ]] 0.8607 Distillation range / °C (IBP~FBP) 205~381 S / µg•g -1 ]] 14773 Nitrogen mg g -1 ]] 426 Aromatics, % 29.4 Polycyclic aromatics, % 14.3 Cetane index 59.0

[0080] Table 3 Results of catalyst evaluation tests

[0081] Catalyst no. a b e f g h i Density of the produced oil (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 Polycyclic aromatics, 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 process for the preparation of a diesel hydrofmishing catalyst, characterized in that The method comprises the following steps: (1) mixing solution A is used as the bottom solution of the coprecipitation reaction, and mixed solution B and an alkaline working solution are added into the mixed solution A to carry out the coprecipitation reaction, so as to obtain slurry D; wherein the mixed solution A is an aqueous solution containing polyvinylpyrrolidone (PVP) and a nickel salt; the mixed solution B is a mixed solution containing sodium tungstate and sodium molybdate; (2) the slurry D is vacuum filtered to obtain a filter cake, and the filter cake is aged; (3) after the aging is completed, the filter cake is placed in a vacuum filter, and deionized water is added into the filter cake to carry out the first vacuum filtration until no suspended liquid is present on the surface of the filter cake, and the vacuum filtration is stopped; the deionized water is continuously added to carry out the second vacuum filtration until no suspended liquid is present on the surface of the filter cake, and the vacuum filtration is stopped; the deionized water is added again to carry out the third vacuum filtration until no filter liquid drops, and the vacuum filtration is stopped, so as to obtain a sodium-removed filter cake, which is dried, shaped and calcined to obtain a diesel hydrofining catalyst; in the step (1), the number-average relative molecular weight of the PVP in the mixed solution A ranges from 2500 to 60000, and the mass concentration of the PVP is 10-60 g / L; in the step (2), the aging conditions are as follows: the environmental humidity is greater than 78%, the aging temperature is 25-55 ℃, and the aging time is 0.5-3 hours.

2. The method of claim 1, wherein: In the step (1), the molar ratio of sodium molybdate to sodium tungstate in the mixed solution B is 1:0.1-10; and the concentration of the mixed solution B ranges from 0.01 to 1 mol / L in terms of the molar concentration of WO3+MoO3.

3. The method of claim 1, wherein: In the step (1), the number-average relative molecular weight of the PVP in the mixed solution A ranges from 5000 to 58000, and the mass concentration of the PVP is 20-35 g / L.

4. The method of claim 1, wherein: In the step (1), the nickel salt in the mixed solution A is 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 of claim 1, wherein: In the step (1), the alkaline working solution is one or more of sodium hydroxide, sodium carbonate and sodium bicarbonate, and the pH value of the alkaline working solution is not less than 11.

5.

6. The method of claim 1, wherein: In the step (1), the amount of the mixed solution A and the mixed solution B in the coprecipitation reaction is determined according to the active metal ratio of the hydrofining catalyst, and the mass ratio of the active metal (WO3+MoO3):NiO is 1:0.4-1.

7. The method of claim 1, wherein: In the step (1), the pH value of the coprecipitation reaction is 6.9-7.8, the reaction temperature is 30-95 ℃, and the reaction time is 15-120 minutes.

8. The method of claim 1, wherein: In the step (2), the water content of the filter cake after the aging is 75wt%-95wt%.

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

1.

10. The method of claim 1, wherein: In the step (3), the mass ratio of the deionized water to the final catalyst preparation in the second vacuum filtration is 0.5-2:

1.

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

1.

12. The method of claim 1, wherein: In the step (3), the deionized water cannot be stirred with the filter cake in the first, second and third vacuum filtrations.

13. The method of claim 1, wherein: In the step (3), the drying temperature is 50-120 ℃, and the dry basis is controlled to be 38wt%-68wt%.

14. The method of claim 1, wherein: In the step (3), the calcination temperature is 300-550 ℃, and the calcination time is 6-12 hours.