Diesel hydrocracking catalyst as well as preparation method and application thereof

Abstract

The invention provides a preparation method of a diesel oil hydrocracking catalyst. The method comprises the following steps: carrying out kneading molding on a Y molecular sieve loaded with hydrogenation active metal and alumina loaded with hydrogenation active metal to obtain the final hydrocracking catalyst, the average pore size of the aluminum oxide is greater than that of the Y molecular sieve. The catalyst prepared by the method can improve the diffusion performance of macromolecules in inferior diesel oil in molecular sieve pore channels, improve the catalytic reaction activity, lower the reaction temperature, lower the energy consumption and prolong the operation cycle of a device.

Description

Technical Field

[0001] The present invention relates to a diesel hydrocracking catalyst and its preparation method and application, which is particularly suitable for the process of producing high value-added products by hydrocracking of inferior diesel, and can achieve the purpose of reducing the cracking reaction temperature and extending the operation cycle of the device. Background Art

[0002] Hydrocracking technology is a clean fuel oil and chemical feedstock production technology. It can process low-quality feedstocks such as vacuum gas oil, catalytic diesel, coker gas oil, coker diesel, ebullated-bed gas oil, and ebullated-bed diesel to produce products such as light naphtha, heavy naphtha, jet fuel, diesel, and high-quality tail oil. In recent years, the diesel consumption market has been weak, the diesel-to-gasoline ratio has continued to decline, and gasoline demand has been on the rise. Therefore, my country's refineries are currently adjusting their product mix to shift from producing traditional low-value-added, low-quality diesel feedstock to producing high-value-added gasoline products or BTX products. This can address the problem of excess diesel products and insufficient gasoline and aromatics production in refineries.

[0003] The major technical limitations of hydrocracking low-quality diesel to produce gasoline or BTX are high reaction temperatures, rapid catalyst deactivation, and short unit operating cycles. Therefore, developing highly active and stable hydrocracking catalysts is crucial for extending the operating cycle of low-quality diesel hydrocracking units and improving the company's economic benefits.

[0004] CN106669789A discloses a method for preparing a catalytic diesel hydrocracking catalyst. This method involves calcining a deactivated hydrocracking catalyst in an oxygen-containing atmosphere to partially decarbonize the catalyst, which is then pulverized to obtain a decarbonized catalyst powder. The sieved powder, a hydrocracking catalyst support material, and a hydrogenation-active metal precursor are then mixed and treated at high temperature in an inert atmosphere to obtain a catalytic diesel hydrocracking catalyst. While this catalyst can address the long equilibration time during the initial startup of a catalytic diesel hydroconversion unit, it suffers from high carbon deposition, a faster deactivation rate, and a lack of guaranteed unit operating cycle. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to improve the diffusion performance of macromolecules in inferior diesel in the molecular sieve pores to improve the catalytic reaction activity, reduce the reaction temperature, reduce energy consumption and extend the operation cycle of the device.

[0006] The present invention provides a method for preparing a diesel hydrocracking catalyst, comprising the following steps: mixing and kneading a Y molecular sieve loaded with a hydrogenation active metal and alumina loaded with a hydrogenation active metal to prepare a final hydrocracking catalyst; the average pore size of the alumina is larger than the average pore size of the Y molecular sieve.

[0007] In the preparation method of the catalyst of the present invention, a Y molecular sieve 1 loaded with a hydrogenation active metal, a Y molecular sieve 2 loaded with a hydrogenation active metal, and alumina loaded with a hydrogenation active metal are mixed and kneaded and formed to obtain a final hydrocracking catalyst; the pore size of the Y molecular sieve 1 is smaller than the pore size of the Y molecular sieve 2, and the pore size of the alumina is larger than the average pore size of the Y molecular sieve 2, calculated based on the carrier without metal loading.

[0008] In the preparation method of the catalyst of the present invention, the average pore size of the Y molecular sieve 1 is 1 to 7 nm lower than the average pore size of the Y molecular sieve 2, preferably 2 to 6 nm, and more preferably 3 to 5 nm.

[0009] In the preparation method of the catalyst of the present invention, the average pore size of the alumina is 2 to 10 nm higher than the average pore size of the molecular sieve 2, preferably 3 to 8 nm, and more preferably 4 to 6 nm.

[0010] In the preparation method of the catalyst of the present invention, the average pore size of the Y molecular sieve 1 is 1-5 nm, preferably 2-4 nm; the average pore size of the Y molecular sieve 2 is 3-10 nm, preferably 4-8 nm; and the average pore size of the alumina is 6-20 nm, preferably 8-16 nm.

[0011] In the preparation method of the catalyst of the present invention, the weight content of the hydrogenation active metal as oxide in the Y molecular sieve 1 loaded with the hydrogenation active metal is lower than the weight content of the hydrogenation active metal as oxide in the Y molecular sieve 2 loaded with the hydrogenation active metal; the difference between the two is 5 to 35 wt%, preferably 10 to 30 wt%, and more preferably 15 to 25 wt%.

[0012] In the preparation method of the catalyst of the present invention, the weight content of the hydrogenation active metal in the Y molecular sieve 2 loaded with the hydrogenation active metal as oxide is lower than the weight content of the hydrogenation active metal in the alumina loaded with the hydrogenation active metal as oxide based on its weight; the difference between the two is 5 to 40 wt%, preferably 8 to 36 wt%, and more preferably 10 to 30 wt%.

[0013] In the preparation method of the catalyst of the present invention, the Y molecular sieve 1 loaded with hydrogenation active metal accounts for 3 to 20 wt% of the total weight of the final hydrocracking catalyst, preferably 5 to 18 wt%; the Y molecular sieve 2 loaded with hydrogenation active metal accounts for 10 to 40 wt% of the total weight of the final hydrocracking catalyst, preferably 12 to 35 wt%; and the alumina loaded with hydrogenation active metal accounts for 20 to 65 wt% of the total weight of the final hydrocracking catalyst, preferably 25 to 55 wt%.

[0014] In the preparation method of the catalyst of the present invention, the hydrogenation active metal includes Group VI, Group VII, Group VIII metals or their metal oxides or metal sulfides, more preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, nickel or their sulfides or oxides.

[0015] In the preparation method of the catalyst of the present invention, based on the total weight of the Y molecular sieve 1 loaded with hydrogenation active metals, the content of the hydrogenation active metal in the Y molecular sieve 1 loaded with hydrogenation active metals is generally 0 to 15 wt%, preferably 2 to 12 wt%, calculated as oxide; wherein the content of the Group VII or Group VIII hydrogenation active metal oxide is generally 0 to 5 wt%, preferably 1 to 4 wt%, and the content of the Group VI hydrogenation active metal in oxide is generally 0 to 10 wt%, preferably 2 to 8 wt%.

[0016] In the preparation method of the catalyst of the present invention, based on the total weight of the Y molecular sieve 2 loaded with hydrogenation active metals, the content of the hydrogenation active metal in the Y molecular sieve 2 loaded with hydrogenation active metals in the form of oxides is generally 2 to 30 wt%, preferably 5 to 26 wt%; wherein the content of the Group VII or Group VIII hydrogenation active metal in the form of oxides is generally 1 to 8 wt%, preferably 2 to 6 wt%; and the content of the Group VI hydrogenation active metal in the form of oxides is generally 1 to 25 wt%, preferably 3 to 22 wt%.

[0017] In the preparation method of the catalyst of the present invention, based on the total weight of the hydrogenation-active metal-loaded alumina, the content of the hydrogenation-active metal in the hydrogenation-active metal-loaded alumina is generally 3 to 42 wt%, preferably 8 to 35 wt%, calculated as oxide; wherein the content of the Group VII or Group VIII hydrogenation-active metal in terms of oxide is generally 1 to 8 wt%, preferably 2 to 6 wt%; and the content of the Group VI hydrogenation-active metal in terms of oxide is generally 2 to 35 wt%, preferably 4 to 30 wt%.

[0018] In the catalyst preparation method of the present invention, the hydrogenation-active metal is loaded onto the corresponding support by impregnation. Equal volume impregnation, excess impregnation, stepwise impregnation, or co-impregnation can be employed, with equal volume stepwise impregnation being preferred. When stepwise loading is employed, Group VI active components should be loaded first, followed by Group VII or Group VIII active metals. After impregnation, the support is allowed to dry for 4-18 hours, then oven-dried at 60-120°C for 6-16 hours, and calcined in a muffle furnace at 400-600°C for 4-12 hours to obtain an intermediate material powder.

[0019] In the catalyst preparation method of the present invention, a Y molecular sieve loaded with a hydrogenation-active metal 1, a Y molecular sieve loaded with a hydrogenation-active metal 2, and alumina loaded with a hydrogenation-active metal are mixed with a binder and then kneaded and formed. The binder is typically alumina sol, peptized pseudo-boehmite, silica sol, silica-alumina sol, polyethylene glycol, or phosphoalumina sol, and the weight of the binder added is 1% to 5% of the weight of the final diesel hydrocracking catalyst. The catalyst is then dried at 60 to 120°C for 6 to 16 hours and calcined at 400 to 650°C for 2 to 12 hours to obtain the finished catalyst.

[0020] The catalyst of the present invention can be in the shape of a toothed ball, a three-leaf clover, a four-leaf clover, or a cylindrical bar. The diameter of the toothed ball catalyst is 1.4 to 8.0 mm. The length of the three-leaf clover, four-leaf clover, or cylindrical bar is 1.0 to 12.0 mm and the diameter is 1.2 to 5.0 mm.

[0021] The diesel hydrocracking catalyst of the present invention is suitable for use in the hydrocracking process of low-quality diesel fuel. Diesel fuels typically include catalytic diesel, coker diesel, ebullated-bed diesel, slurry-bed diesel, residual oil hydrotreated diesel, and straight-run diesel. The diesel fuel has an initial boiling point of 140-260°C, a dry point of 280-390°C, a sulfur content of 500-15,000 ppm, and a nitrogen content of 500-1,200 ppm.

[0022] During the diesel hydrocracking process, the reaction conditions in the refining reaction zone are generally as follows: reaction pressure 5.0-14.0 MPa, preferably 6.0-10.0 MPa; average reaction temperature 260-420°C, preferably 280-410°C; refining volume space velocity 0.2-3.0 h -1 , preferably 0.5 to 2.0 hours -1 The reaction conditions in the cracking reaction zone are generally as follows: reaction pressure 5.0-14.0 MPa, preferably 6.0-10.0 MPa; average reaction temperature 300-430°C, preferably 320-410°C; cracking volume space velocity 0.5-4.0 h -1 , preferably 1.0 to 3.0 hours -1 .

[0023] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0024] 1. When using catalysts with supports of varying pore sizes, the linear velocity of reactants varies significantly as they flow through particles of varying pore sizes. According to Bernoulli's equation, the pressure heads on the outer surfaces of particles of varying pore sizes also vary significantly. Large-pore alumina has a higher pressure head, causing reactants to flow toward the smaller-pore Y molecular sieve support, significantly improving the outward diffusion of large molecular reactants across the catalyst, thereby enhancing the diffusion of large molecular reactants into the diesel hydrocracking catalyst and reducing the reaction temperature.

[0025] 2. By loading different contents of active metals on carriers with different pore sizes, the overall active metal loading and packing density of the catalyst can be effectively reduced, thereby reducing the cost of catalyst raw materials.

[0026] 3. The diesel hydrocracking catalyst of the present invention can process secondary low-quality diesel from different sources, has a wide adaptability to raw oil, a high blending ratio, a low reaction temperature, and a long device operation cycle. DETAILED DESCRIPTION

[0027] The preparation method of the diesel hydrocracking catalyst provided by the present invention will be further described below with reference to the examples, but the present invention is not limited thereto.

[0028] Table 1 Properties of crude oil

[0029] Raw oil name diesel fuel <![CDATA[Density (20 °C), g·cm -3 (GB / T 1884)]]> 0.9650 Distillation range, °C (ASTM D1160) Sulfur content, ppm 8000 Nitrogen content, ppm 580 IBP~EBP 150～380 Group composition, wt% (SH / T 0606) Total paraffins 11.5 Total cycloalkanes 20.5 Total aromatics 68.0

[0030] Table 2 Physicochemical properties of refined catalysts and other supports

[0031] Catalysts and carriers FHUDS-8 1-Y 2-Y 3-Y <![CDATA[Al2O3]]> Average pore size / nm 5.6 2.5 7.0 9.0 12.0 <![CDATA[Pore volume / mL·g -1 > 0.35 0.25 0.23 0.20 0.42 shape Shamrock cylindrical bars cylindrical bars cylindrical bars cylindrical bars

[0032] Table 3 Evaluation conditions

[0033] Reaction pressure, MPa 8.0 <![CDATA[Refining / cracking agent mass hourly space velocity, h -1 > 1.0 / 2.0 Hydrogen-to-oil ratio at the inlet of hydrotreating / cracking reaction zone, v / v 400:1 / 600:1 Nitrogen content of refined oil, ppm 10 Conversion rate, % 75 Operation time, days 100

[0034] The feedstock oil used in the following Examples and Comparative Examples was a mixture of catalytic diesel and straight-run diesel, the properties of which are shown in Table 1. The refining reactor was loaded with the commercial catalyst FHUDS-8. The properties of FHUDS-8 and the carrier required for preparing the hydrocracking catalyst by the method of the present invention are shown in Table 2. The catalyst evaluation conditions in all Examples and Comparative Examples were the same, as shown in Table 3.

[0035] In this embodiment, catalysts with different properties are used, and their synthesis methods are as follows.

[0036] Example 1

[0037] Two Y molecular sieves with different average pore sizes were selected as carriers. The average pore size of the smallest pore size 1-Y molecular sieve carrier was 2.5 nm, and the average pore size of the largest pore size 2-Y carrier was 7.0 nm.

[0038] Using 1-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, catalyst-A powder was calcined in a 500°C muffle furnace for 8 hours. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in catalyst-A was 1.0 wt%, and the molybdenum active metal loading was 2.0 wt%.

[0039] Using 2-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 5 hours to dry, then dried in a 120°C oven for 8 hours. Finally, they were calcined in a 500°C muffle furnace for 6 hours to obtain Catalyst-B powder. Based on the mass of the loaded active metal 2-Y molecular sieve, the nickel active metal loading in Catalyst-B was 3.0 wt%, and the molybdenum active metal loading was 10.0 wt%.

[0040] Alumina was used as a support, and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, the powder was calcined in a 500°C muffle furnace for 6 hours to obtain Catalyst-C. Based on the mass of the active metal-loaded alumina, the nickel active metal loading in Catalyst-C was 4.0 wt%, and the molybdenum active metal loading was 18.0 wt%.

[0041] Catalyst-A, Catalyst-B, and Catalyst-C powders prepared above were mechanically mixed, then extruded with 2.0 wt% polyethylene glycol binder. The mixture was then dried at 100°C for 6 hours and calcined at 450°C for 4 hours to obtain Catalyst HC-1. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 16.0 wt%, the mass fraction of Catalyst-B was 36.0 wt%, and the mass fraction of Catalyst-C was 48.0 wt%.

[0042] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-1 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0043] Example 2

[0044] Two Y molecular sieves with different average pore sizes were selected as carriers. The average pore size of the smallest pore size 1-Y molecular sieve carrier was 2.5 nm, and the average pore size of the largest pore size 3-Y carrier was 9.0 nm.

[0045] Using 1-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 8 hours to dry, then dried in a 120°C oven for 8 hours. Finally, catalyst-A powder was calcined in a muffle furnace at 550°C for 8 hours. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in catalyst-A was 2.0 wt%, and the molybdenum active metal loading was 4.0 wt%.

[0046] Using 3-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 5 hours to dry, then oven-dried at 120°C for 8 hours. Finally, the catalyst was calcined in a muffle furnace at 550°C for 6 hours to obtain Catalyst-B powder. Based on the mass of the loaded active metal 3-Y molecular sieve, the nickel active metal loading in Catalyst-B was 3.0 wt%, and the molybdenum active metal loading was 10.0 wt%.

[0047] Alumina was used as a support, and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then oven-dried at 100°C for 8 hours. Finally, the powder was calcined in a muffle furnace at 550°C for 6 hours to obtain Catalyst-C. Based on the mass of the active metal-loaded alumina, the nickel active metal loading in Catalyst-C was 4.0 wt%, and the molybdenum active metal loading was 25.0 wt%.

[0048] Catalyst-A, Catalyst-B, and Catalyst-C powders prepared above were mechanically mixed, then extruded with 3.0 wt% polyethylene glycol binder. The mixture was then dried at 100°C for 4 hours and calcined at 450°C for 6 hours to obtain Catalyst HC-2. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 14.0 wt%, the mass fraction of Catalyst-B was 30.0 wt%, and the mass fraction of Catalyst-C was 56.0 wt%.

[0049] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-2 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0050] Example 3

[0051] Two Y molecular sieves with different average pore sizes were selected as carriers. The average pore size of the smallest pore size 1-Y molecular sieve carrier was 2.5 nm, and the average pore size of the largest pore size 2-Y carrier was 7.0 nm.

[0052] Using 1-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 8 hours to dry, then oven-dried at 120°C for 8 hours. Finally, catalyst-A powder was calcined in a muffle furnace at 500°C for 12 hours. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in catalyst-A was 2.5 wt%, and the molybdenum active metal loading was 8.0 wt%.

[0053] Using 2-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 8 hours to dry, then oven-dried at 100°C for 8 hours. Finally, catalyst-B powder was calcined in a muffle furnace at 550°C for 8 hours. Based on the mass of the loaded active metal 2-Y molecular sieve, the nickel active metal loading in catalyst-B was 4.0 wt%, and the molybdenum active metal loading was 12.0 wt%.

[0054] Alumina was used as a support, and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 8 hours to dry, then dried in a 100°C oven for 8 hours. Finally, the powdered catalyst, Catalyst-C, was calcined in a muffle furnace at 550°C for 8 hours. Based on the mass of the active metal-loaded alumina, the nickel active metal loading in Catalyst-C was 4.5wt%, and the molybdenum active metal loading was 30.5wt%.

[0055] Catalyst-A, Catalyst-B, and Catalyst-C powders prepared above were mechanically mixed, then extruded with 4.0 wt% polyethylene glycol binder. The mixture was then dried at 120°C for 6 hours and calcined at 450°C for 8 hours to obtain Catalyst HC-3. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 19.5 wt%, the mass fraction of Catalyst-B was 31.0 wt%, and the mass fraction of Catalyst-C was 49.5 wt%.

[0056] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-3 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0057] Example 4

[0058] Two Y molecular sieves with different average pore sizes were selected as carriers. The average pore size of the smallest pore size 1-Y molecular sieve carrier was 2.5 nm, and the average pore size of the largest pore size 3-Y carrier was 9.0 nm.

[0059] Using 1-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 8 hours to dry, then dried in a 120°C oven for 8 hours. Finally, catalyst-A powder was calcined in a muffle furnace at 550°C for 8 hours. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in catalyst-A was 3.0 wt%, and the molybdenum active metal loading was 7.0 wt%.

[0060] Using 3-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 5 hours to dry, then oven-dried at 120°C for 8 hours. Finally, the powder was calcined in a muffle furnace at 550°C for 6 hours to obtain Catalyst-B. Based on the mass of the loaded active metal 3-Y molecular sieve, the nickel active metal loading in Catalyst-B was 4.0 wt%, and the molybdenum active metal loading was 12.0 wt%.

[0061] Alumina was used as a support, and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, the powder was calcined in a 550°C muffle furnace for 6 hours to obtain Catalyst-C. Based on the mass of the active metal-loaded alumina, the nickel active metal loading in Catalyst-C was 4.0 wt%, and the molybdenum active metal loading was 30.0 wt%.

[0062] Catalyst-A, Catalyst-B, and Catalyst-C powders prepared above were mechanically mixed, then extruded with 3.0 wt% polyethylene glycol binder. The mixture was then dried at 100°C for 6 hours and calcined at 550°C for 6 hours to obtain Catalyst HC-4. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 11.0 wt%, the mass fraction of Catalyst-B was 29.0 wt%, and the mass fraction of Catalyst-C was 60.0 wt%.

[0063] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-4 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0064] Comparative Example 1

[0065] Using 1-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, catalyst-A powder was calcined in a 500°C muffle furnace for 8 hours. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in catalyst-A was 1.0 wt%, and the molybdenum active metal loading was 2.0 wt%.

[0066] Using 1-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 5 hours to dry, then dried in a 120°C oven for 8 hours. Finally, they were calcined in a 500°C muffle furnace for 6 hours to obtain Catalyst-B powder. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in Catalyst-B was 3.0 wt%, and the molybdenum active metal loading was 10.0 wt%.

[0067] Alumina was used as a support, and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, the powder was calcined in a 500°C muffle furnace for 6 hours to obtain Catalyst-C. Based on the mass of the active metal-loaded alumina, the nickel active metal loading in Catalyst-C was 4.0 wt%, and the molybdenum active metal loading was 18.0 wt%.

[0068] Catalyst-A, Catalyst-B, and Catalyst-C powders prepared above were mechanically mixed, then extruded with 2.0 wt% polyethylene glycol binder. The mixture was then dried at 100°C for 6 hours and calcined at 450°C for 4 hours to obtain Catalyst HC-5. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 16.0 wt%, the mass fraction of Catalyst-B was 36.0 wt%, and the mass fraction of Catalyst-C was 48.0 wt%.

[0069] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-5 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0070] Comparative Example 2

[0071] Using 2-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, catalyst-A powder was calcined in a 500°C muffle furnace for 8 hours. Based on the mass of the 1-Y molecular sieve loaded with active metals, the nickel active metal loading in catalyst-A was 1.0 wt%, and the molybdenum active metal loading was 2.0 wt%.

[0072] Using 2-Y as the support, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 5 hours to dry, then dried in a 120°C oven for 8 hours. Finally, they were calcined in a 500°C muffle furnace for 6 hours to obtain Catalyst-B powder. Based on the mass of the loaded active metal 2-Y molecular sieve, the nickel active metal loading in Catalyst-B was 3.0 wt%, and the molybdenum active metal loading was 10.0 wt%.

[0073] Alumina was used as a support, and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then dried in a 100°C oven for 8 hours. Finally, the powder was calcined in a 500°C muffle furnace for 6 hours to obtain Catalyst-C. Based on the mass of the active metal-loaded alumina, the nickel active metal loading in Catalyst-C was 4.0 wt%, and the molybdenum active metal loading was 18.0 wt%.

[0074] Catalyst-A, Catalyst-B, and Catalyst-C powders prepared above were mechanically mixed, then extruded with 2.0 wt% polyethylene glycol binder. The mixture was then dried at 100°C for 6 hours and calcined at 450°C for 4 hours to yield Catalyst HC-6. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 16.0 wt%, the mass fraction of Catalyst-B was 36.0 wt%, and the mass fraction of Catalyst-C was 48.0 wt%.

[0075] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-6 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0076] Comparative Example 3

[0077] Using equal mass fractions of 1-Y and 2-Y as supports, nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then oven-dried at 100°C for 8 hours. Finally, catalyst-A powder was calcined in a muffle furnace at 500°C for 8 hours. Based on the weight of the loaded active metal Y molecular sieve, the nickel active metal loading in catalyst-A was 3.0 wt%, and the molybdenum active metal loading was 6.0 wt%.

[0078] Alumina was used as a support and nickel and tungsten active metals were impregnated separately using an equal volume impregnation method. After impregnation, the active metals were allowed to stand for 6 hours to dry, then oven-dried at 100°C for 8 hours. Finally, catalyst-B powder was calcined in a muffle furnace at 500°C for 6 hours. The active metal loading in catalyst-B was 2.0 wt% nickel and 10.0 wt% molybdenum, based on the mass of the loaded active metal Y molecular sieve.

[0079] Catalyst-A and Catalyst-B powders prepared above were mechanically mixed, then extruded with 2.0 wt% polyethylene glycol binder. The mixture was then dried at 100°C for 6 hours and calcined at 450°C for 4 hours to obtain Catalyst HC-7. Based on the total weight of the catalysts, the mass fraction of Catalyst-A was 40.0 wt%, and the mass fraction of Catalyst-B was 60.0 wt%.

[0080] The refining reactor was filled with FHUDS-8 hydrorefining catalyst, and the HC-7 catalyst synthesized by the above method was loaded into the hydrocracking reaction zone. The diesel in Table 1 was used as the raw material and the evaluation was carried out according to the conditions in Table 3.

[0081] Table 4 Experimental results of examples and comparative examples

[0082]

[0083] 1The conversion rate is uniformly controlled at 75%; 2 Catalyst deactivation rate = (cracking reaction temperature after 100 days of operation - initial reaction temperature) / 100.

[0084] The test results of all examples and comparative examples are shown in Table 4. The test results show that, using the diesel cracking catalyst of the present invention, under the same reaction conditions, the hydrocracking reaction temperature and catalyst deactivation rate in the examples are lower, indicating that the catalyst of the present invention has better reaction activity and stability.

Claims

1. A method for preparing a diesel hydrocracking catalyst, characterized in that: The method comprises the following contents: mixing and kneading a Y molecular sieve loaded with a hydrogenation active metal and alumina loaded with a hydrogenation active metal to prepare a final hydrocracking catalyst; the average pore size of the alumina is larger than the average pore size of the Y molecular sieve.

2. The method according to claim 1, wherein: The final hydrocracking catalyst is prepared by mixing and kneading a Y molecular sieve 1 loaded with a hydrogenation active metal, a Y molecular sieve 2 loaded with a hydrogenation active metal, and alumina loaded with a hydrogenation active metal; the pore size of the Y molecular sieve 1 is smaller than the pore size of the Y molecular sieve 2, and the pore size of the alumina is larger than the average pore size of the Y molecular sieve 2.

3. The method according to claim 1, wherein: The average pore size of the Y molecular sieve 1 is 1 to 7 nm lower than that of the Y molecular sieve 2, preferably 2 to 6 nm, and more preferably 3 to 5 nm.

4. The method according to claim 1, wherein: The average pore size of the alumina is 2 to 10 nm higher than that of the molecular sieve 2, preferably 3 to 8 nm, and more preferably 4 to 6 nm.

5. The method according to claim 1, wherein: The average pore size of the Y molecular sieve 1 is 1 to 5 nm, preferably 2 to 4 nm; the average pore size of the Y molecular sieve 2 is 3 to 10 nm, preferably 4 to 8 nm; and the average pore size of the alumina is 6 to 20 nm, preferably 8 to 16 nm.

6. The method according to claim 1, wherein: The weight content of the hydrogenation active metal in the Y molecular sieve 1 loaded with hydrogenation active metals as oxides is lower than the weight content of the hydrogenation active metal in the Y molecular sieve 2 loaded with hydrogenation active metals as oxides.

7. The method according to claim 6, characterized in that: The difference between the two is 5 to 35 wt%, preferably 10 to 30 wt%, and more preferably 15 to 25 wt%.

8. The method according to claim 1, wherein: The weight content of the hydrogenation active metal in the Y molecular sieve 2 loaded with the hydrogenation active metal as oxide is lower than the weight content of the hydrogenation active metal in the alumina loaded with the hydrogenation active metal as oxide.

9. The method according to claim 8, characterized in that: The difference between the two is 5 to 40 wt%, preferably 8 to 36 wt%, and more preferably 10 to 30 wt%.

10. The method according to claim 1, wherein: The Y molecular sieve 1 loaded with hydrogenation active metals accounts for 3-20 wt% of the total weight of the final hydrocracking catalyst, preferably 5-18 wt%; the Y molecular sieve 2 loaded with hydrogenation active metals accounts for 10-40 wt% of the total weight of the final hydrocracking catalyst, preferably 12-35 wt%; the alumina loaded with hydrogenation active metals accounts for 20-65 wt% of the total weight of the final hydrocracking catalyst, preferably 25-55 wt%.

11. The method according to claim 1, wherein: The hydrogenation active metal includes Group VI, Group VII, Group VIII metals or their metal oxides or metal sulfides, preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, nickel or their sulfides or oxides.

12. The method according to claim 1, wherein: Based on the total weight of the Y molecular sieve 1 loaded with hydrogenation active metals, the content of the hydrogenation active metal in the Y molecular sieve 1 loaded with hydrogenation active metals is generally 0 to 5 wt%, preferably 1 to 4 wt%, calculated as oxide; wherein the content of Group VII or Group VIII hydrogenation active metal oxide is generally 0 to 2 wt%, preferably 0.5 to 1.5 wt%, and the content of Group VI hydrogenation active metal in oxide is generally 0 to 5 wt%, preferably 0.5 to 4.5 wt%.

13. The method according to claim 1, wherein: Based on the total weight of the Y molecular sieve 2 loaded with hydrogenation active metals, the content of the hydrogenation active metal in the Y molecular sieve 1 loaded with hydrogenation active metals as oxides is generally 1 to 20 wt%, preferably 2 to 18 wt%; wherein the content of the Group VII or Group VIII hydrogenation active metal as oxides is generally 1 to 5 wt%, preferably 1.5 to 4 wt%; and the content of the Group VI hydrogenation active metal as oxides is generally 1 to 15 wt%, preferably 3 to 12 wt%.

14. The method according to claim 1, wherein: Based on the total weight of the hydrogenation-active metal-loaded alumina, the content of the hydrogenation-active metal in the hydrogenation-active metal-loaded alumina is generally 3 to 25 wt%, preferably 4 to 20 wt%, calculated as oxide; wherein the content of the Group VII or Group VIII hydrogenation-active metal in terms of oxide is generally 1 to 6 wt%, preferably 2.0 to 5.0 wt%; and the content of the Group VI hydrogenation-active metal in terms of oxide is generally 2 to 20 wt%, preferably 4 to 15 wt%.

15. The method according to claim 1, wherein: The Y molecular sieve 1 carrying a hydrogenation active metal, the Y molecular sieve 2 carrying a hydrogenation active metal, and the alumina carrying a hydrogenation active metal are mixed with a binder and then kneaded and molded.

16. A diesel hydrocracking catalyst prepared by the method of any one of claims 1 to 15.

17. The hydrocracking catalyst prepared according to any one of claims 1 to 15 is used in the hydrocracking process of low-quality diesel.

18. The method according to claim 17, wherein: Diesel includes catalytic diesel and coking diesel. The initial distillation point of diesel is between 140 and 260°C, the dry point is between 280 and 390°C, the sulfur content is between 500 and 15,000 ppm, and the nitrogen content is between 500 and 1,200 ppm.

19. The use according to claim 17, characterized in that: The reaction conditions in the refining reaction zone are: reaction pressure 5.0-14.0 MPa, preferably 6.0-10.0 MPa; average reaction temperature 260-420°C, preferably 280-410°C; refining volume space velocity 0.2-3.0 h -1 , preferably 0.5 to 2.0 hours -1 .

20. The use according to claim 17, characterized in that: The reaction conditions in the cracking reaction zone are: reaction pressure 5.0-14.0 MPa, preferably 6.0-10.0 MPa; average reaction temperature 300-430°C, preferably 320-410°C; cracking volume space velocity 0.5-4.0 h -1 , preferably 1.0 to 3.0 hours -1 .

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