A catalyst composition for preparing aviation kerosene by hydroisomerization cracking of feedstock of fischer-tropsch synthesis oil

Abstract

The application provides a catalyst composition for preparing aviation kerosene by hydroisomerization cracking of a Fischer-Tropsch synthesis oil as a raw material. The catalyst composition comprises a hydroisomerization cracking catalyst A, a hydroisomerization cracking catalyst B and a hydroisomerization cracking catalyst C; the hydroisomerization cracking catalyst A, the hydroisomerization cracking catalyst B and the hydroisomerization cracking catalyst C have different mass ratios of noble metal, amorphous silicon aluminum powder and alumina. According to the characteristics that the content of straight-chain alkanes gradually decreases and the content of isomeric alkanes which are prone to secondary cracking gradually increases in the reaction material flow, the different catalysts are arranged in order from high to low according to the isomerization cracking performance, so that the content of reaction molecules is matched with the active center, and the secondary cracking of isomeric alkanes is reduced.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to a catalyst composition for preparing aviation kerosene by hydroisomerization cracking of Fischer-Tropsch synthetic oil as raw material. Background Technology

[0002] Fischer-Tropsch synthetic oils (waxes) have a wide carbon number distribution and are predominantly composed of long-chain alkanes. When converting them into aviation kerosene with a carbon number range of C8-C16 and predominantly branched alkanes, it is necessary to perform both hydrocracking to shorten the long-chain alkanes to meet the distillation range requirements of aviation kerosene and hydroisomerization to convert the straight-chain alkanes into branched alkanes to meet the freezing point requirements of aviation kerosene. The entire reaction process is therefore quite complex, placing high demands on the design of the reaction route and catalyst. Furthermore, when Fischer-Tropsch synthetic oils with a predominantly straight-chain alkanes undergo hydroisomerization cracking to produce aviation kerosene, the lack of competitive adsorption from cycloalkanes and aromatics makes the produced isomers prone to secondary cracking within the catalyst channels, leading to a decrease in the yield of the main product. Summary of the Invention

[0003] Studies have found that in traditional hydroisomerization cracking reactions, the reactor is only filled with a single-property hydroisomerization cracking catalyst. However, as the reactants flow, the content and structure of reactant molecules gradually change, while the catalyst properties and performance remain unchanged. This leads to a mismatch between reaction requirements and catalyst performance, resulting in a decrease in the selectivity of the target product. The inventors of this application unexpectedly discovered that during the flow of reactants in the catalyst bed, straight-chain alkanes gradually decrease, isoalkanes gradually increase, and the reaction temperature gradually rises. By designing the catalyst in zones, corresponding the characteristics of the reactants and reaction temperature with the characteristics of the catalyst, the secondary cracking of isoalkanes can be reduced. Therefore, this invention provides a catalyst composition for the hydroisomerization cracking of aviation kerosene using Fischer-Tropsch synthetic oil as a feedstock. The catalyst composition is based on the characteristics of gradually decreasing straight-chain alkanes and gradually increasing isoalkanes prone to secondary cracking in the flow of reactants. Different catalysts are set in order of decreasing isomerization cracking performance to match the content of reactant molecules with the active sites, thereby reducing the secondary cracking of isoalkanes.

[0004] The objective of this invention is achieved through the following technical solution: A catalyst composition for the preparation of aviation kerosene by hydroisomerization cracking, the catalyst composition comprising hydroisomerization cracking catalyst A, hydroisomerization cracking catalyst B and hydroisomerization cracking catalyst C; The hydroisomerization catalyst A comprises the following components in the following mass percentages: 0.3%-0.4% precious metals, 50%-60% amorphous silica-alumina powder, and 39.6%-49.7% alumina. The hydroisomerization catalyst B comprises the following components in the following mass percentages: 0.2%-0.3% precious metals, 40%-50% amorphous silica-alumina powder, and 49.7%-59.8% alumina. The hydroisomerization catalyst C comprises the following components in the following mass percentages: 0.1%-0.2% precious metals, 30%-40% amorphous silica-alumina powder, and 59.8%-69.9% alumina.

[0005] According to an embodiment of the present invention, the volume of the hydroisomerization catalyst A accounts for 30-50% of the total volume of the catalyst composition, for example, 30%, 35%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.

[0006] According to an embodiment of the present invention, the volume of the hydroisomerization catalyst B accounts for 30-40% of the total volume of the catalyst composition, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.

[0007] According to an embodiment of the present invention, the volume of the hydroisomerization catalyst C accounts for 20-30% of the total volume of the catalyst composition, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%.

[0008] According to an embodiment of the present invention, the sum of the volumes of the hydroisomerization catalyst A, the hydroisomerization catalyst B, and the hydroisomerization catalyst C is the total volume of the catalyst bed when the catalyst composition undergoes a catalytic reaction.

[0009] According to an embodiment of the present invention, the hydroisomerization catalyst A comprises the following components in the following mass percentages: a precious metal of 0.3%, 0.35%, or 0.4%; amorphous silica-alumina powder of 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%; and alumina of 39.6%, 39.7%, 40.6%, 40.7%, 41.6%, 41.7%, 42.6%, 42.7%, 43.6%, 43.7%, 44.6%, 44.7%, 45.6%, 45.7%, 46.6%, 46.7%, 47.6%, 47.7%, 48.6%, 48.7%, 49.6%, or 49.7%.

[0010] According to an embodiment of the present invention, the hydroisomerization catalyst B comprises the following components in the following mass percentages: a precious metal of 0.2%, 0.25%, or 0.3%; amorphous silica-alumina powder of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%; and alumina of 49.7%, 49.8%, 50.7%, 50.8%, 51.7%, 51.8%, 52.7%, 52.8%, 53.7%, 53.8%, 54.7%, 54.8%, 55.7%, 55.8%, 56.7%, 56.8%, 57.7%, 57.8%, 58.7%, 58.8%, 59.7%, or 59.8%.

[0011] According to an embodiment of the present invention, the hydroisomerization cracking catalyst C comprises the following components in the following mass percentages: a noble metal of 0.1%, 0.15%, or 0.2%; amorphous silica-alumina powder of 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%; and alumina of 59.8%, 59.9%, 60.8%, 60.9%, 61.8%, 61.9%, 62.8%, 62.9%, 63.8%, 63.9%, 64.8%, 64.9%, 65.8%, 65.9%, 66.8%, 66.9%, 67.8%, 67.9%, 68.8%, 68.9%, 69.8%, or 69.9%. According to an embodiment of the present invention, the catalyst composition for hydroisomerization to prepare aviation kerosene is used to prepare aviation kerosene by hydroisomerization using Fischer-Tropsch synthetic oil as a feedstock.

[0012] <Precious Metals> According to an embodiment of the present invention, the noble metals in the hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C are the same, preferably platinum.

[0013] According to an embodiment of the present invention, the platinum salt used to prepare the noble metal is at least one of chloroplatinic acid, tetraammonium dichloroplatinum, tetraammonium acetate platinum, and tetraammonium nitrate platinum.

[0014] Amorphous silica-alumina powder According to an embodiment of the present invention, the amorphous silica-alumina powder in the hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C is the same.

[0015] According to an embodiment of the present invention, the amorphous silicon-aluminum powder comprises amorphous silicon dioxide (SiO2) and amorphous aluminum oxide (Al2O3); preferably, the amorphous silicon-aluminum powder is composed of amorphous silicon dioxide (SiO2) and amorphous aluminum oxide (Al2O3).

[0016] According to an embodiment of the present invention, the amorphous aluminum silicate powder is prepared by methods known in the art or obtained through commercial purchase.

[0017] According to an embodiment of the present invention, the amorphous silicon-aluminum powder comprises amorphous silicon dioxide (SiO2) with a mass percentage of 35%-45%; exemplaryly, the amorphous silicon-aluminum powder comprises amorphous silicon dioxide (SiO2) with a mass percentage of 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%.

[0018] According to an embodiment of the present invention, the amorphous aluminum silica powder comprises amorphous alumina (Al2O3) with a mass percentage of 55%-65%; exemplaryly, the amorphous aluminum silica powder comprises amorphous alumina (Al2O3) with a mass percentage of 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64% or 65%.

[0019] According to an embodiment of the present invention, the sum of the mass percentages of the amorphous silicon dioxide (SiO2) and amorphous aluminum oxide (Al2O3) is 100%.

[0020] According to an embodiment of the present invention, the mass percentage of Na ions in the amorphous silica-alumina powder is ≤100 mg / kg.

[0021] According to an embodiment of the present invention, the specific surface area of ​​the amorphous aluminum silicate powder is ≥400 m². 2 / g, pore volume ≥0.80mL / g.

[0022] <alumina> According to an embodiment of the present invention, the alumina is amorphous alumina.

[0023] According to an embodiment of the present invention, the specific surface area of ​​the alumina is ≥200 m². 2 / g, pore volume ≥0.7mL / g.

[0024] According to an embodiment of the present invention, the alumina precursor used to prepare alumina is boehmite.

[0025] According to an embodiment of the present invention, the alumina is prepared by calcining boehmite at 700-800°C for 1-4 hours (e.g., calcining at 750°C for 2 hours) to obtain the alumina.

[0026] According to an embodiment of the present invention, the impurity components in the pseudoboehmite include at least one of Na, Fe, and Si; the content of each impurity component is ≤500 mg / kg; the SO4 content in the pseudoboehmite is... 2- The content is ≤500mg / kg.

[0027] According to an embodiment of the present invention, the specific surface area of ​​the pseudoboehmite is ≥200 m². 2 / g, pore volume ≥0.7mL / g.

[0028] <Preparation of Hydroisomerization Cracking Catalysts> According to an embodiment of the present invention, the hydroisomerization cracking catalyst is prepared by the following method: (1) Mix boehmite, amorphous aluminosilicate powder, adhesive, extrusion aid and water, and then form. (2) The molded carrier from step (1) is dried in air at 110-150℃ for 6-12 hours, and then calcined at 520-620℃ for 2-6 hours. (3) Impregnate the carrier after calcination in step (2) with platinum salt solution. After impregnation, dry it in air at 110-150℃ for 6-12 hours, and then calcine it at 350-450℃ for 2-6 hours. (4) The support calcined in step (3) is reduced in a hydrogen atmosphere at 350-450°C for 2-6 hours to obtain the hydroisomerization cracking catalyst.

[0029] According to an embodiment of the present invention, in step (1), the definition of the pseudoboehmite is as shown above.

[0030] According to an embodiment of the present invention, in step (1), the definition of the amorphous aluminum silicate powder is as shown above.

[0031] According to an embodiment of the present invention, in step (1), the adhesive solvent is selected from at least one of hydrochloric acid, nitric acid, acetic acid and citric acid.

[0032] According to an embodiment of the present invention, in step (1), the extrusion aid is selected from at least one of guar gum powder, methylcellulose and graphite.

[0033] According to an embodiment of the present invention, in step (1), boehmite, amorphous aluminum silicate powder and extrusion aid are mixed to obtain carrier precursor powder; a binder and water are mixed to obtain an acidic aqueous solution; the acidic aqueous solution is mixed with the carrier precursor powder and shaped.

[0034] According to an embodiment of the present invention, in step (1), the mass ratio of the amorphous silica-alumina powder to the extrusion aid is 1:0.01-0.05, for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04 or 1:0.05.

[0035] According to an embodiment of the present invention, in step (1), the mass ratio of amorphous aluminum silicate powder to boehmite is 1:0.4-2, for example, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2. By adjusting the mass ratio of amorphous aluminum silicate powder to boehmite, the mass percentage of alumina and amorphous aluminum silicate powder in the final prepared hydroisomerization cracking catalyst can be adjusted to obtain hydroisomerization cracking catalyst A, hydroisomerization cracking catalyst B, and hydroisomerization cracking catalyst C with specific mass percentage contents. For example, when the mass ratio of amorphous aluminum silicate powder to boehmite is 1:0.4-0.8, hydroisomerization cracking catalyst A can be prepared; when the mass ratio of amorphous aluminum silicate powder to boehmite is 1:0.8-1.4, hydroisomerization cracking catalyst B can be prepared; and when the mass ratio of amorphous aluminum silicate powder to boehmite is 1:1.4-2, hydroisomerization cracking catalyst C can be prepared.

[0036] According to an embodiment of the present invention, in step (1), the mass ratio of the amorphous silica-alumina powder to the adhesive solvent is 1:0.01-0.1, for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09 or 1:0.1.

[0037] According to an embodiment of the present invention, in step (1), the mass ratio of the amorphous aluminum silicate powder to water is 1:0.5-1, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1.

[0038] According to an embodiment of the present invention, in step (1), the molding is, for example, extrusion, sheeting or ball forming.

[0039] According to an embodiment of the present invention, in step (2), the product is first dried at 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C for 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, and then calcined at 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C or 620°C for 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0040] According to an embodiment of the present invention, in step (3), the concentration of the platinum salt solution is 2-10 mol / L, for example, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L. By adjusting the concentration of the platinum salt solution, the mass percentage of the noble metal Pt in the finally prepared hydroisomerization cracking catalyst can be adjusted to obtain hydroisomerization cracking catalyst A, hydroisomerization cracking catalyst B, and hydroisomerization cracking catalyst C with specific mass percentage contents. For example, when the concentration of the platinum salt solution is 7.3-10 mol / L, hydroisomerization cracking catalyst A can be prepared; when the concentration of the platinum salt solution is 4.7-7.3 mol / L, hydroisomerization cracking catalyst B can be prepared; and when the concentration of the platinum salt solution is 2-4.7 mol / L, hydroisomerization cracking catalyst C can be prepared.

[0041] According to an embodiment of the present invention, in step (3), the impregnation is an equal-volume impregnation.

[0042] According to an embodiment of the present invention, in step (3), the immersion temperature is room temperature and the immersion time is 1-5 hours.

[0043] According to an embodiment of the present invention, in step (3), the product is dried at 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C for 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, and then calcined at 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 450°C for 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0044] According to an embodiment of the present invention, in step (4), the hydrogen atmosphere is, for example, an atmosphere of 5-20 vol% H2 / 80-95 vol% Ar.

[0045] According to an embodiment of the present invention, in step (4), the reduction is carried out at 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 450°C for 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0046] The present invention also provides the use of the catalyst composition for the preparation of aviation kerosene by hydroisomerization cracking described above, which is used to prepare aviation kerosene by hydroisomerization cracking using Fischer-Tropsch synthetic oil as raw material.

[0047] According to an embodiment of the present invention, the reaction conditions for the hydroisomerization cracking are as follows: hydrogen partial pressure of 4-6 MPa, for example, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, or 6 MPa; reaction temperature of 320-360°C, for example, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, or 360°C; hydrogen-to-oil volume ratio of 400-600:1, for example, 400:1, 450:1, 500:1, 550:1, or 600:1; and liquid hourly space velocity of 0.5-1.0 h⁻¹. -1 For example, 0.5h -1 0.6h -1 0.7h -1 0.8h -1 0.9h -1 or 1.0h -1 .

[0048] This invention also provides a method for preparing aviation kerosene by hydroisomerization cracking of Fischer-Tropsch synthetic oil as feedstock, the method comprising the following steps: Hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C are sequentially filled into the reactor according to the flow direction of the reactants. Fischer-Tropsch synthetic oil is then introduced to carry out the hydroisomerization reaction.

[0049] According to an embodiment of the present invention, the source of the Fischer-Tropsch synthetic oil is not specifically defined, and it can be any Fischer-Tropsch synthetic oil prepared by methods known in the art; or Fischer-Tropsch synthetic oil obtained through commercial purchase.

[0050] According to an embodiment of the present invention, the reaction conditions for the hydroisomerization cracking are as follows: hydrogen partial pressure of 4-6 MPa, for example, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, or 6 MPa; reaction temperature of 320-360°C, for example, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, or 360°C; hydrogen-to-oil volume ratio of 400-600:1, for example, 400:1, 450:1, 500:1, 550:1, or 600:1; and liquid hourly space velocity of 0.5-1.0 h⁻¹. -1 For example, 0.5h -1 0.6h -1 0.7h -1 0.8h -1 0.9h -1 or 1.0h -1 .

[0051] Compared with the prior art, the present invention has the following beneficial effects: (1) In view of the changes in hydrocarbon structure and composition of Fischer-Tropsch synthetic oil feedstock during the flow reaction, this invention rationally combines catalysts with different catalytic activities in the reactor to match the catalyst performance with the material reaction requirements, thereby reducing the secondary cracking of isoparaffins and improving the selectivity of the target product.

[0052] (2) The selection of the hydroisomerization cracking catalyst composition of the present invention effectively reduces the amount of precious metal platinum used and reduces the preparation cost of the whole catalyst, which has significant economic benefits. Detailed Implementation

[0053] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0054] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0055] Example 1 (1) Preparation method of hydroisomerization cracking catalyst A: 200g of boehmite, 300g of amorphous aluminum silicate powder, and 12g of extrusion aid guarana powder were mixed evenly to obtain a carrier precursor powder. 12g of 3mol / L hydrochloric acid and 250g of water were mixed evenly to obtain an acidic aqueous solution. The acidic aqueous solution was mixed evenly with the carrier precursor powder, rolled, and extruded. The mixture was then dried at 120℃ for 6 hours and calcined at 560℃ for 2 hours in air to obtain carrier Z-1. An 8.6mol / L tetraammonium nitrate platinum impregnation solution was prepared and used to impregnate carrier Z-1 in equal volumes. The mixture was then dried at 120℃ for 6 hours and calcined at 400℃ for 2 hours in air. Finally, it was reduced and activated at 400℃ for 4 hours in a hydrogen atmosphere to obtain hydroisomerization catalyst A. In the hydroisomerization catalyst A, the mass percentage of noble metal Pt was 0.35%, the mass percentage of amorphous aluminum silicate powder was 55%, and the balance was alumina.

[0056] The amorphous silicon-aluminum powder used in this embodiment comprises 45% amorphous silicon dioxide (SiO2) and 55% amorphous aluminum oxide (Al2O3) by mass; the Na ion content in the amorphous silicon-aluminum powder is 80 mg / kg by mass; and the specific surface area of ​​the amorphous silicon-aluminum powder is 460 m². 2 / g, pore volume is 0.88mL / g.

[0057] The impurity components in the pseudoboehmite used in this embodiment include at least one of Na, Fe, and Si; the content of each impurity component is ≤100 mg / kg, and it is free of SO4. 2- The specific surface area of ​​the pseudoboehmite used is 280 m². 2 / g, pore volume is 0.80mL / g.

[0058] (2) Preparation method of hydroisomerization cracking catalyst B: The preparation method of the hydroisomerization catalyst B is the same as that of the hydroisomerization catalyst A, except that: the concentration of the pseudoboehmite (225g), amorphous aluminum silicate powder (275g), and tetraammonium nitrate platinum impregnation solution is 6.14mol / L. In the hydroisomerization catalyst B, the mass percentage of precious metal Pt is 0.25%, the mass percentage of amorphous aluminum silicate powder is 49%, and the balance is alumina.

[0059] (3) Preparation method of hydroisomerization cracking catalyst C: The preparation method of the hydroisomerization catalyst C is the same as that of the hydroisomerization catalyst A, except that: the concentration of the pseudoboehmite (300g), amorphous aluminum silicate powder (200g), and tetraammonium nitrate platinum impregnation solution is 3.68mol / L. In the hydroisomerization catalyst C, the mass percentage of precious metal Pt is 0.15%, the mass percentage of amorphous aluminum silicate powder is 38%, and the balance is alumina.

[0060] (4) Fixed-bed hydroisomerization reactor with a filling volume of 200 mL: Hydrogen and feed oil enter from the top and exit from the bottom. Along the flow direction, in the constant temperature zone, 60 mL of hydroisomerization catalyst A, 80 mL of hydroisomerization catalyst B, and 60 mL of hydroisomerization catalyst C are filled in sequence from top to bottom. Other areas are filled with inert ceramic balls.

[0061] (5) The hydroisomerization cracking catalyst composition can be used to produce aviation kerosene via hydroisomerization from Fischer-Tropsch synthetic oil. The hydroisomerization cracking reaction conditions are: hydrogen partial pressure of 4 MPa; reaction temperature of 320 °C; hydrogen-to-oil volume ratio of 500:1; and liquid hourly space velocity of 0.6 h⁻¹. -1 .

[0062] Comparative Examples 1-3 In a fixed-bed hydroisomerization reactor identical to that in Example 1, only one type of hydroisomerization cracking catalyst A (comparative example 1), hydroisomerization cracking catalyst B (comparative example 2), or hydroisomerization cracking catalyst C (comparative example 3) was loaded. Hydrogen and feedstock oil flowed from top to bottom along the flow direction. 200 mL of catalyst was loaded in the isothermal zone to produce aviation kerosene using Fischer-Tropsch synthetic oil as feedstock. The hydroisomerization cracking reaction conditions were: hydrogen partial pressure 4 MPa; reaction temperature 320°C; hydrogen-to-oil volume ratio 500:1; liquid hourly space velocity 0.6 h⁻¹. -1 .

[0063] Properties of Fischer-Tropsch synthetic oil feedstock:

[0064] The products synthesized from the catalyst composition in this embodiment were analyzed. First, the light naphtha fraction at <145℃ was collected by atmospheric distillation. Then, after the oil sample was cooled to room temperature, the aviation kerosene fraction at 145℃-295℃ was collected by vacuum distillation. The freezing point of the aviation kerosene fraction was measured, and the results are as follows:

[0065] The test results above show that the hydroisomerization catalyst of the present invention can achieve a jet fuel fraction yield of over 94.8% with a freezing point of -46℃, meeting the requirement that jet fuel be kept below -40℃. In contrast, using a single catalyst in the hydroisomerization process cannot simultaneously achieve both high yield and high light naphtha content; either the light naphtha content is too high (e.g., Comparative Examples 1 and 2), or the yield is too low (e.g., Comparative Example 3). This indicates that the catalyst composition of the present invention can be used to prepare jet fuel and exhibits high isomer selectivity.

[0066] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A catalyst composition for the hydroisomerization cracking of aviation kerosene, wherein, The catalyst composition includes hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C; The hydroisomerization catalyst A comprises the following components in the following mass percentages: 0.3%-0.4% precious metals, 50%-60% amorphous silica-alumina powder, and 39.6%-49.7% alumina. The hydroisomerization catalyst B comprises the following components in the following mass percentages: 0.2%-0.3% precious metals, 40%-50% amorphous silica-alumina powder, and 49.7%-59.8% alumina. The hydroisomerization catalyst C comprises the following components in the following mass percentages: 0.1%-0.2% precious metals, 30%-40% amorphous silica-alumina powder, and 59.8%-69.9% alumina.

2. The catalyst composition according to claim 1, wherein, The volume of the hydroisomerization cracking catalyst A accounts for 30-50% of the total volume of the catalyst composition; the volume of the hydroisomerization cracking catalyst B accounts for 30-40% of the total volume of the catalyst composition; and the volume of the hydroisomerization cracking catalyst C accounts for 20-30% of the total volume of the catalyst composition.

3. The catalyst composition according to claim 1 or 2, wherein, The noble metal in the hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C is the same, which is platinum; And / or, the platinum salt used to prepare the noble metal is at least one of chloroplatinic acid, tetraammonium dichloroplatinum, tetraammonium acetate platinum, and tetraammonium nitrate platinum.

4. The catalyst composition according to any one of claims 1-3, wherein, The amorphous silica-alumina powder in the hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C is the same. Preferably, the amorphous silicon-aluminum powder comprises 35%-45% by mass of amorphous silicon dioxide (SiO2); the amorphous silicon-aluminum powder comprises 55%-65% by mass of amorphous aluminum oxide (Al2O3).

5. The catalyst composition according to any one of claims 1-4, wherein, The alumina is amorphous alumina; And / or, the specific surface area of ​​the alumina is ≥200 m². 2 / g, pore volume ≥0.7mL / g; And / or, the alumina precursor used to prepare alumina is boehmite; And / or, the alumina is prepared by calcining boehmite at 700-800°C for 1-4 hours.

6. The catalyst composition according to any one of claims 1-5, wherein, The hydroisomerization cracking catalyst was prepared by the following method: (1) Mix boehmite, amorphous aluminum silicate powder, adhesive, extrusion aid and water, and then form. (2) The molded carrier from step (1) is dried in air at 110-150℃ for 6-12 hours, and then calcined at 520-620℃ for 2-6 hours. (3) Impregnate the carrier after calcination in step (2) with platinum salt solution. After impregnation, dry it in air at 110-150℃ for 6-12 hours, and then calcine it at 350-450℃ for 2-6 hours. (4) The support calcined in step (3) is reduced in a hydrogen atmosphere at 350-450°C for 2-6 hours to obtain the hydroisomerization cracking catalyst.

7. The catalyst composition according to claim 6, wherein, In step (1), the adhesive solvent is selected from at least one of hydrochloric acid, nitric acid, acetic acid and citric acid; And / or, in step (1), the extrusion aid is selected from at least one of guar gum powder, methylcellulose and graphite; And / or, in step (1), the mass ratio of the amorphous silica-alumina powder to the extrusion aid is 1:0.01-0.05; And / or, in step (1), the mass ratio of the amorphous aluminum silicate powder to the pseudoboehmite is 1:0.4-2; Preferably, when the mass ratio of amorphous aluminum silicate powder to boehmite is 1:0.4-0.8, hydroisomerization cracking catalyst A can be prepared; when the mass ratio of amorphous aluminum silicate powder to boehmite is 1:0.8-1.4, hydroisomerization cracking catalyst B can be prepared; and when the mass ratio of amorphous aluminum silicate powder to boehmite is 1:1.4-2, hydroisomerization cracking catalyst C can be prepared. And / or, in step (1), the mass ratio of the amorphous aluminum silicate powder to the adhesive solvent is 1: 0.01-0.1; And / or, in step (1), the mass ratio of the amorphous aluminum silicate powder to water is 1:0.5-1.

8. The catalyst composition according to claim 6 or 7, wherein, In step (3), the concentration of the platinum salt solution is 2-10 mol / L; Preferably, when the concentration of the platinum salt solution is 7.3-10 mol / L, hydroisomerization cracking catalyst A can be prepared; when the concentration of the platinum salt solution is 4.7-7.3 mol / L, hydroisomerization cracking catalyst B can be prepared; and when the concentration of the platinum salt solution is 2-4.7 mol / L, hydroisomerization cracking catalyst C can be prepared. Preferably, in step (3), the impregnation is an equal-volume impregnation.

9. Use of the catalyst composition for hydroisomerization to prepare aviation kerosene according to any one of claims 1-8, wherein the catalyst composition is used for hydroisomerization to prepare aviation kerosene from Fischer-Tropsch synthetic oil. Preferably, the reaction conditions for the hydroisomerization cracking are: hydrogen partial pressure of 4-6 MPa; reaction temperature of 320-360 °C; hydrogen-to-oil volume ratio of 400-600:1; and liquid hourly space velocity of 0.5-1.0 h⁻¹. -1 .

10. A method for preparing aviation kerosene by hydroisomerization cracking of Fischer-Tropsch synthetic oil as feedstock, the method comprising the following steps: Hydroisomerization catalyst A, hydroisomerization catalyst B, and hydroisomerization catalyst C are sequentially filled into the reactor according to the flow direction of the reactants. Fischer-Tropsch synthetic oil is then introduced to carry out the hydroisomerization reaction. Preferably, the reaction conditions for the hydroisomerization cracking are: hydrogen partial pressure of 4-6 MPa; reaction temperature of 320-360 °C; hydrogen-to-oil volume ratio of 400-600:1; and liquid hourly space velocity of 0.5-1.0 h⁻¹. -1 .

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