Catalytic diesel polycondensation catalyst, method for preparing the same, and use thereof

Abstract

The application belongs to the technical field of catalyst preparation, and provides a catalytic diesel polycondensation catalyst, a preparation method and application thereof, the polycondensation catalyst comprising an active component and a carrier; the active component is composed of one or more metal chloride salts. The polycondensation catalyst is contacted with catalytic diesel to perform a reaction, and the catalytic diesel can be efficiently directed polycondensation under mild conditions, 3-4 ring aromatic hydrocarbons have high selectivity, and the coking rate is low, which provides high-quality reaction raw materials for high-quality needle coke.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to catalysts for catalytic diesel polycondensation. Background Technology

[0002] With the booming development of the new energy vehicle industry, the demand for high-quality needle coke has experienced explosive growth. One method for producing needle coke is delayed coking, which typically uses residual oil or slurry oil rich in tri- and tetra-cyclic aromatics as feedstock. However, slurry oil has a high impurity content, making it difficult to produce high-quality needle coke even after pretreatment. In recent years, diesel demand has been declining, and the production of clean diesel has shifted from limiting impurity content to optimizing the hydrocarbon composition of oil products. Catalytic diesel (LCO) has a high proportion of impurities, and its sulfur, nitrogen, and aromatic content are all high, making it difficult to use for producing China VI diesel. Therefore, there is an urgent need to explore new pathways for LCO conversion. LCO meets the requirements for high-grade needle coke feedstock in terms of impurity content and also has a high aromatic content. However, the aromatics in LCO are mainly one- and two-membered ring aromatics, which are difficult to form coke through conventional coking methods.

[0003] One method for producing coke using monocyclic and dicyclic aromatic hydrocarbons involves polycondensation. CN102899061A and CN118108559 disclose methods using naphthalene for polycondensation. In this method, which uses pure aromatic compounds as raw materials for polycondensation, the catalyst is always mixed with the high-melting-point product. Therefore, it is difficult to extract the molten AlCl3 catalyst from the product. Without separation, the presence of AlCl3 will prevent the product from being used to prepare needle coke and will also cause corrosion to equipment. Separation costs are high. Furthermore, the polycondensation product has a large molecular weight and a wide molecular weight distribution, making it difficult to use the resulting polycondensate to prepare high-quality needle coke.

[0004] The above methods are not suitable for catalytic diesel polycondensation, especially when the coking rate is high. Tri- and tetra-cyclic aromatics are excellent feedstocks for forming high-quality needle coke, but currently, there are no known catalysts or methods for the directional polycondensation of catalytic diesel to form tri- and tetra-cyclic aromatics.

[0005] The above background information is intended to help those skilled in the art understand the present invention and the prior art, and may include non-prior art content not known to those skilled in the art. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a catalyst for the catalytic polycondensation of diesel fuel with a low coking rate.

[0007] Another technical problem to be solved by the present invention is to provide a method for directional polycondensation of catalytic diesel, which can efficiently and directionally polycondense catalytic diesel under mild conditions to obtain aromatic polycondensates of tricyclic and tetracyclic aromatics with high selectivity for 3- to 4-cyclic aromatics.

[0008] The present invention provides a low coking rate catalytic diesel polycondensation catalyst, comprising a support and an active component supported on the support, wherein the active component comprises one or more first metal chlorides selected from anhydrous zirconium chloride, anhydrous zinc chloride, and anhydrous copper chloride.

[0009] According to the polycondensation catalyst described in the above technical solution, the support is selected from one or more of silica, alumina, molecular sieves, and aluminosilicate materials.

[0010] In one embodiment, the carrier comprises a silicon-aluminum material.

[0011] According to the polycondensation catalyst of any of the above technical solutions, optionally, the silicon-aluminum material has one or more of the following characteristics, preferably all of the following characteristics:

[0012] 1) Pore distribution: Mesoporous pore volume > 0.7 ml / g, for example, 0.7–1.2 ml / g;

[0013] 2) Specific surface area: Total specific surface area > 340m² 2 / g, for example, 340-550 mg 2 / g or 350-500m 2 / g, optionally, the mesoporous specific surface area accounts for >95% of the total specific surface area, for example 95-100% or 96-99%;

[0014] 3) Mesopore volume accounts for more than 95% of the total pore volume, for example, 95-100% or 96-99%;

[0015] 4) Silicon / Al molar ratio: 0.08–0.7, for example, 0.08–0.6;

[0016] 5) Acidity characteristics: Total acidity > 200 μmol / g, such as 200-400 μmol / g; the proportion of Brønsted acid in total acidity > 20%, such as 20-30%;

[0017] 6) The silicon-aluminum material has a pseudo-boehmite structure.

[0018] According to the present invention, the acid content is measured using pyridine adsorption infrared spectroscopy. The acid content is calculated based on the amount of pyridine adsorbed at 200°C. The method is as follows: The sample is self-supported and pressed into a pellet, then sealed in the in-situ cell of an infrared spectrometer. The temperature is raised to 400°C, and a vacuum is applied to 10... -3 The sample was heated to 280 Pa and kept at a constant temperature for 2 hours to remove adsorbed gas molecules. The temperature was then lowered to room temperature, and pyridine vapor was introduced at a pressure of 2.67 Pa to maintain adsorption equilibrium for 30 minutes. The temperature was then raised to 200 °C and evacuated to a vacuum of 10 °C. -3 Desorption was performed at Pa for 30 min, followed by spectral analysis at room temperature. The wavenumber range was 1400 cm⁻¹. -1 -1700cm-1 The pyridine adsorption infrared spectrum of the sample after desorption at 200℃ was obtained. Based on the pyridine adsorption infrared spectrum at 1540 cm⁻¹... -1 and 1450cm -1 The intensity of the characteristic adsorption peaks yields the total adsorption capacity of the molecular sieve. The relative amounts of acid centers (B acid centers) and Lewis acid centers (L acid centers)

[0019] The specific surface area and pore size distribution were measured using the nitrogen adsorption capacity method. At liquid nitrogen temperature, the volume of nitrogen adsorbed by the sample under different relative pressures (P / P0) was determined. The total surface area of ​​the sample was calculated using the BET formula according to GB / T5816-1995. The matrix (mesoporous) surface area and micropore volume of the sample were calculated using the t-plot method according to SH / T0571-1993 (2004). The zeolite (microporous) surface area was the difference between the total sample surface area and the matrix (mesoporous) surface area. The volume of liquid nitrogen adsorbed at a relative pressure (P / P0) of approximately 0.98 was taken as the total pore volume of the sample.

[0020] According to any of the above technical solutions, the polycondensation catalyst wherein the silicon-aluminum material has a pseudo-boehmite structure, which can have significantly higher catalytic diesel conversion activity and 3-4 ring aromatic hydrocarbon yield. The silicon-aluminum material with the pseudo-boehmite structure can be a commercially available product or prepared by any existing method.

[0021] According to any of the above technical solutions, the polycondensation catalyst further includes anhydrous aluminum chloride as the active component. The first metal chloride is preferably anhydrous zirconium chloride and / or anhydrous zinc chloride, more preferably anhydrous zirconium chloride, which can achieve higher catalytic diesel conversion with a lower coking rate; preferably, it has a higher yield of 3-4 ring aromatics and / or higher selectivity for 3-4 ring aromatics.

[0022] According to the polycondensation catalyst of any of the above technical solutions, the weight ratio of the first metal chloride to anhydrous aluminum chloride is preferably 0.25 to 3:1, for example 0.5 to 2:1.

[0023] According to any of the above technical solutions, the polycondensation catalyst comprises: 1 to 10 wt%, for example 1.5 to 9 wt%, of an active component based on chlorine, and optionally, 77 to 98.5%, 85 to 98%, or 90 to 99 wt%, of a support based on anhydrous elements.

[0024] The preparation method of the polycondensation catalyst according to any of the above technical solutions includes:

[0025] (1) Dry the carrier;

[0026] (2) An organic solution for preparing a metal chloride salt; wherein the metal chloride salt is a first metal chloride and optionally anhydrous aluminum chloride;

[0027] (3) Contact the dried carrier with the organic solution of the metal chloride salt obtained in step (2);

[0028] (4) Vacuum drying.

[0029] According to the polycondensation catalyst preparation method described in any of the above technical solutions, the drying in step (1) can be carried out using existing methods. In one embodiment, the drying in step (1) is, for example, drying at 100-120°C for 2-6 hours.

[0030] According to the method described in any of the above technical solutions, in step (2), the concentration of the organic solution of the metal chloride salt can be: 3-8g anhydrous metal chloride salt / 100mL organic solvent.

[0031] In one embodiment, the organic solution of the metal chloride salt is obtained by mixing anhydrous metal chloride salt with an organic solvent to form a solution, wherein the ratio of anhydrous metal chloride salt to organic solvent is 3-8 g: 100 mL; the organic solvent is one or more of anhydrous ethanol, anhydrous methanol, and carbon tetrachloride.

[0032] According to the polycondensation catalyst preparation method of any of the above technical solutions, optionally, in step (3), the contact includes mixing the organic solution of the metal chloride salt with the dried support and maintaining it for a period of time to load the metal chloride salt onto the support, preferably maintaining it at 50-75°C for a period of time, for example, stirring and / or reflux (the purpose of which is to cool the evaporated organic solvent and return it to the solution) for 6-24 hours, for example, maintaining it at a temperature of 50-75°C for 6-24 hours. Optionally, the ratio of the dried support to the organic solution of the metal chloride salt is: 10-20 parts by weight of the dried support: 3-8 parts by weight of the organic solution of the metal chloride salt (calculated as metal chloride salt).

[0033] According to the polycondensation catalyst preparation method described in any of the above technical solutions, optionally, in step (4), the vacuum drying temperature is lower than the boiling point of the organic solvent at 1 atm and higher than the freezing point of the organic solvent at 1 atm. Optionally, the vacuum degree of the vacuum drying is 0.01 to 0.08 MPa. A catalytic diesel polycondensation catalyst can be obtained after vacuum drying.

[0034] The present invention also provides a method for catalytic diesel polycondensation, comprising contacting catalytic diesel with the catalytic diesel polycondensation catalyst described in any of the above technical solutions to react.

[0035] According to the catalytic diesel polycondensation method described in any of the above technical solutions, optionally, the reaction temperature is 90-160℃, the weight ratio of catalytic diesel to the polycondensation catalyst is 10-100:1, and the reaction time is 0.5-3 hours. The aromatics in the catalytic diesel undergo a polycondensation reaction through contact with the polycondensation catalyst.

[0036] According to the catalytic diesel polycondensation method described in any of the above technical solutions, the catalytic diesel can be catalytic cracking diesel, such as LCO from a catalytic cracking unit. Optionally, the catalytic diesel is a fraction with a distillation range between 170 and 370°C produced by catalytic cracking. Optionally, the initial boiling point of the catalytic diesel is 170–220°C, and the final boiling point is 330–370°C, for example, 343°C.

[0037] Optionally, the catalytic diesel contains 15-30% monocyclic aromatic hydrocarbons and 45-60% by weight bicyclic aromatic hydrocarbons.

[0038] According to the catalytic diesel polycondensation method described in any of the above technical solutions, the coking rate of the reaction is no more than 3% by weight, preferably no more than 2% by weight, for example less than 1% by weight, for example 0 to 0.8% by weight. The coking rate refers to the percentage of dichloromethane-insoluble matter in the reaction solid product to the catalytic diesel fuel. The method for measuring dichloromethane-insoluble matter is as follows:

[0039] The collected solid phase component was mixed with dichloromethane at a weight ratio of 1:50 at room temperature (usually 20-30℃), stirred for 4 hours, and then filtered. After filtration, the dichloromethane-insoluble component was dried and weighed.

[0040] According to the catalytic diesel polycondensation method described in any of the above technical solutions, optionally, the selectivity of 3- to 4-cyclic aromatic hydrocarbons in the reaction is not less than 35% by weight. Preferably, the catalytic diesel conversion rate is not less than 30% by weight, for example, 40-50% by weight. Optionally, the weight yield of 3- to 4-cyclic aromatic hydrocarbons is not less than 10% by weight, for example, 15-30% or 16-25% by weight.

[0041] The catalytic diesel polycondensation catalyst provided by the present invention has at least one of the following advantages, and preferably all of the following advantages:

[0042] 1. Used for catalytic diesel polycondensation, enabling catalytic diesel to undergo directional polycondensation reaction to generate 3-4 ring fused ring aromatics (tricyclic and / or tetracyclic aromatics), and can have a lower coking rate.

[0043] 2. It can have high selectivity for 3- to 4-cyclic aromatic hydrocarbons.

[0044] 3. The presence of anhydrous aluminum chloride and the other metal chloride salts can improve diesel conversion rate.

[0045] 4. With the presence of silicon-aluminum material as a carrier, it can achieve a significantly higher total yield of 3-4 ring aromatics, higher diesel conversion rate, and higher selectivity for 3-4 ring aromatics.

[0046] 5. It can avoid the problem of difficulty in separating molten metal chloride salts in polycondensation products.

[0047] The catalytic diesel polycondensation method provided by this invention has a low coking rate and, under preferred conditions, can achieve a higher catalytic diesel conversion rate, higher selectivity for 3- to 4-cyclic aromatic hydrocarbons, and a more concentrated molecular weight distribution of the product. Therefore, it can provide high-quality reactants for the production of high-quality needle coke. Detailed Implementation

[0048] The polycondensation catalyst provided by the present invention, in one embodiment, is composed of an active component and a support; the active component is composed of a first metal chloride and anhydrous aluminum chloride, and the support is a silicon-aluminum material; the first metal chloride is selected from one or more of anhydrous zirconium chloride, anhydrous zinc chloride, and anhydrous copper chloride.

[0049] In one embodiment, the preparation method of the catalytic diesel polycondensation catalyst is as follows: the support is dried at 100-120°C for 2-6 hours to obtain a dried support; a metal chloride organic solution is prepared by mixing 3-8g of a metal chloride salt mixture with 100ml of an organic solvent such as anhydrous ethanol; 10-20g of the dried support is added to 100ml of the metal chloride organic solution and mixed with the dried support; the mixture is stirred and / or kept under reflux at 50-75°C for 6-24 hours; and then vacuum dried to obtain the catalytic diesel polycondensation catalyst.

[0050] One embodiment of the vacuum drying includes: vacuum drying at a vacuum degree of 0.08 MPa and a temperature of 65°C for 4 hours.

[0051] According to the invention, optionally, the polycondensation catalyst comprises 1.3 to 20% by weight, for example 1.5 to 15% by weight or 3 to 10% by weight, of an active component, and optionally, 80 to 98.7% or 85 to 98.5% or 90 to 97% by weight, of a support on an anhydrous basis.

[0052] In the following examples and comparative examples,

[0053] Silica carrier, purity 99.99%, manufacturer: Aladdin, item number: S104578;

[0054] Alumina carrier, purity 99.99%, manufacturer: Aladdin, item number: A140802;

[0055] The pseudo-boehmite structured silica-alumina (i.e., silica-alumina materials with a pseudo-boehmite structure) is produced by Sasol, part of the Siral series of silica-alumina materials, and has the following properties: a silica / alumina molar ratio of 1.24; a pore volume of 0.91 ml / g; a mesopore volume of 0.89 ml / g; and a total specific surface area of ​​462 m². 2 / g; with the following acidity distribution: total acidity is 300 μmol / g, and Brønsted acid accounts for 21% of the total acidity.

[0056] The total acid content and B acid content were measured by pyridine adsorption infrared spectroscopy, and the acid content was calculated based on the amount of pyridine adsorbed at an adsorption temperature of 200℃.

[0057] Example 1

[0058] The silica support was dried at 120℃ for 4 hours. 1 g of anhydrous aluminum trichloride and 2 g of anhydrous zirconium chloride were dissolved in 100 ml of anhydrous ethanol to form a solution. 15 g of the dried support was added, and the solution was refluxed at 70℃ for 4 hours and then vacuum dried to obtain the catalytic diesel polycondensation catalyst.

[0059] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0060] Example 2

[0061] The alumina support was dried at 120℃ for 4 hours. 1 g of anhydrous aluminum trichloride and 2 g of anhydrous zirconium chloride were dissolved in 100 ml of anhydrous ethanol to form a solution. 15 g of the dried support was added, and the solution was refluxed at 70℃ for 4 hours and then vacuum dried to obtain the catalytic diesel polycondensation catalyst.

[0062] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0063] Example 3

[0064] Using a pseudo-boehmite structure of silica-alumina as a support, the support was dried at 120°C for 4 hours. 1 g of anhydrous aluminum trichloride and 2 g of anhydrous zirconium chloride were dissolved in 100 ml of anhydrous ethanol to prepare a solution. 15 g of the dried support was added, and the solution was refluxed at 70°C for 4 hours and then vacuum dried to obtain a catalytic diesel polycondensation catalyst.

[0065] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0066] Example 4

[0067] Using a pseudo-boehmite structure of silica-alumina as a support, the support was dried at 120℃ for 4 hours. 2g of anhydrous aluminum trichloride and 1g of anhydrous zirconium chloride were dissolved in 100ml of anhydrous ethanol to form a solution. 15g of the dried support was added, and the solution was refluxed at 70℃ for 4 hours and then vacuum dried to obtain a catalytic diesel polycondensation catalyst.

[0068] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0069] Example 5

[0070] The silica-alumina support with a pseudo-boehmite structure was dried at 120℃ for 4 hours. 2g of anhydrous aluminum trichloride and 1g of anhydrous zinc chloride were prepared into a solution in 100ml of anhydrous ethanol. 15g of the dried support was added, and the solution was refluxed at 70℃ for 4 hours and then vacuum dried to obtain the catalytic diesel polycondensation catalyst.

[0071] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0072] Example 6

[0073] A silica-alumina support with a pseudo-boehmite structure was dried at 120℃ for 4 hours. 2g of anhydrous aluminum trichloride and 1g of anhydrous copper chloride were dissolved in 100ml of anhydrous ethanol to form a solution. 15g of the dried support was added, and the solution was refluxed at 70℃ for 4 hours and then vacuum dried to obtain the catalytic diesel polycondensation catalyst.

[0074] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0075] Example 7

[0076] The silica-alumina support with a pseudo-boehmite structure was dried at 120℃ for 4 hours. 4 g of anhydrous aluminum trichloride and 2 g of anhydrous zirconium chloride were prepared into a solution in 100 ml of anhydrous ethanol. 15 g of the dried support was added, and the solution was refluxed at 70℃ for 4 hours and then vacuum dried to obtain the catalytic diesel polycondensation catalyst.

[0077] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above-mentioned catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour. The results are shown in Table 2.

[0078] Example 8

[0079] Using a pseudo-boehmite structured silica-alumina material as a carrier, the carrier was dried at 120°C for 4 hours. 3g of anhydrous zirconium chloride was dissolved in 100ml of anhydrous ethanol to form a solution. 15g of the dried carrier was added, and the solution was refluxed at 70°C for 4 hours and then vacuum dried to obtain a catalytic diesel polycondensation catalyst.

[0080] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90°C for 1 hour.

[0081] Example 9

[0082] The catalyst was prepared according to the method of Example 8, except that anhydrous zinc chloride was used instead of anhydrous zirconium chloride.

[0083] Example 10

[0084] The catalyst was prepared according to the method of Example 8, except that anhydrous copper chloride was used instead of anhydrous zirconium chloride.

[0085] Comparative Example 1

[0086] Under nitrogen protection, 10g of catalytic diesel oil and 1g of anhydrous aluminum chloride were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1 hour.

[0087] Comparative Example 1

[0088] A silica-alumina support with a pseudo-boehmite structure was dried at 120°C for 4 hours. 3 g of anhydrous aluminum trichloride was dissolved in 100 ml of anhydrous ethanol to form a solution. 15 g of the dried support was added, and the solution was refluxed at 70°C for 4 hours and then vacuum dried to obtain a catalytic diesel polycondensation catalyst.

[0089] Under nitrogen protection, 10g of catalytic diesel oil and 1g of the above catalyst were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90°C for 1 hour.

[0090] Comparative Example 2

[0091] Under nitrogen protection, 10g of catalytic diesel oil and 1g of pseudoboehmite-structured silica-alumina were added to a three-necked flask, and the polycondensation reaction was carried out at atmospheric pressure and 90℃ for 1h.

[0092] After the reaction was stopped, centrifugation yielded a mixture of liquid and solid products and catalyst. The liquid phase was weighed and its detailed hydrocarbon composition was analyzed by mass spectrometry. The solid product and catalyst mixture were dissolved in dichloromethane and filtered. After filtration, the insoluble components in dichloromethane were dried and weighed. The hydrocarbon composition of the liquid product was analyzed by mass spectrometry. The formulas for calculating the various reaction parameters are as follows:

[0093] (1) Mass yield of 3-4 ring aromatics:

[0094]

[0095] (2) Catalytic diesel conversion rate:

[0096]

[0097] (3) Coking rate:

[0098]

[0099] (4) Selectivity of 3- to 4-cyclic aromatic hydrocarbons:

[0100]

[0101] In the formula, Y1 is the mass yield of 3-4 ring aromatics (wt%); m1 is the mass of catalytic diesel (g); m2 is the mass of liquid product (g); X1 is the mass percentage of 3-4 ring aromatics in the liquid product of the feedstock (wt%); X2 is the mass percentage of 3-4 ring aromatics in the liquid product (wt%); m3 is the mass of solid product (g); X3 is the mass percentage of 3-4 ring aromatics in the solid product (wt%); X is the conversion rate of catalytic diesel; X4 is the mass percentage of the fraction from the initial boiling point to 343℃ in the feedstock (wt%); X5 is the mass percentage of the fraction from the initial boiling point to 343℃ in the liquid product (wt%); Y2 is the coking rate; m4 is the mass of the dichloromethane insoluble component (g); and S is the selectivity of 3-4 ring aromatics.

[0102] The formulation and composition of the catalyst are shown in Table 1, the properties of the catalytic diesel are shown in Table 2, and the product distribution is shown in Table 3.

[0103] Table 1

[0104]

[0105] In the table above, aluminum oxide refers to the aluminum silicate material with a pseudo-boehmite structure.

[0106] Table 2 Properties of Catalytic Diesel

[0107]

[0108]

[0109] Table 3

[0110]

Claims

1. A low coking rate catalytic diesel polycondensation catalyst, comprising a support and an active component supported on the support, wherein the active component comprises one or more first metal chlorides selected from anhydrous zirconium chloride, anhydrous zinc chloride, and anhydrous copper chloride.

2. The polycondensation catalyst according to claim 1, characterized in that, The carrier is selected from one or more of silicon oxide, alumina, molecular sieves, and aluminosilicate materials; preferably aluminosilicate materials.

3. The polycondensation catalyst according to claim 2, characterized in that, The silicon-aluminum material has the following characteristics: 1) Mesoporous pore volume > 0.7 ml / g, for example, 0.7–1.2 ml / g; 2) Total specific surface area > 340m² 2 / g is, for example, 340-550 mg 2 / g, optional, the proportion of mesoporous specific surface area to total specific surface area is >95%; 3) Silicon / Al molar ratio: 0.08–0.7, for example, 0.08–0.

6. 4) Total acid content > 200 μmol / g, such as 200-400 μmol / g, and the proportion of Brønsted acid in total acid content > 20%, such as 20-30%; Optionally, the silicon-aluminum material has a pseudo-boehmite structure.

4. The polycondensation catalyst according to any one of claims 1, 2, or 3, characterized in that, The active component further includes anhydrous aluminum chloride; preferably, the first metal chloride is anhydrous zirconium chloride and / or anhydrous zinc chloride, more preferably anhydrous zirconium chloride.

5. The polycondensation catalyst according to claim 4, characterized in that, The mass ratio of the first metal chloride to anhydrous aluminum chloride is optionally 0.25 to 3:1, for example 0.5 to 2:

1.

6. The polycondensation catalyst according to any one of claims 1 to 5, characterized in that, The polycondensation catalyst comprises 1 to 10 wt% (e.g., 1.5 to 9 wt%) of an active component based on chlorine, and optionally 77 to 98.5%, 85 to 98%, or 90 to 99 wt% of a support based on anhydrous content.

7. A method for preparing the polycondensation catalyst according to any one of claims 1 to 6, comprising: (1) Dry the carrier; (2) Preparation of organic solutions of metal chloride salts; The metal chloride salt is a first metal chloride and optionally anhydrous aluminum chloride; (3) Contact the dried carrier with the organic solution of the metal chloride salt obtained in step (2); (4) Vacuum drying.

8. The method according to claim 7, wherein, The drying process described in step (1) is, for example, drying at 100–120°C for 2–6 hours; In step (2), optionally, the concentration of the organic solution of the metal chloride salt is 3-8 g of anhydrous metal chloride salt / 100 mL of organic solvent. In one embodiment, the organic solution of the metal chloride salt is obtained by mixing the metal chloride salt mixture with an organic solvent at a ratio of 3g to 8g of metal chloride salt to 100mL of organic solvent; the organic solvent is one or more of anhydrous ethanol, anhydrous methanol, and carbon tetrachloride that can dissolve the first metal chloride and aluminum chloride. Optionally, in step (3), the contact is to mix the organic solution of the metal chloride salt with the dried carrier, preferably at 50-75°C for a period of time, for example, 6-24 hours, wherein the ratio of the dried carrier to the organic solution of the metal chloride salt can be: 10-20 parts by weight of the dried carrier: 3-8 parts by weight of the organic solution of the metal chloride salt (calculated as metal chloride salt). Optionally, in step (4), the temperature of the vacuum drying is lower than the boiling point of the organic solvent at 1 atm and higher than the freezing point of the organic solvent at 1 atm; optionally, the vacuum degree of the vacuum drying is 0.01 to 0.08 MPa.

9. A method for catalytic diesel polycondensation, comprising contacting and reacting catalytic diesel with a polycondensation catalyst according to any one of claims 1 to 6.

10. The method according to claim 9, characterized in that, The reaction temperature is 90-160℃, and the weight ratio of catalytic diesel to the polycondensation catalyst is 10-100:1; the reaction time is 0.5-3h; the catalytic diesel can be catalytic cracking diesel, optionally, the catalytic diesel is a fraction produced by catalytic cracking with a distillation range between 170-370℃; optionally, the catalytic diesel contains 15-30% by weight of monocyclic aromatic hydrocarbons and 45-60% by weight of bicyclic aromatic hydrocarbons.

11. The method according to claim 9, characterized in that, The coking rate of the reaction is no more than 3% by weight, for example, no more than 1% by weight; optionally, the selectivity of 3-4 ring aromatics is no less than 35% by weight; preferably, the catalytic diesel conversion rate is no less than 30% by weight, for example, 40-50% by weight; and the mass yield of 3-4 ring aromatics is preferably no less than 10% by weight, for example, 15-30% by weight.

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