A process for the production of quadricylene

Abstract

The application discloses a method for producing quadricylene. The method comprises the following steps: contacting heavy aromatic hydrocarbon raw materials with a hydrocracking catalyst to perform a hydrocracking reaction, obtaining a reaction crude product, and then performing rectification separation to obtain a quadricylene product. The method provided by the application is used for preparing high-purity quadricylene through heavy aromatic hydrocarbon reaction separation, and has the characteristics that interfering components, i.e., methylindane and methylisobutylbenzene, which affect the separation of quadricylene can be effectively removed, and high-purity quadricylene can be separated through rectification.

Description

Technical Field

[0001] This invention relates to a method for producing tetramethylbenzene (1,2,3,4-tetramethylbenzene), and particularly to a method for producing tetramethylbenzene using C10 aromatics. Background Technology

[0002] 1,2,3,4-Tetramethylbenzene is an important fine chemical raw material, mainly used to produce phenyltetracarboxylic dianhydride, which in turn produces phenyltetracarboxylic dianhydride-based polyimide (PI) resins or films and other new materials. These PI resins can be injection molded and have better processing performance than phenyltetracarboxylic dianhydride resins, possessing potentially broader applications. Currently, industrially, 1,2,3,4-tetramethylbenzene is mainly a byproduct of the mesitylene production process. Specifically, in various mesitylene production processes such as C10 aromatics separation, coal tar separation, C10 aromatics isomerization, chloromethane alkylation, pseudotrimethylbenzene isomerization disproportionation, and pseudotrimethylbenzene methanol alkylation, a mixed tetramethylbenzene component including mesitylene, 1,2,3,4-tetramethylbenzene is first obtained. Mesitylene is then extracted through crystallization, and the remaining liquid is further purified by distillation to obtain 1,2,3,4-tetramethylbenzene.

[0003] Among the aforementioned processes, the production of mesitylene using C10 aromatics as raw material is the most widely used and mature industrial production method. C10 aromatics mainly refer to the aromatic fractions containing ten or more carbon atoms obtained from catalytic reforming and cracking to produce ethylene. This fraction has a complex composition, primarily including tetramethylbenzene, pseudotetramethylbenzene, mesitylene, methylpropylbenzene, butylbenzene, diethylbenzene, methylindene, methylindene, and naphthalene, among others. The fraction produced at 190℃~205℃ is a tetramethylbenzene-rich mixture. When producing mesitylene using this process, after crystallization and separation of mesitylene, the remaining tetramethylbenzene-rich liquid contains, in addition to pseudotetramethylbenzene and tetramethylbenzene, a certain amount of interfering components with boiling points close to tetramethylbenzene (boiling point 204.2℃), such as methylindene (boiling point 205℃). Therefore, high-purity tetramethylbenzene cannot be obtained through distillation.

[0004] Chinese patent CN107935804A discloses a method for preparing tetramethylbenzene, using maleic anhydride and 2,5-dimethylfuran as raw materials, and synthesizing tetramethylbenzene in five steps via intermediates such as 1,7-dimethyl-4,10-dioxa-tricyclo[5.2.1.0]dec-8-8en-3,5-dione, 4,7-dimethyl-isobenzofuran-1,3-dione, 1,2-bis(hydroxymethyl)-3,6-dimethylbenzene, and 1,2-bis(bromomethyl)-3,6-dimethylbenzene. This method does not require high temperature or high pressure, does not produce isomers such as mesitylene, and the product does not require subsequent separation, yielding high-purity tetramethylbenzene. However, this synthetic route involves many steps, a long reaction path, low product yield, and high cost, making it unsuitable for large-scale industrial production.

[0005] Chinese patents CN202011068678.5 and CN01103144.1 disclose a catalyst preparation method for producing homo-tetramethylbenzene by isomerization of mixed tetramethylbenzene. However, the reaction under non-hydrogen-dependent conditions is mainly isomerization, and interfering components such as methyl indane cannot be removed by cracking reaction, thus making it impossible to obtain high-purity tetramethylbenzene by distillation separation. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, such as low purity and poor economic efficiency of tetramethylbenzene, this invention provides a method for producing tetramethylbenzene. This method is used for the reaction separation of heavy aromatic hydrocarbons to prepare high-purity tetramethylbenzene. It has the characteristics of effectively removing interfering components such as methyl indane and methyl isobutylbenzene that affect the separation of tetramethylbenzene, and high-purity tetramethylbenzene can be obtained by distillation.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for producing tetramethylbenzene, the process comprising:

[0008] Heavy aromatics feedstock is contacted with a hydrocracking catalyst to undergo a hydrocracking reaction, yielding a crude product, which is then separated by distillation to obtain tetramethylbenzene.

[0009] In the above technical solution, the heavy aromatics feedstock is a reformed C10 heavy aromatics feedstock after hydrogenation.

[0010] In the above technical solution, the heavy aromatic raw material is a tetramethylbenzene-rich fraction with a distillation range of 190~205℃ obtained by distillation separation.

[0011] In the above technical solution, the hydrogenated reformed C10 aromatics feedstock contains, by weight percentage, 4.0%–15.5% mesitylene, 10.0%–20.0% pseudotetramethylbenzene, 4.5%–15.0% methyltetramethylbenzene, 1.0%–5.0% methylindene, 0.5%–5.0% methyl isobutylbenzene, and 39.5%–80.0% other components.

[0012] In the above technical solution, the tetramethylbenzene-rich fraction with a distillation range of 190℃~205℃, by mass fraction, comprises 10.0%~21.5% mesitylene, 20.0%~38.5% metatetramethylbenzene, 10.0%~25.5% methyltetramethylbenzene, 2.0%~6.3% methyl indene, 2.0%~8.2% methyl isobutylbenzene, and 0%~56.0% other components.

[0013] In the above technical solution, the heavy aromatics feedstock is preferably obtained by distillation to separate tetramethylbenzene, which can reduce hydrogen consumption during hydrogenation and improve technical and economic efficiency.

[0014] In the above technical solution, the mesitylene and pseudotetramethyllene separated from the crude reaction product by distillation can be recycled back into the hydrocracking reaction.

[0015] In the above technical solution, the hydrocracking reaction is carried out in a fixed-bed adiabatic reactor.

[0016] In the above technical solution, the reaction conditions for the hydrocracking reaction are as follows: reaction temperature 300–600℃, reaction pressure 1.0–6.0 MPa, and volume hourly space velocity (VHSV) 0.5–5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 200–1000.

[0017] In the above technical solution, the preferred reaction conditions for the hydrocracking reaction are: reaction temperature 350–500℃, reaction pressure 2.0–4.0 MPa, and volume hourly space velocity (VHSV) 1.0–3.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 400–800.

[0018] In the above technical solution, the purity of the tetramethylbenzene product is above 97%, preferably 97% to 99%.

[0019] In the above technical solution, the hydrocracking catalyst comprises:

[0020] (a) A carrier containing layered mordenite zeolite;

[0021] (b) Using at least one of Group VIII metals as the active component;

[0022] The layered mordenite has a lamellar structure, with individual lamellar crystals growing orderly along the c-axis, i.e., the thickness direction of the lamellar crystals.

[0023] Furthermore, the silicon-aluminum molar ratio of the layered mordenite, calculated as silicon oxide / alumina, is 5 to 50, preferably 5 to 20.

[0024] Furthermore, the specific surface area of ​​the layered mordenite is 300–450 m². 2 / g, preferably 350–430 m 2 / g; external specific surface area is 100-200m² 2 / g, preferably 150-200 m 2 / g.

[0025] Furthermore, the thickness of the individual sheet-like crystal, i.e., the c-axis thickness, is 30–150 nm.

[0026] Furthermore, the relative crystallinity of the layered mordenite is 85%–95%.

[0027] Furthermore, the carrier containing layered mordenite contains layered mordenite and alumina.

[0028] Furthermore, in the carrier containing layered mordenite, the content of layered mordenite accounts for 50% to 95% of the dry weight of the carrier, preferably 70% to 90%; and the content of alumina accounts for 5% to 50% of the dry weight of the carrier, preferably 10% to 30%.

[0029] In the above technical solution, the group VIII metal in the hydrocracking catalyst is preferably platinum or / and palladium.

[0030] In the above technical solution, the mass content of group VIII metals in the hydrocracking catalyst is 0.01% to 2%, preferably 0.1% to 0.5%, based on the mass of the catalyst.

[0031] The preparation method of the hydrocracking catalyst in the above technical solution includes the following steps:

[0032] (1) Mix silicon source, aluminum source a, alkali source, template agent T1, template agent T2 and water, and adjust the pH value of the system to 8.5-12.5 to obtain crystallization solution;

[0033] (2) The crystallization solution obtained in step (1) is crystallized, ammonium exchanged, dried and calcined to obtain hydrogen-type layered mordenite;

[0034] (3) The hydrogen-type layered mordenite obtained in step (2) is mixed with aluminum source b, shaped, dried and calcined to obtain a catalyst support;

[0035] (4) At least one of the group VIII metals is loaded onto the catalyst support prepared in step (3) to obtain the catalyst.

[0036] In the above technical solution, the silicon source in step (1) is selected from at least one of water glass, silica sol, silica, and silicon dioxide; the aluminum source a is selected from at least one of aluminum sulfate, sodium aluminate, aluminum nitrate, and aluminum isopropoxide; and the alkali source is selected from at least one of sodium hydroxide and potassium hydroxide. The template agent T1 is selected from one or more of tetraethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium bromide, and tetrapropylammonium hydroxide, and the template agent T2 is selected from one or more of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0037] In the above technical solution, in step (1), the silicon source, alkali source and aluminum source a are dissolved in water to prepare material A; template agent T1, template agent T2 and alkali source are added to water to prepare material B; and material B is slowly added to material A.

[0038] In the above technical solution, in the crystallization solution of step (1), the silicon source is SiO2, the aluminum source a is Al2O3, and the molar ratio of each material is SiO2 / Al2O3 = 5~50, T / SiO2 = 0.01~0.65, T1 / T2 = 0.1~2, H2O / SiO2 = 5~30, OH - / SiO2=0.1~0.5; where T represents template agent T1 and template agent T2, OH - This represents both the alkali source and the alkali used to adjust the pH.

[0039] In the above technical solution, in step (1), the pH of the system is adjusted by dropping a strong alkaline solution.

[0040] In the above technical solution, the crystallization treatment conditions in step (2) are crystallization at 120-240℃ for 3-120 hours.

[0041] In the above technical solution, after crystallization in step (2), the sodium-type layered molecular sieve is obtained by calcination after conventional solid-liquid separation, washing, and drying operations. The solid-liquid separation, washing, drying, and calcination are all conventional and well-known processes familiar to those skilled in the art, without any special limitations. For example, a method of filtering the obtained mixture can be used for separation. Here, the filtration, washing, and drying can be performed in any manner conventionally known in the art. Specifically, for example, the filtration can be performed by simply vacuum filtering the obtained product mixture. For example, washing can be performed using deionized water and / or ethanol. For example, the drying temperature can be 40–250°C, preferably 60–150°C, and the drying time can be 4–30 hours, preferably 4–20 hours. The drying can be carried out under normal pressure or under reduced pressure. The roasting can be carried out in any manner conventionally known in the art, for example, the roasting temperature is generally 300–800°C, preferably 400–650°C, and the roasting time is generally 1–12 hours, preferably 2–8 hours. Furthermore, the roasting is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0042] In the above technical solution, the ammonium exchange temperature in step (2) is 50–90℃, the ammonium exchange time is 2–10 h / time, and the number of ammonium exchanges is 2–4 times. The ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride, and ammonium sulfate, and the mass concentration of the ammonium salt solution is 5%–20%. The ammonium salt solution is mixed with the sodium-type layered zeolite solid obtained in step (2) at a mass ratio of 5–10:1. After the ammonium exchange is completed, the sample is filtered and washed with deionized water.

[0043] In the above technical solution, after the ammonium exchange step (2) is completed, the drying temperature is 50-150℃, preferably 80-120℃, and the drying time is 10-24 hours. This drying can be carried out under normal pressure or under reduced pressure. The calcination can be carried out in any manner conventionally known in the art, with a calcination temperature of 450-650℃ and a calcination time of 1-12 hours, preferably 2-6 hours. Furthermore, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0044] In the above technical solution, the amount of hydrogen-type layered mordenite added in step (3) is 50% to 95% of the dry weight of the catalyst support, preferably 70% to 90%; the amount of aluminum source b added, calculated as alumina, is 5% to 50% of the dry weight of the catalyst support, preferably 10% to 30%.

[0045] In the above technical solution, the aluminum source b in step (3) can be selected from one or more of boehmite, boehmite, and aluminum hydroxide, preferably boehmite. The molding can be carried out using conventional molding methods, such as extrusion molding. During the molding process, conventional molding aids can be added, such as extrusion aids and pectinic acids. The extrusion aid is a substance that is beneficial to extrusion molding, and can be selected from one or more of starch, hydroxymethyl cellulose, and guar gum powder, preferably guar gum powder, and its addition amount is 1.0% to 10.0% of the weight content of the catalyst carrier, preferably 1.0% to 5.0%. The pectinic acid in the pectinic acid solution can be selected from one or more of hydrochloric acid, nitric acid, acetic acid, citric acid, and tartaric acid, preferably nitric acid; the addition amount of pectinic acid solution and the aluminum source b according to the mass ratio of feed is 0.9 to 1.5, preferably 1.0 to 1.3; the concentration of pectinic acid solution is 0.5wt% to 5.0wt%, preferably 1.5wt% to 4.0wt%.

[0046] In the above technical solution, the drying conditions in step (3) are 50℃~200℃ for 1h~48h; the calcination conditions are 300℃~600℃ for 0.5h~10.0h.

[0047] In the above technical solution, the group VIII metal precursor in step (4) is selected from metal salts, preferably at least one of palladium chloride, palladium nitrate, ammonium chloropalladate, ammonium chloropalladate, platinum nitrate, chloroplatinic acid, ammonium chloroplatinate, tetraammonium dichloroplatinate, and ammonium chloroplatinate.

[0048] In the above technical solution, the mass content of the group VIII noble metal in step (4) on the catalyst is 0.01% to 2%, preferably 0.1% to 0.5%.

[0049] In the above technical solution, after loading the metal in step (4), the catalyst is obtained by drying and calcining. The drying conditions are 50℃~200℃ for 1h~48h; the calcination conditions are 300℃~600℃ for 0.5h~10.0h.

[0050] In the above technical solution, the loading method in step (4) can be one or both of the impregnation method and the ion exchange method.

[0051] In the above technical solution, the catalyst used needs to be reduced and activated before use, that is, the metal oxide on the support is converted into an active metal under a reducing atmosphere. The reduction and activation conditions are as follows: hydrogen partial pressure 0.1 MPa~5.0 MPa, reaction temperature 100℃~350℃, and volume hourly space velocity 50 h⁻¹. -1 ~300h -1 The restoration time is 1 to 12 hours.

[0052] In the above technical solution, the distillation separation is performed by separating the tetramethylbenzene product through a distillation column.

[0053] In the above technical solution, the crude product of the reaction is heat-exchanged with the feed material and then sent to a distillation column for distillation separation. The distillation column is a vacuum distillation column, and the final boiling point of the top material is controlled to be <202.5℃. The distillate with a final boiling point of 202.5~205℃ is collected from the side of the distillation column, and the material with a final boiling point >205℃ is collected from the bottom of the column. Each fraction is cooled by an air cooler and a condenser before entering the tank. The light fraction at the top of the column (fraction <202.5℃) can be recycled back to the hydrocracking reaction unit, the heavy fraction at the bottom of the column (fraction >205℃) is externally extracted heavy aromatics, and the middle fraction (fraction 202.5~205℃) is the target product, high-purity tetramethylbenzene.

[0054] In the above technical solution, the operating conditions for distillation separation can be: 120 to 150 trays, operating vacuum of -8 to -20 kPa, top temperature of 120 to 140°C, bottom temperature of 175 to 190°C, and reflux ratio of 2.0 to 4.0.

[0055] Compared with the prior art, the method of the present invention has the following advantages:

[0056] (1) Compared with chemical synthesis, the raw material used in the method of the present invention is C10 aromatic hydrocarbons by-product of refining and chemical production. The raw material cost is low, and the production of tetramethylbenzene can realize the high added value utilization of by-product resources, which has good technical and economic efficiency.

[0057] (2) Compared with the traditional direct separation method of C10 aromatics, the method of the present invention is prepared by hydrogenation cracking reaction of tetramethylbenzene fraction and separation. Because interfering components such as methylindene with a boiling point close to that of tetramethylbenzene are cracked and removed, the purity of the target product tetramethylbenzene after distillation is high.

[0058] (3) The hydrocracking catalyst used in the method of the present invention can continuously produce tetramethylbenzene through reaction separation under suitable reaction conditions. The process is short, the process route is simple, and it is easier to realize large-scale industrial production. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the hydrocracking process for producing tetramethylbenzene in Example 1;

[0060] Figure 2 This is a schematic diagram of the direct separation process of tetramethylbenzene in Comparative Example 1.

[0061] Figure 3 The image shows the X-ray diffraction (XRD) pattern of layered mordenite from Example 1.

[0062] Figure 4 This is an electron microscope image of layered mordenite from Example 1;

[0063] Figure 5 The image shows the X-ray diffraction (XRD) pattern of layered mordenite in Example 2.

[0064] Appendix Figure 1 Marker explanation:

[0065] 1: Raw material, 2: Hydrogen, 3: Hydrocracking reactor, 4: Gas-liquid separator, 5: Gas phase product, 6: Distillation column, 7: <202.5℃ fraction, 8: 202.5~205℃ (tetramethylbenzene) fraction, 9: >205℃ heavy fraction;

[0066] Appendix Figure 2 Marker explanation:

[0067] 11: C10 heavy aromatics, 21: distillation column, 31: <202.5℃ fraction, 41: 202.5~205℃ fraction, 51: >205℃ heavy fraction. Detailed Implementation

[0068] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited by these specific embodiments, but is determined by the claims.

[0069] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0070] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0071] It should be noted that the two or more aspects (or embodiments) disclosed in the context of this specification can be arbitrarily combined with each other, and the resulting technical solutions (such as methods or systems) are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0072] In this invention, the XRD determination of layered mordenite zeolite was performed on a Bruker D8 Advance SS powder X-ray diffractometer, with a Cu Kα ray source, tube voltage of 40 kV, tube current of 300 mA, and scan rate of 5. o / min.

[0073] In this invention, the method for determining the relative crystallinity is to use commercial mordenite zeolite (SiO2 / Al2O3=16) from the catalyst factory of Nankai University as a standard sample. This sample has high crystallinity, which is assumed to be 100%. Then, the sum of the intensities of eight strong line peaks with d values ​​of 9.11, 6.60, 4.52, 3.98, 3.46, 3.38, 3.23, and 2.89 on the X-ray diffraction pattern is compared, that is, the sum of the peak areas of the sample is divided by the sum of the peak areas of the standard sample.

[0074] In this invention, scanning electron microscopy (SEM) tests were performed on a Nova Nano SEM 450 from FEI Corporation in the United States, with an accelerating voltage of 30 kV.

[0075] In this invention, the specific surface area and external surface area are measured on a Micrometrics ASAP-2010 physical adsorption instrument. N2 is the adsorbed gas, adsorbed at liquid nitrogen temperature (-196℃) and desorbed at room temperature. The specific surface area and external specific surface area are calculated based on the amount of N2 desorbed according to the BET model.

[0076] The catalyst of this invention was evaluated using a 100ml fixed-bed adiabatic reactor with a catalyst loading of 60ml. Before feeding, the catalyst underwent reduction and activation treatment. Two hours after feeding, the product was analyzed for composition, and the conversion rate of the typical interfering component, methyl indane, was calculated. The liquid product was collected and separated in a distillation column, and the fraction collected at 202.5–205℃ was analyzed for composition. Example 1

[0077] The preparation steps of the catalyst in this embodiment are as follows:

[0078] (1) Mordenite zeolite was prepared by hydrothermal synthesis: Silica, sodium hydroxide, and sodium aluminate were dissolved in water to prepare material A; tetraethylammonium bromide, hexadecyltrimethylammonium bromide, and sodium hydroxide were dissolved in water to prepare material B. Under vigorous stirring, material B was slowly added dropwise to material A, and the pH of the solution was adjusted to 12 by adding 10wt% sodium hydroxide aqueous solution. The mixture was stirred thoroughly. The silicon source was calculated as SiO2, the aluminum source a as Al2O3, and the alkali source as OH... - The molar ratios of the materials are calculated as follows: SiO2 / Al2O3 = 18.19, T / SiO2 = 0.03, T1 / T2 = 1.8, H2O / SiO2 = 12.57, OH... - / SiO2=0.20. After thorough mixing at room temperature, the resulting gel was crystallized at 170℃ for 5 hours, filtered, washed, dried at 120℃, and calcined at 550℃ to obtain a sodium-type zeolite sample. Using a 10wt% ammonium nitrate solution as the ammonium exchanger, the above sodium-type zeolite was subjected to ammonium exchange three times at 90℃ under a solid-liquid ratio of 1:10. After filtration, washing, drying at 120℃, and calcining at 550℃, hydrogen-type layered mordenite was obtained.

[0079] The XRD pattern of layered mordenite is shown below. Figure 3 Appearance and morphology Figure 4 The zeolite exhibits a plate-like structure, with individual plate-shaped crystals growing orderly along the c-axis, i.e., the thickness direction of the plate. The thickness of an individual plate-shaped crystal is between 90-120 nm along the c-axis, and the relative crystallinity is 93.8%. The silica-alumina molar ratio of the layered mordenite, calculated as silica / alumina, is 15.2, and the zeolite specific surface area is 416.5 m². 2 / g, with an external specific surface area of ​​176.8 m². 2 / g.

[0080] (2) Take 100g of hydrogen-type mordenite, 20g of pseudoboehmite, 5g of guar gum powder, 24g of 2.5wt.% nitric acid solution and an appropriate amount of water, mix thoroughly, and then extrude into cylindrical strips (1.8 mm in diameter). After drying at 120℃ for 8 hours and calcining at 550℃ for 3 hours, the catalyst support is obtained. The amount of hydrogen-type layered mordenite molecular sieve added is 87.7% of the dry weight of the catalyst support; the amount of aluminum source added is 17.5% of the dry weight of the catalyst support; the amount of extrusion aid added is 4.4% of the dry weight of the catalyst support; and the amount of nitric acid solution added is 1.0 to 1.3 of the mass ratio of aluminum source b.

[0081] (3) Pt with a loading weight ratio of 0.1wt% was obtained by equal volume impregnation on the support, and after drying at 120℃ for 8 hours and calcining at 450℃ for 4 hours, catalyst CAT-1 was obtained.

[0082] The heavy aromatics feedstock comes from a tetramethylbenzene-rich unit that has been separated by distillation. The tetramethylbenzene-rich fraction with a distillation range of 190~205℃ is selected by distillation pre-separation. By weight percentage, it consists of 19.75% mesitylene, 36.36% paratetramethylbenzene, 23.62% methyltetramethylbenzene, 5.50% methyl indene, 7.39% methyl isobutylbenzene, and 7.38% other components.

[0083] The hydrocracking reaction conditions for the catalyst were: reaction temperature 400℃, reaction pressure 3.5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500. The catalyst obtained in Example 1 needs to be reduced and activated before use, that is, the metal oxide on the support is converted into an active metal under a reducing atmosphere. The reduction and activation conditions are as follows: hydrogen partial pressure 0.5 MPa, reduction temperature 400 °C, and volume hourly space velocity 120 h⁻¹. -1 The reduction time was 12 hours. The reaction results are shown in Table 1.

[0084] The reaction process is as follows: hydrocracking reaction + tetramethylbenzene separation ( Figure 1 Heavy aromatics feedstock 1 and hydrogen 2 are fed into hydrocracking reactor 3 for hydrocracking. After gas-liquid separation by gas-liquid separator 4, gaseous product 5 is collected from the gas-liquid separator, and liquid product enters distillation column 6. The fraction 7 below 202.5℃ is collected from the top of the column, high-purity tetramethylbenzene 8 is collected from the side of distillation column 6, and a small amount of heavy fraction 9 above 205℃ is collected from the bottom of distillation column 6. The tetramethylbenzene fraction between 202.5℃ and 205℃ is separated and collected by distillation column for purity analysis. The results are shown in Table 1.

[0085] The parameters of the distillation column are as follows: 133 trays, operating vacuum of -10 kPa, top temperature of 126℃, bottom temperature of 186℃, and reflux ratio of 3.0. Example 2

[0086] The catalyst preparation steps in this embodiment are the same as in Example 1. The difference lies in the adjustment of the material ratios during the hydrothermal synthesis of mordenite. Specifically, the molar ratios are SiO2 / Al2O3 = 16, T / SiO2 = 0.1, T1 / T2 = 1.5, H2O / SiO2 = 18, and OH... - / SiO2=0.2. XRD pattern of mordenite is shown in [reference needed]. Figure 5 The thickness of individual lamellar crystals of the mordenite is between 90-120 nm along the c-axis, with a relative crystallinity of 93%. The silica-alumina molar ratio of the layered mordenite, calculated as silica / alumina, is 13.7, and the zeolite specific surface area is 398.4 m². 2 / g, with an external specific surface area of ​​169.2m². 2 / g.

[0087] The heavy aromatics feedstock, catalyst reduction and reaction conditions, reaction process, and distillation column operating parameters were the same as in Example 1. The reaction results are shown in Table 1. Example 3

[0088] The preparation steps of the catalyst in this embodiment are the same as those in Example 1. The difference is in the support forming process: 100g of hydrogen-type mordenite, 20g of pseudoboehmite, 5g of guar gum powder, 20g of 2.5wt.% nitric acid solution and an appropriate amount of water are mixed and kneaded, and then extruded, dried and calcined to obtain the catalyst support.

[0089] The heavy aromatics feedstock, catalyst reduction and reaction conditions, reaction process, and distillation column operating parameters were the same as in Example 1. The reaction results are shown in Table 1. Example 4

[0090] The catalyst preparation method in this embodiment is the same as in Example 1. The difference between Example 1 and Example 1 is that the heavy aromatic raw material is hydroreformed C10 heavy aromatics, which, by weight percentage, is 6.6% methyltetramethylene, 13.4% p-methyltetramethylene, 10.8% methyltetramethylene, 1.67% methylindene, 3.04% methyl isobutylbenzene, and 64.49% other components.

[0091] The hydrogenation and reduction conditions of the catalyst, as well as the operating parameters of the distillation column, were the same as in Example 1. The reaction results are shown in Table 1. Example 5

[0092] The catalyst preparation method in this embodiment is the same as in Example 2, and the reaction process is: hydrocracking reaction + tetramethylbenzene separation ( Figure 1 The heavy aromatics feedstock is hydroreformed C10 heavy aromatics, which, by weight percentage, consist of 6.6% mesitylene, 13.4% paratetramethylbenzene, 10.8% methyltetramethylbenzene, 1.67% methyl indene, 3.04% methyl isobutylbenzene, and 64.49% other components.

[0093] The hydrocracking reaction conditions and catalyst reduction conditions were the same as in Example 1, and the reaction results are shown in Table 1. Comparative Example 1

[0094] This comparative example did not undergo hydrocracking and used the same heavy aromatics feedstock as in Example 1 (19.75% mesitylene, 36.36% pseudotetramethylbenzene, 23.62% methyltetramethylbenzene, 5.50% methylindene, 7.39% methyl isobutylbenzene, and 7.38% other components by weight percentage). As in Example 1, the mixture was directly fed into a distillation column for separation, and the purity of the methyltetramethylbenzene was collected from the fraction at 202.5–205 °C for analysis. The results are shown in Table 1.

[0095] See process flow Figure 2Using reformed C10 heavy aromatics 11 as raw material, it is directly fed into distillation column 21 for separation. The top of distillation column 21 is the fraction 3 with a temperature of <202.5℃, the side of distillation column 21 is the fraction 41 with a temperature of 400-400℃, and the bottom of distillation column 21 is the heavy fraction 51 with a temperature of >205℃. Comparative Example 2

[0096] This comparative example did not undergo hydrocracking and used the same heavy aromatics feedstock as in Example 4 (by weight percentage: mesitylene 6.6%, pseudotetramethylbenzene 13.4%, methyltetramethylbenzene 10.8%, methylindene 1.67%, methyl isobutylbenzene 3.04%, and other components 64.49%). Similar to Example 4, the mixture was directly fed into a distillation column for separation. The purity of the methyltetramethylbenzene was collected in the 202.5–205°C fraction for analysis. The results are shown in Table 1. The process flow is shown in Comparative Example 1.

[0097] Table 1 Evaluation results of different catalysts

[0098]

Claims

1. A method for producing quadricylene, the process comprising: contacting a heavy aromatic hydrocarbon feedstock with a hydrocracking catalyst to perform a hydrocracking reaction to obtain a reaction crude product, and then performing a rectification separation to obtain a quadricylene product; the hydrocracking catalyst comprising: (a) a support comprising a layered mordenite; (b) at least one of a Group VIII metal as an active component; the layered mordenite having a sheet-like structure, and individual sheet crystals grow in order along a c-axis, i.e. a sheet thickness direction, and the thickness of the individual sheet crystals, i.e. the c-axis thickness, is 90-120 nm; the heavy aromatic hydrocarbon feedstock is a tetramethylbenzene-rich fraction having a distillation range of 190-205°C obtained by rectification separation; The reaction conditions of the hydrocracking reaction are as follows: reaction temperature 300-600℃, reaction pressure 1.0-6.0 MPa, volume space velocity 0.5-5.0 h -1 , hydrogen / oil volume ratio 200-1000.

2. The method of claim 1, wherein, the heavy aromatic hydrocarbon feedstock is a heavy reformate C10 hydrocarbon feedstock after hydrogenation.

3. The method of claim 2, wherein, in the heavy reformate C10 hydrocarbon feedstock after hydrogenation, the weight percentage of mesitylene is 4.0-15.5%, the weight percentage of durene is 10.0-20.0%, the weight percentage of quadricylene is 4.5-15.0%, the weight percentage of methylindane is 1.0-5.0%, the weight percentage of methylisobutylbenzene is 0.5-5.0%, and the weight percentage of other components is 39.5-80.0%.

4. The method of claim 1, wherein, in the tetramethylbenzene-rich fraction having a distillation range of 190-205°C, the mass percentage of mesitylene is 10.0-21.5%, the mass percentage of durene is 20.0-38.5%, the mass percentage of quadricylene is 10.0-25.5%, the mass percentage of methylindane is 2.0-6.3%, the mass percentage of methylisobutylbenzene is 2.0-8.2%, and the mass percentage of other components is 0-56.0%.

5. The method of claim 1, wherein, the purity of the quadricylene product is greater than 97%.

6. The method of claim 5, wherein, the purity of the quadricylene product is 97-99%.

7. The method of claim 1, wherein, The layered mordenite has a specific surface area of 300 to 450 m 2 / g; and an external specific surface area of 100 to 200 m 2 / g.

8. The method of claim 7, wherein, The layered mordenite has a specific surface area of 350 to 430 m 2 / g; and an external specific surface area of 150 to 200 m 2 / g.

9. The method of claim 1, wherein, the rectification separation is performed by a rectification column to obtain the quadricylene product, and the operating conditions of the rectification separation can be as follows: the number of plates is 120-150, the operating vacuum is -8 to -20 kPa, the overhead temperature is 120-140°C, the bottom temperature is 175-190°C, and the reflux ratio is 2.0-4.0.

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