A method for lightening C10+ heavy aromatics

Abstract

The present invention discloses a method for lightening C10+ heavy aromatics. The C10+ heavy aromatic feedstock sequentially enters a hydrogenation saturation zone, a hydrogenation ring-opening zone, a dealkylation reaction zone, and a transalkylation reaction zone. The reaction products are separated to obtain BTX. This method achieves the targeted conversion of C10+ aromatics to light aromatics through zone-specific intensification. While increasing the yield of light aromatics, it significantly reduces side reactions such as aromatic condensation to carbon deposition and aromatic saturation, significantly extending catalyst life.

Description

Technical Field

[0001] The present invention relates to the field of comprehensive utilization of C10+ heavy aromatics, and relates to a method for producing high-value products by lightening C10+ heavy aromatics, and specifically to a method for producing the high-value product BTX from C10+ heavy aromatics. Background Art

[0002] C10+ aromatics primarily originate from naphtha catalytic reforming, catalytic cracking, and steam cracking processes. Their composition is highly complex, primarily consisting of monocyclic aromatics, along with smaller amounts of tricyclic aromatics and cycloalkanes. Currently, there are no promising utilization pathways or target markets. Some companies directly separate high-value chemical products such as durene, unsymmetrical tetramethylbenzene, naphthalene, and methylnaphthalene, but these contain relatively low levels of aromatics. Others use them as feedstock for diesel hydrotreating to increase diesel production, but this processing is challenging and affects the diesel product's cetane number and jet fuel smoke point, making them uneconomical. Therefore, companies urgently need resourceful solutions for the recovery of C10+ heavy aromatic tail oil.

[0003] CN201910977804.X adopts a two-stage conversion scheme: C10+ heavy aromatic hydrocarbon feedstock oil is first subjected to selective hydrogenation saturation reaction under mild conditions, and the obtained hydrogenation saturated product is then subjected to hydrocracking reaction to obtain a logistics including C6~C8 aromatics, C9 / C10 heavy aromatics and C10+ heavy aromatics; the heavy tail oil fraction containing C10+ heavy aromatics after separation of the hydrocracking product is recycled back to the hydrogenation saturation reaction.

[0004] CN104357083A discloses a method for producing light aromatics from C10+ heavy aromatics. Similar to traditional refinery-type hydrocracking processes, pre-hydrogenation and hydrocracking reactors are directly connected in series to produce light aromatics or high-octane gasoline blending components. The pre-hydrogenation reaction achieves selective saturation of condensed-ring aromatics. The hydrocracking catalyst is derived from one or more of β molecular sieve, Y molecular sieve, and mordenite supported with precious metals such as Pt and Pd.

[0005] The C10+ heavy aromatics processing methods disclosed in the prior art have the problems of many aromatics condensation side reactions, obvious carbon deposition, short catalyst life or many aromatics saturation side reactions and high aromatic loss rate. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides a method for converting C10+ heavy aromatics to lighter hydrocarbons. This method achieves targeted conversion of C10+ aromatics to light aromatics through zoned intensification. While increasing the yield of light aromatics, it significantly reduces side reactions such as aromatic condensation to carbon deposition and aromatic saturation, significantly extending catalyst life.

[0007] A method for lightening C10+ heavy aromatics, wherein C10+ heavy aromatics raw materials successively enter a hydrogenation saturation zone, a hydrogenation ring-opening zone, a dealkylation reaction zone and a transalkylation reaction zone, and the reaction products are separated to obtain BTX.

[0008] In the method of the present invention, the C10+ heavy aromatic hydrocarbon raw material contains 20-70 wt% of monocyclic aromatic hydrocarbons, 20-70 wt% of dicyclic aromatic hydrocarbons, 1-10 wt% of tricyclic aromatic hydrocarbons, a sulfur content of less than 20 ppm, and a nitrogen content of less than 50 ppm.

[0009] In the method of the present invention, the hydrogenation ring-opening zone, the dealkylation reaction zone and the transalkylation reaction zone can be completed in one reactor or divided into multiple reactors.

[0010] In the method of the present invention, the fraction with a temperature of 65 to 145° C. obtained after separation of the reaction product is a product rich in BTX components, the fraction with a temperature greater than 145 to 210° C. is circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210° C. is circulated to the inlet of the hydrogenation saturation reaction zone.

[0011] In the method of the present invention, the hydrogenation saturation reaction zone can be filled with a commercial hydrorefining catalyst, such as FF-56 and FF-66 developed by Dalian Petrochemical Research Institute, etc. The reaction pressure is 2.0~8.0MPa, preferably 3.0~6.0MPa; the hydrogen-to-oil volume ratio is 50:1~600:1, preferably 200:1~400:1; the liquid hourly volume space velocity is 0.5~3h -1 , preferably 1.0~2h -1 ; The reaction temperature is 150~300℃, preferably 200~280℃.

[0012] In the method of the present invention, the hydrogenation ring-opening reaction zone can be filled with a commercial hydrocracking catalyst, such as HC-35 from UOP, or can be prepared using existing technologies. The reaction pressure is 2.0-8.0 MPa, preferably 3.0-6.0 MPa; the hydrogen-to-oil volume ratio is 50:1-600:1, preferably 200:1-400:1; and the liquid hourly space velocity is 1.0-5.0 h -1 , preferably 2.0~4.0h -1 ; The reaction temperature is 350~450℃, preferably 380~420℃.

[0013] In the method of the present invention, the dealkylation reaction zone is filled with a dealkylation catalyst having a modified ZSM-5 molecular sieve as the main component. The dealkylation catalyst contains a modified ZSM-5 molecular sieve, a binder, and a precious metal. Based on the weight of the dealkylation catalyst, the modified ZSM-5 molecular sieve is contained in an amount of 50 wt% to 90 wt%, and the precious metal content is recorded as 0.1 wt% to 2.0 wt% as a single substance. The total acid content of the dealkylation catalyst is 0.05 to 0.12 mmol / g, the pore-external acid content is not higher than 0.005 mmol / g, preferably 0.1 μmol / g to 2 μmol / g, and the pore volume is 0.18 to 0.30 cm 3 / g, of which the micropore volume is 0.03~0.09cm 3 / g, 0.1wt%~2.0wt%.

[0014] In the method of the present invention, the reaction pressure of the dealkylation reaction zone is 1.0-5.0 MPa, preferably 2.0-4.0 MPa; the hydrogen-to-oil volume ratio is 50:1-600:1, preferably 200:1-400:1; the liquid hourly volume space velocity is 2.0-10.0 h -1 , preferably 3.0~6.0h -1 ; The reaction temperature is 350~450℃, preferably 380~420℃.

[0015] In the method of the present invention, the transalkylation reaction zone is loaded with a transalkylation catalyst primarily composed of a modified Beta molecular sieve. The transalkylation catalyst comprises the modified Beta molecular sieve, a binder, and a precious metal, with the modified Beta molecular sieve comprising 20 wt% to 60 wt% of the modified Beta molecular sieve, and the precious metal comprising 0.1 wt% to 2.0 wt% of the elemental precious metal.

[0016] In the method of the present invention, the total acid content of the transalkylation catalyst is 0.25-0.45 mmol / g, the acid content outside the pores is not higher than 0.01 mmol / g, preferably 0.5 μmol / g-5 μmol / g, and the pore volume is 0.30-0.45 cm 3 / g, of which the micropore volume is 0.15~0.30cm 3 / g.

[0017] In the method of the present invention, the reaction pressure of the transalkylation reaction zone is 1.0-5.0 MPa, preferably 2.0-4.0 MPa; the hydrogen-to-oil volume ratio is 50:1-600:1, preferably 200:1-400:1; the liquid hourly volume space velocity is 4.0-20.0 h -1 , preferably 8.0~12.0h -1 ; The reaction temperature is 350~450℃, preferably 380~420℃.

[0018] Compared with the prior art, the method for lightweighting C10+ heavy aromatics of the present invention has the following advantages:

[0019] (1) The present invention designs an optimized reaction path based on the analysis of the raw material spectrum and product spectrum of the C10+ heavy aromatics lightening process, and then divides the reaction process into a hydrogenation saturation zone, a hydrogenation ring-opening zone, a dealkylation reaction zone, and an alkylation translocation reaction zone, respectively realizing partial saturation of polycyclic aromatic hydrocarbons, ring-opening of saturated rings in partially saturated polycyclic aromatic hydrocarbons to obtain dealkylation of long side-chain monocyclic aromatic hydrocarbons, and alkylation translocation of polymethylbenzenes with benzene / toluene, and respectively loading the most suitable catalyst to guide the reactant molecules to the designed optimal path, thereby improving the BTX yield;

[0020] (2) The present invention selectively masks the acidity outside the pores of ZSM-5 molecular sieves and Beta molecular sieves, avoiding the adsorption and condensation of larger molecules in the mesopores and external surfaces, reducing carbon deposition, and increasing the service life of the catalyst. Implementation Method

[0021] In an embodiment of the present invention, the preparation method of the modified ZSM-5 molecular sieve or modified Beta molecular sieve comprises the following steps:

[0022] (1) hydrothermally treating ZSM-5 molecular sieve raw powder or Beta molecular sieve raw powder;

[0023] (2) impregnating the material obtained in step (1) with a pore protection liquid;

[0024] (3) treating the material obtained in step (2) with a highly sterically hindered organic acid;

[0025] (4) mixing the material obtained in step (3) with a dealumination and siliconization reagent to carry out dealumination and siliconization;

[0026] (5) The material obtained in step (4) is filtered, washed, dried, and calcined to obtain a modified molecular sieve.

[0027] Furthermore, in step (1), the ZSM-5 molecular sieve can be a commercially available product or prepared according to existing technology. The properties of the ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio is 30-100.

[0028] Furthermore, in step (1), the Beta molecular sieve can be a commercially available product or prepared according to existing technology. The properties of the Beta molecular sieve are as follows: a SiO2 / Al2O3 molar ratio of 20 to 40.

[0029] Furthermore, in step (1), the specific treatment process in the hydrothermal process is: placing a commercially available molecular sieve in a hydrothermal furnace, introducing water vapor, and treating it at a temperature of 400°C to 600°C and a pressure of 0.05 to 0.2 MPa for 1 hour to 3 hours.

[0030] Furthermore, in step (2), the pore protection solution is one or more of isopropylamine solution, tetraethylammonium hydroxide solution, tetrapropylammonium hydroxide solution, etc. The concentration of the pore protection solution is 0.8-2.0 mol / L, preferably 1.1-1.5 mol / L.

[0031] Furthermore, in step (2), the impregnation is preferably equal volume impregnation. The impregnation temperature is room temperature, generally 20-25°C.

[0032] Furthermore, in step (3), the highly sterically hindered organic acid is one or more of 2,4-dimethylbenzenesulfonic acid and 2,5-dimethylbenzoic acid.

[0033] Furthermore, in step (3), the specific operation is as follows: first, the material obtained in step (2) is mixed with water, wherein the liquid-to-solid volume ratio of water to the material obtained in step (2) is 2:1 to 6:1, and then an organic acid is added until the pH value of the solution drops below 8, preferably 6.5 to 7.5.

[0034] Furthermore, in step (4), the dealuminized siliconizing agent is at least one of an ammonium hexafluorosilicate solution and an ethyl orthosilicate solution. The molar concentration of the dealuminized siliconizing agent is 0.3 to 1.0 mol / L. The mass ratio of the material obtained in step (4) to the dealuminized siliconizing agent is 1:1 to 1:5. The mixing temperature is 60 to 100°C.

[0035] Furthermore, the specific operation process of step (4) is as follows: the material obtained in step (3) is rapidly heated to 60-100°C, and continuously stirred, and the dealumination and siliconization reagent is added dropwise, and stirring is continued for 60-120 minutes after the addition is completed. The addition rate does not exceed 0.5 mL / min·g of the material obtained in step (3); preferably, it is 0.2-0.4 mL / min·g of the material obtained in step (3).

[0036] Furthermore, in step (5), the filtration and washing can be carried out by conventional methods in the art, the drying temperature is 100°C to 150°C, and the drying time is 2 to 4 hours; the roasting temperature is 400°C to 600°C; and the roasting time is 3 to 5 hours.

[0037] In the embodiment of the present invention, the preparation process of the dealkylation catalyst or the transalkylation catalyst is as follows:

[0038] (1) The modified molecular sieve and aluminum sol binder are kneaded, extruded, and formed, and then dried and calcined to obtain a catalyst carrier;

[0039] (2) The catalyst carrier is impregnated with an equal volume of a solution containing a precious metal, and then dried and calcined to obtain the final dealkylation catalyst or transalkylation catalyst.

[0040] Furthermore, the noble metal is one or more of platinum, palladium or ruthenium.

[0041] The following examples and comparative examples are used to further illustrate the effects and benefits of the technical solutions of the present invention. However, the following examples do not limit the scope of protection of the present invention.

[0042] In the present invention, % involved in the embodiments and comparative examples are all mass fractions unless otherwise specified.

[0043] In the present invention, the total acid content is determined by the following method: the powdered catalyst is pressed into pellets, evacuated, and then degassed at 450°C for 2 hours. After cooling to room temperature, a pyridine molecule with a kinetic diameter of 5Å is used as a probe molecule. The infrared spectrum of chemical desorption is measured and the adsorption amount is calculated. Because the diameter of the pyridine molecule is smaller than the pores of the molecular sieve, this method can determine the total acid content.

[0044] In the present invention, the method for determining the amount of external acid in the micropores is as follows: a powdered catalyst is pressed into a pellet, evacuated, and then degassed at 450°C for 2 hours. After the temperature is cooled to room temperature, a 2,6-di-tert-butylpyridine molecule is used as a probe molecule, and its chemical desorption infrared spectrum is measured to calculate the adsorption amount. Because the diameter of the 2,6-di-tert-butylpyridine molecule is larger than the micropores of the molecular sieve, this method can determine the amount of external acid in the micropores.

[0045] In this invention, pore volume and micropore volume were measured by physical adsorption using an ASAP 2420 low-temperature liquid nitrogen physical adsorption instrument manufactured by MICROMERITICS (USA). Prior to measurement, the sample was calcined at 550°C for 4 hours to remove the template. During testing, the sample was pretreated at 300°C for 3 hours and then subjected to nitrogen adsorption at 77K.

[0046] The calculation formula for the conversion rate of C10+ heavy aromatics in the embodiment is:

[0047] Conversion rate = mass of all fractions below 195°C in the product / mass of raw materials * 100%

[0048] The BTX selectivity calculation formula in the embodiment is:

[0049] BTX selectivity = mass of C6~C8 in the product / mass of all fractions below 195℃ in the product * 100%

[0050] The Examples and Comparative Examples all used C10+ heavy aromatics from a refinery as raw materials, the composition of which is shown in Table 1.

[0051] Table 1 C10+ heavy aromatics feedstock of a refinery

[0052]

[0053] Example 1

[0054] CAT-1 was obtained according to the method of the present invention. Its properties are as follows: total acid content is 0.09 mmol / g, pore external acid content is 1.0 μmol / g, pore volume is 0.28 cm 3 / g, of which the micropore volume is 0.07cm 3 / g, the Pt content (calculated as a single substance) is 0.5wt%, and the content of modified ZSM-5 molecular sieve is 80 wt%.

[0055] CAT-2 was obtained according to the method of the present invention. Its properties are as follows: total acid content is 0.43 mmol / g, pore external acid content is 1.4 μmol / g, pore volume is 0.43 cm 3 / g, of which the micropore volume is 0.26cm 3 / g, the Pt content (calculated as a single substance) is 0.5wt%, and the modified Beta molecular sieve content is 30wt%.

[0056] CAT-3 was obtained according to the method of the present invention. Its properties are as follows: total acid content is 0.11 mmol / g, pore external acid content is 2.1 μmol / g, pore volume is 0.20 cm 3 / g, of which the micropore volume is 0.04cm 3 / g, the Pt content (calculated as a single substance) is 0.5wt%, and the content of modified ZSM-5 molecular sieve is 40 wt%.

[0057] CAT-4 was obtained according to the method of the present invention. Its properties are as follows: total acid content is 0.27 mmol / g, pore external acid content is 4.5 μmol / g, pore volume is 0.32 cm 3 / g, of which the micropore volume is 0.17cm 3 / g, the Pt content (calculated as a single substance) is 0.5wt%, and the modified Beta molecular sieve content is 70wt%.

[0058] Example 1-1

[0059] The dealkylation catalyst support CAT-1BS was obtained by rolling and mixing H-ZSM-5 raw powder and aluminum sol binder in a dry weight ratio of 80:20. The mixture was then extruded, dried, and calcined to obtain CAT-1BS. The support was then impregnated with ammonium chloroplatinate solution to obtain CAT-1B. Its properties are as follows: total acid content of 0.25 mmol / g, extra-pore acid content of 0.012 mmol / g, and a pore volume of 0.27 cm. 3 / g, of which the micropore volume is 0.12cm 3 / g, and the Pt content (as a single substance) is 0.5wt%.

[0060] The dealkylation catalyst support CAT-2BS was obtained by rolling and mixing H-Beta raw powder and aluminum sol binder in a dry weight ratio of 70:30, extruding, drying, and calcining. The support was impregnated with ammonium chloroplatinate solution to obtain CAT-2B. Its properties are as follows: total acid content of 0.57 mmol / g, extra-pore acid content of 0.027 mmol / g, and pore volume of 0.40 cm 3 / g, of which the micropore volume is 0.32cm 3 / g, and the Pt content (as a single substance) is 0.5wt%.

[0061] Example 2

[0062] The hydrogenation saturation zone, hydrogenation ring-opening zone, dealkylation reaction zone, and transalkylation reaction zone were respectively loaded with presulfurized FF-66, HC-35, CAT1, and CAT2. After passing through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases were separated and then entered the subsequent reaction zone. The fraction with a temperature of 145-210°C was circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C was circulated to the inlet of the hydrogenation saturation reaction zone. The operation was carried out for 168 hours (the operation time of the following examples and comparative examples is the same). The conditions of each reaction zone are shown in Table 2. + The conversion rate of heavy aromatics was 34wt%, the BTX selectivity was 81.3wt%, and the catalyst carbon deposition amount was 1.5wt%.

[0063] Table 2 Conditions of each reaction zone in Example 2

[0064]

[0065] Comparative Example 1

[0066] The hydrogenation saturation zone is loaded with pre-sulfurized FF-66 catalyst. The cracking section does not distinguish between the hydrogenation ring-opening zone, dealkylation reaction zone, and transalkylation reaction zone, and is uniformly loaded with HC-35. The reactant stream passes through the hydrogenation saturation zone, and the generated hydrogen sulfide and other gases are separated before entering the subsequent reaction zone. The fraction with a temperature greater than 145°C is recycled to the entrance of the hydrogenation saturation reaction zone. The conditions are shown in Table 3.+ The conversion rate of heavy aromatics was 30wt%, the BTX selectivity was 67.3wt%, and the catalyst carbon deposition amount was 2.5wt%.

[0067] Table 3 Conditions of each reaction zone in Comparative Example 1

[0068]

[0069] Example 2-1

[0070] The hydrogenation saturation zone, hydrogenation ring-opening zone, dealkylation reaction zone, and transalkylation reaction zone are respectively loaded with presulfurized FF-66, HC-35, CATB1, and CATB2. After the reactant stream passes through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases are separated and then enter the subsequent reaction zone. The fraction with a temperature of 145-210°C is recycled to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C is recycled to the inlet of the hydrogenation saturation reaction zone. The conditions of each reaction zone are shown in Table 4. + The conversion rate of heavy aromatics was 39wt%, the BTX selectivity was 81.3wt%, and the catalyst carbon deposition was 2.6wt%.

[0071] Table 4 Conditions of each reaction zone in Example 2-1

[0072]

[0073] Example 3

[0074] The hydrogenation saturation zone, hydrogenation ring opening zone, dealkylation reaction zone, and transalkylation reaction zone are respectively loaded with pre-sulfurized FF-66, HC-35, CAT1, and CAT2. After the reactant stream passes through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases are separated and then enter the subsequent reaction zone. The fraction with a temperature of 145-210°C is recycled to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C is recycled to the inlet of the hydrogenation saturation reaction zone. The conditions of each reaction zone are shown in Table 5. + The conversion rate of heavy aromatics was 72wt%, the BTX selectivity was 74.3wt%, and the catalyst carbon deposition amount was 1.6 wt%.

[0075] Table 5 Conditions of each reaction zone in Example 3

[0076]

[0077] Example 4

[0078] The hydrogenation saturation zone, hydrogenation ring opening zone, dealkylation reaction zone, and transalkylation reaction zone are respectively loaded with pre-sulfurized FF-66, HC-35, CAT3, and CAT4. After passing through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases are separated and then enter the subsequent reaction zone. The fraction with a temperature of 145-210°C is recycled to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C is recycled to the inlet of the hydrogenation saturation reaction zone. The conditions of each reaction zone are shown in Table 6. + The conversion rate of heavy aromatics was 52wt%, the BTX selectivity was 82.3wt%, and the catalyst carbon deposition amount was 1.7wt%.

[0079] Table 6 Conditions of each reaction zone in Example 4

[0080]

[0081] Example 5

[0082] The hydrogenation saturation zone, hydrogenation ring opening zone, dealkylation reaction zone, and transalkylation reaction zone are respectively loaded with pre-sulfurized FF-66, HC-35, CAT1, and CAT2. After the reactant stream passes through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases are separated and then enter the subsequent reaction zone. The fraction with a temperature of 145-210°C is recycled to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C is recycled to the inlet of the hydrogenation saturation reaction zone. The conditions of each reaction zone are shown in Table 7. + The conversion rate of heavy aromatics was 47wt%, the BTX selectivity was 81.2wt%, and the catalyst carbon deposition amount was 1.6wt%.

[0083] Table 7 Conditions of each reaction zone in Example 5

[0084]

[0085] Example 6

[0086] The hydrogenation saturation zone, hydrogenation ring-opening zone, dealkylation reaction zone, and transalkylation reaction zone are respectively loaded with pre-sulfurized FF-66, HC-35, CAT1, and CAT4. After the reactant stream passes through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases are separated and then enter the subsequent reaction zone. The fraction with a temperature of 145-210°C is recycled to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C is recycled to the inlet of the hydrogenation saturation reaction zone. The conditions of each reaction zone are shown in Table 8. + The conversion rate of heavy aromatics was 58wt%, the BTX selectivity was 84.3wt%, and the catalyst carbon deposition amount was 1.8wt%.

[0087] Table 8 Conditions of each reaction zone in Example 6

[0088]

[0089] Example 7

[0090] The hydrogenation saturation zone, hydrogenation ring opening zone, dealkylation reaction zone, and transalkylation reaction zone are respectively loaded with presulfurized FF-66, conventionally prepared precious metal hydrocracking catalysts HCAT, CAT3, and CAT2. After the reactant stream passes through the hydrogenation saturation zone, the generated hydrogen sulfide and other gases are separated and then enter the subsequent reaction zone. The fraction with a temperature of 145-210°C is recycled to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210°C is recycled to the inlet of the hydrogenation saturation reaction zone. The conditions of each reaction zone are shown in Table 9. + The conversion rate of heavy aromatics was 61wt%, the BTX selectivity was 82.6wt%, and the catalyst carbon deposition was 1.5%.

[0091] Table 9 Conditions of each reaction zone in Example 7

[0092]

Claims

1. A method for lightweighting C10+ heavy aromatics, characterized by: The C10+ heavy aromatics feedstock enters the hydrogenation saturation zone, hydrogenation ring opening zone, dealkylation reaction zone and transalkylation reaction zone in sequence, and the reaction products are separated to obtain BTX; The dealkylation reaction zone is filled with a dealkylation catalyst with modified ZSM-5 molecular sieve as the main component; The total acid content of the dealkylation catalyst is 0.05-0.12 mmol / g, the acid content outside the pores is not higher than 0.005 mmol / g, and the pore volume is 0.18-0.30 cm 3 / g, of which the micropore volume is 0.03~0.09cm 3 / g; The transalkylation reaction zone is filled with a transalkylation catalyst with modified Beta molecular sieve as the main component; The total acid content of the transalkylation catalyst is 0.25-0.45 mmol / g, the external acid content of the pores is not higher than 0.01 mmol / g, and the pore volume is 0.30-0.45 cm 3 / g, of which the micropore volume is 0.15~0.30cm 3 / g.

2. The method according to claim 1, wherein: The C10+ heavy aromatic hydrocarbon feedstock contains 20-70 wt% of monocyclic aromatic hydrocarbons, 20-70 wt% of dicyclic aromatic hydrocarbons, 1-10 wt% of tricyclic aromatic hydrocarbons, a sulfur content of less than 20 ppm, and a nitrogen content of less than 50 ppm.

3. The method according to claim 1, wherein: The fraction with a temperature of 65 to 145° C. obtained after separation of the reaction products is a product rich in BTX components, the fraction with a temperature of 145 to 210° C. is circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature greater than 210° C. is circulated to the inlet of the hydrogenation saturation reaction zone.

4. The method according to claim 1, wherein: The reaction pressure of the hydrogenation saturation reaction zone is 2.0~8.0MPa, the hydrogen-to-oil volume ratio is 50:1~600:1, and the liquid hourly volume space velocity is 0.5~3h -1 , the reaction temperature is 150~300℃.

5. The method according to claim 4, characterized in that: The reaction pressure of the hydrogenation saturation reaction zone is 3.0~6.0MPa, the hydrogen-oil volume ratio is 200:1~400:1, and the liquid hourly volume space velocity is 1.0~2h -1 , the reaction temperature is 200~280℃.

6. The method according to claim 1, wherein: The reaction pressure of the hydrogenation ring-opening reaction zone is 2.0-8.0 MPa, the hydrogen-to-oil volume ratio is 50:1-600:1, and the liquid hourly volume space velocity is 1.0-5.0 h -1 , the reaction temperature is 350~450℃.

7. The method according to claim 6, characterized in that: The reaction pressure in the hydrogenation ring-opening reaction zone is 3.0-6.0 MPa, the hydrogen-to-oil volume ratio is 200:1-400:1, and the liquid hourly volume space velocity is 2.0-4.0 h -1 , the reaction temperature is 380~420℃.

8. The method according to claim 1, wherein: The dealkylation catalyst contains a modified ZSM-5 molecular sieve, a binder, and a noble metal. Based on the weight of the dealkylation catalyst, the modified ZSM-5 molecular sieve is 50 wt% to 90 wt%, and the noble metal content is 0.1 wt% to 2.0 wt% as a single substance.

9. The method according to claim 1, wherein: The amount of external acid in the pores of the dealkylation catalyst is 0.1 μmol / g to 2 μmol / g.

10. The method according to claim 1, wherein: The reaction pressure of the dealkylation reaction zone is 1.0-5.0 MPa, the hydrogen-to-oil volume ratio is 50:1-600:1, and the liquid hourly volume space velocity is 2.0-10.0 h -1 , the reaction temperature is 350~450℃.

11. The method according to claim 10, characterized in that: The dealkylation reaction zone has a reaction pressure of 2.0-4.0 MPa, a hydrogen-to-oil volume ratio of 200:1-400:1, and a liquid hourly space velocity of 3.0-6.0 h -1 , the reaction temperature is 380~420℃.

12. The method according to claim 1, wherein: The transalkylation catalyst contains a modified Beta molecular sieve, a binder and a noble metal, wherein the modified Beta molecular sieve is contained in an amount of 20 wt% to 60 wt% based on the weight of the modified Beta molecular sieve and the noble metal is contained in an amount of 0.1 wt% to 2.0 wt% based on the weight of the modified Beta molecular sieve.

13. The method according to claim 1, wherein: The amount of external acid in the pores of the transalkylation catalyst is 0.5 μmol / g to 5 μmol / g.

14. The method according to claim 1, wherein: The reaction pressure of the transalkylation reaction zone is 1.0-5.0 MPa, the hydrogen-to-oil volume ratio is 50:1-600:1, and the liquid hourly volume space velocity is 4.0-20.0 h -1 , the reaction temperature is 350~450℃.

15. The method according to claim 14, characterized in that: The reaction pressure in the transalkylation reaction zone is 2.0-4.0 MPa, the hydrogen-to-oil volume ratio is 200:1-400:1, and the liquid hourly volume space velocity is 8.0-12.0 h -1 , the reaction temperature is 380~420℃.

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