C9+ heavy aromatic lightening catalyst, preparation method and application thereof

Abstract

This invention discloses a C9+ heavy aromatic hydrocarbon lightening catalyst, its preparation method, and its application. The catalyst uses modified ZSM-5 molecular sieve and modified Beta molecular sieve as acid cracking components, and Group VIB and / or Group VIII metals as hydrogenation components. The ratio of acid content inside the micropores to acid content outside the micropores of the catalyst (A...) in / A out The ratio of micropore volume to mesopore volume (V) should be no less than 100, preferably 200-500. micro / V meso The concentration is 1.0~5.0, preferably 1.5~3.5. The method includes the modification process of the ZSM-5 molecular sieve and the Beta molecular sieve, and the kneading and molding process. The catalyst has both long-chain alkylbenzene dealkylation activity and toluene / trimethylbenzene alkyl transfer activity, realizing the lightening of heavy aromatics without the need for external toluene, and effectively avoiding side reactions such as trimethylbenzene disproportionation and aromatic condensation, delaying carbon deposition, and improving the operating cycle of the device.

Description

Technical Field

[0001] With the increasing scale of aromatics complexes in my country, the production of C9+ heavy aromatics will significantly increase. C9+ heavy aromatics are typically used as gasoline blending components, have low selling prices, and are subject to fuel taxes, severely impacting enterprise profitability. Furthermore, with restrictions on the aromatics content in automotive gasoline, the amount of C9+ reformed heavy aromatics that can be absorbed by gasoline pools will decrease. Meanwhile, BTX consumption is expected to continue growing over the next few decades, with high profit margins. This technology can utilize existing hydrocracking units to process reformed heavy aromatics into BTX, significantly improving refinery economic efficiency and effectively increasing BTX production, providing technical support for "oil-to-gas conversion."

[0002] C9+ heavy aromatics, as byproducts of catalytic reforming and steam cracking to ethylene production units, mainly include propylbenzene, ethylbenzene, trimethylbenzene, and a small amount of C10 aromatics. The main reactions occurring during the conversion of C9+ heavy aromatics include dealkylation, alkyl transfer of trimethylbenzene to xylene from light aromatics, disproportionation of trimethylbenzene to xylene while simultaneously generating tetramethylbenzene, isomerization, aromatic ring saturation and ring opening, and condensation carbon deposition. Among these, dealkylation and alkyl transfer are ideal reactions for the production of BTX from C9+ heavy aromatics, while the other reactions are non-ideal. Enhancing ideal reactions and reducing non-ideal reactions is key to maximizing the production of BTX from C9+ heavy aromatics.

[0003] Patent CN 99113580 uses nickel and bismuth modified Beta zeolite as a catalyst, and a mixture of toluene, C9 aromatics and C10 aromatics as raw materials, wherein the C10+ aromatics content is 5%, the total conversion rate is 47%, and the selectivity of benzene and xylene is 88%.

[0004] CN201310512218.0 discloses a catalyst for the lightening of heavy aromatics, which comprises, by weight percentage, 30-60% of a mixture of MFI type zeolite and ZSM-12 molecular sieve, 38.5-69.8% of at least one selected from γ-alumina, η-alumina or boehmite as a binder, 0.1-0.5% of at least one metal selected from Pt, Pd or Ir and 0.1-1% of at least one metal selected from Zn, La, Ce or Bi.

[0005] The catalysts disclosed in the prior art for the lightening of heavy aromatics have problems such as the need for external toluene, toluene disproportionation, and numerous side reactions such as aromatic condensation. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a C9+ heavy aromatic hydrocarbon lightening catalyst, its preparation method, and its application. This catalyst simultaneously possesses long-chain alkylbenzene dealkylation activity and toluene / trimethylbenzene alkyl transfer activity, achieving the lightening of heavy aromatic hydrocarbons without the need for external toluene addition. Furthermore, it effectively avoids side reactions such as trimethylbenzene disproportionation and aromatic hydrocarbon condensation, delays carbon deposition, and improves the operating cycle of the equipment.

[0007] A C9+ heavy aromatic hydrocarbon lightening catalyst, wherein the catalyst uses modified ZSM-5 molecular sieve and modified Beta molecular sieve as acid cracking components, and Group VIB and / or Group VIII metals as hydrogenation components. Based on the weight of the catalyst, the content of the modified ZSM-5 molecular sieve is 20%~50%, preferably 20%~30%; the content of the modified Beta molecular sieve is 30%~70%, preferably 50%~60%; the content of the hydrogenation component, calculated as oxides, is 3%~15%, preferably 5%~12%. The ratio of acid content inside the micropores to acid content outside the micropores (A) is... in / A out The ratio of micropore volume to mesopore volume (V) should be no less than 100, preferably 200-500. micro / V meso The value is 1.0~5.0, preferably 1.5~3.5.

[0008] In the catalyst of this invention, the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel. Based on the weight of the catalyst, the content of the Group VIB metal as oxide is 5wt% to 20wt%, and the content of the Group VIII metal as oxide is 2wt% to 5wt%.

[0009] A method for preparing a C9+ heavy aromatic hydrocarbon lightening catalyst, the method comprising a modification process of the ZSM-5 molecular sieve and a Beta molecular sieve, and a mixing and molding process; wherein the modification process includes the following steps:

[0010] (1) Treat ZSM-5 molecular sieve or Beta molecular sieve raw powder with inorganic acid;

[0011] (2) Impregnate the material obtained in step (1) with a channel protection liquid;

[0012] (3) The material obtained in step (2) is treated with a sterically hindered organic acid;

[0013] (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent to perform dealuminizing and silicon replenishment;

[0014] (5) The material obtained in step (4) is filtered, washed, dried and calcined to obtain modified ZSM-5 molecular sieve or modified Beta molecular sieve.

[0015] Further, in step (1), the ZSM-5 molecular sieve can be a commercially available product or a microporous hydrogen-type ZSM-5 molecular sieve prepared according to existing technology. The properties of the ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio 30~100.

[0016] Furthermore, in step (1), the Beta molecular sieve can be a commercially available product or a microporous hydrogen-type Beta molecular sieve prepared according to existing technology. The properties of the Beta molecular sieve are as follows: SiO2 / Al2O3 molar ratio 20~40.

[0017] Furthermore, in step (1), the acid treatment process can use one or more strong acidic substances such as hydrochloric acid and nitric acid. The specific treatment process is as follows: the molecular sieve obtained in step (1) is mixed with the acid solution and stirred. The treatment temperature is 40~80℃ and the treatment time is 0.5~3h. Then, solid-liquid separation is performed (e.g., vacuum filtration). The above operation is repeated 2~4 times.

[0018] Further, 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.

[0019] Furthermore, in step (2), the impregnation is preferably an equal-volume impregnation. The impregnation treatment temperature is room temperature, generally 20~25℃.

[0020] Further, in step (3), the sterically hindered organic acid is one or more of 2,4-dimethylbenzenesulfonic acid and 2,5-dimethylbenzoic acid.

[0021] Further, in step (3), the specific operation is as follows: first, the material obtained in step (2) is mixed with water, wherein the liquid-solid volume ratio of water to the material obtained in step (2) is 2:1 to 6:1, and then organic acid is added until the pH value of the solution drops below 8, preferably 6.5 to 7.5.

[0022] Further, in step (4), the dealuminizing and silicon-replenishing reagent is at least one of ammonium hexafluorosilicate solution, tetraethyl orthosilicate solution, etc. The molar concentration of the dealuminizing and silicon-replenishing reagent is 0.3~1.0 mol / L. The mass ratio of the material obtained in step (4) to the dealuminizing and silicon-replenishing reagent is 1:1~1:5. The mixing temperature is 60~100℃.

[0023] Further, the specific operation process of step (4) is as follows: rapidly heat the material obtained in step (3) to 60~100℃ and continuously stir, add the aluminum removal and silicon replenishment reagent dropwise, and continue stirring for 60~120min after the dropwise addition is completed. Among them, the dropwise addition rate does not exceed 0.5mL / min·g of the material obtained in step (3); preferably 0.2~0.4mL / min·g of the material obtained in step (3).

[0024] Furthermore, in step (5), the filtration and washing can be carried out using conventional methods in the art, the drying temperature is 100℃~150℃, the drying time is 2~4h, the calcination temperature is 400℃~600℃, and the calcination time is 3~5h.

[0025] In the method of this invention, the kneading and molding process involves kneading, extruding, and molding modified ZSM-5 molecular sieve, modified Beta molecular sieve, hydrogenated metal, and binder, followed by drying and calcination to obtain a C9+ heavy aromatic hydrocarbon lightening catalyst.

[0026] The application of C9+ heavy aromatic hydrocarbon lightening catalyst, wherein the C9+ heavy aromatic hydrocarbon is reformed heavy aromatic hydrocarbon, wherein the mass content of the reformed heavy aromatic hydrocarbon is 30%~50% by mass, the mass content of propylbenzene is 3%~10% by mass, the mass content of methyl ethylbenzene is 20%~30% by mass, and the mass content of C10+ aromatic hydrocarbon is 10%~20% by mass.

[0027] Compared with existing technologies, the C9+ heavy aromatic hydrocarbon lightening catalyst, its preparation method, and its application of the present invention have the following advantages:

[0028] (1) The modified ZSM-5 molecular sieve and Beta molecular sieve used in the hydrocracking catalysis of this invention serve as cracking centers. The modified ZSM-5 molecular sieve exhibits higher dealkylation activity for long side chains of heavy aromatic hydrocarbons such as ethylbenzene, diethylbenzene, propylbenzene, and butylbenzene. The Beta molecular sieve has higher disproportionation and alkyl transfer activity. Polymethylbenzene in the feedstock undergoes alkyl transfer reaction within the Beta molecular sieve to obtain xylene. The two molecular sieves synergistically catalyze the lightening of all components of the reformed heavy aromatic hydrocarbons to obtain chemical feedstocks such as BTX.

[0029] (2) After the ZSM-5 molecular sieve and Beta molecular sieve are subjected to pore-expanding treatment, the accessibility of their acid sites is greatly improved, the activity is further improved, and the product molecules can diffuse out of the pores as soon as possible, thus avoiding excessive reaction and generation of chain hydrocarbons.

[0030] (3) The selective masking of the acidity outside the two molecular sieve channels makes the reactions involving small molecules that can enter the molecular sieve channels, such as toluene disproportionation and toluene / trimethylbenzene alkyl transfer, dominant. This reduces the polymethylbenzene disproportionation and condensation that are easy to occur on the outer surface. The introduction of a small amount of hydrogenated metal avoids the loss of aromatics and simultaneously completes the dealkylation reaction to obtain olefin products, thereby reducing carbon deposition and improving the service life of the catalyst. Implementation

[0031] The following examples and comparative examples further illustrate the role and effect of the technical solution of the present invention, but the following examples do not constitute a limitation on the scope of protection of the present invention.

[0032] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0033] In this invention, the total acid content is determined as follows: The powdered catalyst is compressed into tablets, evacuated, and then degassed at 450°C for 2 hours. After the temperature drops to room temperature, a pyridine molecule with a kinetic diameter of 5 Å is used as a probe molecule to measure the infrared spectrum of chemical desorption, and the adsorption amount is calculated. Since the diameter of the pyridine molecule is smaller than that of the molecular sieve pores, this method can obtain its total acid content A. total .

[0034] In this invention, the method for measuring the external micropore content is as follows: The powdered catalyst is compressed into tablets, evacuated, and then degassed at 450°C for 2 hours. After the temperature drops to room temperature, 2,6-di-tert-butylpyridine molecules are used as probe molecules to measure the infrared spectrum of its chemical desorption, and the adsorption amount is calculated. Since the diameter of the 2,6-di-tert-butylpyridine molecule is larger than that of the molecular sieve pores, this method can obtain the external acid content A of the micropores. out .

[0035] The difference between the total acid content obtained from pyridine infrared spectroscopy and the acid content within the microporous channels obtained from 2,6-di-tert-butylpyridine infrared spectroscopy is A. in。

[0036] In this invention, the micropore and mesopore volumes are determined using the following method: an ASAP 2420 cryogenic liquid nitrogen physical adsorption instrument manufactured by Micrometics, Inc. (USA). Before measurement, the sample is first calcined at 550°C for 4 hours to remove the template agent. During testing, the sample is pretreated at 300°C for 3 hours, and then nitrogen is adsorbed at 77K for testing.

[0037] Example 1

[0038] Take 300g of commercially available hydrogen-type Beta molecular sieve raw powder, add it to 1800mL of 0.1mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 8.0. The mixture was stirred and heated to 60 °C. 300 mL of 0.3 mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2 mL / min·g using a peristaltic pump. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Beta-1.

[0039] Take 300g of commercially available hydrogen-type ZSM-5 molecular sieve raw powder, add it to 1800mL of 0.1mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 8.0. The mixture was stirred and heated to 60 °C. 300 mL of 0.3 mol / L ammonium hexafluorosilicate solution was added dropwise using a peristaltic pump at a rate of 0.2 mL / min·g. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Z-1.

[0040] Z-1, Beta-1, alumina sol binder, tungsten oxide, and nickel nitrate were mixed evenly by rolling in a certain proportion, and then extruded, dried, and calcined to obtain the alkyl transfer catalyst CAT-1. Its properties are as follows: Z-1 content 20 wt%, Beta-1 content 10 wt%, NiO content 2.0 wt%, WO3 content 5.0 wt%; the ratio of acid content inside the micropores to acid content outside the micropores (A... in / A out The ratio of micropore volume to mesopore volume (V) is 134. micro / V meso The value is 4.9.

[0041] Example 2

[0042] Take 300g of commercially available hydrogen-type Beta molecular sieve raw powder, add it to 1800mL of 0.6mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 5.0. The mixture was stirred and heated to 60 °C. 300 mL of 1.0 mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2 mL / min·g using a peristaltic pump. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Beta-2.

[0043] Take 300g of commercially available hydrogen-type ZSM-5 molecular sieve raw powder, add it to 1800mL of 0.6mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the obtained filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 5.0. The mixture was stirred and heated to 60 °C. 300 mL of 1.0 mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2 mL / min·g using a peristaltic pump. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Z-2.

[0044] Z-2, Beta-2, alumina sol binder, tungsten oxide, and nickel nitrate were mixed evenly by rolling in a certain proportion, and then extruded, dried, and calcined to obtain the alkyl transfer catalyst CAT-2. Its properties are as follows: Z-2 content 20wt%, Beta-2 content 30wt%, NiO content 4.0wt%, WO3 content 10.0wt%; the ratio of acid content inside the micropores to acid content outside the micropores (A... in / A out The ratio of micropore volume to mesopore volume is 158 (V).micro / V meso The value is 1.0.

[0045] Example 3

[0046] Take 300g of commercially available hydrogen-type Beta molecular sieve raw powder, add it to 1800mL of 0.3mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 6.5. The mixture was stirred and heated to 60 °C. 300 mL of 0.6 mol / L ammonium hexafluorosilicate solution was added dropwise using a peristaltic pump at a rate of 0.2 mL / min·g. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Beta-3.

[0047] Take 300g of commercially available hydrogen-type ZSM-5 molecular sieve raw powder, add it to 1800mL of 0.3mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the obtained filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 6.5. The mixture was stirred and heated to 60 °C. 300 mL of 0.6 mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2 mL / min·g using a peristaltic pump. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Z-3.

[0048] Z-3, Beta-3, alumina sol binder, tungsten oxide, and nickel nitrate were mixed evenly by rolling in a certain proportion, and then extruded, dried, and calcined to obtain the alkyl transfer catalyst CAT-3. Its properties are as follows: Z-2 content 30wt%, Beta-2 content 45wt%, NiO content 3.0wt%, WO3 content 6.0wt%; the ratio of acid content inside the micropores to acid content outside the micropores (A...in / A out The ratio of micropore volume to mesopore volume (V) is 298. micro / V meso The value is 2.1.

[0049] Example 4

[0050] Take 300g of commercially available hydrogen-type Beta molecular sieve raw powder, add it to 1800mL of 0.4mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 7.0. The mixture was stirred and heated to 60 °C. 300 mL of 0.6 mol / L ammonium hexafluorosilicate solution was added dropwise using a peristaltic pump at a rate of 0.2 mL / min·g. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was filtered while hot, and 2400 mL of water was added to the filter cake. The mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Beta-4.

[0051] Take 300g of commercially available hydrogen-type ZSM-5 molecular sieve powder, add it to 1800mL of 0.4mol / L hydrochloric acid solution, stir and heat to 60℃ and maintain for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and maintain for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 7.0. The mixture was stirred and heated to 60 °C. 300 mL of 0.6 mol / L ammonium hexafluorosilicate solution was added dropwise using a peristaltic pump at a rate of 0.2 mL / min·g. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Z-4.

[0052] Z-4, Beta-4, alumina sol binder, tungsten oxide, and nickel nitrate were mixed evenly by rolling in a certain proportion, and then extruded, dried, and calcined to obtain the alkyl transfer catalyst CAT-4. Its properties are as follows: Z-2 content 40wt%, Beta-2 content 45wt%, NiO content 3.0wt%, WO3 content 8.0wt%; the ratio of acid content inside the micropores to acid content outside the micropores (A... in / A out The ratio of micropore volume to mesopore volume (V) is 232. micro / V meso The value is 3.1.

[0053] Example 5

[0054] Take 300g of commercially available hydrogen-type Beta molecular sieve raw powder, add it to 1800mL of 0.2mol / L hydrochloric acid solution, stir and heat to 60℃ and keep for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and keep for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 7.0. The mixture was stirred and heated to 60 °C. 300 mL of 0.4 mol / L ammonium hexafluorosilicate solution was added dropwise using a peristaltic pump at a rate of 0.2 mL / min·g. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was filtered while hot, and 2400 mL of water was added to the filter cake. The mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Beta-5.

[0055] Take 300g of commercially available hydrogen-type ZSM-5 molecular sieve powder, add it to 1800mL of 0.2mol / L hydrochloric acid solution, stir and heat to 60℃ and maintain for 1h, filter while hot, add 2400mL of water to the filter cake, heat to 60℃ and maintain for 20min, filter while hot, and dry the filter cake at 120℃ for 24h. The obtained material was impregnated with an equal volume of 2.0 mol / L tetraethylammonium hydroxide solution and allowed to stand for 10 min. 1700 mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH reached 7.0. The mixture was stirred and heated to 60 °C. 300 mL of 0.4 mol / L ammonium hexafluorosilicate solution was added dropwise using a peristaltic pump at a rate of 0.2 mL / min·g. The temperature was maintained at 60 °C with continuous stirring for 90 min. The mixture was then filtered while hot. 2400 mL of water was added to the filter cake, and the mixture was heated to 60 °C and maintained for 20 min. The mixture was then filtered while hot, and the filter cake was dried at 120 °C for 24 h. The dried product was then calcined at 550 °C for 3 h. The resulting modified molecular sieve was named Z-5.

[0056] Z-5, Beta-5, alumina sol binder, tungsten oxide, and nickel nitrate were mixed evenly by rolling in a certain proportion, and then extruded, dried, and calcined to obtain the alkyl transfer catalyst CAT-5. Its properties are as follows: Z-2 content 30wt%, Beta-2 content 55wt%, NiO content 5.0wt%, WO3 content 12.0wt%, and the ratio of acid content inside the micropores to acid content outside the micropores (A... in / A out The ratio of micropore volume to mesopore volume (V) is 215. micro / V meso The value is 3.3.

[0057] Comparative Example 1

[0058] The alkyl transfer catalyst CAT-B1 was obtained by uniformly mixing hydrogen-form ZSM-5 raw powder, hydrogen-form Beta raw powder, alumina sol binder, tungsten oxide, and nickel nitrate in a certain proportion after rolling and pressing, followed by extrusion, drying, and calcination. Its properties are as follows: ZSM-5 molecular sieve content 20 wt%, Beta molecular sieve content 10 wt%, NiO content 2.0 wt%, WO3 content 5.0 wt%; the ratio of acid content inside to outside the micropores (Ain / Aout) is 32, and the ratio of micropore volume to mesopore volume (Vmicro / Vmeso) is 8.9.

[0059] Example 6

[0060] 10g of catalyst CAT-1 was placed in a fixed-bed reactor. The reaction was carried out at a pressure of 5.0 MPa, a hydrogen-to-oil volume ratio of 100:1, and a liquid hourly space velocity of 2.0 h⁻¹. -1The heavy aromatic hydrocarbon lightening reaction was carried out at a reaction temperature of 420℃ for 160h. The conversion rates of each component, BTX yield and catalyst carbon deposition are shown in Table 1.

[0061] Example 7

[0062] 10g of catalyst CAT-2 was placed in a fixed-bed reactor. The reaction was carried out at a pressure of 5.0 MPa, a hydrogen-to-oil volume ratio of 100:1, and a liquid hourly space velocity of 2.0 h⁻¹. -1 The heavy aromatic hydrocarbon lightening reaction was carried out at a reaction temperature of 420℃ for 160h. The conversion rates of each component, BTX yield and catalyst carbon deposition are shown in Table 1.

[0063] Example 8

[0064] 10g of catalyst CAT-3 was placed in a fixed-bed reactor. The reaction was carried out at a pressure of 5.0 MPa, a hydrogen-to-oil volume ratio of 100:1, and a liquid hourly space velocity of 2.0 h⁻¹. -1 The heavy aromatic hydrocarbon lightening reaction was carried out at a reaction temperature of 420℃ for 160h. The conversion rates of each component, BTX yield and catalyst carbon deposition are shown in Table 1.

[0065] Comparative Example 2

[0066] 10g of catalyst CAT-B1 was placed in a fixed-bed reactor. The reaction was carried out at a pressure of 5.0 MPa, a hydrogen-to-oil volume ratio of 100:1, and a liquid hourly space velocity of 2.0 h⁻¹. -1 The heavy aromatic hydrocarbon lightening reaction was carried out at a reaction temperature of 420℃ for 160h. The conversion rates of each component, BTX yield and catalyst carbon deposition are shown in Table 1.

[0067] Table 1 Evaluation results of the examples and comparative examples

[0068]

Claims

1. A catalyst for the lightening of C9+ heavy aromatics, characterized in that: The catalyst uses modified ZSM-5 molecular sieve and modified Beta molecular sieve as acid cracking components, and Group VIB and / or Group VIII metals as hydrogenation components. Based on the weight of the catalyst, the content of the modified ZSM-5 molecular sieve is 20%–50%; the content of the modified Beta molecular sieve is 30%–70%; the content of the hydrogenation components (calculated as oxides) is 3%–15%; and the ratio A of the acid content inside the micropores to the acid content outside the micropores is... in / A out The ratio of micropore volume to mesopore volume V is not less than 100. micro / V meso The value ranges from 1.0 to 5.

0. The preparation method of the C9+ heavy aromatic hydrocarbon lightening catalyst includes the modification process of the ZSM-5 molecular sieve and the Beta molecular sieve, and the kneading and molding process. The modification process includes the following steps: (1) Treat ZSM-5 molecular sieve or Beta molecular sieve raw powder with inorganic acid; (2) Impregnate the material obtained in step (1) with a channel protection liquid; (3) The material obtained in step (2) is treated with a sterically hindered organic acid; (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent to perform dealuminizing and silicon replenishment; (5) The material obtained in step (4) is filtered, washed, dried and calcined to obtain modified ZSM-5 molecular sieve or modified Beta molecular sieve; In step (2), the pore protection solution is one or more of isopropylamine solution, tetraethylammonium hydroxide solution, and tetrapropylammonium hydroxide solution; The total acidity obtained from pyridine infrared spectroscopy and the acidity outside the micropores obtained from 2,6-di-tert-butylpyridine infrared spectroscopy (A) out The difference is A in .

2. The catalyst according to claim 1, characterized in that: Based on the weight of the catalyst, the content of the modified ZSM-5 molecular sieve is 20%–30%; the content of the modified Beta molecular sieve is 50%–60%; the content of the hydrogenation component, calculated as oxides, is 5%–12%; and the ratio A of the acid content inside the micropores of the catalyst to the acid content outside the micropores is... in / A out 200–500, the ratio of micropore volume to mesopore volume V micro / V meso It ranges from 1.5 to 3.

5.

3. The catalyst according to claim 1, characterized in that: The group VIB metal is molybdenum and / or tungsten, and the group VIII metal is cobalt and / or nickel. Based on the weight of the catalyst, the content of group VIB metal as oxide is 5 wt% to 15 wt%, and the content of group VIII metal as oxide is 3 wt% to 5 wt%.

4. A method for preparing the C9+ heavy aromatic hydrocarbon lightening catalyst according to any one of claims 1 to 3, characterized in that: The method includes a modification process of ZSM-5 molecular sieve and Beta molecular sieve, and a kneading molding process; The modification process includes the following steps: (1) Treat ZSM-5 molecular sieve or Beta molecular sieve raw powder with inorganic acid; (2) Impregnate the material obtained in step (1) with a channel protection liquid; (3) The material obtained in step (2) is treated with a sterically hindered organic acid; (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent to perform dealuminizing and silicon replenishment; (5) The material obtained in step (4) is filtered, washed, dried and calcined to obtain modified ZSM-5 molecular sieve or modified Beta molecular sieve; In step (2), the pore protection liquid is one or more of isopropylamine solution, tetraethylammonium hydroxide solution, and tetrapropylammonium hydroxide solution.

5. The method according to claim 4, characterized in that: The properties of the ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio 30-100, and the properties of the Beta molecular sieve are as follows: SiO2 / Al2O3 molar ratio 20-40.

6. The method according to claim 4, characterized in that... In step (1), the specific process of inorganic acid treatment is as follows: the ZSM-5 molecular sieve or Beta molecular sieve obtained in step (1) is mixed with inorganic acid solution and stirred, the treatment temperature is 40-80℃, the treatment time is 0.5-3h, and then solid-liquid separation is performed.

7. The method according to claim 4, characterized in that: The sterically hindered organic acid is 2,4-dimethylbenzenesulfonic acid and / or 2,5-dimethylbenzoic acid.

8. The method according to claim 4, characterized in that: In step (3), the specific operation is as follows: first, mix the material obtained in step (2) with water, wherein the liquid-solid volume ratio of water to the material obtained in step (2) is 2:1 to 6:1, and then add a sterically hindered organic acid until the pH value of the solution drops below 8.

9. The method according to claim 4, characterized in that: In step (3), a sterically hindered organic acid is added until the pH of the solution drops to 6.5-7.

5.

10. The method according to claim 4, characterized in that: In step (4), the dealuminizing and silicon replenishing reagent is at least one of ammonium hexafluorosilicate solution and tetraethyl orthosilicate solution.

11. The method according to claim 4, characterized in that: The specific operation process of step (4) is as follows: rapidly heat the material obtained in step (3) to 60-100℃ and continue stirring, add aluminum removal and silicon replenishment reagent dropwise, and continue stirring for 60-120 minutes after the dropwise addition is completed.

12. The method according to claim 4, characterized in that: The drying temperature in step (5) is 100℃~150℃ and the drying time is 2~4h; the calcination temperature is 400℃~600℃ and the calcination time is 3~5h.

13. The method according to claim 4, characterized in that: The kneading and molding process involves kneading, extruding, and molding modified ZSM-5 molecular sieve, modified Beta molecular sieve, hydrogenation components, and binders, followed by drying and calcination to obtain a C9+ heavy aromatic hydrocarbon lightening catalyst.

14. The application of the C9+ heavy aromatic hydrocarbon lightening catalyst according to any one of claims 1 to 3, wherein the C9+ heavy aromatic hydrocarbon is a C9+ reformed heavy aromatic hydrocarbon.

15. In the application according to claim 14, the C9+ reformed heavy aromatic hydrocarbon contains 30% to 50% by mass of methylbenzene, 3% to 10% by mass of propylbenzene, 20% to 30% by mass of ethylbenzene, and 10% to 20% by mass of C10+ aromatic hydrocarbon.

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