Composite catalyst bed and use thereof

Abstract

The present application discloses a composite catalyst bed and its application, especially in the production of light C6-C8 aromatic hydrocarbons from heavy aromatic hydrocarbons. The composite catalyst bed comprises multiple layers of catalyst-loaded beds, each of the catalysts independently comprising a silico-alumina molecular sieve, a metal component and optionally a binder, and the pore structure of the silico-alumina molecular sieve in each bed catalyst gradually decreases in the order of contacting the material. The composite catalyst bed of the present application can be used for the lightening of heavy aromatic hydrocarbons, and especially for the production of C9 + Aromatic hydrocarbon lightening, wherein the use of different pore size molecular sieves to match different raw material molecular conversion reactions can effectively utilize naphthalene and / or its derivatives in heavy aromatic hydrocarbons, improve the utilization rate of heavy aromatic hydrocarbon resources, and significantly improve the conversion rate of heavy aromatic hydrocarbon lightening reaction and the selectivity of the target product BTX.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, and particularly relates to a composite catalyst bed and its application, especially in the production of light C6-C8 aromatics from heavy aromatics. Background Technology

[0002] Heavy aromatics are byproducts of petroleum processing. They are commonly referred to as C9A and C10 aromatics. 10 A) with C11 and above heavy aromatics (C 11 + A) Collectively referred to as heavy aromatics. Petroleum heavy aromatics mainly originate as byproducts from catalytic cracking, catalytic reforming, and naphtha steam cracking units in refineries. The structure and composition of heavy aromatics are very complex, containing not only a significant amount of methyl, ethyl, and propyl groups, but also a large number of polycyclic aromatic hydrocarbons. With the development of heavy crude oil production, the resources of byproduct heavy aromatics will increase.

[0003] An aromatics complex is a chemical plant that produces BTX (benzene, toluene, and xylene) light aromatics through processes such as catalytic reforming, aromatics extraction, disproportionation / alkyl transfer, isomerization, and adsorption separation. The heavy aromatics byproducts of the catalytic reforming unit mainly contain monocyclic aromatics, and also contain approximately 3-5% polycyclic aromatics. Most of the reformed heavy aromatics can be converted to xylene through heavy aromatics lightening or disproportionation and alkyl transfer units. For example, UOP's TAC9 is suitable for processing pure C9A / C... 10 Aromatic hydrocarbons, and TA series alkyl transfer catalysts are suitable for processing feedstocks containing a certain amount of monocyclic heavy aromatic hydrocarbons. However, these catalysts have certain limitations on the content of polycyclic aromatic hydrocarbons in the feedstock, requiring the separation and removal of naphthalene derivatives from the reformed heavy aromatic hydrocarbons before use. This process suffers from high energy consumption in heavy aromatic hydrocarbon separation and low utilization rate of heavy aromatic hydrocarbon resources. Further reducing energy and material consumption and improving the utilization rate of low-quality heavy aromatic hydrocarbon feedstocks are the future development trends of aromatic hydrocarbon plants. However, the higher the content of C10 and above heavy aromatic hydrocarbons in the reaction feedstock, especially the higher the content of naphthalene derivatives, the lower the catalyst activity and the more prone it is to coking and deactivation. Therefore, traditional alkyl transfer processes have strict limitations on the naphthalene derivative content in the reaction feedstock. Currently, the disproportionation and alkyl transfer units for C9... + The utilization of heavy aromatics mainly focuses on C9A and some C14A hydrocarbons. 10 The utilization of A, while naphthalene compounds and C 11 + Naphthalene compounds, due to their ineffective utilization, are discharged from the bottom of heavy aromatics towers and are generally used for blending diesel and fuel. In recent years, the light utilization of naphthalene compounds has been gradually developed by researchers. This requires the action of a bifunctional catalyst combining metal and acid, and involves the production of light aromatics through partial ring-opening hydrogenation and hydrocracking processes. Precious metals such as platinum and palladium have been reported as selectively ring-opening metal compounds.

[0004] WO2019177961A1 (2019-3-11) Saudi Aramco discloses a method for preparing BTX compounds of benzene, toluene, and xylene. The process feeds reformate into a reactor containing a composite zeolite catalyst. The composite zeolite catalyst comprises a mixture of nano-beta and ZSM-5. The nano-beta, ZSM-5, or both comprise one or more impregnated metals, with a Re content of 0.25 to 0.55 wt.%. A key feature of this patent is the limitation on the nano-beta particle size, which is between 10-40 nm, with an external specific surface area greater than 150 m² / g and a silica-alumina ratio between 6-12. Combined with the hydrogenation effect of the metal, this molecular sieve can be used simultaneously in alkyl transfer and dealkylation processes. The presence of the nano-beta molecular sieve increases the external specific surface area of ​​the catalyst, effectively improving the conversion rate of heavy aromatic alkyl transfer and dealkylation performance. This catalyst can process high C9+A feedstocks and improves the yield of mixed xylenes and catalyst stability. ExxonMobil Chemicals patent company US20200031740A1 discloses a novel process for converting C9 and larger heavy aromatics into benzene, toluene, and xylene. This patent utilizes two catalysts, one containing zeolite, the other a first metal and / or a second metal, and a binder, as the first catalyst and the second catalyst, respectively, to effectively increase the yields of benzene, toluene, and xylene. The process primarily combines dealkylation and alkyl transfer processes, using a sulfidated bifunctional catalyst to lighten C9 and larger heavy aromatics under hydrogen-exposed conditions. In this process, C9 and larger heavy aromatics are first converted into benzene, toluene, and xylene, as well as lower-carbon alkanes (C2) through dealkylation. + The remaining C9 and higher aromatic hydrocarbons further react with the generated benzene and toluene through alkyl transfer to produce xylene. Unlike previous processes, this method utilizes different catalyst beds or a physical mixture of two catalysts to catalyze the C9... + Aromatic hydrocarbons are lightly converted into benzene, toluene, and xylene. The above reaction system mainly involves multiple reactors connected in series, increasing equipment investment and process complexity. Summary of the Invention

[0005] To overcome the problems existing in the prior art, the present invention provides a composite catalyst bed, its preparation method and application. The composite catalyst bed utilizes molecular sieves of different pore sizes to match the conversion reactions of different raw material molecules, which can effectively utilize naphthalene compounds in heavy aromatics and improve the utilization rate of heavy aromatic resources.

[0006] One aspect of the present invention is to provide a composite catalyst bed comprising multiple layers of catalyst-filled beds, each catalyst independently comprising a silica-alumina molecular sieve, a metal component, and an optional binder, wherein the pore structure of the silica-alumina molecular sieve in each catalyst bed gradually decreases according to the order of contact with the material.

[0007] The binder is selected from at least one of alumina, alumina sol, boehmite, and silica sol. Preferably, in the catalyst of each bed, based on the total weight of the alumina-silica molecular sieve and the binder of 100 wt%, the alumina-silica molecular sieve is 10-85 wt% and the binder is 5-80 wt% respectively.

[0008] Each of the metal components is independently selected from at least one element in Group IB, Group IIB, Group VIB, Group VIII and Group VIIB, preferably from at least one of Ni, Mo, Re, Pd, Co, Rh, Ru, Ir, Cr, Pt and Zn, and more preferably, the loading of each metal component in each catalyst bed is independently 0.01 to 25 wt%.

[0009] According to the order of contact with the material, the number of framework T atoms of the largest ring structure on the silica-alumina molecular sieve in each bed catalyst gradually decreases (preferably in the range of 20 to 6, more preferably in the range of 18 to 9);

[0010] More preferably, the silica-alumina molecular sieve is selected from at least one of AET molecular sieve, ETR molecular sieve, ZEO-1 molecular sieve, UTD-1F molecular sieve, β-zeolite molecular sieve, mordenite molecular sieve, ZSM-12 molecular sieve, Y molecular sieve, MCM-22 molecular sieve, ITQ-1 molecular sieve, ITQ-24 molecular sieve, ITQ-32 molecular sieve, AFR molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-5 molecular sieve, EU-1 molecular sieve, ITQ-13 molecular sieve, NU-87 molecular sieve, ZSM-34 molecular sieve, and ZSM-11 molecular sieve.

[0011] The aluminum content and / or acid content of the silica-alumina molecular sieve in each catalyst bed gradually increase according to the order of contact with the material; preferably, the aluminum content and / or acid content of the silica-alumina molecular sieve in each catalyst bed is between 10 and 500 μmol / dg according to the order of contact with the material. -1 (Preferred 20–450 μmol pydg) -1 It gradually increases within the range.

[0012] The composite catalyst bed comprises three or more layers filled with catalyst, preferably 3 to 10 layers, more preferably 3 to 6 layers.

[0013] The composite catalyst bed comprises three layers. According to the order of contact with the material, the catalyst in the first layer has a framework T atom number of 14 to 18 for the largest ring structure of the silica-alumina molecular sieve; and / or, the catalyst in the second layer has a framework T atom number of 11 to 12 for the largest ring structure of the silica-alumina molecular sieve; and / or, the catalyst in the third layer has a framework T atom number of 9 to 10 for the largest ring structure of the silica-alumina molecular sieve.

[0014] The composite catalyst bed comprises three layers. According to the order of contact with the material, the first layer of the catalyst contains silica and alumina molecules selected from at least one of AET molecular sieve, ETR molecular sieve, ZEO-1 molecular sieve, and UTD-1F molecular sieve; and / or, the second layer of the catalyst contains silica and alumina molecules selected from at least one of β-zeolite molecular sieve, mordenite molecular sieve, ZSM-12 molecular sieve, Y molecular sieve, MCM-22 molecular sieve, ITQ-1 molecular sieve, ITQ-24 molecular sieve, ITQ-32 molecular sieve, and AFR molecular sieve; and / or, the third layer of the catalyst contains silica and alumina molecules selected from at least one of ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-5 molecular sieve, EU-1 molecular sieve, ITQ-13 molecular sieve, NU-87 molecular sieve, ZSM-34 molecular sieve, and ZSM-11 molecular sieve.

[0015] The composite catalyst bed comprises three layers. In order of contact with the material, the first layer of catalyst contains 20–200 μmol pydg of silica-alumina molecular sieve acid. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the second bed is 200–300 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the third bed is 320–450 μmol pydg. -1 .

[0016] A second aspect of the present invention is to provide the application of the composite catalyst bed, preferably in the lightening of heavy aromatics.

[0017] A third aspect of the present invention is to provide a method for lightening heavy aromatics, comprising: reacting a heavy aromatic feedstock with the composite catalyst bed under hydrogen-containing conditions.

[0018] The heavy aromatic feedstock is a C9 hydrocarbon containing naphthalene and / or its derivatives. + Aromatic hydrocarbon, preferably, wherein the content of naphthalene and / or its derivatives is 0.1 to 100 wt%.

[0019] The contact reaction temperature is 200℃~600℃; and / or, the contact reaction pressure is 2~10.0 MPa; and / or, the hydrogen-to-hydrocarbon molecular ratio is 1~20; and / or, the weight hourly space velocity of the heavy aromatic feedstock is 1~7 h⁻¹. -1 .

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The composite catalyst bed described in this invention can be used for the lightening of heavy aromatics, especially for C9 hydrocarbons containing naphthalene and / or its derivatives.+ Aromatic hydrocarbon lightening involves using molecular sieves of different pore sizes to match the conversion reactions of different raw material molecules. This effectively utilizes naphthalene and / or its derivatives in heavy aromatic hydrocarbons, improving the utilization rate of heavy aromatic hydrocarbon resources. It can significantly improve the conversion rate of heavy aromatic hydrocarbon lightening reaction and the selectivity of the target product BTX. Specifically, it has high total conversion rate, high conversion rate of naphthalene and / or its derivatives, and high BTX selectivity. Detailed Implementation

[0022] One objective of this invention is to provide a composite catalyst bed comprising multiple layers of catalyst-filled beds, each catalyst independently comprising a silica-alumina molecular sieve, a metal component, and an optional binder, wherein the pore structure of the silica-alumina molecular sieve in each catalyst bed gradually decreases according to the order of contact with the material.

[0023] In a preferred embodiment, the number of framework T atoms of the largest ring structure on the silica-alumina molecular sieve in each bed catalyst gradually decreases according to the order of contact with the material. (Preferably in the range of 20 to 6, more preferably in the range of 18 to 9).

[0024] The pore sizes of the silica-alumina molecular sieves vary between different bed layers. The "number of T atoms in the framework of the largest ring structure" refers to the total number of silicon and aluminum atoms in the framework of the largest ring structure.

[0025] In a further preferred embodiment, the silica-alumina molecular sieve is selected from at least one of AET molecular sieve, ETR molecular sieve, ZEO-1 molecular sieve, UTD-1F molecular sieve, β-zeolite molecular sieve, mordenite molecular sieve, ZSM-12 molecular sieve, Y molecular sieve, MCM-22 molecular sieve, ITQ-1 molecular sieve, ITQ-24 molecular sieve, ITQ-32 molecular sieve, AFR molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-5 molecular sieve, EU-1 molecular sieve, ITQ-13 molecular sieve, NU-87 molecular sieve, ZSM-34 molecular sieve, and ZSM-11 molecular sieve.

[0026] In a further preferred embodiment, the silica-alumina molecular sieve is selected from at least one of AET molecular sieve, β-zeolite molecular sieve, mordenite molecular sieve, ZSM-5 molecular sieve, ZSM-11 molecular sieve, and ZSM-22 molecular sieve.

[0027] In a preferred embodiment, the aluminum content and / or acid content of the silica-alumina molecular sieve in each bed of catalyst gradually increases according to the order of contact with the material.

[0028] Among them, the number of acidic sites on the silica-alumina molecular sieve varies between different bed layers.

[0029] In a further preferred embodiment, the aluminum content and / or acid content of the silica-alumina molecular sieve in each catalyst bed is between 10 and 500 μmol / dg, depending on the order in which they come into contact with the material. -1 (Preferred 20–450 μmol pydg) -1 It gradually increases within the range.

[0030] In a further preferred embodiment, the aluminum content and / or acid content of the silica-alumina molecular sieve in each catalyst bed is between 50 and 500 μmol / dg, depending on the order in which they come into contact with the material. -1 (Preferred 80-450 μmol pydg) -1 It gradually increases within the range.

[0031] In a preferred embodiment, the composite catalyst bed comprises three or more layers filled with catalyst, preferably 3 to 10 layers, more preferably 3 to 6 layers, such as 3, 4, 5, 6, 7, 8, 9 or 10 layers.

[0032] In a preferred embodiment, the composite catalyst bed comprises three layers. According to the order of contact with the material, the catalyst in the first layer has a framework T atom number of the largest ring structure on the silica-alumina molecular sieve of 14 to 18 (e.g., 14, 15, 16, 17 or 18); and / or, the catalyst in the second layer has a framework T atom number of the largest ring structure on the silica-alumina molecular sieve of 11 to 12 (11 or 12); and / or, the catalyst in the third layer has a framework T atom number of the largest ring structure on the silica-alumina molecular sieve of 9 to 10 (9 or 10).

[0033] In a further preferred embodiment, the composite catalyst bed comprises three layers. According to the order in which they contact the material, the catalyst in the first layer contains silica and alumina molecules selected from at least one of AET molecular sieve, ETR molecular sieve, ZEO-1 molecular sieve, and UTD-1F molecular sieve; and / or, the catalyst in the second layer contains silica and alumina molecules selected from at least one of β-zeolite molecular sieve, mordenite molecular sieve, ZSM-12 molecular sieve, Y molecular sieve, MCM-22 molecular sieve, ITQ-1 molecular sieve, ITQ-24 molecular sieve, ITQ-32 molecular sieve, and AFR molecular sieve; and / or, the catalyst in the third layer contains silica and alumina molecules selected from at least one of ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-5 molecular sieve, EU-1 molecular sieve, ITQ-13 molecular sieve, NU-87 molecular sieve, ZSM-34 molecular sieve, and ZSM-11 molecular sieve.

[0034] In a further preferred embodiment, the composite catalyst bed comprises three layers, wherein, in order of contact with the material, the first layer of catalyst contains silicon and aluminum molecules screened from AET molecular sieves; and / or, the second layer of catalyst contains silicon and aluminum molecules screened from at least one of β-zeolite molecular sieves and mordenite molecular sieves; and / or, the third layer of catalyst contains silicon and aluminum molecules screened from at least one of ZSM-5 molecular sieves, ZSM-11 molecular sieves, and ZSM-22 molecular sieves.

[0035] In a preferred embodiment, the composite catalyst bed comprises three layers, wherein the first layer of the catalyst contains 20–200 μmol pydg of silica-alumina molecular sieve acid in accordance with the order of contact with the material. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the second bed is 200–300 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the third bed is 320–450 μmol pydg. -1 .

[0036] For example, the composite catalyst bed comprises three layers. According to the order of contact with the material, the acid content of the silica-alumina molecular sieve in the catalyst of the first layer is 20, 50, 80, 100, 120, 150, 180, or 200 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the second bed is 200, 220, 240, 260, 280 or 300 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the third bed is 320, 340, 360, 380, 400, 420, 440 or 450 μmol pydg. -1 .

[0037] In a further preferred embodiment, the composite catalyst bed comprises three layers, wherein the first layer of the catalyst contains 80–150 μmol pydg of silica-alumina molecular sieve acid in accordance with the order of contact with the material. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the second bed is 220–280 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the third bed is 340–400 μmol pydg. -1 .

[0038] In a preferred embodiment, the composite catalyst bed comprises three layers, and the weight ratio of the first bed layer, the second bed layer, and the third bed layer, according to the order of contact with the material, is 1:(1-30):(1-30).

[0039] For example, according to the order in which they come into contact with the material, the weight ratio of the first bed layer, the second bed layer, and the third bed layer is 1:(1, 2, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28 or 30):(1, 2, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28 or 30).

[0040] In a preferred embodiment, the metal components in the catalyst of each bed are each independently selected from at least one element from Group IB, Group IIB, Group VIB, Group VIII, and Group VIIB.

[0041] In a further preferred embodiment, the metal component in each catalyst bed is independently selected from at least one of Ni, Mo, Re, Pd, Co, Rh, Ru, Ir, Cr, Pt, and Zn.

[0042] In a preferred embodiment, the loading of the metal component in each catalyst bed is independently 0.01 to 25 wt%, wherein the metal loading is based on the weight of the metal element, with the total catalyst amount being 100 wt%.

[0043] For example, the loading of the metal component in each catalyst bed is independently 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, or 25 wt%, wherein, based on a total catalyst volume of 100 wt%, the metal loading is expressed by weight of the metal element.

[0044] In a further preferred embodiment, the metal loading on each catalyst bed is independently 0.05 to 10 wt%, wherein the total amount of each catalyst bed is 100 wt%, and the metal loading is based on the weight of the metal element.

[0045] In a preferred embodiment, the binder is selected from at least one of alumina, alumina sol, boehmite, and silica sol.

[0046] In a preferred embodiment, in each bed of catalyst, based on a total weight of 100 wt% of the silica-alumina molecular sieve and binder, the silica-alumina molecular sieve is 10-85 wt% and the binder is 5-80 wt% respectively.

[0047] For example, in each bed of catalyst, based on a total weight of 100 wt% of the silica-alumina molecular sieve and binder, the silica-alumina molecular sieves are each independently 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 85 wt%, and the binder is each independently 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt%.

[0048] In a further preferred embodiment, in each bed of catalyst, based on a total weight of 100 wt% of the silica-alumina molecular sieve and the binder, the silica-alumina molecular sieve is 30-80 wt% and the binder is 20-60 wt% respectively.

[0049] In a preferred embodiment, the composite catalyst bed sequentially comprises a first bed filled with a first catalyst, a second bed filled with a second catalyst, and a third bed filled with a third catalyst along the material flow direction. The first catalyst, the second catalyst, and the third catalyst each independently comprise a silica-alumina molecular sieve, the metal component, and optionally the binder.

[0050] In a further preferred embodiment, along the material flow direction from the first catalyst to the third catalyst, the number of framework T atoms of the largest ring structure on the silica-alumina molecular sieve gradually decreases, and / or the aluminum content and / or acid content of the silica-alumina molecular sieve gradually increase.

[0051] Thus, the catalyst in the first bed is the first catalyst, the catalyst in the second bed is the second catalyst, and the catalyst in the third bed is the third catalyst.

[0052] In a preferred embodiment, the catalyst for each bed is prepared independently as follows: the silica-alumina molecular sieve and optionally the binder are mixed to obtain a support, the metal component is loaded, and the support is shaped, dried, and calcined to obtain the catalyst.

[0053] In a further preferred embodiment, the metal component is loaded onto the carrier by at least one of metal exchange, adsorption, deposition, and impregnation.

[0054] A second objective of this invention is to provide the application of the composite catalyst bed described in one objective of this invention in the lightening of heavy aromatics, for example, increasing the production of light C6-C8 aromatics from heavy aromatics.

[0055] The heavy aromatic hydrocarbon is a C9 hydrocarbon containing naphthalene and / or its derivatives. + Aromatic hydrocarbons.

[0056] A third objective of this invention is to provide a method for lightening heavy aromatics, comprising: reacting heavy aromatic feedstock with the composite catalyst bed described in one objective of this invention under hydrogen-containing conditions.

[0057] In a preferred embodiment, the heavy aromatic feedstock is a C9 hydrocarbon containing naphthalene and / or its derivatives. + Aromatic hydrocarbon, preferably, wherein the content of naphthalene and / or its derivatives is 0.1 to 100 wt%, for example 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, or 100 wt%.

[0058] In a preferred embodiment, the temperature of the contact reaction is 200°C to 600°C; and / or the pressure of the contact reaction is 2 to 10.0 MPa; and / or the hydrogen-to-hydrocarbon molecular ratio is 1 to 20.

[0059] For example, the temperature of the contact reaction is 200°C, 300°C, 400°C, 500°C, or 600°C; and / or the pressure of the contact reaction is 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa; and / or the hydrogen-to-hydrocarbon molecular ratio is 1, 2, 5, 8, 10, 12, 15, 18, or 20.

[0060] In a preferred embodiment, the weight hourly space velocity (WHSV) of the heavy aromatic feedstock is 1–7 h⁻¹. -1 For example, 1h -1 2h -1 3h -1 4h -1 5h -1 6h -1 or 7h -1 .

[0061] A third objective of this invention is to overcome the shortcomings of existing alkyl transfer technologies, such as their inability to effectively process heavy aromatic components containing naphthalene and / or its derivatives. This invention provides a novel C9 hydrocarbon containing naphthalene and / or its derivatives. + A method for lightening heavy aromatics involves a catalyst system that utilizes molecular sieves of different pore sizes to match the conversion reactions of different raw material molecules. This method can effectively utilize naphthalene and / or its derivatives in heavy aromatics, thereby improving the utilization rate of heavy aromatic resources.

[0062] The technical solution adopted in this invention is as follows: Increasing the production of light C6-C8 aromatics from naphthalene-containing heavy aromatics, using C9 and above heavy aromatics containing naphthalene and / or its derivatives as raw materials in a composite bed system of silicon-aluminum molecular sieve catalysts with different supported metals, under hydrogen-containing conditions, C6-C8 light aromatic products rich in benzene, toluene, xylene, etc., are generated. This effectively solves the above-mentioned technical problems and can be applied to the industrial production of increasing the production of light C6-C8 aromatics by lightening naphthalene-containing heavy aromatics.

[0063] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0064] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0065] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0066] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0067] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0068] The metal loading in Table 1 is a theoretical value inferred from the amount of raw materials used. Since the initial impregnation method is used, almost all the metal components are loaded onto the catalyst, so the theoretical amount is almost equal to the actual content.

[0069] [Example 1] Preparation of a catalyst that first contacts the material

[0070] Preparation of catalyst in the first bed: 60 g of hydrogen-type molecular sieve ZEO-1, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst A1.

[0071] Preparation of catalyst in the first bed: 60 g of hydrogen-type molecular sieve ZEO-1, 40 g of pseudoboehmite and 3 g of appropriate amount of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst A2.

[0072] Preparation of catalyst in the first bed: 60 g of hydrogen-type molecular sieve UTD-1F and 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried, and calcined at 500℃ for 3 hours to obtain catalyst A3.

[0073] Preparation of catalyst in the first bed: 60 g of hydrogen-type molecular sieve ETR, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst A4.

[0074] The composition of each catalyst is shown in Table 1.

[0075] [Example 2] Preparation of catalyst in secondary contact with materials

[0076] Preparation of catalyst in the second bed: 60 g of hydrogen-type molecular sieve β zeolite, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst B1.

[0077] Preparation of catalyst in the second bed: 60 g of hydrogen-type molecular sieve mordenite, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst B2.

[0078] Preparation of catalyst in the second bed: 60 g of hydrogen-type molecular sieve β zeolite, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst B3.

[0079] Preparation of catalyst in the second bed: 60 g of hydrogen-type molecular sieve ZSM-12, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst B4.

[0080] The composition of each catalyst is shown in Table 1.

[0081] [Example 3] Preparation of the catalyst that comes into final contact with the material

[0082] Preparation of catalyst in the third bed: 60 g of hydrogen-type molecular sieve ZSM-5, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst C1.

[0083] Preparation of catalyst in the third bed: 60 g of hydrogen-type molecular sieve ZSM-11, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst C2.

[0084] Preparation of catalyst in the third bed: 60 g of hydrogen-type molecular sieve ZSM-11, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst C3.

[0085] Preparation of catalyst in the third bed: 60 g of hydrogen-type molecular sieve ZSM-22, 40 g of pseudoboehmite and 3 g of Tianqing powder were mixed evenly, and a certain amount of metal salt aqueous solution and 5 ml of 60% dilute nitric acid were added. The metal components were loaded by the initial wet impregnation method, extruded into strips, dried and calcined at 500℃ for 3 hours to obtain catalyst C4.

[0086] The composition of each catalyst is shown in Table 1.

[0087] Table 1: Catalyst Number, Preparation and Composition

[0088]

[0089]

Example 4

[0090] The composite bed I consists of three layers, which are arranged in the order of contact with the material as the first bed, the second bed, and the third bed. The first bed is filled with catalyst A1, the second bed is filled with catalyst B1, and the third bed is filled with catalyst C1.

[0091]

Example 5

[0092] Composite bed II comprises three layers, which are arranged in the order of contact with the material as a first bed layer, a second bed layer, and a third bed layer. The first bed layer is filled with catalyst A2, the second bed layer is filled with catalyst B2, and the third bed layer is filled with catalyst C2. The total weight of the three layers is the same as that of the three layers in Example 4.

[0093]

Example 6

[0094] Composite bed III comprises three layers, which are arranged in the order of contact with the material as a first bed, a second bed, and a third bed. The first bed is filled with catalyst A3, the second bed is filled with catalyst B3, and the third bed is filled with catalyst C3. The total weight of the three layers is the same as that of the three layers in Example 4.

[0095]

Example 7

[0096] Composite bed IV comprises three layers, which are arranged in the order of contact with the material as the first, second, and third bed layers. The first bed layer is filled with catalyst A4, the second bed layer is filled with catalyst B4, and the third bed layer is filled with catalyst C4. The total weight of the three layers is the same as that of the three layers in Example 4.

[0097]

Example 8

[0098] The composite bed V comprises three layers, which are arranged in the order of contact with the material as a first bed layer, a second bed layer, and a third bed layer. The first bed layer is filled with catalyst A1, the second bed layer is filled with catalyst B2, and the third bed layer is filled with catalyst C3. The total weight of the three layers is the same as that of the three layers in Example 4.

[0099]

Example 9

[0100] Composite bed VI comprises three layers, which are arranged in the order of contact with the material as a first bed layer, a second bed layer, and a third bed layer. The first bed layer is filled with catalyst A3, the second bed layer is filled with catalyst B4, and the third bed layer is filled with catalyst C2. The total weight of the three layers is the same as that of the three layers in Example 4.

[0101]

Example 10

[0102] Composite bed VII comprises three layers, which are arranged in the order of contact with the material as a first bed layer, a second bed layer, and a third bed layer. The first bed layer is filled with catalyst A4, the second bed layer is filled with catalyst B1, and the third bed layer is filled with catalyst C1. The total weight of the three layers is the same as that of the three layers in Example 4.

[0103] Comparative Example 1

[0104] Composite bed i consists of only one layer, which is a mixture of catalyst A1, catalyst B1, and catalyst C1, with the same weight ratio as in Example 4. The total loading weight of the single layer is the same as the total loading weight of the three layers in Example 4.

[0105] Comparative Example 2

[0106] Composite bed ii comprises three layers, which are arranged in the order of contact with the material as the first bed, the second bed, and the third bed. The first bed is filled with catalyst C1, the second bed is filled with catalyst B1, and the third bed is filled with catalyst A1. The total weight of the three layers is the same as that of the three layers in Example 4.

[0107] Comparative Example 3

[0108] Composite bed iii comprises two layers, which are arranged in the order of contact with the material as a first bed and a second bed. The first bed is filled with catalyst A1 and the second bed is filled with catalyst B1. The loading weight ratio of catalyst A1 in the first bed and catalyst B1 in the second bed is the same as the loading weight ratio of catalyst A1 bed to catalyst B1 bed in Example 4. The total loading weight of the two layers in Comparative Example 3 is the same as the total loading weight of the three layers in Example 4.

[0109] Comparative Example 4

[0110] The composite bed iv comprises two layers, which are the first bed and the second bed in the order of contact with the material. The first bed is filled with catalyst B1 and the second bed is filled with catalyst C1. The loading weight ratio of catalyst B1 in the first bed and catalyst C1 in the second bed is the same as the loading weight ratio of catalyst B1 bed to catalyst C1 bed in Example 4. The total loading weight of the two layers in Comparative Example 4 is the same as the total loading weight of the three layers in Example 4.

[0111] Comparative Example 5

[0112] The composite bed v comprises two layers, which are designated as the first bed and the second bed in the order of contact with the material. The first bed is filled with catalyst A1 and the second bed is filled with catalyst C1. The loading weight ratio of catalyst A1 in the first bed and catalyst C1 in the second bed is the same as the loading weight ratio of catalyst A1 bed to catalyst C1 bed in Example 4. Furthermore, the total loading weight of the two layers in Comparative Example 5 is the same as the total loading weight of the three layers in Example 4.

[0113] [Evaluation Experiment]

[0114] The bed layers of Examples 4-10 and the comparative examples were used to lighten heavy aromatic feedstocks containing naphthalene and / or its derivatives. The feedstocks were contacted sequentially with the first layer (first bed layer), the second layer (second bed layer) and the third layer (third bed layer). The evaluation conditions and results are shown in Table 2.

[0115] Table 2:

[0116]

[0117] After bed-layer composite, the conversion rates of heavy aromatics and naphthalene derivatives under the same reaction conditions were improved. Through in vitro comparison, it was found that after bed-layer composite, the conversion rates of heavy aromatics, especially naphthalene derivatives, and the selectivity of the target product BTX were significantly improved.

[0118] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A composite catalyst bed for the lightening of heavy aromatics, comprising three layers of catalyst-filled beds, each catalyst independently comprising a silica-alumina molecular sieve, a metal component, and an optional binder; the pore structure of the silica-alumina molecular sieves in each catalyst bed gradually decreases according to the order of contact with the material, wherein the silica-alumina molecular sieves in the first catalyst bed are selected from at least one of AET molecular sieve, ETR molecular sieve, ZEO-1 molecular sieve, and UTD-1F molecular sieve, and the silica-alumina molecular sieves in the second catalyst bed are selected from β-zeolite molecular sieve, mordenite molecular sieve, ZSM-12 molecular sieve, and Y molecular sieve. The catalyst in the third bed is selected from at least one of MCM-22 molecular sieve, ITQ-1 molecular sieve, ITQ-24 molecular sieve, ITQ-32 molecular sieve, and AFR molecular sieve. The silica-alumina molecular sieve in the third bed is selected from at least one of ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-5 molecular sieve, EU-1 molecular sieve, ITQ-13 molecular sieve, NU-87 molecular sieve, ZSM-34 molecular sieve, and ZSM-11 molecular sieve. The weight ratio of the first bed, the second bed, and the third bed is 1:(5~30):(1~30) according to the order of contact with the material.

2. The composite catalyst bed according to claim 1, characterized in that, The binder is selected from at least one of alumina, alumina sol, boehmite, and silica sol.

3. The composite catalyst bed according to claim 1, characterized in that, In each bed of catalyst, based on a total weight of 100 wt% of the silica-alumina molecular sieve and binder, the silica-alumina molecular sieve is 20-80 wt% and the binder is 20-80 wt% respectively.

4. The composite catalyst bed according to claim 1, characterized in that, The metal components in each catalyst bed are each independently selected from at least one element from Group IB, Group IIB, Group VIB, Group VIII, and Group VIIB.

5. The composite catalyst bed according to claim 1, characterized in that, The metal components in each catalyst bed are independently selected from at least one of Ni, Mo, Re, Pd, Co, Rh, Ru, Ir, Cr, Pt, and Zn.

6. The composite catalyst bed according to claim 1, characterized in that, The loading of the metal component in each catalyst bed is independently 0.01~25 wt%, wherein the metal loading is based on the weight of the metal element, with the total catalyst amount being 100 wt%.

7. The composite catalyst bed according to claim 1, characterized in that, The acid content of the silica-alumina molecular sieve in the catalyst of each bed gradually increases according to the order of contact with the material.

8. The composite catalyst bed according to claim 1, characterized in that, The acid content of the silica-alumina molecular sieve in each catalyst bed ranges from 10 to 500 μmol / dg, depending on the order of contact with the material. -1 It gradually increases within the range.

9. The composite catalyst bed according to claim 1, characterized in that, The acid content of the silica-alumina molecular sieve in each catalyst bed ranges from 20 to 450 μmol / dg, depending on the order of contact with the material. -1 It gradually increases within the range.

10. The composite catalyst bed according to claim 7, characterized in that, According to the order of contact with the materials, the acid content of the silica-alumina molecular sieve in the first bed of catalyst is 20~200 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the second bed is 200~300 μmol pydg. -1 ; and / or, the acid content of the silica-alumina molecular sieve in the catalyst of the third bed is 320~450 μmol pydg. -1 .

11. The application of the composite catalyst bed according to any one of claims 1 to 9 in the lightening of heavy aromatics, wherein the heavy aromatic feedstock is C9 hydrocarbons containing naphthalene and / or its derivatives. + Aromatic hydrocarbons.

12. A method for lightening heavy aromatics, comprising: Under hydrogen-containing conditions, a heavy aromatic feedstock is reacted with the composite catalyst bed described in any one of claims 1 to 10; the heavy aromatic feedstock is a C9 hydrocarbon containing naphthalene and / or its derivatives. + Aromatic hydrocarbons.

13. The method for lightening heavy aromatics according to claim 12, characterized in that, The content of naphthalene and / or its derivatives in the heavy aromatic raw material is 0.1~100wt%.

14. The method for lightening heavy aromatics according to claim 12, characterized in that, The contact reaction temperature is 200℃~600℃; and / or, the contact reaction pressure is 2~10.0 MPa; and / or, the hydrogen-to-hydrocarbon molecular ratio is 1~20; and / or, the weight hourly space velocity of the heavy aromatic feedstock is 1~7 h⁻¹. -1 .

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