Heavy aromatic catalytic conversion method with adjustable reactant-oil ratio

Abstract

The invention relates to a heavy aromatics catalytic conversion method with an adjustable reactant-oil ratio, and the method can efficiently convert heavy aromatics into light aromatics through a non-hydrogen cracking reaction of a raw material containing the heavy aromatics. The problems of high hydrogen consumption, harsh operation conditions and aromatic hydrocarbon loss caused by hydrotreating production of light aromatic hydrocarbon can be avoided; on the other hand, the problem that low-value heavy aromatics are difficult to utilize can be solved, and efficient utilization of resources is achieved. Moreover, part of other C9 < + > products obtained by the cracking reaction of the raw materials in the second reaction zone are returned to the first reaction zone of the cracking reaction unit for reprocessing, heavy aromatics in the raw materials can be fully utilized, the yield of light aromatics can be increased, and the utilization rate of the raw materials can also be increased. Besides, the carbon-containing catalyst is returned from the second reaction zone to the first reaction zone to adjust the catalyst-oil ratio in the first reaction zone, so that various different types of raw materials can be treated, and the method has relatively high applicability and flexibility.

Description

Technical Field

[0001] The present disclosure relates to the field of petrochemical industry, and in particular, to a method for catalytic conversion of heavy aromatics with adjustable reactant-oil ratio. Background Art

[0002] BTX (benzene, toluene, xylene) is an important petrochemical basic product and an important raw material for a variety of chemical products such as synthetic rubber, synthetic fiber and synthetic resin. In the process of producing BTX, C9 heavy aromatics will be generated. At present, the output of C9+ heavy aromatics is large, the value is low, and the utilization channels are limited, resulting in a waste of resources. Converting C9+ heavy aromatics into BTX is undoubtedly an effective way to fully utilize resources and improve the quality and efficiency of enterprises.

[0003] The trimethylol and mesitylene contained in heavy aromatics are important chemical raw materials. Trimethylol is widely used in fine chemicals, mainly for the synthesis of trimellitic anhydride, or isomerization to produce mesitylene and other chemical products, and can also be used as a solvent. At present, trimethylol is mainly separated from C9 aromatics, but heavy aromatics have a wide range of sources and trimethylol concentrations vary. If the trimethylol concentration in the raw material is too low, the separation energy consumption will increase and the separation effect will be affected.

[0004] The existing heavy aromatics lightening technology mostly adopts the fixed bed hydrogenation dealkylation method. However, the hydrogenation process has problems such as high hydrogen consumption, harsh operating conditions, aromatics loss and single product. In addition, the existing technical solutions for processing heavy aromatics cannot increase the production of BTX while reducing the energy consumption of separating unsatisfactory and mesitylene. Summary of the invention

[0005] The present invention discloses a method for catalytic conversion of heavy aromatics with an adjustable reactant-to-oil ratio, so as to solve the problems existing in the prior art such as high hydrogen consumption, harsh operating conditions, aromatics loss, single product, and inability to increase BTX production while reducing the energy consumption of separating unsimilar to trimethylol and mesitylene.

[0006] In order to achieve the above-mentioned purpose, the present disclosure provides a method for catalytic conversion of heavy aromatics with an adjustable reactant-to-oil ratio, the method comprising: allowing a raw material containing heavy aromatics to enter a second reaction zone of a cracking reaction unit for a second cracking reaction to obtain a cracking reaction product; allowing the obtained cracking reaction product to be separated and treated to obtain a benzene product, a toluene product, a xylene product, partial trimethylolene, mesitylene and other C9+ products; allowing at least part of the other C9+ products to enter a first reaction zone of the cracking reaction unit to contact with a cracking catalyst for a first cracking reaction to obtain an oil-agent mixed material; allowing the oil-agent mixed material to enter the second reaction zone; the bed density of the first reaction zone of the cracking reaction unit is 180-700 kg / m 3; The second reaction zone is arranged downstream of the first reaction zone; the catalyst activity of the catalyst in the first reaction zone is 50-99; part of the cracking catalyst includes a carbon-bearing catalyst from the second reaction zone.

[0007] Optionally, the reaction conditions of the second reaction zone include: reaction temperature of 500-580°C, preferably 560-580°C; reaction time of 1-10 seconds, preferably 2-8 seconds.

[0008] Optionally, the reaction conditions of the first reaction zone include: reaction temperature of 580-720°C, preferably 620-660°C; catalyst-oil ratio of (1-100):1, preferably (6-30):1; catalyst activity of 60-90.

[0009] Optionally, the first reaction zone of the cracking reaction unit adopts a dense fluidized bed reactor; the second reaction zone of the cracking reaction unit adopts a dense fluidized bed reactor and / or a dilute phase transport bed reactor; preferably, the cracking reaction unit includes a dense fluidized bed reactor, the dense fluidized bed reactor includes the first reaction zone and the second reaction zone, and the first reaction zone is located upstream of the second reaction zone.

[0010] Optionally, the bed density of the dense phase fluidized bed reactor is 300-500 kg / m 3 The bed line speed is 0.4-2m / s; the bed density of the dilute phase transport bed reactor is less than 180kg / m 3 , the bed linear speed is 2-20m / s.

[0011] Optionally, the initial distillation point of the raw material containing heavy aromatics is 120-150°C, and the final distillation point is 200-250°C.

[0012] Optionally, the content of C9+ aromatics in the raw material containing heavy aromatics is 20-100% by weight.

[0013] Optionally, the raw material containing heavy aromatics is selected from one or more of steam cracking gasoline heavy aromatics, catalytic cracking gasoline heavy aromatics, catalytic cracking gasoline heavy aromatics, catalytic reforming heavy aromatics and PX xylene tower bottom C9+ heavy aromatics.

[0014] Optionally, the cracking reaction product is subjected to a first separation to obtain a gas product, a liquid light fraction and a liquid heavy fraction; the liquid light fraction is subjected to a second separation to obtain the benzene product, the toluene product and the xylene product; the liquid heavy fraction is subjected to a third separation to obtain the unsymmetrical trimethylolene, the mesitylene and the other C9+ products; the cut-off point of the liquid light fraction and the liquid heavy fraction is 120-160°C.

[0015] Optionally, the method further comprises regenerating the spent catalyst obtained from the second cracking reaction, and returning the obtained regenerated catalyst to the first reaction zone of the cracking reaction unit.

[0016] Optionally, the method further comprises adding a fresh agent into the first reaction zone.

[0017] Optionally, the ratio of the weight of the fresh agent to the total weight of the cracking catalyst in the cracking reaction unit is 0.2 or less.

[0018] Optionally, the cracking reaction unit further comprises a regenerator and a circulation pipeline; the method further comprises: allowing the catalyst to be regenerated to enter the regenerator for regeneration to obtain a regenerated catalyst; allowing the regenerated catalyst to return to the first reaction zone through a regeneration inclined tube; allowing part of the catalyst to be regenerated to return to the first reaction zone as the carbon-bearing catalyst through a circulation pipeline;

[0019] Optionally, a fresh agent inlet is provided on the regeneration inclined tube.

[0020] Optionally, the catalyst used in the first reaction zone and the second reaction zone includes zeolite, inorganic oxide and optional clay; based on the total weight of the catalyst, the content of the zeolite is 5-70 weight%, the content of the inorganic oxide is 1-95 weight%, and the content of the clay is 1-50 weight%.

[0021] Optionally, the zeolite of the catalyst includes large-pore zeolite and optional medium-pore zeolite; based on the total weight of the zeolite in the catalyst, the content of large-pore zeolite is 40-100% by weight, preferably 50-80% by weight; the content of medium-pore zeolite is 0-60% by weight, preferably 20-50% by weight; the medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of β zeolite and Y zeolite; the inorganic oxide includes silicon dioxide and / or aluminum oxide; the clay is kaolin and / or halloysite.

[0022] Optionally, the catalyst contains a rare earth element. Preferably, the large-pore zeolite is a Y-type zeolite modified with a rare earth element.

[0023] Optionally, the method further comprises adding steam at the outlet of the first reaction zone.

[0024] Through the above technical scheme, the raw materials containing heavy aromatics can be subjected to non-hydrogenated cracking reactions to efficiently convert heavy aromatics into light aromatics. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatics loss caused by the use of hydrogenation to produce light aromatics; on the other hand, it can solve the problem of low-value heavy aromatics being difficult to utilize and achieve efficient utilization of resources. In addition, part of the other C9+ products obtained by the catalytic cracking reaction of the raw materials in the second reaction zone are returned to the first reaction zone of the cracking reaction unit for recycling, which can make full use of the heavy aromatics in the raw materials, not only to improve the yield of light aromatics, but also to improve the utilization rate of the raw materials. In addition, the carbon-bearing catalyst is returned from the second reaction zone to the first reaction zone to adjust the catalyst-oil ratio in the first reaction zone, which can process a variety of different types of raw materials and has high applicability and flexibility. In addition, the technical solution disclosed in the present invention can improve the yield of light aromatics while co-producing trimethylol and mesitylene, solving the problem of high concentration requirements of trimethylol and mesitylene in the raw materials in the traditional process of separating trimethylol and mesitylene, and achieving enrichment during the reaction process, thereby improving the separation efficiency of trimethylol and mesitylene and reducing the energy consumption required for separation. When the raw materials contain non-aromatic hydrocarbons, light olefins can also be produced as by-products, which can further improve the utilization rate of raw materials.

[0025] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0027] Figure 1 The present invention is a schematic diagram of a method for catalytic conversion of heavy aromatics with adjustable reactant-oil ratio.

[0028] Figure 2 is a schematic diagram of a cracking reaction unit used in the present disclosure.

[0029] Figure 3 It is a schematic diagram of the method for catalytic conversion of heavy aromatics in Comparative Example 1 of the present disclosure.

[0030] Description of Reference Numerals

[0031] 1 Raw materials containing heavy aromatics; 2 Cracking reaction unit; 3 Cracking reaction products; 4 Product separation device; 5 Gaseous products; 6 Liquid light fraction; 7 Liquid heavy fraction; 8 Light aromatic separation device; 9 Heavy aromatic separation device; 10 Benzene product; 11 Toluene product; 12 Xylene product; 13 Trimethylolbenzene; 14 Mesitylene; 15 Other C9+ products; 16 First reaction zone; 17 Second reaction zone; 18 Settler; 19 Inclined tube to be regenerated; 20 Regenerator; 21 Regenerated flue gas; 22 Regenerated inclined tube; 23 Fresh agent; 24 Fresh agent; 25 Circulation pipeline; 26 Riser reactor. DETAILED DESCRIPTION

[0032] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0033] like Figure 1 As shown, the present disclosure provides a method for catalytic conversion of heavy aromatics with an adjustable reactant-to-oil ratio, the method comprising: allowing a raw material containing heavy aromatics to enter a second reaction zone 17 of a cracking reaction unit 2 for a second cracking reaction to obtain a cracking reaction product 3; allowing the cracking reaction product 3 to be separated and treated to obtain a benzene product 10, a toluene product 11, a xylene product 12, partial trimethylolene 13, mesitylene 14 and other C9+ products 15; allowing at least part of the other C9+ products 15 to enter a first reaction zone 16 of the cracking reaction unit 2 to contact with a cracking catalyst for a first cracking reaction to obtain an oil-agent mixed material; allowing the oil-agent mixed material to enter the second reaction zone 17; the bed density of the first reaction zone 16 of the cracking reaction unit 2 is 180-700 kg / m 3 ; The second reaction zone 17 is arranged downstream of the first reaction zone 16; the catalyst activity of the catalyst in the first reaction zone is 50-99; part of the cracking catalyst includes the carbon-bearing catalyst from the second reaction zone.

[0034] Through the above technical scheme, the raw materials containing heavy aromatics can be subjected to non-hydrogenated cracking reactions to efficiently convert heavy aromatics into light aromatics. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatics loss caused by the use of hydrogenation to produce light aromatics; on the other hand, it can solve the problem of low-value heavy aromatics being difficult to utilize and achieve efficient utilization of resources. In addition, part of the other C9+ products obtained by the catalytic cracking reaction of the raw materials in the second reaction zone are returned to the first reaction zone of the cracking reaction unit for recycling, which can make full use of the heavy aromatics in the raw materials, not only to improve the yield of light aromatics, but also to improve the utilization rate of the raw materials. In addition, the carbon-bearing catalyst is returned from the second reaction zone to the first reaction zone to adjust the catalyst-oil ratio in the first reaction zone, which can process a variety of different types of raw materials and has high applicability and flexibility. In addition, the technical solution disclosed in the present invention can improve the yield of light aromatics while co-producing trimethylol and mesitylene, solving the problem of high concentration requirements of trimethylol and mesitylene in the raw materials in the traditional process of separating trimethylol and mesitylene, and achieving enrichment during the reaction process, thereby improving the separation efficiency of trimethylol and mesitylene and reducing the energy consumption required for separation. When the raw materials contain non-aromatic hydrocarbons, light olefins can also be produced as by-products, which can further improve the utilization rate of raw materials.

[0035] In one embodiment, the initial boiling point of the raw material containing heavy aromatics used in the present disclosure is 120-150° C., preferably 140-150° C., and the final boiling point is 200-250° C., preferably 200-220° C. In addition, in the raw material containing heavy aromatics, the content of C9+ aromatics is 20-100% by weight, preferably 50-90% by weight, and more preferably 60-80% by weight.

[0036] In a preferred embodiment, the raw material containing heavy aromatics is selected from at least one of steam cracking gasoline heavy aromatics, catalytic cracking gasoline heavy aromatics, catalytic cracking gasoline heavy aromatics, catalytic reforming heavy aromatics and PX xylene tower bottom C9+ heavy aromatics.

[0037] In the above embodiment, the raw material containing heavy aromatics mainly comprises C9-C12 components. After the raw material is subjected to catalytic cracking reaction and separation treatment, the components of the gas product obtained include H 2 -C4 gas component, the main components of the obtained liquid light fraction are C6-C8 components, and the main components of the obtained liquid heavy fraction are C9+ components.

[0038] In one embodiment, the catalyst used in the first reaction zone and the second reaction zone of the present disclosure includes zeolite, inorganic oxide and optional clay; based on the total weight of the cracking catalyst, the content of the zeolite is 5-70% by weight, preferably 30-60% by weight; the content of the inorganic oxide is 1-95% by weight, preferably 30-70% by weight; the content of the clay is 1-50% by weight, preferably 5-40% by weight.

[0039] The zeolite includes large-pore zeolite and optional medium-pore zeolite; the medium-pore zeolite is preferably ZSM zeolite; the large-pore zeolite is preferably one or more of β zeolite and Y zeolite. Based on the total weight of the zeolite, the content of the large-pore zeolite is 40-100% by weight, preferably 50-80% by weight; the content of the medium-pore zeolite is 0-60% by weight, preferably 20-50% by weight.

[0040] Wherein, the inorganic oxide is silicon dioxide and / or aluminum oxide; and the clay is kaolin and / or halloysite.

[0041] Wherein, the cracking catalyst also contains rare earth elements. The rare earth elements used in the present disclosure are conventionally selected in the art, and this application does not make special requirements. Preferably, the rare earth elements exist in the zeolite of the cracking catalyst, and more preferably, the rare earth elements in the cracking catalyst are mainly derived from Y-type zeolite modified with rare earth elements. In this embodiment, adding rare earth elements to the cracking catalyst can improve the catalytic activity of the cracking catalyst, which is beneficial to improving the activity of the catalytic cracking reaction.

[0042] In a specific embodiment, the method for rare earth modification of Y-type zeolite includes: contacting NaY molecular sieve with rare earth solution or a mixed solution of rare earth solution and ammonium salt, filtering, washing and drying, and then performing a first calcination treatment to obtain rare earth sodium Y molecular sieve; then slurrying the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering and then mixing it with a rare earth solution, and adjusting the pH value of the slurry to 5-6 with ammonia water, filtering or not filtering, drying, and performing a second calcination treatment to obtain a rare earth Y-type molecular sieve.

[0043] In one embodiment, the method for preparing a cracking catalyst comprises:

[0044] The inorganic oxide source, clay and decationized water are mixed and stirred evenly to prepare a slurry, wherein the solid content of the slurry is 10-50% by weight; the pH of the above slurry is adjusted to 1-4 with an inorganic acid such as (hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, etc.), and an aging treatment is performed at this pH value, wherein the temperature of the aging treatment is 20-80°C and the time is 0-2h; then the inorganic oxide is added, stirred for 0.5-1.5 hours to form a colloid, and zeolite is added thereto to form a catalyst slurry, based on the total weight of the solid phase in the catalyst slurry, the content of zeolite is 5-70% by weight, the content of clay is 1-50% by weight, and the content of inorganic oxide is 1-95% by weight, wherein, based on the total weight of the zeolite, the content of large-pore zeolite in the zeolite is 40-100% by weight, and the content of medium-pore zeolite is 0-60% by weight; after continuing to stir, spray drying is performed to prepare a microsphere catalyst. The microsphere catalyst is then calcined at 400-600° C. for 0.5-2 hours, and then washed with ammonium sulfate at 30-80° C. until the sodium oxide content is less than 0.25% by weight, and then rinsed with deionized water and filtered, and then dried at 100-200° C. to obtain a cracking catalyst; wherein the weight of ammonium sulfate: the weight of the microsphere catalyst: the weight of water = (0.1-1): 1: (5-15).

[0045] like Figure 2 As shown, the cracking reaction unit 2 described in the present disclosure includes a first reaction zone 16, a second reaction zone 17, a settler 18, a regenerator 20 and a circulation pipeline 25; wherein the circulation pipeline 25 is used to connect the first reaction zone 16 and the second reaction zone 17.

[0046] The first reaction zone 16 and the second reaction zone 17 are interconnected, and the second reaction zone 17 is disposed downstream of the first reaction zone 16 , so that the material passing through the first reaction zone 16 can directly enter the second reaction zone 17 .

[0047] The first reaction zone 16 is a dense fluidized bed reactor, and the reactor type of the second reaction zone 17 is a dense fluidized bed reactor, a dilute phase transport bed reactor, and a composite reactor consisting of a dense fluidized bed reactor and a dilute phase transport bed reactor. The dense fluidized bed reactor used in the present disclosure is a bubbling bed reactor, a turbulent bed reactor, or a fast bed reactor; the dilute phase transport bed reactor is a riser reactor.

[0048] In a preferred embodiment, the cracking reaction unit 2 includes a dense fluidized bed reactor, and the dense fluidized bed reactor includes the first reaction zone 16 and the second reaction zone 17 , and the first reaction zone 16 is located upstream of the second reaction zone 17 .

[0049] The bed density of the dense phase fluidized bed reactor is preferably 300-500 kg / m 3; The bed linear velocity is 0.1-4m / s, preferably 0.4-2m / s.

[0050] The reactor of the cracking reaction unit 2 may be an expanded-diameter reactor or a constant-diameter reactor.

[0051] The second reaction zone 17 can be integrated with the settler 18, or the upper part of the second reaction zone 17 can be integrated inside the settler 18, so that the material obtained by the reaction in the second reaction zone 17 can enter the settler 18. In addition, the first reaction zone 16 and the settler 18 can also be coaxially arranged or separately arranged according to actual use. Preferably, the first reaction zone 16 and the settler 18 are coaxially arranged.

[0052] In one embodiment, the method further comprises regenerating the spent catalyst obtained from the second cracking reaction, and returning the obtained regenerated catalyst to the cracking reaction unit.

[0053] In a preferred embodiment, using Figure 2 The cracking reaction unit 2 is used to carry out a cracking reaction, and the obtained regenerated catalyst is returned to the first reaction zone 16 of the cracking reaction unit 2.

[0054] In a specific implementation manner, Figure 2 As shown, the settler 18 includes a spent catalyst outlet and a cracking reaction product outlet; the first reaction zone 16 includes a regenerated agent inlet, a fresh agent inlet, a carbonized catalyst inlet and other C9+ product inlets; the second reaction zone 17 includes a raw material inlet and a carbonized catalyst outlet; the regenerator 20 includes a spent catalyst inlet and a regenerated agent outlet; the spent catalyst outlet of the settler 18 is connected to the spent catalyst inlet of the regenerator 20 through a spent catalyst inclined pipe 19; the regenerated agent outlet of the regenerator 20 is connected to the regenerated agent inlet of the first reaction zone 16 through a regeneration inclined pipe 22; the carbonized catalyst outlet of the second reaction zone 17 is connected to the carbonized catalyst inlet of the first reaction zone 16 through a circulation pipeline 25; the other C9+ product inlet of the first reaction zone 16 is connected to the other C9+ product outlet of the heavy aromatics separation device 9; the raw material inlet of the second reaction zone 17 is used to be connected to a raw material source.

[0055] A fresh agent inlet is provided on the regeneration inclined tube 22 , and the fresh agent inlet on the first reaction zone 16 and the fresh agent inlet on the regeneration inclined tube 22 are respectively used to communicate with a fresh agent source.

[0056] A steam inlet may be provided on the reactor of the cracking reaction unit 2 so that steam can enter the second reaction zone 17. The steam inlet is provided at the outlet of the first reaction zone 16 so that steam can enter the second reaction zone 17 from the outlet of the first reaction zone 16.

[0057] In order to flexibly adjust the flow rate of the circulating material between the second reaction zone 17 and the first reaction zone 16 , a flow regulating valve is provided on the circulating pipeline 25 .

[0058] A pre-lifting medium inlet is also provided at the bottom of the first reaction zone 16 so that the pre-lifting medium can enter the first reaction zone 16. The pre-lifting medium used in the present disclosure is conventionally selected in the art, and this application does not make any special requirements. For example, the pre-lifting medium can be water vapor and / or dry gas.

[0059] In one embodiment, in order to further improve the separation effect, a cyclone separator is provided on the upper part of the settler 18 and the regenerator 20. The cyclone separator used in the present disclosure is a conventional choice in the art, and this application does not make any requirements. As for the number of cyclone separators, it can be flexibly selected according to actual production needs. Preferably, the number of cyclone separators is 2.

[0060] Among them, an air collecting chamber is provided at the top of the settler 18, the inlet of the air collecting chamber is connected with the cracking reaction product outlet of the cyclone separator, and the outlet of the air collecting chamber is used to be connected with the cracking reaction product outlet, so that the cracking reaction product can be buffered by the air collecting chamber and then exit the settler 18 through the cracking reaction product outlet.

[0061] An oxygen-containing gas distributor is further provided inside the regenerator 20, and the inlet of the oxygen-containing gas distributor extends to the outside of the regenerator 20 to form an oxygen-containing gas inlet.

[0062] In one embodiment, using Figure 2The method for catalytic conversion of heavy aromatics by using a device comprises: allowing a fresh catalyst 24, a regenerated catalyst and other C9+ products 15 to enter a first reaction zone 16 under the action of a pre-lifting medium and contact with a carbon-bearing catalyst for cracking treatment to obtain an oil-agent mixture; allowing the oil-agent mixture, a raw material 1 containing heavy aromatics and steam to enter a second reaction zone 17 for cracking reaction to obtain a reaction material containing a catalyst to be regenerated and a cracking reaction product 3; allowing the reaction material to enter a settler 18 for separation, and a portion of the catalyst to be regenerated in the reaction material is returned to the first reaction zone 16 from the second reaction zone 17 as a carbon-bearing catalyst through a circulation pipeline 25; allowing the remaining reaction material to move upward into the settler 18, wherein most of the catalyst to be regenerated moves downward under the action of gravity, and the cracking reaction product and a small portion of the catalyst to be regenerated in the reaction material move upward and enter a cyclone separator for separation, so that a small portion of the catalyst to be regenerated returns to the settler 18, and the cracking reaction product 3 exits the settler 18 through a gas collecting chamber. The catalyst to be regenerated in the settler 18 enters the regenerator through the regeneration inclined pipe 19 and is regenerated under the action of the oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 21, which is then discharged; the regenerated catalyst and the fresh agent 23 are returned to the first reaction zone 16 through the regeneration inclined pipe 22.

[0063] In one embodiment, the cracking catalyst in the first reaction zone 16 includes one or more of a regenerated catalyst, a carbon-containing catalyst and a fresh agent, wherein the ratio of the weight of the fresh agent to the total weight of the cracking catalyst is less than 0.2, preferably 0.02-0.18, and further preferably 0.05-0.12.

[0064] In this embodiment, after adding the fresh agent to the first reaction zone 16, the catalyst activity of the catalyst in the first reaction zone 16 can be increased to 50-99, and the catalyst activity of the catalyst in the second reaction zone 17 can be increased to 40-90. In order to further improve the reaction performance of the cracking reaction in the cracking reaction unit, the catalyst activity of the catalyst in the first reaction zone 16 is preferably 60-90, more preferably 68-90; the catalyst activity of the catalyst in the second reaction zone 17 is preferably 50-70, more preferably 55-70.

[0065] In the above embodiment, the fresh agent refers to the fresh cracking catalyst; the regenerated catalyst refers to the cracking catalyst after the first cracking reaction and / or the second cracking reaction; the regenerated catalyst refers to the regenerated catalyst after the regeneration treatment in the regenerator 20; the carbonized catalyst refers to the regenerated catalyst obtained after the second cracking reaction in the second reaction zone.

[0066] In a preferred embodiment, the reaction conditions of the second reaction zone 17 include: reaction temperature of 500-580°C, preferably 560-580°C; reaction time of 1-10 seconds, preferably 2-8 seconds; reaction pressure of 130-450kPa, preferably 160-300kPa; agent-oil ratio of (1-100):1, preferably (5-20):1.

[0067] In one embodiment, the reaction conditions of the first reaction zone 16 include: a reaction temperature of 580-720°C, preferably 620-660°C; a reaction time of 3-20 seconds, preferably 5-15 seconds; a reaction pressure of 130-450 kPa, preferably 160-300 kPa; and a catalyst-oil ratio of (1-100):1, preferably (6-30):1.

[0068] In one embodiment, the catalyst activity disclosed herein refers to the micro-reaction activity index measured by the method of NB / SH / T 0952-2017.

[0069] In one embodiment, the method further includes subjecting the cracking reaction product to a first separation in a product separation device 4 to obtain a gas product, a liquid light fraction and a liquid heavy fraction; subjecting the liquid light fraction to a second separation in a light aromatic separation device 8 to obtain a benzene product, a toluene product and a xylene product; and subjecting the liquid heavy fraction to a third separation in a heavy aromatic separation device 9 to obtain trimethylolene, mesitylene and other C9+ products.

[0070] In one embodiment, the cut point between the gas product and the liquid light fraction is 30-50°C; the cut point between the liquid light fraction and the liquid heavy fraction is 120-160°C.

[0071] In one embodiment, the separation and processing device and method for the first separation described in the present disclosure are conventionally selected in the art, and the present application does not make any requirements, as long as the cracking reaction product can be separated into gas products, liquid light fractions and liquid heavy fractions. In this embodiment, the main components of the gas product include H 2 and C4 gas components; the liquid light fraction is mainly composed of C6-C8 components; the liquid heavy fraction is mainly composed of C9+ components, and the cut point between the liquid light fraction and the liquid heavy fraction is 120-160℃.

[0072] In one embodiment, the separation processing device and method for the second separation described in the present disclosure are conventionally selected in the art, and the present application does not make any requirements. It only needs to be able to separate the light fraction of gasoline into benzene products, toluene products and xylene products. For example, the present application uses aromatic extraction technology for separation, and the aromatic raffinate oil can be returned to the catalytic cracking reactor to continue the reaction, and its recycling position can be located in the first reaction zone.

[0073] In one embodiment, the separation and processing device and method of the third separation disclosed in the present invention are conventionally selected in the art, and the present application does not make any requirements. It only needs to be able to separate the heavy fraction into trimethylol, mesitylene and other C9+ products. For example, the third separation can be a heavy aromatic separation process. For example, the method of heavy aromatic separation process can adopt conventional distillation, extractive distillation, azeotropic distillation, adsorption distillation, reactive distillation, crystallization distillation and thermal coupling distillation and other technologies. Reactive distillation can include reactions such as alkylation and transalkylation. By refining other C9+ products, trimethylol and mesitylene in the liquid heavy fraction of the third separation are further enriched and the concentration is increased, thereby improving the separation efficiency of the third separation for trimethylol and mesitylene and reducing the energy consumption required for separation.

[0074] The following examples will further illustrate the present invention, but are not intended to limit the present invention. The raw materials used in the examples and comparative examples contain heavy hydrocarbons, namely, raw material A and raw material B, wherein raw material A is catalytic cracking gasoline heavy aromatics, raw material B is reforming heavy aromatics, and raw material C is a gasoline fraction rich in C9+ aromatics, wherein the properties of raw material A, raw material B and raw material C are shown in Table 1.

[0075] Table 1 Properties of raw materials A and B

[0076]

[0077] Preparation Example 1

[0078] The preparation method of rare earth Y type molecular sieve (REY) comprises: contacting NaY molecular sieve with rare earth solution or a mixed solution of rare earth solution and ammonium salt, filtering, washing with water, drying, and then performing a first roasting treatment to obtain rare earth sodium Y molecular sieve; then slurrying the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering and then mixing it with a rare earth solution, and adjusting the pH value of the slurry to 6 with ammonia water, filtering or not filtering, drying, and performing a second roasting treatment to obtain rare earth Y type molecular sieve (REY).

[0079] The method for preparing cracking catalyst C1 comprises: mixing aluminum sol and kaolin, and preparing them into a slurry with a solid content of 40% by weight with decationized water, stirring evenly, adjusting the pH of the slurry to 4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), maintaining the pH value, adding aluminum sol after standing and aging for 1 hour at 60°C, stirring for 1 hour to form a colloid, adding rare earth Y molecular sieve (REY) to form a catalyst slurry (solid content of 35% by weight), wherein the weight of REY: the weight of kaolin: the weight of aluminum sol = 50:34:16, continuing to stir and spray drying to form a microsphere catalyst. Then, the microsphere catalyst is roasted at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of microsphere catalyst: the weight of water = 0.5:1:10) until the sodium oxide content is less than 0.25% by weight, followed by rinsing with deionized water and filtering, and then drying at 110°C to obtain cracking catalyst C1.

[0080] Preparation Example 2

[0081] The preparation method of rare earth Y-type molecular sieve (REY) is the same as that of Preparation Example 1;

[0082] The method for preparing cracking catalyst C2 includes: mixing aluminum sol and kaolin, and preparing them into a slurry with a solid content of 40% by weight with decationized water, stirring evenly, adjusting the pH of the slurry to 4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), maintaining the pH value, adding aluminum sol after standing and aging at 60°C for 1 hour, stirring for 1 hour to form a colloid, adding ZSM-5 and rare earth Y-type molecular sieve (REY) to form a catalyst slurry (solid content of 35% by weight), wherein the weight of ZSM-5 molecular sieve: weight of REY: weight of kaolin: weight of aluminum sol = 15:35:34:16, and continuing to stir and spray drying to prepare a microsphere catalyst. The microsphere catalyst was then calcined at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of microsphere catalyst: the weight of water = 0.5:1:10) until the sodium oxide content was less than 0.25% by weight, followed by rinsing with deionized water and filtering, and then drying at 110°C to obtain cracking catalyst C2.

[0083] Test Example 1

[0084] The test is carried out according to the 460°C micro-reaction activity index determination method in NB / SH / T 0952-2017, and the obtained micro-reaction activity index is the catalytic activity of the cracking catalyst.

[0085] Example 1

[0086] use Figure 1 systems and Figure 2The cracking reaction unit 2 carries out catalytic conversion of heavy aromatics, wherein the cracking reaction unit 2 comprises a dense fluidized bed reactor, the dense bed reactor comprises a first reaction zone 16 and a second reaction zone 17, and the first reaction zone 16 is located upstream of the second reaction zone 17.

[0087] The method for catalytic conversion of heavy aromatics comprises: allowing the oil agent mixture from the first reaction zone, the raw material 1 containing heavy aromatics and steam to enter the second reaction zone 17 for cracking reaction to obtain a reaction material containing a catalyst to be regenerated and a cracking reaction product 3; allowing the reaction material to enter the settler 18 for separation, and part of the catalyst to be regenerated in the reaction material is returned to the first reaction zone 16 from the second reaction zone 17 as a carbon-bearing catalyst via the circulation pipeline 25; allowing the remaining reaction material to move upward into the settler 18, wherein most of the catalyst to be regenerated moves downward under the action of gravity, and the cracking reaction product and a small part of the catalyst to be regenerated in the reaction material move upward and enter the cyclone separator for separation, so that a small part of the catalyst to be regenerated returns to the settler 18, and the cracking reaction product 3 exits the settler 18 via the gas collecting chamber. The catalyst to be regenerated in the settler 18 enters the regenerator through the inclined tube 19 and is regenerated under the action of the oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 21; the regenerated flue gas 21 is discharged, and the regenerated catalyst returns to the first reaction zone 16 through the regeneration inclined tube 22;

[0088] The cracking reaction product is subjected to a first separation in a product separation device 4 to obtain a gas product 5, a liquid light fraction 6 and a liquid heavy fraction 7; the liquid light fraction 6 is subjected to a second separation in a light aromatic separation device 8 to obtain a benzene product 10, a toluene product 11 and a xylene product 12; the liquid heavy fraction 7 is subjected to a third separation in a heavy aromatic separation device 9 to obtain partial trimethylolene 13, mesitylene 14 and other C9+ products 15; the fresh agent, the regenerated catalyst and other C9+ products 15 are subjected to a cracking treatment in the first reaction zone 16 under the action of a pre-lifting medium (steam) to obtain the oil agent mixed material. The ratio of the weight of the fresh agent to the total weight of the cracking catalyst in the cracking reaction unit is 0.18:1; the cut point of the gas product and the liquid light fraction is 40°C, and the cut point of the liquid light fraction and the liquid heavy fraction is 150°C.

[0089] The reaction conditions and properties of the products are shown in Table 2.

[0090] Example 2

[0091] The method for catalytic conversion of heavy aromatics is the same as in Example 1, except that the reaction temperature in the first reaction zone is 640° C. The reaction conditions and properties of the products are shown in Table 2.

[0092] Example 3

[0093] The method for catalytic conversion of heavy aromatics is the same as in Example 1, except that the catalyst-oil ratio in the first reaction zone is 8:1. The reaction conditions and properties of the products are shown in Table 2.

[0094] Example 4

[0095] The method for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the first reaction zone of the cracking reaction unit 2 is a dense phase fluidized bed reactor, and the second reaction zone is a riser reactor; wherein the bed density of the riser reactor is 70 kg / m 3 The reaction conditions and properties of the products are shown in Table 2.

[0096] Example 5

[0097] The method for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the raw material containing heavy aromatics is treated with an equal weight of raw material B. The reaction conditions and properties of the products are shown in Table 2.

[0098] Example 6

[0099] The method for catalytic conversion of heavy aromatics is the same as in Example 1, except that the cracking catalyst is replaced by an equal weight of C2. The reaction conditions and properties of the products are shown in Table 2.

[0100] Example 7

[0101] The method for catalytic conversion of heavy aromatics is the same as in Example 1, except that the reaction conditions of the first cracking reaction and the second cracking reaction are different. The reaction conditions and product properties are shown in Table 2.

[0102] Example 8

[0103] The method for catalytic conversion of heavy aromatics is the same as that of Example 1, except that no fresh agent is added when the first cracking reaction is carried out in the first reaction zone.

[0104] Example 9

[0105] The method for catalytic conversion of heavy aromatics is the same as that in Example 1, except that the raw material containing heavy aromatics is raw material C. The reaction conditions and properties of the products are shown in Table 2.

[0106] Comparative Example 1

[0107] The method for catalytic conversion of heavy aromatics is the same as in Example 1, except that Figure 3 The cracking reaction unit is used to carry out the cracking reaction, that is, the reactor of the cracking reaction unit is replaced with the riser reactor 26. The reaction conditions and the properties of the products are shown in Table 2.

[0108] Comparative Example 2

[0109] The method for catalytic conversion of heavy aromatics is the same as in Example 1, except that the cracking catalyst is replaced by an equal weight of CDOS, wherein the CDOS catalytic cracking catalyst is purchased from Changling Catalyst Co., Ltd. The reaction conditions and properties of the products are shown in Table 2.

[0110] Table 2 Conditions of cracking reaction and product properties in Examples and Comparative Examples

[0111]

[0112] As can be seen from Table 2, according to the comparison of the data of Examples 1-9 and Comparative Examples 1-2, it can be seen that the technical solution of the present application can, on the one hand, avoid the problems of high hydrogen consumption, harsh operating conditions and aromatic losses caused by the production of light aromatics by hydroprocessing; on the other hand, it can solve the problem of difficult utilization of low-value heavy aromatics and achieve efficient utilization of resources. According to the comparison of the data in Example 1, Example 2 and Example 3, the first reaction zone of the present application performs non-hydrogen catalytic conversion of heavy aromatics at a temperature of 620-660°C and a catalyst-oil ratio of (6-30):1, which can obtain a higher BTX yield and co-produce trimethylol and mesitylene. When the raw material contains non-aromatic hydrocarbons, low-carbon olefins can also be produced as a by-product, which can further improve the utilization rate of the raw material; according to the comparison of the data in Example 1, Example 4 and Comparative Example 1, the bed density of the first reaction zone of the cracking reaction unit 2 is 180-700kg / m 3 , can obtain a higher BTX yield, and has a good conversion effect on heavy aromatics. The two reaction zones of the cracking reaction unit 2 are both dense phase fluidized bed reactors with bed densities of 180-700 kg / m 3 , which can further improve the yield of BTX; according to the comparison of the data in Example 1, Example 6 and Comparative Example 2, it can be seen that when the catalytic activity of the catalyst in the first reaction zone meets 50-99, a higher yield of BTX can be obtained; according to the comparison of the data in Example 1 and Example 8, it can be seen that adding a fresh agent during the cracking reaction can further improve the yield of BTX; according to the comparison of the data in Example 1, Example 5 and Example 9, it can be seen that the method of the present disclosure can process a variety of different types of raw materials, has high applicability and flexibility, and also has a good conversion effect on raw materials with a high content of C9+ heavy aromatics.

[0113] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0114] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0115] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for catalytic conversion of heavy aromatics with adjustable reactant-to-oil ratio, characterized in that: The method includes: The raw material containing heavy aromatics is fed into the second reaction zone of the cracking reaction unit to carry out a second cracking reaction to obtain a cracking reaction product; the obtained cracking reaction product is separated and treated to obtain a benzene product, a toluene product, a xylene product, unsymmetrical trimethylolene, mesitylene and other C9+ products; Allow at least part of the other C9+ products to enter the first reaction zone of the cracking reaction unit to contact with the cracking catalyst for a first cracking reaction to obtain an oil-agent mixed material; allow the oil-agent mixed material to enter the second reaction zone; The bed density of the first reaction zone of the cracking reaction unit is 180-700 kg / m 3 ; The second reaction zone is disposed downstream of the first reaction zone; the catalyst activity of the catalyst in the first reaction zone is 50 to 99; A portion of the cracking catalyst includes the carbon-bearing catalyst from the second reaction zone.

2. The method according to claim 1, characterized in that The reaction conditions of the second reaction zone include: reaction temperature of 500-580° C., preferably 560-580° C.; reaction time of 1-10 seconds, preferably 2-8 seconds.

3. The method according to claim 1, characterized in that The reaction conditions of the first reaction zone include: reaction temperature of 580-720°C, preferably 620-660°C; catalyst-oil ratio of (1-100):1, preferably (6-30):1; catalyst activity of 60-90.

4. The method according to claim 3, characterized in that: The first reaction zone of the cracking reaction unit adopts a dense phase fluidized bed reactor; the second reaction zone of the cracking reaction unit adopts a dense phase fluidized bed reactor and / or a dilute phase transport bed reactor; Preferably, the cracking reaction unit comprises a dense fluidized bed reactor, and the dense fluidized bed reactor comprises the first reaction zone and the second reaction zone, and the first reaction zone is located upstream of the second reaction zone.

5. The method according to claim 4, characterized in that The bed density of the dense phase fluidized bed reactor is 300-500 kg / m 3 The bed line speed is 0.4-2m / s; the bed density of the dilute phase transport bed reactor is less than 180kg / m 3 , the bed linear speed is 2-20m / s.

6. The method according to claim 1, characterized in that The initial distillation point of the raw material containing heavy aromatics is 120-150°C, and the final distillation point is 200-250°C.

7. The method according to claim 1, characterized in that The content of C9+ aromatics in the raw material containing heavy aromatics is 20-100% by weight.

8. The method according to claim 1 or 6, characterized in that: The raw material containing heavy aromatics is selected from one or more of steam cracking gasoline heavy aromatics, catalytic cracking gasoline heavy aromatics, catalytic cracking gasoline heavy aromatics, catalytic reforming heavy aromatics and PX xylene tower bottom C9+ heavy aromatics.

9. The method according to claim 1, characterized in that: The method further comprises: subjecting the cracking reaction product to a first separation to obtain a gas product, a liquid light fraction and a liquid heavy fraction; subjecting the liquid light fraction to a second separation to obtain the benzene product, the toluene product and the xylene product; subjecting the liquid heavy fraction to a third separation to obtain the unsymmetrical trimethylolene, the mesitylene and the other C9+ products; The cut-off point between the liquid light fraction and the liquid heavy fraction is 120-160°C.

10. The method according to claim 1, characterized in that The method further comprises regenerating the spent catalyst obtained from the second cracking reaction, and returning the obtained regenerated catalyst to the first reaction zone of the cracking reaction unit.

11. The method according to claim 1, characterized in that: The method also includes adding a fresh agent to the first reaction zone.

12. The method according to claim 11, characterized in that The ratio of the weight of the fresh catalyst to the total weight of the cracking catalyst in the cracking reaction unit is 0.2 or less.

13. The method according to claim 10, characterized in that The cracking reaction unit also includes a regenerator and a circulation pipeline; The method further includes: allowing the catalyst to be regenerated to enter the regenerator for regeneration to obtain a regenerated catalyst; allowing the regenerated catalyst to return to the first reaction zone through a regeneration inclined tube; allowing part of the catalyst to be regenerated to return to the first reaction zone as the carbon-bearing catalyst through a circulation pipeline; Optionally, a fresh agent inlet is provided on the regeneration inclined tube.

14. The method according to claim 1, characterized in that The catalyst used in the first reaction zone and the second reaction zone comprises zeolite, inorganic oxide and optionally clay; Based on the total weight of the catalyst, the content of the zeolite is 5-70% by weight, the content of the inorganic oxide is 1-95% by weight, and the content of the clay is 1-50% by weight.

15. The method according to claim 14, characterized in that The zeolite of the catalyst includes large-pore zeolite and optional medium-pore zeolite; based on the total weight of the zeolite in the catalyst, the content of the large-pore zeolite is 40-100% by weight, preferably 50-80% by weight; the content of the medium-pore zeolite is 0-60% by weight, preferably 20-50% by weight; The medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of β zeolite and Y zeolite; The inorganic oxide includes silicon dioxide and / or aluminum oxide; The clay is kaolin and / or halloysite.

16. The method according to claim 15, characterized in that The catalyst contains rare earth elements. Preferably, the large-pore zeolite is Y-type zeolite modified by rare earth elements.

17. The method according to claim 1, characterized in that The method further includes adding steam at the outlet of the first reaction zone.

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