Process for the catalytic conversion of heavy aromatic hydrocarbons with adjustable reactant oil ratio

Abstract

The present disclosure relates to a method for catalytic conversion of heavy aromatic hydrocarbons with adjustable agent-oil ratio, which can efficiently convert heavy aromatic hydrocarbons into light aromatic hydrocarbons through non-hydrogen cracking reaction, thereby avoiding the problems of high hydrogen consumption, harsh operating conditions and aromatic hydrocarbon loss caused by using hydrogenation treatment to produce light aromatic hydrocarbons, and solving the problem of difficult utilization of low-value heavy aromatic hydrocarbons to realize efficient utilization of resources. Moreover, part of other C9+ products obtained by cracking reaction of the raw material in the second reaction zone is returned to the first reaction zone of the cracking reaction unit for recycling, which can make full use of heavy aromatic hydrocarbons in the raw material, thereby not only improving the yield of light aromatic hydrocarbons, but also improving the utilization rate of the raw material. In addition, the carbon-containing catalyst is returned from the second reaction zone to the first reaction zone to adjust the agent-oil ratio in the first reaction zone, which can process various types of raw materials and has high applicability and flexibility.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of petroleum chemical industry, in particular, to a method for catalytic conversion of heavy aromatic hydrocarbons with adjustable reaction agent to oil ratio. BACKGROUND

[0002] BTX (benzene, toluene, xylene) is an important petrochemical basic product, and is an important raw material for synthesizing rubber, synthetic fibers and synthetic resins and various chemical products. In the production of BTX, C9 heavy aromatic hydrocarbons are generated. At present, the yield of C9+ heavy aromatic hydrocarbons is large, the value is low, and the utilization way is limited, causing waste of resources. It is undoubtedly an effective method to fully utilize resources and improve enterprise quality and efficiency to convert C9+ heavy aromatic hydrocarbons into BTX.

[0003] The trimethylbenzene and mesitylene contained in heavy aromatic hydrocarbons are important chemical raw materials. Trimethylbenzene is widely used in fine chemicals, mainly used for synthesizing trimellitic anhydride, or isomerization to produce mesitylene and other chemical products, and can also be used as a solvent. At present, trimethylbenzene is mainly separated from C9 aromatic hydrocarbons, but heavy aromatic hydrocarbons are widely sourced, and the concentration of trimethylbenzene is different. If the concentration of trimethylbenzene in the raw material is too low, the energy consumption for separation will increase, and the separation effect will be affected.

[0004] The existing heavy aromatic hydrocarbon lightening technology mainly adopts the method of fixed bed hydrodealkylation. However, the hydrogen consumption is high, the operation conditions are harsh, the aromatic hydrocarbons are lost, and the products are single. In addition, the existing technical scheme for treating heavy aromatic hydrocarbons cannot increase the yield of BTX while reducing the energy consumption for separating trimethylbenzene and mesitylene. SUMMARY

[0005] The present disclosure provides a method for catalytic conversion of heavy aromatic hydrocarbons with adjustable reaction agent to oil ratio, to solve the problems of high hydrogen consumption, harsh operation conditions, loss of aromatic hydrocarbons, single product, and inability to increase the yield of BTX while reducing the energy consumption for separating trimethylbenzene and mesitylene in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present disclosure provides a method for catalytic conversion of heavy aromatic hydrocarbons with adjustable reaction agent to oil ratio, which comprises: making a raw material containing heavy aromatic hydrocarbons enter a second reaction zone of a cracking reaction unit to perform a second cracking reaction, to obtain a cracking reaction product; performing separation treatment on the obtained cracking reaction product to obtain benzene product, toluene product, xylene product, trimethylbenzene, mesitylene and other C9+ products; making at least part of the other C9+ products enter a first reaction zone of the cracking reaction unit to contact with a cracking catalyst to perform a first cracking reaction, to obtain an oil agent mixture; making the oil agent mixture 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 50-99; and part of the cracking catalyst comprises carbon-carrying catalyst from the second reaction zone.

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

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

[0009] Optionally, 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 phase fluidized bed reactor, which comprises 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 , and the bed linear velocity is 0.4-2 m / s; the bed density of the dilute phase transport bed reactor is less than 180 kg / m 3 , and the bed linear velocity is 2-20 m / s.

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

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

[0013] Optionally, the heavy aromatic hydrocarbon-containing raw material is selected from one or more of steam cracking gasoline heavy aromatic hydrocarbons, catalytic cracking gasoline heavy aromatic hydrocarbons, catalytic cracking gasoline heavy aromatic hydrocarbons, catalytic reforming heavy aromatic hydrocarbons, and PX dimethylbenzene column bottom C9+ heavy aromatic hydrocarbons.

[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 dimethylbenzene product; and the liquid heavy fraction is subjected to a third separation to obtain the mesitylene, the pseudocumene, and the other C9+ product; and the fraction cut points of the liquid light fraction and the liquid heavy fraction are 120-160°C.

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

[0016] Optionally, the method further comprises adding fresh agent in 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 recycle line; the method further comprises feeding the spent catalyst into the regenerator for regeneration to obtain regenerated catalyst; feeding the regenerated catalyst back to the first reaction zone through a regenerated catalyst inclined pipe; feeding part of the spent catalyst as the carbon-laden catalyst back to the first reaction zone through the recycle line.

[0019] Optionally, the regenerated catalyst inclined pipe is provided with a fresh agent inlet.

[0020] Optionally, the catalyst used in the first reaction zone and the second reaction zone comprises zeolite, inorganic oxide and optional clay; 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, based on the total weight of the catalyst.

[0021] Optionally, the zeolite of the catalyst comprises large-pore zeolite and optional medium-pore zeolite; the content of the large-pore zeolite is 40-100% by weight, preferably 50-80% by weight, and the content of the medium-pore zeolite is 0-60% by weight, preferably 20-50% by weight, based on the total weight of the zeolite in the catalyst; 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 comprises silicon dioxide and / or diatomic aluminum oxide; the clay is kaolin and / or polyhydrous kaolin.

[0022] Optionally, the catalyst contains rare earth elements, and preferably the large-pore zeolite is Y-type zeolite modified by rare earth elements.

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

[0024] By the technical scheme, the heavy aromatic hydrocarbons in the raw material can be efficiently converted into light aromatic hydrocarbons through a non-hydrogen cracking reaction. On the one hand, the problems of high hydrogen consumption, harsh operating conditions and loss of aromatic hydrocarbons caused by using hydrogen treatment to produce light aromatic hydrocarbons can be avoided. On the other hand, the problem of difficult utilization of low-value heavy aromatic hydrocarbons can be solved, and efficient utilization of resources can be realized. Moreover, part of other C9+ products obtained by catalytic cracking of the raw material in the second reaction zone returns to the first reaction zone of the cracking reaction unit for recycling, which can make full use of the heavy aromatic hydrocarbons in the raw material, improve the yield of light aromatic hydrocarbons, and improve the utilization rate of the raw material. In addition, the carbon-containing catalyst returns from the second reaction zone to the first reaction zone to adjust the catalyst to oil ratio in the first reaction zone, which can process various types of raw materials, has high applicability and flexibility. In addition, the technical scheme of the present disclosure can improve the yield of light aromatic hydrocarbons while co-producing trimethylbenzene and mesitylene, solve the problem of high concentration requirement of trimethylbenzene and mesitylene in the raw material in the traditional separation process of trimethylbenzene and mesitylene, and realize enrichment in the reaction process, thereby improving the separation efficiency of trimethylbenzene and mesitylene and reducing the energy consumption required for separation. When the raw material contains non-aromatic hydrocarbons, low-carbon olefins can also be produced, which can further improve the utilization rate of the raw material.

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

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

[0027] Figure 1 is a schematic diagram of a method for catalytic conversion of heavy aromatic hydrocarbons with adjustable catalyst to oil ratio according to the present disclosure.

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

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

[0030] Explanation of reference signs

[0031] 1 feedstock containing heavy aromatics; 2 cracking reaction unit; 3 cracking reaction product; 4 product separation device; 5 gaseous product; 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 cymene; 14 mesitylene; 15 other C9+ product; 16 first reaction zone; 17 second reaction zone; 18 settler; 19 green slope; 20 regenerator; 21 regeneration flue gas; 22 regeneration slope; 23 fresh agent; 24 fresh agent; 25 circulation line; 26 riser reactor. DETAILED DESCRIPTION

[0032] The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present disclosure, and are not intended to limit the present disclosure.

[0033] As shown in Figure 1 The present disclosure provides a method for catalytic conversion of heavy aromatics with adjustable oil-to-agent ratio, which comprises: feeding a feedstock containing heavy aromatics into a second reaction zone 17 of a cracking reaction unit 2 to perform a second cracking reaction, to obtain a cracking reaction product 3; separating the cracking reaction product 3 to obtain a benzene product 10, a toluene product 11, a xylene product 12, cymene 13, mesitylene 14, and other C9+ products 15; feeding at least part of the other C9+ products 15 into a first reaction zone 16 of the cracking reaction unit 2 to contact with a cracking catalyst to perform a first cracking reaction, to obtain an oil-agent mixture; feeding the oil-agent mixture into the second reaction zone 17; the bed density of the first reaction zone 16 of the cracking reaction unit 2 is 180-700 kg / m3; 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 comprises carbon-carrying catalyst from the second reaction zone. 3

[0034] ​By the technical scheme, the heavy aromatic hydrocarbons in the raw material can be efficiently converted into light aromatic hydrocarbons through the non-hydrogen cracking reaction. On the one hand, the problems of high hydrogen consumption, harsh operating conditions and loss of aromatic hydrocarbons caused by the production of light aromatic hydrocarbons through hydrogenation treatment can be avoided. On the other hand, the problem of difficult utilization of low-value heavy aromatic hydrocarbons can be solved, and the efficient utilization of resources can be realized. Moreover, part of other C9+ products obtained by catalytic cracking of the raw material in the second reaction zone is returned to the first reaction zone of the cracking reaction unit for recycling, which can make full use of the heavy aromatic hydrocarbons in the raw material, improve the yield of light aromatic hydrocarbons, and improve the utilization rate of the raw material. In addition, the carbon-containing catalyst is returned from the second reaction zone to the first reaction zone to adjust the catalyst to oil ratio in the first reaction zone, which can process various types of raw materials, has high applicability and flexibility. In addition, by using the technical scheme of the present disclosure, the yield of light aromatic hydrocarbons can be improved, and co-production of trimethylbenzene and mesitylene can be realized, solving the problem of high concentration requirement of trimethylbenzene and mesitylene in the raw material in the traditional separation process of trimethylbenzene and mesitylene, and realizing enrichment in the reaction process, thereby improving the separation efficiency of trimethylbenzene and mesitylene and reducing the energy consumption required for separation. When the raw material contains non-aromatic hydrocarbons, low-carbon olefins can also be produced, which can further improve the utilization rate of the raw material.

[0035] In an embodiment, the initial boiling point of the heavy aromatic hydrocarbon-containing raw material 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, the content of C9+ aromatic hydrocarbons in the heavy aromatic hydrocarbon-containing raw material is 20-100% by weight, preferably 50-90% by weight, and further preferably 60-80% by weight.

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

[0037] In the above embodiment, the main component of the heavy aromatic hydrocarbon-containing raw material is C9-C12 component, and after the catalytic cracking reaction and separation treatment of the raw material, the components of the obtained gas product include H2-C4 gas components, the main component of the obtained liquid light fraction is C6-C8 component, and the main component of the obtained liquid heavy fraction is C9+ component.

[0038] In an 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; the content of the zeolite is 5-70% by weight, preferably 30-60% by weight, based on the total weight of the cracking catalyst; the content of the inorganic oxide is 1-95% by weight, preferably 30-70% by weight; and the content of the clay is 1-50% by weight, preferably 5-40% by weight.

[0039] The zeolite comprises a large-pore zeolite and optionally a medium-pore zeolite; the medium-pore zeolite is preferably a ZSM zeolite; the large-pore zeolite is preferably one or more of a beta zeolite and a Y zeolite. The content of the large-pore zeolite is 40-100% by weight, preferably 50-80% by weight, based on the total weight of the zeolite; the content of the medium-pore zeolite is 0-60% by weight, preferably 20-50% by weight.

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

[0041] The cracking catalyst further contains a rare earth element. The rare earth element used in the present disclosure is conventionally selected in the art, and no special requirement is made in the present application. Preferably, the rare earth element is present in the zeolite of the cracking catalyst, and further preferably, the rare earth element in the cracking catalyst is mainly derived from a Y-type zeolite modified by a rare earth element. In this embodiment, the addition of the rare earth element in the cracking catalyst can improve the catalytic activity of the cracking catalyst, thereby facilitating the improvement of the activity of the catalytic cracking reaction.

[0042] In a specific embodiment, the method for modifying a Y-type zeolite with a rare earth element comprises: contacting NaY molecular sieve with a rare earth solution or a mixed solution of a rare earth solution and an ammonium salt, and then performing a first calcination treatment after filtration, water washing and drying, to obtain a rare earth sodium Y molecular sieve; then slushing the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering, mixing with a rare earth solution, and adjusting the pH value of the slurry to 5-6 with ammonia water, and then performing a second calcination treatment after filtration or without filtration and drying, to obtain a rare earth Y-type molecular sieve.

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

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

[0045] As shown in Figure 2 The cracking reaction unit 2 of the present disclosure comprises a first reaction zone 16, a second reaction zone 17, a settler 18, a regenerator 20 and a circulation line 25; wherein the circulation line 25 is used to communicate the first reaction zone 16 and the second reaction zone 17.

[0046] The first reaction zone 16 and the second reaction zone 17 are in communication with each other, and the second reaction zone 17 is arranged 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 phase fluidized bed reactor, and the reactor type of the second reaction zone 17 is a dense phase fluidized bed reactor, a dilute phase transport bed reactor or a composite reactor composed of a dense phase fluidized bed reactor and a dilute phase transport bed reactor. The reactor type of the dense phase 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 comprises a dense phase fluidized bed reactor, and the dense phase fluidized bed reactor comprises 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 0.1-4 m / s, preferably 0.4-2 m / s.

[0050] The reactor of the cracking reaction unit 2 can be a reactor with an expanding diameter or a reactor with an equal diameter.

[0051] The second reaction zone 17 can be integrally arranged with the settler 18, or the upper part of the second reaction zone 17 can be integrally arranged 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 be coaxially arranged or separately arranged according to the actual use, and 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 by the second cracking reaction, and returning the regenerated catalyst to the cracking reaction unit.

[0053] In a preferred embodiment, the cracking reaction is performed by using a cracking reaction unit 2 as shown in Figure 2 , and the regenerated catalyst is returned to the first reaction zone 16 of the cracking reaction unit 2.

[0054] In a specific embodiment, as shown in Figure 2 , the settler 18 comprises a spent catalyst outlet and a cracking reaction product outlet; the first reaction zone 16 comprises a regenerated catalyst inlet, a fresh catalyst inlet, a carbon-containing catalyst inlet and an other C9+ product inlet; the second reaction zone 17 comprises a raw material inlet and a carbon-containing catalyst outlet; the regenerator 20 comprises a spent catalyst inlet and a regenerated catalyst outlet; the spent catalyst outlet of the settler 18 is communicated with the spent catalyst inlet of the regenerator 20 through a spent catalyst inclined pipe 19; the regenerated catalyst outlet of the regenerator 20 is communicated with the regenerated catalyst inlet of the first reaction zone 16 through a regenerated catalyst inclined pipe 22; the carbon-containing catalyst outlet of the second reaction zone 17 is communicated with the carbon-containing 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 communicated with the other C9+ product outlet of the heavy aromatic hydrocarbon separation device 9; and the raw material inlet of the second reaction zone 17 is used to communicate with a raw material source.

[0055] The fresh catalyst inlet on the first reaction zone 16 and the fresh catalyst inlet on the regenerated catalyst inclined pipe 22 are respectively used to communicate with a fresh catalyst source.

[0056] The reactor of the cracking reaction unit 2 can be a reactor with an expanding diameter or a reactor with an equal diameter.

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

[0058] In addition, a pre-lifting medium inlet is arranged 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 a conventional selection in the art, and the present application does not make any special requirements. For example, the pre-lifting medium can be steam and / or dry gas.

[0059] In an embodiment, in order to further improve the separation effect, a cyclone separator is arranged at the upper part of the settler 18 and the regenerator 20. The cyclone separator used in the present disclosure is a conventional selection in the art, and the present application does not make any special requirements. The number of stages of the cyclone separator can be flexibly selected according to actual production needs, and preferably, the number of stages of the cyclone separator is 2 stages.

[0060] In addition, a cyclone separator is arranged at the upper part of the settler 18 and the regenerator 20. The cyclone separator used in the present disclosure is a conventional selection in the art, and the present application does not make any special requirements. The number of stages of the cyclone separator can be flexibly selected according to actual production needs, and preferably, the number of stages of the cyclone separator is 2 stages.

[0061] In addition, a cyclone separator is arranged at the upper part of the settler 18 and the regenerator 20. The cyclone separator used in the present disclosure is a conventional selection in the art, and the present application does not make any special requirements. The number of stages of the cyclone separator can be flexibly selected according to actual production needs, and preferably, the number of stages of the cyclone separator is 2 stages.

[0062] In an embodiment, the present application adopts Figure 2The method for catalytic conversion of heavy aromatics by the device comprises the following steps: the fresh agent 24, regenerated catalyst and other C9+ products 15 are introduced into the first reaction zone 16 under the action of pre-elevation medium and are contacted with the carbon-containing catalyst to perform cracking treatment, so as to obtain an oil agent mixture; the oil agent mixture, the raw material 1 containing heavy aromatics and steam are introduced into the second reaction zone 17 to perform cracking reaction, so as to obtain a reaction material containing spent catalyst and cracking reaction products 3; the reaction material is introduced into the settler 18 to perform separation, part of the spent catalyst in the reaction material returns to the first reaction zone 16 from the second reaction zone 17 as the carbon-containing catalyst through the circulation pipeline 25; the remaining reaction material moves upward into the settler 18, most of the spent catalyst in the reaction material moves downward under the action of gravity, and the cracking reaction products and a small part of the spent catalyst in the reaction material move upward and are introduced into the cyclone separator to perform separation, so that the small part of the spent catalyst returns to the settler 18, and the cracking reaction products 3 are discharged from the settler 18 through the gas collecting chamber. The spent catalyst in the settler 18 is introduced into the regenerator through the spent catalyst inclined pipe 19, is subjected to regeneration treatment under the action of oxygen-containing gas, so as to obtain regenerated catalyst and regenerated flue gas 21, and the regenerated flue gas 21 is discharged; the regenerated catalyst and the fresh agent 23 return to the first reaction zone 16 through the regenerated catalyst inclined pipe 22.

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

[0064] In this embodiment, after the fresh agent is added into the first reaction zone 16, the catalyst activity of the catalyst in the first reaction zone 16 is increased to 50-99, and the catalyst activity of the catalyst in the second reaction zone 17 is 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, and more preferably 68-90; and the catalyst activity of the catalyst in the second reaction zone 17 is preferably 50-70, and more preferably 55-70.

[0065] In the above embodiment, the fresh agent refers to fresh cracking catalyst; the spent catalyst refers to the cracking catalyst after the first cracking reaction and / or the second cracking reaction; the regenerated catalyst refers to the spent catalyst after the regeneration treatment by the regenerator 20; and the carbon-containing catalyst refers to the spent 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: the reaction temperature is 500-580℃, preferably 560-580℃; the reaction time is 1-10 seconds, preferably 2-8 seconds; the reaction pressure is 130-450 kPa, preferably 160-300 kPa; the catalyst to oil ratio is (1-100) : 1, preferably (5-20) : 1.

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

[0068] In an embodiment, the catalyst activity of the present disclosure refers to the micro- reaction activity index determined by the method of NB / SH / T 0952-2017.

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

[0070] In an embodiment, the cut point of the gas product and the light liquid fraction is 30-50℃; and the cut point of the light liquid fraction and the heavy liquid fraction is 120-160℃.

[0071] In an embodiment, the separation processing device and method of the first separation of the present disclosure are conventional choices in the art, and the present application does not make any requirements, as long as the cracking reaction product can be separated into a gas product, a light liquid fraction, and a heavy liquid fraction. In this embodiment, the main components of the gas product include H2 and C4 gas components, etc.; the main components of the light liquid fraction include C6-C8 components; and the main components of the heavy liquid fraction include C9+ components. The cut point of the light liquid fraction and the heavy liquid fraction is 120-160℃.

[0072] In an embodiment, the separation processing device and method of the second separation of the present disclosure are conventional choices in the art, and the present application does not make any requirements, as long as the gasoline light fraction can be separated into a benzene product, a toluene product, and a xylene product. For example, the present application uses aromatic extraction technology for separation, and the aromatic raffinate can be returned to the catalytic cracking reactor for further reaction, and the backfining position can be located in the first reaction zone.

[0073] In one embodiment, the third separation processing device and method described in the present disclosure is a conventional selection in the art, and the present application does not make any requirements, as long as the heavy fraction can be separated into mesitylene, trimethylbenzene and other C9+ products, for example, the third separation can be a heavy aromatic separation process, for example, the method of the heavy aromatic separation process can use conventional rectification, extractive rectification, azeotropic rectification, adsorption rectification, reaction rectification, crystallization rectification and heat coupling rectification and other technologies, and the reaction rectification can include alkylation and transalkylation reactions. Through the recycling of other C9+ products, the mesitylene and trimethylbenzene in the liquid heavy fraction subjected to the third separation are further enriched and concentrated, thereby improving the separation efficiency of the third separation for mesitylene and trimethylbenzene and reducing the energy consumption required for separation.

[0074] The following examples will further illustrate the present application without limiting it. The raw materials used in the examples and comparative examples are raw material A and raw material B, which are heavy hydrocarbon-containing raw materials, wherein raw material A is catalytically cracked 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 material A and raw material B

[0076]

[0077] Preparation Example 1

[0078] The preparation method of the rare earth Y-type molecular sieve (REY) includes: contacting NaY molecular sieve with a rare earth solution or a mixed solution of a rare earth solution and an ammonium salt, and after filtration, water washing and drying, performing a first calcination treatment to obtain a rare earth sodium Y-type molecular sieve; then, the rare earth sodium Y-type molecular sieve is slurried and contacted with an acid solution, filtered, mixed with a rare earth solution, and the pH value of the slurry is adjusted to 6 with ammonia water, and after filtration or without filtration, drying and a second calcination treatment, a rare earth Y-type molecular sieve (REY) is obtained.

[0079] The method for preparing the cracking catalyst C1 comprises: mixing an aluminum sol with kaolin, and preparing a slurry with a solid content of 40% by weight using deionized water, stirring uniformly, adjusting the pH of the slurry to 4 using an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), keeping the pH value, adding the aluminum sol after standing and aging at 60℃ for 1 hour, stirring for 1 hour to form a colloid, adding a rare earth Y type molecular sieve (REY), and forming a catalyst slurry (with a solid content of 35% by weight), wherein the weight of the REY: the weight of the kaolin: the weight of the aluminum sol = 50:34:16, continuing to stir, and then spray drying to prepare a microspherical catalyst. Then, the microspherical catalyst is calcined at 500℃ for 1 hour, washed with ammonium sulfate at 60℃ (wherein the weight of the ammonium sulfate: the weight of the microspherical catalyst: the weight of the water = 0.5:1:10) until the sodium oxide content is less than 0.25% by weight, then rinsed with deionized water and filtered, and then dried at 110℃ to obtain the cracking catalyst C1.

[0080] Preparation Example 2

[0081] The method for preparing the rare earth Y type molecular sieve (REY) is the same as that in Preparation Example 1.

[0082] The method for preparing the cracking catalyst C2 comprises: mixing an aluminum sol with kaolin, and preparing a slurry with a solid content of 40% by weight using deionized water, stirring uniformly, adjusting the pH of the slurry to 4 using an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), keeping the pH value, adding the aluminum sol after standing and aging at 60℃ for 1 hour, stirring for 1 hour to form a colloid, adding ZSM-5 and a rare earth Y type molecular sieve (REY), and forming a catalyst slurry (with a solid content of 35% by weight), wherein the weight of the ZSM-5 molecular sieve: the weight of the REY: the weight of the kaolin: the weight of the aluminum sol = 15:35:34:16, continuing to stir, and then spray drying to prepare a microspherical catalyst. Then, the microspherical catalyst is calcined at 500℃ for 1 hour, washed with ammonium sulfate at 60℃ (wherein the weight of the ammonium sulfate: the weight of the microspherical catalyst: the weight of the water = 0.5:1:10) until the sodium oxide content is less than 0.25% by weight, then rinsed with deionized water and filtered, and then dried at 110℃ to obtain the cracking catalyst C2.

[0083] Test Example 1

[0084] The micro-activity index is determined according to the method in NB / SH / T 0952-2017, and the micro-activity index obtained is the catalyst activity of the cracking catalyst.

[0085] Example 1

[0086] The system and method of the application are used Figure 1 for preparing a cracking catalyst. Figure 2The heavy aromatic catalytic conversion is carried out in a cracking reaction unit 2, wherein the cracking reaction unit 2 comprises a dense phase fluidized bed reactor, the dense phase fluidized 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 carrying out the heavy aromatic catalytic conversion comprises: introducing the oil agent mixture material, the raw material 1 containing heavy aromatics and steam into the second reaction zone 17 to carry out a cracking reaction, so as to obtain a reaction material containing spent catalyst and a cracking reaction product 3; introducing the reaction material into a settler 18 to carry out separation, part of the spent catalyst in the reaction material returns to the first reaction zone 16 from the second reaction zone 17 as carbon-carrying catalyst through a circulation pipeline 25; the remaining reaction material moves upward into the settler 18, most of the spent catalyst in the reaction material runs downward under the action of gravity, and the cracking reaction product and a small part of the spent catalyst in the reaction material run upward and enter a cyclone separator to carry out separation, so as to return the small part of the spent catalyst to the settler 18, and the cracking reaction product 3 is discharged from the settler 18 through a gas collecting chamber; the spent catalyst in the settler 18 enters a regenerator through a spent catalyst inclined pipe 19, and is subjected to a regeneration treatment under the action of an oxygen-containing gas to obtain 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 a regenerated catalyst inclined pipe 22;

[0088] The cracking reaction product is subjected to a first separation through 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 through a light aromatic separation device 8 to obtain a benzene product 10, a toluene product 11 and a dimethylbenzene product 12; the liquid heavy fraction 7 is subjected to a third separation through a heavy aromatic separation device 9 to obtain a trimethylbenzene 13, a mesitylene 14 and other C9+ products 15; fresh agent, regenerated catalyst and other C9+ products 15 are introduced into the first reaction zone 16 under the action of pre-lifting medium (steam) to carry out a cracking treatment, so as to obtain the oil agent mixture 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 fraction cutting point of the gas product and the liquid light fraction is 40°C, and the fraction cutting point of the liquid light fraction and the liquid heavy fraction is 150°C.

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

[0090] Example 2

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

[0092] Example 3

[0093] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that the ratio of agent to oil in the first reaction zone was 8:1. The reaction conditions and product properties are shown in Table 2.

[0094] Example 4

[0095] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that the first reaction zone of the cracking reaction unit 2 was a dense phase fluidized bed reactor and the second reaction zone was a riser reactor; wherein the bed density of the riser reactor was 70 kg / m3. 3 The reaction conditions and product properties are shown in Table 2.

[0096] Example 5

[0097] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that the heavy aromatics-containing feedstock treated was feedstock B of equal weight. The reaction conditions and product properties are shown in Table 2.

[0098] Example 6

[0099] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that the cracking catalyst was replaced with C2 of equal weight. The reaction conditions and product properties are shown in Table 2.

[0100] Example 7

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

[0102] Example 8

[0103] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that no fresh agent was added during the first cracking reaction in the first reaction zone.

[0104] Example 9

[0105] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that the heavy aromatics-containing feedstock treated was feedstock C. The reaction conditions and product properties are shown in Table 2.

[0106] Comparative Example 1

[0107] The process for catalytic conversion of heavy aromatics was the same as in Example 1, except that the cracking reaction was performed using a cracking reaction unit Figure 3 , i.e., the reactor of the cracking reaction unit was replaced with a riser reactor 26. The reaction conditions and product properties are shown in Table 2.

[0108] Comparative Example 2

[0109] The process for catalytic conversion of heavy aromatics was carried out as in Example 1, except that the cracking catalyst was replaced by an equal weight of CDOS, wherein the CDOS catalytic cracking catalyst was purchased from Changling Catalyst Company. The reaction conditions and product properties 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, by comparing the data in Examples 1-9 and Comparative Examples 1-2, it can be seen that, on the one hand, the technical solution of the present application can avoid the problems of high hydrogen consumption, harsh operating conditions and loss of aromatics caused by using hydrotreating to produce light aromatics; on the other hand, it can solve the problem of difficult utilization of low-value heavy aromatics, and realize efficient utilization of resources. By comparing the data in Example 1, Example 2 and Example 3, it can be seen that the first reaction zone of the present application carries out non-hydrogen catalytic conversion of heavy aromatics at a temperature of 620-660℃ and a catalyst to oil ratio of (6-30): 1, which can obtain a high yield of BTX, and co-produce pseudocumene and mesitylene. When the raw material contains non-aromatic hydrocarbons, low-carbon olefins can also be produced as by-products, which can further improve the utilization rate of raw materials; by comparing the data in Example 1, Example 4 and Comparative Example 1, it can be seen that the bed density of the first reaction zone of the cracking reaction unit 2 is 180-700 kg / m 3 , which can obtain a high yield of BTX, has a good conversion effect on heavy aromatics, and both reaction zones of the cracking reaction unit 2 are dense phase fluidized bed reactors with a bed density of 180-700 kg / m 3 , which can further improve the yield of BTX; by comparing the data in Example 1, Example 6 and Comparative Example 2, it can be seen that when the catalyst activity of the catalyst in the first reaction zone satisfies 50-99, a high yield of BTX can be obtained; by comparing the data in Example 1 and Example 8, it can be seen that adding fresh agent during the cracking reaction can further improve the yield of BTX; by comparing the data in Example 1, Example 5 and Example 9, it can be seen that the method of the present application 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 application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the scope of the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0114] It should be further noted that various specific technical features described in the above specific embodiments can be combined in any suitable manner, and the disclosure will not be repeated here for various possible combinations.

[0115] In addition, various different embodiments of the disclosure can also be combined with each other as long as they do not contradict the idea of the disclosure, and they should also be considered as disclosed by the disclosure.

Claims

1. A process for the catalytic conversion of heavy aromatic hydrocarbons with adjustable reactant oil ratio, characterized in that, The method comprises: feeding a heavy aromatic hydrocarbon-containing raw material into a second reaction zone of a cracking reaction unit to perform a second cracking reaction to obtain a cracking reaction product; and separating the obtained cracking reaction product to obtain benzene, toluene, xylene, mesitylene, trimethylbenzene and other C9+ products; feeding at least part of the other C9+ products into a first reaction zone of the cracking reaction unit to perform a first cracking reaction with a cracking catalyst to obtain an oil mixture; and feeding the oil mixture into 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 micro-reaction activity index of the catalyst in the first reaction zone is 50-99; Part of the cracking catalysts comprise carbon-carrying catalysts from the second reaction zone.

2. The method of claim 1, wherein, The reaction conditions of the second reaction zone comprise a reaction temperature of 500-580°C and a reaction time of 1-10 seconds.

3. The method of claim 2, wherein, The reaction conditions of the second reaction zone comprise a reaction temperature of 560-580°C and a reaction time of 2-8 seconds.

4. The method of claim 1, wherein, The reaction conditions of the first reaction zone comprise a reaction temperature of 580-720°C, an agent-to-oil ratio of (1-100):1 and a micro-reaction activity index of the catalyst of 60-90.

5. The method of claim 4, wherein, The reaction conditions of the first reaction zone comprise a reaction temperature of 620-660°C and an agent-to-oil ratio of (6-30):

1.

6. The method of claim 3, wherein, The first reaction zone of the cracking reaction unit adopts a dense-phase fluidized bed reactor; and the second reaction zone of the cracking reaction unit adopts a dense-phase fluidized bed reactor and / or a dilute-phase transport bed reactor.

7. The method of claim 6, wherein, The cracking reaction unit comprises a dense-phase fluidized bed reactor, wherein the dense-phase 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.

8. The method of claim 6, wherein, The bed density of the dense fluidized bed reactor is 300-500 kg / m 3 , and the superficial velocity of the bed is 0.4-2 m / s; the bed density of the dilute transport bed reactor is less than 180 kg / m 3 , and the superficial velocity of the bed is 2-20 m / s.

9. The method of claim 1, wherein, The heavy aromatic hydrocarbon-containing raw material has an initial boiling point of 120-150°C and a final boiling point of 200-250°C.

10. The method of claim 1, wherein, The heavy aromatic hydrocarbon-containing raw material contains 20-100% by weight of C9+ aromatic hydrocarbons.

11. The method of claim 1 or 9, wherein, The heavy aromatic hydrocarbon-containing raw material is selected from one or more of steam-cracking gasoline heavy aromatic hydrocarbons, catalytic-cracking gasoline heavy aromatic hydrocarbons, catalytic-cracking gasoline heavy aromatic hydrocarbons, catalytic reforming heavy aromatic hydrocarbons and PX xylene column bottom C9+ heavy aromatic hydrocarbons.

12. The method of claim 1, wherein, The method further comprises performing a first separation on the cracking reaction product to obtain a gas product, a liquid light fraction and a liquid heavy fraction; performing a second separation on the liquid light fraction to obtain the benzene, the toluene and the xylene; and performing a third separation on the liquid heavy fraction to obtain the mesitylene, the trimethylbenzene and the other C9+ products. The liquid light fraction and the liquid heavy fraction have a fraction cutting point of 120-160°C.

13. The method of claim 1, wherein, The method further comprises regenerating spent catalyst obtained from the second cracking reaction and returning the obtained regenerated catalyst to the first reaction zone of the cracking reaction unit.

14. The method of claim 1, wherein, The method further comprises adding fresh agent into the first reaction zone.

15. The method of claim 14, wherein, The ratio of the weight of the fresh agent to the total weight of the cracking catalysts in the cracking reaction unit is 0.2 or less.

16. The method of claim 13, wherein, The cracking reaction unit further comprises a regenerator and a circulation pipeline. The method further comprises feeding the spent catalyst into the regenerator for regeneration to obtain regenerated catalyst; feeding the regenerated catalyst back to the first reaction zone through a regenerated catalyst inclined pipe; feeding part of the spent catalyst as the carbon-laden catalyst back to the first reaction zone through a recycle line; Optionally, a fresh agent inlet is arranged on the regenerated catalyst inclined pipe.

17. The method of claim 1, wherein, The catalyst used in the first reaction zone and the second reaction zone comprises a zeolite, an inorganic oxide and a clay; 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, based on the total weight of the catalyst, wherein the sum of the contents of the components in the catalyst is 100% by weight.

18. The method of claim 17, wherein, The zeolite of the catalyst comprises a large-pore zeolite and optionally a medium-pore zeolite; the content of the large-pore zeolite is 40-100% by weight, and the content of the medium-pore zeolite is 0-60% by weight, based on the total weight of the zeolite in the catalyst. The medium-pore zeolite is selected from ZSM zeolite; and the large-pore zeolite is selected from β zeolite and / or Y zeolite. The inorganic oxide comprises silicon dioxide and / or diatomic aluminum oxide. The clay is kaolin.

19. The method of claim 18, wherein, The content of the large-pore zeolite is 50-80% by weight, and the content of the medium-pore zeolite is 20-50% by weight, based on the total weight of the zeolite in the catalyst. The clay is hydrous kaolin.

20. The method of claim 18, wherein, The catalyst contains rare earth elements.

21. The method of claim 20, wherein, The large-pore zeolite is Y zeolite modified by rare earth elements.

22. The method of claim 1, wherein, The method further comprises adding steam at the outlet of the first reaction zone.

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