A process for the catalytic conversion of heavy aromatics

Abstract

The present disclosure relates to a method for catalytic conversion of heavy aromatic hydrocarbons, which can efficiently convert heavy aromatic hydrocarbons into light aromatic hydrocarbons through a non-hydrogen cracking reaction, thereby avoiding the shortcomings caused by the production of light aromatic hydrocarbons by hydrogen treatment, solving the problem of difficult utilization of low-value heavy aromatic hydrocarbons, and realizing efficient utilization of resources. 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 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 technical solution of the present disclosure can improve the yield of light aromatic hydrocarbons while co-producing trimethylbenzene and mesitylene, improve the separation efficiency of trimethylbenzene and mesitylene, and reduce the energy consumption required for separation. When the raw material contains non-aromatic hydrocarbons, low-carbon olefins can also be produced.

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. 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, which causes 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. However, the trimethylbenzene and mesitylene contained in heavy aromatic hydrocarbons are important chemical raw materials. Trimethylbenzene is widely used in fine chemical industry, mainly used for synthesizing trimellitic anhydride, or isomerization to produce chemical products such as mesitylene, and can also be used as a solvent. Mesitylene is an important organic chemical raw material, mainly used for producing trimesic acid, synthetic resin, etc., and can be produced into mesityl aniline by nitration and reduction, which is an intermediate for organic dyes, medicines, special adhesives and pesticides, and can also be used as a special solvent, extractant, adsorbent, swelling agent, and has a wide range of uses in pharmaceuticals and photographic materials.

[0003] At present, trimethylbenzene is mainly separated from C9 aromatic hydrocarbons. The production technology of trimethylbenzene and mesitylene mainly separates from C9 aromatic hydrocarbons, including conventional rectification, extractive rectification, azeotropic rectification, adsorption rectification, reaction rectification, crystallization rectification and heat coupling rectification. However, 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 of separation will increase, and the separation effect will be affected.

[0004] In addition, 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. SUMMARY

[0005] The present disclosure provides a method for catalytic conversion of heavy aromatic hydrocarbons to solve the problems of high hydrogen consumption, harsh operation conditions, loss of aromatic hydrocarbons and single product in the existing hydrogenation technology.

[0006] To achieve the above object, the present disclosure provides a method for catalytic conversion of heavy aromatics, which comprises: feeding a heavy aromatics-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; 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 a benzene product, a toluene product and a xylene product; performing a third separation on the liquid heavy fraction to obtain a mesitylene, a tri-methyl benzene 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, to obtain an oil agent mixture; feeding the oil agent mixture into the second reaction zone of the cracking reaction unit; 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.

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

[0008] Optionally, the reaction conditions of the first reaction zone include: the reaction temperature is 580-720℃, preferably 620-660℃; the catalyst / oil ratio is (1-100):1, preferably (6-30):1; the catalyst activity is 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 aromatics-containing raw material is 120-150℃, and the final boiling point is 200-250℃.

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

[0013] Optionally, the heavy aromatic hydrocarbon-containing feedstock is selected from one or more of steam 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 cut 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 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 to 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; the method further comprises passing the spent catalyst into the regenerator to regenerate the spent catalyst into regenerated catalyst; and passing the regenerated catalyst through a regenerated catalyst inclined pipe back to the first reaction zone.

[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 is a cracking catalyst; the cracking catalyst comprises zeolite, inorganic oxide, and optionally 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 cracking catalyst.

[0021] Optionally, the zeolite of the cracking catalyst comprises large-pore zeolite and optionally 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 cracking catalyst; the medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of beta zeolite and Y zeolite; the inorganic oxide comprises silicon dioxide and / or di-aluminum trioxide; and the clay is kaolin and / or poly-hydro 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 hydrocarbon-containing raw material is subjected to a non-hydrogenation cracking reaction, and the heavy aromatic hydrocarbon can be efficiently converted into light aromatic hydrocarbon. On one hand, the problems of high hydrogen consumption, harsh operating conditions and aromatic hydrocarbon loss caused by the production of light aromatic hydrocarbon by hydrogenation treatment can be avoided. On the other hand, the problem of difficult utilization of low-value heavy aromatic hydrocarbon 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 is returned to the first reaction zone of the cracking reaction unit for recycling, so that the heavy aromatic hydrocarbon in the raw material can be fully utilized, the yield of light aromatic hydrocarbon can be improved, and the utilization rate of the raw material can be improved. In addition, by using the technical scheme of the present disclosure, the yield of light aromatic hydrocarbon can be improved, and co-production of pseudocumene and mesitylene can be realized, so that the problem of high concentration requirement of pseudocumene and mesitylene in the raw material in the traditional separation process of pseudocumene and mesitylene can be solved, and enrichment can be realized in the reaction process, so that the separation efficiency of pseudocumene and mesitylene is improved and the energy consumption required for separation is reduced. When the raw material contains non-aromatic hydrocarbons, low-carbon olefins can also be produced, and the utilization rate of the raw material can be further improved.

[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 together with the following specific embodiments, serve to explain the present disclosure but do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 is a schematic diagram of a method for catalytic conversion of heavy aromatic hydrocarbon 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 hydrocarbon in Comparative Example 1 of the present disclosure.

[0030] Explanation of reference signs

[0031] 1 heavy aromatic hydrocarbon-containing raw material; 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 hydrocarbon separation device; 9 heavy aromatic hydrocarbon separation device; 10 benzene product; 11 toluene product; 12 xylene product; 13 pseudocumene; 14 mesitylene; 15 other C9+ product; 16 cracking reactor; 17 steam; 18 settler; 19 to-be-regenerated inclined pipe; 20 regenerator; 21 regenerated flue gas; 22 regenerated inclined pipe; 23 fresh agent; 24 fresh agent; 25 riser reactor. DETAILED DESCRIPTION

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

[0033] As shown in Figure 1 The present disclosure provides a method for catalytic conversion of heavy aromatic hydrocarbons, which comprises: feeding a raw material containing heavy aromatic hydrocarbons into a second reaction zone of a cracking reaction unit 2 to perform a second cracking reaction, to obtain a cracking reaction product; feeding the cracking reaction product into a product separation device 4 to perform a first separation, to obtain a gas product 5, a liquid light fraction 6 and a liquid heavy fraction 7; feeding the liquid light fraction 6 into a light aromatic hydrocarbon separation device 8 to perform a second separation, to obtain a benzene product 10, a toluene product 11 and a xylene product 12; feeding at least part of the other C9+ products into a first reaction zone of the cracking reaction unit 2 to perform a first cracking reaction, to obtain an oil agent mixture material; feeding the oil agent mixture material into the second reaction zone of the cracking reaction unit 2; the bed density of the first reaction zone of the cracking reaction unit 2 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.

[0034] Through the above technical solution, the raw material containing heavy aromatic hydrocarbons is subjected to a non-hydrogen cracking reaction, which can efficiently convert heavy aromatic hydrocarbons into light aromatic hydrocarbons. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatic hydrocarbon loss caused by using hydrogen treatment to produce light aromatic hydrocarbons; on the other hand, it can solve the problem of difficult utilization of low-value heavy aromatic hydrocarbons, and realize efficient utilization of resources. Moreover, part of the other C9+ products obtained by catalytic cracking of the raw material in the second reaction zone are returned to the first reaction zone of the cracking reaction unit for backfiring, which can make full use of the heavy aromatic hydrocarbons in the raw material, not only can improve the yield of light aromatic hydrocarbons, but also can improve the utilization rate of the raw material. In addition, by using the technical solution of the present disclosure, the yield of light aromatic hydrocarbons can be improved, and the production of mesitylene and pseudocumene can be achieved at the same time, which solves the problem of high concentration requirement of pseudocumene and mesitylene in the raw material in the traditional separation process of pseudocumene and mesitylene, and realizes enrichment in the reaction process, thereby improving the separation efficiency of pseudocumene 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 one embodiment, the feedstock containing heavy aromatics used in the present disclosure has an initial boiling point of 120-150°C, preferably 140-150°C, and a final boiling point of 200-250°C, preferably 200-220°C. In addition, the content of C9+aromatics in the feedstock containing heavy aromatics is 20-100% by weight, preferably 50-90% by weight, and further preferably 60-80% by weight.

[0036] In one preferred embodiment, the feedstock 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 dimethylbenzene column bottom C9+heavy aromatics.

[0037] In the above embodiment, the feedstock containing heavy aromatics has C9-C12 components as the main components, and after the catalytic cracking reaction and separation treatment, the gas product obtained includes H2-C4 gas components, 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 is a cracking catalyst; the cracking catalyst 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] In the above embodiment, the zeolite includes large-pore zeolite and optional medium-pore zeolite; the medium-pore zeolite is preferably ZSM zeolite; and the large-pore zeolite is preferably one or more of β zeolite and Y zeolite. The content of the large-pore zeolite is 40-100% by weight, preferably 60-100% by weight, based on the total weight of the zeolite; and the content of the medium-pore zeolite is 0-60% by weight, preferably 0-25% by weight.

[0040] In the above embodiment, the inorganic oxide is silicon dioxide and / or diatomic aluminum oxide; and the clay is kaolin and / or polyhydrous kaolin.

[0041] In the above embodiment, the cracking catalyst further contains rare earth elements. The rare earth elements used in the present disclosure are conventionally selected in the art, and no special requirements are made in the present application. Preferably, the rare earth elements exist in the zeolite of the cracking catalyst, and further preferably, the rare earth elements in the cracking catalyst mainly come from Y-type zeolite modified by rare earth elements. In this embodiment, the addition of rare earth elements 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 Y-type zeolite with rare earths comprises: contacting NaY molecular sieve with a rare earth solution or a mixed solution of rare earth solution and 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 with an acid solution, and then mixing with a rare earth solution after filtration, 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: mixing and stirring a source of inorganic oxide, clay and deionized water uniformly to prepare a slurry, wherein the solid content of the slurry is 10-50% by weight; adjusting the pH of the slurry to 1-4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, etc.), and performing an aging treatment at the pH, wherein the temperature of the aging treatment is 20-80℃ and the time is 0-2h; then adding inorganic oxide and stirring for 0.5-1.5h to form a colloid, and adding zeolite to the colloid to form a catalyst slurry, wherein 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, based on the total weight of the solid phase in the catalyst slurry, and wherein the content of the large-pore zeolite in the zeolite is 40-100% by weight and the content of the medium-pore zeolite in the zeolite is 0-60% by weight, based on the total weight of the zeolite; and then spray drying after continuous stirring to prepare a microspherical catalyst. Then the microspherical catalyst is calcined at 400-600℃ for 0.5-2h, washed with ammonium sulfate at 30-80℃ until the sodium oxide content is less than 0.25% by weight, then leached with deionized water and filtered, and then dried at 100-200℃ to obtain the cracking catalyst; wherein the weight of ammonium sulfate: the weight of the microspherical catalyst: the weight of water = (0.1-1) : 1 : (5-15).

[0044] As shown in Figure 2 The cracking reaction unit 2 comprises a cracking reactor 16, a regenerator 20 and a settler 18; wherein the cracking reactor 16 comprises a first reaction zone and a second reaction zone.

[0045] The second reaction zone is in communication with the first reaction zone and is arranged downstream of the first reaction zone.

[0046] The first reaction zone is a dense phase fluidized bed reactor, and the second reaction zone is a dense phase fluidized bed reactor, a dilute phase transport bed reactor or a composite reactor comprising 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; and the dilute phase transport bed reactor is a riser reactor.

[0047] In a preferred embodiment, the cracking reaction unit 2 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.

[0048] The bed density of the dense phase fluidized bed reactor is preferably 300-500 kg / m 3 , and the bed linear velocity is 0.1-4 m / s, preferably 0.4-2 m / s.

[0049] The reactor of the cracking reactor 16 can be a reactor with expanding diameter or a reactor with equal diameter.

[0050] The cracking reactor 16 can be integrated with the settler 18, so that the material reacted in the cracking reactor 16 can enter the settler 18.

[0051] In an embodiment, the cracking reaction is carried out by using a cracking reaction unit 2 as shown in Figure 2 , so that the spent catalyst obtained in the second cracking reaction is regenerated, and the regenerated catalyst is returned to the cracking reactor 16.

[0052] In a preferred embodiment, the method further comprises returning the regenerated catalyst to the first reaction zone of the cracking reaction unit.

[0053] In a specific embodiment, as shown in Figure 2 , the settler 18 comprises a spent catalyst outlet, the cracking reactor 16 comprises a regenerated catalyst inlet, a fresh catalyst inlet, a raw material inlet and an other C9+ product inlet; 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 inlet of the cracking reactor 16 is communicated with the regenerated catalyst outlet of the regenerator 20 through a regenerated catalyst inclined pipe 22; the raw material inlet of the cracking reactor 16 is used to communicate with a raw material source; and the other C9+ product inlet of the cracking reactor 16 is communicated with the other C9+ product outlet of the heavy aromatic hydrocarbon separation device 9.

[0054] The fresh catalyst inlet of the cracking reactor 16 and the fresh catalyst inlet on the regenerated catalyst inclined pipe 22 are respectively used to communicate with a fresh catalyst source.

[0055] The cracking reactor 16 is further provided with a steam inlet, so that the steam 17 can enter the cracking reactor 16. The steam inlet is provided at the outlet of the first reaction zone, so that the steam 17 can enter the second reaction zone from the outlet of the first reaction zone.

[0056] The pre-lifting medium inlet is arranged at the bottom of the cracking reactor 16 to enable the pre-lifting medium to enter the cracking reactor 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.

[0057] 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, respectively. 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 the actual production needs, and preferably, the number of stages of the cyclone separator is 2 stages.

[0058] The gas collection chamber is arranged at the top of the settler 18, the inlet of the gas collection chamber is in communication with the cracking reaction product outlet of the cyclone separator, and the outlet of the gas collection chamber is used to be in communication with the cracking reaction product outlet, so that the cracking reaction product can be buffered in the gas collection chamber and then discharged from the settler 18 through the cracking reaction product outlet.

[0059] The oxygen-containing gas distributor is further arranged 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.

[0060] In an embodiment, the method for catalytically converting heavy aromatic hydrocarbons by using the device of Figure 2 The method for catalytically converting heavy aromatic hydrocarbons by using the device of includes: enabling the fresh agent 24, the regenerated catalyst and other C9+ products to enter the first reaction zone under the action of the pre-lifting medium to perform the first cracking reaction, to obtain an oil agent mixture; enabling the oil agent mixture, the raw material containing heavy aromatic hydrocarbons and steam to enter the second reaction zone to perform the second cracking reaction, to obtain a mixture containing the cracking reaction product and the spent catalyst. The mixture is enabled to enter the settler 18 to perform the separation, most of the spent catalyst in the mixture runs downward under the action of gravity, the cracking reaction product and a small part of the spent catalyst in the mixture run upward and enter the cyclone separator to perform the separation, so that the small part of the spent catalyst returns to the settler, and the cracking reaction product is discharged from the settler 18 through the gas collection chamber. The spent catalyst passes through the spent inclined pipe 19 to enter the regenerator 20, and is subjected to the regeneration treatment under the action of the oxygen-containing gas, to obtain the regenerated catalyst and the regeneration flue gas 21, and the regeneration flue gas 21 is discharged. The regenerated catalyst and the fresh agent 23 return to the first reaction zone of the cracking reactor 16 through the regenerated inclined pipe 22.

[0061] In an embodiment, the cracking catalyst in the first reaction zone includes at least one of the regenerated catalyst and the fresh agent, wherein the ratio of the weight of the fresh agent to the total weight of the cracking catalyst in the cracking reactor 16 is 0.2 or less, preferably 0.02-0.18, and further preferably 0.05-0.12.

[0062] In this embodiment, after the fresh agent is added into the first reaction zone, the catalyst activity of the catalyst in the first reaction zone is increased to 50-99, and the catalyst activity of the catalyst in the second reaction zone is increased to 40-90. In order to further improve the reaction performance of the cracking reaction in the cracking reactor 16, the catalyst activity of the catalyst in the first reaction zone is preferably 60-90, and more preferably 68-90; the catalyst activity of the catalyst in the second reaction zone is preferably 50-70, and more preferably 55-70.

[0063] 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; and the regenerated catalyst refers to the spent catalyst after the regeneration treatment by the regenerator 20.

[0064] In a preferred embodiment, the reaction conditions of the second reaction zone 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; and the agent / oil ratio is (1-100):1, preferably (5-20):1.

[0065] In an embodiment, the reaction conditions of the first reaction zone 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; and the agent / oil ratio is (1-100):1, preferably (6-30):1.

[0066] 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.

[0067] In an embodiment, the first separation separation treatment device and method 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 gaseous product, liquid light fraction and liquid heavy fraction. Among them, the fraction cut point of the gaseous product and the liquid light fraction is 30-50℃; the fraction cut point of the liquid light fraction and the liquid heavy fraction is 120-160℃.

[0068] In an embodiment, the second separation separation treatment device and method 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 benzene product, toluene product and 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.

[0069] 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 adopt 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.

[0070] The following examples will further illustrate the present application without limiting the present application. 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, and raw material B is reforming heavy aromatics, and the properties of raw material A and raw material B are shown in Table 1.

[0071] Table 1 Properties of raw material A and raw material B

[0072]

[0073] Preparation Example 1

[0074] The preparation method of the rare earth Y-type molecular sieve (REY) includes: contacting a 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 performing a second calcination treatment, a rare earth Y-type molecular sieve (REY) is obtained.

[0075] 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.

[0076] Preparation Example 2

[0077] The method for preparing the rare earth Y type molecular sieve (REY) is the same as that in Preparation Example 1.

[0078] 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.

[0079] Test Example 1

[0080] 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.

[0081] Example 1

[0082] The system and method of the application are used Figure 1 to prepare a cracking catalyst. Figure 2The heavy aromatic catalytic conversion is carried out in the cracking reaction unit 2, wherein the cracking reactor 16 of the cracking reaction unit 2 is a dense phase fluidized bed reactor, the dense phase bed reactor comprises a first reaction zone and a second reaction zone, and the first reaction zone is located upstream of the second reaction zone.

[0083] 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 the steam 17 into the second reaction zone to carry out a second cracking reaction, so as to obtain a mixture containing the cracking reaction product 3 and spent catalyst. The mixture is introduced into the settler 18 to carry out separation, most of the spent catalyst in the mixture runs downward under the action of gravity, the cracking reaction product 3 and a small part of the spent catalyst in the mixture run upward and enter the cyclone separator to carry out separation, so as to return the small part of the spent catalyst to the settler, and the cracking reaction product 3 is discharged from the settler 18 through the gas collecting chamber. The spent catalyst passes through the spent catalyst inclined pipe 19 and enters the regenerator 20, and is subjected to a regeneration treatment under the action of the oxygen-containing gas, so as to obtain the regenerated catalyst and the regenerated flue gas 21, and the regenerated flue gas 21 is discharged; the regenerated catalyst returns to the first reaction zone of the dense phase fluidized bed reactor through the regenerated catalyst inclined pipe 22.

[0084] The cracking reaction product is subjected to a first separation through the product separation device 4, so as to obtain the gas product 5, the liquid light fraction 6 and the liquid heavy fraction 7; the liquid light fraction 6 is subjected to a second separation through the light aromatic separation device 8, so as to obtain the benzene product 10, the toluene product 11 and the xylene product 12; the liquid heavy fraction 7 is subjected to a third separation through the heavy aromatic separation device 9, so as to obtain the trimethylbenzene 13, the mesitylene 14 and the other C9+ product 15; the fresh agent, the regenerated catalyst and the other C9+ product 15 are introduced into the first reaction zone under the action of the pre-lifting medium (steam), so as to obtain the oil agent mixture material. The cut point of the fraction of the gas product and the liquid light fraction is 40℃, the cut point of the fraction of the liquid light fraction and the liquid heavy fraction is 150℃, and the ratio of the weight of the fresh agent to the total weight of the cracking catalyst in the cracking reactor 16 is 0.18:1.

[0085] The reaction conditions and the properties of the products are shown in Table 2.

[0086] Example 2

[0087] The method for carrying out the heavy aromatic catalytic conversion is the same as that in Example 1, and the difference lies in that the reaction temperature of the first reaction zone is 640℃. The reaction conditions and the properties of the products are shown in Table 2.

[0088] Example 3

[0089] The process for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the first reaction zone of the cracking reactor 16 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 product properties are shown in Table 2.

[0090] Example 4

[0091] The process for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the feedstock is replaced by an equal weight of feedstock B. The reaction conditions and product properties are shown in Table 2.

[0092] Example 5

[0093] The process for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the catalyst is replaced by an equal weight of catalyst C2, and the ratio of the weight of fresh agent to the total weight of the cracking catalyst in the cracking reactor 16 is 0.02:1. The reaction conditions and product properties are shown in Table 2.

[0094] Example 6

[0095] The process for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the bed density of the dense phase fluidized bed reactor is 250 kg / m 3 . The reaction conditions and product properties are shown in Table 2.

[0096] Example 7

[0097] The process for catalytic conversion of heavy aromatics is the same as that of 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.

[0098] Example 8

[0099] The process for catalytic conversion of heavy aromatics is the same as that of Example 1, except that no fresh agent is added during the first cracking reaction in the first reaction zone. The reaction conditions and product properties are shown in Table 2.

[0100] Comparative Example 1

[0101] The process for catalytic conversion of heavy aromatics is the same as that of Example 1, except that the cracking reaction unit is replaced by a cracking reaction unit Figure 3 , i.e. the cracking reactor 16 is replaced by a riser reactor 25. The reaction conditions and product properties are shown in Table 2.

[0102] Comparative Example 2

[0103] The method for catalytically converting heavy aromatics is the same as that in Example 1, except that the cracking catalyst C1 is replaced by an equal weight of cracking catalyst CDOS, wherein the CDOS catalytic cracking catalyst is purchased from Changling Catalyst Company. The reaction conditions and product properties are shown in Table 2.

[0104] Table 2 Reaction conditions and product properties

[0105]

[0106]

[0107] As shown in Table 2, according to the data in Examples 1-8 and Comparative Examples 1-2, using 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. According to the data in Example 1 and Example 2, the first reaction zone of the present application can perform non-hydrogen catalytic conversion of heavy aromatics at a temperature of 620-660℃, 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; according to the data in Example 1, Example 3, Example 6 and Comparative Example 1, the bed density of the first reaction zone of the cracking reactor 16 is 180-700 kg / m 3 , which can obtain a high yield of BTX, has good conversion effect on heavy aromatics, and the two reaction zones of the cracking reaction unit 2 are both dense phase fluidized bed reactors with a bed density of 180-700 kg / m 3 , which can further improve the yield of BTX; according to the data in Example 1 and Example 8, adding fresh agent during the cracking reaction can further improve the yield of BTX; according to the data in Example 1, Example 5 and Comparative Example 2, when the catalyst activity of the catalyst in the first reaction zone satisfies 50-99, a high yield of BTX can be obtained.

[0108] The preferred embodiments of the present disclosure are described in detail above with reference to the accompanying drawings, but the present disclosure 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 disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0109] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0110] Furthermore, various embodiments of the present disclosure can be arbitrarily combined with each other, as long as the combination does not violate the idea of the present disclosure, and it should be considered as disclosed in the present disclosure.

Claims

1. A process for the catalytic conversion of heavy aromatic hydrocarbons, 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; 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 a benzene product, a toluene product and a xylene product; performing a third separation on the liquid heavy fraction to obtain a trimethylbenzene, a mesitylene 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, to obtain an oil mixture; feeding the oil mixture into the second reaction zone of the cracking reaction unit; 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; a micro-reaction activity index of the catalyst in the first reaction zone is 50-99; a content of C9+ aromatic hydrocarbons in the heavy aromatic hydrocarbon-containing raw material is 50-100% by weight; 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.

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

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

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

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

1.

6. The method of claim 1, 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, and the dense phase fluidized bed reactor comprises the first reaction zone and the second reaction zone, and the first reaction zone is arranged 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 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 The bed linear velocity is 2-20 m / s.

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

10. The method of claim 1, wherein, a fraction cutting point of the liquid light fraction and the liquid heavy fraction is 120-160°C.

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

12. The method of claim 1, wherein, the method further comprises adding a fresh agent in the first reaction zone.

13. The method of claim 12, wherein, a 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.

14. The method of claim 11, wherein, the cracking reaction unit further comprises a regenerator; the method further comprises feeding the spent catalyst into the regenerator to perform regeneration, to obtain regenerated catalyst; and returning the regenerated catalyst to the first reaction zone through a regeneration inclined pipe; optionally, a fresh agent inlet is arranged on the regeneration inclined pipe.

15. The method of claim 1, wherein, the catalyst used in the first reaction zone and the second reaction zone is a cracking catalyst; and the cracking catalyst comprises a zeolite, an inorganic oxide and a clay. The content of the zeolite is 5-70 wt%, the content of the inorganic oxide is 1-95 wt%, and the content of the clay is 1-50 wt%, based on the total weight of the cracking catalyst, wherein the sum of the contents of the components in the catalyst is 100 wt%.

16. The method of claim 15, wherein, The zeolite of the cracking catalyst comprises a large-pore zeolite and optionally a medium-pore zeolite; the content of the large-pore zeolite is 40-100 wt% and the content of the medium-pore zeolite is 0-60 wt%, based on the total weight of the zeolite in the cracking catalyst; The medium-pore zeolite is selected from ZSM zeolite; 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.

17. The method of claim 16, wherein, The clay is polyhydrous kaolin.

18. The method of claim 16, wherein, The cracking catalyst contains rare earth elements.

19. The method of claim 18, wherein, The large-pore zeolite is Y-type zeolite modified by rare earth elements.

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

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