A method for producing light aromatics by catalytic conversion of heavy aromatics

Abstract

The present disclosure relates to a method for producing light aromatic hydrocarbons from heavy aromatic hydrocarbons, which comprises: subjecting a feedstock containing heavy aromatic hydrocarbons to a non-hydrogen catalytic cracking reaction in a dense phase fluidized bed reactor, so as to efficiently convert the heavy aromatic hydrocarbons into light aromatic hydrocarbons. On the one hand, the method can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatic hydrocarbon loss caused by the traditional hydrogenation process. On the other hand, the method can solve the problem of difficult utilization of low-value heavy aromatic hydrocarbons and realize efficient utilization of resources. Meanwhile, the method can further improve the yield of BTX products by using the dense phase fluidized bed reactor for catalytic cracking reaction. In addition, when the feedstock containing heavy aromatic hydrocarbons contains non-aromatic hydrocarbons, the method can also produce low-carbon olefins as by-products, further improving the utilization rate of the feedstock.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of petroleum chemical industry, in particular, to a method for producing light aromatic hydrocarbons by 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. Toluene and xylene can also be used as gasoline octane number additives. However, the production process of aromatic hydrocarbons is accompanied by the production of C9+ heavy aromatic hydrocarbons. At present, the production of C9+ heavy aromatic hydrocarbons is large, the value is low, and the utilization channels are limited, resulting in 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] Patent CN97106718.X discloses a heavy aromatic hydrocarbon hydrodealkylation and transalkylation process, which uses C10 or / and C11 aromatic hydrocarbons as raw materials, uses hydrogen-type mordenite loaded with bismuth and at least one metal or oxide selected from iron, cobalt, nickel or molybdenum as catalyst in a fixed bed reactor, and reacts at a temperature of 300-600 ℃ and a pressure of 1.5-4.0 MPa to generate C6-C9 aromatic hydrocarbons and C1-C4 paraffin hydrocarbons. This process has the characteristics of being particularly suitable for C10 or / and C10+ heavy aromatic hydrocarbon hydrodealkylation and transalkylation, and can be used in industrial production.

[0004] Patent CN200410066625.4 discloses a heavy aromatic hydrocarbon hydrodealkylation and transalkylation method, which mainly solves the problem of low heavy aromatic hydrocarbon content in the raw material and low utilization rate of heavy aromatic hydrocarbons in the prior art. The present invention uses C10 or / and C11 aromatic hydrocarbons as raw materials, uses large-pore zeolite loaded with bismuth and molybdenum metal or oxide as catalyst in a fixed bed reactor, and reacts at a temperature of 300-600 ℃ and a pressure of 1.0-4.0 MPa to generate mixed xylene. This technical solution solves the problem. This method has the characteristics of simple process, high mixed xylene yield and low hydrogen to hydrocarbon ratio, and can be used in the industrial production of heavy aromatic hydrocarbon production of mixed xylene.

[0005] From the above-mentioned patent disclosed technology, it can be seen that the existing heavy aromatic hydrocarbon lightening technology mostly adopts the method of fixed bed hydrodealkylation, but the hydrogenation process has problems such as high hydrogen consumption, harsh operating conditions, and aromatic hydrocarbon loss. SUMMARY

[0006] The present disclosure provides a method for producing light aromatic hydrocarbons by catalytic conversion of heavy aromatic hydrocarbons, to solve the problems of difficult utilization of heavy aromatic hydrocarbons and high hydrogen consumption, harsh operating conditions and aromatic hydrocarbon loss caused by hydrogen treatment in the prior art.

[0007] To achieve the above object, the present disclosure provides a method for producing light aromatic hydrocarbons by catalytic conversion of heavy aromatic hydrocarbons, which comprises: feeding a heavy aromatic hydrocarbon-containing raw material into a dense phase fluidized bed reactor to contact with a cracking catalyst to perform a catalytic cracking reaction to obtain a cracking reaction product; performing a first separation on the cracking reaction product to obtain other products, a light fraction and a heavy fraction; performing a second separation on the light fraction to obtain a benzene product, a toluene product and a xylene product; the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; the catalyst activity of the catalyst in the dense phase fluidized bed reactor is 60-99; part of the cracking catalyst is from added fresh agent.

[0008] 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.

[0009] Optionally, the reaction conditions of the catalytic cracking reaction include: the reaction temperature is 555-720℃, preferably 580-660℃; the agent / oil ratio is (1-100):1, preferably (5-30):1; and the catalyst activity is 60-90.

[0010] Optionally, the initial boiling point of the heavy aromatic hydrocarbon-containing raw material is 120-150℃, and the final boiling point is 200-250℃.

[0011] Optionally, the content of C9+ aromatic hydrocarbons in the heavy aromatic hydrocarbon-containing raw material is 20-100% by weight.

[0012] Optionally, 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 xylene column bottom C9+ heavy aromatic hydrocarbons.

[0013] Optionally, the method further comprises: separating the outlet material of the dense phase fluidized bed reactor through a settler to obtain spent catalyst and the cracking reaction product; feeding the spent catalyst into a regenerator to perform a regeneration treatment to obtain regenerated catalyst; and returning the regenerated catalyst to the dense phase fluidized bed reactor through a regeneration inclined pipe.

[0014] Optionally, a first fresh catalyst inlet is arranged on the regeneration inclined pipe, and the method further comprises: feeding a fresh agent into the regeneration inclined pipe through the first fresh catalyst inlet.

[0015] Optionally, a second fresh agent inlet and a raw material inlet are arranged at the lower part of the dense phase fluidized bed reactor, and the second fresh agent inlet is arranged upstream of the raw material inlet.

[0016] Optionally, the dense phase fluidized bed reactor is an upflow reactor or a downflow reactor.

[0017] Optionally, the cracking catalyst comprises a zeolite, an inorganic oxide and optionally 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.

[0018] Optionally, the zeolite comprises a large pore zeolite and optionally a medium pore zeolite; 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 is silicon dioxide and / or diatomic aluminum oxide; and the clay is kaolin and / or polyhydrous kaolin.

[0019] Optionally, the content of the large pore zeolite is 40-100 wt%, preferably 60-100 wt%, and the content of the medium pore zeolite is 0-60 wt%, preferably 0-25 wt%, based on the total weight of the zeolite.

[0020] Optionally, the cracking catalyst contains rare earth elements, and preferably, the large pore zeolite is Y zeolite modified by rare earth elements.

[0021] Optionally, part or all of the heavy fraction is returned to the dense phase fluidized bed reactor to participate in the catalytic cracking reaction.

[0022] Optionally, the ratio of the weight of the fresh agent to the total weight of the cracking catalyst is 0.2 or less.

[0023] According to the above technical solution, the raw material containing heavy aromatic hydrocarbons is subjected to non-hydrogen catalytic cracking reaction in the dense phase fluidized bed reactor, 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 traditional hydrogenation process; on the other hand, it can solve the problem of difficult utilization of low-value heavy aromatic hydrocarbons, and realize efficient utilization of resources. At the same time, the dense phase fluidized bed reactor is used for catalytic cracking reaction in the present disclosure, which can further improve the yield of BTX products. In addition, when the raw material containing heavy aromatic hydrocarbons contains non-aromatic hydrocarbons, the method of the present disclosure can also produce low-carbon olefins as by-products, further improving the utilization rate of raw materials.

[0024] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0025] 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:

[0026] Figure 1 is a schematic diagram of a method for producing light aromatics by catalytic conversion of heavy aromatics according to the present disclosure.

[0027] Figure 2 is a schematic diagram of a catalytic cracking reaction unit used in Comparative Example 1 of the present disclosure.

[0028] Figure 3 is a schematic diagram of a catalytic cracking reaction unit used in Comparative Example 1 of the present disclosure.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] 1 feedstock containing heavy aromatics; 2 catalytic cracking reaction unit; 3 cracking reaction product; 4 product separation device; 5 light fraction; 6 other product; 7 heavy fraction; 8 aromatics separation device; 9 benzene product; 10 toluene product; 11 xylene product; 12 dense phase fluidized bed reactor; 13 settler; 14 spent catalyst dipleg; 15 regenerator; 16 regenerated catalyst dipleg; 17 regenerated flue gas; 18 fresh catalyst; 19 fresh catalyst; 20 riser reactor. DETAILED DESCRIPTION

[0031] 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.

[0032] As shown in Figure 1 , the present disclosure provides a method for producing light aromatics by catalytic conversion of heavy aromatics, which comprises: feeding a feedstock containing heavy aromatics 1 into a dense phase fluidized bed reactor to contact with a cracking catalyst to perform a catalytic cracking reaction, to obtain a cracking reaction product 3; performing a first separation on the cracking reaction product 3 to obtain other products 6, a light fraction 5 and a heavy fraction 7; performing a second separation on the light fraction 5 to obtain a benzene product 9, a toluene product 10 and a xylene product 11; the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; the catalyst activity of the catalyst in the dense phase fluidized bed reactor is 60-99; part of the cracking catalyst is from added fresh catalyst.

[0033] By the technical scheme, the raw material containing heavy aromatic hydrocarbons is subjected to non-hydrogen catalytic cracking reaction in the dense phase fluidized bed reactor, so that the heavy aromatic hydrocarbons can be efficiently converted into light aromatic hydrocarbons. On the one hand, the problems of high hydrogen consumption, harsh operating conditions and loss of aromatic hydrocarbons caused by the traditional hydrogenation process 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. Meanwhile, the catalytic cracking reaction is carried out in the dense phase fluidized bed reactor, so that the yield of BTX products can be further improved. In addition, when the raw material containing heavy aromatic hydrocarbons contains non-aromatic hydrocarbons, the method of the present disclosure can also produce low-carbon olefins as by-products, further improving the utilization rate of raw materials.

[0034] In an embodiment, the initial boiling point of the raw material containing heavy aromatic hydrocarbons 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 raw material containing heavy aromatic hydrocarbons is 20-100% by weight, preferably 50-90% by weight, and further preferably 60-80% by weight.

[0035] In a preferred embodiment, the raw material containing heavy aromatic hydrocarbons 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.

[0036] In the above embodiment, the main component of the raw material containing heavy aromatic hydrocarbons is C9-C12 component. After the catalytic cracking reaction of the raw material, the components of other products obtained include H2-C4 gas components, diesel and heavy oil components, the main component of the obtained light fraction is C6-C8 component, and the main component of the obtained heavy fraction is C9-C12 component.

[0037] In a preferred embodiment, 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.

[0038] The cracking catalyst used in the cracking reaction 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. The content of the clay is 1-50% by weight, preferably 5-40% by weight.

[0039] The zeolite comprises large-pore zeolite and optional medium-pore zeolite; the medium-pore zeolite is preferably ZSM zeolite; the large-pore zeolite is preferably one or more of beta 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; the content of the medium-pore zeolite is 0-60% by weight, preferably 0-25% by weight.

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

[0041] 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 requirement is 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 by rare earth elements comprises: contacting NaY molecular sieve with a rare earth solution or a mixed solution of the rare earth solution and ammonium salt, performing filtration, water washing and drying, and then performing first calcination to obtain rare earth sodium Y molecular sieve; then, the rare earth sodium Y 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 5-6 by using ammonia water, and then filtered or not filtered, dried, and subjected to second calcination to obtain rare earth Y-type molecular sieve.

[0043] In an embodiment, the method for preparing the 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 by using an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, etc.), and the aging treatment is carried out at the pH value, wherein the temperature of the aging treatment is 20-80°C, and the time is 0-2h; then the inorganic oxide is added and stirred for 0.5-1.5h to form a colloid, and the zeolite is added 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, wherein the content of the large-pore zeolite in the 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; after continuous stirring, the microspherical catalyst is prepared by spray drying; then the microspherical catalyst is calcined at 400-600°C for 0.5-2h, washed with ammonium sulfate at 30-80°C until the content of sodium oxide is less than 0.25% by weight, then leached with deionized water and filtered, and then dried at 100-200°C to obtain the cracking catalyst; wherein the weight ratio of the ammonium sulfate to the microspherical catalyst to the water is (0.1-1) : 1 : (5-15).

[0045] As shown in Figure 2 The catalytic cracking reaction unit 2 used in the present disclosure includes a regenerator 15 and a dense-phase fluidized bed reactor 12 and a settler 13, wherein the dense-phase fluidized bed reactor 12 and the settler 13 are in communication with each other to enable the spent catalyst obtained by the reaction in the dense-phase fluidized bed reactor 12 and the cracking reaction product 3 to enter the settler 13 for separation. In this embodiment, the outlet material of the dense-phase fluidized bed reactor 12 is separated by the settler 13 to obtain the spent catalyst and the cracking reaction product 3; the spent catalyst enters the regenerator 15 through the spent catalyst inclined pipe 14 for regeneration treatment to obtain the regenerated catalyst; and the regenerated catalyst returns to the dense-phase fluidized bed reactor 12 through the regenerated catalyst inclined pipe 16.

[0046] The dense-phase fluidized bed reactor 12 and the settler 13 can be coaxially arranged or separately arranged according to the actual use, and preferably, the dense-phase fluidized bed reactor 12 and the settler 13 are coaxially arranged.

[0047] The reactor of the dense-phase fluidized bed reactor 12 can be an upflow reactor or a downflow reactor.

[0048] The settling tank 13 has a catalyst outlet at the bottom and a cracking reaction product outlet at the top. The dense phase fluidized bed reactor 12 has a pre-lifting medium inlet at the bottom and a second fresh agent inlet, a regenerated catalyst inlet, and a raw material inlet at the bottom. The regenerator 15 has an oxygen-containing gas inlet and a regenerated catalyst outlet at the bottom, a regenerated flue gas outlet at the top, and a catalyst outlet on the side wall of the regenerator 15. The pre-lifting medium inlet of the dense-phase fluidized bed reactor 12 is connected to a pre-lifting medium source, allowing the pre-lifting medium to enter the reactor and move the reactants. The regeneration catalyst inlet of the dense-phase fluidized bed reactor 12 is connected to the regeneration catalyst outlet of the regenerator 15 via a regeneration inclined tube 16, allowing the regeneration catalyst to enter the reactor 12 via the regeneration inclined tube 16 to participate in the cracking reaction. The unused catalyst outlet of the settling tank 13 is connected to the unused catalyst inlet of the regenerator 15 via an unused inclined tube 14, allowing the unused catalyst to enter the regenerator 15 for catalyst regeneration. The oxygen-containing gas inlet of the regenerator 15 is connected to an oxygen-containing gas source, and the regeneration flue gas outlet of the regenerator 15 is connected to the atmosphere, allowing oxygen-containing gas to enter the regenerator 15 to participate in catalyst regeneration and for the resulting regeneration flue gas to be discharged from the system. The feed inlet of the dense-phase fluidized bed reactor 12 is connected to a feed source containing heavy aromatics.

[0049] The second freshener inlet on the dense phase fluidized bed reactor 12 is located on the side wall upstream of the feed inlet; the regenerated catalyst inlet can be located on the side wall between the second freshener inlet and the feed inlet, or on the side wall upstream of the second freshener inlet.

[0050] The dense phase fluidized bed reactor 12 is also equipped with a steam inlet for connecting to a steam source so that steam can enter the dense phase fluidized bed reactor 12.

[0051] To further improve the separation effect, cyclone separators are provided at the top of both the settling tank 13 and the regenerator 15. The cyclone separators used in this disclosure are conventional choices in the art, and this application does not make any requirements. As for the number of stages of the cyclone separator, it can be flexibly selected according to actual production needs. Preferably, the number of stages of the cyclone separator is 2.

[0052] The settling chamber 13 is provided at the top of the settling chamber. The inlet of the settling chamber is connected to the reaction oil and gas outlet of the cyclone separator, and the outlet of the settling chamber is connected to the cracking reaction product outlet, so that the reaction oil and gas can be buffered in the settling chamber and then exit the system through the cracking reaction product outlet.

[0053] The oxygen-containing gas distributor can be provided inside the regenerator 15, and the inlet of the oxygen-containing gas distributor extends to the outside of the regenerator 15 to form an oxygen-containing gas inlet.

[0054] The first fresh agent inlet is provided on the regeneration inclined pipe 16 and is connected with a fresh agent source to allow the fresh agent to mix with the regenerated catalyst and then enter the dense phase fluidized bed reactor 12.

[0055] In one embodiment, the pre-lift medium used in the present disclosure is selected according to the conventional method in the art, and no special requirement is made in the present application. For example, the pre-lift medium can be steam and / or dry gas.

[0056] The flow regulating valves are further provided on the spent catalyst inclined pipe 14 and the regeneration inclined pipe 16 to flexibly regulate the flow of the material entering the regenerator 15 and / or the dense phase fluidized bed reactor 12.

[0057] In the above embodiment, the pre-lift medium enters from the bottom of the dense phase fluidized bed reactor 12, and the fresh agent 19, the regenerated catalyst and the raw material 1 containing heavy aromatic hydrocarbons are lifted to the dense phase fluidized bed reactor 12 to perform catalytic cracking reaction, thereby obtaining a mixture containing spent catalyst and cracking reaction product 3. The mixture enters the settler 13 to be separated, and most of the spent catalyst in the mixture runs downward under the action of gravity, and the cracking reaction product 3 and a small part of the spent catalyst in the mixture run upward and enter the cyclone separator to be separated, so that the small part of the spent catalyst returns to the settler 13, and the cracking reaction product 3 is discharged from the settler 13 through the gas collecting chamber. The spent catalyst enters the regenerator 15 through the spent catalyst inclined pipe 14 and is subjected to regeneration treatment under the action of the oxygen-containing gas to obtain the regenerated catalyst and the regeneration flue gas 17, and the regeneration flue gas 17 is discharged to the atmosphere. The regenerated catalyst and the fresh agent 18 return to the dense phase fluidized bed reactor 12 through the regeneration inclined pipe 16.

[0058] In one embodiment, the catalyst used in the dense phase fluidized bed reactor 12 includes the regenerated catalyst and / or the fresh agent, and 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 further preferably 0.05-0.12. The fresh agent in the present disclosure refers to the unused cracking catalyst, the spent catalyst refers to the cracking catalyst after the catalytic cracking reaction, and the regenerated catalyst refers to the spent catalyst after the regeneration treatment. The spent catalyst is obtained after the cracking catalyst is subjected to the cracking reaction, and therefore, the spent catalyst contains part of carbon.

[0059] In one embodiment, the reaction conditions of the catalytic cracking reaction include: a reaction temperature of 555-720℃, a reaction time of 1-20 seconds, a reaction pressure of 130-450 kPa, and a catalyst to oil ratio of (1-100):1; preferred reaction conditions include: a reaction temperature of 580-660℃, a reaction time of 3-15 seconds, a reaction pressure of 150-400 kPa, and a catalyst to oil ratio of (5-30):1; further preferred reaction conditions include: a reaction temperature of 600-650℃, a reaction time of 3.5-10 seconds, a reaction pressure of 160-300 kPa, and a catalyst to oil ratio of (15-25):1.

[0060] In one embodiment, the catalyst activity of the present disclosure refers to the micro-reactor activity index determined by the method of NB / SH / T 0952-2017.

[0061] In one preferred embodiment, in order to further improve the reaction activity of the catalytic cracking reaction, the catalyst activity of the catalyst in the dense phase fluidized bed reactor 12 needs to be optimized, specifically, the catalyst activity of the catalyst in the dense phase fluidized bed reactor 12 is preferably 60-90.

[0062] In one embodiment, the method further comprises returning part or all of the heavy fraction to the dense phase fluidized bed reactor for participating in the catalytic cracking reaction, wherein the ratio of the weight of the heavy fraction returned to the catalytic cracking reaction unit 2 to the total weight of the heavy fraction needs to be flexibly selected according to the actual production needs, and the present application does not make any special requirements. In this embodiment, the back-refining of the heavy fraction can make the C9+ components in the heavy fraction crack into light aromatic components and other components, further improving the yield of BTX and reducing the output of heavy fraction.

[0063] In one embodiment, the product 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 they can separate the cracking reaction products into other products, the light fraction and the heavy fraction. Among them, the initial boiling point of the light fraction is 20-40℃; the fraction cutting point of the light fraction and the heavy fraction is 120-160℃.

[0064] In one embodiment, the device and method for aromatic separation treatment are conventional choices in the art, and the present application does not make any requirements, as long as they can separate the light fraction 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 back-refining position can be the same as the raw material containing heavy aromatic hydrocarbons.

[0065] The following examples will further illustrate the present application without, however, restricting it. The heavy aromatic hydrocarbon-containing feedstocks used in the examples and comparative examples are Feedstock A and Feedstock B, wherein Feedstock A is catalytically cracked gasoline heavy aromatic hydrocarbons and Feedstock B is reforming heavy aromatic hydrocarbons. The properties of Feedstock A and Feedstock B are shown in Table 1.

[0066] Table 1 Properties of Feedstock A and Feedstock B

[0067]

[0068] Preparation Example 1

[0069] The method for preparing the rare earth Y-type molecular sieve (REY) comprises: 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 slurrying the rare earth sodium Y-type 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 6 with ammonia water, and after filtration or without filtration, drying and performing a second calcination treatment to obtain the rare earth Y-type molecular sieve (REY).

[0070] The method for preparing the cracking catalyst C1 comprises: mixing an aluminum sol with kaolin, and using deionized water to prepare a slurry with a solid content of 40% by weight, stirring uniformly, adjusting the pH value of the slurry to 4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), maintaining the pH value, adding aluminum sol at 60°C after standing and aging for 1 hour, stirring for 1 hour to form a colloid, adding a rare earth Y-type molecular sieve (REY) to form a catalyst slurry (with a solid content of 35% by weight), wherein the weight of REY: the weight of kaolin: the weight of aluminum sol = 50:34:16, continuing to stir and then spray drying to prepare a microspherical catalyst. Then the microspherical catalyst is calcined at 500°C for 1 hour, washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of the microspherical catalyst: the weight of water = 0.5:1:10) until the sodium oxide content is less than 0.25% by weight, then leaching with deionized water and filtering, and then drying at 110°C to obtain the cracking catalyst C1.

[0071] Preparation Example 2

[0072] The method for preparing the rare earth Y-type molecular sieve (REY) is the same as that in Preparation Example 1;

[0073] The method for preparing the cracking catalyst C2 includes: mixing alumina sol with kaolin and preparing it into a slurry with a solid content of 40% by weight using decationized water, stirring evenly, adjusting the pH of the slurry to 4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), maintaining this pH value, allowing it to stand and age at 60°C for 1 hour, adding alumina sol, stirring for 1 hour to form a colloid, adding ZSM-5 and REY to form a catalyst slurry (with a solid content of 35% by weight), wherein the weight of ZSM-5 molecular sieve: weight of REY: weight of kaolin: weight of alumina sol = 15:35:34:16, continuing to stir and then spray drying to prepare microsphere catalyst. The microsphere catalyst was then calcined at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: weight of microsphere catalyst: weight of water = 0.5:1:10) until the sodium oxide content was less than 0.25% by weight. After that, it was rinsed with deionized water and filtered, and then dried at 110°C to obtain the cracking catalyst C2.

[0074] Test Example 1

[0075] The micro-reaction activity index was determined according to the method for determining the micro-reaction activity index at 460℃ in NB / SH / T 0952-2017, and the obtained micro-reaction activity index is the catalyst activity of the cracking catalyst.

[0076] Example 1

[0077] use Figure 1 The system and Figure 2 Methods for the catalytic conversion of heavy aromatics to light aromatics in cracking reaction unit 2 include:

[0078] Fresh catalyst 19, regenerated catalyst, and feedstock 1 containing heavy aromatics are introduced into a dense-phase fluidized bed reactor 12 under the action of a pre-lifting medium (steam) for catalytic cracking reaction, resulting in a mixture containing recycled catalyst and cracking product 3. The reaction conditions of the dense-phase fluidized bed reactor 12 are shown in Table 2, and the weight ratio of fresh catalyst to the total weight of catalyst in the dense-phase fluidized bed reactor 12 is 0.02:1. The mixture is then introduced into a settling tank 13 for separation. Most of the recycled catalyst in the mixture moves downward under the action of gravity, while the cracking product 3 and a small portion of the recycled catalyst move upward and enter a cyclone separator for separation, so that a small portion of the recycled catalyst returns to the settling tank 13. The cracking product 3 exits the settling tank 13 through the gas collecting chamber. The catalyst to be regenerated is introduced into the regenerator 15 through the regenerated inclined tube 14 and regenerated under the action of oxygen-containing gas to obtain regenerated catalyst and regenerated flue gas 17; the regenerated flue gas 17 is discharged from the system and the regenerated catalyst and fresh catalyst 18 are returned to the dense phase fluidized bed reactor 12 through the regenerated inclined tube 16.

[0079] The cracking reaction product 3 is subjected to a first separation by means of a product separation device 4, to obtain other products 6, a light fraction 5 and a heavy fraction 7; the light fraction 5 is subjected to a second separation by means of an aromatic separation device 8, to obtain a benzene product 9, a toluene product 10 and a xylene product 11; the other products are subjected to further separation, to obtain dry gas, ethylene, liquefied petroleum gas, propylene and gasoline; the initial boiling point of the light fraction is 30°C, and the fraction cut point of the light fraction and the heavy fraction is 145°C. The reaction conditions and the properties of the products are shown in Table 2.

[0080] Example 2

[0081] The method for the catalytic conversion of heavy aromatics to produce light aromatics is the same as in Example 1, except that the reaction temperature of the catalytic cracking reaction is 600°C. The reaction conditions and the properties of the products are shown in Table 2.

[0082] Example 3

[0083] The method for the catalytic conversion of heavy aromatics to produce light aromatics is the same as in Example 1, except that the catalyst to oil ratio of the catalytic cracking reaction is 15:1. The reaction conditions and the properties of the products are shown in Table 2.

[0084] Example 4

[0085] The method for the catalytic conversion of heavy aromatics to produce light aromatics is the same as in Example 1, except that an equal weight of raw material B is used as the raw material containing heavy aromatics. The reaction conditions and the properties of the products are shown in Table 2.

[0086] Example 5

[0087] The method for the catalytic conversion of heavy aromatics to produce light aromatics is the same as in Example 1, except that an equal weight of cracking catalyst C2 is used as the cracking catalyst. The reaction conditions and the properties of the products are shown in Table 2.

[0088] Example 6

[0089] The method for the catalytic conversion of heavy aromatics to produce light aromatics is the same as in Example 1, except that the bed density of the dense phase fluidized bed reactor 12 is 250 kg / m 3 . The reaction conditions and the properties of the products are shown in Table 2.

[0090] Example 7

[0091] The method for the catalytic conversion of heavy aromatics to produce light aromatics is the same as in Example 1, except that the heavy fraction is all mixed with the raw material A and then returned to the dense phase fluidized bed reactor 12. The reaction conditions and the properties of the products are shown in Table 2.

[0092] Example 8

[0093] The method for producing light aromatic hydrocarbons by catalytic conversion of heavy aromatic hydrocarbons is the same as that in Example 1, except that the reaction conditions of the catalytic cracking reaction are different. The reaction conditions and the properties of the products are shown in Table 2.

[0094] Comparative Example 1

[0095] The system for producing light aromatic hydrocarbons by catalytic conversion of heavy aromatic hydrocarbons is the same as that in Example 1, except that the cracking reactor used is Figure 3 , i.e., the dense phase fluidized bed reactor 12 is replaced by a riser reactor 20, wherein the bed density of the riser reactor 20 is 70 kg / m 3 . The reaction conditions and the properties of the products are shown in Table 2.

[0096] Comparative Example 2

[0097] The method for producing light aromatic hydrocarbons by catalytic conversion of heavy aromatic hydrocarbons is the same as that in Example 1, except that the cracking catalyst C1 is replaced by an equal weight of a CDOS catalytic cracking catalyst, wherein the CDOS catalytic cracking catalyst is purchased from Changling Catalyst Company. The reaction conditions and the properties of the products are shown in Table 2.

[0098] Comparative Example 3

[0099] The method for producing light aromatic hydrocarbons by catalytic conversion of heavy aromatic hydrocarbons is the same as that in Example 1, except that no fresh agent is added when the catalytic cracking reaction is performed.

[0100] Table 2 Reaction conditions and properties of products

[0101]

[0102]

[0103] As shown in Table 2, by comparing the data in Examples 1-8 and Comparative Examples 1-3, it can be seen that, by using the technical solution of the present disclosure, on the one hand, the problems of high hydrogen consumption, harsh operating conditions and loss of aromatic hydrocarbons caused by the traditional hydrogenation process can be avoided; on the other hand, the catalytic cracking reaction is performed in a dense phase fluidized bed reactor, which can greatly improve the yield of BTX. By comparing the data in Examples 1, 2 and 3, it can be seen that, by performing non-hydrogen catalytic conversion of the heavy aromatic hydrocarbon-containing raw material at a cracking reaction temperature of 600-650°C and an agent to oil ratio of (15-25): 1, a higher yield of BTX can be obtained; by comparing the data in Examples 1, 5 and Comparative Example 2, it can be seen that, when the catalyst activity of the catalyst in the dense phase fluidized bed reactor satisfies 60-99, a higher yield of BTX can be obtained; by comparing the data in Examples 1, 6 and Comparative Example 1, it can be seen that, when the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3, the bed density of the dense phase fluidized bed reactor is 300-500 kg / m 3 According to the comparison of the data in Example 1 and Example 7, it can be known that the yield of BTX can be further improved by recycling the heavy fraction back to the cracking reaction unit; according to the comparison of the data in Example 1 and Comparative Example 3, it can be known that the yield of BTX can be higher by adding fresh agent during the cracking reaction.

[0104] The preferred embodiments of the present disclosure are described in detail above in combination with the 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.

[0105] 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.

[0106] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed by the present disclosure.

Claims

1. A process for the catalytic conversion of heavy aromatic hydrocarbons to produce light aromatic hydrocarbons, characterized in that, The method comprises: feeding a heavy aromatic hydrocarbon-containing raw material into a dense phase fluidized bed reactor to contact with a cracking catalyst to perform a non-hydrogen catalytic cracking reaction to obtain a cracking reaction product; performing a first separation on the cracking reaction product to obtain other products, a light fraction and a heavy fraction; performing a second separation on the light fraction to obtain benzene product, toluene product and xylene product; the micro-reaction activity index of the catalyst in the dense phase fluidized bed reactor is 60-99; part of the cracking catalyst is from added fresh agent; 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 reaction conditions of the non-hydrogen catalytic cracking reaction include: the reaction temperature is 580-660 ℃; the agent / oil ratio is (10-30):1; the content of C9+ aromatic hydrocarbons in the heavy aromatic hydrocarbon-containing raw material is 20-100% by weight; part or all of the heavy fraction is returned to the dense phase fluidized bed reactor to participate in the non-hydrogen catalytic cracking reaction.

2. The method of claim 1, wherein, The micro-reaction activity index of the non-hydrogen catalytic cracking reaction is 60-90.

3. The method of claim 1, wherein, The initial boiling point of the heavy aromatic hydrocarbon-containing raw material is 120-150 ℃, and the final boiling point is 200-250 ℃.

4. The method of claim 1, wherein, 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 xylene column bottom C9+ heavy aromatic hydrocarbons.

5. The method of claim 1, wherein, The method further comprises separating the outlet material of the dense phase fluidized bed reactor through a settler to obtain spent catalyst and the cracking reaction product; feeding the spent catalyst into a regenerator to perform regeneration treatment to obtain regenerated catalyst; feeding the regenerated catalyst into the dense phase fluidized bed reactor through a regenerated catalyst inclined pipe.

6. The method of claim 5, wherein, A first fresh catalyst inlet is arranged on the regenerated catalyst inclined pipe, and the method further comprises feeding fresh agent into the regenerated catalyst inclined pipe through the first fresh catalyst inlet.

7. The method of claim 5, wherein, A second fresh agent inlet and a raw material inlet are arranged in the lower part of the dense phase fluidized bed reactor, and the second fresh agent inlet is arranged upstream of the raw material inlet.

8. The method of claim 5, wherein, The dense phase fluidized bed reactor is an upflow reactor or a downflow reactor.

9. The method of claim 1, wherein, The cracking catalyst comprises zeolite, inorganic oxide and 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; and the sum of the contents of the components in the cracking catalyst is 100% by weight.

10. The method of claim 9, wherein, The zeolite comprises large-pore zeolite and optional medium-pore zeolite; the medium-pore zeolite is selected from ZSM zeolite; and the large-pore zeolite is selected from β-type zeolite and / or Y-type zeolite. The inorganic oxide is silicon dioxide and / or di-aluminum trioxide. The clay is kaolin.

11. The method of claim 10, wherein, The clay is hydrous kaolin.

12. The method of claim 10, wherein, 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.

13. The method of claim 12, wherein, The content of the large-pore zeolite is 60-100% by weight, and the content of the medium-pore zeolite is 0-25% by weight, based on the total weight of the zeolite.

14. The method of claim 12, wherein, The cracking catalyst contains rare earth elements.

15. The method of claim 14, wherein, The large-pore zeolite is Y-type zeolite modified by rare earth elements.

16. The method of claim 1, wherein, The ratio of the weight of the fresh agent to the total weight of the cracking catalyst is 0.2 or less. The ratio of the weight of the fresh agent to the total weight of the cracking catalyst is 0.2 or less.

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