Method for producing light aromatic compounds

Abstract

A method for producing light aromatic compounds includes: i) contacting a feedstock containing heavy aromatic compounds with a catalyst in a fluidized reactor for aromatic compound downsizing in the presence of hydrogen to obtain a product rich in C6-C8 light aromatic compounds and spent catalyst, wherein the heavy aromatic compounds are one or more selected from C9+ aromatic compounds; ii) separating the obtained product rich in C6-C8 light aromatic compounds to obtain hydrogen, non-aromatic components, C6-C8 light aromatic compounds, and C9+ aromatic components; and iii) recycling at least a portion of the C9+ aromatic components to the fluidized reactor. This method has strong adaptability to feedstocks and high flexibility in operation, allowing for long-term stable operation. This method can produce high-value light aromatic compounds from heavy aromatic compounds that are difficult to process and utilize.

Description

Detailed Description of the Invention

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Patent Application No. 201911047207.3, entitled "METHING FOR PRODUCING LIGHT AROMATIC COMPOUNDS," filed on October 30, 2019, the entire contents of which are incorporated herein by reference.

[0002] [Technical field] The present application relates to a method for producing light aromatic compounds, and more particularly to a method for producing light aromatic compounds from a feedstock containing heavy aromatic compounds.

[0003] [Background technology] BTX (benzene, toluene and xylene) is an important petrochemical basic product and an important starting material for various chemical products such as synthetic rubber, synthetic fiber and synthetic resin, and toluene and xylene can also be used as additives to improve the octane number of gasoline. With the continuous development of terylene, polyester and PTA industries in China, the growth of the global aromatic hydrocarbon industrial chain is concentrated in the Northeast Asian region, and the demand for BTX is continuously increasing. However, the aromatics production process involves the production of C9+ heavy aromatic compounds. The current production of C9+ heavy aromatic compounds, which have low value and limited utilization, is very large, which is a source of resource waste. Therefore, there is no doubt that the conversion of C9+ heavy aromatic compounds to BTX in the catalytic cracking of gasoline with the simultaneous production of more light olefins is an effective way to fully utilize resources and improve the quality and efficiency of enterprises.

[0004] CN1217370A discloses a method for hydrodealkylation and transalkylation of heavy aromatic compounds, which uses C10 and / or C11 aromatic compounds as raw materials, and hydrogen-type mordenite supported with at least one metal selected from iron, cobalt, nickel, or molybdenum or their oxides and bismuth as catalyst, and carries out the reaction in a fixed-bed reactor at a temperature of 300-600°C and a pressure of 1.5-4.0MPa to produce C6-C9 aromatic compounds and C1-C4 paraffins. This method is particularly suitable for hydrodealkylation and transalkylation of C10+ heavy aromatic compounds, and can be used for industrial production.

[0005] CN101362669A discloses a catalytic conversion method for preparing ethylene, propylene and aromatic compounds, which is characterized by including the steps of contacting hydrocarbon feedstocks with different cracking behaviors with catalytic cracking catalysts to carry out cracking reactions in a fluidized bed reactor, separating the spent catalyst from the reacted petroleum gas, recycling the spent catalyst to the reactor after regeneration, and separating the reacted petroleum gas to obtain the target products, i.e., light olefins and aromatic compounds, in which the 160-260°C fraction is recycled to the catalytic cracking step for reuse, and ethane, propane and butane are subjected to steam cracking to further produce ethylene and propylene. This method allows the maximum production of light olefins such as ethylene and propylene from heavy feedstocks with the simultaneous production of aromatic compounds such as toluene and xylene, whereby the yields of ethylene and propylene can both exceed 20% by weight.

[0006] CN1752058A discloses a method for hydrodealkylation and transalkylation of heavy aromatic compounds, which is mainly aimed at solving the problems in the prior art of low allowable content of heavy aromatic compounds in the feedstock and low utilization rate of heavy aromatic compounds. This method solves the above problems by using C10 and / or C11 aromatic compounds as the feedstock and using macroporous zeolite supported with metallic bismuth and molybdenum or their oxides as the catalyst to carry out the reaction in a fixed-bed reactor at a temperature of 300-600°C and a pressure of 1.0-4.0 MPa to produce mixed xylenes. This method has the characteristics of simple process, high yield of mixed xylenes, low hydrogen-hydrocarbon ratio, etc., and can be used to industrially produce mixed xylenes from heavy aromatic compounds.

[0007] CN1906272A discloses a separate catalytic hydrodealkylation process for hydrocarbons including C8-C13 alkylaromatic compounds, possibly mixed with C4-C9 aliphatic and cycloaliphatic products. The process involves continuously treating a hydrocarbon composition in the presence of hydrogen at a temperature of 400-650°C, a pressure of 2-4 MPa, and a H2 / feedstock molar ratio of 3-6 with a catalyst made of ZSM-5 zeolite and modified with at least one metal selected from group IIB, VIB, and VIII metals. The process can provide an overall yield of benzene and toluene of up to 75%.

[0008] CN101348733A discloses a process for producing light aromatic compounds and light paraffins from a hydrocarbon feedstock. The process includes the steps of reacting the hydrocarbon feedstock at a boiling point of 30-250°C in the presence of a zeolite catalyst containing Pt or Pd, subjecting the heavy aromatic compounds in the hydrocarbon feedstock to hydrodealkylation and transalkylation reactions with the light aromatic compounds, subjecting the light aromatic compounds to an isomerization reaction to convert them into components rich in BTX (B is benzene, T is toluene, and X is xylene) light aromatic compounds, subjecting the non-aromatic compounds to a hydrocracking reaction to produce light paraffins, separating the liquid product into benzene, toluene, xylene, and C9+ aromatic compounds according to the difference in boiling point in a distillation column, and separating the light paraffins from the gas product. This process overcomes the problems encountered in traditional hydrocarbon feedstock separation processes, such as the need for solvent extraction, process complexity, high cost, and low value of the heavy aromatics and non-aromatic compounds obtained after separation.

[0009] CN101734986A discloses a process for producing more benzene and xylenes by hydrocracking cracked gasoline. The process includes reacting C7+ cracked gasoline feedstock in the presence of a catalyst, subjecting heavy aromatic compounds to hydrodealkylation and to transalkylation reaction with light aromatic compounds, subjecting light aromatic compounds to isomerization reaction to convert them into components rich in BTX light aromatic compounds, separating the liquid product into benzene, toluene, xylene and C9+ fraction according to the difference in boiling point, thereby allowing toluene and C9+ fraction to be recycled for further processing, and separating light paraffins from the gas product. This process solves the problems encountered in the traditional process of treating cracked gasoline, namely, only BTX (B is benzene, T is toluene, and X is xylene) aromatic compounds are separated, the light aromatic products contain a large amount of toluene, and the separated heavy aromatic compounds and non-aromatic compounds have low value.

[0010] CN103930524A discloses a process for converting biomass to products, which includes contacting biomass with hydrogen in the presence of a hydropyrolysis catalyst in a fluidized bed reactor under hydropyrolysis conditions; and removing products and carbon from the reactor, where the carbon and catalyst are separated according to differences in settling velocity.

[0011] The technologies disclosed in the above patent applications show that most of the existing heavy aromatic compound lightening technologies adopt fixed-bed hydrodealkylation processes, and have disadvantages such as harsh reaction conditions, difficulties in regenerating and recycling the catalyst, and strict requirements for the initial activity of the catalyst.

[0012] Summary of the Invention The objective of the present application is to provide a method for producing light aromatic compounds, which can efficiently convert C9+ heavy aromatic compounds into C6-C8 light aromatic compounds and enable stable operation for a long period of time.

[0013] In order to achieve the above object, the present application provides a method for producing light aromatic compounds, comprising the steps of: i) contacting a feedstock containing heavy aromatic compounds with a catalyst in a fluidized reactor for an aromatic compound lightening reaction in the presence of hydrogen to obtain a product enriched in C6-C8 light aromatic compounds and a spent catalyst, wherein the heavy aromatic compounds are one or more selected from C9+ aromatic compounds; ii) separating the resulting C6-C8 light aromatics-enriched product to obtain hydrogen, non-aromatic components, C6-C8 light aromatics and C9+ aromatic components; and iii) recycling at least a portion of the C9+ aromatics to the fluidization reactor; where: The reaction conditions for step i) are: a temperature of about 250 to 750°C, a pressure of about 0 to 6 MPa, and a reaction time of about 0.1 to 120 h. -1 and a hydrogen / hydrocarbon molar ratio of about 1 to 15; The catalyst used in step i) comprises a support and an active metal component supported on the support in an amount of about 0.01 to 50 wt. % based on the total weight of the catalyst; wherein the support comprises, based on the total weight of the support, about 1 to about 80 wt. % of a zeolite, about 5 to about 99 wt. % of an inorganic oxide, and about 0 to about 70 wt. % of a clay, wherein the zeolite comprises a mesoporous zeolite, a macroporous zeolite, or a combination thereof; the inorganic oxide is one or more selected from silica, alumina, zirconia, titania, and amorphous silica-alumina; the clay is one or more selected from kaolin, montmorillonite, diatomaceous earth, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite, and rectorite; The active metal component is one or more selected from rare earth metals and transition metals.

[0014] The process according to the present application uses a fluidized reaction system to carry out hydrodealkylation and transalkylation processing on feedstocks containing C9+ heavy aromatic compounds, which has strong feedstock compatibility and high flexibility in operation, allows long-term stable operation, and can convert the difficult-to-process and difficult-to-utilize heavy aromatic compounds into high-value light aromatic compounds.

[0015] Further features and advantages of the present application are described in detail in the detailed description that follows.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS The drawings forming part of this specification are provided to aid in the understanding of the application and should not be considered limiting. The application can be read with reference to the drawings in combination with the following detailed description. In the drawings: FIG. 1 shows a process flow diagram of one embodiment of the method according to the present application; FIG. 2 shows a schematic diagram of a regenerator according to one embodiment of the method according to the present application.

[0017] Detailed Description of the Invention The present application will now be described in more detail with reference to specific embodiments thereof and the accompanying drawings. It should be noted that the specific embodiments of the present application are provided for illustrative purposes only and are not intended to be limiting in any way.

[0018] Any specific numerical value, including the end point of a numerical range described in the context of this application, should be interpreted as not being limited to that exact value, but also encompassing all values ​​close to said exact value, such as any possible value within ±5% of the exact value. Furthermore, for any numerical range described herein, any combination can be made between the end points of the range, between each end point in the range and any specific value, or between any two specific values ​​in the range to provide one or more new numerical ranges. In this case, said new numerical range should also be considered to be specifically described in this application.

[0019] Unless otherwise stated, terms used herein have the same meaning as commonly understood by one of ordinary skill in the art, and where terms are defined herein and their definitions differ from the normal understanding in the art, the definitions provided herein shall control.

[0020] In this application, the term "C9+ aromatic compound" is a generic term for aromatic compounds having 9 or more carbon atoms and is intended to include any existing aromatic compound having 9 or more carbon atoms. Similarly, in this application, the term "C10+ aromatic compound" is a generic term for aromatic compounds having 10 or more carbon atoms and is intended to include any existing aromatic compound having 10 or more carbon atoms.

[0021] In this application, the term "C6-C8 light aromatic compound" is a general term for aromatic compounds having 6 to 8 carbon atoms, and is intended to include any existing aromatic compound having 6, 7, or 8 carbon atoms.

[0022] In this application, the terms "fluidized reactor" and "fluidized bed reactor" are used interchangeably and refer to a reactor in which solid catalyst particles are suspended in a fluidic suspension by a gaseous process stream to carry out a gas-solid reaction process, including various forms of dilute phase conveying beds, dense phase conveying beds, bubbling fluidized beds, turbulent fluidized beds, fast fluidized beds, etc.

[0023] In the context of this application, in addition to what is explicitly stated, all unmentioned matters shall be regarded as the same as known in the art without modification.Furthermore, any of the embodiments described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or concepts thus obtained shall be regarded as part of the original disclosure or original description of this application, and shall not be regarded as new matters not disclosed or anticipated herein, unless it is obvious to those skilled in the art that such combination is obviously unreasonable.

[0024] All patent and non-patent literature, including but not limited to textbooks and journal articles, cited herein are hereby incorporated by reference in their entirety.

[0025] The present application provides a method for producing light aromatic compounds, comprising the steps of: i) contacting a feed containing heavy aromatic compounds with a catalyst in a fluidized reactor for reaction in the presence of hydrogen under conditions effective to convert the heavy aromatic compounds to light aromatic compounds to obtain a product enriched in C6 to C8 light aromatic compounds and spent catalyst, wherein the heavy aromatic compounds are one or more selected from C9+ aromatic compounds; ii) separating the resulting C6-C8 light aromatics-enriched product to obtain hydrogen, non-aromatic components, C6-C8 light aromatics and C9+ aromatic components; and iii) recycling at least a portion of said C9+ aromatics to the fluidization reactor.

[0026] Since the method according to the present application uses a fluidized reaction system, the raw material and the catalyst can be reacted continuously in the fluidized reactor, and therefore has strong raw material compatibility and high flexibility in operation, enabling long-term stable operation.

[0027] The method of the present application can eliminate the contradiction between the supply and demand of light aromatic compounds, solve the problem of producing large amounts of heavy aromatic compounds with low value and difficulty in utilization encountered in various oil refining processes and chemical engineering processes, and improve the economic and social benefits of the petrochemical industry.

[0028] According to the present application, in step i), the C9+ heavy aromatic compounds may undergo dealkylation and transalkylation reactions to obtain C6-C8 light aromatic compounds. The reaction conditions in step i) may vary within a wide range. In a preferred embodiment, the reaction temperature may be about 250-750°C, preferably about 320-600°C, more preferably about 360-550°C, such as about 380-500°C or about 400-480°C; the pressure (gauge pressure) may be about 0-6 MPa, preferably about 0-4.5 MPa, more preferably about 1-3 MPa; the weight hourly space velocity (e.g., for a dense phase fluidized bed) may be about 0.1-120 h -1 , preferably about 1 to about 80 hours -1 , more preferably about 1.5 to about 50 hours -1 For example, about 1 to about 30 hours -1 , about 1.5~about 15h -1 , about 1~about 10h -1 Or about 1.5 to 10 hours -1 or the reaction time (e.g., for a transporting bed reactor) may be from about 0.1 to about 40 seconds, preferably from about 0.5 to about 30 seconds, more preferably from about 1 to about 15 seconds, such as from about 0.2 to about 20 seconds or from about 0.6 to about 10 seconds; and the hydrogen / hydrocarbon molar ratio may be from about 1 to about 15, preferably from about 2 to about 10, more preferably from about 3 to about 8, such as from about 3 to about 5.

[0029] According to the present application, after the petroleum gas obtained from the fluidized reactor is separated from the spent catalyst, a reaction product rich in C6-C8 light aromatic compounds is obtained, and the reaction product can be further separated to obtain hydrogen, non-aromatic components, C6-C8 light aromatic compounds and C9+ aromatic components, said separation can be carried out by any method conventionally used in the art. In a preferred embodiment, the product rich in C6-C8 light aromatic compounds can be subjected to gas-liquid separation to obtain hydrogen and liquid products, and then the liquid products can be subjected to aromatic compound extraction to obtain non-aromatic components and aromatic components. Preferably, the separated hydrogen can be recycled to the fluidized reactor of step i).

[0030] In a further preferred embodiment, the aromatic components may be subjected to a first fractionation to separate C6-C8 light aromatic compounds, resulting in C6-C8 light aromatic compounds and C9+ aromatic components; wherein at least a portion of the C9+ aromatic components may be recycled to the fluidized reactor for further reaction, and particularly preferably, the entire C9+ aromatic components may be recycled to the fluidized reactor for further reaction. The apparatus and conditions for carrying out the first fractionation may be those conventionally used in the art, for example, the apparatus for the first fractionation may be a fractionation tower or a flash drum, and the conditions for the first fractionation may be those conventionally used in the art.

[0031] In another further preferred embodiment, the C9 aromatics and the C10+ aromatics of the C9+ aromatics may be separated, for example by performing a second fractionation on the aromatics to produce C6-C8 light aromatics, C9 aromatics, and C10+ aromatics. The apparatus and conditions for performing the second fractionation may be those conventionally used in the art, for example the apparatus for the second fractionation may be a fractionation column, and the conditions for the second fractionation may be those conventionally used in the art.

[0032] According to the present application, the C6-C8 light aromatic compounds separated from the product can be sent out of the system as one product or can be further separated by another method to obtain benzene, toluene and xylene. The separation method can be conventionally used in the art, for example, the C6-C8 light aromatic compounds can be subjected to a third fractionation to produce benzene, toluene and xylene. The apparatus and conditions for carrying out the third fractionation can be conventionally used in the art, for example, the apparatus for the third fractionation can be a fractionation column, and the conditions for the third fractionation can be conventionally used in the art.

[0033] In a preferred embodiment where the aromatics are subjected to a second fractionation, the C9 aromatics separated by the second fractionation may be subjected to transalkylation together with toluene to produce more xylenes. In yet a further preferred embodiment, a mixed recycle feed may be obtained by mixing the C9 aromatics with toluene separated from the C6-C8 light aromatics as shown in FIG. 1, and the mixed recycle feed may be recycled to the fluidized reactor. The toluene and C9 aromatics in the mixed recycle feed may undergo toluene disproportionation and transalkylation together with the C9 aromatics in the fluidized reactor to produce xylenes, resulting in an increase in the xylene content in the light aromatic product. Also, in this embodiment, the C10+ aromatics may be mixed with a feed containing heavy aromatics before being recycled to the fluidized reactor for reaction.

[0034] More preferably, in order to increase the reaction conversion in the fluidized reactor, in a particularly preferred embodiment, the C10+ aromatics and the mixed recycle feed may be continuously fed into the fluidized reactor along the flow direction of the feed in the fluidized reactor, i.e., the C10+ aromatics may be fed at an upstream position of the fluidized reactor, and the mixed recycle feed containing toluene and C9 aromatics may be recycled to the fluidized reactor downstream of the inlet for the heavy aromatic feed, as shown in Figure 1. In the reactor shown in Figure 1, the fluidized reactor is a riser reactor, and the inlet position of the mixed recycle feed is higher than the inlet position of the feed containing heavy aromatics; in an embodiment where the fluidized reactor is a downer reactor, the inlet position of the mixed recycle feed is lower than the inlet position of the feed containing heavy aromatics.

[0035] According to the present application, the separation of the spent catalyst from the oil gas can be carried out by a cyclone known to those skilled in the art or by a filter known to those skilled in the art. The oil gas obtained after the separation of the spent catalyst, i.e., the reaction product rich in C6-C8 light aromatic compounds, can be subjected to a subsequent separation system to separate gas, non-aromatic components, C6-C8 light aromatic compounds, and relatively heavy C9+ aromatic components, and further to separate desired products such as BTX. And, this separation can be carried out by a method conventionally used in the art without being limited to a specific method in the present application, and the detailed description thereof is omitted in this specification.

[0036] According to the present application, the separated spent catalyst can be sent to a regeneration reactor for regeneration and recycled, and the product rich in C6-C8 light aromatic compounds can be subjected to gas-liquid separation to separate hydrogen. As shown in FIG. 1, the product rich in C6-C8 light aromatic compounds can be passed through a two-stage cooling gas-liquid separator and then sequentially sent to a hot product gas-liquid separation tank and a cold product gas-liquid separation tank for separation, for example. Hydrogen is obtained from the top of the cold product gas-liquid separation tank, and the obtained hydrogen can also be recycled to the fluidization reactor as recycled hydrogen, and the liquid product obtained from the bottom of the two gas-liquid separation tanks can be further separated.

[0037] In a preferred embodiment of the present application, the spent catalyst may be sent to a fluidized bed regenerator for regeneration, and the resulting regenerated catalyst may be recycled to the fluidized reactor. The regeneration of the spent catalyst may be carried out in a manner well known to those skilled in the art, and all or at least a portion of the catalyst used in step i) may be obtained from the regenerated catalyst. In the regeneration step, an oxygen-containing gas, such as atmospheric air, may be introduced into the regenerator, typically from the bottom of the regenerator. After the introduction of the oxygen-containing gas into the regenerator, the spent catalyst is contacted with oxygen for regeneration by coke combustion, and the combustion gas produced from the regeneration of the catalyst is subjected to gas-solid separation at the top of the regenerator and then passed to the next energy recovery system. Depending on the nature of the active metal components of the catalyst, regeneration processes such as reduction and sulfurization may be incorporated.

[0038] In order to avoid contact between the hydrogen-containing gas stream and the oxygen-containing gas stream during catalyst regeneration and to improve plant safety, in a preferred embodiment, as shown in Figure 2, the fluidized bed regenerator may further include a lock hopper, and the regeneration method may include: passing the spent dealkylation catalyst into the fluidized bed regenerator via the lock hopper for regeneration, and recycling the regenerated dealkylation catalyst to the fluidized reactor via said lock hopper. In this embodiment, the lock hopper allows safe and efficient transfer of catalyst from a high-pressure hydrocarbon or hydrogen environment in the reactor to a low-pressure oxygen environment in the regenerator, and from a low-pressure oxygen environment in the regenerator to a high-pressure hydrocarbon or hydrogen environment in the reactor. In a preferred embodiment, the method further includes depressurizing the spent catalyst in the lock hopper, followed by pressurizing the regenerated catalyst.

[0039] According to the present application, by using a lock hopper, the reducing atmosphere (hydrogen atmosphere) in the reactor and the regenerated catalyst supply tank can be sufficiently isolated from the oxygen-containing atmosphere in the regenerator for coke combustion regeneration, thereby ensuring the safety of the process and method, and allowing the operating pressure of the reactor and the regenerator to be flexibly adjusted and controlled. In particular, the operating pressure of the reactor can be increased without increasing the operating pressure of the regenerator, thereby increasing the processing capacity of the plant. The lock hopper described herein is a device that allows switching of flows between different atmospheres (e.g., oxidizing atmosphere and reducing atmosphere) and / or between different pressure environments (e.g., from high pressure to low pressure or vice versa), and its configuration and operation can be easily realized by those skilled in the art based on the description herein.

[0040] In a further preferred embodiment, as shown in Fig. 2, the fluidized bed regenerator may further include a reactor receiver 19, a regenerator receiver 23, a regenerator feed tank 21, and optionally a reducer 24, and the spent catalyst recovered from the fluidized reactor may be transferred to the reactor receiver 19, then transferred to the regenerator feed tank 21 via a lock hopper 20, and then transferred from the regenerator feed tank 21 to the fluidized bed regenerator 22, and subjected to regeneration by coke combustion in the regenerator under an oxygen-containing atmosphere to obtain a regenerated dealkylation catalyst; the regenerated catalyst is continuously recovered from the fluidized bed regenerator 22, passed through the regenerator receiver 23 and the reducer 24, and recycled to the fluidized reactor for reuse after reduction. Even more preferably, the spent catalyst may be depressurized in the lock hopper 20, and the regenerated catalyst may be pressurized in the lock hopper 20 as necessary.

[0041] In other embodiments of the present application, catalyst transfer between the regenerator and the reactor may be accomplished using a regenerated catalyst standpipe and a spent catalyst standpipe.

[0042] According to the present application, the feedstock containing heavy aromatic compounds contains at least one C9+ aromatic hydrocarbon, which means that the feedstock may be a pure C9+ aromatic hydrocarbon or a feedstock containing C9+ aromatic hydrocarbons, preferably a feedstock rich in C9+ aromatic compounds; the content of C9+ aromatic compounds in the feedstock containing heavy aromatic compounds can vary over a wide range, preferably the content of C9+ aromatic compounds can be in the range of about 20% by weight to about 100% by weight, more preferably in the range of about 30% by weight to about 100% by weight.

[0043] According to the present application, the feed containing heavy aromatic compounds may have an initial boiling point of about 120-150°C, preferably about 130-140°C, a final boiling point of about 200-250°C, preferably about 205-240°C, and a distillation range of about 120-250°C, preferably about 140-220°C.

[0044] According to the present application, the feedstock containing heavy aromatic compounds may be obtained from processes such as steam cracking, catalytic cracking, catalytic reforming, PX production, or other processes that can produce C9+ aromatic compounds, for example, the feedstock meeting the above requirements may be at least one of heavy aromatic compounds obtained from steam cracking gasoline, heavy aromatic compounds obtained from catalytic cracking gasoline, heavy aromatic compounds obtained from catalytic reforming, and C9+ heavy aromatic compounds from the bottom of the xylene tower in the aromatic compound combined unit.

[0045] According to the present application, the catalyst used in step i) may comprise a support and an active metal component supported on the support, and the composition and content of the catalyst may vary over a wide range. In a preferred embodiment, based on the total weight of the catalyst, the support may be present in the catalyst in an amount of about 50 to about 99.99% by weight, preferably about 55 to about 85% by weight; the active metal component may be present in an amount of about 0.01 to about 50% by weight, preferably about 0.01 to about 45% by weight.

[0046] According to the present application, the active metal component is preferably one or more of rare earth metals and transition metals, such as Fe, Ni, Pt, Pd, Co and Mo, preferably Ni, Pt and Pd. When the active metal component is a precious metal, it is preferably present in an amount of about 0.01 to about 5% by weight; when the active metal component is a non-precious metal, it is preferably present in an amount of about 0.01 to about 30% by weight, these values ​​being calculated on an elemental metal basis and based on the total weight of the catalyst.

[0047] According to the present application, when the active metal component is a precious metal, the dealkylation catalyst does not need to be presulfided; when the active metal component is a non-precious metal, the catalyst may or may not be presulfided.

[0048] According to the present application, the composition and content of the support may also vary within a wide range. In a preferred embodiment, the support may comprise, based on the dry weight of the support, about 1 to about 80% by weight of zeolite, about 5 to about 99% by weight of inorganic oxide, and about 0 to about 70% by weight of clay; more preferably, the support may comprise about 10 to about 50% by weight of zeolite, about 10 to about 90% by weight of inorganic oxide, and about 1 to about 60% by weight of clay. Preferably, the zeolite may comprise mesoporous zeolite, macroporous zeolite, or a combination thereof, and is preferably selected from the group consisting of mesoporous zeolite, macroporous zeolite, or a combination thereof. More preferably, the mesoporous zeolite is present in an amount of about 0 to about 100% by weight, preferably about 50 to about 100% by weight, more preferably about 70 to about 90% by weight; and the macroporous zeolite is present in an amount of about 0 to about 100% by weight, preferably about 0 to about 50% by weight, more preferably about 10 to about 30% by weight, based on the total weight of the zeolite.

[0049] According to the present application, in the catalyst support, the mesoporous zeolite and the macroporous zeolite may be of the type conventionally used in the art, for example, the mesoporous zeolite is preferably one or more selected from ZSM zeolite and ZRP zeolite, and the macroporous zeolite is preferably one or more selected from β zeolite, REY zeolite, REHY zeolite, ultrastable Y zeolite and high silica Y zeolite.

[0050] According to the present application, in the support of the catalyst, the inorganic oxide and the clay may each be of a type conventionally used in the art, for example, the inorganic oxide may be one or more of silica, alumina, zirconia, titania and amorphous silica-alumina, preferably silica and / or alumina; the clay may be one or more selected from kaolin, montmorillonite, diatomaceous earth, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and rectorite, preferably kaolin and / or halloysite.

[0051] According to the present application, the support may be subjected to a hydrothermal aging treatment under conditions of a temperature of about 700° C. to about 850° C. and an atmosphere of up to 100% water vapor, or may be used without hydrothermal aging.

[0052] According to the present application, the catalyst is preferably in the form of microspherical particles having the following particle size distribution: a mass fraction of particles between 0 and 20 μm less than about 5%, a mass fraction of particles between 0 and 40 μm less than about 30%, a mass fraction of particles between 0 and 149 μm more than about 80%, and an average particle size between about 50 and about 90 μm, preferably between about 60 and about 80 μm; and a catalyst attrition index less than about 10% / h, preferably less than about 5% / h.

[0053] According to the present application, the fluidized reactor is preferably selected from the group consisting of a conveying bed reactor, a dense-phase fluidized bed reactor, a composite reactor composed of a conveying bed reactor and a dense-phase fluidized bed reactor, a composite reactor composed of two or more conveying bed reactors, or a composite reactor composed of two or more dense-phase fluidized bed reactors; wherein the conveying bed reactor can be, for example, a riser reactor; the dense-phase fluidized bed reactor can be, for example, a bubbling bed reactor, a turbulent fluidized bed reactor, etc. In a preferred embodiment, the fluidized reactor used is a dense-phase fluidized bed reactor, which can be equipped with an expansion segment at the top, in which a cyclone or a catalyst filter can be provided for recovering the catalyst entrained in the gas flow. When a dense-phase fluidized bed reactor or a riser reactor is used, its feeding and operation mode can be the same as those conventionally adopted in existing dense-phase fluidized bed reactors and riser reactors, and is not particularly limited in the present application.

[0054] In a particularly preferred embodiment, as shown in FIG. 1, the method for producing light aromatic compounds according to the present application is carried out as follows: a feedstock 8 containing heavy aromatic compounds and hydrogen 9 are separately fed into the fluidized reactor 1 from the bottom of the fluidized reactor 1, and are contacted with a catalyst in the fluidized reactor 1 to carry out an aromatic compound lightening reaction. The product rich in C6-C8 light aromatic compounds obtained after gas-solid separation is sequentially passed through a hot product gas-liquid separation tank 2 and a cold product gas-liquid separation tank 3 for gas-liquid separation to obtain recycled hydrogen 11 and liquid product 10. The recycled hydrogen 11 is recycled to the fluidized reactor 1 after treatment for further reaction. The liquid product 10 is sent to an aromatic compound extraction unit 4 for aromatic compound extraction, and non-aromatic components 12 and aromatic components 13 are obtained by separation. The aromatic components 13 are sent to an aromatic compound separation tower 5. The C10+ aromatic components 15 obtained from the bottom of the tower are mixed with the feedstock 8 and then recycled to the fluidized reactor 1 for further reaction. C9 aromatics 14 are obtained at the bottom of aromatics separation column 5. BTEX (benzene, toluene, ethylbenzene and xylenes) are obtained at the top of the column. BTEX is sent to product separation unit 6 for further separation to obtain benzene 18, toluene 16 and xylenes 17. C9 aromatics 14 and toluene 16 are mixed to obtain mixed recycle feed 7. Mixed recycle feed 7 is sent to fluidized reactor 1 from a location downstream of the feed location of feedstock 8 for further reaction.

[0055] As shown in FIG. 2, in a further preferred embodiment, the feedstock 8 containing heavy aromatic compounds and hydrogen 9 are fed into the fluidized reactor 1 from the bottom of the fluidized reactor 1, and are reacted with the catalyst to lighten the aromatic compounds. The reaction product is sent to the gas-liquid separation tank 25 for gas-liquid separation to obtain the reaction liquid product 10 and hydrogen. The spent catalyst is continuously recovered from the fluidized reactor 1, sent through the reactor receiver 19 to the lock hopper 20, then sent to the regenerator feed tank 21, and then sent to the fluidized bed regenerator 22, in which it is subjected to regeneration by coke combustion in an oxygen-containing atmosphere, and the obtained regenerated catalyst is continuously discharged to the regenerator receiver 23, then sent through the lock hopper 20 to the reducer 24 for reduction, and continuously recycled to the fluidized reactor 1 for reuse.

[0056] In some preferred embodiments, the present application provides the following technical solutions: Item 1. A method for producing a light aromatic compound, comprising the steps of: contacting a feedstock containing heavy aromatic compounds with a catalyst in a fluidized reactor for an aromatics lightening reaction in the presence of hydrogen to obtain a product enriched in light aromatic compounds and a spent catalyst; separating the light aromatics-enriched product to obtain hydrogen, non-aromatic components, C6-C8 light aromatics and C9+ aromatic components, and recycling at least a portion of the C9+ aromatic components to the fluidization reactor.

[0057] Item 2: The lightening reaction is carried out at a temperature of 250 to 750°C, a pressure of 0 to 6 MPa, and for 0.1 to 7 hours. -1 and a hydrogen / hydrocarbon molar ratio of 1 to 15; preferably, the lightening reaction is carried out at a temperature of 320 to 600° C., a pressure of 0 to 4.5 MPa, and a reaction time of 1 to 6 h. -1 and a hydrogen / hydrocarbon molar ratio of 2 to 10; more preferably, the lightening reaction is carried out at a temperature of 360 to 550° C., a pressure of 1 to 3 MPa, and a reaction time of 1.5 to 4.5 h. -1and a hydrogen / hydrocarbon molar ratio of 3 to 8.

[0058] Item 3. The method of item 1, wherein the separating includes: subjecting the light aromatics-rich product to gas-liquid separation to obtain hydrogen and a liquid product, and subjecting the liquid product to aromatics extraction to obtain non-aromatic and aromatic components; Subjecting the aromatic components to a first fractionation to obtain light aromatics and C9+ aromatics, or alternatively subjecting the aromatic components to a second fractionation to obtain light aromatics, C9 aromatics, and C10+ aromatics.

[0059] Item 4. The method according to item 3, further comprising: subjecting the light aromatics to a third fractionation to obtain benzene, toluene and xylenes, mixing the toluene and the C9 aromatics to obtain a mixed recycle feed, and recycling the mixed recycle feed to the fluidized reactor; and mixing the C10+ aromatics with the feed containing the heavy aromatics and then recycling it to the fluidized reactor for the lightening reaction.

[0060] Item 5. The method according to item 4, wherein the C10+ aromatics and the mixed recycle feed are continuously fed to the fluidized reactor along the flow direction of the feed containing heavy aromatics in the fluidized reactor.

[0061] Item 6. The method of item 1, wherein the method includes recycling the hydrogen to the fluidized reactor for reuse.

[0062] Item 7. The method according to item 1, further comprising sending the spent catalyst to a fluidized bed regenerator for regeneration, and recycling the resulting regenerated catalyst to the fluidized reactor.

[0063] Item 8. The method according to item 7, wherein the fluidized bed regenerator includes a lock hopper, and the regeneration is carried out by: sending the spent catalyst via the lock hopper to the fluidized bed regenerator for regeneration, and recycling the regenerated catalyst via the lock hopper to the fluidized reactor.

[0064] Item 9: The method according to Item 1, wherein the feedstock containing heavy aromatic compounds has an initial boiling point of 120 to 150°C and a final boiling point of 200 to 250°C.

[0065] Item 10. The method according to item 1, wherein the feedstock containing heavy aromatic compounds has a C9+ aromatic compound content of 20 to 100 wt.%.

[0066] Item 11. The method according to item 1, wherein the feedstock is at least one selected from heavy aromatic compounds obtained from steam cracking gasoline, heavy aromatic compounds obtained from deep catalytic cracking gasoline, heavy aromatic compounds obtained from catalytic cracking gasoline, heavy aromatic compounds obtained from catalytic reforming, and C9+ heavy aromatic compounds from the bottom of the xylene tower in a PX plant.

[0067] Item 12: The method according to item 1, wherein the fluidized reactor is a dilute phase transport bed reactor, a dense phase fluidized bed reactor, a composite reactor consisting of a dilute phase transport bed reactor and a dense phase fluidized bed reactor, a composite reactor consisting of two or more dilute phase transport bed reactors, or a composite reactor consisting of two or more dense phase fluidized bed reactors.

[0068] Item 13. The method according to item 12, wherein the dilute phase conveying bed reactor is a riser reactor, and the dense phase fluidized bed reactor is a bubbling fluidized bed reactor, a turbulent fluidized bed reactor, etc.

[0069] Item 14. The method according to item 1, wherein the fluidization reactor is a riser reactor or a downer reactor.

[0070] Item 15. The method according to item 1, wherein the catalyst comprises a support and an active metal component supported on the support in an amount of 0.01 to 50% by weight based on the total weight of the catalyst.

[0071] Item 16, based on the total weight of the support, the support comprises 1-60 wt. % zeolite, 5-99 wt. % inorganic oxide, and 0-70 wt. % clay; Item 16. The method according to item 15, wherein the zeolite comprises a mesoporous zeolite and / or a macroporous zeolite; the inorganic oxide is at least one of silica, alumina, zirconia, titania and amorphous silica-alumina; and the clay is at least one selected from kaolin, montmorillonite, diatomaceous earth, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and rectorite.

[0072] Item 17. The method according to item 16, wherein the mesoporous zeolite is a ZSM zeolite and / or a ZRP zeolite, and the macroporous zeolite is one or more selected from beta zeolite, REY zeolite, REHY zeolite, ultrastable Y zeolite, and high silica Y zeolite.

[0073] Item 18. The method of item 15, wherein the active metal component is one of a rare earth metal and a transition metal, or a combination of two or more of a rare earth metal and a transition metal.

[0074] [Example] The present application will be further illustrated with reference to the following examples, without however being limited thereto.

[0075] Carrier Preparation Example 1 Alumina sol (Qilu Branch of Sinopec Catalyst Co. ltd.) was divided into two equal parts, one part was mixed with kaolin (Qilu Branch of Sinopec Catalyst Co. ltd.), and a slurry with 40% solids by weight was formed with deionized water and stirred uniformly. The slurry was adjusted to pH 3.5 with hydrochloric acid, maintained at this pH value, and allowed to stand and age at 60°C for 1.5 hours. The remaining alumina sol was added and stirred for 1.0 hour to form a colloid. ZSM-5 molecular sieve (available from Qilu Branch of Sinopec Catalyst Co. ltd.) and Y molecular sieve (available from Qilu Branch of Sinopec Catalyst Co. ltd.) were added to form a carrier slurry (with 35% solids by weight), which was further stirred and spray-dried to obtain a microsphere carrier. The weight ratio in this microsphere carrier was ZSM-5 molecular sieve:Y molecular sieve:kaolin:aluminum sol=30:10:39:21.

[0076] The microspherical support was then calcined at 500°C for 1 hour, washed with ammonium sulfate at 60°C to a sodium oxide content of less than 0.25 wt% (ammonium sulfate:microspherical support:water=0.5:1:10), rinsed with deionized water, filtered, and then dried at 110°C to obtain support C1.

[0077] Carrier Preparation Example 2 The alumina sol was divided into two equal parts, one part was mixed with kaolin, and a slurry with 40% solids by weight was formed with deionized water and stirred uniformly. The pH of the slurry was adjusted to 3.5 with hydrochloric acid, and the pH was maintained at this value, and the slurry was allowed to stand and age at 60°C for 1.5 hours. The remaining alumina sol was added and stirred for 1.0 hour to form a colloid. Y molecular sieves were added to form a carrier slurry (with 35% solids by weight), which was further stirred and spray-dried to obtain a microsphere carrier. The weight ratio of the microsphere carrier was Y molecular sieves:kaolin:aluminum sol=40:39:21.

[0078] The microspherical support was then calcined at 500°C for 1 hour, washed with ammonium sulfate at 60°C (ammonium sulfate:microspherical support:water=0.5:1:10) to a sodium oxide content of less than 0.25 wt%, rinsed with deionized water, filtered, and then dried at 110°C to obtain support C2.

[0079] Catalyst Preparation Example 1 The support C1 was subjected to hydrothermal aging (800°C, 100% steam, 12 hours), then added to a PdCl2 solution to carry out incipient wetness impregnation at an impregnation temperature of 80°C for 120 minutes, and dried at a temperature of 150°C for 2 hours. The Pd-impregnated support was then added to a chloroplatinic acid solution to carry out incipient wetness impregnation at an impregnation temperature of 80°C for 120 minutes; the result was washed with deionized water, dried at a temperature of 150°C for 2 hours, and calcined at a temperature of 500°C for 4 hours. The calcined catalyst was reduced in a hydrogen-containing gas at a temperature of 100°C for 2 hours to obtain a catalyst H1 carrying the active metals Pd and Pt. In this catalyst, the loadings of Pd and Pt were 0.04 wt % and 0.04 wt %, respectively (calculated based on the metal elements relative to the total weight of the catalyst), the attrition index was 3.2% / h, and the particle size distribution was as follows: the mass fraction of particles having a particle size of 0 to 20 μm was 3%, the mass fraction of particles having a particle size of 0 to 40 μm was 22%, the mass fraction of particles having a particle size of 0 to 149 μm was 89%, and the average particle size was 75 μm.

[0080] Catalyst Preparation Example 2 The support C1 was subjected to hydrothermal aging (800 ° C, 100% water vapor, 12 h), added to NiCl2 solution, subjected to incipient wetness impregnation at an impregnation temperature of 80 ° C for 120 min, washed with deionized water, dried at 150 ° C for 2 h, and calcined at 500 ° C for 4 h. The calcined catalyst was subjected to a preliminary sulfurization treatment to obtain a catalyst H2 carrying NiS. In this catalyst, the NiS loading was 6.5% (calculated based on Ni, relative to the total weight of the catalyst), the wear index was 3.2% / h, and the particle size distribution was as follows: the mass fraction of particles having a particle size of 0-20 μm was 3%, the mass fraction of particles having a particle size of 0-40 μm was 22%, the mass fraction of particles having a particle size of 0-149 μm was 89%, and the average particle size was 75 μm.

[0081] Catalyst Preparation Example 3 Support C2 was subjected to hydrothermal aging (800°C, 100% steam, 12 hours), then added to a PdCl2 solution, incipient wetness impregnation was performed at an impregnation temperature of 80°C for 120 minutes, and dried at 150°C for 2 hours. The Pd-impregnated support was then added to a chloroplatinic acid solution, incipient wetness impregnation was performed at an impregnation temperature of 80°C for 120 minutes, washed with deionized water, dried at 150°C for 2 hours, and calcined at 500°C for 4 hours. The calcined catalyst was reduced in a hydrogen-containing gas at 100°C for 2 hours to obtain catalyst H3 carrying the active metals Pd and Pt. In this catalyst, the loadings of Pd and Pt were 0.04 wt % and 0.04 wt %, respectively (calculated based on the metal elements relative to the total weight of the catalyst), the attrition index was 2.8% / h, and the particle size distribution was as follows: the mass fraction of particles having a particle size of 0 to 20 was 2.5%, the mass fraction of particles having a particle size of 0 to 40 μm was 19%, the mass fraction of particles having a particle size of 0 to 149 μm was 91%, and the average particle size was 73 μm.

[0082] Catalyst Preparation Example 4 The carrier C1 was subjected to hydrothermal aging (800 ° C, 100% water vapor, 12 hours), added to NiCl2 solution, subjected to incipient wetness impregnation at an impregnation temperature of 80 ° C for 120 minutes, washed with deionized water, dried at 150 ° C for 2 hours, and calcined at 500 ° C for 4 hours. The calcined catalyst was reduced in a hydrogen-containing gas at 100 ° C for 2 hours without pre-sulfurization treatment to obtain a catalyst H4 carrying Ni. In this catalyst, the Ni loading was 6.5% (calculated based on Ni with respect to the total weight of the catalyst), the wear index was 3.2% / h, and the particle size distribution was as follows: the mass fraction of particles having a particle size of 0 to 20 μm was 3%, the mass fraction of particles having a particle size of 0 to 40 μm was 22%, the mass fraction of particles having a particle size of 0 to 149 μm was 89%, and the average particle size was 75 μm.

[0083] Catalyst Preparation Example 5 The support C1 was added to a PdCl2 solution without hydrothermal aging, and incipient wetness impregnation was performed at an impregnation temperature of 80° C. for 120 minutes, and dried at a temperature of 150° C. for 2 hours. The Pd-impregnated support was then added to a chloroplatinic acid solution, and incipient wetness impregnation was performed at an impregnation temperature of 80° C. for 120 minutes, washed with deionized water, dried at a temperature of 150° C. for 2 hours, and calcined at a temperature of 500° C. for 4 hours. The calcined catalyst was reduced in a hydrogen-containing gas at a temperature of 100° C. for 2 hours to obtain a catalyst H5 carrying the active metals Pd and Pt. In this catalyst, the loadings of Pd and Pt were 0.04 wt % and 0.04 wt %, respectively (calculated based on the metal elements relative to the total weight of the catalyst), the attrition index was 3.2% / h, and the particle size distribution was as follows: the mass fraction of particles having a particle size of 0 to 20 μm was 2.5%, the mass fraction of particles having a particle size of 0 to 40 μm was 16%, the mass fraction of particles having a particle size of 0 to 149 μm was 87%, and the average particle size was 78 μm.

[0084] The following examples and comparative examples are provided to illustrate methods for producing light aromatic compounds according to the present application and methods for producing light aromatic compounds not according to the present application.

[0085] The properties of the heavy aromatics feedstocks used are listed in Table 1. In Table 1, feedstock A is a heavy aromatics obtained from deep catalytic cracking gasoline, feedstock B is a heavy aromatics obtained from steam cracking gasoline, and feedstock C is a heavy aromatics obtained from catalytic reforming.

[0086] [Table 1]

[0087] The results of each of the Examples and Comparative Examples are as follows: Conversion % = 100% - the total mass content, expressed as a percentage, of all components in the product that are the same as those in the feedstock; BTX selectivity = BTX yield / conversion; Xylene selectivity = xylene yield / conversion.

[0088] Example 1 The experiments were carried out on a pilot dense-phase fluidized-bed reactor with continuous regeneration using feed A and catalyst H1 according to the flow schemes shown in Figures 1 and 2. The relevant conditions and products are listed in Table 2.

[0089] Example 2 The experiment was carried out as described in Example 1, except that the reaction temperature was 480° C. The relevant conditions and products are listed in Table 2.

[0090] Example 3 The experiment was carried out as described in Example 1, except that catalyst H2 was used. The relevant conditions and products are listed in Table 2.

[0091] Example 4 The experiment was carried out as described in Example 1, except that catalyst H3 was used. The relevant conditions and products are listed in Table 2.

[0092] Example 5 The experiment was carried out as described in Example 1, except that Feedstock B was used. The relevant conditions and products are listed in Table 2.

[0093] Example 6 The experiment was carried out as described in Example 1, except that Feedstock C was used. The relevant conditions and products are listed in Table 2.

[0094] [Table 2]

[0095] Example 7 The experiment was carried out as described in Example 1, except that the separated C9 aromatics were not mixed with toluene but were fed separately to the reactor for reaction downstream of the feed nozzle, and toluene was not recycled but was directly recovered as a product. The relevant conditions and products are listed in Table 3.

[0096] Example 8 The experiments were carried out as described in Example 1, except that the reaction conditions in the dense phase fluidized bed reactor were varied. The relevant conditions and products are listed in Table 3.

[0097] Example 9 The experiment was carried out as described in Example 1, except that catalyst H4 was used. The relevant conditions and products are listed in Table 3.

[0098] Example 10 The experiment was carried out as described in Example 1, except that catalyst H5 was used. The relevant conditions and products are listed in Table 3.

[0099] Example 11 The experiment was carried out as described in Example 1, except that a riser reactor was used as the reactor. The relevant conditions and products are listed in Table 3.

[0100] Example 12 The experiment was carried out as described in Example 1, except that a combined riser reactor and dense phase fluidized bed reactor was used as the reactor. The relevant conditions and products are listed in Table 3.

[0101] [Table 3]

[0102] Comparative Example 1 The experiment was carried out as described in Example 1, except that the toluene and C9+ heavy aromatics separated from the product were not recycled to the reactor. The relevant conditions and products are listed in Table 4.

[0103] Comparative Example 2 The experiment was carried out as described in Example 1, except that a fixed bed reactor was used as the reactor, no additional equipment was used to separate the catalyst and the oil gas, and the catalyst was not continuously regenerated. The relevant conditions and products are listed in Table 4.

[0104] Comparative Example 3 The experiment was carried out as described in Example 1, except that the reaction was carried out in the absence of hydrogen using hydrothermally aged support C2 as the catalyst. The relevant conditions and products are listed in Table 4.

[0105] [Table 4]

[0106] As can be seen from the results of the above examples and comparative examples, the method for producing light aromatic compounds of the present invention can produce light aromatic compounds from various heavy aromatic feedstocks, and shows high feedstock conversion and BTX selectivity; the method can further improve xylene selectivity by recycling C9 aromatic compounds and toluene, and has great flexibility in operation and enables long-term stable operation, in which the catalyst is easily regenerated and the mass and heat transfer are uniform.

[0107] Although the present application has been described in detail above with reference to preferred embodiments, it is not intended to be limited to these embodiments. According to the inventive concept of the present application, various modifications are possible, and these modifications are within the scope of the present application.

[0108] It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, this application does not describe various possible combinations, but such combinations are within the scope of this application.

[0109] Furthermore, various embodiments of the present application may be combined in any manner without departing from the spirit of the present application, and such combined embodiments should be considered as the disclosure of the present application. [Brief description of the drawings]

[0110] [Figure 1] FIG. 1 shows a process flow diagram of one embodiment of the method according to the present application. [Diagram 2] FIG. 2 shows a schematic diagram of a regenerator according to one embodiment of the method according to the present application.

Claims

1. i) contacting a feedstock comprising heavy aromatic compounds with a catalyst in a fluidized reactor for an aromatics lightening reaction in the presence of hydrogen to obtain a product enriched in C6-C8 light aromatic compounds and spent catalyst, wherein the heavy aromatic compounds are one or more selected from C9+ aromatic compounds; ii) separating the resulting C6-C8 light aromatics-enriched product to obtain hydrogen, non-aromatic components, C6-C8 light aromatics and C9+ aromatic components; and iii) recycling at least a portion of the C9+ aromatics to the fluidization reactor; Including, Where: The reaction conditions for step i) are a temperature of 250 to 750 ° C., a pressure (gauge pressure) of 0 to 6 MPa, and a reaction time of 0.1 to 120 h. －１ or a reaction time of 0.1 to 40 seconds, and a hydrogen / hydrocarbon molar ratio of 1 to 15; The catalyst used in step i) comprises a support and an active metal component supported on the support in an amount of 0.01 to 50 wt. % based on the total weight of the catalyst; wherein the support comprises, based on the total weight of the support, 1 wt. % to 80 wt. % of a zeolite, 5 wt. % to 99 wt. % of an inorganic oxide, and 0 wt. % to 70 wt. % of a clay, wherein the zeolite comprises a mesoporous zeolite, a macroporous zeolite, or a combination thereof; the inorganic oxide is one or more selected from silica, alumina, zirconia, titania, and amorphous silica-alumina; the clay is one or more selected from kaolin, montmorillonite, diatomaceous earth, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite, and rectorite; The active metal component is one or more selected from rare earth metals and transition metals, The separation of step ii) further comprises: subjecting the C6-C8 light aromatics-enriched product to gas-liquid separation to obtain hydrogen and a liquid product; subjecting the liquid product to aromatics extraction to obtain non-aromatic and aromatic components; and subjecting the aromatics to a second fractionation to obtain C6-C8 light aromatics, C9 aromatics, and C10+ aromatics; After step ii), further comprising: subjecting the C6 to C8 light aromatic compounds to a third fractionation to obtain benzene, toluene and xylenes; mixing the toluene and the C9 aromatics to obtain a mixed recycle feed, and recycling the mixed recycle feed to the fluidization reactor; and mixing the C10+ aromatics with a feed containing heavy aromatics and recycling the resultant to the fluidization reactor; the mixed recycle feed is recycled to the fluidized reactor at a location along a flow direction of the heavy aromatics feedstock in the fluidized reactor downstream of a location where the C10+ aromatics are recycled; A method for producing light aromatic compounds.

2. The reaction conditions in step i) are a temperature of 320 to 600° C., a pressure of 0 to 4.5 MPa, and a reaction time of 1 to 80 h. －１ or a reaction time of 0.5 to 30 seconds, and a hydrogen / hydrocarbon molar ratio of 2 to 10. The method of claim 1.

3. The reaction conditions in step i) are a temperature of 360 to 550° C., a pressure of 1 to 3 MPa, and a reaction time of 1.5 to 50 h. －１ or a reaction time of 1 to 15 seconds, and a hydrogen / hydrocarbon molar ratio of 3 to 8. The method of claim 1.

4. The process according to any one of claims 1 to 3, further comprising the step of regenerating the spent catalyst in a fluidized bed regenerator and recycling the resulting regenerated catalyst to the fluidized reactor.

5. the fluidized bed regenerator includes a lock hopper; and 5. The method of claim 4, wherein the regeneration is carried out by sending the spent catalyst to the fluidized bed regenerator for regeneration via the lock hopper, and recycling the resulting regenerated catalyst to the fluidized reactor via the lock hopper.

6. The fluidized bed regenerator further comprises a reactor receiver, a regenerator receiver, a regenerator feed tank, and optionally a reducer; and The regeneration may include removing said spent catalyst from said fluidized reactor and passing it to said reactor receiver and then via said lock hopper to said regenerator feed tank and then from said regenerator feed tank to said fluidized bed regenerator; subjecting the spent catalyst to regeneration by coke combustion in the regenerator under an oxygen-containing atmosphere to obtain a regenerated catalyst; and removing the regenerated catalyst from the fluidized bed regenerator and recycling it directly through the regenerator receiver to the fluidized reactor for reuse or after reduction in a reducer, recycling it to the fluidized reactor for reuse; To be carried out by The method according to claim 5.

7. The method further includes depressurizing the spent catalyst in the lock hopper and pressurizing the regenerated catalyst in the lock hopper. The method according to claim 5.

8. The feedstock containing heavy aromatic compounds has an initial boiling point of 120° C. to 150° C. and a final boiling point of 200° C. to 250° C. The method according to any one of claims 1 to 3.

9. the heavy aromatics-containing feedstock has a total C9+ aromatics content of 20 wt.% to 100 wt.%; The method according to any one of claims 1 to 3.

10. The method according to any one of claims 1 to 3, wherein the feedstock containing heavy aromatic compounds is at least one selected from heavy aromatic compounds obtained from steam cracked gasoline, heavy aromatic compounds obtained from deep catalytic cracked gasoline, heavy aromatic compounds obtained from catalytic cracked gasoline, heavy aromatic compounds obtained from catalytic reforming, and C9+ heavy aromatic compounds from the bottom of a xylene tower in an aromatic compound complex plant.

11. 4. The method according to any one of claims 1 to 3, wherein the fluidized reactor is selected from a conveying bed reactor, a dense phase fluidized bed reactor, a composite reactor composed of a conveying bed reactor and a dense phase fluidized bed reactor, a composite reactor composed of two or more conveying bed reactors, or a composite reactor composed of two or more dense phase fluidized bed reactors.

12. the transporting bed reactor is a riser reactor, and The dense phase fluidized bed reactor is a bubbling fluidized bed reactor, a turbulent fluidized bed reactor; The method of claim 11.

13. The mesoporous zeolite is one or more selected from ZSM zeolite and ZRP zeolite; and The method according to any one of claims 1 to 3, wherein the macroporous zeolite is one or more selected from beta zeolite, REY zeolite, REHY zeolite, ultrastable Y zeolite, and high silica Y zeolite.

14. Based on the total weight of the zeolite, the mesoporous zeolite is present in an amount of 0% to 100% by weight; and The macroporous zeolite is present in an amount of 0% to 100% by weight. The method according to any one of claims 1 to 3.

15. The mesoporous zeolite is present in an amount of 50% to 100% by weight. The method of claim 14.

16. The mesoporous zeolite is present in an amount of 70% to 90% by weight. The method of claim 14.

17. The macroporous zeolite is present in an amount of 0% to 50% by weight. The method of claim 14.

18. The macroporous zeolite is present in an amount of 10% to 30% by weight. The method of claim 14.

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