Method for increasing yield of light aromatic hydrocarbons through catalytic cracking gasoline reconversion

Abstract

The invention relates to a method for increasing yield of light aromatic hydrocarbons through catalytic cracking gasoline reconversion, and the method is characterized in that heavy aromatic hydrocarbons in a heavy oil cracking product can be efficiently converted into light aromatic hydrocarbons by treating a heavy oil raw material through a catalytic cracking reaction. The problems of high hydrogen consumption, harsh operation conditions and aromatic hydrocarbon loss caused by hydrotreating production of light aromatic hydrocarbon can be avoided; on the other hand, the problem that low-value heavy aromatics are difficult to utilize can be solved, and efficient utilization of resources is achieved. Moreover, the gasoline heavy fraction is reprocessed in a second reactor, and the second reactor is a dense-phase fluidized bed reactor, so that the gasoline heavy fraction can fully react, and the yield of the light aromatic hydrocarbon can be further improved. In addition, by adopting the method disclosed by the invention, low-carbon olefin can be produced as a byproduct, and the utilization rate of the raw materials is further improved.

Description

Technical Field

[0001] The present disclosure relates to the field of petrochemical industry, and in particular, to a method for catalytically cracking gasoline and then converting it to increase the production of light aromatics. Background Art

[0002] BTX (B is benzene, T is toluene, and X is xylene) is an important petrochemical basic product and an important raw material for a variety of chemical products such as synthetic rubber, synthetic fiber, and synthetic resin. Toluene and xylene can also be used as gasoline octane additives. However, the production process of aromatics is accompanied by the production of C9+ heavy aromatics. At present, the output of C9+ heavy aromatics is large, the value is low, and the utilization channels are limited, resulting in a waste of resources. Converting C9+ heavy aromatics into BTX is undoubtedly an effective way to fully utilize resources and improve the quality and efficiency of enterprises.

[0003] 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, and reacts to produce C6-C9 aromatic hydrocarbons and C1-C4 paraffin hydrocarbons at a temperature of 300-600°C and a pressure of 1.5-4.0MPa in a fixed bed reactor. The process is particularly suitable for hydrodealkylation and transalkylation of C10 or / and heavy aromatic hydrocarbons above C10, and can be used in industrial production.

[0004] CN200410066625.4 discloses a method for hydrogenation dealkylation and transalkylation of heavy aromatics, which mainly solves the problem that the content of heavy aromatics allowed in the raw materials is low and the utilization rate of heavy aromatics is low in the prior art. The present invention adopts C10 or / and C11 aromatics as raw materials, and uses large-pore zeolite loaded with bismuth and molybdenum metals or oxides as catalysts in a fixed bed reactor to react and generate mixed xylenes at a temperature of 300-600°C and a pressure of 1.0-4.0MPa, which solves the problem well. The 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 mixed xylenes from heavy aromatics.

[0005] CN200480040758.2 discloses a method for the separate catalytic hydrodealkylation of hydrocarbons, wherein the hydrocarbons contain C8-C13 alkyl aromatic compounds, which are optionally mixed with C4-C9 aliphatic and alicyclic products, the method comprising continuously treating the hydrocarbon composition with a catalyst 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, the catalyst consisting of ZSM-5 zeolite and modified by at least one metal selected from Groups IIB, VIB and VIII. The method can achieve a benzene + toluene yield of 75%.

[0006] CN200710043941.3 discloses a method for producing light aromatics and light alkanes using hydrocarbon raw materials. In this method, hydrocarbon raw materials with a boiling point of 30 to 250°C are reacted in the presence of a zeolite catalyst containing Pt or Pd. Heavy aromatics in the hydrocarbon raw materials are dealkylated by hydrogenation and undergo an alkylation translocation reaction with light aromatics. Light aromatics undergo an isomerization reaction to convert into components rich in BTX (B is benzene, T is toluene, and X is xylene) light aromatics. Non-aromatics are converted into light alkanes by a hydrogenation cracking reaction. In a distillation tower, liquid products can be separated into benzene, toluene, xylene, and C9+ aromatics according to different boiling points, and light alkanes can be separated from gaseous products. This method solves the technical problems that the traditional separation process of hydrocarbon raw materials requires solvent extraction, the process is complicated, the cost is high, and the utilization value of heavy aromatics and non-aromatics after separation is low.

[0007] CN200810043966.8 discloses a method for producing more benzene and xylene by hydrogenation cracking of pyrolysis gasoline. The method reacts C7+ pyrolysis gasoline raw materials in the presence of a catalyst, hydrogenates and dealkylates heavy aromatics and undergoes an alkylation translocation reaction with light aromatics, and undergoes an isomerization reaction to convert light aromatics rich in BTX into components, and the liquid phase products are separated into benzene, toluene, xylene, and C9+ fractions according to different boiling points, wherein the toluene and C9+ fractions can be returned as feeds for further processing, and the light alkanes can be separated from the gas phase products. The method solves the problem that the traditional process of pyrolysis gasoline only simply separates BTX aromatics, and the light aromatics product contains a large amount of toluene, and the utilization value of the separated heavy aromatics and non-aromatics is low.

[0008] From the technology disclosed in the above patent application, it can be seen that the existing heavy aromatics lightening technology mostly adopts the fixed bed hydrogenation dealkylation method. However, the hydrogenation process has problems such as high hydrogen consumption, harsh operating conditions, and aromatics loss. Catalytic cracking has the characteristics of no hydrogen consumption and flexible operation. While catalytic cracking produces low-carbon olefins and light aromatics, it also generates heavy aromatics. Summary of the invention

[0009] The present invention provides a method for catalytic cracking gasoline reconversion to increase the production of light aromatics, so as to solve the problems of high hydrogen consumption, harsh operating conditions, aromatics loss and low resource utilization in the existing hydrogenation technology.

[0010] In order to achieve the above-mentioned object, the present disclosure provides a method for catalytic cracking gasoline reconversion to increase the production of light aromatics, which method comprises: allowing a heavy oil feedstock to enter a first reactor of a cracking reaction unit and contact it with a cracking catalyst to perform a cracking reaction to obtain a cracking reaction product; subjecting the cracking reaction product to product separation treatment to obtain other products, light gasoline, a gasoline middle fraction and a gasoline heavy fraction; subjecting the gasoline middle fraction to aromatic separation treatment to obtain a benzene product, a toluene product and a xylene product; allowing the gasoline heavy fraction to enter a second reactor of the cracking reaction unit and contact it with a lightening catalyst to perform a lightening reaction to obtain a lightening reaction product; subjecting the lightening reaction product and the cracking reaction product to the product separation treatment; or, returning the lightening reaction product to the first reactor; the second reactor is a dense phase fluidized bed reactor, and the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; The catalyst activity of the catalyst in the second reactor is 50-99.

[0011] Optionally, the heavy oil feedstock includes petroleum hydrocarbons and / or other mineral oils; the petroleum hydrocarbons are selected from one or more of vacuum wax oil, atmospheric wax oil, coker wax oil, deasphalted oil, vacuum residue oil, atmospheric residue oil, extracted oil and inferior recycled oil; the other mineral oils are selected from one or more of coal liquefaction oil, oil sand oil and shale oil.

[0012] Optionally, the reaction conditions of the cracking reaction include: reaction temperature of 555-720°C, preferably 580-700°C; reaction time of 1-10s, preferably 1.5-6s; catalyst-oil ratio of (1-100):1, preferably (10-50):1; the reaction conditions of the lightening reaction include: reaction temperature of 530-730°C, preferably 560-680°C; catalyst-oil ratio of (1-100):1, preferably (5-30):1; catalyst activity of 60-90.

[0013] Optionally, the cracking catalyst and the lightening catalyst are the same or different; the cracking catalyst and the lightening catalyst each independently comprise zeolite, an inorganic oxide and optional clay; based on the total weight of the catalyst, the content of the zeolite is 5-70% by weight, the content of the inorganic oxide is 1-95% by weight, and the content of the clay is 1-50% by weight.

[0014] Optionally, the zeolite of the cracking catalyst includes large-pore zeolite and optional medium-pore zeolite; based on the total weight of the zeolite in the cracking catalyst, the content of large-pore zeolite is 30-99 weight%, and the content of medium-pore zeolite is 1-70 weight%; the zeolite of the lightening catalyst includes large-pore zeolite and medium-pore zeolite; based on the total weight of the zeolite in the lightening catalyst, the content of large-pore zeolite is 50-99 weight%, and the content of medium-pore zeolite is 1-50 weight%.

[0015] Optionally, the medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of β zeolite and Y zeolite; the inorganic oxide includes silicon dioxide and / or aluminum oxide; and the clay is kaolin and / or halloysite.

[0016] Optionally, the cracking catalyst and the lightening catalyst contain rare earth elements respectively. Preferably, the large-pore zeolite is a Y-type zeolite modified with rare earth elements.

[0017] Optionally, the first reactor is a combination of a riser reactor and a fluidized bed reactor.

[0018] Optionally, the first reactor and the second reactor are arranged in parallel or in series; when the first reactor and the second reactor are arranged in series, the first reactor is arranged downstream of the second reactor.

[0019] Optionally, the cracking reaction unit also includes a regenerator; the method also includes separating the outlet material of the first reactor to obtain a catalyst to be regenerated and the cracking reaction product; allowing the catalyst to be regenerated to enter the regenerator for regeneration treatment to obtain a regenerated catalyst; returning the regenerated catalyst to the first reactor through a first regeneration inclined tube and / or returning the regenerated catalyst to the second reactor through a second regeneration inclined tube; or, separating the outlet material of the first reactor to obtain a cracking catalyst to be regenerated and the cracking reaction product; separating the outlet material of the second reactor to obtain a light-weighted catalyst to be regenerated and the light-weighted reaction product; allowing the cracking catalyst to be regenerated and the light-weighted catalyst to be regenerated to enter the regenerator respectively for regeneration treatment to obtain a regenerated cracking catalyst and a regenerated light-weighted catalyst; returning the regenerated cracking catalyst to the first reactor through a third regeneration inclined tube, and returning the regenerated light-weighted catalyst to the second reactor through a fourth regeneration inclined tube.

[0020] Optionally, a fresh agent inlet is provided on the second regeneration inclined tube and / or at the bottom of the second reactor; or, a fresh agent inlet is provided on the fourth regeneration inclined tube and / or at the bottom of the second reactor.

[0021] Optionally, the product separation process includes: subjecting the cracking reaction product to a first separation to obtain the other products, the light gasoline and heavy gasoline; subjecting the heavy gasoline to a second separation to obtain the gasoline middle fraction and the gasoline heavy fraction.

[0022] Optionally, the initial boiling point of the light gasoline is 20-40°C; the distillation cut point between the light gasoline and the heavy gasoline is 80-100°C; and the distillation cut point between the gasoline middle fraction and the gasoline heavy fraction is 120-150°C.

[0023] Optionally, the bed density of the fluidized bed reactor is 300-500 kg / m 3 , the bed linear speed is 0.4-2m / s.

[0024] Optionally, the light gasoline is returned to the cracking reaction unit for the cracking reaction.

[0025] Optionally, the method further comprises adding a fresh agent into the second reactor; the ratio of the weight of the fresh agent to the total weight of the catalyst in the cracking reaction unit is less than 0.2.

[0026] Through the above technical scheme, the present disclosure can efficiently convert heavy aromatics in heavy oil cracking products into light aromatics by subjecting heavy oil raw materials to catalytic cracking reactions. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatics loss caused by the production of light aromatics by hydroprocessing; on the other hand, it can solve the problem of low-value heavy aromatics being difficult to utilize, and achieve efficient utilization of resources. In addition, the heavy fraction of gasoline is recycled in the second reactor, wherein the second reactor is a dense phase fluidized bed reactor, which can make the heavy fraction of gasoline fully react, thereby further improving the yield of light aromatics. In addition, the method disclosed in the present disclosure can also produce low-carbon olefins as by-products, further improving the utilization rate of raw materials.

[0027] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0029] Figure 1 The present invention is a schematic diagram of a method for catalytically cracking gasoline and then converting it to increase the production of light aromatics.

[0030] Figure 2 It is a schematic diagram of a specific embodiment of the cracking reaction unit used in the method of the present disclosure.

[0031] Figure 3 Schematic diagram of a second specific embodiment of a cracking reaction unit used in the method of the present disclosure.

[0032] Figure 4 Schematic diagram of a third specific embodiment of a cracking reaction unit used in the method of the present disclosure.

[0033] Figure 5 Schematic diagram of the cracking reaction unit used in Comparative Example 3 of the present disclosure.

[0034] Description of Reference Numerals

[0035] 1 heavy oil feedstock; 2 cracking reaction unit; 3 cracking reaction product; 4 product separation device; 5 light gasoline; 6 gasoline middle fraction; 7 gasoline heavy fraction; 8 other products; 9 aromatic separation device; 10 benzene product; 11 toluene product; 12 xylene product; 13 second reactor; 14 riser reactor; 15 fluidized bed reactor; 16 settler; 17 inclined tube to be regenerated; 18 regenerator; 19 second regeneration inclined tube; 20 first regeneration inclined tube; 21 regenerated flue gas; 22 fresh agent; 23 fresh agent; 24 riser reactor; 40 cracking settler; 41 lightening settler; 42 cracking inclined tube to be regenerated; 43 third regeneration inclined tube; 44 lightening inclined tube to be regenerated; 45 fourth regeneration inclined tube; 46 cracking regenerator; 47 lightening regenerator; 48 lightening reaction product; 49 cracking reaction product; 50 regeneration inclined tube. DETAILED DESCRIPTION

[0036] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0037] like Figure 1 As shown, the present disclosure provides a method for catalytic cracking gasoline reconversion to increase the production of light aromatics, the method comprising: allowing a heavy oil feedstock to enter a first reactor of a cracking reaction unit and contact it with a cracking catalyst to perform a cracking reaction to obtain a cracking reaction product; subjecting the cracking reaction product to product separation treatment to obtain other products, light gasoline, a gasoline middle fraction and a gasoline heavy fraction; subjecting the gasoline middle fraction to aromatic separation treatment to obtain a benzene product, a toluene product and a xylene product; allowing the gasoline heavy fraction to enter a second reactor of the cracking reaction unit and contact it with a lightening catalyst to perform a lightening reaction to obtain a lightening reaction product; subjecting the lightening reaction product to the product separation treatment with the cracking reaction product; or, returning the lightening reaction product to the first reactor; the second reactor is a dense phase fluidized bed reactor, and the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; The catalyst activity of the catalyst in the second reactor is 50-99.

[0038] Through the above technical scheme, the present disclosure can efficiently convert heavy aromatics in heavy oil cracking products into light aromatics by subjecting heavy oil raw materials to catalytic cracking reactions. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatics loss caused by the production of light aromatics by hydroprocessing; on the other hand, it can solve the problem of low-value heavy aromatics being difficult to utilize, and achieve efficient utilization of resources. In addition, the heavy fraction of gasoline is recycled in the second reactor, wherein the second reactor is a dense phase fluidized bed reactor, which can make the heavy fraction of gasoline fully react, thereby further improving the yield of light aromatics. In addition, the method disclosed in the present disclosure can also produce low-carbon olefins as by-products, further improving the utilization rate of raw materials.

[0039] In one embodiment, the heavy oil feedstock used in the present disclosure has an initial distillation point of 200-400°C, preferably 250-350°C; and a final distillation point of 450-600°C, preferably 500-550°C.

[0040] In a preferred embodiment, the heavy oil feedstock includes petroleum hydrocarbons and / or other mineral oils; wherein the petroleum hydrocarbons are selected from one or more of vacuum wax oil, atmospheric wax oil, coker wax oil, deasphalted oil, vacuum residue oil, atmospheric residue oil, extracted oil and inferior recycled oil; wherein the other mineral oils are selected from one or more of coal liquefaction oil, oil sand oil and shale oil.

[0041] In one embodiment, the cracking catalyst described in the present disclosure comprises zeolite, inorganic oxide and optional clay; based on the total weight of the cracking catalyst, the content of the zeolite is 5-70% by weight, preferably 30-60% by weight; the content of the inorganic oxide is 1-95% by weight, preferably 30-70% by weight; the content of the clay is 1-50% by weight, preferably 5-40% by weight.

[0042] Wherein, the zeolite of the cracking catalyst includes large-pore zeolite and optional medium-pore zeolite; based on the total weight of the zeolite in the cracking catalyst, the content of large-pore zeolite is 30-99% by weight, preferably 40-80% by weight; the content of medium-pore zeolite is 1-70% by weight, preferably 20-60% by weight.

[0043] In one embodiment, the light-weight catalyst comprises zeolite, inorganic oxide and optional clay; based on the total weight of the light-weight catalyst, the content of the zeolite is 5-70% by weight, preferably 30-60% by weight; the content of the inorganic oxide is 1-95% by weight, preferably 30-70% by weight; the content of the clay is 1-50% by weight, preferably 5-40% by weight.

[0044] Among them, the zeolite of the light-weight catalyst includes large-pore zeolite and medium-pore zeolite; based on the total weight of the zeolite in the light-weight catalyst, the content of large-pore zeolite is 50-99% by weight, preferably 60-80% by weight; the content of medium-pore zeolite is 1-50% by weight, preferably 20-40% by weight.

[0045] The zeolite includes large-pore zeolite and optional medium-pore zeolite; the medium-pore zeolite is preferably ZSM zeolite; the large-pore zeolite is preferably one or more of β zeolite and Y zeolite.

[0046] Wherein, the inorganic oxide is silicon dioxide and / or aluminum oxide; and the clay is kaolin and / or halloysite.

[0047] Wherein, the cracking catalyst and the light-weighting catalyst also contain rare earth elements respectively. The rare earth elements used in the present disclosure are conventionally selected in the art, and this application does not make special requirements. Preferably, rare earth elements are present in the zeolite of the cracking catalyst and the light-weighting catalyst. Further preferably, the rare earth elements in the cracking catalyst and the light-weighting catalyst are mainly derived from Y-type zeolite modified with rare earth elements. In this embodiment, adding rare earth elements to the cracking catalyst and the light-weighting catalyst can enhance the catalytic activity of the cracking catalyst and the light-weighting catalyst, thereby facilitating enhancing the activity of the cracking reaction and the light-weighting reaction.

[0048] In a specific embodiment, the method for rare earth modification of Y-type zeolite includes: contacting NaY molecular sieve with rare earth solution or a mixed solution of rare earth solution and ammonium salt, filtering, washing and drying, and then performing a first calcination treatment to obtain rare earth sodium Y molecular sieve; then slurrying the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering and then mixing it with a rare earth solution, and adjusting the pH value of the slurry to 5-6 with ammonia water, filtering or not filtering, drying, and performing a second calcination treatment to obtain a rare earth Y-type molecular sieve.

[0049] In one embodiment, according to actual production needs, the lightening catalyst and cracking catalyst used in the present disclosure may be the same or different.

[0050] In one embodiment, the method for preparing the cracking catalyst and the lightening catalyst comprises:

[0051] The inorganic oxide source, clay and decationized 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 above slurry is adjusted to 1-4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, etc.), and an aging treatment is performed at this pH value, wherein the temperature of the aging treatment is 20-80°C and the time is 0-2h; then the inorganic oxide is added, stirred for 0.5-1.5 hours to form a colloid, and zeolite is added thereto to form a catalyst slurry, based on the total weight of the solid phase in the catalyst slurry, the content of zeolite is 5-70% by weight, the content of clay is 1-50% by weight, and the content of inorganic oxide is 1-95% by weight, wherein, based on the total weight of the zeolite, the content of large-pore zeolite in the zeolite is 30-99% by weight, and the content of medium-pore zeolite is 1-70% by weight; after continuing to stir, spray drying is performed to form a microsphere catalyst. The microsphere catalyst is then calcined at 400-600° C. for 0.5-2 hours, and then washed with ammonium sulfate at 30-80° C. until the sodium oxide content is less than 0.25% by weight, and then rinsed with deionized water and filtered, and then dried at 100-200° C. to obtain a cracking catalyst; wherein the weight of ammonium sulfate: the weight of the microsphere catalyst: the weight of water = (0.1-1): 1: (5-15).

[0052] In one embodiment, the cracking reaction unit used in the present disclosure includes a first reactor, a second reactor 13, a regenerator 18 and a settler 16; wherein the number of regenerators 18 and settlers 16 can be flexibly selected according to actual production needs. For example, the number of regenerators 18 and settlers 16 used in the present application can be independently 1 or 2.

[0053] The reactor type of the second reactor 13 is a dense phase fluidized bed reactor, and the reactor type of the first reactor is a dense phase fluidized bed reactor, a dilute phase transport bed reactor, and a composite reactor consisting of a dense phase fluidized bed reactor and a dilute phase transport bed reactor. The reactor type of the dense phase fluidized bed reactor used in the present disclosure is a bubbling bed reactor, a turbulent bed reactor, or a fast bed reactor; the dilute phase transport bed reactor is a riser reactor.

[0054] In a preferred embodiment, the first reactor is a combination of a riser reactor 14 and a fluidized bed reactor 15 , wherein the riser reactor 14 and the fluidized bed reactor 15 are arranged in series, and the fluidized bed reactor 15 is located downstream of the riser reactor 14 .

[0055] The bed density of the dense phase fluidized bed reactor is preferably 300-500 kg / m 3 ; The bed linear velocity is 0.1-4m / s, preferably 0.4-2m / s.

[0056] The first reactor and the second reactor 13 may be arranged in parallel or in series. It should be noted that the connection method of the first reactor and the second reactor 13 may be selected according to the cracking catalyst and the lightening catalyst.

[0057] In one embodiment, when the lightening catalyst and the cracking catalyst are the same, there is no need to consider the catalyst mixing problem, therefore, the cracking reaction unit includes a regenerator 18, a settler 16, a riser reactor 14, a fluidized bed reactor 15 and a second reactor 13, and the first reactor and the second reactor 13 are arranged in series. When the lightening catalyst and the cracking catalyst are different, the cracking catalyst and the lightening catalyst need to be separated, therefore, the cracking reaction unit includes two regenerators, namely a cracking regenerator 46 and a lightening regenerator 47, two settlers, namely a cracking settler 40 and a lightening settler 41, a riser reactor 14, a fluidized bed reactor 15 and the second reactor 13, wherein the riser reactor 14 and the fluidized bed reactor 15 are connected in series, and the first reactor and the second reactor 13 are arranged in parallel.

[0058] In a specific embodiment, when the first reactor and the second reactor 13 are arranged in series, the first reactor is arranged downstream of the second reactor 13, so that the product obtained by the second reactor 13 can enter the first reactor to continue the reaction.

[0059] The first reactor is connected in series with the settler 16 so that the materials obtained by the reaction in the first reactor can enter the settler 16 for separation. In addition, the first reactor and the settler 16 can be coaxially arranged or separately arranged according to actual use. Preferably, the first reactor and the settler 16 are coaxially arranged.

[0060] According to actual production needs, the first reactor and the second reactor 13 can be coaxially arranged or separately arranged.

[0061] In one embodiment, when the first reactor and the second reactor 13 are arranged in series, the outlet material of the fluidized bed reactor 15 is separated through a settler 16 to obtain a catalyst to be regenerated and the cracking reaction product; the catalyst to be regenerated enters a regenerator 18 for regeneration treatment to obtain a regenerated catalyst; the regenerated catalyst is returned to the riser reactor 14 through a first regeneration inclined pipe 20 and / or the regenerated catalyst is returned to the second reactor 13 through a second regeneration inclined pipe 19.

[0062] In a specific implementation manner, Figure 2As shown, when the first reactor and the second reactor 13 are coaxially arranged, a catalyst outlet to be regenerated is provided on the side wall of the settler 16, a catalyst inlet to be regenerated, a first regeneration agent outlet and a second regeneration agent outlet are provided on the side wall of the regenerator 18, a first regeneration agent inlet and a heavy oil feedstock inlet are provided on the riser reactor 14, and a second regeneration agent inlet, a gasoline heavy fraction inlet, a fresh agent inlet and a pre-lifting medium inlet are provided on the second reactor 13; the catalyst outlet to be regenerated of the settler 16 is connected to the catalyst inlet to be regenerated of the regenerator through the inclined tube 17; the first regeneration agent outlet of the regenerator 18 is connected to the first regeneration agent inlet of the riser reactor 14 through the first regeneration inclined tube 20, and the second regeneration agent outlet of the regenerator 18 is connected to the second regeneration agent inlet of the second reactor 13 through the second regeneration inclined tube 19; the heavy oil feedstock inlet of the riser reactor 14 is connected to the heavy oil feedstock source; the pre-lifting medium inlet of the second reactor 13 is used to communicate with the pre-lifting medium source, and the fresh agent inlet of the second reactor 13 is used to communicate with the fresh agent source.

[0063] A fresh agent inlet is provided on the second regeneration inclined tube 19 , and the fresh agent inlet is used to communicate with a fresh agent source, so that the fresh agent can enter the second reactor 13 through the second regeneration inclined tube 19 .

[0064] In order to flexibly adjust the flow rates of the feed and discharge of the regenerator 18 , flow regulating valves are provided on the inclined pipe to be regenerated 17 , the first regeneration inclined pipe 20 and the second regeneration inclined pipe 19 .

[0065] In another specific embodiment, Figure 3 As shown, when the first reactor and the second reactor 13 are separately arranged, an outlet for the catalyst to be regenerated is provided on the side wall of the settler 16, an inlet for the catalyst to be regenerated, a first regeneration agent outlet and a second regeneration agent outlet are provided on the side wall of the regenerator 18, a first regeneration agent inlet, a light reaction product inlet, a heavy oil feedstock inlet and a pre-lifting medium inlet are provided on the riser reactor 14, and a second regeneration agent inlet, a gasoline heavy fraction inlet and a light reaction product outlet are provided on the second reactor 13; the outlet for the catalyst to be regenerated of the settler 16 is connected to the inlet for the catalyst to be regenerated of the regenerator 18 through the inclined tube 17; the regenerator 1 The first regeneration agent outlet of 8 is connected with the first regeneration agent inlet of the riser reactor 14 through the first regeneration inclined tube 20, and the second regeneration agent outlet of the regenerator is connected with the second regeneration agent inlet of the second reactor 13 through the second regeneration inclined tube 19; the light reaction product outlet of the second reactor 13 is connected with the light reaction product inlet of the riser reactor 14; the heavy oil feedstock inlet of the riser reactor 14 is connected with the heavy oil feedstock source; the pre-lifting medium inlet of the riser reactor 14 is used to be connected with the pre-lifting medium source; the gasoline heavy fraction inlet of the second reactor 13 is connected with the gasoline heavy fraction outlet of the product separation device 4.

[0066] A fresh agent inlet is provided at the bottom of the second regeneration inclined tube 19 and / or the second reactor 13 , and the two fresh agent inlets are connected to a fresh agent source so that the fresh agent can enter the second reactor 13 .

[0067] In one embodiment, if the cracking catalyst and the lightening catalyst are different, the first reactor and the second reactor 13 need to be separately arranged, and the first reactor is connected in series with the cracking settler 40 so that the material obtained by the reaction in the first reactor can enter the cracking settler 40; the second reactor 13 is integrated with the lightening settler 41 so that the material obtained by the reaction in the second reactor 13 can enter the lightening settler 41. In addition, the first reactor and the second reactor 13 are respectively equipped with a regenerator.

[0068] In this embodiment, the outlet material of the fluidized bed reactor 15 is separated by a cracking settler 40 to obtain a cracking catalyst to be regenerated and the cracking reaction product; the cracking catalyst to be regenerated enters a cracking regenerator 46 for regeneration treatment to obtain a regenerated cracking catalyst; the regenerated cracking catalyst is returned to the riser reactor 14 through a third regeneration inclined pipe 43; the outlet material of the second reactor 13 is separated by a lightening settler 41 to obtain a lightened catalyst to be regenerated and the lightening reaction product; the lightened catalyst to be regenerated enters a lightening regenerator 47 for regeneration treatment to obtain a regenerated lightened catalyst; the regenerated lightened catalyst is returned to the second reactor 13 through a fourth regeneration inclined pipe 45.

[0069] In a specific implementation manner, Figure 4 As shown, a catalyst outlet and a cracking reaction product outlet are provided on the side wall of the cracking settler 40; the riser reactor 14 includes a pre-lifting medium inlet, a heavy oil feedstock inlet and a third regeneration agent inlet; the cracking regenerator 46 includes a spent catalyst inlet and a third regeneration agent outlet; the spent catalyst outlet of the cracking settler 40 is connected with the spent catalyst inlet of the cracking regenerator 46 through a cracking spent catalyst inclined pipe 42; the third regeneration agent outlet of the cracking regenerator 46 is connected with the third regeneration agent inlet of the riser reactor 14 through a third regeneration inclined pipe 43; the pre-lifting medium inlet of the riser reactor 14 is used to communicate with a pre-lifting medium source; the heavy oil feedstock inlet of the riser reactor 14 is used to communicate with a heavy oil feedstock source.

[0070] A spent agent outlet and a spent reaction product outlet are provided on the side wall of the lightening settler 41; the second reactor 13 includes a pre-lifting medium inlet, a gasoline heavy fraction inlet and a fourth regeneration agent inlet; the lightening regenerator 47 includes a spent agent inlet and a fourth regeneration agent outlet; the spent agent outlet of the lightening settler 41 is connected to the spent agent inlet of the lightening regenerator 47 through a lightening spent agent inclined pipe 44; the fourth regeneration agent outlet of the lightening regenerator 47 is connected to the fourth regeneration agent inlet of the second reactor 13 through a fourth regeneration inclined pipe 45; the pre-lifting medium inlet of the second reactor 13 is used to be connected to a pre-lifting medium source; the gasoline heavy fraction inlet of the second reactor 13 is used to be connected to the gasoline heavy fraction outlet of the product separation device 4.

[0071] The cracking reaction product outlet pipeline of the cracking settler 40 and the lightening reaction product outlet pipeline of the lightening settler 41 are merged into a cracking reaction product bus, so that the mixed materials can enter the product separation device 4 .

[0072] A fresh agent inlet is provided on the fourth regeneration inclined tube 45 and / or at the bottom of the second reactor 13 , and the two fresh agent inlets are connected to a fresh agent source so that the fresh agent can enter the second reactor 13 .

[0073] In one embodiment, a steam inlet is further provided at the inlet of the riser reactor 14 for communicating with a steam source so that steam can enter the riser reactor 14 .

[0074] In one embodiment, in order to further improve the separation effect, cyclone separators are respectively provided on the upper parts of the settler 16, the regenerator 18, the cracking settler 40, the cracking regenerator 46, the lightening settler 41 and the lightening regenerator 47. The cyclone separators used in the present disclosure are conventionally selected in the art, and the present application does not make any requirements. As for the number of cyclone separators, it can be flexibly selected according to actual production needs. Preferably, the number of cyclone separators is 2.

[0075] Among them, an air collecting chamber is provided at the top of the settler 16, the cracking settler 40 and the lightening settler 41, the inlet of the air collecting chamber is connected with the cracking reaction product outlet of the cyclone separator, and the outlet of the air collecting chamber is used to be connected with the cracking reaction product outlet, so that the cracking reaction product can be buffered by the air collecting chamber and then leave the system through the outlet.

[0076] Therein, an oxygen-containing gas distributor is further provided inside the regenerator 18, the cracking regenerator 46 and the lightening regenerator 47, and the inlet of the oxygen-containing gas distributor extends to the outside of each regenerator to form an oxygen-containing gas inlet.

[0077] In one embodiment, a light gasoline inlet may be provided at the lower portion of the fluidized bed reactor 15 so that the light gasoline can be returned to the cracking reaction unit for further reaction.

[0078] In one embodiment, the pre-lifting medium used in the present disclosure is a conventional choice in the art, and this application does not make any special requirements. For example, the pre-lifting medium may be water vapor and / or dry gas.

[0079] In one embodiment, using Figure 2 The method for carrying out cracking reaction in the device comprises: allowing the fresh catalyst 23, the second regenerated catalyst and the gasoline heavy fraction 7 to enter the second reactor 13 under the action of the pre-lifting medium for a lightening reaction to obtain a lightening reaction product; allowing the lightening reaction product, the first regenerated catalyst and the heavy oil feedstock 1 to enter the first reactor for a cracking reaction to obtain a mixture of cracking reaction products and catalyst to be regenerated, wherein most of the catalyst to be regenerated moves downward under the action of gravity, and the cracking reaction products and a small part of the catalyst to be regenerated in the mixture move upward and enter a cyclone separator for separation, so that a small part of the catalyst to be regenerated returns to the settler 16, and the cracking reaction products exit the settler 16 through the gas collecting chamber. The catalyst to be regenerated is passed through the inclined tube 17 into the regenerator 18, and is regenerated under the action of the oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 21, and the regenerated flue gas 21 is discharged; the regenerated catalyst is divided into a first regenerated catalyst and a second catalyst, the first regenerated catalyst is returned to the riser reactor 14 through the first regeneration inclined tube 20, and the second regenerated catalyst is returned to the second reactor 13 after being mixed with the fresh agent 22 through the second regeneration inclined tube 19.

[0080] In another embodiment, using Figure 3 The method for carrying out cracking reaction in the device includes: allowing the light reaction product, the first regenerated catalyst and the heavy oil feedstock 1 to enter the first reactor under the action of the pre-lifting medium for cracking reaction to obtain a mixture of cracking reaction products and the catalyst to be regenerated, wherein most of the catalyst to be regenerated moves downward under the action of gravity, and the cracking reaction product and a small part of the catalyst to be regenerated in the mixture move upward and enter the cyclone separator for separation, so that the small part of the catalyst to be regenerated returns to the settler 16, and the cracking reaction product 3 exits the settler 16 through the gas collecting chamber. The catalyst to be regenerated is passed through the inclined tube 17 into the regenerator 18, and is regenerated under the action of oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 21, and the regenerated flue gas 21 is discharged; the regenerated catalyst is divided into a first regenerated catalyst and a second catalyst, and the first regenerated catalyst is returned to the riser reactor 14 through the first regeneration inclined tube 20; the second regenerated catalyst is passed through the second regeneration inclined tube 19 into the second reactor 13 and mixed with the gasoline heavy fraction 7 and the fresh agent to obtain a light reaction product, and the light reaction product is returned to the riser reactor 14 through the outlet pipeline.

[0081] In another embodiment, using Figure 4 The method for carrying out cracking reaction in the device includes: allowing the heavy oil feedstock 1 and the third regenerated catalyst to enter the riser reactor 14 under the action of the pre-lifting medium for cracking reaction to obtain a mixture containing the cracking catalyst to be grown and the cracking reaction product; allowing the vast majority of the cracking catalyst to be grown in the mixture to move downward under the action of gravity, and the cracking reaction product and a small portion of the cracking catalyst to be grown in the mixture to move upward and enter the cyclone separator for separation, so that a small portion of the cracking catalyst to be grown returns to the cracking settler 40, and the cracking reaction product exits the cracking settler 40 through the gas collecting chamber. Allowing the cracking catalyst to be grown to enter the cracking regenerator 46 through the cracking inclined pipe 42, and undergo regeneration treatment under the action of the oxygen-containing gas to obtain the third regenerated catalyst and the regenerated flue gas 21; allowing the regenerated flue gas 21 to be discharged, and allowing the third regenerated catalyst to return to the riser reactor 14 through the third regeneration inclined pipe 43. The fresh catalyst 23, the fourth regenerated catalyst and the heavy fraction of gasoline are allowed to enter the second reactor 13 under the action of the pre-lifting medium for a lightening reaction, and a mixture containing a lightening reaction product and a lightening catalyst to be regenerated is obtained; the vast majority of the lightening catalyst to be regenerated in the mixture moves downward under the action of gravity, and the lightening reaction product and a small portion of the lightening catalyst to be regenerated in the mixture move upward and enter the cyclone separator for separation, so that a small portion of the lightening catalyst to be regenerated returns to the lightening settler 41, and the cracking reaction product exits the system through the gas collecting chamber. The lightening catalyst to be regenerated enters the lightening regenerator 47 through the lightening regenerator inclined pipe 44, and is regenerated under the action of oxygen-containing gas to obtain a fourth regenerated catalyst and regenerated flue gas 21; the regenerated flue gas 21 is discharged, and the fourth regenerated catalyst is mixed with the fresh catalyst 22 through the fourth regeneration inclined pipe 45 and then returns to the second reactor 13; the cracking reaction product 49 and the lightening reaction product 48 are mixed and then enter the product separation device 4.

[0082] In the above embodiment, the fresh agent is a fresh cracking catalyst or a light-weighted catalyst. When the cracking catalyst and the light-weighted catalyst are the same, the fresh agent can be a fresh cracking catalyst or a light-weighted catalyst; when the cracking catalyst and the light-weighted catalyst are different, the fresh agent is a fresh light-weighted catalyst.

[0083] In one embodiment, the method further comprises adding a fresh agent into the second reactor 13; wherein the ratio of the weight of the fresh agent to the total weight of the catalyst used in the cracking reaction unit is less than 0.2, preferably 0.02-0.18, and further preferably 0.05-0.12.

[0084] In one embodiment, the catalyst activity disclosed herein refers to the micro-reaction activity index measured by the method of NB / SH / T 0952-2017.

[0085] In one embodiment, the reaction conditions of the cracking reaction include: reaction temperature of 555-720°C, preferably 580-700°C, and more preferably 600-640°C; reaction time of 1-10s, preferably 1.5-6s, and more preferably 2-4s; reaction pressure of 130-450kPa, preferably 150-400kPa, and more preferably 180-300kPa; catalyst-oil ratio of (1-100):1, preferably (10-50):1, and more preferably (15-20):1; catalyst activity of 40-90, preferably 50-80; and more preferably 55-70.

[0086] In one embodiment, the reaction conditions of the lightening reaction include: reaction temperature of 530-730°C, preferably 560-680°C, and more preferably 610-650; reaction time of 1-20 seconds, preferably 3-15s, and more preferably 3.5-10s; reaction pressure of 130-450kPa, preferably 150-400kPa, and more preferably 180-300kPa; catalyst-oil ratio of (1-100):1, preferably (5-30):1, and more preferably (15-25):1; catalyst activity is more preferably 60-90.

[0087] In one embodiment, the product separation and processing device and method described in the present disclosure are conventionally selected in the art, and the present application does not make any requirements. It only needs to be able to separate the cracking reaction products into other products, light gasoline, gasoline middle fractions and gasoline heavy fractions. For example, the product separation and processing of the present application includes: subjecting the cracking reaction products to a first separation to obtain the light gasoline, heavy gasoline and the other products; subjecting the heavy gasoline to a second separation to obtain the gasoline middle fraction and the gasoline heavy fraction.

[0088] Among them, the main components of other products include H2-C4 gas components, diesel and heavy oil fractions; the light gasoline is mainly composed of C4-C5 components; the gasoline intermediate fraction is mainly composed of C6-C8 components; the gasoline heavy fraction is mainly composed of C9+ components.

[0089] The initial boiling point of the light gasoline is 20-40°C; the distillation cut point between the light gasoline and the heavy gasoline is 80-100°C; and the distillation cut point between the gasoline middle fraction and the gasoline heavy fraction is 120-150°C.

[0090] In one embodiment, the apparatus and method for separation and treatment of aromatics are conventionally selected in the art, and this application does not make any requirements. It only needs to be able to separate the intermediate fraction of gasoline into benzene products, toluene products and xylene products. For example, this application uses aromatic extraction technology for separation, and the aromatic raffinate can be returned to the catalytic cracking reactor to continue the reaction, and its refining position can be the same as that of light gasoline.

[0091] In one embodiment, the method further includes returning part or all of the light gasoline to the cracking reaction unit 2 for reaction, and the return position of the light gasoline can be flexibly selected according to actual production needs; wherein, the ratio of the weight of the light gasoline returned to the catalytic cracking reaction unit 2 to the total weight of the light gasoline needs to be flexibly selected according to actual production needs, and this application does not make any special requirements.

[0092] The following examples will further illustrate the present invention, but are not intended to limit the present invention. The heavy oil raw material used in the examples and comparative examples is heavy oil, wherein the properties of the heavy oil are shown in Table 1.

[0093] Table 1 Properties of heavy oil feedstock

[0094]

[0095] Preparation Example 1

[0096] The preparation method of rare earth Y type molecular sieve (REY) comprises: contacting NaY molecular sieve with rare earth solution or a mixed solution of rare earth solution and ammonium salt, filtering, washing with water, drying, and then performing a first roasting treatment to obtain rare earth sodium Y molecular sieve; then slurrying the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering and then mixing it with a rare earth solution, and adjusting the pH value of the slurry to 6 with ammonia water, filtering or not filtering, drying, and performing a second roasting treatment to obtain rare earth Y type molecular sieve (REY).

[0097] The method for preparing catalyst C1 includes: mixing aluminum sol and kaolin, and preparing them into a slurry with a solid content of 40% by weight with decationized water, stirring evenly, adjusting the pH of the slurry to 4 with hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, maintaining the pH value, adding aluminum sol after standing and aging at 60°C for 1 hour, stirring for 1 hour to form a colloid, adding ZSM-5 and rare earth Y-type molecular sieve (REY) to form a catalyst slurry (solid content is 35% by weight), wherein the weight of ZSM-5 molecular sieve: the weight of REY: the weight of kaolin: the weight of aluminum sol = 15:35:34:16, and continuing to stir and spray drying to prepare a microsphere catalyst. The microsphere catalyst was then calcined at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of the microsphere catalyst: the weight of water = 0.5:1:10) until the sodium oxide content was less than 0.25% by weight, followed by rinsing with deionized water and filtering, and then drying at 110°C to obtain catalyst C1.

[0098] Preparation Example 2

[0099] The preparation method of rare earth Y-type molecular sieve (REY) is the same as that of Preparation Example 1;

[0100] The method for preparing catalyst C2 includes: mixing aluminum sol and kaolin, and preparing them into a slurry with a solid content of 40% by weight with decationized water, stirring evenly, adjusting the pH of the slurry to 4 with hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, maintaining the pH value, adding aluminum sol after standing and aging at 60°C for 1 hour, stirring for 1 hour to form a colloid, adding ZSM-5 and rare earth Y-type molecular sieve (REY) to form a catalyst slurry (solid content is 35% by weight), wherein the weight of ZSM-5: the weight of REY: the weight of kaolin: the weight of aluminum sol = 5:45:34:16, and continuing to stir and spray drying to form a microsphere catalyst. The microsphere catalyst was then calcined at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of the microsphere catalyst: the weight of water = 0.5:1:10) until the sodium oxide content was less than 0.25% by weight, followed by rinsing with deionized water and filtering, and then drying at 110°C to obtain catalyst C2.

[0101] Test Example 1

[0102] The test is carried out according to the 460°C micro-reaction activity index determination method in NB / SH / T 0952-2017, and the obtained micro-reaction activity index is the catalytic activity of the cracking catalyst.

[0103] Example 1

[0104] use Figure 1 systems and Figure 2 The method for increasing the production of light aromatics by catalytic cracking gasoline reconversion in the cracking reaction unit 2 comprises:

[0105] The light reaction product from the second reactor, the first regenerated catalyst and the heavy oil feedstock 1 are introduced into the first reactor for cracking reaction to obtain a mixture containing cracking reaction products and catalyst to be regenerated, wherein most of the catalyst to be regenerated moves downward under the action of gravity, and the cracking reaction product and a small part of the catalyst to be regenerated in the mixture move upward and enter the cyclone separator for separation, so that a small part of the catalyst to be regenerated is returned to the settler 16, and the cracking reaction product exits the settler 16 through the gas collecting chamber. The catalyst to be regenerated is introduced into the regenerator 18 through the inclined tube to be regenerated 17, and is regenerated under the action of oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 21, and the regenerated flue gas 21 is discharged; the regenerated catalyst is divided into a first regenerated catalyst and a second regenerated catalyst, the first regenerated catalyst is returned to the first reactor through the first regeneration inclined tube 20, and the second regenerated catalyst is returned to the second reactor 13 through the second regeneration inclined tube 19;

[0106] The cracking reaction product is allowed to enter the product separation device 4 for the first separation to obtain the other products 8, light gasoline 5 and heavy gasoline; the heavy gasoline is allowed to undergo a second separation to obtain a gasoline middle fraction 6 and a gasoline heavy fraction 7, wherein the initial boiling point of the light gasoline 5 is 30°C, the fraction cut point between the light gasoline 5 and the heavy gasoline is 75°C, and the fraction cut point between the gasoline middle fraction 6 and the gasoline heavy fraction 7 is 145°C; the gasoline middle fraction is allowed to enter the aromatic separation device 9 for aromatic separation treatment to obtain a benzene product 10, a toluene product 11 and a xylene product 12; the fresh agent, the second regenerated catalyst and the gasoline heavy fraction 7 are allowed to enter the second reactor 13 under the action of a pre-lifting medium (steam) to undergo a lightening reaction to obtain a lightening reaction product; the weight ratio of the fresh agent to the total weight of the catalyst used in the cracking reaction unit is 0.02:1; the other products are further separated to obtain dry gas, ethylene, liquefied petroleum gas, propylene and gasoline.

[0107] The reaction conditions and product properties are shown in Table 2.

[0108] Example 2

[0109] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the reaction temperature of the lightening reaction is 620° C. The reaction conditions and product properties are shown in Table 2.

[0110] Example 3

[0111] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the catalyst-to-oil ratio in the lightening reaction is 15:1. The reaction conditions and product properties are shown in Table 2.

[0112] Example 4

[0113] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as that in Example 1, except that Figure 4 The cracking reaction unit is used to carry out the cracking reaction, so that the source of the catalyst for the cracking reaction is all C1 regenerated catalyst. The reaction conditions and product properties are shown in Table 2.

[0114] Example 5

[0115] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the valve on the first regeneration inclined tube 20 is closed so that the source of the catalyst for the cracking reaction is all C1 spent catalyst. The reaction conditions and product properties are shown in Table 2.

[0116] Example 6

[0117] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as that in Example 1, except that Figure 4 The cracking reaction unit is used for cracking reaction, and the catalyst for the lightening reaction is replaced with an equal weight of catalyst C2. The reaction conditions and product properties are shown in Table 2.

[0118] Example 7

[0119] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the bed density of the dense phase fluidized bed reactor is 250 kg / m 3 The reaction conditions and product properties are shown in Table 2.

[0120] Example 8

[0121] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the light gasoline is not returned to the cracking reaction unit 2 for further reaction. The reaction conditions and product properties are shown in Table 2.

[0122] Example 9

[0123] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the reaction conditions of the cracking reaction are different. The reaction conditions and product properties are shown in Table 3.

[0124] Example 10

[0125] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that no fresh agent is added during the lightening reaction in the second reactor. The reaction conditions and product properties are shown in Table 3.

[0126] Embodiment 11

[0127] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the ratio of the weight of the fresh catalyst to the total weight of the catalyst used in the cracking reaction unit is 0.16:1. The reaction conditions and product properties are shown in Table 3.

[0128] Comparative Example 1

[0129] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the light gasoline and the heavy gasoline fraction are not returned to the cracking reaction unit 2 for further reaction. The reaction conditions and product properties are shown in Table 3.

[0130] Comparative Example 2

[0131] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as in Example 1, except that the cracking catalyst and the lightening catalyst are replaced by equal weights of CDOS, wherein the CDOS catalytic cracking catalyst is purchased from Changling Catalyst Co., Ltd. The reaction conditions and product properties are shown in Table 3.

[0132] Comparative Example 3

[0133] The method for catalytic cracking gasoline reconversion to increase the production of light aromatics is the same as that in Example 1, except that Figure 5 The cracking reaction unit is used for cracking reaction, that is, the second reactor is the riser reactor 24, and the regenerated catalyst is returned to the riser reactor 24 through the regeneration inclined pipe 50. The reaction conditions and product properties are shown in Table 3.

[0134] Table 2 Reaction conditions and product properties in the examples

[0135]

[0136]

[0137] Table 3 Reaction conditions and product properties in Examples and Comparative Examples

[0138]

[0139]

[0140] As can be seen from the table, according to the comparison of the data of Examples 1-11 and Comparative Examples 1-3, it can be seen that the technical solution of the present disclosure can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatics loss caused by the production of light aromatics by hydroprocessing. According to the comparison of the data in Example 1, Example 2 and Example 3, the lightening reaction of the present application is carried out under the conditions of a temperature of 610 to 650°C and a catalyst-oil ratio of (15-25): 1. Non-hydrogen catalytic cracking of the heavy fraction of gasoline can obtain a higher BTX yield; According to the comparison of the data in Example 1, Example 6 and Comparative Example 2, when the catalytic activity of the catalyst in the second reactor meets 50-99, a higher BTX yield can be obtained; According to the comparison of the data in Example 1, Example 7 and Comparative Example 3, the bed density of the second reactor is 180-700kg / m3 , a higher BTX yield can be obtained, and the bed density of the dense phase fluidized bed reactor is 300-500kg / m 3 , which can further improve the yield of BTX; according to the comparison of the data in Example 1 and Example 8, returning the light gasoline to the cracking reaction unit for recycling can further improve the yield of BTX; according to the comparison of the data in Example 1, Example 10 and Example 11, it can be seen that adding a fresh agent during the lightening reaction can obtain a higher yield of BTX.

[0141] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0142] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0143] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for catalytic cracking gasoline reconversion to increase the production of light aromatics, characterized in that: The method includes: The heavy oil feedstock is brought into the first reactor of the cracking reaction unit to contact with the cracking catalyst for cracking reaction to obtain a cracking reaction product; The cracking reaction product is subjected to product separation treatment to obtain other products, light gasoline, gasoline middle fraction and gasoline heavy fraction; the gasoline middle fraction is subjected to aromatic separation treatment to obtain a benzene product, a toluene product and a xylene product; The gasoline heavy fraction is allowed to enter the second reactor of the cracking reaction unit to contact with the lightening catalyst to perform a lightening reaction to obtain a lightening reaction product; subjecting the lightening reaction product and the cracking reaction product to the product separation treatment; or, returning the lightening reaction product to the first reactor; The second reactor is a dense phase fluidized bed reactor, and the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; The catalyst activity of the catalyst in the second reactor is 50-99.

2. The method according to claim 1, characterized in that The heavy oil feedstock includes petroleum hydrocarbons and / or other mineral oils; The petroleum hydrocarbon is selected from one or more of vacuum wax oil, atmospheric wax oil, coker wax oil, deasphalted oil, vacuum residue oil, atmospheric residue oil, extracted oil and inferior recycled oil; The other mineral oil is selected from one or more of coal liquefaction oil, oil sand oil and shale oil.

3. The method according to claim 1, characterized in that The reaction conditions of the cracking reaction include: reaction temperature of 555-720°C, preferably 580-700°C; reaction time of 1-10s, preferably 1.5-6s; catalyst-oil ratio of (1-100):1, preferably (10-50):1; The reaction conditions of the lightening reaction include: reaction temperature of 530-730° C., preferably 560-680° C.; catalyst-oil ratio of (1-100):1, preferably (5-30):1; catalyst activity of 60-90.

4. The method according to claim 1, characterized in that: The cracking catalyst and the lightening catalyst are the same or different; The cracking catalyst and the lightening catalyst independently comprise zeolite, inorganic oxide and optional clay; based on the total weight of the catalyst, the content of the zeolite is 5-70% by weight, the content of the inorganic oxide is 1-95% by weight, and the content of the clay is 1-50% by weight.

5. The method according to claim 4, characterized in that The zeolite of the cracking catalyst includes large-pore zeolite and optional medium-pore zeolite; based on the total weight of the zeolite in the cracking catalyst, the content of the large-pore zeolite is 30-99% by weight, and the content of the medium-pore zeolite is 1-70% by weight; The zeolite of the light-weight catalyst includes large-pore zeolite and medium-pore zeolite; based on the total weight of the zeolite in the light-weight catalyst, the content of the large-pore zeolite is 50-99% by weight, and the content of the medium-pore zeolite is 1-50% by weight.

6. The method according to claim 5, characterized in that The medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of β zeolite and Y zeolite; The inorganic oxide includes silicon dioxide and / or aluminum oxide; The clay is kaolin and / or halloysite.

7. The method according to claim 6, characterized in that The cracking catalyst and the lightening catalyst contain rare earth elements respectively. Preferably, the large-pore zeolite is a Y-type zeolite modified by rare earth elements.

8. The method according to claim 1, characterized in that The first reactor is a combination of a riser reactor and a fluidized bed reactor.

9. The method according to claim 1, characterized in that: The first reactor and the second reactor are arranged in parallel or in series; When the first reactor and the second reactor are arranged in series, the first reactor is arranged downstream of the second reactor.

10. The method according to claim 1, characterized in that The cracking reaction unit also includes a regenerator; The method further comprises separating the outlet material of the first reactor to obtain spent catalyst and the cracking reaction product; Allowing the catalyst to be regenerated to enter the regenerator for regeneration treatment to obtain a regenerated catalyst; The regenerated catalyst is returned to the first reactor through a first regeneration inclined tube and / or the regenerated catalyst is returned to the second reactor through a second regeneration inclined tube; or, The outlet material of the first reactor is separated to obtain the raw cracking catalyst and the cracking reaction product; The outlet material of the second reactor is separated to obtain the light-weight catalyst to be produced and the light-weight reaction product; The regenerated cracking catalyst and the regenerated light-weight catalyst are respectively introduced into the regenerator for regeneration treatment to obtain a regenerated cracking catalyst and a regenerated light-weight catalyst; The regenerated cracking catalyst is returned to the first reactor through the third regeneration inclined tube, and the regenerated lightened catalyst is returned to the second reactor through the fourth regeneration inclined tube.

11. The method according to claim 10, characterized in that A fresh agent inlet is provided on the second regeneration inclined tube and / or at the bottom of the second reactor; or, A fresh agent inlet is provided on the fourth regeneration inclined tube and / or at the bottom of the second reactor.

12. The method according to claim 1, characterized in that The product separation process comprises: The cracking reaction product is subjected to a first separation to obtain the other products, the light gasoline and the heavy gasoline; the heavy gasoline is subjected to a second separation to obtain the gasoline middle fraction and the gasoline heavy fraction.

13. The method according to claim 12, characterized in that The initial boiling point of the light gasoline is 20-40°C; the distillation cut point between the light gasoline and the heavy gasoline is 80-100°C; the distillation cut point between the gasoline middle fraction and the gasoline heavy fraction is 120-150°C.

14. The method according to claim 1, characterized in that The bed density of the dense phase fluidized bed reactor is 300-500 kg / m 3 , the bed linear speed is 0.4-2m / s.

15. The method according to claim 1, characterized in that The light gasoline is returned to the cracking reaction unit to undergo the cracking reaction.

16. The method according to claim 1, characterized in that The method further comprises adding a fresh agent into the second reactor; The ratio of the weight of the fresh agent to the total weight of the catalyst in the cracking reaction unit is 0.2 or less.

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