A method for increasing production of light aromatics by catalytic cracking gasoline reformation

Abstract

The present disclosure relates to a method for increasing production of light aromatics by catalytic cracking gasoline re-conversion, which can efficiently convert heavy aromatics in heavy oil cracking products into light aromatics by processing heavy oil raw materials through catalytic cracking reaction, on the one hand, can avoid the problems of high hydrogen consumption, harsh operating conditions and loss of aromatics caused by using hydrogenation treatment to produce light aromatics; on the other hand, can solve the problem of difficult utilization of low-value heavy aromatics, realize efficient utilization of resources. And, the gasoline heavy fraction is recycled in the second reactor, wherein the second reactor is a dense phase fluidized bed reactor, which can make the gasoline heavy fraction fully react, thereby further improving the yield of light aromatics. In addition, the method of the present disclosure can also produce low-carbon olefins as by-products, further improving the utilization rate of raw materials.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of petroleum chemical industry, in particular, to a method for increasing production of light aromatic hydrocarbons by catalytic cracking gasoline re-conversion. BACKGROUND

[0002] BTX (B is benzene, T is toluene, and X is xylene) is an important petrochemical basic product, and is an important raw material for synthesizing rubber, synthetic fibers and synthetic resins and various chemical products. Toluene and xylene can also be used as gasoline octane number additives. However, the production process of aromatic hydrocarbons is accompanied by the production of C9+ heavy aromatic hydrocarbons. At present, the production of C9+ heavy aromatic hydrocarbons is large, the value is low, and the utilization channels are limited, resulting in waste of resources. It is undoubtedly an effective method to fully utilize resources and improve enterprise quality and efficiency to convert C9+ heavy aromatic hydrocarbons into BTX.

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

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

[0005] CN200480040758.2 discloses a method for separate catalytic hydrodealkylation of hydrocarbons, wherein the hydrocarbons contain C8-C13 alkyl aromatic compounds, which are optionally mixed with C4-C9 aliphatic and cycloaliphatic 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 modified with at least one metal selected from groups IIB, VIB and VIII. This method can produce benzene+toluene with a yield of 75%.

[0006] CN200710043941.3 discloses a method for producing light aromatics and light alkanes from hydrocarbon feedstock, which reacts the hydrocarbon feedstock with a boiling point of 30-250°C in the presence of a zeolite catalyst containing Pt or Pd, the heavy aromatics in the hydrocarbon feedstock are dealkylated by hydrogenation and transalkylated with light aromatics, the light aromatics are isomerized to form a component rich in BTX (B is benzene, T is toluene, and X is xylene) light aromatics, and the non-aromatics are cracked by hydrogenation to form light alkanes. In a distillation column, the liquid phase products are separated into benzene, toluene, xylene, and C9+aromatics according to different boiling points, and the light alkanes are separated from the gas phase products. This method solves the technical problems of complex process, high cost, low utilization value of heavy aromatics and non-aromatics after separation in the traditional separation process of hydrocarbon feedstock.

[0007] CN200810043966.8 discloses a method for producing more benzene and xylene by hydrocracking of pyrolysis gasoline. The method reacts C7+pyrolysis gasoline feedstock in the presence of a catalyst, the heavy aromatics are dealkylated by hydrogenation and transalkylated with light aromatics, the light aromatics are isomerized to form a component rich in BTX light aromatics, 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 feed for further processing, and the light alkanes are separated from the gas phase products. This method solves the problems of low utilization value of heavy aromatics and non-aromatics after separation, and the presence of a large amount of toluene in the light aromatic product in the traditional process of pyrolysis gasoline.

[0008] As can be seen from the above-mentioned patent applications, the existing heavy aromatics lightening technology mostly adopts the method of fixed bed hydrodealkylation. However, the hydrogen consumption is high, the operating conditions are harsh, and the aromatics are lost in the hydrogenation process. Catalytic cracking has the characteristics of not consuming hydrogen and flexible operation, and catalytic cracking produces heavy aromatics while producing low-carbon olefins and light aromatics. SUMMARY

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

[0010] To achieve the above object, the present disclosure provides a method for increasing production of light aromatics by catalytic cracking gasoline re-conversion, which comprises: feeding a heavy oil raw material into a first reactor of a cracking reaction unit to contact with a cracking catalyst to perform a cracking reaction, to obtain a cracking reaction product; performing product separation treatment on the cracking reaction product to obtain other products, light gasoline, gasoline intermediate fraction and gasoline heavy fraction; performing aromatics separation treatment on the gasoline intermediate fraction to obtain benzene product, toluene product and xylene product; feeding the gasoline heavy fraction into a second reactor of the cracking reaction unit to contact with a lightening catalyst to perform a lightening reaction, to obtain a lightening reaction product; performing the product separation treatment on the lightening reaction product and the cracking reaction product; or returning the lightening reaction product to the first reactor; the second reactor is a dense phase fluidized bed reactor, 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 raw material comprises petroleum hydrocarbon and / or other mineral oil; the petroleum hydrocarbon is selected from one or more of vacuum wax oil, atmospheric wax oil, coking wax oil, deasphalted oil, vacuum residue, atmospheric residue, extracted oil and poor quality back-refined oil; the other mineral oil is selected from one or more of coal liquefied oil, oil sand oil and shale oil.

[0012] Optionally, the reaction conditions of the cracking reaction comprise: reaction temperature is 555-720℃, preferably 580-700℃; reaction time is 1-10s, preferably 1.5-6s; catalyst / oil ratio is (1-100):1, preferably (10-50):1; the reaction conditions of the lightening reaction comprise: reaction temperature is 530-730℃, preferably 560-680℃; catalyst / oil ratio is (1-100):1, preferably (5-30):1; catalyst activity is 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, inorganic oxide and optional clay; the content of the zeolite is 5-70% by weight, the content of the inorganic oxide is 1-95% by weight, and the content of the clay is 1-50% by weight, based on the total weight of the catalyst.

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

[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 comprises silicon dioxide and / or di-aluminum trioxide; the clay is kaolin and / or poly-hydroxy kaolin.

[0016] Optionally, the cracking catalyst and the lightening catalyst each contain a rare earth element, and preferably, the large-pore zeolite is a Y-type zeolite modified by a rare earth element.

[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, and 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 further comprises a regenerator; the method further comprises separating the outlet material of the first reactor to obtain spent catalyst and the cracking reaction product; feeding the spent catalyst into the regenerator for regeneration treatment to obtain regenerated catalyst; returning the regenerated catalyst to the first reactor through a first regeneration inclined pipe and / or returning the regenerated catalyst to the second reactor through a second regeneration inclined pipe; or separating the outlet material of the first reactor to obtain spent cracking catalyst and the cracking reaction product; separating the outlet material of the second reactor to obtain spent lightening catalyst and the lightening reaction product; feeding the spent cracking catalyst and the spent lightening catalyst into the regenerator for regeneration treatment to obtain regenerated cracking catalyst and regenerated lightening catalyst; returning the regenerated cracking catalyst to the first reactor through a third regeneration inclined pipe, and returning the regenerated lightening catalyst to the second reactor through a fourth regeneration inclined pipe.

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

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

[0022] Optionally, the initial boiling point of the light gasoline is 20-40℃; the distillate cutting point of the light gasoline and the heavy gasoline is 80-100℃; the distillate cutting point of the gasoline middle distillate and the gasoline heavy distillate is 120-150℃.

[0023] Optionally, the bed density of the fluidized bed reactor is 300-500kg / m 3 , and the bed linear velocity 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 fresh agent in 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.

[0026] By the above technical solution, the heavy oil feedstock is subjected to catalytic cracking reaction for treatment, which can efficiently convert heavy aromatics in heavy oil cracking product into light aromatics. On one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and loss of aromatics caused by using hydrogenation treatment to produce light aromatics; on the other hand, it can solve the problem of difficult utilization of low-value heavy aromatics, and realize efficient utilization of resources. Moreover, the gasoline heavy distillate is subjected to back-fining in the second reactor, which is a dense-phase fluidized bed reactor, which can make the gasoline heavy distillate fully react, thereby further improving the yield of light aromatics. In addition, the method of 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 specific embodiments section. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and together with the specific embodiments below, serve to explain the present disclosure but do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 is a schematic diagram of a method for increasing production of light aromatics by catalytic cracking of gasoline according to the present disclosure.

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

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

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

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

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] 1 heavy oil feedstock; 2 cracking reaction unit; 3 cracking reaction product; 4 product separation device; 5 light gasoline; 6 gasoline intermediate fraction; 7 gasoline heavy fraction; 8 other product; 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 spent catalyst pipe; 18 regenerator; 19 second regenerated catalyst pipe; 20 first regenerated catalyst pipe; 21 regenerated flue gas; 22 make-up agent; 23 make-up agent; 24 riser reactor; 40 cracking settler; 41 lightening settler; 42 cracking spent catalyst pipe; 43 third regenerated catalyst pipe; 44 lightening spent catalyst pipe; 45 fourth regenerated catalyst pipe; 46 cracking regenerator; 47 lightening regenerator; 48 lightening reaction product; 49 cracking reaction product; 50 regenerated catalyst pipe. DETAILED DESCRIPTION

[0036] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present disclosure, and are not intended to limit the present disclosure.

[0037] As shown in Figure 1 The present disclosure provides a method for increasing production of light aromatics by catalytic cracking gasoline reforming, which comprises: introducing a heavy oil feedstock into a first reactor of a cracking reaction unit to contact with a cracking catalyst to perform a cracking reaction, to obtain a cracking reaction product; performing product separation treatment on the cracking reaction product to obtain other products, light gasoline, gasoline intermediate fraction and gasoline heavy fraction; performing aromatic separation treatment on the gasoline intermediate fraction to obtain benzene product, toluene product and xylene product; introducing the gasoline heavy fraction into a second reactor of the cracking reaction unit to contact with a lightening catalyst to perform a lightening reaction, to obtain a lightening reaction product; performing the product separation treatment on the lightening reaction product and the cracking reaction product; or returning the lightening reaction product to the first reactor; the second reactor is a dense phase fluidized bed reactor, 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] By the above technical solution, the heavy oil feedstock is treated by catalytic cracking reaction, which can efficiently convert heavy aromatics in heavy oil cracking products into light aromatics. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and loss of aromatics caused by using hydrogenation treatment to produce light aromatics; on the other hand, it can solve the problem of difficult utilization of low-value heavy aromatics, and realize efficient utilization of resources. Moreover, the gasoline heavy fraction is recycled in the second reactor, which is a dense phase fluidized bed reactor, which can make the gasoline heavy fraction fully react, thereby further improving the yield of light aromatics. In addition, the method of the present disclosure can also produce low-carbon olefins, further improving the utilization rate of raw materials.

[0039] In one embodiment, the initial boiling point of the heavy oil feedstock used by the present disclosure is 200-400℃, preferably 250-350℃; the final boiling point is 450-600℃, preferably 500-550℃.

[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 gas oil, atmospheric gas oil, coking gas oil, deasphalted oil, vacuum residue, atmospheric residue, extract oil and poor quality recycling oil; the other mineral oils are selected from one or more of coal liquefied oil, oil sand oil and shale oil.

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

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

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

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

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

[0046] The inorganic oxide is silicon dioxide and / or diatomic aluminum oxide; and the clay is kaolin and / or polyhydrous kaolin.

[0047] The cracking catalyst and the lightening catalyst also contain rare earth elements, respectively. The rare earth elements used in the present disclosure are conventionally selected in the art, and no special requirements are made in the present application. Preferably, the rare earth elements exist in the zeolite of the cracking catalyst and the lightening catalyst, and further preferably, the rare earth elements in the cracking catalyst and the lightening catalyst mainly come from Y-type zeolite modified by rare earth elements. In this embodiment, the addition of rare earth elements in the cracking catalyst and the lightening catalyst can improve the catalytic activity of the cracking catalyst and the lightening catalyst, thereby facilitating the improvement of the activity of the cracking reaction and the lightening reaction.

[0048] In a specific embodiment, the method for modifying Y-type zeolite by rare earth elements comprises: contacting NaY molecular sieve with a rare earth solution or a mixed solution of the rare earth solution and an ammonium salt, performing filtration, water washing, and drying, and then performing first calcination 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, mixing with a rare earth solution, and adjusting the pH value of the slurry to 5-6 with ammonia water, and then performing second calcination to obtain rare earth Y-type molecular sieve.

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

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

[0051] The inorganic oxide source, clay and deionized water are mixed and stirred to form a slurry, wherein the solid content of the slurry is 10-50% by weight; the pH of the slurry is adjusted to 1-4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, etc.), and the aging treatment is carried out at the pH; the temperature of the aging treatment is 20-80°C, and the time is 0-2h; then the inorganic oxide is added and stirred for 0.5-1.5h to form a colloid, and the zeolite is added to form a catalyst slurry; based on the total weight of the solid phase in the catalyst slurry, the content of the zeolite is 5-70% by weight, the content of the clay is 1-50% by weight, and the content of the inorganic oxide is 1-95% by weight; based on the total weight of the zeolite, the content of the large-pore zeolite in the zeolite is 30-99% by weight, and the content of the medium-pore zeolite is 1-70% by weight; after continuous stirring, the microspherical catalyst is prepared by spray drying; then the microspherical catalyst is calcined at 400-600°C for 0.5-2h, washed with ammonium sulfate at 30-80°C until the sodium oxide content is less than 0.25% by weight, then leached with deionized water and filtered, and then dried at 100-200°C to obtain a cracking catalyst; wherein the weight ratio of ammonium sulfate to microspherical catalyst to water is (0.1-1) : 1 : (5-15).

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

[0053] In an embodiment, 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, or a composite reactor composed of a dense phase fluidized bed reactor and a dilute phase transport bed reactor. The reactor type of the dense phase fluidized bed reactor used in the present disclosure is a bubbling bed reactor, a turbulent bed reactor or a fast bed reactor; the dilute phase transport bed reactor is a riser reactor.

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

[0056] The first reactor and the second reactor 13 can be arranged in parallel or in series. It should be noted that the connection mode of the first reactor and the second reactor 13 can 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, the catalyst mixing problem does not need to be considered, and therefore, the cracking reaction unit comprises a regenerator 18, a settler 16, a riser reactor 14, a fluidized bed reactor 15 and a second reactor 13. 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, and therefore, the cracking reaction unit comprises two regenerators, i.e., a cracking regenerator 46 and a lightening regenerator 47, two settlers, i.e., a cracking settler 40 and a lightening settler 41, the riser reactor 14, the fluidized bed reactor 15 and the second reactor 13. The riser reactor 14 and the fluidized bed reactor 15 are arranged 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 for further reaction.

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

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

[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 by the settler 16 to obtain spent catalyst and the cracking reaction product; the spent catalyst enters the regenerator 18 for regeneration treatment to obtain regenerated catalyst; the regenerated catalyst returns to the riser reactor 14 through the first regeneration inclined pipe 20 and / or the regenerated catalyst returns to the second reactor 13 through the second regeneration inclined pipe 19.

[0062] In a specific embodiment, as shown in FIG. 1, the first reactor and the second reactor 13 are arranged in series, and the first reactor is arranged downstream of the second reactor 13. Figure 2As shown, when the first reactor and the second reactor 13 are coaxially arranged, a catalyst outlet is provided on the side wall of the settling tank 16, a catalyst inlet, a first regenerator outlet, and a second regenerator outlet are provided on the side wall of the regenerator 18, a first regenerator inlet and a heavy oil feedstock inlet are provided on the riser reactor 14, and a second regenerator inlet, a gasoline heavy fraction inlet, a freshener inlet, and a pre-lifting medium inlet are provided on the second reactor 13. The catalyst outlet of the settling tank 16 is connected to the catalyst inlet of the regenerator through the catalyst inlet of the regenerator via the catalyst inlet inclined tube 17. The first regenerator outlet of the regenerator 18 is connected to the first regenerator inlet of the riser reactor 14 through the first regeneration inclined tube 20, and the second regenerator outlet of the regenerator 18 is connected to the second regenerator 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 connect to the pre-lifting medium source, and the freshener inlet of the second reactor 13 is used to connect to the freshener source.

[0063] The second regeneration inclined tube 19 is provided with a fresh agent inlet, which 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 feed and discharge flow rates of the regenerator 18, flow regulating valves are provided on the pre-regeneration inclined tube 17, the first regeneration inclined tube 20, and the second regeneration inclined tube 19.

[0065] Another specific implementation, such as Figure 3 As shown, when the first reactor and the second reactor 13 are set up separately, a catalyst outlet is provided on the side wall of the settling tank 16, and a catalyst inlet, a first regenerator outlet, and a second regenerator outlet are provided on the side wall of the regenerator 18. The riser reactor 14 is provided with a first regenerator inlet, a light-reduction reaction product inlet, a heavy oil feedstock inlet, and a pre-lifting medium inlet. The second reactor 13 is provided with a second regenerator inlet, a gasoline heavy fraction inlet, and a light-reduction reaction product outlet. The catalyst outlet of the settling tank 16 is connected to the catalyst inlet of the regenerator 18 via a catalyst inclined tube 17. The regenerator 1... The first regenerator outlet of reactor 8 is connected to the first regenerator inlet of riser reactor 14 via the first regeneration inclined tube 20, and the second regenerator outlet of the regenerator is connected to the second regenerator inlet of second reactor 13 via the second regeneration inclined tube 19; the light-reduction reaction product outlet of second reactor 13 is connected to the light-reduction reaction product inlet of riser reactor 14; the heavy oil feedstock inlet of riser reactor 14 is connected to the heavy oil feedstock source; the pre-lifting medium inlet of riser reactor 14 is used to connect to the pre-lifting medium source; the gasoline heavy fraction inlet of second reactor 13 is connected to the gasoline heavy fraction outlet of product separation device 4.

[0066] The second reactor 13 is provided with a fresh agent inlet at the bottom of the second regeneration inclined pipe 19 and / or the second reactor 13, and the two fresh agent inlets are communicated with a fresh agent source to enable the fresh agent to 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 are separately provided, and the first reactor is connected in series with the cracking settler 40 to enable the material reacted in the first reactor to enter the cracking settler 40; the second reactor 13 is integrally provided with the lightening settler 41 to enable the material reacted in the second reactor 13 to enter the lightening settler 41. And, the first reactor and the second reactor 13 are respectively provided with a regenerator.

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

[0069] In one specific embodiment, as shown in Figure 4 The cracking settler 40 is provided with a spent catalyst outlet and a cracking reaction product outlet on the side wall; the riser reactor 14 comprises a pre-lift medium inlet, a heavy oil raw material inlet and a third regeneration agent inlet; the cracking regenerator 46 comprises a spent agent inlet and a third regeneration agent outlet; the spent agent outlet of the cracking settler 40 is communicated with the spent agent inlet of the cracking regenerator 46 through the cracking spent inclined pipe 42; the third regeneration agent outlet of the cracking regenerator 46 is communicated with the third regeneration agent inlet of the riser reactor 14 through the third regeneration inclined pipe 43; the pre-lift medium inlet of the riser reactor 14 is used to communicate with a pre-lift medium source; and the heavy oil raw material inlet of the riser reactor 14 is used to communicate with a heavy oil raw material source.

[0070] The side wall of the lightening settler 41 is provided with a spent catalyst outlet and a lightening reaction product outlet; the second reactor 13 comprises a pre-lifting medium inlet, a gasoline heavy fraction inlet and a fourth regenerated catalyst inlet; the lightening regenerator 47 comprises a spent catalyst inlet and a fourth regenerated catalyst outlet; the spent catalyst outlet of the lightening settler 41 is communicated with the spent catalyst inlet of the lightening regenerator 47 through a lightening spent catalyst inclined pipe 44; the fourth regenerated catalyst outlet of the lightening regenerator 47 is communicated with the fourth regenerated catalyst inlet of the second reactor 13 through a fourth regenerated catalyst inclined pipe 45; the pre-lifting medium inlet of the second reactor 13 is used to communicate with a pre-lifting medium source; the gasoline heavy fraction inlet of the second reactor 13 is used to communicate with a 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 converged into a cracking reaction product bus to enable the mixed materials to enter the product separation device 4.

[0072] The fourth regenerated catalyst inclined pipe 45 and / or the bottom of the second reactor 13 is provided with a fresh catalyst inlet, and the two fresh catalyst inlets are communicated with a fresh catalyst source to enable the fresh catalyst to enter the second reactor 13.

[0073] In an embodiment, a steam inlet is further provided at the inlet of the riser reactor 14 and is used to communicate with a steam source to enable the steam to enter the riser reactor 14.

[0074] In an embodiment, in order to further improve the separation effect, a cyclone separator is respectively arranged at the upper part 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 separator used in the present disclosure is a conventional selection in the art, and the present application does not make any requirements. The number of stages of the cyclone separator can be flexibly selected according to the actual production needs, and preferably, the number of stages of the cyclone separator is 2 stages.

[0075] The top of the settler 16, the cracking settler 40 and the lightening settler 41 is provided with a gas collecting chamber, the inlet of the gas collecting chamber is communicated with the cracking reaction product outlet of the cyclone separator, and the outlet of the gas collecting chamber is used to communicate with the cracking reaction product outlet to enable the cracking reaction product to be buffered in the gas collecting chamber and then be discharged out of the system through the outlet.

[0076] The inside of the regenerator 18, the cracking regenerator 46 and the lightening regenerator 47 is further provided with an oxygen-containing gas distributor, 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 can be arranged at the lower part of the fluidized bed reactor 15 to enable the light gasoline to return to the cracking reaction unit for further reaction.

[0078] In one embodiment, the pre-lift medium used by the present disclosure is conventionally selected in the art, and no special requirement is made in the present application. For example, the pre-lift medium can be steam and / or dry gas.

[0079] In one embodiment, the method for carrying out the cracking reaction by using the device of Figure 2 The method for carrying out the cracking reaction by using the device of The method for carrying out the cracking reaction by using the device of

[0080] The method for carrying out the cracking reaction by using the device of Figure 3 The method for carrying out the cracking reaction by using the device of

[0081] In another embodiment, the method for carrying out the cracking reaction by the device of Figure 4 The method for carrying out the cracking reaction by the device of the above embodiment includes: feeding the heavy oil raw material 1 and the third regenerated catalyst into the riser reactor 14 under the action of the pre-lifting medium to carry out the cracking reaction, to obtain a mixture containing the spent cracking catalyst and the cracking reaction product; making the majority of the spent cracking catalyst in the mixture run downward under the action of gravity, and the cracking reaction product and the small part of the spent cracking catalyst in the mixture run upward and enter the cyclone separator to be separated, so that the small part of the spent cracking catalyst returns to the cracking settler 40, and the cracking reaction product is discharged from the cracking settler 40 through the gas collecting chamber. The spent cracking catalyst passes through the cracking spent slanted pipe 42 and enters the cracking regenerator 46, and is subjected to the regeneration treatment under the action of the oxygen-containing gas to obtain the third regenerated catalyst and the regenerated flue gas 21; the regenerated flue gas 21 is discharged, and the third regenerated catalyst returns to the riser reactor 14 through the third regenerated slanted pipe 43. The fresh agent 23, the fourth regenerated catalyst, and the gasoline heavy fraction enter the second reactor 13 under the action of the pre-lifting medium to carry out the lightening reaction, to obtain a mixture containing the lightening reaction product and the spent lightening catalyst; the majority of the spent lightening catalyst in the mixture runs downward under the action of gravity, and the lightening reaction product and the small part of the spent lightening catalyst in the mixture run upward and enter the cyclone separator to be separated, so that the small part of the spent lightening catalyst returns to the lightening settler 41, and the cracking reaction product is discharged from the system through the gas collecting chamber. The spent lightening catalyst passes through the spent lightening slanted pipe 44 and enters the lightening regenerator 47, and is subjected to the regeneration treatment under the action of the oxygen-containing gas to obtain the fourth regenerated catalyst and the regenerated flue gas 21; the regenerated flue gas 21 is discharged, and the fourth regenerated catalyst returns to the second reactor 13 after being mixed with the fresh agent 22 through the fourth regenerated slanted pipe 45; and 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 the fresh cracking catalyst or the fresh lightening catalyst, when the cracking catalyst and the lightening catalyst are the same, the fresh agent can be the fresh cracking catalyst or the fresh lightening catalyst; when the cracking catalyst and the lightening catalyst are different, the fresh agent is the fresh lightening catalyst.

[0083] In one embodiment, the method further includes adding the fresh agent in 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 0.2 or less, preferably 0.02-0.18, and further preferably 0.05-0.12.

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

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

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

[0087] In one embodiment, the product separation treatment device and method of the present disclosure are both conventional choices in the art, and the present application does not make any requirements, as long as the cracking reaction product can be separated into other products, light gasoline, gasoline intermediate fraction and gasoline heavy fraction. For example, the product separation treatment of the present application includes: subjecting the cracking reaction product 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 intermediate fraction and the gasoline heavy fraction.

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

[0089] In the above, the initial boiling point of the light gasoline is 20-40°C; the distillation cut point of the light gasoline and the heavy gasoline is 80-100°C; and the distillation cut point of the gasoline intermediate fraction and the gasoline heavy fraction is 120-150°C.

[0090] In one embodiment, the device and method for separating aromatics is a conventional selection in the art, and the present application does not make any requirement, as long as the gasoline middle distillate can be separated into benzene product, toluene product and xylene product, for example, the present application uses aromatics extraction technology for separation, and the aromatics raffinate can be returned to the catalytic cracking reactor for further reaction, and the recycling position can be the same as the light gasoline.

[0091] In one embodiment, the method further comprises returning part or all of the light gasoline to the cracking reaction unit 2 for reaction, and the returning 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 the present application does not make any special requirement.

[0092] The following examples will further illustrate the present application, but do not limit the present application. The heavy oil feedstock 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 the rare earth Y type molecular sieve (REY) comprises: contacting NaY molecular sieve with a rare earth solution or a mixed solution of the rare earth solution and an ammonium salt, and after filtration, water washing and drying, performing first calcination treatment to obtain a rare earth sodium Y type molecular sieve; then, the rare earth sodium Y type molecular sieve is slurried and contacted with an acid solution, filtered, mixed with a rare earth solution, and the pH value of the slurry is adjusted to 6 with ammonia water, and after filtration or without filtration, drying and second calcination treatment, a rare earth Y type molecular sieve (REY) is obtained.

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

[0098] Preparation Example 2

[0099] The method for preparing the rare earth Y type molecular sieve (REY) is the same as that in the preparation example 1.

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

[0101] Test Example 1

[0102] The micro-activity index obtained by testing according to the method for testing the 460°C micro-activity index in the NB / SH / T 0952-2017 is the catalyst activity of the cracking catalyst.

[0103] Example 1

[0104] The method for catalytically cracking gasoline to increase the production of light aromatic hydrocarbons by using the system of Figure 1 and the cracking reaction unit 2 of Figure 2 comprises the following steps:

[0105] The lightening reaction product from the second reactor, the first regenerated catalyst and the heavy oil feedstock 1 are introduced into the first reactor to carry out cracking reaction, to obtain a mixture containing cracking reaction product and spent catalyst, wherein most of the spent catalyst runs downward under the action of gravity, and the cracking reaction product and a small part of the spent catalyst in the mixture run upward and enter the cyclone separator to separate, so that the small part of the spent catalyst returns to the settler 16, and the cracking reaction product is discharged from the settler 16 through the gas collecting chamber. The spent catalyst passes through the spent catalyst inclined pipe 17 and enters the regenerator 18, and is subjected to regeneration treatment under the action of oxygen-containing gas to obtain regenerated catalyst and regeneration flue gas 21, and the regeneration flue gas 21 is discharged; the regenerated catalyst is divided into the first regenerated catalyst and the second regenerated catalyst, and the first regenerated catalyst returns to the first reactor through the first regenerated catalyst inclined pipe 20, and the second regenerated catalyst returns to the second reactor 13 through the second regenerated catalyst inclined pipe 19;

[0106] The cracking reaction product is introduced into the product separation device 4 to carry out first separation, to obtain the other products 8, light gasoline 5 and heavy gasoline; the heavy gasoline is subjected to second separation to obtain gasoline intermediate fraction 6 and gasoline heavy fraction 7, wherein the initial boiling point of the light gasoline 5 is 30°C, the distillation cut point of the light gasoline 5 and the heavy gasoline is 75°C, and the distillation cut point of the gasoline intermediate fraction 6 and the gasoline heavy fraction 7 is 145°C; the gasoline intermediate fraction is introduced into the aromatic separation device 9 to carry out aromatic separation treatment, to obtain benzene product 10, toluene product 11 and xylene product 12; the fresh agent, the second regenerated catalyst and the gasoline heavy fraction 7 are introduced into the second reactor 13 under the action of pre-lifting medium (water vapor) to carry out lightening reaction, to obtain lightening reaction product; the ratio of the weight 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 subjected to further separation, 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 increasing production of light aromatic hydrocarbons by re-conversion of catalytically cracked gasoline is the same as that 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 increasing production of light aromatic hydrocarbons by re-conversion of catalytically cracked gasoline is the same as that in Example 1, except that the agent oil ratio of 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 of gasoline to increase the production of light aromatics is the same as in Example 1, except that it employs... Figure 4 The cracking reaction is carried out in a cracking unit so that the catalyst for the cracking reaction is entirely sourced from C1 regenerated catalyst. The reaction conditions and product properties are shown in Table 2.

[0114] Example 5

[0115] The method for increasing the production of light aromatics through the re-conversion of catalytic cracked gasoline is the same as in Example 1, except that the valve on the first regeneration inclined tube 20 is closed so that the catalyst source for the cracking reaction is entirely C1 recycled catalyst. Reaction conditions and product properties are shown in Table 2.

[0116] Example 6

[0117] The method for catalytic cracking of gasoline to increase the production of light aromatics is the same as in Example 1, except that it employs... Figure 4 The cracking reaction was carried out in a cracking unit, and the catalyst for the lightening reaction was 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 increasing the production of light aromatics through catalytic cracking of gasoline is the same as in Example 1, except that the bed density of the dense-phase fluidized bed reactor is 250 kg / m³. 3 The reaction conditions and product properties are shown in Table 2.

[0120] Example 8

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

[0122] Example 9

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

[0124] Example 10

[0125] The method for increasing the production of light aromatics through the re-conversion of catalytic cracked gasoline is the same as in Example 1, except that no freshener is added during the lightening reaction in the second reactor. Reaction conditions and product properties are shown in Table 3.

[0126] Example 11

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

[0128] Comparative Example 1

[0129] The method for increasing production of light aromatics by re-conversion of catalytically cracked gasoline is the same as that of Example 1, except that neither the light gasoline nor the heavy gasoline fraction is 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 increasing production of light aromatics by re-conversion of catalytically cracked gasoline is the same as that of 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 Company. The reaction conditions and product properties are shown in Table 3.

[0132] Comparative Example 3

[0133] The method for increasing production of light aromatics by re-conversion of catalytically cracked gasoline is the same as that of Example 1, except that the cracking reaction unit is replaced by a cracking reaction unit Figure 5 , i.e., the second reactor is a riser reactor 24, and the regenerated catalyst is returned to the riser reactor 24 through a regeneration elbow 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 the examples and comparative examples

[0138]

[0139]

[0140] As can be seen from the table, comparison of the data in Examples 1-11 and Comparative Examples 1-3 shows that the technical solution of the present disclosure can avoid the problems of high hydrogen consumption, harsh operating conditions, and loss of aromatics caused by using hydrogen treatment to produce light aromatics. Comparison of the data in Example 1, Example 2, and Example 3 shows that the lightening reaction of the present application can obtain a high yield of BTX by non-hydrogen catalytic cracking of the heavy gasoline fraction at a temperature of 610-650°C and a catalyst to oil ratio of (15-25): 1. Comparison of the data in Example 1, Example 6, and Comparative Example 2 shows that when the catalyst activity of the catalyst in the second reactor is 50-99, a high yield of BTX can be obtained. Comparison of the data in Example 1, Example 7, and Comparative Example 3 shows that when the bed density of the second reactor is 180-700 kg / m3, a high yield of BTX can be obtained.3 , the yield of BTX can be improved, and the bed density of the dense fluidized bed reactor is 300-500 kg / m 3 , the yield of BTX can be further improved; according to the data in Example 1 and Example 8, it can be known that the recycling of the light gasoline to the cracking reaction unit can further improve the yield of BTX; according to the data in Example 1, Example 10 and Example 11, it can be known that the addition of 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 combination with the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0142] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0143] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as it does not deviate from the idea of the present disclosure, and it should also be considered as disclosed by the present disclosure.

Claims

1. A process for the increased production of light aromatics from catalytic cracking gasoline by secondary conversion, characterized in that, The method comprises: making the heavy oil raw material enter a first reactor of a cracking reaction unit to contact with a cracking catalyst to perform a non-hydrogenation cracking reaction, to obtain a cracking reaction product; making the cracking reaction product perform a product separation treatment to obtain other products, light gasoline, gasoline intermediate fraction and gasoline heavy fraction; making the gasoline intermediate fraction perform an aromatic hydrocarbon separation treatment to obtain benzene product, toluene product and xylene product; making the gasoline heavy fraction enter a second reactor of the cracking reaction unit to contact with a lightening catalyst to perform a non-hydrogenation lightening reaction, to obtain a lightening reaction product; making the lightening reaction product perform the product separation treatment with the cracking reaction product; or, making the lightening reaction product return to the first reactor; The second reactor is a dense phase fluidized bed reactor, the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; the micro-reactivity index of the catalyst in the second reactor is 50-99; the reaction conditions of the non-hydrogenation cracking reaction include: the reaction temperature is 555-720℃, the reaction time is 1-10s, and the catalyst-oil ratio is (1-100):1; the reaction conditions of the non-hydrogenation lightening reaction include: the reaction temperature is 560-680℃, and the catalyst-oil ratio is (10-30):

1.

2. The method of claim 1, wherein, The heavy oil raw material includes petroleum hydrocarbon and / or other mineral oil; The petroleum hydrocarbon is selected from one or more of vacuum wax oil, atmospheric wax oil, coking wax oil, deasphalted oil, vacuum residue, atmospheric residue, extracted oil and poor quality back-refined oil; The other mineral oil is selected from one or more of coal liquefied oil, oil sand oil and shale oil.

3. The method of claim 1, wherein, The reaction conditions of the non-hydrogenation cracking reaction include: the reaction temperature is 580-700℃, the reaction time is 1.5-6s, and the catalyst-oil ratio is (10-50):1; The micro-reaction activity index of the catalyst in the non-hydrogenation lightening reaction is 60-90.

4. The method of claim 1, wherein, The cracking catalyst and the lightening catalyst are the same or different; The cracking catalyst and the lightening catalyst each independently include zeolite, inorganic oxide and clay; the content of the zeolite is 5-70% by weight, the content of the inorganic oxide is 1-95% by weight, and the content of the clay is 1-50% by weight, based on the total weight of the catalyst, wherein the sum of the contents of the components in the cracking catalyst is 100% by weight, and the sum of the contents of the components in the lightening catalyst is 100% by weight.

5. The method of claim 4, wherein, The zeolite of the cracking catalyst includes large-pore zeolite and medium-pore zeolite; 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, based on the total weight of the zeolite in the cracking catalyst; The zeolite of the lightening catalyst includes large-pore zeolite and medium-pore zeolite; 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, based on the total weight of the zeolite in the lightening catalyst.

6. The method of claim 5, wherein, The medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from β zeolite and / or Y zeolite; The inorganic oxide includes silicon dioxide and / or di-aluminum trioxide; The clay is kaolin.

7. The method of claim 6, wherein, The clay is hydrous kaolin.

8. The method of claim 6, wherein, The cracking catalyst and the lightening catalyst each contain rare earth elements.

9. The method of claim 8, wherein, The large-pore zeolite is Y-type zeolite modified by rare earth elements.

10. The method of claim 1, wherein, The first reactor is a combination of a riser reactor and a fluidized bed reactor.

11. The method of claim 1, wherein, 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.

12. The method of claim 1, wherein, The cracking reaction unit further comprises a regenerator; The method further comprises separating the outlet material of the first reactor to obtain spent catalyst and the cracking reaction product; The spent catalyst is introduced into the regenerator for regeneration treatment to obtain regenerated catalyst; The regenerated catalyst is returned to the first reactor through a first regenerated inclined pipe and / or the regenerated catalyst is returned to the second reactor through a second regenerated inclined pipe; or, The outlet material of the first reactor is separated to obtain spent cracking catalyst and the cracking reaction product; The outlet material of the second reactor is separated to obtain spent lightening catalyst and the lightening reaction product; The spent cracking catalyst and the spent lightening catalyst are introduced into the regenerator respectively for regeneration treatment to obtain regenerated cracking catalyst and regenerated lightening catalyst; The regenerated cracking catalyst is returned to the first reactor through a third regenerated inclined pipe, and the regenerated lightening catalyst is returned to the second reactor through a fourth regenerated inclined pipe.

13. The method of claim 12, wherein, A fresh agent inlet is arranged on the second regenerated inclined pipe and / or at the bottom of the second reactor; or, A fresh agent inlet is arranged on the fourth regenerated inclined pipe and / or at the bottom of the second reactor.

14. The method of claim 1, wherein, The product separation treatment comprises: The cracking reaction product is subjected to first separation to obtain the other product, the light gasoline and heavy gasoline; the heavy gasoline is subjected to second separation to obtain the gasoline intermediate fraction and the gasoline heavy fraction.

15. The method of claim 14, wherein, The initial boiling point of the light gasoline is 20-40℃; the distillation cut point of the light gasoline and the heavy gasoline is 80-100℃; the distillation cut point of the gasoline intermediate fraction and the gasoline heavy fraction is 120-150℃.

16. The method of claim 1, wherein, The bed density of the dense fluidized bed reactor is 300-500 kg / m 3 , and the bed linear velocity is 0.4-2 m / s.

17. The method of claim 1, wherein, The light gasoline is returned to the cracking reaction unit for the non-hydrogen cracking reaction.

18. The method of claim 1, wherein, The method further comprises adding fresh agent in 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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