Method for reducing benzene content in gasoline and method for producing low-benzene gasoline

Abstract

The invention relates to a method for reducing benzene content in gasoline and a method for producing low-benzene gasoline. The method comprises the following steps: performing high-precision distillation cutting on benzene-rich gasoline to obtain gasoline light fraction, middle fraction and heavy fraction; the benzene-rich gasoline middle fraction enters a moving bed or fluidized bed or fixed bed reactor to be in graded contact with a low-carbon olefin-rich material flow for catalytic alkylation with a mesoporous molecular sieve catalyst, and benzene is efficiently converted into alkylbenzene, so that the benzene-rich gasoline is converted into high-octane-number low-benzene gasoline and liquefied gas. The method provided by the invention reduces the benzene content and olefin content in gasoline, improves the octane number of gasoline and increases the yield of liquefied gas, not only solves the problem that refinery gasoline has high benzene content and is difficult to meet the national VI standard of motor gasoline, but also improves the quality of gasoline and increases the yield of liquefied gas.

Description

Technical Field

[0001] The invention relates to the field of catalytic conversion of gasoline and benzene, and in particular to a method for reducing the benzene content in benzene-rich gasoline and a method for producing low-benzene gasoline. Background Art

[0002] In recent years, with the implementation of the National VI clean gasoline standard, not only has the olefin content limit of automotive gasoline been reduced from 24v% of National V to 18v% in National VI a stage and 15v% in National VI b stage, and the aromatic content limit has been reduced from 40v% of National V to 35v%, but the benzene content limit has also been tightened, from 1.0v% of National V to 0.8v%, even stricter than the EU 1.0v%. The benzene in the gasoline pool mainly comes from reformed gasoline and catalytic cracking gasoline that have not been extracted with benzene. The benzene content of reformed gasoline is relatively high, generally 2-10% by weight, while the benzene content of catalytic cracking gasoline with high olefin, high sulfur and high nitrogen content is relatively low, generally 0.4-1.0% by weight. The benzene content of straight-run naphtha and hydrocracking naphtha is as low as 0.1-0.5% by weight, and because of the low octane number, it is generally not used as a gasoline blending component. The benzene content of steam cracking gasoline is as high as 20-60% by weight. Because of the high benzene content, benzene is generally extracted and used as a chemical material.

[0003] With the deterioration of catalytic cracking raw materials and the strong demand for producing more liquefied gas and processing catalytic diesel, the severity of the reaction has continued to increase, further leading to a high benzene content in catalytic cracking gasoline. Taking Tianjin Petrochemical and Jinan Refining as examples, their catalytic cracking units are processing residual oil raw materials while processing hydrogenated catalytic diesel and straight-run diesel. When implementing the high-production liquefied gas plan, the benzene content of the stable gasoline produced is as high as 1.4% by weight, and the volume fraction of gasoline benzene is higher than 1.2v%. The excessive benzene content in catalytic cracking gasoline has seriously restricted the catalytic cracking unit from processing catalytic diesel and increasing the production of liquefied gas according to market demand. Therefore, in the process of chemical transformation and structural adjustment, refineries need to deal with gasoline upgrades and reduce benzene in catalytic cracking gasoline without delay.

[0004] At present, mature gasoline benzene reduction schemes are mainly carried out on reformed gasoline, such as physical separation methods such as distillation, extraction, and adsorption, as well as chemical methods such as benzene hydrogenation saturation and alkylation. North American countries such as the United States have stricter restrictions on benzene (<0.6v%) because benzene is carcinogenic, and usually use physical separation + chemical conversion methods to reduce benzene. There are usually two technical routes for reducing benzene by hydrogenation saturation of aromatic rings in reformed gasoline benzene fractions and alkylation.

[0005] Hydrogenation saturation aromatic ring benzene reduction technologies include CD Tech's catalytic distillation hydrogenation saturation benzene reduction (CD Hydro) process that combines a hydrogenation reactor with a product stripper, UOP's Bensat process using a Pt-based catalyst, IFP and Axens' Benfree process, GTC's GT-BenZapSM process, and Neste's NExSAT process. The hydrogenation saturation route for benzene-containing fractions has problems with gasoline octane number loss and high hydrogen consumption, and needs to be combined with isomerization to compensate for the octane number loss. Only about 20 sets of hydrogenation saturation benzene reduction units are in use.

[0006] The main technologies for alkylation benzene reduction in reformed gasoline containing benzene include the MBR dense phase fluidized bed process developed by Mobil and the liquid phase alkylation BenzOUTTM process developed by ExxonMobil. The alkylation benzene reduction is more mainstream abroad, with more than 90 commercial applications. Among them, hydrogenation saturation benzene reduction and liquid phase alkylation benzene reduction are not suitable for benzene reduction in catalytic cracking gasoline with high olefin content. Currently, only the MBR dense phase fluidized bed process can achieve mixed feed of reformed oil benzene-rich fraction and catalytic cracking light gasoline. Using a dense phase fluidized bed and a dedicated ZSM-5 catalyst, the raw material is the reformed oil benzene-rich fraction, and the olefin is a light olefin resource such as catalytic cracking dry gas. Under typical gas phase alkylation conditions (operating pressure of 1.2-1.5MPa and temperature of 350℃), the single-pass conversion rate of benzene is 60%-70%. If the material is partially recycled, the total conversion rate can reach 90%. Since light olefins are converted into gasoline components, the gasoline yield increases by 7% and the octane number increases by 5-10 units. There is also technology for producing ethylbenzene by alkylation of dry gas and benzene in China, but it mainly utilizes pure benzene and ethylene in dry gas to produce ethylbenzene or styrene.

[0007] Regarding the patented technology of reducing benzene by alkylation of benzene with low-carbon olefins, most foreign countries use MWW zeolite proprietary catalysts to alkylate reformed gasoline in a fixed bed reactor. U.S. Patents US62 / 084158, US61 / 209995, US2011 / 023900 and US2011 / 023912 all disclose that benzene-containing gasoline is contacted with a C4+ alkylating agent in a fixed bed of MWW zeolite catalyst, preferably MCM-22, and the alkylating agent is operated by staged olefin injection, and the final distillate has a reduced benzene content.

[0008] Most of the Chinese patents are about alkylation of reformed gasoline using a proprietary ZSM zeolite catalyst in a fixed bed reactor. Chinese patent CN201110109863.9 is about the alkylation reaction of the benzene-rich fraction of the reformed oil with C2-C4 olefins in the presence of an alkylation catalyst, and the polyalkylbenzene fraction obtained by the reaction is then subjected to a transalkylation reaction with the benzene-rich fraction of the reformed oil in the presence of an alkylation catalyst. CN200710140485.4 ethylene and benzene in gasoline are contacted with a ZSM5 / ZSM11 co-crystallized silica-alumina zeolite alkylation catalyst in a fixed bed or fluidized bed reactor at 0.2-1.5MPa, a temperature of 300-450°C, an ethylene to benzene molar ratio of 1-12, and a benzene space velocity of 0.2-2.0h-1 to produce ethylbenzene, and the conversion rate of benzene is greater than 45%.

[0009] There are also patents proposing patented technologies for coupling FCC gasoline benzene alkylation with catalytic cracking. Patents CN200810231560.2 and CN200710120108.4 both disclose that a catalytic cracking unit is provided with an alkylation reaction zone to introduce dry gas and gasoline fractions, and benzene is converted into alkylbenzene under the action of ZSM-5 molecular sieve and Y-type molecular sieve catalysts, and the volume content of benzene can be reduced by more than 50%.

[0010] Domestic and foreign patents for reducing benzene, as well as existing technologies for reducing benzene by hydrogenation saturation and liquid phase alkylation, are all aimed at reducing benzene in reformed gasoline fractions that are low in olefins and do not contain sulfur, nitrogen, or water. They are not suitable for reducing benzene in catalytic cracking gasoline that has high olefins, high sulfur, and nitrogen content, and has a lower benzene content than reformed gasoline. At present, there is no mature, low-cost, and efficient technology for reducing the benzene content in catalytic cracking gasoline at home and abroad. Therefore, the catalytic cracking unit has a problem of exceeding the stable benzene content in gasoline when executing the processing of hydrogenation catalytic diesel or the production of more liquefied gas, which is as high as 1.2v%. There is an urgent need to develop a production method for reducing the benzene content in gasoline. Summary of the invention

[0011] The purpose of the present invention is to provide a method for catalytically converting gasoline benzene into alkylbenzene and converting benzene-rich gasoline into high-octane low-benzene gasoline and liquefied gas, thereby improving gasoline quality and increasing liquefied gas production. A method and system for producing low-benzene gasoline are also provided.

[0012] A first aspect of the present invention provides a method for reducing the benzene content in gasoline, the method comprising:

[0013] (1) distilling and cutting the benzene-rich gasoline to obtain a benzene-rich gasoline middle distillate with a distillation range of 60 to 90° C.;

[0014] (2) the benzene-rich gasoline middle fraction enters the first reactor and contacts the catalyst with the graded injected light olefin-rich stream under hydrogenation conditions to carry out a catalytic alkylation reaction, thereby obtaining a first mixed material comprising a first spent catalyst and a first oil gas;

[0015] (3) allowing the first mixed material to pass through the oil separation filter of the first reactor for separation, and the separated first oil and gas enter the oil and gas separation system for product separation to obtain products including dry gas, liquefied gas and gasoline;

[0016] (4) the separated first catalyst to be regenerated is stripped in a steam exchanger and then enters a regenerator for oxygen-containing regeneration. The regenerated catalyst is returned to the first reactor for recycling. Preferably, part or all of the flue gas after regeneration is recycled back to the regenerator;

[0017] The benzene content of the benzene-rich gasoline is 0.8 to 40% by weight; the low-carbon olefin is ethylene and / or propylene;

[0018] Preferably, in step (2), the molar ratio of light olefins to benzene is maintained at 3 to 9:1, preferably 4 to 8:1.

[0019] According to the method of the first aspect of the present invention, the light olefin content in the light olefin-rich stream is 20 to 50 weight %;

[0020] Preferably, the light olefin-rich stream is selected from one or more of the following: an ethylene stream, a propylene stream, ethylene-rich dry gas, and propylene-rich liquefied gas.

[0021] According to the method of the first aspect of the present invention, the catalytic alkylation reaction temperature is 250 to 450°C, preferably 300 to 400°C;

[0022] The reaction pressure is 0.1 to 5.0 MPa, preferably 0.5 to 4.0 MPa;

[0023] The weight ratio of catalyst to feedstock oil is 1.0 to 9.0:1, preferably 2.0 to 6.0:1; and / or

[0024] Weight hourly space velocity is 0.2~20.0h -1 , preferably 1.0~5.0h -1 .

[0025] According to the method of the first aspect of the present invention, the first reactor is selected from a fluidized bed reactor, a moving bed reactor or a fixed bed reactor, preferably a moving bed reactor; and / or

[0026] The first reactor is provided with 3 or more light olefin injection ports in sections.

[0027] According to the method of the first aspect of the present invention, the distillation and cutting of the benzene-rich gasoline is carried out by using one or more distillation towers;

[0028] Preferably, the total theoretical plate number of the distillation tower is greater than or equal to 14.

[0029] According to the method of the first aspect of the present invention, the catalyst comprises a mesoporous molecular sieve, a heat-resistant inorganic oxide and optionally clay, wherein the mesoporous molecular sieve accounts for 40 to 80 weight percent of the total amount of the catalyst;

[0030] Preferably, the mesoporous molecular sieve is selected from the mordenite series and / or ZSM series mesoporous zeolite, more preferably the ZSM series mesoporous zeolite; and / or

[0031] Preferably, the heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide.

[0032] According to the method of the first aspect of the present invention, the benzene-rich gasoline is catalytic cracking gasoline, hydrocracking gasoline, reforming gasoline and / or steam cracking gasoline with a boiling point of 30 to 220° C.; and / or

[0033] The benzene-rich gasoline middle fraction is preheated before entering the first reactor, and the preheating temperature is 100-350°C, preferably 150-300°C.

[0034] According to the method of the first aspect of the present invention, the atmosphere for oxygen-containing regeneration is air and / or oxygen atmosphere, preferably oxygen-enriched and / or pure oxygen atmosphere;

[0035] The regeneration temperature of the regenerator is 450-750°C, preferably 500-700°C;

[0036] The regeneration pressure of the regenerator is 0.2 to 5.0 MPa, preferably 0.5 to 5.0 MPa; and / or

[0037] The flue gas temperature circulating back to the regenerator is 300-600°C.

[0038] A second aspect of the present invention provides a method for producing low-benzene gasoline, the method comprising:

[0039] (1) catalytically cracking the heavy oil in a second reactor to obtain a second mixed material comprising a second spent catalyst and a second oil and gas;

[0040] (2) performing oil-gas separation on the second mixed material in an oil-gas separation system to obtain a dry gas component, a liquefied gas component, and a gasoline component;

[0041] (3) distilling the gasoline components in a gasoline distillation system to obtain a self-produced gasoline benzene-rich fraction and a low-benzene gasoline;

[0042] (4) the self-produced gasoline benzene-rich fraction and any other gasoline benzene-rich fraction enter the first reactor and contact the catalyst with the graded injected light olefin stream under non-hydrogenation or hydrogenation conditions to perform a catalytic alkylation reaction to obtain a first mixed material comprising a first spent catalyst and a first oil gas;

[0043] (5) allowing the first mixed material to pass through the oil separation filter of the first reactor for separation, and the separated oil and gas enter the oil and gas separation system for oil and gas separation;

[0044] (6) The separated first catalyst to be regenerated enters the second reactor and is mixed with the second catalyst to be regenerated. After being stripped by the steam exchanger of the second reactor, it enters the regenerator for oxygen-containing regeneration. The regenerated catalyst is returned to the first reactor and the second reactor for recycling. Preferably, part or all of the flue gas after regeneration is recycled back to the regenerator.

[0045] Wherein, the heavy oil is wax oil and / or residual oil.

[0046] According to the method of the second aspect of the present invention, the gasoline benzene-rich fraction is obtained by distilling and cutting the benzene-rich gasoline to obtain a benzene-rich gasoline middle fraction with a distillation range of 60 to 90° C.;

[0047] Wherein, the benzene content of the benzene-rich gasoline is 0.8 to 40 weight %;

[0048] Preferably, the benzene-rich gasoline is catalytic cracking gasoline, hydrocracking gasoline, reforming gasoline and / or steam cracking gasoline with a boiling point of 30 to 220°C.

[0049] Compared with the prior art, the present invention has the following technical effects:

[0050] (1) The benzene-rich catalytic cracking gasoline is cut by high-precision distillation to obtain a benzene-rich gasoline intermediate fraction, which is then contacted with a medium-pore molecular sieve for catalytic alkylation together with a graded injection of a low-carbon olefin-rich stream. The benzene conversion rate is high, the gasoline octane number is improved, and the production of liquefied gas is increased.

[0051] (2) After the reaction, the catalyst is regenerated and recycled, or fed into the heavy oil catalytic cracking reactor, which not only realizes continuous production but also can always maintain a high activity of the catalyst, thus solving the problem of catalyst deactivation caused by coking when processing high-olefin catalytic cracking gasoline or steam cracking gasoline.

[0052] (3) The regenerated flue gas is partially or completely circulated after heat exchange with the main air, which not only makes full use of the oxygen in the flue gas, but also solves the problem of the flue gas carrying heat out of the regeneration system, and reduces the emission of waste gases such as carbon dioxide, thus greatly saving energy and reducing emissions.

[0053] (4) It has a wide range of applications. It is not only suitable for benzene-containing reforming gasoline (benzene 2-10 wt%) with low olefin, low sulfur and low nitrogen content, but also can be used for catalytic cracking gasoline (benzene 0.8-3.0 wt%) with high olefin, high sulfur and high nitrogen content and relatively low benzene content, and steam cracking gasoline (benzene 20-40 wt%) with high olefin, high sulfur and high nitrogen content and also relatively high benzene content. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The present invention is a schematic diagram of a process flow of a benzene alkylation moving bed reactor embodiment, which is used to illustrate the continuous process flow of the fluidized bed catalytic alkylation of benzene-rich gasoline.

[0055] Figure 2 The present invention is a process flow diagram of a combined implementation method of a benzene alkylation moving bed reactor and heavy oil catalytic cracking, which is used to illustrate the coupled processing process of benzene-rich gasoline intermediate fraction alkylation and heavy oil catalytic cracking.

[0056] Description of reference numerals:

[0057] I, reactor; II, regenerator; III, oil-gas separation system; IV, oil filter separator; V, gasoline distillation system; VI, heavy oil cracking reactor; VII, distillation tower; 1, gasoline benzene-rich fraction; 1a, gasoline light fraction without aromatics; 1b, gasoline middle fraction rich in benzene; 1c, gasoline heavy fraction rich in aromatics; 2, light olefin logistics I; 3, hydrogen-fluidized medium; 4, light olefin logistics II; 5, light olefin logistics III; 6, reaction oil and gas pipeline dry gas; 7, dry gas; 8. Liquefied gas; 9. Gasoline; 10. Regenerated agent delivery pipeline I; 11. Regenerated agent delivery pipeline II; 12. Regeneration agent delivery pipeline I; 13. Regeneration agent delivery pipeline II; 14. Stripping medium; 15. Oxygen-containing regeneration gas; 16. Flue gas; 17. Flue gas circulation pipeline; 18. Additive pipeline; 19. Heavy crude oil; 20. Atomizing medium; 21. Pre-lifting medium; 22. Diesel; 23. Slurry oil; 24. Steam exchanger; 25. Self-produced gasoline benzene-rich fraction; 26. Low-benzene gasoline after distillation. DETAILED DESCRIPTION

[0058] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0059] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0060] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0061] The inventors of the present invention have found through years of research that: (1) the benzene content of high-benzene catalytic cracking gasoline is 0.8-2.0% by weight, which is mainly distributed in the gasoline middle distillate at 60-90°C. Therefore, the present invention uses distillation to cut the benzene-rich middle distillate for separate processing; (2) the alkylation of low-carbon olefins with benzene requires maintaining the olefin / benzene molar ratio within a certain range, such as an olefin / benzene molar ratio of 3-9, in order to maintain a high benzene conversion rate; (3) the benzene-rich middle distillate of catalytic cracking gasoline has not only a high olefin content and a low octane number for reforming gasoline, but also high sulfur and nitrogen contents and a relatively low benzene content. Therefore, the present invention uses a medium-pore molecular sieve catalyst to catalyze the conversion of the benzene-rich middle distillate. Alkylation of benzene with low-carbon olefins can not only reduce the benzene content of catalytic cracking gasoline, but also improve the octane number of gasoline and increase the production of liquefied gas. (4) The benzene-rich intermediate fraction of catalytic cracking gasoline has a high olefin content and is easily coked and deactivated during the alkylation process. The coked catalyst can be regenerated by burning it in an oxygen atmosphere. After the reaction, the catalyst can be regenerated and recycled, which not only realizes continuous production but also keeps the catalyst at a high activity. (5) The flue gas after the regeneration of the coked catalyst is exchanged with the main air, which not only makes full use of the oxygen in the flue gas, but also further solves the problem of the flue gas carrying heat out of the regeneration system and reduces the emission of waste gases such as carbon dioxide.

[0062] Based on the above findings, the present invention provides a gasoline benzene reduction method in which a benzene-rich gasoline fraction is contacted with a medium-pore molecular sieve catalyst in a staged manner to carry out benzene catalytic alkylation, that is, a benzene-rich gasoline intermediate fraction is obtained by high-precision distillation and cutting, and then enters a moving bed, fluidized bed or fixed bed reactor, and is contacted with a staged injected low-carbon olefin-rich stream in the presence of hydrogen to carry out a catalytic alkylation reaction with a medium-pore molecular sieve catalyst at a suitable temperature and pressure; after the reaction, the oil and gas are separated into products by a separation system to obtain dry gas, liquefied gas, gasoline and other products; the coked deactivated catalyst is further stripped to remove the entrained flammable gas such as oil and gas, and then regenerated in an oxygen-containing regeneration system; the regenerated catalyst is stripped, deoxygenated and dehydrated with nitrogen, and then returned to the reaction stage for recycling, and part and / or all of the regenerated high-temperature flue gas is returned to the regenerator, thereby achieving the self-heat balance of the gasoline benzene alkylation reaction in a continuous regeneration, and achieving a higher conversion rate of benzene under a high-activity catalyst, and achieving efficient and continuous production.

[0063] The present invention provides a method for reducing the benzene content in benzene-rich gasoline, comprising:

[0064] (1) distilling and cutting the benzene-rich gasoline to obtain a benzene-rich gasoline middle distillate with a distillation range of 60 to 90° C.;

[0065] (2) the benzene-rich gasoline middle fraction enters the first reactor and contacts the catalyst with the graded injected light olefin-rich stream under hydrogenation conditions to carry out a catalytic alkylation reaction, thereby obtaining a first mixed material comprising a first spent catalyst and a first oil gas;

[0066] (3) allowing the first mixed material to pass through the oil separation filter of the first reactor for separation, and the separated first oil and gas enter the oil and gas separation system for product separation to obtain products including dry gas, liquefied gas and gasoline;

[0067] (4) The separated first catalyst to be regenerated is stripped in a steam exchanger and then enters a regenerator for oxygen-containing regeneration. The regenerated catalyst is returned to the first reactor for recycling. Preferably, part or all of the flue gas after regeneration is recycled back to the regenerator.

[0068] In step (1), the benzene content of the benzene-rich gasoline is 0.8-40% by weight, and the benzene-rich gasoline is catalytic cracking gasoline, hydrocracking gasoline, reforming gasoline and / or steam cracking gasoline with a boiling point of 30-220°C.

[0069] The benzene-rich gasoline in the present invention is mainly catalytic cracking gasoline with a boiling point of 30-220°C and / or gasoline fractions from other sources such as hydrocracking units and / or reforming units and / or steam cracking units, and its benzene content is 0.8-40% by weight. The benzene-rich gasoline is cut by high-precision distillation to obtain a gasoline light fraction without aromatics, a gasoline middle fraction rich in benzene, and a gasoline heavy fraction rich in aromatics, wherein the gasoline middle fraction rich in benzene is generally controlled to have a distillation range of 60-90°C, and more than 50% of the benzene in the gasoline is enriched. In principle, the benzene content of the gasoline obtained by mixing the gasoline light fraction and the gasoline heavy fraction rich in aromatics is controlled to meet the gasoline blending requirements of the refinery, and the benzene is enriched in the maximum amount with lower energy consumption, and the yield of the gasoline middle fraction rich in benzene is lower.

[0070] In one embodiment, the distillation and cutting of the benzene-rich gasoline is performed by using one or more distillation towers;

[0071] Preferably, the total theoretical plate number of the distillation tower is greater than or equal to 14.

[0072] In step (2), the light olefin is ethylene and / or propylene;

[0073] Preferably, in step (2), the molar ratio of light olefins to benzene is maintained at 3 to 9:1, preferably 4 to 8:1.

[0074] In one embodiment, the benzene-rich gasoline middle fraction is preheated before entering the first reactor, and the preheating temperature is 100-350°C, preferably 150-300°C.

[0075] Since the equilibrium conversion rate of the reaction between light olefins and benzene is low, the present invention maintains an olefin / benzene molar ratio of 3 to 9:1 by staged injection of a light olefin-rich stream, thereby improving the conversion rate of benzene.

[0076] The light olefin-rich logistics of the present invention mainly refers to ethylene, propylene, and ethylene-rich dry gas or propylene-rich liquefied gas from catalytic cracking devices, with a light olefin content of 20-50% by weight.

[0077] In one embodiment, the first reactor is selected from a fluidized bed reactor, a moving bed reactor or a fixed bed reactor, preferably a moving bed reactor; and / or

[0078] The first reactor is provided with 3 or more light olefin injection ports in sections.

[0079] In the present invention, the benzene-rich gasoline intermediate fraction reaction oil and gas enters a moving bed or fluidized bed or fixed bed reactor and contacts with a light olefin-rich logistics in stages, and the light olefin fraction is injected in stages to maintain the olefin / benzene molar ratio within a certain range; the catalyst in the moving bed reactor is in a uniform downward moving state, the catalyst and the reaction logistics can be contacted and reacted in a co-current manner or in a counter-current manner, preferably in a counter-current manner, and more than three light olefin logistics injection ports are arranged in sections; the catalyst in the fluidized bed reactor is in a turbulent fluidization state, the oil and gas apparent average linear velocity is 0.2-2.0 m / s, the catalyst and the reaction logistics can be an ascending bed or a descending bed, preferably an ascending bed, and more than three light olefin logistics injection ports are arranged in sections; the fixed bed reactor can be a conventional radial flow fixed bed reactor, preferably a tubular reactor, and the catalyst is loaded in at least two reaction zones, and a light olefin logistics injection port is arranged upstream of each reaction zone.

[0080] In one embodiment, the catalyst comprises a mesoporous molecular sieve, a heat-resistant inorganic oxide and optionally clay, wherein the mesoporous molecular sieve accounts for 40 to 80 weight percent of the total amount of the catalyst;

[0081] Preferably, the mesoporous molecular sieve is selected from the mordenite series and / or ZSM series mesoporous zeolite, more preferably the ZSM series mesoporous zeolite; and / or

[0082] Preferably, the heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide.

[0083] The mesoporous molecular sieve catalyst of the present invention is a catalyst composed of a molecular sieve and a heat-resistant inorganic oxide, wherein the catalyst molecular sieve is an optional mesoporous zeolite of the mercerized series and the ZSM series; the heat-resistant inorganic oxide is a binder such as aluminum oxide, silicon oxide and / or an optional natural porous carrier material such as clay; preferably, the composite is composed of a ZSM series mesoporous zeolite, a binder such as aluminum oxide, silicon oxide and an optional natural porous carrier material such as clay, wherein the mesoporous molecular sieve accounts for 40-80% by weight of the total catalyst, and the rest is the carrier component.

[0084] In one embodiment, the catalytic alkylation reaction temperature is 250 to 450°C, preferably 300 to 400°C;

[0085] The reaction pressure is 0.1 to 5.0 MPa, preferably 0.5 to 4.0 MPa;

[0086] The weight ratio of catalyst to feedstock oil is 1.0 to 9.0:1, preferably 2.0 to 6.0:1; and / or

[0087] Weight hourly space velocity is 0.2~20.0h -1 , preferably 1.0~5.0h -1 .

[0088] In the present invention, the reactor and the regenerator can be arranged in parallel or overlapped, and the fluidized bed and the settler of the fluidized bed reactor can be internal or external; the spent catalyst can be stripped and lifted by nitrogen and / or water vapor and other media when entering the regenerator, and the regenerated catalyst is stripped, deoxygenated and dehydrated by nitrogen, and then returned to the reaction stage for recycling.

[0089] In one embodiment, the oxygen-containing regeneration atmosphere is air and / or oxygen atmosphere, preferably oxygen-enriched and / or pure oxygen atmosphere;

[0090] The regeneration temperature of the regenerator is 450-750°C, preferably 500-700°C;

[0091] The regeneration pressure of the regenerator is 0.2 to 5.0 MPa, preferably 0.5 to 5.0 MPa; and / or

[0092] The flue gas temperature circulating back to the regenerator is 300-600°C.

[0093] In the present invention, the catalyst after the reaction enters the oxygen-containing regeneration system for regeneration, and air and / or oxygen can be used for regeneration; preferably, oxygen-enriched and / or pure oxygen is used for regeneration. The flue gas after regeneration is partially or completely circulated back to the regenerator, and the oxygen-containing high-temperature flue gas is not heat exchanged or partially heat exchanged, and its temperature is 300-600°C, and partially and / or completely returned to the regenerator for recycling, making full use of the oxygen in the flue gas and maintaining a high regeneration temperature of the regenerator and a high regeneration agent temperature.

[0094] The alkylation debenzenization of benzene-rich gasoline of the present invention can be coupled with the catalytic cracking of heavy oils such as wax oil and residual oil, and the reaction is carried out in two different reactors, and a catalyst regeneration system and an oil-gas separation system are shared, so the integration is high. Moreover, after the alkylation reaction, the catalyst is regenerated and recycled, or added into a heavy oil catalytic cracking reactor, so that not only continuous production is realized, but also a high activity of the catalyst can be always maintained, thereby solving the problem that the alkylation catalyst is easily coked and deactivated when processing high-olefin catalytic cracking gasoline or steam cracking gasoline.

[0095] The method of reducing the benzene content in gasoline by coupling the present invention with heavy oil catalytic cracking comprises:

[0096] (1) catalytically cracking the heavy oil in a second reactor to obtain a second mixed material comprising a second spent catalyst and a second oil and gas;

[0097] (2) performing oil-gas separation on the second mixed material in an oil-gas separation system to obtain a dry gas component, a liquefied gas component, and a gasoline component;

[0098] (3) distilling the gasoline components in a gasoline distillation system to obtain a self-produced gasoline benzene-rich fraction and a low-benzene gasoline;

[0099] (4) the self-produced gasoline benzene-rich fraction and any other gasoline benzene-rich fraction are introduced into the first reactor and contacted with the graded injected light olefin stream under non-hydrogenation or hydrogenation conditions to carry out a catalytic alkylation reaction to obtain a first mixed material comprising a first spent catalyst and a first oil gas;

[0100] (5) allowing the first mixed material to pass through the oil separation filter of the first reactor for separation, and the separated oil and gas enter the oil and gas separation system for oil and gas separation;

[0101] (6) The separated first catalyst to be regenerated enters the second reactor and is mixed with the second catalyst to be regenerated. After being stripped by the steam exchanger of the second reactor, it enters the regenerator for oxygen-containing regeneration. The regenerated catalyst is returned to the first reactor and the second reactor for recycling. Preferably, part or all of the flue gas after regeneration is recycled back to the regenerator.

[0102] Wherein, the heavy oil is wax oil and / or residual oil.

[0103] The low-benzene gasoline of the present invention has a benzene content of less than 1.0 weight %, preferably less than 0.8 weight %.

[0104] In one embodiment, the gasoline benzene-rich fraction is obtained by distilling and cutting the benzene-rich gasoline to obtain a benzene-rich gasoline middle fraction with a distillation range of 60 to 90° C.

[0105] Wherein, the benzene content of the benzene-rich gasoline is 0.8 to 40 weight %;

[0106] Preferably, the benzene-rich gasoline is catalytic cracking gasoline, hydrocracking gasoline, reforming gasoline and / or steam cracking gasoline with a boiling point of 30 to 220°C.

[0107] The present invention is further described in detail by way of examples. The raw materials used in the examples can be obtained through commercial sources.

[0108] The following examples will further illustrate the method, but are not intended to limit the method.

[0109] In the embodiment, the full-fraction gasoline feedstock A is catalytic cracking gasoline from a refinery. A is distilled and cut to obtain a benzene-rich fraction feedstock oil B. The low-carbon olefin-rich stream is a catalytic cracking concentrated dry gas containing 40% by weight of ethylene in a refinery after deoxygenation and desulfurization. The heavy feedstock oil is hydrogenated residue oil from a refinery. The properties of the three feedstock oils are shown in Table 1.

[0110] The catalysts used in the examples are the same, and their preparation methods are briefly described as follows:

[0111] 1) 20.0 kg of MFI structured mesoporous ZRP-1 zeolite powder (industrial product of Sinopec Catalyst Qilu Branch, SiO2 / Al2O3=30, phosphorus content P2O5=3.5 wt%, solid content 91.75%) and 113.3 kg of 3 wt% ammonium chloride aqueous solution were stirred in a reactor at 70-80°C for 2 hours and ammonium exchanged twice; the mixture was cooled, the liquid was removed, and an ion exchange catalyst was obtained after washing with water; the ion exchange catalyst was dried at 120°C and calcined at 500°C for 3 hours to obtain an H-type ZRP-1 molecular sieve.

[0112] 2) 5.1 kg of halloysite (industrial product of Suzhou Clay Company, solid content 71.6 wt%) was slurried with 28.4 kg of decationized water, and then 3.4 kg of pseudo-boehmite (industrial product of Shandong Aluminum Plant, solid content 63 wt%) was added to slurry to obtain a slurry with a solid content of 5-30 wt%; the pH was adjusted to 2-4 with hydrochloric acid, stirred evenly, and aged at 60-70°C for 1 hour to obtain a mixed carrier slurry.

[0113] 3) Forming and drying: 18 kg of H-type ZRP-1 molecular sieve (solid content of 91% by weight) obtained in step 1) was mixed with 48 kg of decationized water at a solid-liquid ratio of 1:1-1:10, added to the mixed carrier slurry obtained in step 2), stirred evenly, and 4.4 kg of aluminum sol (produced by Sinopec Catalyst Qilu Branch, with an Al2O3 content of 21.7% by weight, wherein the ratio of catalyst solid content to aluminum sol solid content (in terms of alumina) was 10-50:1) was added, and the mixture was placed in a bonding machine and stirred continuously until a uniform sol was formed; the sol was placed in the air for 4 hours, formed by rolling with a rolling machine, and then placed for 24 hours, and then dried in a drying oven at 120°C for 3 hours, and free Na + , dried at about 120°C for 3 hours, and then calcined at 500-800°C for 3 hours to obtain a catalyst named CAT-Z1.

[0114] CAT-Z1 has an average particle size of 2-4 mm and is used as a moving bed alkylation catalyst. The catalyst is composed on a dry basis of 70.82 wt% of MFI structure medium pore zeolite, 9.26 wt% of pseudo-boehmite, 4.13 wt% of aluminum sol and 15.79% of kaolin. Its properties are listed in Table 2.

[0115] The heavy oil catalytic cracking catalyst is a CGP special agent produced by Sinopec Catalyst Qilu Branch, containing ZSM-5 molecular sieve and Y molecular sieve. Its properties are listed in Table 2.

[0116] Example 1

[0117] This embodiment follows Figure 1 The process was tested using the feedstock B in Table 1, i.e., the benzene-rich fraction of catalytic cracking gasoline, as the feedstock, and an alkylation reaction was carried out with staged injection of ethylene in a moving bed reactor using a CAT-Z1 catalyst.

[0118] like Figure 1 As shown, in this embodiment, benzene-rich gasoline 1 is subjected to high-precision distillation cutting in distillation tower VII to obtain a gasoline light fraction 1a without aromatics, a gasoline middle fraction 1b rich in benzene and a gasoline heavy fraction 1c rich in aromatics, wherein the gasoline middle fraction 1b rich in benzene is generally controlled to have a distillation range of 60-90°C, and more than 50% of the benzene in the gasoline is enriched.

[0119] Using a moving bed reactor I, the benzene-rich gasoline middle fraction 1b is fed into the reactor at the bottom of the moving bed reactor to contact the catalyst, and is contacted with the low-carbon olefins injected from the bottom, middle and upper parts of the reactor for alkylation reaction. The spent catalyst after the reaction is separated from the oil and gas and then regenerated, and the regenerated flue gas is partially recycled back to the regenerator. The process flow is as follows:

[0120] The gasoline benzene-rich fraction 1 is fed into the reactor at the lower part of the reactor I to contact the catalyst, and undergoes an alkylation reaction with the light olefin gas I2 fed from the bottom of the reactor. According to the catalyst fluidization requirements, a fluidizing medium 3 can be injected into the bottom of the reactor; after a period of reaction, it is further contacted with the light olefin gas II4 and light olefin gas III5 injected into the middle and upper parts of the reactor to strengthen the alkylation of benzene; the spent catalyst after the reaction is separated from the oil and gas by the oil filter separator IV, and the separated catalyst is settled and then enters the steam exchanger 24 through the spent catalyst delivery pipeline I10, and then is nitrogen After stripping with gas and / or water vapor, the catalyst enters the regenerator II through the regenerated catalyst delivery pipeline II11; the regenerated catalyst is regenerated in an oxygen-containing atmosphere in the regenerator, and the oxygen-containing regeneration gas 15 includes air, oxygen, etc., and the regeneration temperature is 450-550°C. The regenerated catalyst returns to the reactor I for recycling through the regeneration agent delivery pipeline I12 and the regeneration agent delivery pipeline II13; part of the regenerated flue gas 16 is circulated back to the regenerator through the flue gas circulation pipeline 17; the separated reaction oil and gas enter the oil and gas separation system III through the reaction oil and gas pipeline 6, and the product dry gas 7, liquefied gas 8, and gasoline 9 are separated.

[0121] Catalytic cracking gasoline feedstock A is distilled and cut using a 30-plate distillation tower (theoretical plate number 18), and a 60-90°C middle fraction rich in benzene is extracted from the middle section of the tower to obtain feedstock B, with a yield of 16.0%. This cutting method consumes 21.59 kg EO / t feedstock.

[0122] The feedstock oil B is preheated at 180°C and enters the lower part of the moving fluidized bed reactor I to undergo an alkylation reaction with ethylene fed from the bottom of the reactor. At a reaction pressure of 1.0 MPa, hydrogen is used as a fluidizing medium. As the fluidizing medium flows from bottom to top, ethylene is injected into the lower, middle and upper regions of the reactor three times and the molar ratio of ethylene to benzene in the reaction system is maintained at 4.0. At a reaction temperature (based on the upper part of the reactor, i.e., the outlet temperature, the same below) of 400°C, a weight ratio of catalyst to feedstock oil of 3.1, and a weight hourly space velocity of 5.0 h -1 The alkylation reaction is carried out under the following conditions; the oil agent is separated after the reaction, and the separated reaction oil and gas are separated into dry gas, liquefied gas and gasoline products by the separation system; the spent catalyst after the oil agent separation is stripped by nitrogen to remove the oil and gas adsorbed inside it and then sent to the regenerator, and oxygen is used as the regeneration gas to contact with the spent catalyst at a regeneration temperature of 500°C for regeneration; the regenerated regenerated agent is recycled, and the regenerated flue gas is partially recycled, the circulating flue gas temperature is 400°C, and the regeneration dense phase temperature is maintained at 500°C. The operating conditions and product distribution are listed in Table 3.

[0123] As can be seen from Table 3, in Example 1, the benzene-rich fraction of the catalytic cracking gasoline with a benzene content of 7.68% and an octane number RON 83.6 was subjected to an alkylation reaction with ethylene in a moving bed reactor, and the benzene conversion rate was 96.42%, the gasoline yield was 81.25 wt%, the benzene content of the gasoline was reduced to 0.25 wt%, the octane number RON 89.1 was increased by 5.5 units, and the liquefied gas yield reached 15.55 wt%.

[0124] Comparative Example 1

[0125] By using uncut catalytic cracking gasoline feedstock A as raw material, the alkylation reaction is carried out using the same catalyst and process conditions as in Example 1, except that: 1) Comparative Example 1 uses a riser reactor; 2) ethylene is injected only at the bottom of the reactor; 3) air is used as the regeneration gas, and the flue gas is not circulated; 4) in order to maintain the same process conditions as in Example 1, it is necessary to spray combustion oil in the regenerator to provide heat. The operating conditions and product distribution are listed in Table 3.

[0126] As can be seen from Table 3, compared with Comparative Example 1 (riser reactor), Example 1 (moving bed reactor) has a benzene conversion rate that is 63.33 percentage points higher, a gasoline benzene content that is 1.03 percentage points lower, and an octane number RON improvement that is 4.0 units higher, and a liquefied gas yield that is 7.83 percentage points higher.

[0127] Example 2

[0128] This embodiment follows Figure 2 The heavy crude oil C in Table 1 was used as the raw material. The catalytic cracking gasoline D obtained by cracking was subjected to high-precision distillation and cutting to obtain the gasoline benzene-rich fraction E. The heavy crude oil C and the gasoline benzene-rich fraction E were tested in a riser reactor and a moving bed reactor, respectively, using catalysts CGP and CAT-Z1, respectively.

[0129] Figure 2 The process flow diagram of Example 2 is the same as that of Example 1 in that the gasoline benzene-rich fraction alkylation adopts a moving bed reactor I, and the difference is that the heavy crude oil 19 enters a conventional riser reactor, and the catalyst after the benzene alkylation reaction and the catalyst after the heavy oil catalytic cracking reaction can be stripped separately and then enter the same regenerator, or they can share a settler for stripping. In this embodiment, the two use a settler. The process flow is as follows:

[0130] The heavy crude oil 19 is atomized by atomizing steam and fed into the lower part of the heavy oil cracking reactor VI to contact the catalytic cracking catalyst for cracking reaction; the separated reaction oil and gas enter the oil and gas separation system III through the reaction oil and gas pipeline 6 to separate the product dry gas 7, liquefied gas 8, gasoline 9, diesel 22 and oil slurry 23; the gasoline 9 is separated into a self-produced gasoline benzene-rich fraction 25 and a low-benzene gasoline 26 after distillation through a gasoline distillation tower V. The self-produced gasoline benzene-rich fraction 25 is partially recycled or not returned to the reactor I as needed, and the low-benzene gasoline 26 after distillation is discharged from the device for gasoline pool blending. The benzene-rich fraction 25 of the self-produced gasoline and the optional benzene-rich gasoline middle fraction 1b of the benzene-rich gasoline from the distillation tower are fed into the reactor at the lower part of the reactor I to contact the catalyst and undergo alkylation reaction with the light olefin gas I2 fed from the bottom of the reactor; after a period of reaction, they are further contacted with the light olefin gas II4 and light olefin gas III5 injected into the middle and upper parts of the reactor to strengthen the alkylation of benzene; the spent catalyst after the alkylation reaction is separated from the oil gas by the oil agent filter separator IV, and the separated catalyst is settled and then enters the heavy oil cracking reactor V through the spent catalyst delivery pipeline I10. I, and then after stripping by nitrogen and / or water vapor 14 in the steam exchanger 24, it enters the regenerator II through the spent catalyst delivery pipeline II11; the spent catalyst is regenerated in the oxygen-containing atmosphere in the regenerator II, and the oxygen-containing regeneration gas 15 includes air, oxygen, etc., and the regeneration temperature is 600-700°C. The regenerated catalyst is recycled, and the regenerated catalyst is delivered to the heavy oil cracking reactor VI through the regeneration agent delivery pipeline I12, and delivered to the reactor I through the regeneration agent delivery pipeline II13; the separated reaction oil and gas enter the oil and gas separation system III through the reaction oil and gas pipeline 6 for product separation. It should be noted that in this embodiment, the alkylation catalyst is supplemented into the reactor I through the dosing pipeline 18, and since the alkylation catalyst is also a propylene additive or octane improver for heavy oil cracking, the amount of the alkylation catalyst entering the heavy feedstock oil cracking reactor needs to meet the requirements of benzene alkylation and heavy oil cracking.

[0131] The heavy crude oil was preheated at 200°C and then placed at the bottom of the riser reactor to contact the catalytic cracking catalyst for cracking reaction. At a reaction pressure of 0.35 MPa, water vapor was used as the fluidizing and atomizing medium. As the fluidizing medium flowed from bottom to top, the reaction temperature (based on the outlet temperature of the upper part of the reactor, the same below) was 540°C, the weight ratio of catalyst to crude oil was 7.4, the mass ratio of atomized water to crude oil was 11.8, and the weight hourly space velocity was 20.0 h. -1 The cracking reaction was carried out under the following conditions.

[0132] Gasoline D obtained by catalytic cracking of heavy crude oil is subjected to high-precision distillation cutting using a distillation tower 1 with 30 plates (theoretical plate number 15) and a distillation tower 2 with 50 plates (theoretical plate number 25). The light gasoline fraction at the bottom of distillation tower 1 enters distillation tower 2, and a 60-90°C middle fraction rich in benzene, i.e. gasoline benzene-rich fraction E, is extracted at the top of distillation tower 2, with a yield of 29.4% of catalytic cracking gasoline D. This cutting method consumes 14.66 kg EO / t of raw material. The properties of catalytic cracking gasoline D and gasoline benzene-rich fraction E are shown in Table 1.

[0133] After being preheated at 300°C, the gasoline benzene-rich fraction E enters the lower part of the moving fluidized bed reactor I and undergoes an alkylation reaction with the ethylene-rich dry gas fed from the bottom of the reactor. The alkylation dry gas provides both low-carbon olefins and a hydrogen atmosphere. At a reaction pressure of 0.5 MPa, it flows from bottom to top, and ethylene is injected into the lower, middle, and upper regions of the reactor three times, maintaining a molar ratio of ethylene to benzene in the reaction system of 5.9. At a reaction temperature of 350°C, a weight ratio of catalyst to feedstock oil of 4.7, and a weight hourly space velocity of 2.0 h -1 The alkylation reaction is carried out under the following conditions, and the oil agent is separated after the reaction.

[0134] The separated reaction oil and gas enter the oil and gas separation system through the reaction oil and gas pipeline, and are separated into product dry gas, liquefied gas, gasoline, diesel and oil slurry. The gasoline is separated into self-produced benzene-rich gasoline and low-benzene gasoline through a gasoline distillation tower, and the self-produced benzene-rich gasoline is circulated back to the reactor.

[0135] The reaction oil and gas after separation of the gasoline benzene-rich fraction alkylation oil agent are merged into the heavy oil cracking oil and gas pipeline. The separated spent catalyst enters the settling section of the heavy crude oil catalytic cracking reactor, and is sent to the regenerator after being stripped by steam to remove the oil and gas adsorbed inside. Air is used as the regeneration gas and is regenerated by contact with the spent catalyst at a regeneration dense phase temperature of 680°C. The regenerated regenerated agent is recycled, but the regenerated flue gas is not recycled.

[0136] The operating conditions and product distribution are listed in Table 4.

[0137] As can be seen from Table 4, in Example 2, after alkylation of the gasoline benzene-rich fraction with a benzene content of 7.72% and an octane number RON 82.4, the benzene conversion rate is 89.24%, the benzene content of the gasoline is reduced to 0.77%, the octane number RON is increased to 88.0, and the liquefied gas yield is as high as 8.55%; when the gasoline benzene-rich fraction is alkylated as a recycling and is not included in the raw materials, the liquefied gas yield of the heavy oil catalytic cracking is 28.75% by weight, the gasoline yield is 34.09% by weight, the gasoline olefin content is 8.54% by weight, the benzene content is 0.42% by weight, and the octane number RON is 98.3.

[0138] Comparative Example 2

[0139] The same heavy crude oil C as in Example 2 was used as the raw material, and the same catalyst and process conditions as in Example 2 were used to carry out the cracking reaction, except that: 1) the gasoline obtained by cracking the heavy crude oil in Example 2 was not cut; 2) the gasoline was all fed to the upper part of the riser reactor for recycling and alkylation reaction with ethylene in the dry gas. The operating conditions and product distribution are listed in Table 4.

[0140] As can be seen from Table 4, compared with Comparative Example 2 (alkylation in a riser reactor without gasoline cutting), Example 2 (moving bed alkylation after gasoline cutting) has a gasoline benzene content that is 1.21 percentage points lower, an octane number RON that is 1.8 units higher, and a liquefied gas yield that is 7.3 percentage points higher.

[0141] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

[0142] Table 1

[0143]

[0144] Table 2

[0145]

[0146]

[0147] Table 3

[0148]

[0149]

[0150] Table 4

[0151]

[0152] The # column represents the data obtained by sampling and analyzing at the outlet of the catalytic cracking oil separator of the riser reactor (based on crude oil C)

[0153] The ## column represents the data obtained by sampling and analyzing at the outlet of the oil filter separator of the moving bed reactor (based on the gasoline benzene-rich fraction E)

[0154] The ### column represents the overall data of Example 2 (based on raw oil C).

Claims

1. A method for reducing the benzene content in gasoline, characterized in that: The method comprises: (1) distilling and cutting the benzene-rich gasoline to obtain a benzene-rich gasoline middle distillate with a distillation range of 60 to 90° C.; (2) the benzene-rich gasoline middle fraction enters the first reactor and contacts the catalyst with the graded injected light olefin-rich stream under hydrogenation conditions to carry out a catalytic alkylation reaction, thereby obtaining a first mixed material comprising a first spent catalyst and a first oil gas; (3) allowing the first mixed material to pass through the oil separation filter of the first reactor for separation, and the separated first oil and gas enter the oil and gas separation system for product separation to obtain products including dry gas, liquefied gas and gasoline; (4) the separated first catalyst to be regenerated is stripped in a steam exchanger and then enters a regenerator for oxygen-containing regeneration. The regenerated catalyst is returned to the first reactor for recycling. Preferably, part or all of the flue gas after regeneration is recycled back to the regenerator; The benzene content of the benzene-rich gasoline is 0.8 to 40% by weight; the low-carbon olefin is ethylene and / or propylene; Preferably, in step (2), the molar ratio of light olefins to benzene is maintained at 3 to 9:1, preferably 4 to 8:

1.

2. The method according to claim 1, characterized in that The light olefin content in the light olefin-rich stream is 20 to 50 weight %; Preferably, the light olefin-rich stream is selected from one or more of the following: an ethylene stream, a propylene stream, ethylene-rich dry gas, and propylene-rich liquefied gas.

3. The method according to claim 1, characterized in that The catalytic alkylation reaction temperature is 250-450°C, preferably 300-400°C; The reaction pressure is 0.1 to 5.0 MPa, preferably 0.5 to 4.0 MPa; The weight ratio of catalyst to feedstock oil is 1.0 to 9.0:1, preferably 2.0 to 6.0:1; and / or Weight hourly space velocity is 0.2~20.0h -1 , preferably 1.0~5.0h -1 .

4. The method according to claim 1, characterized in that: The first reactor is selected from a fluidized bed reactor, a moving bed reactor or a fixed bed reactor, preferably a moving bed reactor; and / or The first reactor is provided with 3 or more light olefin injection ports in sections.

5. The method according to claim 1, characterized in that The distillation and cutting of the benzene-rich gasoline is carried out by using one or more distillation towers; Preferably, the total theoretical plate number of the distillation tower is greater than or equal to 14.

6. The method according to claim 1, characterized in that The catalyst comprises a mesoporous molecular sieve, a heat-resistant inorganic oxide and optional clay, wherein the mesoporous molecular sieve accounts for 40 to 80 weight percent of the total amount of the catalyst; Preferably, the mesoporous molecular sieve is selected from the mordenite series and / or ZSM series mesoporous zeolite, more preferably the ZSM series mesoporous zeolite; and / or Preferably, the heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide.

7. The method according to claim 1, characterized in that The benzene-rich gasoline is catalytic cracking gasoline, hydrocracking gasoline, reforming gasoline and / or steam cracking gasoline with a boiling point of 30 to 220° C.; and / or The benzene-rich gasoline middle fraction is preheated before entering the first reactor, and the preheating temperature is 100-350°C, preferably 150-300°C.

8. The method according to claim 1, characterized in that The oxygen-containing regeneration atmosphere is air and / or oxygen atmosphere, preferably oxygen-enriched and / or pure oxygen atmosphere; The regeneration temperature of the regenerator is 450-750°C, preferably 500-700°C; The regeneration pressure of the regenerator is 0.2 to 5.0 MPa, preferably 0.5 to 5.0 MPa; and / or The flue gas temperature circulating back to the regenerator is 300-600°C.

9. A method for producing low-benzene gasoline, characterized in that: The method comprises: (1) catalytically cracking the heavy oil in a second reactor to obtain a second mixed material comprising a second spent catalyst and a second oil and gas; (2) performing oil-gas separation on the second mixed material in an oil-gas separation system to obtain a dry gas component, a liquefied gas component, and a gasoline component; (3) distilling the gasoline components in a gasoline distillation system to obtain a self-produced gasoline benzene-rich fraction and a low-benzene gasoline; (4) the self-produced gasoline benzene-rich fraction and any other gasoline benzene-rich fraction enter the first reactor and contact the catalyst with the graded injected light olefin stream under non-hydrogenation or hydrogenation conditions to perform a catalytic alkylation reaction to obtain a first mixed material comprising a first spent catalyst and a first oil gas; (5) allowing the first mixed material to pass through the oil separation filter of the first reactor for separation, and the separated oil and gas enter the oil and gas separation system for oil and gas separation; (6) The separated first catalyst to be regenerated enters the second reactor and is mixed with the second catalyst to be regenerated. After being stripped by the steam exchanger of the second reactor, it enters the regenerator for oxygen-containing regeneration. The regenerated catalyst is returned to the first reactor and the second reactor for recycling. Preferably, part or all of the flue gas after regeneration is recycled back to the regenerator. Wherein, the heavy oil is wax oil and / or residual oil.

10. The method according to claim 9, characterized in that The gasoline benzene-rich fraction is obtained by distilling and cutting the benzene-rich gasoline to obtain a benzene-rich gasoline middle fraction with a distillation range of 60 to 90° C. Wherein, the benzene content of the benzene-rich gasoline is 0.8 to 40 weight %; Preferably, the benzene-rich gasoline is catalytic cracking gasoline, hydrocracking gasoline, reforming gasoline and / or steam cracking gasoline with a boiling point of 30 to 220°C.

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