Method and reaction system for preparing low-carbon olefin through catalytic conversion of etherified gasoline

Abstract

The invention discloses a method and a reaction system for preparing low-carbon olefin by catalytic conversion of etherified gasoline, which can realize high-selectivity conversion of etherified gasoline into low-carbon olefin, furthest obtain ethylene and propylene and improve the selectivity of methane and coke.

Description

Method and reaction system for catalytic conversion of etherified gasoline to produce low-carbon olefins Technical Field

[0001] This application belongs to the field of petroleum processing, and specifically relates to a method and reaction system for the catalytic conversion of etherified gasoline to prepare low-carbon olefins. Background Technology

[0002] With the rapid development of the national economy, environmental pollution has received increasing attention, and environmental regulations have become increasingly stringent, leading to a continued slowdown in the growth rate of refined oil demand. In the near future, demand for low-carbon olefins will remain strong, making the transformation of oil refining towards chemical production inevitable. Ethylene and propylene are two high-value basic organic chemical raw materials. Ethylene is an important basic organic chemical raw material, mainly used in the production of polyethylene, ethylene propylene rubber, polyvinyl chloride, ethanol, ethylene oxide, ethylene glycol, acetaldehyde, acetic acid, propionaldehyde, propionic acid and their derivatives, and other basic organic synthetic raw materials; it is widely used in the pharmaceutical and chemical industries. Propylene is an important basic chemical raw material for the production of propylene derivatives (such as polypropylene, acrylonitrile, and propylene oxide). Etherified gasoline has a high octane number and is widely used globally as a gasoline octane number blending agent. Similarly, catalytic gasoline etherification involves reacting reactive C5 and C6 olefins in catalytic cracking gasoline with alcohols to produce alkyl tertiary alkyl ethers, reducing the olefin content and vapor pressure of catalytic gasoline, while simultaneously converting low-value methanol into high-value gasoline products. This is a clean gasoline production process with considerable economic benefits.

[0003] CN102451674B discloses a catalyst for the cracking of methyl tert-butyl ether to isobutylene, its preparation method, and its application, with the aim of producing high-purity isobutylene. This method utilizes a catalyst prepared for the cracking of methyl tert-butyl ether to isobutylene, enabling the reaction to be completed under relatively high pressure, achieving high conversion and selectivity, and extending the equipment's operating cycle.

[0004] CN109225349A discloses a method for preparing a catalyst for the cracking of methyl tert-butyl ether to isobutylene. The catalyst prepared by this method can reduce the temperature required for the cracking reaction of methyl tert-butyl ether, has high selectivity for isobutylene and methanol, and also has a high conversion rate. It does not require the addition of inert substances such as water to the reaction system, has low energy consumption, and high equipment utilization.

[0005] Most of the catalysts or processes disclosed in existing patents or literature for the cracking of methyl tert-butyl ether to produce olefins are used to produce high-purity olefins with four or more carbon atoms. For example, the cracking of methyl tert-butyl ether is used to prepare high-purity isobutylene. However, there are very few reports on the use of etherified gasoline to produce low-carbon olefins such as ethylene and propylene. Summary of the Invention

[0006] One object of this application is to provide a method for maximizing the production of low-carbon olefins from etherified gasoline, which enables the conversion of etherified gasoline into low-carbon olefins, increases the yield and selectivity of ethylene, propylene and butene, and reduces the methane yield.

[0007] A first aspect of the present invention provides a method for the catalytic conversion of etherified gasoline to prepare low-carbon olefins, comprising:

[0008] (1) Feedstock containing etherified gasoline enters the catalytic conversion reactor and comes into contact with the catalytic conversion catalyst to undergo a catalytic conversion reaction, thereby obtaining the catalytic conversion reaction product;

[0009] (2) Separate the catalytic conversion reaction products to obtain a first olefin stream containing C2-C4 olefins and a second recycle stream containing light gasoline. Separate the second recycle stream to obtain a light gasoline stream. Optionally, further separate the first olefin stream into ethylene, propylene and butene.

[0010] (3) At least a portion of the light gasoline stream and optional external olefins enter the etherification unit and contact with alcohol feedstock to carry out the etherification reaction to obtain recycled etherified gasoline and etherified olefins. At least a portion of the recycled etherified gasoline is returned to the catalytic conversion reactor for recycling.

[0011] (4) At least a portion of the etherified olefin enters the isomerization unit and reacts with the isomerization catalyst to obtain isomerized olefin, which is then returned to the etherification unit for recycling.

[0012] According to the method of the first aspect, in step (1), the mass fraction of etherified gasoline in the feedstock oil is not less than 20%, preferably not less than 30%, more preferably not less than 50%, and most preferably not less than 80%; and / or

[0013] The etherified gasoline has a final boiling point of not more than 120°C, preferably not more than 110°C, more preferably not more than 100°C, and most preferably not more than 95°C.

[0014] According to the method of the first aspect, in step (1), the catalytic conversion reaction conditions include:

[0015] The reaction temperature is 460-750℃, preferably 500-700℃, more preferably 520-700℃, and most preferably 550-680℃;

[0016] The reaction time is 0.01-15 seconds, preferably 0.05-10 seconds, more preferably 0.1-8.0 seconds, and most preferably 0.15-7.0 seconds; and / or

[0017] The weight ratio of the agent to oil is 1-50, preferably 5-40, and more preferably 6-30.

[0018] According to the method of the first aspect, in step (1), the catalytic conversion catalyst is selected from amorphous silica-alumina catalysts and / or zeolite catalysts, and the zeolite in the zeolite catalyst is selected from Y-type series macroporous molecular sieves, β-type macroporous zeolite molecular sieves, ZSM-type series mesoporous molecular sieves, and SAPO-type series small-pore molecular sieves.

[0019] Preferably, the zeolite in the catalytic conversion catalyst is selected from ZSM-type molecular sieves, more preferably from ZSM-5, ZSM-11 molecular sieves and hierarchical porous molecular sieves, wherein the silicon-aluminum molar ratio SiO2 / AlO3 of the molecular sieve is 50-1000, more preferably 80-800, and most preferably 100-800;

[0020] More preferably, the ZSM-type molecular sieve in the catalytic conversion catalyst is a high-silica zeolite containing phosphorus and transition metals, and its anhydrous chemical expression, based on the mass of the oxide, is (0-0.3)Na₂O·(0.3-5)Al₂O₃·(1-10)P₂O₅·(0.7-20)M x O y ·(70-95)SiO2, where element M is selected from one or more of rare earth elements, alkali metals and alkaline earth metals, Fe, Co, Ni, Cu, Zn, Mo and Mn, x is the oxidation state of oxygen, and y is the oxidation state of element M.

[0021] According to the method of the first aspect, in step (1), the catalytic conversion reaction product includes:

[0022] The methane yield is no more than 5.0%, preferably no more than 2.0%, and most preferably no more than 1.0%.

[0023] The mass ratio of ethylene to methane is not less than 4.0, preferably not less than 8.0, and most preferably not less than 12.

[0024] The mass fraction ratio of propylene to propane is not less than 10, preferably not less than 15, and most preferably not less than 30.

[0025] According to the method of the first aspect, in step (2), the light gasoline has a final boiling point of not more than 90°C, preferably not more than 80°C, more preferably not more than 75°C, and most preferably not more than 70°C.

[0026] According to the method of the first aspect, in step (3), the etherification reaction conditions include:

[0027] The reaction temperature is 20-120℃, preferably 30-80℃, and more preferably 35-75℃;

[0028] The reaction pressure is 0-5.0 MPa, preferably 0.2-2.0 MPa, more preferably 0.5-1.5 MPa; and / or

[0029] The alcohol raw materials are selected from one or more of methanol, ethanol, propanol, butanol, and pentanol, preferably methanol, ethanol, or a combination thereof.

[0030] According to the method of the first aspect, in step (4), the isomerization catalyst comprises a support and a modified oxide, wherein:

[0031] The carrier comprises a zeolite molecular sieve and a binder. Preferably, the carrier comprises 50-99% by mass of molecular sieve and 1-50% by mass of binder. The molecular sieve is a molecular sieve with MFI, FER, TON and AEL structures, and the binder is alumina.

[0032] The modified oxide is a polyol, and the mass ratio of the modified oxide to the carrier is preferably 0.01 to 0.3:1. Preferably, the polyol is a C2 to C7 polyol, and more preferably one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol and sorbitol.

[0033] According to the method of the first aspect, in step (4), the isomerization reaction conditions include:

[0034] The reaction temperature is 150-500℃, preferably 250-480℃, more preferably 300-450℃, and most preferably 350-450℃; and / or

[0035] Heavy hourly space velocity is 1-30 h -1 Preferably 2-20h -1 More preferably 5-15h -1 .

[0036] A second aspect of the present invention provides a reaction system for the catalytic conversion of etherified gasoline to prepare low-carbon olefins, comprising:

[0037] The catalytic conversion unit includes a catalytic conversion reactor, an oil-gas separator, and a regenerator, wherein:

[0038] A catalytic conversion reactor is used to bring feedstock containing etherified gasoline into contact with a catalytic conversion catalyst in the reactor to carry out a catalytic conversion reaction, thereby obtaining catalytic conversion reaction products.

[0039] An oil-gas separation device, connected to the catalytic conversion reactor, is used to separate the catalytic conversion reaction products and the catalytic conversion catalyst to be generated after the reaction.

[0040] A regenerator is used to regenerate the catalytic conversion catalyst to be generated after the reaction. The regenerator is equipped with a waiting inclined tube and a regeneration inclined tube. The catalytic conversion catalyst to be generated after the reaction from the oil and gas separation unit enters the regenerator through the waiting inclined tube, and the regenerated catalytic conversion catalyst returns to the catalytic conversion reactor through the regeneration inclined tube.

[0041] A separation unit, connected to the catalytic conversion unit, includes a single-stage or multi-stage separation device for separating the catalytic conversion reaction products to obtain a first olefin stream containing C2-C4 olefins and a second recycle stream containing light gasoline, and separating the second recycle stream to obtain a light gasoline stream.

[0042] An etherification unit, connected to the separation unit, is used to contact at least a portion of the light gasoline stream from the separation unit and optionally externally sourced olefins with alcohol feedstock in the etherification unit to obtain recycled etherified gasoline and post-etherified olefins. The etherification unit is also connected to the catalytic conversion reactor of the catalytic conversion unit for returning at least a portion of the recycled etherified gasoline to the catalytic conversion reactor for catalytic conversion reaction.

[0043] Specifically, the method of this application has at least one of the following technical effects compared with the prior art:

[0044] 1. Etherified gasoline is prepared from olefins and alcohols, and alcohols can be produced at low cost from coal, low-quality high-sulfur coal and coke oven gas, as well as biomass (such as wood, organic waste, etc.), thereby achieving low-cost production of low-carbon olefins.

[0045] 2. Biomass is the process by which plants fix carbon dioxide using solar energy and store it as chemical energy. Alcohols are produced from biomass energy, which are then reacted with olefins to produce etherified gasoline, ultimately converting it into low-carbon olefins, thus enabling the recycling of carbon resources.

[0046] 3. It can achieve highly selective conversion of etherified gasoline into low-carbon olefins, maximizing the yield of ethylene and propylene, while improving the selectivity of methane and coke. Attached Figure Description

[0047] Figure 1 shows an apparatus for the catalytic conversion of etherified gasoline to produce low-carbon olefins according to this application.

[0048] Figure 2 shows a device diagram of one specific embodiment of this application.

[0049] Figure 3 shows a device diagram of a comparative example of this application.

[0050] Explanation of reference numerals in the attached figures:

[0051] 100. Catalytic Conversion Unit; 200. First Separation Unit; 201. First Olefin Stream Separation Unit; 202. Second Recycle Stream Separation Unit; 300. Etherification Unit; 400. Isomerization Unit; 101. Feedstock; 102. Catalytic Conversion Reaction Products; 103. First Olefin Stream; 104. Second Recycle Stream; 105. Ethylene; 106. Propylene; 107. Butene; 108. Light Gasoline Stream; 109. Externally Sourced Olefins; 110. Alcohol Feedstock; 111. Recycled Etherified Gasoline; 112. Post-Etherification Olefins; 113. Non-Olefin Components; 114. Isomeric Olefins; 115. Recycled Methyl Tert-Butyl Ether Return Line;

[0052] 1. Pre-lifting medium pipeline; 2. Variable diameter fluidized bed reactor; 3. Etherified gasoline mixture pipeline; 4. Atomizing steam pipeline; 5. Cooling agent pipeline; 6. Settler; 7. First reaction zone; 8. Second reaction zone; 9. Stripping section; 10. Stripping steam pipeline; 11. Regenerator inclined tube; 12. Regenerator; 13. Main air pipeline; 14. Flue gas pipeline; 15. Regeneration inclined tube; 16. Main oil and gas pipeline; 17. Fractionation, absorption-stabilization unit; 8. Dry gas pipeline; 19. Liquefied petroleum gas pipeline; 20. Gasoline pipeline; 21. Diesel fuel; 22. Oil slurry; 23. Gas separation unit; 24. Propylene pipeline; 25. Butene pipeline; 26. Gasoline separator; 27. Light gasoline pipeline at <65℃; 28. Methanol; 29. ​​Etherification unit; 30. Post-etherification olefin pipeline; 31. Non-olefin component pipeline; 32. Isomerization unit; 33. Iso-olefin pipeline; 34. Recycled etherified gasoline pipeline. Detailed Implementation

[0053] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0054] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0055] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0056] The "etherified gasoline" described in this invention refers to gasoline containing at least one component that is reacted with an alcohol to obtain gasoline with C n H 2n+1 -OC m H 2m+1The structural formula is given, wherein m and n are each independent integers greater than or equal to 1, preferably 1-10, more preferably 1-6, and most preferably a mixture of 1-4.

[0057] This invention provides a method for the catalytic conversion of etherified gasoline to prepare low-carbon olefins, comprising:

[0058] (1) Feedstock containing etherified gasoline enters the catalytic conversion reactor and comes into contact with the catalytic conversion catalyst to undergo a catalytic conversion reaction, thereby obtaining the catalytic conversion reaction product;

[0059] (2) Separate the catalytic conversion reaction products to obtain a first olefin stream containing C2-C4 olefins and a second recycle stream containing light gasoline. Separate the second recycle stream to obtain a light gasoline stream. Optionally, further separate the first olefin stream into ethylene, propylene and butene.

[0060] (3) At least a portion of the light gasoline stream and optional external olefins enter the etherification unit and contact with alcohol feedstock to carry out the etherification reaction to obtain recycled etherified gasoline and etherified olefins. At least a portion of the recycled etherified gasoline is returned to the catalytic conversion reactor for recycling.

[0061] (4) At least a portion of the etherified olefin enters the isomerization unit and reacts with the isomerization catalyst to obtain isomerized olefin, which is then returned to the etherification unit for recycling.

[0062] The method of this application includes: introducing at least a portion of the post-etherified olefins into an isomerization unit for isomerization in the presence of an isomerization catalyst to obtain isomerized olefins. The inventors of this application have discovered that, compared to isomerized olefins, the conversion rate of normal-type olefins to ethers via condensation reactions with alcohols is lower, resulting in a higher proportion of normal-type olefins in the post-etherified olefins after etherification. Simultaneously, ethers generated from the condensation reaction of isomerized olefins with alcohols are more readily converted into low-carbon olefins such as ethylene and propylene in catalytic conversion reactions. Therefore, at least a portion of the post-etherified olefins can be introduced into an isomerization unit for isomerization in the presence of an isomerization catalyst to obtain isomerized olefins; and, as described above, these isomerized olefins are further converted into corresponding ether compounds as part of the olefin feedstock supplied to the etherification unit. The method of this invention, by producing low-carbon olefins such as ethylene and propylene from etherified gasoline, can maximize the production of low-carbon olefins.

[0063] In one embodiment, in step (1), the mass fraction of etherified gasoline in the feedstock oil is not less than 20%, preferably not less than 30%, more preferably not less than 50%, and most preferably not less than 80%; and / or

[0064] The etherified gasoline has a final boiling point of not more than 120°C, preferably not more than 110°C, more preferably not more than 100°C, and most preferably not more than 95°C.

[0065] In one embodiment, the catalytic conversion reaction conditions in step (1) include:

[0066] The reaction temperature is 460-750℃, preferably 500-700℃, more preferably 520-700℃, and most preferably 550-680℃;

[0067] The reaction time is 0.01-15 seconds, preferably 0.05-10 seconds, more preferably 0.1-8.0 seconds, and most preferably 0.15-7.0 seconds; and / or

[0068] The weight ratio of the agent to oil is 1-50, preferably 5-40, and more preferably 6-30.

[0069] In this application, reaction time refers to the residence time of the feedstock oil in the reactor. The catalyst-to-oil weight ratio refers to the weight ratio of the catalyst to the feedstock oil entering the reactor.

[0070] The inventors of this application have discovered that when the temperature is below 200°C, etherified gasoline is converted into alcohols and olefins, with a low selectivity for low-carbon olefins (the total amount of ethylene and propylene), below 10%, which is not conducive to maximizing the production of low-carbon olefins. However, when the reaction temperature is increased to above 460°C, especially above 550°C, the selectivity for low-carbon olefins (the total amount of ethylene and propylene) in the product increases significantly, particularly the ethylene selectivity, and the ethylene / methane mass ratio decreases significantly, thereby maximizing the production of high-value-added low-carbon olefins.

[0071] In one embodiment, in step (1), the catalytic conversion catalyst is selected from amorphous silica-alumina catalysts and / or zeolite catalysts. The zeolite in the zeolite catalyst is selected from Y-type macroporous molecular sieves, β-type macroporous zeolite molecular sieves, ZSM-type mesoporous molecular sieves, and SAPO-type microporous molecular sieves. SAPO-type molecular sieve catalysts include, but are not limited to, SAPO-34 and SAPO-18 molecular sieves.

[0072] Preferably, the zeolite in the catalytic conversion catalyst is selected from ZSM-type molecular sieves, more preferably from ZSM-5, ZSM-11 molecular sieves and hierarchical porous molecular sieves, wherein the silicon-aluminum molar ratio SiO2 / AlO3 of the molecular sieve is 50-1000, more preferably 80-800, and most preferably 100-800;

[0073] More preferably, the ZSM-type molecular sieve in the catalytic conversion catalyst is a high-silica zeolite containing phosphorus and transition metals, and its anhydrous chemical expression, based on the mass of the oxide, is (0-0.3)Na₂O·(0.3-5)Al₂O₃·(1-10)P₂O₅·(0.7-20)M x O y ·(70-95)SiO2, where element M is selected from one or more of rare earth elements, alkali metals and alkaline earth metals, Fe, Co, Ni, Cu, Zn, Mo and Mn, x is the oxidation state of oxygen, and y is the oxidation state of element M.

[0074] The inventors of this application have discovered that, under appropriate catalytic conversion conditions, ether feedstocks can be readily cracked into C2 and C3 olefins (i.e., ethylene and propylene), as well as C4 or C5+ olefins. As described below, these C4 or C5+ olefins can be converted into corresponding ether compounds through etherification reactions, and these ether compounds can be repeatedly subjected to catalytic conversion reactions to further convert the C4 or C5+ olefins into low-carbon olefins such as ethylene and propylene.

[0075] The catalytic conversion reaction products obtained above can be divided into dry gas components (mainly including ethylene, methane, ethane, etc.), liquefied petroleum gas components (mainly including propylene, as well as propane, butane, butene, etc.), and gasoline components (mainly including C5+ olefins, etc.) according to their distillation range. In this application, the proportion of non-olefin products such as methane, ethane, and propane in the catalytic conversion reaction products is low.

[0076] In one embodiment, in step (1), the catalytic conversion reaction product includes:

[0077] The methane yield is no more than 5.0%, preferably no more than 2.0%, and most preferably no more than 1.0%.

[0078] The mass ratio of ethylene to methane is not less than 4.0, preferably not less than 8.0, and most preferably not less than 12.

[0079] The mass fraction ratio of propylene to propane is not less than 10, preferably not less than 15, and most preferably not less than 30.

[0080] In one embodiment, in step (2), the light gasoline has a final boiling point of no more than 90°C, preferably no more than 80°C, more preferably no more than 75°C, and most preferably no more than 70°C.

[0081] In one embodiment, the etherification reaction conditions in step (3) include:

[0082] The reaction temperature is 20-120℃, preferably 30-80℃, and more preferably 35-75℃;

[0083] The reaction pressure is 0-5.0 MPa, preferably 0.2-2.0 MPa, more preferably 0.5-1.5 MPa; and / or

[0084] The alcohol raw materials are selected from one or more of methanol, ethanol, propanol, butanol, and pentanol, preferably methanol, ethanol, or a combination thereof.

[0085] The alcohol feedstock used in this application can be obtained at low cost from coal, low-quality high-sulfur coal and coke oven gas, as well as biomass (such as forest trees, organic waste, etc.), thereby achieving low-cost etherification reaction; biomass is the carbon dioxide fixed by plants through solar energy and stored in the form of chemical energy. Alcohols are prepared through biomass energy, further ethers are obtained, and finally converted into low-carbon olefins, which can realize the recycling of carbon resources and the low-cost production of low-carbon olefins.

[0086] Through this etherification reaction and etherification unit, high-carbon olefins (such as butene and C5+ olefins) generated by the catalytic conversion of etherified gasoline, as well as isomerized olefins and external olefins described later, can be converted into the corresponding etherified gasoline. This etherified gasoline can be fed as a component into a catalytic conversion reactor for further catalytic conversion, thereby converting C4 or C5+ olefins into low-carbon olefins such as ethylene and propylene. This increases the yield of low-carbon olefins such as ethylene and propylene.

[0087] In one embodiment, in step (4), the isomerization catalyst comprises a support and a modified oxide, wherein:

[0088] The carrier comprises a zeolite molecular sieve and a binder. Preferably, the carrier comprises 50-99% by mass of molecular sieve and 1-50% by mass of binder. The molecular sieve is a molecular sieve with MFI, FER, TON and AEL structures, and the binder is alumina.

[0089] The modified oxide is a polyol, and the mass ratio of the modified oxide to the carrier is preferably 0.01 to 0.3:1. Preferably, the polyol is a C2 to C7 polyol, and more preferably one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol and sorbitol.

[0090] In one embodiment, the isomerization reaction conditions in step (4) include:

[0091] The reaction temperature is 150-500℃, preferably 250-480℃, more preferably 300-450℃, and most preferably 350-450℃; and / or

[0092] Heavy hourly space velocity is 1-30 h -1 Preferably 2-20h-1 More preferably 5-15h -1 .

[0093] This invention also provides a reaction system for the catalytic conversion of etherified gasoline to prepare low-carbon olefins, comprising:

[0094] The catalytic conversion unit includes a catalytic conversion reactor, an oil-gas separator, and a regenerator, wherein:

[0095] A catalytic conversion reactor is used to bring feedstock containing etherified gasoline into contact with a catalytic conversion catalyst in the reactor to carry out a catalytic conversion reaction, thereby obtaining catalytic conversion reaction products.

[0096] An oil-gas separation device, connected to the catalytic conversion reactor, is used to separate the catalytic conversion reaction products and the catalytic conversion catalyst to be generated after the reaction.

[0097] A regenerator is used to regenerate the catalytic conversion catalyst to be generated after the reaction. The regenerator is equipped with a waiting inclined tube and a regeneration inclined tube. The catalytic conversion catalyst to be generated after the reaction from the oil and gas separation unit enters the regenerator through the waiting inclined tube, and the regenerated catalytic conversion catalyst returns to the catalytic conversion reactor through the regeneration inclined tube.

[0098] A separation unit, connected to the catalytic conversion unit, includes a single-stage or multi-stage separation device for separating the catalytic conversion reaction products to obtain a first olefin stream containing C2-C4 olefins and a second recycle stream containing light gasoline, and separating the second recycle stream to obtain a light gasoline stream.

[0099] An etherification unit, connected to the separation unit, is used to contact at least a portion of the light gasoline stream from the separation unit and optionally externally sourced olefins with alcohol feedstock in the etherification unit to obtain recycled etherified gasoline and post-etherified olefins. The etherification unit is also connected to the catalytic conversion reactor of the catalytic conversion unit for returning at least a portion of the recycled etherified gasoline to the catalytic conversion reactor for catalytic conversion reaction.

[0100] According to this application, the catalytic conversion reactor is selected from any one and / or a combination of two or more reactor types, such as fixed bed, moving bed, and fluidized bed reactors; preferably, the fixed bed reactor is selected from two or more reactors connected in series or parallel; optionally, the fluidized bed reactor is selected from one or more reactors connected in series or parallel, such as constant diameter riser, constant linear velocity riser, variable diameter riser, fluidized bed and a composite reactor composed of constant diameter riser and fluidized bed, upward conveying line, and downward conveying line.

[0101] In one specific embodiment, the catalytic conversion reactor can be a fluidized bed reactor of various forms, such as a single fluidized bed reactor or a composite reactor obtained by combining multiple fluidized bed reactors in series or parallel. In some preferred embodiments, the fluidized bed reactor can be a constant-diameter riser reactor or a fluidized bed reactor of various variable diameter forms, such as the reactor disclosed in Chinese Patent CN112569875A.

[0102] The separation unit of the present invention can be a common separation device in the art, such as a fractionation tower, which can separate the components into different components according to their distillation range. For example, catalytic cracking reaction products can be separated into dry gas components, liquefied petroleum gas components, gasoline components, diesel components, and slurry components in a fractionation tower, and then ethylene components can be separated from the dry gas components in another separation device, propylene components can be separated from the liquefied petroleum gas components in another separation device, and FGO components can be separated from the slurry components.

[0103] In the etherification unit of this invention, olefin feedstock and alcohol feedstock can react in the presence of a catalyst to obtain the corresponding ether. This etherification reaction can be carried out using processes known in the art.

[0104] For example, in the presence of an acid catalyst, olefin feedstocks can be brought into contact with alcohol feedstocks to undergo a condensation reaction, thereby generating the corresponding ethers. Commonly used acid catalysts include sulfuric acid, phosphoric acid, and aluminum trichloride.

[0105] In the presence of an alkaline catalyst, olefin feedstocks can be brought into contact with alcohol feedstocks to undergo a condensation reaction, thereby generating the corresponding ethers. Commonly used alkaline catalysts include sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0106] In the presence of a metal catalyst, olefin feedstocks can be brought into contact with alcohol feedstocks to undergo a condensation reaction, thereby generating the corresponding ethers. Commonly used metal catalysts include copper, iron, and palladium.

[0107] Figure 1 illustrates an apparatus for the catalytic conversion of etherified gasoline to produce low-carbon olefins according to this application, comprising:

[0108] The catalytic conversion unit 100 is used to bring the feedstock oil into contact with the catalytic conversion catalyst in the catalytic conversion reactor to carry out the catalytic conversion reaction and obtain the catalytic conversion reaction product. The catalytic conversion unit 100 includes a catalytic conversion reactor, a settling tank and a regenerator (not shown in the figure).

[0109] A separation unit 200 is connected to a catalytic conversion unit 100, such that catalytic conversion reaction products from the catalytic conversion reactor are transported to the separation unit for separating the catalytic conversion reaction products, including a first olefin stream containing C2-C4 olefins and / or a second recycle stream containing light gasoline.

[0110] The separation unit 200 further includes a first olefin stream separation unit 201 and a second recycle stream separation unit 202. The first olefin stream separation unit 201 is connected to the separation unit 200 and is used to separate ethylene, propylene and butene in the first olefin stream. The second recycle stream separation unit 202 is connected to the separation unit and is used to separate light gasoline in the second recycle stream.

[0111] Etherification unit 300, which is connected to second circulating stream separation unit 202, allows light gasoline stream to enter the etherification unit and contact with alcohol feedstock under etherification conditions to obtain recycled etherified gasoline and etherified olefins;

[0112] An isomerization unit 400 is connected to an etherification unit 300, such that at least a portion of the post-etherified olefins enter the isomerization unit to undergo an isomerization reaction in the presence of an isomerization catalyst to obtain isomerized olefins, and the isomerized olefins are also recycled back to the etherification unit 300 for further etherification reaction.

[0113] The etherification unit 300 is also connected to the catalytic conversion unit 100, and is used to recycle recycled etherified gasoline and optional post-etherified olefins back to the catalytic conversion unit 100 for catalytic conversion reaction.

[0114] Feedstock 101 containing etherified gasoline is fed into catalytic conversion unit 100 and reacted with catalytic conversion catalyst under effective conditions to obtain catalytic conversion reaction products. The catalytic conversion reaction products are then separated in separation unit 200 to obtain a first olefin stream 103 containing C2-C4 olefins and a second recycle stream 104 containing light gasoline. The first olefin stream 103 containing C2-C4 olefins is further separated in the first olefin stream separation unit 201 to obtain the target products ethylene 105, propylene 106, and butene 107, and the second recycle stream 104 containing light gasoline. 4. Light gasoline stream 108 is separated through the second circulating stream separation unit 202. Light gasoline stream 108 and optional externally sourced olefins 109 are fed into the etherification unit 300 for etherification reaction to obtain circulating etherified gasoline 111 and post-etherified olefins 112. Circulating etherified gasoline 111 is returned to the catalytic conversion unit 100, and post-etherified olefins 112 are sent to the isomerization unit 400, or returned to the catalytic conversion unit 100 via the post-etherified olefin return line 115. Isomerized olefins 114 are returned to the etherification unit 300 to continue the etherification reaction, and non-olefin components 113 are sent downstream.

[0115] The following description, in conjunction with Figure 2, illustrates a specific implementation of the method of this application, but does not limit the scope of this application.

[0116] The pre-lifting medium enters from the bottom of the variable-diameter fluidized bed reactor 2 (e.g., the reactor disclosed in Chinese Patent CN112569875A) via pipeline 1. The etherified gasoline mixture, along with atomized steam from pipeline 4, is injected into the bottom of the first reaction zone 7 of the variable-diameter fluidized bed reactor 2 via pipeline 3 and nozzles, where it contacts the regenerated catalyst from the regeneration inclined tube 15 within the reactor. It then moves upwards into the second reaction zone 8 of the variable-diameter fluidized bed reactor 2 to continue the reaction. The generated oil and gas, along with the deactivated catalyst, enters the cyclone separator in the settling tank 6 to separate the catalyst from the oil and gas. The reacted oil and gas enters the main oil and gas pipeline 16, while the catalyst powder returns to the settling tank 6 via the cyclone separator feed leg. The catalyst in the settling tank 6 flows to the stripping section 9, where it contacts the stripping steam from pipeline 10. The oil and gas stripped from the catalyst enters the main oil and gas pipeline 16 after passing through the cyclone separator. After stripping, the spent catalyst enters the regenerator 12 through the spent catalyst inclined tube 11. The main air enters the regenerator through pipeline 13 to burn off the coke on the spent catalyst, thus regenerating the deactivated spent catalyst. The flue gas is then led out through pipeline 14. The regenerated catalyst enters the variable diameter fluidized bed reactor 2 through the regeneration inclined tube 15 for recycling.

[0117] The reaction oil and gas pass through the large oil and gas pipeline 16 and enter the fractionation, absorption-stabilization unit 17. The separated dry gas is led out through pipeline 18 and separated to obtain ethylene. The liquefied gas is led out through pipeline 19 and separated into propylene through gas separation unit 23 and sent out through pipeline 24. Butene is led out through pipeline 25. The gasoline from pipeline 20 is sent to the separation unit 26 to obtain light gasoline with a temperature of <65℃. The gasoline and methanol from pipeline 28 are sent to the etherification unit 29. The etherified gasoline is returned to the riser reactor through pipeline 34 to react and increase the production of low-carbon olefins. The etherified olefins are sent to the isomerization unit 32 through pipeline 30. The isomerized olefins are returned to the etherification unit 29 through pipeline 33. The unreacted non-olefin components are sent to the downstream unit through pipeline 31.

[0118] The present application will be further described below with reference to the embodiments, but this does not limit the present application. The properties of the feedstock oil used in the embodiments and comparative examples are as follows: the catalyst used in the embodiments and comparative examples is a commercially available catalytic conversion catalyst with the brand name TCC-1, manufactured by Sinopec Catalyst Qilu Branch; the isomerization catalyst used in the embodiments is a commercially available catalyst with the brand name FI-15, manufactured by Sinopec Petrochemical Research Institute; the catalyst used in the etherification unit in the embodiments is CN101245255B, which is consistent with the catalyst used in the embodiments.

[0119] Table 1. Properties of raw materials in examples and comparative examples.

[0120]

[0121]

[0122] Comparative Example 1

[0123] The experiment was conducted according to the process shown in Figure 3. The feedstock was etherified gasoline, and TCC-1 was used as the catalyst. The experiment was carried out on a variable diameter fluidized bed reactor catalytic cracking unit (the specific structure of the variable diameter fluidized bed reactor is shown in Example 1 of CN112569875A). The unit does not include etherification and isomerization units. The target products of ethylene and propylene were obtained. The reaction conditions and product distribution are listed in Table 2.

[0124] Comparative Example 2

[0125] The experiment was conducted according to the process shown in Figure 3, using etherified gasoline as the feedstock and TCC-1 as the catalyst. The experiment was carried out in a variable-diameter fluidized bed reactor catalytic cracking unit (the specific structure of the variable-diameter fluidized bed reactor is shown in Example 1 of CN112569875A). The unit did not include etherification and isomerization units. The target products, ethylene and propylene, were obtained. The reaction conditions and product distribution are listed in Table 2. The difference from Example 1 is that the reaction temperature was 450℃.

[0126] Example 1

[0127] The experiment was conducted according to the process shown in Figure 2, using etherified gasoline as the feedstock and TCC-1 as the catalyst. The experiment was carried out in a variable-diameter fluidized bed reactor catalytic cracking unit (the specific structure of the variable-diameter fluidized bed reactor is shown in Example 1 of CN112569875A), yielding the target products of ethylene and propylene. The reaction conditions and product distribution are listed in Table 2. The difference from Example 1 is that after the C4 olefins and gasoline undergo etherification and isomerization operations, they are returned to the variable-diameter fluidized bed reactor catalytic cracking unit.

[0128] Table 2 Reaction conditions and product distribution of the examples

[0129]

[0130]

[0131] The results above show that the method of the present invention can achieve highly selective conversion of etherified gasoline into low-carbon olefins, maximizing the yield of ethylene and propylene, while improving the selectivity of methane and coke.

[0132] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0133] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0134] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A method for the catalytic conversion of etherified gasoline to prepare low-carbon olefins, comprising: (1) Feedstock containing etherified gasoline enters the catalytic conversion reactor and comes into contact with the catalytic conversion catalyst to undergo a catalytic conversion reaction, thereby obtaining the catalytic conversion reaction product; (2) The catalytic conversion reaction products are separated to obtain a first olefin stream containing C2-C4 olefins and a second recycle stream containing light gasoline. The second recycle stream is separated to obtain a light gasoline stream. Optionally, the first olefin stream is further separated into ethylene, propylene and butene. (3) At least a portion of the light gasoline stream and optional externally sourced olefins are introduced into the etherification unit and contacted with alcohol feedstock to undergo an etherification reaction to obtain recycle etherified gasoline and post-etherified olefins. At least a portion of the recycle etherified gasoline is returned to the catalytic conversion reactor for recycling. (4) At least a portion of the post-etherified olefins are introduced into the isomerization unit and contacted with the isomerization catalyst to undergo a reaction to obtain isomerized olefins. The isomerized olefins are returned to the etherification unit for recycling.

2. The method according to claim 1, characterized in that, In step (1), the mass fraction of etherified gasoline in the feedstock oil is not less than 20%, preferably not less than 30%, more preferably not less than 50%, and most preferably not less than 80%; and / or the etherified gasoline has a final boiling point of not more than 120°C, preferably not more than 110°C, more preferably not more than 100°C, and most preferably not more than 95°C.

3. The method according to claim 1, characterized in that, In step (1), the catalytic conversion reaction conditions include: a reaction temperature of 460-750℃, preferably 500-700℃, more preferably 520-700℃, and most preferably 550-680℃; a reaction time of 0.01-15 seconds, preferably 0.05-10 seconds, more preferably 0.1-8.0 seconds, and most preferably 0.15-7.0 seconds; and / or an agent-oil weight ratio of 1-50, preferably 5-40, and more preferably 6-30.

4. The method according to claim 1, characterized in that, In step (1), the catalytic conversion catalyst is selected from amorphous silica-alumina catalysts and / or zeolite catalysts. The zeolite in the zeolite catalyst is selected from Y-type macroporous molecular sieves, β-type macroporous zeolite molecular sieves, ZSM-type mesoporous molecular sieves, and SAPO-type microporous molecular sieves. Preferably, the zeolite in the catalytic conversion catalyst is selected from ZSM-type molecular sieves, more preferably from ZSM-5, ZSM-11 molecular sieves, and hierarchical molecular sieves, wherein the silica-alumina molar ratio SiO2 / AlO3 of the molecular sieve is 50-1000, preferably 80-800, and most preferably 100-800. More preferably, the ZSM-type molecular sieve in the catalytic conversion catalyst is a high-silica zeolite containing phosphorus and transition metals, and its anhydrous chemical expression, based on the mass of oxides, is (0-0.3)Na2O·(0.3-5)Al2O3·(1-10)P2O5·(0.7-20)M x O y ·(70-95)SiO2, where element M is selected from one or more of rare earth elements, alkali metals and alkaline earth metals, Fe, Co, Ni, Cu, Zn, Mo and Mn, x is the oxidation state of oxygen, and y is the oxidation state of element M.

5. The method according to claim 1, characterized in that, In step (1), the catalytic conversion reaction products have the following characteristics: methane yield not greater than 5.0%, preferably not greater than 2.0%, and most preferably not greater than 1.0%; ethylene to methane mass ratio not less than 4.0, preferably not less than 8.0, and most preferably not less than 12; and propylene to propane mass fraction ratio not less than 10, preferably not less than 15, and most preferably not less than 30.

6. The method according to claim 1, characterized in that, In step (2), the light gasoline has a final boiling point of no more than 90°C, preferably no more than 80°C, more preferably no more than 75°C, and most preferably no more than 70°C.

7. The method according to claim 1, characterized in that, In step (3), the etherification reaction conditions include: a reaction temperature of 20-120℃, preferably 30-80℃, more preferably 35-75℃; a reaction pressure of 0-5.0MPa, preferably 0.2-2.0MPa, more preferably 0.5-1.5MPa; and / or the alcohol raw material is selected from one or more of methanol, ethanol, propanol, butanol, and pentanol, preferably methanol, ethanol, or a combination thereof.

8. The method according to claim 1, characterized in that, In step (4), the isomerization catalyst includes a support and a modified oxide, wherein: the support includes a zeolite molecular sieve and a binder, preferably, the support includes 50-99% by mass of molecular sieve and 1-50% by mass of binder; the molecular sieve is a molecular sieve with MFI structure, FER structure, TON structure and AEL structure, and the binder is alumina; the modified oxide is a polyol, and the mass ratio of the modified oxide to the support is preferably 0.01-0.3:1, preferably, the polyol is a C2-C7 polyol, more preferably one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol and sorbitol.

9. The method according to claim 1, characterized in that, In step (4), the isomerization reaction conditions include: a reaction temperature of 150-500℃, preferably 250-480℃, more preferably 300-450℃, and most preferably 350-450℃; and / or a heavy hourly space velocity of 1-30 h⁻¹. -1 Preferably 2-20h -1 More preferably 5-15h -1 .

10. A reaction system for the catalytic conversion of etherified gasoline to produce low-carbon olefins, comprising: The catalytic conversion unit includes a catalytic conversion reactor, an oil-gas separator, and a regenerator. The catalytic conversion reactor is used to contact a feedstock containing etherified gasoline with a catalytic conversion catalyst to carry out a catalytic conversion reaction, obtaining catalytic conversion reaction products. The oil-gas separator is connected to the catalytic conversion reactor and is used to separate the catalytic conversion reaction products and the catalytic conversion catalyst to be recycled after the reaction. The regenerator is used to regenerate the catalytic conversion catalyst to be recycled after the reaction. The regenerator is equipped with a recycled inclined tube and a regeneration inclined tube. The catalytic conversion catalyst to be recycled after the reaction from the oil-gas separator enters the regenerator through the recycled inclined tube, and the regenerated catalytic conversion catalyst returns to the reactor through the regeneration inclined tube. A conversion reactor; a separation unit connected to the catalytic conversion unit, comprising one or more stages of separation devices for separating the catalytic conversion reaction products to obtain a first olefin stream containing C2-C4 olefins and a second recycle stream containing light gasoline, and separating the second recycle stream to obtain a light gasoline stream; an etherification unit connected to the separation unit for contacting at least a portion of the light gasoline stream from the separation unit and optionally externally sourced olefins with alcohol feedstock in the etherification unit to obtain recycle etherified gasoline and post-etherified olefins, the etherification unit also being connected to the catalytic conversion reactor of the catalytic conversion unit for returning at least a portion of the recycle etherified gasoline to the catalytic conversion reactor for catalytic conversion reaction.

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