Method and device for preparing low-carbon olefin

Abstract

The invention relates to a method and device for preparing low-carbon olefins, and the method comprises the following steps: S1, contacting raw oil with a catalytic conversion catalyst in a catalytic conversion reactor for catalytic conversion reaction to obtain a catalytic conversion reaction product; s2, separating the catalytic conversion reaction product to obtain ethylene and propylene as well as a first circulating olefin flow containing butene and / or a second circulating olefin flow containing C5 + olefin; s3, enabling the olefin material to enter an etherification unit, and contacting the olefin material with an alcohol raw material under an etherification condition to obtain a circulating ether material and etherified olefin; and S4, enabling at least one part of etherified olefin to enter an isomerization unit, and carrying out isomerization reaction in the presence of an isomerization catalyst to obtain isomerized olefin. According to the method disclosed by the invention, the conversion of ethers into low-carbon olefins can be realized, the yield and selectivity of ethylene and propylene are improved, the yield of methane is reduced, the content of methanol in the product is reduced to the greatest extent, and the conversion of low-cost methanol into low-carbon olefins is realized.

Description

Technical Field

[0001] This application relates to the field of low-carbon olefin preparation, specifically to a method and apparatus for catalytically converting ether compounds into low-carbon olefins. Background Technology

[0002] Increasingly stringent environmental regulations have led 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, 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). Methyl tert-butyl ether has a high octane number and is widely used globally as a gasoline octane number blender. Similarly, catalytic light gasoline ether chemistry reacts reactive C5 and C6 olefins in catalytic cracking light gasoline with alcohols to produce alkyl tert-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 ethers 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 produce high-purity isobutylene. There are very few reports on using ethers to produce low-carbon olefins such as ethylene and propylene. There is a need in the art for further methods and apparatus for the preparation of low-carbon olefins such as ethylene and propylene. Summary of the Invention

[0006] This application provides a method for preparing low-carbon olefins, comprising:

[0007] S1 allows the feedstock oil to come into contact with the catalytic conversion catalyst in the catalytic conversion reactor to carry out a catalytic conversion reaction, thereby obtaining the catalytic conversion reaction product;

[0008] S2 separates the catalytic conversion reaction products to yield ethylene and propylene, as well as a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream;

[0009] S3 allows olefin feedstock to enter the etherification unit, where it comes into contact with alcohol feedstock under etherification conditions to obtain recycled ether materials and post-etherified olefins.

[0010] S4 causes at least a portion of the post-etherified olefin to enter the isomerization unit and undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin.

[0011] The feedstock oil includes ether feedstocks, recycled ether materials, and optionally a portion of post-etherified olefins; wherein the ether feedstocks have C n H 2n+1 -OC m H 2m+1 The structure is as follows, where m and n are each independent integers greater than or equal to 1, preferably 1-10, more preferably 1-6, and most preferably 1-4;

[0012] The olefin feed comprises at least a portion of a first-cycle olefin stream and / or at least a portion of a second-cycle olefin stream, as well as isomerized olefins and optional externally sourced olefins.

[0013] In one embodiment, the ether raw material is selected from one or more of methyl tert-butyl ether, methyl tert-pentyl ether, methyl tert-hexyl ether, methyl tert-heptyl ether, methyl sec-butyl ether, methyl sec-pentyl ether, methyl sec-hexyl ether, methyl sec-heptyl ether, ethyl tert-butyl ether, ethyl tert-pentyl ether, ethyl tert-heptyl ether, ethyl sec-butyl ether, ethyl sec-pentyl ether, ethyl sec-hexyl ether, dimethyl ether, methyl ethyl ether, and diethyl ether; preferably, the ether raw material comes from an etherification unit, which is selected from a methyl tert-butyl ether unit, a light gasoline etherification unit, an ethyl tert-butyl ether unit, and combinations thereof.

[0014] In one embodiment, the reaction temperature of the catalytic conversion reaction is about 460-750°C, preferably about 500-700°C, more preferably about 520-700°C, and most preferably about 550-680°C.

[0015] In one embodiment, the reaction time of the catalytic conversion reaction is about 0.01-15 seconds, preferably about 0.05-10 seconds, more preferably about 0.1-8.0 seconds, and most preferably about 0.15-7.0 seconds; the agent-to-oil weight ratio is about 1-50, preferably about 5-40, and more preferably about 6-30.

[0016] In one embodiment, the alcohol raw material is selected from one or more of methanol, ethanol, propanol, butanol, and pentanol; preferably, the alcohol raw material is selected from methanol, ethanol, or a combination thereof.

[0017] In one embodiment, the etherification conditions include: a reaction temperature of about 20-120°C, preferably about 30-80°C, more preferably about 35-75°C; and a reaction pressure of 0-5.0 MPa, preferably 0.2-2.0 MPa, more preferably 0.5-1.5 MPa.

[0018] In one embodiment, the isomerization reaction conditions include: a reaction temperature of about 150-500°C, preferably about 250-480°C, more preferably about 300-450°C, and most preferably about 350-450°C; and a weight hourly space velocity of about 1-30 h⁻¹. -1 Preferably about 2-20 hours -1 More preferably about 5-15 hours -1 .

[0019] In one embodiment, the isomerization catalyst comprises a support and a modified oxide, wherein the support comprises a zeolite molecular sieve and a binder, the support comprising 50-99% by mass of the molecular sieve and 1-50% by mass of the binder, the molecular sieve being a molecular sieve having an MFI structure, a FER structure, a TON structure, and an AEL structure, and the binder being alumina; the modified oxide is a polyol, and the mass ratio of the modified oxide to the support is 0.01-0.3:1; preferably, the polyol is a C2-C7 polyol, selected from one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol, and sorbitol.

[0020] In one embodiment, the catalytic conversion catalyst is selected from amorphous silica-alumina catalysts and / or zeolite catalysts, wherein the zeolite in the zeolite catalyst is selected from Y-type series molecular sieve catalysts, β-type zeolite molecular sieves, ZSM-type series molecular sieve catalysts, and SAPO-type series molecular sieves.

[0021] In one embodiment, the catalytic conversion catalyst is selected from ZSM-type molecular sieves, preferably from ZSM-5, ZSM-11 molecular sieves and hierarchical porous molecular sieves, wherein the silicon-aluminum molar ratio of the molecular sieve, SiO2 / AlO3, is 50-1000, preferably 80-800, and most preferably 100-800.

[0022] In one embodiment, the catalytic conversion catalyst is a high-silica zeolite containing phosphorus and transition metals, whose anhydrous chemical formula, based on the mass of the 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.

[0023] This application also provides an apparatus for preparing low-carbon olefins, comprising:

[0024] A catalytic conversion reactor is used to bring feedstock oil into contact with a catalytic conversion catalyst to carry out a catalytic conversion reaction, thereby obtaining catalytic conversion reaction products;

[0025] A separation unit, connected to a catalytic conversion reactor, is used to separate the catalytic conversion products from the reactor, yielding ethylene and propylene, and a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream;

[0026] An etherification unit is connected to a separation unit, allowing olefin materials to enter the etherification unit and contact with alcohol feedstock under etherification conditions to obtain recycled ether materials and etherified olefins.

[0027] An isomerization unit is connected to the etherification unit, such that at least a portion of the post-etherified olefin enters the isomerization unit to undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin, and the isomerized olefin is also recycled back to the etherification unit for another etherification reaction.

[0028] The etherification unit is also connected to the catalytic conversion reactor, and is used to recycle the recycled ether material and optional post-etherified olefins back to the catalytic conversion reactor for catalytic conversion reaction.

[0029] The method described in this application can convert ethers into low-carbon olefins, improve the yield and selectivity of ethylene and propylene, reduce the yield of methane, and minimize the methanol content in the product, thus achieving low-cost methanol-to-low-carbon olefin conversion. It can also improve the selectivity and yield of low-carbon olefins and significantly reduce the yield of methane in dry gas, resulting in good economic and social benefits. Attached Figure Description

[0030] Figure 1 An apparatus for preparing low-carbon olefins according to this application is shown;

[0031] Figure 2 One specific implementation of the method of this application is shown;

[0032] Figure 3 A specific implementation of the comparative method is shown. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] 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.

[0036] This application provides a method for preparing low-carbon olefins, comprising:

[0037] S1 allows the feedstock oil to come into contact with the catalytic conversion catalyst in the catalytic conversion reactor to carry out a catalytic conversion reaction, thereby obtaining the catalytic conversion reaction product;

[0038] S2 separates the catalytic conversion reaction products to yield ethylene and propylene, as well as a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream;

[0039] S3 allows olefin feedstock to enter the etherification unit, where it comes into contact with alcohol feedstock under etherification conditions to obtain recycled ether materials and post-etherified olefins.

[0040] S4 causes at least a portion of the post-etherified olefin to enter the isomerization unit and undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin.

[0041] The feedstock oil includes ether feedstocks, recycled ether materials, and optionally a portion of post-etherified olefins; wherein the ether feedstocks have C n H 2n+1 -OC m H 2m+1 The structure is as follows, where m and n are each independent integers greater than or equal to 1, preferably 1-10, more preferably 1-6, and most preferably 1-4;

[0042] The olefin feed comprises at least a portion of a first-cycle olefin stream and / or at least a portion of a second-cycle olefin stream, as well as isomerized olefins and optional externally sourced olefins.

[0043] This application also provides an apparatus for preparing low-carbon olefins, comprising:

[0044] A catalytic conversion reactor is used to bring feedstock oil into contact with a catalytic conversion catalyst to carry out a catalytic conversion reaction, thereby obtaining catalytic conversion reaction products;

[0045] A separation unit, connected to a catalytic conversion reactor, is used to separate the catalytic conversion products from the reactor, yielding ethylene and propylene, and a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream;

[0046] An etherification unit is connected to a separation unit, allowing olefin materials to enter the etherification unit and contact with alcohol feedstock under etherification conditions to obtain recycled ether materials and etherified olefins.

[0047] An isomerization unit is connected to the etherification unit, such that at least a portion of the post-etherified olefin enters the isomerization unit to undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin, and the isomerized olefin is also recycled back to the etherification unit for another etherification reaction.

[0048] The etherification unit is also connected to the catalytic conversion reactor, and is used to recycle the recycled ether material and optional post-etherified olefins back to the catalytic conversion reactor for catalytic conversion reaction.

[0049] The following describes the methods and apparatus for preparing low-carbon olefins. It should be noted that the descriptions of the methods also apply to the apparatus; and vice versa.

[0050] In this application, low-carbon olefins refer to ethylene and propylene. The method and apparatus of this application can produce ethylene and propylene with relatively few other byproducts such as methane and propane.

[0051] This application provides a method for preparing low-carbon olefins, comprising: contacting feedstock oil with a catalytic conversion catalyst in a catalytic conversion reactor to carry out a catalytic conversion reaction, thereby obtaining catalytic conversion reaction products.

[0052] In this application, the feedstock includes ether feedstocks, recycled ether feedstocks described later, and optionally a portion of post-ether olefins.

[0053] In this application, the ether raw material has C n H 2n+1 -OC m H 2m+1The structural formula is given, where m and n are each independently an integer greater than or equal to 1, preferably 1-10, more preferably 1-6, and most preferably 1-4. In one embodiment, the ether raw material is selected from one or more of methyl tert-butyl ether, methyl tert-amyl ether, methyl tert-hexyl ether, methyl tert-heptyl ether, methyl sec-butyl ether, methyl sec-amyl ether, methyl sec-hexyl ether, methyl sec-heptyl ether, ethyl tert-butyl ether, ethyl tert-amyl ether, ethyl tert-hexyl ether, ethyl tert-heptyl ether, ethyl sec-butyl ether, ethyl sec-amyl ether, ethyl sec-hexyl ether, ethyl sec-heptyl ether, dimethyl ether, methyl ethyl ether, and diethyl ether. Preferably, the ether raw material comes from an etherification unit, which is selected from a methyl tert-butyl ether unit, a light gasoline etherification unit, an ethyl tert-butyl ether unit, and combinations thereof.

[0054] 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.

[0055] 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. In one embodiment, the methane ratio in the catalytic conversion reaction products is not greater than about 5.0%, preferably not greater than about 2.0%, and most preferably not greater than 1.0%; the mass ratio of ethylene to methane is not less than 4.0, preferably not less than about 8.0, and most preferably not less than 12. The mass fraction ratio of propylene to propane in the liquefied petroleum gas is not less than about 10, preferably not less than about 15, and most preferably not less than about 30.

[0056] In one embodiment, the reaction temperature of the catalytic conversion reaction is about 460-750°C, preferably about 500-700°C, more preferably about 520-700°C, and most preferably about 550-680°C. The inventors of this application have discovered that the reaction temperature of the catalytic conversion reaction significantly affects the compositional distribution of the products. When the temperature is below 200°C, ethers are converted into alcohols and olefins, with a low selectivity for low-carbon olefins (total 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 (total ethylene and propylene) in the products 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.

[0057] In one embodiment, the reaction time of the catalytic conversion reaction is about 0.01-15 seconds, preferably about 0.05-10 seconds, more preferably about 0.1-8.0 seconds, and most preferably about 0.15-7.0 seconds; the agent-to-oil weight ratio is about 1-50, preferably about 5-40, and more preferably about 6-30.

[0058] 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 (including the total weight of ether feedstock, recycled ether materials, and post-ether olefins described later) entering the reactor.

[0059] The catalytic conversion catalyst used in this application can be selected from amorphous silica-alumina catalysts and / or zeolite catalysts. The zeolite in the zeolite catalyst is selected from Y-type series molecular sieve catalysts, β-type zeolite molecular sieves, ZSM-type series molecular sieve catalysts, and SAPO-type series molecular sieves. ZSM-type catalysts include, but are not limited to, ZSM-5 and ZSM-11 catalysts, and SAPO-type series molecular sieve catalysts include, but are not limited to, SAPO-34 and SAPO-18 molecular sieve catalysts. According to this application, the ZSM-type series molecular sieves are preferably selected from ZSM-5 and ZSM-11 molecular sieves, and the silica-alumina molar ratio (SiO2 / Al2O3) of the molecular sieve is 50-1000, preferably 80-800, and most preferably 100-800. According to this application, the catalytic conversion catalyst used in this application can be a high-silica zeolite containing phosphorus and transition metals, whose anhydrous chemical expression, based on the mass of the 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 the metal element.

[0060] According to this application, the catalytic conversion reactor is selected from any one and / or a combination of two or more reactor types, including fixed-bed, moving-bed, and fluidized-bed reactors. Preferably, the fixed-bed reactor consists of two or more reactors connected in series or parallel.

[0061] Optionally, the fluidized bed reactor may be selected from one or more reactors in series or in parallel, including constant diameter riser, constant linear velocity riser, variable diameter riser, fluidized bed and composite reactor composed of constant diameter riser and fluidized bed, upward conveyor line, and downward conveyor line.

[0062] According to this application, 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.

[0063] The method of this application includes separating catalytic conversion reaction products to obtain the target products ethylene and propylene. This separation operation can be carried out in a separation unit. This separation unit can be a separation device common in the art, such as a fractionating column, which can separate the components into different components according to their distillation range. For example, the catalytic conversion reaction products can be separated into a dry gas component, a liquefied petroleum gas component, and a gasoline component in a fractionating column, and then the ethylene component can be separated from the dry gas component in another separation unit, and the propylene component can be separated from the liquefied petroleum gas component in another separation unit, thereby obtaining the target products ethylene and propylene components. It should be noted that the separation of the catalytic conversion reaction products also yields a first recycled olefin stream containing butene and / or containing C5... + The second-cycle olefin stream. Other olefin components (mainly butene) can be separated from the liquefied petroleum gas (LPG) component, and can be combined with gasoline components to enter the etherification unit for etherification reaction.

[0064] The method of this application includes: feeding an olefin feedstock into an etherification unit, and contacting it with an alcohol feedstock under etherification conditions to obtain recycled ether materials and post-etherified olefins;

[0065] The olefin feed comprises at least a portion of the first cycle olefin stream and / or at least a portion of the second cycle olefin stream, as well as isomerized olefins and optional externally sourced olefins as described later.

[0066] In the etherification unit, 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. A portion of the first-cycle olefin stream and a portion of the second-cycle olefin stream can be introduced into the etherification unit; however, it is preferable to introduce all of the first-cycle and second-cycle olefin streams into the etherification unit, thereby maximizing the production of propylene and ethylene.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] Those skilled in the art can select appropriate catalysts and etherification conditions according to specific circumstances. In one embodiment, the etherification conditions may include: a reaction temperature of about 20-120°C, preferably about 30-80°C, more preferably about 35-75°C; and a reaction pressure of 0-5.0 MPa, preferably 0.2-2.0 MPa, more preferably 0.5-1.5 MPa.

[0071] In one embodiment, the alcohol raw material is a fatty alcohol, which may be selected from one or more of methanol, ethanol, propanol, butanol, and pentanol; preferably, the alcohol raw material is selected from methanol, ethanol, or a combination thereof.

[0072] 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.

[0073] This etherification reaction and etherification unit can convert high-carbon olefins (such as butene and C5+ olefins) generated from ether feedstocks through catalytic conversion, as well as isomerized olefins and external olefins described later, into corresponding ether compounds. These ether compounds can be fed as part of the feedstock 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.

[0074] 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 lower-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 used as part of the olefin feedstock delivered to the etherification unit, further converting these isomerized olefins into corresponding ether compounds.

[0075] In one embodiment, the isomerization reaction conditions include: a reaction temperature of about 150-500°C, preferably about 250-480°C, more preferably about 300-450°C, and most preferably about 350-450°C; and a weight hourly space velocity of about 1-30 h⁻¹. -1 Preferably about 2-20 hours -1 More preferably about 5-15 hours -1 .

[0076] In one embodiment, the isomerization catalyst comprises a support and a modified oxide, wherein the support comprises a zeolite molecular sieve and a binder, the support comprising 50-99% by mass of the molecular sieve and 1-50% by mass of the binder, the molecular sieve being a molecular sieve having an MFI structure, a FER structure, a TON structure, and an AEL structure, and the binder being alumina; the modified oxide is a polyol, and the mass ratio of the modified oxide to the support is 0.01-0.3:1; preferably, the polyol is a C2-C7 polyol, selected from one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol, and sorbitol.

[0077] Figure 1 This application illustrates an apparatus for preparing low-carbon olefins, comprising:

[0078] Catalytic conversion reactor 100 is used to bring feedstock oil into contact with catalytic conversion catalyst in the catalytic conversion reactor to carry out catalytic conversion reaction and obtain catalytic conversion reaction products;

[0079] Separation unit 200, connected to catalytic conversion reactor 100, is used to separate the catalytic conversion products from the reactor, yielding ethylene and propylene, and a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream;

[0080] Etherification unit 300, which is connected to separation unit 200, allows olefin material to enter the etherification unit and contact with alcohol raw material under etherification conditions to obtain recycled ether material and etherified olefin.

[0081] An isomerization unit 400 is connected to the etherification unit 300, such that at least a portion of the post-etherified olefin enters the isomerization unit to undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin, and the isomerized olefin is also recycled back to the etherification unit to undergo another etherification reaction.

[0082] The etherification unit 300 is also connected to the catalytic conversion reactor 100, and is used to recycle the recycled ether material and optional post-etherified olefins back to the catalytic conversion reactor for catalytic conversion reaction.

[0083] The ether feedstock is fed into the catalytic conversion reactor 100 via pipeline 101, where it reacts with the catalytic conversion catalyst under effective conditions to obtain products containing catalytic conversion reaction products. These products are then separated in the separation unit 200 to obtain the target products ethylene and propylene, as well as a first circulating olefin stream containing butene and / or containing C5... + The second cycle olefin stream of olefins; the first cycle olefin stream containing butene and / or containing C5 + The second-cycle olefins flow through line 102 and, together with optional externally sourced olefins through line 103, enter the etherification unit 300 for etherification reaction, yielding recycled ethers and post-etherified olefins. The recycled ethers are returned to the catalytic conversion reactor 100 via line 106. The post-etherified olefins are sent to the isomerization unit 400 via line 104, or returned to the catalytic conversion reactor 100 via line 105. The isomerized olefins are returned to the etherification unit 300 via line 108 for further etherification reaction, and the non-olefin components are sent downstream via line 107.

[0084] Of course, the device also includes a regenerator for regenerating the catalytic conversion catalyst. Figure 1(Not shown), used to enable the catalytic conversion catalyst to be recycled during the reaction. Further details will not be provided here.

[0085] The following is combined Figure 2 One specific embodiment of the method described herein is illustrated, but this does not limit the scope of the application. 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. An ether mixture (including ether feedstock and recycled ether material) is injected into the bottom of the first reaction zone 7 of the variable-diameter fluidized bed reactor 2 via pipeline 3 and atomized steam from pipeline 4 through a nozzle. It contacts the regenerated catalyst from the regeneration inclined tube 15 within the reactor and 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 and the deactivated catalyst enter the cyclone separator in the settling tank 7 to separate the catalyst from the oil and gas. The reacted oil and gas enter the large 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 stripped oil and gas from the spent catalyst enters the main oil and gas pipeline 16 after passing through a cyclone separator. The stripped spent catalyst then enters the regenerator 12 via the spent catalyst inclined tube 11. Main air enters the regenerator via pipeline 13 to burn off the coke on the spent catalyst, regenerating the deactivated catalyst. The flue gas is then exited via pipeline 14. The regenerated catalyst then enters the variable-diameter fluidized bed reactor 2 via the regeneration inclined tube 15 for recycling.

[0086] The reaction oil and gas pass through the main oil and gas pipeline 16 and enter the fractionation, absorption, and stabilization unit 17. The separated dry gas is led out through pipeline 18 and separated to obtain ethylene; liquefied gas is led out through pipeline 19 and separated into propylene through gas separation unit 23, which is then sent out through pipeline 24; other olefins are sent through pipeline 25 along with gasoline from pipeline 20 to the etherification unit 26; diesel and heavy oil may be present and are discharged through pipelines 21 and 22, respectively; simultaneously, alcohol feedstocks such as methanol from pipeline 28 are also sent to the etherification unit 26 for etherification reaction; the ethylene obtained from the etherification unit 26... The recycled ether material is returned to the riser reactor 2 via pipelines 31 and 33 to react and increase the production of low-carbon olefins. The unreacted non-olefin components are sent to the downstream unit via pipeline 29. The unreacted olefin components (post-ether olefins) are returned to the riser reactor 2 via pipelines 32 and 33 to increase the production of low-carbon olefins, or enter the isomerization unit 30 via pipeline 27 for isomerization treatment. The isomerized olefins are returned to the etherification unit 26 via pipeline 34 to further convert the post-ether olefins into recycled ether material after isomerization treatment, so as to increase the production of low-carbon olefins.

[0087] Example

[0088] 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 oils used in the embodiments and comparative examples are shown in Table 1. The catalysts used in the embodiments and comparative examples are commercially available catalytic conversion catalysts with the brand name TCC-1, manufactured by Sinopec Catalyst Qilu Branch; the isomerization catalysts used in the embodiments are commercially available catalysts with the brand name FI-15, manufactured by Sinopec Petrochemical Research Institute; the catalysts used in the etherification units in the embodiments are the same as those used in the CN101245255B embodiment, and the etherification units are also fixed-bed reactors as used in the CN101245255B embodiment.

[0089] Table 1. Properties of raw materials in examples and comparative examples.

[0090] Crude oil name Methyl tert-butyl ether Methyl tert-amyl ether Molecular formula <![CDATA[C5H 12 O]]> <![CDATA[C6H 14 O]]> <![CDATA[Density (20 °C), g / cm 3 > 0.7 0.77 molecular weight 78 102 Boiling point, °C 55 85

[0091] Comparative Example 1

[0092] according to Figure 3 The process shown was tested, and its relationship with... Figure 2 Similarly, the difference lies in the absence of etherification unit 26 and isomerization unit 30. Other olefins are discharged directly via pipeline 25, gasoline via pipeline 20, and diesel and heavy oil, which may be present, are discharged via pipelines 21 and 22, respectively. The feedstock is methyl tert-butyl ether, and TCC-1 is used as the catalyst. The experiment was conducted 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) to obtain the target products of ethylene and propylene. The reaction conditions and product distribution are listed in Table 2.

[0093] Comparative Example 2

[0094] according to Figure 3 The process shown was tested using methyl tert-butyl ether as the feedstock and TCC-1 as the catalyst 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 target products, ethylene and propylene, were obtained. The reaction conditions and product distribution are listed in Table 2. The difference from Comparative Example 1 is that the catalytic conversion reaction temperature was 450℃.

[0095] Example 1

[0096] according to Figure 2The process illustrated was tested using methyl tert-butyl ether as the feedstock and TCC-1 as the catalyst 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). Other olefin components (mainly isobutylene) and gasoline components underwent etherification in the etherification unit and were then returned to the variable-diameter fluidized bed reactor catalytic cracking unit. The etherified olefins underwent isomerization in the isomerization unit and were then returned to the etherification unit for re-etherification. The target products, ethylene and propylene, were obtained. The reaction conditions and product distribution are listed in Table 2.

[0097] Table 2 Reaction conditions for the examples and comparative examples

[0098]

[0099]

[0100] Comparative Example 3

[0101] according to Figure 3 The process shown was tested using methyl tert-amyl ether as feedstock and TCC-1 as catalyst 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 target products of ethylene and propylene were obtained. The reaction conditions and product distribution are listed in Table 3.

[0102] Comparative Example 4

[0103] according to Figure 3 The process shown was tested using methyl tert-amyl ether as the feedstock and TCC-1 as the catalyst 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 target products, ethylene and propylene, were obtained. The reaction conditions and product distribution are listed in Table 3. The difference from Comparative Example 3 is that the catalytic conversion reaction temperature was 450℃.

[0104] Example 2

[0105] according to Figure 2 The process illustrated was tested using methyl tert-amyl ether as the feedstock and TCC-1 as the catalyst 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). Other olefin components (mainly isobutylene) and gasoline components underwent etherification in the etherification unit and were then returned to the variable-diameter fluidized bed reactor catalytic cracking unit. The etherified olefins underwent isomerization in the isomerization unit and were then returned to the etherification unit for re-etherification. The target products, ethylene and propylene, were obtained. The reaction conditions and product distribution are listed in Table 3.

[0106] Table 3 Reaction conditions for the examples and comparative examples

[0107]

[0108]

[0109] 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 preparing low-carbon olefins, comprising: S1 allows the feedstock oil to come into contact with the catalytic conversion catalyst in the catalytic conversion reactor to carry out a catalytic conversion reaction, thereby obtaining the catalytic conversion reaction product; S2 separates the catalytic conversion reaction products to yield ethylene and propylene, as well as a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream; S3 allows olefin feedstock to enter the etherification unit, where it comes into contact with alcohol feedstock under etherification conditions to obtain recycled ether feedstock and post-etherified olefins. S4 causes at least a portion of the post-etherified olefin to enter the isomerization unit and undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin. The feedstock oil includes ether feedstocks, recycled ether materials, and optionally a portion of post-etherified olefins; wherein the ether feedstocks have C n H 2n+1 -OC m H 2m+1 The structure is as follows, where m and n are each independent integers greater than or equal to 1, preferably 1-10, more preferably 1-6, and most preferably 1-4; The olefin feed comprises at least a portion of a first-cycle olefin stream and / or at least a portion of a second-cycle olefin stream, as well as isomerized olefins and optional externally sourced olefins.

2. The method according to claim 1, wherein, The ether raw material is selected from one or more of methyl tert-butyl ether, methyl tert-amyl ether, methyl tert-hexyl ether, methyl tert-heptyl ether, methyl sec-butyl ether, methyl sec-amyl ether, methyl sec-hexyl ether, methyl sec-heptyl ether, ethyl tert-butyl ether, ethyl tert-amyl ether, ethyl tert-hexyl ether, ethyl tert-heptyl ether, ethyl sec-butyl ether, ethyl sec-amyl ether, ethyl sec-hexyl ether, ethyl sec-heptyl ether, dimethyl ether, methyl ethyl ether, and diethyl ether; preferably, the ether raw material comes from an etherification unit, which is selected from a methyl tert-butyl ether unit, a light gasoline etherification unit, an ethyl tert-butyl ether unit, and combinations thereof.

3. The method according to claim 1, wherein, The reaction temperature of the catalytic conversion reaction is about 460-750°C, preferably about 500-700°C, more preferably about 520-700°C, and most preferably about 550-680°C.

4. The method according to claim 1, wherein, The reaction time of the catalytic conversion reaction is about 0.01-15 seconds, preferably about 0.05-10 seconds, more preferably about 0.1-8.0 seconds, and most preferably about 0.15-7.0 seconds; the agent-to-oil weight ratio is about 1-50, preferably about 5-40, and more preferably about 6-30.

5. The method according to claim 1, wherein, The alcohol raw material is selected from one or more of methanol, ethanol, propanol, butanol, and pentanol; preferably, the alcohol raw material is selected from methanol, ethanol, or a combination thereof.

6. The method according to claim 1, wherein, The etherification conditions include: a reaction temperature of about 20-120°C, preferably about 30-80°C, more preferably about 35-75°C; and a reaction pressure of 0-5.0 MPa, preferably 0.2-2.0 MPa, more preferably 0.5-1.5 MPa.

7. The method according to claim 1, wherein, The isomerization reaction conditions include: a reaction temperature of about 150-500°C, preferably about 250-480°C, more preferably about 300-450°C, and most preferably about 350-450°C; and a weight hourly space velocity of about 1-30 h⁻¹. -1 Preferably about 2-20 hours -1 More preferably about 5-15 hours -1 .

8. The method according to claim 1, wherein, The isomerization catalyst comprises a support and a modified oxide, wherein the support comprises a zeolite molecular sieve and a binder, the support comprising 50-99% by mass of molecular sieve and 1-50% by mass of binder, the molecular sieve being a molecular sieve having MFI, FER, TON, and AEL structures, and the binder being alumina; the modified oxide is a polyol, and the mass ratio of the modified oxide to the support is 0.01-0.3:1; preferably, the polyol is a C2-C7 polyol, selected from one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol, and sorbitol.

9. The method according to claim 1, wherein, The catalytic conversion catalyst is selected from amorphous silica-alumina catalysts and / or zeolite catalysts, wherein the zeolite in the zeolite catalyst is selected from Y-type series molecular sieve catalysts, β-type zeolite molecular sieves, ZSM-type series molecular sieve catalysts, and SAPO-type series molecular sieves.

10. The method according to claim 9, wherein, The catalytic conversion catalyst is selected from ZSM series molecular sieves, preferably ZSM-5, ZSM-11 molecular sieves and hierarchical porous molecular sieves, wherein the silicon-aluminum molar ratio of the molecular sieve SiO2 / AlO3 is 50-1000, preferably 80-800, and most preferably 100-800.

11. The method according to claim 9, wherein, The catalytic conversion catalyst is a high-silica zeolite containing phosphorus and transition metals, and its anhydrous chemical formula, based on the mass of the 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.

12. An apparatus for preparing low-carbon olefins, comprising: A catalytic conversion reactor is used to bring feedstock oil into contact with a catalytic conversion catalyst to carry out a catalytic conversion reaction, thereby obtaining catalytic conversion reaction products; A separation unit, connected to a catalytic conversion reactor, is used to separate the catalytic conversion products from the reactor, yielding ethylene and propylene, and a first recycled olefin stream containing butene and / or containing C5. + The second-cycle olefin stream; An etherification unit is connected to a separation unit, allowing olefin materials to enter the etherification unit and contact with alcohol feedstock under etherification conditions to obtain recycled ether materials and etherified olefins. An isomerization unit is connected to the etherification unit, such that at least a portion of the post-etherified olefin enters the isomerization unit to undergo an isomerization reaction in the presence of an isomerization catalyst to obtain an isomerized olefin, and the isomerized olefin is also recycled back to the etherification unit for another etherification reaction. The etherification unit is also connected to the catalytic conversion reactor, and is used to recycle the recycled ether material and optional post-etherified olefins back to the catalytic conversion reactor for catalytic conversion reaction.

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