Method for producing ethylene and propylene through catalytic conversion of olefin

Abstract

The invention relates to a method for producing ethylene and propylene by catalytic conversion of olefin, which comprises the following steps: introducing a raw material containing C4 and above olefin into a first reactor to contact with a first catalyst for a first catalytic conversion reaction to obtain a first oil agent mixture; introducing the superimposed oil into a second reactor to be in contact with a second catalyst for a second catalytic conversion reaction to obtain a second oil agent mixture; carrying out gas-solid separation on the first oil agent mixture and the second oil agent mixture, mixing the obtained first reaction oil gas and second reaction oil gas, and feeding the mixture into a separation device for separation to obtain ethylene, propylene and C4 fractions; and carrying out a superposition reaction on the C4 fraction, and introducing part or all of the obtained superposition product into the second reactor. The method disclosed by the invention is beneficial to improving the catalytic cracking performance of the raw material and further improving the yield of the low-carbon olefin.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of petrochemical industry, and particularly relates to a method for producing ethylene and propylene by catalytic conversion of olefins. BACKGROUND

[0002] Low-carbon olefins such as ethylene and propylene are basic raw materials in the petrochemical industry. The traditional technology uses a tubular furnace steam cracking to produce ethylene and propylene. However, this process has disadvantages such as high energy consumption, low propylene / ethylene yield ratio, and large carbon dioxide emissions, and is subject to constraints such as shortage of light feedstock and high carbon emissions.

[0003] Steam cracking and catalytic cracking processes produce a large amount of carbon four light hydrocarbon resources, but the comprehensive utilization efficiency is low. CN1915928A discloses a method for continuously producing propylene by switching with etherized carbon four from an ethylene plant as raw material. The method uses a group of multi-stage fixed bed reactors connected in parallel. By operating each fixed bed in a certain time interval, the composition of the reaction products entering the next process is ensured to be stable, and part of the catalyst bed is in a regenerated state. The propylene yield reaches 26.38%.

[0004] CN102952577A discloses a catalytic conversion method for improving propylene yield. High-quality catalytic cracking feedstock oil is contacted with hot regenerated catalyst in the first reaction zone of the reactor to generate oil gas and carbon-containing catalyst, which undergoes selective hydrogen transfer reaction and isomerization reaction in the second reaction zone. The separated C4 fraction and / or light gasoline fraction are injected into the reactor for further reaction. This method can increase the propylene yield by 1.3 percentage points and improve the product distribution.

[0005] CN114195612A discloses a method for producing propylene and ethylene by catalytic conversion of petroleum hydrocarbons. The reactor is divided into a lower riser reaction zone and an upper fast fluidized bed reaction zone. The reaction raw material undergoes macromolecular catalytic cracking reaction and small molecule catalytic cracking reaction in turn according to the molecular structure, which can realize the staged conversion of the reaction process to propylene and ethylene, thereby improving the yield of ethylene and propylene.

[0006] US2010022810A1 discloses a method for producing propylene by catalytic cracking of carbon four and above olefins. By using an adiabatic fixed bed reactor and silver-modified MFI molecular sieve as catalyst, the raffinate carbon four raw material is subjected to catalytic cracking at a temperature of 500-580°C and a hydrocarbon partial pressure of 0.05-0.3 MPa. The propylene yield can reach more than 26%.

[0007] Existing heavy oil catalytic cracking technology uses catalytic cracking C4 fraction as an auxiliary means to increase propylene production. However, under the conditions of catalyst and reactor designed for macromolecular heavy oil feedstock, the cracking performance of C4 fraction is insufficient, and the contribution to low-carbon olefin yield is low. SUMMARY

[0008] The present application aims to solve the problem of insufficient cracking performance of C4 and above olefins, and improve the yield of ethylene and propylene in catalytic conversion products.

[0009] To achieve the above-mentioned purpose, the present application provides a method for producing ethylene and propylene by catalytic conversion of olefins, which comprises: introducing a raw material containing C4 and above olefins into a first reactor to contact with a first catalyst for a first catalytic conversion reaction to obtain a first oil agent mixture; performing gas-solid separation on the first oil agent mixture to obtain a first spent catalyst and a first reaction oil gas; the first reactor is selected from at least one of a turbulent bed reactor, a fast fluidized bed reactor and a riser reactor; introducing a polymerization oil into a second reactor to contact with a second catalyst for a second catalytic conversion reaction to obtain a second oil agent mixture; performing gas-solid separation on the second oil agent mixture to obtain a second spent catalyst and a second reaction oil gas; the second reactor is a riser reactor; mixing the first reaction oil gas and the second reaction oil gas and then feeding into a separation device for separation to obtain ethylene, propylene and a C4 fraction; feeding the C4 fraction into a polymerization reactor to contact with a polymerization catalyst for polymerization reaction to obtain a polymerization product, and introducing part or all of the polymerization product into the second reactor for reaction.

[0010] Optionally, the first reactor is selected from at least one of a turbulent bed reactor and a fast fluidized bed reactor; the conditions of the first catalytic conversion reaction include: reaction temperature of 500-700 ℃, preferably 550-680 ℃; reaction pressure of 0.1-1 MPa, preferably 0.1-0.5 MPa; oil gas residence time of 1-20 seconds, preferably 3-15 seconds; catalyst / oil weight ratio of 4-60:1, preferably 8-50:1; water / oil weight ratio of 0.1-1:1, preferably 0.2-0.5:1; catalyst density of 50-400 kg / m 3 , preferably 150-300 kg / m 3 ; gas linear velocity of 0.6-3.0 m / s, preferably 0.8-2.0 m / s.

[0011] Optionally, the conditions of the second catalytic conversion reaction include: a reaction temperature of 520-680 ℃, preferably 540-650 ℃; a reaction pressure of 0.1-1 MPa, preferably 0.1-0.4 MPa; an oil gas residence time of 0.5-5 seconds, preferably 1-5 seconds; a catalyst to oil weight ratio of 4-60:1, preferably 8-40:1; a water to oil weight ratio of 0.1-1:1, preferably 0.2-0.5:1; a catalyst density of 20-120 kg / m 3 , preferably 30-100 kg / m 3 ; a gas linear velocity of 3-20 m / s, preferably 4-18 m / s; preferably, the outlet of the second reactor is in communication with the inlet of a gas-solid separation device.

[0012] Optionally, the first catalyst and the second catalyst each independently include 10-80 wt% of MFI molecular sieve, 5-99 wt% of inorganic oxide, and 0-70 wt% of clay, based on the weight of the first catalyst or the second catalyst; the micro-activity of the first catalyst and the second catalyst each independently is 40-75%; preferably, the MFI molecular sieve is ZSM-5 molecular sieve and / or ZRP molecular sieve; optionally, the inorganic oxide is selected from one or more of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and amorphous silicon aluminum; the clay is selected from at least one of kaolin, metakaolin, montmorillonite, diatomite, sepiolite, attapulgite, rectites, hydrotalcite, and bentonite; preferably, one or more of kaolin, metakaolin, diatomite, and attapulgite.

[0013] Optionally, the conditions of the condensation reaction include: a reaction temperature of 100-300 ℃, preferably 120-260 ℃; a reaction pressure of 1-8 MPa, preferably 1-5 MPa; a liquid volume space velocity of 0.5-10 h -1 , preferably 1-8 h -1 ; preferably, the condensation reactor is selected from one of a fixed bed reactor, a stirred tank reactor, and a column reactor.

[0014] Optionally, the polymerization catalyst is selected from one or more of a solid phosphoric acid catalyst, an ion exchange resin catalyst and a zeolite molecular sieve catalyst, preferably a zeolite molecular sieve catalyst; preferably, the zeolite molecular sieve catalyst comprises 15-70 wt% of a binder, 10-65 wt% of a matrix and 20-75 wt% of a zeolite molecular sieve, based on the total weight of the zeolite molecular sieve catalyst; the binder is one or more of a silica sol, an alumina sol and a pseudoboehmite; the matrix is selected from one or more of a kaolin, a montmorillonite and a bentonite; the zeolite molecular sieve is an MTT structure molecular sieve and / or an MFI structure molecular sieve, preferably an MFI structure molecular sieve; the MFI structure molecular sieve is selected from a ZSM-5 molecular sieve and / or a ZRP molecular sieve; preferably, the zeolite molecular sieve is an element-modified mesoporous molecular sieve; the modifying element is selected from one or more of phosphorus, boron, iron, cobalt and nickel.

[0015] Optionally, the method for preparing the zeolite molecular sieve catalyst comprises the following steps: mixing the zeolite molecular sieve with an alkaline solution for alkaline treatment to obtain a first treated zeolite molecular sieve; subjecting the first treated zeolite molecular sieve to ion exchange treatment, mixing the ion exchange product with an acidic solution for acid treatment, and washing to obtain a second treated zeolite molecular sieve; immersing the second treated zeolite molecular sieve in a phosphorus-containing solution, drying and calcining the immersed solid to obtain a phosphorus-modified zeolite molecular sieve; uniformly mixing a colloid formed by aging of a binder and a matrix with the phosphorus-modified zeolite molecular sieve to form a catalyst slurry, and shaping and drying the catalyst slurry.

[0016] Optionally, the content of olefins in the carbon four and above olefin-containing raw material is 20 wt% or more, preferably 30 wt% or more; the content of dienes in the carbon four and above olefin-containing raw material is 1 wt% or less, preferably 0.5 wt% or less; preferably, the carbon four and above olefin-containing raw material is from at least one of a refinery catalytic cracking / cracking unit, an ethylene steam cracking unit, an etherization unit, an MTO unit and an MTP unit; the carbon four and above olefin-containing raw material is selected from one or more of C4-C 12 Optionally, the polymerization catalyst is selected from one or more of a solid phosphoric acid catalyst, an ion exchange resin catalyst and a zeolite molecular sieve catalyst, preferably a zeolite molecular sieve catalyst; preferably, the zeolite molecular sieve catalyst comprises 15-70 wt% of a binder, 10-65 wt% of a matrix and 20-75 wt% of a zeolite molecular sieve, based on the total weight of the zeolite molecular sieve catalyst; the binder is one or more of a silica sol, an alumina sol and a pseudoboehmite; the matrix is selected from one or more of a kaolin, a montmorillonite and a bentonite; the zeolite molecular sieve is an MTT structure molecular sieve and / or an MFI structure molecular sieve, preferably an MFI structure molecular sieve; the MFI structure molecular sieve is selected from a ZSM-5 molecular sieve and / or a ZRP molecular sieve; preferably, the zeolite molecular sieve is an element-modified mesoporous molecular sieve; the modifying element is selected from one or more of phosphorus, boron, iron, cobalt and nickel.

[0017] Optionally, the content of olefins in the carbon four and above olefin-containing raw material is 20 wt% or more, preferably 30 wt% or more; the content of dienes in the carbon four and above olefin-containing raw material is 1 wt% or less, preferably 0.5 wt% or less; preferably, the carbon four and above olefin-containing raw material is from at least one of a refinery catalytic cracking / cracking unit, an ethylene steam cracking unit, an etherization unit, an MTO unit and an MTP unit; the carbon four and above olefin-containing raw material is selected from one or more of C4-C 8+ Optionally, the polymerization catalyst is selected from one or more of a solid phosphoric acid catalyst, an ion exchange resin catalyst and a zeolite molecular sieve catalyst, preferably a zeolite molecular sieve catalyst; preferably, the zeolite molecular sieve catalyst comprises 15-70 wt% of a binder, 10-65 wt% of a matrix and 20-75 wt% of a zeolite molecular sieve, based on the total weight of the zeolite molecular sieve catalyst; the binder is one or more of a silica sol, an alumina sol and a pseudoboehmite; the matrix is selected from one or more of a kaolin, a montmorillonite and a bentonite; the zeolite molecular sieve is an MTT structure molecular sieve and / or an MFI structure molecular sieve, preferably an MFI structure molecular sieve; the MFI structure molecular sieve is selected from a ZSM-5 molecular sieve and / or a ZRP molecular sieve; preferably, the zeolite molecular sieve is an element-modified mesoporous molecular sieve; the modifying element is selected from one or more of phosphorus, boron, iron, cobalt and nickel.

[0018] Optionally, the method further includes: performing coke regeneration on the first and second spent catalysts; the coke regeneration conditions include: a regeneration temperature of 600-750 ℃, preferably 650-700 ℃; a gas apparent linear velocity of 0.2-3 m / s, preferably 0.5-2 m / s; and an average residence time of the spent catalyst of 0.5-3 min, preferably 0.8-2 min.

[0019] Through the above technical solution, the present invention, based on the differences in components between feedstocks containing C4 and above olefins and blended oils, adopts matched reactors for feedstocks containing C4 and above olefins and blended oils respectively, which is beneficial to improving the catalytic cracking performance of feedstocks and further increasing the yield of low-carbon olefins.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart illustrating a method for the catalytic conversion of olefins to produce ethylene and propylene according to some embodiments of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Rapid fluidized bed reactor; 2. Riser reactor; 3. Settler; 4. Regenerator; 5. Separator; 6. Composite reactor; 7. Pipeline; 8. Pipeline; 9. Pipeline; 10. Cyclone separator; 11. Pipeline; 12. Stripping section; 13. Regenerating inclined tube; 14. Pipeline; 15. Cyclone separator; 16. Regenerating inclined tube; 17. Oil and gas pipeline; 18. Pipeline; 19. Pipeline. Detailed Implementation

[0023] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] This invention provides a method for the catalytic conversion of olefins to produce ethylene and propylene, the method comprising: A feedstock containing C4 or higher olefins is introduced into a first reactor and contacted with a first catalyst to carry out a first catalytic conversion reaction, yielding a first oil-agent mixture; the first oil-agent mixture is subjected to gas-solid separation to obtain a first undeveloped catalyst and a first reaction oil-gas; the first reactor is selected from at least one of a turbulent bed reactor, a fast fluidized bed reactor, and a riser reactor; The composite oil is introduced into the second reactor and comes into contact with the second catalyst to carry out the second catalytic conversion reaction, resulting in a second oil-catalyst mixture; the second oil-catalyst mixture is subjected to gas-solid separation to obtain the second undeveloped catalyst and the second reaction oil-gas; the second reactor is a riser reactor; The first and second reaction oil gases are mixed and then sent to a separation device for separation to obtain ethylene, propylene and C4 fractions. The C4 fraction is fed into a superposition reactor and contacted with a superposition catalyst to carry out a superposition reaction, thereby obtaining a superposition product. Part or all of the superposition product is then introduced into a second reactor for further reaction.

[0025] Based on the differences in composition between feedstocks containing C4 and above olefins and blended oils, this invention improves the catalytic cracking performance of feedstocks and further increases the yield of low-carbon olefins by using matched reactors for feedstocks containing C4 and above olefins and blended oils respectively.

[0026] In some embodiments of the present invention, the feedstock containing C4 or higher olefins comes from at least one of a refinery catalytic cracking / pyrolysis unit, an ethylene steam cracking unit, a chemical plant etherification unit, an MTO unit, and an MTP unit.

[0027] In some specific embodiments of the present invention, the olefins in the raw materials containing C4 or higher olefins can be selected from C4-C6 olefins. 12 One or more of the olefins, preferably one or more selected from C4-C6 olefins.

[0028] In some embodiments of the present invention, the olefin content in the raw material containing C4 or higher olefins can be 20% by weight or more, preferably 30% by weight or more.

[0029] In some embodiments of the present invention, the content of C4 olefins in the feedstock containing C4 or higher olefins is 40-90% by weight. The content of C4 fraction in the feedstock containing C4 or higher olefins varies depending on the source of the feedstock; for example, the content of olefins in the C4 fraction from catalytic cracking is about 40% by weight, and the content of olefins in the C4 fraction from a chemical plant etherification unit is about 50% by weight.

[0030] In some embodiments of the present invention, reducing the diene content in the feedstock containing C4 or higher olefins can reduce catalyst coking. The diene content in the feedstock containing C4 or higher olefins is less than 1% by weight, preferably less than 0.5% by weight. When the feedstock containing C4 or higher olefins comes from an ethylene plant steam cracking unit, the C4 or higher olefin fraction produced by the ethylene plant steam cracking unit can be hydrogenated to reduce the diene content to less than 1% by weight, preferably less than 0.5% by weight.

[0031] In some embodiments of the present invention, the first reactor is preferably a turbulent bed reactor or a fast fluidized bed reactor, and more preferably a fast fluidized bed reactor. By adjusting the gas linear velocity in the fast fluidized bed reactor, the catalyst in the fast fluidized bed reactor is made to have a fully concentrated phase distribution, reducing the generation of dry gas, coke, etc., and increasing the yield of low-carbon olefins. In addition, the distribution of the catalyst can be adjusted by setting a gas distributor at the feed of the fast fluidized bed reactor, so that the feedstock after atomization by atomized steam enters the reactor, so that the feedstock with uniform concentration comes into contact with the catalytic conversion of higher catalyst concentration for catalytic cracking reaction.

[0032] In this invention, a fast fluidized bed refers to a reactor in which the catalyst is in a fast fluidized state. Fast fluidization is a bubble-free gas-solid contact fluidization, and its important feature is that solid particles tend to move in clusters.

[0033] In some preferred embodiments of the present invention, the feedstock containing C4 or higher olefins is introduced into the lower part of the rapid fluidized bed reactor; the fluidized bed reactor includes, from bottom to top, a pre-lifting section and at least one reaction zone.

[0034] In some embodiments of the present invention, the raw material containing C4 or higher olefins is preheated to 200-450°C, preferably 300-420°C, before being introduced into the rapid fluidized bed reactor.

[0035] In some embodiments of the present invention, a pre-lifting medium is injected into the bottom of the rapid fluidized bed reactor. The pre-lifting medium may be selected from one or more of water vapor, dry gas or nitrogen. The weight ratio of the pre-lifting medium to the hydrocarbon feedstock is 0.01-2, preferably 0.05-1.

[0036] The inventors discovered in their research that small-molecule C4 olefins have low catalytic cracking performance, and that the catalytic performance of C4 olefins can be improved by increasing the reaction time of C4 olefins and the density of the catalyst.

[0037] In some embodiments of the present invention, the conditions for the first catalytic conversion reaction may include: a reaction temperature (at the outlet) of 500-700 °C; a reaction pressure of 0.1-1 MPa; an oil-gas residence time of 1-20 seconds; a catalyst-to-oil weight ratio of 4-60:1; a water-to-oil weight ratio of 0.1-1:1; and a catalyst density of 50-400 kg / m³. 3 The gas linear velocity is 0.6-3.0 m / s.

[0038] In some embodiments of the present invention, the conditions for the first catalytic conversion reaction may include: a reaction temperature (at the outlet) of 550-680 °C; a reaction pressure of 0.1-0.5 MPa; an oil-gas residence time of 3-15 seconds; a catalyst-to-oil weight ratio of 8-50:1; a water-to-oil weight ratio of 0.2-0.5:1; and a catalyst density of 150-300 kg / m³. 3 The gas linear velocity is 0.8-2.0 m / s.

[0039] In some embodiments of the present invention, in order to reduce catalyst coking during the catalytic cracking reaction of the composite oil, the content of olefins with more than 2 substituents in the composite oil is less than 30% by weight, preferably less than 25% by weight.

[0040] In some preferred embodiments of the present invention, C in the composite product 8+ The olefin content is above 60% by weight.

[0041] The inventor discovered C 8+ The catalytic cracking of olefins has a fast reaction rate and a short reaction time, which can be controlled by adjusting the C2O2 concentration. 8+ Conditions in the catalytic cracking reaction of olefins can improve the catalytic cracking performance of composite oils, resulting in high reactivity of composite oils in producing ethylene and propylene.

[0042] In some embodiments of the present invention, the conditions for the second catalytic conversion reaction may include: a reaction temperature (at the outlet) of 520-680 °C; a reaction pressure of 0.1-1 MPa; an oil-gas residence time of 0.5-5 seconds; a catalyst-to-oil weight ratio of 4-60:1; a water-to-oil weight ratio of 0.1-1:1; and a catalyst density of 20-120 kg / m³. 3 The gas linear velocity is 3-20 m / s.

[0043] In some preferred embodiments of the present invention, the conditions for the second catalytic conversion reaction may include: a reaction temperature (at the outlet) of 540-650 °C; a reaction pressure of 0.1-0.4 MPa; an oil-gas residence time of 1-5 seconds; a catalyst-to-oil weight ratio of 8-40:1; a water-to-oil weight ratio of 0.2-0.5:1; and a catalyst density of 30-100 kg / m³. 3 The gas linear velocity is 4-18 m / s.

[0044] In some embodiments of the present invention, the second reactor is a constant-diameter riser reactor or a variable-diameter riser reactor. The riser reactor includes multiple feed points, allowing partial and / or complete introduction of the composite oil into the riser reactor at one feed point; alternatively, the composite oil can be introduced into the reactor at at least two different feed points in the same or different proportions. Further, the composite oil is introduced into the lower part of the riser reactor.

[0045] In some embodiments of the present invention, in order to improve the catalytic conversion efficiency of the composite oil, the composite oil is preheated to 200-400°C, preferably 250-360°C, before being introduced into the second reactor.

[0046] In some preferred embodiments of the present invention, the outlet of the second reactor is connected to the inlet of the gas-solid separation device. The oil-catalyst mixture at the outlet of the second reactor is directly introduced into the reactor for gas-solid separation to separate the catalyst to be generated and the reaction oil-gas, further reducing the residence time of the raw materials and catalyst at the outlet of the second reactor, further reducing the proportion of secondary reactions, thereby improving the selectivity of ethylene and propylene.

[0047] In some embodiments of the present invention, the first catalyst and the second catalyst are catalytic cracking catalysts, and the first catalyst and the second catalyst may be the same or different. On a dry basis and based on the weight of the first catalyst or the second catalyst, the first catalyst and the second catalyst each independently comprise 10-80 wt% MFI molecular sieve, 5-99 wt% inorganic oxides, and 0-70 wt% clay.

[0048] In some embodiments of the present invention, the microreactor activity of the first catalyst and the second catalyst is independently 40-75%. The catalyst microreactor activity is tested on a standard cracking catalyst microreactor activity tester according to the RIPP92-90 standard.

[0049] In some embodiments of the present invention, the MFI molecular sieve is a ZSM-5 molecular sieve and / or a ZRP molecular sieve; the MFI molecular sieve is a high-silica molecular sieve with a pentasil structure, such as a ZSM-5 molecular sieve and / or a ZRP molecular sieve. The above-mentioned mesoporous molecular sieves can also be modified with non-metallic elements such as phosphorus and / or transition metal elements such as iron, cobalt, and nickel; for a more detailed description of ZRP, see US5232675; for a more detailed description of ZSM-5, see US3702886.

[0050] In some embodiments of the present invention, the inorganic oxide may be boehmite and / or aluminum sol; the inorganic oxide is selected from one or more of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide and amorphous aluminum silicate.

[0051] In some embodiments of the present invention, the clay may be any material known to those skilled in the art, and may be various natural and / or synthetic clays commonly used as cracking catalyst supports, with or without various chemical and / or physical treatments. The clay is selected from at least one of kaolin, metakaolin, montmorillonite, diatomite, sepiolite, attapulgite, attapulgite, hydrotalcite, and bentonite; preferably one or more of kaolin, metakaolin, diatomite, and attapulgite.

[0052] In this invention, the regeneration process of the spent catalyst can be implemented according to conventional catalyst regeneration methods in the art, for example: introducing oxygen-containing gas (such as air) from the bottom of the regenerator, the spent catalyst is regenerated by contacting oxygen and burning, and the generated flue gas is separated into gas and solid by the cyclone separator of the regenerator and enters the subsequent energy recovery system.

[0053] In some embodiments of the present invention, the method for regenerating the first and / or second catalyst may include: a regeneration temperature of 600-750 °C, preferably 650-700 °C; a gas apparent linear velocity of 0.2-3 m / s, preferably 0.5-2 m / s; and an average residence time of 0.5-3 min, preferably 0.8-2 min.

[0054] In some embodiments of the present invention, the gas-solid separation can be carried out in a cyclone separator or other gas-solid separation equipment. Methods for separating ethylene, propylene, and C4 fractions from the reaction products can employ conventional techniques in the art, and the present invention does not limit this, nor will it be described in detail here.

[0055] In some embodiments of the present invention, the superimposed reactor may be selected from a fixed-bed reactor, a stirred tank reactor, and a tower reactor. The superimposed reactor may be operated batch or continuously, preferably in a continuous operation mode.

[0056] In some embodiments of the present invention, the conditions for the superposition reaction may include: a reaction temperature of 100-300 °C; a reaction pressure of 1-8 MPa; and a liquid hourly space velocity of 0.5-10 h⁻¹. -1 .

[0057] In some preferred embodiments of the present invention, the conditions for the superposition reaction may include: a reaction temperature of 120-260°C; a reaction pressure of 1-5 MPa; and a liquid hourly space velocity of 1-8 h⁻¹. -1 .

[0058] In the above embodiments, the superposition reactor mainly converts C4 olefins into C8 and higher carbon number olefins, wherein the conversion rate of C4 olefins is higher than 90%, and the remaining C4 fraction is mainly composed of alkanes, thereby achieving the separation of alkanes and olefins in the mixed C4 fraction. The content of olefins with more than 2 substituents in the superposition product is less than 30% by weight, preferably less than 25% by weight.

[0059] In the above embodiments, the molecular structure of the composite product is optimized, and the yield of propylene is further improved when the composite product is subjected to further catalytic cracking reaction. The olefins with more than two substituents include one or more of trimethyl-substituted olefins, dimethyl-1-ethyl-substituted olefins, monomethyl-2-ethyl-substituted olefins, and polyalkyl-substituted olefins.

[0060] In some embodiments of the present invention, the composite catalyst is selected from one or more of solid phosphoric acid catalysts, ion exchange resin catalysts and zeolite molecular sieve catalysts, preferably zeolite molecular sieve catalysts.

[0061] In some embodiments of the present invention, based on the total weight of the zeolite molecular sieve catalyst, the zeolite molecular sieve catalyst comprises 15-70% by weight of binder, 10-65% by weight of matrix, and 20-75% by weight of zeolite molecular sieve; the binder is selected from one or more of silica sol, alumina sol, and pseudoboehmite; the matrix is ​​selected from one or more of kaolin, montmorillonite, and bentonite; the zeolite molecular sieve is an MTT structure molecular sieve and / or an MFI structure molecular sieve, preferably an MFI structure molecular sieve; the MFI structure molecular sieve is selected from ZSM-5 molecular sieve and / or ZRP molecular sieve.

[0062] In some preferred embodiments of the present invention, the zeolite molecular sieve can be a mesoporous zeolite modified with non-metallic elements and / or transition metal elements, for example, the non-metallic elements are selected from phosphorus and / or boron, and the transition metal elements are selected from one or more of iron, cobalt, and nickel. The macroporous zeolite is defined conventionally in the art as a mesoporous zeolite with an average pore size of 0.5-6.0 nm.

[0063] In some embodiments of the present invention, the preparation method of the zeolite molecular sieve catalyst includes the following steps: The zeolite molecular sieve is mixed with an alkaline solution and subjected to alkaline treatment to obtain the first-treated zeolite molecular sieve. The first-treated zeolite molecular sieve is subjected to ion exchange treatment, and the ion exchange product is mixed with an acidic solution for acid treatment and washing to obtain the second-treated zeolite molecular sieve. The second-treated zeolite molecular sieve is impregnated with a phosphorus-containing solution, and the impregnated solid is dried and calcined to obtain a phosphorus-modified zeolite molecular sieve. The colloid formed by aging the binder and matrix is ​​mixed evenly with the phosphorus-modified zeolite molecular sieve to form a catalyst slurry, which is then shaped and dried.

[0064] In some embodiments of the present invention, the alkaline solution may be an alkali metal hydroxide solution; the temperature of the alkali treatment may be 50-90 °C, and the time may be 20-70 minutes.

[0065] In some embodiments of the present invention, the acidic reagent in the acidic solution may be selected from one or more of oxalic acid, hydrochloric acid, and fluorosilicic acid.

[0066] In some embodiments of the present invention, the method for forming the catalyst includes spray drying to obtain microsphere catalysts.

[0067] In some embodiments of the present invention, the method further includes: calcining the microsphere catalyst, washing it with ammonium sulfate, and then washing it with water, filtering it, and drying it.

[0068] Figure 1 A flowchart illustrating a preferred embodiment of the present invention is shown below. Figure 1 The flowchart shown illustrates the method for the catalytic conversion of olefins to produce ethylene and propylene according to the present invention.

[0069] like Figure 1 As shown, the pre-lifting medium is introduced into the bottom of the fast fluidized bed reactor 1 (first reactor) via pipeline 7. The first catalyst in a fluidized state from pipeline 16 is accelerated upward along the fast fluidized bed reactor 1 under the action of the pre-lifting medium. The preheated feedstock containing C4 and above olefins is injected into the fast fluidized bed reactor 1 via pipeline 8 together with the atomizing medium from pipeline 9. It comes into contact with the first catalyst and undergoes the first catalytic conversion reaction. The first oil-agent mixture obtained from the reaction is introduced into the cyclone separator 10 of the settling tank 3 for gas-solid separation.

[0070] The preheated composite oil is introduced into the lower part of the riser reactor 2 (second reactor) via pipeline 19, where it comes into contact with the fluidized second catalyst from pipeline 11 to undergo a second catalytic conversion reaction. The resulting second oil-catalyst mixture is then directly introduced into the cyclone separator 10 for gas-solid separation, thereby separating the catalyst to be generated from the reaction products.

[0071] The separated spent catalyst flows to the stripping section 12, and after steam stripping, it enters the regenerator 4 via the spent catalyst inclined tube 13. Main air from pipeline 14 enters the regenerator 4, burning off the coke on the spent catalyst in the dense phase bed. The flue gas then enters the subsequent energy recovery system after passing through the cyclone separator 15. The regenerated catalyst is divided into at least two streams, which are returned to the fast fluidized bed reactor 1 via the regeneration inclined tube 16 and to the riser reactor 2 via pipeline 11, respectively. The separated reaction products enter the separation unit 5 via the oil and gas pipeline 17 for separation, yielding ethylene, propylene, and C4 fractions. The C4 fraction obtained from the reaction products is introduced into the superposition reactor 6 via pipeline 18, where it undergoes a catalytic superposition reaction under the action of the superposition catalyst. The resulting superposition oil is introduced into the riser reactor 2 via pipeline 19.

[0072] The present invention will be further described in detail below through examples, but the invention is not limited thereto. All raw materials used in the examples are commercially available. Unless otherwise specified, all reagents used below are chemically pure reagents.

[0073] In this embodiment of the invention, the first reactor is a rapid fluidized bed reactor, and the second reactor is a riser reactor.

[0074] The raw material A used in the embodiments and comparative examples of this invention is a C4 fraction from a petrochemical plant, wherein the content of butene is 71.7% by weight and the content of diene is 0.4% by weight.

[0075] The first and second catalysts used in the embodiments of the present invention are ZSM-5 molecular sieve catalysts, which were purchased from Qilu Branch of China Petrochemical Catalyst Co., Ltd. Before use, they were treated with water vapor at 820℃ for 17 h, and their properties are shown in Table 1. The micro-reaction activity of the catalysts was tested on a standard cracking catalyst micro-reaction activity tester according to the RIPP92-90 standard.

[0076]

[0077] Preparation Example The method for preparing the composite catalyst in the embodiments of the present invention includes the following steps: (1) Preparation of phosphorus-modified ZSM-5 molecular sieve S1. Add ZSM-5 molecular sieve (dry basis) to NaOH solution, heat the resulting mixture to 65℃, react for 30 minutes, rapidly cool the reaction product to room temperature, filter, and wash the filtered solid product until the filtrate is neutral to obtain alkali-treated ZSM-5 molecular sieve; wherein, the concentration of NaOH solution is 2.4% by weight, and the mass ratio of ZSM-5 molecular sieve (dry basis) to NaOH solution is 1:10; S2. The alkali-treated ZSM-5 molecular sieve obtained in step S1 is mixed with water and pulped. NH4Cl is added to the pulp for ammonium exchange treatment. The ammonium exchange product is filtered, and the resulting solid product is washed to obtain ammonium-exchanged ZSM-5 molecular sieve. The mass ratio of water added during pulping to ZSM-5 molecular sieve (dry basis) in step S1 is 8; the mass ratio of NH4Cl to ZSM-5 molecular sieve (dry basis) is 1.0; the ammonium exchange treatment conditions include: temperature of 75℃ and time of 1 hour. S3. Prepare a molecular sieve slurry with a solid content of 10% by weight by adding water to ammonium-exchanged ZSM-5 molecular sieve (dry basis). Add oxalic acid to the slurry under stirring, then add hydrochloric acid (10% by weight) and fluorosilicic acid (3% by weight) concurrently over a period of 30 minutes. Heat the slurry after adding the acid to 65°C and stir at this temperature for 1 hour. Filter the reaction product and wash the resulting solid with water until the filtrate is neutral. Add water to the obtained filter cake and slurry to obtain a molecular sieve slurry with a solid content of 40% by weight. Add H3PO4 solution (85% by mass) to the obtained molecular sieve slurry, mix thoroughly, impregnate, and dry at 550°C. The phosphorus-modified ZSM-5 molecular sieve was obtained by calcination at ℃ for 2 hours; the mass ratio of ammonium-exchanged ZSM-5 molecular sieve (dry basis) to oxalic acid, hydrochloric acid, fluorosilicic acid and H3PO4 solution was 100:10:70:56:12.6.

[0078] (2) Preparation of composite catalysts Aluminum sol, kaolin, and decationized water were mixed to prepare a slurry with a solid content of 40% by weight. Hydrochloric acid was added to the slurry to adjust the pH to 3. The pH of the slurry was kept constant and allowed to stand and age at 40 °C for 1 hour. Aluminum sol was then added and stirred for 1 hour to form a colloid. Phosphorus-modified ZSM-5 molecular sieve was added to the colloid to form a catalyst slurry (solid content of 35% by weight), wherein the weight ratio of phosphorus-modified ZSM-5 molecular sieve:kaolin:aluminum sol was 50:34:16. The catalyst slurry was spray-dried to prepare microsphere catalysts. The microsphere catalysts were then calcined at 500 °C for 1 hour. The calcined microsphere catalysts were then washed with ammonium sulfate solution at 60 °C until the Na2O content was less than 0.25% by weight. The ammonium-exchanged catalysts were rinsed with deionized water, filtered, and the filtered solids were dried at 110 °C to obtain composite catalyst B. The ammonium sulfate solution includes ammonium sulfate and water, and the weight ratio of the microsphere catalyst to ammonium sulfate and water is 1:0.5:10.

[0079] Example 1 according to Figure 1As shown in the process, the first catalyst, which is 680 °C from the regenerator, enters the first reactor (fast fluidized bed reactor) under the action of the pre-lifting medium. The raw material A, which is preheated to 360 °C, is injected into the fast fluidized bed reactor together with the atomizing medium and comes into contact with the first catalyst to carry out the first catalytic conversion reaction, thereby obtaining the first oil-agent mixture. The first oil-agent mixture is introduced into the cyclone separator of the settling tank for gas-solid separation.

[0080] The preheated oil to 300 °C is introduced into the lower part of the second reactor (riser reactor) and comes into contact with the second catalyst from the regenerator at a temperature of 680 °C to carry out the second catalytic conversion reaction. The resulting second oil-catalyst mixture is introduced into the cyclone separator of the settling tank for gas-solid separation to obtain the catalyst to be generated and the reaction oil and gas.

[0081] The spent catalyst is fed into a regenerator for coke burn-off regeneration; the reaction oil and gas are sent to a separation unit for further separation to obtain ethylene, propylene, and C4 fractions. The C4 fraction obtained from the reaction products is introduced into a superposition reactor, where a superposition reaction is carried out under the action of superposition catalyst B to obtain the superposition product; all of the superposition product is returned to the second reactor as feedstock for superposition oil reaction. The superposition reaction conditions include: reaction temperature of 150℃, reaction pressure of 3.0 MPa, and liquid hourly space velocity of 3 h⁻¹. -1 The C8 olefin content in the composite product is approximately 65.3% by weight, and the content of olefins with more than 2 substituents is 17.7% by weight.

[0082] The reaction conditions and results of the first and second catalytic conversion reactions are shown in Table 2. The distillation range of the liquid products is 40-330 °C.

[0083] Comparative Example 1 The method for catalytic conversion of olefins to produce ethylene and propylene in this comparative example is basically similar to that in Example 1, except that the first reactor is a riser reactor. The second reactor does not introduce composite oil feedstock; instead, the C4 fraction separated from the reaction gas in the first reactor is introduced into the second reactor for reaction. The reaction results are shown in Table 2.

[0084] Example 2 The method for catalytic conversion of olefins to produce ethylene and propylene in this embodiment is basically similar to that in Example 1, except that the superposition reaction temperature is 250 °C, the reaction pressure is 5.0 MPa, and the liquid hourly space velocity is 6 h⁻¹. -1 The C8 olefin content in the obtained composite product is approximately 73.2% by weight, of which the content of olefins with more than 2 substituents is 36.0% by weight.

[0085] The reaction results are shown in Table 2.

[0086] Table 2

[0087] As can be seen from the data in the table above, the method of the present invention can improve the catalytic cracking performance of C4 olefins and composite oils, significantly increase the yield of ethylene and propylene, and reduce the generation of non-ethylene dry gas.

[0088] Example 3 The method for catalytic conversion of olefins to produce ethylene and propylene in this embodiment is basically similar to that in Example 1, except that the reaction conditions in the first reactor are different. The reaction results are shown in Table 3.

[0089] Example 4 The method for catalytic conversion of olefins to produce ethylene and propylene in this embodiment is basically similar to that in Example 1, except that the reaction conditions in the second reactor are different. The reaction results are shown in Table 3.

[0090] Examples 5-6 The methods for catalytic conversion of olefins to produce ethylene and propylene in Examples 5-6 are basically similar to those in Example 1, except that the reaction conditions in the first and second reactors are different. The reaction results are shown in Table 3.

[0091] Table 3

[0092] The data above shows that the method of the present invention is beneficial to improving the catalytic cracking performance of feedstocks and composite oils containing C4 and above olefins, and increases the yield of low-carbon olefins.

[0093] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0094] 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. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0095] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for the catalytic conversion of olefins to produce ethylene and propylene, characterized in that, The method includes: A feedstock containing C4 or higher olefins is introduced into a first reactor and contacted with a first catalyst to carry out a first catalytic conversion reaction, yielding a first oil-agent mixture; the first oil-agent mixture is subjected to gas-solid separation to obtain a first undeveloped catalyst and a first reaction oil-gas; the first reactor is selected from at least one of a turbulent bed reactor, a fast fluidized bed reactor, and a riser reactor; The composite oil is introduced into the second reactor and comes into contact with the second catalyst to carry out the second catalytic conversion reaction, resulting in a second oil-catalyst mixture; the second oil-catalyst mixture is subjected to gas-solid separation to obtain the second undeveloped catalyst and the second reaction oil-gas; the second reactor is a riser reactor; The first and second reaction oil gases are mixed and then sent to a separation device for separation to obtain ethylene, propylene and C4 fractions. The C4 fraction is fed into a superposition reactor and contacted with a superposition catalyst to carry out a superposition reaction, thereby obtaining a superposition product. Part or all of the superposition product is then introduced into a second reactor for further reaction.

2. The method according to claim 1, wherein, The first reactor is selected from at least one of a turbulent bed reactor and a fast fluidized bed reactor; the conditions for the first catalytic conversion reaction include: a reaction temperature of 500-700 ℃, preferably 550-680 ℃; a reaction pressure of 0.1-1 MPa, preferably 0.1-0.5 MPa; an oil-gas residence time of 1-20 seconds, preferably 3-15 seconds; a catalyst-to-oil weight ratio of 4-60:1, preferably 8-50:1; a water-to-oil weight ratio of 0.1-1:1, preferably 0.2-0.5:1; and a catalyst density of 50-400 kg / m³. 3 Preferably 150-300 kg / m 3 The gas linear velocity is 0.6-3.0 m / s, preferably 0.8-2.0 m / s.

3. The method according to claim 1, wherein, The conditions for the second catalytic conversion reaction include: a reaction temperature of 520-680 ℃, preferably 540-650 ℃; a reaction pressure of 0.1-1 MPa, preferably 0.1-0.4 MPa; an oil-gas residence time of 0.5-5 seconds, preferably 1-5 seconds; a catalyst-to-oil weight ratio of 4-60:1, preferably 8-40:1; a water-to-oil weight ratio of 0.1-1:1, preferably 0.2-0.5:1; and a catalyst density of 20-120 kg / m³. 3 Preferably 30-100 kg / m 3 The gas linear velocity is 3-20 m / s, preferably 4-18 m / s; Preferably, the outlet of the second reactor is connected to the inlet of the gas-solid separation device.

4. The method according to claim 1, wherein, Based on the weight of the first catalyst or the second catalyst, the first catalyst and the second catalyst each independently comprise 10-80% by weight of MFI molecular sieve, 5-99% by weight of inorganic oxide and 0-70% by weight of clay. The microreactor activities of the first catalyst and the second catalyst are each independently 40-75%; Preferably, the MFI molecular sieve is a ZSM-5 molecular sieve and / or a ZRP molecular sieve; Optionally, the inorganic oxide is selected from one or more of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, and amorphous aluminum silicate; the clay is selected from at least one of kaolin, metakaolin, montmorillonite, diatomite, sepiolite, attapulgite, attapulgite, hydrotalcite, and bentonite; preferably, one or more of kaolin, metakaolin, diatomite, and attapulgite.

5. The method according to claim 1, wherein, The conditions for the superposition reaction include: a reaction temperature of 100-300℃, preferably 120-260℃; a reaction pressure of 1-8 MPa, preferably 1-5 MPa; and a liquid hourly space velocity of 0.5-10 h⁻¹. -1 Preferably 1-8 h -1 ; Preferably, the superimposed reactor is selected from one of a fixed-bed reactor, a stirred tank reactor, and a tower reactor.

6. The method according to claim 1, wherein, The composite catalyst is selected from one or more of solid phosphoric acid catalysts, ion exchange resin catalysts and zeolite molecular sieve catalysts, preferably zeolite molecular sieve catalysts. Preferably, based on the total weight of the zeolite molecular sieve catalyst, the zeolite molecular sieve catalyst comprises 15-70% by weight of binder, 10-65% by weight of matrix, and 20-75% by weight of zeolite molecular sieve; the binder is selected from one or more of silica sol, alumina sol, and boehmite; the matrix is ​​selected from one or more of kaolin, montmorillonite, and bentonite; the zeolite molecular sieve is an MTT structure molecular sieve and / or an MFI structure molecular sieve, preferably an MFI structure molecular sieve; the MFI structure molecular sieve is selected from ZSM-5 molecular sieve and / or ZRP molecular sieve. Preferably, the zeolite molecular sieve is an element-modified mesoporous molecular sieve; the modifying element is selected from one or more of phosphorus, boron, iron, cobalt and nickel.

7. The method according to claim 6, wherein, The preparation method of the zeolite molecular sieve catalyst includes the following steps: The zeolite molecular sieve is mixed with an alkaline solution and subjected to alkaline treatment to obtain the first-treated zeolite molecular sieve. The first-treated zeolite molecular sieve is subjected to ion exchange treatment, and the ion exchange product is mixed with an acidic solution for acid treatment and washing to obtain the second-treated zeolite molecular sieve. The second-treated zeolite molecular sieve is impregnated with a phosphorus-containing solution, and the impregnated solid is dried and calcined to obtain a phosphorus-modified zeolite molecular sieve. The colloid formed by aging the binder and matrix is ​​mixed evenly with the phosphorus-modified zeolite molecular sieve to form a catalyst slurry, which is then shaped and dried.

8. The method according to claim 1, wherein, The olefin content in the raw material containing C4 or higher olefins is 20% by weight or more, preferably 30% by weight or more. The content of diene in the raw material containing C4 or higher olefins is less than 1% by weight, preferably less than 0.5% by weight; Preferably, the feedstock containing C4 or higher olefins comes from at least one of a refinery catalytic cracking / pyrolysis unit, ethylene steam cracking unit, etherification unit, MTO unit, and MTP unit; The raw materials containing C4 and above olefins are selected from C4-C4 olefins. 12 One or more of the olefins, preferably one or more selected from C4-C6 olefins.

9. The method according to claim 1, wherein, The content of olefins with more than 2 substituents in the composite oil is less than 30% by weight, preferably less than 25% by weight; C in the composite product 8+ The olefin content is above 60% by weight.

10. The method according to claim 1, wherein, The method further includes: regenerating the first spent catalyst and the second spent catalyst by coking; The conditions for coke regeneration include: a regeneration temperature of 600-750 ℃, preferably 650-700 ℃; a gas apparent linear velocity of 0.2-3 m / s, preferably 0.5-2 m / s; and an average residence time of the catalyst to be regenerated of 0.5-3 min, preferably 0.8-2 min.

Images