Process and equipment for directly preparing propylene from ethylene

Abstract

The invention discloses a process and equipment for directly preparing propylene from ethylene, and belongs to the technical field of chemistry and chemical engineering. The invention provides a process for directly preparing propylene from ethylene. The process comprises the following steps: (1) pre-activating a catalyst; (2) catalytic reaction; (3) gas-solid separation and catalyst regeneration; feeding the separated spent catalyst into a regenerator, regenerating the catalyst at 500-750 DEG C in a regenerated gas atmosphere, and controlling the carbon deposition amount of the regenerated catalyst to be 1.5-12wt%; and (4) circulation: returning the regenerated catalyst to the riser reactor through a regeneration inclined tube, and circulating the steps (2)-(4). The process for directly preparing propylene from ethylene can effectively regulate and control the heat release problem in the process, accurately regulate and control the carbon deposition amount of the catalyst, avoid inactivation caused by excessive carbon deposition of the catalyst, and improve the yield of propylene. And the regeneration of the catalyst and the catalytic reaction for preparing propylene from ethylene can be synchronously carried out, so that continuous work is realized without frequent shutdown.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering technology, and more specifically, relates to a process and equipment for the direct production of propylene from ethylene. Background Technology

[0002] Propylene is an important basic organic chemical raw material, widely used in the synthesis of acrylonitrile, propylene oxide, isopropanol, acetone, polypropylene resin, butanol, and various fine chemicals. In recent years, with the vigorous promotion of technologies such as methanol-to-olefins (MTO) and bioethanol-to-ethylene in my country, ethylene production has increased year by year. However, the growth in propylene supply has consistently lagged behind the growth rate of market demand. Therefore, developing new propylene sourcing technologies and improving propylene supply capacity are of great significance for optimizing the olefin product structure and enhancing the economic benefits of petrochemical and coal chemical industries.

[0003] Currently, the technology for producing propylene via the disproportionation reaction of ethylene and butene is relatively mature, but research on one-step technology for the direct conversion of ethylene to propylene is limited. Compared to the ethylene / butene disproportionation process, which requires a specific source of butene and complex separation processes, the direct ethylene-to-propylene process has advantages such as a single source of raw materials and a simple process. Therefore, the ethylene→propylene conversion route has become an important focus of industry attention.

[0004] The reaction mechanism of ethylene to propylene (ETP) is based on an oligomerization-cracking mechanism catalyzed by strong Brønsted acids. Strong Brønsted acid sites on molecular sieve catalysts (such as H-ZSM-5 and H-SSZ-13) interact with ethylene molecules. Ethylene is first protonated to form a carbocation, followed by a chain propagation reaction to generate C3-C8 alkane intermediates. Finally, β-cracking produces the target product propylene and olefins such as butene. Related patents (such as ZL201810224320.3 and ZL201410104214.3) have reported process conditions for evaluating the direct ethylene to propylene production using a fixed-bed reactor: in ZL201810224320.3, the reaction temperature is 450-500℃, atmospheric pressure, and the ethylene weight hourly space velocity (WHSV) is 0.5-5 h⁻¹. -1 The reaction conditions in ZL201410104214.3 are 300~450℃, atmospheric pressure, and WHSV of 1.0~10.0 h. - ¹. Among them, the optimal performance of H-SSZ-13 molecular sieve in fixed bed after acid treatment is: ethylene conversion rate of 84.7%, propylene selectivity of 62.2%, and catalyst lifetime of more than 10 hours.

[0005] Although the fixed-bed process described above establishes the basic reaction conditions, this reactor type exposes the following key problems in the direct production of propylene from ethylene: First, the ethylene oligomerization reaction is a strongly exothermic reaction. In a fixed-bed reactor, the heat dissipation effect is poor, which leads to the aggravation of secondary reactions of the product propylene (dehydrogenation, isomerization, and deep cracking), reducing the yield of the target product.

[0006] Secondly, carbon deposits are generated during the catalyst reaction, and the exothermic reaction exacerbates carbon buildup and deactivation. After deactivation, the catalyst requires carbon burning for regeneration. Traditional regeneration typically takes place at 700°C in air for 4-6 hours. During this high-temperature carbon burning process, aluminum in the molecular sieve framework is prone to dealumination, resulting in the permanent loss of active sites and a gradual decline in catalyst performance. Most critically, fixed-bed reaction and regeneration must be carried out separately, requiring a complete shutdown of the unit. This involves complex operations such as heating, carbon burning, and cooling, making continuous and stable operation impossible and severely hindering industrial applications.

[0007] Finally, in existing fixed-bed reactors, the inflexible control of catalyst coking makes it impossible to improve selectivity through process optimization, resulting in a monotonous decrease in propylene selectivity with reaction time. The final industrial product yield is usually only 40-50%, far below the theoretical potential.

[0008] In summary, existing fixed-bed processes for the direct production of propylene from ethylene face limitations such as difficulty in temperature control, easy catalyst deactivation, and difficulty in ensuring continuous operation. There is an urgent need to develop new processes and equipment for the direct production of propylene from ethylene. Summary of the Invention

[0009] 1. The problem to be solved To address at least one of the problems in existing technologies, such as difficulty in controlling core reaction conditions, insufficient catalyst stability, and lack of continuous operation capability, this invention provides a process and equipment for the direct production of propylene from ethylene.

[0010] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a process for the direct preparation of propylene from ethylene, comprising the following steps: (1) Catalyst pre-activation: The catalyst is pre-activated at 250~450℃ under N2 atmosphere for 1~5h; (2) Catalytic reaction: The pre-activated catalyst is placed in the riser reactor, and riser gas, ethylene and dilution gas are introduced to bring the ethylene into contact with the catalyst and carry out the catalytic reaction in the reaction section of the riser reactor; (3) Gas-solid separation and catalyst regeneration: The reaction products in step (2) enter the settling tank, and stripping gas is introduced into the settling tank to perform gas-solid separation to obtain a mixed gas and a catalyst to be generated; then, the mixed gas enters the gas separation system for separation to obtain product gas and recycled ethylene; The catalyst awaiting regeneration enters the regenerator and is regenerated at 500-750°C in a regeneration gas atmosphere, with the carbon deposition on the regenerated catalyst controlled to be 1.5-12 wt%. (4) Circulation: The regenerated catalyst is returned to the riser reactor through the regeneration inclined tube, and steps (2) to (4) are repeated.

[0011] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (2), the boosting gas enters the pre-boosting section of the booster reactor through the boosting gas inlet, and the catalyst reaches the reaction section in the booster reactor under the action of the boosting gas and comes into contact with ethylene. The mass ratio of catalyst to ethylene is (5~40):1.

[0012] Further preferred, in step (2), the mass ratio of the catalyst to ethylene is (8~30):1.

[0013] In a further preferred embodiment, in step (2), the mass ratio of the catalyst to ethylene is (10~20):1.

[0014] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (2), the catalytic reaction satisfies one or more of the following conditions (I) to (IV): (I) The reaction temperature is 280~450℃; (II) The reaction pressure is 0~0.3MPa; (III) The gas phase linear velocity in the reaction section is 2~10 m / s; at this time, the gas phase in the reaction section includes the ethylene, dilution gas and boosting gas; (IV) The reaction time is 0.1~3s.

[0015] Further preferred, in step (2), the reaction temperature is 280~420℃.

[0016] In a further preferred embodiment, in step (2), the reaction temperature is 300~350℃.

[0017] It should be noted that if the reaction temperature for the direct production of propylene from ethylene exceeds 450℃, the secondary reaction of the propylene product (hydrogenation) will be intensified, reducing the yield of the target product and exacerbating catalyst carbonization and accelerating the catalyst deactivation process.

[0018] Further preferably, in step (2), the reaction pressure is 0~0.2MPa.

[0019] Further preferred, in step (2), the gas phase linear velocity of the reaction section is 2~8m / s.

[0020] Further optimization is made in step (2), where the reaction time is 0.5~2s.

[0021] It should be noted that by adjusting the gas phase linear velocity in the reaction section, the length of the riser reactor, and the diameter of the pre-rise section and the reaction section, the final catalytic reaction time can be controlled between 0.1 and 3 seconds. This ensures that the reaction is fully realized without over-reacting and producing excessive carbon deposits and side reactions.

[0022] As a preferred embodiment of any technical solution in the first aspect of the present invention, in step (2), V 乙烯 The volume of ethylene in the catalytic reaction is represented by V. 提升气+稀释气 If V represents the sum of the volumes of the lift gas and the dilution gas in the catalytic reaction, then the following condition must be met: 提升气+稀释气 :V 乙烯 =(10~0.5):1.

[0023] Further preferably, the V 提升气+稀释气 V 乙烯 =(8~1):1.

[0024] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (2), the dilution gas includes one or more of water vapor, nitrogen, and argon; More preferably, the diluent gas is water vapor.

[0025] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (2), the lifting gas includes one or more of water vapor, nitrogen, and argon.

[0026] Further preferably, the lifting gas is water vapor.

[0027] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (3), the stripping gas includes one or more of water vapor and nitrogen, and the flow rate of the stripping gas is 100~200g / h.

[0028] It should be noted that the stripping gas can help with gas-solid separation and desorb a small amount of gas adsorbed in the catalyst, reducing the amount of reaction products entering the regenerator with the catalyst and preventing the product gas from being burned in the regenerator.

[0029] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (3), the regenerated gas is an oxygen-containing mixed gas, and the volume fraction of oxygen in the regenerated gas is 1~25%.

[0030] Further preferred, in step (3), the volume fraction of oxygen in the oxygen-containing gas is 3-19%.

[0031] As a preferred embodiment of any technical solution of the first aspect of the present invention, the regenerated gas includes one or more of air and oxygen-enriched air, and one or more of carbon dioxide, water vapor, and nitrogen.

[0032] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (3), the catalyst regeneration temperature is 550~700℃.

[0033] As a preferred embodiment of any technical solution of the first aspect of the present invention, in step (3), the amount of carbon deposited on the regenerated catalyst is controlled to be 2~10wt%.

[0034] Further preferred, in step (3), the amount of carbon deposits on the regenerated catalyst is controlled to be 4~10wt%.

[0035] It should be noted that the catalyst carbon deposition refers to the mass of carbon deposited per unit mass of catalyst, which can be tested using thermogravimetric analysis (TG). Catalyst carbon deposition significantly affects the conversion rate of ethylene and the yield of propylene. Too much or too little catalyst carbon deposition will impair the direct production of propylene from ethylene. Excessive carbon deposition will clog the mesoporous / microporous channels of the catalyst, preventing ethylene from reaching the internal active sites and causing only surface sites to participate in the reaction, resulting in a significant decrease in ethylene conversion. Insufficient catalyst carbon deposition may lead to excessively high Brønsted acid strength and density, producing more alkane products instead of propylene, thus reducing the propylene yield.

[0036] As a preferred embodiment of any technical solution in the first aspect of the present invention, the catalyst is a microsphere molecular sieve catalyst, and in step (1), the average particle size of the catalyst is 80~90μm and the bulk density is 0.6~0.75 g / cm³. 3 .

[0037] As a preferred embodiment of any technical solution of the first aspect of the present invention, the catalyst includes one or more of SSZ-13, ZSM-5, SAPO-34, SSZ-39, and SAPO-18.

[0038] More preferably, the catalyst includes one or more of SSZ-13 and ZSM-5.

[0039] A second aspect of the present invention provides a fluidized bed apparatus for the direct production of propylene from ethylene, comprising a riser reactor, a settling tank and a regenerator connected in sequence, wherein the regenerator is connected to the riser reactor to form a connected circulation loop of riser reactor, settling tank and regenerator. The riser reactor includes a pre-rise section and a reaction section; the reaction section is located above the pre-rise section and is connected to the pre-rise section, with a sample inlet at the connection point; a feed inlet is located at the end of the pre-rise section away from the sample inlet, and a discharge outlet is located at the end of the reaction section away from the sample inlet; a riser gas inlet is located at the bottom of the pre-rise section; and the reaction section is connected to a settler. The settling device is equipped with a cyclone separator at the top and a stripping pipe at the bottom, with a stripping gas inlet on the stripping pipe; the stripping pipe is connected to the regenerator through a waiting inclined pipe. The regenerator is equipped with a cyclone separator and a flue gas outlet at the top, and a regeneration gas inlet at the bottom; the regenerator is connected to the feed inlet of the riser reactor through a regeneration inclined tube. As a preferred embodiment of any technical solution in the second aspect of the present invention, the length ratio of the pre-lifting section to the reaction section is 1:(1~9); the pipe diameter ratio of the pre-lifting section to the reaction section is (2~10):1.

[0040] It should be noted that the diameter reduction treatment from the pre-lifting section to the reaction section of the riser reactor can suddenly increase the gas flow velocity in the reaction section. On the one hand, this can shorten the contact time between ethylene and the catalyst, preventing the formation of excessive carbon deposits that accelerate catalyst deactivation. On the other hand, the large gas flow velocity in the reaction section after the diameter reduction treatment allows the catalyst to enter the settling tank more effectively. This is because a uniform gas flow velocity in the riser reactor may lead to catalyst accumulation in the reaction section, which is not conducive to the circulation of the catalyst throughout the fluidized bed.

[0041] As a preferred embodiment of any technical solution in the second aspect of the present invention, the fluidized bed equipment for direct propylene production from ethylene further includes: a gas separation system and a preheating furnace. The gas separation system is connected to the gas outlet of the cyclone separator in the settling tank via a pipeline and is used to separate product gas and recycled ethylene. The preheating furnace is located at the front end of the inlet. Ethylene and dilution gas are preheated by the preheating furnace and then enter the reaction section of the riser reactor through the inlet.

[0042] The process for directly producing propylene from ethylene as described in any of the first aspects of this invention can be carried out using the fluidized bed equipment for directly producing propylene from ethylene as described in any of the second aspects of this invention.

[0043] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The process for direct propylene preparation from ethylene provided by the present invention adopts a fluidized bed circulation process design, which enables the heat of reaction to dissipate in a timely and uniform manner. The dilution gas and booster gas provide a portion of the ethylene partial pressure, which can effectively control the exothermic problem in the reaction and avoid local overheating and reaction runaway. Compared with the traditional fixed bed process, it can solve the problem of temperature control difficulties caused by rapid exothermic reaction, thereby avoiding the phenomenon of reduced propylene yield due to increased side reactions.

[0044] (2) The process for direct propylene production from ethylene provided by the present invention regenerates the catalyst under a regeneration gas atmosphere. By controlling the volume fraction of oxygen in the regeneration gas and the regeneration temperature, the amount of carbon deposited on the catalyst can be precisely controlled, which can achieve high ethylene conversion rate and propylene yield, and can also effectively delay the catalyst deactivation process. At the same time, the process for direct propylene production from ethylene provided by the present invention separates and recovers unreacted ethylene (recycled ethylene) through a gas separation system and uses it as raw material ethylene gas to participate in the reaction again, which can improve the utilization rate of ethylene and further improve the conversion rate of ethylene and the yield of propylene.

[0045] (3) The fluidized bed equipment for direct propylene production from ethylene provided by the present invention adopts a circulating fluidized bed design, with the regenerator and riser reactor set up independently. The catalyst circulates continuously between the regenerator and the riser reactor, so that the reaction for direct propylene production from ethylene and catalyst regeneration can be carried out simultaneously. The device achieves true long-term continuous operation. Compared with the fixed bed which requires frequent shutdowns, the fluidized bed equipment for direct propylene production from ethylene provided by the present invention has improved utilization and significantly reduced operating costs and process complexity.

[0046] (4) The fluidized bed equipment for direct propylene production from ethylene provided by the present invention has a reduced diameter treatment from the pre-lifting section to the reaction section, which increases the gas flow rate of the inlet and the reaction section, reduces the contact time between the catalyst and ethylene, and allows the ethylene to be quickly separated from the catalyst after the reaction, avoiding excessive reaction and the generation of excessive carbon deposits that lead to catalyst deactivation, and ensuring smooth circulation of the catalyst in the entire fluidized bed equipment. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the fluidized bed equipment for the direct production of propylene from ethylene according to the present invention.

[0048] The accompanying figure labels are explained as follows: 1. Sample inlet; 2. Riser reactor; 3. Settler; 4. Stripping tube; 5. Regenerated inclined tube; 6. Stripping gas inlet; 7. Regenerator; 8. Regenerated gas inlet; 9. Regenerated inclined tube; 10. Needle valve; 11. Riser gas inlet; 12. Cyclone separator; 13. Flue gas outlet; 14. Gas separation system; 15. Product gas; 16. Preheater; 17. Ethylene; 18. Dilution gas; 19. Circulating ethylene; 20. Reaction section; 21. Pre-lifting section. Detailed Implementation

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0050] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0051] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0052] The present invention will be further described below with reference to specific embodiments.

[0053] 1. Structural Description of Fluidized Bed Equipment for Direct Ethylene-to-Propylene Production like Figure 1 As shown, the fluidized bed equipment for the direct production of propylene from ethylene includes a riser reactor 2, a settling tank 3, and a regenerator 7 connected in sequence. The regenerator 7 is connected to the riser reactor 2 to form a connected circulation loop of riser reactor 2, settling tank 3, regenerator 7, and riser reactor 2.

[0054] The riser reactor 2 includes a pre-rise section 21 and a reaction section 20. The reaction section 20 is located above and communicates with the pre-rise section 21. An inlet 1 is provided at the connection between the pre-rise section 21 and the reaction section 20. Raw material ethylene 17 and dilution gas 18 enter the riser reactor 2 through the inlet 1, contact the catalyst, and undergo a catalytic reaction to produce propylene. A feed inlet is provided at the end of the pre-rise section 21 away from the inlet 1, and a discharge outlet is provided at the end of the reaction section 20 away from the inlet 1. A riser gas inlet 11 is provided at the bottom of the pre-rise section 21. Riser gas enters the pre-rise section 20 through the riser gas inlet 11, delivering the catalyst filled in the pre-rise section 20 to the reaction section 20 to contact the ethylene and undergo a catalytic reaction to produce propylene. The length ratio of the pre-rise section 21 to the reaction section 20 is 1:(1~9); the pipe diameter ratio of the pre-rise section 21 to the reaction section 20 is (2~10):1. The narrowing treatment of the pre-lifting section 21 to the reaction section 20 of the riser reactor 2 can suddenly increase the gas flow velocity in the reaction section 20. On the one hand, this can shorten the contact time between ethylene and the catalyst, preventing the formation of excessive carbon deposits that accelerate catalyst deactivation; on the other hand, the high gas flow velocity in the reaction section 20 after the narrowing treatment allows the catalyst to enter the settling tank 3 more effectively. If the gas flow velocity in the riser reactor 2 is uniform, it may lead to catalyst accumulation in the reaction section 20, which is detrimental to catalyst circulation throughout the fluidized bed. The reaction section 20 is connected to the settling tank 3.

[0055] The settling tank 3 is equipped with a cyclone separator 12 at the top and a stripping pipe 4 at the bottom. The stripping pipe 4 has a stripping gas inlet 6. The stripping gas desorbs the gas adsorbed in the catalyst and achieves gas-solid separation under the action of the cyclone separator 12. The separated gas is sent to the gas separation system 14 through a pipeline to separate the product gas 15 and recycled ethylene 19. Product gas 15 is propylene, and recycled ethylene 19 is unreacted ethylene. Recycled ethylene 19 can be used as raw material ethylene 17 to re-enter the riser reactor 2 for catalytic reaction to produce propylene. The separated solid, i.e., the catalyst to be generated, enters the regenerator 7 for regeneration. The stripping pipe 4 in the settling tank 3 is connected to the regenerator 7 through a catalyst inclined pipe 5, which is equipped with a needle valve 10 for control.

[0056] The regenerator 7 is equipped with a cyclone separator 12 and a flue gas outlet 13 at the top, and a regeneration gas inlet 8 at the bottom. Regeneration gas enters the regenerator 7 through the regeneration gas inlet 8 and regenerates the catalyst to be generated at 500-750°C. The flue gas generated during the regeneration process is separated by the cyclone separator 12 and discharged through the flue gas outlet 13. Simultaneously, the regenerator 7 is connected to the feed inlet at the end of the pre-lift section 21 of the riser reactor 2 via a regeneration inclined pipe 9. A needle valve 10 with a control switch is installed on the regeneration inclined pipe 9. When the needle valve 10 is opened, the regenerated catalyst obtained after regeneration returns to the pre-lift section 21 of the riser reactor 2 for the next catalytic reaction.

[0057] The fluidized bed equipment for direct propylene production from ethylene further includes a gas separation system 14 and a preheating furnace 16. The gas separation system 14 is connected to the gas outlet of the cyclone separator 12 in the settling tank 3 via a pipeline, and is used to separate the gas in the settling tank 3 to separate product gas 15 and recycled ethylene 19. Product gas 15 is propylene, and recycled ethylene 19 is ethylene that has not participated in the reaction. Recycled ethylene 19 can be used as raw material ethylene 17 to re-enter the riser reactor 2 for catalytic reaction to produce propylene.

[0058] The preheating furnace 16 is located at the front end of the inlet 1 and is used to preheat the ethylene 17 and dilution gas 18. After being preheated to 280~450°C by the preheating furnace 16, the ethylene 17 and dilution gas 18 enter the reaction section 20 of the riser reactor 2 through the inlet 1 and come into contact with the catalyst to react and generate propylene.

[0059] 2. Explanation of the principle of propylene preparation using the fluidized bed equipment for direct propylene production from ethylene. Ethylene 17 and dilution gas 18 are preheated to 280-450°C in preheating furnace 16 and then enter the reaction section 20 of riser reactor 2 through inlet 1. Simultaneously, riser gas is introduced into riser gas inlet 11, sending the catalyst filled in pre-riser section 20 to reaction section 20. The catalyst contacts ethylene in reaction section 20 to catalyze the reaction to produce propylene. Under the continuous introduction of ethylene, dilution gas 18, and riser gas, the catalyst in reaction section 20 (which becomes a catalyst after entering settling tank 3), the product gas 15 generated from the reaction, and unreacted ethylene flow into settling tank 3. At this time, stripping gas is introduced through stripping gas inlet 6 on stripping pipe 4 of settling tank 3, and the stripping gas is desorbed. The gas adsorbed in the catalyst awaiting generation, at this time, contains solid (catalyst awaiting generation) and mixed gas (product gas 15 generated from the reaction, unreacted ethylene, product gas 15 and ethylene desorbed from the catalyst awaiting generation, and a small amount of stripping gas). After gas-solid separation by cyclone separator 12 in settler 3, the separated gas is sent to gas separation system 14 via pipeline for further separation of product gas 15 and recycled ethylene 19. Product gas 15 is propylene, and recycled ethylene 19 is unreacted ethylene. Recycled ethylene 19 can be used as feedstock ethylene 17 to re-enter riser reactor 2 for catalytic reaction to produce propylene. The solid enters regenerator 7 for regeneration. Regeneration is achieved by introducing regeneration gas through regeneration gas inlet 8, controlling the temperature in regenerator 7 to 500~750℃, and regenerating the catalyst awaiting generation. The regenerated catalyst (called the regenerated catalyst) returns to the pre-lift section 21 of riser reactor 2 through the feed inlet to undergo the next catalytic reaction, forming a circulating fluidized bed for continuous propylene production.

[0060] 3. Process description for the direct production of propylene from ethylene The process for directly producing propylene from ethylene can be carried out using "1. Fluidized bed equipment for direct ethylene-propylene production", including the following steps: (1) Catalyst pre-activation: The catalyst is pre-activated at 250~450℃ under N2 atmosphere for 1~5h; (2) Catalytic reaction: The pre-activated catalyst is placed in the riser reactor 2, and riser gas, ethylene 17 and dilution gas 18 are introduced to make ethylene 17 contact the catalyst and carry out catalytic reaction in the reaction section 20 of the riser reactor 2. (3) Gas-solid separation and catalyst regeneration: The reaction products in step (2) enter the settling tank 3, stripping gas is introduced, and gas-solid separation is performed to obtain mixed gas and catalyst to be generated; then, the mixed gas enters the gas separation system 14 for separation to obtain product gas 15 and recycled ethylene 19. The catalyst awaiting regeneration enters regenerator 7 for regeneration; the catalyst is regenerated at 500~750℃ in a regeneration gas atmosphere, and the carbon deposit content of the regenerated catalyst is controlled to be 1.5~12 wt%. (4) Circulation: The regenerated catalyst is returned to the riser reactor 2 through the regeneration inclined tube 9, and the steps (2) to (4) are repeated.

[0061] Specifically, the catalyst used in step (1) is a microsphere molecular sieve catalyst with an average particle size of 80~90μm and a density of 0.6~0.75g / cm³. 3 Based on the packing density, catalysts such as SSZ-13, ZSM-5, SAPO-34, SSZ-39, and SAPO-18 are available for reference, with SSZ-13 and ZSM-5 being preferred.

[0062] In step (2), riser gas is introduced into the riser gas inlet 11, which lifts the catalyst to the reaction section 20 of the riser reactor 2. Ethylene 17 and dilution gas 18 are introduced into the sample inlet 1. The catalyst contacts ethylene 17 and dilution gas 18 in the reaction section 20 and undergoes a catalytic reaction at a temperature of 280~450℃, 280~420℃, or 300~350℃, and a pressure of 0~0.3MPa or 0~0.2MPa. The reaction in the reaction section 20 is controlled by the gas ratio and gas rate. The linear velocity of the gas phase (including booster gas, ethylene and dilution gas) is 2~10 m / s or 2~8 m / s, and the reaction time is 0.1~3 s or 0.5~2 s.

[0063] If we take V 乙烯 The volume of ethylene in the catalytic reaction is represented by V. 提升气+稀释气 If V represents the sum of the volumes of the lift gas and the dilution gas in the catalytic reaction, then the following condition must be met: 提升气+稀释气 V 乙烯 = (10~0.5):1; preferably the V 提升气+稀释气 V 乙烯 =(8~1):1; The mass ratio of catalyst to ethylene is (5~40):1, preferably (8~30):1, and even more preferably (10~20):1.

[0064] Among the dilution gases that can be used for reference, such as water vapor, nitrogen, and argon, water vapor should be given priority. Among the boosting gases that can be used for reference, such as water vapor, nitrogen, and argon, water vapor should be given priority.

[0065] In step (3), stripping gas is introduced at a flow rate of 100-200 g / h. Suitable stripping gases include water vapor and nitrogen. The regeneration gas is an oxygen-containing mixture with a volume fraction of 1-25% oxygen; preferably, it is an oxygen-containing mixture with a volume fraction of 3-19%. Specifically, the oxygen component in the regeneration gas originates from air or oxygen-enriched air, while other components can consist of carbon dioxide, water vapor, and nitrogen. For example, the regeneration gas may include air and water vapor, with the volume ratio of air to water vapor controlled to achieve an oxygen volume fraction of 19%; or the regeneration gas may include oxygen-enriched air with a volume fraction of 30% oxygen and water vapor, with the volume ratio of oxygen-enriched air to water vapor controlled to achieve an oxygen volume fraction of 25%. In the process of ethylene to propylene, the amount of carbon deposited on the regenerated catalyst can be controlled by adjusting regeneration conditions, such as the composition of the regeneration gas and the regeneration temperature. An increase in the volume fraction of oxygen in the regenerated gas and an increase in the regeneration temperature will reduce the amount of carbon deposits on the regenerated catalyst, and vice versa.

[0066] Raw material information used in the examples SSZ-13 molecular sieve: SiO2:Al2O3=20, average particle size 80μm, bulk density 0.68 g / cm³ 3 , Zhengda Energy Materials (Dalian) Co., Ltd.

[0067] Example 1 This embodiment uses the fluidized bed equipment described in "1. Structural Description of Fluidized Bed Equipment for Direct Ethylene-to-Propylene Production" to directly produce propylene from ethylene. For example... Figure 1 As shown, the length of the reaction section 20 of the riser reactor 2 of the fluidized bed equipment used in this embodiment is 3 m, the length ratio of the pre-lifting section 21 to the reaction section 20 is 1:7, and the pipe diameter ratio of the pre-lifting section 21 to the reaction section 20 is 2:1.

[0068] The catalyst used in this embodiment is SSZ-13 molecular sieve, which has an average particle size of 80 μm and a bulk density of 0.68 g / cm³. 3 The catalyst is placed in the fluidized bed apparatus for the direct production of propylene from ethylene.

[0069] The process for producing propylene using the fluidized bed equipment for the direct production of propylene from ethylene is as follows: (1) Catalyst pre-activation: The catalyst was pre-activated at 350℃ under N2 atmosphere for 2h; (2) Catalytic reaction: The pre-activated catalyst is placed in the riser reactor 2, and ethylene 17 and dilution gas 18 are introduced into the riser reactor 2 to bring the ethylene into contact with the catalyst and carry out the catalytic reaction in the reaction section 20 of the riser reactor 2. The mass ratio of catalyst to ethylene is 20. Both the dilution gas and the booster gas are water vapor, V 提升气+稀释气 V 乙烯 =3:1; The catalytic reaction conditions were as follows: the reaction was carried out at a temperature of 350℃ (preheating of ethylene 17 and dilution gas 18 by preheating furnace 16), at atmospheric pressure (standard atmospheric pressure, reaction pressure of approximately 0.101325 MPa), and at a gas phase linear velocity of 3 m / s in the reaction section, for a reaction time of 1.0 s.

[0070] (3) Gas-solid separation and catalyst regeneration: The reaction products in step (2) enter the settling tank 3, and stripping gas (water vapor, flow rate of 100g / h) is introduced to perform gas-solid separation to obtain mixed gas and catalyst to be regenerated; then, the mixed gas enters the gas separation system 14 for separation to obtain product gas 15 (propylene) and recycled ethylene 19. The catalyst to be regenerated enters regenerator 7 for regeneration. The catalyst is regenerated at 550°C in a regeneration gas atmosphere (a mixture of air and water vapor, with an oxygen volume fraction of 13%). Thermogravimetric analysis (TG analysis) is used to detect the amount of carbon deposit on the catalyst, and the amount of carbon deposit on the regenerated catalyst is controlled to be 7 wt%. After the equipment is running stably, the amount of carbon deposit on the regenerated catalyst can be maintained at around 7 wt%.

[0071] (4) Recycling: The regenerated catalyst is returned to the riser reactor 2 through the regeneration inclined tube 9 to continue steps (2) to (4). Among them, the recycled ethylene 19 obtained in step (3) is used as raw material ethylene in step (2).

[0072] After the operation stabilized, the total ethylene conversion rate remained stable at 96%, and the propylene yield was 83.5%.

[0073] Example 2 The only difference between this embodiment and Embodiment 1 is that the length ratio of the pre-lifting section 21 to the reaction section 20 in the riser reactor 2 of the fluidized bed equipment for the direct production of propylene from ethylene is different. In this embodiment, the length ratio of the pre-lifting section 21 to the reaction section 20 is 1:9.

[0074] After the operation stabilized, the total ethylene conversion rate remained stable at 97%, and the propylene yield was 82.4%.

[0075] Example 3 The only difference between this embodiment and Embodiment 1 is that the length ratio of the pre-lifting section 21 to the reaction section 20 in the riser reactor 2 of the fluidized bed equipment for the direct production of propylene from ethylene is different. In this embodiment, the length ratio of the pre-lifting section 21 to the reaction section 20 is 1:1. After the operation stabilized, the total ethylene conversion rate remained stable at 93%, and the propylene yield was 80%.

[0076] Example 4 The only difference between this embodiment and Example 1 is that the regeneration conditions in the corresponding step (3) are different, resulting in a different amount of carbon deposits on the regenerated catalyst.

[0077] In this embodiment, the catalyst was regenerated at 550°C in a regeneration gas atmosphere (a mixture of air and water vapor, wherein the volume fraction of oxygen was 15%), and the corresponding carbon deposition of the regenerated catalyst was 4 wt%.

[0078] After the operation stabilized, the total ethylene conversion rate remained stable at 95%, and the propylene yield was 82.2%.

[0079] Example 5 The only difference between this embodiment and Example 1 is that the regeneration conditions in the corresponding step (3) are different, resulting in a different amount of carbon deposits on the regenerated catalyst.

[0080] In this embodiment, the catalyst was regenerated at 550°C in a regeneration gas atmosphere (a mixture of air, water vapor and nitrogen, wherein the volume fraction of oxygen was 5%), and the corresponding carbon deposition of the regenerated catalyst was 10 wt%.

[0081] After the operation stabilized, the total ethylene conversion rate remained stable at 93%, and the propylene yield was 80.9%.

[0082] Example 6 The only difference between this embodiment and Example 1 is that the regeneration conditions in the corresponding step (3) are different, resulting in a different amount of carbon deposits on the regenerated catalyst.

[0083] In this embodiment, the catalyst was regenerated at 550°C in a regeneration gas atmosphere (a mixture of oxygen-enriched air and water vapor, wherein the volume fraction of oxygen was 23%), and the corresponding carbon deposition of the regenerated catalyst was 1.5 wt%.

[0084] After the operation stabilized, the total ethylene conversion rate remained stable at 97%, and the propylene yield was 78.6%.

[0085] Example 7 The only difference between this embodiment and Embodiment 1 is the gas phase linear velocity in the reaction section in step (2) and the regeneration conditions in step (3).

[0086] In this embodiment, the gas phase linear velocity in the reaction section corresponding to step (2) is 2 m / s.

[0087] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 550°C in a regeneration gas atmosphere (a mixture of air and water vapor, wherein the volume fraction of oxygen is 12.5%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0088] After the operation stabilized, the total ethylene conversion rate remained stable at 97%, and the propylene yield was 78.6%.

[0089] Example 8 The only difference between this embodiment and Embodiment 1 is the gas phase linear velocity in the reaction section in step (2) and the regeneration conditions in step (3).

[0090] In this embodiment, the gas phase linear velocity in the reaction section corresponding to step (2) is 10 m / s.

[0091] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 650°C in a regeneration gas atmosphere (a mixture of oxygen-enriched air and water vapor, wherein the volume fraction of oxygen is 16%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0092] After the operation stabilized, the total ethylene conversion rate remained stable at 92%, and the propylene yield was 81%.

[0093] Example 9 The only difference between this embodiment and Example 1 is the reaction temperature in step (2) and the regeneration conditions in step (3).

[0094] The reaction temperature in step (2) of this embodiment is 280℃.

[0095] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 550°C in a regeneration gas atmosphere (a mixture of air, nitrogen and water vapor, wherein the volume fraction of oxygen is 8%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0096] After the operation stabilized, the total ethylene conversion rate remained stable at 90%, and the propylene yield was 80.1%.

[0097] Example 10 The only difference between this embodiment and Example 1 is the reaction temperature in step (2) and the regeneration conditions in step (3).

[0098] The reaction temperature in step (2) of this embodiment is 420℃.

[0099] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 550°C in a regeneration gas atmosphere (a mixture of oxygen-enriched air and water vapor, wherein the volume fraction of oxygen is 21%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0100] After the operation stabilized, the total ethylene conversion rate remained stable at 98%, and the propylene yield was 79.4%.

[0101] Example 11 The difference between this embodiment and embodiment 1 lies only in step (2) where V 提升气+稀释气 V 乙烯 The ratio is different from the regeneration conditions in step (3).

[0102] In this embodiment, V corresponds to step (2). 提升气+稀释气 V 乙烯 The ratio is 1:1.

[0103] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 600°C in a regeneration gas atmosphere (a mixture of air and water vapor, wherein the volume fraction of oxygen is 18%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0104] After the operation stabilized, the total ethylene conversion rate remained stable at 97%, and the propylene yield was 81.5%.

[0105] Example 12 The difference between this embodiment and embodiment 1 lies only in step (2) where V 提升气+稀释气 V 乙烯 The ratio is different from the regeneration conditions in step (3).

[0106] In this embodiment, V corresponds to step (2). 提升气+稀释气 V 乙烯 The ratio is 8:1.

[0107] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 550°C in a regeneration gas atmosphere (a mixture of air, nitrogen and water vapor, wherein the volume fraction of oxygen is 9%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0108] After the operation stabilized, the total ethylene conversion rate remained stable at 97%, and the propylene yield was 82.5%.

[0109] Comparative Example 1 The only difference between this comparative example and Example 1 is the regeneration conditions in the corresponding step (3), which in turn results in a different amount of carbon deposit on the regenerated catalyst. In this embodiment, the catalyst was regenerated at 450°C in a regeneration gas atmosphere (a mixture of air, nitrogen and water vapor, wherein the volume fraction of oxygen was 5%), and the corresponding carbon deposition of the regenerated catalyst was 17 wt%.

[0110] After the operation stabilized, the total ethylene conversion rate remained stable at 71%, and the propylene yield was 61.1%.

[0111] Comparative Example 2 The only difference between this comparative example and Example 1 is the regeneration conditions in the corresponding step (3), which in turn results in a different amount of carbon deposit on the regenerated catalyst.

[0112] In this embodiment, the catalyst was regenerated at 650°C in a regeneration gas atmosphere (a mixture of oxygen-enriched air and water vapor, wherein the volume fraction of oxygen was 26%), and the corresponding carbon deposition of the regenerated catalyst was 0.2 wt%.

[0113] After the operation stabilized, the total ethylene conversion rate remained stable at 97%, and the propylene yield was 14.6%.

[0114] Comparative Example 3 The only difference between this comparative example and Example 1 is in step (2) V 提升气+稀释气 V 乙烯 The ratio is different from the regeneration conditions in step (3).

[0115] In this embodiment, no dilution gas is added in step (2), V 提升气+稀释气 V 乙烯 The ratio is 0.1:1.

[0116] Meanwhile, the regeneration conditions corresponding to step (3) are adjusted to be: catalyst regeneration is carried out at 600°C in a regeneration gas atmosphere (a mixture of oxygen-enriched air and water vapor, wherein the volume fraction of oxygen is 21%), so that the amount of carbon deposits on the regenerated catalyst is consistent with that in Example 1.

[0117] After the operation stabilized, the total ethylene conversion rate remained stable at 80%, and the propylene yield was 55.2%. The decrease in propylene yield was due to the absence of dilution gas, which increased the volume fraction of ethylene in the reaction section, caused rapid exothermic reaction, and made the temperature uncontrollable. This led to rapid carbon deposition on the catalyst in the reaction section, resulting in excessive carbon buildup, a decrease in ethylene conversion rate, and an increase in propylene side reactions, ultimately leading to a lower propylene yield. As can be seen from the above experimental comparisons, by adjusting the process parameters in Examples 1 to 12, propylene can be directly produced from ethylene within the range of technical parameters defined in this invention, and high ethylene conversion rate and high propylene yield can be achieved.

[0118] Comparison of data from Comparative Examples 1-2, Example 1, and Examples 4-6 shows that the amount of catalyst carbon deposit is a crucial control parameter in this process. The results of Comparative Examples 1 and 2 indicate that both excessively high and low catalyst carbon deposits affect propylene yield; excessively high deposits primarily affect ethylene conversion, while excessively low deposits primarily affect propylene selectivity (manifested as propylene yield).

[0119] Comparing Comparative Example 3 with Example 1, it can be seen that dilution gas plays an important role in the process of direct ethylene to propylene production. 提升气+稀释气 V 乙烯 The ratio is mainly determined by the dilution gas and ethylene, V 提升气+稀释气 V 乙烯 By controlling the ratio within a reasonable range, the partial pressure of ethylene can be kept under control, allowing for precise control of the exothermic reaction and avoiding the increase in side reactions caused by difficulties in temperature control.

[0120] The above description provides an illustrative overview of the present invention and its embodiments. This description is not restrictive, and the embodiments shown are merely one example of the invention's implementation. Actual implementations are not limited to these examples. Therefore, if those skilled in the art are inspired by this description and design similar implementations and examples without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention.

Claims

1. A process for the direct production of propylene from ethylene, characterized in that, Includes the following steps: (1) Catalyst pre-activation: The catalyst is pre-activated at 250~450℃ under N2 atmosphere for 1~5h; (2) Catalytic reaction: The pre-activated catalyst is placed in the riser reactor (2), and riser gas, ethylene and dilution gas are introduced to bring the ethylene into contact with the catalyst and carry out the catalytic reaction in the reaction section (20) of the riser reactor (2); (3) Gas-solid separation and catalyst regeneration: The reaction products in step (2) enter the settling tank (3), and stripping gas is introduced into the settling tank (3) to carry out gas-solid separation to obtain a mixed gas and a catalyst to be generated; then, the mixed gas enters the gas separation system (14) for separation to obtain product gas (15) and recycled ethylene (19). The catalyst to be regenerated enters the regenerator (7) and is regenerated at 500~750℃ in a regeneration gas atmosphere, with the carbon deposition on the regenerated catalyst controlled to be 1.5~12 wt%. (4) Circulation: The regenerated catalyst is returned to the riser reactor (2) through the regeneration inclined tube (9) and the steps (2) to (4) are repeated.

2. The process for directly producing propylene from ethylene according to claim 1, characterized in that, In step (2), the boosting gas enters the pre-boosting section (21) of the riser reactor (2) through the boosting gas inlet (11), and the catalyst reaches the reaction section (20) in the riser reactor (2) under the action of the boosting gas and comes into contact with ethylene; The mass ratio of catalyst to ethylene is (5~40):

1.

3. The process for directly producing propylene from ethylene according to claim 2, characterized in that, In step (2), the catalytic reaction satisfies one or more of the following conditions (I) to (IV): (I) The reaction temperature is 280~450℃; (II) The reaction pressure is 0~0.3 MPa; (III) The gas phase linear velocity of the reaction section (20) is 2~10 m / s; (IV) The reaction time is 0.1~3s.

4. The process for directly producing propylene from ethylene according to claim 3, characterized in that, In step (2), V 乙烯 The volume of ethylene in the catalytic reaction is represented by V. 提升气+稀释气 V represents the sum of the volumes of the lift gas and the dilution gas in the catalytic reaction, satisfying: 提升气+稀释气 V 乙烯 = (10~0.5):1; The dilution gas includes one or more of water vapor, nitrogen, and argon; The lifting gas includes one or more of water vapor, nitrogen, and argon.

5. The process for directly producing propylene from ethylene according to claim 4, characterized in that, In step (3), the stripping gas includes one or more of water vapor and nitrogen, and the flow rate of the stripping gas is 100~200g / h.

6. The process for directly producing propylene from ethylene according to claim 5, characterized in that, In step (3), the regenerated gas is an oxygen-containing mixed gas, and the volume fraction of oxygen in the regenerated gas is 1-25%. And / or, the regenerated gas includes one or more of air, oxygen-enriched air, and one or more of carbon dioxide, water vapor, and nitrogen.

7. The process for directly producing propylene from ethylene according to claim 6, characterized in that, In step (1), the catalyst is a microsphere molecular sieve catalyst with an average particle size of 80-90 μm and a bulk density of 0.6-0.75 g / cm³. 3 ; The catalyst includes one or more of SSZ-13, ZSM-5, SAPO-34, SSZ-39, and SAPO-18.

8. A fluidized bed apparatus for the direct production of propylene from ethylene, characterized in that, It includes a riser reactor (2), a settling tank (3) and a regenerator (7) connected in sequence. The regenerator (7) is connected to the riser reactor (2) to form a connected circulation loop of riser reactor (2), settling tank (3), regenerator (7) and riser reactor (2). The riser reactor (2) includes a pre-lifting section (21) and a reaction section (20); the reaction section (20) is located above the pre-lifting section (21) and is connected to the pre-lifting section (21), with an inlet (1) at the connection point; an inlet is located at the end of the pre-lifting section (21) away from the inlet (1), and an outlet is located at the end of the reaction section (20) away from the inlet (1); a riser gas inlet (11) is located at the bottom of the pre-lifting section (21); and the reaction section (20) is connected to the settler (3). The settling device (3) is equipped with a cyclone separator at the top and a stripping pipe (4) at the bottom. The stripping pipe (4) is equipped with a stripping gas inlet (6). The stripping pipe (4) is connected to the regenerator (7) through a waiting inclined pipe (5). The regenerator (7) is equipped with a cyclone separator and a flue gas outlet (13) at the top and a regeneration gas inlet (8) at the bottom; the regenerator (7) is connected to the feed inlet of the riser reactor (2) through a regeneration inclined tube (9).

9. The fluidized bed apparatus for direct propylene production from ethylene according to claim 8, characterized in that, The length ratio of the pre-lifting section (21) to the reaction section (20) is 1:(1~9); the pipe diameter ratio of the pre-lifting section (21) to the reaction section (20) is (2~10):

1.

10. The fluidized bed apparatus for direct propylene production from ethylene according to claim 8 or 9, characterized in that, It also includes: a gas separation system (14) and a preheating furnace (16), wherein the gas separation system (14) is connected to the gas outlet of the cyclone separator in the settling tank (3) via a pipeline for separating product gas (15) and recycled ethylene (19). The preheating furnace (16) is located at the front end of the inlet (1). Ethylene and dilution gas are preheated by the preheating furnace (16) and then enter the reaction section (20) of the riser reactor (2) through the inlet (1).

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