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CN-122010661-A - Process and equipment for directly preparing propylene from ethylene

CN122010661ACN 122010661 ACN122010661 ACN 122010661ACN-122010661-A

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, which comprises the following steps of (1) pre-activating a catalyst, (2) catalyzing, separating gas and solid, regenerating the catalyst in a regenerator at 500-750 ℃ in a regenerated gas atmosphere, controlling the carbon deposition of the regenerated catalyst to be 1.5-12 wt%, and (4) circulating, wherein the regenerated catalyst returns to a riser reactor through a regeneration inclined tube, and steps (2) - (4) are performed circularly. The process for directly preparing propylene from ethylene can effectively regulate and control the heat release problem and accurately regulate and control the carbon deposition of the catalyst, can avoid the deactivation caused by excessive carbon deposition of the catalyst, and can also improve the yield of propylene. And the catalyst regeneration and the catalytic reaction of preparing propylene from ethylene can be synchronously carried out, so that continuous work is realized without frequent shutdown.

Inventors

  • LIU ZHIQIANG
  • WEI XIAONA
  • ZHAO BOQI
  • WANG CHUANG
  • LI LI
  • Xing Debao

Assignees

  • 正大能源材料(大连)有限公司

Dates

Publication Date
20260512
Application Date
20260128

Claims (10)

  1. 1. A process for the direct preparation of propylene from ethylene, comprising the steps of: (1) Pre-activating the catalyst for 1-5 h at the temperature of 250-450 ℃ in the atmosphere of N 2 ; (2) The catalyst after preactivation is placed in a riser reactor (2), and the lift gas, ethylene and diluent gas are introduced to make the ethylene contact with the catalyst, and the catalytic reaction is carried out in a reaction section (20) of the riser reactor (2); (3) The gas-solid separation and catalyst regeneration, namely, the reaction product in the step (2) enters a settler (3), stripping gas is introduced into the settler (3) to carry out gas-solid separation to obtain mixed gas and catalyst to be regenerated, and then, the mixed gas enters a gas separation system (14) to carry out separation to obtain product gas (15) and circulating ethylene (19); The spent catalyst enters a regenerator (7) to be regenerated under the atmosphere of 500-750 ℃ and regeneration gas, and the carbon deposition of the regenerated catalyst is controlled to be 1.5-12 wt%; (4) And (3) circulating, namely returning the regenerated catalyst to the riser reactor (2) through a regeneration inclined tube (9), and circularly carrying out the steps (2) - (4).
  2. 2. Process for the direct preparation of propylene from ethylene according to claim 1, characterized in that in step (2) the lift gas enters the pre-lift section (21) of the riser reactor (2) through the lift gas inlet (11) and the catalyst reaches the reaction section (20) in the riser reactor (2) under the effect of the lift gas, in contact with ethylene; wherein the mass ratio of the catalyst to the ethylene is (5-40): 1.
  3. 3. The process for the direct preparation of 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) - (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 to 3s.
  4. 4. The process for directly preparing propylene from ethylene according to claim 3, wherein in the step (2), V Ethylene represents the volume of ethylene in the catalytic reaction, and V Lifting qi + Dilution gas represents the sum of the volumes of the lifting gas and the diluting gas in the catalytic reaction, and the ratio of V Lifting qi + Dilution gas : V Ethylene = (10-0.5) to 1 is satisfied; the dilution gas comprises one or more of steam, nitrogen and argon; the lifting gas comprises one or more of steam, nitrogen and argon.
  5. 5. The process for directly producing propylene from ethylene according to claim 4, wherein in the step (3), the stripping gas comprises one or more of steam and nitrogen, and the flow rate of the stripping gas is 100-200 g/h.
  6. 6. The process for directly preparing propylene from ethylene according to claim 5, wherein in the step (3), the regeneration gas is an oxygen-containing mixed gas, and the volume fraction of oxygen in the regeneration gas is 1-25%; And/or the regeneration gas comprises one or more of air, oxygen-enriched air and one or more of carbon dioxide, water vapor and nitrogen.
  7. 7. The process for directly preparing propylene from ethylene according to claim 6, wherein in the step (1), the catalyst is catalyzed by a microsphere molecular sieve, the average particle size of the catalyst is 80-90 μm, and the bulk density is 0.6-0.75 g/cm 3 ; The catalyst comprises one or more of SSZ-13, ZSM-5, SAPO-34, SSZ-39 and SAPO-18.
  8. 8. The fluidized bed equipment for directly preparing propylene from ethylene is characterized by comprising a riser reactor (2), a settler (3) and a regenerator (7) which are sequentially communicated, wherein the regenerator (7) is connected with the riser reactor (2) to form a communication circulation loop of the riser reactor (2), the settler (3), the regenerator (7) and the riser reactor (2); The riser reactor (2) comprises a pre-lifting section (21) and a reaction section (20), wherein the reaction section (20) is arranged at the upper part of the pre-lifting section (21) and is communicated with the pre-lifting section (21), a sample inlet (1) is arranged at the communication position of the pre-lifting section (20) and the reaction section, a feeding port is arranged at the tail end of the pre-lifting section (21) far away from the sample inlet (1), a discharge port is arranged at the tail end of the reaction section (20) far away from the sample inlet (1), a lifting gas inlet (11) is arranged at the bottom of the pre-lifting section (21), and the reaction section (20) is communicated with the settler (3); The top of the settler (3) is provided with a cyclone separator, the bottom of the settler is provided with a stripping pipe (4), the stripping pipe (4) is provided with a stripping gas inlet (6), and the stripping pipe (4) is communicated with a regenerator (7) through a waiting inclined pipe (5); the top of the regenerator (7) is provided with a cyclone separator and a flue gas outlet (13), the bottom of the regenerator is provided with a regeneration gas inlet (8), and the regenerator (7) is communicated with a feed inlet of the riser reactor (2) through a regeneration inclined tube (9).
  9. 9. The fluidized bed apparatus for directly preparing propylene from ethylene according to claim 8, wherein the length ratio of the pre-lifting section (21) to the reaction section (20) is 1 (1-9), and the pipe diameter ratio of the pre-lifting section (21) to the reaction section (20) is (2-10): 1.
  10. 10. Fluidized bed unit for the direct preparation of propylene from ethylene according to claim 8 or 9, characterized in that it further comprises a gas separation system (14), a preheating furnace (16), said gas separation system (14) being connected by piping to the gas outlet of the cyclone in the settler (3) for separating the product gas (15) and the recycled ethylene (19); the preheating furnace (16) is arranged at the front end of the sample inlet (1), and ethylene and diluent gas enter the reaction section (20) of the riser reactor (2) through the sample inlet (1) after being preheated by the preheating furnace (16).

Description

Process and equipment for directly preparing propylene from ethylene Technical Field The invention belongs to the technical field of chemistry and chemical engineering, and particularly relates to a process and equipment for directly preparing propylene from ethylene. Background Propylene is an important basic organic chemical raw material and is widely applied to the synthesis of products such as acrylonitrile, propylene oxide, isopropanol, acetone, polypropylene resin, butanol, various fine chemicals and the like. In recent years, with the strong promotion of the technology of preparing olefin (MTO) from methanol, preparing ethylene from bioethanol and the like in China, the yield of ethylene is improved year by year, but the supply growth of propylene is always delayed from the increase of market demand, so that the development of a new propylene source technology and the improvement of the supply capability of propylene have great significance in optimizing the structure of olefin products and improving the economic benefits of petrochemical and coal chemical industry. At present, the technology for preparing propylene by disproportionation reaction of ethylene and butene is mature, but the one-step technology for preparing propylene by directly converting ethylene has less research. Compared with the ethylene/butene disproportionation process which needs a matched butene source and a complex separation process, the process for directly preparing propylene from ethylene has the advantages of single raw material source, simple flow and the like. Therefore, the ethylene-propylene conversion route is an important concern in the industry. The reaction mechanism for the direct preparation of propylene (Ethylene to Propylene, ETP for short) from ethylene is based on the Jiang Bu lambertian acid catalyzed oligomerization-cleavage mechanism. The strong Bronsted acid sites (Br NSTED ACID SITES) on molecular sieve catalysts (e.g. H-ZSM-5, H-SSZ-13, etc.) react with ethylene molecules, ethylene is first protonated to form carbonium ions, then chain-extended to form C 3~C8 alkane intermediates, and finally beta-site cleavage to yield the target products propylene and butene, etc. Related patents (such as ZL201810224320.3, ZL201410104214.3 and the like) report that the technical conditions for directly preparing propylene by using ethylene are evaluated by adopting a fixed bed reactor, wherein the reaction temperature in ZL201810224320.3 is 450-500 ℃, the normal pressure and the ethylene Weight Hourly Space Velocity (WHSV) are 0.5-5 h -1, and the reaction conditions in ZL201410104214.3 are 300-450 ℃, the normal pressure and the WHSV are 1.0-10.0 h - 1. The optimal performance of the H-SSZ-13 molecular sieve on a fixed bed after acid treatment is that the ethylene conversion rate is 84.7%, the propylene selectivity is 62.2%, and the service life of the catalyst is more than 10 hours. Although the above fixed bed process establishes the basic reaction conditions, this reactor type exposes the following key problems in the direct preparation of propylene from ethylene: firstly, the ethylene oligomerization reaction is a strong exothermic reaction, and in a fixed bed reactor, the heat dissipation effect of reaction heat is poor, so that the secondary reaction of propylene products is aggravated (dehydrogenation, isomerization and deep cracking), and the yield of target products is reduced. Secondly, carbon deposition is generated in the reaction process of the catalyst, and the reaction heat release can aggravate the carbon deposition and deactivation of the catalyst. The catalyst is required to be regenerated by carbon burning after being deactivated, the traditional regeneration is usually carried out for 4-6 hours at 700 ℃ in an air atmosphere, and aluminum in a molecular sieve frame is easy to leach (dealumination) in the high-temperature carbon burning process, so that active sites are permanently lost, and the performance of the catalyst is gradually attenuated. The most fatal is that the fixed bed reaction and the regeneration must be carried out separately, the device needs to be completely shut down, and complex operations such as temperature rising, carbon burning, cooling and the like are included, continuous and stable operation can not be realized, and the industrial application is severely restricted. Finally, in the existing fixed bed, the carbon deposition regulation and control of the catalyst are inflexible, the selectivity cannot be improved through process optimization, the propylene selectivity is monotonically reduced along with the reaction time, and the final industrial product yield is usually only 40-50%, which is far lower than the theoretical potential. In view of the above, the existing fixed bed process is subject to the limitations of difficult temperature control, easy deactivation of catalyst, difficult continuous process and the like in the direct preparation of propylene from ethylene,