Ethylene oligomerization catalyst recovery device and method

Abstract

The invention relates to the technical field of catalyst recovery, in particular to an ethylene oligomerization catalyst recovery device and method.The ethylene oligomerization catalyst recovery method comprises the steps that ethylene and a catalyst are injected into a reactor for a reaction, and reaction liquid is formed; injecting the reaction liquid into a flash tank for flash evaporation, and discharging a flash evaporation gas phase; one part of the residual catalyst concentrated solution at the bottom of the flash tank flows back to the reactor for continuous reaction, and the rest part flows into a termination kettle; and adding a terminating agent into the terminating kettle to carry out catalyst inactivation treatment. The flash tank is additionally arranged between the reactor and the termination kettle, when reaction liquid is subjected to flash treatment, flash vapor phase ethylene, butylene and a small amount of high-boiling-point impurities are discharged as semi-finished products, part of catalyst concentrated liquid remaining in the flash tank flows back to the reactor to be reused, and the other part enters the termination kettle to be subjected to inactivation treatment; the usage amount of the catalyst and the terminator is reduced; and since the product and the catalyst are separated in advance by flash evaporation, the later purification energy consumption can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst recovery, and specifically to an ethylene oligomerization catalyst recovery device and method. Background Art

[0002] In the ethylene oligomerization production process, transition metal compounds of Groups IV-VI (main catalysts) and organometallic compounds of Groups I-II (co-catalysts) are commonly used and added to the reaction system for homogeneous catalytic reaction to produce olefin oligomers. The active catalyst is transported to the product separation unit together with the product, and then a terminator is added to deactivate the catalyst.

[0003] Patent CN118059802A discloses an oligomerization reactor for continuous production of α-olefins, including an axial flow forced circulation heat exchanger and an upper tube box and a lower tube box respectively installed at the upper and lower ends of the axial flow forced circulation heat exchanger. In its process, the mixed reaction liquid with products after the reaction stage is sent to a dynamic mixer for inactivation treatment and then enters the separation unit for product separation and purification.

[0004] Patent CN117126028A discloses a method and device for co-producing α-olefins by ethylene oligomerization. Ethylene undergoes first oligomerization under the action of a first catalyst to obtain a first material, and the first material undergoes second oligomerization under the action of a second catalyst and a polymerization inhibitor to obtain a second material. The second material is quenched and then separated to obtain 1-butene, 1-hexene, and 1-octene.

[0005] Patent CN115894148B discloses a method for continuously producing 1-octene by selective oligomerization of ethylene. After premixing a solvent, ethylene, a catalyst, and a catalytic assistant, they enter the first-stage reactor together with hydrogen for reaction. Part of the ethylene directly participates in the reaction, and the other part of the liquid-phase ethylene is drawn out of the reaction after being vaporized by absorbing heat in the upper part of the reactor, compressed and condensed, and then returned to the first-stage reactor for recycling. The liquid-phase material obtained from the first-stage reactor overflows into the second-stage reactor for continuous reaction. The temperature is higher than that of the reaction in the first-stage reactor, and the jacket temperatures of both reactors are higher than the temperature of the material in the reactor. The obtained liquid-phase product is quenched and then enters the separation system to recover the unreacted ethylene, and 1-octene product and 1-hexene product are obtained respectively.

[0006] Patent CN115106037A discloses a process for continuously producing α-olefins by selective oligomerization of ethylene. Solvent, catalyst, and ethylene are continuously fed into one of the parallel first and second reactors, and under a predetermined pressure and temperature, a selective oligomerization reaction of ethylene is carried out to obtain a reaction solution. The reaction solution passes through a buffer tank and intermittently enters a quenching and dissolution tank to be mixed with a quenching agent therein to obtain a homogeneous solution. After the homogeneous solution is successively subjected to ethylene removal, hexene removal, octene removal, and solvent removal, it is cooled and precipitated to obtain an ethylene polymer.

[0007] CN115093302A discloses a method for producing α-olefins by ethylene oligomerization reaction. A catalyst and a cocatalyst are added to an organic solvent, then ethylene is added, and hydrogen is added during stirring for reaction. After the reaction is completed, a terminator is added. The resulting reactant is subjected to flash distillation to separate unreacted ethylene and hydrogen, and then 1-octene, 1-hexene, and the organic solvent are obtained through rectification. The catalyst flowing out of the reactor still has activity, and the catalyst activity cannot be fully utilized, resulting in catalyst waste. If most of the catalyst in the product stream can be recycled and reused in the reactor, then the amount of catalyst inactivator used to deactivate the catalyst will be greatly reduced; at the same time, the generation of hazardous waste will also be greatly reduced. Based on this, a method and device for recycling ethylene oligomerization catalyst are proposed. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the present invention provides a device and method for recycling ethylene oligomerization catalyst, which improve the production efficiency of the catalyst, reduce the usage amount of the terminator, and significantly reduce the generation of harmful waste through flash distillation treatment.

[0009] To achieve the above object, the present invention provides the following technical solution: An ethylene oligomerization catalyst recycling device, comprising a reactor, and an ethylene feed port and a catalyst feed port are arranged at the bottom of the reactor;

[0010] A flash tank connected to the reactor to separate the catalyst;

[0011] A termination kettle connected to the flash tank. Part of the catalyst flowing out of the flash tank flows back into the reactor, and the remaining part flows into the termination kettle;

[0012] A rectification tower connected to the flash tank. The gas flowing out from the top of the flash tank is introduced into the rectification tower for rectification and recovery.

[0013] The present invention also provides a method for recycling ethylene polymerization reaction catalyst, comprising the following steps:

[0014] (1) Inject ethylene and catalyst into the reactor for reaction to form a reaction solution; wherein the catalyst can be pre-dissolved in solvents such as n-hexane, cyclohexane, methylcyclohexane, etc. and then injected into the reactor;

[0015] (2) After the reaction is completed, the reaction solution is injected into a flash tank for flashing, and the flash vapor phase is discharged as a semi-finished product into a distillation column for distillation recovery;

[0016] (3) The catalyst concentrate remaining at the bottom of the flash tank, a part of it is refluxed into the reactor for continuous reaction, and the remaining part flows into a termination kettle;

[0017] (4) A terminating agent is added to the termination kettle to inactivate the catalyst.

[0018] Preferably, in step (1), the reaction time is 2.5 h and the reaction temperature is 53 - 55 °C.

[0019] Preferably, in step (1), the catalyst is composed of tetrabutyl titanate and triethylaluminum.

[0020] Preferably, in step (2), the flash vapor phase includes ethylene, butene and a small amount of high-boiling impurities.

[0021] Preferably, in step (2), the flash pressure is 1 MPa and the flash temperature is 30 °C.

[0022] Preferably, in step (3), 80% of the total mass of the catalyst concentrate is refluxed into the reactor, and 20% flows into the termination kettle.

[0023] Preferably, in step (4), the terminating agent is selected from methanol, ethanol, isopropanol, n-octanol, isooctanol, n-octylamine and isooctylamine.

[0024] The present invention provides an ethylene oligomerization catalyst recovery device and method, which have the following beneficial effects compared with the prior art:

[0025] 1. The recovery and reuse of the catalyst are realized, and the amount of catalyst used is reduced.

[0026] 2. The amount of terminating agent used can be reduced, the generation of harmful waste can be significantly reduced, and low-cost methanol, ethanol, isopropanol and other catalyst deactivators are used to replace expensive long-chain alcohols and amines, reducing the production cost.

[0027] 3. Since there are very few heavier impurities in the flash gas stream except for ethylene and α-olefins, the downstream separation process will become easier and less energy is required.

[0028] 4. Since the product and the catalyst are separated by flashing in advance, the energy consumption for later purification and the product pollution caused by waste catalyst can be reduced. Description of the Drawings

[0029] The accompanying drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0030] Figure 1 is a schematic structural diagram of the recovery device of the present invention;

[0031] Figure 2 is a schematic structural diagram of the recovery device in the prior art. Detailed Embodiments

[0032] The following embodiments are used to illustrate in detail the implementation manners of the present application, so as to fully understand how the present application uses technical means to solve technical problems and achieve the implementation process of technical effects and implement accordingly.

[0033] Embodiment 1

[0034] An ethylene oligomerization catalyst recovery device includes a reactor, an ethylene feed port and a catalyst feed port are arranged at the bottom of the reactor; a flash tank communicated with the reactor to separate the catalyst; a termination kettle communicated with the flash tank, and a part of the catalyst flowing out of the flash tank flows back into the reactor, and the remaining part flows into the termination kettle. A rectification column communicated with the flash tank, and the gas phase flowing out from the top of the flash tank is introduced into the rectification column for rectification recovery.

[0035] Embodiment 2

[0036] An ethylene polymerization reaction catalyst recovery method uses the recovery device in claim 1 and includes the following steps:

[0037] (1) Inject ethylene and catalyst into the reactor for reaction to form a reaction solution;

[0038] (2) After the reaction is completed, inject the reaction solution into the flash tank for flash evaporation. The flash gas phase is discharged to the rectification column as a semi-finished product to recover ethylene and produce purified α-olefins; the flash gas phase includes ethylene, butene and a small amount of high-boiling impurities;

[0039] (3) 80% of the total mass of the catalyst concentrate remaining at the bottom of the flash tank flows back into the reactor for continuous reaction, and 20% flows into the termination kettle;

[0040] (4) Add a terminator to the termination kettle for catalyst inactivation treatment, and the fluid in the termination kettle can be introduced into the rectification column to separate out products of C 4 and above.

[0041] Reference Figure 1 , the specific parameters of the above ethylene polymerization reaction catalyst recovery method are as follows:

[0042]

[0043] Comparative Example 1

[0044] A method for recovering a catalyst for ethylene polymerization reaction, comprising the following steps:

[0045] (1) Inject ethylene and the catalyst into a reactor for reaction to form a reaction solution;

[0046] (2) After the reaction is completed, inject the reaction solution into a termination kettle;

[0047] (3) Add a terminator into the termination kettle to inactivate the catalyst.

[0048] Reference Figure 2 , the specific parameters of the above method for recovering a catalyst for ethylene polymerization reaction are as follows:

[0049]

[0050] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An ethylene oligomerization catalyst recovery device, characterized in that: It comprises a reactor, wherein an ethylene feed port and a catalyst feed port are arranged at the bottom of the reactor; a flash tank connected to the reactor to separate the catalyst; A termination kettle is connected to the flash tank, and part of the catalyst flowing out from the bottom of the flash tank is refluxed into the reactor, and the remaining part flows into the termination kettle; The distillation tower is connected to the flash tank, and the gas phase flowing out from the top of the flash tank is passed into the distillation tower for distillation recovery.

2. A method for recovering an ethylene oligomerization catalyst, using the recovery device described in claim 1, characterized in that: The following steps are involved: (1) injecting ethylene and a catalyst into a reactor to react and form a reaction liquid; (2) After the reaction is completed, the reaction liquid is injected into a flash tank for flash evaporation, and the flash gas phase is discharged as a semi-finished product into a distillation tower for distillation recovery; (3) A portion of the catalyst concentrate remaining at the bottom of the flash tank is refluxed into the reactor to continue the reaction, and the remaining portion flows into the termination kettle; (4) Add terminator into the termination kettle to deactivate the catalyst.

3. The method for recovering ethylene oligomerization catalyst according to claim 2, wherein: In step (1), the reaction time is 2.5 h and the reaction temperature is 53-55°C.

4. The method for recovering ethylene oligomerization catalyst according to claim 2, wherein: In step (1), the catalyst consists of tetrabutyl titanate and triethylaluminum.

5. The method for recovering ethylene oligomerization catalyst according to claim 2, characterized in that: In step (2), the flash gas phase includes ethylene, butene and a small amount of high boiling point impurities.

6. The method for recovering ethylene oligomerization catalyst according to claim 2, characterized in that: In step (2), the flash evaporation pressure is 1 MPa and the flash evaporation temperature is 30°C.

7. The method for recovering ethylene oligomerization catalyst according to claim 2, characterized in that: In step (3), 80% of the total mass of the catalyst concentrate is refluxed into the reactor, and 20% flows into the termination kettle.

8. The method for recovering ethylene oligomerization catalyst according to claim 2, characterized in that: In step (4), the terminator is selected from methanol, ethanol, isopropanol, n-octanol, isooctyl alcohol, n-octylamine and isooctylamine.

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