Method and device for preparing 4-methyl-1-pentene

Abstract

The invention relates to the technical field of organic synthesis, in particular to a method and device for preparing 4-methyl-1-pentene, and the method comprises the following steps: (1) pretreating a raw material containing propylene and an inert substance, and carrying out heat exchange on the obtained refined raw material to obtain a heat-exchanged raw material; (2) carrying out dimerization reaction on the raw material subjected to heat exchange and a catalyst in the presence of inert gas, wherein the obtained reaction product is divided into a part of reaction product and a residual part of reaction product; (3) cooling the part of the reaction product as a heat exchange medium, and carrying out heat exchange with the refined raw material to obtain a heat-exchanged product; (4) separating a mixed material of the rest reaction product and the product after heat exchange to obtain a light component and a heavy component; and carrying out rectification on the heavy component to obtain the 4-methyl-1-pentene. According to the method, by controlling the reaction temperature rise, the stable reaction temperature and the uniform reaction process are ensured, and the raw material conversion rate and the product selectivity are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for preparing 4-methyl-1-pentene and a device for preparing 4-methyl-1-pentene. Background Art

[0002] 4-Methyl-1-pentene is an important polymerization monomer that can be used as a comonomer of ethylene and propylene. It can improve the transparency and environmental stress resistance of polyolefins. It can also be homopolymerized into thermoplastics to prepare poly-4-methyl-1-pentene (PMP) with excellent performance. The preparation of 4-methyl-1-pentene mainly includes three main synthetic routes: halogenated hydrocarbon coupling, pentanol dehydration and propylene dimerization. Among them, the process route of preparing 4-methyl-1-pentene by propylene dimerization using alkali metal as catalyst has good economic efficiency and has been industrialized abroad.

[0003] The preparation of 4-methyl-1-pentene by propylene dimerization is an exothermic reaction with a large amount of heat released, and the conversion rate and selectivity are sensitive to the reaction temperature. Therefore, it is necessary to remove the heat released by the reaction in time to maintain a stable reaction temperature, reduce the probability of side reactions, and improve the selectivity of the target product. In order to facilitate heat removal or heat supply during the reaction, a tubular reactor is usually used to remove heat or supply heat to achieve heat exchange. Therefore, a fixed bed reactor with multiple reaction tubes is widely used in the petrochemical industry. Loading the catalyst into this reactor has become a more prominent problem. Due to the large number of tubulars, it is difficult to ensure that each one is loaded evenly. On the one hand, it is inconvenient to detect the uniformity of the loading, and it is impossible to ensure that the loading amount of each reaction tube is the same. Uneven loading will result in different resistances of each reaction tube and uneven material distribution during the formal reaction, thereby affecting the normal progress of the reaction and the service life of the catalyst.

[0004] Shell-and-tube reactors are generally loaded with catalyst particles, which exist in the reactor tubes in the form of natural accumulation to form a catalyst bed. When the bed is operated in the reactor by bottom feeding or reacting from bottom to top, it will become loose due to the impact force, and the catalyst particles in many tubes will flow out of the reactor tubes along with the fluid, resulting in catalyst loss.

[0005] CN115193463A discloses a method for synthesizing 4-methyl-1-pentene by dimerization of propylene, wherein a catalyst loaded with sodium and / or potassium on a carrier is used, a fixed bed gas phase reaction is adopted, the raw material is vaporized and then enters a fixed bed reactor for reaction, the reaction product enters a gas-liquid separator after depressurization, and a liquid phase containing 4-methyl-1-pentene is obtained. This method still cannot meet the following requirements: controlling the temperature rise of the reaction, uniform loading of the catalyst, and preventing the catalyst from loosening and losing during the reaction, thereby ensuring that the bed temperature of the propylene dimerization reactor is stable, the reaction materials are uniform, and thus the normal progress of the reaction and the service life of the catalyst are not affected; in addition, due to the harsh reaction conditions and great technical difficulty, this method is difficult to realize industrialization. Summary of the invention

[0006] The purpose of the present invention is to overcome the above technical problems. The present invention provides a method for preparing 4-methyl-1-pentene and a device for preparing 4-methyl-1-pentene. The method controls the reaction temperature rise to ensure the stability of the reaction temperature and the uniformity of the reaction process, thereby improving the raw material conversion rate and product selectivity; at the same time, the method simplifies the process and is convenient for industrial production.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing 4-methyl-1-pentene, the method comprising:

[0008] (1) pretreating a raw material containing propylene and an inert substance, and subjecting the obtained refined raw material to heat exchange to obtain a heat-exchanged raw material;

[0009] (2) subjecting the raw materials after heat exchange and the catalyst to a dimerization reaction in the presence of an inert gas, and dividing the obtained reaction products into a partial reaction product and a remaining partial reaction product;

[0010] (3) using the cooled partial reaction product as a heat exchange medium to perform heat exchange with the refined raw material to obtain a heat exchange product;

[0011] (4) separating the mixture of the remaining reaction product and the product after heat exchange to obtain a light component and a heavy component; and distilling the heavy component to obtain 4-methyl-1-pentene.

[0012] The second aspect of the present invention provides a device for preparing 4-methyl-1-pentene, the device comprising a raw material tank, a pretreatment unit, a reaction unit, a separation unit and a distillation unit connected in sequence, the reaction unit comprising a fixed bed reactor, and a heat exchange unit connected to the side wall of the fixed bed reactor;

[0013] The pretreatment unit is used to pretreat the raw material containing propylene and inerts to obtain a refined raw material;

[0014] The fixed bed reactor comprises a shell provided with at least one wound reaction tube. The refined raw material entering the wound reaction tube is subjected to heat exchange with the heat exchange medium of the shell side, and then contacts with the catalyst loaded in the wound reaction tube in the presence of an inert gas and undergoes a dimerization reaction. The obtained reaction product is divided into two streams. Part of the reaction product is cooled by the heat exchange unit and used as the heat exchange medium. The remaining reaction product and the mixture of the product after heat exchange enter the separation unit, and the light component is obtained at the top of the tower. The heavy component obtained at the bottom of the tower enters the distillation unit, and 4-methyl-1-pentene is obtained at the top of the tower, and heavy impurities are obtained at the bottom of the tower.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The method provided by the present invention controls the dimerization reaction temperature by adding an inert substance to the raw material and using part of the reaction product as a heat exchange medium after cooling to exchange heat with the refined raw material, thereby stabilizing the dimerization reaction temperature and extending the service life of the catalyst, thereby improving the propylene conversion rate in the raw material and the selectivity of the target product; in particular, by adjusting the circulation ratio of the reaction materials, it is more conducive to improving the selectivity of the target product;

[0017] (2) The device provided by the present invention, by limiting the fixed bed reactor to have a wound reaction tube, allows the wound reaction tube to be loaded with catalyst evenly, thereby preventing the catalyst from loosening and losing during feeding and reaction in the tubular fixed bed reactor. Under the premise of ensuring the stability of the catalyst bed temperature, the service life of the catalyst is extended, thereby meeting the process requirements of long-term operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a device for preparing 4-methyl-1-pentene provided by the present invention;

[0019] Figure 2 It is a structural schematic diagram of a reaction unit provided by the present invention;

[0020] Figure 3 is a schematic structural diagram of another reaction unit provided by the present invention;

[0021] Figure 4 This is a schematic structural diagram of a reaction unit provided in Comparative Example 1.

[0022] Description of Reference Numerals

[0023] I, raw material tank; II, pretreatment unit; III, fixed bed reactor; IV, heat exchange unit; V, separation unit; VI, distillation unit; VII, catalyst loading unit; T1, first thermometer; T2, second thermometer;

[0024] 1. Shell; 2. Upper end cap; 3. Lower end cap; 4. Material outlet; 5. Logistics inlet; 6. Winding reaction tube; 7-1. First support member; 7-2. Second support member; 8. Joint; 9. Inert gas inlet; 11. Tube array; 12. Catalyst inlet; 13. Inert gas interface; 14. External loading container; 15. External loading connecting pipe; 16. Heat exchange medium outlet; 17. Heat exchange medium inlet;

[0025] 01. Propylene; 02. Inert matter; 03. Raw materials; 04. Refined raw materials; 05-i. Partial reaction products; 06. Heat exchange medium; 07. Mixed materials; 08. Light components; 09. Heavy components; 010. 4-methyl-1-pentene; 011. Heavy impurities. DETAILED DESCRIPTION

[0026] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0027] In the present invention, unless otherwise specified, the “top” of a container is used to indicate the position of 0-10% of the container from top to bottom; the “upper part” of a container is used to indicate the position of 10-40% of the container from top to bottom; the “middle part” of a container is used to indicate the position of 40-60% of the container from top to bottom; the “lower part” of a container is used to indicate the position of 60-90% of the container from top to bottom; and the “bottom” of a container is used to indicate the position of 90-100% of the container from top to bottom.

[0028] In the present invention, unless otherwise specified, "first" and "second" do not indicate a sequence or limit the materials or steps, but are only used to distinguish or indicate that they are not the same material or step. For example, "first" and "second" in "first supporting member" and "second supporting member" are only used to distinguish or indicate that they are not the same supporting member.

[0029] A first aspect of the present invention provides a method for preparing 4-methyl-1-pentene, the method comprising:

[0030] (1) pretreating a raw material containing propylene and an inert substance, and subjecting the obtained refined raw material to heat exchange to obtain a heat-exchanged raw material;

[0031] (2) subjecting the raw materials after heat exchange and the catalyst to a dimerization reaction in the presence of an inert gas, and dividing the obtained reaction products into a partial reaction product and a remaining partial reaction product;

[0032] (3) using the cooled partial reaction product as a heat exchange medium to perform heat exchange with the refined raw material to obtain a heat exchange product;

[0033] (4) separating the mixture of the remaining reaction product and the product after heat exchange to obtain a light component and a heavy component; and distilling the heavy component to obtain 4-methyl-1-pentene.

[0034] In some embodiments of the present invention, preferably, in step (1), the volume flow ratio of propylene to inert in the raw material is 1:0.01-50, for example, 1:0.01, 1:0.04, 1:0.1, 1:0.5, 1:1, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, and any value in the range of any two values, preferably 1:0.04-40. Meeting the above volume flow ratio range is conducive to improving the conversion rate of the raw material.

[0035] In some embodiments of the present invention, preferably, the inert substance is selected from C2-C5 alkanes and / or C3-C5 cycloalkanes, preferably C2-C5 alkanes, and more preferably propane.

[0036] In the present invention, preferably, the raw material consists of propylene and an inert substance, and the volume flow ratio of propylene to the inert substance is 1:0.01-50, preferably 1:0.04-40.

[0037] In some embodiments of the present invention, preferably, the pretreatment process includes: dehydrating and deoxygenating the raw material to obtain the refined raw material; further preferably, the water content in the refined raw material is ≤10ppm, preferably ≤3ppm; the O2 content is ≤10ppm, preferably ≤3ppm.

[0038] In the present invention, the heat exchange process includes: exchanging heat between the refined raw material and the heat exchange medium to obtain a heat-exchanged raw material converted from the refined raw material and a heat-exchanged product converted from the heat exchange medium.

[0039] In some embodiments of the present invention, preferably, the temperature of the raw material after heat exchange is 50-300°C, preferably 100-200°C.

[0040] In some embodiments of the present invention, preferably, in step (2), the volume flow ratio of the raw material and the catalyst after heat exchange is 0.1-10:1, for example, 0.1:1, 0.5:1, 1:1, 2:1, 5:1, 10:1, and any value in the range consisting of any two values, preferably 0.5-5:1.

[0041] In some embodiments of the present invention, preferably, the water content in the inert gas is ≤10ppm, preferably ≤3ppm; the O2 content is ≤10ppm, preferably ≤3ppm. In the present invention, the inert gas includes but is not limited to nitrogen, helium, argon, neon, etc., preferably nitrogen.

[0042] In some embodiments of the present invention, preferably, the dimerization reaction conditions include: a temperature of 50-300° C., preferably 100-200° C.; and a pressure of 4-20 MPa, preferably 6-12 MPa. In the present invention, pressure refers to gauge pressure.

[0043] In some embodiments of the present invention, it is further preferred that the temperature rise of the dimerization reaction is ≤60° C., preferably ≤30° C. In the present invention, the temperature rise of the dimerization reaction refers to the temperature difference between the mixed material and the raw material after heat exchange, that is, the difference between the logistics temperature through the material inlet and the logistics temperature through the material outlet.

[0044] In the present invention, the reaction product is divided into two streams, namely, a partial reaction product and a remaining partial reaction product. Preferably, in step (2), the mass flow ratio of the partial reaction product to the remaining partial reaction product is 0.1-50:1, for example, 0.1:1, 0.2:1, 0.5:1, 1:1, 2:1, 5:1, 8:1, 10:1, 15:1, 20:1, 30:1, 50:1, and any value in the range of any two values, preferably 0.2-20:1. Meeting the above mass flow ratio range is conducive to regulating the temperature rise of the dimerization reaction, controlling the temperature difference of the dimerization reaction, and thereby improving the propylene conversion rate and the selectivity of the target product.

[0045] In some embodiments of the present invention, preferably, the catalyst is selected from active metal catalysts, and the active metal in the active metal catalyst is selected from at least one of Na, K, Li, Mg, Al and Fe, preferably selected from Na and / or K.

[0046] In some embodiments of the present invention, preferably, the active metal content in the active metal catalyst is 0.1-20wt%, preferably 0.5-10wt%. In the present invention, the carrier of the active metal catalyst is selected from at least one of alkali metal salts, molecular sieves and activated carbon, preferably alkali metal salts, wherein the alkali metal salts include but are not limited to potassium carbonate and / or sodium carbonate.

[0047] In the present invention, the source of the active metal catalyst has a wide selection range, and can be obtained from commercial sources or homemade, for example, based on the method disclosed in CN115193462A.

[0048] In the present invention, in step (3), the part of the reaction product is cooled and used as a heat exchange medium to perform the heat exchange with the refined raw material, so that the cooled product (i.e., the heat exchange medium) is converted into a heat exchanged product, and the heat exchanged raw material converted from the refined raw material is obtained.

[0049] In some embodiments of the present invention, preferably, in step (3), the temperature difference between the reaction product and the heat exchange medium is 1-50° C., for example, 1° C., 10° C., 15° C., 20° C., 25° C., 30° C., 50° C., and any value in the range of any two values, preferably 10-30° C. The temperature within the above range is conducive to controlling the reaction temperature, regulating the temperature rise of the dimerization reaction, and thus improving the propylene conversion rate and 4-methyl-1-pentene selectivity.

[0050] In some embodiments of the present invention, preferably, in step (3), the temperature of the heat exchange medium is 30-280°C, for example, 30°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 250°C, 280°C, and any value in the range consisting of any two values, preferably 80-180°C.

[0051] In the present invention, the separation is intended to separate the mixture of the remaining product and the product after heat exchange to obtain a light component containing unreacted propylene and inerts, and a heavy component containing 4-methyl-1-pentene and by-products. Preferably, in step (4), the separation conditions include: a tower top temperature of 30-90°C, preferably 40-70°C; a tower top pressure of 1-3MPa, preferably 1.5-2MPa.

[0052] In the present invention, the distillation is to distill the heavy component to obtain the target product. Preferably, the distillation conditions include: the tower top temperature is 60-150°C, preferably 80-120°C; the tower top pressure is 0.2-0.8MPa, preferably 0.2-0.5MPa.

[0053] In some embodiments of the present invention, preferably, the method further comprises: returning the light component and mixing it into the raw material.

[0054] The second aspect of the present invention provides a schematic diagram of the structure of a device for preparing 4-methyl-1-pentene. Figure 1-3 As shown by Figure 1-3 It can be seen that the device includes a raw material tank I, a pretreatment unit II, a reaction unit, a separation unit V and a distillation unit VI connected in sequence, the reaction unit includes a fixed bed reactor III, and a heat exchange unit IV connected to the side wall of the fixed bed reactor III;

[0055] The pretreatment unit II is used to pretreat the raw material 03 containing propylene 01 and inert matter 02 to obtain a refined raw material 04;

[0056] The fixed bed reactor III comprises a shell 1 provided with at least one wound reaction tube 6. The refined raw material 04 entering the wound reaction tube 6 is heat exchanged with the heat exchange medium 06 of the shell side, and then contacts with the catalyst loaded in the wound reaction tube 6 in the presence of an inert gas and undergoes a dimerization reaction. The obtained reaction product is divided into two streams. Part of the reaction product 05-i is cooled by the heat exchange unit IV and used as the heat exchange medium 06. The remaining reaction product and the mixture 07 of the product after heat exchange enters the separation unit V, and the light component 08 is obtained at the top of the tower. The heavy component 09 obtained at the bottom of the tower enters the distillation unit VI, and 4-methyl-1-pentene 010 is obtained at the top of the tower, and the heavy impurity 011 is obtained at the bottom of the tower.

[0057] In the present invention, unless otherwise specified, the raw material tank I is used to store raw material 03 containing propylene 01 and inert material 02; the heat exchange unit IV is connected to the side wall of the shell 1 through a pipeline to regulate the reaction temperature in the wound reaction tube; the shell side refers to the area formed by the inner wall of the shell and the outer wall of the wound reaction tube.

[0058] In some embodiments of the present invention, preferably, Figure 2-3 As shown, the winding reaction tube 6 is selected from a serpentine reaction tube and a disc reaction tube.

[0059] In some embodiments of the present invention, preferably, a plurality of the wound reaction tubes 6 are arranged in parallel in the shell 1; further preferably, the number of the wound reaction tubes 6 is selected from 1-200, preferably 1-20.

[0060] In the present invention, when the winding reaction tube is selected from a serpentine reaction tube, the number of the winding reaction tube is preferably one; when the winding reaction tube is selected from a disc-shaped reaction tube, the number of the winding reaction tube is preferably multiple. This arrangement not only ensures the stability of the reactor bed temperature, but also helps to improve the reaction efficiency.

[0061] In some embodiments of the present invention, preferably, Figure 2-3 As shown, the inner diameter ratio of the wound reaction tube 6 and the shell 1 is 0.00125-0.4:1, for example, 0.00125:1, 0.005:1, 0.01:1, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.4:1, and any value in the range consisting of any two numerical values; the height ratio of the wound reaction tube 6 and the shell 1 is 0.7-1:1, for example, 0.7:1, 0.8:1, 0.9:1, 1:1, and any value in the range consisting of any two numerical values.

[0062] In some embodiments of the present invention, it is further preferred that Figure 2-3 As shown, the inner diameter of the wound reaction tube 6 is 10-200 mm, preferably 15-150 mm.

[0063] In some embodiments of the present invention, preferably, Figure 2-3 As shown, a first supporting component 7 - 1 and a second supporting component 7 - 2 are further provided in the shell 1 for fixing the wound reaction tube 6 .

[0064] In some embodiments of the present invention, preferably, Figure 2 As shown, when the winding reaction tube 6 is selected from a serpentine reaction tube, the serpentine reaction tube is composed of a series of tubes, and the tubes are connected by a joint 8, that is, the tubes are connected by the joint to form a complete winding reaction tube.

[0065] In some embodiments of the present invention, preferably, Figure 2 As shown, the number of the tube arrays is 1-50, preferably 1-10.

[0066] In some embodiments of the present invention, preferably, Figure 2 As shown, the joint 8 includes but is not limited to a threaded joint, a ferrule joint, a welded elbow joint, and a flange joint.

[0067] In some embodiments of the present invention, preferably, Figure 3 As shown, when the wound reaction tube 6 is selected from a disc-shaped reaction tube, the number of the disc-shaped reaction tubes is 1-50, preferably 1-15; the spacing between two adjacent coils is 12.5-300 mm, preferably 20-225 mm. In the present invention, the spacing between two adjacent coils refers to the vertical distance between the centers of the two adjacent coils.

[0068] In the present invention, when there are multiple disc-shaped reaction tubes, the multiple disc-shaped reaction tubes are connected in parallel and symmetrically arranged in the shell, especially when the amount of catalyst loaded in each disc-shaped reaction tube and the amount of reaction raw materials entering are the same, then it is assumed that the temperature rise of the multiple disc-shaped reaction tubes is the same.

[0069] In some embodiments of the present invention, preferably, Figure 2-3 As shown, the upper head 2 of the shell 1 is provided with a material inlet 5, and the lower head 3 is provided with a material outlet 4 and an inert gas inlet 9.

[0070] In some embodiments of the present invention, preferably, Figure 2-3As shown, a heat exchange medium outlet 16 and a heat exchange medium inlet 17 are provided on the connecting pipe between the side wall of the shell 1 and the heat exchange unit IV, and the heat exchange medium outlet 16 is arranged below the heat exchange medium inlet 17, so as to allow part of the reaction product 05-i to enter the heat exchange unit IV through the heat exchange medium outlet 16 for cooling, and then the obtained heat exchange medium 06 enters the shell side through the heat exchange medium inlet 17.

[0071] In some embodiments of the present invention, preferably, Figure 2-3 As shown, a first thermometer T1 and a second thermometer T2 are respectively provided on the pipeline connecting the material inlet 5 and the material outlet 4 .

[0072] In some embodiments of the present invention, preferably, a flow controller is provided on the pipeline connected to the material inlet 5; or, a distributor is provided in the shell 1, and the distributor is provided above the winding reactor 6 for distributing the refined raw material 04.

[0073] In some embodiments of the present invention, preferably, Figure 2-3 As shown, the reaction unit also includes: a catalyst loading unit VII connected to the upper head 2 of the shell 1, the catalyst loading unit VII includes an external loading container 14, and an inert gas interface 13 and a catalyst inlet 12 arranged on the external loading container 14, which are used to load the catalyst into the wound reaction tube 6 under the transport of inert gas.

[0074] In some embodiments of the present invention, preferably, during the loading process of the catalyst, the flow rate of the inert gas is 1-100 m / s, for example, 1 m / s, 5 m / s, 10 m / s, 15 m / s, 20 m / s, 25 m / s, 30 m / s, 50 m / s, 80 m / s, 100 m / s, and any value in the range of any two values, preferably 5-30 m / s. By controlling the flow rate of the inert gas, the catalyst in the wound reaction tube is loaded without oxygen, which ensures uniform loading on the one hand, and avoids the catalyst from being damaged by contact with oxygen during loading.

[0075] In some embodiments of the present invention, preferably, Figure 2-3 As shown, the external loading container 14 and the fixed bed reactor III are connected via an external loading connecting pipe 15 .

[0076] In some embodiments of the present invention, preferably, Figure 1 As shown, the top of the separation unit V is connected to the pretreatment unit II for returning the light component 08 and mixing it into the raw material 03.

[0077] According to a particularly preferred embodiment of the present invention, a method for preparing 4-methyl-1-pentene comprises:

[0078] (1) pretreating a raw material containing propylene and an inert substance, and subjecting the obtained refined raw material to heat exchange to obtain a heat-exchanged raw material;

[0079] (2) subjecting the raw materials after heat exchange and the catalyst to a dimerization reaction in the presence of an inert gas, and dividing the obtained reaction products into a partial reaction product and a remaining partial reaction product;

[0080] (3) using the cooled partial reaction product as a heat exchange medium to perform heat exchange with the refined raw material to obtain a heat exchange product;

[0081] (4) separating the mixture of the remaining reaction product and the product after heat exchange to obtain a light component and a heavy component; and distilling the heavy component to obtain 4-methyl-1-pentene;

[0082] The volume flow ratio of propylene and inert in the raw material is 1:0.04-40; the volume flow ratio of the raw material and the catalyst after the heat exchange is 0.5-5:1;

[0083] The mass flow ratio of the partial reaction product to the remaining partial reaction product is 0.2-20:1;

[0084] The temperature difference between the reaction product and the heat exchange medium is 10-30°C.

[0085] The present invention will be described in detail below through examples.

[0086] The active metal catalyst is prepared based on the method of CN115193462A. The active metal in the active metal catalyst is selected from Na and K, and the mass ratio of Na to K is 3:2. The total loading amount is 8wt%, and the carrier is selected from potassium carbonate.

[0087] The temperature rise of the dimerization reaction = the second thermometer T2 - the first thermometer T1.

[0088] Example 1

[0089] The device for preparing 4-methyl-1-pentene is as follows Figure 1-2 As shown, the device includes a raw material tank I, a pretreatment unit II, a fixed bed reactor III, a heat exchange unit IV, a separation unit V and a distillation unit VI, and a catalyst loading unit VII which are connected in sequence;

[0090] The fixed bed reactor III comprises a shell 1 provided with a winding reaction tube 6, a heat exchange medium inlet 17 and a heat exchange medium outlet 16 provided on the side wall of the shell 1, and connected to the heat exchange unit IV through a pipeline; the upper head 2 of the shell 1 is provided with a material inlet 5, and a catalyst loading unit VII connected through an external loading connection pipeline 15; the lower head 3 of the shell 1 is provided with a material outlet 4 and an inert gas inlet 9; the catalyst loading unit VII comprises an external loading container 14, an inert gas interface 13 and a catalyst inlet 12; the above-mentioned winding reaction tube is composed of serially connected tubes, and the tubes are connected by a joint 8, and the number of the tubes is 2; the pipelines connecting the material inlet 5 and the material outlet 4 are respectively provided with a first thermometer T1 and a second thermometer T2;

[0091] Among them, the height of the fixed bed reactor III is 6500 mm and the inner diameter is 2000 mm; the height of the wound reaction tube is 5000 mm and the inner diameter is 20 mm.

[0092] The method for preparing 4-methyl-1-pentene is carried out in the above-mentioned device, and the method comprises:

[0093] (1) placing a fixed bed reactor in a nitrogen atmosphere, and loading the above catalyst into a coiled reaction tube under nitrogen (water content of 3 ppm, O2 content of 3 ppm, flow rate of 20 m / s);

[0094] Propylene and inert (propane) were mixed at a volume flow ratio of 1:10, and the obtained raw material was subjected to dehydration and deoxygenation treatment to obtain a refined raw material (water content of 2 ppm; O2 content of 2 ppm). After heat exchange, a heat-exchanged raw material with a temperature of 155° C. was obtained;

[0095] (2) dimerizing the raw materials after heat exchange with the active metal catalyst loaded in the wound reaction tube in the presence of an inert gas (temperature of 155° C., pressure of 7 MPa), and the obtained reaction products are divided into a partial reaction product with a mass flow ratio of 10:1 and a remaining partial reaction product;

[0096] The volume flow ratio of the raw material and the catalyst after the above heat exchange is 1.5:1;

[0097] (3) using the partial reaction product cooled to 135° C. as a heat exchange medium to exchange heat with the refined raw material to obtain a heat exchange product;

[0098] (4) separating the mixture of the remaining reaction product and the product after heat exchange to obtain a light component and a heavy component; and distilling the heavy component to obtain 4-methyl-1-pentene.

[0099] The dimerization reaction was carried out for 2 hours, the temperature rise of the dimerization reaction was 20° C. The mixture was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 88%, and the selectivity of 4-methyl-1-pentene was 83%.

[0100] Example 2

[0101] The apparatus according to Example 1 is different in that the reaction unit is as follows Figure 3 As shown, the fixed bed reactor III includes four disc-shaped reaction tubes arranged in parallel, and the four disc-shaped reaction tubes are symmetrically distributed in the shell;

[0102] Among them, the height of the fixed bed reactor III is 6500 mm and the inner diameter is 2000 mm; the height of the wound reaction tube is 6500 mm and the inner diameter is 20 mm.

[0103] According to the method of Example 1, the difference is that the method is carried out in the above-mentioned device,

[0104] In step (2), the volume flow ratio of the raw material and the catalyst after the heat exchange is replaced with 2:1;

[0105] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 23° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 86%, and the selectivity of 4-methyl-1-pentene was 80%.

[0106] Example 3

[0107] According to the device of Example 1,

[0108] According to the method of Example 1, the difference is that in step (1),

[0109] The volume flow ratio of propylene and inerts in the raw material is replaced with 1:0.01, and the other conditions remain the same.

[0110] The dimerization reaction was carried out for 2 hours, the temperature rise of the dimerization reaction was 25° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 85%, and the selectivity of 4-methyl-1-pentene was 79%.

[0111] Example 4

[0112] According to the device of Example 1,

[0113] The method of Example 1 is followed, except that in step (2),

[0114] The volume flow ratio of the raw material and the catalyst after the heat exchange is 0.3:1, and the other conditions are the same.

[0115] The dimerization reaction was carried out for 2 hours, the temperature rise of the dimerization reaction was 40° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 80%, and the selectivity of 4-methyl-1-pentene was 70%.

[0116] Example 5

[0117] According to the device of Example 1,

[0118] The method of Example 1 is followed, except that in step (2),

[0119] The mass flow ratio of the partial reaction product to the remaining partial reaction product was changed to 0.15:1, and the other conditions were the same.

[0120] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 42° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 79%, and the selectivity of 4-methyl-1-pentene was 71%.

[0121] Example 6

[0122] According to the device of Example 1,

[0123] The method of Example 1 is followed, except that in step (3),

[0124] The above reaction product was cooled to 150°C, and the other conditions were the same.

[0125] The dimerization reaction was carried out for 2 hours, the temperature rise of the dimerization reaction was 45° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 81%, and the selectivity of 4-methyl-1-pentene was 70%.

[0126] Example 7

[0127] According to the device of Example 1,

[0128] According to the method of Example 1, the difference is that in step (1),

[0129] Replace the nitrogen flow rate with 3m / s, and keep the other conditions the same.

[0130] The dimerization reaction was carried out for 2 hours, the temperature rise of the dimerization reaction was 40° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 75%, and the selectivity of 4-methyl-1-pentene was 68%.

[0131] Comparative Example 1

[0132] The apparatus according to Example 1 is different in that the reaction unit is as follows Figure 4As shown, the reaction unit does not contain a catalyst loading unit, and the fixed bed reactor III is selected from a tube-in-tube fixed bed reactor, and the number of tubes is 3200; the first thermometer T1 and the second thermometer T2 are respectively provided on the pipeline connecting the material inlet 5 and the material outlet 4;

[0133] Among them, the height of the fixed bed reactor III is 6500mm and the inner diameter is 2000mm; the height of the tube array is 5000mm and the inner diameter is 20mm.

[0134] According to the method of Example 1, the difference is that the method is carried out in the above-mentioned device,

[0135] (1) Propylene and an inert substance (propane) are mixed at a volume flow ratio of 1:10, and the obtained raw material is subjected to dehydration and deoxygenation treatment to obtain a refined raw material (water content of 2 ppm; O2 content of 2 ppm), and after heat exchange, a heat-exchanged raw material having a temperature of 155° C. is obtained;

[0136] (2) dimerizing the raw materials after heat exchange with the active metal catalyst loaded in the tubes in the presence of an inert gas (temperature of 155° C., pressure of 7 MPa), and the obtained reaction products are divided into a partial reaction product with a mass flow ratio of 10:1 and a remaining partial reaction product;

[0137] The volume flow ratio of the raw material and the catalyst after the above heat exchange is 1.5:1;

[0138] (3) using the partial reaction product cooled to 135° C. as a heat exchange medium to exchange heat with the refined raw material to obtain a heat exchange product;

[0139] (4) separating the mixture of the remaining reaction product and the product after heat exchange to obtain a light component and a heavy component; and distilling the heavy component to obtain 4-methyl-1-pentene.

[0140] The dimerization reaction was carried out for 2 hours, the temperature rise of the dimerization reaction was 60° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 60%, and the selectivity of 4-methyl-1-pentene was 70%.

[0141] Comparative Example 2

[0142] According to the device of embodiment 1;

[0143] According to the method of Example 1, the difference is that in step (1),

[0144] No inert material (propane) was added, and other conditions were the same.

[0145] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 65° C. The mixed material was fed into an online chromatograph for composition analysis, and the propylene conversion rate was 60%, and the selectivity of 4-methyl-1-pentene was 65%.

[0146] Compared with Comparative Examples 1-2, Examples 1-7 use the method provided by the present invention to prepare 4-methyl-1-pentene, and by regulating the reaction temperature, the propylene conversion rate and the selectivity of the target product are improved, especially by regulating the circulation ratio of the reaction materials, the temperature difference between the dimerization reaction and the heat exchange medium, the yield of the target product is further improved.

[0147] Compared with Example 1, it is difficult to ensure uniform catalyst loading in Comparative Example 1 due to the large number of tubes used. Uneven loading will result in different resistances in each reaction tube, resulting in uneven material distribution during the formal reaction, thereby affecting the normal and stable progress of the reaction; at the same time, the catalyst loaded in the tube-type reactor will become loose due to the impact force, and the catalyst particles in the numerous tubes will flow out of the reactor tubes along with the fluid, resulting in catalyst loss, which will also affect the stable progress of the reaction.

[0148] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing 4-methyl-1-pentene, characterized in that: The method comprises: (1) pretreating a raw material containing propylene and an inert substance, and subjecting the obtained refined raw material to heat exchange to obtain a heat-exchanged raw material; (2) subjecting the raw materials after heat exchange and the catalyst to a dimerization reaction in the presence of an inert gas, and dividing the obtained reaction products into a partial reaction product and a remaining partial reaction product; (3) using the cooled partial reaction product as a heat exchange medium to perform heat exchange with the refined raw material to obtain a heat exchange product; (4) separating the mixture of the remaining reaction product and the product after heat exchange to obtain a light component and a heavy component; and distilling the heavy component to obtain 4-methyl-1-pentene.

2. The method according to claim 1, wherein: In step (1), the volume flow ratio of propylene to inert in the raw material is 1:0.01-50, preferably 1:0.04-40; and / or, the inert substance is selected from C2-C5 alkanes and / or C3-C5 cycloalkanes, preferably C2-C5 alkanes; And / or, the pretreatment process includes: dehydrating and deoxygenating the raw material to obtain the refined raw material; And / or, the water content in the refined raw material is ≤10ppm, preferably ≤3ppm; the O2 content is ≤10ppm, preferably ≤3ppm; And / or, the temperature of the raw material after the heat exchange is 50-300°C, preferably 100-200°C.

3. The method according to claim 1 or 2, wherein: In step (2), the volume flow ratio of the raw material and the catalyst after the heat exchange is 0.1-10:1, preferably 0.5-5:1; And / or, the water content in the inert gas is ≤10ppm, preferably ≤3ppm; the O2 content is ≤10ppm, preferably ≤3ppm; And / or, the conditions of the dimerization reaction include: temperature of 50-300°C, preferably 100-200°C; pressure of 4-20MPa, preferably 6-12MPa; And / or, the temperature rise of the dimerization reaction is ≤60°C, preferably ≤30°C.

4. The method according to any one of claims 1 to 3, wherein: In step (2), the mass flow ratio of the partial reaction product to the remaining partial reaction product is 0.1-50:1, preferably 0.2-20:1; And / or, the catalyst is selected from active metal catalysts, and the active metal in the active metal catalyst is selected from at least one of Na, K, Li, Mg, Al and Fe, preferably selected from Na and / or K; Preferably, the active metal content in the active metal catalyst is 0.1-20wt%, preferably 0.5-10wt%; Preferably, the carrier of the active metal catalyst is selected from at least one of alkali metal salts, molecular sieves and activated carbon.

5. The method according to any one of claims 1 to 4, wherein: In step (3), the temperature difference between the reaction product and the heat exchange medium is 1-50°C, preferably 10-30°C; and / or, the temperature of the heat exchange medium is 30-280°C, preferably 80-180°C; And / or, in step (4), the separation conditions include: the tower top temperature is 30-90°C, preferably 40-70°C; the tower top pressure is 1-3MPa, preferably 1.5-2MPa; And / or, the distillation conditions include: the tower top temperature is 60-150° C., preferably 80-120° C.; the tower top pressure is 0.2-0.8 MPa, preferably 0.2-0.5 MPa; And / or, the method further comprises: returning the light component and mixing it into the raw material.

6. A device for preparing 4-methyl-1-pentene, characterized in that: The device comprises a raw material tank (I), a pretreatment unit (II), a reaction unit, a separation unit (V) and a distillation unit (VI) which are connected in sequence, wherein the reaction unit comprises a fixed bed reactor (III) and a heat exchange unit (IV) connected to the side wall of the fixed bed reactor (III); The pretreatment unit (II) is used to pretreat the raw material (03) containing propylene (01) and inert matter (02) to obtain a refined raw material (04); The fixed bed reactor (III) comprises a shell (1) provided with at least one wound reaction tube (6). The refined raw material (04) entering the wound reaction tube (6) is heat exchanged with the heat exchange medium (06) of the shell side, and then contacts with the catalyst loaded in the wound reaction tube (6) in the presence of an inert gas and undergoes a dimerization reaction. The obtained reaction product is divided into two streams. A part of the reaction product (05-i) is cooled in the heat exchange unit (IV) and used as the heat exchange medium (06); the remaining part of the reaction product and the mixture (07) of the product after heat exchange enters the separation unit (V), and the light component (08) is obtained at the top of the tower. The heavy component (09) obtained at the bottom of the tower enters the distillation unit (VI), and 4-methyl-1-pentene (010) is obtained at the top of the tower, and the heavy impurities (011) are obtained at the bottom of the tower.

7. The device according to claim 6, wherein: The winding reaction tube (6) is selected from a serpentine reaction tube and a disc-shaped reaction tube; and / or, a plurality of the wound reaction tubes (6) are arranged in parallel in the housing (1); And / or, the number of the wound reaction tubes (6) is selected from 1 to 200, preferably 1 to 20; And / or, the inner diameter ratio of the wound reaction tube (6) and the shell (1) is 0.00125-0.4:1, and the height ratio is 0.7-1:1; And / or, the inner diameter of the wound reaction tube (6) is 10-200 mm, preferably 15-150 mm; And / or, a first supporting component (7-1) and a second supporting component (7-2) are also provided in the housing (1).

8. The device according to claim 7, wherein: When the winding reaction tube (6) is selected from a serpentine reaction tube, the serpentine reaction tube is composed of a series of tubes, and the tubes are connected by a joint (8); Preferably, the number of the tube arrays is 1-50, preferably 1-10; Preferably, the joint (8) is selected from a threaded joint, a ferrule joint, a welded elbow joint, and a flange joint; And / or, when the wound reaction tube (6) is selected from a disc-shaped reaction tube, the number of the disc-shaped reaction tubes is 1-50, preferably 1-15; the distance between two adjacent coils is 12.5-300 mm, preferably 20-225 mm.

9. The device according to any one of claims 6 to 8, wherein: The upper end cover (2) of the shell (1) is provided with a material inlet (5), and the lower end cover (3) is provided with a material outlet (4) and an inert gas inlet (9); And / or, a heat exchange medium outlet (16) and a heat exchange medium inlet (17) are provided on the side wall of the shell (1) and the connecting pipe of the heat exchange unit (IV), and the heat exchange medium outlet (16) is provided below the heat exchange medium inlet (17); and / or, a first thermometer (T1) and a second thermometer (T2) are respectively provided on the pipeline connecting the material inlet (5) and the material outlet (4); And / or, a flow controller is provided on the pipeline connected to the material inlet (5); or, a distributor is provided in the shell (1), and the distributor is provided above the wound reactor (6).

10. The device according to any one of claims 6 to 9, wherein: The reaction unit further comprises: a catalyst loading unit (VII) connected to the upper end cap (2) of the shell (1), the catalyst loading unit (VII) comprising an external loading container (14), and an inert gas interface (13) and a catalyst inlet (12) arranged on the external loading container (14), for loading the catalyst into the wound reaction tube (6) under the transport of the inert gas; Preferably, during the loading process of the catalyst, the flow rate of the inert gas is 1-100 m / s, preferably 5-30 m / s; Preferably, the external loading container (14) and the fixed bed reactor (III) are connected via an external loading connecting pipe (15); And / or, the top of the separation unit (V) is connected to the pretreatment unit (II) for returning the light component (08) and mixing it into the raw material (03).

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