Fixed bed reactor system, application thereof and method for preparing 4-methyl-1-pentene through propylene dimerization

Abstract

The invention relates to the technical field of fixed bed reactors, in particular to a fixed bed reactor system and application thereof, and a method for preparing 4-methyl-1-pentene through propylene dimerization. According to the system, the winding type reaction tubes are used for filling the catalyst, so that the problems that a tubular fixed bed reactor cannot ensure the same filling amount of each reaction tube, the resistance of each reaction tube is different due to non-uniform filling, and the material distribution is non-uniform during formal reaction are solved; stable temperature of a reactor bed layer and uniform reaction process are ensured, so that normal reaction and the service life of a catalyst are not influenced, and loosening and loss of catalyst particles in a plurality of tubes in lower feeding operation or upper feeding operation of the tubular fixed bed reactor are prevented; the system is applied to a method for dimerizing 4-methyl-1-pentene from propylene, so that the propylene conversion rate is increased, the reaction process is efficient, uniform and stable, and the process requirement of long-period operation is met.

Description

Technical Field

[0001] The invention relates to the technical field of fixed bed reactors, and in particular to a fixed bed reactor system and application thereof, and a method for preparing 4-methyl-1-pentene by propylene dimerization. Background Art

[0002] For catalytic reactions with high thermal effects, it is usually necessary to take away the heat released by the reaction in time, or to replenish the heat required for the reaction in time, so as 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 take away 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. At present, the method of loading the catalyst usually loads the catalyst from the top of the reactor and lets the catalyst fall. The manual loading method is the most common. 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.

[0003] 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.

[0004] CN105363388A discloses a multiphase liquid distribution structure for a tubular reactor, which is fixed on the tube sheet of the tubular reactor by a liquid distribution structure such as a cap, a sleeve and a circular baffle to compensate for the problem of uneven material distribution during the reaction due to different resistances of each reaction tube caused by inconsistent loading of catalysts in different tubes. CN114392702A discloses a tubular reactor in series. When the reaction to prepare the desired product requires heating equipment, a tubular reactor is used. The series design avoids heat waste in the heating method, but the reaction is not sufficient.

[0005] Although the above-mentioned disclosed shell-and-tube reactor system has been compensated through some structural and process designs, it cannot simultaneously solve the problem of uneven material distribution during the reaction due to different resistances of each reaction tube caused by uneven filling and the problem of catalyst loosening and loss in many shells and tubes. It is necessary to ensure that the reactor bed temperature is stable and the reaction materials are uniform so as not to affect the normal progress of the reaction and the service life of the catalyst. The existing disclosed methods cannot meet the requirements. Summary of the invention

[0006] The purpose of the present invention is to overcome the above technical problems and provide a fixed bed reactor system and its application, a method for preparing 4-methyl-1-pentene by propylene dimerization. The system solves the problem of uneven material distribution during reaction due to different resistances of each reaction tube caused by uneven catalyst loading and the problem of catalyst loosening and loss in many tubes, and ensures the stability of the reactor bed temperature.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a fixed bed reactor system, which includes a fixed bed reactor, a heat exchange unit and a catalyst loading unit, wherein the fixed bed reactor includes a shell, and the shell is provided with a material outlet and a material inlet; at least one winding reaction tube is arranged in the shell; the catalyst loading unit is connected to the upper part of the shell, and is used to load the active metal catalyst into the winding reaction tube under the conveyance of inert gas; the heat exchange unit is connected to the side wall of the shell through a pipeline;

[0008] The reaction material enters the wound reaction tube, contacts the active metal catalyst and reacts. After the material on the tube side exchanges heat with the heat exchange medium on the shell side, the heat exchanged material is discharged through the material outlet. The heat exchange medium is cooled by the heat exchange unit and recycled.

[0009] The second aspect of the present invention provides a method for preparing 4-methyl-1-pentene by dimerizing propylene using the system provided in the first aspect.

[0010] The third aspect of the present invention provides a method for preparing 4-methyl-1-pentene by dimerization of propylene, which is carried out in the system provided in the first aspect, and comprises:

[0011] (1) placing the system in a non-oxidizing atmosphere;

[0012] (2) loading an active metal catalyst into a coiled reaction tube under inert gas transport;

[0013] (3) Propylene introduced through the material inlet contacts with the active metal catalyst in the wound reaction tube and undergoes a dimerization reaction. The obtained mixed material exchanges heat with the heat exchange medium in the shell side, and the obtained heat exchanged material is discharged through the material outlet. The obtained heat exchanged heat exchange medium is cooled by the heat exchange unit and then recycled;

[0014] Wherein, the mixed material includes: unreacted propylene and reaction products.

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

[0016] (1) The system provided by the present invention adopts a winding reaction tube to load the catalyst, thereby avoiding the problem that the tube-in-tube fixed bed reactor cannot ensure the same loading amount in each reaction tube. Uneven loading will result in different resistances in each reaction tube, and the material distribution is uneven during the formal reaction. The reactor bed temperature is ensured to be stable and the reaction process is uniform, thereby not affecting the normal progress of the reaction and the service life of the catalyst, and preventing the catalyst particles in the numerous tubes of the tube-in-tube fixed bed reactor from loosening and losing during the lower feeding operation or the upper feeding operation.

[0017] (2) The system provided by the present invention is used for the method of dimerizing propylene with 4-methyl-1-pentene. By adjusting the uniform loading of the catalyst and introducing a heat exchange medium to adjust the dimerization reaction temperature, not only the propylene conversion rate is improved, but also the reaction process is made efficient, uniform and stable, meeting the process requirements for long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a first fixed bed reactor system provided by the present invention;

[0019] Figure 2 is a structural schematic diagram of a second fixed bed reactor system provided by the present invention;

[0020] Figure 3 is a structural schematic diagram of a third fixed bed reactor system provided by the present invention;

[0021] Figure 4 This is a structural schematic diagram of a fixed bed reactor system provided in Example 1.

[0022] Description of Reference Numerals

[0023] I. Fixed bed reactor; II. Heat exchange unit; III. Catalyst loading unit;

[0024] 1. Shell; 2. Upper head; 3. Lower head; 4. Material outlet; 5. Logistics inlet; 6. Winding reaction tube; 7-1. First supporting component; 7-2. Second supporting component; 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; T1. First thermometer; T2. Second thermometer. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[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] The first aspect of the present invention provides a fixed bed reactor system, such as Figure 1-3 As shown, the system includes a fixed bed reactor I, a heat exchange unit II and a catalyst loading unit III, wherein the fixed bed reactor I includes a shell 1, and the shell 1 is provided with a material outlet 4 and a material inlet 5; at least one winding reaction tube 6 is provided in the shell 1; the catalyst loading unit III is connected to the upper part of the shell 1, and is used to load the active metal catalyst into the winding reaction tube 6 under the conveyance of an inert gas; the heat exchange unit II is connected to the side wall of the shell 1 through a pipeline;

[0029] Among them, the reaction material enters the wound reaction tube 6 and contacts with the active metal catalyst to react. After the material in the tube side exchanges heat with the heat exchange medium in the shell side, the obtained heat-exchanged material is discharged through the material outlet 4, and the obtained heat-exchanged heat exchange medium is cooled by the heat exchange unit II and then recycled.

[0030] The inventors of the present invention have found through research that compared with the prior art which uses a parallel shell-and-tube fixed bed reactor, the present invention uses a winding reaction tube and combines inert gas to transport the active metal catalyst to be loaded, so that the active metal catalyst is evenly loaded in the winding reaction tube, thereby avoiding the problems of different loading amounts of each reaction tube in the shell-and-tube fixed bed reactor, causing different resistances of each reaction tube, and uneven material distribution during the formal reaction, thereby ensuring that the reactor bed temperature is stable and the reaction process is uniform, thereby not affecting the normal progress of the reaction and the service life of the catalyst; at the same time, it also prevents the loosening and loss of catalyst particles in many shell-and-tube reactors during lower or upper feeding operations.

[0031] In the present invention, unless otherwise specified, the materials in the tube pass include: unreacted reaction materials and reaction products.

[0032] In the present invention, unless otherwise specified, the heat exchange unit is connected to the side wall of the shell 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.

[0033] In the present invention, if Figure 1-3 As described above, the material outlet 4 can be arranged at the upper head 2 of the shell 1 , or at the lower head 3 of the shell 1 ; similarly, the material inlet 5 can be arranged at the upper head 2 of the shell 1 , or at the lower head 3 of the shell 1 .

[0034] In some embodiments of the present invention, preferably, Figure 1-3 As shown, the winding reaction tube 6 is selected from a serpentine reaction tube and a disc reaction tube.

[0035] In some embodiments of the present invention, preferably, Figure 1-3 As shown, at least one of the wound reaction tubes 6 is 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.

[0036] 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.

[0037] In some embodiments of the present invention, preferably, Figure 1-3As 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.

[0038] In a specific embodiment of the present invention, preferably, Figure 1-3 As shown, the inner diameter of the wound reaction tube 6 is 10-200 mm, preferably 15-150 mm.

[0039] In some embodiments of the present invention, preferably, Figure 1-3 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 .

[0040] In some embodiments of the present invention, preferably, Figure 1-2 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.

[0041] In some embodiments of the present invention, preferably, Figure 1-2 As shown, the number of the tube arrays is 1-50, preferably 1-10.

[0042] In some embodiments of the present invention, preferably, Figure 1-2 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.

[0043] 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.

[0044] 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.

[0045] In some embodiments of the present invention, preferably, Figure 1-3 As shown, the housing 1 is also provided with an inert gas inlet 9 for placing the system in a non-oxidizing atmosphere. In the present invention, the inert gas inlet 9 can be provided at the top or bottom of the housing 1, preferably at the bottom of the housing 1.

[0046] In some embodiments of the present invention, preferably, Figure 1-3 As shown, 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 II.

[0047] In a specific embodiment of the present invention, Figure 1 , 3 As shown, when the system adopts bottom-in and top-out, the material outlet 4 and the material inlet 5 are respectively arranged at the top and bottom of the shell 1, and the heat exchange medium outlet 16 is arranged above the heat exchange medium inlet 17; or Figure 2 As shown, when the system adopts top-in and bottom-out, the material outlet 4 and the material inlet 5 are respectively arranged at the bottom and the top of the shell 1 , and the heat exchange medium outlet 16 is arranged below the heat exchange medium inlet 17 .

[0048] In some embodiments of the present invention, preferably, Figure 1-3 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, for detecting the temperature rise of the fixed bed reactor I.

[0049] In some embodiments of the present invention, preferably, a flow controller is provided on the pipeline connected to the material inlet 5 for regulating the flow of the reaction material.

[0050] In some embodiments of the present invention, preferably, according to the material flow direction, a distributor is provided in the housing 1 for distributing the reaction materials. When the system adopts bottom-in and top-out, the distributor is provided below the winding reactor 6; when the system adopts top-in and bottom-out, the distributor is provided above the winding reactor 6.

[0051] In some embodiments of the present invention, preferably, Figure 1-3 As shown, the catalyst loading unit III includes an external loading container 14 , and an inert gas interface 13 and a catalyst inlet 12 arranged on the external loading container 14 .

[0052] In some embodiments of the present invention, preferably, Figure 1-3As shown, the external loading container 14 and the wound reaction tube 6 are connected via an external loading connecting pipe 15, which is used to load the active metal catalyst into the wound reaction tube 6 under the transport of inert gas.

[0053] In the present invention, unless otherwise specified, the external loading connection pipe 15 connects the bottom of the external loading container 14 and the inlet of the wound reaction tube 6, and is used to load the active metal catalyst into the wound reaction tube 6 under the transport of inert gas.

[0054] The second aspect of the present invention provides an application of the system provided in the first aspect in propylene dimerization with 4-methyl-1-pentene.

[0055] The third aspect of the present invention provides a method for preparing 4-methyl-1-pentene by dimerization of propylene, which is carried out in the system provided in the first aspect, and comprises:

[0056] (1) placing the system in a non-oxidizing atmosphere;

[0057] (2) loading an active metal catalyst into a coiled reaction tube under inert gas transport;

[0058] (3) Propylene introduced through the material inlet contacts with the active metal catalyst in the wound reaction tube and undergoes a dimerization reaction. The obtained mixed material exchanges heat with the heat exchange medium in the shell side, and the obtained heat exchanged material is discharged through the material outlet. The obtained heat exchanged heat exchange medium is cooled by the heat exchange unit and then recycled;

[0059] Wherein, the mixed material includes: unreacted propylene and reaction products.

[0060] In the present invention, in step (1), an inert gas is introduced into the system through an inert gas inlet so that the system is in a non-oxidizing atmosphere.

[0061] In some embodiments of the present invention, preferably, in step (2), 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.

[0062] In some embodiments of the present invention, preferably, in step (2), 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.

[0063] 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.

[0064] In one embodiment of the present invention, preferably, in step (2), 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 with oxygen-free gas, which ensures uniform loading on the one hand and prevents the catalyst from being exposed to oxygen during loading and causing performance damage on the other hand.

[0065] In some embodiments of the present invention, preferably, in step (2), 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, etc.

[0066] In some embodiments of the present invention, preferably, in step (3), the dimerization reaction conditions include: a pressure of 4-20 MPa, preferably 6-12 MPa; a temperature of 50-300° C., preferably 100-200° C. In the present invention, pressure refers to gauge pressure.

[0067] In some embodiments of the present invention, preferably, 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 difference between the logistics temperature through the material outlet and the logistics temperature through the material inlet.

[0068] In some embodiments of the present invention, preferably, the volume flow ratio of propylene to active metal catalyst is 0.1-10:1, for example, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 5:1, 10:1, and any value in the range of any two values, preferably 0.5-5:1.

[0069] In some embodiments of the present invention, preferably, the temperature of the heat exchange medium is 30-280°C, preferably 80-180°C; further preferably, the heat exchange medium is selected from at least one of water, heat transfer oil and partial reaction products, preferably partial reaction products.

[0070] In a specific embodiment of the present invention, when the heat exchange medium is selected from a part of the reaction product, the part of the reaction product is cooled to 30-280°C by a heat exchange unit and then enters the shell side to perform the heat exchange with the mixed material in the wound reaction tube, and the material after heat exchange and the remaining part of the reaction product are discharged through the material outlet.

[0071] In some embodiments of the present invention, preferably, 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 consisting of any two numerical values, preferably 0.2-20:1.

[0072] According to a particularly preferred embodiment of the present invention, a fixed bed reactor system comprises a fixed bed reactor, a heat exchange unit and a catalyst loading unit, wherein the fixed bed reactor comprises a shell, the shell is provided with a material outlet and a material inlet; at least one winding reaction tube is provided in the shell; the catalyst loading unit is connected to the upper part of the shell, and is used to load the active metal catalyst into the winding reaction tube under the conveyance of an inert gas; the heat exchange unit is connected to the side wall of the shell through a pipeline;

[0073] The reaction material enters the wound reaction tube and contacts the active metal catalyst to react. After the material in the tube side exchanges heat with the heat exchange medium in the shell side, the heat exchanged material is discharged through the material outlet. The heat exchange medium is cooled by the heat exchange unit and then recycled.

[0074] Wherein, when the winding reaction tube 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; or, when the winding reaction tube is selected from a disc reaction tube, the number of the disc reaction tubes is 1-50;

[0075] Wherein, the catalyst loading unit comprises an external loading container, and an inert gas interface and a catalyst inlet arranged on the external loading container.

[0076] The present invention will be described in detail below through examples.

[0077] 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.

[0078]

[0079] The temperature rise of the dimerization reaction = the second thermometer T2 - the first thermometer T1.

[0080] Example 1

[0081] Fixed bed reactor system Figure 1 As shown, the system includes: a fixed bed reactor I, a heat exchange unit II and a catalyst loading unit III; when the system adopts bottom-in and top-out, the fixed bed reactor I includes a shell 1, the top of the shell 1 is provided with a material outlet 4, and the bottom is provided with a material inlet 5 and an inert gas inlet 9; a winding reaction tube 6 is provided in the shell 1, and the winding reaction tube is composed of a series of tubes, and the number of tubes is 2; the bottom of the catalyst loading unit III and the upper part of the shell 1 are connected through an external loading connecting pipe 15, and the catalyst loading unit III includes an external loading container 14, an inert gas interface 13 and a catalyst inlet 12; 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 II, and the heat exchange medium outlet 16 is arranged above the heat exchange medium inlet 17;

[0082] 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;

[0083] Among them, the height of the fixed bed reactor I is 6500mm and the inner diameter is 2000mm; the height of the wound reaction tube is 5000mm and the inner diameter is 20mm;

[0084] The method for preparing 4-methyl-1-pentene by propylene dimerization is carried out in the above system, and the method comprises:

[0085] (1) introducing nitrogen to place the above system in a non-oxidizing atmosphere;

[0086] (2) The above active metal catalyst is loaded into a coiled reaction tube under nitrogen gas (water content of 3 ppm; O2 content of 3 ppm, flow rate of 20 m / s);

[0087] (3) Propylene and the above-mentioned active metal catalyst are subjected to dimerization reaction in a wound reaction tube at a volume flow ratio of 1.5:1 (temperature of 155° C., pressure of 7 MPa) to obtain a mixed material containing reaction products and unreacted propylene. The above-mentioned mixed material is heat exchanged with a heat exchange medium (water, temperature of 135° C.) outside the wound reaction tube, and the obtained heat exchanged material is discharged through a material outlet. The obtained heat exchanged heat exchange medium is cooled by a heat exchange unit and then recycled.

[0088] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 25° C. The obtained reaction material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 85%.

[0089] Example 2

[0090] According to the system of Example 1, the difference is that Figure 2 As shown, when the system adopts top-in and bottom-out, the top of the shell 1 is provided with a material inlet 5, and the bottom is provided with a material outlet 4; the heat exchange medium inlet 17 is provided above the heat exchange medium outlet 16;

[0091] According to the method of Example 1, the difference is that the method is carried out in the above system,

[0092] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 25° C. The obtained reaction material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 84%.

[0093] Example 3

[0094] According to the system of Example 1, the difference is that Figure 3 As shown, the types of the wound reaction tubes are different, that is, the wound reaction tubes are selected from four disc-shaped reaction tubes connected in parallel, and the four disc-shaped tubes are symmetrically distributed in the shell;

[0095] According to the method of Example 1, the difference is that the method is carried out in the above system,

[0096] The volume flow ratio of propylene and the above active metal catalyst is changed to 2:1;

[0097] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 28° C. The obtained reaction material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 83%.

[0098] Example 4

[0099] The system according to embodiment 1;

[0100] The method of Example 1 is followed, except that the flow rate of nitrogen is replaced with 3 m / s;

[0101] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 40° C. The obtained reaction material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 75%.

[0102] Example 5

[0103] The system according to embodiment 1;

[0104] The method of Example 1 is different in that the heat exchange medium is replaced by part of the reaction product, that is, the part of the reaction product is cooled to 135° C. by the heat exchange unit and then enters the shell side to exchange heat with the propylene in the wound reaction tube, and the heat exchanged material and the remaining part of the reaction product are discharged through the material outlet;

[0105] Wherein, the mass flow ratio of the partial reaction product to the remaining partial reaction product is 1.5:1;

[0106] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 25° C. The obtained reaction material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 86%.

[0107] Comparative Example 1

[0108] Fixed bed reactor system Figure 4 As shown, the system comprises: a fixed bed reactor I, a heat exchange unit II;

[0109] When the system adopts bottom-in and top-out, the fixed bed reactor I comprises a shell 1, the top of the shell 1 is provided with a material outlet 4, and the bottom is provided with a material inlet 5 and an inert gas inlet 9; 3200 parallel tubes 11 are provided in the shell 1, and the tubes 11 are filled with the above-mentioned active metal catalyst; 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 II, and the heat exchange medium outlet 16 is provided above the heat exchange medium inlet 17; a first thermometer T1 and a second thermometer T2 are respectively provided on the pipe connecting the material inlet 5 and the material outlet 4;

[0110] The fixed bed reactor I has a height of 6500 mm and an inner diameter of 2000 mm; the tubes have a height of 5000 mm and an inner diameter of 20 mm; the tubes are filled with the active metal catalyst;

[0111] The method for preparing 4-methyl-1-pentene by propylene dimerization is carried out in the above system, and the method comprises:

[0112] Propylene and the above-mentioned active metal catalyst are dimerized in a tube array at a volume flow ratio of 1.5:1 (temperature is 155°C, pressure is 7MPa), and the obtained mixed material containing reaction products and unreacted is heat exchanged with a heat exchange medium (water, temperature is 135°C) outside the tube array. The heat exchanged material is discharged through the material outlet, and the heat exchange medium is cooled by a heat exchange unit and recycled.

[0113] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was 60° C. The obtained material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 60%.

[0114] 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.

[0115] Comparative Example 2

[0116] A system according to Example 1, except that the system does not include: a heat exchange unit II, a heat exchange medium outlet 16 and a heat exchange medium inlet 17;

[0117] According to the method of Example 1, except that the method is carried out in the above system;

[0118] In step (2), the reaction product is directly discharged through the material outlet;

[0119] The dimerization reaction was carried out for 2 hours, and the temperature rise of the dimerization reaction was greater than 150° C. The obtained reaction material after heat exchange was sent to an online chromatographic analyzer for composition analysis, and the propylene conversion rate was 70%.

[0120] Compared with Comparative Examples 1-2, Examples 1-5 use the fixed bed reactor system provided by the present invention to carry out propylene dimerization reaction, and the reaction conversion rate is significantly improved. The reaction process is efficient, uniform and stable, meeting the process requirements for long-term operation.

[0121] 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 fixed bed reactor system, characterized in that: The system comprises a fixed bed reactor (I), a heat exchange unit (II) and a catalyst loading unit (III), wherein the fixed bed reactor comprises a shell (1), wherein the shell (1) is provided with a material outlet (4) and a material inlet (5); at least one winding reaction tube (6) is provided in the shell (1); the catalyst loading unit (III) is connected to the upper part of the shell (1) and is used for loading an active metal catalyst into the winding reaction tube (6) under the conveyance of an inert gas; the heat exchange unit (II) is connected to the side wall of the shell through a pipeline; The reaction material enters the wound reaction tube (6) and contacts the active metal catalyst to react. After the material on the tube side exchanges heat with the heat exchange medium on the shell side, the heat exchanged material is discharged through the material outlet (4). The heat exchange medium is cooled by the heat exchange unit (II) and recycled.

2. The system according to claim 1, wherein: The winding reaction tube (6) is selected from a serpentine reaction tube and a disc-shaped reaction tube; and / or, at least one of the wound reaction tubes (6) is arranged in parallel in the housing (1); And / or, the number of the wound reaction tubes (6) is selected from 1-200, preferably 1-20.

3. The system according to claim 2, wherein: 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).

4. The system according to claim 2 or 3, 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.

5. The system according to any one of claims 1 to 4, wherein: The housing (1) is also provided with 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 (II); And / or, when the system adopts bottom-in and top-out, the material outlet (4) and the material inlet (5) are respectively arranged at the top and bottom of the shell, and the heat exchange medium outlet (16) is arranged above the heat exchange medium inlet (17); or, when the system adopts top-in and bottom-out, the material outlet (4) and the material inlet (5) are respectively arranged at the bottom and top of the shell, and the heat exchange medium outlet (16) is arranged 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).

6. The system according to any one of claims 1 to 5, wherein: The catalyst loading unit (III) comprises an external loading container (14), and an inert gas interface (13) and a catalyst inlet (12) arranged on the external loading container (14); Preferably, the external loading container (14) and the wound reaction tube (6) are connected via an external loading connecting pipe (15).

7. Use of the system according to any one of claims 1 to 6 in the preparation of 4-methyl-1-pentene by propylene dimerization.

8. A method for preparing 4-methyl-1-pentene by propylene dimerization, characterized in that: The method is carried out in a system as described in any one of claims 1 to 6, and the method comprises: (1) placing the system in a non-oxidizing atmosphere; (2) loading an active metal catalyst into a coiled reaction tube under inert gas transport; (3) Propylene introduced through the material inlet contacts with the active metal catalyst in the wound reaction tube and undergoes a dimerization reaction. The obtained mixed material exchanges heat with the heat exchange medium in the shell side, and the obtained heat exchanged material is discharged through the material outlet. The obtained heat exchanged heat exchange medium is cooled by the heat exchange unit and then recycled; Wherein, the mixed material includes: unreacted propylene and reaction products.

9. The method according to claim 8, wherein: In step (2), The active metal in the active metal catalyst is selected from at least one of Na, K, Li, Mg, Al and Fe; and / or, the active metal content in the active metal catalyst is 0.1-20wt%, preferably 0.5-10wt%; And / or, the flow rate of the inert gas is 1-100 m / s, preferably 5-30 m / s; And / or, the water content in the inert gas is ≤10ppm, preferably ≤3ppm; the O2 content is ≤10ppm, preferably ≤3ppm.

10. The method according to claim 8 or 9, wherein: In step (3), The conditions of the dimerization reaction include: a pressure of 4-20 MPa, preferably 6-12 MPa; a temperature of 50-300° C., preferably 100-200° C.; and / or, the temperature rise of the dimerization reaction is ≤60°C, preferably ≤30°C; and / or, the volume flow ratio of propylene to active metal catalyst is 0.1-10:1, preferably 0.5-5:1; and / or, the temperature of the heat exchange medium is 30-280°C, preferably 80-180°C; And / or, the heat exchange medium is selected from at least one of water, heat transfer oil and part of the reaction product; And / or, when the heat exchange medium is selected from a part of the reaction product, the part of the reaction product is cooled by the heat exchange unit and then enters the shell side to perform the heat exchange with the mixed material, and the heat exchanged material and the remaining part of the reaction product are discharged through the material outlet; And / or, 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.

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