Catalyst and preparation method thereof, and method for preparing 4-methyl-1-pentene through propylene dimerization

Abstract

The invention relates to the technical field of catalysts, and discloses a catalyst and a preparation method thereof, and a method for preparing 4-methyl-1-pentene through propylene dimerization, the catalyst comprises a carrier, and an active metal component and an auxiliary metal component loaded on the carrier; wherein the carrier comprises potassium carbonate and a binder, the active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of precious metals; wherein on the basis of the mass of the carrier, the content of the active metal component is 1-20wt% and the content of the auxiliary metal component is 0.1-10wt% in terms of metal elements. The catalyst has high catalytic activity and stability in propylene dimerization reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a catalyst and its preparation method, and a method for preparing 4-methyl-1-pentene by propylene dimerization. Background Technology

[0002] 4-Methyl-1-pentene (4M1P) can form linear low-density polyethylene resin (LLDPE) with ethylene and propylene. It has excellent impact resistance, tensile tear strength and dielectric properties, so it is widely used in industry. At the same time, it can also self-polymerize to obtain a thermoplastic plastic with strong advantages in density, transparency, heat resistance and corrosion resistance - poly(4-methyl-1-pentene) (PMP), which is the core material of extracorporeal membrane oxygenation (ECMO) "artificial lung".

[0003] In the 1960s, California Research Corp. successfully developed alkali metal catalysts for the dimerization of propylene to produce 4M1P. BP pioneered its industrialization, building the world's first 2,000-ton / year production plant. In the 1970s, Mitsui Petrochemicals of Japan imported and improved upon BP's manufacturing technology, establishing a 2,500-ton / year production plant, which was increased to 25,000 tons / year in the early 1990s. Meanwhile, Phillips Petroleum of the United States built an industrial-scale plant in the early 1990s, reaching a capacity of 45,000 tons / year. Currently, global 4M1P production capacity is mainly concentrated in Mitsui Chemicals of Japan and Phillips Petroleum of the United States, using alkali metal catalyst systems as the active component and high-temperature, high-pressure, anhydrous, and oxygen-free conditions to produce 4M1P through the dimerization of propylene.

[0004] The low single-pass conversion rate of feedstock is a major challenge in the alkali metal-catalyzed propylene dimerization to 4M1P reaction. Therefore, current experiments typically employ methods such as increasing reaction temperature and pressure, and decreasing space velocity to attempt to overcome this limitation. However, while these operations improve feedstock conversion, they also prolong the contact time between reactants and catalyst, intensifying the polymerization reaction and increasing the proportion of isomerization byproducts in the product, thus creating new challenges for the subsequent industrial separation and purification of the product. Simulation studies of the product component distillation process show that 4M1P is the light key component in distillation, while 4-methyl-2-pentene (4M2P), with a similar boiling point, is the heavy key component. The ratio of these two components in the distillation feedstock significantly affects the scale and energy consumption of the distillation column. Therefore, their proportion in the product becomes one of the main evaluation indicators for the propylene dimerization reaction. Correspondingly, the selectivity of 4M1P is also an important factor influencing the industrial application potential of propylene dimerization catalysts. Furthermore, improving catalyst lifetime not only reduces production costs but also helps to reduce the cumbersome steps of loading water- and oxygen-sensitive catalysts and the risk of handling deactivated catalysts. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low single-pass conversion rate and poor stability of raw materials in the prior art, and to provide a catalyst and its preparation method, and a method for preparing 4-methyl-1-pentene by propylene dimerization. This catalyst has high catalytic activity and stability in the propylene dimerization reaction.

[0006] To achieve the above objectives, the present invention provides a catalyst comprising a support and an active metal component and an auxiliary metal component supported on the support; wherein the support comprises potassium carbonate and a binder, the active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of noble metals;

[0007] Based on the mass of the carrier, the content of the active metal component is 1-20 wt% and the content of the auxiliary metal component is 0.1-10 wt%, calculated by metal element.

[0008] A second aspect of the present invention provides a method for preparing a catalyst, the method comprising:

[0009] (1) Potassium carbonate, binder and guar gum powder are mixed and molded to obtain a carrier;

[0010] (2) Loading the active metal component and the auxiliary metal component onto the carrier;

[0011] The active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of noble metals.

[0012] Based on the mass of the carrier, the loading of the active metal component is 1-20 wt% and the loading of the auxiliary metal component is 0.1-10 wt%, calculated by metal element.

[0013] A third aspect of the present invention provides a method for preparing 4-methyl-1-pentene by propylene dimerization, the method comprising: contacting propylene with a catalyst under an inert atmosphere to carry out selective polymerization of propylene;

[0014] The catalyst is either the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect.

[0015] The catalyst provided by this invention, through the above technical solution, comprises a potassium carbonate-containing support and a noble metal and an active metal sodium and / or potassium loaded on the support. Through the synergistic effect of the support and an appropriate loading of active and noble metals, this catalyst exhibits high catalytic activity in the propylene dimerization reaction. Compared to conventional alkali metal catalysts, the propylene single-conversion rate is significantly improved. Furthermore, the catalyst performs admirably at a rapid deactivation temperature of 170°C, effectively slowing down the deactivation process and demonstrating good catalyst stability. This is likely because the introduction of appropriate noble metal promoters, through their interaction with the active metal and support, promotes the adsorption of propylene molecules on the catalyst surface, reducing the energy barriers for reactant diffusion and active site adsorption in heterogeneous catalytic reactions, thereby improving the conversion rate and selectivity of the catalyst in the propylene dimerization reaction. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] A first aspect of the present invention provides a catalyst comprising a support and an active metal component and an auxiliary metal component supported on the support; wherein the support comprises potassium carbonate and a binder, the active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of noble metals;

[0018] Based on the mass of the carrier, the content of the active metal component is 1-20 wt% and the content of the auxiliary metal component is 0.1-10 wt%, calculated by metal element.

[0019] According to the present invention, under the synergistic effect of the support and an appropriate loading of active metal and noble metal, the catalyst exhibits high catalytic activity in the propylene dimerization reaction. Compared with conventional alkali metal catalysts, the single conversion rate of propylene is significantly improved. Simultaneously, the catalyst demonstrates high stability and a long service life. This is likely because the introduction of appropriate noble metal promoters, through their interaction with the active metal and support, promotes the adsorption of propylene molecules on the catalyst surface, lowers the energy barriers for reactant diffusion and adsorption at active sites in heterogeneous catalytic reactions, thereby improving the catalyst's conversion rate, selectivity, and stability in the propylene dimerization reaction.

[0020] The present invention does not have any special requirements regarding the source of the potassium carbonate. Preferably, the potassium carbonate is anhydrous potassium carbonate, which can be obtained from commercial purchases or by any method known in the art. For example, it can be anhydrous potassium carbonate with a particle size distribution satisfying the Rosin-Rammler (RR) distribution obtained by sieving, classifying, and mixing according to the Rosin-Rammler (RR) distribution disclosed in EP0083083.

[0021] According to the present invention, the carrier optionally includes a binder, preferably graphite. Preferably, the binder content in the carrier is 0.5-5 wt%, more preferably 0.75-3 wt%, based on the mass of the potassium carbonate.

[0022] In this invention, the active metal component can be sodium, potassium, or a combination of sodium and potassium, which can be selected by those skilled in the art according to actual needs. Preferably, the active metal component includes sodium and potassium. Preferably, the mass ratio of sodium to potassium is 1-5:5-1, based on elemental composition. With the above-mentioned preferred carrier and active metal composition, a suitable propylene conversion rate and selectivity for 4-methyl-1-pentene can be further balanced.

[0023] According to the present invention, preferably, the active metal component exists in elemental form.

[0024] According to some preferred embodiments of the present invention, the auxiliary metal component is selected from at least one of platinum, rhodium and palladium, preferably platinum.

[0025] Preferably, the auxiliary metal component exists in elemental form.

[0026] According to some particularly preferred embodiments of the present invention, the active metal component includes sodium and potassium, and the auxiliary metal component is platinum. In the above preferred embodiments, it is advantageous to further improve the catalytic activity and stability of the catalyst.

[0027] In this invention, based on the mass of the support, the content of the active metal component, calculated by metal element, is 1-20 wt%, and the content of the auxiliary metal component is 0.1-10 wt%. Preferably, based on the mass of the support, the content of the active metal component, calculated by metal element, is 2-10 wt%, and the content of the auxiliary metal component is 0.5-2.5 wt%. In the above preferred embodiments, it is beneficial for the catalyst to maintain a high propylene conversion and 4M1P selectivity while having good flowability. Due to the water and oxygen sensitive characteristics of the catalyst, flowability is particularly important in the loading and transfer steps of industrial plants.

[0028] According to the present invention, preferably, the mass ratio of the active metal component to the auxiliary metal component, based on metal element content, is 1:(0.01-1), for example, it can be a specific ratio or any range between two such ratios, such as 1:0.01, 1:0.02, 1:0.04, 1:0.06, 1:0.08, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc. Preferably, the mass ratio of the active metal component to the auxiliary metal component, based on metal element content, is 1:(0.1-0.5). In the above preferred case, it is beneficial to further exert the synergistic effect of the active metal component and the auxiliary component, and further improve the catalytic activity and stability of the catalyst.

[0029] A second aspect of the present invention provides a method for preparing a catalyst, the method comprising:

[0030] (1) Potassium carbonate, binder and guar gum powder are mixed and molded to obtain a carrier;

[0031] (2) Loading the active metal component and the auxiliary metal component onto the carrier;

[0032] The active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of noble metals.

[0033] Based on the mass of the carrier, the loading of the active metal component is 1-20 wt% and the loading of the auxiliary metal component is 0.1-10 wt%, calculated by metal element.

[0034] According to some preferred embodiments of the present invention, in step (1), the amount of binder used is 0.5-5 wt%, preferably 0.75-3 wt%, based on the mass of potassium carbonate.

[0035] Preferably, the binder is graphite.

[0036] According to some preferred embodiments of the present invention, in step (1), the amount of guar gum powder used is 0.1-20 wt%, preferably 1-10 wt%, based on the mass of potassium carbonate.

[0037] In this invention, there are no special requirements for the specific operation and conditions of the mixing and molding in step (1), and conventional molding methods in the art can be used. Preferably, the molding method is tableting. This invention does not have special limitations on the specific operating conditions of the tableting, and conventional conditions can be used for tableting. Preferably, the tableting pressure is 5-100 MPa, and the holding time is 1-20 min.

[0038] According to some preferred embodiments of the present invention, step (1) further includes: optionally crushing and sieving the shaped product to a particle size of 250-500 nm, preferably 300-450 nm.

[0039] In this invention, the pulverization and sieving can be carried out using conventional methods in the art, as long as the particle size of the support meets the above-mentioned range. Controlling the support particle size within the above-mentioned preferred range helps to balance the conversion rate of propylene dimerization and the product isomerization rate, taking into account both suitable propylene conversion and 4M1P selectivity, while further improving the catalyst's flowability.

[0040] According to the present invention, preferably, the molding and calcination are carried out in an oxygen-containing atmosphere, which may be, for example, air.

[0041] Preferably, the molding and baking temperature is 100-800℃, and more preferably 300-600℃.

[0042] Preferably, the molding and baking time is 1-10 hours, and more preferably 2-8 hours.

[0043] In this invention, there are no particular limitations on the loading order and loading method of the active metal component and the auxiliary metal component in step (2). The active metal component and the auxiliary metal component can be loaded onto the carrier in one step or in stages, depending on the loading amount of the active metal component and the auxiliary metal component. Those skilled in the art can make the selection according to the actual situation.

[0044] According to some preferred embodiments of the present invention, step (2) includes:

[0045] (2-1) Under a protective atmosphere, the carrier and the auxiliary metal are first mixed;

[0046] (2-2) The product obtained in step (2-1) is mixed with the active metal in a second step.

[0047] The present invention does not have particular requirements for the specific mixing method, as long as the active metal can be uniformly dispersed on the carrier. Any mixing method well known to those skilled in the art can be used, such as rotational mixing or stirring mixing. Preferably, the mixing is carried out under stirring conditions.

[0048] The present invention does not impose any particular limitations on the specific conditions for the mixing, and those skilled in the art can select them according to actual needs.

[0049] Preferably, the temperature of the first mixing is 50-400℃, more preferably 100-300℃; and the time is 1-8h, more preferably 2-4h.

[0050] Preferably, the temperature of the second mixing is 100-600℃, more preferably 200-400℃; and the time is 0.5-8h, more preferably 1-6h.

[0051] In this invention, the protective atmosphere refers to an inactive atmosphere that does not participate in the reaction. Preferably, the protective atmosphere is provided by at least one of nitrogen, argon, neon and helium.

[0052] According to the present invention, preferably, based on the mass of the carrier and calculated by metal elements, the loading of the active metal component is 1-20 wt%, preferably 2-10 wt%, and the loading of the auxiliary metal component is 0.1-10 wt%, preferably 0.5-5 wt%.

[0053] Preferably, the mass ratio of active metal to auxiliary metal is 1:(0.01-1), more preferably 1:(0.1-0.5).

[0054] A third aspect of the present invention provides a method for preparing 4-methyl-1-pentene by propylene dimerization, the method comprising: contacting propylene with a catalyst under an inert atmosphere to carry out selective polymerization of propylene;

[0055] The catalyst is either the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect.

[0056] In this invention, the selection range for the contact conditions is relatively wide and can be chosen according to actual production needs. Preferably, the contact conditions include: a reaction pressure of 4-16 MPa, more preferably 6-12 MPa; a reaction temperature of 120-180℃, more preferably 140-160℃; and a liquid hourly space velocity of 0.2-6 h⁻¹. -1 Preferably, it is 0.6-2.4h. -1 .

[0057] According to the present invention, the inert atmosphere is an inert protective gas that does not participate in the reaction, and may be provided by at least one of nitrogen, argon, neon and helium.

[0058] Preferably, the method further includes: subjecting the propylene to deoxygenation and dehydration treatment prior to the contact. The deoxygenation and dehydration treatment can be performed using conventional methods in the art, which are well known to those skilled in the art and will not be described in detail here.

[0059] The present invention will be described in detail below through embodiments.

[0060] Example 1

[0061] (1) Carrier treatment: Anhydrous potassium carbonate was sieved, graded and mixed according to the Rosin-Rammler distribution (RR distribution) disclosed in patent EP0083083; based on the mass of anhydrous potassium carbonate (RR distribution potassium carbonate), 1 wt% graphite and 2.5 wt% guar gum powder were added and mixed evenly. Then, the mixture was pressed into tablets using an electric tablet press at a pressure of 20 MPa and a holding time of 5 min; the pressed tablets were crushed and sieved, and the 40-60 mesh (300-450 nm) carrier particles were placed in a vacuum crucible furnace and baked with air at 500℃ and normal pressure for 6 h to prepare the catalyst carrier.

[0062] (2) Support loading: A certain amount of baked catalyst support was placed in a three-necked flask under an inert atmosphere, and 1 wt% of platinum powder was added. The flask was dried at 350°C by mechanical stirring and electric heating. After the flask wall was free of water mist, the drying was maintained for 2 hours. After cooling, 2.2 wt% of metallic sodium and 2.8 wt% of metallic potassium were added, and the flask was stirred at 350°C for 4 hours to prepare CAT-1, a propylene dimerization catalyst with silver-gray particles.

[0063] Example 2

[0064] (1) Carrier treatment: Anhydrous potassium carbonate was sieved, graded and mixed according to the Rosin-Rammler distribution (RR distribution) disclosed in patent EP0083083; based on the mass of anhydrous potassium carbonate (RR distribution potassium carbonate), 0.75wt% of graphite and 3wt% of guar gum powder were added and mixed evenly. Then, the mixture was pressed into tablets using an electric tablet press at a pressure of 20MPa and a holding time of 5min; the pressed tablets were crushed and sieved, and the 40-60 mesh (300-450nm) carrier particles were placed in a vacuum crucible furnace and baked at 500℃ and normal pressure for 6h to prepare the catalyst carrier.

[0065] (2) Support loading: A certain amount of baked catalyst support was placed in a three-necked flask under an inert atmosphere, and 1 wt% platinum powder was added. The flask was dried at 300°C by mechanical stirring and electric heating. After the flask wall was free of water mist, the drying was maintained for 4 hours. After cooling, 2 wt% sodium metal and 1 wt% potassium metal were added, and then the mixture was stirred at 350°C for 3 hours to prepare CAT-2, a propylene dimerization catalyst with silver-gray particles.

[0066] Example 3

[0067] The method is the same as in Example 1, except that in step (2), the amount of platinum powder added is 0.2 wt%.

[0068] The resulting propylene dimerization catalyst was designated CAT-3.

[0069] Example 4

[0070] The method is the same as in Example 1, except that in step (2), the amount of platinum powder added is 3 wt%.

[0071] The resulting propylene dimerization catalyst was designated CAT-4.

[0072] Example 5

[0073] The method of Example 1 is different in that 1 wt% of platinum powder based on the mass of anhydrous potassium carbonate is placed in a vacuum crucible furnace together with 40-60 mesh carrier particles in step (1), and baked with air at 500°C and normal pressure for 6 hours. Then it is placed in a three-necked flask under an inert atmosphere and dried at 350°C by mechanical stirring and electric heating. After the flask wall is free of water mist, it is maintained for 2 hours. After cooling, 2.2 wt% of metallic sodium and 2.8 wt% of metallic potassium are added, and then stirred at 350°C for 4 hours to prepare the silver-gray propylene dimerization catalyst CAT-5.

[0074] Comparative Example 1

[0075] (1) Carrier treatment: Anhydrous potassium carbonate was sieved, graded and mixed according to the Rosin-Rammler distribution (RR distribution) disclosed in patent EP0083083; based on the mass of anhydrous potassium carbonate (RR distribution potassium carbonate), 1 wt% graphite and 2.5 wt% guar gum powder were added and mixed evenly. Then, the mixture was pressed into tablets using an electric tablet press at a pressure of 20 MPa and a holding time of 5 min; the pressed tablets were crushed and sieved, and the 40-60 mesh (300-450 nm) carrier particles were placed in a vacuum crucible furnace and baked with air at 500℃ and normal pressure for 6 h to prepare the catalyst carrier.

[0076] (2) Support loading: A certain amount of baked catalyst support was placed in a three-necked flask under an inert atmosphere and dried at 350°C by mechanical stirring and electric heating. After the flask wall was free of water mist, it was maintained for 2 hours. After cooling, 2.2 wt% of metallic sodium and 2.8 wt% of metallic potassium were added, and then stirred at 350°C for 4 hours to prepare silver-gray propylene dimerization catalyst DCAT.

[0077] Test case

[0078] Under a nitrogen atmosphere, the catalysts prepared in the above examples and comparative examples were transferred to the reactor and connected to a high-pressure microreactor. The raw material propylene was fed into the reactor through a high-pressure constant flow pump and sequentially through a deoxygenation and dehydration pretreatment system to carry out the reaction of propylene dimerization to prepare 4-methyl-1-pentene. The polymerization reaction conditions are shown in Table 1. A portion of the reaction product was diverted through a six-way valve to gas chromatography for online analysis, and the remaining product was collected in a cold trap collection bottle.

[0079] Product analysis: Gas chromatography analysis of the products was performed using a PONA column (50m×200μm×0.5μm), detector temperature 300℃, injection port temperature 250℃, split ratio 1:200, and temperature programmed conditions: initial temperature 35℃, constant temperature for 15 min, then increased to 65℃ at 2℃ / min, and then increased to 250℃ at 20℃ / min; the product analysis results are listed in Table 1.

[0080] Table 1

[0081]

[0082] Stability test:

[0083] The catalysts prepared in Example 1 and Comparative Example 1 were subjected to polymerization at a temperature of 170°C, a pressure of 11 MPa, and a space velocity of 1.0 h⁻¹. -1 Stability tests were conducted under these conditions. Timing began after the catalyst's polymerization performance stabilized under these conditions (approximately 12 hours). The high-temperature deactivation data obtained are shown in Table 2.

[0084] Table 2

[0085]

[0086]

[0087] As can be seen from the results of CAT-1 and the comparative example DCAT in Table 1 of Example 1, under the same polymerization conditions, the polymerization performance of the propylene dimerization catalyst prepared by the method of the present invention is more than doubled when the 4M1P selectivity is approximately the same. Comparing the data in the second and third columns of Table 1, it can be seen that CAT-1 has similar catalytic performance at different polymerization reaction temperatures and space velocities, providing multiple polymerization conditions for the subsequent industrial application of the catalyst. Meanwhile, according to the stability test data in Table 2, the propylene dimerization catalyst of the present invention can effectively slow down the deactivation process at high temperatures compared to the comparative example. At 170°C, the half-life increased from 100 min in the comparative example to 140 min, and the conversion rate after 160 min increased from 38% to 46% of the initial conversion rate. These data demonstrate that the catalyst of the present invention has superior high-temperature stability.

[0088] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst, characterized in that, The catalyst comprises a support and an active metal component and an auxiliary metal component supported on the support; wherein the support comprises potassium carbonate and a binder, the active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of noble metals; Based on the mass of the carrier, the content of the active metal component is 1-20 wt% and the content of the auxiliary metal component is 0.1-10 wt%, calculated by metal element.

2. The catalyst according to claim 1, wherein, The active metals include sodium and potassium; Preferably, in the active metal component, the mass ratio of sodium to potassium, calculated by element, is 1-5:5-1; Preferably, the active metal component exists in elemental form.

3. The catalyst according to claim 1 or 2, wherein, The auxiliary metal component is selected from at least one of platinum, rhodium and palladium, preferably platinum; Preferably, the auxiliary metal component exists in elemental form.

4. The catalyst according to any one of claims 1-3, wherein, Based on the mass of the carrier, the content of the active metal component is 2-10 wt% and the content of the auxiliary metal component is 0.5-2.5 wt%, calculated by metal element. Preferably, the mass ratio of the active metal component to the auxiliary metal component, based on metal elements, is 1:(0.01-1), more preferably 1:(0.1-0.5).

5. A method for preparing a catalyst, characterized in that, The preparation method includes: (1) Potassium carbonate, binder and guar gum powder are mixed and molded to obtain a carrier; (2) Loading the active metal component and the auxiliary metal component onto the carrier; The active metal component is selected from sodium and / or potassium, and the auxiliary metal component is selected from at least one of noble metals. Based on the mass of the carrier, the loading of the active metal component is 1-20 wt% and the loading of the auxiliary metal component is 0.1-10 wt%, calculated by metal element.

6. The preparation method according to claim 5, wherein, In step (1), based on the mass of potassium carbonate, the amount of binder is 0.5-5 wt%, preferably 0.75-3 wt%. Preferably, in step (1), the amount of guar gum powder used is 0.1-20 wt%, preferably 1-10 wt%, based on the mass of potassium carbonate; Preferably, in step (1), the molding method is tablet molding; Preferably, step (1) further includes: optionally crushing and sieving the shaped product to a particle size of 250-500 nm, preferably 300-450 nm.

7. The preparation method according to claim 5 or 6, wherein, The molding and calcination are carried out in an oxygen-containing atmosphere; Preferably, the molding and baking temperature is 100-800℃, and more preferably 300-600℃; Preferably, the molding and baking time is 1-10 hours, and more preferably 2-8 hours.

8. The preparation method according to any one of claims 5-7, wherein, Step (2) includes: (2-1) Under a protective atmosphere, the carrier and the auxiliary metal are first mixed; (2-2) The product obtained in step (2-1) is mixed with the active metal in a second process; Preferably, the temperature of the first mixing is 50-400℃, more preferably 100-300℃; the time is 1-8h, more preferably 2-4h. Preferably, the temperature of the second mixing is 100-600℃, more preferably 200-400℃; and the time is 0.5-8h, more preferably 1-6h. Preferably, the protective atmosphere is provided by at least one of nitrogen, argon, neon and helium.

9. A method for preparing 4-methyl-1-pentene by propylene dimerization, the method comprising: In an inert atmosphere, propylene is brought into contact with a catalyst to carry out selective polymerization of propylene; The catalyst is characterized in that it is the catalyst according to any one of claims 1-4 or the catalyst prepared by the preparation method according to any one of claims 5-8.

10. The method according to claim 9, wherein, The contact conditions include: a reaction pressure of 4-16 MPa, preferably 6-12 MPa; a reaction temperature of 120-180°C, preferably 140-160°C; and a liquid hourly space velocity of 0.2-6 h⁻¹. -1 Preferably 0.6-2.4h -1 .

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