Propylene dimerization catalyst, process for its preparation and use, and process for propylene dimerization
By using K-modified alumina as a support to support alkali metal catalysts, the problems of low conversion rate and poor flowability of propylene dimerization catalysts were solved, achieving high conversion rate and stable selectivity of dimerization products, which is suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-10-31
- Publication Date
- 2026-07-14
AI Technical Summary
Existing propylene dimerization catalysts have low conversion rates, require harsh reaction conditions, and have poor flowability, making them difficult to use for industrial production.
K-modified alumina was used as a support to support alkali metal catalysts. The catalysts were prepared by two calcinations to improve their flowability and activity, ensuring high conversion and selectivity.
The catalyst achieves a propylene conversion rate of up to 98.2% at a liquid hourly space velocity of 0.6 h⁻¹, exhibits stable selectivity for the dimer product, and demonstrates excellent flowability, making it suitable for industrial applications.
Smart Images
Figure BDA0003919379870000021 
Figure BDA0003919379870000022 
Figure BDA0003919379870000121
Abstract
Description
Technical Field
[0001] This invention relates to the field of propylene dimerization catalysts, specifically to a propylene dimerization catalyst, its preparation method and application, and a propylene dimerization reaction method. Background Technology
[0002] Propylene dimerization is an important method for preparing C6 olefins, yielding various higher olefin products including 1-pentene, 4-methyl-1-pentene, 2-methyl-2-pentene, and 4-methyl-2-pentene. These dimerization products can be used as monomers to polymerize other high-performance polymers, such as linear low-density polyethylene (LLDPE) resin with excellent impact resistance, tensile tear strength, and dielectric properties, and poly(4-methyl-1-pentene) (PMP), which is widely used in the automotive, aerospace, optics, and medical device industries. They can also serve as precursors for detergents, synthetic oils, and plasticizers in human society.
[0003] The main technical routes for propylene dimerization include two methods: alkali metal catalysis and metallocene complex catalysis. The latter mostly uses transition metals as catalytic centers and cannot simultaneously achieve propylene dimerization conversion and selectivity. The former is based on the principle of carbanion and adjusts the degree of polymerization of the reaction by the activity difference between different carbanions, thus having a higher dimer selectivity. It is also the route most studied by domestic and foreign institutions. The relevant reaction mechanism is shown in equation (1): First, propylene generates allyl anion A under alkali metal catalysis (not drawn in conjugated form for easier expression). The anion intermediate preferentially attacks the C2 in the double bond of the raw material propylene, which is in an electron-deficient state, to generate dimer intermediate B. Then, B undergoes proton exchange with propylene to obtain the allyl anion and the Markovnikov dimer product 4-methyl-1-pentene (route A). At the same time, allyl anion A also attacks the electronegative terminal carbon in propylene to obtain carbanion intermediate C, which also undergoes proton exchange with propylene to obtain the kinetically disadvantaged anti-Markovnikov byproduct 1-hexene (route B). Furthermore, since allyl anion A has better stability than 4M1P anion B and 1-hexene anion C, it has a relatively high concentration in the reaction system, which can inhibit the tendency of the reaction to continue to polymerize and form trimers or polymers to a certain extent, thus giving the polymerization reaction a high dimer selectivity.
[0004]
[0005] Furthermore, under specific catalytic conditions, the dimer can undergo isomerization reactions, with the corresponding reaction mechanisms shown in equations (2)-(4): First, the carbanion attacks the α-carbon atom of 4M1P to obtain carbanion intermediate D, which is then isomerized to intermediate E. Species E undergoes proton exchange with propylene to obtain the isomer 4-methyl-2-pentene. 4-methyl-2-pentene also undergoes a similar isomerization reaction under the action of the carbanion to obtain intermediate F, which then undergoes proton exchange with the isomerized carbanion G to generate 2-methyl-2-pentene. Under environmental conditions, 2-methyl-2-pentene can also undergo a similar reaction process to generate 2-methyl-1-pentene via the isomerization intermediate H. In addition, the byproduct 1-hexene generated in the first step also undergoes isomerization to generate isomers including 2-hexene and 3-hexene. Since the reaction process is similar, it will not be described in detail here.
[0006]
[0007] Based on the above-mentioned reaction mechanism of alkali metal-catalyzed propylene dimerization, the polymerization reaction requires the carbanion intermediates generated by the catalyst to reach a certain concentration before it can occur. Therefore, the single-pass conversion rate of the raw materials is usually low. Although the conversion rate can be improved by recycling a large amount of raw materials, the extra separation and purification steps will bring additional power consumption and unavoidable material loss, and increase the environmental impact factors and risk level of the reaction device. In addition, the poor flowability of alkali metal catalysts can be ignored in laboratory scale, but given their sensitivity to water and oxygen, an inert atmosphere must be maintained throughout the transfer process. The realization of industrial production will inevitably place higher requirements on the flowability and other properties of the catalyst.
[0008] Therefore, the development of an alkali metal catalyst for propylene dimerization with high catalytic activity and excellent comprehensive performance is urgently needed to realize the industrial production of propylene dimerization, thereby safeguarding people's health and meeting the needs of the masses for a rich and better life. Summary of the Invention
[0009] The purpose of this invention is to overcome the problems of low propylene conversion and harsh reaction conditions in the prior art, and to provide a propylene dimerization catalyst, its preparation method and application, and a propylene dimerization reaction method. This catalyst has high propylene dimerization catalytic activity, high propylene conversion, and good C6 olefin selectivity.
[0010] To achieve the above objectives, a first aspect of the present invention provides a propylene dimerization catalyst, the catalyst comprising a support and an active metal supported on the support;
[0011] The carrier is K-modified alumina, wherein the K content (calculated as K2CO3) in the carrier is 10-40 wt%, the alumina content is 60-90 wt%, and the active metal is selected from at least one of alkali metals.
[0012] A second aspect of this invention provides a method for preparing a propylene dimerization catalyst, comprising the following steps:
[0013] (1) A soluble compound containing K is brought into contact with an alumina support, and then subjected to a first calcination to obtain the support;
[0014] The amount of soluble compound containing K and alumina carrier used is such that the content of K (calculated as K2CO3) in the prepared carrier is 10-40 wt% and the content of alumina is 60-90 wt%.
[0015] (2) Under an inert atmosphere, the carrier is mixed with an active metal and subjected to a second calcination;
[0016] The active metal is selected from at least one of the alkali metals.
[0017] A third aspect of the present invention provides a propylene dimerization catalyst prepared by the above-described preparation method.
[0018] The fourth aspect of the present invention provides the application of the propylene dimerization catalyst described in the first or third aspect in the propylene dimerization reaction.
[0019] The fifth aspect of the present invention provides a method for propylene dimerization, the method comprising: contacting propylene with a catalyst under an inert atmosphere;
[0020] The catalyst is the propylene dimerization catalyst described in the first or third aspect.
[0021] The beneficial effects achieved by the present invention through the above technical solutions are as follows:
[0022] The propylene dimerization catalyst provided by this invention uses K-modified alumina as a support to support alkali metals. This catalyst exhibits high catalytic activity, particularly at a liquid hourly space velocity (LHSV) of 0.6 h⁻¹. -1 Under suitable polymerization conditions, it exhibits a propylene conversion rate as high as 98.2%. In addition, it has a high selectivity for 2-methyl-2-pentene, and the selectivity of the dimer product hardly changes with the increase of liquid hourly space velocity in the polymerization reaction, which greatly reduces the complexity of adjusting the reaction conditions during industrial polymerization. Furthermore, the catalyst loaded with alkali metals does not agglomerate, has excellent fluidity, and can be easily transferred to the reactor. There is no pulverization after the dimerization reaction, which shows broad prospects for industrial application. Detailed Implementation
[0023] 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.
[0024] The first aspect of the present invention provides a propylene dimerization catalyst, the catalyst comprising a support and an active metal component supported on the support;
[0025] The carrier is K-modified alumina, wherein the K content (calculated as K2CO3) in the carrier is 10-40 wt%, the alumina content is 60-90 wt%, and the active metal component is selected from at least one of alkali metals.
[0026] Existing propylene dimerization catalysts typically use anhydrous potassium carbonate as the catalyst matrix, upon which active metal components are supported. However, the catalyst has poor flowability. Given the need for an inert atmosphere during use, the difficulty of transferring the catalyst in industrial applications increases dramatically, thus limiting its application potential. Furthermore, the low conversion efficiency also increases energy consumption and risks during its use.
[0027] The inventors of this invention discovered in their research that by using K-modified alumina as a support to load alkali metals, the catalyst exhibits excellent fluidity. Through the synergistic effect of the K-modified alumina support and the active metal, the catalyst has a short induction period and extremely high catalytic activity in the propylene dimerization reaction, resulting in a high propylene conversion rate.
[0028] In this invention, K-modified alumina helps to increase the pore volume and specific surface area of the catalyst, making the active components of the shaped catalyst more dispersed and improving the overall performance of the catalyst. Preferably, the content of K in the support, calculated as K2CO3, is 15-30 wt%, and the content of alumina is 70-85 wt%. It should be noted that the form of K in the support is not limited to potassium carbonate; this is only a uniform measurement method.
[0029] In this invention, the component content is obtained by ICP testing.
[0030] According to the present invention, preferably, the specific surface area of the carrier is 40-80 m². 2 / g, preferably 50-60m 2 / g.
[0031] Preferably, the pore volume of the carrier is 0.1-1 mL / g, more preferably 0.3-0.7 mL / g.
[0032] In this invention, the specific surface area and pore volume of the carrier are obtained by BET testing.
[0033] In this invention, the source of the alumina is broadly selectable, and it can be commercially available or prepared using conventional methods. The crystal form of the alumina is also broadly selectable; for example, at least one of α-Al₂O₃, β-Al₂O₃, and γ-Al₂O₃ can be used, preferably γ-Al₂O₃. Under these preferred conditions, it is beneficial to further improve the propylene conversion rate of the catalyst.
[0034] In this invention, the selection range for the content of the active metal is relatively wide. Preferably, based on the mass of the catalyst support, the content of the active metal component is 1-20 wt% (elemental basis). More preferably, based on the mass of the catalyst support, the content of the active metal component is 2-10 wt% (elemental basis). Under the above preferred conditions, it is beneficial to achieve high activity of the catalyst for the propylene dimerization reaction.
[0035] In this invention, the active metal component exists in a metallic state.
[0036] Preferably, the active metal component is Na and / or K, more preferably Na and K; the synergistic effect of Na and K helps to ensure catalyst activity while maintaining high selectivity.
[0037] Preferably, the mass ratio of Na to K is 0.2-5:1, more preferably 0.5-2:1. Under these preferred conditions, the synergistic effect of Na and K can be further enhanced, thereby improving the activity of the catalyst.
[0038] A second aspect of this invention provides a method for preparing a propylene dimerization catalyst, comprising the following steps:
[0039] (1) A soluble compound containing K is brought into contact with an alumina support, and then subjected to a first calcination to obtain the support;
[0040] The amount of soluble compound containing K and alumina carrier is such that the content of K2CO3 in the prepared carrier is 10-40 wt% and the content of alumina is 60-90 wt%.
[0041] (2) Under an inert atmosphere, the carrier is mixed with an active metal and subjected to a second calcination;
[0042] The active metal is selected from at least one of the alkali metals.
[0043] According to the present invention, preferably, the amount of the soluble compound containing K and the alumina support is such that the content of K in the prepared support, calculated as K2CO3, is 15-30 wt%, and the content of alumina is 70-85 wt%. It should be noted that the form of K in the support is not limited to potassium carbonate; this is only a uniform measurement method.
[0044] According to the present invention, preferably, in step (1), the contact includes: impregnating the alumina support with a solution of a soluble compound containing potassium (K). The present invention does not impose any particular limitation on the specific operation of the impregnation; conventional methods in the art can be used, as long as the K content in the support meets the above-mentioned range. Preferably, the impregnation time is 0.5-8 hours.
[0045] In this invention, preferably, the conditions for the first calcination include: a calcination temperature of 200-800℃, more preferably 400-600℃, for example, any one of 400℃, 450℃, 500℃, 520℃, 540℃, 560℃, 580℃, and 600℃, or a temperature range between the two; adopting the above-mentioned preferred first calcination conditions is beneficial to the subsequent loading of active metals, ensuring the maintenance of alkali metal activity during the loading process, and further improving the catalyst activity. Preferably, the calcination time is 2-10 hours, more preferably 4-8 hours.
[0046] In this invention, to ensure the uniformity of the carrier, the preparation method preferably further includes drying the product after the first calcination. The drying can be performed using conventional operations and conditions in the art. Preferably, the drying includes drying at 100-400°C for 0.5-4 hours in the presence of an inert atmosphere. The inert atmosphere is preferably nitrogen.
[0047] In this invention, the source of the alumina support is not particularly limited; it can be commercially available or prepared using conventional methods in the art. This invention also allows for a wide range of choices regarding the crystal form of the alumina; for example, at least one of α-Al₂O₃, β-Al₂O₃, and γ-Al₂O₃ can be used, preferably γ-Al₂O₃. Under these preferred conditions, it is beneficial to further improve the propylene conversion rate of the catalyst.
[0048] Preferably, the specific surface area of the alumina carrier is 40-160 m². 2 / g, preferably 60-120m 2 / g.
[0049] Preferably, the pore volume of the alumina support is 0.4-1 mL / g, and more preferably 0.6-0.8 mL / g.
[0050] In this invention, there are no particular limitations on the morphology and particle size of the alumina support, and those skilled in the art can select according to actual needs. To obtain the target support morphology and size, preferably, the preparation method further includes: pulverizing and sieving the alumina support. The pulverization and sieving can be performed using conventional methods in the art, and this invention does not impose any particular limitations on this. Preferably, through pulverization and sieving, the particle size of the alumina support is 10-100 mesh, more preferably 40-60 mesh.
[0051] In this invention, the soluble compound containing K is selected from at least one of potassium carbonate, potassium bicarbonate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium sulfate, and potassium bisulfate.
[0052] According to the present invention, preferably, the active metal is Na and / or K, more preferably Na and K. The synergistic effect of Na and K helps to ensure catalyst activity, improve propylene conversion, and enhance product selectivity.
[0053] Preferably, in the active metal, the mass ratio of Na to K, based on elemental composition, is 0.2-5:1, more preferably 0.5-2:1. Under these preferred conditions, the synergistic effect of Na and K can be further enhanced, thereby improving the catalyst activity.
[0054] According to the present invention, preferably, in step (2), the conditions for the second calcination include: a calcination temperature of 100-600℃, preferably 200-400℃; and a calcination time of 0.5-8h, preferably 1-3h. The inert atmosphere is preferably nitrogen.
[0055] In this invention, the terms "first roasting" and "second roasting" do not refer to the order of operations, but are only used to distinguish the roasting conditions in different steps.
[0056] A third aspect of the present invention provides a propylene dimerization catalyst prepared by the above-described preparation method.
[0057] The fourth aspect of the present invention provides the application of the above-mentioned propylene dimerization catalyst in the propylene dimerization reaction.
[0058] The fifth aspect of the present invention provides a method for propylene dimerization, the method comprising: contacting propylene with a catalyst under an inert atmosphere; wherein the catalyst is the propylene dimerization catalyst described in the first or third aspect.
[0059] Preferably, the contact conditions include: a reaction pressure of 4-16 MPa, more preferably 6-12 MPa; a reaction temperature of 120-180°C, more preferably 140-160°C; and a liquid hourly space velocity of 0.2-6 h⁻¹. -1 Preferably 0.6-4h-1 .
[0060] The propylene dimerization method provided by this invention offers a wide range of reaction condition selection. It achieves high propylene conversion, and the selectivity for 2-methyl-2-pentene remains almost unchanged with increasing liquid hourly space velocity (LHSV) during polymerization. Furthermore, it maintains relatively stable 2-methyl-2-pentene selectivity over a wide LHSV range, which is beneficial for ensuring product stability in industrial production. This keeps subsequent product distillation conditions within a small fluctuation range, reducing energy consumption and capital investment in distillation columns. It significantly reduces the complexity of adjusting reaction conditions during industrial polymerization, especially at LHSVs of 0.6 h⁻¹. -1 Under the polymerization conditions, it has a propylene conversion rate as high as 98.2%.
[0061] 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.
[0062] Preferably, the contact is performed in a high-voltage microreactor.
[0063] The present invention will be described in detail below through embodiments.
[0064] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available.
[0065] Example 1
[0066] (1) Carrier treatment: 1.78 mm diameter spherical γ-alumina carrier (pore volume 0.702 mL / g, specific surface area 95.693 m²) was used. 2 / g) The alumina support was crushed and sieved. 40-60 mesh (300-450 nm) particles were placed in a beaker containing a saturated potassium carbonate aqueous solution and soaked for 3 hours. The filtered-off support particles were then transferred to a vacuum crucible furnace and calcined at 500℃ under normal pressure for 6 hours to obtain the K-modified alumina support. The physicochemical properties of the support are shown in Table 1.
[0067] (2) Support loading: A certain amount of the baked support was placed in a three-necked flask under a nitrogen atmosphere and dried at 350°C using mechanical stirring and electric heating. After the flask wall was free of water mist, the drying process was maintained for 2 hours. After cooling, 1.3 wt% sodium metal and 1.7 wt% potassium metal were added based on the weight of the support. Subsequently, a second calcination was carried out at 350°C for 4 hours to prepare a gray-black powder propylene dimerization catalyst A1. The catalyst composition is shown in Table 2.
[0068] Test characterization:
[0069] Catalyst A1 was transferred to the reactor under an inert atmosphere and connected to a high-pressure microreactor. Propylene feedstock was fed into the reactor via a high-pressure constant-flow pump, passing through a deoxygenation and dehydration pretreatment system sequentially. The reaction pressure was 11 MPa, the reaction temperature was 150 °C, and the liquid hourly space velocity (LHSV) was 0.6 h⁻¹. -1 The reaction products are partially diverted and sent to a gas chromatograph for online analysis via a six-way valve, while the remaining products are collected in a cold trap collection bottle.
[0070] Gas chromatography analysis of the products was performed using a PONA column (50m×200μm×0.5μm), with a detector temperature of 300℃, an injection port temperature of 250℃, a split ratio of 1:200, and a programmed temperature rise of 35℃ for 15 min, followed by a rise at 2℃ / min to 65℃, and then a rise at 20℃ / min to 250℃. The product analysis results are listed in Table 2.
[0071] The reaction time velocity was adjusted according to Table 2, and the reaction results at different liquid hourly space velocities are shown in Table 2.
[0072] Example 2
[0073] (1) Carrier treatment: 1.78 mm diameter spherical γ-alumina carrier (pore volume 0.702 mL / g, specific surface area 95.693 m²) was used. 2 / g) The alumina support was crushed and sieved. 40-60 mesh (300-450 nm) particles were placed in a beaker containing a saturated potassium carbonate aqueous solution and soaked for 2 hours. The filtered-off support particles were then transferred to a vacuum crucible furnace and calcined at 500℃ under normal pressure for 6 hours to obtain the K-modified alumina support. The physicochemical properties of the support are shown in Table 1.
[0074] (2) Support loading: A certain amount of the baked support was placed in a three-necked flask under a nitrogen atmosphere and dried at 350°C using mechanical stirring and electric heating. After the flask wall was free of water mist, the drying process was maintained for 2 hours. After cooling, 3 wt% sodium metal and 4 wt% potassium metal were added based on the weight of the support, followed by a second calcination at 350°C for 4 hours to prepare a gray-black powder propylene dimerization catalyst A2. The catalyst composition is shown in Table 2.
[0075] Example 3
[0076] (1) Carrier treatment: 1.78 mm diameter spherical γ-alumina carrier (pore volume 0.702 mL / g, specific surface area 95.693 m²) was used. 2 / g) The alumina support was crushed and sieved. 40-60 mesh (300-450 nm) particles were placed in a beaker containing a saturated potassium carbonate aqueous solution and soaked for 5 hours. The filtered-off support particles were then transferred to a vacuum crucible furnace and calcined at 500℃ under normal pressure for 6 hours to obtain the K-modified alumina support. The physicochemical properties of the support are shown in Table 1.
[0077] (2) Support loading: A certain amount of baked support was placed in a three-necked flask under a nitrogen atmosphere and dried at 350°C by mechanical stirring and electric heating. After the flask wall was free of water mist, the drying time was maintained for 2 hours. After cooling, 3 wt% metallic sodium was added based on the weight of the support, followed by a second calcination at 350°C for 4 hours to prepare a gray-black powder propylene dimerization catalyst A3. The catalyst composition is shown in Table 2.
[0078] Example 4
[0079] The method of Example 1 was followed, except that, based on the weight of the carrier, the amount of sodium metal added was 4.4 wt% and the amount of potassium metal added was 5.6 wt%, and the resulting catalyst was designated A4. The product analysis results of propylene dimerization are listed in Table 3.
[0080] Example 5
[0081] Following the method of Example 1, except that an equal mass of metallic sodium was used to replace metallic potassium, the resulting catalyst was designated A5, and the product analysis results of propylene dimerization are listed in Table 3.
[0082] Example 6
[0083] The method of Example 1 is followed, except that the amount of saturated potassium carbonate aqueous solution used is such that the content of K2CO3 in the K-modified alumina support is 5.6 wt%, and the physicochemical properties of the support are shown in Table 1.
[0084] The obtained catalyst was designated A6, and the product analysis results of propylene dimerization are listed in Table 3.
[0085] Example 7
[0086] The method is the same as in Example 1, except that the temperature of the first calcination in step (1) is 300°C, and the physicochemical properties of the carrier are shown in Table 1.
[0087] The obtained catalyst was designated A7, and the product analysis results of propylene dimerization are listed in Table 3.
[0088] Example 8
[0089] The method described in Example 1 was followed, except that the γ-alumina support was passivated at 950°C for 5 hours before use to convert the γ-alumina into α-alumina. Then, K modification was performed according to the method described in Example 1, and the physicochemical properties of the resulting support are shown in Table 1.
[0090] Step (2) is the same as the method in Example 1, and the resulting catalyst is designated as A8. The product analysis results of propylene dimerization are shown in Table 3.
[0091] Comparative Example 1
[0092] (1) Carrier treatment: Anhydrous potassium carbonate was sieved, graded, and mixed according to the Rosin-Rammler distribution (RR distribution) disclosed in patent EP0083083; 1 wt% graphite and 2.5 wt% guar gum powder were added to a certain amount of prepared anhydrous potassium carbonate (RR distribution potassium carbonate), and after mixing evenly, it was compressed into tablets using an electric tablet press under a pressure of 20 MPa and a holding time of 5 min; the compressed 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. The physicochemical properties of the carrier are shown in Table 1.
[0093] (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, 1.3 wt% of metallic sodium and 1.7 wt% of metallic potassium were added, and then stirred at 350°C for 4 hours to prepare propylene dimerization catalyst DA1 as a gray-black powder.
[0094] The performance was characterized according to the method in Example 1, and the product analysis results of propylene dimerization are shown in Table 3.
[0095] Table 1 Physicochemical properties of the carrier
[0096]
[0097]
[0098] Table 2. Reaction results of catalyst A1 at different liquid hourly space velocities.
[0099]
[0100] Table 3
[0101]
[0102] As can be seen from the results in Tables 2 and 3, the propylene dimerization catalyst prepared by the method of the present invention using alumina as a support for alkali metals has the advantage of high activity, especially at a liquid hourly space velocity of 0.6 h⁻¹. -1 Under suitable polymerization conditions, it exhibits a propylene conversion rate as high as 98.2%; the selectivity of the dimer product hardly changes with the increase of the liquid hourly space velocity in the polymerization reaction, greatly reducing the complexity of adjusting the reaction conditions during industrial polymerization; in addition, the catalyst loaded with alkali metals does not agglomerate or clump, has excellent fluidity, can be easily transferred to the reactor, and does not pulverize after the dimerization reaction, showing broad prospects for industrial application.
[0103] 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 propylene dimerization catalyst, characterized in that, The catalyst includes a support and an active metal component supported on the support; The carrier is K-modified alumina, wherein the content of K (calculated as K2CO3) in the carrier is 10-40 wt%, the content of alumina is 60-90 wt%, the active metal component is selected from at least one alkali metal, and the alumina is γ-Al2O3; based on the mass of the carrier, the content of the active metal component is 2-7 wt% by elemental basis. The specific surface area of the carrier is 40-80 m². 2 / g, pore volume is 0.1-1mL / g.
2. The catalyst according to claim 1, wherein, The carrier contains 15-30 wt% K (calculated as K2CO3) and 70-85 wt% alumina.
3. The catalyst according to claim 1 or 2, wherein, The specific surface area of the carrier is 50-60 m². 2 / g.
4. The catalyst according to claim 1 or 2, wherein, The pore volume of the carrier is 0.3-0.7 mL / g.
5. The catalyst according to claim 1 or 2, wherein, The active metal component is Na and / or K.
6. The catalyst according to claim 5, wherein, The active metal components are Na and K.
7. The catalyst according to claim 6, wherein, In the active metal component, the mass ratio of Na to K, calculated by element, is 0.2-5:
1.
8. The catalyst according to claim 7, wherein, In the active metal component, the mass ratio of Na to K, calculated by element, is 0.5-2:
1.
9. The catalyst according to claim 1 or 2, wherein, The active metal component exists in a metallic state.
10. A method for preparing a propylene dimerization catalyst, characterized in that, Includes the following steps: (1) A soluble compound containing K is brought into contact with an alumina support, and then subjected to a first calcination to obtain the support; The alumina support is γ-Al₂O₃, and the specific surface area of the alumina support is 40-160 m². 2 / g, pore volume is 0.4-1mL / g; The amount of soluble K-containing compounds and alumina carrier used is such that the content of K (calculated as K2CO3) in the prepared carrier is 10-40 wt%, and the content of alumina is 60-90 wt%. (2) Under an inert atmosphere, the carrier is mixed with the active metal and subjected to a second calcination; The active metal is selected from at least one of alkali metals, and the amount of the active metal is 2-7 wt% based on the mass of the carrier and by element.
11. The preparation method according to claim 10, wherein, The amount of soluble K-containing compound and alumina carrier used is such that the content of K (calculated as K2CO3) in the prepared carrier is 15-30 wt%, and the content of alumina is 70-85 wt%.
12. The preparation method according to claim 10 or 11, wherein, In step (1), the contact includes: impregnating the alumina carrier with a solution of a soluble compound containing K.
13. The preparation method according to claim 12, wherein, The soaking time is 0.5-8 hours.
14. The preparation method according to claim 11, wherein, The conditions for the first roasting include: a roasting temperature of 200-800℃ and a roasting time of 2-10h.
15. The preparation method according to claim 10 or 11, wherein, The specific surface area of the alumina carrier is 60-120 m². 2 / g.
16. The preparation method according to claim 10 or 11, wherein, The alumina support has a pore volume of 0.6-0.8 mL / g.
17. The preparation method according to claim 10 or 11, wherein, The soluble compound containing K is selected from at least one of potassium carbonate, potassium bicarbonate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium sulfate, and potassium bisulfate.
18. The preparation method according to claim 10 or 11, wherein, The active metal is Na and / or K.
19. The preparation method according to claim 18, wherein, The active metals are Na and K.
20. The preparation method according to claim 19, wherein, The mass ratio of metallic Na to metallic K is 0.2-5:
1.
21. The preparation method according to claim 20, wherein, The mass ratio of metallic Na to metallic K is 0.5-2:
1.
22. The preparation method according to claim 10 or 11, wherein, In step (2), the conditions for the second roasting include: roasting temperature of 100-600℃ and roasting time of 0.5-8h.
23. The preparation method according to claim 10 or 11, wherein, The inert atmosphere is nitrogen.
24. The propylene dimerization catalyst prepared by the method according to any one of claims 10-23.
25. The use of the propylene dimerization catalyst according to any one of claims 1-9 and 24 in the propylene dimerization reaction.
26. A method for propylene dimerization, the method comprising: Propylene is brought into contact with the catalyst under an inert atmosphere; The catalyst is characterized in that it is a propylene dimerization catalyst according to any one of claims 1-9 and 24.
27. The method according to claim 26, wherein, The contact conditions include: reaction pressure 4-16 MPa, reaction temperature 120-180 °C, and liquid hourly space velocity (LISH) of 0.2-6 h⁻¹. -1 .
28. The method according to claim 27, wherein, The contact conditions include: reaction pressure 6-12 MPa; reaction temperature 140-160 °C; and liquid hourly space velocity (LISH) of 0.6-4 h⁻¹. -1 .