Propylene dimerization catalyst as well as preparation method and application thereof
By preparing a catalyst on a composite support on γ-alumina, a super-strong base site active center is formed, which solves the problems of insufficient activity and easy pulverization of propylene dimerization catalysts, and achieves high selectivity and long lifespan catalytic effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2026-01-06
- Publication Date
- 2026-04-17
AI Technical Summary
Existing propylene dimerization catalysts suffer from insufficient activity, poor selectivity for 4-methyl-1-pentene, and are prone to pulverization and disintegration.
A composite support, including γ-alumina, an inorganic salt modification layer, a transition metal and a graphite modification layer, is used to prepare the catalyst via vapor deposition and solvent methods, forming ultra-strong base active centers and enhancing the structural strength of the catalyst.
It improves the selectivity of 4-methyl-1-pentene and the service life of the catalyst, reduces the loss of active components, and ensures that the catalyst is not easily disintegrated or pulverized in industrial production.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation, specifically to a propylene dimerization catalyst, its preparation method, and its application. Background Technology
[0002] Propylene dimerization is an important method for preparing hexane-6 olefins, yielding various products such as hexene and 4-methyl-1-pentene. These products can be used industrially to prepare other high-performance polymers. This technology, developed in the 1960s, has gradually become a key technology for producing specialty olefins. As an olefin oligomerization reaction, propylene dimerization is mainly divided into acid-catalyzed and base-catalyzed reactions, but alkali metal catalysis is considered the primary method for obtaining 4-methyl-1-pentene industrially.
[0003] Alkali metal catalysis is based on the principle of carbanion. Propylene generates allyl anions under alkali metal catalysis. The anion intermediate attacks the double bond of the raw material propylene to obtain a dimer intermediate, which then undergoes proton exchange with propylene to obtain the dimer product.
[0004] Alkali metal catalysts have high selectivity for dimer products, but the single-pass conversion rate of raw materials is low. Catalyst disintegration and deactivation are prone to occur during industrial production. Once the catalyst is blocked downstream with the material, there is a high risk of fire when the equipment is dismantled, which has many impacts on industrial production.
[0005] Catalysts are the core of propylene dimerization technology. Patent CN117816146A discloses a catalyst containing alkali metal salts and silicates, which can effectively improve the support strength of the catalyst and thus improve the catalyst life. However, there is no interaction between silicates and the active components of the catalyst, which can easily lead to the loss of active components.
[0006] Patent CN117960219A discloses a catalyst whose main components are carbonate and fluorinated graphite. Fluorinated graphite is added to the catalyst, and the interaction between fluorinated graphite and carbonate is used to stabilize the active components. However, the main structure is prone to collapse and decomposition during use due to insufficient strength, which poses a huge risk during disassembly. Summary of the Invention
[0007] This invention provides a propylene dimerization catalyst, its preparation method, and its application, to solve the problems of insufficient activity, poor selectivity for 4-methyl-1-pentene, and easy pulverization and disintegration of the propylene dimerization catalyst.
[0008] In a first aspect, the present invention provides a propylene dimerization catalyst, comprising: a composite support, and an alkali metal supported on the composite support; The composite carrier includes γ-alumina and an inorganic salt modified layer loaded on the surface of γ-alumina; Transition metal and graphite modification layers loaded on the surface of an inorganic salt modified layer.
[0009] In one optional embodiment, the mass ratio of the inorganic salt modified layer to γ-alumina is (0.05-0.1):1; In one optional embodiment, the mass ratio of transition metal to γ-alumina is (0.01-0.03):1; In one alternative embodiment, the mass ratio of the graphite-modified layer to γ-alumina is (0.01-0.03):1.
[0010] In one optional embodiment, the mass ratio of alkali metal to γ-alumina is (0.03-0.075):1; The inorganic salt modified layer includes carbonates; In one optional embodiment, the inorganic salt modified layer includes at least one of K2CO3 and Na2CO3; In one optional embodiment, the inorganic salt modified layer further includes KOH; In one optional embodiment, the mass ratio of KOH to carbonate is (0.01-0.05):1; In one optional embodiment, the mass ratio of KOH to carbonate is (0.01-0.03):1. In one alternative embodiment, the transition metal is selected from at least one of Fe, Co, Ni, Zn, Cu, and Ti; In one alternative embodiment, the alkali metal is selected from at least one of Na and K; In one alternative embodiment, the alkali metals include Na and K; In one optional embodiment, the mass ratio of sodium to potassium in the alkali metal is (0.2-5):1; In one alternative embodiment, the average particle size of γ-alumina is 2-4 mm; In one optional embodiment, the specific surface area of γ-alumina is 45-160 m². 2 / g; In one alternative embodiment, the pore volume of the γ-alumina is 0.3-1 ml / g.
[0011] Secondly, the present invention also provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) γ-alumina was soaked in a strong alkaline solution, and then soaked in an inorganic salt solution and calcined to obtain a γ-alumina carrier with an inorganic salt modified layer. (2) A transition metal is formed on the surface of the inorganic salt modified layer of the γ-alumina support to obtain a transition metal covered γ-alumina support; (3) Graphite is formed on the surface of a transition metal-coated γ-alumina support to obtain a composite support; (4) An alkali metal layer is formed on the surface of the composite support to obtain the propylene dimerization catalyst.
[0012] In one optional embodiment, in step (1), the alkali in the strong alkali solution is KOH; In one optional embodiment, the concentration of the alkali in the strong alkali solution is 15-25 wt%. In one alternative embodiment, the soaking process in a strong alkaline solution is carried out under ultrasonic conditions; the soaking time is 4-8 hours.
[0013] In one alternative embodiment, soaking in a strong alkaline solution also includes a drying process.
[0014] In one optional embodiment, the drying temperature is 140-160°C; the drying time is 4-8 hours.
[0015] In one alternative embodiment, the concentration of the inorganic salt in the inorganic salt solution is 0.5-1.5 mol / L.
[0016] In one alternative embodiment, the inorganic salt in the inorganic salt solution includes carbonates; In one optional embodiment, the inorganic salt modified layer includes at least one of K2CO3 and Na2CO3; In one optional embodiment, the inorganic salt modified layer further includes KOH; In one optional embodiment, the mass ratio of KOH to carbonate is (0.01-0.05):1; In one optional embodiment, the calcination temperature is 450-500℃; the time is 2-6 hours. In one optional embodiment, the mass ratio of the inorganic salt modified layer to the γ-alumina in the inorganic salt modified layer γ-alumina carrier is (0.05-0.1):1.
[0017] In one alternative embodiment, immersion in an inorganic salt solution is performed under ultrasonic treatment; In one alternative embodiment, the soaking time in the inorganic salt solution is 20-28 hours.
[0018] In one alternative embodiment, the process includes a drying treatment after soaking in an inorganic salt solution and before calcination.
[0019] In one optional embodiment, the drying temperature is 100℃-120℃; the time is 1-3h.
[0020] In an alternative implementation, the calcination in step (2) is carried out in an inert gas.
[0021] In one alternative embodiment, in step (2), the transition metal is formed by vapor deposition of a transition metal organic salt followed by a reduction reaction; In one alternative embodiment, the transition metal organosalt is selected from at least one of the organosalts of Fe, Co, Ni, Zn, Cu, and Ti.
[0022] In one alternative embodiment, the transition metal organosalt is selected from at least one of acetylacetonate iron, bis(hexafluoroacetylacetonate)copper(II), and Ti(CH2tBu)4.
[0023] In one alternative embodiment, the reduced transition metal loading is 0.01-0.03 of the mass of the γ-alumina support.
[0024] In one alternative implementation, the vapor deposition is chemical vapor deposition.
[0025] In one alternative implementation, the reduction reaction is carried out under an H2 atmosphere.
[0026] In one alternative embodiment, the vapor deposition temperature is 300-350°C.
[0027] In one alternative embodiment, in step (3), the process of forming graphite involves immersing a transition metal-coated γ-alumina support in a graphite solution, followed by drying and calcination. In one optional embodiment, the solvent for the graphite solution is an organic solvent; In one alternative embodiment, the organic solvent is selected from tetrahydrofuran; In one optional embodiment, the concentration of graphite in the graphite solution is 0.1-1 mg / ml; In one alternative implementation, the soaking time is 1-3 hours.
[0028] In one alternative implementation, the impregnation is an over-impregnation.
[0029] In one optional embodiment, the drying temperature is 40-60°C; the drying time is 1-2 hours. In one optional embodiment, the calcination temperature is 250-350℃ and the time is 1-2 hours.
[0030] In one optional embodiment, the graphite solution is prepared by mixing graphite and an organic solvent and then subjecting the mixture to ultrasonic dispersion for 1-2 hours to obtain the graphite solution.
[0031] In one alternative embodiment, the process of forming an alkali metal layer on the surface of the composite carrier is to immerse the composite carrier in an alkali metal melt. In one alternative embodiment, the alkali metals include Na and K; In one alternative embodiment, the sodium-potassium mass ratio in the alkali metal is (0.2-5):1.
[0032] In one optional embodiment, the sodium-potassium mass ratio in the alkali metal is (0.5-1.5):1. In one alternative embodiment, the temperature of the alkali metal melt is 60-100°C higher than the melting point of the alkali metal; In one optional embodiment, the composite carrier is immersed in the alkali metal melt for 0.5-1.5 hours; In one alternative embodiment, the process of forming the alkali metal layer is carried out under stirring conditions; In one optional embodiment, the stirring speed is 50-200 rpm; In one optional embodiment, the stirring speed is 80-120 rpm; In one alternative embodiment, the mass ratio of alkali metal to γ-alumina is (0.03-0.075):1.
[0033] In one optional embodiment, the γ-alumina is further subjected to a calcination process under a nitrogen gas flow before being immersed in a strong alkaline solution; the calcination temperature is 900-1100℃; and the calcination time is 10-14h.
[0034] In one alternative embodiment, the average particle size of γ-alumina is 2-4 mm; In one optional embodiment, the specific surface area of γ-alumina is 45-160 m². 2 / g.
[0035] In one alternative embodiment, the specific surface area of γ-alumina is 80-120 m². 2 / g.
[0036] In one alternative embodiment, the pore volume of the γ-alumina is 0.3-1 ml / g.
[0037] In one alternative embodiment, the pore volume of the γ-alumina is 0.6-0.8 ml / g.
[0038] In one alternative embodiment, the process of forming an alkali metal layer on the surface of the composite carrier is carried out under anhydrous and oxygen-free conditions.
[0039] Thirdly, this application also provides the application of the propylene dimerization catalyst described above or the propylene dimerization catalyst prepared by the preparation method described above in the synthesis of 4-methyl-1-pentene.
[0040] The technical solution of this invention has the following advantages: 1. The present invention provides a propylene dimerization catalyst, comprising: a composite support, an alkali metal supported on the composite support; the composite support comprising γ-alumina; an inorganic salt modified layer supported on the surface of the γ-alumina; and a transition metal and graphite modified layer supported on the surface of the inorganic salt modified layer.
[0041] The propylene dimerization catalyst provided by this invention uses γ-alumina as the basic framework, which interacts with the super-strong base active centers formed by the alkali metal system. This effectively reduces the loss of active components and exposes more active centers. The super-strong base sites formed are more conducive to the generation of the active intermediate allyl carbanion, thereby improving the selectivity of 4-methyl-1-pentene. At the same time, the use of γ-alumina ensures the strength of the catalyst structure, making it less prone to disintegration and pulverization during industrial production, thus effectively extending its service life.
[0042] 2. The preparation method provided by the present invention uses vapor deposition, which can effectively introduce transition metal co-catalysts, change the distribution of products, and generate 4-methyl-1-pentene more efficiently.
[0043] 3. The preparation method provided by the present invention introduces graphite with excellent lubrication and binding properties into the catalyst system through a solvent method, which not only has certain catalytic activity, but also enhances the structural strength of the catalyst. Detailed Implementation
[0044] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.
[0045] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0046] The average particle size of γ-alumina is 3 mm, and its specific surface area is 100 m². 2 / g, pore volume is 0.7 ml / g.
[0047] Example 1 This embodiment provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) Place γ-alumina in a tube furnace at 1000℃ and calcine with nitrogen gas flow protection for 12 hours. Then immerse the γ-alumina in a 16.7wt% KOH aqueous solution and soak it under ultrasonic conditions for 6 hours. After removal, dry it at 150℃ for 6 hours. (2) Prepare a mixed aqueous solution (inorganic salt solution) containing K2CO3 and KOH, with a molar ratio of KOH to K2CO3 of 0.03:1; the total molar concentration of KOH and K2CO3 in the inorganic salt solution is 1 mol / L. Immerse the carrier treated with strong alkali into this inorganic salt solution (K2CO3 accounts for 10% of the mass of γ-alumina), soak it under ultrasonic action for 24 h, take out the soaked carrier, dry it at 110℃ for 2 h, and then calcine it at 480℃ for 4 h to obtain the γ-alumina carrier with an inorganic salt modified layer. After weighing, the mass ratio of the inorganic salt modified layer to the mass of γ-alumina is 0.06:1; (3) Formation of the transition metal layer Iron acetylacetone was selected as the transition metal organometallic salt. Iron acetylacetone was deposited on the surface of the modified support using chemical vapor deposition (CVD) at 325°C. A reduction reaction was then carried out in an H2 atmosphere to obtain a transition metal Fe-coated γ-alumina support. Weighing analysis showed that the mass ratio of transition metal Fe to γ-alumina was 0.02:1. (4) Formation of graphite modification layer Graphite powder was added to tetrahydrofuran and mixed, then ultrasonically dispersed for 1.5 h to obtain a graphite solution with a graphite concentration of 0.5 mg / ml. A transition metal-coated support was immersed in the graphite solution for 2 h, then dried at 50 °C for 1.5 h, followed by calcination at 300 °C for 1.5 h to obtain a composite support. Weighing analysis showed that the mass ratio of the graphite-modified layer to γ-alumina was 0.02:1. (5) Heat and melt sodium and potassium at a sodium-potassium mass ratio of 1:1 to obtain alkali metal melt. Immerse the composite carrier obtained in step (4) into the alkali metal melt, control the melt temperature to be 80°C higher than the melting point (the melting point when the sodium-potassium mass ratio is 1:1), soak for 1 hour under the condition of stirring speed of 100 rpm, take it out and cool it to obtain the propylene dimerization catalyst.
[0048] In the final catalyst, the mass ratio of alkali metal to γ-alumina is 0.05:1.
[0049] Example 2 This embodiment provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) Place γ-alumina in a tube furnace at 1000℃ and calcine with nitrogen gas flow protection for 12 hours. Then immerse the γ-alumina in a 16.7wt% KOH aqueous solution and soak it under ultrasonic conditions for 6 hours. After removal, dry it at 150℃ for 6 hours. (2) Prepare a mixed aqueous solution (inorganic salt solution) containing K2CO3 and KOH, wherein K2CO3 accounts for 10% of the mass of γ-alumina; the molar ratio of KOH to K2CO3 is 0.03:1; and the total molar concentration of KOH and K2CO3 in the inorganic salt solution is 1 mol / L. Immerse the carrier treated with strong alkali into the inorganic salt solution and soak it under ultrasonic action for 24 h. Take out the soaked carrier, dry it at 110℃ for 2 h, and then calcine it at 480℃ for 4 h to obtain the γ-alumina carrier with an inorganic salt modified layer. The mass ratio of the inorganic salt modified layer to the mass of γ-alumina is 0.06:1. (3) Formation of the transition metal layer Ferric acetylacetone was selected as the transition metal organometallic salt. Ferric acetylacetone was deposited on the surface of the modified support using chemical vapor deposition (CVD) at 325°C. Subsequently, a reduction reaction was carried out in an H2 atmosphere to obtain a γ-alumina support covered with transition metal Fe. Weighing analysis showed that the mass ratio of transition metal Fe to γ-alumina was 0.02:1. (4) Formation of graphite modification layer Graphite powder was added to tetrahydrofuran and mixed, then ultrasonically dispersed for 1.5 h to obtain a graphite solution with a graphite concentration of 0.5 mg / ml. A transition metal-coated support was immersed in the above graphite solution for 2 h, then dried at 50 °C for 1.5 h, and subsequently calcined at 300 °C for 1.5 h to obtain a composite support. The mass ratio of the graphite-modified layer to γ-alumina was measured to be 0.02:1. (5) Heat the sodium to melt it, immerse the composite carrier obtained in step (4) into the alkali metal melt, control the melt temperature to be 80°C higher than the melting point (melting point of sodium), soak for 1 hour under the condition of stirring speed of 100 rpm, take it out and cool it to obtain the propylene dimerization catalyst.
[0050] In the final catalyst, the mass ratio of alkali metal to γ-alumina is 0.05:1. Example 3 This embodiment provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) Place γ-alumina in a tube furnace, purge with nitrogen gas for protection, heat to 1000℃ and calcine for 12 hours. Then immerse the γ-alumina in a 16.7wt% KOH aqueous solution and soak under ultrasonic conditions for 6 hours. After removal, dry at 150℃ for 6 hours. (2) Prepare a mixed aqueous solution (inorganic salt solution) containing K2CO3 and KOH; the molar ratio of KOH to K2CO3 is 0.03:1; the total molar concentration of KOH and K2CO3 in the inorganic salt solution is 1 mol / L. Immerse the carrier treated with strong alkali in the inorganic salt solution (K2CO3 accounts for 10% of the mass of γ-alumina), soak it under ultrasonic action for 24 h, take out the soaked carrier, dry it at 110℃ for 2 h, and then calcine it at 480℃ for 4 h to obtain the γ-alumina carrier with inorganic salt modified layer. After weighing, the mass ratio of inorganic salt modified layer to γ-alumina is 0.06:1; (3) Formation of the transition metal layer Ferric acetylacetone was selected as the transition metal organometallic salt. Ferric acetylacetone was deposited on the surface of the modified support using chemical vapor deposition (CVD) at 325°C. Subsequently, a reduction reaction was carried out in an H2 atmosphere to obtain a γ-alumina support covered with transition metal Fe. Weighing analysis showed that the mass ratio of transition metal Fe to γ-alumina was 0.02:1. (4) Formation of graphite modification layer Graphite powder was added to tetrahydrofuran and mixed, then ultrasonically dispersed for 1.5 h to obtain a graphite solution with a graphite concentration of 0.5 mg / ml. A transition metal-coated support was immersed in the above graphite solution for 2 h, then dried at 50 °C for 1.5 h, and subsequently calcined at 300 °C for 1.5 h to obtain a composite support. The mass ratio of the graphite-modified layer to γ-alumina was measured to be 0.02:1. (5) Heat the potassium to melt it, immerse the composite carrier obtained in step (4) into the alkali metal melt, control the melt temperature to be 80°C higher than the melting point, soak for 1 hour under the condition of stirring speed of 100 rpm, take it out and cool it to obtain the propylene dimerization catalyst.
[0051] In the final catalyst, the mass ratio of alkali metal to γ-alumina is 0.05:1.
[0052] Comparative Example 1 This comparative example provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) Place γ-alumina in a tube furnace at 1000°C and calcine it for 12 hours under nitrogen gas protection. (2) Prepare a mixed aqueous solution (inorganic salt solution) containing K2CO3 and KOH, with a molar ratio of KOH to K2CO3 of 0.03:1; the total molar concentration of KOH and K2CO3 in the inorganic salt solution is 1 mol / L. Immerse the calcined support (without strong alkali treatment as in Example 1) in the inorganic salt solution (K2CO3 accounts for 10% of the mass of γ-alumina) and soak it under ultrasonic treatment for 24 h. Take out the soaked support, dry it at 110 °C for 2 h, and then calcine it at 480 °C for 4 h to obtain the γ-alumina support with an inorganic salt modified layer.
[0053] (3) Formation of the transition metal layer Iron acetylacetone was selected as the transition metal organometallic salt. Using chemical vapor deposition (CVD), Fe was deposited on the aforementioned γ-alumina support with an inorganic salt modified layer at 325°C (same time as in Example 1). Subsequently, a reduction reaction was carried out in an H2 atmosphere to obtain a γ-alumina support covered with transition metal Fe. (4) Formation of graphite modification layer Graphite powder was added to tetrahydrofuran and mixed, then ultrasonically dispersed for 1.5 h to obtain a graphite solution with a graphite concentration of 0.5 mg / ml. A transition metal Fe-coated γ-alumina support was immersed in the above graphite solution for 2 h, then dried at 50 °C for 1.5 h, and then calcined at 300 °C for 1.5 h to obtain a composite support.
[0054] (5) Prepare sodium and potassium by heating and melting them at a sodium-potassium mass ratio of 1:1 to obtain an alkali metal melt. Immerse the composite carrier obtained in step (4) into the alkali metal melt, control the melt temperature to be 80°C higher than the melting point, and soak for 1 hour under a stirring speed of 100 rpm. Remove and cool to obtain the propylene dimerization catalyst.
[0055] Comparative Example 2 This comparative example provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) Place γ-alumina in a tube furnace at 1000℃ and calcine with nitrogen gas flow protection for 12 hours. Then immerse the γ-alumina in a 16.7wt% KOH aqueous solution and soak it under ultrasonic conditions for 6 hours. After removal, dry it at 150℃ for 6 hours. (2) Formation of the transition metal layer Iron acetylacetone was selected as the transition metal organometallic salt; Fe was deposited on a strongly alkali-treated support at 325°C using chemical vapor deposition (CVD) (same time as in Example 1). A reduction reaction was then carried out in an H2 atmosphere to obtain a transition metal Fe-coated γ-alumina support. (4) Formation of graphite modification layer Graphite powder was added to tetrahydrofuran and mixed, then ultrasonically dispersed for 1.5 h to obtain a graphite solution with a graphite concentration of 0.5 mg / ml. A transition metal Fe-coated γ-alumina support was immersed in the above graphite solution for 2 h, then dried at 50 °C for 1.5 h, and then calcined at 300 °C for 1.5 h to obtain a composite support.
[0056] (5) Prepare sodium and potassium by heating and melting them at a sodium-potassium mass ratio of 1:1 to obtain an alkali metal melt. Immerse the composite carrier obtained in step (4) into the alkali metal melt, control the melt temperature to be 80°C higher than the melting point, and soak for 1 hour under a stirring speed of 100 rpm. Remove and cool to obtain the propylene dimerization catalyst.
[0057] Comparative Example 3 This comparative example provides a method for preparing a propylene dimerization catalyst, comprising the following steps: (1) Potassium carbonate powder was mixed with 3%wt graphite to form a 3mm particle support, and the catalyst support was initially obtained by calcining in a nitrogen atmosphere at 400℃ for 4h.
[0058] (2) Iron acetylacetone was selected as the transition metal organosalt; Fe was deposited on the catalyst support at 325°C using chemical vapor deposition (CVD) (same time as in Example 1). Then, a reduction reaction was carried out in an H2 atmosphere to obtain a potassium carbonate support covered with transition metal Fe. (3) Heat and melt sodium and potassium at a sodium-potassium mass ratio of 1:1 to obtain alkali metal melt. Immerse the composite carrier obtained in step (1) into the alkali metal melt, control the melt temperature to be 80°C higher than the melting point (the melting point when the sodium-potassium mass ratio is 1:1), soak for 1 hour under the condition of stirring speed of 100 rpm, take it out and cool it to obtain the propylene dimerization catalyst.
[0059] Test example: Conversion rate and selectivity testing: The catalysts prepared in the examples and comparative examples were soaked in an inert solvent, white oil, and then loaded into a reaction tube. The tube was purged 2-3 times with a high-pressure nitrogen flow. The system was heated to 150°C and filled with inert gas to keep the system pressure constant at 6 MPa. The raw material propylene was fed into the reactor after passing through a dehydration and deoxygenation device. The purity of the raw material propylene was greater than 99.9% to avoid poisoning and deactivation of the catalyst. The product liquid was obtained after 5 hours of reaction.
[0060] Lifetime test: Using the same testing methods as conversion rate and selectivity tests, a continuous test is conducted. The effective service life of the catalyst when the conversion rate is greater than 20% and the selectivity is greater than 75% is defined as the effective service life of the catalyst.
[0061] 4MP1 represents 4-methyl-1-pentene. The detection of 4-methyl-1-pentene content was performed using an Agilent gas chromatograph (0.25 mm × 30 m DB-5 capillary column), with a detector temperature of 300 °C, an injection temperature of 280 °C, an injection flow rate of 2.1 ml / min, a nitrogen flow rate of 30 ml / min, and an air flow rate of 360 ml / min. The temperature program was to preheat to 38 °C and hold for 2 min, then increase the temperature to 280 °C at a rate of 10 °C / min and hold for 5 min.
[0062] The experimental parameters and test results are shown in Table 1.
[0063] Table 1
[0064] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A propylene dimerization catalyst, characterized in that, include: Composite carrier, alkali metal loaded on composite carrier; The composite carrier includes γ-alumina; Inorganic salt modified layer loaded on the surface of γ-alumina; transition metal and graphite modified layer loaded on the surface of inorganic salt modified layer.
2. The propylene dimerization catalyst according to claim 1, characterized in that, The mass ratio of the inorganic salt modified layer to γ-alumina is (0.05-0.1):1; Preferably, the mass ratio of transition metal to γ-alumina is (0.01-0.03):1; Preferably, the mass ratio of the graphite-modified layer to γ-alumina is (0.01-0.03):1; Preferably, the mass ratio of alkali metal to γ-alumina is (0.03-0.075):1; Preferably, the inorganic salt modified layer comprises carbonate; Preferably, the inorganic salt modified layer includes at least one of K2CO3 and Na2CO3; Preferably, the inorganic salt modified layer further includes KOH; Preferably, the molar ratio of KOH to carbonate is (0.01-0.05):1; Preferably, the transition metal is selected from at least one of Fe, Co, Ni, Zn, Cu, and Ti; Preferably, the alkali metal is selected from at least one of Na and K; Preferably, alkali metals include Na and K; Preferably, the mass ratio of sodium to potassium in the alkali metal is (0.2-5):1; Preferably, the average particle size of γ-alumina is 2-4 mm; Preferably, the specific surface area of the gamma-alumina is between 45 and 160 m 2 / g; Preferably, the pore volume of the γ-alumina is 0.3-1 ml / g.
3. A method for preparing a propylene dimerization catalyst, characterized in that, Includes the following steps: (1) γ-alumina was soaked in a strong alkaline solution, and then soaked in an inorganic salt solution and calcined to obtain a γ-alumina carrier with an inorganic salt modified layer. (2) A transition metal is formed on the surface of the inorganic salt modified layer of the γ-alumina support to obtain a transition metal covered γ-alumina support; (3) Graphite is formed on the surface of a transition metal-coated γ-alumina support to obtain a composite support; (4) An alkali metal layer is formed on the surface of the composite support to obtain the propylene dimerization catalyst.
4. The preparation method according to claim 3, characterized in that, In step (1), the alkali in the strong alkali solution is KOH; Preferably, the concentration of the alkali in the strong alkaline solution is 15-25 wt%; Preferably, the soaking process in the strong alkaline solution is carried out under ultrasonic conditions; the soaking time is 4-8 hours. Preferably, the concentration of inorganic salts in the inorganic salt solution is 0.5-1.5 mol / L; Preferably, the inorganic salt in the inorganic salt solution includes carbonates; Preferably, the inorganic salt modified layer includes at least one of K2CO3 and Na2CO3; Preferably, the inorganic salt modified layer further includes KOH; Preferably, the molar ratio of KOH to carbonate is (0.01-0.05):1; Preferably, the calcination temperature is 450-500℃; the time is 2-6 hours. Preferably, the mass ratio of the inorganic salt modified layer to the γ-alumina in the inorganic salt modified layer γ-alumina carrier is (0.05-0.1):
1.
5. The preparation method according to claim 3 or 4, characterized in that, In step (2), the transition metal is formed by vapor deposition of a transition metal organic salt followed by a reduction reaction; Preferably, the transition metal organometallic salt is selected from at least one of the following: organometallic salts of Fe, Co, Ni, Zn, Cu, and Ti. Preferably, the transition metal organometallic salt is selected from at least one of acetylacetonate iron, bis(hexafluoroacetylacetonate)copper(II), and Ti(CH2tBu)4; Preferably, the reduced transition metal loading is 0.01-0.03 of the mass of the γ-alumina carrier.
6. The preparation method according to any one of claims 3-5, characterized in that, In step (3), the process of forming graphite involves immersing a transition metal-coated γ-alumina support in a graphite solution, followed by drying and calcination. Preferably, the solvent for the graphite solution is an organic solvent; Preferably, the organic solvent is selected from tetrahydrofuran; Preferably, the concentration of graphite in the graphite solution is 0.1-1 mg / ml; Preferably, the soaking time is 1-3 hours; Preferably, the drying temperature is 40-60℃; the drying time is 1-2 hours. Preferably, the roasting temperature is 250-350℃ and the time is 1-2 hours.
7. The preparation method according to any one of claims 3-6, characterized in that, The process of forming an alkali metal layer on the surface of a composite carrier involves immersing the composite carrier in molten alkali metal. Preferably, alkali metals include Na and K; Preferably, the mass ratio of sodium to potassium in the alkali metal is (0.2-5):1; Preferably, the temperature of the alkali metal melt is 60-100°C higher than the melting point of the alkali metal; Preferably, the composite carrier is immersed in the alkali metal melt for 0.5-1.5 hours; Preferably, the process of forming the alkali metal layer is carried out under stirring conditions; Preferably, the stirring speed is 50-200 rpm / min; Preferably, the mass ratio of alkali metal to γ-alumina is (0.03-0.075):
1.
8. The preparation method according to any one of claims 3-7, characterized in that, Before immersing in a strong alkaline solution, γ-alumina undergoes a calcination process under a nitrogen gas flow; the calcination temperature is 900-1100℃; and the calcination time is 10-14h.
9. The preparation method according to any one of claims 3-8, characterized in that, The average particle size of γ-alumina is 2-4 mm; Preferably, the specific surface area of γ-alumina is 45-160 m² / g. 2 / g; Preferably, the pore volume of the γ-alumina is 0.3-1 ml / g.
10. The use of the propylene dimerization catalyst of claim 1 or the propylene dimerization catalyst prepared by any one of claims 2-9 in the synthesis of 4-methyl-1-pentene.