MWW structural molecular sieve, its manufacturing method and application

Abstract

The present invention provides a MWW molecular sieve and its preparation method and application, which comprises: mixing an aluminum source, water, an alkali source, a first template agent including cyclohexylamine, a second template agent including diisopropylamine, di-n-butylamine, diisobutylamine, 1,4-diazabicyclo[2.2.2]octane, 1,6-hexanediamine, N,N,N,N-tetramethyl-1,6-hexanediamine, a silicon source and seed crystals, and crystallizing to obtain a MWW molecular sieve.

Description

[Technical Field]

[0001] This invention relates to the field of molecular sieve material synthesis technology, and more particularly to MWW structure molecular sieves, their manufacturing method, and applications. [Background technology]

[0002] The MWW molecular sieve has a very typical two-dimensional sheet-like morphology, which consists of several stacked base monolayers. It also forms a unique channel structure primarily in the ab-axis plane, including two-dimensional sinusoidal ten-membered ring channels and twelve-membered ring supercage and semi-supercage structures along the c-axis. The ten-membered ring channels have an opening size of 0.41 nm × 0.51 nm and are distributed outside the supercage structure. The twelve-membered ring supercages have a size of 0.71 nm × 0.71 nm × 1.82 nm and communicate with six identical supercages in the surrounding ab-axis plane via the ten-membered ring. The semi-supercages distributed on the surface of the sheet layer have a size of 0.71 nm × 0.71 nm × 0.8 nm, and their open twelve-membered openings are highly favorable for the diffusion of reactants. The MWW molecular sieve exhibits excellent catalytic reaction performance for large molecule reactions and is widely applied to reaction processes such as alkylation.

[0003] MWW structured molecular sieves are subdivided into several varieties depending on the deposition method of the base monolayer. These mainly include MPM-22 molecular sieves, MCM-49 molecular sieves with oxygen cross-linking bonds between monolayers, MCM-36 molecular sieves that form a support structure between layers, MCM-56 molecular sieves that are deposited disorderly between layers, and single-layer ITQ-2 molecular sieves. Here, MCM-22 molecular sieves are obtained after roasting and dehydrating the silanol groups between layers to form oxygen cross-linking bonds. The crystal structure of roasted MCM-22 molecular sieves is the same as that of MCM-49 molecular sieves.

[0004] Templates for the direct induction synthesis of MWW-structured molecular sieves generally include hexamethyleneimine, piperidine, and homopiperazine. Of these, hexamethyleneimine is the most widely used, but it has the disadvantages of being highly volatile, flammable, and toxic. Piperidine is difficult to obtain commercially. Homopiperazine is expensive and difficult to apply. Therefore, developing an inexpensive and environmentally friendly method for synthesizing MWW-structured molecular sieves is extremely important.

[0005] In conventional synthesis of MWW structured molecular sieves, the synthesis of molecular sieves such as MCM-22 is usually achieved by using hexamethyleneimine in combination with other organic amines.

[0006] According to conventional techniques, due to the unique properties of MWW molecular sieves, synthesis cannot be achieved directly using seed crystals. Instead, a complete MCM-49 molecular sieve can be constructed by adding an organic amine to a seed crystal. To date, there are no precedents for synthesizing MCM-22 molecular sieves without using hexamethyleneimine, piperidine, or homopiperazine. Therefore, there is an urgent need to develop a manufacturing method for MWW molecular sieves, such as MCM-22 molecular sieves, that is easy to operate, environmentally friendly, and inexpensive. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] To solve the above problems, the object of the present invention is to provide an MWW structure molecular sieve, a method for producing the same, and its applications. The present invention enables the direct synthesis of an MWW structure molecular sieve without using hexamethyleneimine, piperidine, and homopiperazine by a method that assists crystallization through the cooperation of a seed crystal and two types of template agents. [Means for solving the problem]

[0008] To achieve the above object, the present invention provides a method for producing an MWW-structured molecular sieve, which includes mixing an aluminum source, water, an alkali source, a first template agent, a second template agent, a silicon source, and seed crystals to form a gel, and crystallizing the gel to obtain the MWW-structured molecular sieve. The first template agent includes cyclohexylamine, and the second template agent includes one or a combination of two or more of diisopropylamine (molecular formula C6H 15 N), di-n-butylamine (molecular formula C8H 19 N), diisobutylamine (molecular formula C8H 19 N), 1,4-diazabicyclo[2.2.2]octane (molecular formula C6H 12 N2), 1,6-hexanediamine (molecular formula C6H 16 N2), N,N,N,N-tetramethyl-1,6-hexanediamine (CAS number 111-18-2, molecular formula C 10 H 24 N2).

[0009] In the above production method, low-toxicity and inexpensive organic amines are adopted as both the first template agent and the second template agent. Here, the first template agent serves as the main template agent and can cooperate with the seed crystals to realize the construction of the basic layer structure of the molecular sieve. The second template agent is used as an auxiliary template agent. And as the second template agent, aliphatic amines with 6-10 carbon atoms and N atoms in sp 3 hybridization are adopted. Therefore, it can form an intermolecular hydrogen bond with the silanol group on the surface of the single-layer structure through the vacant orbital holes in the nitrogen atom sp 3 hybrid orbital. The formation process of the hydrogen bond does not affect the overall crystallization effect of the molecular sieve. Therefore, in some embodiments, the MWW-structured molecular sieve obtained by the above production method has an intermolecular hydrogen bond formed by the silanol group and the second template agent.

[0010] The inventors have found that a molecular sieve with an MWW structure having interlayer hydrogen bonds cannot be obtained using the first template agent, the second template agent, or any one of the seed crystals alone. For example, if the second template agent is omitted, only an MCM-49 molecular sieve can be obtained using only the first template agent and seed crystal. The interlayer bonds in this molecular sieve are oxygen cross-linked bonds, not hydrogen bonds. The above-mentioned production method provided by the present invention allows for the synthesis of a molecular sieve with an MWW structure having interlayer hydrogen bonds by omitting hexamethyleneimine, piperidine, and homopiperazine through the synergistic effect of the first template agent, the second template agent, and the seed crystal. In some specific embodiments, the molar ratio of the first template agent to the second template agent is generally controlled to 0.5-20:1, and can be controlled to, for example, 0.5-1.5:1.

[0011] In a specific embodiment of the present invention, when the alkali source is denoted as MOH (where M is the atom that forms a cation in the alkali source, and the valence of M is generally monovalent; for example, if the alkali source is NaOH, then M is Na), the silicon source is calculated as SiO2, the aluminum source as Al2O3, the alkali source as M2O, and the sum of the first and second template agents is denoted as T, the chemical composition of the gel is generally Al2O3 / SiO2=0.005-0.05, M2O / SiO2=0.03-0.50, T / SiO2=0.10-0.75, and H2O / SiO2=8-120. When the seed crystal is calculated on a dry basis, the mass ratio of the seed crystal to the silicon source generally satisfies seed crystal / SiO2=0.01-0.25.

[0012] In some specific embodiments, the silicon source and the aluminum source can satisfy molar ratios of Al2O3 / SiO2 = 0.01-0.05, and further, Al2O3 / SiO2 = 0.01-0.02.

[0013] In some specific embodiments, the silicon source and water can satisfy a molar ratio of H2O / SiO2 = 15-120 or H2O / SiO2 = 8-13.

[0014] In a specific embodiment of the present invention, the crystallization temperature is generally controlled to 120°C-170°C, for example, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, etc. The crystallization time is generally controlled to 12-120 hours, for example, 12 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 72 hours, 80 hours, 90 hours, 100 hours, 110 hours, 120 hours, etc.

[0015] In specific embodiments of the present invention, the components of the silicon source may include silica, silicates, silicate esters, and the like. Specifically, the silicon source may include one or more combinations of silica sol, solid silica gel, white carbon, water glass, or tetraethyl orthosilicate.

[0016] In specific embodiments of the present invention, the aluminum source may include one or more combinations of metaaluminates (e.g., sodium metaaluminate), aluminum sulfate, aluminum oxide, and boehmite.

[0017] In specific embodiments of the present invention, the seed crystal is generally a molecular sieve having an MWW topological structure, and for example, commercially available MCM-22 molecular sieves, MCM-49 molecular sieves, etc., can be used. In some specific embodiments, the seed crystal may be a molecular sieve having an MWW topological structure obtained by the manufacturing method of the present invention. Preferably, the seed crystal is an MCM-22 molecular sieve from which the template agent has not been removed. Since the molecular sieve has interlayer hydrogen bonds, when applied as a seed crystal in the above manufacturing process, it is advantageous to obtain an MWW structure molecular sieve that has interlayer hydrogen bonds and is similar in structure to the MCM-22 molecular sieve structure.

[0018] In specific embodiments of the present invention, the alkali source may include sodium hydroxide and / or potassium hydroxide, etc.

[0019] In a specific embodiment of the present invention, the manufacturing method specifically includes mixing an aluminum source, water, an alkali source, a first template agent, and a second template agent to obtain an intermediate solution, adding a silicon source and seed crystals to the intermediate solution, mixing to form a gel, and crystallizing the gel to obtain the MWW structure molecular sieve. Synthesizing by the above procedure is advantageous for the uniform dispersion of each raw material and the promotion of the crystallization reaction. In some specific embodiments, the first template agent and the second template agent are added after the aluminum source. This contributes to the complete dissolution of the aluminum source in the solution and its uniform dispersion. The method of adding the silicon source may be a method of adding it slowly. And the seed crystals can be added after the silicon source. By doing so, the uniformity and stability of the reaction system can be improved, and the problem that the dispersion of the reaction system becomes non-uniform due to the formation of a colloid with the aluminum source after the rapid addition of the silicon source can be avoided.

[0020] The present invention further provides an MWW structure molecular sieve obtained by the above manufacturing method. The MWW structure molecular sieve provided by the present invention has an MWW topological structure and has interlayer hydrogen bonds. In some specific embodiments, in the XRD pattern of the above MWW structure molecular sieve, prominent characteristic peaks appear near 6.5 - 7.15° (for example, 7.09°) and 7.18° respectively.

[0021] The MWW-structured molecular sieve of the present invention has interlayer hydrogen bonds and is similar to the structure of the MCM-22 molecular sieve when it is not calcined (the template agent has not been removed), so it can be regarded as a precursor of the MCM-22 molecular sieve (which can be denoted as the MCM-22(P) molecular sieve). The MWW-structured molecular sieve of the present invention has good reforming potential. For example, it can be prepared into the MCM-36 molecular sieve through swelling and pillaring, and can be prepared into the ITQ-2 molecular sieve through swelling and delamination. According to the research of the present invention, the MCM-49 molecular sieve does not have interlayer hydrogen bonds and cannot be exfoliated by swelling. The MCM-22 molecular sieve produced using a conventional template agent (hexamethyleneimine) and the MWW-structured molecular sieve provided by the present invention both have interlayer hydrogen bonds, so it has been found that both of these two types of molecular sieves have the ability to be exfoliated by swelling. For the MCM-22 molecular sieve produced using a conventional template agent (hexamethyleneimine), the difficulty of exfoliation of the MWW-structured molecular sieve provided by the present invention is smaller. Specifically, the pH of the alkaline environment required for exfoliation is closer to neutral. This indicates that the interlayer hydrogen bond strength of the MWW-structured molecular sieve provided by the present invention is more appropriate than the interlayer hydrogen bond strength of the MCM-22 molecular sieve. When performing pillar or exfoliation modification on the molecular sieve, it is more advantageous for retaining the integrity of the molecular sieve sheet-like crystal structure, improving the stability of the molecular sieve, and reducing the loss of catalytic active sites, so it is advantageous for improving the catalytic activity and stability when the molecular sieve is applied to reactions such as alkylation reaction, isomerization reaction or decomposition reaction.

[0022] In a specific embodiment of the present invention, the specific surface area of the MWW-structured molecular sieve is high and can reach 500 m 2 ·g or more.

[0023] In a specific embodiment of the present invention, the specific surface area of the micropores of the MWW-structured molecular sieve is 350 m 2 ·g or more, and the specific surface area of the mesopores of the MWW-structured molecular sieve can reach 140 m 2 ·g or more.

[0024] In a specific embodiment of the present invention, the pore volume of the MWW structure molecular sieve is 0.60 cm³. 3 It can reach more than g.

[0025] In a specific embodiment of the present invention, the pore volume of the micropores of the MWW molecular sieve is 0.16 cm³. 3 It can reach more than g.

[0026] The present invention also provides the use of the MWW structure molecular sieve as a catalyst in alkylation, isomerization, or decomposition reactions. The catalytic effect of the molecular sieve provided by the present invention is not inferior to that of commercially available MCM-22 molecular sieves. In some specific embodiments, when the MWW structure molecular sieve of the present invention is applied to an alkylation reaction, the olefin conversion rate can reach 99.97% or higher, the selectivity can reach 42% or higher, and even 96% or higher. [Effects of the Invention]

[0027] 1. The present invention achieves the construction of a basic layer structure using a seed crystal and a first template agent, and the construction of interlayer hydrogen bonds using a second template agent. Therefore, without using conventional template agents such as hexamethyleneimine, piperidine, and homopiperazine, the product still possesses properties similar to MCM-22 molecular sieves and exhibits high catalytic activity.

[0028] 2. Both the first and second template agents used in this invention are low-toxicity, readily available organic amines, and low-cost, significantly improving the operability of MWW structure molecular sieves and thus having great practical significance. [Brief explanation of the drawing]

[0029] [Figure 1] This is the XRD pattern of the seed crystal. [Figure 2] This is an SEM image of a seed crystal. [Figure 3] This is the XRD pattern of the molecular sieve synthesized in Example 1. [Figure 4] This is an SEM image of the molecular sieve synthesized in Example 1. [Figure 5] This is the XRD pattern of the molecular sieve synthesized in Example 2. [Figure 6] This is an SEM image of the molecular sieve synthesized in Example 2. [Figure 7] This is the XRD pattern of the molecular sieve synthesized in Comparative Example 1. [Figure 8] This is an SEM image of the molecular sieve synthesized in Comparative Example 1. [Figure 9] This is the XRD pattern of the molecular sieve synthesized in Comparative Example 2. [Figure 10] This is an SEM image of the molecular sieve synthesized in Comparative Example 2. [Figure 11] This is the XRD pattern of the molecular sieve synthesized in Comparative Example 3. [Figure 12] This is an SEM image of the molecular sieve synthesized in Comparative Example 3. [Figure 13] This is a TEM image of the molecular sieve synthesized in Comparative Example 1. [Figure 14] This is a TEM diagram of the molecular sieve synthesized in Example 1. [Modes for carrying out the invention]

[0030] To provide a clearer understanding of the technical requirements, objectives, and beneficial effects of the present invention, the proposed technical aspects of the invention will be described in detail below, but this should not be understood as limiting the scope of the invention's applicability. [Examples]

[0031] The following describes in detail embodiments of the present invention. These embodiments are based on the technical proposal of the present invention, and detailed embodiments and processes are shown, but the scope of protection of the present invention is not limited to the embodiments described below. In the following embodiments, for experimental methods where specific conditions are not specified, general conditions may be used.

[0032] The raw materials used in the following examples and comparative examples are as follows:

[0033] Silicon sources: Silica sol (SiO2 content 40%, content is by mass, same applies below), solid silica gel (SiO2 content 95%), white carbon black (SiO2 content 93%), tetraethyl orthosilicate (SiO2 content 98% in terms of elemental silicon), Aluminum sources: Sodium metaaluminate (41% Al2O3 content in terms of aluminum element content), aluminum sulfate (15% Al2O3 content in terms of aluminum element content), aluminum oxide (95% Al2O3 content in terms of aluminum element content), boehmite (70% Al2O3 content in terms of aluminum element content) Alkali source: Sodium hydroxide (99%), potassium hydroxide (99%) First template agent: Cyclohexylamine (99%) Second template agent: diisopropylamine (99%), di-n-butylamine (99%), diisobutylamine (99%), 1,4-diazabicyclo[2.2.2]octane (99%), 1,6-hexanediamine (99%), N,N,N,N-tetramethyl-1,6-hexanediamine (99%), Seed crystal: MCM-22 molecular sieve manufactured by Mobil, which has not undergone the process of removing the template agent by roasting. Water: Deionized water.

[0034] The molecular sieve products of the examples and comparative examples used for characterization were first roasted at 540°C in an air atmosphere, and then subjected to BET evaluation.

[0035] <Example 1> This embodiment provides an MWW structure molecular sieve. The method for producing the molecular sieve includes the following:

[0036] 1. Add 1.87 g of sodium hydroxide to 120 g of deionized water and stir until dissolved. 2. Add 15 g of sodium metaaluminate and stir vigorously for 1 hour until dissolved. 9. Slowly add 50 g of cyclohexylamine and stir vigorously for 0.5 hours. Then, slowly add 6.50 g of diisopropylamine and stir vigorously for 0.5 hours to obtain an intermediate solution.

[0037] 2. 80 g of silica sol was slowly added to the intermediate solution and vigorously stirred for 3 hours. Seed crystals were then added so that their weight was 3% of the silica content in the silica sol, and vigorously stirred for 1 hour to obtain a gel. The gel was crystallized at 140°C for 60 hours. After crystallization was complete, the temperature was lowered to room temperature. The crystallized product was washed with deionized water, filtered, and dried at 120°C for 4 hours to obtain the molecular sieve product.

[0038] In the above experiment, when the silicon source content is calculated as SiO2 and the amount of aluminum source used is calculated as Al2O3, the molar ratio of silicon source to aluminum source is SiO2 / Al2O3 = 62.

[0039] <Example 2> This embodiment provides an MWW structure molecular sieve. The method for producing the molecular sieve includes the following:

[0040] 1. Add 1.87 g of sodium hydroxide to 120 g of deionized water and stir until dissolved. 2. Add 50 g of sodium metaaluminate and stir vigorously for 1 hour until dissolved. 9.00 g of cyclohexylamine is slowly added and vigorously stirred for 0.5 hours. 8.00 g of 1,6-hexanediamine is slowly added and vigorously stirred for 0.5 hours to obtain an intermediate solution.

[0041] 2. 80 g of silica sol was slowly added to the intermediate solution and vigorously stirred for 3 hours. Seed crystals were then added so that their weight was 5% of the silica content in the silica sol, and vigorously stirred for 1 hour to obtain a gel. The gel was crystallized at 145°C for 72 hours. After crystallization was complete, the mixture was cooled to room temperature. The crystallized product was washed with deionized water, filtered, and dried at 120°C for 4 hours to obtain the molecular sieve product.

[0042] In the above experiment, when the silicon source content is calculated as SiO2 and the amount of aluminum source used is calculated as Al2O3, the molar ratio of silicon source to aluminum source is SiO2 / Al2O3 = 53.3.

[0043] <Example 3> This embodiment provides an MWW structure molecular sieve. The method for producing the molecular sieve includes the following:

[0044] 1. Add 1.95 g of sodium hydroxide to 130 g of deionized water and stir until dissolved. 2. Add 33 g of sodium metaaluminate and stir vigorously for 1 hour. Slowly add 9.00 g of 1,4-diazabicyclo[2.2.2]octane and continue stirring vigorously for 0.5 hours. Slowly add 9.00 g of 1,6-hexanediamine and continue stirring vigorously for 0.5 hours to obtain the intermediate solution.

[0045] 2. 80 g of silica sol was slowly added to the intermediate solution and vigorously stirred for 3 hours. Seed crystals were then added so that their weight was 5% of the silica content in the silica sol, and vigorously stirred for 1 hour to obtain a gel. The gel was crystallized at 150°C for 72 hours. After crystallization was complete, the mixture was cooled to room temperature. The crystallized product was washed with deionized water, filtered, and air-dried for 48 hours to obtain the molecular sieve product.

[0046] In the above experiment, when the silicon source content is calculated as SiO2 and the amount of aluminum source used is calculated as Al2O3, the molar ratio of silicon source to aluminum source is SiO2 / Al2O3 = 57.2.

[0047] <Example 4> This embodiment provides an MWW structure molecular sieve. The method for producing the molecular sieve includes the following:

[0048] 1. Add 1.93 g of sodium hydroxide to 150 g of deionized water and stir until dissolved. Add 1.50 g of sodium metaaluminate and stir vigorously for 1 hour. Slowly add 12.25 g of cyclohexylamine and continue stirring vigorously for 0.5 hours. Slowly add 8.50 g of N,N,N,N-tetramethyl-1,6-hexanediamine and continue stirring vigorously for 0.5 hours to obtain an intermediate solution.

[0049] 2. 80 g of silica sol was slowly added to the intermediate solution and the mixture was vigorously stirred for 3 hours. Then, 10% seed crystals were added and the mixture was vigorously stirred for 1 hour to obtain a gel. The gel was crystallized at 150°C for 100 hours. After crystallization was complete, the mixture was cooled to room temperature. The product was washed with deionized water, filtered, and dried at 120°C for 4 hours to obtain the molecular sieve product.

[0050] In the above experiment, when the silicon source content is calculated as SiO2 and the amount of aluminum source used is calculated as Al2O3, the molar ratio of silicon source to aluminum source is SiO2 / Al2O3 = 88.9.

[0051] <Example 5> This embodiment provides an MWW structure molecular sieve. The method for producing the molecular sieve includes the following:

[0052] 1. Add 2.21 g of sodium hydroxide to 175 g of deionized water and stir until dissolved. Add 1.25 g of sodium metaaluminate and stir vigorously for 1 hour. Slowly add 7.55 g of cyclohexylamine and continue stirring vigorously for 0.5 hours. Slowly add 10.50 g of diisobutylamine and continue stirring vigorously for 0.5 hours to obtain an intermediate solution.

[0053] 2. 80 g of silica sol was slowly added to the intermediate solution and vigorously stirred for 3 hours. Seed crystals were then added so that their weight equaled 15% of the silica content in the silica sol, and vigorously stirred for 1 hour to obtain a gel. The gel was crystallized at 140°C for 120 hours. After crystallization was complete, the mixture was cooled to room temperature. The product was washed with deionized water, filtered, and air-dried for 48 hours to obtain the molecular sieve product.

[0054] In the above experiment, when the silicon source content is calculated as SiO2 and the amount of aluminum source used is calculated as Al2O3, the molar ratio of silicon source to aluminum source is SiO2 / Al2O3 = 106.6.

[0055] <Comparative Example 1> This comparative example provides a molecular sieve. The method for producing the molecular sieve includes the following:

[0056] 1. Add 1.95 g of sodium hydroxide to 130 g of deionized water and stir until dissolved. 2. Add 33 g of sodium metaaluminate and stir vigorously for 1 hour. 9.00 g of cyclohexylamine is slowly added and vigorously stirred for 0.5 hours to obtain an intermediate solution.

[0057] 2. 80 g of silica sol was slowly added to the intermediate solution and vigorously stirred for 3 hours. Seed crystals were then added so that their weight was 5% of the silica content in the silica sol, and vigorously stirred for 1 hour to obtain a gel. The gel was crystallized at 150°C for 72 hours. After crystallization was complete, the mixture was cooled to room temperature. The product was washed with deionized water, filtered, and air-dried for 48 hours to obtain the molecular sieve product.

[0058] <Comparative Example 2> This comparative example provides a molecular sieve. The method for producing the molecular sieve includes the following:

[0059] 1. Add 1.87 g of sodium hydroxide to 120 g of deionized water and stir until dissolved. 2. Add 15 g of sodium metaaluminate and stir until dissolved. Stir vigorously for 1 hour. Slowly add 19.0 g of hexamethyleneimine (with a molar ratio of template agent to silicon source of 0.35:1) and continue stirring vigorously for 0.5 hours to obtain an intermediate solution.

[0060] 2. 80 g of silica sol was slowly added to the intermediate solution, and the mixture was vigorously stirred for 3 hours to obtain a crystallized gel. The crystallized gel was allowed to crystallize at 155°C for 60 hours. After crystallization was complete, the mixture was cooled to room temperature. The product was washed with deionized water, filtered, and dried at 120°C for 4 hours to obtain the molecular sieve product.

[0061] The hexamethyleneimine used in this method is a typical template agent for producing MCM-22 molecular sieves. In this comparative example, a pure phase MCM-22 molecular sieve can be obtained, but a large amount of the hexamethyleneimine template agent is used, the template agent is expensive, and it is highly toxic.

[0062] <Comparative Example 3> This comparative example provides a molecular sieve. The method for producing the molecular sieve includes the following:

[0063] 1. Add 1.87 g of sodium hydroxide to 120 g of deionized water and stir until dissolved. 2. Add 15 g of sodium metaaluminate and stir until dissolved. Continue stirring vigorously for 1 hour. Slowly add 9.50 g of cyclohexylamine and 9.50 g of hexamethyleneimine and stir vigorously for 0.5 hours to obtain an intermediate solution.

[0064] 2. Slowly add 80 g of silica sol to the intermediate solution and stir vigorously for 3 hours to obtain a crystallized gel. Crystallize the crystallized gel at 155°C for 60 hours. Once crystallization is complete, cool to room temperature. Wash the product with deionized water, filter, and dry at 120°C for 4 hours to obtain the molecular sieve product.

[0065] <Test Example 1> This test example evaluates the structures of the above-described examples and comparative examples.

[0066] Figures 1 and 2 show the XRD patterns and SEM images of the seed crystals (MCM-22 molecular sieves commercially available from mobile) used in the above examples and comparative examples, respectively.

[0067] Figures 3 and 4 show the XRD pattern and SEM image of the molecular sieve product from Example 1, respectively. As can be seen from Figures 3 and 4, the molecular sieve product produced in Example 1 has typical MWW structural feature peaks, and the molecular sieve product morphology exhibits a cluster-like structure of deposited nanosheets.

[0068] Figures 5 and 6 show the XRD pattern and SEM image of the molecular sieve product from Example 2, respectively. As can be seen from Figures 5 and 6, the molecular sieve product produced in Example 2 has typical MWW structural feature peaks, and the molecular sieve product morphology exhibits a cluster-like structure of deposited nanosheets.

[0069] XRD and SEM evaluation of the molecular sieve products of Examples 3, 4, and 5 revealed that the samples possessed typical MWW structural feature peaks, and that the molecular sieve product morphology exhibited a cluster-like structure with deposited nanosheets.

[0070] Figures 7 and 8 show the XRD pattern and SEM image of the molecular sieve product of Comparative Example 1, respectively. As can be seen from Figures 7 and 8, the molecular sieve product produced in Comparative Example 1 has typical MWW structural feature peaks and can be subdivided into MCM-49 molecular sieves. Furthermore, the molecular sieve product morphology exhibits a regularly deposited nanosheet-like structure.

[0071] Figures 9 and 10 show the XRD pattern and SEM image of the molecular sieve product of Comparative Example 2, respectively. The molecular sieve product produced in Comparative Example 2 had typical MWW structural feature peaks, was subdivided into MCM-22 molecular sieves, and was found to have a nanosheet-like molecular sieve morphology.

[0072] Figures 11 and 12 show the XRD pattern and SEM image of the molecular sieve product of Comparative Example 3, respectively. The molecular sieve product prepared in Comparative Example 3 has typical MWW structural feature peaks. The molecular sieve product is a mixture of MCM-22 and MCM-49 molecular sieves. The molecular sieve morphology is nanosheet deposition.

[0073] As can be seen by comparing the XRD results of the molecular sieve products of Examples 1 to 5 with those of Comparative Example 1, the molecular sieve products of Examples 1 to 5 have independent characteristic peaks at 7.09° (corresponding to the 002 crystal plane) and 7.18°, respectively. These two characteristic peaks indicate that there is a clear interlayer spacing between the 002 crystal planes in the molecular sieve product. This is because the second template agent constructs interlayer hydrogen bonds between adjacent 002 crystal planes, causing a certain degree of steric hindrance, resulting in a significant distance between adjacent crystal planes. On the other hand, the product of Comparative Example 1 has a clear characteristic peak only at 7.18° in its XRD pattern and no clear characteristic peak at 7.09°. This is because, in the product of Comparative Example 1, the 002 crystal planes are deposited together and do not have a clear interlayer spacing; rather, the interlayers in the product of Comparative Example 1 are condensed oxygen crosslinking bonds.

[0074] The hexamethyleneimine used in Comparative Example 2 is a typical template agent for producing MCM-22 molecular sieves, and the molecular sieve obtained in Comparative Example 2 is a pure-phase MCM-22 molecular sieve. As can be seen by comparing the XRD results of the molecular sieve products of Examples 1 to 5 with the XRD results of Comparative Example 2, the molecular sieves of Examples 1 to 5 have a structure similar to that of the MCM-22 molecular sieve. It has been further demonstrated that the molecular sieve of the present invention has interlayer hydrogen bonds similar to those of MCM-22.

[0075] As can be seen from the comparison results above, when cyclohexylamine is used alone as a template agent, the resulting product is an MCM-49 molecular sieve. However, by using cyclohexylamine and a second template agent as template agents, it is possible to produce an MWW structure molecular sieve that has interlayer hydrogen bonds and a structure similar to the MCM-22 molecular sieve manufactured by Mobil.

[0076] As can be seen by comparing the composition of the products of Comparative Example 3 and Example 1, when hexamethyleneimine and cyclohexylamine were used as a composite template agent, a pure-phase MWW structure molecular sieve was synthesized. However, the product of Comparative Example 3 was a mixture of MCM-22 and MCM-49 molecular sieves, and a pure-phase MCM-22 structure molecular sieve could not be obtained. The reason why a pure-phase molecular sieve could not be obtained using a composite template agent of hexamethyleneimine and cyclohexylamine is that when hexamethyleneimine is replaced with cyclohexylamine in a certain proportion, cyclohexylamine does not have the ability to form interlayer hydrogen bonds, and because the hexamethyleneimine concentration is low, sufficient hydrogen bonds cannot be formed. For these reasons, only a mixture of the two types of molecular sieves was obtained, and a single pure-phase molecular sieve could not be obtained.

[0077] Figure 13 is a TEM diagram of the molecular sieve product produced in Comparative Example 1, and Figure 14 is a TEM diagram of the molecular sieve product produced in Example 1. As can be seen by comparing Figures 13 and 14, the molecular sieve of Comparative Example 1 clearly has a deposited base layer and a sheet layer thickness of approximately 20 nm, while the molecular sieve of Example 1 has a reduced base layer volume and a molecular sieve sheet layer thickness of approximately 10 nm. The sheet layer thickness was clearly reduced compared to Comparative Example 1.

[0078] <Test Example 2> This test example provides the results of the specific surface area and pore volume of the molecular sieve products of Examples 1 to 5 and Comparative Example 1 measured by BET, which are specifically shown in Table 1. Here, S BET is the specific surface area, S mic is the surface area of ​​the micropores, S ext V is the surface area of ​​the mesopore. pore V is the pore volume.mic This is the micropore volume.

[0079] [Table 1]

[0080] As can be seen from Table 1, the specific surface area of ​​the micropores, the specific surface area of ​​the mesopores, the total specific surface area, and the total pore volume of the molecular sieves produced in Examples 1 to 5 of the present invention are all larger than those of the molecular sieve products produced in Comparative Examples 1 to 3, and the micropore volume of the molecular sieves produced in Examples 1 to 5 is greater than or equal to the micropore volume of the molecular sieve products prepared in Comparative Examples 1 to 3.

[0081] As can be seen from the data in Table 1 and the results in Figures 13 and 14, the manufacturing method provided in the present invention involves adding a second template agent, thereby increasing the amount of N atoms sp in the second template agent. 3 Hydrogen bonds can be formed between the orbital holes and the hydrogen atoms in the silanol groups. The resulting molecular sieves not only have an MWW topological structure, but their structure is similar to that of MCM-22 molecular sieves, and both have interlayer hydrogen bonds, thus possessing the characteristics of MCM-22 molecular sieves. Furthermore, the total specific surface area and total pore volume of the molecular sieves of the present invention were significantly increased. In addition, the molecular sieve products produced in the present invention had a low deposition number and a small sheet layer thickness, and the deposition morphology of the molecular sieves was different compared to MCM-49 molecular sieves.

[0082] As can be seen by combining the results of Test Example 1 and Test Example 2, in Comparative Example 1, when cyclohexylamine is used as a template agent, it is possible to directly synthesize an MWW structure molecular sieve with high crystallinity that is subdivided into pure-phase MCM-49 molecular sieves. However, since cyclohexylamine cannot form interlayer hydrogen bonds, cyclohexylamine can only be used as a template agent for the synthesis of MMC-49 molecular sieves and cannot be used to synthesize other types of MWW structure molecular sieves. In Comparative Example 3, even when cyclohexylamine is used as a composite template agent in place of hexamethyleneimine in part, sufficient interlayer hydrogen bonds cannot be formed. Therefore, only a mixture of MCM-22 molecular sieves and MCM-49 molecular sieves can be produced, and a molecular sieve having a pure-phase MCM-22 structure cannot be obtained.

[0083] <Example 6> This example provides the use of the molecular sieve product of Example 1 as a catalyst in the alkylation reaction.

[0084] The molecular sieve product from Example 1 was taken and roasted at 540°C for 5 hours in an air atmosphere to remove the template agent. Then, the ammonium was replaced in a 1 mol / L ammonium nitrate solution at 80°C for 2 hours, and roasted again at 540°C for 4 hours in an air atmosphere to obtain an H-type molecular sieve.

[0085] 90g of the above H-type molecular sieve and 15g of pseudo-boehmite were uniformly mixed, and 55g of nitric acid solution was gradually added while kneading. The mixture was extruded into a φ2.0mm cylindrical catalyst and cut into 2.5mm long cylindrical catalysts. After drying the catalyst at room temperature for 24 hours, it was roasted at 550°C for 6 hours to obtain the finished catalyst.

[0086] Two grams of the completed catalyst described above was taken and placed in a fixed-bed reactor, and a mixture of benzene and ethylene was introduced. The reaction conditions were: benzene / olefin ratio 5, reaction temperature 330°C, reaction pressure 1.4 MPa, and gravimetric space velocity 2.0 h. -1 That was the case.

[0087] After 500 hours of reaction, the olefin conversion rate was 99.99% and the ethylbenzene selectivity was 96.21%.

[0088] <Example 7> This example provides the use of the molecular sieve product of Example 2 as a catalyst in the alkylation reaction.

[0089] The molecular sieve product from Example 2 was taken and roasted at 540°C for 5 hours in an air atmosphere to remove the template agent. Then, the ammonium was replaced in a 1 mol / L ammonium nitrate solution at 80°C for 2 hours, and roasted again at 540°C for 4 hours in an air atmosphere to obtain an H-type molecular sieve.

[0090] 90g of the above H-type molecular sieve and 15g of pseudo-boehmite were uniformly mixed, and 55g of nitric acid solution was gradually added while kneading. The mixture was extruded into a φ2.0mm cylindrical catalyst and cut into 2.5mm long cylindrical catalysts. After drying the catalyst at room temperature for 24 hours, it was roasted at 550°C for 6 hours to obtain the finished catalyst.

[0091] Two grams of the completed catalyst described above was taken and placed in a fixed-bed reactor, where a mixture of benzene and propylene was introduced. The reaction conditions were: benzene / olefin ratio of 4, reaction temperature of 150°C, reaction pressure of 2.5 MPa, and gravimetric space velocity of 3.0 h. -1 That was the case.

[0092] After 300 hours of reaction, the olefin conversion rate was 99.97% and the isopropylbenzene selectivity was 99.20%.

[0093] <Example 8> This example provides the use of the molecular sieve product of Example 3 as a catalyst in the alkylation reaction.

[0094] The molecular sieve product from Example 3 was taken and roasted at 540°C for 5 hours in an air atmosphere to remove the template agent. Then, the ammonium was replaced in a 1 mol / L ammonium nitrate solution at 80°C for 2 hours, and roasted again at 540°C for 4 hours in an air atmosphere to obtain an H-type molecular sieve.

[0095] 90g of the above H-type molecular sieve and 15g of pseudo-boehmite were uniformly mixed, and 55g of nitric acid solution was gradually added while kneading. The mixture was extruded into a φ2.0mm cylindrical catalyst and cut into 2.5mm long cylindrical catalysts. After drying the catalyst at room temperature for 24 hours, it was roasted at 550°C for 6 hours to obtain the finished catalyst.

[0096] Two grams of the completed catalyst described above was taken and placed in a fixed-bed reactor, and a mixture of benzene and n-dodecene was introduced. The reaction conditions were: benzene / olefin ratio 15, reaction temperature 150°C, reaction pressure 3.0 MPa, and gravimetric space velocity 2.0 h. -1 That was the case.

[0097] After 300 hours of reaction, the olefin conversion rate was 99.97%, and the 2-alkylbenzene selectivity was 42.01%.

[0098] <Comparative Example 4> This comparative example demonstrates the use of the molecular sieve product of Comparative Example 1 as a catalyst in the alkylation reaction.

[0099] The molecular sieve of Comparative Example 1 was roasted at 540°C for 5 hours in an air atmosphere to remove the template agent. Then, the ammonium was replaced in a 1 mol / L ammonium nitrate solution at 80°C for 2 hours, and then roasted again at 540°C for 4 hours in an air atmosphere to obtain an H-type molecular sieve.

[0100] 90g of the above H-type molecular sieve and 15g of pseudo-boehmite were uniformly mixed, and 55g of nitric acid solution was gradually added while kneading. The mixture was extruded into a φ2.0mm cylindrical catalyst and cut into 2.5mm long cylindrical catalysts. After drying the catalyst at room temperature for 24 hours, it was roasted at 550°C for 6 hours to obtain the finished catalyst.

[0101] Two grams of the completed catalyst described above was taken and placed in a fixed-bed reactor, and a mixture of benzene and n-dodecene was introduced. The reaction conditions were: benzene / olefin ratio 15, reaction temperature 150°C, reaction pressure 3.0 MPa, and gravimetric space velocity 2.0 h. -1 That was the case.

[0102] After 100 hours of reaction, the olefin conversion rate was 76.32% and the 2-alkylbenzene selectivity was 45.03%.

[0103] Comparing the results of Comparative Example 4 with those of Examples 6 to 8, it was found that the catalysts of Examples 6 to 8 had higher olefin conversion rates and isopropylbenzene selectivity. The reason for this is that the MCM-49 molecular sieve produced in Comparative Example 1 did not have interlayer hydrogen bonds, and each monolayer was deposited on top of the others, forming condensed oxygen crosslinks, resulting in a tendency for a high degree of lamination. Interlayer hydrogen bonds exist in the molecular sieves produced in each example, and the hydrogen bonds and the template agents for constructing the hydrogen bonds have a steric hindrance effect between the layers, which can avoid deposition between each layer of the molecular sieve, resulting in a lower degree of lamination in the molecular sieves of each example. On the other hand, since the degree of lamination of the molecular sieves of the examples is lower than that of the molecular sieve of Comparative Example 1, the sheet layer thickness of the molecular sieves produced in Examples 1 to 3 is smaller than that of the MCM-49 molecular sieve of Comparative Example 1, resulting in a larger number of exposed surface catalytic active sites per unit mass of catalyst, which not only results in higher catalytic activity but also avoids the problem of deactivation due to clogging during the reaction, leading to a longer catalyst life.

[0104] From the above, the manufacturing method provided in the present invention can synthesize an MWW structure molecular sieve having interlayer hydrogen bonds, which has properties similar to an MCM-22 molecular sieve and high catalytic activity, without the need for conventional template agents such as hexamethyleneimine, piperidine, and homopiperazine.

Claims

1. A method for producing MWW structured molecular sieves, The process involves mixing an aluminum source, water, an alkali source, a first template agent, a second template agent, a silicon source, and a seed crystal to form a gel, and then crystallizing the gel to obtain the MWW structure molecular sieve. The first template agent comprises cyclohexylamine, The second template agent comprises one or more combinations of diisopropylamine, di-n-butylamine, diisobutylamine, 1,4-diazabicyclo[2.2.2]octane, 1,6-hexanediamine, and N,N,N,N-tetramethyl-1,6-hexanediamine. A method for producing MWW structured molecular sieves.

2. The manufacturing method according to claim 1, wherein the molar ratio of the first template agent to the second template agent is 0.5-20:

1.

3. The alkali source is denoted as MOH, and the silicon source as SiO 2 It is calculated as follows, and the aluminum source is Al 2 O 3 It is calculated as follows, and the alkali source is M 2 When calculated as O, and the sum of the first and second template agents is denoted as T, the chemical composition of the gel satisfies the following range in molar ratios: Al 2 O 3 / SiO 2 =0.005-0.05、M 2 O / SiO 2 =0.03-0.50、T / SiO 2 =0.10-0.75、H 2 O / SiO 2 =8-120 When the seed crystal is calculated as dry weight, what is the mass ratio of the seed crystal to the silicon source (seed crystal / SiO₂)? 2 The manufacturing method according to claim 1, wherein the coefficient satisfies 0.01-0.

25.

4. The chemical composition of the gel is H 2 O / SiO 2 The manufacturing method according to claim 3, wherein the molar ratio satisfies the range of =15-120.

5. The manufacturing method according to claim 1, wherein the crystallization temperature is 120°C to 170°C and the crystallization time is 12 to 120 hours.

6. The manufacturing method according to claim 1, wherein the silicon source includes one or more combinations of silica, silicates, and silicate esters.

7. The manufacturing method according to claim 1, wherein the silicon source comprises one or a combination of two or more of silica sol, solid silica gel, white carbon, water glass, and tetraethyl orthosilicate.

8. The manufacturing method according to claim 1, wherein the aluminum source includes one or more combinations of metaaluminate, aluminum sulfate, aluminum oxide, and pseudoboehmite.

9. The manufacturing method according to claim 1, wherein the seed crystal is a molecular sieve having an MWW topological structure.

10. The manufacturing method according to claim 1, wherein the seed crystal comprises an MCM-22 molecular sieve and / or an MCM-49 molecular sieve.

11. The manufacturing method according to claim 1, wherein the alkali source comprises sodium hydroxide and / or potassium hydroxide.

12. The manufacturing method according to claim 1, comprising mixing an aluminum source, water, an alkali source, a first template agent, and a second template agent to obtain an intermediate solution, adding a silicon source and a seed crystal to the intermediate solution, mixing to form a gel, and crystallizing the gel to obtain the MWW structure molecular sieve.

Images