MWW molecular sieve and 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] The present invention relates to the technical field of molecular sieve material synthesis, and in particular to a molecular sieve with MWW structure and its preparation method and application. [Background technology]

[0002] The MWW molecular sieve has a very typical two-dimensional sheet-like morphology, and the sheet-like structure is formed by stacking several basic monolayers, and a unique channel structure is also formed, mainly including two-dimensional sinusoidal ten-membered ring channels in the ab-axis plane and twelve-membered ring supercage structures and semi-supercage structures along the c-axis direction. The ten-membered ring channels have an opening size of 0.41nm×0.51nm and are distributed outside the supercage structure. The twelve-membered ring supercage has a size of 0.71nm×0.71nm×1.82nm and communicates with six identical supercages in the surrounding ab-axis plane through ten-membered rings. The semi-supercage distributed on the surface of the sheet layer has a size of 0.71nm×0.71nm×0.8nm, and its open twelve-membered opening is very favorable for the diffusion of reactants. The MWW molecular sieve has excellent catalytic reaction performance for large molecule reactions and is widely applied in reaction processes such as alkylation.

[0003] MWW molecular sieves are divided into several varieties according to the deposition method of the basic monolayer, which mainly include MPM-22 molecular sieve, MCM-49 molecular sieve with oxygen bridge bond between monolayer, MCM-36 molecular sieve with pillar structure between layers, MCM-56 molecular sieve with random deposition between layers, ITQ-2 molecular sieve with monolayer structure, etc. Here, MCM-22 molecular sieve is obtained after roasting and dehydrating the silanol group between layers to form oxygen bridge bond. The crystal structure of the roasted MCM-22 molecular sieve is the same as that of MCM-49 molecular sieve.

[0004] Template agents for direct induction synthesis of MWW molecular sieves generally include hexamethyleneimine, piperidine, and homopiperazine. Among them, hexamethyleneimine is the most widely used, but it has the disadvantages of being volatile, flammable, and highly toxic. Piperidine is difficult to obtain from commercial sources. Homopiperazine is expensive and difficult to apply. Therefore, it is very important to develop a method for synthesizing MWW molecular sieves that is inexpensive and has low environmental impact.

[0005] In the conventional synthesis of MWW 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 the prior art, due to the special nature of MWW molecular sieve, it is not possible to directly use seed crystals to realize the synthesis, and the complete MCM-49 molecular sieve can be constructed by adding organic amine after adding seed crystals. Up to now, there is no precedent for synthesizing MCM-22 molecular sieve without using hexamethyleneimine, piperidine, or homopiperazine, so it is urgent to develop a method for producing MWW molecular sieve such as MCM-22 molecular sieve, which is easy to operate, has low environmental impact, and is inexpensive. Summary of the Invention [Problem to be solved by the invention]

[0007] In order to solve the above problems, the present invention aims to provide a MWW molecular sieve and its preparation method and application. The present invention can directly synthesize MWW molecular sieve by using a method of assisting crystallization by the cooperation of seed crystals and two kinds of template agents without using hexamethyleneimine, piperidine, or homopiperazine. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a method for preparing an MWW structure molecular sieve, comprising 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 includes cyclohexylamine, and the second template agent includes diisopropylamine (molecular formula CH 15 N), di-n-butylamine (molecular formula CH 19 N), diisobutylamine (molecular formula: CH 19 N), 1,4-diazabicyclo[2.2.2]octane (molecular formula CH 12 N2), 1,6-Hexanediamine (molecular formula CH 16 N2), N,N,N,N-tetramethyl-1,6-hexanediamine (CAS number 111-18-2, molecular formula C 10 H 24 N2) includes one or a combination of two or more of the above.

[0009] In the above-mentioned manufacturing method, the first template agent and the second template agent are both low-toxicity and inexpensive organic amines. Here, the first template agent is a main template agent that can cooperate with the seed crystal to realize the construction of the basic layer structure of the molecular sieve. The second template agent is used as a sub-template agent. The second template agent is an organic amine having 6-10 carbon atoms and an N atom in the sp 3 A mixed aliphatic amine is used. Therefore, the nitrogen atom sp 3 The hybrid orbital can form interlayer hydrogen bonds with the silanol groups on the surface of the single-layer structure through the vacant orbital holes. The hydrogen bond formation process does not affect the overall crystallization effect of the molecular sieve. Therefore, in some embodiments, the MWW molecular sieve obtained by the above preparation method has interlayer hydrogen bonds formed by the silanol groups and the second template agent.

[0010] The present inventors have found that the MWW molecular sieve having interlayer hydrogen bonds cannot be obtained by using only one of the first template agent, the second template agent, or the seed crystals. For example, when the second template agent is omitted, only the first template agent and the seed crystals are used to obtain MCM-49 molecular sieves. The interlayers of the molecular sieve are not hydrogen bonds but oxygen bridge bonds. The above-mentioned preparation method provided by the present invention can synthesize the MWW molecular sieve having interlayer hydrogen bonds by omitting hexamethyleneimine, piperidine, and homopiperazine through the synergistic action of the first template agent, the second template agent, and the seed crystals. 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, for example, 0.5-1.5:1.

[0011] In a specific embodiment of the present invention, when the alkali source is expressed as MOH (M is an atom forming a cation in the alkali source, and the atomic valence of M is generally monovalent. For example, when the alkali source is NaOH, M is Na), the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the alkali source is calculated as M2O, and the sum of the first template agent and the second template agent is expressed 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 as a dry weight, 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 the molar ratio of Al2O3 / SiO2=0.01-0.05, or even 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., such as 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, such as 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 a specific embodiment of the present invention, the silicon source component can include silica, silicate, silicate ester, etc. Specifically, the silicon source can include one or more of silica sol, solid silica gel, white carbon, water glass, tetraethyl orthosilicate, etc.

[0016] In a specific embodiment of the present invention, the aluminum source can include one or a combination of two or more of metaaluminates (eg, sodium metaaluminate), aluminum sulfate, aluminum oxide, pseudoboehmite, and the like.

[0017] In a specific embodiment of the present invention, the seed crystal generally adopts a molecular sieve having MWW topology structure, for example, commercially available MCM-22 molecular sieve, MCM-49 molecular sieve, etc. In some specific embodiments, the seed crystal may adopt a molecular sieve having MWW topology structure obtained by the manufacturing method of the present invention. The seed crystal is preferably 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 a molecular sieve having MWW structure with interlayer hydrogen bonds and similar to the MCM-22 molecular sieve structure.

[0018] In a specific embodiment of the present invention, the alkaline source may include sodium hydroxide and / or potassium hydroxide.

[0019] In a specific embodiment of the present invention, the above preparation 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 a seed crystal to the intermediate solution, mixing to form a gel, and crystallizing the gel to obtain the MWW structure molecular sieve. The above procedure is advantageous for uniform dispersion of each raw material and promotion of 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 aluminum source being completely dissolved in the solution and uniformly dispersed. The silicon source may be added in a slow manner. And the seed crystals may be added after the silicon source. This can improve the uniformity and stability of the reaction system and avoid the problem of the silicon source being quickly added and then forming a colloid with the aluminum source, resulting in non-uniform dispersion of the reaction system.

[0020] The present invention further provides a MWW molecular sieve obtained by the above-mentioned preparation method. The MWW molecular sieve provided by the present invention has an MWW topology structure and has interlayer hydrogen bonds. In some specific embodiments, the XRD pattern of the MWW molecular sieve has prominent characteristic peaks at around 6.5-7.15° (e.g., 7.09°) and 7.18°.

[0021] The MWW molecular sieve of the present invention has interlayer hydrogen bonds and is similar to the structure of MCM-22 molecular sieve when it is not roasted (the template agent is not removed), so it can be regarded as a precursor of MCM-22 molecular sieve (which can be written as MCM-22(P) molecular sieve). The MWW molecular sieve of the present invention has good modification potential. For example, it can be prepared into MCM-36 molecular sieve through swelling and strut, and into ITQ-2 molecular sieve through swelling and peeling. The present invention has found that MCM-49 molecular sieve does not have interlayer hydrogen bonds and cannot be swollen and peeled. It has been found that the MCM-22 molecular sieve prepared using a normal template agent (hexamethyleneimine) and the MWW molecular sieve provided by the present invention both have interlayer hydrogen bonds, so these two molecular sieves both have the ability of swelling and peeling. Compared with the MCM-22 molecular sieve prepared by the conventional template (hexamethyleneimine), the MWW molecular sieve provided by the present invention is less difficult to peel off. Specifically, the pH of the alkaline environment required for peeling is closer to neutral. This indicates that the interlayer hydrogen bond strength of the MWW molecular sieve provided by the present invention is more suitable than that of the MCM-22 molecular sieve. When the molecular sieve is subjected to the support or peeling modification, it is more favorable to maintain the integrity of the molecular sieve sheet crystal structure, improve the stability of the molecular sieve, and reduce the loss of catalytic active sites, and therefore it is favorable to improve the catalytic activity and stability when the molecular sieve is applied to reactions such as alkylation, isomerization, or cracking.

[0022] In a specific embodiment of the present invention, the MWW molecular sieve has a high specific surface area of ​​500 m 2 · It can reach more than g.

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

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

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

[0027] 1. The present invention uses seed crystals and a first template agent to establish a basic layer structure, and a second template agent to establish interlayer hydrogen bonds. Therefore, the product does not need to use traditional templates such as hexamethyleneimine, piperidine, homopiperazine, etc., and still has properties similar to MCM-22 molecular sieve and exhibits high catalytic ability.

[0028] 2. The first and second template agents used in the present invention are both organic amines with low toxicity and easy availability, and are low-cost, which can greatly improve the operability of the production of MWW molecular sieves, and is of great practical significance. [Brief description of the drawings]

[0029] [Figure 1] 1 is an XRD pattern of a seed crystal. [Diagram 2] FIG. 2 is an SEM image of a seed crystal. [Diagram 3] 1 is an XRD pattern of the molecular sieve synthesized in Example 1. [Figure 4] FIG. 2 is an SEM image of the molecular sieve synthesized in Example 1. [Diagram 5] 1 is an XRD pattern of the molecular sieve synthesized in Example 2. [Figure 6] FIG. 2 is an SEM image of the molecular sieve synthesized in Example 2. [Figure 7] 1 is an XRD pattern of the molecular sieve synthesized in Comparative Example 1. [Figure 8] FIG. 2 is an SEM image of the molecular sieve synthesized in Comparative Example 1. [Figure 9] 1 is an XRD pattern of the molecular sieve synthesized in Comparative Example 2. [Figure 10] FIG. 2 is an SEM image of the molecular sieve synthesized in Comparative Example 2. [Figure 11] 1 is an XRD pattern of the molecular sieve synthesized in Comparative Example 3. [Figure 12] FIG. 2 is an SEM image of the molecular sieve synthesized in Comparative Example 3. [Figure 13] FIG. 2 is a TEM image of the molecular sieve synthesized in Comparative Example 1. [Figure 14] FIG. 1 is a TEM image of the molecular sieve synthesized in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In order to make the technical requirements, objectives and beneficial effects of the present invention more clearly understood, the technical solutions of the present invention are described in detail below, but should not be understood as limiting the possible scope of the present invention. EXAMPLES

[0031] The following examples of the present invention are described in detail, and the examples are carried out based on the technical solution 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 following examples. In the following examples, for the experimental methods for which 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 source: silica sol (SiO2 content 40%, content is mass content, same below), solid silica gel (SiO2 content 95%), white carbon black (SiO2 content 93%), tetraethyl orthosilicate (SiO2 content 98% in terms of silicon element), Aluminum source: sodium metaaluminate (aluminum content: 41% Al2O3), aluminum sulfate (aluminum content: 15% Al2O3), aluminum oxide (aluminum content: 95% Al2O3), pseudoboehmite (aluminum content: 70% Al2O3), Alkaline 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 crystals: Mobil MCM-22 molecular sieve, which has not been roasted to remove the template; Water: Deionized water.

[0034] The molecular sieve products of the examples and comparative examples used for the property evaluation are first roasted at 540° C. in an air atmosphere, and then the BET evaluation is performed.

[0035] <Example 1> This embodiment provides a MWW structure molecular sieve, the preparation method of which includes:

[0036] 1. 1.87g of sodium hydroxide was added to 120g of deionized water and stirred to dissolve. 2.15g of sodium metaaluminate was added and stirred vigorously for 1 hour to dissolve. 9.50g of cyclohexylamine was slowly added and stirred vigorously for 0.5 hours. Then, 6.50g of diisopropylamine was slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

[0037] 2. 80g of silica sol was slowly added to the intermediate solution and stirred vigorously for 3 hours. Seed crystals were then added so that the weight was 3% of the silica content in the silica sol, and stirred vigorously for 1 hour to obtain a gel. The gel was crystallized at 140°C for 60 hours. When the crystallization was completed, 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 a molecular sieve product.

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

[0039] <Example 2> This embodiment provides a MWW structure molecular sieve, the preparation method of which includes:

[0040] 1. 1.87g of sodium hydroxide was added to 120g of deionized water and stirred until dissolved. 2.50g of sodium metaaluminate was added and stirred vigorously for 1 hour until dissolved. 9.00g of cyclohexylamine was added slowly and stirred vigorously for 0.5 hours. 8.00g of 1,6-hexanediamine was added slowly and stirred vigorously for 0.5 hours to obtain an intermediate solution.

[0041] 2. 80g of silica sol was slowly added to the intermediate solution and stirred vigorously for 3 hours. Seed crystals were then added so that the weight was 5% of the silica content in the silica sol, and stirred vigorously for 1 hour to obtain a gel. The gel was crystallized at 145°C for 72 hours. After the crystallization was completed, 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 a molecular sieve product.

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

[0043] <Example 3> This embodiment provides a MWW structure molecular sieve, the preparation method of which includes:

[0044] 1. 1.95g of sodium hydroxide was added to 130g of deionized water and stirred to dissolve. 2.33g of sodium metaaluminate was added and stirred vigorously for 1 hour. 9.00g of 1,4-diazabicyclo[2.2.2]octane was slowly added and stirred vigorously for 0.5 hours. 9.00g of 1,6-hexanediamine was slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

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

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

[0047] <Example 4> This embodiment provides a MWW structure molecular sieve, the preparation method of which includes:

[0048] 1. 1.93 g of sodium hydroxide was added to 150 g of deionized water and stirred to dissolve. 1.50 g of sodium metaaluminate was added and stirred vigorously for 1 hour. 12.25 g of cyclohexylamine was slowly added and stirred vigorously for 0.5 hours. 8.50 g of N,N,N,N-tetramethyl-1,6-hexanediamine was slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

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

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

[0051] <Example 5> This embodiment provides a MWW structure molecular sieve, the preparation method of which includes:

[0052] 1. 2.21g of sodium hydroxide was added to 175g of deionized water and stirred to dissolve. 1.25g of sodium metaaluminate was added and stirred vigorously for 1 hour. 7.55g of cyclohexylamine was slowly added and stirred vigorously for 0.5 hours. 10.50g of diisobutylamine was slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

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

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

[0055] <Comparative Example 1> This comparative example provides a molecular sieve, the preparation method of which includes:

[0056] 1. 1.95g of sodium hydroxide was added to 130g of deionized water and stirred to dissolve. 2.33g of sodium metaaluminate was added and stirred vigorously for 1 hour. 9.00g of cyclohexylamine was slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

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

[0058] <Comparative Example 2> This comparative example provides a molecular sieve, the preparation method of which includes:

[0059] 1. 1.87g of sodium hydroxide was added to 120g of deionized water and stirred to dissolve. 2.15g of sodium metaaluminate was added and stirred to dissolve. Stirred vigorously for 1 hour. 19.0g of hexamethyleneimine (template agent to silicon source molar ratio of 0.35:1) was slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

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

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

[0062] <Comparative Example 3> This comparative example provides a molecular sieve, the preparation method of which includes:

[0063] 1. 1.87g of sodium hydroxide was added to 120g of deionized water and dissolved by stirring. 2.15g of sodium metaaluminate was added and dissolved by stirring. Stirring was continued for 1 hour. 9.50g of cyclohexylamine and 9.50g of hexamethyleneimine were slowly added and stirred vigorously for 0.5 hours to obtain an intermediate solution.

[0064] 2. 80g of silica sol was slowly added to the intermediate solution and stirred vigorously for 3 hours to obtain a crystallized gel. The crystallized gel was crystallized at 155°C for 60 hours. After the crystallization was completed, the temperature was lowered to room temperature. The product was washed with deionized water, filtered, and dried at 120°C for 4 hours to obtain a molecular sieve product.

[0065] <Test Example 1> In this test example, the structures of the above-mentioned examples and comparative examples are evaluated.

[0066] 1 and 2 are respectively an XRD pattern and an SEM photograph of the seed crystals (MCM-22 molecular sieve available from Mobile) used in the above examples and comparative examples.

[0067] Figures 3 and 4 are respectively the XRD pattern and SEM photograph of the molecular sieve product of Example 1. As can be seen from Figures 3 and 4, the molecular sieve product prepared in Example 1 has a typical MWW structure characteristic peak, and the molecular sieve product morphology is a cluster of nanosheets.

[0068] Figures 5 and 6 are respectively the XRD pattern and SEM photograph of the molecular sieve product of Example 2. As can be seen from Figures 5 and 6, the molecular sieve product prepared in Example 2 has a typical MWW structure characteristic peak, and the molecular sieve product morphology is a cluster of nanosheets.

[0069] XRD and SEM evaluation of the molecular sieve products of Examples 3, 4, and 5 showed that the samples had typical MWW structure characteristic peaks, and the molecular sieve product morphology was a cluster of nanosheets.

[0070] 7 and 8 are respectively the XRD pattern and SEM photograph of the molecular sieve product of Comparative Example 1. As can be seen from Fig. 7 and Fig. 8, the molecular sieve product produced in Comparative Example 1 has a typical MWW structure characteristic peak and can be subdivided into MCM-49 molecular sieve. And the molecular sieve product has a regularly stacked nanosheet shape.

[0071] 9 and 10 are respectively an XRD pattern and an SEM photograph of the molecular sieve product of Comparative Example 2. It was found that the molecular sieve product produced in Comparative Example 2 had a typical MWW structure characteristic peak, was subdivided into MCM-22 molecular sieve, and had a nanosheet-like molecular sieve morphology.

[0072] 11 and 12 are respectively the XRD pattern and SEM photograph of the molecular sieve product of Comparative Example 3. The molecular sieve product produced in Comparative Example 3 has a typical MWW structure characteristic peak. The molecular sieve product is a mixture of MCM-22 and MCM-49 molecular sieves. The molecular sieve morphology is a nanosheet stack.

[0073] 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 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 the molecular sieve products have a clear layer spacing between the 002 crystal planes. This is because the second template agent creates interlayer hydrogen bonds between adjacent 002 crystal planes to create a certain 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 the XRD pattern, and does not have a clear characteristic peak at 7.09°. This is because in the product of Comparative Example 1, the 002 crystal planes are stacked together and do not have a clear layer spacing, and the interlayers in the product of Comparative Example 1 are condensed oxygen bridge bonds.

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

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

[0076] As can be seen from the comparison of the composition of the product of Comparative Example 3 and Example 1, when hexamethyleneimine and cyclohexylamine are used as composite template agents, a pure-phase MWW structure molecular sieve can be synthesized, but the product of Comparative Example 3 is a mixture of MCM-22 and MCM-49 molecular sieves, and a pure-phase MCM-22 structure molecular sieve cannot be obtained. The reason why a pure-phase molecular sieve cannot be obtained by using a composite template agent of hexamethyleneimine and cyclohexylamine is that when hexamethyleneimine is replaced by cyclohexylamine at a certain ratio, cyclohexylamine does not have the ability to build interlayer hydrogen bonds, and the hexamethyleneimine concentration is low, so sufficient hydrogen bonds cannot be built. For the above reasons, only a mixture of two types of molecular sieves can be obtained, and a single pure-phase molecular sieve cannot be obtained.

[0077] Fig. 13 is a TEM image of the molecular sieve product produced in Comparative Example 1, and Fig. 14 is a TEM image of the molecular sieve product produced in Example 1. Comparing Fig. 13 and Fig. 14, it can be seen that the molecular sieve of Comparative Example 1 has a clearly deposited base layer and the thickness of the sheet layer is about 20 nm, while the molecular sieve of Example 1 has a reduced volume of the base layer and the thickness of the molecular sieve sheet layer is about 10 nm. The thickness of the sheet layer is obviously 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. BET is the specific surface area, S mic is the surface area of ​​the micropores, S ext is the surface area of ​​the mesopores, V pore is the pore volume, Vmic is the micropore volume.

[0079] [Table 1]

[0080] As can be seen from Table 1, the micropore specific surface area, mesopore specific surface area, total specific surface area and total pore volume of the molecular sieves prepared in Examples 1 to 5 of the present invention are all larger than those of the molecular sieve products prepared in Comparative Examples 1 to 3, and the micropore volumes of the molecular sieves prepared in Examples 1 to 5 are equal to or larger than those 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 FIG. 13 and FIG. 14, the production method provided by the present invention can convert the N atom sp 3 The orbital holes of the silanol groups can form hydrogen bonds with the hydrogen in the silanol groups. The molecular sieve thus obtained not only has an MWW topology structure, but also has a molecular sieve structure similar to that of MCM-22 molecular sieve, and both have interlayer hydrogen bonds, so that the molecular sieve has the properties of MCM-22 molecular sieve, and the total specific surface area and total pore volume of the molecular sieve of the present invention are also significantly increased. In addition, the molecular sieve product produced by the present invention has a low stacking number and a small thickness of the sheet layer, and the stacking morphology of the molecular sieve is changed compared with that of MCM-49 molecular sieve.

[0082] As can be seen from 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 a MWW molecular sieve with high crystallinity and which is subdivided into a pure phase MCM-49 molecular sieve, but cyclohexylamine cannot form interlayer hydrogen bonds, so cyclohexylamine can only be used as a template agent to synthesize MMC-49 molecular sieves, and cannot synthesize other types of MWW molecular sieves. In Comparative Example 3, even if cyclohexylamine is used as a composite template agent instead of hexamethyleneimine, it is not possible to form sufficient interlayer hydrogen bonds, so only a mixture of MCM-22 molecular sieves and MCM-49 molecular sieves can be produced, and a molecular sieve with 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 to catalyze an alkylation reaction.

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

[0085] 90g of the above H-type molecular sieve and 15g of pseudo-boehmite were mixed uniformly, and 55g of nitric acid solution was gradually added while kneading, and the mixture was extruded into a cylindrical catalyst with a diameter of 2.0 mm, and then cut into a cylindrical catalyst with a length of 2.5 mm. The catalyst was dried at room temperature for 24 hours, and then roasted at 550℃ for 6 hours to obtain a finished catalyst.

[0086] 2g of the above catalyst 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 1.4MPa, and weight space velocity 2.0h -1 It was.

[0087] As a result of the reaction, after 500 hours of reaction, the olefin conversion 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 an alkylation reaction.

[0089] The molecular sieve product of Example 2 was taken and roasted at 540°C for 5 hours in an air atmosphere to remove the template, then ammonium-exchanged in 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 mixed uniformly, and 55g of nitric acid solution was gradually added while kneading, and the mixture was extruded into a cylindrical catalyst with a diameter of 2.0 mm, and then cut into a cylindrical catalyst with a length of 2.5 mm. The catalyst was dried at room temperature for 24 hours, and then roasted at 550℃ for 6 hours to obtain a finished catalyst.

[0091] 2g of the above catalyst was taken and placed in a fixed bed reactor, and a mixture of benzene and propylene was introduced. The reaction conditions were benzene / olefin ratio 4, reaction temperature 150°C, reaction pressure 2.5MPa, and weight space velocity 3.0h -1 It was.

[0092] As a result of the reaction, after 300 hours of reaction, the olefin conversion 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 an alkylation reaction.

[0094] The molecular sieve product of Example 3 was taken and roasted at 540°C for 5 hours in an air atmosphere to remove the template, then ammonium-exchanged in 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 mixed uniformly, and 55g of nitric acid solution was gradually added while kneading, and the mixture was extruded into a cylindrical catalyst with a diameter of 2.0 mm, and then cut into a cylindrical catalyst with a length of 2.5 mm. The catalyst was dried at room temperature for 24 hours, and then roasted at 550℃ for 6 hours to obtain a finished catalyst.

[0096] 2 g of the above catalyst 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 weight space velocity 2.0 h -1 It was.

[0097] As a result of the reaction, after 300 hours of reaction, the olefin conversion was 99.97% and the 2-alkylbenzene selectivity was 42.01%.

[0098] <Comparative Example 4> This comparative example provides the use of the molecular sieve product of Comparative Example 1 as a catalyst in an 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, and then ammonium-exchanged 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.

[0100] 90g of the above H-type molecular sieve and 15g of pseudo-boehmite were mixed uniformly, and 55g of nitric acid solution was gradually added while kneading, and the mixture was extruded into a cylindrical catalyst with a diameter of 2.0 mm, and then cut into a cylindrical catalyst with a length of 2.5 mm. The catalyst was dried at room temperature for 24 hours, and then roasted at 550℃ for 6 hours to obtain a finished catalyst.

[0101] 2 g of the above catalyst 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 weight space velocity 2.0 h -1 It was.

[0102] As a result of the reaction, after 100 hours of reaction, the olefin conversion was 76.32% and the 2-alkylbenzene selectivity was 45.03%.

[0103] Comparing the results of Comparative Example 4 and Examples 6 to 8, it was found that the catalysts of Examples 6 to 8 have higher olefin conversion and isopropylbenzene selectivity. The reason is that the MCM-49 molecular sieve prepared in Comparative Example 1 does not have interlayer hydrogen bonds, and each monolayer is stacked on each other to form condensed oxygen bridge bonds, which tends to have a high degree of stacking. The molecular sieves prepared in each example have interlayer hydrogen bonds, and the hydrogen bonds and the template agent for constructing hydrogen bonds have a steric hindrance effect between the layers, which can avoid stacking between each layer of the molecular sieve, so the degree of stacking in the molecular sieves of each example is low. On the other hand, the stacking degree of the molecular sieves of the examples is lower than that of the molecular sieve of Comparative Example 1, so the molecular sieves prepared in Examples 1 to 3 have a sheet layer thickness smaller than that of the MCM-49 molecular sieve of Comparative Example 1, and the number of surface catalytic active sites exposed in a unit mass of catalyst is larger, which not only has higher catalytic activity, but also avoids the problem of inactivation caused by clogging during the reaction, and has a longer catalyst life.

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

Claims

1. A method for producing a MWW molecular sieve, comprising the steps of: 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 crystallizing the gel to obtain the MWW-structured molecular sieve; the first template agent comprises cyclohexylamine; The second template agent includes one or a combination of two or more 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; The manufacturing method of MWW structure molecular sieve.

2. 2. The method of 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 represented as MOH, and the silicon source is represented as SiO 2 where the aluminum source is Al 2 O 3 and the alkali source is M 2 When the total amount of the first template agent and the second template agent is expressed as O, and the total amount of the first template agent and the second template agent is expressed as T, the chemical composition of the gel satisfies the following range in terms of molar ratio: 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 crystals are calculated as a dry mass, the mass ratio of the seed crystals to the silicon source (seed crystals / SiO 2 2. The method according to claim 1 , wherein the ratio of the total mass of the polymer to the total mass of the cellulose is 0.01 to 0.

25.

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

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

6. The method according to claim 1 , wherein the silicon source comprises one or a combination of two or more of silica, silicate, and silicate ester.

7. The method according to claim 1 or 6, 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 method according to claim 1 , wherein the aluminum source comprises one or a combination of two or more of metaaluminate, aluminum sulfate, aluminum oxide, and pseudoboehmite.

9. 2. The method of claim 1, wherein the seed crystal is a molecular sieve having a MWW topology structure.

10. 2. The process of claim 1, wherein the seed crystals comprise MCM-22 molecular sieve and / or MCM-49 molecular sieve.

11. The method of claim 1 , wherein the alkaline source comprises sodium hydroxide and / or potassium hydroxide.

12. 12. The method of 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 seed crystals to the intermediate solution, and mixing to form a gel; and crystallizing the gel to obtain the MWW-structured molecular sieve.

13. A MWW molecular sieve obtained by the process according to any one of claims 1 to 12.

14. The specific surface area of ​​the MWW molecular sieve is 500m 2 The MWW molecular sieve of claim 13, wherein the molecular weight is greater than or equal to g.

15. The specific surface area of ​​the micropores of the MWW molecular sieve is 350m 2 g or more, and the specific surface area of ​​the mesopores of the MWW structure molecular sieve is 140 m 2 The MWW molecular sieve of claim 13, wherein the molecular weight is greater than or equal to g.

16. The pore volume of the MWW molecular sieve is 0.60 cm 3 The MWW molecular sieve of claim 13, wherein the molecular weight is greater than or equal to g.

17. The pore volume of the micropores of the MWW molecular sieve is 0.16 cm 3 The MWW molecular sieve of claim 13, wherein the molecular weight is greater than or equal to g.

18. 20. Use of the MWW structure molecular sieve according to any one of claims 13 to 17 for catalysis in alkylation, isomerization or cracking reactions.

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