Composite molecular sieve with EUO structure and MTW structure and preparation method and application thereof

Abstract

The present invention relates to the field of catalytic material synthesis, and discloses a composite molecular sieve having an EUO structure and an MTW structure, and a preparation method and application thereof, wherein the composite molecular sieve having an EUO structure and an MTW structure adopts silica-alumina gel as a composite silica-alumina source, and uses silica-alumina gel, an inorganic base, a template agent such as 1,4-bis(N-methylpyrrolidine)butane hydroxide, and water as raw materials, and is crystallized to obtain the composite molecular sieve. The molecular sieve synthesized by the present invention is a composite molecular sieve having an EUO structure and an MTW structure, and the ratio of the two-phase molecular sieve is adjustable.

Description

Technical Field

[0001] The present invention relates to the field of catalytic material synthesis, and in particular to a composite molecular sieve with EUO structure and MTW structure, and a preparation method and application thereof. Background Art

[0002] Composite molecular sieve is a composite molecular sieve with a special structure. It is a co-crystal formed by two or more molecular sieves, or a composite crystal with the structural characteristics of two or more molecular sieves. Due to the particularity of the composite molecular sieve structure, this molecular sieve has a more reasonably distributed pore structure, acidity and other properties, overcoming the limitations of a single molecular sieve, can better meet the needs of industrial applications, and has broad application prospects.

[0003] EUO molecular sieve has a 1-dimensional 10-membered ring pore structure, and the pore size of the 10-membered ring in the (100) direction is 0.41×0.54nm. It belongs to the medium-pore molecular sieve, among which EU-1 and ZSM-50 molecular sieves have EUO-type topological structure. Due to the unique pore structure characteristics of EUO molecular sieve, it has excellent shape selectivity in reactions such as xylene isomerization, linear alkane isomerization, and benzene isopropylation, and has broad catalytic application prospects. MTW molecular sieve has a 1-dimensional 12-membered ring pore structure, and the pore size of the 12-membered ring in the (010) direction is 0.56×0.60nm. It belongs to the large-pore molecular sieve, among which ZSM-12 molecular sieve has MTW-type topological structure. Due to its good thermal stability, unique pore structure and adjustable acidity, it exhibits good catalytic activity in reactions such as cracking, isomerization, reforming of alkanes and alkylation of aromatics. EUO structure and MTW structure are single one-dimensional mesopore and macropore molecular sieves respectively. Therefore, EUO structure and MTW structure composite molecular sieves have the characteristics of both one-dimensional mesopores and macropores.

[0004] At present, the template agents for synthesizing EUO structured molecular sieves mainly include alkylated derivatives of polymethylene α-ω-diamine ions or their precursors (US6514479), diphenylmethyl dimethyl ammonium and its derivatives (US6723301 and US6616910), 1,6-dibromohexane and anionic surfactants, 1-chloro-6-bromohexane (CN102452663A and CN104229817A), a mixture of N,N-dimethylbenzylamine and chlorinated toluene (reference (Zeolites, 1989, 9 (6): 483-490.)), hexamethyldiamine bromide (reference (Acta Petrolei Sinica (Petroleum Processing) 2008 Supplement: 226-229.)), tetraethylammonium hydroxide or tetraethylammonium bromide (CN102311125B), etc. At present, the organic template agents commonly used for synthesizing ZSM-12 molecular sieves mainly include tetraethylammonium (TEA +) ion (US4112056A), methyltriethylammonium (MTEA + ) ion halogenated compounds or hydroxides, dispiroalkane compounds (CN107602573B), etc. The literature (J.Phys.Chem.B 2003,107,5432-5440.) reported that 1-methyl-1-cyclohexylpyrrolidinium was used as a template agent to synthesize EU-1 and ZSM-12 molecular sieves in a HF-containing system, but EU-1 molecular sieves could only be synthesized under low silicon-aluminum ratio conditions, while ZSM-12 molecular sieves could be synthesized under all-silicon conditions, and ZSM-12 was more likely to coexist with β molecular sieves.

[0005] Although there are patents that introduce the preparation methods of EUO structure molecular sieves and MTW structure molecular sieves using various templates, there are no reports on the preparation methods of EUO structure and MTW structure composite molecular sieves. Summary of the invention

[0006] The purpose of the present invention is to provide a composite molecular sieve with EUO structure and MTW structure, and a preparation method and application thereof. Silica-alumina gel is used as a composite silica-alumina source for synthesis, and 1,4-bis(N-methylpyrrolidine)butane hydroxide is used as a template. The EUO structure and MTW structure composite molecular sieve have high crystallinity and the ratio of the two-phase molecular sieves is adjustable, which solves the problem that the prior art cannot synthesize EUO structure and MTW structure composite molecular sieves.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing a composite molecular sieve having an EUO structure and an MTW structure, comprising: crystallizing a mixture containing silica-alumina gel, an inorganic base, a template and water, wherein the crystallization time is less than or equal to 10 days, and the amount of the composite molecular sieve is 0.0447 W / mol. 2 Calculated silica alumina, OH - The amount of inorganic base is less than or equal to 0.55 mol, the amount of template is less than or equal to 0.4 mol, and the template is selected from at least one of the compounds shown in Formula I:

[0008]

[0009] In formula I, n=4.

[0010] The present invention also provides a composite molecular sieve having an EUO structure and an MTW structure.

[0011] The present invention also relates to the use of silica-alumina gel and / or the compound shown in formula I in the preparation of a composite molecular sieve having an EUO structure and an MTW structure.

[0012] Through the above technical scheme, the present invention can obtain a composite molecular sieve having an EUO structure and an MTW structure, and the ratio of the two-phase molecular sieves in the composite molecular sieve is adjustable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 XRD spectrum of the molecular sieve sample synthesized in Example 1;

[0014] Figure 2 XRD spectrum of the molecular sieve sample synthesized in Example 2;

[0015] Figure 3 This is a SEM photo of the molecular sieve sample synthesized in Example 2;

[0016] Figure 4 XRD spectrum of the molecular sieve sample synthesized in Example 3;

[0017] Figure 5 XRD spectrum of the molecular sieve sample synthesized in Example 4;

[0018] Figure 6 This is a SEM photo of the molecular sieve sample synthesized in Example 4;

[0019] Figure 7 XRD spectrum of the molecular sieve sample synthesized in Example 5;

[0020] Figure 8 XRD spectrum of the molecular sieve sample synthesized in Comparative Example 1;

[0021] Fig. 9 XRD spectrum of the molecular sieve sample synthesized in Comparative Example 2;

[0022] Fig.10 XRD spectrum of the molecular sieve sample synthesized in Comparative Example 3;

[0023] Fig.11 XRD spectrum of the molecular sieve sample synthesized in Comparative Example 4;

[0024] Fig.12 This is the XRD spectrum of the molecular sieve sample synthesized in Comparative Example 5. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] Technical terms in the present invention are defined according to their definitions, and are understood according to the common meanings in the art if not defined. The template in the present invention is also called a structure directing agent or an organic structure directing agent in the art.

[0027] The present invention provides a method for preparing a composite molecular sieve having an EUO structure and an MTW structure, characterized in that the method comprises: crystallizing a mixture containing silica-alumina gel, an inorganic base, a template and water, wherein the crystallization time is less than or equal to 10 days, and the amount of the composite molecular sieve is 0.0447 W / mol. 2 Calculated silica alumina, OH - The amount of inorganic base is less than or equal to 0.55 mol, the amount of template is less than or equal to 0.4 mol, and the template is selected from at least one of the compounds shown in Formula I:

[0028]

[0029] In formula I, n=4.

[0030] In the present invention, the SiO 2 With Al 2 O 3 The molar ratio is 20-70 (such as 22, 25, 28, 35, 40, 42, 45, 50, 55, 58, 60, 62, 65, 68 or any value therebetween).

[0031] In the present invention, relative to each mole of SiO 2 Calculated silica alumina, OH - The amount of inorganic base used is 0.1-0.5 mol (such as 0.12, 0.18, 0.22, 0.28, 0.32, 0.35, 0.38, 0.4, 0.44, 0.46, 0.48 mol or any value between the above values).

[0032] In the present invention, relative to each mole of SiO 2 The amount of the template used is 0.15-0.4 mol (such as 0.16, 0.17, 0.2, 0.25, 0.28, 0.32, 0.35, 0.38 mol or any value between the above values).

[0033] In the present invention, relative to each mole of SiO 2 For the silica-alumina gel, the amount of water used is 15-50 mol (such as 15, 18, 22, 28, 32, 35, 38, 42, 44, 46, 48 mol or any value between the above values).

[0034] In the present invention, there is no particular requirement for the selection of the inorganic base, which may be any common inorganic base in the art. Preferably, the inorganic base is selected from alkali metal hydroxides and / or alkaline earth metal hydroxides, more preferably sodium hydroxide.

[0035] In an embodiment of the present invention, the template agent is selected from 1,4-bis(N-methylpyrrolidine)butane hydroxide (ie, n=4).

[0036] In the present invention, there is no special requirement for the crystallization method. One-stage crystallization (such as crystallization at 110-165°C for 5-10 days) or two-stage crystallization can be used. In a preferred embodiment of the present invention, the crystallization includes sequentially performing a first stage crystallization and a second stage crystallization. More preferably, the temperature of the first stage crystallization is 25-55°C lower than the temperature of the second stage crystallization (such as 26, 28, 32, 35, 38, 42, 45, 48, 52, 54°C or any value between the above values). More preferably, the time of the first stage crystallization is 2-5 days shorter than the time of the second stage crystallization (such as 2.2, 2.8, 3.2, 3.5, 3.8, 4.2, 4.5, 4.8 days or any value between the above values).

[0037] More preferably, the conditions of the first stage of crystallization include: a temperature of 110-130° C. (such as 111, 112, 115, 118, 122, 128, 129° C. or any value therebetween). More preferably, the conditions of the first stage of crystallization also include: a time of 1-3 days (such as 1.1, 1.2, 1.3, 1.4, 1.8, 1.9, 2.1, 2.2, 2.8, 2.9 days or any value therebetween).

[0038] More preferably, the conditions for the second stage of crystallization include: a temperature of 155-165°C (such as 156, 158, 160, 162, 164°C or any value between the above values). More preferably, the conditions for the second stage of crystallization also include: a time of 4-6 days (such as 4.2, 4.5, 4.8, 5.2, 5.5, 5.8 days or any value between the above values).

[0039] In the present invention, the crystallization has no special requirements on the pressure, and can be autogenous pressure. The crystallization can be static crystallization or dynamic crystallization, preferably dynamic crystallization. As a condition for dynamic crystallization, the preferred rotation speed is 15-40r / min.

[0040] In the present invention, in order to obtain the molecular sieve (raw powder), the method may further include subjecting the crystallized product to solid-liquid separation, and then washing and drying the obtained solid phase in sequence to obtain the molecular sieve. Specifically, the solid-liquid separation method can be carried out by conventional methods, such as filtering, centrifugation, etc. In addition, the solid phase obtained by solid-liquid separation is washed before drying. The washing can be carried out by conventional methods, and in order to avoid the introduction of other impurities, it is preferably washed with deionized water to neutrality. The drying can be carried out at a temperature of 80-120°C, and the drying time can be selected according to the drying temperature, generally 4-12 hours.

[0041] The present invention also provides a composite molecular sieve having an EUO structure and an MTW structure, characterized in that the composite molecular sieve having an EUO structure and an MTW structure is prepared by the method as described above; or, the weight percentage of the EUO structure molecular sieve in the composite molecular sieve is 10-96%, and the weight percentage of the MTW structure molecular sieve is 4-90%.

[0042] The present invention also relates to the use of silica-alumina gel and / or the compound shown in formula I in the preparation of a composite molecular sieve having an EUO structure and an MTW structure.

[0043] The present invention will be described in detail below by way of examples. In the following examples and comparative examples,

[0044] X-ray powder diffraction (XRD) was performed using a PANalytical Empyrean diffractometer equipped with a PIXcel 3D Detector. Test conditions: Cu target, Kα radiation, Ni filter, tube voltage 40kV, tube current 40mA, scanning range 5°-35°. The weight percentage of molecular sieves with different physical phase structures in the composite molecular sieve is determined according to the characteristic peaks of each molecular sieve in the XRD spectrum, that is, the weight percentage of each phase is calculated according to the peak height of the characteristic peak of each molecular sieve. The specific calculation method is as follows: the characteristic peaks of the EUO structure molecular sieve are: 20.58°, 22.22° and 27.18°; the characteristic peaks of the MTW structure molecular sieve are 7.62°, 20.98° and 23.02°; the peak heights of the characteristic peaks of the EUO structure molecular sieve and the MTW structure molecular sieve are added respectively, and recorded as S1 and S2 respectively; the weight percentage of the EUO structure molecular sieve in the composite molecular sieve = S1 / (S1+S2)×100%; the weight percentage of the MTW structure molecular sieve = S2 / (S1+S2)×100%.

[0045] Scanning electron microscope morphology analysis (SEM) uses a Japanese Hitachi S4800 scanning electron microscope. Test conditions: After the sample is dried and ground, it is glued on a conductive adhesive. The acceleration voltage of the analysis electron microscope is 5.0 kV, and the magnification is 20-800000 times.

[0046] R represents the template 1,4-bis(N-methylpyrrolidino)butane hydroxide (1,4-MPBOH).

[0047] Silica-alumina gels with different silicon-alumina ratios were purchased from Dongying Yiming New Materials Co., Ltd.

[0048] Examples 1-5 are used to illustrate the synthesis of composite molecular sieves having EUO structure and MTW structure according to the method described in the present invention.

[0049] Example 1

[0050] Take 18.873 g of deionized water and add it to the polytetrafluoroethylene liner. Then add 1,4-bis(N-methylpyrrolidine)butane hydroxide (1,4-MPBOH) (mass fraction 35.58%) and NaOH (mass fraction 96%) in turn and stir to mix evenly. Then add silica-alumina gel (solid content 92.70% by weight, SiO 2 Mass fraction 95.50%, Al 2 O 3 Mass fraction 2.62%, SiO 2 / Al 2 O 3 =61.86), stirred evenly, wherein the added molar ratio of each component is: NaOH / SiO 2 =0.45, R / SiO 2 =0.15, H 2 O / SiO 2 =20.

[0051] The polytetrafluoroethylene liner containing the above reaction mixture is covered, placed in a stainless steel autoclave, sealed, and placed in a rotary convection oven with a rotation speed set to 20 r / min. Crystallization is carried out under autogenous pressure: first crystallize at 120°C for 1 day, then crystallize at 160°C for 5 days. After the crystallization is completed and the temperature is cooled to room temperature, the product is taken out, filtered, washed, and dried at 110°C for 12 hours to obtain a molecular sieve sample.

[0052] The obtained molecular sieve sample was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Figure 1 , which is a composite molecular sieve with EUO structure and MTW structure. XRD diffraction quantitative analysis shows that the weight percentage of EUO structure molecular sieve in the composite molecular sieve is 84.4%, and the weight percentage of MTW structure molecular sieve is 15.6%.

[0053] Example 2

[0054] The amount of NaOH added in Example 1 was changed to NaOH / SiO 2 =0.1.

[0055] The obtained molecular sieve sample was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Figure 2 , which is a composite molecular sieve with EUO structure and MTW structure. XRD diffraction quantitatively shows that the weight percentage of EUO structure molecular sieve in the composite molecular sieve is 14.7%, and the weight percentage of MTW structure molecular sieve is 85.3%. The morphology of the molecular sieve was observed by SEM, and the SEM photos are shown in Figure 3 , mainly in rod-like morphology and a small amount of spherical morphology.

[0056] Example 3

[0057] The amount of NaOH added in Example 1 was changed to NaOH / SiO 2 =0.2, the amount of template added becomes R / SiO 2 =0.3.

[0058] The obtained molecular sieve sample was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Figure 4 , which is a composite molecular sieve with EUO structure and MTW structure. XRD diffraction quantitative analysis shows that the weight percentage of EUO structure molecular sieve in the composite molecular sieve is 10.9%, and the weight percentage of MTW structure molecular sieve is 89.1%.

[0059] Example 4

[0060] Take 44.232 g of deionized water and add it to the polytetrafluoroethylene liner. Then add 1,4-bis(N-methylpyrrolidine)butane hydroxide (1,4-MPBOH) (mass fraction 35.58%) and NaOH (mass fraction 96%) in turn and stir to mix evenly. Then add silica-alumina gel (solid content 96.8% by weight, SiO 2 Mass fraction 94.18%, Al 2 O 3 Mass fraction 3.71%, SiO 2 / Al 2 O 3 =43.08), stirred evenly, wherein the added molar ratio of each component is: NaOH / SiO 2 =0.3, R / SiO 2 =0.15, H 2 O / SiO 2 =40.

[0061] The polytetrafluoroethylene liner containing the above reaction mixture is covered, placed in a stainless steel autoclave, sealed, and placed in a rotary convection oven with a rotation speed set to 20 r / min. Crystallization is carried out under autogenous pressure: first crystallize at 110°C for 3 days, then crystallize at 165°C for 5 days. After the crystallization is completed and the temperature is cooled to room temperature, the product is taken out, filtered, washed, and dried at 110°C for 12 hours to obtain a molecular sieve sample.

[0062] The obtained molecular sieve sample was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Figure 5 , which is a composite molecular sieve with EUO structure and MTW structure. XRD diffraction quantitatively shows that the weight percentage of EUO structure molecular sieve in the composite molecular sieve is 95.3%, and the weight percentage of MTW structure molecular sieve is 4.7%. The morphology of the molecular sieve was observed by SEM, and the SEM photos are shown in Figure 6 , mainly in spherical morphology and a small amount of rod-like morphology.

[0063] Example 5

[0064] Take 30.452 g of deionized water and add it to the polytetrafluoroethylene liner. Then add 1,4-bis(N-methylpyrrolidine)butane hydroxide (1,4-MPBOH) (mass fraction 35.58%) and NaOH (mass fraction 96%) in turn and stir to mix evenly. Then add silica-alumina gel (solid content 94.3% by weight, SiO 2 Mass fraction 92.56%, Al 2 O 3 Mass fraction 6.47%, SiO 2 / Al 2 O 3 =24.28), stirred evenly, wherein the added molar ratio of each component is: NaOH / SiO 2 =0.2, R / SiO 2 =0.15, H 2 O / SiO 2 =30.

[0065] The polytetrafluoroethylene liner containing the above reaction mixture is covered, placed in a stainless steel autoclave, sealed, and placed in a rotary convection oven with a rotation speed set to 20 r / min. Crystallization is carried out under autogenous pressure: first crystallize at 130°C for 1 day, then crystallize at 155°C for 6 days. After the crystallization is completed and the temperature is cooled to room temperature, the product is taken out, filtered, washed, and dried at 110°C for 12 hours to obtain a molecular sieve sample.

[0066] The obtained molecular sieve sample was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Figure 7 It is a composite molecular sieve with EUO structure and MTW structure. Quantitative analysis by XRD diffraction shows that the weight percentage of the EUO structure molecular sieve in the composite molecular sieve is 39.2%, and the weight percentage of the MTW structure molecular sieve is 60.8%.

[0067] Comparative Example 1

[0068] The same as in Example 1, except that NaOH / SiO 2 =0.6.

[0069] The obtained solid was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Figure 8 , for other molecular sieves, it is impossible to synthesize a composite molecular sieve with EUO structure and MTW structure.

[0070] Comparative Example 2

[0071] As in Example 3, except that no NaOH was added.

[0072] The obtained solid was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Fig. 9 , for other molecular sieves, it is impossible to synthesize a composite molecular sieve with EUO structure and MTW structure.

[0073] Comparative Example 3

[0074] According to Example 2, except that R / SiO 2 =0.45.

[0075] The obtained solid was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Fig.10 , for other molecular sieves, it is impossible to synthesize a composite molecular sieve with EUO structure and MTW structure.

[0076] Comparative Example 4

[0077] The same as in Example 1, except that the crystallization conditions are: first crystallization at 120° C. for 1 day, and then crystallization at 160° C. for 13 days.

[0078] The obtained solid was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Fig.11 , which is a NON structure molecular sieve, and cannot synthesize composite molecular sieves with EUO structure and MTW structure.

[0079] Comparative Example 5

[0080] The method is as in Example 1, except that coarse-porous silica gel (solid content 90.7%) is used as the silicon source, sodium aluminate (specific gravity 1.243 g / ml, Al 2 O 3 Mass concentration 101.5g / L, NaOH mass fraction 194.0g / L) is the aluminum source.

[0081] The obtained solid was subjected to X-ray diffraction analysis, and the XRD spectrum is shown in Fig.12 , for other molecular sieves, it can be seen that under the same ratio and crystallization conditions, the composite molecular sieves with EUO structure and MTW structure cannot be synthesized by using separate silicon source and aluminum source.

[0082] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a composite molecular sieve having an EUO structure and an MTW structure, characterized in that: The method comprises: crystallizing a mixture containing silica-alumina gel, an inorganic base, a template and water, wherein the crystallization time is less than or equal to 10 days, the crystallization comprises sequentially performing a first stage crystallization and a second stage crystallization, the conditions of the first stage crystallization comprise: a temperature of 110-130° C. and a time of 1-3 days, the conditions of the second stage crystallization comprise: a temperature of 155-165° C. and a time of 4-6 days, the molar ratio of SiO2 to Al2O3 in the silica-alumina gel is 20-70, and the molar ratio of OH to SiO2 per mole of the silica-alumina gel is 20-70. - The amount of inorganic base is less than or equal to 0.55 mol, the amount of template is less than or equal to 0.4 mol, and the template is selected from at least one of the compounds shown in Formula I: Formula I In formula I, n=4.

2. The method according to claim 1, wherein: Relative to each mole of silica-alumina gel in terms of SiO2, OH - The amount of inorganic base used is 0.1-0.5 mol, the amount of template used is 0.15-0.4 mol, and the amount of water used is 15-50 mol.

3. The method according to claim 1, wherein: The inorganic base is selected from alkali metal hydroxides and / or alkaline earth metal hydroxides.

4. The method according to claim 3, wherein: The inorganic base is selected from sodium hydroxide.

5. The method according to claim 1, wherein: The method further comprises performing solid-liquid separation on the crystallized product, and then washing and drying the obtained solid phase in sequence to obtain molecular sieve raw powder.

6. A composite molecular sieve having EUO structure and MTW structure, characterized in that: The composite molecular sieve is prepared by the method described in any one of claims 1 to 5.

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