Preparation methods of asymmetric gemini structure directing agent, SBT molecular sieve and FAU-SBT-SBS symbiotic molecular sieve

Abstract

The invention provides an asymmetric gemini structure directing agent and a preparation method of an SBT and FAU-SBT-SBS symbiotic molecular sieve, and relates to the technical field of molecular sieves. The invention provides an asymmetric gemini type structure directing agent, which is an asymmetric gemini type 1, 4-diazo bicyclo [2.2. 2] octane derivative. By adopting the asymmetric gemini structure directing agent provided by the invention, an aluminosilicate molecular sieve with an SBT topological structure can be synthesized in a window with a relatively wide silica-alumina ratio, and the specificity is high. The SBT molecular sieve and the preparation method of the FAU-SBT-SBS symbiotic molecular sieve provided by the invention have the advantages of wide silica-alumina ratio, high yield and good crystallinity, the synthesis process is simple, the raw materials are cheap and easy to obtain, and industrial amplification is easy to realize.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieves, and in particular to a method for preparing an asymmetric twin structure directing agent and an SBT molecular sieve and a FAU-SBT-SBS symbiotic molecular sieve. Background Art

[0002] Large-pore molecular sieves represented by Y molecular sieves are widely used in the fields of petroleum processing, environmental pollutant elimination and adsorption separation, while SBT molecular sieves with similar structures have not been widely studied and applied due to limitations in preparation methods. SBT molecular sieves exhibit high thermal stability in the catalytic cracking process, and have supercage and large-pore structures comparable to Y molecular sieves. These structural characteristics make them comparable to Y molecular sieves in catalytic and adsorption applications in terms of application potential and commercial value.

[0003] In 1997, Stucky et al. (Science, 278, 2080-2085 (1997)) first reported the synthesis of a phosphate molecular sieve UCSB-10 with skeleton atoms of metals such as Co and Zn, using linear flexible diamine molecules as structure-directing agents according to the host-guest charge density matching method. The structure has a three-dimensional macroporous channel structure, including a pore volume of about 1.14 nm. 3 The super cage has two apertures. and UCSB-10 has poor thermal stability and structural collapse after high-temperature calcination, which hinders its application in catalysis and separation. Until 2021, researchers used 1,4-dimethyl-1,4-diazobicyclo[2.2.2]octane (Me 2 -DABCO) as a structure-directing agent, successfully synthesized an aluminosilicate molecular sieve with SBT topology and named it PST-32. 2 -DABCO is used as a structure-directing agent to synthesize aluminosilicate molecular sieves with SBT topological structure. Its silicon-aluminum ratio (Si / Al) window is narrow (Si / Al=4, and the raw material composition range is only 5). Changing the raw material feed ratio can easily generate other molecular sieves such as ERI, and the structure-directing specificity is poor. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an asymmetric Gemini structure directing agent and a method for preparing SBT molecular sieves and FAU-SBT-SBS symbiotic molecular sieves. The asymmetric Gemini structure directing agent provided by the present invention can synthesize aluminosilicate molecular sieves with SBT topological structure in a wider silicon-aluminum ratio window with good specificity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an asymmetric twin structure directing agent having a structure shown in Formula I:

[0007]

[0008] In Formula I, R 1 and R 2 are independently alkyl groups having 1 to 8 carbon atoms, and R 1 and R 2 Different from each other; X 1 and X 2 are independently halogen or both are hydroxide.

[0009] Preferably, the R 1 is ethyl, propyl, isopropyl, butyl, sec-butyl, isopentyl, cyclopentyl, methylcyclopentyl, cyclohexyl or methylcyclohexyl, wherein R 2 It is methyl.

[0010] The present invention provides a method for preparing the asymmetric twin structure directing agent described in the above technical solution, comprising the following steps:

[0011] 1,4-diazabicyclo[2.2.2]octane, a first halogenated alkane and a first organic solvent are mixed to perform a first nucleophilic substitution reaction to obtain an intermediate product; the first halogenated alkane and the intermediate product have the structures shown in Formula II and Formula III respectively:

[0012] R 1 -X 1 Formula II,

[0013] The intermediate product is mixed with a second halogenated alkane and a second organic solvent to carry out a second nucleophilic substitution reaction to obtain X 1 and X 2 An asymmetric gemini-type structure directing agent having a structure shown in Formula I when independently halogen; the second halogenated alkane has a structure shown in Formula IV:

[0014] R 2 -X 2 Formula IV;

[0015] The X 1 and X 2 When the asymmetric Gemini structure directing agent of the structure shown in Formula I is independently halogen, ion exchange is performed through a strong basic anion exchange resin to obtain X 1 and X 2 When both are hydroxide groups, they are asymmetric gemini-type structure directing agents having the structure shown in Formula I.

[0016] Preferably, the molar ratio of the 1,4-diazabicyclo[2.2.2]octane to the first halogenated alkane is 1:1; and the molar ratio of the intermediate product to the second halogenated alkane is 1:1.2.

[0017] The present invention provides the use of the asymmetric gemini structure directing agent described in the above technical solution in the preparation of SBT molecular sieve or FAU-SBT-SBS symbiotic molecular sieve.

[0018] The present invention provides a method for preparing SBT molecular sieve, comprising the following steps:

[0019] A structure directing agent, an aluminum source, an alkali source, a silicon source and water are mixed for hydrothermal crystallization to obtain a crystallized product; the alkali source is sodium hydroxide and cesium hydroxide, and the structure directing agent is the asymmetric twin structure directing agent described in the above technical solution, wherein R 2 is methyl, R 1 is ethyl or propyl; the silicon source is SiO 2 Aluminum source is Al 2 O 3 Sodium hydroxide is measured as Na 2 O, cesium hydroxide as Cs 2 O, the molar ratio of the silicon source, the aluminum source, the sodium hydroxide, the cesium hydroxide, the structure directing agent and the water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20);

[0020] The crystallized product is calcined to obtain the SBT molecular sieve.

[0021] The present invention provides a method for preparing a FAU-SBT-SBS symbiotic molecular sieve, comprising the following steps:

[0022] An aluminum source, an alkali source, water, a silicon source and a structure directing agent are mixed for hydrothermal crystallization to obtain a crystallized product; the alkali source is sodium hydroxide and cesium hydroxide, and the structure directing agent is the asymmetric twin structure directing agent described in the technical solution of the transfer business, wherein R 2 is methyl, R 1 isopropyl, butyl or sec-butyl; the silicon source is SiO 2 Aluminum source is Al 2 O 3 Sodium hydroxide is measured as Na 2 O, cesium hydroxide as Cs 2 O, the molar ratio of the silicon source, the aluminum source, the sodium hydroxide, the cesium hydroxide, the structure directing agent and the water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20);

[0023] The crystallized product is calcined to obtain a FAU-SBT-SBS intergrowth molecular sieve.

[0024] Preferably, the aluminum source is one or more of aluminum sulfate, aluminum hydroxide, sodium aluminate and aluminum isopropoxide; the silicon source is one or more of sodium silicate, silica sol, white carbon black and tetraethyl orthosilicate.

[0025] Preferably, the hydrothermal crystallization temperature is 120-150° C., and the time is 168-336 hours.

[0026] Preferably, the silicon-aluminum molar ratio of the SBT molecular sieve or the FAU-SBT-SBS intergrowth molecular sieve is 3-8.

[0027] The present invention provides an asymmetric gemini structure directing agent having a structure shown in Formula I. The structure directing agent provided by the present invention is an asymmetric gemini 1,4-diazobicyclo[2.2.2]octane derivative. The asymmetric gemini structure directing agent provided by the present invention can synthesize aluminosilicate molecular sieves with SBT topological structure in a wide silicon-aluminum ratio window (3-8) with high specificity.

[0028] The present invention provides a method for preparing the structure directing agent described in the above technical solution, which has a simple process and is easy to synthesize.

[0029] The present invention provides a method for preparing SBT molecular sieve and FAU-SBT-SBS symbiotic molecular sieve. The present invention adopts the asymmetric twin structure directing agent for the first time to synthesize SBT molecular sieve or FAU-SBT-SBS symbiotic molecular sieve, and has a wide silicon-aluminum ratio window, high yield (60-82%), and good crystallinity, which is beneficial to improving the synthesis specificity and realizing the regulation of the acidity and diffusion mass transfer performance of the molecular sieve; in addition, the present invention can directly synthesize SBT molecular sieve or FAU-SBT-SBS symbiotic molecular sieve by a one-step hydrothermal method, the process is simple, the raw materials are cheap and easy to obtain, and industrial scale-up is easy to achieve. The present invention can guide the generation of SBT molecular sieve and FAU-SBT-SBS symbiotic molecular sieve respectively by regulating the structure of the structure directing agent, and provides a new method for controlling the structure and composition of the molecular sieve. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The structural formula of the structure directing agent Me-DABCO-Et prepared in Example 1 is 1 H. 13 C NMR spectrum, Figure 1 (a) is the structural formula of Me-DABCO-Et and 13 C NMR spectrum, (b) is the structural formula of Me-DABCO-Et and 1 H NMR spectrum;

[0031] Figure 2 The structural formula of the structure directing agent Me-DABCO-iPr prepared in Example 2 is 1 H. 13 C NMR spectrum, Figure 2 (a) is the structural formula of Me-DABCO-iPr and 13 C NMR spectrum, (b) the structural formula of Me-DABCO-iPr and 1 H NMR spectrum;

[0032] Figure 3 The structural formula of the structure directing agent Me-DABCO-sBu prepared in Example 3 is 1 H. 13 C NMR spectrum, Figure 3 (a) is the structural formula of Me-DABCO-sBu and 13 C NMR spectrum, (b) is the structural formula of Me-DABCO-sBu and 1 H NMR spectrum;

[0033] Figure 4 The X-ray diffraction pattern (XRD) of the SBT molecular sieve prepared in Example 4;

[0034] Figure 5 This is a scanning electron microscope image (SEM) of the SBT molecular sieve prepared in Example 4;

[0035] Figure 6 N is the SBT molecular sieve prepared in Example 4 2 Adsorption curve;

[0036] Figure 7 The solid state of SBT molecular sieve before calcination in Example 4 13 C MAS NMR spectrum;

[0037] Figure 8 This is the X-ray diffraction pattern (XRD) of the FAU-SBT-SBS molecular sieve prepared in Example 5;

[0038] Fig. 9 This is a scanning electron microscope (SEM) image of the FAU-SBT-SBS molecular sieve prepared in Example 5;

[0039] Fig.10 This is the X-ray diffraction pattern (XRD) of the FAU-SBT-SBS molecular sieve prepared in Example 6;

[0040] Fig.11 This is a scanning electron microscope image (SEM) of the FAU-SBT-SBS molecular sieve prepared in Example 6;

[0041] Fig.12 This is the X-ray diffraction pattern (XRD) of the SBT molecular sieve prepared in Example 7;

[0042] Fig.13 This is a scanning electron microscope (SEM) image of the SBT molecular sieve prepared in Example 7. DETAILED DESCRIPTION

[0043] The present invention provides an asymmetric twin structure directing agent having a structure shown in Formula I:

[0044]

[0045] In Formula I, R 1 and R 2 are independently alkyl groups having 1 to 8 carbon atoms, and R 1 and R 2 Different from each other; X 1 and X 2 are independently halogen or both are hydroxide.

[0046] In the present invention, the asymmetric gemini structure directing agent is an asymmetric gemini 1,4-diazobicyclo[2.2.2]octane derivative having a gemini quaternary ammonium salt structure, connected in the middle by 1,4-diazabicyclo[2.2.2]octane. The chemical formula of the asymmetric gemini structure directing agent is R 1 (C 6 H 12 N 2 2+ )R 2 (X 1 - X 2 - ), in the embodiment of the present invention, the asymmetric twin structure directing agent is abbreviated as R 1 -DABCO-R 2 .

[0047] In the present invention, the R 1 Preferably, it is ethyl (Et), propyl, isopropyl (iPr), butyl (Bu), sec-butyl (sBu), isopentyl (iPe), cyclopentyl (cPe), methylcyclopentyl (mcPe), cyclohexyl (cHe) or methylcyclohexyl (mcHe). The present invention has no particular requirements on the substitution position of the methyl in the methylcyclopentyl and methylcyclohexyl. The R 2 Preferably methyl; the halogen may be fluorine, chlorine, bromine or iodine, the X 1 and X 2 They can be the same halogen or different halogens. 1is ethyl (Et), propyl, isopropyl (iPr), butyl (Bu), sec-butyl (sBu), isopentyl (iPe), cyclopentyl (cPe), methylcyclopentyl (mcPe), cyclohexyl (cHe) or methylcyclohexyl (mcHe), wherein R 2 When it is methyl, the chemical names of the corresponding asymmetric gemini structure directing agents are 1-methyl-4-ethyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-propyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-isopropyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-butyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-sec-butyl-1,4-diazobicyclo[2.2.2]octane, Cyclo[2.2.2]octane, 1-methyl-4-isopentyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-cyclopentyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-methylcyclopentyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-cyclohexyl-1,4-diazobicyclo[2.2.2]octane, 1-methyl-4-methylcyclohexyl-1,4-diazobicyclo[2.2.2]octane.

[0048] The present invention provides a method for preparing the asymmetric twin structure directing agent described in the above technical solution, comprising the following steps:

[0049] 1,4-diazabicyclo[2.2.2]octane, a first halogenated alkane and a first organic solvent are mixed to perform a first nucleophilic substitution reaction to obtain an intermediate product; the first halogenated alkane and the intermediate product have the structures shown in Formula II and Formula III respectively:

[0050] R 1 -X 1 Formula II,

[0051] The intermediate product is mixed with a second halogenated alkane and a second organic solvent to carry out a second nucleophilic substitution reaction to obtain X 1 and X 2 An asymmetric gemini-type structure directing agent having a structure shown in Formula I when independently halogen; the second halogenated alkane has a structure shown in Formula IV:

[0052] R 2 -X 2 Formula IV;

[0053] The X 1 and X 2 When the asymmetric Gemini structure directing agent of the structure shown in Formula I is independently halogen, ion exchange is performed through a strong basic anion exchange resin to obtain X 1 and X 2When both are hydroxide groups, they are asymmetric gemini-type structure directing agents having the structure shown in Formula I.

[0054] In the present invention, unless otherwise specified, all raw materials involved are commercially available products.

[0055] In the present invention, 1,4-diazabicyclo[2.2.2]octane, a first halogenated alkane and a first organic solvent are mixed to perform a first nucleophilic substitution reaction to obtain an intermediate product. In the present invention, the first halogenated alkane and the intermediate product have structures shown in Formula II and Formula III, respectively, and R 1 and X 1 With R in Formula Ⅰ 1 and X 1 The first halogenated alkane is preferably halogenated ethane, halogenated propane, halogenated isopropane, halogenated butane, halogenated sec-butane, halogenated isopentane, halogenated cyclopentane, halogenated methylcyclopentane, halogenated cyclohexane or halogenated methylcyclohexane. In the present invention, the molar ratio of the 1,4-diazabicyclo[2.2.2]octane to the first halogenated alkane is 1:1, and the first organic solvent can be ethyl acetate, methanol or ethanol. The present invention has no special requirements for the amount of the first organic solvent, as long as the raw material is dissolved and the reaction proceeds smoothly.

[0056] In the present invention, the method for mixing the 1,4-diazabicyclo[2.2.2]octane, the first halogenated alkane and the first organic solvent is preferably: adding 1,4-diazabicyclo[2.2.2]octane to the first organic solvent, stirring until completely dissolved, and then slowly dropping the first halogenated alkane therein.

[0057] In the present invention, the temperature of the first nucleophilic substitution reaction is preferably 25-50°C, and may be 25, 30, 40 or 50°C. The time is preferably 4-48h, and may be 4, 12, 24 or 48h.

[0058] After the first nucleophilic substitution reaction is completed, the present invention preferably washes the obtained reaction product with acetone or ether, and then filters and vacuum-dries it in sequence to obtain the intermediate product; in an embodiment of the present invention, the vacuum drying time is 12 hours.

[0059] After obtaining the intermediate product, the present invention mixes the intermediate product with a second halogenated alkane and a second organic solvent to perform a second nucleophilic substitution reaction to obtain X 1 and X 2 When the second halogenated alkane is independently a halogen, the asymmetric gemini-type structure directing agent (i.e., a halogen-type structure directing agent) has the structure shown in Formula I. In the present invention, the second halogenated alkane has the structure shown in Formula IV, wherein R 2 and X 2 With R in Formula Ⅰ 2 and X2 Keeping the same, the second halogenated alkane is preferably methyl halide. In the present invention, the molar ratio of the intermediate product to the second halogenated alkane is preferably 1:1.2; the second organic solvent can be acetonitrile, methanol or ethanol, and the present invention has no special requirements for the amount of the second organic solvent, as long as the raw material is dissolved and the reaction proceeds smoothly.

[0060] In the present invention, the method of mixing the intermediate product with the second halogenated alkane and the second organic solvent is preferably: dissolving the intermediate product in the second organic solvent, stirring until completely dissolved, and then slowly dropping the second halogenated alkane therein.

[0061] In the present invention, the temperature of the second nucleophilic substitution reaction is preferably 10-80°C, and may be 25, 30, 40, 50, 60, 70 or 80°C, and the time is preferably 12-48h, and may be 12, 24 or 48h.

[0062] After the second nucleophilic substitution reaction is completed, the obtained reaction product is preferably washed with acetone, filtered and vacuum dried in sequence to obtain X 1 and X 2 When independently halogen, the asymmetric gemini structure directing agent has the structure shown in Formula I; in the embodiment of the present invention, the vacuum drying time is 12 hours.

[0063] In the present invention, preparation X 1 and X 2 When the asymmetric gemini structure directing agent of the structure shown in formula I is independently halogen, the reaction formula involved is as follows:

[0064]

[0065] The invention uses 1,4-diazabicyclo[2.2.2]octane (i.e. 1,4-diazobicyclo[2.2.2]octane) as a raw material, strictly controls the molar ratio of reactants, and adopts a two-step method to connect different groups on both sides of 1,4-diazabicyclo[2.2.2]octane to obtain an asymmetric gemini 1,4-diazobicyclo[2.2.2]octane derivative.

[0066] The present invention converts the X 1 and X 2 When the asymmetric Gemini structure directing agent of the structure shown in Formula I is independently halogen, ion exchange is performed through a strong basic anion exchange resin to obtain X 1 and X 2 When both are hydroxide groups, the asymmetric Gemini structure directing agent (ie, hydroxide type structure directing agent) has the structure shown in Formula I. In the present invention, the strong basic anion exchange resin is preferably a 717 type anion exchange resin.

[0067] In the present invention, the specific operation of the ion exchange is preferably: 1 and X 2 The asymmetric twin structure directing agent of the structure shown in Formula I is dissolved in water, and the strong basic anion exchange resin is added thereto for ion exchange to obtain an ion exchange liquid; the ion exchange liquid is subjected to rotary evaporation to obtain X 1 and X 2 When all of them are hydroxide groups, the asymmetric twin structure directing agent has the structure shown in Formula I. In the present invention, the number of ion exchanges is preferably 3 times, and the time of each ion exchange is preferably 8 hours.

[0068] The preparation method of the asymmetric twin-type structure directing agent provided by the present invention has a simple process.

[0069] The present invention provides the use of the asymmetric Gemini structure directing agent described in the above technical solution in the preparation of SBT molecular sieve or FAU-SBT-SBS symbiotic molecular sieve. The asymmetric Gemini structure directing agent provided by the present invention can synthesize aluminosilicate molecular sieves with SBT topological structure in a wider silicon-aluminum ratio window, and the structure directing specificity is good.

[0070] The present invention provides a method for preparing SBT molecular sieve, comprising the following steps:

[0071] An aluminum source, an alkali source, water, a silicon source and a structure directing agent are mixed for hydrothermal crystallization to obtain a crystallized product; the alkali source is sodium hydroxide and cesium hydroxide, and the structure directing agent is the asymmetric twin structure directing agent described in the above technical solution, wherein R 2 is methyl, R 1 is ethyl or propyl; the silicon source is SiO 2 Aluminum source is Al 2 O 3 Sodium hydroxide is measured as Na 2 O, cesium hydroxide as Cs 2 O, the molar ratio of the silicon source, the aluminum source, the sodium hydroxide, the cesium hydroxide, the structure directing agent and the water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20);

[0072] The crystallized product is calcined to obtain SBT molecular sieve (pure phase).

[0073] The invention mixes an aluminum source, an alkali source, water, a silicon source and a structure directing agent for hydrothermal crystallization to obtain a crystallized product.

[0074] In the present invention, the alkali source is sodium hydroxide and cesium hydroxide, and the structure directing agent is the asymmetric gemini structure directing agent described in the above technical solution, wherein R2 is methyl, R 1 is ethyl or propyl; the aluminum source is preferably one or more of aluminum sulfate, aluminum hydroxide, sodium aluminate and aluminum isopropoxide; the silicon source is preferably one or more of sodium silicate, silica sol, white carbon black and ethyl orthosilicate; the water is preferably deionized water. In the present invention, the silicon source is SiO 2 Aluminum source is Al 2 O 3 Sodium hydroxide is measured as Na 2 O, cesium hydroxide as Cs 2 O, the molar ratio of the silicon source, aluminum source, sodium hydroxide, cesium hydroxide, structure directing agent and water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20), and can be 1:(0.05-0.08):(0.15-0.30):(0.02-0.025):(0.03-0.06):(10-12).

[0075] In the present invention, the method for mixing the aluminum source, alkali source, water, silicon source and structure directing agent is preferably: stirring the aluminum source, alkali source and water evenly at room temperature, statically aging at 120°C for 12 hours, adding the silicon source thereto, and stirring to form a uniform sol; adding the structure directing agent to the sol, and mixing again evenly.

[0076] In the present invention, the temperature of the hydrothermal crystallization is preferably 120-150°C, which can be 120, 130, 140 or 150°C, and the time is preferably 168-504h, which can be 168, 336 or 504h; the hydrothermal crystallization can be carried out under static or dynamic conditions, and the dynamic conditions are preferably carried out under rotating conditions, specifically to keep the reactor used for the hydrothermal crystallization rotating, and the rotating speed is preferably 10-80rpm, which can be 60rpm. In the present invention, the hydrothermal crystallization is specifically carried out in a hydrothermal reactor.

[0077] After the hydrothermal crystallization is completed, the present invention preferably sequentially performs solid-liquid separation, solid phase washing and drying on the obtained reaction solution to obtain the crystallized product. In the present invention, the solid-liquid separation method can be centrifugation.

[0078] After obtaining the crystallized product, the present invention calcines the crystallized product to obtain the SBT molecular sieve. In the present invention, the calcination temperature is preferably 550°C, the time is preferably 6 to 10 hours, and the heating rate from room temperature to the calcination temperature is preferably 1°C·min -1 The present invention removes the organic structure directing agent and moisture through the calcination.

[0079] In the present invention, the silicon-aluminum molar ratio of the SBT molecular sieve is 3-8, and can be 3, 3.4, 4, 4.1, 4.6, 5, 6, 6.8, 7 or 8.

[0080] The present invention provides a method for preparing a FAU-SBT-SBS symbiotic molecular sieve, comprising the following steps:

[0081] An aluminum source, an alkali source, water, a silicon source and a structure directing agent are mixed for hydrothermal crystallization to obtain a crystallized product; the alkali source is sodium hydroxide and cesium hydroxide, and the structure directing agent is the asymmetric twin structure directing agent described in the above technical solution, wherein R 2 is methyl, R 1 isopropyl, butyl or sec-butyl; the silicon source is SiO 2 Aluminum source is Al 2 O 3 Sodium hydroxide is measured as Na 2 O, cesium hydroxide as Cs 2 O, the molar ratio of the silicon source, the aluminum source, the sodium hydroxide, the cesium hydroxide, the structure directing agent and the water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20);

[0082] The crystallized product is calcined to obtain a FAU-SBT-SBS intergrowth molecular sieve.

[0083] The invention mixes an aluminum source, an alkali source, water, a silicon source and a structure directing agent for hydrothermal crystallization to obtain a crystallized product.

[0084] In the present invention, the alkaline source is sodium hydroxide and cesium hydroxide, that is, the molecular sieve is synthesized in an alkaline system; the structure directing agent is the asymmetric gemini structure directing agent described in the above technical solution, wherein R 2 is methyl, R 1 is isopropyl, butyl or sec-butyl; the aluminum source is preferably one or more of aluminum sulfate, aluminum hydroxide, sodium aluminate and aluminum isopropoxide; the silicon source is preferably one or more of sodium silicate, silica sol, white carbon black and ethyl orthosilicate; the water is preferably deionized water. In the present invention, the silicon source is SiO 2 Aluminum source is Al 2 O 3 Sodium hydroxide is measured as Na 2 O, cesium hydroxide as Cs 2O, the molar ratio of the silicon source, aluminum source, sodium hydroxide, cesium hydroxide, structure directing agent and water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20), and can be 1:(0.05-0.1):(0.15-0.30):(0.02-0.025):(0.03-0.06):(10-15).

[0085] In the present invention, the method for mixing the aluminum source, alkali source, water, silicon source and structure directing agent is preferably: stirring the aluminum source, alkali source and water evenly at room temperature, statically aging at 120°C for 12 hours, adding the silicon source thereto, and stirring to form a uniform sol; adding the structure directing agent to the sol, and mixing again evenly.

[0086] In the present invention, the temperature of the hydrothermal crystallization is preferably 120-150°C, and may be 120, 130, 140 or 150°C. The time is preferably 168-504h, and may be 168, 336 or 504h. The hydrothermal crystallization is specifically carried out in a hydrothermal kettle.

[0087] After the hydrothermal crystallization is completed, the present invention preferably sequentially performs solid-liquid separation, solid phase washing and drying on the obtained reaction solution to obtain the crystallized product. In the present invention, the solid-liquid separation method can be centrifugation.

[0088] After obtaining the crystallized product, the present invention calcines the crystallized product to obtain the FAU-SBT-SBS intergrowth molecular sieve. In the present invention, the calcination temperature is preferably 550°C, the time is preferably 6 to 10 hours, and the heating rate from room temperature to the calcination temperature is preferably 1°C·min -1 .

[0089] In the present invention, the silicon-aluminum molar ratio of the FAU-SBT-SBS intergrowth molecular sieve is 3-8, and can be 3, 3.4, 4, 4.1, 4.6, 5, 6, 6.8, 7 or 8.

[0090] Symbiotic molecular sieves have attracted widespread attention from scientists due to their unique structure and unique properties, such as different diffusion paths and special crystal pore environments of metal active sites. The FAU-SBT-SBS symbiotic molecular sieve has the periodic structural units of both FAU and SBT molecular sieves. Through the repeated stacking of the periodic structural units of FAU and SBT, the FAU-SBT-SBS symbiotic molecular sieve has a structure similar to that of FAU and SBT, and also has the potential for catalytic and adsorption applications. The related technology mainly synthesizes the FAU-SBT-SBS symbiotic molecular sieve by regulating the concentration of inorganic cations, but it is necessary to strictly control the feed ratio of Cs\Na\Al to control the physical phase, which is easy to generate competitive impurities and difficult to scale up industrially. The present invention adopts the asymmetric gemini structure directing agent to synthesize the FAU-SBT-SBS symbiotic molecular sieve, that is, the present invention mainly controls the physical phase through the structure directing agent, provides a new strategy for the synthesis of symbiotic molecular sieves, and is easy to scale up industrially.

[0091] The present invention adopts a new structure directing agent, and can directly synthesize SBT molecular sieve (single-phase molecular sieve) and FAU-SBT-SBS symbiotic molecular sieve (three-phase symbiotic molecular sieve) with a higher silicon-aluminum ratio by one-step hydrothermal synthesis. The silicon-aluminum ratio of the product is adjustable, and the silicon-aluminum ratio window is wide. The preparation method of the SBT molecular sieve and the FAU-SBT-SBS symbiotic molecular sieve provided by the present invention is simple in process, the raw materials are cheap and easy to obtain, the cost is low, and the preparation process is easy to achieve industrial scale-up. The synthesis method of synthesizing symbiotic molecular sieves by selecting different structure directing agents provided by the present invention has not been reported before.

[0092] In order to further illustrate the present invention, the preparation methods of the asymmetric gemini structure directing agent, SBT molecular sieve and FAU-SBT-SBS symbiotic molecular sieve provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0093] Example 1

[0094] Preparation of asymmetric gemini structure directing agents:

[0095] The raw material 1,4-diazabicyclo[2.2.2]octane (0.20 mol) was added to 200 mL of ethyl acetate and stirred until completely dissolved to obtain a 1,4-diazabicyclo[2.2.2]octane solution; iodoethane (0.20 mol) was slowly added dropwise to the 1,4-diazabicyclo[2.2.2]octane solution, stirred at room temperature for 4 hours, washed with acetone, filtered, and vacuum dried for 12 hours to obtain a white solid product, i.e., 1-ethyl-1,4-diazobicyclo[2.2.2]octane iodide;

[0096] 1-Ethyl-1,4-diazobicyclo[2.2.2]octane iodide (0.1 mol) was dissolved in acetonitrile and stirred until completely dissolved to obtain a 1-ethyl-1,4-diazobicyclo[2.2.2]octane iodide solution; iodomethane (0.12 mol) was slowly added dropwise to the 1-ethyl-1,4-diazobicyclo[2.2.2]octane iodide solution, refluxed at 60° C. for 24 h, washed with acetone, filtered, and vacuum dried for 12 h to obtain a white solid product, 1-methyl-4-ethyl-1,4-diazobicyclo[2.2.2]octane gemini quaternary ammonium salt, recorded as Me-DABCO-Et.

[0097] Figure 1 The structural formula of the structure directing agent Me-DABCO-Et prepared in Example 1 is 1 H. 13 C NMR spectrum, Figure 1 (a) is the structural formula of Me-DABCO-Et and 13 C NMR spectrum, (b) is the structural formula of Me-DABCO-Et and 1 H NMR spectrum.

[0098] The obtained Me-DABCO-Et was dissolved in water, and 717 type anion exchange resin was added, and ion exchange was performed 3 times, each time for 8 hours. Finally, the obtained solution was rotary evaporated to obtain the hydroxide form of Me-DABCO-Et (denoted as Me-DABCO-Et(OH) 2 ), and the final concentration was determined by titration.

[0099] Example 2

[0100] Preparation of asymmetric gemini structure directing agents:

[0101] The raw material 1,4-diazabicyclo[2.2.2]octane (0.20 mol) was added to 200 mL of ethyl acetate and stirred until completely dissolved to obtain a 1,4-diazabicyclo[2.2.2]octane solution; 2-bromopropane (0.20 mol) was slowly added dropwise to the 1,4-diazabicyclo[2.2.2]octane solution, stirred at room temperature for 48 hours, washed with ether and recrystallized, filtered, and vacuum dried for 12 hours to obtain a white solid product, i.e., 1-isopropyl-1,4-diazobicyclo[2.2.2]octane bromide;

[0102] 1-isopropyl-1,4-diazobicyclo[2.2.2]octane bromide (0.1 mol) was dissolved in methanol and stirred until completely dissolved to obtain a 1-isopropyl-1,4-diazobicyclo[2.2.2]octane bromide solution; iodomethane (0.12 mol) was slowly added dropwise to the 1-isopropyl-1,4-diazobicyclo[2.2.2]octane bromide solution, reacted at room temperature for 24 hours, washed with acetone and recrystallized, filtered, and vacuum dried for 12 hours to obtain a white solid product, bromoiodine type 1-methyl-4-isopropyl-1,4-diazobicyclo[2.2.2]octane gemini quaternary ammonium salt, recorded as Me-DABCO-iPr.

[0103] Figure 2 The structural formula of the structure-directing agent Me-DABCO-iPr prepared in Example 2 is 1 H. 13 C NMR spectrum, Figure 2 (a) is the structural formula of Me-DABCO-iPr and 13 C NMR spectrum, (b) the structural formula of Me-DABCO-iPr and 1 H NMR spectrum.

[0104] The obtained Me-DABCO-iPr was dissolved in water, and 717 type anion exchange resin was added. Ion exchange was performed 3 times, each time for 8 hours. Finally, the obtained solution was rotary evaporated to obtain the hydroxide-type Me-DABCO-iPr (denoted as Me-DABCO-iPr(OH) 2 ), and the final concentration was determined by titration.

[0105] Example 3

[0106] Preparation of asymmetric gemini structure directing agents:

[0107] The raw material 1,4-diazabicyclo[2.2.2]octane (0.20 mol) was added to 200 mL of ethyl acetate and stirred until completely dissolved to obtain a 1,4-diazabicyclo[2.2.2]octane solution; 2-bromobutane (0.20 mol) was slowly added dropwise to the 1,4-diazabicyclo[2.2.2]octane solution, refluxed at 50° C. for 48 h, washed with acetone, filtered, and vacuum dried for 12 h to obtain a white solid product, i.e., 1-sec-butyl-1,4-diazobicyclo[2.2.2]octane bromide;

[0108] 1-sec-butyl-1,4-diazobicyclo[2.2.2]octane bromide (0.1 mol) was dissolved in acetonitrile and stirred until completely dissolved to obtain a 1-sec-butyl-1,4-diazobicyclo[2.2.2]octane bromide solution; iodomethane (0.12 mol) was slowly added dropwise to the 1-sec-butyl-1,4-diazobicyclo[2.2.2]octane bromide solution, refluxed at 60° C. for 24 h, washed with acetone, filtered, and vacuum dried for 12 h to obtain a white solid product, bromoiodine type 1-methyl-4-sec-butyl-1,4-diazobicyclo[2.2.2]octane gemini quaternary ammonium salt, recorded as Me-DABCO-sBu.

[0109] Figure 3 The structural formula of the structure directing agent Me-DABCO-sBu prepared in Example 3 is 1 H. 13 C NMR spectrum, Figure 3 (a) is the structural formula of Me-DABCO-sBu and 13 C NMR spectrum, (b) is the structural formula of Me-DABCO-sBu and 1 H NMR spectrum.

[0110] The obtained Me-DABCO-sBu was dissolved in water, and 717 type anion exchange resin was added, and ion exchange was performed 3 times, each time for 8 hours. Finally, the obtained solution was rotary evaporated to obtain the hydroxide form of Me-DABCO-sBu (denoted as Me-DABCO-sBu(OH) 2 ), and the final concentration was determined by titration.

[0111] Example 4

[0112] (1) Accurately weigh 0.69 g of sodium hydroxide (96 wt%), 0.75 g of cesium hydroxide aqueous solution (50 wt%), 0.80 g of aluminum hydroxide (78 wt%), and 3.56 g of deionized water, stir them evenly at room temperature, and place them statically at 120° C. for aging for 12 h;

[0113] (2) Add 7.51 g of silica sol (Ludox-HS-40) to the solution obtained in step (1) and stir again;

[0114] (3) Add 2.87 g of the structure directing agent Me-DABCO-Et(OH) prepared in Example 1 to the solution obtained in step (2) 2 The aqueous solution (15 wt%) was stirred at room temperature for 24 h to form a uniform solution; the obtained solution was transferred to a 25 mL hydrothermal kettle and subjected to static hydrothermal crystallization at 120 ° C for 336 h;

[0115] (4) The solid obtained in step (3) is centrifuged, washed, dried, and calcined to obtain a pure phase SBT molecular sieve. The calcination conditions are 1°C·min -1 The heating rate was from room temperature to 550°C and calcined at this temperature for 8h.

[0116] The yield of the SBT molecular sieve obtained in Example 4 was 72% (the yield was calculated as the ratio of the mass of the molecular sieve obtained after the reaction to the mass of the molecular sieve that should be obtained theoretically), and the silicon-aluminum ratio (Si / Al) was 4.6.

[0117] Figure 4 This is the X-ray diffraction pattern (XRD) of the SBT molecular sieve prepared in Example 4, which proves that the synthesized molecular sieve is a pure phase SBT molecular sieve with good crystallinity.

[0118] Figure 5 This is a scanning electron microscope (SEM) image of the SBT molecular sieve prepared in Example 4. The obtained SBT molecular sieve has a hexagonal sheet structure and is relatively regular.

[0119] Figure 6 N is the SBT molecular sieve prepared in Example 4 2 Adsorption curve, the specific surface area of ​​SBT molecular sieve is 551m 2 ·g -1 .

[0120] Figure 7 The solid state of SBT molecular sieve before calcination in Example 4 13 C MAS NMR spectrum. Figure 7 It can be seen that the structure directing agent is not decomposed.

[0121] Example 5

[0122] (1) Accurately weigh 0.69 g of sodium hydroxide (96 wt%), 0.75 g of cesium hydroxide aqueous solution (50 wt%), 0.80 g of aluminum hydroxide (78 wt%), and 3.46 g of deionized water, stir them evenly at room temperature, and place them statically at 120° C. for aging for 12 h;

[0123] (2) Add 7.51 g of silica sol (Ludox-HS-40) to the solution obtained in step (1) and stir again;

[0124] (3) Add 2.47 g of the structure directing agent Me-DABCO-iPr(OH) prepared in Example 2 to the solution obtained in step (2) 2 The aqueous solution (15 wt%) was stirred at room temperature for 24 h to form a uniform solution; the obtained solution was transferred to a 25 mL hydrothermal kettle and subjected to static hydrothermal crystallization at 120 ° C for 336 h;

[0125] (4) The solid obtained in step (3) is centrifuged, washed, dried, and calcined to obtain FAU-SBT-SBS molecular sieve. The calcination conditions are 1°C·min -1 The heating rate was from room temperature to 550°C and calcined at this temperature for 8h.

[0126] The yield of the SBT molecular sieve obtained in Example 5 is 82%, and the silicon-aluminum ratio (Si / Al) is 4.1.

[0127] Figure 8 This is the X-ray diffraction pattern (XRD) of the FAU-SBT-SBS molecular sieve prepared in Example 5, which confirms the successful synthesis of FAU-SBT-SBS without impurities.

[0128] Fig. 9 This is a scanning electron microscope (SEM) image of the FAU-SBT-SBS molecular sieve prepared in Example 5, and the morphology is a stacked flaky structure.

[0129] Example 6

[0130] (1) Accurately weigh 0.69 g of sodium hydroxide (96 wt%), 0.75 g of cesium hydroxide aqueous solution (50 wt%), 0.80 g of aluminum hydroxide (78 wt%), and 3.11 g of deionized water, stir them evenly at room temperature, and place them statically at 120° C. for aging for 12 h;

[0131] (2) Add 7.51 g of silica sol (Ludox-HS-40) to the solution obtained in step (1) and stir again;

[0132] (3) Add 2.22 g of the structure directing agent Me-DABCO-sBu(OH) prepared in Example 3 to the solution obtained in step (2) 2 The aqueous solution (15 wt%) was stirred at room temperature for 24 h to form a uniform solution; the obtained solution was transferred to a 25 mL hydrothermal kettle and subjected to static hydrothermal crystallization at 120 ° C for 336 h;

[0133] (4) The solid obtained in step (3) is centrifuged, washed, dried, and calcined to obtain FAU-SBT-SBS molecular sieve. The calcination conditions are 1°C·min -1 The heating rate was from room temperature to 550°C and calcined at this temperature for 8h.

[0134] The yield of the SBT molecular sieve obtained in Example 6 is 79%, and the silicon-aluminum ratio (Si / Al) is 3.4.

[0135] Fig.10This is the X-ray diffraction pattern (XRD) of the FAU-SBT-SBS molecular sieve prepared in Example 6, which confirms the successful synthesis of FAU-SBT-SBS.

[0136] Fig.11 This is a scanning electron microscope (SEM) image of the FAU-SBT-SBS molecular sieve prepared in Example 6, and the morphology is a stacked lamellar structure.

[0137] Example 7

[0138] (1) Accurately weigh 0.66 g of sodium hydroxide (96 wt%), 0.70 g of cesium hydroxide aqueous solution (50 wt%), 0.50 g of aluminum hydroxide (78 wt%), and 2.54 g of deionized water, stir them evenly at room temperature, and place them statically at 120° C. for aging for 12 h;

[0139] (2) Add 7.51 g of silica sol (Ludox-HS-40) to the solution obtained in step (1) and stir again;

[0140] (3) Add 2.54 g of the structure directing agent Me-DABCO-Et(OH) prepared in Example 1 to the solution obtained in step (2) 2 The aqueous solution (15 wt%) was stirred at room temperature for 24 h to form a uniform solution; the obtained solution was transferred to a 25 mL hydrothermal kettle and subjected to static hydrothermal crystallization at 120 ° C for 336 h;

[0141] (4) The solid obtained in step (3) is centrifuged, washed, dried, and calcined to obtain SBT molecular sieve. The calcination conditions are 1°C·min -1 The heating rate was from room temperature to 550°C and calcined at this temperature for 8h.

[0142] The yield of the SBT molecular sieve obtained in Example 7 is 77%, and the Si / Al ratio is 6.8.

[0143] Fig.12 This is the X-ray diffraction pattern (XRD) of the SBT molecular sieve prepared in Example 7, which confirms the successful synthesis of SBT without impurities.

[0144] Fig.13 This is a scanning electron microscope (SEM) image of the SBT molecular sieve prepared in Example 7, and the morphology is a flaky structure.

[0145] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An asymmetric twin structure directing agent, characterized in that: It has the structure shown in formula I: In formula I, R1 and R2 are independently alkyl groups having 1 to 8 carbon atoms, and R1 and R2 are different from each other; X1 and X2 are independently halogen or both are hydroxide.

2. The asymmetric gemini structure directing agent according to claim 1, characterized in that: The R1 is ethyl, propyl, isopropyl, butyl, sec-butyl, isopentyl, cyclopentyl, methylcyclopentyl, cyclohexyl or methylcyclohexyl, and the R2 is methyl.

3. The method for preparing the asymmetric gemini structure directing agent according to claim 1 or 2, characterized in that: The following steps are involved: 1,4-diazabicyclo[2.2.2]octane, a first halogenated alkane and a first organic solvent are mixed to perform a first nucleophilic substitution reaction to obtain an intermediate product; the first halogenated alkane and the intermediate product have the structures shown in Formula II and Formula III respectively: R1-X1 formula Ⅱ, The intermediate product is mixed with a second halogenated alkane and a second organic solvent to carry out a second nucleophilic substitution reaction to obtain an asymmetric gemini-type structure directing agent having a structure shown in Formula I when X1 and X2 are independently halogens; the second halogenated alkane has a structure shown in Formula IV: R2-X2 Formula IV; The asymmetric gemini structure directing agent of the structure shown in formula I when X1 and X2 are independently halogens is subjected to ion exchange through a strong alkaline anion exchange resin to obtain an asymmetric gemini structure directing agent of the structure shown in formula I when X1 and X2 are both hydroxides.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the 1,4-diazabicyclo[2.2.2]octane to the first halogenated alkane is 1:1; and the molar ratio of the intermediate product to the second halogenated alkane is 1:1.

2.

5. Use of the asymmetric gemini structure directing agent according to claim 1 or 2 in the preparation of SBT molecular sieve or FAU-SBT-SBS symbiotic molecular sieve.

6. A method for preparing SBT molecular sieve, characterized in that: The following steps are involved: A structure directing agent, an aluminum source, an alkali source, a silicon source and water are mixed for hydrothermal crystallization to obtain a crystallized product; the alkali source is sodium hydroxide and cesium hydroxide, the structure directing agent is the asymmetric gemini structure directing agent according to claim 1, wherein R2 is methyl, and R1 is ethyl or propyl; the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the sodium hydroxide is calculated as Na2O, and the cesium hydroxide is calculated as Cs2O, and the molar ratio of the silicon source, the aluminum source, the sodium hydroxide, the cesium hydroxide, the structure directing agent and water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20); The crystallized product is calcined to obtain the SBT molecular sieve.

7. A method for preparing a FAU-SBT-SBS symbiotic molecular sieve, characterized in that: The following steps are involved: An aluminum source, an alkali source, water, a silicon source and a structure directing agent are mixed for hydrothermal crystallization to obtain a crystallized product; the alkali source is sodium hydroxide and cesium hydroxide, and the structure directing agent is the asymmetric gemini structure directing agent according to claim 1, wherein R2 is methyl, and R1 is isopropyl, butyl or sec-butyl; the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the sodium hydroxide is calculated as Na2O, and the cesium hydroxide is calculated as Cs2O, and the molar ratio of the silicon source, the aluminum source, sodium hydroxide, cesium hydroxide, the structure directing agent and water is 1:(0.05-0.15):(0.15-0.35):(0.015-0.045):(0.01-0.06):(8-20); The crystallized product is calcined to obtain a FAU-SBT-SBS intergrowth molecular sieve.

8. The preparation method according to claim 6 or 7, characterized in that: The aluminum source is one or more of aluminum sulfate, aluminum hydroxide, sodium aluminate and aluminum isopropoxide; the silicon source is one or more of sodium silicate, silica sol, white carbon black and ethyl orthosilicate.

9. The preparation method according to claim 6 or 7, characterized in that: The temperature of the hydrothermal crystallization is 120-150° C., and the time is 168-336 hours.

10. The preparation method according to claim 6 or 7, characterized in that: The silicon-aluminum molar ratio of the SBT molecular sieve or the FAU-SBT-SBS intergrowth molecular sieve is 3-8.

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