Aluminum-rich ZSM-5 molecular sieve as well as preparation method and application thereof
By using a dual-cation system of a first alkali source containing alkali metal and other alkali sources, aluminum-rich ZSM-5 molecular sieves were prepared, solving the problems of high silicon-to-aluminum ratio and environmental protection, and realizing low-cost and environmentally friendly molecular sieve preparation.
Patent Information
- Application Number
- CN202410960566.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-17
- Publication Date
- 2026-01-20
AI Technical Summary
In existing technologies, ZSM-5 molecular sieves have a high silica-to-alumina ratio and the preparation process is not environmentally friendly. The use of organic template agents leads to high costs and the generation of harmful substances.
Aluminum-rich ZSM-5 molecular sieves were prepared by using a dual-cationic system with an alkali metal-containing primary alkali source and other alkali sources, through mixing and gelling followed by crystallization. This reduced or eliminated the use of organic template agents and promoted the entry of Al atoms into the molecular sieve framework.
The preparation of ZSM-5 molecular sieves with low silicon-to-aluminum ratio has been achieved, simplifying the process, reducing costs, decreasing harmful gas emissions, and protecting the environment.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of molecular sieve preparation, and more particularly to an aluminum-rich ZSM-5 molecular sieve, a preparation method and application thereof. BACKGROUND
[0002] ZSM-5 molecular sieve is generally synthesized by using an organic template agent. In the synthesis process of the ZSM-5 molecular sieve, the organic template agent first interacts with Si atoms in the synthesis system, and the Si atoms form a silicon-rich ZSM-5 molecular sieve under the guidance of the organic template agent; and according to the lowenstein rule, Al atoms in the molecular sieve framework must be connected to Si atoms through an oxygen bridge, and when the Si atoms in the raw material are consumed, the Al atoms cannot continue to enter the molecular sieve framework, and the uncrystallized aluminum source exists in the crystallization product in the form of amorphous aluminum or is lost with the mother liquor. Therefore, the silicon-aluminum ratio of the ZSM-5 molecular sieve prepared by using the organic template agent is generally high.
[0003] In addition, the organic template agent is expensive, and a large amount of toxic and harmful substances are generated in the use process. Therefore, how to reduce the use of the organic template agent and synthesize a molecular sieve with a low silicon-aluminum ratio through a more green approach is a popular direction of molecular sieve research. SUMMARY
[0004] The present application aims to provide an aluminum-rich ZSM-5 molecular sieve, a preparation method and application thereof, so as to solve the technical problems of high silicon-aluminum ratio and non-green and environmental protection in the preparation of the ZSM-5 molecular sieve by using the organic template agent in the prior art.
[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:
[0006] In a first aspect, the present application provides a preparation method of an aluminum-rich ZSM-5 molecular sieve, comprising: mixing raw materials including an aluminum source, a silicon source, a first alkali source and water to form a gel; obtaining a mixed solution including the gel, a second alkali source, ZSM-5 seeds and an optional organic template agent; and performing crystallization treatment on the mixed solution to obtain the aluminum-rich ZSM-5 molecular sieve.
[0007] The first alkali source includes an alkali metal-containing alkali source.
[0008] The second alkali source includes at least one of an alkali earth metal-containing alkali source, a group VIII metal-containing alkali source, a group IB metal-containing alkali source and a group IIB metal-containing alkali source.
[0009] The preparation method of the ZSM-5 molecular sieve provided by the present application is to first form a gel by using the silicon source, the aluminum source and the first alkali source containing the alkali metal, and then add the second alkali source and other raw materials. The alkali metal cations, such as Na + , K+ , compared with the organic cation charge density is higher, can promote the Al atom into the molecular sieve framework, can better meet the [AlO4] - The demand for compensation cations. Alkaline earth metal ions, Group VIII metal ions, Group IB metal ions, Group IIB metal ions have higher charge density, but the guiding ability is weak in the process of molecular sieve crystallization. The present application adopts a double-cation system including a first alkali source (containing alkali metal) and a second alkali source (containing alkaline earth metal, Group VIII metal, Group IB metal, Group IIB metal), without using organic template or using a small amount of organic template, can synthesize aluminum-rich ZSM-5 molecular sieve.
[0010] And, since the preparation process of the aluminum-rich ZSM-5 molecular sieve does not need to add an organic template or only adds a small amount of template, the calcination process can be omitted, not only avoiding the harmful gases such as nitrogen oxides generated in the process of calcination to remove the organic template, but also avoiding the damage to the molecular sieve framework caused by the heat and water vapor generated in the high-temperature calcination process.
[0011] According to some embodiments of the present application, the first alkali source includes at least one of alkali metal hydroxide, alkali metal carbonate, alkali metal bicarbonate, alkali metal fluoride.
[0012] According to some embodiments of the present application, the first alkali source includes at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, cesium carbonate, lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride.
[0013] According to some embodiments of the present application, the second alkali source contains at least one of Mg, Ca, Ba, Fe, Cu, Zn.
[0014] According to some embodiments of the present application, the second alkali source includes at least one of alkaline earth metal hydroxide, Group VIII metal hydroxide, Group IB metal hydroxide, Group IIB metal hydroxide.
[0015] According to some embodiments of the present application, the second alkali source includes at least one of magnesium hydroxide, calcium hydroxide, barium hydroxide, iron hydroxide, ferrous hydroxide, copper hydroxide, zinc hydroxide.
[0016] According to some embodiments of the present application, the aluminum source includes at least one of aluminum sol, aluminum hydroxide, aluminum isopropyl alcohol, aluminum sec-butyl alcohol, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum oxide.
[0017] According to some embodiments of the present application, the silicon source comprises at least one of silicon powder, silicon ball, silica gel, silica sol, sodium silicate, silica-alumina gel, amorphous silica powder, methyl silicate, ethyl silicate, propyl silicate, silicon tetrachloride, silane, white carbon black, and diatomite.
[0018] According to some embodiments of the present application, the organic template comprises at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, and tetrabutylammonium bromide.
[0019] According to some embodiments of the present application, the molar ratio of each raw material is: SiO2 / Al2O3 = 10-30, M1 / SiO2 = 0.001-0.5, M2 / SiO2 = 0.0005-0.5, OSDA / M1 = 0-0.01, and H2O / SiO2 = 5-70, wherein SiO2 is calculated based on the silicon source, Al2O3 is calculated based on the aluminum source, M1 is calculated based on the first alkali source, M2 is calculated based on the second alkali source, and OSDA is calculated based on the organic template.
[0020] In the present application, when calculating the molar ratio of each raw material, only SiO2 in the silicon source is included, and SiO2 in the ZSM-5 seed is not included; similarly, when calculating the molar ratio of each raw material, only Al2O3 in the aluminum source is included, and Al2O3 in the ZSM-5 seed is not included.
[0021] According to some embodiments of the present application, SiO2 / Al2O3 = 10-25.
[0022] According to some embodiments of the present application, M1 / SiO2 = 0.03-0.3.
[0023] According to some embodiments of the present application, M2 / SiO2 = 0.001-0.1.
[0024] According to some embodiments of the present application, M2 / SiO2 = 0.002-0.05.
[0025] According to some embodiments of the present application, H2O / SiO2 = 25-60.
[0026] According to some embodiments of the present application, the ZSM-5 seed is selected from non-Na type ZSM-5 molecular sieve. For example, NH4 + type ZSM-5 molecular sieve and H + type ZSM-5 molecular sieve. Na contained in the Na type molecular sieve can affect the control of the metal ratio in the mixed solution, thereby causing the prepared molecular sieve to have a mixed crystal.
[0027] According to some embodiments of the present application, the SiO2 / Al2O3 of the ZSM-5 seeds is 30-∞.
[0028] According to some embodiments of the present application, the SiO2 / Al2O3 of the ZSM-5 seeds is 40-500, for example, 40, 45, 50, 55, 70, 90, 100, 125, 150, 175, 200, 300, 400, 500, etc.
[0029] According to some embodiments of the present application, the mass of the ZSM-5 seeds accounts for 0.05-10% of the mass of the silicon source in the mixed solution, for example, 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 0.7%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.
[0030] According to some embodiments of the present application, the mass of the ZSM-5 seeds accounts for 1-9% of the mass of the silicon source in the mixed solution.
[0031] According to some embodiments of the present application, the process of forming the gel comprises: dissolving the aluminum source in water, adding the silicon source dropwise under stirring; stirring for 2-24h, adding the first alkali source aqueous solution to obtain the gel.
[0032] According to some embodiments of the present application, the temperature of the crystallization treatment is 100-200℃, preferably 120-180℃; the time of the crystallization treatment is 2-200h, preferably 48-150h.
[0033] According to some embodiments of the present application, the stirring speed of the crystallization treatment is 0-6000rpm.
[0034] According to some embodiments of the present application, the product of the crystallization treatment is subjected to cooling, filtration, washing, and drying treatment to obtain the aluminum-rich ZSM-5 molecular sieve.
[0035] According to some embodiments of the present application, the drying temperature is 30-200℃, preferably 80-150℃; the drying time is 3-36h, preferably 5-24h.
[0036] In the second aspect, the present application provides an aluminum-rich ZSM-5 molecular sieve prepared by the preparation method of the first aspect.
[0037] According to some embodiments of the present application, the SiO2 / Al2O3 of the aluminum-rich ZSM-5 molecular sieve is <20.
[0038] According to some embodiments of the present application, the crystallinity of the aluminum-rich ZSM-5 molecular sieve is ≥75%, preferably ≥80%.
[0039] According to some embodiments of the present application, the content of the second alkali source metal oxide in the aluminum-rich ZSM-5 molecular sieve is <0.05wt%, preferably <0.02wt%, more preferably <0.01wt%.
[0040] In the present application, the metal cations in the second alkali source can play a role in promoting Al atoms to enter the molecular sieve framework during the crystallization of the molecular sieve, and only a small amount of the metal cations in the second alkali source will enter or remain in the molecular sieve framework, and the influence on the physicochemical properties of the molecular sieve itself is minimal.
[0041] In a third aspect, the present application provides the use of the aluminum-rich ZSM-5 molecular sieve of the second aspect in the field of catalysts.
[0042] The present application has at least the following beneficial effects:
[0043] The present application can synthesize the aluminum-rich ZSM-5 molecular sieve under the condition of not using or less using organic template by adopting the double metal cation system including the first alkali source and the second alkali source, the preparation method is simple and easy to operate, and is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS
[0044] Figure 1 XRD diffraction pattern of the ZSM-5 molecular sieve prepared for the present embodiment 1. DETAILED DESCRIPTION
[0045] In order to make the technical problems to be solved by the present application, the technical solutions and beneficial effects more clear, the present application will be further described in detail in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present patent, and do not limit the protection scope of the present application in any way.
[0046] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as generally understood by those skilled in the art to which the present application belongs. The reagents used in the following embodiments, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following embodiments, unless otherwise specified, can be purchased on the market or obtained by existing methods; the reagent amount, unless otherwise specified, is the reagent amount in conventional experimental operation; the experimental method, unless otherwise specified, is a conventional method.
[0047] In each embodiment and comparative example of the present application, each performance data is tested according to the following test method:
[0048] (1) XRD phase analysis: measured by using a D8 Focus diffractometer of Bruker Company, graphite monochromator, Cu target Kα ray light source, wavelength λ of 0.154 nm, 40 kV tube voltage, 40 mA tube current, and recording diffraction signals in a 2θ range of 3-90° (2° / min scanning speed). The relative crystallinity of the molecular sieve can be calculated according to the XRD test results.
[0049] (2) Element content of the molecular sieve: obtained by using a Perkin Elmer Optima 3300DV inductively coupled plasma emission spectrometer (ICP).
[0050] Example 1
[0051] The aluminum sol was dissolved in water, and the silica sol was added dropwise under stirring; after stirring for 4 h, a 10 wt% sodium hydroxide solution was added dropwise to obtain a gel. Magnesium hydroxide and hydrogen-type ZSM-5 seeds (SiO2 / Al2O3= 50) were added to the gel to obtain a mixture, the mass of the ZSM-5 seeds was 8 wt% of the mass of the silica sol calculated based on SiO2, and the molar ratio of the components in the mixture (excluding the hydrogen-type ZSM-5 seeds) was SiO2: 0.063 Al2O3: 0.1 NaOH: 0.005 Mg(OH)2: 50 H2O. The mixture was loaded into a polytetrafluoroethylene-lined pressure steel kettle, and crystallization was performed at 150°C for 5 days. After the crystallization was completed, the crystallization product was naturally cooled to room temperature, filtered, washed, dried at 120°C for 12 h, and calcined to obtain the product.
[0052] The XRD pattern of the product of this example is shown in Figure 1 It can be seen that it is a ZSM-5 molecular sieve.
[0053] The SiO2 / Al2O3of the product of this example was 17.0, the crystallinity was 85.5%, and the MgO content in the product was 0.005 wt% obtained by ICP testing.
[0054] Example 2
[0055] Dissolve sodium aluminate in water, and drop in methyl silicate under stirring; after stirring for 4 h, drop in 10 wt% sodium hydroxide solution to obtain a gel. Add magnesium hydroxide and hydrogen type ZSM-5 seed crystal (SiO2 / Al2O3=300) to the gel to obtain a mixture, the mass of the ZSM-5 seed crystal is 4 wt% of the mass of the silica sol calculated as SiO2, and the molar ratio of the components in the mixture (excluding the hydrogen type ZSM-5 seed crystal) is SiO2:0.05Al2O3:0.25NaOH:0.01Mg(OH)2:30H2O. Put the mixture into a polytetrafluoroethylene-lined pressure steel autoclave, and crystallize at 170°C for 3 days. After the crystallization is completed, cool naturally to room temperature, filter, wash, and dry at 90°C for 24 h, without calcination, to obtain a product, which is ZSM-5 molecular sieve, SiO2 / Al2O3=18.8, and the crystallinity is 89.6%, and the MgO content in the product is 0.008 wt% as tested by ICP.
[0056] Example 3
[0057] The molecular sieve is prepared according to the method of Example 1, except that the molar ratio of the components in the mixture (excluding the hydrogen type ZSM-5 seed crystal) is SiO2:0.063Al2O3:0.05NaOH:0.015Mg(OH)2:50H2O.
[0058] The obtained product is ZSM-5 molecular sieve, SiO2 / Al2O3=16.0, the crystallinity is 81.2%, and the MgO content in the product is 0.009 wt% as tested by ICP.
[0059] Example 4
[0060] The molecular sieve is prepared according to the method of Example 1, except that equal molar amount of KOH is used instead of NaOH.
[0061] The obtained product is ZSM-5 molecular sieve, SiO2 / Al2O3=15.4, the crystallinity is 75.7%, and the MgO content in the product is 0.004 wt% as tested by ICP.
[0062] Example 5
[0063] The molecular sieve is prepared according to the method of Example 1, except that equal molar amount of Ca(OH)2 is used instead of Mg(OH)2.
[0064] The obtained product is ZSM-5 molecular sieve, SiO2 / Al2O3=17.8, the crystallinity is 84.5%, and the CaO content in the product is 0.006 wt% as tested by ICP.
[0065] Example 6
[0066] The molecular sieve was prepared according to the method of Example 1, except that equal molar amounts of Fe(OH)2were used instead of Mg(OH)2.
[0067] The product obtained was ZSM-5 molecular sieve with SiO2 / Al2O3= 16.8 and a crystallinity of 79.2%, and the FeO content in the product was 0.007 wt% as determined by ICP.
[0068] Example 7
[0069] The molecular sieve was prepared according to the method of Example 1, except that equal molar amounts of Cu(OH)2were used instead of Mg(OH)2.
[0070] The product obtained was ZSM-5 molecular sieve with SiO2 / Al2O3= 19 and a crystallinity of 87.6%, and the CuO content in the product was 0.006 wt% as determined by ICP.
[0071] Example 8
[0072] The molecular sieve was prepared according to the method of Example 1, except that equal molar amounts of Zn(OH)2were used instead of Mg(OH)2.
[0073] The product obtained was ZSM-5 molecular sieve with SiO2 / Al2O3= 18.3 and a crystallinity of 88.5%, and the ZnO content in the product was 0.009 wt% as determined by ICP.
[0074] Example 9
[0075] The molecular sieve was prepared according to the method of Example 1, except that the mixture solution further included tetrapropylammonium hydroxide (OSDA), and the molar ratio of the components in the mixture solution (excluding the hydrogen-type ZSM-5 seed crystal) was SiO2: 0.063 Al2O3: 0.1 NaOH: 0.005 Mg(OH)2: 0.0001 OSDA: 50 H2O.
[0076] The product obtained was ZSM-5 molecular sieve with SiO2 / Al2O3= 18.4 and a crystallinity of 86.2%, and the MgO content in the product was 0.002 wt% as determined by ICP.
[0077] Example 10
[0078] The molecular sieve was prepared according to the method of Example 1, except that the molar ratio of the components in the mixture solution (excluding the hydrogen-type ZSM-5 seed crystal) was SiO2: 0.063 Al2O3: 0.1 NaOH: 0.5 Mg(OH)2: 50 H2O.
[0079] The obtained product was ZSM-5 molecular sieve with SiO2 / Al2O3= 15.6 and crystallinity of 75.4%, and the MgO content in the product was 0.012wt% as determined by ICP.
[0080] Comparative Example 1
[0081] The molecular sieve was prepared according to Example 1, except that Mg(OH)2was not added to the mixed solution.
[0082] The obtained product was ZSM-5 molecular sieve with SiO2 / Al2O3= 31.6 and crystallinity of 52.8%.
[0083] Comparative Example 2
[0084] The molecular sieve was prepared according to Example 1, except that Mg(OH)2was not added to the mixed solution, but tetrapropylammonium hydroxide was added, and the molar ratio of the components (excluding the hydrogen-type ZSM-5 seed crystal) in the mixed solution was SiO2: 0.063Al2O3: 0.1NaOH: 0.01OSDA: 50H2O.
[0085] The obtained product was ZSM-5 molecular sieve with SiO2 / Al2O3= 32.4 and crystallinity of 87.7%.
[0086] Comparative Example 3
[0087] The molecular sieve was prepared according to Example 1, except that NaOH was not added.
[0088] The specific preparation steps included:
[0089] The aluminum sol was dissolved in water, and the silica sol was added dropwise under stirring; after stirring for 4h, magnesium hydroxide and hydrogen-type ZSM-5 seed crystal (SiO2 / Al2O3= 50) were added to obtain a mixed solution, and the mass of the ZSM-5 seed crystal was 8wt% of the mass of the silica sol calculated based on SiO2, and the molar ratio of the components (excluding the hydrogen-type ZSM-5 seed crystal) in the mixed solution was SiO2: 0.063Al2O3: 0.005Mg(OH)2: 50H2O. The mixed solution was placed in a polytetrafluoroethylene-lined pressure steel kettle, and crystallization was carried out at 150°C for 5 days. After the crystallization was completed, natural cooling was carried out to room temperature, and the crystallization product was filtered, washed, and dried at 120°C for 12h, without calcination, to obtain the product.
[0090] The obtained product was amorphous substance.
[0091] Comparative Example 4
[0092] The aluminum sol was dissolved in water, and the silica sol was added dropwise under stirring; after stirring for 4 h, a mixed solution of sodium hydroxide and magnesium hydroxide (the total concentration of sodium hydroxide and magnesium hydroxide was 10 wt%) was added to obtain a first mixed solution, the molar ratio of the components in the first mixed solution was SiO2:0.063Al2O3:0.1NaOH:0.005Mg(OH)2:50H2O. ZSM-5 seeds (SiO2 / Al2O3=50) were added to the first mixed solution to obtain a second mixed solution, the mass of the ZSM-5 seeds was 8 wt% of the mass of the silica sol calculated based on SiO2. The second mixed solution was loaded into a polytetrafluoroethylene-lined pressure steel kettle, and crystallization was performed at 150°C for 5 days. After the crystallization was completed, the crystallization product was naturally cooled to room temperature, filtered, washed, and dried at 120°C for 12 h, and the product was obtained without calcination.
[0093] The obtained product was ZSM-5 molecular sieve, SiO2 / Al2O3=28.3, the crystallinity was 88.1%, and the MgO content in the product was 0.007 wt% as determined by ICP
[0094] It should be noted that the above-described examples are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified as specified within the scope of the claims of the present application, and the present application can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials, and examples, it does not mean that the present application is limited to the specific examples disclosed therein, but rather, the present application can be extended to all other methods and applications having the same function.
Claims
1. A process for the preparation of an aluminum-rich ZSM-5 molecular sieve, characterized by, The application relates to a method for preparing an aluminum-rich ZSM-5 molecular sieve. The raw materials including an aluminum source, a silicon source, a first alkali source and water are mixed to form a gel; a mixed solution including the gel, a second alkali source, ZSM-5 seeds and an optional organic template agent is obtained; and the mixed solution is subjected to a crystallization treatment to obtain the aluminum-rich ZSM-5 molecular sieve. The first alkali source includes an alkali metal-containing alkali source. The second alkali source includes at least one of an alkali earth metal-containing alkali source, a group VIII metal-containing alkali source, a group IB metal-containing alkali source and a group IIB metal-containing alkali source.
2. The production method according to claim 1, characterized by, The first alkali source includes at least one of alkali metal hydroxide, alkali metal carbonate, alkali metal bicarbonate and alkali metal fluoride. The second alkali source includes at least one of alkali earth metal hydroxide, group VIII metal hydroxide, group IB metal hydroxide and group IIB metal hydroxide.
3. The production method according to claim 1 or 2, characterized by, The first alkali source includes at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, cesium carbonate, lithium fluoride, sodium fluoride, potassium fluoride and cesium fluoride. The second alkali source includes at least one of magnesium hydroxide, calcium hydroxide, barium hydroxide, iron hydroxide, ferrous hydroxide, copper hydroxide and zinc hydroxide.
4. The production method according to any one of claims 1 to 3, characterized by, The aluminum source includes at least one of aluminum sol, aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride and aluminum oxide. The silicon source includes at least one of silicon powder, silicon ball, silica gel, silica sol, sodium silicate, silica-alumina gel, amorphous silica powder, methyl silicate, ethyl silicate, propyl silicate, silicon tetrachloride, silane, white carbon black and diatomite. The organic template agent includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide and tetrabutylammonium bromide.
5. The method of any one of claims 1-4, wherein, The molar ratio of each raw material is as follows: SiO2 / Al2O3=10-30, M1 / SiO2=0.001-0.5, M2 / SiO2=0.0005-0.5, OSDA / M1=0-0.01 and H2O / SiO2=5-70, wherein SiO2 is the silicon source, Al2O3 is the aluminum source, M1 is the first alkali source, M2 is the second alkali source and OSDA is the organic template agent. Preferably, M1 / SiO2=0.03-0.3 and / or M2 / SiO2=0.001-0.1, preferably 0.002-0.
05.
6. The method of any one of claims 1-5, wherein, The ZSM-5 seeds are selected from non-Na type ZSM-5 molecular sieves. The SiO2 / Al2O3 of the ZSM-5 seeds is 30-infinity, preferably 40-500. The mass of the ZSM-5 seeds accounts for 0.05-10% of the mass of the silicon source in the mixed solution, preferably 1-9%.
7. The method of any one of claims 1-6, wherein, The temperature of the crystallization treatment is 100-200 DEG C, preferably 120-180 DEG C, and the time of the crystallization treatment is 2-200 h, preferably 48-150 h.
8. The method of any one of claims 1-7, wherein, The product of the crystallization treatment is subjected to cooling, filtration, washing, and drying treatment to obtain the aluminum-rich ZSM-5 molecular sieve. Preferably, the drying temperature is 30-200°C, preferably 80-150°C. 9.An aluminum-rich ZSM-5 molecular sieve prepared by the method of any one of claims 1-8. Preferably, The SiO2 / Al2O3 of the aluminum-rich ZSM-5 molecular sieve is less than 20. Preferably, the crystallinity of the aluminum-rich ZSM-5 molecular sieve is greater than or equal to 75%, preferably greater than or equal to 80%. Preferably, the content of the second alkali source metal oxide in the aluminum-rich ZSM-5 molecular sieve is less than 0.05wt%, preferably less than 0.02wt%, more preferably less than 0.01wt%. 10.Use of the aluminum-rich ZSM-5 molecular sieve of claim 9 in the field of catalysts.