Aluminum-rich zsm-5 molecular sieve, method for preparing same, and use thereof

Abstract

The present application relates to the technical field of molecular sieve preparation, and provides an aluminum-rich ZSM-5 molecular sieve, a preparation method and application thereof.The preparation method of the aluminum-rich ZSM-5 molecular sieve comprises the following steps: 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; and performing crystallization treatment on the mixed solution to obtain the aluminum-rich ZSM-5 molecular sieve; the first alkali source includes an alkali source containing alkali metals; and the second alkali source includes at least one of an alkali source containing alkaline earth metals, an alkali source containing metals of group VIII, an alkali source containing metals of group IB and an alkali source containing metals of group IIB.By adopting a bimetallic cation system including the first alkali source and the second alkali source, the aluminum-rich ZSM-5 molecular sieve can be synthesized without or with less use of an organic template, the preparation method is simple and easy to operate, and is green and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation technology, and more specifically, to an aluminum-rich ZSM-5 molecular sieve, its preparation method, and its application. Background Technology

[0002] ZSM-5 molecular sieves typically require the use of organic templates for synthesis. During the synthesis of ZSM-5 molecular sieves, the organic template first interacts with Si atoms in the synthesis system. Under the guidance of the organic template, Si forms a silicon-rich ZSM-5 molecular sieve. According to Lowenstein's rule, Al atoms in the molecular sieve framework must be connected to Si atoms through oxygen bridges. Once the Si atoms in the raw material are depleted, Al atoms can no longer enter the molecular sieve framework, and the uncrystallized aluminum source exists as amorphous aluminum in the crystallized product or is lost with the mother liquor. Therefore, ZSM-5 molecular sieves prepared using organic templates generally have a higher Si / Al ratio.

[0003] Furthermore, organic template agents are expensive and generate large amounts of toxic and harmful substances during use. Therefore, reducing the use of organic template agents and synthesizing molecular sieves with low silica-to-alumina ratios through greener methods is a hot research direction in molecular sieve research. Summary of the Invention

[0004] The purpose of this invention is to provide an aluminum-rich ZSM-5 molecular sieve, its preparation method, and its application, so as to solve the technical problems of high silicon-aluminum ratio and lack of green and environmental protection in the preparation of ZSM-5 molecular sieves using organic template agents in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing 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 mixture including the gel, a second alkali source, ZSM-5 seed crystals and an optional organic template agent; and crystallizing the mixture to obtain the aluminum-rich ZSM-5 molecular sieve.

[0007] The first alkali source includes an alkali source containing an alkali metal;

[0008] The second alkali source includes at least one of the following: an alkali source containing an alkaline earth metal, an alkali source containing a group VIII metal, an alkali source containing a group IB metal, and an alkali source containing a group IIB metal.

[0009] The ZSM-5 molecular sieve preparation method provided by this invention involves first forming a gel from a silicon source, an aluminum source, and a first alkali source containing an alkali metal, and then adding a second alkali source and other raw materials. The alkali metal cation, such as Na... + K+ Compared to organic cations, it has a higher charge density, which can promote the entry of Al atoms into the molecular sieve framework and better meet the requirements of [AlO4] in the aluminum-rich molecular sieve framework. - The need for compensating cations. Alkaline earth metal ions, Group VIII metal ions, Group IB metal ions, and Group IIB metal ions have higher charge densities, but their guiding ability is weaker during molecular sieve crystallization. This invention employs a dual-cation system including a first alkali source (containing an alkali metal) and a second alkali source (containing an alkaline earth metal, Group VIII metal, Group IB metal, or Group IIB metal), which can synthesize aluminum-rich ZSM-5 molecular sieves without the need for organic template agents or with only a very small amount of organic template agents.

[0010] Furthermore, since the preparation process of aluminum-rich ZSM-5 molecular sieves does not require the addition of organic template agents or only requires the addition of a very small amount of template agent, the calcination process can be omitted. This not only avoids harmful gases such as nitrogen oxides generated during the calcination process to remove organic template agents, but also avoids the damage to the molecular sieve framework caused by the heat and water vapor generated during the high-temperature calcination process.

[0011] According to some embodiments of the present invention, the first alkali source includes at least one of alkali metal hydroxide, alkali metal carbonate, alkali metal bicarbonate, and alkali metal fluoride.

[0012] According to some embodiments of the present invention, 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.

[0013] According to some embodiments of the present invention, the second alkali source contains at least one of Mg, Ca, Ba, Fe, Cu, and Zn.

[0014] According to some embodiments of the present invention, the second alkali source includes at least one of alkaline earth metal hydroxide, group VIII metal hydroxide, group IB metal hydroxide, and group IIB metal hydroxide.

[0015] According to some embodiments of the present invention, the second alkali source includes at least one selected from magnesium hydroxide, calcium hydroxide, barium hydroxide, iron hydroxide, ferrous hydroxide, copper hydroxide, and zinc hydroxide.

[0016] According to some embodiments of the present invention, the aluminum source includes at least one selected from aluminum sol, aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, and aluminum oxide.

[0017] According to some embodiments of the present invention, the silicon source includes at least one of silicon powder, silicon balls, silica gel, silica sol, sodium silicate, aluminosilicate, amorphous silica powder, methyl silicate, ethyl silicate, propyl silicate, silicon tetrachloride, silane, silica, and diatomaceous earth.

[0018] According to some embodiments of the present invention, 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.

[0019] According to some embodiments of the present invention, the silicon source is SiO2, the aluminum source is Al2O3, the first alkali source is M1, the second alkali source is M2, the organic template agent is OSDA, and 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, H2O / SiO2 = 5~70.

[0020] In this invention, when calculating the molar ratio of each raw material, only SiO2 in the silicon source is included, excluding SiO2 in the ZSM-5 seed crystal; similarly, when calculating the molar ratio of each raw material, only Al2O3 in the aluminum source is included, excluding Al2O3 in the ZSM-5 seed crystal.

[0021] According to some embodiments of the present invention, SiO2 / Al2O3 = 10 to 25.

[0022] According to some embodiments of the present invention, M1 / SiO2 = 0.03 to 0.3.

[0023] According to some embodiments of the present invention, M2 / SiO2 = 0.001 to 0.1.

[0024] According to some embodiments of the present invention, M2 / SiO2 = 0.002 to 0.05.

[0025] According to some embodiments of the present invention, H2O / SiO2 = 25 to 60.

[0026] According to some embodiments of the present invention, the ZSM-5 seed crystals are selected from non-Na-type ZSM-5 molecular sieves. For example, NH4 can be selected. + ZSM-5 molecular sieve and H + Type ZSM-5 molecular sieve. The Na contained in Na-type molecular sieves can affect the control of the metal ratio in the mixed solution, which can lead to the appearance of impurities in the prepared molecular sieve.

[0027] According to some embodiments of the present invention, the SiO2 / Al2O3 ratio of the ZSM-5 seed crystal is 30 to ∞.

[0028] According to some embodiments of the present invention, the SiO2 / Al2O3 ratio of the ZSM-5 seed crystal is 40 to 500, for example, it can be 40, 45, 50, 55, 70, 90, 100, 125, 150, 175, 200, 300, 400, 500, etc.

[0029] According to some embodiments of the present invention, the mass of the ZSM-5 seed crystal accounts for 0.05 to 10% of the mass of the silicon source in the mixed solution, calculated as SiO2, for example, it can be 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 invention, the mass of the ZSM-5 seed crystal accounts for 1 to 9% of the mass of the silicon source in the mixed solution, calculated as SiO2.

[0031] According to some embodiments of the present invention, the gel formation process includes: dissolving an aluminum source in water, adding a silicon source dropwise while stirring; stirring for 2 to 24 hours, and adding an aqueous solution of a first alkali source dropwise to obtain a gel.

[0032] According to some embodiments of the present invention, the temperature of the crystallization treatment is 100-200°C, preferably 120-180°C; the time of the crystallization treatment is 2-200 hours, preferably 48-150 hours.

[0033] According to some embodiments of the present invention, the stirring speed of the crystallization treatment is 0 to 6000 rpm.

[0034] According to some embodiments of the present invention, the crystallized product is cooled, filtered, washed, and dried to obtain the alumina-rich ZSM-5 molecular sieve.

[0035] According to some embodiments of the present invention, the drying temperature is 30-200°C, preferably 80-150°C; the drying time is 3-36 hours, preferably 5-24 hours.

[0036] Secondly, the present invention provides an aluminum-rich ZSM-5 molecular sieve, which is prepared by the preparation method described in the first aspect.

[0037] According to some embodiments of the present invention, the SiO2 / Al2O3 ratio of the aluminum-rich ZSM-5 molecular sieve is <20.

[0038] According to some embodiments of the present invention, the crystallinity of the alumina-rich ZSM-5 molecular sieve is ≥75%, preferably ≥80%.

[0039] According to some embodiments of the present invention, the content of the second alkali source metal oxide in the alumina-rich ZSM-5 molecular sieve is <0.05wt%, preferably <0.02wt%, and more preferably <0.01wt%.

[0040] In this invention, the metal cations in the second alkali source can promote the entry of Al atoms into the molecular sieve framework during the molecular sieve crystallization process, and only a very small amount of metal cations in the second alkali source will enter or remain in the molecular sieve framework, so the impact on the physicochemical properties of the molecular sieve itself is minimal.

[0041] Thirdly, the present invention provides the application of the aluminum-rich ZSM-5 molecular sieve described in the second aspect in the field of catalysts.

[0042] The beneficial effects of this invention are at least as follows:

[0043] This invention utilizes a bimetallic cation system comprising a first alkali source and a second alkali source to synthesize aluminum-rich ZSM-5 molecular sieves with little or no use of organic template agents. The preparation method is simple, easy to operate, and environmentally friendly. Attached Figure Description

[0044] Figure 1 The XRD diffraction pattern of the ZSM-5 molecular sieve prepared in Example 1 is shown. Detailed Implementation

[0045] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0046] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in conventional experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0047] In the various embodiments and comparative examples of the present invention, the performance data were tested according to the following test methods:

[0048] (1) XRD phase analysis: The phases were determined using a Bruker D8 Focus diffractometer with a graphite monochromator, a Cu target Kα light source, a wavelength λ of 0.154 nm, a tube voltage of 40 kV, and a tube current of 40 mA. The diffraction signal was recorded in the 2θ range of 3-90° (scanning speed of 2° / min). The relative crystallinity of the molecular sieve can be calculated based on the XRD test results.

[0049] (2) Element content of molecular sieve: The content was obtained by measuring the element content using a Perkin Elmer Optima 3300DV inductively coupled plasma atomic emission spectrometer (ICP).

[0050] Example 1

[0051] Aluminum sol was dissolved in water, and silica sol was added dropwise while stirring. After stirring for 4 hours, a 10 wt% sodium hydroxide solution was added dropwise to obtain a gel. Magnesium hydroxide and hydrogen-form ZSM-5 seed crystals (SiO2 / Al2O3 = 50) were added to the gel to obtain a mixed solution. The mass of the ZSM-5 seed crystals was 8 wt% of the mass of the silica sol based on SiO2. The molar ratio of the components in the mixed solution (excluding hydrogen-form ZSM-5 seed crystals) was SiO2:0.063Al2O3:0.1NaOH:0.005Mg(OH)2:50H2O. The mixed solution was placed in a polytetrafluoroethylene-lined pressure vessel and crystallized at 150℃ for 5 days. After crystallization, the mixture was naturally cooled to room temperature. The crystallized product was filtered, washed, and dried at 120℃ for 12 hours without calcination to obtain the final product.

[0052] The XRD pattern of the product in this embodiment is as follows: Figure 1 As shown, it can be seen that it is a ZSM-5 molecular sieve.

[0053] The product of this embodiment has a SiO2 / Al2O3 ratio of 17.0, a crystallinity of 85.5%, and an MgO content of 0.005 wt% as determined by ICP testing.

[0054] Example 2

[0055] Sodium aluminate was dissolved in water, and methyl silicate was added dropwise while stirring. After stirring for 4 hours, a 10 wt% sodium hydroxide solution was added dropwise to obtain a gel. Magnesium hydroxide and hydrogen-form ZSM-5 seed crystals (SiO2 / Al2O3 = 300) were added to the gel to obtain a mixed solution. The mass of the ZSM-5 seed crystals was 4 wt% of the mass of the silica sol based on SiO2. The molar ratio of the components in the mixed solution (excluding the hydrogen-form ZSM-5 seed crystals) was SiO2:0.05Al2O3:0.25NaOH:0.01Mg(OH)2:30H2O. The mixed solution was placed in a polytetrafluoroethylene-lined pressure vessel and crystallized at 170°C for 3 days. After crystallization, the product was naturally cooled to room temperature, filtered, washed, and dried at 90°C for 24 hours without calcination. The resulting product was ZSM-5 molecular sieve with a SiO2 / Al2O3 ratio of 18.8 and a crystallinity of 89.6%. ICP analysis showed that the MgO content in the product was 0.008 wt%.

[0056] Example 3

[0057] The molecular sieve preparation method is the same as in Example 1, except that the molar ratio of each component (excluding hydrogen-type ZSM-5 seed crystals) in the mixture is SiO2:0.063Al2O3:0.05NaOH:0.015Mg(OH)2:50H2O.

[0058] The obtained product is ZSM-5 molecular sieve with SiO2 / Al2O3 = 16.0 and crystallinity of 81.2%. The MgO content in the product was found to be 0.009 wt% by ICP analysis.

[0059] Example 4

[0060] The molecular sieve preparation method is the same as in Example 1, except that an equimolar amount of KOH is used instead of NaOH.

[0061] The obtained product is ZSM-5 molecular sieve, with SiO2 / Al2O3 = 15.4 and crystallinity of 75.7%. ICP analysis showed that the MgO content in the product was 0.004 wt%.

[0062] Example 5

[0063] The molecular sieve preparation method is the same as in Example 1, except that an equimolar amount of Ca(OH)2 is used instead of Mg(OH)2.

[0064] The obtained product is ZSM-5 molecular sieve with SiO2 / Al2O3 = 17.8 and crystallinity of 84.5%. ICP analysis showed that the CaO content in the product was 0.006 wt%.

[0065] Example 6

[0066] The molecular sieve preparation method is the same as in Example 1, except that an equimolar amount of Fe(OH)2 is used instead of Mg(OH)2.

[0067] The obtained product is ZSM-5 molecular sieve with SiO2 / Al2O3 = 16.8 and crystallinity of 79.2%. ICP analysis showed that the FeO content in the product was 0.007 wt%.

[0068] Example 7

[0069] The molecular sieve preparation method is the same as in Example 1, except that an equimolar amount of Cu(OH)2 is used instead of Mg(OH)2.

[0070] The obtained product is ZSM-5 molecular sieve with SiO2 / Al2O3 = 19 and crystallinity of 87.6%. ICP analysis showed that the CuO content in the product was 0.006 wt%.

[0071] Example 8

[0072] The molecular sieve preparation method is the same as in Example 1, except that an equimolar amount of Zn(OH)2 is used instead of Mg(OH)2.

[0073] The obtained product is ZSM-5 molecular sieve, with SiO2 / Al2O3 = 18.3 and crystallinity of 88.5%. The ZnO content in the product was found to be 0.009 wt% by ICP testing.

[0074] Example 9

[0075] The molecular sieve preparation method is the same as in Example 1, except that the mixture also includes tetrapropylammonium hydroxide (OSDA), and the molar ratio of each component (excluding hydrogen-type ZSM-5 seed crystals) in the mixture is SiO2:0.063Al2O3:0.1NaOH:0.005Mg(OH)2:0.0001OSDA:50H2O.

[0076] The obtained product was ZSM-5 molecular sieve with SiO2 / Al2O3 = 18.4 and crystallinity of 86.2%. ICP analysis showed that the MgO content in the product was 0.002 wt%.

[0077] Example 10

[0078] The molecular sieve preparation method is the same as in Example 1, except that the molar ratio of each component (excluding hydrogen-type ZSM-5 seed crystals) in the mixture is SiO2:0.063Al2O3:0.1NaOH:0.5Mg(OH)2:50H2O.

[0079] The obtained product is ZSM-5 molecular sieve with SiO2 / Al2O3 = 15.6 and crystallinity of 75.4%. The MgO content in the product was found to be 0.012 wt% by ICP analysis.

[0080] Comparative Example 1

[0081] The molecular sieve preparation method is the same as in Example 1, except that Mg(OH)2 is not added to the mixture.

[0082] The product obtained was ZSM-5 molecular sieve, with SiO2 / Al2O3 = 31.6 and crystallinity of 52.8%.

[0083] Comparative Example 2

[0084] The molecular sieve preparation method is the same as in Example 1, except that Mg(OH)2 is not added to the mixture, but tetrapropylammonium hydroxide is added. The molar ratio of each component (excluding hydrogen-type ZSM-5 seed crystals) in the mixture is SiO2:0.063Al2O3:0.1NaOH:0.01OSDA:50H2O.

[0085] The product obtained was ZSM-5 molecular sieve, with SiO2 / Al2O3 = 32.4 and crystallinity of 87.7%.

[0086] Comparative Example 3

[0087] The molecular sieve preparation method is the same as in Example 1, except that NaOH is not added.

[0088] The specific preparation steps include:

[0089] Aluminum sol was dissolved in water, and silica sol was added dropwise while stirring. After stirring for 4 hours, magnesium hydroxide and hydrogen-form ZSM-5 seed crystals (SiO2 / Al2O3 = 50) were added to obtain a mixed solution. The mass of the ZSM-5 seed crystals was 8 wt% of the silica sol mass based on SiO2. The molar ratio of each component in the mixed solution (excluding hydrogen-form ZSM-5 seed crystals) was SiO2:0.063Al2O3:0.005Mg(OH)2:50H2O. The mixed solution was placed in a polytetrafluoroethylene-lined pressure vessel and crystallized at 150℃ for 5 days. After crystallization, the solution was naturally cooled to room temperature. The crystallized product was filtered, washed, and dried at 120℃ for 12 hours without calcination to obtain the final product.

[0090] The product obtained is an amorphous substance.

[0091] Comparative Example 4

[0092] Aluminum sol was dissolved in water, and silica sol was added dropwise while stirring. After stirring for 4 hours, a mixed solution of sodium hydroxide and magnesium hydroxide (total concentration of sodium hydroxide and magnesium hydroxide was 10 wt%) was added to obtain a first mixture. The molar ratio of the components in the first mixture was SiO2:0.063Al2O3:0.1NaOH:0.005Mg(OH)2:50H2O. Hydrogen-form ZSM-5 seed crystals (SiO2 / Al2O3 = 50) were added to the first mixture to obtain a second mixture. The mass of the ZSM-5 seed crystals was 8 wt% of the silica sol mass based on SiO2. The second mixture was placed in a polytetrafluoroethylene-lined pressure vessel and crystallized at 150°C for 5 days. After crystallization, the mixture was naturally cooled to room temperature. The crystallized product was filtered, washed, and dried at 120°C for 12 hours without calcination to obtain the final product.

[0093] The obtained product was ZSM-5 molecular sieve, with a SiO2 / Al2O3 ratio of 28.3 and a crystallinity of 88.1%. ICP analysis showed that the MgO content in the product was 0.007 wt%.

[0094] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing alumina-rich ZSM-5 molecular sieve, characterized in that, include: Raw materials including an aluminum source, a silicon source, a first alkali source, and water are mixed to form a gel; a mixture including the gel, a second alkali source, ZSM-5 seed crystals, and an optional organic template agent is obtained; the mixture is crystallized to obtain the aluminum-rich ZSM-5 molecular sieve. The first alkali source includes an alkali source containing an alkali metal; The second alkali source includes at least one of the following: an alkali source containing an alkaline earth metal, an alkali source containing a group VIII metal, an alkali source containing a group IB metal, and an alkali source containing a group IIB metal. The silicon source is calculated as SiO2, the aluminum source as Al2O3, the first alkali source as M1, the second alkali source as M2, and the organic template agent as OSDA. The molar ratios of each raw material are: 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. The ZSM-5 seed crystals are selected from non-Na-type ZSM-5 molecular sieves.

2. The preparation method according to claim 1, characterized in that, The first alkali source includes at least one of alkali metal hydroxide, alkali metal carbonate, alkali metal bicarbonate, and alkali metal fluoride; And / or, the second alkali source includes at least one of alkaline earth metal hydroxides, group VIII metal hydroxides, group IB metal hydroxides, and group IIB metal hydroxides.

3. The preparation method according to claim 2, characterized in that, 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; And / or, 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 preparation method according to any one of claims 1-3, characterized in that, 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. And / or, the silicon source includes at least one of silicon powder, silicon balls, silica gel, silica sol, sodium silicate, aluminosilicate, amorphous silica powder, methyl silicate, ethyl silicate, propyl silicate, silicon tetrachloride, silane, silica, and diatomaceous earth. And / or, 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 preparation method according to any one of claims 1-3, characterized in that, M1 / SiO2 = 0.03 to 0.3; and / or, M2 / SiO2 = 0.001 to 0.

1.

6. The preparation method according to claim 5, characterized in that, M2 / SiO2 = 0.002~0.

05.

7. The preparation method according to any one of claims 1-3, characterized in that, The SiO2 / Al2O3 ratio of the ZSM-5 seed crystal is 30 to ∞. And / or, the mass of the ZSM-5 seed crystal accounts for 0.05 to 10% of the mass of the silicon source in the mixed solution, calculated as SiO2.

8. The preparation method according to claim 7, characterized in that, The SiO2 / Al2O3 ratio of the ZSM-5 seed crystal is 40-500; And / or, the mass of the ZSM-5 seed crystal accounts for 1 to 9% of the mass of the silicon source in the mixed solution, calculated as SiO2.

9. The preparation method according to any one of claims 1-3, characterized in that, The crystallization treatment temperature is 100–200°C; the crystallization treatment time is 2–200 h.

10. The preparation method according to claim 9, characterized in that, The crystallization treatment temperature is 120–180°C; And / or, the crystallization treatment time is 48 to 150 hours.

11. The preparation method according to any one of claims 1-3, characterized in that, The crystallized product was cooled, filtered, washed, and dried to obtain the aluminum-rich ZSM-5 molecular sieve.

12. The preparation method according to claim 11, characterized in that, The drying temperature is 30–200°C.

13. The preparation method according to claim 12, characterized in that, The drying temperature is 80–150°C.

14. An aluminum-rich ZSM-5 molecular sieve, prepared by the preparation method described in any one of claims 1-13.

15. The alumina-rich ZSM-5 molecular sieve according to claim 14, characterized in that, The SiO2 / Al2O3 ratio of the aluminum-rich ZSM-5 molecular sieve is <20; And / or, the crystallinity of the alumina-rich ZSM-5 molecular sieve is ≥75%; And / or, the content of the second alkali source metal oxide in the aluminum-rich ZSM-5 molecular sieve is <0.05wt%.

16. The alumina-rich ZSM-5 molecular sieve according to claim 15, characterized in that, The crystallinity of the alumina-rich ZSM-5 molecular sieve is ≥80%; And / or, the content of the second alkali source metal oxide in the aluminum-rich ZSM-5 molecular sieve is <0.02wt%.

17. The alumina-rich ZSM-5 molecular sieve according to claim 16, characterized in that, The content of the second alkali source metal oxide in the aluminum-rich ZSM-5 molecular sieve is <0.01wt%.

18. The application of the aluminum-rich ZSM-5 molecular sieve according to any one of claims 14-17 in the field of catalysts.

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