A process for the preparation of a catalyst containing a molecular sieve

Abstract

A preparation method of a catalyst containing a molecular sieve, characterized in that it comprises the following steps: (1) contacting and reacting alumina or a precursor of alumina with an organic amine to obtain a solution containing a four-coordinated aluminum species; (2) mixing a silicoaluminate molecular sieve with the solution containing the four-coordinated aluminum species in step (1) and then performing a hydrothermal reaction in a crystallization kettle, and filtering, washing and drying a crystallization product to obtain a first molecular sieve; (3) mixing and heating the first molecular sieve in step (2) with an acid solution, and filtering, washing and drying a product to obtain a second molecular sieve; (4) calcining the second molecular sieve in step (3) to obtain a modified hydrogen-type silicoaluminate molecular sieve; and (5) mixing the modified hydrogen-type silicoaluminate molecular sieve with a binder or a precursor thereof, an optional acid solution, an additive and water, shaping, drying and calcining.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve catalyst preparation, specifically to a method for preparing a catalyst containing molecular sieves, the catalyst prepared by the method, and its applications. Background Technology

[0002] The alkylation reaction of isobutane and butene is a crucial process in the petroleum refining industry for producing high-octane gasoline components. This alkylated oil, as an ideal high-octane gasoline blending component, possesses characteristics such as high octane number, low sensitivity, low Reid vapor pressure, low sulfur content, and absence of olefins and aromatics. Currently, the main industrial alkylation oil production processes are the sulfuric acid process and the hydrofluoric acid process. However, due to the corrosiveness and toxicity of sulfuric acid and hydrofluoric acid themselves, as well as the environmental hazards caused by waste acid emissions during the process, alkylation oil production enterprises are facing increasing safety and environmental pressures. Solid acid alkylation processes, with their advantages of environmental friendliness and good stability, are considered the most promising reaction processes. The core of solid acid alkylation processes lies in the development of high-performance solid acid catalysts. Currently, solid acid alkylation catalysts are mainly classified into four categories: metal halides, solid superacids, supported heteropolyacids, and molecular sieves. Among them, molecular sieve catalysts are widely used in the petrochemical field due to their large specific surface area, numerous acidic sites, tunable acidity, good thermal stability, and shape-selective catalysis. However, the rapid deactivation of catalysts still exists, which affects the industrialization of solid acid alkylation technology using molecular sieve catalysts.

[0003] CN109865532A discloses a method for preparing a solid acid-catalyzed C4 alkylation catalyst and its application. During the preparation of a hierarchical porous ZSM-5 molecular sieve, a certain amount of heteropolyacid compound (HPA) and metal components such as Pt and Fe are introduced in situ, allowing the heteropolyacid compound and Pt / Fe nanoparticles to grow in situ on the surface of the hierarchical ZSM-5 molecular sieve channels. This preparation method is easy to scale up and can be applied to the field of C4 alkylation acid catalysis, showing good industrial application prospects. The introduction of heteropolyacid as a supplementary catalyst, and the use of a molecular sieve with higher acidity as the active center, can further improve the alkylation performance.

[0004] CN104891525A discloses a method for preparing a strongly acidic, highly stable mesoporous molecular sieve. This method first synthesizes a Y-type molecular sieve precursor, then assembles the precursor under acidic conditions using a seed crystal method to obtain a first-step crystallization product. The pH value of the first-step crystallization product is adjusted, and a second-step crystallization is performed to obtain the final product. The prepared molecular sieve exhibits strong hydrothermal stability, strong acidity, and low cost. As a catalyst component, it demonstrates good catalytic cracking performance for heavy oil. However, the synthesis steps are cumbersome, and the acid content still needs further improvement for acid-catalyzed reactions. Summary of the Invention

[0005] The purpose of this invention is to meet the high acidity requirements of existing molecular sieve catalysts used in solid acid alkylation reactions, and to provide a method for preparing a catalyst containing molecular sieves. In the catalyst obtained by this method, the molecular sieve, as the active component, has a different silicon-to-aluminum ratio characteristic than that of existing technologies.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a catalyst containing a molecular sieve, characterized by comprising the following steps: (1) reacting alumina or an alumina precursor with an organic amine to obtain a solution containing a tetracoordinated aluminum species; (2) mixing the aluminosilicate molecular sieve with the solution containing the tetracoordinated aluminum species obtained in step (1) and then carrying out a hydrothermal reaction in a crystallization kettle, and filtering, washing and drying the crystallization product to obtain a first molecular sieve; (3) mixing and heating the first molecular sieve obtained in step (2) with an acid solution, and filtering, washing and drying the product to obtain a second molecular sieve; (4) calcining the second molecular sieve obtained in step (3) to obtain a modified hydrogen-type aluminosilicate molecular sieve; (5) mixing the modified hydrogen-type aluminosilicate molecular sieve with a binder or its precursor, an acid, an additive, and water, molding, drying and calcining.

[0007] In this invention, the binder is at least one of alumina, zirconium oxide, silicon dioxide, or titanium dioxide; the weight ratio of the molecular sieve to the binder is 5:95 to 75:25, preferably 10:90 to 50:50.

[0008] In this invention, the hydrogen-form aluminosilicate molecular sieve is obtained by post-treatment modification of the hydrogen-form aluminosilicate molecular sieve, through hydrothermal treatment to achieve secondary aluminization of the molecular sieve; this post-treatment modification process does not introduce alkali metal ions, does not require subsequent ion exchange, and residual organic amines can be removed by subsequent acid treatment and calcination. The modified hydrogen-form aluminosilicate molecular sieve has the following characteristics: (a) an A value of 4.0-6.0 and a B value of not less than 1.4. The aforementioned In the formula: Q4, Q3, Q2, Q1 and Q0 respectively correspond to molecular sieve MAS NMR. 29 The peak areas of the five resolvable peaks appearing in the Si spectrum correspond to the possible SiO4 tetrahedral structures of the species. From high field to low field, they are the resonance peaks corresponding to Si(4Si,0Al)), Si(3Si,1Al), Si(2Si,2Al), Si(1Si,3Al)), and Si(0Si,4Al). (This method is from "Research Methods for Solid Catalysts", edited by Xin Qin, Beijing: Science Press, 2004, p. 435); (b) The surface silicon-aluminum molar ratio is 0.9-2.0, and the surface elemental distribution is determined by X-ray photoelectron spectroscopy; (c) The bulk silicon-aluminum molar ratio is 2.0-4.0, and the bulk elemental distribution is determined by X-ray fluorescence spectroscopy.

[0009] Furthermore, the modified hydrogen-type aluminosilicate molecular sieve has a sodium oxide content of no more than 0.5 wt%, preferably no more than 0.2 wt%; and a specific surface area greater than 650 m². 2 / g; NH3-TPD acidity is greater than 2000μg / g.

[0010] Traditional methods for preparing modified molecular sieves typically involve direct synthesis to control the silica-to-alumina ratio. However, this method is complex, and the large amount of waste liquid generated during the preparation process can negatively impact the environment. The inventors discovered that by hydrothermally treating an existing molecular sieve with a solution containing four-coordinated aluminum species, followed by acid treatment and calcination, aluminum can be added to the framework of a simple molecular sieve. The resulting modified molecular sieve is then used for catalyst preparation. During high-temperature calcination, the organic amines adsorbed inside the molecular sieve during the modification process can protect the molecular sieve framework, increase the crystallinity of the molecular sieve in the catalyst, inhibit cell shrinkage, improve catalyst stability, and thus extend the catalyst's lifespan.

[0011] In this invention, the alumina precursor in step (1) is selected from one or more of boehmite, aluminum hydroxide, and aluminum sol. The organic amine has a wide selection range; preferably, it is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide. The mass ratio of alumina or its precursor to the organic amine is 0.01-2:1, preferably 0.04-1:1, and the alumina precursor is calculated as alumina. The contact reaction in step (1) is not particularly limited by conditions, as long as a stable and homogeneous solution can be obtained. For example, the conditions include: a temperature of 60-150℃, preferably 100-150℃, and a time of 1-10h, preferably 2-6h. The solution containing tetracoordinated aluminum species has a concentration of 0.4-20 wt% based on aluminum.

[0012] In this invention, the aluminosilicate molecular sieve in step (2) has a wide selection range. Preferably, the aluminosilicate molecular sieve is selected from one of the following: Y-type molecular sieve, X-type molecular sieve, β-type molecular sieve, MOR-type molecular sieve, and ZSM-5-type molecular sieve. The silica-to-alumina ratio of the aluminosilicate molecular sieve is 5-100, preferably 5-20. To facilitate the entry of tetracoordinated aluminum species into the molecular sieve framework, the mass ratio of the aluminosilicate molecular sieve in step (2) to the solution containing tetracoordinated aluminum species is 100-1:1, preferably 25-5:1, where the aluminosilicate molecular sieve is on a dry basis, and the solution containing tetracoordinated aluminum species is based on aluminum. The hydrothermal reaction conditions include: a temperature of 100-150℃ and a time of 1-20h, preferably 2-10h.

[0013] In this invention, through step (2), the four-coordinated aluminum species in the solution can enter the vacancies in the aluminosilicate molecular sieve framework, completing the molecular sieve framework and playing a role in finely adjusting the silica-to-alumina ratio of the molecular sieve. The solution containing the four-coordinated aluminum species refers to the solution capable of forming Al(OH)4 under the above mixing conditions. - The solution of the substance. The filtration, washing, and drying conditions are not particularly limited and can be any washing and drying conditions existing in the art. The washing is preferably performed by rinsing with hot water until neutral. Preferably, the drying conditions include: a temperature of 100-200°C, more preferably 100-150°C; and a time of 1-12 hours, more preferably 4-8 hours.

[0014] In this invention, steps (1) and (2) are preferably carried out in a homogeneous reactor after mixing in a crystallization kettle. This invention does not have any particular limitation on the equipment used to achieve the rotation conditions, and can be a conventional choice in the field. Those skilled in the art can select the rotation speed of the stirring equipment according to actual needs.

[0015] In this invention, step (3) involves using an acid solution to clean the pore structure and remove non-framework aluminum species. The acid can be selected from a wide range, as long as it can provide H+ in the presence of water. + The acid solution can be an organic acid or an inorganic acid; it can be a strong acid, a weak acid, or a moderately strong acid; preferably, the organic acid is a C2-C4 organic acid. The acid solution is selected from one or more of hydrochloric acid, nitric acid, lactic acid, oxalic acid, hydrofluoric acid, and fluorosilicic acid, and the concentration of the acid solution is 0.1-20 wt%, preferably 0.5-5 wt%. The acid solution is not particularly limited, as long as a homogeneous and stable solution can be obtained. Considering the need to save preparation costs, the solvent in the acid solution is preferably water, more preferably deionized water. The mass ratio of the acid solution to the second molecular sieve is 2-20:1, preferably 3-8:1. The reaction conditions include: a temperature of 40-95℃, preferably 50-70℃, and a time of 0.1-10 h, preferably 0.5-5 h. Most preferably, the acid solution is mixed with the first molecular sieve by dropwise addition at room temperature (approximately 25°C); the dropwise addition time is 0.1-10 hours, preferably 0.5-2 hours. Under these preferred conditions, it is more beneficial to repair and regulate the structure of the molecular sieve, thereby obtaining a modified molecular sieve with better diffusion performance. The mixing and heating treatment in step (3) is preferably carried out under stirring conditions. The present invention does not have any particular limitation on the equipment used to achieve the stirring conditions; any conventional choice in the art can be used. Those skilled in the art can select the stirring rate of the stirring equipment according to actual needs.

[0016] In this invention, the roasting atmosphere in step (4) has a wide range of selection; it can be carried out in an air atmosphere, a nitrogen atmosphere, or a water vapor atmosphere. The roasting conditions include: a temperature of 400-650℃, preferably 500-600℃; and a time of 0.5-4h, preferably 1-3h.

[0017] In this invention, the amount of the optional acid solution in step (5) is 0-5 wt% of the total dry weight of the molecular sieve and binder. Whether to add acid solution depends on the type of binder or its precursor. If the binder is alumina or the heat-resistant inorganic oxide precursor is an aluminum salt, then acid solution is added; if the binder is silica, titanium dioxide, zirconium oxide, or the binder precursor is a silicate, titanium salt, or zirconium salt, then no acid solution is added. The selection range of the acid solution is relatively wide. Preferably, the acid solution is selected from at least one of hydrochloric acid solution, nitric acid solution, oxalic acid solution, hydrofluoric acid solution, fluorosilicic acid solution, and citric acid solution. The amount of the optional additive is 0-5 wt% of the total dry weight of the molecular sieve and binder. The additive plays a role in lubrication and pore formation. In this invention, the dried mixed molding is first calcined, and then air-calcined to remove the additives, obtaining the calcined product. Preferably, the additive is selected from at least one of guar gum powder, methylcellulose, polyether, polyvinyl alcohol, cyclodextrin, and chitosan. The amount of water used is not particularly limited, as long as it is sufficient to ensure uniform mixing of the mixture, including the molecular sieve, binder or its precursor, and optional additives. Preferably, the weight ratio of water to the total dry weight of the other mixture (including the molecular sieve, binder or its precursor, and optional additives) is (0.8-1.2):1. According to the invention, the washing and drying conditions are not particularly limited and can be any washing and drying conditions existing in the art. The washing method of the invention preferably involves rinsing with hot water until neutral. The drying conditions include: a temperature of 100-200°C, preferably 100-150°C, and a time of 1-12 hours, preferably 4-8 hours. The filtration method described here is as previously stated and will not be repeated.

[0018] To achieve the objectives of this invention, a second aspect of this invention also provides a catalyst obtained by the above-described preparation method. The modified aluminosilicate molecular sieve contained therein has the following characteristics: (a) an A value of 4.0-6.0 and a B value of not less than 1.4. The aforementioned In the formula: Q4, Q3, Q2, Q1 and Q0 respectively correspond to molecular sieve MAS NMR. 29The peak areas of the five resolvable peaks in the Si spectrum correspond to the possible SiO4 tetrahedral structures of the species, and from high field to low field, they are the resonance peaks corresponding to Si(4Si,0Al)), Si(3Si,1Al), Si(2Si,2Al), Si(1Si,3Al)) and Si(0Si,4Al); (b) the surface silicon-aluminum molar ratio is 0.9-2.0, and the surface elemental distribution is determined by X-ray photoelectron spectroscopy; (c) the bulk silicon-aluminum molar ratio is 2.0-4.0, and the bulk elemental distribution is determined by X-ray fluorescence spectroscopy.

[0019] To achieve the objectives of this invention, a third aspect of the invention also provides the use of a catalyst in the alkylation reaction of isoalkanes and olefins. This use includes contacting isoalkanes and olefins under alkylation reaction conditions in the presence of a catalyst, said catalyst being the catalyst described in the second aspect of the invention. In this reaction, the catalyst exhibits a long cycle life and high selectivity for the target product. Detailed Implementation

[0020] The invention will be further illustrated below by way of examples, but these examples do not limit the scope of the invention. The endpoints and values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] In the examples, the silicon-to-aluminum ratio of the molecular sieve framework and the chemical states of silicon and aluminum were determined using solid-state nuclear magnetic resonance (MAS NMR). The specific surface area of ​​the molecular sieve samples was determined using the BET method with low-temperature N2 adsorption-desorption. The acidity of the molecular sieve samples was determined using NH3-programmed temperature desorption (NH3-TPD). The elemental distribution on the surface of the molecular sieve samples was determined by X-ray photoelectron spectroscopy (XPS). The elemental distribution in the bulk phase of the molecular sieve samples was determined by X-ray fluorescence spectroscopy (XRF).

[0022] Example 1

[0023] (1) Boehmite and 25wt% tetramethylamine hydroxide solution were mixed at a mass ratio of 0.125:1 and transferred into a crystallization vessel. The mixture was reacted for 4 hours at a reaction temperature of 120℃ to obtain a homogeneous and stable solution.

[0024] (2) Mix the HY type molecular sieve (sample number HY) with the above solution at a mass ratio of 25:1 (based on the dry basis weight of the molecular sieve and the Al(OH)4 content in the solution). -The mass ratio of the two liquids was used to transfer the mixed liquid into a crystallization vessel and react for 4 hours at a reaction temperature of 120°C. Then the mixture was filtered, washed, and dried at 110°C for 4 hours to obtain the first molecular sieve.

[0025] (3) At room temperature (25°C), a 1 wt% fluorosilicic acid solution is added dropwise into the first molecular sieve over 1 hour, wherein the mass ratio of the fluorosilicic acid solution to the first molecular sieve is 5:1. Then, the mixture is stirred at 65°C for 1 hour, filtered, washed, and dried at 110°C for 4 hours to obtain the second molecular sieve.

[0026] (4) The second molecular sieve was calcined at 550°C for 3 hours in air atmosphere to obtain a modified aluminosilicate molecular sieve sample, numbered MY-1.

[0027] (5) Mix MY-1 and pseudoboehmite at a dry weight percentage of 85:15, add 3wt% guar gum powder and 3wt% nitric acid respectively, add deionized water at a ratio of 1:1 of water weight to the total dry weight of other mixtures, mix evenly, extrude and mold, dry at 110°C so that the dry weight of the molded mixture is 75wt%, and then calcine at 550°C for 3h in air atmosphere to obtain the molded catalyst, numbered PYC-1.

[0028] Example 2

[0029] The molecular sieve was modified using the same method as in Example 1, except that in step (2), the HY-type molecular sieve was reacted with Al(OH)4 (calculated as Al). - The mass ratio was changed to 12:1; the modified molecular sieve sample was obtained, numbered MY-2. The formed catalyst was numbered PYC-2.

[0030] Example 3

[0031] The molecular sieve was modified using the same method as in Example 1, except that in step (2), the mass ratio of the HY-type molecular sieve to the solution (calculated as Al) was changed to 5:1; the modified molecular sieve sample was obtained and designated MY-3. The formed catalyst was designated PYC-3.

[0032] Example 4

[0033] The molecular sieve was modified using the same method as in Example 1, except that in step (2), the reaction temperature was changed to 150°C, resulting in a modified molecular sieve sample, designated MY-4. The formed catalyst was designated PYC-4.

[0034] Comparative Example 1

[0035] The method is the same as in Example 1, except that steps (1), (2), and (3) are omitted, while step (4) is retained. Specifically, the HY-type molecular sieve is calcined at 550°C for 3 hours in an air atmosphere to obtain a modified molecular sieve comparative sample, numbered HY-C. A shaped comparative catalyst is numbered DPYC-1.

[0036] Comparative Example 2

[0037] Following the same method as in Example 1, except that step (3) is omitted, while steps (1), (2), and (4) are retained, a modified molecular sieve comparative sample, designated HY-A, is obtained. A shaped comparative catalyst, designated DPYC-2, is also obtained.

[0038] Comparative Example 3

[0039] Following the same method as in Example 1, except that steps (1) and (2) are omitted, while steps (3) and (4) are retained, specifically: the HY-type molecular sieve is calcined at 550°C for 3 hours in an air atmosphere to obtain a modified molecular sieve comparative sample, numbered HY-G. The formed comparative catalyst is numbered DPYC-3.

[0040] Comparative Example 4

[0041] The molecular sieve was modified using the same method as in Example 1, except that in step (2), the mass ratio of the HY-type molecular sieve to the solution (calculated as Al) was changed to 1:1; a modified molecular sieve control sample was obtained, numbered MY-5. A prepared control catalyst was numbered DPYC-4.

[0042] Comparative Example 5

[0043] The molecular sieve was modified using the same method as in Example 1, except that in step (2), the reaction temperature was changed to 90°C, resulting in a modified molecular sieve control sample, designated MY-6. A prepared control catalyst was designated DPYC-5.

[0044] MAS NMR of the modified molecular sieve samples and control samples obtained in Examples 1-4 and Comparative Examples 1-5 above 29 The determination of Si, the low-temperature adsorption and desorption of N2, the temperature-programmed desorption of NH3, the X-ray photoelectron spectroscopy (XPS) analysis, the X-ray fluorescence spectroscopy (XRF) analysis, and the calculation results are shown in Table 1.

[0045] Table 1

[0046]

[0047] Test Example 1

[0048] This test example involves the alkylation of isoalkanes and olefins in a fixed-bed reactor using the catalysts obtained in the above examples and comparative examples, as well as the comparative catalyst.

[0049] Reaction conditions: The molar ratio of isobutane to mixed butenes (1-butene and 2-butene) was 250; the reaction temperature was 75℃; the reaction pressure was 2.5 MPa; and the feed flow rate was 38 mL / (g·h). The detection of butene in the product indicates catalyst deactivation; the reaction time before catalyst deactivation is defined as the catalyst's cycle life.

[0050] The results of the specific alkylation reactions are shown in Table 2. In Table 2, C8 selectivity represents the average result over the cycle life.

[0051] Table 2 lists the cycle life and C8 selectivity of the catalysts (numbered DC) obtained from HY molecular sieves.

[0052] Table 2

[0053] Molecular sieve number Catalyst number Catalyst cycle life (h) <![CDATA[C8 Selectivity (%)]]> HY DC 28 75 MY-1 PYC-1 40 83 MY-2 PYC-2 42 82 MY-3 PYC-3 40 80 MY-4 PYC-4 38 80 HY-C DPYC-1 8 62 HY-A DPYC-2 10 65 HY-G DPYC-3 10 63 MY-5 DPYC-4 22 70 MY-6 DPYC-5 28 72

[0054] Example 5

[0055] Same as Example 1, except that in step (5), MY-1 and pseudoboehmite are mixed at a dry weight percentage of 90:10. The resulting shaped catalyst is designated PYC-5.

[0056] Example 6

[0057] Same as Example 1, except that in step (5), MY-1 and pseudoboehmite are mixed at a dry weight percentage of 80:20. The resulting shaped catalyst is designated PYC-6.

[0058] Example 7

[0059] Same as Example 2, except that MY-2 and pseudoboehmite were mixed at a dry weight ratio of 90:10. The resulting shaped catalyst was designated PYC-7.

[0060] Example 8

[0061] Same as Example 2, except that MY-2 and pseudoboehmite were mixed at a dry weight percentage of 80:20. The resulting shaped catalyst was designated PYC-8.

[0062] Example 9

[0063] Same as Example 3, except that MY-3 and pseudoboehmite were mixed at a dry weight ratio of 90:10. The resulting shaped catalyst was designated PYC-9.

[0064] Example 10

[0065] Same as Example 3, except that MY-3 and pseudoboehmite were mixed at a dry weight percentage of 80:20. The resulting shaped catalyst was designated PYC-10.

[0066] Example 11

[0067] Same as Example 4, except that MY-4 and pseudoboehmite were mixed at a dry weight ratio of 90:10. The resulting shaped catalyst was designated PYC-11.

[0068] Example 12

[0069] Same as Example 4, except that MY-4 and pseudoboehmite were mixed at a dry weight percentage of 80:20. The resulting shaped catalyst was designated PYC-12.

[0070] Test Example 2

[0071] The test conditions for the alkylation reaction of catalysts PYC-5 to PYC-12 were the same as those for Test Example 1. The cycle life and C8 selectivity are shown in Table 3.

[0072] Table 3

[0073] Catalyst number Catalyst cycle life (h) <![CDATA[C8 selectivity (%)]]> PYC-5 44 82 PYC-6 42 80 PYC-7 42 80 PYC-8 38 82 PYC-9 40 82 PYC-10 38 80 PYC-11 38 80 PYC-12 38 78

Claims

1. A method for preparing a catalyst containing a molecular sieve, characterized in that, The process includes the following steps: (1) reacting alumina or its precursor with an organic amine to obtain a solution containing a tetracoordinated aluminum species; (2) mixing a hydrogen-form aluminosilicate molecular sieve with the solution containing the tetracoordinated aluminum species from step (1) and then performing a hydrothermal reaction in a crystallization kettle, the crystallization product being filtered, washed, and dried to obtain a first molecular sieve; (3) mixing the first molecular sieve from step (2) with an acid solution and heating the mixture, the product being filtered, washed, and dried to obtain a second molecular sieve; (4) calcining the second molecular sieve from step (3) to obtain a modified hydrogen-form aluminosilicate molecular sieve, wherein the modified hydrogen-form aluminosilicate molecular sieve has at least the characteristics of (a), (b), and (c): (a) an A value of 4.0-6.0 and a B value of not less than 1.4, the The In the formula: Q4, Q3, Q2, Q1 and Q0 respectively correspond to molecular sieve MAS NMR. 29 The peak areas of the five resolvable peaks in the Si spectrum correspond to the SiO4 tetrahedral structure of the species, and from high field to low field, they correspond to the resonance peaks of Si (4Si, 0Al)), Si (3Si, 1Al), Si (2Si, 2Al), Si (1Si, 3Al)) and Si (0Si, 4Al); (b) the surface silicon-aluminum molar ratio is 0.9-2.0, and the surface elemental distribution is determined by X-ray photoelectron spectroscopy; (c) the bulk silicon-aluminum molar ratio is 2.0-4.0, and the bulk elemental distribution is determined by X-ray fluorescence spectroscopy; (5) the modified hydrogen-type aluminosilicate molecular sieve is mixed with binder or its precursor, optional acid, additives, and water, molded, dried and calcined.

2. The preparation method according to claim 1, characterized in that, The precursor of alumina in step (1) is selected from one or more of boehmite, aluminum hydroxide and aluminum sol.

3. The preparation method according to claim 1, characterized in that, The organic amine in step (1) is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

4. The preparation method according to claim 1, characterized in that, The mass ratio of alumina or its precursor to organic amine in step (1) is 0.01-2:1, wherein the precursor of alumina is calculated as alumina.

5. The preparation method according to claim 4, characterized in that, The mass ratio of alumina or alumina precursor to organic amine in step (1) is 0.04-1:

1.

6. The preparation method according to claim 1, characterized in that, The contact reaction described in step (1) is subject to the following conditions: temperature of 60-150℃ and time of 1-10 h.

7. The preparation method according to claim 6, characterized in that, The contact reaction described in step (1) is subject to the following conditions: temperature of 100-150℃ and time of 2-6 h.

8. The preparation method according to claim 1, characterized in that, The solution containing tetracoordinated aluminum species in step (1) has a concentration of 0.4-20 wt% based on aluminum.

9. The preparation method according to claim 1, characterized in that, The hydrogen-type aluminosilicate molecular sieve in step (2) is selected from one of the hydrogen-type Y-type molecular sieve, X-type molecular sieve, β-type molecular sieve, MOR-type molecular sieve and ZSM-5-type molecular sieve.

10. The preparation method according to claim 1, characterized in that, The silicon-to-aluminum ratio of the hydrogen-type aluminosilicate molecular sieve in step (2) is 5-100.

11. The preparation method according to claim 10, characterized in that, The silicon-to-aluminum ratio of the hydrogen-type aluminosilicate molecular sieve in step (2) is 5-20.

12. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the hydrogen-form aluminosilicate molecular sieve to the solution containing four-coordinated aluminum species is 100-1:1, wherein the hydrogen-form aluminosilicate molecular sieve is on a dry basis and the solution containing four-coordinated aluminum species is based on aluminum.

13. The preparation method according to claim 12, characterized in that, In step (2), the mass ratio of the hydrogen-type aluminosilicate molecular sieve to the solution containing tetracoordinated aluminum species is 25-5:

1.

14. The preparation method according to claim 1, characterized in that, The hydrothermal reaction in step (2) is subject to the following conditions: temperature of 100-150℃ and time of 1-20 h.

15. The preparation method according to claim 1, characterized in that, The acid solution in step (3) is selected from one or more of hydrochloric acid, nitric acid, lactic acid, oxalic acid, hydrofluoric acid and fluorosilicic acid.

16. The preparation method according to claim 1, characterized in that, The acid solution described in step (3) has a concentration of 0.1-20 wt%.

17. The preparation method according to claim 16, characterized in that, The acid solution described in step (3) has a concentration of 0.5-5 wt%.

18. The preparation method according to claim 1, characterized in that, The mass ratio of the acid solution to the first molecular sieve in step (3) is 2-20:

1.

19. The preparation method according to claim 18, characterized in that, The mass ratio of the acid solution to the first molecular sieve in step (3) is 3-8:

1.

20. The preparation method according to claim 1, characterized in that, The heating treatment in step (3) includes the following conditions: temperature of 40-95℃ and time of 0.1-10 h.

21. The preparation method according to claim 20, characterized in that, The heating treatment in step (3) includes the following conditions: temperature of 50-70℃ and time of 0.5-5 h.

22. The preparation method according to claim 1, characterized in that, The roasting process described in step (4) includes the following conditions: temperature of 400-650℃ and time of 0.5-4 h.

23. The preparation method according to claim 22, characterized in that, The roasting process described in step (4) includes the following conditions: temperature of 500-600℃ and time of 1-3 h.

24. The preparation method according to claim 1, characterized in that, The sodium oxide content of the modified hydrogen-type aluminosilicate molecular sieve in step (4) does not exceed 0.5 wt%.

25. The preparation method according to claim 24, characterized in that, The sodium oxide content of the modified hydrogen-type aluminosilicate molecular sieve in step (4) does not exceed 0.2 wt%.

26. The preparation method according to claim 1, characterized in that, The modified hydrogen-type aluminosilicate molecular sieve in step (4) has a specific surface area greater than 650 m². 2 / g.

27. The preparation method according to claim 1, characterized in that, The modified hydrogen-type aluminosilicate molecular sieve in step (4) has an NH3-TPD acidity greater than 2000 μg / g.

28. The preparation method according to claim 1, characterized in that, The adhesive in step (5) is at least one of alumina, zirconium oxide, silicon dioxide and titanium dioxide.

29. The preparation method according to claim 1, characterized in that, Step (5) When the binder is alumina or the precursor of the binder is an aluminum salt, an acid solution is added. The amount of the acid solution is no more than 5 wt% of the total dry weight of the molecular sieve and the binder.

30. The preparation method according to claim 1 or 29, characterized in that, The acid solution in step (5) is selected from at least one of hydrochloric acid solution, nitric acid solution, oxalic acid solution, hydrofluoric acid solution, fluorosilicic acid solution and citric acid solution.

31. The preparation method according to claim 1, characterized in that, The amount of the additive used in step (5) is 0-5 wt% of the total dry weight of the molecular sieve and binder. The additive is selected from at least one of guar gum powder, methylcellulose, polyether, polyvinyl alcohol, cyclodextrin and chitosan.

32. The preparation method according to claim 1, characterized in that, The weight ratio of the molecular sieve to the binder in step (5) is 5:95 to 75:

25.

33. The preparation method according to claim 32, characterized in that, The weight ratio of the molecular sieve to the binder in step (5) is 10:90 to 50:

50.

34. A catalyst containing a molecular sieve obtained by any one of claims 1-33.

35. The use of the molecular sieve-containing catalyst of claim 34 in the alkylation reaction of isoalkanes and alkenes.

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