阅读说明：本技术 一种氢型zsm-48分子筛的制备方法 (Preparation method of hydrogen type ZSM-48 molecular sieve ) 是由 邢恩会 王萍 方文秀 毕云飞 罗一斌 于 2020-05-06 设计创作，主要内容包括：本发明公开了一种氢型ZSM-48分子筛的制备方法,包括如下步骤：将硅源、无机碱和有机模板剂混合均匀的反应物经水热晶化得到结晶度≥90％的纯硅的ZSM-48分子筛作为中间产品；将有机碱与无碱金属铝源混合后,在密闭反应釜中50～190℃下处理0.1～5小时后冷却,得到无碱金属的四配位铝源；将所述的中间产品和所述的无碱金属的四配位铝源进行接触补铝并回收产物得到氢型ZSM-48分子筛。该制备方法无需经过铵交换,焙烧可获得低硅铝比的氢型ZSM-48分子筛。(The invention discloses a preparation method of a hydrogen type ZSM-48 molecular sieve, which comprises the following steps: carrying out hydrothermal crystallization on a reactant obtained by uniformly mixing a silicon source, inorganic alkali and an organic template agent to obtain a pure silicon ZSM-48 molecular sieve with the crystallinity of more than or equal to 90 percent as an intermediate product; mixing an organic alkali and an alkali-free aluminum source, treating for 0.1-5 hours at 50-190 ℃ in a closed reaction kettle, and cooling to obtain an alkali-free four-coordination aluminum source; and (3) contacting the intermediate product with the four-coordination aluminum source without alkali metal for aluminum supplement and recovering the product to obtain the hydrogen type ZSM-48 molecular sieve. The preparation method can obtain the hydrogen type ZSM-48 molecular sieve with low silica-alumina ratio by roasting without ammonium exchange.)

1. A preparation method of a hydrogen type ZSM-48 molecular sieve comprises the following steps:

(1) carrying out hydrothermal crystallization on a reactant obtained by uniformly mixing a silicon source, inorganic alkali and an organic template agent to obtain a pure silicon ZSM-48 molecular sieve with the crystallinity of more than or equal to 90 percent as an intermediate product;

(2) mixing an organic alkali and an alkali-free aluminum source, treating for 0.1-5 hours at 50-190 ℃ in a closed reaction kettle, and cooling to obtain an alkali-free four-coordination aluminum source;

(3) and (3) contacting the intermediate product in the step (1) with the alkali-free four-coordinate aluminum source in the step (2) to supplement aluminum, and recovering a product to obtain the hydrogen type ZSM-48 molecular sieve.

2. The method of claim 1, wherein the silicon source is selected from the group consisting of silica sol, silica white, ethyl orthosilicate, and water glass.

3. The process of claim 1, wherein the inorganic base is sodium hydroxide or potassium hydroxide.

4. The method according to claim 1, wherein said organic template is selected from the group consisting of ethylenediamine, 1, 3-propanediamine, 1, 4-butanediamine, 1, 5-pentanediamine, 1, 6-hexanediamine, 1, 7-heptanediamine, 1, 8-octanediamine, 1, 9-nonanediamine and one or a mixture of said substituted diamines.

5. The method according to claim 1, wherein the organic template is selected from one or a mixture of ethylenediamine, 1, 5-pentanediamine, 1, 6-hexanediamine, 1, 7-heptanediamine, or the diamines with substituents.

6. The process of claim 1 wherein said organic templating agent is 1, 6-hexanediamine.

7. The method of claim 1, wherein the intermediate product in step (1) has one of the following forms: (a) filtering and washing to obtain a molecular sieve filter cake without free alkali metal; (b) filtering, washing to obtain molecular sieve raw powder without free alkali metal and drying; (c) filtering, washing to remove free alkali metal, drying and roasting to remove the molecular sieve of the organic template agent.

8. The process of claim 1 wherein the reactants of step (1) have the following molar composition: m⁺/SiO₂＝0.01～0.30、R/SiO₂＝0.01～0.50、SiO₂/Al₂O₃＝300～∞、H₂O/SiO₂5 to 100, M represents an alkali metal, and R represents an organic template.

9. The method according to claim 1, wherein the organic base is one or more selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, n-butylamine, ethylamine, and propylamine; or the organic alkali is replaced by ammonia water.

10. The process of claim 1 wherein said organic base is tetramethylammonium hydroxide and/or tetraethylammonium hydroxide.

11. The process of claim 1 wherein said alkali-free aluminum source is selected from the group consisting of pseudoboehmite, alumina, and aluminum hydroxide.

12. The process of claim 1 wherein the reactants of step (1) have the following molar composition: m⁺/SiO₂＝0.01～0.20、R/SiO₂＝0.03～0.30、SiO₂/Al₂O₃＝500～∞、H₂O/SiO₂＝20～50。

13. The method according to claim 1, wherein the contact aluminum supplement in the step (3) is carried out at 0-180 ℃, preferably 20-160 ℃ for 1-48 h, preferably 20-36 h.

14. The process of claim 1 wherein the organic base is admixed with Al from an alkali-free aluminum source₂O₃The molar ratio of (A) to (B) is 0.2-40: 1.

15. the process of claim 1 wherein the organic base is admixed with Al from an alkali-free aluminum source₂O₃The molar ratio of (A) to (B) is 1-30: 1.

16. the process of claim 1 wherein the organic base is admixed with Al from an alkali-free aluminum source₂O₃The molar ratio of (A) to (B) is 2-20: 1.

17. The method of claim 1, wherein the mixture of step (3) has the following molar composition: SiO 2₂/Al₂O₃＝20～+∞、H₂O/SiO₂＝5～30。

18. The method of claim 1, wherein the mixture of step (3) has the following molar composition: SiO 2₂/Al₂O₃＝20～400、H₂O/SiO₂＝5～20。

Technical Field

The invention relates to a preparation method of a hydrogen type ZSM-48 molecular sieve, in particular to a method for directly preparing the hydrogen type ZSM-48 molecular sieve without ammonium exchange.

Background

The ZSM-48 molecular sieve with MRE topological structure is a kind of high-silicon zeolite, belonging to orthorhombic system, its channel structure is 10-membered ring open one-dimensional linear channels which are not mutually communicated, and the channels are mutually connected by 5-membered ring, and the diameter of the channel opening is 0.56 nm. The 10-membered ring channels of the ZSM-48 can be regarded as six-membered ring belts formed by 20T atoms, the channels can form two connections among the channels by moving 1/2 units in the channel direction, one connection is a curved chain connection, the other connection is a 4-membered ring connection, and each tubular channel is adjacent to 4 tubular channels, so that various polymorphs can be formed among the channels of the ZSM-48 molecular sieve, and the ZSM-48 is not a code of a material but represents a series of similar tubular channel materials.

Generally, due to the introduction of aluminum, the molecular sieve framework is negatively charged and requires a positive charge at the cationic position to balance. During the synthesis, alkali metal ions (Na) are generally used⁺And K⁺) And a protonated templating agent to balance the negative charge imparted by the aluminum, but the charge balanced by the alkali metal is not acidic. Therefore, it is necessary to exchange alkali metal ions for H⁺Or is exchanged for NH₄ ⁺Post-resolution to H⁺It has acid and acid catalytic activity. The same is true for the silica-alumina ZSM-48 molecular sieve.

Currently, various organic templates can be used to synthesize ZSM-48 molecular sieves, N-methylpyridine (US4585747), ethylenediamine (US5961951), alkylamine and tetramethylammonium (CN101330975A), N-diethylhexamethyleneimine quaternary ammonium (CN102040231A), hexamethylenediamine chloride (US7482300/US7625478), 1, 6-hexamethylenediamine or 1, 8-octanediamine (US 6923949A).

In 1983, US4397827 for the first time discloses the synthesis of a ZSM-48 molecular sieve, the template agent is C2-C12 alkylamine, preferably the mixture of C3-C5 alkylamine and tetramethylammonium hydroxide, and the silicon-aluminum ratio (SiO) of the synthesized ZSM-48 molecular sieve is₂/Al₂O₃Hereinafter, the same) range of 25 to infinity. The synthesized ZSM-48 molecular sieve has a needle-shaped or rod-shaped appearance, and a trace amount of octahedral metastable ZSM-48 precursor exists in a product. Subsequent research results show that when tetramethyl ammonium radical ion is used as template agent and NaOH is used as alkali source, no addition of alkali is neededWhen the crystal seeds or other templates are used, the synthesized main product is the ZSM-39 molecular sieve, and the pure-phase ZSM-48 molecular sieve cannot be synthesized.

US4423021 discloses a method for synthesizing ZSM-48 molecular sieve with high Si/Al ratio by using diamine of C4-C12 as template agent, wherein the product contains no or little aluminum because of the use of organic template agent different from that of US4397827, and the Si/Al ratio is in the range of 50 to infinity, preferably in the range of 100 to infinity.

Currently, ZSM-48 molecular sieves can be synthesized using a variety of organic templates. For example, N-methylpyridine (US4585747), ethylenediamine (US5961951), alkylamines and tetramethylammonium (CN101330975A), N-diethylhexamethyleneimine quaternary ammonium (CN102040231A), hexamethylenediamine chloride (US7482300/US7625478), 1, 6-hexanediamine or 1, 8-octanediamine (US6923949A) and the like.

In addition to the simple and relatively simple templates described above, a number of structurally complex templates are disclosed. EP-A-142317 discloses the synthesis of ZSM-48 molecular sieves in the presence of specific linear diquaternary ammonium compounds having the general formulｃA: [ (R)₃N⁺(Z)_m[(R)₃N⁺](X^-)²Wherein each R is an alkyl or heteroalkyl group having 1 to 20 carbon atoms, a cycloalkyl or cycloheteroalkyl group having 3 to 6 carbon atoms, or an aryl or heteroaryl group, Z is an alkylene or heteroalkylene group having 1 to 20 carbon atoms, an alkenylene or heteroalkylene group having 2 to 20 carbon atoms, or an arylenemetal or heteroarylene group, m is 5, 6, 8, 9, or 10, and X-is an anion. CN102910642A discloses a method for synthesizing a ZSM-48 molecular sieve by using dibromohexane, trimethylamine and ethanol as template agents, and the method has the characteristic of low synthesis cost, and the silica-alumina ratio is 150-500.

Generally, the silica to alumina ratio of the molecular sieve product is closely related to the templating agent. The research focus of the existing ZSM-48 molecular sieve is still the synthesis process, and the synthesis process has the following characteristics: 1) the synthesized molecular sieve has high silicon-aluminum ratio, so the application in the aspect of acid catalytic reaction faces certain limitation, even if a template agent with a complex structure and high price is adopted, the silicon-aluminum ratio of the generally synthesized ZSM-48 molecular sieve is more than 100; 2) if a template agent with lower cost is adopted, not only the synthesized ZSM-48 molecular sieve has higher silica-alumina ratio, but also long crystallization time is needed.

The method disclosed in US4585747 synthesizes ZSM-48 molecular sieve by using monomolecular or bimolecular N-methylpyridine as template agent, the feeding silica-alumina ratio is more than 250, and the synthesis time is more than 5 days. The method for synthesizing ZSM-48 disclosed in US5961951 takes cheap ethylenediamine as a template agent, the feeding silica-alumina ratio can be reduced to 200, and the synthesis time is greatly shortened to 65 h. US7482300 and US7625478 disclose a synthesis method of a ZSM-48 molecular sieve with a low silica alumina ratio, which uses expensive hexamethonium chloride as a template agent, and can obtain the ZSM-48 molecular sieve with the silica alumina ratio of about 100 after crystallization for 48 hours with the charge silica alumina ratio of about 100.

The synthesis of the ZSM-48 molecular sieve with low silica-alumina ratio by using different templates is also researched. CN104003413A discloses a method for synthesizing a ZSM-48 molecular sieve by using 1, N-bis (N-methylpyrrolidine) hexane bromide (N is 1-10), wherein the ZSM-48 molecular sieve obtained by the method is a regular rice-grain-shaped molecular sieve composed of nano rods, the particle size range of the regular rice-grain-shaped molecular sieve is 500-2000 nm, and the size of small cubic-grain-shaped small crystal grains is about 20-50 nm. Reported in microporus and mesoporus materials, 2004, 68(1-3), 97-104 as (CH3)₃N⁺(CH₂)_nN⁺(CH₃)₃Is taken as a template agent, and the raw material composition is SiO₂/Al₂O₃＝60、R/SiO₂A method for synthesizing a ZSM-48 molecular sieve under the condition of 0.1. CN106608635A discloses a method for preparing ZSM-48 molecular sieve, the template agent used is dinitrogen oxacycloalkane dibromide salt or organic matter with similar structure, synthesized SiO₂/Al₂O₃The range is 10 to 50.

In conclusion, the ZSM-48 molecular sieve can be synthesized by using organic amine with low cost, but the application of the ZSM-48 molecular sieve as an acid catalyst is limited due to the high silica-alumina ratio (generally more than 200); although the ZSM-48 molecular sieve with the silica-alumina ratio lower than 200 can be synthesized by utilizing a template with a complex structure and high cost, the hydrogen type ZSM-48 molecular sieve can be obtained only by a subsequent exchange process because alkali metal is introduced in the synthesis process.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a method for directly synthesizing a low silica-alumina ratio hydrogen type ZSM-48 molecular sieve without an ammonium exchange process.

A preparation method of a hydrogen type ZSM-48 molecular sieve comprises the following steps:

(1) carrying out hydrothermal crystallization on a reactant obtained by uniformly mixing a silicon source, inorganic alkali and an organic template agent R1 to obtain a pure silicon ZSM-48 molecular sieve with the crystallinity of more than or equal to 90 percent as an intermediate product;

(2) mixing an organic alkali and an alkali-free aluminum source, treating for 0.1-5 hours at 50-190 ℃ in a closed reaction kettle, and cooling to obtain an alkali-free four-coordination aluminum source;

(3) and (3) contacting the intermediate product in the step (1) with the alkali-free four-coordinate aluminum source in the step (2) to supplement aluminum, and recovering a product to obtain the hydrogen type ZSM-48 molecular sieve.

In the invention, the silicon source in the step (1) is a silicon source which can be stably dispersed in a water phase, and can be selected from silica sol, white carbon black, ethyl orthosilicate and water glass. The inorganic alkali is sodium hydroxide or potassium hydroxide. The organic template agent is selected from one or a mixture of ethylenediamine, 1, 3-propanediamine, 1, 4-butanediamine, 1, 5-pentanediamine, 1, 6-hexanediamine, 1, 7-heptanediamine, 1, 8-octanediamine, 1, 9-arbitrary diamine and the diamine with substituent groups; preferably, the organic template is selected from one or a mixture of ethylenediamine, 1, 5-pentanediamine, 1, 6-hexanediamine, 1, 7-heptanediamine or the diamines with substituent groups; more preferably, the organic template is 1, 6-hexamethylene diamine.

The hydrothermal crystallization in the step (1) is to put the uniform and transparent mixture prepared in the step (1) into a crystallization kettle, heat the mixture to 100-180 ℃, preferably 140-180 ℃, and perform hydrothermal crystallization for 24-240 hours, preferably 36-96 hours, wherein the crystallinity of the pure silicon molecular sieve can reach more than or equal to 90%, preferably 95%. The hydrothermal crystallization process may be static crystallization or dynamic crystallization, and dynamic crystallization is preferred.

The intermediate product in the step (1) is a pure silicon ZSM-48 molecular sieve, and as the silicon source in the step (3), the intermediate product can have one of the following forms: (a) filtering and washing to obtain a molecular sieve filter cake without free alkali metal; (b) filtering, washing to obtain molecular sieve raw powder without free alkali metal and drying; (c) filtering, washing to remove free alkali metal, drying and roasting to remove the molecular sieve of the organic template agent. The pure silicon molecular sieve is a molecular sieve with a silicon-aluminum molecular ratio of more than 500 determined by an XRF method, wherein a small amount of aluminum is possibly carried in by a silicon source. The synthesis process of the pure silicon molecular sieve is also suitable for promoting the crystallization of the molecular sieve by adding a small amount of pure silicon ZSM-48 seed crystals.

The reactants in the step (1) have the following molar compositions: m⁺/SiO₂＝0.01～0.30、R1/SiO₂＝0.01～0.50、SiO₂/Al₂O₃300 to infinity (Al content in silicon source is controlled without additionally adding an aluminum source), H₂O/SiO₂5 to 100, M represents an alkali metal, and R1 represents an organic templating agent; preferably, the reactants have the following molar composition: m⁺/SiO₂＝0.01～0.20、R1/SiO₂＝0.03～0.30、SiO₂/Al₂O₃500 ~ ∞ (depending on the purity of silicon source, no additional aluminum source), H₂O/SiO₂＝20～50。

In the invention, the organic base in the step (2) is selected from one or more of quaternary ammonium bases such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and the like or organic amines such as n-butylamine, ethylamine, propylamine and the like. Preferred organic bases are tetramethylammonium hydroxide, tetraethylammonium hydroxide, etc., and the organic base can also be replaced with aqueous ammonia. The alkali-free aluminum source can be one or more selected from pseudo-boehmite, alumina and aluminum hydroxide. In step (2), Al in organic alkali and alkali-free aluminum source₂O₃The molar ratio of (A) can be 0.2-40: 1. preferably 1-30: 1. more preferably 2 to 20: 1. The alkali-free four-coordination aluminum source is obtained by mixing an organic alkali R2 with the alkali-free aluminum source, treating the mixture in a closed reaction kettle at 50-190 ℃ for 0.1-5 hours and then cooling the mixture, and the alkali-free four-coordination aluminum source has the characteristics of uniformity, clarification and transparency.

In the invention, the step (3) is a contact aluminum supplement process, and the aluminum is supplemented in the step (1)And (3) heating the uniform and transparent mixture of the intermediate product and the alkali-free four-coordinate aluminum source in the step (2) to a wide range of 0-180 ℃ in a crystallization kettle, and carrying out contact crystallization for aluminum supplementation for 1-48 h, preferably 2-24 h to obtain the hydrogen type ZSM-48 molecular sieve. The mixture has the following molar composition: SiO 2₂/Al₂O₃＝20～+∞、H₂O/SiO₂Preferably, the mixture has the following molar composition: SiO 2₂/Al₂O₃＝20～400、H₂O/SiO₂5-20. The contact aluminum supplementing process can be static crystallization or dynamic crystallization, and the dynamic crystallization is preferred. The molecular sieve product obtained after the aluminum is supplemented by contacting with Al²⁷MAS NMR spectrum determination shows that all the aluminum enters the molecular sieve skeleton and no obvious non-skeleton aluminum is produced.

Because some organic bases are aqueous, such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, ethylamine, ammonia water and the like exist in the form of aqueous solutions with different percentage contents; there are also organic templating agents which are free of water and are themselves present in liquid form, such as n-butylamine and propylamine, for example, and therefore it is possible for the water in the mixture in step (3) to be introduced from the aqueous solution of the organic base in step (2), or to be additionally added in step (3) in the event of an insufficient water content or in the case of the use of a non-aqueous organic base, in principle as long as the mixture in step (3) satisfies H₂O/SiO₂5 to 30, preferably H₂O/SiO₂The content of the organic solvent is 5 to 20.

In the invention, the processes of hydrothermal crystallization, washing, drying, roasting and the like are all common technical means and technical conditions in the preparation process of the silicon-aluminum molecular sieve.

The preparation method provided by the invention fully utilizes the characteristic that hexamethylenediamine is easy to synthesize the pure silicon ZSM-48 molecular sieve when being used as a template agent, adopts the method of firstly synthesizing the pure silicon ZSM-48 molecular sieve, enhances the crystal seed guiding effect once the crystal of the ZSM-48 molecular sieve grows completely, and then utilizes an alkali-free four-coordinate aluminum source to supplement aluminum to the pure silicon ZSM-48 molecular sieve to obtain the silicon-aluminum ZSM-48 molecular sieve, wherein the aluminum is inserted into the framework of the molecular sieve to generate acidity and has no obvious non-framework aluminum. The molecular sieve does not need ammonium exchange, and the hydrogen type ZSM-48 molecular sieve can be directly obtained by roasting.

Drawings

The XRD spectrum of sample T1 of fig. 1.

Al of sample T1 of FIG. 2²⁷MAS NMR spectra.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

In the examples, the chemical composition of the molecular sieve was determined by X-ray fluorescence.

The relative crystallinity is expressed by percentage according to the ratio of the sum of the peak heights of two characteristic diffraction peaks of 20-24 degrees of 2 theta of an X-ray diffraction (XRD) spectrum of the obtained product and a ZSM-48 molecular sieve standard sample. The ZSM-48 molecular sieve synthesized using the method of example 5 in US4423021 was used as a standard and its crystallinity was determined to be 100%. XRD was measured on a SIMENS D5005 model X-ray diffractometer with CuK α radiation, 44 kv, 40 ma and a scan speed of 2 °/min.

²⁷The Al MAS NMR spectrum is obtained by a Bruker AVANCE III 600WB type nuclear magnetic resonance spectrometer test, and the test conditions are as follows: the resonance frequency is 78.155MHz, the magic angle rotating speed is 5kHz, the pulse width is 1.6 mus, the cycle delay time is 1s, and the scanning times are 8000 times.

Example 1

400g of silica sol (Shandong Yiming Industrial Co., Ltd., 30% SiO)₂) 7g of NaOH, 48g of 1, 6-hexanediamine (analytical grade, chemical reagents of the national pharmaceutical group Co., Ltd.) and 260g of water were mixed thoroughly and homogeneously, the reaction mixture had the following molar composition: m⁺/SiO₂＝0.087、R/SiO₂＝0.2、H₂O/SiO₂15. And (3) putting the reaction mixture into a crystallization kettle, heating to 160 ℃, performing hydrothermal dynamic crystallization for 48 hours, filtering and washing the product until no free alkali metal exists, drying, and roasting at 580 ℃ for 3 hours to obtain the pure silicon ZSM-48 molecular sieve (the crystallinity of which is 92 percent by determination).

Weighing 1g of pseudoboehmite (Changling catalyst works, Al)₂O₃75% content) was mixed with 60g of tetraethylammonium hydroxide aqueous solution (TEAOH content 20%) in a molar ratio TEAOH/Al₂O₃The mixture was placed in a crystallization kettle containing a teflon liner, reacted at 150 ℃ for 3 hours, and then cooled to room temperature to obtain a sodium-free tetra-coordinated aluminum source.

Uniformly mixing a sodium-free four-coordination aluminum source with 40g of the pure silicon ZSM-48 molecular sieve and 60g of water, wherein the molar composition of the mixture is as follows: SiO 2₂/Al₂O₃＝90、H₂O/SiO₂The mixture was hydrothermally crystallized in an autoclave at 150 ℃ for 15 hours. And (3) filtering and washing the crystallized product, drying the crystallized product for 4 hours at 120 ℃, and roasting the crystallized product for 3 hours at 550 ℃ to obtain a silicon-aluminum molecular sieve sample with the number of T1.

The XRD pattern of sample T1 is shown in FIG. 1, which shows ZSM-48 molecular sieve with a relative crystallinity of 99% and a silica to alumina ratio of 88.

Of sample S1²⁷An Al MAS NMR spectrum is shown in figure 2, the peak position of an aluminum spectrum is 50-70 ppm, and the aluminum in the sample is four-coordinate and is completely inserted into a framework to form framework aluminum.

Example 2

281g of tetraethoxysilane (containing 28% SiO)₂Beijing Chemicals company), 10.5g NaOH, 16.5g1, 6-hexanediamine and 378g water were mixed thoroughly and homogeneously, the reaction mixture having the following molar composition: m⁺/SiO₂＝0.2、R/SiO₂＝0.1、H₂O/SiO₂16. And (3) putting the reaction mixture into a crystallization kettle, heating to 160 ℃, performing hydrothermal dynamic crystallization for 48 hours, filtering and washing a product until no free alkali metal exists, drying, and roasting at 580 ℃ for 3 hours to obtain the pure silicon ZSM-48 molecular sieve (the crystallinity of the pure silicon ZSM-48 molecular sieve is determined to be 96%).

1.12 g of alumina (Changling catalyst works, Al) was weighed₂O₃98 percent of the total content), and 54g of tetrapropylammonium hydroxide aqueous solution (25 percent of TPAOH content, pure analysis, of New technology development center, Jiayou Beijing) are mixed, and the molar composition of the mixture is TPAOH/Al₂O₃6.16. Placing the mixture in a crystallization kettle with polytetrafluoroethylene lining, reacting at 150 deg.C for 3 hr, and cooling to room temperature to obtain sodium-freeA tetra-coordinated aluminum source.

Uniformly mixing a sodium-free four-coordination aluminum source with 40g of the pure silicon ZSM-48 molecular sieve and 140g of water, wherein the molar composition of the mixture is as follows: SiO 2₂/Al₂O₃＝62、H₂O/SiO₂The mixture was hydrothermally crystallized in an autoclave at 150 ℃ for 15 hours. And (3) filtering and washing the crystallized product, drying the crystallized product for 4 hours at 120 ℃, and roasting the crystallized product for 3 hours at 550 ℃ to obtain a silicon-aluminum molecular sieve sample with the number of T2.

The XRD pattern of sample T2 is characterized by FIG. 1, indicating ZSM-48, 95% relative crystallinity and a silica to alumina ratio of 60.

Of sample T2²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.

Example 3

200g of silica sol, 6.7g of NaOH, 18g of 1, 6-hexamethylenediamine and 220g of water are mixed thoroughly and homogeneously, the reaction mixture having the molar composition: m⁺/SiO₂＝0.167、R/SiO₂＝0.15、H₂O/SiO₂20. And (3) putting the reaction mixture into a crystallization kettle, heating to 140 ℃, carrying out hydrothermal dynamic crystallization for 48 hours, filtering and washing a product until free alkali metals do not exist, and drying to obtain pure silicon ZSM-48 molecular sieve raw powder (the crystallinity of the molecular sieve raw powder is determined to be 98%).

0.55 g of pseudoboehmite was weighed and mixed with 60g of tetraethylammonium hydroxide aqueous solution, the molar composition of the mixture being TEAOH/Al₂O₃20. And (3) placing the mixture into a crystallization kettle with a polytetrafluoroethylene lining, reacting at 150 ℃ for 3 hours, and cooling to room temperature to obtain a sodium-free four-coordination aluminum source.

Uniformly mixing a sodium-free four-coordination aluminum source with 40g and 97g of water of the pure silicon ZSM-48 molecular sieve, wherein the mixture comprises the following components in mole: SiO 2₂/Al₂O₃＝164、H₂O/SiO₂The mixture was hydrothermally crystallized in an autoclave at 150 ℃ for 24 hours. And (3) filtering and washing the crystallized product, drying for 4 hours at 120 ℃, and roasting for 3 hours at 550 ℃ to obtain a silicon-aluminum ZSM-48 molecular sieve sample with the number of T3.

The XRD pattern of sample T3 is characterized by FIG. 1, indicating ZSM-48, relative crystallinity 96%, silica to alumina ratio 150.

Of sample T3²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.

Example 4

200g of silica sol, 10g of NaOH, 12g of 1, 6-hexamethylenediamine and 400g of water are mixed thoroughly and homogeneously, the reaction mixture having the molar composition: m⁺/SiO₂＝0.25、R/SiO₂＝0.1、H₂O/SiO₂30. And (3) putting the reaction mixture into a crystallization kettle, heating to 160 ℃, and performing hydrothermal dynamic crystallization for 48 hours. The product is filtered, washed until no free alkali metal exists, dried and roasted at 580 ℃ for 3h to obtain the pure silicon ZSM-48 molecular sieve (the crystallinity of which is 99 percent by determination).

Weighing 1g of pseudoboehmite, mixing with 58g of tetraethylammonium hydroxide aqueous solution, and mixing the mixture to obtain a molar composition of TEAOH/Al₂O₃10.7. And (3) placing the mixture into a crystallization kettle with a polytetrafluoroethylene lining, reacting at 150 ℃ for 3 hours, and cooling to room temperature to obtain a sodium-free four-coordination aluminum source.

Uniformly mixing a sodium-free four-coordination aluminum source with 22g of the pure silicon ZSM-48 molecular sieve and 18g of water, wherein the molar composition of the mixture is as follows: SiO 2₂/Al₂O₃＝50、H₂O/SiO₂The mixture was hydrothermally crystallized in an autoclave at 150 ℃ for 15 hours ═ 9.8. And (3) filtering and washing the crystallized product, drying for 4 hours at 120 ℃, and roasting for 3 hours at 550 ℃ to obtain a silicon-aluminum ZSM-48 molecular sieve sample with the number of T4.

The XRD pattern of sample T4 is characterized by FIG. 1, indicating ZSM-48, relative crystallinity 99%, silica to alumina ratio 48.

Of sample T4²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.

Example 5

140g of ethyl orthosilicate, 2.2g of NaOH, 16g of 1, 6-hexanediamine and 360g of water are mixed thoroughly and homogeneously, the reaction mixture having the molar composition: m⁺/SiO₂＝0.08、R/SiO₂＝0.2、H₂O/SiO₂30. The reaction mixture is put into a crystallization kettle to be heated to 160 ℃, and after hydrothermal dynamic crystallization is carried out for 48 hours, the product is filtered and washed until no free alkali metal existsDrying, calcining at 580 deg.C for 3h to obtain pure silicon ZSM-48 molecular sieve (its crystallinity is 99% by determination).

0.45 g of alumina is weighed and mixed with 30g of tetrapropylammonium hydroxide aqueous solution (25% TPAOH, pure by analysis, from Beijing Jiayou Sheng New technology development center) to obtain a mixture with a molar composition of TPAOH/Al₂O₃8.53. Placing the mixture in a crystallization kettle with a polytetrafluoroethylene lining, reacting for 3 hours at 150 ℃, cooling to room temperature to obtain a sodium-free four-coordination aluminum source,

uniformly mixing a sodium-free four-coordination aluminum source with 40g and 140g of water of the pure silicon ZSM-48 molecular sieve, wherein the molar composition of the mixture is as follows: SiO 2₂/Al₂O₃＝154、H₂O/SiO₂13. The mixture is hydrothermally crystallized in a high-pressure reaction kettle at 150 ℃ for 15 hours. And (3) filtering and washing the crystallized product, drying for 4 hours at 120 ℃, and roasting for 3 hours at 550 ℃ to obtain a silicon-aluminum ZSM-48 molecular sieve sample with the number of T5.

The XRD pattern of sample T5 is characterized by FIG. 1, indicating ZSM-48, relative crystallinity 105%, silica to alumina ratio 147.

Of sample T5²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.

Example 6

200g of silica sol, 4g of NaOH, 30g of 1, 6-hexanediamine and 220g of water are fully and uniformly mixed, and the molar composition of a reaction mixture is as follows: m⁺/SiO₂＝0.1、R/SiO₂＝0.25、H₂O/SiO₂20. And (3) putting the reaction mixture into a crystallization kettle, heating to 140 ℃, carrying out hydrothermal dynamic crystallization for 48 hours, filtering and washing the product until free alkali metals do not exist, and obtaining a pure silicon ZSM-48 molecular sieve filter cake (the crystallinity of the product is determined to be 98%).

Weighing 1g of pseudoboehmite (Changling catalyst works, Al)₂O₃75% content) was mixed with 33g of tetraethylammonium hydroxide aqueous solution in a molar ratio R1/Al₂O₃6. Placing the mixture into a crystallization kettle with a polytetrafluoroethylene lining, reacting for 3 hours at 150 ℃, and cooling to room temperature to obtain a sodium-free four-coordination aluminum source.

Will not have four coordination of sodiumThe aluminum source was uniformly mixed with the pure silicon ZSM-48 molecular sieve filter cake (40 g dry basis) and 106g water, the molar composition of the mixture: SiO 2₂/Al₂O₃＝90、H₂O/SiO₂11. The mixture is hydrothermally crystallized in a high-pressure reaction kettle at 150 ℃ for 24 hours. And (3) filtering and washing the crystallized product, drying for 4 hours at 120 ℃, and roasting for 3 hours at 550 ℃ to obtain the silicon-aluminum ZSM-48 molecular sieve T6.

The XRD pattern of sample T6 is characterized by FIG. 1, indicating ZSM-48, relative crystallinity 99%, silica to alumina ratio 85.

Of sample T6²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.

Example 7

200g of silica sol, 6g of NaOH, 18g of 1, 5-pentanediamine and 200g of water are mixed thoroughly and homogeneously, the reaction mixture having the molar composition: m⁺/SiO₂＝0.15、R/SiO₂＝0.17、H₂O/SiO₂19. And (3) putting the reaction mixture into a crystallization kettle, heating to 160 ℃, and performing hydrothermal dynamic crystallization for 48 hours. The product is filtered, washed until no free alkali metal exists, dried and roasted at 580 ℃ for 3h to obtain the pure silicon ZSM-48 molecular sieve (the crystallinity of which is 92 percent by determination).

0.5g of pseudoboehmite was weighed and mixed with 40g of tetraethylammonium hydroxide aqueous solution, the molar composition of the mixture being TEAOH/Al₂O₃14.7. And (3) placing the mixture into a crystallization kettle with a polytetrafluoroethylene lining, reacting for 4 hours at 150 ℃, and cooling to room temperature to obtain a sodium-free four-coordination aluminum source.

Uniformly mixing a sodium-free four-coordination aluminum source with 22g and 35g of water of the pure silicon ZSM-48 molecular sieve, wherein the mixture comprises the following components in mole: SiO 2₂/Al₂O₃＝100、H₂O/SiO₂The mixture was hydrothermally crystallized in an autoclave at 150 ℃ for 24 hours at 10.2. And (3) filtering and washing the crystallized product, drying for 4 hours at 120 ℃, and roasting for 3 hours at 550 ℃ to obtain a silicon-aluminum ZSM-48 molecular sieve sample with the number of T7.

The XRD pattern of sample T7 is characterized by FIG. 1, indicating ZSM-48, relative crystallinity 94%, silica to alumina ratio 97.

Of sample T7²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.

Example 8

200g of silica sol, 7g of NaOH, 13g of 1, 7-heptanediamine and 210g of water are mixed thoroughly and homogeneously, the reaction mixture having the molar composition: m⁺/SiO₂＝0.17、R/SiO₂＝0.1、H₂O/SiO₂19.5. And (3) putting the reaction mixture into a crystallization kettle, heating to 160 ℃, and performing hydrothermal dynamic crystallization for 48 hours. The product is filtered, washed until no free alkali metal exists, dried and roasted at 580 ℃ for 3h to obtain the pure silicon ZSM-48 molecular sieve (the crystallinity of which is 99 percent by determination).

0.4 g of pseudoboehmite was weighed and mixed with 30g of tetraethylammonium hydroxide aqueous solution, the molar composition of the mixture being TEAOH/Al₂O₃13.84. And (3) placing the mixture into a crystallization kettle with a polytetrafluoroethylene lining, reacting at 150 ℃ for 6 hours, and cooling to room temperature to obtain a sodium-free four-coordination aluminum source.

Uniformly mixing a sodium-free four-coordinate aluminum source with 22g and 36g of water of the pure silicon ZSM-48 molecular sieve, wherein the molar composition of the mixture is as follows: SiO 2₂/Al₂O₃＝124、H₂O/SiO₂The mixture was hydrothermally crystallized in an autoclave at 150 ℃ for 24 hours ═ 9.1. And (3) filtering and washing the crystallized product, drying for 4 hours at 120 ℃, and roasting for 3 hours at 550 ℃ to obtain a silicon-aluminum ZSM-48 molecular sieve sample with the number of T8.

The XRD pattern of sample T8 is characterized by FIG. 1, indicating ZSM-48, relative crystallinity 95%, silica to alumina ratio 118.

Of sample T8²⁷The Al MAS NMR spectrum has the characteristics of fig. 2.