CN111422881A

CN111422881A - TON type zeolite molecular sieve and preparation method thereof

Info

Publication number: CN111422881A
Application number: CN202010279420.3A
Authority: CN
Inventors: 闫文付; 苏浩鹏; 聂冰莹; 于吉红; 徐如人
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2020-07-17
Anticipated expiration: 2040-04-10
Also published as: CN111422881B

Abstract

The invention provides a TON type zeolite molecular sieve and a preparation method thereof, belonging to the technical field of TON type zeolite molecular sieve preparation. The preparation method provided by the invention comprises the following steps: mixing a silicon source, an aluminum source, an inorganic base, water and a template agent under a closed condition to obtain gel; the template agent is tetramethylene hydroxide bis- (1-methylimidazole); and carrying out static hydrothermal reaction on the gel in an oven to obtain the TON type zeolite molecular sieve. The invention takes tetramethylene hydroxide bis- (1-methylimidazole) as a template agent to carry out static hydrothermal reaction in an oven, effectively solves the problems of higher silicon-aluminum ratio and fewer acid sites of the TON type molecular sieve prepared by the prior art, and has low production cost.

Description

TON type zeolite molecular sieve and preparation method thereof

Technical Field

The invention belongs to the technical field of TON type zeolite molecular sieve preparation, and particularly relates to a TON type zeolite molecular sieve and a preparation method thereof.

Background

Molecular sieves are a class of inorganic microporous materials with regular and uniform pore structures and have wide applications in the fields of adsorption, catalysis, ion exchange and the like. Wherein the TON type molecular sieve has a one-dimensional ten-membered ring channel structure and a channel rulerCun is just about

Slightly smaller than ZSM-5 and ZSM-11. Owing to its strong shape selectivity, TON type molecular sieve has wide application in industry, such as alkane isomerization, propene oligomerization, petroleum dewaxing, etc.

Chinese patent CN200910012472.8 discloses a preparation method for synthesizing TON type molecular sieve using organic structure directing agent, which comprises: preparing gel containing silicon source, aluminum source, organic template agent, halogen compound, alkali and water, then carrying out dynamic hydrothermal reaction on the gel in a high-pressure autoclave reactor with self-generated pressure, and separating to obtain a molecular sieve product with TON topological structure.

A method for the dynamic synthesis of TON-type molecular sieves of different sizes in alcohols and glycols is disclosed in the literature "Jamil A K, Muraza O, Al-Amer A M. the role of alcohols and diols asco-solvents in the simulation of TON zeolite [ J ]. Journal of Industrial and engineering Chemistry 2015: S1226086X15000994".

The document "Wang Y, Wang X, Wu Q, et al, seed-directed and organic template-free synthesis of TON Zeolite [ J ]. Catalysis Today,2014,226: 103-108" discloses a process for the dynamic synthesis of high-silicon TON-type molecular sieves without the introduction of an organic template under hydrothermal conditions.

The synthesis of the TON type molecular sieve disclosed in the prior art needs to be carried out under dynamic conditions, and the TON type molecular sieve prepared by the method has higher silicon-aluminum ratio.

Disclosure of Invention

In view of the above, the present invention provides a TON type zeolite molecular sieve and a preparation method thereof. The TON type zeolite molecular sieve prepared by the invention has low silicon-aluminum ratio.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of TON type zeolite molecular sieve, comprising the following steps:

mixing a silicon source, an aluminum source, an inorganic base, water and a template agent under a closed condition to obtain gel; the template agent is tetramethylene hydroxide bis- (1-methylimidazole);

and carrying out static hydrothermal reaction on the gel in an oven to obtain the TON type zeolite molecular sieve.

Preferably, the mass of the silicon source is calculated by silicon dioxide, the mass of the aluminum source is calculated by aluminum oxide, the mass of the inorganic base is calculated by sodium oxide, and the gel comprises the following components in molar ratio:

Na₂O:ROH:SiO₂:Al₂O₃:H₂o is 3-8: 1-9: 30-70: 1: 750-950, and the ROH is a template agent.

Preferably, the gel comprises the following components in molar ratio:

Na₂O:ROH:SiO₂:Al₂O₃:H₂O＝5～6:2～5:40～60:1:800～900。

preferably, the gel comprises the following components in molar ratio:

Na₂O:ROH:SiO₂:Al₂O₃:H₂O＝5.86:2.72:49.3:1.00:857。

preferably, the tetramethylene hydroxide bis- (1-methylimidazole) is added in the form of an aqueous solution of tetramethylene hydroxide bis- (1-methylimidazole), and the mass concentration of the aqueous solution of tetramethylene hydroxide bis- (1-methylimidazole) is 10-17%.

Preferably, the temperature of the static hydrothermal reaction is 150-200 ℃, and the time of the static hydrothermal reaction is 3-10 days.

The invention also provides the TON type zeolite molecular sieve prepared by the preparation method of the technical scheme, wherein the silicon-aluminum ratio of the TON type zeolite molecular sieve is 17-23, and the particle size is 2.5-5.5 mu m.

The preparation method provided by the invention comprises the following steps: mixing a silicon source, an aluminum source, an inorganic base, water and a template agent under a closed condition to obtain gel; the template agent is tetramethylene hydroxide bis- (1-methylimidazole); carrying out static hydrothermal reaction on the gel in an oven to obtain TON typeA zeolite molecular sieve. In the invention, two nitrogen atoms are respectively contained at two ends of a molecular chain of template agent tetramethylene bis (1-methylimidazole), each nitrogen atom contains a positive charge which can be used as an attack site of a negative charge group, and in the nucleation stage of TON type zeolite molecular sieve crystals, the nitrogen atoms on the template agent are easy to react with AlO with negative charge₂ ^-Radicals forming a bond to AlO₂ ^-The groups can enter the framework of the molecular sieve more easily, the silicon-aluminum ratio of the TON type zeolite molecular sieve is reduced, and the acid sites are increased. The invention takes tetramethylene hydroxide bis- (1-methylimidazole) as a template agent to carry out static hydrothermal reaction in an oven, effectively solves the problem of higher silica-alumina ratio of the TON type molecular sieve prepared by the prior art, and has more acid sites and low production cost. The example result shows that the silicon-aluminum ratio of the TON type zeolite molecular sieve prepared by the invention is 17.2-22.5, and the particle size is 2.5-5.5 μm.

Drawings

FIG. 1 is an X-ray diffraction pattern of TON type molecular sieves prepared in examples 1-5 and comparative examples 1-3 of the present invention;

FIG. 2 is a scanning electron micrograph of the TON type molecular sieve prepared in example 1;

FIG. 3 is a scanning electron micrograph of the TON type molecular sieve prepared in example 2;

FIG. 4 is a scanning electron micrograph of the TON type molecular sieve prepared in example 3;

FIG. 5 is a scanning electron micrograph of the TON type molecular sieve prepared in example 4;

FIG. 6 is a scanning electron micrograph of the TON type molecular sieve prepared in example 5;

FIG. 7 is a scanning electron micrograph of the TON type molecular sieve prepared in comparative example 1.

Detailed Description

Under a closed condition, a silicon source, an aluminum source, inorganic alkali, water and a template agent are mixed to obtain gel.

In the present invention, the raw materials used are all commercial products conventional in the art unless otherwise specified.

In the present invention, the template agent is tetramethylene hydroxide bis- (1-methylimidazole), the tetramethylene hydroxide bis- (1-methylimidazole) is preferably added in the form of a tetramethylene hydroxide bis- (1-methylimidazole) aqueous solution, and the mass concentration of the tetramethylene hydroxide bis- (1-methylimidazole) aqueous solution is preferably 10% to 17%, and more preferably 12%; the tetramethylene hydroxide bis- (1-methylimidazole) is preferably purchased from kenter catalytic materials, inc. In the invention, the kinetic diameter of the tetramethylene hydroxide bis- (1-methylimidazole) is similar to the diameter of the pore canal of the TON type molecular sieve, and the synthesis of the TON type molecular sieve can be guided. Two nitrogen atoms are respectively contained at two ends of a molecular chain of the tetramethylene hydroxide bis (1-methylimidazole), each nitrogen atom contains a positive charge which can be used as an attack site of a negative charge group, and in the nucleation stage of the TON type zeolite molecular sieve crystal, the nitrogen atom on the template agent is easy to react with AlO with negative charge₂ ^-Radicals forming a bond to AlO₂ ^-The groups can enter the framework of the TON type molecular sieve more easily, and the silicon-aluminum ratio of the TON type zeolite molecular sieve is reduced. In the present invention, the framework of the TON type molecular sieve is mainly composed of silicon aluminum oxygen Tetrahedron (TO)₄Where T ═ Si or Al). When all T atoms in the framework are silicon, the framework of the TON type molecular sieve is neutral; AlO, which is a substituted alundum when a part of silicon atoms is substituted with aluminum atoms₄Will be charged with a negative charge and require cations in the pores to balance the AlO₄If the balancing cation is H⁺The molecular sieve as a whole will exhibit acidity. After the silicon-aluminum ratio of the TON type molecular sieve is reduced, the content of aluminum-oxygen tetrahedron in the TON type molecular sieve is increased, so that the acidic site of the TON type molecular sieve is causedThe number of dots increases.

In the invention, the silicon source preferably comprises silica gel and/or white carbon black, and the form of the silica gel is preferably solid or liquid; when the silica gel is preferably a liquid silica sol, SiO in the liquid silica sol₂The mass percentage of the component (A) is 30-40%; the balancing cation in the liquid silica sol is preferably ammonium ion; the particle size of the silicon source is preferably 15-30 nm. In the present invention, the aluminum source preferably comprises one or more of sodium metaaluminate, aluminum hydroxide and aluminum oxide, and further preferably sodium metaaluminate in the present embodiment; the particle size of the aluminum source is preferably 5-10 nm. In the present invention, the inorganic base preferably includes sodium hydroxide and/or sodium carbonate, and further preferably sodium hydroxide in the embodiment of the present invention. In the present invention, the water is preferably distilled water.

In the present invention, the mixing order is preferably that an aluminum source, an inorganic base, water and a template agent are mixed and then mixed with a silicon source; the temperature of the mixing is preferably room temperature. In the present invention, the mixing is preferably performed by stirring; the stirring speed is preferably 100-300 rpm. In the present invention, the stirring time is not particularly limited, and the raw materials can be uniformly mixed.

In the present invention, the mass of the silicon source is calculated by silica, the mass of the aluminum source is calculated by alumina, the mass of the inorganic base is calculated by sodium oxide, and the gel preferably comprises the following components in a molar ratio of Na₂O:ROH:SiO₂:Al₂O₃:H₂O is 3-8: 1-9: 30-70: 1: 750-950, the ROH is a template agent, and Na is more preferable₂O:ROH:SiO₂:Al₂O₃:H₂O is 5 to 6:2 to 5:40 to 60:1:800 to 900, and more preferably Na₂O:ROH:SiO₂:Al₂O₃:H₂O＝5.86:2.72:49.3:1.00:857。

After obtaining the gel, the gel is subjected to a static hydrothermal reaction in an oven to obtain the TON type zeolite molecular sieve.

In the invention, the temperature of the static hydrothermal reaction is preferably 150-200 ℃, and more preferably 160-170 ℃; the time of the static hydrothermal reaction is preferably 3 to 10 days, and more preferably 4 to 5 days. The static hydrothermal reaction in the oven can not only reduce the silicon-aluminum ratio of the TON type molecular sieve and increase the acid sites, but also reduce the production cost.

After the static hydrothermal reaction is finished, the invention preferably further comprises the steps of sequentially carrying out solid-liquid separation, water washing and drying on the obtained static hydrothermal reaction product.

In the invention, the obtained hydrothermal reaction product is preferably cooled to room temperature, and then solid-liquid separation, water washing and drying are sequentially carried out. In the present invention, the solid-liquid separation is preferably performed by suction filtration or centrifugation. The present invention does not specifically limit the specific operation conditions of the suction filtration or centrifugation, and may employ suction filtration or centrifugation known to those skilled in the art. The specific operation conditions of the water washing in the present invention are not particularly limited, and the water washing operation known to those skilled in the art may be employed. The invention removes the raw materials which do not participate in the reaction in the static hydrothermal reaction by water washing.

In the invention, the drying temperature is preferably 75-100 ℃, and more preferably 80 ℃; the drying time is preferably 6-12 h, and more preferably 8 h. In the present invention, the drying is preferably performed in an oven.

The TON-type zeolite molecular sieve and the preparation method thereof provided by the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.

Example 1

0.0286g of sodium metaaluminate, 0.0614g of sodium hydroxide and 1.201m of L parts of distilled water are added into a reaction vessel, the mixture is stirred uniformly under the conditions of sealing and room temperature, 0.908m of L parts by mass of 12% aqueous tetramethylenebis (1-methylimidazole) hydroxide solution (purchased from kenter catalytic materials, Ltd.) is added, and then 1.165g of silica sol (in which the cation is balanced) is addedThe seed is ammonium ion, SiO₂0.4660g) under sealed condition at room temperature, stirring to obtain uniform gel containing Na as effective component and molar ratio₂O:ROH:SiO₂:Al₂O₃:H₂And (3) performing static hydrothermal reaction for 5 days at the temperature of 170 ℃ in a drying box, wherein O is 5.86:2.72:49.3:1.00: 857.

After the hydrothermal reaction, solid-liquid separation was performed using a centrifugal device, and the solid product was dried in an oven at 75 ℃ for 12 hours after washing to obtain a product, which was designated as H1.

The crystallinity and the silicon-to-aluminum ratio (Si/Al) of H1 were measured and are shown in Table 1. Wherein, the crystallinity of H1 is calculated by XRD diffraction data, and the calculation method is a conventional technical method in the field; the silicon to aluminum ratio (Si/Al) is calculated from the X-ray fluorescence data, using methods conventional in the art.

FIG. 1 is an X-ray diffraction pattern of TON type molecular sieves obtained in examples 1-5 and comparative examples 1-3 of the present invention, wherein curve 1 is the X-ray diffraction pattern of H1, and H1 is a molecular sieve having TON structure, as compared with the standard diffraction pattern published by the International molecular sieves Association.

FIG. 2 is a scanning electron micrograph of the TON type molecular sieve prepared in example 1, wherein the particle size of H1 was 4 μm as observed by a scanning electron microscope.

Example 2

Adding 0.0505g of aluminum hydroxide, 0.0259g of sodium hydroxide and 0.22m of L distilled water into a reaction vessel, uniformly stirring under the condition of sealing and room temperature, adding 12.33m of L mass percent of tetramethylenebis (1-methylimidazole) hydroxide aqueous solution with the mass concentration of 12 percent, and then adding 1.945g of white carbon black (SiO among the SiO)₂Mass 1.945g), stirring under sealed condition at room temperature to form uniform gel, wherein the effective component and molar ratio are Na₂O:ROH:SiO₂:Al₂O₃:H₂And (3) performing static hydrothermal reaction for 3 days at the temperature of 200 ℃ in a drying box under the condition that O is 3.00:9.00:50.1:1.00: 949.

After the hydrothermal reaction, solid-liquid separation was performed using a centrifuge, and the solid product was dried in an oven at 100 ℃ for 8 hours after washing to obtain a product, which was designated as H2.

The crystallinity and Si/Al of the product H2 were measured and are shown in Table 1.

Curve 2 in FIG. 1 is the X-ray diffraction pattern of H2, and by comparison with the standard diffraction pattern published by the International molecular sieves society, H2 is a molecular sieve having a TON structure.

FIG. 3 is a scanning electron micrograph of the TON type molecular sieve prepared in example 2, wherein the particle size of H2 was 4.5 μm as observed by a scanning electron microscope.

Example 3

0.14g of alumina, 0.44g of sodium hydroxide and 16.0m of L g of distilled water were charged into a reaction vessel, stirred uniformly under a closed condition at room temperature, added with a 2.90m L mass% aqueous solution of tetramethylenebis (1-methylimidazole) hydroxide, and then added with 5.77g of solid silica gel (in which SiO is contained)₂5.77g) under sealed conditions at room temperature to form a uniform gel containing Na as the active ingredient in a molar ratio₂O:ROH:SiO₂:Al₂O₃:H₂And (3) performing static hydrothermal reaction for 10 days in a drying oven at 150 ℃ under the condition that O is 8:1:70:1: 750.

After the hydrothermal reaction, solid-liquid separation was performed by suction filtration, and the solid product was dried in an oven at 100 ℃ for 9 hours after washing to obtain a product, which was designated as H3.

The crystallinity and Si/Al of the product H3 were measured and are shown in Table 1.

Curve 3 in FIG. 1 is the X-ray diffraction pattern of H3, and by comparison with the standard diffraction pattern published by the International molecular sieves society, H3 is a molecular sieve having the TON structure.

FIG. 4 is a scanning electron micrograph of the TON type molecular sieve prepared in example 3, wherein the particle size of H3 was 3.5 μm as observed by a scanning electron microscope.

Example 4

0.099g of sodium metaaluminate, 0.217g of sodium hydroxide and 9.58m of L distilled water are added into a reaction vessel, the mixture is stirred uniformly under the conditions of sealing and room temperature, a 6.90m L12% aqueous solution of tetramethylene hydroxide bis (1-methylimidazole) is added, and then 1.30g of white carbon black (SiO 2 among them) is added₂Mass 1.30g), stirring under sealed condition at room temperature to form uniform gel with effective component composition and molar ratio of Na₂O:ROH:SiO₂:Al₂O₃:H₂And (3) performing static hydrothermal reaction for 5 days in a drying oven at 160 ℃ under the condition that O is 6:3:40:1: 800.

After the hydrothermal reaction, solid-liquid separation is carried out by using a centrifugal machine, and the solid product is dried in an oven at 75 ℃ for 12 hours after being washed, so as to obtain the product which is marked as H4.

The crystallinity and Si/Al of the product H4 were measured and are shown in Table 1.

Curve 4 in FIG. 1 is the X-ray powder diffraction pattern of H4, and by comparison with the standard diffraction pattern published by the International molecular sieves society, H4 is a molecular sieve having the TON structure.

FIG. 5 is a scanning electron micrograph of the TON type molecular sieve prepared in example 4, wherein the particle size of H4 was 4 μm as observed by a scanning electron microscope.

Example 5

0.3g of sodium metaaluminate, 0.527g of sodium hydroxide and 4.8m of L parts of distilled water were charged into a reaction vessel, stirred uniformly under a closed condition at room temperature, added with 34.7m of L mass% of 12% aqueous tetramethylenebis (1-methylimidazole) hydroxide solution, and then added with 29.7g of silica sol (of which SiO is contained)₂Mass 11.8g), stirring under sealed condition at room temperature to form uniform gel with effective component composition and molar ratio of Na₂O:ROH:SiO₂:Al₂O₃:H₂And (3) carrying out static hydrothermal reaction for 4 days at 180 ℃ in an oven, wherein O is 5:5:60:1: 900.

After the hydrothermal reaction, solid-liquid separation was performed using a centrifuge, and the solid product was dried in an oven at 100 ℃ for 12 hours after washing to obtain a product, which was designated as H5.

The crystallinity and Si/Al of the product H5 were measured and are shown in Table 1.

Curve 5 in FIG. 1 is the X-ray powder diffraction pattern of H5, and by comparison with the standard diffraction pattern published by the International molecular sieves Association, H5 is a molecular sieve having the HEU structure.

FIG. 6 is a scanning electron micrograph of the TON type molecular sieve prepared in example 5, wherein the particle size of H5 was 3.2 μm as observed by a scanning electron microscope.

Comparative example 1

According to the literature "Wang Y, Wang X, Wu Q, et al.Seed-directed and organotemplate-free synthesis of TON zeolite[J]Catalysis Today,2014,226:103-108 ", discloses a process for the synthesis of TON-type molecular sieves by the seeding method, wherein 0.096g of crystalline alumina, 3g of ethyl orthosilicate, 0.18g of potassium hydroxide and 11.5m L of water are mixed in a molar ratio of Al₂O₃:SiO₂:K₂O:H₂Mixing O-1: 100:95.0:4500 to obtain precursor, adding 0.043g of powdered TON type molecular sieve (from Dalianchun) as seed crystal containing Al₂O₃The amount of the substance(s) accounts for Al in the whole precursor₂O₃0.9% by mole, was subjected to dynamic hydrothermal reaction at 140 ℃ for 48 hours (45rpm) in a high-temperature reaction vessel, washed with water, and dried at 100 ℃ for 4 hours to give a product designated as H6.

The crystallinity and Si/Al of the product H6 were determined and are shown in Table 1.

Curve 6 in FIG. 1 is the X-ray powder diffraction pattern of H6, and by comparison with the standard diffraction pattern published by the International society for molecular sieves, H6 is a molecular sieve having the TON structure.

FIG. 7 is a scanning electron micrograph of the TON type molecular sieve prepared in comparative example 1, wherein the particle size of H6 was 500nm as observed by a scanning electron microscope.

Comparative example 2

Grinding a commercially available TON type molecular sieve (purchased from Dalianzhuoran) synthesized by a traditional method into powder, dispersing in distilled water, stirring for 4H, performing solid-liquid separation by using a centrifugal machine, and drying a solid product in an oven at 100 ℃ for 4H to obtain a product, which is recorded as H7.

The crystallinity and Si/Al of the product H7 were determined and are shown in Table 1.

Curve 7 in FIG. 1 is the X-ray powder diffraction pattern of H7, and by comparison with the standard diffraction pattern published by the International molecular sieves society, H7 is a molecular sieve having the TON structure.

Comparative example 3

In contrast to example 1, in comparative example 3, in which no aqueous tetramethylene hydroxide bis (1-methylimidazole) hydroxide solution was added, the procedure was the same as in example 3, and a comparative product was prepared and designated as H8.

The crystallinity and Si/Al of the product H8 were determined and are shown in Table 1.

Curve 8 in fig. 1 is the X-ray diffraction pattern of H8, from which curve 8 it can be determined that H8 is not a zeolitic molecular sieve having a TON structure.

TABLE 1 Performance results for TON-type zeolite molecular sieves prepared in examples 1-5 and comparative examples 1-3

	H1	H2	H3	H4	H5	H6	H7	H8
									Si/Al	17.2	22.5	20.1	19.8	21.9	44.8	35.0	-

From the analysis of the experimental data in table 1, it can be seen that the TON-type zeolite molecular sieve prepared by the present invention has the advantage of low silicon-aluminum ratio, which is 17.2-22.5, compared with the TON-type zeolite molecular sieve prepared by the prior art.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of TON type zeolite molecular sieve is characterized by comprising the following steps:

2. The method according to claim 1, wherein the mass of the silicon source is calculated as silicon dioxide, the mass of the aluminum source is calculated as aluminum oxide, the mass of the inorganic base is calculated as sodium oxide, and the gel comprises the following components in molar ratio:

3. The method according to claim 2, wherein the gel comprises the following components in the following molar ratios:

Na₂O:ROH:SiO₂:Al₂O₃:H₂O＝5～6:2～5:40～60:1:800～900。

4. the method according to claim 3, wherein the gel comprises the following components in the following molar ratios:

Na₂O:ROH:SiO₂:Al₂O₃:H₂O＝5.86:2.72:49.3:1.00:857。

5. the method according to claim 1, wherein the tetramethylene hydroxide bis- (1-methylimidazole) is added in the form of an aqueous tetramethylene hydroxide bis- (1-methylimidazole) solution having a mass concentration of 10 to 17%.

6. The method according to claim 1, wherein the temperature of the static hydrothermal reaction is 150 to 200 ℃ and the time of the static hydrothermal reaction is 3 to 10 days.

7. The TON type zeolite molecular sieve prepared by the preparation method of any one of claims 1 to 6, wherein the TON type zeolite molecular sieve has a silicon-aluminum ratio of 17 to 23 and a particle size of 2.5 to 5.5 μm.