RU2735849C1 - Method of producing aluminosilicate zeolite with mtw structure (zsm-12 type) - Google Patents

Abstract

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to a method of producing an aluminosilicate zeolite with a MTW structure of the ZSM-12 type. Method comprises mixing solutions containing an aluminum compound, a silicon compound, templates selected from salts of N1,N4-bis(2-hydroxyethyl)-N1,N1,N4,N4-tetramethylbutane-1,4-diammonium, N1,N6-bis(2-hydroxyethyl)-N1,N1,N6,N6-tetramethylhexane-1,6-diammonium, N1,N8-bis(2-hydroxyethyl)-N1,N1,N8,N8-tetramethyloctane-1,8-diammonium, and an alkali metal compound to obtain a reaction mixture, crystallizing the obtained mixture for 4–5 days at temperature of 145–155 °C, recovering the formed crystalline product, washing with distilled water until filtrate pH reaches 9.0–9.5, drying to constant weight and annealing at 500±10 °C for 8–12 hours, ion exchange reaction with ammonium salt solution, recovery of formed crystalline product, washing with distilled water till pH of filtrate is equal to 7.8–8.3, dried to constant weight and product is annealed at 450±10 °C for 4–7 hours.

EFFECT: invention increases content of mesopore aluminosilicate zeolite of ZSM-12 type to 10–35 % of total number of pores with degree of crystallinity of more than 90 % and content of sodium oxide of not more than 0_05 %.

7 cl, 1 dwg, 6 ex

Description

Technology area

The present invention describes a method for preparing aluminosilicate zeolite with the MTW structure (ZSM-12 type) containing mesopores using templates based on quaternary organic polymethylenediammonium salts containing alkyl or alkyl-hydroxyl, or alkyl-carbonyl, or alkyl-carboxyl, or combinations thereof as groups at nitrogen atoms.

State of the art

Zeolites are widely used in the petrochemical and gas industries as adsorbents, catalysts, molecular sieves, ion exchange materials, etc. due to stable physical and mechanical properties, relative low cost of production and structural features of the porous structure. Due to structural limitations, the use of natural, natural zeolites is limited to only a few individual processes. In this connection, artificial, synthetically synthesized zeolites with desired structural properties are becoming increasingly important.

An example of such materials is zeolite with the MTW structure (ZSM-12 type), which forms a one-dimensional system of pores with a size of 0.56 × 0.61 nm, consisting of 12-membered rings. Such a structure of the porous system of MTW zeolite allows it to be used in catalytic processes for the conversion of hydrocarbons, for example, increasing the concentration of p-xylene from a mixture of its isomers or in the selective alkylation or trans-alkylation of aromatic hydrocarbons.

Varying the conditions for the synthesis of zeolites of the ZSM-12 type makes it possible to obtain materials with specified properties - morphology, composition, pore volume and size, surface area, etc. The prior art knows zeolites of the ZSM-12 type and methods for their synthesis by mixing a silicon compound, an aluminum compound, an alkali, a template and a solvent in predetermined sequences, component ratios and conditions [EP-18089 A1, published 03.20.1980, US 4391785, published 05.07 .1983, US 4552739, published 11/12/1985].

In many processes in the petrochemical industry, an important property of the materials on the basis of which catalysts are created is the presence of mesoporous channels in them, facilitating the diffusion of substrates to the active centers of the catalyst and thereby increasing its activity. As a microporous material, zeolite ZSM-12 does not contain mesoporous channels in its structure. For the formation of mesoporous cavities in the structure of zeolites, approaches based on the treatment of already synthesized zeolite of the ZSM-12 type with various reagents [L. Dimitrov, M. Mihaylov, K. Hadjiivanov, V. Mavrodinova "Catalytic properties and acidity of ZSM-12 zeolite with different textures", Microporous and Mesoporous Materials 143 (2011), 291-301]. The disadvantage of this approach is the low degree of process control, which is expressed in the low reproducibility of results (pore sizes in zeolites) and the need to select processing conditions depending on the size and shape of the zeolite crystals. In addition, in the course of this treatment, aluminum ions, which are responsible for the catalytic activity of the zeolite, are often washed out from the zeolite.

From the prior art, methods for the formation of mesopores in the structure of a zeolite of the ZSM-12 type are known based on the use of special additives in the course of the zeolite synthesis, which are subsequently removed by annealing at elevated temperatures. These additives include large particles such as carbon black or polymer particles. However, the disadvantages of using these additives include the complexity of the formation of a homogeneous gel when obtaining the reaction mixture and, as a consequence, the ordered porous structure of zeolites.

A more effective approach is the use of templates-macromolecules, that is, templates of larger molecules. On the one hand, they contribute to the formation of a zeolite with a given structure, and on the other hand, they allow obtaining a reaction mixture that is uniform in composition.

From the prior art, a method for the synthesis of zeolite of the ZSM-12 type is known, which is carried out in the presence of a template of the composition [(CH ₃ ) ₃ N ⁺ (CH ₂ ) ₁₀ N ⁺ (CH ₃ ) ₃ ] Br ^- ₂ , while crystallization is carried out at a temperature from 150 to 180 ° C for 4-10 days while stirring the reaction mixture (US 5192521, published 09.05.1993).

A known method for the synthesis of zeolite type ZSM-12 in the presence of a template containing a diammonium cation composition [(C ₂ H ₅ ) (CH ₃ ) ₂ N ⁺ (CH ₂ ) _4-6 N ⁺ (CH ₃ ) ₂ (C ₂ H ₅ ) ] ⁺ (US 4585639 A, published 04/29/1986). The conditions for obtaining the product assume a fairly wide temperature and time intervals (crystallization temperature from 80 to 200 ° C, crystallization time from 12 hours to 30 days), depending on the composition of the reaction medium. The recommended synthesis conditions imply carrying out the process at a temperature of 100 to 180 ° C for 1-7 days.

A known method of synthesizing zeolite of the ZSM-12 type using as a template polymethylene diammonium salts based on triethylenediamine (DABCO) composition DABCO- (CH ₂ ) _n -DABCO, where n = 4, 5, 6 and 10 in the case of US patent 4482531 or 4-10 in the case of US patent 4559213 (US 4482531 published 11/13/1984; US 4559213 published 12/17/1985). In both cases, the reaction mixture is kept for 6-150 days at a temperature of 80 to 180 ° C, preferably for 5-30 days at a temperature of 150-170 ° C, for the crystallization of a zeolite of the ZSM-12 type.

Data on the textural characteristics of materials that allow us to estimate the proportion of mesopores in the structure are not given in the above documents.

A known method for the synthesis of a zeolite of the ZSM-12 type using as a template polymethylene diammonium salts based on methylpiperidine and / or methylpyrrolidine of the composition [A- (CH ₂ ) _n -A] B ₂ , where A are molecules of methylpiperidine and / or methylpyrrolidine, B - anion Br ^- , n = 4-6 (CN 107032368 A, published on August 11, 2017). The reaction mixture containing the specified template, a silicon compound, an aluminum compound, an alkali and water is kept in an autoclave for 70-100 hours at a temperature of 160 ° C. The resulting product is a star-shaped agglomerates of nanosized crystals of zeolite ZSM-12 with an elongated shape. Data on the quantitative content of meso- and macropores in the resulting product are not given. But the curves of adsorption-desorption of nitrogen are given, which make it possible to assert the presence of meso- and macropores in the synthesis product by the presence of hysteresis between them. Disadvantages of the method: large size of the resulting agglomerates - up to 10 microns. Despite the presence of meso- and macropores in the structure of the zeolite, this fact can negatively affect the transport of substrates to active sites in the zeolite during catalytic reactions and reduce the overall activity of the catalyst.

The closest is a method for synthesizing a highly crystalline zeolite of the ZSM-12 type using cyclic diammonium salts based on dimethylethanolamine as a template (WO 201087633, published 05.08.2010). The general formula of this template is [(CH ₃ ) ₂ N ⁺ R ₁ R ₂ N ⁺ (CH ₃ ) ₂ ] X ₂ , where R ₁ , R ₂ are fragments of molecules based on alkyl-, alkenyl-, aryl-groups, X - halogen ions (Cl ^- , Br ^- , etc.), and / or hydroxide ions OH ^- . Crystallization of the reaction mixture during the preparation of zeolite is carried out for 3 days at a temperature of 170 ° C. However, according to the data of low-temperature adsorption-desorption of nitrogen, the material contains mesopores with a size of 10-40 nm, the total pore volume is 0.4 cm ³ / g.

The technical problem solved by the claimed invention is to obtain a zeolite of the ZSM-12 type with an increased proportion of mesopores in the finished product up to 10-35% of the total number of pores.

Disclosure of invention

The technical result of the proposed method is to increase the proportion of mesopores in the finished product up to 10-35% of the total number of pores in the production of aluminosilicate zeolite.

The technical result is achieved by implementing a method for producing zeolite of the ZSM-12 type with the MTW structure, characterized in that

• mix an aqueous solution, characterized by pH = 11.5-13.5, containing an aluminum compound and a template, which is used as a compound of general formula (I), and an aqueous solution containing a silicon compound, until a gel-like mass is obtained, while the mixture of solutions is prepared based on compliance the following molar ratios of the components used: template / Si = 0.05-0.3, Si / Al = 25-150, H ₂ O / Si = 0.5-25;

where n is from 3 to 10; from R ₁ to R ₆ - alkyl or hydroxyl-alkyl, or aryl-alkyl, or carbonyl-alkyl, or carboxyl-alkyl groups, or combinations thereof with the number of carbon atoms from 2 to 7, X is an anion serving to balance the charge of the compound selected from a halide ion or hydroxide ion, or a combination thereof.

• carry out the crystallization of the resulting mass with the release of a crystalline product, followed by washing with distilled water, drying to constant weight and annealing at 500 ± 10 ° C for 8-12 hours;

• then the resulting product is subjected to an ion exchange reaction with an aqueous solution of ammonium salt, followed by isolation of the product, washing it with distilled water, drying to constant weight and calcining at 450 ± 10 ° C for 4-7 hours.

It is preferable to use solutions of colloidal silicon dioxide or tetraethoxysilane as a silicon compound, as an aluminum compound - aluminum sulphate octadecahydrate or aluminum nitrate nonahydrate, or aluminum isopropoxide, and as a template salt N ¹ , N ⁴ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁴ , N ^4- tetramethylbutane-1,4-diammonium or N ¹ , N ⁶ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁶ , N ⁶ -tetramethylhexane-1,6-diammonium , or N ¹ , N ⁸ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁸ , N ⁸ -tetramethyloctane-1,8-diammonium.

It is preferable to carry out crystallization for 4-5 days at a temperature of 145-155 ° C, while the separation of the crystalline product is carried out under reduced pressure on a porous glass filter, namely, filtration at a pressure of 2 to 101.325 kPa on a class 3 filter. Rinsing with distilled water the product obtained after crystallization is preferably carried out until the filtrate pH reaches 9.0-9.5, and the resulting product is dried at a temperature of 80-110 ° C to constant weight, followed by annealing at 500 ± 10 ° C for 8-12 hours with a heating step of 1 ° S / min.

To carry out ion exchange, it is preferable to use ammonium chloride or ammonium nitrate, or ammonium acetate as the ammonium salt, while the concentration of the aqueous solution of the ammonium salt is at least 0.5 M and taken in at least 20-fold excess by weight relative to the weight of the crystalline product ... The product obtained after ion exchange is washed with distilled water until the filtrate pH reaches 7.8-8.3, followed by calcining at 450 ± 10 ° C for 4-7 hours with a heating step of 1 ° C / min.

Using the above reagents and varying the synthesis conditions - crystallization time, temperature, Si / Al molar ratio - it is possible to synthesize aluminosilicate zeolites of the ZSM-12 type with different textural properties, namely, the synthesis of microporous material with a fraction of mesopores (10-35%) at a degree crystallinity more than 90% and the content of sodium oxide in the finished product is not more than 0.05%.

The reagents used for the synthesis of the template were mixed in molar stoichiometric ratios; therefore, the synthesized templates with alkyl or alkyl-hydroxyl, or alkyl-carbonyl, or alkyl-carboxyl, or their combination as groups at nitrogen atoms with the number of carbon atoms from 2 to 7 will contribute mesoporosity to the material.

Brief Description of Drawings

FIG. 1 shows the X-ray diffraction spectra for aluminosilicate crystalline samples of zeolites of the ZSM-12 type in the H-form, where A) a zeolite of the ZSM-12 type synthesized using N ¹ , N ⁴ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁴ , N ⁴ -tetramethylbutane-1,4-diammonium, example 1; B) a zeolite of the ZSM-12 type, synthesized using N ¹ , N ⁶ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁶ , N ⁶ -tetramethylhexane-1,6-diammonium, example 2; B) zeolite of the ZSM-12 type synthesized using N ¹ , N ⁸ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁸ , N ⁸ -tetramethyloctane-1,4-diammonium, example 3.

Implementation of the invention

The reagents used for the synthesis of zeolite and templates are commercially available. All procedures were carried out in the range from 18 to 25 ° C.

Factors affecting the properties and synthesis of aluminosilicate zeolites of the ZSM-12 type include the temperature and time of crystallization, the nature of the reagents used (aluminum compound and silicon compound, template, solvent) and their concentrations, the presence or absence of mixing (synthesis under static conditions) , pH and holding time of the reaction mixture before crystallization. Crystallization is carried out in steel autoclaves equipped with Teflon liners in the temperature range 145-155 ° C for 4-5 days under conditions of hydrothermal synthesis, from a reaction gel obtained by mixing solutions containing: (1) at least one compound of silicon oxide ; (2) at least one alumina compound; (3) at least one template. PH control is carried out by introducing the required amount of alkali. The optimum pH value is from 11.5 to 13.5. As the silicon compound, a colloidal solution of silicon dioxide or tetraethoxysilane can be used; as the aluminum compound, aluminum sulfate octadecahydrate or aluminum nitrate nonahydrate or aluminum isopropoxide can be used. For pH control, sodium hydroxide or potassium hydroxide can be used in dry form or in the form of aqueous solutions with a concentration of at least 0.5M. The composition of the reaction mixture from which the zeolite of the ZSM-12 type is synthesized, in terms of molar ratios, is given below:

The method for producing an aluminosilicate zeolite with the MTW structure (ZSM-12 type) described by the present invention includes the following steps:

1. The reaction mixture was prepared, which mix the aqueous solution of any concentration containing the aluminum compound and the template - (Solution 1), then add dry or aqueous alkali [H ₂ O:: 8.8: 1 template: Al = (200 ÷ 400)] alkali solution to achieve the required pH from 11.5 to 13.5 - [H ₂ O: Al: template: OH = (200 ÷ 450): 1: 8.8: 10.4] (solution 2), prepare an aqueous solution of arbitrary concentration containing a silicon compound - [ Si: H ₂ O = 1: (6 ÷ 15)] (solution 3). Then add solution 2 dropwise to solution 3. Gently mix the resulting suspension-gel mass until homogeneity (gel) is achieved. Leave for 1.0-1.5 hours at room temperature to form the primary structure of the gel;

2.Crystallize the resulting gel in a steel autoclave equipped with a Teflon liner under hydrothermal conditions: for which purpose move the gel prepared in the previous paragraph into a Teflon liner, place the liner in the autoclave and seal the latter, thermostat the autoclave to temperature from the range of 145-155 ° C for 4-5 days;

3. isolate the crystalline product by filtration under reduced pressure (from 2 to 101.325 kPa) on a glass porous filter of class 3, rinse with distilled water until the filtrate reaches pH 9.0-9.5 and dry at 80-110 ° C until constant weight;

4. remove the template by annealing, starting at room temperature, then with a heating step of 1 ° C / min to 500 ± 10 ° C, then keep it at this temperature for 8-12 hours;

5. to carry out ion exchange with an aqueous solution of ammonium salt to obtain NH ₄ -form of zeolite;

6. isolate the crystalline product by filtration under reduced pressure (from 2 to 101.325 kPa) on a porous glass filter of class 3, rinse with distilled water until the filtrate reaches pH 7.8-8.3, dry at 80-110 ° C until constant weight;

7.Ice the product in a muffle furnace (replacing NH _4- form with H-form), starting at room temperature, then with a heating step of 1 ° C / min to 450 ± 10 ° C, then hold it at this temperature for 4-7 hours ...

To obtain the H-form of the synthesized zeolite, ion exchange is carried out using aqueous solutions of various cationic ammonium salts, for example, ammonium chloride or ammonium nitrate, or ammonium acetate. Examples of ion exchange methods are given in many patents, for example, US 3140249 A, published 07.07.1964; US 3140251 A, published 07.07.1964; US 3140253 A, published 07.07.1964.

The synthesized products were characterized by X-ray diffraction analysis on a Rigaku Rotaflex D / max-RC instrument, elemental analysis on a Thermo ARL PERFORM'X instrument, porosity was determined on a Gemini VII 2390 (V1.02t) instrument (Micromeritics) according to standard operating procedures. The results of analyzes of the synthesis products are shown in each example.

The claimed method synthesized an aluminosilicate product with a chemical composition in terms of oxides:

0.1 ± 0.06M _{2 / n} O: Al ₂ O ₃ : ySiO ₂ : zH ₂ O

where M is at least one cation with valence n; y is between 50 and 300; a z-value between 0.5 and 25.

Below is a more detailed description of the claimed invention. The present invention can be subject to various changes and modifications, which will be understood by a person skilled in the art based on reading this description. Such changes do not limit the scope of the claim.

Example 1

In the first glass, a solution was prepared consisting of 12.6 g of distilled water, 0.9 g of aluminum nanodecahydrate and 8.4 g of bromide N ¹ , N ⁴ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁴ , N ⁴ -tetramethylbutane-1, 4-diammonium (solution 1). Then, while stirring, 1.0 g of sodium hydroxide was added to solution 1 - the solution was stirred until the solid reagents dissolved (solution 2). In the second glass, a solution was prepared consisting of 25.2 g of a 40% (wt.) Colloidal solution of LUDOX AS-40 silicon dioxide and 10.1 g of water - mixed until homogeneous (solution 3). The second solution was added dropwise to the third and mixed until a homogeneous gelatinous mass was formed. Gel composition:

10Na ₂ O: 1Al ₂ O ₃ : 140SiO ₂ : 17.7 template: 99.3H ₂ O

The resulting gel was transferred to a Teflon insert of the autoclave, the latter was sealed and thermostated at 155 ° C for 5 days. The synthesized product was filtered under reduced pressure (from 2 to 101.325 kPa) on a glass porous filter of class 3, washed with distilled water until the filtrate pH reached 9.2, transferred the sample from a Buchner funnel into a Petri dish, dried in an oven for 2 h at 80 ° C, 2 hours at 90 ° C, 3 hours at 100 ° C and 3 hours at 110 ° C; calcined in a muffle furnace, starting at room temperature, then with a heating step of 1 ° C / min to 500 ° C, then at this temperature for 10 hours.

The ion exchange was carried out with a 1.0 M aqueous solution of ammonium nitrate for 17 hours. The buffer mixture was filtered under reduced pressure (from 2 to 101.325 kPa) on a glass porous filter of class 3, washed with distilled water until the filtrate pH reached 8.3, dried in an oven for 2 h at 80 ° C, 2 h at 90 ° C, 3 hours at 100 ° C and 3 hours at 110 ° C; calcined in a muffle furnace, starting at room temperature, then with a heating step of 1 ° C / min to 450 ° C, then at this temperature for 6 hours.

.According to the analyzes, the product is an aluminosilicate zeolite of the ZSM-12 type with a degree of crystallinity of 90%; sodium oxide content 0.045 wt. %; the content of aluminum oxide 1.62 wt. %; the proportion of mesopores is 18.3%; surface area 184 m ² / g; mesopore volume 0.06 cm ³ / g; pore size 45.5

...

Example 2

In the first glass, a solution was prepared consisting of 12.6 g of distilled water, 0.8 g of aluminum sulphate decahydrate and 8.95 g of bromide N ¹ , N ⁶ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁶ , N ⁶ -tetramethylhexane-1, 6-diammonium (solution 1). Then, while stirring, 1.0 g of sodium hydroxide was added to solution 1 - the solution was stirred until the solid reagents dissolved (solution 2). In the second glass, a solution was prepared, consisting of 25.2 g of a 40% (wt.) Colloidal solution of LUDOX HS-40 silicon dioxide and 10.1 g of water - mixed until homogeneous (solution 3). The second solution was added dropwise to the third and mixed until a homogeneous gelatinous mass was formed. Gel composition:

10Na ₂ O: 1Al ₂ O ₃ : 140SiO ₂ : 17.7 temp .: 99.3H ₂ O

The resulting gel was transferred to a Teflon insert of the autoclave, the latter was sealed and thermostated at 155 ° C for 4 days. The resulting product was filtered under reduced pressure (from 2 to 101.325 kPa) on a glass porous filter of class 3, washed with distilled water until the pH of the filtrate reached 9.0, transferred the sample from a Buchner funnel to a Petri dish, dried in an oven for 2 h at 80 ° C, 2 hours at 90 ° C, 2 hours at 100 ° C and 2 hours at 110 ° C; calcined in a muffle furnace, starting at room temperature, then with a heating step of 1 ° C / min to 510 ° C, then at this temperature for 8 hours.

The ion exchange was carried out with a 1.2M aqueous solution of ammonium chloride for 13 hours. The buffer mixture was filtered under reduced pressure (from 2 to 101.325 kPa) on a porous glass filter of class 3, washed with distilled water until the filtrate pH reached 8.0, dried in an oven for 2 h at 80 ° C, 2 h at 90 ° C, 2 hours at 100 ° C and 2 hours at 110 ° C; calcined in a muffle furnace, starting at room temperature, then with a heating step of 1 ° C / min to 460 ° C, then at this temperature for 5 hours.

.According to the analysis data, the product is an aluminosilicate zeolite of the ZSM-12 type with a degree of crystallinity of 95%; sodium oxide content 0.038 wt. %; aluminum oxide content 1.65 wt. %; the proportion of mesopores is 20.1%; surface area 274 m ² / g; mesopore volume 0.08 cm ³ / g; pore size 51.5

...

Example 3

In the first glass, a solution was prepared consisting of 12.6 g of distilled water, 0.5 g of aluminum isopropoxide and 9.6 g of bromide N ¹ , N ⁸ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁸ , N ⁸ -tetramethyloctane-1, 8-diammonium (solution 1). Then, while stirring, 1.0 g of sodium hydroxide was added to solution 1 - the solution was stirred until the solid reagents dissolved (solution 2). In the second glass, 25.3 g of water was added to 35 g of tetraethoxysilane and mixed until homogeneous (solution 3). The second solution was added dropwise to the third and mixed until a homogeneous gelatinous mass was formed. Gel composition:

10Na ₂ O: 1Al ₂ O ₃ : 140SiO ₂ : 17.7 template: 99.3H ₂ O

The resulting gel was transferred to a Teflon insert of the autoclave, the latter was sealed and thermostated at 145 ° C for 6 days. The resulting product was filtered under reduced pressure (from 2 to 101.325 kPa) on a glass porous filter of class 3, washed with distilled water until the pH of the filtrate reached 9.1, the sample was transferred from a Buchner funnel to a Petri dish, dried in an oven for 1 h at 80 ° C, 3 hours at 90 ° C, 5 hours at 100 ° C and 1 hour at 110 ° C; calcined in a muffle furnace, starting at room temperature, then with a heating step of 1 ° C / min to 490 ° C, then at this temperature for 12 hours.

Ion exchange was carried out with a 1.3 M aqueous solution of ammonium acetate for 11 hours. The buffer mixture was filtered under reduced pressure (from 2 to 101.325 kPa) on a glass porous filter of class 3, washed with distilled water until the filtrate pH reached 8.1, dried in an oven for 1 h at 80 ° C, 3 h at 90 ° C, 5 hours at 100 ° C and 1 hour at 110 ° C; calcined in a muffle furnace, starting at room temperature, then with a heating step of 1 ° C / min to 440 ° C, then at this temperature for 7 hours.

.According to the analysis, the product is an aluminosilicate zeolite of the ZSM-12 type with a degree of crystallinity of 98%; sodium oxide content 0.022 wt. %; aluminum oxide content 1.68 wt. %; the proportion of mesopores is 22%; surface area 364 m ² / g; mesopore volume 0.1 cm ³ / g; pore size 58.3

...

Example 4. Synthesis of bromide N ¹ , N ⁴ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁴ , N ⁴ -tetramethylbutane-1,4-diammonium

In a flask with a capacity of 50 ml, equipped with a magnetic stirrer armature, were placed 14.92 g of dimethylethanolamine and 18.08 g of 1,4-dibromobutane. The mixture was stirred for 12 hours, which was then evaporated under reduced pressure (from 2 to 101.325 kPa) on a rotary evaporator. The resulting powder was a colorless amorphous product. Product purity was proved by NMR spectroscopy on nuclei ¹ N.

Example 5. Synthesis of bromide N ¹ , N ⁶ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁶ , N ⁶ -tetramethylhexane-1,6-diammonium

In a 50 ml flask equipped with a magnetic stirrer armature, 11.6 g of dimethylethanolamine and 15.86 g of 1,6-dibromohexane were placed. The mixture was stirred for 12 hours, which was then evaporated under reduced pressure (from 2 to 101.325 kPa) on a rotary evaporator. The resulting powder was a colorless amorphous product. Product purity was proved by NMR spectroscopy on nuclei ¹ N.

Example 6. Synthesis of bromide N ¹ , N ⁸ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁸ , N ⁸ -tetramethyloctane-1,8-diammonium

In a 50 ml flask equipped with a magnetic stirrer armature, 9.68 g of dimethylethanolamine and 14.77 g of 1,8-dibromoctane were placed. The mixture was stirred for 12 hours, which was then evaporated under reduced pressure (from 2 to 101.325 kPa) on a rotary evaporator. The resulting powder was a colorless amorphous product. Product purity was proved by NMR spectroscopy on nuclei ¹ N.

The proposed method for increasing the volume of mesopores in a zeolite of the ZSM-12 type is based on the use of quaternary organic polymethylenediammonium salts containing alkyl or alkyl-hydroxyl, or alkyl-carbonyl, or alkyl-carboxyl, or their combinations as groups at nitrogen atoms. These can be compounds with the general formula R ₁ R ₂ R ₃ -N ⁺ - (CH ₂ ) _n -N ⁺ -R ₄ R ₅ R ₆ , where n is from 3 to 10; from R ₁ to R ₆ - alkyl or hydroxyl-alkyl, or aryl-alkyl, carbonyl-alkyl, or carboxyl-alkyl groups, or their combinations with the number of carbon atoms from 2 to 7. Compared with standard quaternary alkylammonium salts, template molecules of this type have a large size, allowing them to occupy more volume in the pores of the zeolite during the process of structure formation during crystallization from the reaction mixture.

Claims (9)

1. A method of obtaining zeolite of the ZSM-12 type with the MTW structure, characterized in that mix an aqueous solution containing an aluminum compound, a silicon compound and a template selected from salts N ¹ , N ⁴ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁴ , N ⁴ -tetramethylbutane-1,4-diammonium, N ¹ , N ⁶ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁶ , N ⁶ -tetramethylhexane-1,6-diammonium, N ¹ , N ⁸ -bis (2-hydroxyethyl) -N ¹ , N ¹ , N ⁸ , N ⁸ -tetramethyloctane-1,8-diammonium, and an alkali metal compound to obtain a reaction mixture having the following molar ratio of components: 10Na ₂ O: 1Al ₂ O ₃ : 140SiO ₂ : 17.7 template: 99.3H ₂ O and The pH of the mixture is 11.5-13.5, then crystallization of the resulting mixture is carried out for 4-5 days at a temperature of 145-155 ° C, the resulting crystalline product is isolated, washed with distilled water until the pH of the filtrate is 9.0-9.5, dried to constant weight and annealed at 500 ± 10 ° C for 8-12 hours, after which an ion exchange reaction with a solution of ammonium salt is carried out, the formed crystalline product is isolated, washed with distilled water until reaching the pH of the filtrate is 7.8-8.3, dried to constant weight and the product is calcined at 450 ± 10 ° C for 4-7 hours; In this case, solutions of colloidal silicon dioxide or tetraethoxysilane are used as the silicon compound, and aluminum sulfate octadecahydrate, or aluminum nitrate nanohydrate, or aluminum isopropoxide, are used as the aluminum compound. 2. The method according to claim 1, characterized in that the separation of the crystalline product is carried out under reduced pressure on a porous glass filter. 3. The method according to claim 2, characterized in that the filtration is carried out at a pressure of 2 to 101.325 kPa on a class 3 filter. 4. The method according to claim 1, characterized in that drying is carried out at a temperature of 80-110 ° C to constant weight. 5. The method according to claim 1, characterized in that the calcination and annealing of the product is carried out with a heating step of 1 ° C / min. 6. The method according to claim 1, characterized in that ammonium chloride or ammonium nitrate or ammonium acetate is used as the ammonium salt for ion exchange. 7. The method according to claim 1, characterized in that an aqueous solution of an ammonium salt with a concentration of at least 0.5 M. is used for ion exchange.

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