RU2276656C2 - Method of production of zeolite - Google Patents

Abstract

FIELD: chemical industry; methods of production of zeolite.

SUBSTANCE: the invention is pertaining to chemical industry, in particular, to the method of production of zeolite. The method of production of ZSM-5 type zeolite provides for mixing in water of the initial components: silicon, additional members, alkali and seeding agents; realization of the crystallization, the ion exchange, separation of the produced mashes, modifications, granulation, drying, annealing; withdrawal of the main components from the waste waters. The method differs by the fact, that as the source of silicon or its part they apply silica gel extracted from the own local production process as a result of settling from the alkaline waste water outflow by the acidic flow. Then the alkaline waters after filtration and washing of Na-form zeolite are neutralized by the acid waters containing the additional components and produced at the stage of the filtration after the ion exchange. The method allows to use the waste waters of the own production of ZSM-5-type zeolite for production of silica gel, recoverable during the production in the capacity of a source component.

EFFECT: the invention ensures production of ZSM-5-type zeolite and silica gel from the waste waters of the own production of ZSM-5-type zeolite.

17 cl, 6 ex

Description

The invention relates to a method for producing ZSM-5 zeolite, which can be used as a catalyst for the conversion of hydrocarbons by acid-base or redox catalysis.

The catalytic conversion of hydrocarbons to zeolites first appeared after the creation of synthetic type Y zeolite and was further developed with the advent of ZSM-5 zeolite (US Pat. US 3702886, C 01 B 33/28, 1972). According to this patent, zeolite is synthesized from mixtures having a wide range of compositions, in the presence of tetrapropylammonium hydroxide, followed by drying, calcination, ion exchange of zeolite in solutions of hydrochloric acid or ammonium chloride, or by modification with salts of rare earth elements, calcium, ammonium, sodium or silver. However, this catalyst has a high cost due to the use of an expensive organic component - tetrapropylammonium hydroxide.

To reduce the cost of zeolite synthesis is carried out with cheaper organic additives - alcohols (US Pat. GB 1553209, 01 B 33/28, 1979). The crystallization of the zeolite can also be carried out in the presence of amines, amino alcohols, ketones or alcohols (Pat. SU 1610777, 01 B 33/34, 1988). However, zeolites obtained by these methods have low catalytic characteristics in acid-base catalysis reactions, for example, their stability in the reaction of converting methanol to a mixture in hydrocarbons does not exceed 20-100 hours of continuous operation.

To reduce the cost and simplify the methods of producing zeolite catalysts having good performance, for example, high catalytic stability, various methods have been used:

- zeolite is synthesized in the presence of alcohol, iron and seed (SU 1111418, C 01 B 33/26, B 01 J 29/06, 1982);

- two isomorphically substituting elements are already introduced into the zeolite (RU 1262786, B 01 J 37/00, 29/34, 1984);

- apply the seeds that have passed grinding in the presence of water or saline solutions (SU 1686794, C 01 B 33/34, 1987; SU 2056354, C 01 B 39/00, 1993);

- carry out the grinding of silica gel (RU 2174952, C 01 B 39/38, 2000);

- spend the ion exchange of the sodium form of the zeolite with stirring and boiling in an acid solution (SU 1615941, B 01 J 29/28, C 01 B 33/34, 1988);

- the zeolite is modified by the addition of a compound of at least one of the metals selected from the series: zinc, gallium, nickel, cobalt, molybdenum, tungsten, rhenium, a platinum group metal, rare earth elements, which are introduced by impregnation, ion exchange, deposition from the gas phase, or by mechanical mixing (RU 2188225, C 10 G 35/095, 2001; RU 2208626, C 10 G 69/02, 2001).

These techniques can increase the catalytic stability in the methanol conversion reaction to 500-700 hours of continuous operation. But these methods protect specific stages of the preparation of the catalyst and do not guarantee high catalytic performance of the final product with a slight modification of the individual stages.

A known method in which the synthesis of zeolite is carried out from a mixture prepared by mixing in water sources of silicon, aluminum, alkali, one or more elements selected from the series: iron, gallium or boron in the presence or absence of seed, or butyl alcohol. The resulting zeolite is filtered and washed from excess alkali. Then the wet powder is treated at a temperature of 80-100 ° C with a solution of mineral acid, followed by filtration and washing. Then, at 70-100 ° C, a structurally selective exchange of zeolite is carried out, in which the wet powder interacts with a solution of elements selected from the series: iron, aluminum, chromium or rare earth elements in the form of complexes with sulfosalicylic, sulfonaphthalene, cyclohexanedicarboxylic or orthophthalic acid. Subsequently, the zeolite is filtered off, washed, dried and granulated. The final catalyst is treated with water vapor at 500-600 ° C (RU 2070829, B 01 J 29/06, 37/00, 1993). The zeolite samples synthesized by this method show catalytic stability up to 500 hours without structurally selective exchange and up to 3,000 hours after it. However, for the production of zeolite on an industrial scale, the unresolved issue of the disposal of wastewater containing alkalis, acids and polyvalent metals interferes.

Closest to the proposed invention is a method in which the main technological branch of the preparation of the catalyst includes preparing the reaction mixture, crystallizing the zeolite, conducting ion exchange and modifying the zeolite, isolating the zeolite from pulps obtained after crystallization, ion exchange or modification, washing the crystals, molding, drying and calcining the catalyst (RU 2221643, B 01 J 29/48, 37/00, 37/10, C 10 G 35/095, C 07 C 15/02, 2002).

The reaction mixture is prepared by mixing in water solutions of aluminum, zinc, tin, sodium hydroxide, crushed silica gel, butyl alcohol and seeds. The crystallization of the zeolite is carried out at 160-190 ° C for 6-12 hours, followed by distillation of butanol and the return of water-butanol condensate to the operation of preparing the reaction mixture. The Na-form of the zeolite obtained after filtering the pulp is washed first with a solution of ammonium carbonate, then with a solution of ammonium chloride and then with water. A smaller part of the precipitate is returned as seed crystals for the operation of preparing the reaction mixture.

The main part of the precipitate is subjected to ion exchange, carried out by mixing the zeolite in an aqueous solution of ammonium chloride by heating. The precipitate obtained is filtered and washed with water, the filtrate and washings are used in the washing operation of the Na-form of the zeolite.

Next, the wet cake is modified by heating and stirring the pulp in a solution of lanthanum nitrate acidified with nitric acid. The resulting pulp is filtered and the zeolite is washed with water. After mixing with wash water, the filtrate is sent to the regeneration of lanthanum nitrate, carried out by mixing with ammonium carbonate, followed by isolation of lanthanum carbonate and its dissolution in nitric acid. Lanthanum nitrate is returned to the zeolite modification stage. In this case, the wastewater, representing a solution of ammonium carbonate, is directed to washing the Na-form of the zeolite.

Next, the wet sediment of the modified zeolite is stirred with water, active aluminum and chromium hydroxides and then with a solution of nitric acid. The resulting mass is granulated by extrusion, the granules are dried, calcined at 550-600 ° C and after sieving the finished catalyst. The ammonia removed during the calcination of the granules is absorbed with water, the aqueous ammonia solution is neutralized with a hydrochloric acid solution, the resulting ammonium chloride solution is sent to the salt ion exchange operation.

Thus, this scheme is combined with a partial separation of the main components from solutions, which consists in the distillation of butanol, the regeneration of the lanthanum salt and the production of ammonium chloride, as well as with the partial use of wastewater in the intermediate stages of washing the zeolite. This approach allows to some extent to return butyl alcohol, lanthanum nitrate and ammonium chloride back to the catalyst preparation process and reduce the amount of wash water.

Tests of the catalyst prototype obtained in the reaction of converting methanol to a mixture of hydrocarbons taken as a model reaction of acid-base catalysis showed a low stability of the catalyst without loss of activity, which amounts to 350 hours of continuous operation depending on the composition of the synthesized catalyst.

The present invention solves the problem of creating a technology for producing ZSM-5 zeolite and a catalyst based on it, which has high rates in acid-base or redox catalysis reactions.

The problem is solved by an integrated approach, including combining the basic scheme for obtaining zeolite with the partial separation of most of the components from wastewater and their return to the main process.

The reaction mixture is prepared by mixing silicon sources in water, additional elements capable of isomorphically replacing silicon, alkali, and seed crystals in the absence of an organic structure-forming additive. As additional elements, any combination of sources of aluminum, iron, gallium, boron and chromium is used. As a source of silicon, you can use crushed silica gel, silica gel or substandard zeolite catalyst, or a combination thereof. At the same time, additional elements can be applied to them, which are introduced by impregnation, either while grinding with silica gel or a substandard zeolite catalyst, or by co-precipitation with silica gel. As seed crystals, a wet or dry product is used, obtained at any stage of the process and subjected to additional grinding, for example, zeolite powder or substandard catalyst.

The crystallization of zeolite is carried out by exposure of the prepared mixture in an autoclave at elevated temperature and appropriate pressure. Additionally, in the synthesis of zeolite, you can use an organic additive - alcohols or amines, it is preferable to use butyl alcohol or triethylamine.

The ion exchange is carried out with stirring of the Na-form of the zeolite and a temperature of up to 100 ° C in an aqueous solution of ammonium salt or mineral acid, preferably nitric acid. The ratio of liquid to solid (W / T) should be more than 2, preferably from 3 to 4.

The zeolite is modified by treating the precipitate with a solution of salts of one or several polyvalent cations selected from the series: iron, aluminum, chromium, gallium, zinc, cobalt, molybdenum, tungsten, rhenium, nickel, and platinum group metals. This operation can be carried out in two ways: either by the method of impregnation, or by the method of additional ion exchange.

Additional ion exchange is carried out with stirring of the zeolite in a solution of salts of the elements indicated above, at a temperature of up to 100 ° C with a ratio of W / T of more than 2, preferably from 3 to 4. An additional acid solution selected from the range: mineral, sulfosalicylic can be used. , cyclohexanedicarboxylic, orthophthalic, naphthalenesulfonic acid, preferably nitric acid.

The zeolite obtained after crystallization, ion exchange or additional ion exchange is isolated from the pulp by filtration or sedimentation. After which the precipitate is washed from excess salts with either water or intermediate wastewater. In this case, pure water is fed to washing the zeolite modified by ion exchange. The resulting wastewater is directed to washing the ion-exchange form of the zeolite and then to washing the Na-form of the zeolite.

Granulation of the catalyst is carried out by a multi-stage process. For this, the washed precipitate after the stages of ion exchange, additional ion exchange or modification by impregnation is dried at a temperature of from 20 to 120 ° C both in air and in an inert gas atmosphere or under vacuum to a residual moisture content of less than 30%, preferably with stirring of the precipitate. Next, adding a binder component and a peptizer to the dried zeolite, a paste is prepared for subsequent molding, containing about 35% moisture. As a binder component, active hydrogels of aluminum or silicon oxides are used; pseudoboehmite or thermochemically activated aluminum hydroxide is preferably used. As a peptizer, a solution of sodium silicate, silica sol, other organic or mineral components capable of interacting with a binder are used. When using an alumina hydrogel binder, a nitric acid solution is preferred.

In the case of zeolite modification by impregnation, it is carried out at a ratio W / T of less than 2, preferably from 0.1 to 0.7, followed by drying of the powder to a residual moisture content of less than 30%. This operation can be combined with the preparation of the molding paste described above.

Further, the catalyst is granulated from the prepared molding paste, preferably by extrusion to obtain wet cuttings.

The drying of the catalyst granules is carried out at temperatures up to 150 ° C both in air and in an atmosphere of oxygen, inert gas or under vacuum. The calcination of the catalyst is carried out by treating the dry catalyst at a temperature of 500-600 ° C in an atmosphere of air, oxygen, inert gas or water vapor, preferably in an atmosphere of water vapor, which is supplied with a space velocity of 0.5-2 h ^-1 . The finished catalyst after cooling is dispersed and packaged. The substandard fraction representing the screening is ground and used at the stage of mixing the reaction mixture as sources of both seed crystals, silicon and additional elements.

The extraction of the main components from solutions consists in the isolation of silicon sources, additional elements and an organic component from mother liquors and washings if it is used in the synthesis of zeolite.

The selection of the source of silicon is made from alkaline waters obtained after filtration and washing of the Na-form of the zeolite. To do this, these waters are combined with acidic waters obtained in the filtration step after ion exchange. Silicon acid hydrogel is precipitated - silica gel containing additional elements, such as aluminum, iron, gallium, chromium, etc. The resulting silica gel is separated from the mother water by filtration or centrifugation and returned to the mixing operation of the reaction mixture for subsequent synthesis of zeolite.

Isolation of an organic component (for example, butyl alcohol or triethylamine) is carried out directly from the pulp obtained after autoclaving, or from an alkaline mother liquor obtained after filtration of the Na-form of the zeolite. In the first case, the organic component is distilled off immediately after crystallization of the zeolite is completed. This operation allows to reduce the cooling time of the autoclave and to reduce the amount of heat during the distillation operation. In the second case, the organic component is distilled off from the alkaline mother liquor obtained after filtration of the Na form of the zeolite. A similar operation can be done in the synthesis of zeolite in the absence of an organic component. In this case, steam is distilled off, which reduces the cooling time of the autoclave. The vapors obtained in these cases are condensed (aqueous-organic condensate or water) and returned to the process, for example, to prepare the reaction mixture for the subsequent synthesis of zeolite.

Thus, this scheme for the preparation of a zeolite catalyst is combined with the extraction of the main components from wastewater, as well as the partial use of wastewater at intermediate stages of zeolite washing. Such an integrated approach allows to substantially return the organic component (butyl alcohol or triethylamine) and the source of silicon and additional elements (silica gel), back to the process of obtaining a catalyst while reducing the amount of wash water.

The combination of these differences makes it possible to synthesize a zeolite containing any combination of aluminum, iron, gallium, boron, and chromium in its structure during the isolation of the main components returned to the main process from wastewater. Moreover, the resulting zeolite has high characteristics in acid-base or redox catalysis reactions. The catalytic stability of the resulting zeolite in the reaction of converting methanol to a mixture of hydrocarbons is at least 800-1400 hours of continuous operation.

The invention is illustrated by the following examples.

Example 1 (prototype). Solutions of sodium hydroxide with a concentration of 94 g / l, aluminum nitrate with an aluminum concentration of 26 g / l, zinc nitrate with a zinc concentration of 21 g / l and a solution of tin (IV) chloride with a tin concentration of 60 g / l are prepared.

To 87 ml of water with stirring, 50 g of crushed silica gel, 133.5 ml of sodium hydroxide solution, 23 ml of aluminum nitrate solution, 48.75 ml of zinc nitrate solution, 16.75 ml of tin chloride solution, 19.5 ml of n-butanol are successively added. , 43.5 ml of water and 2.12 g of seed crystals, representing a wet Na-form of zeolite.

The prepared reaction mixture is kept in an autoclave at 175 ° C for 12 hours. After which, by turning off the heating of the autoclave, water vapor and butyl alcohol are distilled off. The pulp obtained after cooling is filtered, the zeolite precipitate is washed successively with solutions of ammonium carbonate, ammonium chloride, and then with drinking water.

The washed Na-form of the precipitate is pulp in 223 ml of a solution of ammonium chloride (120 g / l), heated and kept at 100 ° C and stirring for 4 hours. The resulting pulp is filtered, the precipitate is washed with demineralized water. The filtrate and washings, representing a solution of ammonium chloride, are directed to washing the Na-form of the zeolite.

Next, the precipitate of the MH ₄ form of zeolite is pulverized in 170 ml of a solution of lanthanum nitrate with a concentration of lanthanum 1.5 g / l, to which 0.16 ml of a solution of nitric acid with a concentration of nitric acid of 80 g / l is added. The pulp is kept at 90 ° C with stirring for 4 hours. The pulp obtained after the modification operation is filtered, the precipitate is washed with demineralized water.

50 ml of demineralized water, 24 g of a wet paste of active aluminum hydroxide (with a residual moisture content of 28.4 wt.%), 11.2 g of active chromium hydroxide and 10 ml of nitric acid solution (80 g) are successively added to the washed La-form of the precipitate. / l). The mixture is stirred until a homogeneous plastic mass is obtained, which is extruded by granulation into a catalyst.

Next, the crude granules of the catalyst are dried on pallets at 100-110 ° C for 10-12 hours. The dry granules are calcined at 500-600 ° C for 30 minutes and after cooling are classified by sieving. Screenings (<3 mm) are crushed and used in the preparation of the catalyst mass.

This scheme provides for the partial return of some components to the main process.

For this, after crystallization of the zeolite, water vapor and butyl alcohol are condensed, which are returned to prepare the reaction mixture.

The mother liquor and wash water obtained after filtration and washing of the La-form of the zeolite are combined, then 2 g of ammonium carbonate are added and lanthanum carbonate is precipitated. It is filtered off and returned to the zeolite modification operation with lanthanum, and the filtrate, representing a solution of ammonium carbonate, is sent to the washing operation of the Na-form of the zeolite.

Ammonia gas evolved during the calcination of the granules is absorbed by water, the solution is neutralized with hydrochloric acid, then the ammonium chloride solution is sent to prepare a solution for ion exchange.

The powder synthesized according to this example in the Na form contains 68 wt.% Zeolite type ZSM-5. The resulting final product has a residual Na ₂ O content of 0.03 wt.%, And the stability of the catalytic effect in the model reaction of methanol conversion at 380 ° C and a contact time of 2 h ^-1 , equal to 150 hours of continuous operation.

Example 2. In 360 g of water, 5.12 g of anhydrous aluminum nitrate and 15 g of sodium hydroxide are successively dissolved. In the resulting solution, 45 g of silica gel are repulped, containing 10.8 g of SiO ₂ , 0.35 g of Al ₂ O ₃ , 0.75 g of Ga ₂ O ₃ and the rest of the water, and 54.30 g of crushed in the subsequent stages of this example KSK silica gel containing 49.29 g of SiO ₂ , 0.08 g of Al ₂ O ₃ and 4.93 g of water, 1.8 g of pre-milled seed powder ZSM-5 zeolite.

The resulting mixture was crystallized in an autoclave at 180 ° C for 20 hours. After cooling, the pulp was filtered, the Na-form of the zeolite was washed with pure water to a pH of less than 9. The alkaline mother liquor and wastewater were sent to precipitate silica gel. A wet zeolite precipitate is poured into 160 g of a 5% solution of nitric acid and ion exchange is carried out with stirring for 3 hours at a temperature of 98 ° C. The hot pulp is filtered, the zeolite on the filter is washed with wastewater obtained in the operation of ion exchange modification. Acid mother liquor and wastewater are sent to precipitate silica gel.

The acid form of the wet zeolite is poured into 160 g of a solution of gallium nitrate containing 2.5 g of Ga ₂ O ₃ . The modification operation is carried out with stirring for 3 hours at a temperature of 80 ° C. The hot pulp is filtered, the mother liquor is separated and sent to the deposition of silica gel. The zeolite on the filter is washed with clean water. Then the zeolite is dried under vacuum at a temperature of 100 ° C to a residual moisture content of less than 23%.

Dried zeolite, then reprecipitated aluminum hydroxide having a moisture content of 65%, is added to a paste mixer with stirring at the rate of 80 wt.% Dry zeolite per 20 wt.% Dry alumina. Then add a 65% solution of nitric acid at the rate of 5% acid to dry alumina. Then, the paste moisture is adjusted to approximately 35%, and after mixing the components to a homogeneous mass, the catalyst is extruded.

The cuttings of the catalyst are dried at a temperature of 110-120 ° C, calcined for 1 h in a medium of water vapor at a temperature of 530 ° C and a weight rate of steam supply of 1 h ^-1 . After cooling, the finished product is dispersed and packaged. The substandard catalyst fraction is crushed and used in the operation of mixing the components as sources of seeds, as well as silicon, aluminum and gallium.

Acid waters obtained at the filtration stages after ion exchange and ion exchange modification operations are neutralized with alkaline waters after zeolite crystallization. The precipitated gel is centrifuged. 45 g of silica gel are obtained containing 10.8 g of SiO ₂ , 0.35 g of Al ₂ O ₃ , 0.75 g of Ga ₂ O ₃ and the rest is water. Wet silica gel is used in the operation of mixing the components as sources of silicon, aluminum and gallium for the subsequent production of galloaluminosilicate zeolite.

The powder synthesized according to this example in the Na form contains 94 wt.% Zeolite type ZSM-5. The resulting final product has a residual Na ₂ O content of 0.05 wt.% And a catalytic stability in the methanol conversion reaction at 380 ° C. and a contact time of 2 h ⁻¹ equal to 800 hours of continuous operation.

Example 3. 3.24 g of anhydrous gallium nitrate, 3.41 g of anhydrous aluminum nitrate and 13 g of sodium hydroxide are successively dissolved in 348 g of water. 54.82 g of crushed silica gel of the KSK brand containing 49.29 g of SiO ₂ , 0.08 g of Al ₂ O ₃ , 5 g of water are repulled in this solution. Then, 45 g of the silica gel obtained in Example 2 are added with stirring, containing 10.8 g of SiO ₂ , 0.35 g of Al ₂ O ₃ and 0.75 g of Ga ₂ O ₃ . Next, 2.25 g of seed is poured, which is used as a ground substandard catalyst obtained in example 2.

Subsequent operations are carried out analogously to example 2 except that the modification is carried out by impregnation. To do this, 100 g of wet zeolite powder washed after acid ion exchange are poured into a paste mixer. Then with stirring, add 25 ml of a solution containing 6.8 g of anhydrous gallium nitrate. The resulting mixture is dried at 100-110 ° C and stirring until the residual moisture content of the powder is not more than 23%.

Subsequent operations of the preparation of molding paste, granulation, drying and calcination are carried out analogously to example 2.

The disposal of wastewater and the separation of silica gel is carried out analogously to example 2. Receive 40 g of silica gel containing 10.8 g of SiO ₂ , 0.29 g of Al ₂ O ₃ and 0.56 g of Ga ₂ O ₃ . The obtained wet silica gel is used in the operation of mixing the components as sources of silicon, aluminum and gallium for the subsequent production of zeolite containing gallium and aluminum.

The powder synthesized according to this example in the Na form contains 92 wt.% Zeolite type ZSM-5. The resulting final product has a residual Na ₂ O content of 0.04 wt.% And a catalytic stability in the methanol conversion reaction at 380 ° C. and a contact time of 2 h ⁻¹ equal to 870 h of continuous operation.

Example 4. Ball mill silica gel of the KSK brand is poured into the mill, solutions of boric acid and aluminum nitrates, iron are successively poured, and a composition of the following mass composition is obtained: 60.09 g of SiO ₂ : 1.02 g of Al ₂ O ₃ : 0.532 g Fe ₂ O ₃ : 0.435 g of B ₂ O ₃ : 50 g of H ₂ O. The mixture is ground for 12 hours in a ball mill, then separated from the grinding media and repulped in a solution containing 400 g of water, 20 g of butyl alcohol, 14 g of caustic soda and 1, 8 g pre-milled seed.

The resulting mixture was crystallized in an autoclave at 175 ° C for 10 hours. Next, turning off the heat, distill off water vapor and butyl alcohol as in Example 1. After condensation of the vapor, 71.5 g of water and 15.7 g of butyl alcohol are obtained, which are returned to the operation of mixing the reaction mixture.

Subsequent operations are carried out analogously to example 2. However, the operation of modifying the zeolite is carried out by ion exchange with lanthanum nitrate as in example 1.

The disposal of waste water and the separation of silica gel is carried out analogously to example 2. Get 40 g of silica gel containing 10.8 g of SiO ₂ , 0.078 g of Al ₂ O ₃ and 0.064 g of Fe ₂ O ₃ . The obtained wet silica gel is used in the operation of mixing the components as sources of silicon, aluminum, and iron for the subsequent production of zeolite containing iron and aluminum.

The powder synthesized according to this example in the Na form contains 100 wt.% Zeolite type ZSM-5. The resulting final product has a residual Na ₂ O content of 0.03 wt.%, And the stability of the catalytic effect in the methanol conversion reaction at 380 ° C and a contact time of 2 h ^-1 , equal to 1200 hours of continuous operation.

Example 5. In a ball mill, ball silica gel of the KSK grade is poured and solutions of aluminum and chromium nitrates are successively poured, to obtain a composition of the following mass composition 49.29 g SiO ₂ : 0.94 g Al ₂ O ₃ : 0.184 g Cr ₂ O ₃ : 20 g H ₂ O. The mixture is impregnated with stirring for 6 hours, then 50 g of metal balls are poured and ground for 12 hours. After that, it is separated from the grinding media and repulped in a solution containing 400 g of water, 20.2 g of triethylamine, 14 g caustic soda. 45 g of wet silica gel are added to the pulp with stirring, containing 10.8 g of SiO ₂ , 0.08 Al ₂ O ₃ , 0.12 g of Cr ₂ O ₃ and the rest is water, and 1.8 g of pre-milled seed.

The resulting mixture was crystallized in an autoclave at 175 ° C for 10 hours. Then, turning off the heating, distillation of water vapor and triethylamine. After condensation of the vapor, 80.1 g of water and 17.6 g of triethylamine are obtained, which are returned to the mixing operation of the reaction mixture.

Subsequent operations are carried out analogously to example 2. However, the operation of modifying the zeolite is carried out by ion exchange with a 5% solution of chromium nitrate in the presence of a 3% solution of sulfosalicylic acid.

The disposal of wastewater and the separation of silica gel is carried out analogously to example 2. Get 45 g of silica gel containing 10.8 g of SiO ₂ , 0.08 g of Al ₂ O ₃ and 0.12 g of Cr ₂ O ₃ . The obtained wet silica gel is used in the operation of mixing the components as sources of silicon, aluminum and chromium for the subsequent production of zeolite containing chromium and aluminum.

The powder synthesized according to this example in the Na form contains 95 wt.% Zeolite type ZSM-5. The resulting final product has a residual Na ₂ O content of 0.05 wt.% And a catalytic stability in the methanol conversion reaction at 380 ° C. and a contact time of 2 h ⁻¹ equal to 1000 h of continuous operation.

Example 6

8 g of sodium hydroxide are dissolved in 100 g of water. To the resulting solution, 2 g of butanol and 60 g of water-butanol condensate obtained in the subsequent stages of this example and containing 18 g of butanol are added. Next, 170 g of wet silica gel and 2.25 g of ground seed powder prepared in the subsequent stages of this example are added. The resulting mixture is repulped for 1 hour.

The final mixture contains the following amounts of components:

SiO ₂ - 60.085 g, Al ₂ O ₃ - 1,020 g, Fe ₂ O ₃ , - 0.319 g, B ₂ O ₃ - 0.218 g, Ga ₂ O ₃ - 0.625 g, Cr ₂ O ₃ - 0.434 g, H ₂ O - 450 g, butanol - 20.012 g, NaOH - 8,000 g and 2.25 g of ground seed powder.

This mixture was crystallized in an autoclave at 180 ° C for 12 hours. After crystallization was completed, the water-butanol mixture was distilled off and condensed to obtain 60 g of water-butanol condensate containing 18 g of butanol, which was subsequently used to prepare the reaction mixture.

After cooling, the remaining pulp is filtered, the Na-form of the zeolite is washed with pure water to a pH of less than 9. The alkaline mother liquor and wastewater are sent to precipitate silica gel. A wet zeolite precipitate is poured into 160 g of a 5% solution of nitric acid and ion exchange is carried out with stirring for 3 hours at a temperature of 98 ° C. The hot pulp is filtered, the zeolite on the filter is washed with wastewater obtained in the operation of ion exchange modification. Acid mother liquor and wastewater are sent to precipitate silica gel.

The acid form of the wet zeolite is poured into 160 g of a solution of gallium nitrate containing 2.5 g of Ga ₂ O ₃ . The modification operation is carried out with stirring for 3 hours at a temperature of 80 ° C. The hot pulp is filtered, the mother liquor is separated and sent to the deposition of silica gel. The zeolite on the filter is washed with clean water. Then the zeolite is dried under vacuum at a temperature of 100 ° C to a residual moisture content of less than 23%.

Dried zeolite, then reprecipitated aluminum hydroxide having a moisture content of 65%, is added to a paste mixer with stirring at the rate of 80 wt.% Dry zeolite per 20 wt.% Dry alumina. Then add a 65% solution of nitric acid at the rate of 5% acid to dry alumina. Then, the paste moisture is adjusted to approximately 35%, and after mixing the components to a homogeneous mass, the catalyst is extruded.

The cuttings of the catalyst are dried at a temperature of 110-120 ° C, calcined for 1 h in a medium of water vapor at a temperature of 530 ° C and a weight rate of steam supply of 1 h ^-1 . After cooling, the finished product is dispersed and packaged. The substandard catalyst fraction is crushed and used in the operation of mixing the components as sources of seeds, as well as silicon and additional elements.

Acid waters obtained at the filtration stages after ion exchange and ion exchange modification operations are added with nitrates of aluminum, iron, gallium and chromium, as well as boric acid to their mass content: Al ₂ O ₃ - 0.265 g, Fe ₂ O ₃ - 0.319 g, V ₂ O ₃ - 0.218 g, Ga ₂ O ₃ - 0.625 g, Cr ₂ O ₃ - 0.434 g. The prepared solution is neutralized with stirring with alkaline waters formed at the zeolite filtration stage after crystallization. Then, 54.82 g of ground silica gel containing 49.28 g of SiO ₂ , 0.08 g of Al ₂ O ₃ are added with stirring. The resulting mixture was repulped for 1 hour, filtered and washed with water. 170 g of moist silica gel containing SiO ₂ - 60.085 g, Al ₂ O ₃ - 1,020 g, Fe ₂ O ₃ , - 0.319 g, B ₂ O ₃ - 0.218 g, Ga ₂ O ₃ - 0.625 g, Cr ₂ O ₃ are isolated - 0.434 g and the rest is water. The obtained wet silica gel is used in the operation of mixing the components as sources of silicon and additional elements.

The powder synthesized according to this example in the Na form contains 94 wt.% Zeolite type ZSM-5. The resulting final product has a residual Na ₂ O content of 0.03 wt.%, And the stability of the catalytic effect in the methanol conversion reaction at 380 ° C and a contact time of 2 h ^-1 , equal to 1300 h of continuous operation.

Claims (17)

1. A method of producing a zeolite of type ZSM-5, including mixing water sources of silicon, additional elements, alkali and seeds, crystallization, ion exchange, separation of the obtained pulps, modification, granulation, drying, calcination and extraction of the main components from wastewater, characterized in that, as a source of silicon or a part thereof, silica gel is used, isolated from domestic wastewater as a result of precipitation from an alkaline runoff with an acid runoff. 2. The method according to claim 1, characterized in that silica gel is obtained by precipitation from an alkaline filtrate obtained after crystallization of the zeolite, neutralization with acidic waters containing additional elements. 3. The method according to claim 1, characterized in that silica gel and / or zeolite catalyst and silica gel isolated from waste water are used as a source of silicon. 4. The method according to claim 3, characterized in that the silica gel or zeolite catalyst is impregnated with solutions of additional elements or mixed with a source of additional elements and subjected to grinding in dry or wet form. 5. The method according to claim 1, characterized in that any combination of sources of aluminum, iron, gallium, boron or chromium is used as additional elements. 6. The method according to claim 1, characterized in that the synthesis of zeolite is carried out in the presence of an organic additive, such as alcohols or amines, preferably butyl alcohol or triethylamine. 7. The method according to claim 6, characterized in that the organic additive is distilled off from the pulp obtained after crystallization of the zeolite to obtain condensate, which is returned to the mixing operation. 8. The method according to any one of claims 1 and 6, characterized in that water is distilled off from the pulp obtained after crystallization of the zeolite to produce condensate. 9. The method according to claim 1, characterized in that the zeolite obtained at any stage and subjected to grinding is used as a seed. 10. The method according to claim 1, characterized in that the ion exchange is carried out by mixing the zeolite in an aqueous solution of a mineral acid, preferably nitric acid. 11. The method according to claim 1, characterized in that the modification is carried out by mixing the zeolite in a solution of a modifier or by impregnating a zeolite with a solution of a modifier. 12. The method according to claim 11, characterized in that salts of one or more elements selected from the series are used as a modifier: iron, aluminum, chromium, gallium, zinc, cobalt, molybdenum, tungsten, rhenium, nickel, platinum group metals, lanthanum or rare earths. 13. The method according to claim 11, characterized in that the modifier contains any acid, preferably mineral, and / or sulfosalicylic, and / or cyclohexane dicarboxylic, and / or orthophthalic, and / or naphthalene sulfonic acid. 14. The method according to claim 1, characterized in that the zeolite is dried, a paste is prepared for molding and granulated. 15. The method according to item 13, wherein the zeolite is dried in an atmosphere of air, inert gas or vacuum, preferably with stirring. 16. The method according to claim 1, characterized in that the preparation of the paste is combined with the modification of the zeolite by impregnation, followed by drying of the zeolite. 17. The method according to claim 1, characterized in that the zeolite granules are calcined in an atmosphere of air, oxygen, inert gas or water vapor, preferably water vapor.