RU2463109C1 - Dehydrogenation catalyst, production method thereof and method of producing c2-c5 olefin hydrocarbons using said catalyst - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of a catalyst for dehydrogenation of C₂-C₅ aliphatic hydrocarbons to corresponding C₂-C₅ olefin hydrocarbons, a method of producing said catalyst and a method of producing olefin hydrocarbons. Described is a catalyst which contains non-boron-containing pentasil zeolite with molar ratio SiO₂/Al₂O₃ = 20-50, modified with 10-14 wt % chromium, alkali metal (sodium, potassium or lithium) and silicon or aluminium oxide as binder, with the following ratio of components in wt %: chromium-modified zeolite 50-80; alkali metal 0.2-3.4; binder - the balance. Described is a method of producing said catalyst, involving moulding crystalline, non-boron-containing pentasil zeolite with the binder, followed by treatment with a solution of hydrazine or salt thereof and a solution of potassium, sodium or ammonium dichromate, which is repeated until achieving chromium concentration in the zeolite of 10-14 wt %, treatment with water vapour at temperature 550-650°C and a solution of an alkali metal salt. Described is a method of producing C₂-C₅ olefin hydrocarbons via dehydrogenation of corresponding C₂-C₅ aliphatic hydrocarbons by bringing a gaseous stream containing an aliphatic hydrocarbon into contact with said catalyst at high temperature.

EFFECT: high output of olefin hydrocarbons.

3 cl, 3 tbl

Description

The invention relates to the field of production of chromium-containing catalysts based on zeolites of the pentasil type, as well as the production of olefinic hydrocarbons by dehydrogenation of the corresponding aliphatic hydrocarbons, and can find application in the chemical and petrochemical industries.

C ₂ -C ₅ olefin hydrocarbons are widely used as intermediates in the production of many types of large-capacity chemical products. An important industrial method for producing olefinic hydrocarbons is the dehydrogenation of the corresponding aliphatic hydrocarbons. The reaction is endothermic, the equilibrium concentration of the target products reaches economically acceptable values at temperatures above 550 ° C. Despite the high temperature, the dehydrogenation rate remains low, and therefore it is necessary to use a catalyst. At high temperatures, side reactions occur to a significant extent, resulting in the formation of polyaromatic compounds (coke) on the surface of the catalyst, while its activity gradually decreases. Oxidative regenerations are used to remove coke and restore catalyst activity. Currently, industrial dehydrogenation processes use catalysts containing platinum or chromium (III) oxide as the active dehydrogenating component. The main disadvantage of platinum-based catalysts is their high cost; the main disadvantage of chromium (III) oxide-based catalysts is their rapid deactivation.

Known dehydrogenation catalyst, which is platinum deposited on spinel. The catalyst is used in Phillips Petroleum Co.'s STAR (Steam Active Reforming) industrial process. for the dehydrogenation of aliphatic hydrocarbons C ₂ -C ₅ (US Patent No. 4926005, CL B01J 23/62, 05/15/1990). The disadvantage of the catalyst is the presence of expensive and scarce platinum.

Known ball dehydrogenation catalyst consisting of a porous carrier, platinum, tin, halogen, alkali or alkaline earth metal. The catalyst is used in UOP's Oleflex industrial process for the dehydrogenation of C ₂ -C ₅ aliphatic hydrocarbons (US Patent No. 4,430,517, CL B01J 23/56, 02/07/1984). The disadvantages of the catalyst is a difficult way to obtain, the presence of expensive and scarce platinum.

Alyumohromovy known oxide catalyst containing from 15 to 25% Cr ₂ O ₃ and up to 0.5% of an alkali metal used in the industrial process for producing olefinic hydrocarbons C ₃ -C ₅ hydrocarbons from aliphatic C ₃ -C ₅ (Process "CATOFIN" Company ABB Lummus Crest / United Catalysts, UK Patent No. 2162082, CL B01J 23/26, 01/29/1986). Dehydrogenation is carried out at a temperature of 540-650 ° C, atmospheric pressure and a gas space velocity of 1440-2880 h ^-1 , while the dehydrogenated hydrocarbon can be diluted with an inert gas. The disadvantage of the catalyst is quick decontamination. The disadvantage of the dehydrogenation method is the low productivity associated with the need for frequent oxidative catalyst regenerations, the use of expensive multi-reactor equipment.

Known catalyst composition, wt.%: Cr ₂ O ₃ - 6.0-30.0; SnO - 0.1-3.5; MeO 0.4-3.0; SiO ₂ - 0.08-3.0; Al ₂ O ₃ is the rest, where Me is an alkali metal used in the industrial method of producing olefinic hydrocarbons by dehydrogenation of the corresponding aliphatic hydrocarbons in a fluidized bed of a catalyst at a temperature of from 450 to 800 ° C, pressure from 0.1 to 3 atm. abs. and gas volumetric velocity from 100 to 1000 h ^-1 ("FBD" process of Snaprogetti and Yarsintez companies, RF Patent No. 2127242, CL B01J 23/18, 03/10/1999). The disadvantage of the catalyst is a complex method of obtaining, as well as fast decontamination, requiring continuous regeneration. The disadvantage of the dehydrogenation method is the use of a fluidized catalyst bed, which requires special expensive equipment and leads to abrasive wear of structures, abrasion and entrainment of a catalyst containing toxic chromium.

Known chromium-containing dehydrogenation catalyst based on zeolite L (US Patent No. 6084145, CL B01J 23/26, 04.07.2000). The catalyst was developed by Phillips Petroleum Co. and is intended for the dehydrogenation of aliphatic hydrocarbons With ₂ -C ₇ . The catalyst operates stably under the conditions of a dehydrogenation reaction, but has a low activity. For example, in the case of n-butane dehydrogenation, the conversion of the latter is only 18%.

It is known that the use of high-silicon zeolites in the processing of hydrocarbon materials as the basis for bifunctional catalysts can significantly reduce the rate of coke formation. Steric restrictions imposed on the ongoing reactions by the pore system of the zeolite prevent the formation of condensed polyaromatic compounds, increasing the time of continuous operation of the catalyst.

To modify the catalytic and / or molecular sieve properties of high-silicon zeolites, promoters of compounds of various metals are widely used, which can be introduced into the catalyst both at the zeolite synthesis stage and by subsequent treatments (impregnation, ion exchange).

Currently known chromosilicates (Kucherov AV, Zeolites. 1995. V.15. P.431-438) and chromoaluminosilicates (Giannetto G., Zeolites. 1997. V.19. P.169-174) MFI obtained by hydrothermal synthesis from the reaction mass containing chromium compounds, however, high concentrations of chromium in such zeolites lead to their low thermal stability. The use of traditional ion exchange with both solutions of Cr (III) and Cr (II) salts also does not lead to the introduction of appreciable amounts of chromium into the cationic positions of zeolites. In this regard, the reaction of ion exchange in the solid phase (Kucherov A.V., Kinetics and Catalysis. 1986. Vol. 27. No. 3. P.678-684), formally leading to materials any composition. However, in this case, the molar amount of chromium included in the porous structure of the zeolite does not exceed 20% of the number of lattice atoms of aluminum (Slinkin AA, Kinetics and catalysis. 1989. V.30. No. 1. P.184-192) , the use of excess modifier only leads to the formation of a separate phase of chromium oxide. Thus, the maximum concentration of chromium in the pore system of the zeolite does not exceed 1%, the activity of such materials is insufficient for their industrial use as dehydrogenation catalysts.

Known methods for producing chromium-containing zeolites ZSM-5 both by hydrothermal synthesis from a reaction mass containing chromium nitrate, and by impregnation of the initial zeolite with chromium compounds followed by heat treatment (VATsiatouras, Studies in Surface Science and Catalysis. V.142. 2002. P .839). In both cases, the amount of chromium introduced into the composition of zeolites is insufficient to obtain active catalysts; the propylene yield in the propane dehydrogenation reaction does not exceed 10%.

A known method for producing chromium-containing zeolites ZSM-5 by ion exchange of the initial zeolite with aqueous solutions of Cr (III) salts (P. S. Chintawar, Applied Catalysis B: Environmental. V.14. Issues 1-2. P.37-47). The disadvantage of this method is the low (less than 1%) chromium content in the modified zeolite.

There is a method of producing chromium-containing high-silicon zeolites by ion exchange of the initial zeolite with aqueous solutions of Cr (II) salts obtained in situ (US Patent No. 4452958, class C08F 10/00, 06/05/1984). The disadvantage of this method is the low (also less than 1%) chromium content in the modified zeolite.

Thus, all currently known methods for the modification of high-silicon zeolites do not allow significant concentrations of chromium to be introduced into their porous system.

Closest to the present invention (prototype) is a dehydrogenation catalyst based on high-silicon boroaluminosilicates, which includes at least 35% silicon, not more than 0.3% aluminum and 1-20% chromium (Japan Patent No. 2008266286, class C07C 5/333 November 6, 2008). The catalyst is obtained by impregnation of boroaluminosilicates synthesized by the hydrothermal method with a solution of chromium (III) nitrate, followed by treatment at a temperature of 300-900 ° C with a gas mixture containing oxygen and water vapor. The catalyst developed by Mitsubishi Chem. Corp., proposed for the dehydrogenation of alkanes to the corresponding alkenes by contacting a gas mixture containing the starting alkane and carbon dioxide with a fixed catalyst bed at elevated temperature. The catalyst is characterized by high stability of action, however, it is difficult to prepare and exhibits insufficient dehydrogenation activity associated with a low concentration of chromium inside the pores of the catalyst. The disadvantage of the method of producing alkenes is their low yield.

The objective of the present invention is to provide an active and selective catalyst for the dehydrogenation of C ₂ -C ₅ aliphatic hydrocarbons to the corresponding C ₂ -C ₅ olefinic hydrocarbons, characterized by high stability of action, as well as the creation of an economical method for producing C ₂ -C ₅ olefin hydrocarbons by dehydrogenation of the corresponding aliphatic hydrocarbons C ₂ -C ₅ .

The problem is solved by a catalyst for the dehydrogenation of aliphatic hydrocarbons C ₂ -C ₅ into the corresponding olefinic hydrocarbons C ₂ -C ₅ , including crystalline aluminosilicate - a boron-free pentasil type zeolite with a molar ratio of SiO ₂ / Al ₂ O ₃ = from 20 to 50, modified 10 -14 wt.% Chromium, an alkali metal selected from the group: sodium, potassium or lithium, a binder is silica or alumina in the following ratio of components (wt.%):

zeolite modified with chromium - 50-80;

alkali metal - 0.2-3.4;

the binder is the rest.

The solution of the present invention is also a method of producing a catalyst of the specified composition, which consists in the fact that a crystalline aluminosilicate that does not contain a pentasil type zeolite is formed with a binder - silica or alumina, then the formed zeolite is subsequently treated with a solution of hydrazine or its salt and a solution of bichromate potassium, sodium or ammonium, repeating the indicated sequence of treatments until the chromium concentration in the zeolite reaches 10-14 wt.%, after which the molded chromium-containing zeolite with water vapor at a temperature of 550-650 ° C for 1-6 hours, then the resulting composition is treated with a solution of an alkali metal salt, which is used as a salt of sodium, potassium or lithium.

The task is also solved by a method of producing olefinic hydrocarbons C ₂ -C ₅ aliphatic hydrocarbon dehydrogenation of the corresponding C ₂ -C _5, comprising contacting the gas stream comprising an aliphatic hydrocarbon as a pure or diluted with nitrogen, carbon dioxide, steam or a mixture thereof with a catalyst of the present invention at a temperature of 550-650 ° C, a pressure of 90-110 kPa, with a gas flow rate of 400-3000 h ^-1 .

According to the present invention, a high-silica pentasil type zeolite is included as a crystalline aluminosilicate in the composition of the catalyst. The choice of the type of high-silicon zeolite is associated primarily with its thermal and hydrolytic stability. It is preferable to use zeolites of the pentasil type — ZSM-5 (US Patent No. 3702886, CL B01J 29/40, 11/14/1972), ZSM-8 (UK Patent No. 1334243, CL B01J 29/40, 10/17/1973) and ZSM- 11 (US Patent No. 3709979, class B01J 29/40, 01/09/1973), which work well at high temperatures and withstand numerous regenerations.

The formation of a zeolite with a binder is carried out by conventional methods (extrusion, pressing, liquid molding) in order to give the catalyst the necessary shape (granules, balls, tablets) and ensure mechanical strength. Inorganic oxides are used as the binder, it is preferable to use available silica or alumina. It is possible to form a zeolite with a binder at any stage of preparation of the catalyst, however, in order to facilitate the technological operations associated with filtration, it is preferable to first form a zeolite with a binder, and then carry out all further processing.

According to the present invention, for modifying high-silica zeolites with chromium, a method is used, called by the authors "Multi-stage cluster synthesis", then MKS (Vakhmistrov V.E. Inorganic materials. 2010. T. 46. No. 9. S.1090-1094).

The essence of the ISS method is to carry out such a sequence of chemical reactions between a reagent localized inside the zeolite pores and external reagents such that stepwise accumulation of the modifier or modifiers in the form of insoluble compounds inside the zeolite pores occurs with each new reaction. Since chromium (III) or (II) ions, as mentioned above, do not penetrate well into high-silicon zeolites, chromium (VI) compounds — chromates — were chosen as a source of chromium. However, the chromate anions themselves are not capable of modifying the cation exchange positions of zeolites; therefore, it is first necessary to introduce a suitable reagent into them that converts chromium (VI) into some insoluble form. Re-introducing the reagent into the ion-exchange positions of the zeolite and the subsequent reaction with chromium (VI) compounds enriches the zeolite with another portion of the insoluble chromium compound. Acting further in a similar way, one can stepwise increase the amount of chromium in the pore system of the zeolite.

According to the present invention, as a reagent converting chromium (VI) into an insoluble form, hydrazine previously introduced into the pore system of the zeolite is used. Hydrazine in the composition of the zeolite can be introduced by ion exchange of zeolites containing an alkali metal with solutions of hydrazine salts, or by the reaction of the H-form of zeolite with solutions of hydrazine.

As a source of chromate anions, it is preferable to use available compounds — potassium, sodium or ammonium dichromates, the solutions of which contain, along with dichromate anions, an equilibrium concentration of chromate anions.

The molar ratio of SiO ₂ / Al ₂ O ₃ in high-silicon zeolites of the pentasil type can vary within wide limits, starting from a minimum value of 20; to introduce the maximum amount of chromium in one stage of the ISS, it is preferable to use zeolites with a ratio of SiO ₂ / Al ₂ O ₃ in the range of 20-50, since they have a sufficient density of ion-exchange centers. Due to the fact that the amount of chromium introduced during one ISS cycle depends on the molar ratio of SiO ₂ / Al ₂ O _{3 of the} initial zeolite, a different number of ISS cycles is required to achieve the indicated range of chromium concentrations for different zeolites. With an increase in the concentration of chromium in zeolite, diffusion restrictions increase, leading to the blocking of part of the ion-exchange sites and to a slowdown, and in the extreme case, to the termination of further accumulation of chromium in the porous zeolite system. The practically achievable concentration of chromium in pentasil-type zeolites is approximately 14 wt.%, Further processing by the ISS method does not lead to its increase.

To increase the stability of work and increase the selectivity for the target olefins, the catalyst is treated with water vapor at an elevated temperature, resulting in the hydrolysis of the strong acid centers of the zeolite. This step is preferably carried out after the introduction of chromium into the composition of the catalyst, since this treatment leads to a decrease in the density of ion exchange centers in the zeolite, increasing the number of ISS cycles required in the future to introduce a sufficient amount of chromium into the catalyst. Steam treatment is carried out before the introduction of an alkali metal, since it is effective only for decationized zeolites.

The high acidity of the zeolite, which is part of the dehydrogenation catalyst, leads to various side reactions, such as cracking, isomerization, oligomerization, dehydrocyclization and aromatization. According to the present invention, an effective method of inhibiting these reactions is the introduction of an alkali metal into the catalyst. The amount of metal added to the catalyst should neutralize the acid sites present in the zeolite. Modification of the catalyst with an alkali metal is carried out by impregnation by moisture capacity or by ion exchange reaction, it is preferable to use solutions of available sodium, potassium or lithium salts as a source of alkali metal.

According to the present invention, the dehydrogenation of aliphatic hydrocarbons is preferably carried out in the pressure range close to atmospheric. Although the process is carried out under reduced pressure, it increases the equilibrium concentration of reaction products, but it requires expensive vacuum equipment. The same effect can be achieved by diluting the starting aliphatic hydrocarbon with another gas, preferably nitrogen, carbon dioxide, water vapor, or a mixture thereof. It should be borne in mind that such a technical solution also has drawbacks associated with an increase in the cost of isolating and purifying the reaction product, as well as heating additional volumes of gas, the decision on the feasibility of its use is made after analyzing the technical and economic parameters of a particular process.

General Procedure I. Preparation of Dehydrogenation Catalysts

(a) The original pentasil ZSM-5 (CBV 2314 and CBV 5524G of Zeolyst International with a molar ratio of SiO ₂ / Al ₂ O _{3 of} 23 and 50, respectively) is formed with a binder - alumina or silica according to the methods described respectively in US Patent No. 3140253, cl. B01J 29/08, 07/07/1964 and No. 4582815, class. B01J 20/10, 04/15/1986. The formed decationized zeolite is treated with five times the amount of 0.1 M aqueous solution of hydrazine and left for 2 hours at 20 ° C. The solution is decanted, the product is washed with deionized water to a neutral pH.

(b) The obtained wet molded hydrazine-containing zeolite is treated with a five-fold amount of a 0.25 M solution of potassium, sodium or ammonium dichromate, with intense gas evolution lasting approximately 20 minutes. The suspension is left for another 2 hours at 20 ° C, after which the solution is decanted, the product is washed with several portions of a 0.01 M potassium carbonate solution until a colorless filtrate forms. The intermediate is treated with a five-fold amount of 0.1 M hydrazonium hydrogen carbonate solution prepared in situ from a 0.1 M hydrazine solution. The suspension is stirred for 1 hour at 20 ° C, after which the ion exchange is repeated once more. The solution is decanted, the product is washed with deionized water to a neutral pH. A molded chromium-containing zeolite is obtained after the first ISS cycle.

(c) Another or two treatments according to procedure (b) lead to formed chromium-containing zeolites after two or three ISS cycles, respectively.

(d) The obtained formed chromium-containing zeolites are dried for 2 hours at 120 ° C and calcined for 2 hours at 600 ° C.

(e) The obtained samples are treated with water vapor in a quartz isothermal reactor at a temperature of 550-650 ° C for 1-6 hours.

(f) An alkali metal is introduced into the steamed semi-processed products by the method of impregnation by moisture capacity or by the ion exchange reaction using solutions of sodium hydrogen carbonate, potassium carbonate or lithium hydroxide. The intermediates are impregnated with a solution of the calculated amount of an alkali metal salt, the ion exchange reaction is carried out by mixing the intermediate with a five-fold amount of a 0.1 M alkali metal salt solution for 2 hours, after which the solution is decanted and the catalyst is washed with deionized water.

(g) The resulting catalysts are dried for 2 hours at 120 ° C and calcined for 2 hours at 600 ° C.

General procedure II. Dehydrogenation of aliphatic hydrocarbons

Dehydrogenation is carried out in a quartz isothermal reactor, the volume of the loaded catalyst is 1 ml. The temperature in the reaction zone is controlled by an internal thermocouple. Quantitative analysis of the reaction products is carried out by GLC.

The essence of the invention and its practical applicability is illustrated by the following examples.

In Examples No. 1-16 (Table 1) data on the composition and conditions for producing the catalysts of the present invention (Examples No. 1-9) and comparison catalysts (Examples No. 10-16) are given.

In Examples No. 17-33 (Table 2) presents experimental data on the propane dehydrogenation on the catalysts of the present invention (Examples No. 17-25), comparison catalysts (Examples No. 26-32), as well as on the prototype catalyst (Example No. 33) .

An analysis of the results shows that the activity of the catalysts primarily depends on the chromium content introduced into the zeolite. Comparison catalysts containing insufficient chromium exhibit low dehydrogenating activity (Examples No. 26, 30, 31, 32). In addition, alkali metal-free reference catalysts exhibit low propylene selectivity (Examples No. 27, 29). The treatment of the catalysts with water vapor leads only to a slight increase in the yield of propylene, from 39.3 to 39.9% (Examples No. 28 and 17, respectively). However, additional experiments on the long-term dehydrogenation of propane on these catalysts showed that the duration of the steam-treated catalyst was 3 times the duration of the untreated catalyst. The propylene yield on all catalysts of the present invention is not less than 2.5 times higher than the propylene yield on the prototype catalyst.

Examples No. 34-39 (Table 3) show the parameters and results of experiments on the dehydrogenation of ethane, butane, isobutane and isopentane on the catalysts of the present invention (Examples No. 34-37), as well as data on the dehydrogenation of butane and isobutane on the catalyst of the prototype ( Examples No. 38, 39). All examples presented in Table 3 were performed according to General Procedure 2.

An analysis of the results shown in Table 3 shows that in all cases the catalysts of the present invention show high activity and selectivity in the dehydrogenation reactions of aliphatic hydrocarbons C ₂ -C ₅ , while the yields of butenes on the catalyst of the present invention are 3-5.5 times exceed the yields of butenes on the catalyst of the prototype.

Thus, the application of the present invention will allow to obtain technical and economic effects, consisting in increasing the yield of olefinic hydrocarbons and reducing the cost of production.

Table 1 Example No. SiO ₂ / Al ₂ O ₃ (molar) zeolite Binder, its content in the molded zeolite, wt.% The multiplicity of the introduction of Cr and its content in zeolite (wt.%) Alkali metal (method of its introduction *), content in the catalyst, wt.% Steaming mode, T, ° С × t, h 1 (invention) 23 SiO ₂ , 50% 2 (13.9) Na (Ex) 1.2 600 × 4 2 (invention) 23 SiO ₂ , 50% 2 (13.9) Li (Ave) 0.4 600 × 4 3 (invention) 23 SiO ₂ , 50% 2 (13.9) K (I.O.) 1.7 600 × 4 4 (invention) 23 SiO ₂ , 20% 2 (14.0) K (Ex.) 3.4 600 × 4 5 (invention) 23 Al ₂ O ₃ , 35% 2 (13.7) Na (Ex) 1.6 600 × 4 6 (invention) 23 SiO ₂ , 50% 2 (13.9) Na (Ex) 1.2 650 × 1 7 (invention) 23 SiO ₂ , 50% 2 (13.9) Na (I.O.) 0.6 600 × 4 8 (invention) 23 SiO ₂ , 50% 2 (13.9) Na (Ex) 1.2 550 × 6 9 (invention) fifty SiO ₂ , 50% 3 (13.0) Li (Ave) 0.2 600 × 4 10 (comparison) 23 SiO ₂ , 50% 1 (9.4) Na (Ex) 1.3 600 × 4 11 (comparison) 23 SiO ₂ , 50% 2 (13.9) - - 12 (comparison) 23 SiO ₂ , 50% 2 (13.9) Na (Ex) 1.2 - 13 (comparison) 23 SiO ₂ , 50% 2 (13.9) - 600 × 4 14 (comparison) 23 Al ₂ O ₃ , 35% 1 (9.3) Na (Ex) 1.7 600 × 4 15 (comparison) fifty SiO ₂ , 50% 1 (4.3) Na (Ex) 0.7 600 × 4 16 (comparison) fifty SiO ₂ , 50% 2 (8.8) Na (Ex) 0.6 600 × 4 * Etc. - impregnation, I.O. - ion exchange.

table 2 Example No. The catalyst according to example No. T, ° С Volumetric speed of propane, h ^-1 Propane conversion, mol.% The yield of propylene, mol.% Propylene selectivity, mol.% 17 (invention) one 580 420 43.9 39.9 90.9 18 (invention) 2 580 420 42.6 37.9 89.0 19 (invention) 3 580 420 44.1 39.7 90.0 20 (invention) four 580 670 42.7 38.6 90,4 21 (invention) 5 580 550 44.1 39.0 88.4 22 (invention) 6 580 420 44.0 39.7 90.2 23 (invention) 7 580 420 44.3 39.7 89.6 24 (invention) 8 580 420 43.7 39.5 90,4 25 (invention) 9 580 420 40,2 35.9 89.3 26 (comparison) 10 580 420 15.1 13.7 90.7 27 (comparison) eleven 580 420 47.2 18.3 38.8 28 (comparison) 12 580 420 44.7 39.3 87.9 29 (comparison) 13 580 420 39.5 17,2 43.5 30 (comparison) fourteen 580 550 17.0 14.9 87.6 31 (comparison) fifteen 580 420 7.8 7.1 91.0 32 (comparison) 16 580 420 12.7 11.5 90.6 33 (prototype) 1 prototype 600 310 * 16,0 14.3 89.2 * Based on undiluted catalyst.

Claims (3)

1. The catalyst for the dehydrogenation of aliphatic hydrocarbons C ₂ -C ₅ in the corresponding olefinic hydrocarbons C ₂ -C ₅ , comprising crystalline chromium-modified aluminosilicate, characterized in that the catalyst contains boron-free zeolite of the pentasil type with a molar ratio of SiO ₂ as crystalline aluminosilicate / Al ₂ O ₃ = 20 to 50, modified 10-14 wt.% Chromium, an alkali metal selected from the group: sodium, potassium or lithium, a binder is silicon oxide or alumina, in the following ratio, wt.%:
chromium modified zeolite 50-80 alkali metal 0.2-3.4 binder rest 2. The method for producing a catalyst according to claim 1, comprising introducing chromium into crystalline aluminosilicate and treating the resulting product with water vapor at elevated temperature, characterized in that a boron-free zeolite of the pentasil type, which is molded with a binder, is used as crystalline aluminosilicate or alumina, then the formed zeolite is successively treated with a solution of hydrazine or its salt and a solution of potassium, sodium, or ammonium dichromate, repeating the indicated sequence boot until the chromium concentration in the zeolite reaches 10-14 wt.%, after which the formed chromium-containing zeolite is treated with water vapor at a temperature of 550-650 ° C for 1-6 hours, then the resulting composition is treated with an alkali metal salt solution, which is used as a salt sodium, potassium or lithium. 3. A method of producing olefinic hydrocarbons C ₂ -C ₅ aliphatic hydrocarbon dehydrogenation of the corresponding C ₂ -C ₅ by contacting the gas stream containing an aliphatic hydrocarbon with a catalyst at elevated temperature, characterized in that a catalyst according to claim 1, and dehydrogenating aliphatic hydrocarbon , both pure and diluted with nitrogen, carbon dioxide, water vapor or a mixture thereof, is carried out at a temperature of 550-650 ° C, a pressure of 90-110 KPa with a gas flow rate of 400-3000 h ^-1 .