RU2448770C1 - Catalyst for dehydrogenation of c3-c5 paraffin hydrocarbons, method of producing said catalyst and method for dehydrogenation of c3-c5 paraffin hydrocarbons - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to catalysts for dehydrogenation of paraffin hydrocarbons and methods of producing said catalysts, as well as methods of producing olefin hydrocarbons via catalytic dehydrogenation of corresponding C₃-C₅ paraffin hydrocarbons and can be used in chemical and petrochemical industry. Described is a catalyst for dehydrogenation of C₃-C₅ paraffin hydrocarbons, which contains chromium and potassium oxides and optionally zirconium dioxide, deposited on a solid solution of formula Zn_xAl₂O_(3+x) where x=0.025-0.25, with a defective spinel structure. Described is a method of producing the catalyst by hydrating a precursor of the solid solution, saturating with a mixture of solutions of chromic acid, potassium chromate and a zinc salt and optionally zirconyl nitrate, followed by drying and calcination in air, wherein hydration is carried out during the saturation process. A method of dehydrogenating paraffin hydrocarbons in the presence of said catalyst is also described.

EFFECT: high catalytic activity, selectivity and stability with low coke formation.

14 cl, 2 tbl, 12 ex

Description

The invention relates to catalysts for the dehydrogenation of paraffinic hydrocarbons, methods for their preparation, as well as to methods for producing olefinic hydrocarbons by catalytic dehydrogenation of the corresponding paraffinic C ₃ -C ₅ hydrocarbons and may find application in the chemical and petrochemical industries.

The physicochemical features of the dehydrogenation reactions significantly affect the technological design of the processes and the choice of the catalytic system. The main factors determining the technological and structural design of dehydrogenation processes include:

1. The need to supply a large amount of heat to the reaction zone due to the endothermic nature of the reactions.

2. The need to create high temperature to achieve cost-effective dehydrogenation depths.

3. Short contact time for high selectivity.

4. The need for burning coke deposits or the creation of catalysts resistant to coke.

5. The need for rapid cooling of the reaction products to prevent the polymerization reaction from occurring.

Among the possible technological options for the dehydrogenation process, to the greatest extent possible to solve the above problems, a special place is occupied by the dehydrogenation method in a fluidized bed of a microspherical catalyst with catalyst circulation along the reactor - regenerator circuit. However, this process variant imposes special requirements on the catalyst: it should not only have high activity, selectivity, thermal stability, but also have high abrasion resistance and at the same time have low abrasive characteristics that do not lead to equipment abrasion.

The prior art has described many different solutions aimed at creating catalytic compositions having the above properties.

A known catalyst containing oxides of potassium, chromium, silicon on alumina. The catalyst is obtained by impregnation of aluminum oxide, previously calcined at 1000-1150 ° C, with solutions of chromium and potassium compounds, followed by drying, then by re-impregnation with a solution of silicon compounds, followed by drying and calcination (SU 1366200, B0J 37/02, 23/26, 1988) .

The disadvantage of the catalyst and method is the low mechanical strength and selectivity.

Known aluminum-chromium catalyst for dehydrogenation of paraffin hydrocarbons and a method for its production, which includes calcining aluminum hydroxide in a suspended layer at a temperature interaction of 450-800 ° C for 0.05-2.0 with a further decrease in temperature to 280-400 ° C, peptization of hydroxide aluminum nitric acid with the simultaneous introduction of chromium and potassium compounds, molding by spray drying and calcination. Under these conditions, 50-80 wt.% Aluminum hydroxide is calcined, the remaining 20-50 wt.% Aluminum hydroxide is calcined at 950-1200 ° C for 2-10 hours. The catalyst is molded at the spray drying stage (RU 1736034, B01J 37 / 02, 23/26, 21/04, 1995).

The catalyst has not enough high activity and stability, low mechanical strength. The method of its preparation is complex and multi-stage.

Known catalyst based on Al, Cr, K and Si for the dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons. The method for producing the catalyst includes calcining at 500-700 ° C alumina with particles in the form of microspheres, calcining at a temperature above 1000 ° C for several hours, impregnating the calcining product with a solution containing chromium compounds and potassium compounds, drying the resulting product and impregnating the drying product a solution containing a silicon compound, followed by final drying and firing at temperatures below 700 ° C (JP 7010350, B01J 23/26, 1995).

The disadvantage of the resulting catalyst is the lack of strength and stability, as well as the complexity and multi-stage process of obtaining.

A known catalyst for producing olefinic hydrocarbons by dehydrogenation of the following composition, wt.%: Cr ₂ O ₃ - 10.0-30.0; ZnO - 30.0-45.0; Al ₂ O ₃ - the rest. As a carrier, microspherical granules based on aluzinc spinel are used. The maximum productivity in the dehydrogenation process, determined by the product of conversion to selectivity, is 52.4% of the initial isobutane at a space velocity of isobutane of 400 h ^-1 and a temperature of 590 ° C. However, this catalyst has insufficient mechanical strength (RU 2178398, C07C 5/333, 1999).

A known catalyst for the dehydrogenation of paraffin hydrocarbons, which contains chromium oxides 12-23%, an alkali and / or alkaline earth metal compound in an amount of 0.5-3.5% and a non-metal compound: boron and / or silicon in an amount of 0.1-10% . The catalyst also contains at least one compound of a modifying metal (Ti, Zr, Sn, Fe, Ga, Co, Mn, Mo) in an amount of 0.5-1.5%. The catalyst was formed as a result of heat treatment of an aluminum compound of the formula Al ₂ O ₃ · nH ₂ O, where n = 0.3-1.5, an X-ray amorphous structure together with other compounds. The catalyst has high activity and selectivity (RU 2148430, B01J 23/26, 2000). However, its chemical composition is quite complicated, which creates certain difficulties in reproducing its properties during cooking.

A known catalyst that contains chromium oxide in an amount of 12-23 wt.%, A compound of an alkaline and / or alkaline earth metal in an amount of 0.5-3.5 wt.%, Zirconium dioxide in an amount of 0.1-5 wt.% And, at least one oxide promoter from the group: niobium, tantalum, hafnium in an amount of 0.001-2 wt.% on alumina. To prepare the catalyst, an aluminum compound of a layered X-ray amorphous structure of the formula Al ₂ O ₃ · nH ₂ O, where n = 0.3-1.5, preferably with a surface of 50-250 m ² / g, is used. This compound can be obtained by any known method, for example, rapid dehydration of hydrargillite. The catalyst is formed during the heat treatment of the aluminum compound together with the compounds of the above elements (RU 2200143, C07C 5/333, B01J 23/26, 37/02, 03/10/2003).

The disadvantage of this catalyst is that it does not have practical application due to the scarcity and high cost of the compounds used hafnium, niobium, tantalum. In addition, such a catalyst does not solve the stability problem.

A known catalyst for the dehydrogenation of paraffin hydrocarbons containing chromium oxide, an alkali metal compound, zirconia, a supported promoter is aluminum oxide, the precursor of which is an aluminum compound of the formula Al ₂ O ₃ · nH ₂ O, where n = 0.3-1.5, X-ray amorphous structure. The carrier precursor is a product of thermochemical activation (TXA), which is obtained by activating hydrargillite in a flue gas stream. The catalyst contains as a promoter at least one metal compound selected from the group: zinc, copper, iron in an amount of 0.03-2.0 wt.%. The catalyst is preferably formed during the heat treatment of the carrier - aluminum compounds of the formula Al ₂ O ₃ · nH ₂ O, where n = 0.3-1.5, of an X-ray amorphous structure, together with compounds of chromium, zirconium, an alkali metal, a promoter from the group: zinc, copper, iron.

To obtain a catalyst, the aluminum compound is impregnated with the catalytic components in the required amounts, dried and calcined at 700 ° C. During calcination, the formation of active sites of the catalyst in the form of solid solutions of chromates and chromites of zinc or copper or iron is strongly associated with the structure of aluminum oxide (RU 2271860, B01J 23/26, 03.20.06).

The catalyst has a high initial activity and selectivity, however, the achievement of this effect due to the introduction of iron and copper additives inevitably leads to an increase in the degree of coking of the catalyst. In addition, it is known that iron oxide is isostructural with α-Al ₂ O ₃ and, for this reason, the presence of a large amount of iron impurities in the aluminum-chromium catalyst reduces its service life due to the gradual formation of an inactive solid solution of the active component α-Cr ₂ O ₃ during operation in α-Al ₂ O ₃ .

The closest technical solution to both the catalyst and the method for its preparation is the catalyst and the method for its preparation disclosed in patent RU 2350594 C07C 5/333, B01J 23/26, B01J 21/04, B01J 37/02 08/13/2007. The paraffin hydrocarbon dehydrogenation catalyst contains chromium oxide in an amount of 10-20 wt.%, Potassium oxide in an amount of 0.1-5 wt.% And promoters: copper oxide and / or zinc oxide and / or zirconium oxide and / or oxide manganese, in an amount of from 0.1 to 5 wt.%. A method of producing a catalyst includes the operation of hydrothermal treatment of the source medium. After this, the carrier having boehmite morphology is impregnated with solutions of the precursors of the catalytic components. The impregnated carrier is dried and calcined at 600-900 ° C. The catalyst does not have a sufficiently high activity and especially selectivity. In addition, the operation of hydrothermal processing of the source medium significantly complicates the technology for producing a catalyst.

The analysis of the prior art shows that there is a problem of creating an inexpensive microspherical catalyst for the dehydrogenation of paraffinic C ₃ -C ₅ hydrocarbons into olefins in a fluidized bed with high catalytic activity, selectivity and stability with reduced coke formation, with low abrasive characteristics.

The problem is solved by a catalyst for the dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons into olefins, which contains chromium oxide deposited on a solid solution of the composition Zn _x Al ₂ O _{(3 + x)} , (where x = 0.025-0.25) with a defective spinel structure .

In addition, for the synthesis of Zn _x Al ₂ O _{(3 + x)} solid solutions, aluminum compounds of the general formula: Al ₂ O _3-x (OH) _x · nH ₂ O, where x = 0-0, are used as a solid solution precursor 28, n = 0.03-1.8, consisting of nanostructured primary particles 2-5 nm in size and characterized by a disordered defective layered structure close to that of bayerite.

The catalyst contains chromium (III) oxide - 6-20 wt.%; potassium oxide - 0.1-5 wt.%; zirconium dioxide - 0-3 wt.%; zinc oxide - 0.1-14 wt.%; aluminum oxide - the rest.

The catalyst is a microsphere with the following particle size distribution, wt.%: Less than 50 microns - less than 30; 50-80 microns - 20-30; 80-100 microns - 15-25; 100-120 microns - 15-20; 120-140 microns - 10-15; more than 140 microns less than 5.

The catalyst for the dehydrogenation of paraffin hydrocarbons C ₃ -C ₅ contains from 0.2 to 20 wt.% Zinc-aluminum spinel in solid solution.

The problem is also solved by the method of preparation of the catalyst.

The method for producing the catalyst includes the stages in which the solid solution precursor is hydrated, impregnated with a mixture of solutions of chromic acid, potassium chromate and zinc salt, followed by drying and calcination in air, the hydration being carried out in the process of impregnation.

In addition, as the solid solution precursor, aluminum compounds of the general formula are used: Al ₂ O _3-x (OH) _x · nH ₂ O, where x = 0-0.28, n = 0.03-1.8, consisting of nanostructured primary particles 2-5 nm in size and characterized by a disordered, defective layered structure close to that of bayerite obtained by centrifugal thermal activation (CTA).

As zinc salts, nitrates, acetates, formates, sulfates, zinc chlorides are used.

Drying of the catalyst is carried out using the heat released during hydration of the solid solution precursor at a temperature of 40-120 ° C.

In addition, the invention is intended to implement a method for the dehydrogenation of paraffin hydrocarbons C ₃ -C ₅ in which the catalyst described above is used.

The method is carried out in a fluidized bed of catalyst during circulation of the catalyst along the circuit of a dehydrogenation reactor - regeneration reactor.

The dehydrogenation temperature is 520-610 ° C, the regeneration temperature is 550-650 ° C, the volumetric feed rate of 400-800 h ^-1 , the dehydrogenation time is 10-30 minutes, the regeneration time is 5-30 minutes, the inert gas purge time between the dehydrogenation stages - regeneration - dehydrogenation - 3-15 minutes

The preparation of the CTA product is carried out by the method of rapid centrifugal thermal shock activation of aluminum hydroxide with the structure of hydrargillite (gibbsite) or bayerite at an elevated temperature in a heat-insulated chamber under the action of centrifugal forces, followed by forced cooling (RU 2237019, C01F 7/02, 09/27/2004). According to scanning electron microscopy, an oxygen-containing aluminum compound of the general formula: Al ₂ O _3-x (OH) _x · nH ₂ O, where x = 0-0.28, n = 0.03-1.8, obtained by centrifugal thermal shock activation has a particle shape close to spherical. The centrifugal thermal activation of hydrargillite (gibbsite) or bayerite is carried out in the installation, which is a chamber inside which a solid heat carrier rotates - a specially shaped plate. The rotation speed can vary and determines the contact time. Under the plate there are heating elements. The coolant temperature is controlled by three thermocouples. Alumina technical hydrate (hydrargillite) or bayerite from a metering hopper is fed to a heated plate, it is rapidly heated and, under the action of centrifugal force, moves along the surface of the coolant to the walls of the chamber equipped with a cooling jacket. Upon impact of heated particles of the activation product on the cold walls of the chamber, they undergo a sharp cooling (quenching). The chamber is equipped with openings for the exit of steam and a receiving hopper for powder. The study of the X-ray amorphous phase by the method of radial distribution of electron density with the construction of model curves for various oxide and hydroxide phases made it possible to establish that the CTA product differs from the TXA product. This difference is especially noticeable in the region of interatomic distances of 4–6 A. This difference is due to the presence of interatomic bonds in the CTA product characteristic of a disordered / defective layered structure close to that of bayerite. According to Al ²⁷ NMR, the intensity of the lines belonging to aluminum cations in the 4, 5, and 6 coordinated states with respect to the oxygen in the CTA product differs from the similar distribution in the TCA product (D.A. Isupova, Yu.Yu.Tanashev, IVKharina, EMMoroz et al. // Chemical Engeneering Journal 2005, v. 107, issue 1-3, pp. 163-169).

The CTA product has high chemical activity, which ensures a high rate of its subsequent hydration into pseudoboehmite at the stage of catalyst synthesis in the presence of water in an acidic medium.

These product properties contribute to the production of a dehydrogenation catalyst for lower C ₃ -C ₅ paraffins, which has high catalytic activity, selectivity, stability and mechanical strength, with low abrasive properties.

It was found that the introduction of zinc oxide additives in the catalyst based on the CTA product allows to increase the activity and selectivity of the process while reducing the yield of coke. This is explained by the formation of zinc-aluminum spinel with a defective structure during the interaction of the CTA product (having high activity) with zinc salts.

Zinc oxide, which is part of the solid solution, has less abrasiveness than, for example, zirconium oxide, which reduces wear on equipment.

In the range of zinc oxide concentrations from 0.1 to 14 wt.% Non-stoichiometric spinel is formed, which automatically becomes defective and, accordingly, more reactive.

The catalyst is prepared by impregnation of an aluminum compound of the general formula: Al ₂ O _3-x (OH) _x · nH ₂ O, where x = 0-0.28, n = 0.03-1.8, consisting of nanostructured primary particles of size 2- 5 nm and characterized by a disordered, defective layered structure close to that of bayerite obtained by centrifugal thermal activation (CTA).

When preparing an impregnating solution, the volume of water is taken about 30-40% more than is required for moisture capacity, taking into account the fact that an excess amount of water is spent on hydration of the CTA product into pseudoboehmite - AlOOH. The impregnation is carried out for 1-4 hours at a solution temperature of 20-100 ° C (preferably 40-100 ° C) with constant stirring in a closed volume at a constant partial pressure of water vapor. The additional heat generated due to the exothermic reaction of product hydration - CTA to pseudoboehmite is used for subsequent drying of the catalyst. Drying of the catalyst is carried out for one hour with continuous stirring with the lid of the impregnator open.

The heat generated makes it possible to carry out the drying stage more efficiently, as drying of bulk materials only with heating the walls of the drying apparatus is difficult to carry out, you have to significantly increase the drying time or put an additional dryer.

Due to the high chemical activity of the precursor of the CTA product solid solution at the impregnation stage, a solution containing zinc salts and the solid solution precursor react with the formation of zinc hydroxoaluminates (HAC). The formation of a HAC promotes the formation of a Zn _x Al ₂ O _{(3 + x)} solid solution upon calcination in air of a catalyst at temperatures of 650-800 ° C, preferably 750 ° C.

Chromic anhydride or solutions of chromic acid, potassium hydroxides or carbonates, chromates and / or potassium dichromates, nitrates, chlorides, acetates, or zirconium sulfates are used as starting materials for the preparation of the impregnating solution. As zinc salts, nitrates, acetates, formates, sulfates, zinc chlorides are used.

Research methods

The phase composition of the solid solution and the catalyst was determined by x-ray phase analysis (XRD) and derivatography (DTA). X-ray diffraction was performed on an HZG-4c apparatus in the range of angles from 10 to 80 degrees in 2θ with a computer recording of the results. DTA was carried out on a NETZSCH STA 449C apparatus with a heating rate of 10 deg / min.

The composition of the Zn _x Al ₂ O _{(3 + x)} solid solution was calculated by changing the parameter of the cubic alumina phase in the catalyst with respect to the parameter γ-Al ₂ O _{3 of the} phase. The calculation of the lattice parameter was carried out along the line (422) in the region of 66.6-67.2 deg according to 29. The dependence of the lattice parameter of the solid solution calcined at 750 ° C on the content of zinc oxide is shown in Table 1.

Table 1. Changes in the lattice parameter of Zn _x Al ₂ O _{(3 + x)} solid solutions as a function of zinc oxide Phase The content of ZnO wt.% Lattice parameter, a nm γ-Al ₂ O ₃ 0 0.7916 Zn _x Al ₂ O _{(3 + x)} 2 0.7932 - "- 3 0.7939 - "- four 0.7941 - "- 6 0.7950 - "- 8 0.7957 ZnAl ₂ O ₄ 44.3 0.8085

The table shows that the lattice parameter increases with increasing zinc oxide content. Presentation of the obtained data in graphical coordinates shows that a change in the lattice parameter of a solid solution is well described by the Vegard rule. Such a change in the parameter indicates the formation of a solid solution based on the spinel structure with a deficiency in zinc cations, vacancies in the positions of the crystal lattice related to zinc cations create a defective structure. The components deposited on defective carriers have increased catalytic activity (Molchanov V.V., Buyanov R.A., Goidin V.V. // Kinetics and Catalysis, 1998, vol. 39, No. 3, p. 465-471).

The specific surface and porous structure of the initial CTA products and catalysts were determined using a Quantachrome Corporation apparatus for nitrogen adsorption and desorption. To calculate the specific surface area of BET, pore volume, and pore size distribution, the program "Gas Sorpsion Report Autosob for Windows for AS-3 and AS-6" Version 1.23 was used.

The fractional composition of the catalyst was determined by laser scattering on a Shimadzu SALD 2101 instrument.

Chemical analysis of the catalyst was carried out by atomic absorption on a Saturn apparatus.

The catalytic activity of the obtained catalysts in the process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons to olefinic hydrocarbons was evaluated by the activity of the isobutane dehydrogenation reaction in the fluidized bed of the catalyst described above. The dehydrogenation temperature is 560-580 ° C, the regeneration temperature is 560-650 ° C, the volumetric feed rate is 400 h ^-1 , the dehydrogenation time is 10 minutes, the regeneration time is 5-30 minutes, the inert gas purge time between the stages is dehydrogenation - regeneration - dehydrogenation - 3-15 minutes

The invention is illustrated by the following examples.

Example 1

A CTA product with the following characteristics was used as a solid solution precursor: specific surface area 230 m ² / g, particle size 2-5 nm, loss on ignition at 800 ° C - 15.9 wt.%, Moisture capacity 0.3 cm ³ / g .

To prepare 100 kg of the catalyst composition: Cr ₂ O ₃ - 12 wt.%, K ₂ O - 1.5 wt.%, ZrO ₂ - 1.0 wt.%) And ZnO - 3.0 wt.%; 98.1 kg of the precursor was placed in a mixer with Z-shaped blades and the impregnation solution was added. To prepare the impregnating solution, CrO ₃ = 15.8 kg, KOH = 1.8 kg were poured into the container with stirring, and 19.9 L of distilled water was added. In a separate container, 3 kg of ZnO and 2.9 kg of Zr (CO ₃ ) ₂ were dissolved in 9.54 L of HNO ₃ (concentration 629 g / L). Next, the contents of the second container were poured into the first container, and the resulting impregnation solution was poured into the mixer.

The impregnation was carried out with continuous stirring with the mixer lid closed until the temperature of the impregnating solution was increased to 90-120 ° C due to the endothermic hydration reaction of the CTA product. Then the lid of the mixer was opened and drying was carried out at a temperature of 120-40 ° C due to the heat released during hydration. Drying was carried out until a loose mass was formed. Dried catalyst The catalyst was calcined at a temperature of 650-800 ° C for 1 hour.

Example 2-11 The preparation of the precursor and the catalyst was carried out analogously to example 1. The difference is that the obtained catalyst samples differ in the content of chromium oxide and promoting additives of zinc oxides, zirconium and potassium oxide.

Data on the chemical composition and catalytic properties of the obtained samples are shown in table 2.

Catalysts were used to dehydrogenate C ₃ -C ₅ paraffin hydrocarbons to olefinic hydrocarbons in a fluidized bed. The dehydrogenation temperature is 560 and 580 ° C, the catalyst regeneration temperature is 560 and 650 ° C, the volumetric feed rate is 400 h ^-1 , the dehydrogenation time is 10 min, and the regeneration time is 5-30 min. The catalyst circulated in a circle dehydrogenation - regeneration - dehydrogenation. The inert gas purge time between the dehydrogenation – regeneration – dehydrogenation stages was 3–15 min.

Table 2. The effect of the content of zinc oxide and zirconium additives on the catalytic characteristics of the microspherical CrO ₃ —K ₂ O / Al ₂ O ₃ catalyst. Example Content, wt.% Reaction temperature, ° C 560 580 Cr ₂ O ₃ Zno ZrO ₂ K ₂ O VP BP C VP BP C No. 1 12.0 3.0 1.0 1,5 50.9 95.1 1.2 56.9 91.5 2.2 Number 2 12.0 0 0 0.1 47.3 90.8 1.2 55.0 88.7 2.1 Number 3 12.0 2.0 0 1,5 51.3 93.6 1.2 57.8 89.9 2.2 Number 4 12.0 3.0 0 1,5 50.8 93.8 1.2 57.9 90.0 2.2 Number 5 8.0 0 1.0 1,5 46.8 93.2 1.0 51.1 88.1 2.0 Number 6 8.0 3.0 0 1,5 50.2 94.2 0.8 56.6 89.9 1.6 Number 7 12.0 4.0 0 1,5 51.5 93.9 1.1 57.3 90.1 1.8 Number 8 12.0 6.0 0 1,5 51.7 94.5 1.1 57.4 91.1 1.8 Number 9 12.0 8.0 0 1,5 51.4 94.4 1.1 57.5 90.9 1.6 Number 10 6.0 14.0 0 1,5 49.8 94.1 0.6 55.1 89.0 1.4 Number 11 20,0 0.1 3.0 5 46.1 90.0 1,0 50.8 88.8 1.3 No. 12 (prototype) twenty 4.9 0 four 48.3 88.0 VP - yield of isobutylene to the missed isobutane (activity); BP - yield of isobutylene to decomposed isobutane (selectivity); C - coke formation.

As can be seen from the examples in table 2, the introduction of zinc oxide additives and the formation of Zn _x Al ₂ O _{(3 + x)} solid solutions increase the yield of isobutylene and the selectivity of the dehydrogenation reaction. Especially the most prominent promoting effect of the introduction of zinc oxide additives is observed at low levels of chromium oxide. The positive effect of the promotion of zinc oxide is observed in a wide range of concentrations of zinc oxide in the catalyst and solid solution. Moreover, if at the same chromium oxide content the isobutylene yield and selectivity practically do not change with an increase in the ZnO content from 2.0 to 8.0 wt.%, Then the coke yield gradually decreases with increasing zinc oxide content.

Claims (14)

1. The catalyst for the dehydrogenation of paraffin hydrocarbons C ₃ -C ₅ , characterized in that it contains oxides of chromium and potassium and optionally zirconia supported on a solid solution of the composition Zn _x Al ₂ O _{(3 + x)} , where x = 0,025 -0.25, with a defective spinel structure. 2. The catalyst according to claim 1, characterized in that to obtain a solid solution precursor, an aluminum compound of the general formula is used:
Al ₂ O _3-x (OH) _x · nH ₂ O, where x = 0-0.28, n = 0.03-1.8, consisting of nanostructured primary particles 2-5 nm in size and characterized by a disordered defective layered structure close to the structure of bayerite obtained by centrifugal thermal activation. 3. The catalyst according to claim 1, characterized in that it contains in terms of oxides:
chromium oxide (III) 6-20 wt.%
potassium oxide 0.1-5 wt.%
zirconium dioxide 0-3 wt.%
zinc oxide 0.1-14 wt.%
aluminum oxide the rest 4. The catalyst according to claim 1, characterized in that the content of zinc-aluminum spinel in the solid solution is from 0.2 to 20 wt.%. 5. The catalyst according to claim 1, characterized in that it is a microsphere with the following distribution of particle sizes, wt.%:
less than 50 microns less than 30 50-80 microns 20-30 80-100 microns 15-25 100-120 microns 15-20 120-140 microns 10-15 more than 140 microns less than 5 6. A method of preparing a catalyst according to any one of claims 1 to 5, characterized in that the solid solution precursor is hydrated, impregnated with a mixture of solutions of chromic acid, potassium chromate and zinc salt, followed by drying and calcination in air, and hydration is carried out in the process of impregnation. 7. The method of preparation of the catalyst according to claim 6, characterized in that the mixture of solutions for the impregnation of the solid solution precursor further comprises zirconyl nitrate. 8. The method of preparation of the catalyst according to claim 6 or 7, characterized in that nitrates, acetates, formates, sulfates, zinc chlorides are used as zinc salts. 9. The method of preparation of the catalyst according to claim 6, characterized in that the aluminum compound of the general formula: Al ₂ O _3- OH (OH) _x · nH ₂ O, where x = 0-0.28, n, is used as a solid solution precursor = 0.03-1.8, consisting of nanostructured primary particles 2-5 nm in size and characterized by a disordered defective layered structure close to that of bayerite obtained by centrifugal thermal activation. 10. The method of preparation of the catalyst according to claim 6, characterized in that the drying is carried out using heat generated during hydration of the solid solution precursor, at a temperature of 40-120 ° C. 11. The method of preparation of the catalyst according to claim 6, characterized in that the calcination is carried out in air at a temperature of 650-800 ° C. 12. The method of dehydrogenation of paraffin hydrocarbons With ₃ -C ₅ , characterized in that when it is used, use the catalyst according to any one of claims 1 to 5. 13. The method according to p. 12, characterized in that it is carried out in a fluidized bed of catalyst when the catalyst is circulated along the circuit of a dehydrogenation reactor - a regeneration reactor. 14. The method according to p. 12, characterized in that the dehydrogenation temperature is 520-610 ° C, the catalyst regeneration temperature is 550-650 ° C, the volumetric feed rate of 400-800 h ^-1 , the dehydrogenation time 10-30 min, time regeneration 5-30 minutes, the time of purging with an inert gas between the stages of dehydrogenation - regeneration - dehydrogenation - 3-15 minutes