RU2845220C2 - Spheroid particles of aluminium oxide, method for production thereof and catalyst based thereon - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in catalytic processes such as catalytic reforming and dehydrogenation of gaseous hydrocarbons. Disclosed are spheroidal alumina particles having a specific pore volume from 0.50 cm³/g to 0.75 cm³/g, a specific surface area from 85 m²/g to 125 m²/g, a calculated pore diameter from 12 nm to 28 nm and a crushing strength of at least 35 N/granule. said particles contain an element of IV group of periodic table in amount of 0.05 wt. % to 0.50 wt. % and are characterized by spheroidality criterion of at least 0.90 and bulk density of 0.50 g/cm³ to 0.75 g/cm³. Invention also discloses use of such particles as a catalyst support in heterogeneous processes, a method of producing such spheroidal particles and a catalyst for heterogeneous processes containing said particles.

EFFECT: group of inventions enables to obtain a catalyst support having high mechanical crushing strength and abrasion resistance, and a catalyst based thereon, having high catalytic properties.

43 cl, 2 dwg, 1 tbl, 13 ex

Description

Field of technology to which the invention relates

The present invention relates to spheroidal particles of aluminum oxide suitable for use as a catalyst support in various catalytic processes, such as catalytic reforming, dehydrogenation of gaseous hydrocarbons, etc., to a method for producing such particles, as well as to a catalyst containing such particles as a support.

State of the art

Light olefins (ethylene, propylene and butene) are valuable components of the petrochemical industry. Such olefins are used especially actively in the polymer industry. Products containing polypropylene, polyethylene, as well as copolymers of propylene, ethylene and butene, have good performance characteristics and are used everywhere, for example, in the production of cables, household appliances, pipes, etc.

One of the common methods for producing light olefins in industry is the dehydrogenation of gaseous C ₂ -C ₄ hydrocarbons in the presence of catalysts. Heterogeneous catalysts containing an element of group VIII of the Periodic Table of D.I. Mendeleyev (hereinafter referred to as the Periodic Table) as an active component are widely used as dehydrogenation catalysts. The active component is applied to a carrier, which is aluminum oxide, aluminosilicate, or another synthetic carrier. In addition to the active component, other components are applied to the carrier that are not active in the catalytic dehydrogenation process, but allow improving the performance characteristics of the catalyst, in particular, the service life of the catalyst. Some of such components are elements of group IV of the Periodic Table, for example, tin. Such components, as is known from the prior art, incl. from documents US3998900 (published 21.12.1976, applicant UNIVERSAL OIL PROD CO [US]) and US3909451 (published 30.09.1975, applicant UNIVERSAL OIL PROD CO [US]), prevent the formation of large platinum nanoparticles during operation. The introduction of additional components into the catalyst composition allows maintaining high dispersion of the active component on the surface of the corresponding carrier and, therefore, maintaining high catalyst activity over time. In addition to group IV elements, other components are applied to the carrier: alkali metals, alkaline earth metals, lanthanides, halogens, etc.

One of the important components of the catalyst for the dehydrogenation of gaseous _C2 - _C4 hydrocarbons is the carrier.

When using spheroidal aluminum oxide particles as a carrier, they must have not only a developed porous structure and a large specific surface area, but also high mechanical strength.

Mechanical strength, in particular crushing strength and abrasion resistance, is a key parameter to be taken into account for the considered application of aluminum oxide particles in catalysis. When used, for example, in a fluidized or moving bed, the particles are subject to impacts and friction phenomena that can cause the formation of fine particles that pose a risk of clogging of installations or filters and that also contribute to the loss of part of the catalyst.

Therefore, it is important to obtain aluminum oxide particles that have both low density and good mechanical strength.

Patent RU 2608775 (published 24.01.2017, copyright holder IFP ENERGIES NUVELL [FR]) proposes a method for producing spheroidal particles of aluminum oxide, which includes the following stages:

a) obtaining a suspension containing water, acid and at least one boehmite powder for which the ratio of the crystallite sizes in the directions and obtained according to the Scherrer formula for X-ray diffraction is in the range from 0.7 to 1;

b) adding a blowing agent, a surfactant and optionally water or an emulsion containing at least a blowing agent, a surfactant and water to the suspension obtained in step a);

c) mixing the suspension obtained in step b);

d) formation of spheroidal particles by coagulation in a drop, starting from the suspension obtained in step c);

e) drying the particles obtained in step d);

f) calcination of the particles obtained in step e).

The main distinctive feature of the proposed method for producing a carrier is the use of at least a portion of boehmite powder having a certain crystalline structure, which allows for the production of low-density carrier particles having a mechanical strength at least equivalent to a carrier made of dense aluminum oxide, while limiting the amount of blowing agent used in the process. In addition, by limiting the amount of blowing agent used, the method provides an additional advantage from an economic point of view, in particular, a reduction in the cost of the starting material and the processing of volatile organic compounds formed during the decomposition of the blowing agent released at the calcination stage.

The disadvantage of this method of obtaining the carrier is the procedure for selecting the initial raw material of aluminum hydroxide by its crystalline structure. Also, the addition of a surfactant at the stage of preparing the suspension leads to foaming, which negatively affects the supply of sol to the coagulation solution when scaling the process.

Patent RU 2739560 (published 25.12.2020, copyright holder Public Joint Stock Company "Oil Company "Rosneft" [RU]) proposes a method for producing a spherical alumina carrier, including preparing a mixture of aluminum hydroxide powders, suspending, peptizing with a nitric acid solution, forming spherical granules, drying and calcining. In this case, according to the invention, a mixture is prepared containing aluminum hydroxide in the form of 60-70 wt. % highly porous boehmite having a pore volume of 0.9-1.1 cm ³ /g and 30-40 wt. % low-porosity pseudo-boehmite having a pore volume of 0.5 cm ³ /g or a mixture containing 60-70 wt. % highly porous boehmite having a pore volume of 0.9-1.1 cm ³ /g and medium-porosity boehmite having a pore volume of 0.7 ^cm3 /g and 30-40 wt. % low-porosity pseudo-boehmite having a pore volume of 0.5 ^cm3 /g, or a mixture containing aluminum hydroxide in the form of 60-70 wt. % of a mixture of highly porous boehmites having a pore volume of 0.9-1.1 ^cm3 /g and 30-40 wt. % low-porosity pseudo-boehmite having a pore volume of 0.5 ^cm3 /g, are suspended with water, peptized to obtain a pseudo-sol, mixed, water is added and methylcellulose is introduced in an amount of 10-20 wt. % based on calcined aluminum oxide, mixed until a homogeneous state is obtained, the spherical granules are formed by the hydrocarbon-ammonia molding method, and before drying the granules are kept in air for 22-26 hours.

The obtained spherical alumina carrier has the following properties: pore volume - not less than 0.5 ^cm3 /g; specific surface - not less than 180 ^m2 /g; strength - not less than 6 kg/granule; bulk density - not more than 0.7 g/ ^cm3 .

The use of methylcellulose as an organic binder provides a higher content of wide-porous and medium-porous components, as a result of which the resulting spherical granules of the alumina carrier have a developed specific surface area and a porous structure.

The disadvantage of the proposed method is the use of methylcellulose in large quantities, which leads to the formation of macropores, which negatively affect the catalytic properties of catalysts obtained on such carriers. Also, the presence of a long stage of drying granules in the air reduces the productivity of the process and increases ammonia emissions into the atmosphere, which negatively affects the environmental performance of the entire process.

Patent RU 2716435 (published 11.03.2020, copyright holder IFP ENERGIES NUVELL [FR]) describes spheroidal alumina particles characterized by a specific surface area according to BET ranging from 150 to 300 ^m2 /g, an average particle diameter ranging from 1.2 to 3 mm and a spread of particle diameters, expressed through a standard deviation, not exceeding 0.1, a total pore volume measured by mercury porosimetry ranging from 0.50 to 0.85 ml/g, a degree of macroporosity in one particle below 30%, and the spread of macropore diameters, expressed through the ratio of diameters D90/D50, does not exceed 8. The special pore distribution observed in the spheroidal alumina particles according to the invention is due, in particular, to the methods for their production, which use either solid blowing agent or liquid blowing agent. The method for producing spheroidal particles of aluminum oxide includes the following stages:

a) preparing a suspension containing water, acid and at least boehmite powder,

b) adding a solid or liquid blowing agent,

b') in the case of using a liquid blowing agent - dispersing the suspension obtained in step b) using a dispersant,

c) mixing the suspension obtained in step b) or b',

d) shaping the spheroidal particles by drop coagulation based on the mixture obtained in step c),

e) drying the particles obtained in step d),

f) firing the particles obtained in step e).

The disadvantage of the proposed method is the production of an alumina carrier with a wide pore size distribution, which can lead to the formation of a large amount of coke when using a catalyst prepared on the basis of such a carrier.

In addition, especially when used in fluidized bed catalysis, uniformity of the size and shape of the aluminum oxide particles is also important to ensure the fluidity of the catalyst.

Thus, application CN 115364837 (published on 22.11.2022 by CHINA PETROLEUM & CHEM CORP [CN]; SINOPEC CORP RES INST PETROLEUM PROCESSING [CN]) proposes macroporous spherical aluminum oxide particles with a specific surface area of 223-260 ^m2 /g, a pore volume of 0.7-0.9 ^cm3 /g, characterized by a sphericity index of more than 0.95 based on more than 90 vol.% of all particles. The invention also relates to a method for producing spherical aluminum oxide particles, comprising the following steps:

1) peptization of pseudoboehmite with an acid solution to obtain an aluminum oxide sol;

2) feeding aluminum oxide sol dropwise into the oil/ammonia column to form gel beads;

3) unloading of gel beads from the bottom of the oil/ammonia column, dynamic washing with washing liquid until the disappearance of the residual oil phase and ammonia in the washing liquid at a temperature of 20-50°C;

4) aging the balls in fatty alcohol for 4-36 hours at a temperature from 60°C to the boiling point of the alcohol;

5) unloading of granules followed by drying and calcination.

The disadvantage of the proposed method is the high energy costs for heating the washing liquid and fatty alcohol, as well as the long stage of keeping the spherical particles in fatty alcohol, which reduces the overall productivity of the process.

Thus, a simple and moderately resource-intensive method for obtaining spheroidal particles of aluminum oxide is not known from the state of the art. In addition, since the dehydrogenation catalyst is used in the moving bed mode (pneumatic lifting), it is important to obtain a catalyst carrier that has high mechanical crushing strength, i.e., capable of maintaining shape when exposed to various and significant impact and shear loads.

Disclosure of invention

The objective of the present invention is to develop a method for producing spheroidal particles of aluminum oxide that have high mechanical crushing strength, i.e. are capable of retaining their shape when exposed to various significant impact and shear loads.

The technical result of the present invention is an increase in the mechanical crushing strength and wear resistance during movement in the moving layer mode of the obtained spheroidal aluminum oxide particles by 30% relative to the comparison sample.

In addition, the resulting spheroidal aluminum oxide particles have a specific pore volume of 0.50 to 0.75 ^cm3 /g, a specific surface area of 85 to 125 ^m2 /g, a calculated pore diameter of 12 to 28 nm and a crushing strength of at least 35 N/granule, contain an element of group IV of the Periodic Table in an amount of 0.05 to 0.50 wt. %, and are also characterized by a spheroidality criterion of at least 0.90 and a bulk density of 0.50 to 0.75 g/ ^cm3 .

Spheroidal particles of aluminum oxide with the above characteristics can be obtained by a method comprising the following steps:

a) preparation of a molding solution by mixing water, mineral acid, a source of an element of group IV of the Periodic Table and a pore-forming agent;

b) stirring the molding solution obtained in stage a) until the components are completely dissolved;

c) introducing a weighed amount of aluminum hydroxide into the solution obtained in step b) to obtain a molding mixture and subsequent dispersion until the molding mixture is completely homogenized and a pH value of 2.0 to 4.5 is achieved;

d) forming the mixture obtained in step c) by a cold hydrocarbon-ammonia forming method in the presence of a stabilizing ammonium salt to obtain precursors of spheroidal particles;

e) washing the precursors of spheroidal particles obtained in step d) with an aqueous solution containing a polymer additive;

f) heat treatment of the particles obtained in step e).

The authors of the present invention have found that the ammonium salts formed during the molding of the mixture in step d) stabilize the passage of a drop of the molding mixture through the oil-water layer, thereby the obtained particles of the gel of the precursors of the spheroidal particles acquire a spheroidal shape. In addition, the authors of the present invention have found that washing in step e) of the precursors of the spheroidal particles obtained in step d) with an aqueous solution with a polymer additive concentration of 1 to 10 mass %, promotes the production of mechanically strong spheroidal particles of aluminum oxide after calcination in step f).

The present invention makes it possible to obtain highly porous, mechanically strong spheroidal particles of aluminum oxide with a mesoporous structure and a pore diameter range from 12 to 28 nm, suitable for use as a catalyst carrier in various catalytic processes, such as, for example, catalytic reforming, dehydrogenation of gaseous hydrocarbons, etc. In turn, the catalyst obtained on the basis of the spheroidal particles of aluminum oxide proposed in accordance with the present invention has high catalytic characteristics, has high wear resistance indicators when conducting tests for abrasion in a moving bed.

The advantage of the method for producing spheroidal particles of aluminum oxide proposed in accordance with the present invention is the use of a low concentration of ammonia (up to 15 mass %), which reduces emissions of gaseous ammonia into the atmosphere. Also, the use of a polymer additive at stage e) of washing allows for a reduction in the amount of pore-forming agent used at stage a) of preparing the molding solution, which reduces the cost of the final product.

Description of figures

Fig. 1 illustrates a diagram of a setup for testing the wearability index of a carrier.

Fig. 2 illustrates the results of determining the wear index of the carrier.

Detailed description of the invention

The following is a detailed description of various aspects and embodiments of the present invention.

In one aspect, the present invention relates to spheroidal particles of aluminum oxide having a specific pore volume of 0.50 to 0.75 ^cm3 /g, a specific surface area of 85 to 125 ^m2 /g, a calculated pore diameter of 12 to 28 nm and a crushing strength of at least 35 N/granule, containing an element of group IV of the Periodic Table in an amount of 0.05 to 0.50 wt.%, and are also characterized by a spheroidality criterion of at least 0.90 and a bulk density of 0.50 to 0.75 g/ ^cm3 .

The resulting spheroidal aluminum oxide particles have a specific pore volume of 0.50 to 0.75 ^cm3 /g, preferably 0.55 to 0.70 ^cm3 /g, more preferably 0.60 to 0.65 ^cm3 /g.

The resulting spheroidal aluminum oxide particles have a specific surface area of 85 to 125 ^m2 /g, preferably 90 to 110 ^m2 /g, more preferably 95 to 105 ^m2 /g.

The resulting spheroidal aluminum oxide particles are characterized by a calculated pore diameter of 12 to 28 nm, preferably 15 to 25 nm, more preferably 18 to 21 nm.

The resulting spheroidal aluminum oxide particles are characterized by a mechanical crushing strength of at least 35 N/granule, preferably at least 40 N/granule, more preferably at least 45 N/granule.

The resulting spheroidal aluminum oxide particles are characterized by a bulk density of preferably from 0.55 to 0.70 g/ ^cm3 , more preferably from 0.60 to 0.65 g/ ^cm3 .

The resulting spheroidal alumina particles have an average diameter of from about 0.2 to about 10 mm, preferably from about 0.5 to about 5 mm, most preferably from about 1 to about 3 mm.

The resulting aluminum oxide particles are spheroidal, i.e. have a shape close to a sphere. Thus, the majority of the aluminum oxide particles have a spheroidal shape with minor deviations, where "the majority" means at least more than 80% of the particles, preferably more than 90% of the particles, more preferably more than 95% of the particles.

The resulting spheroidal aluminum oxide particles are characterized by a spheroidality criterion of at least 0.80, preferably at least 0.90, more preferably at least 0.92.

The spheroidality criterion is understood as the ratio of the maximum and minimum Feret diameters (K _sph = d _Fmax / d _Fmin ).

The Feret diameter (d _F ) is the distance between two parallel tangents that touch the projection of the particle on opposite sides of it. The tangents must not intersect the edge of the projection of the particle at any point.

The maximum d _Fmax and minimum d _Fmin Feret diameters are measured by rotating the tangents from 0 to 360° (relative to any direction of the particle). The measurements are carried out using an optical method, for example, on the Analysette 28 Imagesizer device. A sample of calcined spheroidal particles of aluminum oxide is poured into a specialized chamber of the device and the length of the sides of the granules and the number of granules are measured using the camera. Then the program calculates the percentage of spheroidal particles in the sample from the data obtained.

In another preferred embodiment of the invention, the spheroidal particles of aluminum oxide contain an element of group IV of the Periodic Table in an amount of from 0.10 to 0.40 mass %, preferably from 0.15 to 0.25 mass %.

The following elements can be used as elements of group IV of the Periodic Table: tin, germanium, lead or mixtures thereof. Preferably, tin is used. In addition to elements of group IV of the Periodic Table, other elements known from the prior art as elements improving the performance characteristics of the catalyst, such as gallium, indium, zinc, manganese or mixtures thereof, can also be present in the spheroidal particles according to the present invention, in a total amount of up to 1.5 mass % of the catalyst mass.

In one aspect, the present invention relates to a method for producing spheroidal particles of aluminum oxide, comprising the following steps:

a) preparation of a molding solution by mixing water, mineral acid, a source of an element of group IV of the Periodic Table and a pore-forming agent;

b) stirring the molding solution obtained in stage a) until the components are completely dissolved;

c) introducing a weighed amount of aluminum hydroxide into the solution obtained in step b) to obtain a molding mixture and subsequent dispersion until the molding mixture is completely homogenized and a pH value of 2.0 to 4.5 is achieved;

d) forming the mixture obtained in step c) by a cold hydrocarbon-ammonia forming method in the presence of a stabilizing ammonium salt to obtain precursors of spheroidal particles;

e) washing the precursors of spheroidal particles obtained in step d) with an aqueous solution containing a polymer additive;

f) heat treatment of the particles obtained in step e).

Stage a) preparation of molding solution

In the context of the present invention, water includes, but is not limited to, distilled, deionized, demineralized, osmotic, bidistilled water.

Hydrochloric acid, nitric acid, sulfuric acid, preferably hydrochloric acid, nitric acid, most preferably hydrochloric acid are used as mineral acids.

The mineral acid is an aqueous solution of mineral acid with a concentration of 5 to 25 mass %, preferably 10 to 15 mass %.

When obtaining spheroidal particles of aluminum oxide, a water-soluble compound of the element of group IV of the Periodic Table is used as a source, for example, tin bromide, tin (II) chloride, tin (IV) chloride, tin (IV) chloride pentahydrate, germanium tetraethoxide, germanium (IV) chloride, lead nitrate, lead acetate, lead chlorate, etc.

C2-C6 di- or tribasic organic acids are used as a pore-forming agent. Examples of such acids include, but are not limited to, oxalic, tartaric, wine, citric, malic, and adipic acids. Preferably, wine, citric, and tartaric acids are used as a pore-forming agent, more preferably, citric and tartaric acids.

The molar ratio of water:acid:pore-forming agent:source of group IV element in step a) is preferably (1 to 10):(0.01 to 0.15):(0.0005 to 0.0025):(0.0005 to 0.0035), respectively, more preferably (3 to 7):(0.03 to 0.10):(0.0010 to 0.0020):(0.0010 to 0.0025), respectively.

The stage of preparation of the molding solution is carried out in any equipment known from the prior art for periodic or continuous operation, resistant to the effects of acids and alkalis.

The order of adding the components of the solution at stage a) can be any. Preferably, the mineral acid is added to the water first, then the source of the element of group IV, after which the pore-forming agent is added to the solution.

The preparation of the molding solution is carried out at room temperature and atmospheric pressure, where room temperature in accordance with the present invention should be considered to be a temperature of (20±10)°C. The definition of such a temperature as room temperature is known, in particular from GOST 9454-78 (clause 3.3), as well as the normative document "State Pharmacopoeia of the Russian Federation XII edition part 1" (applicable to the storage temperature of medicinal products).

Stage b) mixing the molding solution

The molding solution is mixed in any equipment known from the prior art, for example, using a planetary mixer at a speed of 50 to 400 rpm, preferably 100 to 200 rpm until the components are completely dissolved. The solubility of the solution components is assessed visually to ensure a complete absence of suspended solids in the solution, and the solution is mixed until it is completely transparent.

Stage c) obtaining the molding mixture

In step c), the aluminum hydroxide is aluminum hydroxide with the general chemical formula Al ₂ O ₃ ×nH ₂ O, where n = from 1 to 1.8, and in terms of phase composition is pseudoboehmite or boehmite, more preferably pseudoboehmite. In addition, the aluminum hydroxide used in the present invention may contain minor impurities of bayerite in an amount of up to 1 wt.%.

According to the present invention, the aluminum hydroxide used should have a pore volume of 0.60 to 1.30 ^cm3 /g, preferably 0.70 to 1.00 ^cm3 /g, most preferably 0.80 to 0.95 ^cm3 /g, and the particle size distribution should be monomodal with a D50 value of 6 to 12 μm.

Aluminum hydroxide is added to the molding solution in such a way that the concentration of aluminum oxide in the molding mixture is from 12 to 21 mass %, preferably from 14 to 18 mass %.

The mixing of the moldable mixture in step c) is carried out in any equipment known from the prior art, for example, using a planetary mixer at a speed of preferably 150 to 800 rpm, more preferably 300 to 600 rpm until the moldable mixture is completely homogenized, which means the large agglomerates of aluminum hydroxide are completely dispersed, and the pH of the moldable mass is reached in the range of 2.0 to 4.5, preferably 2.5 to 4.0, most preferably 3.0 to 3.5. If the pH of the mixture goes beyond the specified values, irreversible gelation of the moldable mass will occur. The pH value is measured using any equipment known from the prior art, for example, a pH meter from Mettler Toledo.

Stage d) of molding

Suitable methods for forming the precursors of spheroidal alumina particles in step d) are those described, for example, in the following documents: “Synthesis and characterization of millimetric gamma alumina spherical particles by oil drop granulation method” P. Ravindra et al., J. Porous. Mater. 19 (2012) 807–817; “Parametric investigation of g-alumina granule preparation via the oil-drop route” H. Atashi et al., Adv. Powder Technol. 28 (2017) 1356–1371; Ismagilov, Z. R. New technology for production of spherical alumina supports for fluidized bed combustion / Z. R. Ismagilov, R. A. Shkrabina, N. A. Koryabkina // Catalysis Today. 1999. - Vol. 47, No. 1–4. pp. 51-71; Preparation of Strong Alumina Supports for Fluidized Bed Catalysts. Volume 63 / M. N. Shepeleva [and others]. - Elsevier, 1991. - pp. 583-590; Wang, Z.-M. Sol-Gel Synthesis of Pure and Copper Oxide Coated Mesoporous Alumina Granular Particles / Z.-M. Wang, Y. S. Lin // Journal of Catalysis. - 1998. - T. 174, No. 1. - P. 43-51; Yang, Z. Sol-Gel Synthesis of Silicalite/γ-Alumina Granules / Z. Yang, Y. S. Lin // Industrial & Engineering Chemistry Research. - 2000. - T. 39, No. 12. - P. 4944-4948; Buelna, G. Sol-gel-derived mesoporous γ-alumina granules / G. Buelna, Y. S. Lin // Microporous and Mesoporous Materials. - 1999. - Vol. 30, No. 2. - P. 359-369; Structural and Mechanical Properties of Nanostructured Granular Alumina Catalysts / G. Buelna [et al.] // Industrial & Engineering Chemistry Research. 2003. - Vol. 42, No. 3. - P. 442-447. These methods are given as an example and do not limit the present invention.

In one embodiment of the present invention, step d) of molding the molding mixture obtained in step c) by the cold hydrocarbon-ammonia molding method comprises the following sequence of actions:

d.1 introducing an alkaline solution into the forming column;

d.2 introduction of a layer of hydrocarbon liquid;

d.3 feeding the molding mixture into the filled molding column;

d.4 formation of precursors of spheroidal particles;

d.5 keeping the obtained particles in an aqueous ammonia solution followed by separation from the aqueous ammonia solution.

The alkaline solution in step d.1 is a solution of a fatty acid, for example stearic, oleic, margaric, palmitic, preferably stearic, oleic, palmitic, more preferably oleic and stearic, in an aqueous ammonia mixture.

The concentration of ammonia in the aqueous solution is from 5 to 25 mass %, preferably from 10 to 20 mass %.

The concentration of fatty acid in the aqueous ammonia solution is from 0.01 to 0.20 mass %, preferably from 0.05 to 0.10 mass %.

Kerosene, decane, undecane, dodecane, preferably kerosene, undecane, dodecane, more preferably kerosene or dodecane are used as the hydrocarbon liquid in step d.2.

It is obvious to a person skilled in the art that the height of the column for forming the carrier and the height of the hydrocarbon liquid layer are determined by the required volume of the carrier. For example, if the forming column is a vertical tube with a detachable storage bin with a total height of the column together with the bin of 30 to 100 cm, preferably 50 to 80 cm, then the height of the hydrocarbon liquid layer is 0.5 to 15 cm, preferably 1 to 12 cm, more preferably 3 to 8 cm.

The feed of the molded mass into the molding column at stage d.3 is carried out using a pump at a constant volumetric speed through a distribution device that divides the flow into uniform drops.

At stage d.4, droplets of the molding mixture pass through the organic layer and enter a solution of fatty acid in a water-ammonia mixture. The resulting ammonium salts stabilize the passage of the droplet through the oil-water layer, thereby giving the resulting precursor particles a spheroidal shape.

Without wishing to be bound by any theory, the present inventors believe that fatty acids, when interacting with the ammonia solution, form stabilizing salts, which are ionic surfactants. These salts line up at the oil-water interface, reducing surface tension forces, and allow aluminum hydroxide particles to pass through the interface, forming precursors of spheroidal particles.

The precursors of spheroidal particles formed in step d.4 are then kept in a water-ammonia solution at room temperature and atmospheric pressure for 2 to 24 hours, preferably 4 to 18 hours, more preferably 8 to 15 hours in step d.5.

Separation from the aqueous ammonia solution occurs by displacing it with mineral oil, preferably industrial, hydraulic, and most preferably hydraulic oil.

Stage e) washing

In step e) the precursors of the spheroidal particles obtained in step d) are washed with an aqueous solution with a polymer additive. In this step the mineral oil is displaced with an aqueous solution of a polymer additive with a concentration of the polymer additive from 1 to 10 mass %, preferably from 2 to 8 mass %, most preferably from 3 to 6 mass %.

After displacing the oil, flushing is carried out with the said aqueous solution with a polymer additive for 30 to 240 minutes, preferably 100 to 180 minutes.

According to the present invention, the polymer additive is polyethylene oxide, methylcellulose, polyacrylamide, polyvinyl alcohol, polypropylene glycol, preferably polyacrylamide, polypropylene glycol.

Stage f) heat treatment

Next, the particles obtained after washing in stage e) are subjected to thermal treatment by drying and calcining using any method known from the prior art, the choice of which remains with a specialist in this field of technology.

The authors of the present invention recommend carrying out drying at a temperature of 30 to 150°C for 6 to 20 hours, preferably for 10 to 16 hours, calcination at a temperature of 400 to 1100°C for 2 to 16 hours, preferably 5 to 12 hours, using a step heating furnace at a heating rate of 0.5 to 10°C per minute, preferably 1 to 5°C per minute.

In one of the preferred embodiments of the invention, the spheroidal particles of aluminum oxide are used as a support for a catalyst in heterogeneous processes, for example, in the processes of catalytic reforming, hydrocracking, hydrogenation, dehydrogenation, dehydrocyclization of hydrocarbons or other organic compounds. More preferably, the use of the spheroidal particles of aluminum oxide proposed in accordance with the present invention is used to produce a catalyst for the processes of catalytic reforming and dehydrogenation of C ₂ -C ₄ gaseous hydrocarbons.

In another aspect, the present invention relates to a catalyst using as a support spheroidal particles of aluminum oxide obtained in accordance with the present invention.

The catalyst according to the present invention contains, based on the total weight of the catalyst:

- from 0.1 to 4.5 mass % of an element of group VIII of the Periodic Table;

- from 0.1 to 6.0 mass % of an element of group I and/or II of the Periodic Table;

- from 0.2 to 6.0 mass % halogen;

- spheroidal particles of aluminum oxide according to the present invention.

In some embodiments, the catalyst of the invention comprises from 0.15 to 2 wt.%, preferably from 0.15 to 0.8 wt.% of an element of group VIII of the Periodic Table, based on the total weight of the catalyst.

In some embodiments, the content of an element of group I and/or II of the Periodic Table in the catalyst according to the invention may be from 0.2 to 3 mass %, preferably from 0.5 to 2 mass %.

In some embodiments, the halogen content of the catalyst according to the invention may be from 0.2 to 3 wt.%, preferably from 0.2 to 2 wt.%.

Preferably, the catalyst according to the invention contains, based on the total weight of the catalyst:

- from 0.15 to 2 mass % of an element of group VIII of the Periodic Table;

- from 0.2 to 3 mass % of an element of group I and/or II of the Periodic Table;

- from 0.2 to 3 mass % halogen;

- spheroidal particles of aluminum oxide - the rest, where the spheroidal particles of aluminum oxide contain from 0.05 to 0.40 mass. % of an element of group IV of the Periodic Table.

Most preferably, the catalyst according to the invention contains, based on the total weight of the catalyst:

- from 0.15 to 0.8 mass % of an element of group VIII of the Periodic Table;

- from 0.5 to 2 mass % of an element of group I and/or II of the Periodic Table;

- from 0.2 to 2 mass % halogen;

- spheroidal particles of aluminum oxide - the rest, where the spheroidal particles of aluminum oxide contain from 0.15 to 0.25 mass. % of an element of group IV of the Periodic Table.

The catalyst according to the present invention may also contain other components that allow for an additional increase in its service life, activity or selectivity. Examples of such additives include, but are not limited to: rhenium, gallium, cerium, lanthanum, europium, indium, phosphorus, nickel, iron, tungsten, molybdenum, zinc, cadmium and others. Catalytically effective amounts of these components are typically from 0.01 to 5 wt. %, and they can be introduced into the catalyst by any suitable method during or after the catalyst is prepared, either separately or in a mixture.

The following elements may be used as the element of Group VIII of the Periodic Table: platinum, palladium, ruthenium, rhodium, iridium, osmium or mixtures thereof. In the catalyst, the element of Group VIII may be present as a compound such as an oxide, sulfide, halide, or oxyhalide, in chemical combination with one or more other ingredients of the composite or as an elemental metal. The preferred element of Group VIII is platinum.

In some embodiments, the catalyst of the invention comprises from 0.15 to 2 wt.%, preferably from 0.15 to 0.8 wt.% of an element of group VIII of the Periodic Table, based on the total weight of the catalyst.

The following elements can be used as elements of groups I and II of the Periodic Table: calcium, potassium, sodium, magnesium, lithium, strontium, barium, beryllium or mixtures thereof. The preferred element is potassium.

In some embodiments, the content of an element of group I and/or II of the Periodic Table in the catalyst according to the invention may be from 0.2 to 3 mass %, preferably from 0.5 to 2 mass %.

An element of group VII of the Periodic Table, such as chlorine, bromine, is used as a halogen; chlorine is preferably used.

In some embodiments, the halogen content of the catalyst according to the invention may be from 0.2 to 3 wt.%, preferably from 0.2 to 2 wt.%.

According to the present invention, a catalyst is obtained based on spheroidal alumina particles as described above, with an average diameter of from about 0.2 to about 10 mm, preferably from about 0.5 to about 5 mm, most preferably from about 1 to about 3 mm.

The term "spheroidal" means that the majority of the catalyst particles are spheroidal in shape with minor variations, where "majority" means at least more than 80% of the particles, preferably more than 90% of the particles, more preferably more than 95% of the particles.

Implementation of the invention

The present invention is more particularly described in the following examples, which are given solely to illustrate the present invention and do not limit it.

In accordance with the present invention, the mechanical crushing strength is determined using a single-column benchtop universal testing machine Lloyd Instruments LS1 (LFPlus) in accordance with the method described in the standard ASTM D4179-11. The average crushing strength is determined based on the results of crushing at least 100 particles of the sample. It is possible to analyze a larger number of particles in order to increase the accuracy of determining the mechanical crushing strength.

Example 1 (comparative). Obtaining spheroidal particles of aluminum oxide by the hydrocarbon-ammonia molding method.

The acquisition included the following stages:

a) The molding solution was obtained by adding 2 g of tin chloride, 50 g of hydrochloric acid to 2000 g of water;

b) The solution was stirred until completely dissolved using a planetary mixer at a stirring speed of 100 rpm;

c) 300 g of pseudoboehmite was added to the molding solution and the molding mixture was dispersed to a homogeneous state using a planetary mixer with a mixing speed of 300 rpm. The pH of the molded mass was 3.0;

d) Then the molding mixture was pumped into the column using a peristaltic pump through a special flow distributor into uniform drops. The upper part of the column was filled with a 10 cm high layer of petroleum solvent, the lower part of the column was filled with a 0.6 wt. % solution of Tween-80 in a water-ammonia mixture containing 25 wt. % ammonia. The resulting precursors of spheroidal particles were left in the column for 4 hours. Then the solution was displaced with petroleum solvent;

e) The petroleum solvent was displaced with distilled water, then the particles were washed with water for 180 minutes;

f) After washing, the particles were dried stepwise at 40°C for 8 h, then at 150°C for 6 h. After drying, the particles were calcined stepwise at 450°C for 2 h, then at 1000°C for 2 h, heating rate 3°C/min.

Spheroidal particles of aluminum oxide with a specific surface area of 80 ^m2 /g, a specific pore volume of 0.52 ^cm3 /g, a pore diameter of 10 nm, and a mechanical crushing strength of 25 N/granule were obtained. The spheroidality criterion of the obtained particles was 0.80. The mass fraction of spheroidal particles was 50%. The remaining particles were rough, non-spheroidal particles.

Example 2. Obtaining spheroidal particles of aluminum oxide by the method of cold hydrocarbon-ammonia molding.

The acquisition included the following stages:

a) The molding solution was prepared by adding 2 g of tin chloride, 50 g of hydrochloric acid and 1.5 g of citric acid to 2000 g of water;

b) The solution was stirred until completely dissolved using a planetary mixer at a stirring speed of 100 rpm;

c) 400 g of pseudoboehmite was added to the molding solution and the molding mixture was dispersed to a homogeneous state using a planetary mixer with a mixing speed of 300 rpm. The pH of the molded mass was 3.0;

d) Then the molding mixture was pumped into the column through a special flow distributor into uniform drops using a peristaltic pump. The upper part of the column was filled with a 10 cm high layer of kerosene, the lower part of the column was filled with a 0.1 wt. % solution of stearic acid in an aqueous ammonia mixture containing 10 wt. % ammonia. The obtained precursors of spheroidal particles were left to stand in a solution of fatty acid in an aqueous ammonia mixture for 15 hours. Then the solution was displaced with hydraulic oil;

e) The hydraulic oil was displaced with a 6 wt.% aqueous solution of polyethylene oxide, and then the particles were washed with this solution for 240 minutes;

f) After washing, the particles were dried stepwise at 40°C for 8 h, then at 150°C for 6 h. After drying, the particles were calcined stepwise at 450°C for 2 h, then at 1000°C for 2 h, heating rate 3°C/min.

Spheroidal particles of aluminum oxide with a specific surface area of 100 ^m2 /g, a specific pore volume of 0.70 ^cm3 /g, a pore diameter of 23 nm, and a mechanical crushing strength of 40 N/granule were obtained. The spheroidality criterion of the obtained particles was 0.96. The mass fraction of spheroidal particles was 98%.

Example 3

In this example, unlike Example 2, at stage a) citric acid was replaced with oxalic acid, and at stage e) 6 wt.% polyethylene oxide solution was replaced with 4 wt.% polyacrylamide solution.

Spheroidal particles of aluminum oxide with a specific surface area of 105 ^m2 /g, a specific pore volume of 0.68 ^cm3 /g, a pore diameter of 20 nm, and a mechanical crushing strength of 50 N/granule were obtained. The spheroidality criterion of the obtained particles was 0.96. The mass fraction of spheroidal particles was 98%.

Example 4

In this example, in contrast to Example 2, at stage a) hydrochloric acid was replaced with nitric acid, at stage e) the precursors of spheroidal particles were washed for 120 min, at stage d) kerosene was replaced with dodecane.

Spheroidal particles of aluminum oxide with a specific surface area of 105 ^m2 /g, a specific pore volume of 0.65 ^cm3 /g, a pore diameter of 18 nm, and a mechanical crushing strength of 55 N/granule are obtained. The spheroidality criterion of the obtained particles is 0.96. The mass fraction of spheroidal particles was 98%.

Example 5

In comparison with Example 2, the method for obtaining spheroidal particles differed in step f) by calcination. After drying, the particles were calcined stepwise at a temperature of 450°C for 2 h, then at a temperature of 950°C for 1 h, the heating rate was 3°C/min.

Spheroidal particles of aluminum oxide with a specific surface area of 125 ^m2 /g, a specific pore volume of 0.52 ^cm3 /g, a pore diameter of 12 nm, and a mechanical crushing strength of 40 N/granule were obtained. The spheroidality criterion of the obtained particles was 0.96. The mass fraction of spheroidal particles was 98%.

Thus, the proposed carriers can be used to prepare catalysts for the processes of dehydrogenation of _C2 - _C4 hydrocarbons and catalytic reforming, taking place in a moving bed, since they have high mechanical strength and a spheroidality criterion of more than 0.98.

Example 6 (comparative). Obtaining catalyst A (composition 0.3% Pt - 1.0% K - 1.0% Cl/Sn(0.2%)-Al ₂ O ₃ ).

10.0 g of spheroidal particles prepared according to the procedure described in Example 1 were impregnated with a solution containing 0.965 ml of a chloroplatinic acid solution H ₂ PtCl ₆ with a Pt concentration of 31.87 mg/ml and 6.84 ml of distilled water. The wet particles were kept in air at room temperature for 2 h, dried in a drying oven at 60°C for 1 h and at 120°C for 2 h. The Pt-containing catalyst was placed in a reactor and impregnated with a solution containing 4.1 ml of a potassium chloride solution KCl with a K concentration of 25.0 ml/ml in 3.7 ml of distilled water. The wet particles were kept in air at room temperature for 2 h, then in a drying oven at 60°C for 1 h and at 120°C for 2 h. The particles were calcined in a muffle furnace at 550°C for 2 h. The temperature was raised to the specified values at a rate of 10°C/min.

The resulting catalyst was reduced in the following manner: the system was purged with argon at a rate of 50 ^cm3 /min for 20 min, then hydrogen was fed into the reactor instead of argon at a rate of 50 ^cm3 /min. The reactor was heated in a hydrogen flow at a rate of 15°C/min to 550°C and maintained at this temperature for 2 h.

Example 7. Obtaining catalyst B (composition 0.3% Pt - 1.0% K - 1.0% Cl/Sn(0.2%)-Al ₂ O ₃ ).

The carrier was obtained by the method described in Example 2. The application of platinum, potassium, chlorine and subsequent reduction of the catalyst were carried out by the same method as in Example 6. The difference consisted in the addition of a stage of calcination of the dried carrier after applying chloroplatinic acid H ₂ PtCl ₆ from the solution to it. The dried granules of the Pt-containing catalyst were calcined in a muffle furnace at 550°C for 2 h. The temperature was raised to the specified values at a rate of 10°C/min.

Example 8. Obtaining catalyst B (composition 0.3% Pt - 1.0% K - 1.0% Cl/Sn(0.2%)-Al ₂ O ₃ ).

The carrier was obtained using the method described in Example 3. The application of platinum, potassium, chlorine and subsequent reduction of the catalyst was carried out using the same method as in Example 7. The difference consisted in adding hydrochloric acid HCl to the solution of chloroplatinic acid H ₂ PtCl ₆ at a rate of 5 mol of HCl per 1 mol of chloroplatinic acid H ₂ PtCl ₆ .

Example 9. Obtaining catalyst G (composition 0.3% Pt - 1.0% K - 1.0% Cl/Sn(0.2%)-Al ₂ O ₃ ).

The carrier was obtained using the method described in Example 3. The application of platinum, potassium, chlorine and subsequent reduction of the catalyst was carried out using the same method as in Example 8. The difference consisted in adding hydrochloric acid HCl to the potassium chloride KCl solution at a rate of 1 mol HCl per 1 mol potassium chloride KCl.

Example 10. Obtaining catalyst D (composition 0.3% Pt - 1.0% K - 1.0% Cl/Sn(0.2%)-Al ₂ O ₃ ).

The support was obtained by the procedure described in Example 4. The deposition of platinum, potassium, chlorine and subsequent reduction of the catalyst were carried out by the same procedure as in Example 9. The difference consisted in the deposition of potassium on the support from a solution of potassium hydroxide KOH. For this purpose, the Pt-containing catalyst precursor was placed in a reactor and impregnated with a solution containing 4.1 ml of a solution of potassium hydroxide KOH with a concentration of K equal to 25.0 ml/ml in 3.7 ml of distilled water. The wet granules were kept in air at room temperature for 2 hours, then in a drying oven at 60°C for 1 hour and at 120°C for 2 hours. The granules were calcined in a muffle furnace at 550°C for 2 hours. The temperature was raised to the specified values at a rate of 10°C/min.

The resulting catalyst was reduced in the following manner: the system was purged with argon at a rate of 50 ^cm3 /min for 20 min, then hydrogen was fed into the reactor instead of argon at a rate of 50 ^cm3 /min. The reactor was heated in a hydrogen flow at a rate of 15°C/min to 550°C and maintained at this temperature for 2 hours.

Example 11 illustrates the use of the obtained catalysts in the propane dehydrogenation reaction (PDH).

The obtained catalysts A, B, C, D and D were studied in the propane dehydrogenation reaction. The studies on comparative testing of catalysts in the propane dehydrogenation reaction were carried out according to the following procedure. At the initial stage, the reactor was heated at a rate of 20°C/min to 110°C and maintained at this temperature for 1 hour. The catalyst was reduced in a hydrogen stream while heating at a rate of 15°C/min to 650°C and maintained at this temperature for 2 hours. The propane dehydrogenation reaction was carried out at 650°C for 2 hours with the following gas feed mode: C ₃ H ₈ - 30 cm ³ /min, H ₂ - 6.0 cm ³ /min.

The propane conversion on catalyst A at the beginning of the test is 63% and decreases to 50% after 4 hours. On catalysts B, C, G and D, the propane conversion smoothly decreases from 63% to 59% during the 4-hour test. The propylene selectivity for catalyst A increases from 75% to 90% after 4 hours. For catalysts B, C, G and D, the propylene selectivity is in the range of 83-88%. It can be said that the intermediate calcination of the Pt-containing catalyst helps to stabilize the catalytic properties of the resulting catalyst, allowing the propane conversion and propylene selectivity to be maintained within a narrow range.

Example 12. Obtaining a reforming catalyst based on the particles obtained in Example 5.

The catalyst was obtained according to the method described in document RU2767882, testing was carried out according to the method specified in the same document. As a result, a spheroidal reforming catalyst with a specific surface of 120 ^m2 /g, a specific pore volume of 0.50 ^cm3 /g, a pore diameter of 11 nm, and a crushing strength of 40 N/granule was obtained. The spheroidality criterion of the obtained particles is 0.96. The mass fraction of spheroidal particles is 98%.

Thus, the obtained catalysts based on the supports prepared according to examples 2, 3, 4 and 5 have high activity and selectivity, high mechanical strength, and a spheroidality criterion of more than 0.98.

Example 13 illustrates the abrasion resistance of carrier and catalyst samples as a function of their spheroidality.

Samples of the spheroidal aluminum oxide particles obtained in Example 3 and commercial samples of the carrier and catalyst were tested for resistance to abrasion in a moving bed using a setup including a glass tube 1 of variable cross-section, an absorber 2 and a gas flow controller 3. The setup diagram (A) and a drawing of the glass tube (B) are shown in Fig. 1.

The glass tube included the following sections:

• Nitrogen introduction through the branch pipe and its distribution on the mesh wad 4 (cell size 1 mm);

• Working part with an internal diameter of 18 mm and a length of 900 mm;

• Conical expansion to 46mm internal diameter to trap spherical media and prevent it from being carried away from the tube.

Additionally, a mesh wad 5 with a cell size of 1 mm is installed at the exit of the tube.

Nitrogen was supplied to the bottom of the tube through a gas flow regulator with a supply range of 200-1600 l/h. At the exit of the tube, the gas passed through a bubbler filled with water to trap dust particles.

The abrasion resistance test of the carriers was carried out according to the procedure below:

1. The test sample weighing 50 g was calcined in a muffle furnace at a temperature of 370°C for 3 hours to remove sorbed moisture.

2. After cooling in the oven to a temperature of 150°C, the sample was placed in a desiccator to cool to room temperature.

3. The cooled sample was weighed to an accuracy of 0.01 g.

4. The test sample was placed in glass tube 1. To do this, the nitrogen outlet tube was disconnected at the top of the glass tube, mesh wad 5 was removed and the sample was poured into the tube through a funnel.

5. Installed wad 5 and the outlet pipe in place.

6. Set the nitrogen flow rate to 1000-1200 l/h on the gas flow regulator. Make sure that the spheroidal particles of the test sample began to move in portions up the tube with a gradual fall down. Also check that no particles slipped through the conical part of the tube. If necessary, change the gas flow rate at the tube inlet.

7. The test was carried out for a specified period of time: from 20 to 120 hours. The duration of the test could be changed based on the properties of a specific sample.

8. After the test time had elapsed, the supply of nitrogen to the tube was stopped.

9. Disconnect the gas inlet tube at the bottom of glass tube 1 and remove the rubber seal with polytetrafluoroethylene tape.

10. Place a large polyethylene bag (gripper) under the lower end of the tube and remove the mesh wad 4 with tweezers so that the tested carrier would spill into the bag. It is important not to lose a single particle of the tested sample.

11. Removed the bag with the collected material.

12. If it was necessary to collect dust for analysis, a small gripper was attached to the lower end of the tube with tape and the dust was poured into a bag by tapping on the upper part of the tube. If necessary, the tube can be blown from top to bottom with nitrogen.

13. The gripper with the collected dust sample was disconnected.

14. The tube was purged with nitrogen to remove residual dust. A brush should be used to remove dust particles that had settled on the walls in the expanded part of the tube. The recommended nitrogen flow rate for purging was 1200 l/hour, and the purging duration was about 5 minutes.

15. The extracted sample was calcined in a muffle furnace at a temperature of 370°C for three hours to remove sorbed moisture.

16. After cooling in the oven to a temperature of 150°C, the sample was placed in a desiccator to cool to room temperature.

17. The cooled sample was weighed with an accuracy of 0.01 g.

The relative mass loss of the studied sample was calculated using the formula:

(1),

Where - relative mass loss,

M ₀ - initial mass of the sample,

M ₁ - final mass of the sample,

The results of the comparative test of the abrasion resistance of the carriers are presented in Fig. 2, the results of the test of the abrasion resistance of the samples for 96 hours are presented in Table 1.

Table 1. The value of the relative mass loss of the carrier during abrasion for 96 hours

Commercial sample of catalyst Commercial sample of the carrier Carrier according to Example 3 Crushing strength, N/granule 30 30 55 The meaning of the spheroidality criterion 0.85 0.87 0.96 Relative mass loss, % 6.93 6.70 4.64

It is evident from the results of the tests that the sample of spheroidal aluminum oxide particles prepared according to Example 3 is more resistant to abrasion in a moving bed than the commercial samples of the carrier and catalyst due to its high degree of spheroidality. It is also evident from the data in Fig. 2 that the particles according to Example 3 achieve the same mass loss as the commercial samples only after 144 hours of testing.

Thus, the proposed spheroidal carriers have good abrasion resistance.

Claims (53)

1. Spheroidal particles of aluminum oxide having a specific pore volume from 0.50 to 0.75 ^cm3 /g, a specific surface area from 85 to 125 ^m2 /g, a calculated pore diameter from 12 to 28 nm and a crushing strength of at least 35 N/granule, characterized in that they contain an element of group IV of the Periodic Table in an amount of from 0.05 to 0.50 mass %, are characterized by a spheroidality criterion of at least 0.90 and a bulk density of from 0.50 to 0.75 g/ ^cm3 . 2. Spheroidal particles of aluminum oxide according to claim 1, having a specific pore volume of from 0.55 to 0.70 ^cm3 /g, preferably from 0.60 to 0.65 ^cm3 /g. 3. Spheroidal particles of aluminum oxide according to claim 1, having a specific surface area of 90 to 110 ^m2 /g, preferably 95 to 105 ^m2 /g. 4. Spheroidal particles of aluminum oxide according to claim 1, characterized by a calculated pore diameter of 15 to 25 nm, preferably 18 to 21 nm. 5. Spheroidal particles of aluminum oxide according to claim 1, characterized by a mechanical crushing strength of at least 40 N/granule, preferably at least 45 N/granule. 6. Spheroidal particles of aluminum oxide according to claim 1, characterized by a spheroidality criterion of preferably at least 0.92. 7. Spheroidal particles of aluminum oxide according to claim 1, characterized by a bulk density of preferably from 0.55 to 0.70 g/ ^cm3 , more preferably from 0.60 to 0.65 g/ ^cm3 . 8. Spheroidal particles of aluminum oxide according to claim 1, characterized in that they have an average diameter of from 0.2 to 10 mm, preferably from 0.5 to 5 mm, most preferably from 1 to 3 mm. 9. Spheroidal particles of aluminum oxide according to claim 1, characterized in that they contain an element of group IV of the Periodic Table in an amount of from 0.10 to 0.40 mass %, preferably from 0.15 to 0.25 mass %. 10. Spheroidal particles of aluminum oxide according to claim 9, characterized in that they contain tin, germanium, lead or mixtures thereof as an element of Group IV of the Periodic Table, preferably tin is used. 11. Spheroidal particles of aluminum oxide according to claim 1, characterized in that they additionally contain gallium, indium, zinc, manganese or mixtures thereof. 12. The use of spheroidal particles of aluminum oxide according to any one of claims 1-11 as a support for a catalyst in heterogeneous processes. 13. The use of spheroidal particles of aluminum oxide according to claim 12, wherein the catalyst is a catalyst for the dehydrogenation of gaseous hydrocarbons or a reforming catalyst. 14. A method for producing spheroidal particles of aluminum oxide, comprising the following stages: a) preparing a molding solution by mixing water, mineral acid, a source of an element of group IV of the Periodic Table and a pore-forming agent in a molar ratio of water: acid: pore-forming agent: source of an element of group IV (from 1 to 10): (from 0.01 to 0.15): (from 0.0005 to 0.0025): (from 0.0005 to 0.0035), respectively; b) stirring the molding solution obtained in step a) until the components are completely dissolved; c) introducing a weighed amount of aluminum hydroxide into the solution obtained in step b) to obtain a molding mixture and subsequent dispersion until the molding mixture is completely homogenized and a pH value of 2.5 to 4.5 is achieved; d) forming the mixture obtained in step c) by the hydrocarbon-ammonia forming method in the presence of a stabilizing ammonium salt to obtain precursors of spheroidal particles; e) washing the precursors of spheroidal particles obtained in step d) with an aqueous solution containing a polymer additive; f) thermal treatment of the particles obtained in step e) to obtain spheroidal particles of aluminum oxide having a specific pore volume of 0.50 to 0.75 ^cm3 /g, a specific surface area of 85 to 125 ^m2 /g, a calculated pore diameter of 12 to 28 nm, a crushing strength of at least 35 N/granule, a spheroidality criterion of at least 0.90 and a bulk density of 0.50 to 0.75 g/ ^cm3 . 15) The method according to claim 14, wherein in step a) the mineral acid is hydrochloric acid, nitric acid, sulfuric acid, preferably is hydrochloric acid, nitric acid, most preferably is hydrochloric acid. 16) The method according to claim 14, wherein in step a) the mineral acid is an aqueous solution of mineral acid with a concentration of 5 to 25 wt.%, preferably 10 to 15 wt.%. 17. The method according to claim 14, wherein in step a) tin bromide, tin (II) chloride, tin (IV) chloride, tin (IV) chloride pentahydrate, germanium tetraethoxide, germanium (IV) chloride, lead nitrate, lead acetate, lead chlorate are used as a source of an element of group IV of the Periodic Table. 18. The method according to claim 14, wherein in step a) C2-C6 di- or tribasic organic acids are used as the pore-forming agent. 19. The method according to claim 18, wherein in step a) oxalic, tartaric, citric, malic, adipic acids are used as the pore-forming agent, preferably tartaric, citric, tartaric acids are used, more preferably citric, tartaric acids are used. 20. The method according to claim 14, wherein in step a) the molar ratio of water: acid: pore-forming agent: source of element of group IV is preferably (from 3 to 7): (from 0.03 to 0.10): (from 0.0010 to 0.0020): (from 0.0010 to 0.0025), respectively. 21. The method according to claim 14, wherein in step b) the mixing of the molding solution is carried out at a speed of 50 to 400 rpm, preferably 100 to 200 rpm, until the components are completely dissolved. 22. The method according to claim 14, wherein in step c) the aluminum hydroxide is aluminum hydroxide with the general chemical formula Al ₂ O ₃ ⋅nH ₂ O, where n is from 1 to 1.8. 23. The method according to claim 22, wherein in step c) the aluminium hydroxide has a phase composition of pseudoboehmite or boehmite, more preferably pseudoboehmite. 24. The method according to claim 22, wherein in step c) the aluminium hydroxide has a pore volume of from 0.60 to 1.30 ^cm3 /g, preferably from 0.70 to 1.00 ^cm3 /g, most preferably from 0.80 to 0.95 ^cm3 /g. 25. The method according to claim 22, wherein in step c) the aluminium hydroxide is characterised by a monomodal particle size distribution with a D50 value of 6 to 12 μm. 26. The method according to claim 14, wherein in step c) aluminium hydroxide is added to the moulding solution so that the concentration of aluminium oxide in the moulding mixture is from 12 to 21 mass %, preferably from 14 to 18 mass %. 27. The method according to claim 14, wherein in step c) the mixing of the moldable mixture is carried out at a speed of preferably from 150 to 800 rpm, more preferably from 300 to 600 rpm until the moldable mixture is completely homogenized. 28. The method according to claim 14, wherein in step c) the pH of the moldable mass is in the range from 2.5 to 4.0, preferably in the range from 3.0 to 3.5. 29. The method according to claim 14, wherein in step e) the concentration of the polymer additive is from 1 to 10 mass%. 30. The method according to claim 29, wherein in step e) the polymer additive is polyethylene oxide, methylcellulose, polyacrylamide, polyvinyl alcohol, polypropylene glycol, preferably is polyacrylamide, polypropylene glycol. 31. The method according to claim 14, wherein in step f) drying is carried out at a temperature of 30 to 150°C for 6 to 20 hours, preferably for 10 to 16 hours. 32. The method according to claim 14, wherein in step f) calcination is carried out at a temperature of 400 to 1100°C for 2 to 16 hours, preferably 5 to 12 hours. 33. The method according to claim 14, wherein step f) uses step heating of the furnace at a heating rate of 0.5 to 10°C per minute, preferably 1 to 5°C per minute. 34. The method according to claim 14, wherein the spheroidal particles of aluminum oxide are intended for use as a support for a catalyst in processes for the dehydrogenation of C2-C4 gaseous hydrocarbons and catalytic reforming, preferably intended for use as a support for a catalyst in processes for the dehydrogenation of C2-C4 gaseous hydrocarbons. 35. A catalyst for heterogeneous processes containing, based on the total mass of the catalyst, - from 0.1 to 4.5 mass % of an element of group VIII of the Periodic Table; - from 0.1 to 6.0 mass % of an element of group I and/or II of the Periodic Table; - from 0.2 to 6.0 mass % halogen; - spheroidal particles of aluminum oxide according to any one of claims 1-11. 36. The catalyst according to claim 35, containing from 0.15 to 2 mass %, preferably from 0.15 to 0.8 mass % of an element of Group VIII of the Periodic Table, based on the total mass of the catalyst. 37. The catalyst according to claim 35, containing an element of group I and/or II of the Periodic Table in an amount of from 0.2 to 3 mass %, preferably from 0.5 to 2 mass %. 38. The catalyst according to claim 35, containing halogen in an amount of 0.2 to 3 mass %, preferably containing halogen in an amount of 0.2 to 2 mass %. 39. The catalyst according to claim 35, in which platinum, palladium, ruthenium, rhodium, iridium, osmium or mixtures thereof are used as an element of Group VIII of the Periodic Table, preferably platinum is used. 40. The catalyst according to item 35, in which calcium, potassium, sodium, magnesium, lithium, strontium, barium, beryllium or mixtures thereof are used as elements of group I and/or II of the Periodic Table, preferably potassium is used. 41. The catalyst according to claim 35, which contains from 0.2 to 3 mass % of an element from groups I and/or II of the Periodic Table, preferably from 0.5 to 2 mass %. 42. The catalyst according to claim 35, in which chlorine is used as the halogen. 43. The catalyst according to claim 35, wherein the heterogeneous process is a process of reforming or dehydrogenating gaseous hydrocarbons.