RU2373175C1 - Method of dehydrogenating c3-c5 paraffin hydrocarbons - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of C₃-C₅ hydrocarbons through dehydrogenation of corresponding paraffin hydrocarbons n reactors with a fluid bed of micro-spherical chromia-alumina catalyst. Method is described for dehydrogenating C₃-C₅ paraffin hydrocarbons in fluid catalyst bed, containing oxides of chrome, potassium and a promoter, deposited on an alumina support which contains boehmite and up to 10 wt % hydrargillite, which is an aggregate in form of regular, including mimetic, and irregular double aggregates, consisting of hexagonal scaly crystals with size greater than 20 mcm.

EFFECT: increased efficiency of the process of dehydrogenating C₃-C₅ paraffin hydrocarbons, increased output of C₃-C₅ olefin hydrocarbons, reduced abrasive action on elements of a two-reactor installation for dehydrogenation when using chromia-alumina catalyst in a fluid bed.

5 cl, 2 tbl, 11 ex, 1 dwg

Description

The invention relates to the field of petrochemistry and, in particular, to the field of production of olefinic C ₃ -C ₅ hydrocarbons by dehydrogenation of the corresponding paraffin hydrocarbons in fluidized bed reactors of a microspherical chromium-chromium catalyst.

The dehydrogenation processes of paraffin hydrocarbons are among the largest in the petrochemical and organic synthesis technologies; they allow to obtain unsaturated compounds used as monomers for the production of synthetic rubbers, plastics, high-octane fuel components and other valuable products. The endothermic dehydrogenation of paraffins requires a process at a temperature of more than 500 ° C. The process is regulated by thermodynamic equilibrium and is carried out mainly in reactors with a fluidized bed of a microspherical catalyst, continuously circulating in the reactor-regenerator system. Process efficiency is determined by the performance of the catalyst used. Thus, the high yield of olefin hydrocarbons is primarily due to its activity and selectivity under specified conditions (dehydrogenation reaction temperature, pressure, feed stream rates), as well as mechanical stability and thermal stability of the catalyst during oxidative regeneration at temperatures above 600 ° C. The efficiency of the process is also determined by the number of forced shutdowns of technological equipment for the repair of some elements and structures of reactors and various auxiliary devices that are partially worn out.

The structural and mechanical properties of the catalyst determine its physical integrity and abrasive activity in the dynamic mode of the fluidized bed and in a variable redox environment, when the microspherical catalyst granules are subjected to significant mechanical stresses when interacting with each other and elements of technological equipment. The process in the presence of catalysts with insufficient mechanical strength is accompanied by the gradual abrasion of microspherical granules, the formation of fine catalyst fractions, which are subsequently carried out by the feed stream from the reaction zone, which impairs the heat and mass transfer characteristics of the fluidized bed and reduces the efficiency of paraffin dehydrogenation. Therefore, constant reimbursement of irreversible losses of the catalyst is required by periodically dosing fresh portions of it into the reactor. The use of high-strength catalysts with high abrasive effect contributes to the accelerated wear of process equipment. Therefore, when carrying out the process of dehydrogenation of paraffins, it is necessary to use not only highly active, selective and structurally stable catalysts, but also with low abrasive activity.

A known method for the dehydrogenation of paraffin hydrocarbons to the corresponding olefins in the presence of an aluminum chromium microspherical catalyst with a low abrasive effect. The process is carried out at a reaction temperature of 540-610 ° C, regeneration of 610-650 ° C, a volumetric feed rate of 100-300 h ^-1 and a fluidized bed density of 750 kg / m ³ (Bashkatov T.V., Zhigalin Y.L. Technology synthetic rubbers. - M.: Chemistry, 1980, 336 p.). The disadvantages of this method are both low yields of olefins and low selectivity of the process, and a high abrasion index of the used catalyst, which leads to its significant consumption rates during operation. The destruction of the catalyst in the process of dehydrogenation is accompanied by a decrease in its activity. Low mechanical strength is associated with the conditions of the synthesis of the catalyst, namely the application of the spray drying method of the catalyst suspension during the formation of granules (Kirpichnikov PL, Beresnev V.V., Panov L.M. Album of technological schemes of the main industries of the synthetic rubber industry. L .: Chemistry, 1986, 225 pp.). The resulting catalyst includes oxides of aluminum, chromium, potassium, silicon (RF patent No. 1736034, IPC B01J 37/02, 23/26, 21/04; publ. 20.01.95).

To increase the yield of olefins, it is proposed to dehydrogenate paraffin hydrocarbons in the presence of microspherical catalysts modified with high-temperature forms of aluminum oxides and promoted with silicon oxide (RF patent No. 1736034, IPC B01J 37/02, 23/26, 21/04; publ. 20.01.95), tin oxide (RF patent No. 2127242, IPC С07С 5/333, B01J 23/26, 23/18 // (B01J 23/26, 103: 10, 101: 32, 101: 42; publ. 10.03.99), oxide boron (RF patent No. 2156233, IPC С07С 5/333, 11/02, 11/06, 11/09; publ. 09/20/2000), zinc oxide (RF patent No. 2178398, IPC С07С 5/333, B01J 23/26 , B01J 23/06; publ. 20.01.02). The lack of data processor in the dehydrogenation of paraffin hydrocarbons is the use of catalysts with insufficient strength and low thermal stability, which also leads to high consumption rates of the catalyst.

In order to reduce the consumption rate of the catalyst and increase the efficiency of the process, it is proposed to carry out dehydrogenation of paraffins using a more durable microspherical aluminum-chromium catalyst with a low abrasion index of the granules. The improved mechanical characteristics of the catalyst are determined by the use of an alumina carrier with a layered X-ray amorphous structure, which is a product of the thermochemical activation of hydrargillite. The synthesis of the catalyst is carried out by applying chromium, alkali metal and various promoters to the carrier granules (RF patent No. 2148430, IPC B01J 23/26, B01J 37/02, C07C 5/333, B01J 23/26, B01J 101: 20, B01J 101 : 42, B01J 101: 50, B01J 101: 32, B01J 103: 10, B01J 103: 18, publ. 05.10.2000; RF patent No. 2200143, IPC С07С 5/333, B01J 23/26, 37/02, publ. March 10, 2003; RF patent No. 2271860, IPC B01J 23/26, B01J 23/04, B01J 21/04, B01J 21/06, B01J 23/70, C07C 5/333, publ. March 15, 2005). The loose porous surface of the support used allows one to effectively intercalate into the interlayer space and firmly fix the catalyst components on its surface, which leads to its high activity, selectivity and low abrasion index. The disadvantage of the above processes for the dehydrogenation of paraffin hydrocarbons is the use of catalysts with high abrasive activity, which leads to fast and intensive abrasion of technological elements of a two-reactor plant.

The closest technical solution to the proposed method is the process of dehydrogenation of paraffin hydrocarbons in a fluidized bed in the presence of an aluminum chromium catalyst synthesized using a microspherical support, which is an oxygen-containing aluminum compound of the formula Al ₂ O ₃ · nH ₂ O of an X-ray amorphous structure obtained by rapid partial dehydration of hydrargillite (patent RF №2271248, IPC B01J 21/04, C01F 7/02, publ. 10.03.2006). The catalyst carrier (figure 1) is a spherulitic particle size of from 20 to 250 μm, consisting of a large number of smaller ones from 1 to 10 μm in size of hexagonal rod-shaped crystals. The carrier is characterized by a system of flat parallel pores corresponding to cleavage along the (001) face, contains interlayer water in an amount corresponding to n = 0.5-1.0, has a total specific surface area of 80-250 m ² / g and a pore volume of 0.1 -0.3 cm ³ / g. The structural characteristics of spherulites determine a high external specific surface area of the catalyst and a large number of contacts in the form of protruding sharp edges and faces that actively affect equipment and abrade the walls of reactors, transfer pipes, and other technological elements. Low bulk density and high abrasive activity of the catalyst reduce the effectiveness of the process of dehydrogenation of paraffins.

The objective of the invention is to increase the efficiency of the dehydrogenation process of C ₃ -C ₅ paraffin hydrocarbons, increase the yield of C ₃ -C ₅ olefinic hydrocarbons, reduce the abrasive effect on the elements of a two-reactor dehydrogenation unit during operation of an aluminum chromium catalyst in a fluidized bed.

The problem is solved by the method of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons in a fluidized bed of a catalyst containing chromium, potassium oxides and a promoter deposited on an alumina carrier containing boehmite and up to 10 wt.% Hydrargillite, which is an aggregate in the form of regular ones, including mimetic and irregular splices of twins consisting of hexagonal plate crystals larger than 20 microns in size. The alumina carrier may have an external specific surface area of 0.01-1 m ² / g. The alumina carrier may have a bulk density of at least 1.2 g / cm ³ . The catalyst may have a bulk density of at least 1.3 g / cm ³ . The catalyst as a promoter contains copper oxide, zinc oxide, manganese oxide, tin oxide, boron oxide or zirconium oxide and may have a composition, wt.%:

chromium oxide 10-20 potassium oxide 0.1-5 promoter 0.1-5 aluminium oxide rest

Doubles are understood as regular and irregular intergrowths of two or more crystals having an unparallel orientation in space. Mimetic doubles are repeated doubles of low-symmetric crystals imitating highly symmetric crystals (Bokiy GD Crystal chemistry. M .: Nauka, 1971, 400 p.).

The value of the external specific surface is understood as the geometric external surface of the granules of the alumina carrier calculated from the particle sizes and its components, taking into account the particle shape coefficient and reduced to one gram of carrier (Plachenov T.G., Kolosensev S.D. Porometry. L .: Chemistry , 1988, 176 p.). The value of the total specific surface takes into account the external geometric surface of the granules and the inner surface of the pores of the carrier, determined by the BET method (S. Gregg, C. Sing. Adsorption, specific surface, porosity. M: Mir, 1984, 306 p.).

As a result, the claimed process for dehydrogenation of paraffin hydrocarbons is carried out more efficiently, which is reflected in (1) a decrease in the number of shutdowns of the two-reactor system for repairs due to the use of a microspherical catalyst with low abrasive activity, which, in contrast to the prototype, has a small number of protruding fragments in the form of faces and edges of individual crystals, interacting with the surface of the walls of the reactors, transfer pipes and other technological elements; (2) a decrease in the consumption rate of the catalyst due to greater structural stability, increased mechanical strength and low external specific surface area of the granules of the alumina support, which ensures the physical integrity of the catalyst particles that retain their size, both when interacting with each other in a dynamic mode of a fluidized bed, and during the formation and burning of coke deposits; (3) an increase in the yield of olefin hydrocarbons due to the use of a highly active and selective catalyst with an increased bulk density and tight packing of large plate crystals in alumina support granules tending in shape to a single crystal, which in turn allows the process to be carried out at higher feed flow rates.

In contrast to the proposed method, the process of dehydrogenation of paraffins in the prototype is carried out in the presence of an alumina-chromium catalyst of a similar composition, but synthesized using an alumina carrier, the granules of which are spherulites composed of a large number of small, from 1 to 10 microns, prismatic rod-shaped crystals. The lower packing density of the crystals leads to a higher external specific surface area and increased abrasive activity of the catalyst due to the significantly larger number of protruding fragments of individual crystals constituting the catalyst granule and in contact with the surface of the reactors, walls of transfer pipes, cyclones and other equipment under the conditions of reaction and regeneration. The structural features of the carrier obtained by the prototype determine the high consumption rates of the catalyst during operation due to mechanical destruction of the granules during the formation and burning of coke deposits. In addition, such a catalyst has a lower bulk density, therefore, the dehydrogenation process is carried out with lower feed flow rates and lower yield of the target olefin.

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out at a temperature of 560-580 ° C, the volumetric feed rate of 300-400 h ^-1 . Regeneration is carried out with air at a temperature of 650 ° C, keeping the catalyst for 30 minutes. The process is carried out in a flow-through installation with a quartz tube reactor in a fluidized bed of a catalyst. The volume of the loaded catalyst is 100 cm ³ . The process is carried out in cycles in the following sequence: dehydrogenation - 15 minutes, inert gas purge - 5 minutes, air regeneration - 30 minutes, inert gas purge - 5 minutes, then the cycles are repeated. After holding the catalyst at a temperature of 580 ° C for 2 hours, two idle cycles are carried out. In the third cycle, during the dehydrogenation reaction, contact gas is taken from 6 to 15 minutes inclusive in an amount of 1 liter. Contact gas is analyzed by gas chromatography. According to the results of chromatographic analysis, the yield of the target olefin on the passed and decomposed paraffin is calculated — the activity and selectivity of the catalyst, respectively.

The catalyst is prepared by impregnating the alumina support with aqueous solutions of the precursors of chromium oxide, potassium oxide, a promoter, which is at least one of the oxides selected from the group: copper oxide, zinc oxide, manganese oxide, tin oxide, boron oxide, zirconia taken based on the composition of the finished catalyst, wt.%:

chromium oxide 10-20 potassium oxide 0.1-5 promoter 0.1-5 aluminium oxide rest

The carrier has a granule size of from 50 to 500 μm, has a total specific surface area of from 80 to 250 m ² / g, a pore volume of at least 0.2 cm ³ / g. The carrier is placed in the chamber of the vacuum mixer and degassed. Then, aqueous solutions of the active components and promoters are dosed at a residual pressure of about 30 mm Hg. in an amount corresponding to the moisture capacity of the carrier. The carrier is impregnated with solutions for 0.5-2 hours. After impregnation, the catalyst is dried in vacuum at a residual pressure of 10-30 mm Hg. for 4-6 hours and calcined in air at a temperature of 600-900 ° C for 4-6 hours.

As a precursor of chromium oxide, chromic anhydride, potassium chromate, potassium dichromate, chromium hydroxide, chromium nitrate, chromium acetate, chromium oxalate, chromium acetylacetonate, chromium alcoholates, organometallic complex compounds of chromium are used.

As the potassium oxide precursor, potassium carbonate, potassium hydroxide, potassium nitrate, potassium nitrite, potassium sulfate, potassium permanganate, potassium oxalate, potassium acetate or mixtures thereof are used.

Zirconium hydroxide, zirconium nitrate, zirconium nitrate, zirconium alkoxy derivatives, zirconium acetylacetonate, zirconium carbonate, zirconium chromate, zirconium dichromate, zirconium chromite, organometallic complexes and other zirconium compounds are used as a precursor of zirconium oxide.

As the precursor of copper oxide, copper sulfate, copper hydroxide, copper nitrite, copper carbonate, copper chromite, copper chromate, copper dichromate, copper acetate, copper acetylacetonate, copper complexes with polyhydric alcohols (e.g. copper glycerate, etc.) or mixtures thereof, organometallic complex compounds of copper, etc.

Zinc hydroxide, zinc nitrate, zinc nitrite, zinc carbonate, zinc chromate, zinc dichromate, zinc chromite, zinc acetate, zinc oxalate, organometallic zinc complexes, etc. are used as a precursor of zinc oxide.

Potassium permanganate, potassium manganate, manganese nitrate, manganese carbonate, manganese acetate, manganese oxalate, manganese chromite, manganese chromate, manganese dichromate, organometallic complex compounds of manganese, etc. are used as a precursor of manganese oxide.

As a precursor of tin oxide, tin hydroxide, tin sulfate, tin fluoride, tin chloride, tin chloride, tin hydrochloric acid, tin acid, tin oxalate, tin acetate, tin acetylacetonate, organometallic complex compounds of tin, and others are used.

As a precursor of boron oxide, boron hydroxide, boron fluoride, boron chloride, boron hydride, metaboric acid, orthoboric acid, sodium metaborate, potassium metaborate, sodium tetraborate, lithium tetraborate, potassium tetraborate, sodium pentaborate, potassium pentaborate, potassium pentaborate, decaborate , calcium triborate, calcium hexaborate, organic borates, orthoboric acid esters, borides, organometallic complex compounds of boron, etc.

The abrasive activity of the catalyst is determined by the relative weight loss of an X18H10T stainless steel plate with a mass of 114 g pre-annealed at 550 ° C and cleaned from scale and installed in a test chamber at an angle of 30 degrees in the direction of flow when exposed to a stream of catalyst dried at 110 ° C supplied at a speed of 50 km / h through the nozzle of a sandblasting device with compressed air for two hours.

The fractional composition of the carrier granules is determined by the sieve method.

The abrasion resistance of the catalyst granules is determined by the mass fraction of losses during abrasion in a stream of air for 2 hours. The method is based on the destruction of catalyst particles in a fluidized bed and the measurement of the mass of particles unbalanced by a stream of air, the speed of which is stabilized.

The phase composition of the carrier is determined by x-ray diffraction. Radiographs are taken using long-wavelength radiation CuK _α and a graphite monochromator on a diffracting beam. The range of recording angles in the scale 29 is from 5 to 95 degrees.

The value of the total specific surface and pore volume is determined by the method of low-temperature nitrogen adsorption (BET). The essence of the method for determining the parameters of a porous system is described in ASTM D 3663-99, “Standard Method for Studying the Surface Area and Pore Volume of Catalysts and Catalyst Carriers.

The external shape, the size of the crystals and granules of the carrier and catalyst is determined using an electronic scanning microscope (Fig.1, 2).

The bulk density of the catalyst is determined according to TU 2173-075-00206457-2007 "Catalyst for the dehydrogenation of light paraffin hydrocarbons (CDI)".

When comparing the essential features of the invention with those of the prototype, it was revealed that they are new and not described in the prototype, from here we can conclude that the claimed technical solution meets the criterion of "novelty."

The introduction of new distinguishing features in combination with the achieved result indicates the "inventive step" of the invention.

The present invention meets the criterion of "industrial applicability", as it can be used in industry, as evidenced by examples of specific embodiments of the invention.

Example 1

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in a flowing quartz tube reactor at a reaction temperature of 560-580 ° C, regeneration of 650 ° C, and a hydrocarbon feed rate of 300-400 h ^-1 . The catalyst used is prepared by impregnating the alumina support with solutions of the precursors of chromium, potassium, and promoter oxides in the vacuum mixer chamber for 1 hour, dosing aqueous solutions of chromic anhydride, potassium dichromate, and tin oxalate by moisture absorption, followed by drying in vacuum at a residual pressure of 10 mm Hg . and calcination in air at a temperature of 750 ° C for 4 hours.

The properties of the alumina carrier are shown in table 1.

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and ispentane are shown in table 2.

Example 2

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in a flowing quartz tube reactor at a reaction temperature of 560-580 ° C, regeneration of 650 ° C, and a hydrocarbon feed rate of 300-400 h ^-1 . The catalyst used is prepared using an alumina support fraction from 50 to 300 microns in size with an average granule diameter of 205 microns and an average crystal diameter of the granules of 60 microns. The carrier is boehmite - 97 wt.%, Hydrargillite - 3 wt.%, Has an external specific surface area of 0.12 m ² / g, a total specific surface area of 152 m ² / g, a pore volume of 0.24 cm ³ / g, bulk weighing 1.2 g / cm ³ . The carrier is impregnated with solutions of the precursors of chromium, potassium oxides and the promoter for 0.5 hours at a residual pressure of 10 mmHg, for which 150 g of the carrier are placed in a vacuum mixer chamber and 60 ml of an aqueous solution containing 28.9 g of chromic anhydride are dosed 19.6 g of potassium dichromate; 13.4 g of zinc acetate dihydrate. The impregnated carrier is dried in vacuo at a residual pressure of 10 mm Hg. and calcined in air at a temperature of 750 ° C for 4 hours.

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 3

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 2, but a catalyst is used which is prepared using a fraction of an alumina carrier with a size of 50 to 400 μm with an average diameter of granules of 300 microns and an average diameter of crystals constituting the granule, 75 microns. The carrier is boehmite - 99.9 wt.%, Hydrargillite - 0.1 wt.%, Has an external specific surface area of 0.20 m ² / g, a total specific surface area of 120 m ² / g, a pore volume of 0.29 cm ³ / g, bulk density of 1.2 g / cm ³ . The carrier is impregnated with an aqueous solution containing 35.3 g of chromic anhydride, 26.43 g of potassium dichromate, 2.9 g of manganese acetate tetrahydrate, dried in vacuum at a residual pressure of 10 mm Hg and calcined in air at a temperature of 750 ° C for 4 hours.

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 4

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 2, but a catalyst is used that is prepared using a fraction of an alumina carrier of 50 to 500 μm in size with an average diameter of granules of 390 μm and an average diameter of crystals constituting the granule, 80 microns. The carrier is boehmite, has an external specific surface area of 0.51 mg, a total specific surface area of 115 m ² / g, a pore volume of 0.22 cm ³ / g, bulk density of 1.2 g / cm ³ . The carrier is impregnated with an aqueous solution containing 16.5 g of chromic anhydride, 6.4 g of potassium dichromate, 4.8 g of copper acetate monohydrate, dried in vacuum at a residual pressure of 10 mm Hg and calcined in air at a temperature of 750 ° C for 4 hours.

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 5

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 2, but a catalyst is used that is prepared using a fraction of an alumina carrier of 400 to 500 μm in size with an average granule diameter of 450 μm and an average crystal diameter of the granule, 95 microns. The carrier is boehmite, has an external specific surface area of 0.85 m ² / g, a total specific surface area of 81 m ² / g, a pore volume of 0.21 cm ³ / g, bulk density of 1.2 g / cm ³ . The carrier is impregnated with an aqueous solution containing 37.5 g of chromic anhydride, 10.7 g of potassium carbonate, 46.1 g of boric acid, dried in vacuum at a residual pressure of 10 mm Hg and calcined in air at a temperature of 750 ° C for 4 hours.

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 6

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out as described in example 1, but a catalyst is used which is prepared by impregnating the support with an aqueous solution containing 23.8 g of chromic anhydride, 5.5 g of potassium carbonate, 2.9 g of zirconyl nitrate dihydrate, dried in vacuum at a residual pressure of 10 mm Hg and calcined in air at a temperature of 750 ° C for 4 hours.

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 7

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 6, but a catalyst is used which is prepared using a fraction of an alumina carrier from 50 to 300 μm in size with an average diameter of granules of 205 μm and an average diameter of crystals composing the granule, 60 microns. The carrier is boehmite - 97 wt.%, Hydrargillite - 3 wt.%, Has an external specific surface area of 0.12 m ² / g, a total specific surface area of 152 m ² / g, a pore volume of 0.24 cm ³ / g, bulk weighing 1.2 g / cm ³ .

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 8

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 6, but a catalyst is used which is prepared using a fraction of an alumina carrier with a size of 50 to 400 μm with an average diameter of granules of 300 microns and an average diameter of crystals constituting the granule, 75 microns. The carrier is boehmite - 99.9 wt.%, Hydrargillite - 0.1 wt.%, Has an external specific surface area of 0.20 m ² / g, a total specific surface area of 120 m ² / g, a pore volume of 0.29 cm ³ / g, bulk density of 1.2 g / cm ³ .

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 9

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 6, but a catalyst is used which is prepared using a fraction of an alumina carrier of 50 to 500 μm in size with an average diameter of granules of 390 μm and an average diameter of crystals constituting the granule, 80 microns. The carrier is boehmite, has an external specific surface area of 0.51 m ² / g, a total specific surface area of 115 m ² / g, a pore volume of 0.22 cm ³ / g, bulk density of 1.2 g / cm ³ .

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 10

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 6, but a catalyst is used which is prepared using a fraction of an alumina carrier of 400 to 500 μm in size with an average granule diameter of 450 μm and an average crystal diameter of the granule, 95 microns. The carrier is boehmite, has an external specific surface area of 0.85 m ² / g, a total specific surface area of 81 m ² / g, a pore volume of 0.21 cm ³ / g, bulk density of 1.2 g / cm ³ .

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

Example 11 (comparisons)

The process of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons is carried out in the same manner as described in example 6, but a catalyst is used that is prepared using a carrier fraction, a product of thermochemical activation of hydrargillite, ranging in size from 70 to 250 microns with an average granule diameter of 190 microns and an average diameter crystals making up the granule, 7 microns. The carrier is an X-ray amorphous alumina that has an external specific surface area of 31 m ² / g, a total specific surface area of 115 m ² / g, a pore volume of 0.20 cm ³ / g, and a bulk density of 1.0 g / cm ³ .

The chemical composition, abrasion resistance, bulk density, abrasive activity and catalyst properties in the dehydrogenation reactions of pentane, isobutane and isopentane are shown in table 2.

As can be seen from the above examples, the proposed method of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons can improve the efficiency of the process due to a more complete conversion of the starting paraffins with high selectivity for olefinic hydrocarbons.

The increase in catalyst activity is due to the optimization of the structural characteristics of the catalyst. The use of a high-strength catalyst with low abrasive activity and high bulk density can reduce the number of equipment shutdowns for repairs while increasing the yield of olefinic hydrocarbons.

table 2 Example No. The composition of the catalyst, wt.% Etc, % ρ _us , g / cm ³ Abr,% Dehydrogenation Media number Cr ₂ O ₃ K ₂ O Al ₂ O ₃ promoter propane isobutane isopentane compound content VP,% BP,% VP,% BP,% VP,% BP,% one one 12 2.5 85,4 Sno 0.1 99 1.4 0.5 thirty 82.1 50.1 89.1 46 85.6 2 2 16 3.8 77,2 ZnO ₂ 3 99.1 1.42 0.4 33.7 84 50,2 89.7 43 86.7 3 3 19.1 5 75,4 MnO ₂ 0.5 99,2 1.35 0.3 30,2 82.9 50.9 89.9 47.1 84.2 four four 10.3 1.4 87 CuO 1.3 99 1.34 0.2 28.1 80.3 50.7 90.3 46,4 86.3 5 5 19.3 4.1 71.7 B ₂ O ₃ 4.9 99.9 1.43 0.3 31.7 81.5 50.6 90.5 47 86 6 one 12 2.5 84.6 ZrO ₂ 0.9 99 1.41 0.5 30.8 82.6 50,2 91 43.8 85.1 7 2 12 2.5 84.6 ZrO ₂ 0.9 99 1.41 0.4 29.9 81.5 51,4 90 46.7 86 8 3 12 2.5 84.6 ZrO ₂ 0.9 99 1.37 0.3 30.1 82.7 54 90.9 47.7 85 9 four 12 2.5 84.6 ZrO ₂ 0.9 99 1.31 0.2 28.1 81.9 50,2 90 45.1 86.2 10 5 12 2.5 84.6 ZrO ₂ 0.9 99.5 1.43 0.3 thirty 83 51.1 90.2 46,4 86 11 (comparisons) 6 12 2.5 85.6 ZrO ₂ 0.9 98.5 1,2 2.1 28 79 fifty 89 40.1 84 VP - the output of the olefin to the missed paraffin; BP - olefin yield on decomposed paraffin; Pr - abrasion resistance; Abr - abrasive activity; ρ _us is the bulk density of the catalyst.

Claims (5)

1. The method of dehydrogenation of C ₃ -C ₅ paraffin hydrocarbons in a fluidized bed of a catalyst containing chromium and potassium oxides and a promoter supported on an alumina carrier containing boehmite and up to 10 wt.% Hydrargillite, which is a unit in the form of regular, including mimetic , and irregular splices of twins consisting of hexagonal plate crystals larger than 20 microns. 2. The method according to claim 1, characterized in that the alumina carrier has an external specific surface area of 0.01-1 m ² / g. 3. The method according to claim 1, characterized in that the bulk weight of the alumina carrier is at least 1.2 cm ³ / g. 4. The method according to claim 1, characterized in that the catalyst as a promoter contains copper oxide, zinc oxide, manganese oxide, tin oxide, boron oxide or zirconium oxide and has the following composition, wt.%:
chromium oxide 10-20 potassium oxide 0.1-5 promoter 0.1-5 aluminium oxide rest 5. The method according to claim 1, characterized in that the bulk density of the catalyst is at least 1.3 g / cm ³ .

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