RU2444507C1 - Method of producing alkylbenzine - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to a method of producing alkylbenzine via alkylation of isobutane with olefins in a catalytic reactor at high temperature and pressure, where isobutane is fed into the top section of the reactor then successively passed through all sections with a catalyst, and olefin-containing material is distributed into several streams, the number of which is equal to the number of catalyst sections and then simultaneously fed into the section containing catalyst in parallel streams in order to conduct an alkylation reaction. A hydrocarbon stream containing unreacted isobutane and reaction products is divided into two streams: a vapour stream obtained by evaporating isobutane, which is then condensed and taken for recycling, and a liquid stream which is the reaction product coming from the reaction system or partially taken for recycling. Temperature and pressure in each reactor section is kept so as to ensure an equilibrium vapour-liquid state of the mixed hydrocarbon stream passing through the reactor. The olefins used in the method are C2-C4 olefins. The number of sections ranges from 2 to 10. Before entering the section containing catalyst, the olefin-containing stream is mixed with isobutane in ratio of 1:(2501000), and 50-99.9 wt % vapour stream from the overall stream coming out of the last reactor section is taken for recycling. ^ EFFECT: method enables to increase the cycle length of the catalyst and reduce power consumption. ^ 4 cl, 8 ex, 1 tbl

Description

The invention relates to the field of oil refining and more specifically to a method for producing alkylbenzene, which is known as a high-octane component of motor fuels.

A known industrial method of producing alkylbenzene by alkylation of isobutane with olefins in the presence of sulfuric or hydrofluoric acids at 10 ÷ 12 and 35 ÷ 40 ° C, respectively, and pressure, ensuring the stay of the reactants in liquid form. The reaction is carried out by emulsification of the hydrocarbon phase, including isobutane and olefins in the ratio (5 ÷ 10): 1, with a liquid acid catalyst with a phase ratio of 1: (1 ÷ 1,5). The conversion of olefins occurs at a high speed, and the selectivity of the reaction largely depends on the dilution ratio of olefins with isobutane. Therefore, in both versions of the process create a high internal circulation of the total flow of reaction products and the catalyst, providing an internal ratio of isobutane to olefins up to 500: 1 (Petrochemist Handbook. L .: Chemistry, 1978, v.2, p.99-134).

The disadvantages of this method are the use of toxic and corrosive catalysts, the complexity of their regeneration and the associated high risk of the process.

A known method of producing alkylbenzenes by alkylation of isoparaffins with olefins using zeolite catalysts. The process is carried out by contacting a mixture of isobutane with butylenes on a zeolite catalyst (six fixed layers located one above the other) at a temperature of 70 ÷ 100 ° C and a pressure of 1 ÷ 10 MPa, which ensures the presence of hydrocarbons in liquid form; with a total ratio of isobutane: olefins in the reactor 6: 1 with the number of catalyst layers six molar local ratio on each layer is 36: 1.

To create a molar excess of isobutane to olefins, which suppresses side reactions of polymerization of olefins and increases the selectivity of the main reaction, the isobutane alkylated agent is passed sequentially through all catalyst layers, and olefins are introduced onto each layer in such quantities that each portion converts them on the layer at the adopted volumetric velocity of the total flow. An increase in dilution of olefins with isobutane is achieved by increasing the number of catalyst layers onto which olefin-containing feed streams are introduced (Deontiev A.S. et al. Alkylation of isoparaffins with olefins on zeolite catalysts. Chemistry and technology of fuels and oils, 1978, 10, p.29).

The disadvantage of this method is that with a large number of catalyst layers, the design of the reactor is complicated and the difficulty of controlling it increases. With a small number of layers, the selectivity of the process decreases and the likelihood of local overheating increases.

A known method of producing alkylbenzene described in US patent 20080027263, C07C 2/58, 01/31/2008, according to which C ₄ -C ₅ isoparaffins alkyl C ₃ ÷ C ₅ olefins in the presence of a solid acid alkylation catalyst using two reactors with cycles between the reaction mode and the regeneration mode of the catalyst, which exchange their contents with each other at the beginning of each cycle to increase the yield of the target product. This exchange increases the yield of the product, minimizing the contact of the reagent in the reaction mode with the regeneration solution used in the regeneration mode. The disadvantages of the process are the process in the liquid phase and, as a result, the yield and quality of the reaction products are not high enough.

A known method of producing alkylbenzenes by alkylation of isoparaffins with olefins in the presence of several (at least two) fixed layers of a zeolite catalyst at 40 ÷ 100 ° C. The process is carried out at a pressure of 3 ÷ 6 MPa (preferably 3.5 MPa), at which the circulating hydrocarbon stream in the liquid phase is enriched with isobutane before it is introduced into the catalyst layer as a result of mixing with the stream cooled in the heat exchanger, consisting of the second reacting component ( olefin) and a portion of the stream passing through the catalyst bed and including unreacted isobutane and reaction products formed upon contact with the catalyst. The volume ratio of the stream returned to the reaction zone to the feed stream (olefin) is (8 ÷ 12): 1 (preferably 10: 1). The process uses a rare-earth Linde zeolite catalyst in tablets of 6.4 · 3.2 mm in size, the volumetric supply of liquid hydrocarbons to each catalyst bed is 1 ÷ 3 h ^-1 (preferably 2 h ^-1 ).

This technique creates an additional dilution of olefins with isobutane without a general increase in the ratio of isobutane: olefins in the reactor as a whole and reduces the risk of a local temperature increase in the catalyst layers without increasing the number of layers (U.S. Patent 3976713, class C07C 2/58, B01J 8/04).

The disadvantages of the described method are the reaction in the liquid phase and, as a consequence, the use of a “strongly abatic” reactor, in which the temperature of the process is very different in height of the reactor and, as a result, the quality of the products is deteriorated and there is a low selectivity of the process, which ensures the yield of the target product, alkylbenzene, at a level 50% wt. from olefins. In addition, the process in the liquid phase leads to flooding of the catalyst sections, which reduces its service life.

The closest in technical essence to the present invention is a method for producing alkylbenzene by alkylating isobutane with olefins, in particular butylene, in a 6-section catalytic reactor at a temperature of 40-100 ° C and elevated pressure, in which isobutane is fed to the upper section of the reactor and sequentially passed through all sections with a catalyst, and the olefin-containing raw materials are distributed into several streams, the number of which is equal to the number of sections of the catalyst, and are fed simultaneously to the sections with the catalyst and flow for the alkylation reaction, the hydrocarbon stream containing isobutane and unreacted reaction products, is separated into two streams, the steam obtained by evaporation of isobutane, which is subsequently condensed and is recycled, and the liquid, which is a reaction product. Thanks to this technique, the process takes place in an equilibrium vapor-liquid system, which ensures approximately the same temperature over the entire height of the reactor and favorably affects the yield and quality of the products obtained, as well as its selectivity. The liquid stream is removed from the reaction system, and only a small part (less than 0.1 wt.%) Is returned for recycling. The pressure corresponds to the saturated vapor pressure of the reaction mixture at the reaction temperature. The olefin-containing stream is mixed with isobutane in a ratio of 1: (10-200) before being fed to the section with the catalyst (USSR Author's Certificate No. 1076423 A1, class C07C 9/00, 02/28/1984).

The disadvantage of the prototype is not a high inter-regeneration range of the catalyst.

In addition, do not control the value of the proportion of isobutane sent for distillation along with the reaction products. This can lead to its accumulation at the stage of rectification, the need for additional allocation and unjustified energy costs, or accumulation in recycling. The accumulation of isobutane both in recycling and in the rectification stage violates the stability of the process.

The objective of the invention is to develop a method for producing alkylbenzene, which eliminates the disadvantages of the prototype - to increase the inter-regeneration run of the catalyst, as well as reduce energy costs, excluding the accumulation of unreacted isobutane both at the stage of rectification and in recycling, while maintaining high yield and quality of the resulting products, high the selectivity of the process for the target product is alkylbenzene.

The solution to this problem is achieved by the fact that the proposed method of producing alkylbenzene by alkylating isobutane with olefins in a catalytic reactor at an elevated temperature and pressure, in which isobutane is fed to the upper section of the reactor and sequentially passed through all sections with a catalyst, and the olefin-containing feed are distributed into several streams, number which is equal to the number of sections of the catalyst and served simultaneously in sections with the catalyst in parallel flows for the alkylation reaction, hydrocarbon the stream containing unreacted isobutane and the reaction products are divided into two streams: steam, obtained by evaporation of isobutane, which is then condensed and recycled, and liquid, which is the reaction products, which are removed from the reaction system or partially recycled, temperature and the pressure in each section of the reactor is maintained so as to ensure an equilibrium state of the vapor-liquid mixed hydrocarbon stream passing through the reactor, while using as olefins olefins C ₂ ÷ C ₄ , the number of sections of the catalyst is from 2 to 10, the olefin-containing stream is mixed with isobutane in a ratio of 1: (250 ÷ 1000) before being fed to the section with the catalyst, and 50 ÷ 99.9% wt. vapor stream from the total stream leaving the last section of the reactor.

Isobutane is used fresh or recycled. As the catalyst, any catalyst with a pellet strength of more than 0.5 kg / mm ² exhibiting sufficient activity and selectivity in the isobutane alkylation reaction can be selected.

A special case of the proposed method - return to recycling up to 70% wt. liquid stream from the total stream leaving the last section of the reactor.

The non-evaporated alkylating agent (isobutane) and reaction products from the previous section are mixed with a new portion of the alkylating agent (olefin) and fed to the next section, and the resulting vapor stream is sent for condensation. The total condensed stream in the form of irrigation is fed into the reaction zone (in the first or in each of the sections) and the olefins fed into the reaction zone are diluted. Maintaining a high ratio of olefin-containing stream to isobutane - from 1: 250 to 1: 1000 - helps to increase the duration of the catalyst (its inter-regeneration run).

In this case, isothermal conditions are provided inside the reaction zone, and the circulating stream, further diluting the olefin-containing stream, mainly consists of an alkylated agent. Alkylbenzene, as a higher boiling point, evaporates very slightly and is practically absent in the circulating stream (less than 0.1 wt.%). This helps to maintain high process selectivity and product quality indicators.

The circulating hydrocarbon stream is enriched with isobutane as a result of its evaporation from the reaction mixture due to the heat of the alkylation reaction and / or additional heat input and / or pressure reduction of the reaction products at the outlet of the reactor, its subsequent condensation and return to the reaction zone. Strict control of the steam stream returned to recycling (in an amount from 50 to 99.9 wt.%) Of the total stream leaving the last section of the reactor ensures that the higher boiling products of the alkylation reaction practically do not evaporate and remain in the liquid phase, and are eliminated accumulation of unreacted isobutane both at the stage of rectification and in recycling.

The technical effect achieved is:

- to increase the duration of stable operation of the catalyst and the inter-regeneration path of the catalyst;

- in reducing energy costs in the production of alkylbenzene.

An additional technical result is to maintain a high yield and high quality reaction products.

The following examples illustrate and explain the proposed technical solution, but in no way limit it.

Example 1

An alkylated component (isobutane) is fed into the upper part of the four-section reactor with a fixed granular catalyst bed, which is zeolite X cylinders in a Pd-REZEN-form 5 mm high and 5 mm in diameter.

Butylene (an olefin-containing agent), namely the butane-butylene catalytic cracking fraction, is introduced as an alkylating agent, which are introduced in four equal parallel streams to each catalyst bed through devices providing good mixing of the hydrocarbon stream (products of the alkylation reaction together with non-evaporated isobutane) leaving the previous layer, and the butylene stream. The temperature in the reaction zone is kept at 80 ° C, the pressure is 1.32 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The total hydrocarbon stream leaving the last section of the reactor, containing unreacted isobutane and reaction products, is heated by an external heat source and divided into two streams: steam obtained by evaporation of isobutane, which is then condensed and sent for recycling in the amount of 94.7 wt.% From the total flow, providing a ratio of isobutane to butylene 500: 1, and liquid, representing the reaction products, which are removed from the reaction system or partially sent for recycling. The total ratio of isobutane to olefins in the reactor is 6: 1.

The yield of reaction products is calculated according to the following reaction equations:

The equations of the alkylation of isobutane with olefins C ₂ ÷ C ₄ :

Ethylene Alkylation

(100 octane research method - OCH)

Propylene Alkylation

(84 OCHI)

Alkylation with butene-2

(100 GPI)

Alkylation with butene-1

(71.3 OCHI)

(102.7 GPI)

Isobutene Alkylation

(100 GPI)

Olefin conversion is the ratio of the amount of converted olefin (OL) to the taken, expressed in%. It characterizes the completeness of the use of raw materials in this process.

X (OL) - Conversion of OL,% wt.

C (OL) raw materials - the concentration of OL in raw materials,% wt .;

m (raw materials) - mass of raw materials, g;

C (OL) prod. - concentration of OL in the product,% wt .;

m (product) is the mass of the product, g;

The yield of AB on the taken OL is the yield of alkylbenzene on olefins in the feed, expressed in%.

η (AB) - The output of AB,% wt .;

m (product) is the mass of the product, g;

C (OL) raw materials - the concentration of OL in raw materials,% wt .;

m (raw materials) - mass of raw materials, g.

The selectivity of the process is evaluated by the content of the isoactane fraction in the mixture of the obtained products - alkylbenzene, as the most valuable component of gasoline obtained by mixing high-octane gasoline by catalytic cracking of vacuum gas oil and reforming low-octane gasoline.

The selectivity of the reaction - the relative concentration of the isooctane fraction on the reaction products is equal to:

δ (AB) is the selectivity of the reaction,% wt .;

C (ΣC ₈ ) is the concentration of the isooctane fraction in the product,% wt .;

C (cont.) - the total concentration of reaction products,% wt.

In accordance with the presented calculations, the yield of alkylbenzene for the missed olefins in this example is 208% wt.

The selectivity of the process is 93.2%.

The quality of the reaction products is shown in table 1.

As can be seen from the table, the quality of the resulting products significantly increases while increasing the duration of the stable operation of the catalyst.

Example 2

An alkylated component (isobutane) is fed to the upper part of the ten-section reactor with a fixed granular catalyst bed, which is zeolite X cylinders in a Pd-REZEN-form 5 mm high and 5 mm in diameter.

Butylene (an olefin-containing agent) is used as the alkylating agent, namely, the butane-butylene catalytic cracking fraction, which is introduced by ten equal parallel streams to each catalyst bed through devices providing good mixing of the hydrocarbon stream (products of the alkylation reaction together with non-evaporated isobutane) leaving the previous layer, and the butylene stream. The temperature in the reaction zone is kept at 80 ° C, the pressure is 1.32 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The total hydrocarbon stream leaving the last section of the reactor, containing unreacted isobutane and reaction products, is heated by an external heat source and divided into two streams: steam, obtained by evaporation of isobutane, which is then condensed and sent for recycling, in the amount of 85.6 wt.% from the total flow, providing a ratio of isobutane to butylenes of 250: 1, and liquid, representing the reaction products, which are removed from the reaction system or partially sent for recycling. The total ratio of isobutane to olefins in the reactor is 6: 1.

In accordance with the presented calculations, the yield of alkylbenzene for the missed olefins in this example is 206% wt.

The selectivity of the process is 90.8%.

The quality of the reaction products is shown in table 1.

Example 3

An alkylated component (isobutane) is fed into the upper part of the ten-section reactor with a fixed granular catalyst bed, which is zeolite Y cylinders in Ni-REZEN-form, 5 mm high and 5 mm in diameter.

Propylene (an olefin-containing agent) is used as an alkylating agent, which is introduced in two equal parallel streams to each catalyst bed through devices that ensure good mixing of the hydrocarbon stream (products of the alkylation reaction together with non-evaporated isobutane) leaving the previous layer and the propylene stream. The temperature in the reaction zone is kept at 90 ° C, a pressure of 1.6 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The total hydrocarbon stream leaving the last section of the reactor containing unreacted isobutane and reaction products is heated by an external heat source and divided into two streams: steam, obtained by evaporation of isobutane, which is then condensed and sent for recycling, in the amount of 98.6 wt.% from the total flow, providing a ratio of isobutane to propylene 1000: 1, and liquid, representing the reaction products, which are removed from the reaction system or partially sent for recycling. The total ratio of isobutane to propylene in the reactor is 6: 1.

In accordance with the presented calculations, the yield of alkylbenzene on the passed propylene in this example is 221% wt.

The selectivity of the process is 58.5%.

The quality of the reaction products is shown in table 1.

Example 4 (comparative)

An alkylated component (isobutane) is fed into the upper part of the six-section reactor with a fixed granular catalyst bed, which is zeolite Y cylinders in REZEN-form, 5 mm high and 5 mm in diameter.

Butylene (an olefin-containing agent), namely, the butane-butylene catalytic cracking fraction, which is introduced with six equal parallel streams to each catalyst bed through devices providing good mixing of the hydrocarbon stream (products of the alkylation reaction together with the non-evaporated isobutane) coming out of the previous layer, and the butylene stream. The temperature in the reaction zone is kept at 90 ° C, a pressure of 1.6 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The quantitative ratio of the flows is set in such a way that, in the whole reactor, the calculated ratio of isobutane: olefins is 6: 1. The generated reaction heat is removed by evaporation of the excess isobutane in each section. Isobutane vapors in the collector are removed from various sections and sent to a reflux condenser. The condensed isobutane in the form of recirculate (irrigation) is mixed with a fresh stream of isobutane and fed into the reaction zone, namely the catalyst bed. The actual ratio of isobutane: olefins at the entrance to each catalyst layer is (70-75): 1. The reaction is carried out for 12 hours

In accordance with the presented calculations, the yield of alkylbenzene for the missed olefins in this example is 190% wt.

The selectivity of the process is 82.3%.

The quality of the reaction products is shown in table 1.

Example 5 (comparative).

The experiment is carried out as in example 1, but additional heat is introduced into the cube of the reactor by supplying steam through the coil in such a way as to separate the reaction products into two streams: steam (82.6 wt.% Of the total stream) obtained by evaporation of isobutane, which is then condensed and sent for recycling, and liquid, which is the reaction product, which is removed from the reaction system or partially sent for recycling.

This increases the multiplicity of circulation of isobutane, and the actual ratio of isobutane: olefins at the inlet to each catalyst bed is 200: 1 with a total reactor ratio of 6: 1.

The reaction is carried out for 40 hours

The yield of alkylbenzene on the passed butylenes is 205% wt.

The selectivity of the process according to the example is 87.9%.

Product quality is shown in table 1.

Example 6

An alkylated component (isobutane) is fed into the upper part of the six-section reactor with a fixed granular catalyst bed, which is an extrudate of an aluminum-zirconium catalyst with a diameter of 1.5 mm and a length of 3 mm. Butene-1 (an olefin-containing agent) is introduced in six parallel streams to each catalyst bed through devices that ensure good mixing of the hydrocarbon stream (products of the alkylation reaction together with non-evaporated isobutane) leaving the previous layer and the butene-1 stream. The temperature in the reaction zone is kept at 60 ° C, the pressure is 0.85 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The quantitative ratio of the flows is set in such a way that, in the whole reactor, the calculated ratio of isobutane: butene-1 is 6: 1. The generated reaction heat is removed by evaporation of the excess isobutane in each section. Isobutane vapors in the collector are removed from various sections and sent to a reflux condenser. The condensed isobutane in the form of recirculate (irrigation) is mixed with a fresh stream of isobutane and fed into the reaction zone, namely the catalyst bed.

Additional heat is introduced into the reactor cube by supplying steam (or any other heat source) through the coil in such a way as to separate the reaction products into two streams: steam obtained by evaporation of isobutane, which is then condensed and recycled in an amount of 93.45 wt. .% of the total flow, and liquid, representing the reaction products, which is removed from the reaction system or partially sent for recycling.

This increases the multiplicity of circulation of isobutane, and the actual ratio of isobutane: butene-1 at the entrance to each catalyst bed is 600: 1 with a total ratio of 6: 1 in the reactor.

The reaction is carried out for 40 hours

The yield of alkylbenzene to the missed butylenes is 204% wt.

The selectivity of the process for the target product is 83.6%.

Product quality is shown in table 1.

Example 7

An alkylated component (isobutane) is fed to the upper part of the six-section reactor with a fixed granular catalyst bed, which is the extrudates of zeolite X in a Pd-RESEN form with a diameter of 1.5 mm and a length of 3 mm. Ethylene (an alkylating agent) is introduced in six parallel streams to each catalyst bed through devices that provide good mixing of the hydrocarbon stream (products of the alkylation reaction together with the non-evaporated isobutane) leaving the previous layer and the ethylene stream. The temperature in the reaction zone is kept at 80 ° C, the pressure is 1.32 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The quantitative ratio of the flows is set in such a way that, in the whole reactor, the calculated ratio of isobutane: ethylene is 6: 1. The generated reaction heat is removed by evaporation of the excess isobutane in each section. Isobutane vapors in the collector are removed from various sections and sent to a reflux condenser. The condensed isobutane in the form of recirculate (irrigation) is mixed with a fresh stream of isobutane and fed into the reaction zone, namely the catalyst bed.

Additional heat is introduced into the cube of the reactor by supplying steam (or any other heat source) through the coil in such a way as to separate the reaction products into two streams: steam (90.5 wt.% Of the total stream) obtained by evaporation of isobutane, which then condensed and sent for recycling, and liquid, which is the reaction product, which is removed from the reaction system or partially sent for recycling.

This increases the multiplicity of circulation of isobutane, and the actual ratio of isobutane: ethylene at the entrance to each catalyst layer is 400: 1 with a total ratio of 6: 1 in the reactor.

The reaction is carried out for 36 hours

The yield of alkylbenzene on the passed ethylene is 200.8% wt.

The selectivity of the process for the target product is 81.4%.

Product quality is shown in table 3.

Example 8 (comparative).

An alkylated component (isobutane) is fed into the upper part of a six-section reactor with a fixed granular catalyst bed, which is an extrudate of Vetta zeolite in H-form with a diameter of 1.5 mm and a length of 3 mm. Propylene (an alkylating agent) is introduced in six parallel streams to each catalyst bed through devices that provide good mixing of the hydrocarbon stream (products of the alkylation reaction together with unevaporated isobutane) leaving the previous layer and the butylene stream. The temperature in the reaction zone is kept at 90 ° C, the pressure is 1.62 MPa, which corresponds to the equilibrium state of the vapor-liquid hydrocarbon mixture.

The quantitative ratio of the flows is set in such a way that, in the whole reactor, the calculated ratio of isobutane: olefins is 6: 1. The generated reaction heat is removed by evaporation of the excess isobutane in each section. Isobutane vapors in the collector are removed from various sections and sent to a reflux condenser. The condensed isobutane in the form of recirculate (irrigation) is mixed with a fresh stream of isobutane and fed into the reaction zone, namely the catalyst bed.

Additional heat is introduced into the reactor cube by supplying steam (or any other heat source) through the coil in such a way as to separate the reaction products into two streams: steam (82.6 wt.% Of the total flow) obtained by evaporation of isobutane, which then condensed and sent for recycling, and liquid, which is the reaction product, which is removed from the reaction system or partially sent for recycling.

This increases the multiplicity of circulation of isobutane, and the actual ratio of isobutane: olefins at the inlet to each catalyst bed is 200: 1 with a total reactor ratio of 6: 1. The reaction is carried out for 30 hours

The yield of alkylbenzene on the passed propylene is 193.8% wt.

The selectivity of the process for the target product is 35.5%.

Product quality is shown in table 1.

Thus, the proposed method of producing alkylbenzene, which allows to increase the inter-regeneration period and reduce energy costs compared to the prototype, as well as to eliminate the accumulation of isobutane both at the stage of rectification and in recycling, while maintaining high quality of the reaction products, their high yield and high selectivity of the process for the main target component of gasolines.

Claims (4)

1. The method of producing alkylbenzene by alkylating isobutane with olefins in a catalytic reactor at an elevated temperature and pressure, in which isobutane is fed to the upper section of the reactor and sequentially passed through all sections with a catalyst, and the olefin-containing feed is distributed into several streams, the number of which is equal to the number of sections of the catalyst, and fed simultaneously to the sections with the catalyst in parallel streams for carrying out the alkylation reaction, a hydrocarbon stream containing unreacted isobutane and products The reaction steps are divided into two streams: the steam obtained by evaporation of isobutane, which is then condensed and sent for recycling, and liquid, which is the reaction products, which are removed from the reaction system or partially sent for recycling, the temperature and pressure in each section of the reactor are maintained so as to ensure a vapor-liquid equilibrium state of the mixed hydrocarbon stream passing through the reactor, characterized in that C ₂ -C ₄ olefins are used as olefins, the number of sections is catalyzed RA ranges from 2 to 10, the olefin-containing stream is mixed with isobutane in a ratio of 1: (250 ÷ 1000) before being fed to the section with the catalyst, and 50 ÷ 99.9 wt% of the vapor stream from the total stream leaving the last section is returned to recycling the reactor. 2. The method according to claim 1, characterized in that they use isobutane fresh or returned to recycling. 3. The method according to claim 1, characterized in that the evaporation of isobutane is carried out by any of the methods: due to the heat of the reaction, and / or supply of heat from the outside, and / or reducing the pressure of the reaction products at the outlet of the reactor. 4. The method according to claim 1, characterized in that up to 70 wt.% Of the liquid stream from the total stream leaving the last section of the reactor is returned to recycling.