RU2747867C1 - Method of producing gasolines or concentrates of aromatic compounds with different distribution of oxygenate streams and olefin-containing fraction and adding water - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method of producing a liquid hydrocarbon product containing aromatic compounds. In the method, the feedstock used is three streams, the first of which includes a hydrocarbon fraction, the second stream includes an oxygenate, the third stream includes an olefin-containing fraction, wherein the olefin-containing fraction includes one or more olefins selected from a group comprising ethylene, propylene, normal butylenes, isobutylene in total amount of 10-50 wt%. Three reaction zones filled with a zeolite catalyst are used, the first stream is fed into at least one reaction zone, second flow is fed only to the last reaction zone, the third stream is fed into the first and second reaction zones, wherein water is added to the first and second reaction zones, and the product stream from the first reaction zone is fed into the second reaction zone, and the product stream from the second reaction zone is fed into the third reaction zone.

EFFECT: method enables to reduce content of heavy hydrocarbons in the product, obtain a product with a boiling point below 215 °C and resin content of less than 5 mg/100 cm³, avoid recycling of gaseous products, as well as reduce consumption of oxygenates.

35 cl, 14 ex, 7 tbl

Description

The invention relates to the field of oil refining and petrochemical industries. More specifically, the invention relates to a method for the production of gasolines or concentrates of aromatic compounds by co-processing hydrocarbon fractions, oxygenates and olefin-containing fractions.

The following terms are used in the description:

Gasoline - commercial gasoline or the main component (base) for the production of gasoline. In particular, gasoline obtained by the proposed method can be used to obtain motor gasolines by compounding methods (mixing gasoline fractions obtained by various oil refining processes). For example, according to the proposed method, a basis for the production of motor gasoline of ecological class K5 of the AI-92 brand according to GOST 32513-2013 can be produced. In some cases, the gasoline obtained by the proposed method may not meet all the requirements for commercial gasoline by a particular region or organization. For example, the benzene content of the produced gasoline can exceed 1.0 vol. %. As another example, the aromatic content of the gasoline produced can exceed 35 vol. %. As gasoline can be considered a liquid hydrocarbon product produced by the proposed method.

Hydrocarbon fraction - a fraction of the gasoline boiling range (the boiling point is not standardized, the boiling point is not more than 215 ° C). In particular, the end of the boiling point can be 200 ° C, 180 ° C, 160 ° C or 85 ° C. Preferably, the end boiling point is not higher than 180 ° C. The onset of boiling can be, for example, 62 ° C, 85 ° C, 140 ° C. Preferably, the initial boiling point is at least 62 ° C.

Oxygenate is an aliphatic alcohol or ether. Can be selected from the group including: methanol, raw methanol, technical methanol, ethanol, dimethyl ether, other aliphatic alcohols, other ethers, as well as mixtures thereof, incl. with water. May contain impurities such as aldehydes, carboxylic acids, esters, aromatic alcohols. The method does not involve the use of unsaturated (unsaturated) alcohols, for example, allyl alcohol, but their presence is possible as impurities.

Olefin-containing fraction - a fraction comprising 10-50 wt. % olefins C ₂ -C ₄ (ethylene, propylene, normal butylenes, isobutylene).

The olefin-containing fraction may contain inert or weakly reactive components other than olefins, for example: methane, ethane, propane, butane, hydrogen, nitrogen. For example, the olefin-containing fraction may contain from 0.5 to 8.0 wt. % hydrogen, preferably from 2 to 8 wt. % hydrogen. Preferably, the mass fraction of C ₅₊ hydrocarbons in the olefin-containing fraction is not more than 5.0 wt. %. Preferably, the volume fraction of hydrogen sulfide in the olefin-containing fraction is not more than 0.005%.

The reaction zone is a separate volume in the reactor containing the catalyst. Several consecutive reaction zones can be located in one reactor. For example, the reaction zones can be shelves in a shelf reactor. Also, each reaction zone can be located in a separate reactor. A separate reactor can be used as the reaction zone.

OCHI is the octane number determined by the research method. It can be determined, for example, according to ASTM D2699 or according to GOST 8226.

C _n - hydrocarbons with the number of carbon atoms n.

C _{n +} - hydrocarbons with the number of carbon atoms equal to or more than n.

REE - rare earth elements.

DME stands for dimethyl ether.

SGKK is a dry catalytic cracking gas.

FAU - fraction of aromatic hydrocarbons.

Mass feed rate of raw materials, h ^-1 _{- the} amount of raw materials passed per unit time through a unit mass of the catalyst. For example, the mass feed rate of the i-th component:

where is the mass flow of the i-th component at the inlet, g / h.

- масса катализатора, г.

is the mass of the catalyst, g.

Conversion is the ratio of the amount of raw material that has reacted to the amount of raw material fed into the reaction. For example, the conversion of the i-th component:

where is the mass flow of the i-th component at the inlet, g / h.

- mass flow of the i-th component at the outlet, g / h.

Selectivity is the ratio of the amount of the target component to the total amount of hydrocarbons obtained in the given process. For example, the selectivity of the i-th component of the product:

where is the mass flow of the i-th component at the outlet, g / h,

- total mass flow of all produced hydrocarbons, g / h.

The percentage substitution of the oxygenate for the olefin-containing fraction (% substitution) is calculated as follows:

where is the molar flow of the i-th supplied oxygenate, mol / h,

k _i - coefficient advising the i-th supplied oxygenate. The k _i factor is 0.5 for methanol, 1 for other oxygenates (eg ethanol, propanol, DME).

- molar flow of the j-th fed olefin, mol / h.

For example, if it is necessary to replace methanol with dry catalytic cracking gas containing ethylene, the replacement percentage is calculated as follows:

- мольный поток подаваемого метанола, моль/ч,Where

- molar flow of supplied methanol, mol / h,

- мольный поток подаваемого этилена, моль/ч,

- molar flow of supplied ethylene, mol / h,

0.5 is the coefficient corresponding to methanol.

Similarly, if ethanol is used as the oxygenate, and the olefin-containing fraction contains ethylene, propylene and butylenes, the percentage of substitution is calculated as follows.

- мольный поток подаваемого метанола, моль/ч,Where

- molar flow of supplied methanol, mol / h,

- мольный поток подаваемого этилена, моль/ч,

- molar flow of supplied ethylene, mol / h,

- мольный поток подаваемого пропилена, моль/ч,

- molar flow of supplied propylene, mol / h,

- общий мольный поток подаваемых бутиленов (включая изобутилен), моль/ч,

- total molar flow of supplied butylenes (including isobutylene), mol / h,

1 - coefficient for ethanol.

The percent substitution of the oxygenate for the olefin-containing fraction does not take into account the water supplied to the reaction zones.

LEVEL OF TECHNOLOGY

There are several examples of joint processing of hydrocarbon fractions, oxygenates and olefin-containing fractions into gasolines or concentrates of aromatic compounds.

Patent RU 2671568 dated 09/27/2016 refers to a complex plant for processing a mixture of C ₁ -C ₁₀ hydrocarbons of various composition (low-octane gasoline fractions n.c.-180 ° C, 90-160 ° C or narrower fractions, pentane-heptane (hexane ) fractions, propane-butane fractions, BFLH and / or lower olefins C ₂ -C ₁₀ and / or their mixtures with each other, and / or with C ₁ -C ₁₀ paraffins, and / or with hydrogen) in the presence of oxygen-containing compounds, comprising one or more parallel-located sectioned adiabatic reactors, consisting of one or more stationary beds (sections) of a zeolite-containing catalyst with a supply or removal of heat between the beds (sections) of the catalyst. The proposed installation allows you to obtain high-octane gasolines, diesel fractions or aromatic hydrocarbons.

The disadvantage of the invention is the need to add significant amounts of isobutane to the feedstock in order to control the temperature of the reaction zones. Isobutane is a highly demanded refinery product with a high cost. Its redirection to the processing of the hydrocarbon fraction will lead to an increase in the cost of producing gasoline or a concentrate of aromatic compounds.

The disadvantage of the invention is also the circulation of a part of the gaseous product directly through the catalyst bed. Recycling the gaseous product complicates the required equipment and its maintenance. Also, this approach does not allow working with sulfur-containing raw materials without involving additional purification methods. In particular, the plant contains a unit for removing sulfur compounds using the hydrogen-containing gas obtained in the process from at least a portion of the hydrocarbon feedstock. Incomplete purification of raw materials from sulfur can lead to the production of a gaseous product contaminated with sulfur compounds. Recycling of such a gaseous product will lead to accelerated poisoning of the catalyst with gaseous sulfur-containing compounds (hydrogen sulfide, mercaptans).

Application for invention WO2017155431 (PCT / RU2017 / 050009 ) describes a method for producing gasolines from raw hydrocarbon fractions, fractions of gaseous olefins and oxygenates. As a reactor, a reactor is used containing at least two reaction zones with a zeolite-containing catalyst, between which there is additionally located means for mixing the reaction products of the previous reaction zone and supplied methanol or other oxygenates and olefin-containing raw materials, and by means of a flow feed unit:

• to the first reaction zone of the reactor: a stream of methanol or other oxygenates and olefin-containing raw materials and a stream of raw hydrocarbon fractions,

• to the second reaction zone of the reactor - a stream of methanol or other oxygenates and olefin-containing raw materials.

As a disadvantage of the method can be considered the fact that when obtaining gasoline, the temperature of the end layer of the catalyst is 40-70 ° C lower than the maximum temperature of the catalyst layer. Such a drop in temperature in the end layer of the catalyst can lead to uneven coking of the catalyst and to the occurrence of side reactions (for example, oligomerization of olefins instead of involving them in the processes of aromatic alkylation and aromatics formation).

As a disadvantage of the method, the need for additional heat supply to the reaction zones can also be considered, then at low consumption of methanol (less than 20% of the mass of the converted raw material), including due to additional overheating of the feed stream supplied to the last and / or penultimate reaction zones (maximum up to 500 ° C), or by using isothermal reaction zones as one or two of the last reaction zones of the reactor.

This method is the closest to the present invention and is taken as a prototype.

However, none of the documents described does not investigate how the options for the distribution of raw materials between the reaction zones affect the parameters of the process. In particular, the effect of the distribution of water between the reaction zones in combination with the different distribution of the oxygenate and olefin-containing fraction streams is not disclosed. At the same time, the known sources do not investigate the problems that arise when replacing pure olefins with cheap sources of C ₂ -C ₄ olefins with a low concentration of olefins. Conditions are not disclosed that allow obtaining a high-octane product under conditions when the feedstock includes methane, ethane, hydrogen, nitrogen. It is also not disclosed that the use of raw materials of a certain composition with an appropriate distribution between the reaction zones will eliminate the recycle of gaseous products.

DISCLOSURE OF THE INVENTION

As the technical results of the present invention are considered:

1.reduction of the content of heavy hydrocarbons in the product;

2. reduction of the resin content in the product to 5 mg / 100 cm ³ or less;

3. lowering the end boiling point of the product to 215 ° C or less;

4. reduction of coke formation;

5. the ability to use the olefin-content of the fraction with an olefin content of less than 50 wt. % without preliminary concentration of olefins;

6. the ability to use olefin-containing fractions, including hydrogen, without additional separation;

7. absence of oxygenates in the liquid hydrocarbon product;

8. the ability to exclude the recycling of gaseous products;

9. Possibility of producing low-benzene aromatic concentrates;

10. Possibility of producing aromatic concentrate with a high content of C ₈ alkylbenzenes;

11. reduction of oxygenate consumption due to partial replacement of oxygenate with olefin-containing fractions.

The objective of the invention is to reduce the consumption of oxygenates during the joint processing of hydrocarbon fractions and oxygenates into gasolines or concentrates of aromatic compounds while maintaining the yield and quality of the product. The problem is solved, in particular, due to the partial replacement of oxygenates with olefin-containing fractions of low cost.

At the same time, in the production of gasoline, it is necessary to ensure the yield of a liquid hydrocarbon product above 70% for the supplied hydrocarbon fraction, the OCHI of the product is above 85 units, the resin content is not more than 5 mg / 100 cm ³ and the end boiling point of the product is not more than 215 ° C (the resin content can be determined, for example, according to GOST 1567, according to ASTM D381; the end boiling point can be determined, for example, according to GOST 2177, according to ASTM D86). The listed characteristics will make the manufactured product an attractive basis for the production of commercial gasolines, in particular, motor gasoline of ecological class K5.

The set tasks can be solved due to the proposed method for producing a liquid hydrocarbon product containing aromatic compounds, in which three streams are used as raw materials, the first of which includes a hydrocarbon fraction, the second stream includes an oxygenate, the third stream includes an olefin-containing fraction, and:

a. the olefin-containing fraction includes one or more olefins selected from the group consisting of ethylene, propylene, normal butylenes, isobutylene, in a total amount of 10 to 50 wt. %.

b. use three reaction zones filled with zeolite catalyst,

c. the first stream is fed to at least one reaction zone,

d. the second stream is fed only to the last reaction zone,

e. the third stream is fed into the first and second reaction zones,

f. moreover, water is added to the first and second reaction zones,

g. and the product stream from the first reaction zone is fed to the second reaction zone and the product stream from the second reaction zone is fed to the third reaction zone.

It is possible to carry out the invention in which the liquid hydrocarbon product containing aromatic compounds is gasoline if the content of aromatic compounds is less than 40 wt. %, or a liquid hydrocarbon product containing aromatic compounds is an aromatic concentrate if the content of aromatic compounds is more than 40 wt. %.

An embodiment of the invention is possible in which the first stream is preferably fed to the first reaction zone.

Possible execution of the invention, in which the hydrocarbon fraction contains normal paraffins in an amount of 15-24 wt. %, isoparaffins in the amount of 42-56 wt. %, naphthenes in the amount of 22-40 wt. %, the rest is aromatic hydrocarbons and olefins.

Possible execution of the invention, in which the hydrocarbon fraction contains from 0 to 80 wt. % hydrocarbons C ₆ , preferably from 23 to 46 wt. % hydrocarbons C ₆ , most preferably from 36 to 46 wt. % hydrocarbons С ₆ .

Possible execution of the invention, in which the hydrocarbon fraction contains from 0 to 70 wt. % isoparaffins C ₇ , preferably from 26 to 50 wt. % isoparaffins With ₇ , most preferably from 26 to 38 wt. % isoparaffins C ₇ .

It is possible to implement the invention, in which the hydrocarbon fraction can be selected from the group including straight-run gasoline, stable gas gasoline, light gas condensate, gasoline fraction with boiling points of about 62 ° - 85 ° C, raffinate, and mixtures thereof.

It is possible to carry out the invention, in which in the first olefin-containing fraction the mass fraction of C ₅₊ hydrocarbons is from 0 to 10.0 wt. %, preferably from 0 to 5.0 wt. %.

An embodiment of the invention is possible in which the olefin-containing fraction may include C ₅₊ olefins, for example, pentenes, hexenes.

A possible embodiment of the invention, in which the olefin-containing fraction may include methane, ethane, propane, butanes, nitrogen.

It is possible to carry out the invention in which olefin-containing fraction includes from 0.5 to 8 wt. % hydrogen.

It is possible to carry out the invention in which the olefin-containing fraction includes from 2.3 to 8 wt. % hydrogen.

An embodiment of the invention is possible, in which the olefin-containing fraction is selected from the group including dry catalytic cracking gas, catalytic cracking wet gas, other catalytic cracking gases and their fractionation products, off-gas from a coking unit, Fischer-Tropsch synthesis gases, and mixtures thereof ...

An embodiment of the invention is possible in which the olefin-containing fraction is selected from the group including propane-propylene fractions, butane-butylene fractions, thermal cracking gas, visbreaking gas, hydrocracking off-gases, pyrolysis gas, catalytic reforming waste gases, and mixtures thereof.

Possible execution of the invention, in which the olefin-containing fraction includes dry catalytic cracking gas and contains from 25 to 40 wt. % olefins C ₂ -C ₄ .

It is possible to carry out the invention in which the oxygenate is selected from the group consisting of aliphatic alcohols, for example, methanol, ethanol, crude methanol, technical methanol, ethanol; ethers, for example, dimethyl ether, as well as mixtures thereof, including with water.

It is possible to carry out the invention in which the oxygenate may contain impurities, for example, aldehydes, carboxylic acids, esters.

Possible execution of the invention, in which the hydrocarbon fraction is 62-74 wt. % of the supplied raw materials.

Possible execution of the invention, in which the olefin-containing fraction is 16-24 wt. % of the supplied raw materials.

Possible execution of the invention, in which the oxygenate is 2-4 wt. % of the supplied raw materials.

Possible execution of the invention, in which the water is 7-10 wt. % of the supplied raw materials.

Possible execution of the invention, in which the olefin-containing fraction is distributed between the first and second reaction zones in a ratio of 29-72 wt. % / 71-28 wt. %.

Possible execution of the invention, in which water is distributed between the first and second reaction zones in a ratio of 29-54 wt. % / 71-46 wt. %.

An embodiment of the invention is possible in which the process pressure is from 1.5 to 4.0 MPa, preferably from 2.2 to 2.7 MPa.

It is possible to implement the invention, in which the temperature of the stream at the entrance to the first / second / third reaction zone is 340-450 ° C / 340-450 ° C / 350-450 ° C.

An embodiment of the invention is possible, in which the mass feed rate of the raw material is from 0.5 to 10 h ^-1 , preferably 1-3 h ^-1 .

Possible execution of the invention, in which the temperature of the flow at the entrance to the first / second / third reaction zone is 340-380 ° C / 340-380 ° C / 350-380 ° C.

An embodiment of the invention is possible, in which the mass feed rate of the raw material is from 0.9 to 10 h ^-1 , preferably 1-3 h ^-1 .

Possible execution of the invention, in which the temperature of the flow at the entrance to the first / second / third reaction zone is 390-450 ° C / 390-450 ° C / 390-450 ° C.

It is possible to implement the invention in which the mass feed rate of the raw material is from 0.1 to 0.9 h ^-1

Possible execution of the invention, in which the distribution of the catalyst in the reaction is 17-33 wt. % / 28-43 wt. % / 33-50 wt. % of the total amount of catalyst for the first / second / third reaction zone, respectively.

An embodiment of the invention is possible, in which the zeolite catalyst comprises:

a. zeolite of the ZSM-5 type with a SiO ₂ / Al ₂ O ₃ modulus from 43 to 95, in an amount from 65 to 80 wt. %,

b. sodium oxide in an amount from 0.04 to 0.15 wt. %,

c. zinc oxide in the amount of 1.0-5.5 wt. %,

d. oxides of rare earth elements in a total amount of 0.5-5.0 wt. %,

e. a binder comprising silicon dioxide, aluminum oxide, or mixtures thereof.

An embodiment of the invention is possible in which the zeolite catalyst does not contain platinum metals.

An embodiment of the invention is possible in which the rare earth elements are selected from the group including lanthanum, praseodymium, neodymium, cerium, and mixtures thereof.

An embodiment of the invention is possible, in which the reaction is carried out in the gas phase in a fixed catalyst bed.

CARRYING OUT THE INVENTION

To carry out the process, the hydrocarbon fraction, oxygenate, olefin-containing fraction and water are separated into several streams. The streams are fed to the reaction zones:

R ₁₀₁ - the first reaction zone;

R ₂₀₁ - second reaction zone;

R ₃₀₁ is the third reaction zone.

The hydrocarbon fraction is fed to at least one reaction zone. For this, the hydrocarbon fraction can be separated into one, two or three streams. In particular, to carry out the experiments of Examples 1-13, the entire hydrocarbon fraction was distributed to the first reaction zone (i.e., no second and third hydrocarbon fraction streams were generated).

To carry out the experiment of example 14, the hydrocarbon fraction was divided into three reaction zones (i.e., created the first, second and third streams of the hydrocarbon fraction).

It is also possible, if necessary, to distribute the entire flow of the hydrocarbon fraction only to the second or only to the third reaction zone. In another embodiment, the proposed process allows you to distribute the hydrocarbon fraction into several reaction zones.

The oxygenate is fed to the last reaction zone.

The olefin-containing fraction is fed into the first and second reaction zones. For this, the stream of the olefin-containing fraction is divided into two streams.

Water is supplied to the first and second reaction zones. For this, the stream of water is divided into two streams.

In the process, the product stream from the first reaction zone is fed to the second reaction zone and the product stream from the second reaction zone is fed to the third reaction zone.

In this case, each of the streams supplied to a specific reaction zone can be heated before or after mixing with other streams.

The feed streams fed to a particular reaction zone are mixed in a mixing zone located upstream of the catalyst bed of that reaction zone. The mixing zone of the reaction zone can be, for example:

• a layer of granules of neutral material placed in front of the layer of zeolite catalyst, for example, a protective layer, forecontact;

• connecting line (main) connecting the reaction zones;

• a heater (or preheater) located between the reaction zones.

The product stream from the third reaction zone is separated into a hydrocarbon product fraction and an aqueous product fraction . The aqueous fraction of the product is withdrawn.

The hydrocarbon fraction of the product is further separated into a liquid hydrocarbon product and a gaseous product by means of fractionation and stabilization. In particular, settling and degassing of the aqueous phase, debutanization of the hydrocarbon phase, condensation of propane, etc. can be carried out. The gaseous product can be further separated into a gaseous product fraction enriched in C ₃ -C ₄ hydrocarbons and a gaseous product fraction enriched in C ₁ -C ₂ hydrocarbons.

The main component of a liquid hydrocarbon product is C ₅₊ hydrocarbons (hydrocarbons with five or more carbon atoms). Depending on the goals of a particular production, a liquid hydrocarbon product may contain not only C ₅₊ hydrocarbons, but also different amounts of dissolved gases C ₁ -C ₄ . In particular, in the production of motor gasolines, the presence of up to 3-5 wt. % of dissolved gases in summer gasolines and up to 5-7 wt. % of dissolved gases in winter gasolines. The gaseous product may include C ₁ -C ₄ hydrocarbons, nitrogen, hydrogen and other inorganic gases, as well as heavier hydrocarbons.

Product streams can be directed to external heat exchangers, such as recuperative heat exchangers, to heat the feed streams and pre-cool the product streams.

Examples of

The results achieved are illustrated in Examples 1-14 below.

Examples 1-6, 14 and Comparative Examples 7-9 show the case for the production of gasolines. Examples 10-13 show the possibility of obtaining concentrates of aromatic compounds.

The proposed process makes it possible to produce a liquid hydrocarbon product that can be used as gasoline or as a concentrate of aromatic compounds.

The difference between gasoline and aroma concentrate lies in the total aroma content of the product. There are states and enterprises that limit the maximum content of total aromatics in commercial gasolines at 35 vol. % (about 38-40 wt.% aromatics).

In this regard, a liquid hydrocarbon product with a total aromatic hydrocarbon content of not more than 40 wt. % refers to gasoline. In particular, the proposed method makes it possible to produce a liquid hydrocarbon product that can be sold as commercial motor gasoline without additional compounding.

Liquid hydrocarbon product with a total aromatic hydrocarbon content of more than 40 wt. % refers to concentrates of aromatic compounds. In particular, the proposed method makes it possible to produce a liquid hydrocarbon product that can be used as a high-octane aromatics concentrate, which plays the role of the main component in the compounding of motor gasolines.

Note that depending on the state or enterprise, the maximum allowable content of aromatic compounds in commercial gasolines, different from 40 wt. %.

The concentration of aromatics in the resulting liquid hydrocarbon product can be controlled using several parameters. In particular, an increase in the feed temperature and / or a decrease in the mass feed rate of the feed leads to an increase in the mass fraction of aromatics in the resulting liquid hydrocarbon product.

In particular, Examples 10-13 demonstrate the preparation of concentrates of aromatic compounds with an aromatic content of more than 40 wt. % at temperatures of 390-450 ° C and / or at mass feed rates of raw materials from 0.1 to 0.9 h ^-1 . Such aromatic concentrates can be used as the main component in the compounding (mixing) of commercial gasolines. It is also possible to use concentrates of aromatic compounds for further processing by petrochemical methods.

Comparative examples 7-9 differ from examples according to the invention in that the supply of water to the reaction zones was not carried out, and the distribution of oxygenate and olefin-containing fraction differed from that recommended according to the proposed method.

To carry out examples 1-14, a catalytic unit was used, including three reactors connected in series, with a total catalyst load of up to 9 liters. The reactors are designated as first, second and third reaction zones, R ₁₀₁ , R ₂₀₁ , R _301, respectively.

The reactors are structurally as close as possible to the adiabatic type, the heat exchange between the catalyst bed and the vessel is minimized. The catalyst baskets are placed in the reactor vessel so that a gap (approximately 2 mm) remains between the wall of the basket and the strong body. Each reactor is installed in a thermostat with three heating zones. Three thermocouples are placed between the surfaces of the heating elements and the outer surface of the reactor vessel. On the contrary, thermocouples are also located on the inner wall of the reactor basket casing. There is also an air gap not exceeding 3-4 mm between the inner surface of the thermostat and the outer surface of the reactor. The control loops maintain a constant temperature difference between the thermocouples at the outer wall of the reactor and the thermocouple opposite at the inner surface of the reactor basket.

In the process, the product stream from the first reaction zone is fed to the second reaction zone and the product stream from the second reaction zone is fed to the third reaction zone.

Liquid and gaseous products for analysis began to be taken 4 hours after the start of the feed.

Table 1 shows the chemical compositions of the hydrocarbon fractions used in Examples 1-14. In particular, the 62-85 ° C fraction (fr. 62-85 ° C) is the benzene-forming part of the catalytic reforming feedstock (approximate boiling range 62-85 ° C). The raffinate can be a mixture, predominantly of gasoline-range hydrocarbons, which have not undergone conversion during the catalytic reforming process. The raffinate can be described as a by-product gasoline cut taken from an aromatic hydrocarbon extractive distillation unit. For example, the raffinate can be a by-product of the extractive distillation of the benzene-toluene fraction. Also, the raffinate can be a by-product of the extractive distillation of the toluene-xylene fraction.

The presented hydrocarbon fractions are characterized by a high content of isoparaffins, from 42 to 56 wt. %. Such components are poorly processed into high-octane aromatics in standard gasoline production processes. The isoparaffins of the raw materials presented in Table 1 have too high a molecular weight to serve as a raw material for the classical isomerization of C ₅ -C ₆ fractions to obtain high-octane motor gasoline. In this case, the hydrocarbon fractions contain from 23 to 46 wt. % С ₆ hydrocarbons (benzene forming part of feedstock for catalytic reforming purposes).

Table 2 shows the compositions of the olefin-containing fractions used in Examples 1-14. The used olefin-containing fractions can be considered, for example, as a model of a dry gas of catalytic cracking (the composition of the SGCC was obtained by averaging the data of the refinery over several months of the catalytic cracking unit operation). However, we note that the name and the process of origin of the olefin-containing fractions may vary depending on the enterprise and the region. Attention should be paid to the chemical composition of the fraction used, in particular, the olefin-containing fraction should include C ₂ -C ₄ olefins in a total amount of 10 to 50 wt. %. Preferably, the mass fraction of C ₅₊ hydrocarbons in the olefin-containing fraction is not more than 5.0 wt. %. Preferably, the volume fraction of hydrogen sulfide in the olefin-containing fraction is at most 0.005%. Also, the olefin-containing fraction may contain hydrogen at a concentration of 0.5 to 8 wt. %, preferably from 2.3 to 8 wt. % hydrogen.

Methanol technical grade "A" GOST 2222-95 was used as oxygenate in examples 1-4, 7-10 and 13-14. Examples 5 and 12 used dimethyl ether (DME), 99%. Examples 6 and 11 used 95% ethanol.

Table 3 shows the compositions of the zeolite catalysts used in examples 1-14.

Table 4 shows the conditions and basic parameters of examples 1-9. The hydrocarbon fraction in examples 1-9 is fed to the first reaction zone.

Example 14 repeats the conditions of Example 1, except that in Example 14 the hydrocarbon fraction is distributed over three reaction zones in a ratio of 60/30/10 wt. %. The experiments were carried out at a pressure of 15-40 bar (1.5-4.0 MPa), preferably 22-27 bar (2.2-2.7 MPa). The% oxygenate substitution parameter (the percentage of oxygenate substitution for olefin-containing fractions) is calculated using formulas (4) - (6) on pages 3-4 of this Description.

Table 5 and Table 7 show the composition of the liquid hydrocarbon product in Examples 1-7. Example 14 shows the yield of liquid hydrocarbon product C ₅₊ 79.4 wt. % on the supplied hydrocarbon fraction at RON of the product 87.6 units. and an aromatic content of 25.1 wt. % (data are given for a liquid hydrocarbon product that does not contain dissolved gases, similar to Table 5).

Table 7 shows the composition of gasoline after separation of gaseous products from it, while the content of dissolved gases in gasoline is stabilized at 3-5 wt. % (stabilized liquid hydrocarbon product). Such a product can be considered as stable gasoline or as a high-octane base for the production of commercial gasolines. Products in Table 7 contain from 3 to 5 wt. % of dissolved gases C_one-FROM_four... However, depending on the goals of a particular production, a liquid hydrocarbon product may contain different amounts of dissolved gases C_one-FROM_four... In particular, in the production of motor gasolines, the presence of up to 3-5 wt. % of dissolved gases in summer gasolines and up to 5-7 wt. % of dissolved gases in winter gasolines. The desired amount of dissolved gases in the product is controlled by standard fractionation and stabilization techniques.

Table 5 shows the composition of the products for the same experiments as Table 7, however, Table 5 shows the composition of the liquid hydrocarbon products without dissolved gases C ₁ -C ₄ (C ₅₊ fraction of the hydrocarbon fraction of the product). Typically, production does not require a product that does not contain dissolved gases. However, a comparison of the yield and composition of C ₅₊ products is more revealing. Liquid hydrocarbon products obtained and stored under different conditions may contain different amounts of dissolved gases. In this case, the content of dissolved gases can vary unevenly over time, changing the chemical composition. This can lead to inadequate comparison of the yield and quality of products from different experiments, especially when comparing results from different enterprises. Therefore, it is more preferable to compare the parameters of a product that does not contain dissolved gases. However, we note that, depending on the goals of a particular production, the liquid hydrocarbon product may contain not only C ₅₊ hydrocarbons, but also different amounts of dissolved gases C ₁ -C ₄ , as shown in Table 7, for example.

Since C ₅₊ hydrocarbons (hydrocarbons with five or more carbon atoms) are the main component of a liquid hydrocarbon product, the yield of a liquid hydrocarbon product increases simultaneously with the yield of C ₅₊ hydrocarbons.

Table 6 shows the conditions and basic parameters of examples 10-13. The hydrocarbon fraction in examples 10-13 is fed to the first reaction zone. The experiments were carried out at a pressure of 22-27 bar (2.2-2.7 MPa).

The gaseous product in examples 1-14 consisted mainly of saturated hydrocarbons and nitrogen. The source of nitrogen is the olefin-containing fractions fed to the reaction. In the examples according to the invention, the content in the gaseous product of hydrocarbons C ₃₊ (mainly propane) was 34-64 vol. %. The total content of olefins in the gaseous product was 0.4-1.1 vol. %, which shows a high degree of conversion of olefins in the feed. The ethane content was 0.3-1.2 vol. %, which indicates the suppression of side processes of ethylene hydrogenation by hydrogen of the feedstock.

Observations

Reduction of heavy hydrocarbons, tar and end boiling point of the product

It was noted that the replacement of oxygenate with an olefin-containing fraction during the joint processing of hydrocarbon fractions and oxygenates into gasolines increases the content of heavy C ₁₂₊ hydrocarbons in the produced gasolines. At the same time, the production of a product with high boiling ends is observed (the boiling end is above 215 ° C). Production of a product with a high resin content (above 5 mg / 100 cm ³ ) can also be observed. These negative factors complicate the use of the product for the production of commercial gasolines, since for the latter the temperature of the end boiling point and the resin content are strictly regulated.

The minimum content of heavy hydrocarbons C ₁₂₊ in the hydrocarbon product was observed when only oxygenate was used as an additional feedstock (i.e., the percentage of oxygenate replacement by an olefin-containing fraction was 0%). This approach leads to an increase in the cost of producing a unit of product, because low-demand olefin-containing fractions are usually significantly cheaper than oxygenates for a refinery. An example of using only oxygenate as a supplemental feedstock is shown in Comparative Example 7, where a hydrocarbon fraction is fed to the first reaction zone and methanol is distributed to the first, second and third reaction zones. In Comparative Example 7, the end boiling point of the product is 217 ° C, which is relatively close to the required 215 ° C. However, for this it is necessary to use more than 20 wt. % methanol in relation to the weight of the supplied raw material. Both methanol and other aliphatic alcohols are not produced in typical refineries. Such enterprises will have to purchase alcohols from third-party organizations. This complicates the logistics of gasoline production and increases the cost of producing a unit of high-octane gasoline. At the same time, low-demand olefin-containing fractions can be produced in-house as a by-product. For example, SGCC is produced as a by-product of catalytic cracking, and its in-plant price is often equal to that of fuel gas. Thus, replacing oxygenate with olefin-containing fractions will reduce the cost of production per unit of product.

It was noted that attempts to completely replace oxygenate with an olefin-containing fraction _{increase the content of С 12+} hydrocarbons by a factor of 1.5 - 2. Comparative example 8 shows a consequence of this approach: the hydrocarbon fraction is fed to the first reaction zone, dry catalytic cracking gas is distributed in the first, second and third reaction zones. As a result, the end-boiling point of the product reaches 229 ° C, the resin content reaches 6.8 mg / cm ³ .

When the oxygenate is partially replaced by an olefin-containing fraction, under the conditions of their joint distributed supply to the reaction zones, the proportion of heavy C ₁₂₊ hydrocarbons can increase threefold. Comparative Example 9 shows the combined feeding of both methanol and SGCC to the first, second and third reaction zones while feeding the hydrocarbon fraction to the first reaction zone. As a result, the end-boiling point of the product reaches 238 ° C, the resin content reaches 9.0 mg / cm ³ .

Thus, when trying to replace oxygenate with little-demanded olefin-containing fractions, the problem arises of obtaining a product with a boiling point above the required 215 ° C, and with a resin content above 5 mg / cm ³ .

We have found that these problems can be solved by feeding only oxygenate into the third reaction zone, while feeding olefin-containing fractions into the first and second reaction zones. It was also noted that the addition of water to the olefin-containing fraction when feeding it to the first and second reaction zones, and oxygenate to the third reaction zone, reduces the content of heavy hydrocarbons in the hydrocarbon product. As shown by examples 1-6, as a result of the application of the proposed method, it is possible to achieve the end boiling point of the resulting hydrocarbon product below 215 ° C. Also, as a result of the application of the proposed method, it is possible to achieve the resin content in the product below 5 mg / cm ³ .

Reduced coke formation

It was noticed that due to the implementation of the proposed method, the mass of coke accumulated on the sample of the zeolite catalyst for 30 hours of operation is reduced by 4-17% in comparison with the comparative examples.

Possibility to use olefin-containing fractions without preliminary increase in olefin concentration in them

As a technical result, the possibility of using little-demanded olefin-containing fractions as raw materials for the production of gasolines or concentrates of aromatic compounds is also being considered. Refineries produce olefin-containing fractions that are used as fuel. These are gases from catalytic cracking, gases from a delayed coking unit, olefin-containing fuel gases of various origins, etc. The content and composition of olefins in such streams is too low for commercially viable recovery. At the same time, the cost of streams burned as fuel is minimal. The involvement of such olefin-containing fractions in the production of gasolines or aromatic concentrates significantly increases the value of the stream for the enterprise.

Examples 1-6 and 10-14 demonstrate the possibility of using olefin-containing fractions with an olefin content of not more than 50 wt. %. In particular, it is possible to use gaseous sources of olefins with an olefin content of 10 wt. % (and more). This result allows for significant cost savings in the production of a unit of product compared to methods that use highly concentrated sources of olefins or chemically pure olefins.

The proposed method allows the use of diluted olefins instead of highly concentrated sources of olefins (eg, pure ethylene). This creates an opportunity as a source of olefins, semi-products and by-products of already existing petrochemical plants. Among them are dry gases of catalytic cracking, various fuel gases with an olefin content of 10 to 50 wt. %.

Possibility of using olefin-containing fractions without preliminary separation of hydrogen from them

In particular, it was found that the proposed method allows the use of olefin-containing fractions with a high hydrogen content as raw materials. Moreover, the proposed method does not require additional separation of hydrogen from the olefin-containing fraction.

In particular, examples 1-2, 4-6 and 11-14 use olefin-containing fractions with a hydrogen content of 0.5 to 8 wt. %. In this case, olefin-containing fractions were fed to the reaction zones without preliminary separation of hydrogen from them.

This result is important because fuel gases often contain olefins along with significant amounts of hydrogen. However, the presence of hydrogen in the olefin source can lead to side reactions.

In particular, in the course of preliminary studies outside the recommended range of conditions, it was noted that the inclusion of 0.5 - 8 wt. % hydrogen in olefin-containing fractions reduces the yield of a liquid hydrocarbon product by 2-4 wt. % (while maintaining the same molar flow of olefins and feed rate). Additionally, when the hydrogen content in the olefin-containing fractions is from 2.3 to 8 wt. %, there was a decrease in the share of high-octane alkyl-benzenes in the product by 1.2-2.3 wt. %. Similar results could be observed due to a side process of hydrogenation of feed olefins.

The application of the proposed method made it possible to suppress such negative effects, including by feeding oxygenate into the first reaction zone, while simultaneously feeding olefin-containing fractions into three reaction zones. In this case, the proportion of the olefin-containing fraction sent to the third reaction zone is greater than the proportion of the olefin-containing fraction sent to the first or second reaction zones.

Found that examples 1-2, 4-6 and 11-14 according to the invention do not show a decrease in the yield of liquid hydrocarbon product or a decrease in the content of alkyl benzenes in the product as a result of the inclusion of hydrogen in the olefin-containing fractions of the feed.

This result expands the capabilities of the method for the involvement of _{low-cost C 2} -C ₄ olefin sources in the production of gasolines or aromatic compound concentrates.

Lack of oxygenates in the liquid hydrocarbon product

The proposed method makes it possible to obtain a liquid hydrocarbon product that does not contain oxygenates. Oxygenants, in particular ethanol, are often used as octane-enhancing additives in the compounding of motor gasolines. However, the maximum content of oxygenates in commercial gasolines is strictly standardized. Liquid hydrocarbon products obtained in examples 1-7 and 10-14 do not contain oxygenates, however, they have a high octane number according to the research method (RON of the product is higher than 90 units). This combination of properties allows the use of the maximum allowable amount of oxygenates when compounding commercial gasolines based on the product obtained by the proposed method.

Ability to eliminate the recycling of gaseous products

Found that the proposed method eliminates the recycle of gaseous products. All examples, according to the proposed method, show the conversion of olefins C ₂ -C ₄ feed above 98 wt. %. Such a high degree of conversion in one pass of the feedstock through the reactor makes it possible to abandon the use of the recycle of gaseous products for the purpose of a more complete processing of the olefins of the feedstock.

Possibility of producing low-benzene aromatics concentrates

When obtaining concentrates of aromatic compounds , the possibility of producing low-benzene aromatic concentrates is considered as an additional technical result. There are several classical methods for obtaining FAU (fractions of aromatic hydrocarbons, they are also a concentrate of aromatic hydrocarbons). Aromatic concentrates can be obtained, for example, during catalytic reforming, or as by-products of refining. The resulting aromatic concentrates can be used as a high-octane base for compounding motor gasolines. Unfortunately, the known methods often lead to the production of an aromatic concentrate with an extremely high proportion of benzene (benzene content in the liquid hydrocarbon product is more than 15 wt.%). The high content of benzene in aromatics concentrate sharply limits its use when mixing motor gasolines, because The maximum benzene content in fuels is strictly controlled.

However, the proposed method for obtaining concentrates of aromatic compounds makes it possible to obtain low-benzene FAU (fractions of aromatic compounds). Obtained in examples 11-13, the liquid hydrocarbon product contains 55-59 wt. % aromatic hydrocarbons. In this case, the benzene content is 2 to 3 wt. %. Thus, the proposed method makes it possible to obtain FAA with a significantly lower benzene content in comparison with classical methods.

Possibility of producing aromatic concentrate with a high content of C _{8 alkylbenzenes.}

When obtaining concentrates of aromatic compounds , the possibility of producing aromatic concentrates with an increased content of C ₈ alkylbenzenes is considered as an additional technical result. Examples 10-13 demonstrate that the proposed method makes it possible to achieve the content of C ₈ alkylbenzenes in the liquid hydrocarbon product from 17 to 18 wt. %. In this case, the proportion of C ₈ aromatics in relation to the total aromatics reaches 29-31 rel. % Average RON of C ₈ alkylbenzenes reaches 112 units, which makes them attractive components for compounding high-octane gasolines.

Decrease in oxygenate consumption

It was found that the problem of reducing the consumption of oxygenates for the production of gasolines or concentrates of aromatic compounds can be solved by partially replacing oxygenates with low-demand olefin-containing fractions. This approach allows you to reduce the consumption of oxygenates while maintaining the yield and quality of the product.

Co-processing of hydrocarbon fractions and oxygenates (without the involvement of olefin-containing fractions) often makes it possible to obtain gasolines with high RON and high product yields. However, oxygenates such as methanol, ethanol, dimethyl ether are rarely available in refineries as cheap feedstocks. When the source of oxygenate cannot be found in the by-product or intermediate product of the enterprise itself, it has to be purchased from outside at the prices of the commercial product. This increases the cost of producing a unit of commercial gasoline, and complicates the production logistics.

At the same time, the proposed method makes it possible to partially replace oxygenates with a source of dilute olefins (olefin-containing fractions). Examples 1-6 and 10-14 show the possibility of replacing from 50 to 86% of the oxygenate with olefin-containing fractions. In particular, examples 1-6 demonstrate that the proposed method allows you to reduce the consumption of oxygenate to 2 - 4.4 wt. %. This effect can significantly reduce the consumption of oxygenate in the production of gasoline or concentrate of aromatic compounds (for example, see comparative example 7, where oxygenate is more than 20 wt.% From the weight of the supplied raw material).

Replacing from 50 to 86% oxygenate with an olefin-containing fraction, and reducing the consumed oxygenate to 2 - 4.4% of the mass of the supplied raw material, allows you to reduce the cost of producing a product unit due to the fact that the cost of oxygenate for the enterprise exceeds the cost of little-demanded olefin fractions and water.

The calculation of the percentage of substitution of oxygenates for olefin-containing fractions is carried out according to formulas (4) - (6) on page 3 of this Description. The examples according to the invention show the possibility of replacing from 34 to 82% of the oxygenate with olefin-containing fractions to obtain a liquid hydrocarbon product RON of more than 90 units.

The provided formulas (4) - (6) can be applied to the already known methods of joint processing of hydrocarbon fractions and oxygenates (without involving olefin-containing fractions) into gasolines. In this case, formulas (4) - (6) make it possible to calculate the amount (molar flow, mol / h) of oxygenate in a known method, which can be replaced by available olefin-containing fractions without loss of quality and product yield.

Distributed supply of hydrocarbon fraction

It was noticed that changing the supply of the hydrocarbon fraction to the reaction zones makes it possible to control several parameters of the process. In particular, the distribution of the hydrocarbon fraction into two or three reaction zones makes it possible to further increase the yield and / or selectivity of the formation of C ₅₊ hydrocarbons (hydrocarbons with the number of carbon atoms of five or more). Also, in the case of distributed feeding of the hydrocarbon fraction into several reaction zones, cracking can be suppressed. isoparaffins with two or more alkyl substituents with the formation of lower hydrocarbons C ₁ -C ₄ . Also, as a result of the distribution of the hydrocarbon fraction into several reaction zones, a decrease in the dealkylation of alkylaromatic hydrocarbons can be observed.

In particular, Example 14 shows the possibility of distributing the hydrocarbon fraction over several reaction zones. Example 14 repeats the conditions of Example 1, except for a change in the distribution of the hydrocarbon fraction. In example 1, the distribution of the hydrocarbon fraction over the reaction zones R ₁₀₁ / R ₂₀₁ / R ₃₀₁ was 100/0/0 wt. %. Example 14 retains the same mass flow rates of raw materials as in Example 1, however, the hydrocarbon fraction is distributed over the three reaction zones in a ratio of 60/30/10 wt. %. As a result, it is possible to increase the product yield by 4 wt. % on the supplied hydrocarbon fraction (from 75.3 to 79.4 wt.% for a liquid hydrocarbon product that does not contain dissolved gases).

The aromatic content in the product of Example 14 (a liquid hydrocarbon product that does not contain dissolved gases C ₁ -C ₄ ) is reduced by 2.8 wt. % compared to example 1 (from 27.9 to 25.1 wt%). Typically, as the concentration of aromatics in the product decreases, the octane rating of the product is expected to decrease. However, it was found that the RHI of the product of Example 14 is practically indistinguishable from the RHI of the product of Example 1 (87.6 units and 87.4 units, respectively). This effect can be explained by a decrease in the cracking of high-octane C ₅ -C ₈ isoparaffins (isoparaffins with individual research octane numbers more than 72 units) as a result of the distributed supply of the hydrocarbon fraction to several reaction zones.

It is also possible, if necessary, to distribute the entire flow of the hydrocarbon fraction only to the second or only to the third reaction zone.

Claims (47)

1. A method for producing a liquid hydrocarbon product containing aromatic compounds, in which three streams are used as raw materials, the first of which includes a hydrocarbon fraction, the second stream includes an oxygenate, the third stream includes an olefin-containing fraction, and a) the olefin-containing fraction comprises one or more olefins selected from the group consisting of ethylene, propylene, normal butylenes, isobutylene, in a total amount of 10 to 50 wt%, b) using three reaction zones filled with zeolite catalyst, c) the first stream is fed to at least one reaction zone, d) the second stream is fed only to the last reaction zone, e) the third stream is fed to the first and second reaction zones, f) wherein water is added to the first and second reaction zones, g) and the product stream from the first reaction zone is fed to the second reaction zone and the product stream from the second reaction zone is fed to the third reaction zone. 2. The method according to claim 1, wherein the liquid hydrocarbon product containing aromatics is gasoline if the content of aromatic compounds is less than 40 wt%, or the liquid hydrocarbon product containing aromatics is an aromatic concentrate if the content of aromatic compounds is compounds is more than 40 wt.%. 3. A process according to claim 1, wherein the first stream is preferably fed to the first reaction zone. 4. The method according to claim 1, in which the hydrocarbon fraction contains normal paraffins in the amount of 15-24 wt.%, Isoparaffins in the amount of 42-56 wt.%, Naphthenes in the amount of 22-40 wt.%, The rest is aromatic hydrocarbons and olefins. 5. A process according to claim 1, wherein the hydrocarbon fraction contains 0 to 80 wt% C ₆ hydrocarbons, preferably 23 to 46 wt% C ₆ hydrocarbons, most preferably 36 to 46 wt% C ₆ hydrocarbons. 6. A process according to claim 1, wherein the hydrocarbon fraction contains 0 to 70 wt% C ₇ isoparaffins, preferably 26 to 50 wt% C ₇ isoparaffins, most preferably 26 to 38 wt% C ₇ isoparaffins. 7. The method according to claim 1, in which the hydrocarbon fraction can be selected from the group including straight-run gasoline, stable gas gasoline, light gas condensate, gasoline fraction with boiling range of about 62-85 ° C, raffinate, and mixtures thereof. 8. A process according to claim 1, wherein the weight fraction of C ₅₊ hydrocarbons in the first olefin-containing fraction is from 0 to 10.0 wt%, preferably from 0 to 5.0 wt%. 9. A process according to claim 1, wherein the olefin-containing fraction may comprise C ₅₊ olefins, eg, pentenes, hexenes. 10. The method of claim 1, wherein the olefin-containing fraction may include methane, ethane, propane, butanes, nitrogen. 11. The method according to claim 1, wherein the olefin-containing fraction contains from 0.5 to 8 wt% hydrogen. 12. The method according to claim 1, wherein The olefin-containing fraction contains from 2.3 to 8 wt% hydrogen. 13. The method of claim 1, wherein the olefin-containing fraction is selected from the group consisting of dry catalytic cracking gas, catalytic cracking wet gas, other catalytic cracking gases and their fractionation products, coking unit off-gas, Fischer-Tropsch synthesis gases, and their mixtures. 14. The method according to claim 1, in which the olefin-containing fraction is selected from the group consisting of propane-propylene fractions, butane-butylene fractions, thermal cracking gas, visbreaking gas, hydrocracking off-gases, pyrolysis gas, catalytic reforming waste gases, and mixtures thereof ... 15. The method of claim 1, wherein the olefin-containing fraction comprises dry catalytic cracking gas and contains 25 to 40 wt% C ₂ -C ₄ olefins. 16. The method according to claim 1, in which the oxygenate is selected from the group consisting of aliphatic alcohols, for example, methanol, ethanol, crude methanol, technical methanol, ethanol, ethers, for example dimethyl ether, as well as mixtures thereof, including with water ... 17. A process according to claim 1, wherein the oxygenate may contain impurities such as aldehydes, carboxylic acids, esters. 18. The method according to claim 1, wherein the hydrocarbon fraction comprises 62-74 wt% of the feed. 19. The process according to claim 1, wherein the olefin-containing fraction is 16-24 wt.% Of the feed. 20. The method of claim 1, wherein the oxygenate comprises 2-4 wt% of the feed. 21. The method according to claim 1, wherein the water comprises 7-10 wt% of the feed. 22. The process according to claim 1, wherein the olefin-containing fraction is distributed between the first and second reaction zones in a ratio of 29-72 wt% / 71-28 wt%. 23. The method of claim 1, wherein the water is distributed between the first and second reaction zones in a ratio of 29-54 wt% / 71-46 wt%. 24. A method according to claim 1, wherein the process pressure is 1.5 to 4.0 MPa, preferably 2.2 to 2.7 MPa. 25. The method according to claim 1, wherein the temperature of the stream at the inlet to the first / second / third reaction zones is 340-450 ° C / 340-450 ° C / 350-450 ° C. 26. The method according to claim 1, wherein the mass feed rate of the feed is 0.5 to 10 h ^-1 , preferably 1-3 h ^-1 . 27. The method according to claim 1, wherein the temperature of the stream at the inlet to the first / second / third reaction zones is 340-380 ° C / 340-380 ° C / 350-380 ° C. 28. The method according to claim 1, wherein the mass feed rate of the feed is 0.9 to 10 h ^-1 , preferably 1-3 h ^-1 . 29. The method according to claim 1, wherein the temperature of the stream at the inlet to the first / second / third reaction zones is 390-450 ° C / 390-450 ° C / 390-450 ° C. 30. The method according to claim 1, in which the mass feed rate of the raw material is from 0.1 to 0.9 h ^-1 . 31. The method according to claim 1, wherein the distribution of the catalyst over the reaction zones is 17-33 wt.% / 28-43 wt.% / 33-50 wt.% Of the total amount of catalyst for the first / second / third reaction zones, respectively. 32. The method of claim 1, wherein the zeolite catalyst comprises: a) a zeolite of the ZSM-5 type with a SiO ₂ / Al ₂ O ₃ modulus from 43 to 95 in an amount from 65 to 80 wt%, b) sodium oxide in an amount from 0.04 to 0.15 wt%, c) zinc oxide in an amount of 1.0-5.5 wt%, d) oxides of rare earth elements in a total amount of 0.5-5.0 wt%, e) a binder comprising silica, alumina, or mixtures thereof. 33. The method of claim 32, wherein the zeolite catalyst is free of platinum metals. 34. The method of claim 32, wherein the rare earths are selected from the group consisting of lanthanum, praseodymium, neodymium, cerium, and mixtures thereof. 35. The method of claim 1, wherein the reaction is carried out in the gas phase in a fixed bed of catalyst.