RU2372380C1 - Method of selective treatment of gasoline fractions of catalytic cracking (versions) - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: inventions relates to oil processing, particularly to methods of refining of gasoline fractions. Invention relates to method of selective treatment of gasoline fractions of catalytic cracking by means of its stepped hydro-refining at presence of alumo-oxide catalyst in medium of hydrogen at increased pressure and temperature with separation of product of the first stage for light and sinking fractions, with following hydro-refining of sinking fraction at second stage at temperature 280-340°C, pressure 2-3 MPa, volume velocity of raw material feeding 4-8 hour^-1 and mixing of received product after the second stage of hydro-refining with light fraction of product of the first stage with receiving of cleaned product. Separation of product of the first stage or separation of initial gasoline for light and sinking fractions is implemented by temperature 70-90°C at processing of raw materials with content of sulfur higher than 0.16% wt, 90-120°C - at processing of raw materials with content of sulfur 0.005-0.16% wt.

EFFECT: declared methods provide for reduction of sulfur content up to level not more than 0,0010% wt in gasoline fraction at minimal reduction of content of olefinic hydrocarbons.

3 cl, 3 ex, 5 tbl

Description

The invention relates to oil refining, in particular to methods for hydrofining gasoline fractions, and can be used in the oil refining and petrochemical industries.

An increase in motor fuel consumption with a decrease in demand for residual oil products leads to an increase in the depth of oil refining. At the same time, the requirements for operational and environmental characteristics of fuels are being tightened. In particular, in motor gasolines the content of sulfur, aromatic and olefinic hydrocarbons is limited with an increase in the octane number (Table 1).

Table 1 Data of the Technical Regulation of the Russian Federation “On requirements for automobile and aviation gasoline, diesel and marine fuel, jet fuel and heating oil” (approved by the Decree of the Government of the Russian Federation of February 27, 2008 No. 118) Indicator Class Norms 2 3 four 5 Sulfur content, wt.% No more 0,0500 0.0150 0.0050 0.0010 The hydrocarbon content, vol.% Not more than: - aromatic Unnormalized 42 35 35 - olefin eighteen eighteen eighteen Octane number by: - THEM 92 95 95 95 - MM 83 85 85 85 Release allowed until 12/31/2008 12/31/2009 12/31/2012 -

It is possible to combine solving the problems of deepening oil refining and obtaining marketable products that meet the requirements of modern standards through the development and use of new hydrofining methods, the so-called "secondary" fractions obtained as a result of processes such as catalytic cracking, thermal cracking, visbreaking, and coking.

Improving the quality of catalytic cracking gasolines, which are one of the main multi-tonnage high-octane components of gasolines and determining the consumer properties of the latter at most refineries, is especially relevant.

The good antiknock properties (octane number) of catalytic cracking gasolines is due to the high content of olefinic hydrocarbons in them (up to 50 vol.%). Olefin hydrocarbons, unlike dienes, do not adversely affect other commodity characteristics of motor gasolines, in particular oxidative stability.

The main indicator limiting the use of catalytic cracking gasolines in the composition of commercial gasoline is an increased sulfur content.

The latter depends on the sulfur content in the raw material of the process - vacuum gas oil, as well as on the boiling range of the selected gasoline fraction. From 2 to 10% of the sulfur contained in the feed goes to the broad gasoline fraction of catalytic cracking (nk-220 ° C) [Rivkinson I. Reducing the sulfur content of gasoline by using new technologies, catalytic cracking catalysts and additives. Moscow Conference on Oil Refining Technologies, June 25-26, 2001].

In cases where non-hydrotreated raw materials are processed at catalytic cracking plants, the high sulfur content in the resulting gasoline fractions (0.2-0.4 wt.%) Makes it difficult to use them for the preparation of marketable gasolines.

During the processing of deeply purified vacuum gas oil, the sulfur content in the wide gasoline fraction of catalytic cracking is at least 50 ppmw, which is a limitation for the production of class 5 marketable gasoline.

It is possible to reduce the content of sulfur and diene hydrocarbons in gasoline fractions of catalytic cracking by hydrofining.

The method of hydrofining catalytic cracking gasolines along with a high degree of removal of sulfur compounds and diene hydrocarbons should provide a minimum level of hydrogenation of olefinic hydrocarbons, which are the main carrier of the octane number of catalytic cracking gasoline.

Most of the known methods for refining gasolines of secondary processes, including catalytic cracking gasoline, include hydrotreating them in a mixture with straight-run gasoline or diesel fractions [Akhmetov S.A. Technology of deep processing of oil and gas. Ufa: Gilem, 2002, p. 559-573; Kaminsky E.F., Khavkin V.A. Deep oil refining: technological and environmental aspects. M .: Chemistry, 2001, p.342-344].

The disadvantages of this technology include a significant thermal (up to 80 ° C in the reactor) effect, which negatively affects the stability of the catalytic system. In addition, the resulting product can only be used as reforming feedstock. It is not practical to use it as a component of commercial gasoline, since along with the removal of components undesirable for commercial gasolines (sulfur and diene), the content of olefinic hydrocarbons in them will significantly decrease, as a result, the octane number of catalytic cracking gasoline will decrease by 8-10 points [Somov V.E ., Sadchikov I.A., Shershun V.G., Korelyakov L.V. Strategic priorities of Russian oil refineries. M .: TsNIITEneftekhim, 2002, p. 120].

Olefin hydrocarbons and organosulfur compounds are distributed unevenly over narrow fractions of catalytic cracking gasoline.

Almost all olefinic hydrocarbons are in fractions boiling up to 120 ° C. The sulfur content in light fractions (boiling up to a temperature of 120 ° C) is insignificant, not exceeding 30% of the sulfur content in a wide fraction. Sulfur in these fractions is represented mainly by easily convertible mercaptans [RF patent No. 2134287, bull. No. 22 dated 08/10/99].

The above distribution features of sulfur compounds and olefin hydrocarbons are used in methods for refining gasoline fractions of catalytic cracking based on preliminary fractionation of a wide fraction of catalytic cracking gasoline.

In particular, a method is known for hydrodesulphurization of a heavy gasoline fraction of catalytic cracking in the presence of an oxide-sulfide catalyst at elevated temperature and pressure, followed by returning the product of its hydrodesulfurization to a distillation column of a catalytic cracking unit and stabilizing it together with a non-cleaned light gasoline fraction [RF patent No. 2134287, bull. . No. 22 dated 08/10/99].

The implementation of this method allows to reduce the catalytic cracking gasoline sulfur content from 0.20-0.30 wt.% Only to 0.1-0.15 wt.% Without reducing the octane number. The disadvantage of this method is to obtain a product with a high sulfur content for commercial gasoline.

A known method of hydrotreating gasoline for catalytic cracking, including preliminary fractionation of a wide gasoline fraction into light and heavy, followed by hydrotreating the heavy fraction and mixing the light fraction with the heavy hydrotreating product [RF patent No. 224-501, bull. No. 35 dated 12/20/04]. The disadvantage of this method is the low sulfur removal depth for obtaining a product of a given quality.

A known method of improving the quality of the sulfur-containing olefin fraction of gasoline by processing it on an acid zeolite-containing catalyst with the aim of converting the olefins contained therein to aromatic hydrocarbons, followed by hydrodesulfurization of the resulting product [RF patent No. 2186830, bull. No. 22 dated 08/10/02]. The disadvantage of this method is to obtain a product with a high content of aromatic hydrocarbons (more than 50 vol.), Which limits its use as a component of commercial gasoline classes 4 and 5.

Known methods include preliminary separation of a wide fraction of catalytic cracking gasoline into light and heavy fractions with the direction of the light fraction to demercaptanization, heavy - to hydrotreating on alumina catalysts and subsequent mixing of light and heavy fractions purified from sulfur [RF patent No. 2327731, bull. No. 18 dated 06/27/08; US patent 5320742 from 07/14/94, the journal Refining and Petrochemicals, 2008, No. 6, pp. 10-13].

In accordance with the above technical solutions, mercaptans from the light fraction are removed either by using the Merox process (extractive demercaptanization) [US Patent 5,320,742 of 07/14/94, Journal of Refining and Petrochemicals, pp. 10-13, No. 6, 2008], or due to the implementation of the reaction of mercaptans with dienes (thioetherification) [RF Patent №2327731. Bull. No. 18 dated 06/27/08] on a microspherical alumina catalyst with a metal nickel content of 58 wt.%.

Both of the above methods for the removal of mercaptans from oil fractions are associated with a significant complication of the technological scheme of the enterprise, and the use of the Merox process will not ensure the removal of diene hydrocarbons from gasoline.

The closest in technical essence and the achieved results is a method for upgrading catalytic cracking gasoline, including hydrotreating it in the presence of aluminum-nickel or alumina-cobalt-molybdenum catalyst, dividing the resulting product into light and heavy fractions, distributing the heavy fraction into two parts, one of them is returned to the hydrotreating stage in mixtures with the feedstock, and the other compound with a light hydrotreated fraction and removed from the installation system as a component of gasoline [Pat nt RF №2258732, bull. No. 23 dated 08/20/05]. The disadvantage of this method is the inability to obtain a product with a sulfur content of less than 0.03 wt.%. A product with such a sulfur content cannot be used as a component of commercial gasoline that meets the requirements of modern standards.

The aim of the proposed technical solution is to develop a method for cleaning a wide gasoline fraction of catalytic cracking, which allows to reduce the sulfur content in it to a level of not more than 0.0010 wt.%, To remove diene hydrocarbons with a minimum reduction in the content of olefinic hydrocarbons with a loss of octane of not more than 0 , 5 p.

The goal is achieved by the method of selective purification of gasoline fractions of catalytic cracking by stepwise hydrofining in the presence of alumina catalysts in a hydrogen medium at elevated pressure and temperature, with the separation of the product of the first step into light and heavy fractions, followed by hydrofining of the heavy fraction in the second step at a temperature of 280-340 ° C, a pressure of 2-3 MPa, a volumetric feed rate of 4-8 hours ^-1 and mixing the resulting product after the second stage of hydrofining with a light fraction of the first stage product to obtain a purified product, provided that the separation of the first stage product into light and heavy fractions is carried out at a temperature of 70-90 ° C when processing raw materials with a sulfur content above 0.16 wt.%, 90-120 ° C - in the processing of raw materials with a sulfur content of 0.005-0.16 wt.%, The first stage of hydrofining is carried out at a temperature of 200-250 ° C, a pressure of 2-3 MPa, a volumetric feed rate of 6-10 h ^-1 in an axial type apparatus, divided into 2 or 3 sections with the volume of the catalyst each in the course of raw materials in the ratio 1,0: 1,5 or 1,0: 1,5: 2,0, by feeding gas-raw material mixture into the intersection spaces in proportion to the catalyst volume of each section or

by the method of selective purification of gasoline fractions of catalytic cracking by their stepwise hydrofining in the presence of alumina catalysts in a hydrogen medium at elevated pressure and temperature, with the separation of the initial gasoline into light and heavy fractions at a temperature of 70-90 ° C during the processing of raw materials with sulfur contents above 0.16 wt %, 90-120 ° C - when processing raw materials with a sulfur content of 0.005-0.16 wt.%, The light fraction is subjected to the first stage of hydrofining, which is carried out in an axial type apparatus, divided and 2 or 3 sections with a catalyst volume of each along the feedstock in a ratio of 1.0: 1.5 or 1.0: 1.5: 2.0, feeding a gas-raw mixture into the intersection spaces is proportional to the volume of catalyst of each section, followed by hydrofining of the heavy fraction in the second stage at a temperature of 280-340 ° C, a pressure of 2-3 MPa, a volumetric feed rate of 4-8 h ^-1 and mixing the obtained product after the second stage of hydrofining with a light fraction of the first stage product to obtain a purified product or

by the method of selective purification of gasoline fractions of catalytic cracking by stepwise hydrofining in the presence of alumina catalysts in a hydrogen medium at elevated pressure and temperature, with the separation of the product of the first stage into light and heavy fractions, followed by hydrofining of the heavy fraction in the second stage at a temperature of 280-340 ° C, pressure 2-3 MPa, volumetric feed rate of 4-8 h ^-1, and mixing the resulting product after the second stage hydrotreating the light fraction from the first product the first step to obtain a purified product, provided that the separation of the product of the first step into light and heavy fractions is carried out at a temperature of 70-90 ° C during processing of raw materials with a sulfur content above 0.16 wt.%, 90-120 ° C - during processing raw materials with a sulfur content of 0.005-0.16 wt.%, the first stage of hydrofining is carried out in two or three sequentially tied apparatus of the axial type with a volume of catalyst in each in a ratio of 1.0: 1.5 or 1.0: 1.5: 2 , 0 by feeding between the reactors of the gas-feed mixture in proportion to the volume of catalyst in each the reactor.

A distinctive feature of the invention is that the separation of the product of the first stage or the source gasoline into light and heavy fractions is carried out at a temperature of 70-90 ° C during processing of raw materials with a sulfur content above 0.16 wt.%, 90-120 ° C - during processing raw materials with a sulfur content of 0.005-0.16 wt.%, the first stage of hydrofining is carried out at a temperature of 200-250 ° C, a pressure of 2-3 MPa, a volumetric feed rate of 6-10 h ^-1 in an axial type apparatus, divided into 2 or 3 sections with a catalyst volume of each in the course of raw materials in a ratio of 1, 0: 1.5 or 1.0: 1.5: 2.0, feeding into the intersection spaces of a gas-raw material mixture in proportion to the volume of catalyst in each section; the first stage can be carried out in two or three sequentially tied axial-type apparatuses with a catalyst volume along the feedstock in a ratio of 1.0: 1.5 or 1.0: 1.5: 2.0 with a gas-feed mixture between reactors proportional to the volume of catalyst in each reactor.

The proposed method for the selective purification of gasoline fractions of catalytic cracking is as follows.

The broad stable fraction from the catalytic cracking unit is subjected to hydrofining (first stage) on aluminum-nickel and / or cobalt-molybdenum catalysts at a pressure of 2-3 MPa, a space feed rate of 6-10 h ^-1 , and a temperature at the reactor inlet of 200-240 ° С.

Hydrobleaching is carried out either in an axial type reactor, divided into 2 or 3 sections with a useful catalyst volume of each in a ratio of 1.0: 1.5 or 1.0: 1.5: 2.0, changing along the feedstock, or in two or three series-connected reactors with a similar distribution of the useful volume of the catalyst. Into the intersection spaces (or the tube space between the reactors) a gas-raw material mixture is supplied in an amount proportional to the volume of the catalyst in each section of the reactor (or in each reactor).

The product obtained in the first stage of hydrofining, is divided into two fractions - light and heavy. When processing the feedstock (a wide gasoline fraction of catalytic cracking) with a sulfur content above 0.16 wt.%, The temperature of the end of boiling of the light fraction and the beginning of heavy boiling is in the range of 70-90 ° C. When processing raw materials with a sulfur content of 0.005-0.16 wt.%, The separation boundary of light and heavy fractions is 90-120 ° C.

A special case of the implementation of the proposed technical solution is the separation of a wide fraction of catalytic cracking gasoline into light and heavy fractions in accordance with the conditions described above with hydrofining of the light fraction in the conditions of the first stage.

The heavy fraction is subjected to hydrotreating (second stage) at a pressure of 2-3 MPa, volumetric feed rate of 4-8 h ^-1, a temperature at the reactor inlet 280-340 ° C, at alyumonikel- and / or cobalt-molybdenum catalysts.

The product obtained in the second stage is mixed with a light fraction isolated from the product of the first stage or hydrotreated in the first stage.

The use of an axial type apparatus for carrying out the first stage of hydrofining, divided into 2 or 3 sections with a useful catalyst volume in the ratio of 1.0: 1.5 or 1.0: 1.5: 2.0 along the feedstock, or two or three in series bound reactors with a similar distribution of the catalyst volume with the supply of gas-feed mixture to the intersection spaces (or tube space between the reactors) in proportion to the volume of the catalyst in each section of the reactor (or in each reactor) allows us to provide conditions for maximum evrascheniya mercaptans contained in the feed hydrocarbon and a diene with minimum hydrogenation of olefins.

The most reactive compounds of the processed raw materials are dienes. They react with hydrogen even at room temperature.

Among the sulfur compounds contained in the gasoline fractions, mercaptans are most active in reactions with hydrogen. At a pressure of 2-3 MPa, a temperature of 200-240 ° C in the presence of an aluminum-cobalt-molybdenum catalyst with a sufficient amount of hydrogen, the mercaptans of the oil fractions almost completely turn into hydrogen sulfide and the corresponding paraffin hydrocarbon [I. Kalechits. Chemistry of hydrogenation processes in fuel processing. M., Chemistry, 1973, S. 283-284].

Olefins can turn into paraffins at a temperature of 100 ° C [Carrer P. Course in Organic Chemistry. L .: Goskhimizdat, 1960, p.63]. In the presence of hydrogen sulfide and organic sulfur compounds, the olefin hydrogenation reactions are slowed down and under certain conditions (pressure 2-3 MPa, temperature no higher than 240 ° C, space velocity 8-10 h ^-1 ) by selecting a catalyst, it is possible to create conditions for the selective conversion of mercaptans in the presence of olefins. The temperature in the reaction zone above 240 ° C leads to undesirable in this case, the active occurrence of hydrogenation reactions of olefinic hydrocarbons [Kalechits I.V. Chemistry of hydrogenation processes in fuel processing. M., Chemistry, 1973, S. 290-293].

The implementation of the reactions of the conversion of mercaptans and hydrogenation of dienes, which are desirable for the first stage of the technology under consideration, is accompanied by significant heat generation (91850-2100 kJ / kg) [Technological calculations of oil refining plants. M., Chemistry, 1987, p.143]. As a result, hydrofining of raw materials with the content of mercaptans and dienes characteristic of catalytic cracking gasolines will increase the temperature in the reaction zone (0.6-0.9 ° C per 1 m ^{3 of} raw materials), which leads to a violation of the conditions ensuring the selectivity of the process.

The conditions for dividing the reactor into sections or using several series-bound reactors specified in the claims of the invention and feeding a predetermined part of the gas-feed mixture stream into the space between the catalyst layers as a cooling agent will avoid excessive overheating along the catalyst profile and prevent undesired olefin hydrogenation reactions.

The boundaries of the fractionation of the product of the first stage of hydrofining specified in the formula of the invention are based on the distribution of olefins and organosulfur compounds in the fractions of catalytic cracking gasoline and provide maximum concentration of olefinic hydrocarbons in the light fraction, thiophene compounds (the most difficult to remove organosulfur) in the heavy fraction.

In the known methods for the purification of gasoline catalytic cracking, the above technical solutions are unknown.

Thus, this technical solution meets the criteria of "novelty" and "significant difference".

The following are specific examples of the implementation of the proposed method, which he illustrates, but is not limited to.

Examples

When testing the proposed method for the selective purification of gasoline fractions of catalytic cracking, samples obtained from the gasoline stabilization unit of catalytic cracking units with different sulfur contents were used as raw materials (Table 2).

table 2 Characteristics of raw material samples Indicator Value Sample 1 Sample 2 Sample 3 Sample 4 Sulfur content, wt.% 0.315 0.238 0.160 0.005 Fractional composition, ° C nk 45 65 36 32 10% boils off at 58 77 54 51 30% boils off at 73 89 70 69 50% boils off at 101 115 103 105 70% boils off at 137 140 136 138 90% boils off at 178 188 185 171 kk 205 220 215 210 The content of diene hydrocarbons, wt.% 1,5 1.4 1,6 1.8 The content of olefinic hydrocarbons, wt.% 47.2 31.7 42,4 39.6 Urine octane number, point 85.7 82.5 85.0 84.9

The first and second hydrofining stages were carried out using catalysts RK-242 and RK-231 in cobalt and nickel modifications (Table 3).

Table 3 Characteristics of the catalysts used in the implementation of the invention Characteristic RK-231 Co (Ni) RK-242 Co (Ni) TU number 2177-008-11711804 2177-011-40431454 Bulk weight 0.6-0.8 Not less than 0.7 Chemical composition, wt.%: - MoO ₃ 13.0-16.0 12.0-15.0 - CoO (NiO) 4.0-5.0 4.0-5.0 Strength index, kg / mm, not less 2.0 2.2

Example 1

First stage

The raw material sample 1 is fed into an axial three-section reactor, in each section of which a RK-242Co catalyst is loaded with a volume in each section of 100, 150 and 200 ml from top to bottom along the feed. Hydrobleaching is carried out under the following conditions: the volumetric feed rate of 10 h ^-1 , the ratio of hydrogen: feed 50 nm ³ / m ³ , a pressure of 30 kgf / cm ² , the temperature at the inlet to the reactor 250 ° C.

Raw materials are fed into the reactor inlet (first section) at a rate of 1000 ml / hour, 1500 ml / hour is additionally introduced into the space between the first and second sections, and 2000 ml / hour between the second and third sections. The product obtained by hydrofining in the first stage is divided into two fractions:

- light with a boiling end of 70 ° C (yield 30 vol.% from raw materials),

- heavy with a boiling point of 70 ° C (yield 70 vol.% from raw materials).

The light fraction is sent to the mixing unit, and the heavy fraction is fed to the second stage.

Second stage

The heavy fraction of the first stage hydrofining product (70-205 ° C) is fed into the second stage reactor, in which the RK-231Co catalyst with a volume of 780 ml is loaded. Hydrobleaching is carried out at a temperature of 340 ° C, a volumetric feed rate of 4 h ^-1 , the ratio of hydrogen: raw material 100 nm ³ / m ³ .

The hydrogenate obtained in the second stage is mixed with a light fraction of the hydrogenate of the first stage.

The resulting product is characterized by the following indicators:

- sulfur content - 0.0001 wt.%;

- octane number (MOC) - 85.2 p.

Example 2

Raw material sample 1 is divided into two fractions:

- light with a boiling end of 70 ° C (yield 30 vol.% from raw materials),

- heavy with a boiling point of 70 ° C (yield 70 vol.% from raw materials).

First stage

A fraction with a boiling end of 70 ° C, constituting 30% of the feed, is sent to the first stage.

As the reactor, an axial three-section apparatus is used, in each section of which the RK-242Co catalyst is loaded with a volume in each section of 100, 150 and 200 ml from top to bottom along the feedstock. Hydrobleaching is carried out under the following conditions: volumetric feed rate of the fraction 10 h ^-1 , the ratio of hydrogen: raw materials 50 nm ³ / m ³ , a pressure of 30 kgf / cm ² , the temperature at the inlet to the reactor 250 ° C.

A fraction with a boiling end of 70 ° C is fed to the reactor inlet (first section) at a rate of 1000 ml / hour, 1500 ml / hour is additionally introduced into the space between the first and second sections, and 2000 ml / hour of the same fraction between the second and third sections.

The product obtained by hydrofining in the first stage is sent to the mixing unit.

Second stage

The heavy fraction of the feedstock (with a boiling point of 70 ° C) is fed to the second stage reactor, in which the RK-231Co catalyst is loaded.

Hydrobleaching is carried out at a temperature of 340 ° C, a volumetric feed rate of 4 h ^-1 , the ratio of hydrogen: raw material 100 nm ³ / m ³ .

The hydrogenate obtained in the second stage is mixed with the hydrogenate of the first stage.

The resulting product is characterized by the following indicators:

- sulfur content - 0.0001 wt.%;

- octane number (MOC) - 85.2 p.

Example 3

Raw material sample 2 is fed to the reactor block, which includes three series-connected reactors, each of which is loaded with a PK-231Co catalyst with a volume of 100, 150 and 200 ml in each reactor along the raw material. Hydrobleaching is carried out under the following conditions: volumetric feed rate of 6 h ^-1 , the ratio of hydrogen: raw materials 50 nm ³ / m ³ , a pressure of 20 kgf / cm ² , the temperature at the inlet to the reactor 200 ° C.

Raw materials are fed into the first reactor along the line at a rate of 600 ml / hour, 900 ml / hour is additionally supplied to the inlet of the second reactor, and 1200 ml / hour to the inlet of the third.

The product obtained by hydrofining in the first stage is divided into two fractions:

- light with a boiling end of 90 ° C (yield 40 vol.% from raw materials),

- heavy with a boiling point of 90 ° C (yield 60 vol.% from raw materials).

The light fraction is sent to the mixing unit, the heavy fraction is fed to the second stage.

Second stage

The heavy fraction of the first stage hydrofining product (90-220 ° C) is fed to the second stage reactor, in which 405 ml PK-231Ni catalyst is loaded. Hydrobleaching is carried out at a temperature of 340 ° C, a volumetric feed rate of 4 h ^-1 , the ratio of hydrogen: raw material 100 nm ³ / m ³ .

The hydrogenate obtained in the second stage is mixed with a light fraction of the hydrogenate of the first stage.

The resulting product is characterized by the following indicators:

- sulfur content - 0,0007 wt.%;

- octane number (MOC) - 85.0 p.

The conditions and results of the implementation of the proposed technical solution according to examples 1-17 are shown in tables 4 and 5.

The sequence of operations when implementing the proposed technical solution according to examples 4-17 is carried out by analogy with example 1.

It can be seen that the quality of the product in the examples made in accordance with the formula of the invention (examples 1-5) exceeds the quality of the products in tests conducted with violations of the conditions laid down in the formula of the invention (examples 6-16), and the prototype (example 17).

In particular, the use of one single-section reactor during the implementation of the present invention (Example 6), non-compliance with the specified ratios of the volumes of catalysts over sections of the reactor or separate series-connected reactors (Examples 7-8), the distribution of raw materials between sections or reactors (Examples 9-10) lead to a significant increasing the temperature of the first stage of hydrofining (50-120 ° C), the latter creates favorable conditions for undesired hydrogenation of olefins. As a result, the octane number of the resulting product is reduced compared to raw materials by 6-19 p., Which is unacceptable.

Failure to comply with the claims of the present invention for the separation of the first-stage product into light and heavy fractions (examples 11-14) results in a product with either a high sulfur content (examples 12, 14) or a low octane number (examples 11, 13).

Negatively affects the quality of the resulting product and non-compliance with the technological regime of the first stage specified in the formula of the invention, examples (15, 16).

When implementing the method of hydrofining catalytic cracking gasoline in accordance with the prototype (example 17), a product with an unacceptably high sulfur content and low octane number is obtained.

Claims (3)

1. A method for the selective purification of gasoline fractions of catalytic cracking by stepwise hydrofining in the presence of alumina catalysts in a hydrogen atmosphere at elevated pressure and temperature, with the separation of the product of the first step into light and heavy fractions, followed by hydrofining of the heavy fraction in the second step at a temperature of 280-340 ° C, a pressure of 2-3 MPa, volumetric feed rate of 4-8 h ^-1, and mixing the resulting product after the second stage hydrotreating with a light product fraction of the First steps to obtain a purified product, characterized in that the separation of the product of the first step into light and heavy fractions is carried out at a temperature of 70-90 ° C when processing raw materials with a sulfur content above 0.16 wt.% 90-120 ° C - when processing raw materials with sulfur content of 0.005-0.16 wt.% the first stage of hydrofining is carried out at a temperature of 200-250 ° C, a pressure of 2-3 MPa, a volumetric feed rate of 6-10 h ^-1 in an axial type apparatus, divided into 2 or 3 sections with the volume of each catalyst along the feed in a ratio of 1.0: 1.5 or 1.0: 1.5: 2.0, feeding between ektsionnye space gazosyrevoy mixture proportional to the volume of catalyst of each section. 2. A method for the selective purification of gasoline fractions of catalytic cracking by stepwise hydrofining in the presence of alumina catalysts in a hydrogen medium at elevated pressure and temperature with the separation of the source gasoline into light and heavy fractions, the separation of the source gasoline into light and heavy fractions is carried out at a temperature of 70-90 ° C during the processing of raw materials with a sulfur content above 0.16 wt.% 90-120 ° C - when processing raw materials with a sulfur content of 0.005-0.16 wt.%, The light fraction is subjected to the first stage of hydrofining which is carried out in an axial type apparatus, divided into 2 or 3 sections with a catalyst volume of each along the raw material in a ratio of 1.0: 1.5 or 1.0: 1.5: 2.0, by feeding proportional gas-oil mixture into the intersection spaces the catalyst volume of each section, followed by hydrofining of the heavy fraction in the second stage at a temperature of 280-340 ° C, a pressure of 2-3 MPa, a bulk feed rate of 4-8 h ^-1 and mixing the resulting product after the second hydrofining stage with a light fraction of the first stage product with about ischennogo product. 3. A method for the selective purification of gasoline fractions of catalytic cracking by their stepwise hydrofining in the presence of alumina catalysts in a hydrogen medium at elevated pressure and temperature, with the separation of the product of the first step into light and heavy fractions, followed by hydrofining of the heavy fraction in the second step at a temperature of 280-340 ° C and a pressure of 2-3 MPa, volumetric feed rate of 4-8 h ^-1, and mixing the resulting product after the second stage hydrotreating the light fraction from the first product tupeni with obtaining a purified product, characterized in that the separation of the product of the first stage into light and heavy fractions is carried out at a temperature of 70-90 ° when processing raw materials with a sulfur content above 0.16 wt.% 90-120 ° C - when processing raw materials with sulfur content of 0.005-0.16 wt.% the first stage of hydrofining is carried out in two or three sequentially tied reactors, with the volume of catalyst in each reactor along the raw material, taken in the ratio of 1.0: 1.5 or 1.0: 1.5 : 2.0, feeding proportions of the gas-raw material mixture into the tube space between the reactors ionically to the catalyst volume of each section.