Upgrading of aromatics derived from catalytic cracking gasoline for aromatics complex

Abstract

The present invention relates to a method and apparatus for processing and separating aromatic compounds from gasoline feedstock, comprising the following stages / units: selective hydrogenation (A) of gasoline feedstock (1) in the presence of hydrogen (2) to produce a selectively hydrogenated effluent (3); fractionation (B) of the selectively hydrogenated effluent (3) to produce at least a C5- fraction (4) containing compounds having 5 or fewer carbon atoms and a C6+ fraction (5) containing compounds having at least 6 carbon atoms; hydrogenation (C) of the C6+ fraction (5) to produce a hydrogenated effluent (6); extraction of aromatics (D) from the hydrogenated effluent (6) to produce at least an aromatics stream (17) concentrated with respect to the composition of the hydrogenated effluent (6) and a raffinate (10) concentrated with non-aromatic compounds.

Description

Technical Field

[0001] The field of this invention relates to the processing and separation of aromatic compounds derived from gasoline feedstocks, such as benzene, toluene, xylene (BTX), and aromatic compounds having 9 or 10 carbon atoms (A9, A10), for use in the petrochemical industry, including gasoline fractions produced by catalytic cracking. Existing technology

[0002] Patent FR 2925065 B1 claims a scheme enabling the production of high-octane gasoline feedstock using aromatics as a co-product upstream of an aromatics complex. This sequence provides a unit for separating aromatics from one or more naphtha fractions to produce a raffinate containing a majority of non-aromatic compounds, which is at least partially fed to a catalytic reforming unit to produce a high-octane gasoline fraction, which is then recycled to the aromatics separation unit or the "aromatics complex" unit. The extract containing a majority of aromatics from the aromatics separation unit is fed, in whole or in part, to the aromatics complex. Invention Overview

[0004] Against this background, the first objective of this specification is to provide an improved treatment and separation method for producing aromatics suitable for injection into an aromatics complex.

[0005] Surprisingly, the applicant company has determined that processing gasoline feedstocks, such as catalytically cracked gasoline (e.g., FCC, i.e., fluid catalytic cracking), through a series of selective hydrogenation, fractionation, hydrogenation, and extraction stages enables improved separation of aromatic compounds with 6 to 11 carbon atoms.

[0006] According to the first aspect, the above-mentioned objectives and other advantages are achieved by a method for processing and separating aromatic compounds from gasoline feedstock, said method comprising the following stages:

[0007] - Selective hydrogenation of gasoline feedstock to hydrogenate at least a diene contained in the gasoline feedstock in the presence of hydrogen and produce a selectively hydrogenated effluent;

[0008] - Selective hydrotreating of the effluent to produce at least a C5- fraction containing compounds having 5 or fewer carbon atoms and a C6+ fraction containing compounds having at least 6 carbon atoms;

[0009] - The hydrogenation of the C6+ fraction is carried out in the presence of hydrogen to hydrogenate at least the olefin contained in the C6+ fraction and produce a hydrogenated effluent.

[0010] - Extract aromatics from the hydrogenation effluent to produce at least an aromatics stream concentrated with respect to the aromatics, and a raffinate concentrated with respect to the composition of the hydrogenation effluent but not with the aromatics.

[0011] According to one or more embodiments, the gasoline feedstock comprises gasoline fractions obtained from a catalytic cracking unit.

[0012] According to one or more embodiments, the selective hydrogenation stage is carried out under at least one of the following operating conditions: the presence of at least one catalyst comprising a support and an active phase containing at least one Group VIII element, a temperature of 50 to 250°C, and 0.5 h. -1 Up to 20h -1 Liquid hourly space velocity (LHSV), pressure from 0.4 to 5 MPa, and 2 to 100 Sm 3 / m 3 The volume ratio of H2 to gasoline feedstock.

[0013] According to one or more embodiments, the fractionation stage is controlled to produce a C6+ fraction containing compounds with a boiling point greater than 217°C at a content of less than or equal to 5000 ppm by weight.

[0014] According to one or more embodiments, the hydrogenation stage is carried out under at least one of the following operating conditions: the presence of at least one catalyst comprising a support and an active phase containing at least one Group VIII element, a temperature of 100 to 400°C, and 0.1 h. -1 Up to 20h -1 Liquid hourly space velocity (LHSV), pressure from 0.1 to 5 MPa (MPa absolute pressure), and 1 to 400 Sm 3 / m 3 The volume ratio of H2 to gasoline feedstock.

[0015] According to one or more implementation schemes, the aromatics extraction stage includes the following stages:

[0016] - Extracting aromatics from hydrogenated effluent using a liquid-liquid extractor, the liquid-liquid extractor being fed with a solvent stream to separate the raffinate and the extract, which is concentrated in aromatics relative to the composition of the hydrogenated effluent.

[0017] - The extract is stripped using an extract stripping section to separate the gas stream containing non-aromatic compounds and to purify the extract;

[0018] - Aromatics are separated from the purified extract and solvent using an aromatics recovery tower to separate the solvent stream and the overhead vapor containing the aromatics stream.

[0019] According to one or more embodiments, the aromatics extraction stage further includes at least one of the following stages:

[0020] - Feed a solvent stream containing a solvent into the liquid-liquid extractor, said solvent being selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea, and mixtures thereof;

[0021] - The gas stream undergoes phase separation in a condenser to separate the raffinate recirculation stream and the aqueous phase;

[0022] - The raffinate is washed with water using a water-feed scrubbing tower to produce a non-aromatic feed stream and an aqueous scrubbing liquid.

[0023] -At least a portion of the solvent stream is regenerated by vacuum steam stripping in a solvent regeneration section;

[0024] - The overhead vapor is condensed in a condenser to produce an aromatic feed stream.

[0025] According to one or more embodiments, the solvent stream contains sulfolane or is substantially composed of sulfolane.

[0026] According to one or more embodiments, the aromatics extraction stage further includes at least one of the following stages:

[0027] - The feed to the liquid-liquid extractor is a solvent stream selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof;

[0028] - The raffinate recirculation stream is recirculated to the liquid-liquid extractor;

[0029] -Water is produced by stripping the aqueous washing liquid and / or hydrocarbon compounds present in the aqueous phase using a water stripping section;

[0030] - Feed steam into the aromatics recovery tower to generate additional overhead steam containing steam, and condense the overhead steam in a condenser to generate an aromatics stream and water separated by sedimentation.

[0031] According to one or more embodiments, the aromatics extraction stage further includes at least one of the following stages:

[0032] The feed to the liquid-liquid extractor is a stream of solvents selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea, and mixtures thereof, and the stream contains water;

[0033] - The water produced in the water stripping section is recycled to the aromatics recovery tower.

[0034] According to one or more embodiments, at least one pyrolysis gasoline is fed into fractionation unit B and / or into hydrogenation unit C.

[0035] According to the second aspect, the above-mentioned objectives and other advantages are achieved by an apparatus for processing and separating aromatic compounds from gasoline feedstock, the apparatus comprising the following units:

[0036] - A selective hydrogenation unit for hydrogenating at least a diene contained in a gasoline feedstock in the presence of hydrogen and for generating a selective hydrogenation effluent;

[0037] - A fractionation unit for fractionating the selectively hydrogenated effluent and producing at least a C5- fraction containing compounds having 5 or fewer carbon atoms and a C6+ fraction containing compounds having at least 6 carbon atoms;

[0038] - A hydrogenation unit for hydrogenating at least the olefins contained in the C6+ fraction in the presence of hydrogen and producing a hydrogenated effluent;

[0039] - An aromatic extraction unit for extracting aromatics from the hydrogenated effluent and producing at least an aromatic stream concentrated with respect to the hydrogenated effluent and a raffinate concentrated with respect to the composition of the hydrogenated effluent but not with respect to the aromatic compounds.

[0040] According to one or more embodiments, the aromatics extraction unit includes the following elements:

[0041] -Liquid-liquid extractor, which is suitable for feeds containing solvent streams and hydrogenated effluents, and is suitable for separating raffinate and extracts that are concentrated in aromatics relative to the composition of the hydrogenated effluents;

[0042] - Extract stripping section, suitable for feed containing extractables, and suitable for separating gas streams containing non-aromatic compounds and purifying extractables; and

[0043] - A recovery tower, which is suitable for feeding a purified extract and for separating aromatics from the purified extract to produce a solvent stream and a tower top vapor containing the aromatic stream.

[0044] According to one or more embodiments, the aromatics extraction unit further includes at least one of the following elements:

[0045] -Liquid-liquid extractor, suitable for feeding a solvent stream containing a solvent selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof;

[0046] - A condenser settling device suitable for feeding the gas stream and for separating the gas stream to produce a raffinate recirculation stream and an aqueous phase;

[0047] - A water scrubbing tower, which is suitable for feeding water and the raffinate and is suitable for washing the raffinate with water to produce a non-aromatic feed stream and an aqueous scrubbing liquid.

[0048] - A solvent regeneration section, which is suitable for feeding at least a portion of the solvent stream and is suitable for regenerating said portion of the solvent stream by vacuum steam stripping;

[0049] - A condenser settling device suitable for feeding the overhead vapor of the column and suitable for condensing the overhead vapor to produce an aromatic stream.

[0050] According to one or more embodiments, the aromatics extraction unit further includes at least one of the following elements:

[0051] -Liquid-liquid extractor, suitable for feeding streams of solvents selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof;

[0052] -Liquid-liquid extractor, which is suitable for feeding a feed stream containing the raffinate recirculation stream;

[0053] - A water stripping section, which is suitable for feeding the aqueous washing liquid and / or the aqueous phase, and is suitable for stripping hydrocarbon compounds from the aqueous washing liquid and / or from the aqueous phase to produce water;

[0054] - An aromatics recovery tower, which is suitable for feeding steam and for generating additional overhead steam containing steam, and a condenser settling tank, which is suitable for condensing the overhead steam to produce an aromatics stream and water separated by settling.

[0055] According to one or more embodiments, the aromatics extraction unit further includes at least one of the following elements:

[0056] -Liquid-liquid extractor, which is suitable for feed with solvent streams containing sulfolane and water;

[0057] -Aromatic hydrocarbon recovery tower, which is suitable for feed containing water produced by the water stripping section.

[0058] The implementation schemes based on the foregoing aspects, as well as other features and advantages, will become apparent upon reading the following description, which is given by way of example only and not as a limitation, and with reference to the following figures.

[0059] List of Attachments

[0060] Figure 1 The diagram illustrates the processing and separation method according to the present invention.

[0061] Figure 2 The diagram shows that, according to Figure 1 The processing and separation methods further include a second fractionation tower.

[0062] Figure 3 The diagram shows that, according to Figure 1 and Figure 2 The methods and apparatus for aromatic hydrocarbon extraction, including stages and units.

[0063] Description of the implementation plan

[0064] Embodiments according to the present invention will now be described in detail. Numerous specific details are disclosed in the following detailed description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0065] In this application, the term "comprising" is synonymous with "including" and "containing" (meaning the same), and is inclusive or open-ended, not excluding other unstated elements. It is to be understood that the term "comprising" includes the exclusive and closed term "consisting of." The term "based on" is synonymous with "containing at least 50% by weight." Furthermore, in this specification, the terms "substantially" or "approximately" correspond to an approximation of ±5%, preferably ±1%, and very preferably ±0.5%. For example, an effluent substantially comprising compound A or composed of compound A corresponds to an effluent containing at least 95% by weight of compound A.

[0066] This invention relates to aromatic compounds derived from gasoline feedstocks, such as catalytic cracked gasoline, for use in the petrochemical industry, and particularly BTX compounds, as well as the separation of aromatic compounds having 9 or 10, and indeed even 11 carbon atoms (A9, A11). It particularly relates to an improved method and apparatus for separating aromatic compounds, comprising a series of selective hydrogenation, fractionation, hydrogenation, and extraction stages and units, enabling improved separation of aromatic compounds having 6 to 11 carbon atoms.

[0067] Specifically, refer to Figure 1 and Figure 2 The method and apparatus according to the invention relate to a selective hydrogenation stage / unit A, such that gasoline feedstock 1 can be selectively hydrogenated in the presence of hydrogen 2, and thus the (virtually all) dienes contained in the feedstock can be hydrogenated, and optionally a portion of the light sulfur compounds can be converted into heavier sulfur compounds. The method and apparatus according to the invention also relate to a fractionation stage / unit B (by means of a first fractionation column B1) of the selectively hydrogenated effluent 3, such that at least a gasoline fraction containing compounds having 5 or fewer carbon atoms (referred to as fraction C5-4) and a gasoline fraction containing compounds having at least 6 carbon atoms (referred to as (first) C6+ fraction 5) can be obtained, C6+ fraction 5 being sent to hydrogenation stage / unit C. Reference Figure 2 An additional fractionation stage (using a second fractionation tower B2) may exist before the hydrogenation stage / unit C to limit the presence of certain compounds considered contaminants in the C6+ fraction 5, thereby separating the heavy gasoline fraction 51. The second C6+ fraction 52 at the outlet of the additional fractionation stage is then sent to the hydrogenation stage / unit C. In hydrogenation unit C, alkenes and alkenyl aromatics are hydrogenated, while sulfur, nitrogen, and oxygen compounds are (substantially completely) hydrotreated. The hydrogenation effluent 6 is sent to the aromatics extraction stage / unit D, resulting in a concentrated (i.e., enriched) stream of aromatics (aromatics stream 17) and a concentrated stream of non-aromatics (raffinate 10, optionally washed). The envisioned aromatics separation method / apparatus allows for improved aromatics recovery yields while ensuring high purity, particularly benzene purity. The non-aromatics stream 19 may be sent to a thermal cracking stage / unit or a catalytic reforming stage / unit, for example, to increase aromatics production.

[0068] raw material

[0069] The method according to the invention can process gasoline feedstock. According to one or more embodiments, gasoline feedstock 1 comprises gasoline fractions obtained from a catalytic cracking unit. According to one or more embodiments, gasoline feedstock 1, relative to the total weight of the feedstock, consists of at least 50% or 60% by weight, preferably at least 70% or 80% by weight, very preferably at least 90% or 95% by weight, such as at least 97% or 99% by weight, gasoline fractions obtained from a catalytic cracking unit. According to one or more embodiments, gasoline feedstock 1 consists (entirely) of gasoline fractions obtained from a catalytic cracking unit. According to one or more embodiments, the gasoline fractions are obtained from units selected from a list of fluidized bed catalytic cracking (FCC) units.

[0070] According to one or more embodiments, gasoline feedstock 1 comprises compounds whose boiling point ranges from the boiling point of hydrocarbons having 2 or 3 carbon atoms (C2 or C3) to 260°C, preferably to 240°C or 220°C. According to one or more embodiments, gasoline feedstock 1 comprises compounds whose boiling point ranges from the boiling point of hydrocarbons having 4 or 5 carbon atoms (C4 or C5) to 260°C, preferably to 240°C or 220°C. According to one or more embodiments, the feedstock comprises compounds whose boiling point ranges from the boiling point of hydrocarbons having 5 carbon atoms (C5) to 260°C, preferably to 240°C, and most preferably to 220°C. In this patent application, when not specified, the boiling point of a compound is understood to refer to the boiling point of the compound at atmospheric pressure.

[0071] The feedstock comprises saturated and unsaturated hydrocarbon compounds. According to one or more embodiments, the feedstock is rich in (e.g., at least 40% by weight) unsaturated hydrocarbon compounds (e.g., monoolefins, dienes, aromatics). According to one or more embodiments, the feedstock comprises at least 50% by weight, preferably at least 60% by weight, and very preferably at least 70% by weight, relative to the total weight of the feedstock. According to one or more embodiments, the feedstock comprises at least 10% by weight, preferably at least 20% by weight, and very preferably at least 30% by weight (e.g., at least 40% by weight), relative to the total weight of the feedstock. According to one or more embodiments, the feedstock comprises at least 10% by weight, preferably at least 20% by weight, and very preferably at least 30% by weight (e.g., at least 40% by weight), relative to the total weight of the feedstock. According to one or more embodiments, the feedstock comprises less than 10% by weight of dienes. According to one or more embodiments, the feedstock comprises 0.1% by weight or from 0.5% by weight to 5% by weight of dienes relative to the total weight of the feedstock. According to one or more embodiments, the raw material contains at least 10% by weight of aromatic compounds, preferably at least 20% by weight, and very preferably at least 30% by weight (e.g., at least 40% by weight) of aromatic compounds relative to the total weight of the raw material.

[0072] The feedstock may additionally contain sulfur compounds. According to one or more embodiments, the feedstock contains 0 to 5000 ppm by weight (i.e., 0.5% by weight) of sulfur relative to the total weight of the feedstock. According to one or more embodiments, the feedstock contains 10 to 2000 ppm by weight of sulfur. The sulfur content in the feedstock is typically greater than 50 ppm by weight. The sulfur content typically depends on the sulfur content of the feedstock processed by FCC, whether pretreatment of the FCC feedstock is present, and the final boiling point of the fraction.

[0073] According to one or more embodiments, the feedstock processed by this method contains 0.5% to 5% by weight of diene, 20% to 50% by weight of olefin, 20% to 40% by weight of aromatic hydrocarbon, and 10 ppm to 0.5% by weight of sulfur relative to the total weight of the feedstock.

[0074] Selective hydrogenation

[0075] Gasoline feedstock 1 is treated in selective hydrogenation unit A in the presence of hydrogen 2 to at least partially hydrogenate the diene. According to one or more embodiments, the gasoline feedstock is also treated to carry out a reaction to increase the molecular weight of at least a portion of the light thiols (RSHs) that may be present in the feedstock, in order to obtain thioethers by reaction with olefins.

[0076] According to one or more embodiments, the gasoline to be treated is fed to a selective hydrogenation catalytic reactor containing at least one fixed or moving bed of catalyst for selective hydrogenation of dienes and optionally for increasing the molecular weight of light thiols.

[0077] According to one or more embodiments, the selective hydrogenation of dienes and optionally the reaction for increasing the molecular weight of light thiols are carried out on at least one catalyst comprising a support and an active phase containing at least one Group VIII element and optionally at least one Group VIb element. The Group VIII element is preferably selected from nickel and cobalt, and particularly nickel. The Group VIb element, when present, is preferably selected from molybdenum and tungsten, and very preferably molybdenum. The support for the selective hydrogenation catalyst is preferably an oxide support. The oxide support is preferably selected from alumina, nickel aluminate, silica, silicon carbide, or mixtures of these oxides. Alumina, such as γ-alumina, is preferred, and even more preferably high-purity alumina (e.g., with a purity of at least 99.8% by weight). According to one or more embodiments, the hydrogenation catalyst comprises an alumina-based support. According to one or more embodiments, the support comprises at least 50% alumina. According to one or more embodiments, the support is composed of alumina.

[0078] According to one or more embodiments, the selective hydrogenation catalyst contains at least one Group VIII element (e.g., nickel) in an amount of 0.5% to 20% by weight, preferably 1% to 12% by weight, relative to the total weight of the catalyst, based on the weight of the metal oxide. According to one or more embodiments, the selective hydrogenation catalyst contains at least one Group VIb element (e.g., molybdenum) in an amount of 3% to 30% by weight, preferably 6% to 18% by weight, relative to the total weight of the catalyst, based on the weight of the metal oxide. According to one or more embodiments, the selective hydrogenation catalyst has a Group VIII element / Group VIb element (e.g., Ni / Mo) molar ratio of 0.2 to 4, preferably 0.3 to 2.5. According to one or more embodiments, the catalyst is sulfided. The degree of sulfidation of the metal constituting the catalyst is preferably greater than 60%, and more preferably greater than 80%.

[0079] According to one or more embodiments, the selective hydrogenation catalyst contains nickel in the form of nickel oxide (NiO) at a weight of 1% to 12% relative to the total weight of the catalyst, and molybdenum in the form of molybdenum oxide (MoO3) at a weight of 6% to 18% relative to the total weight of the catalyst, and the nickel / molybdenum molar ratio is 0.3 to 2.5, and these metals are deposited on a support composed of alumina.

[0080] The chemical elements are classified into groups according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by DRLide, 81st edition, 2000-2001). For example, Group VIII according to the CAS classification corresponds to metals in columns 8, 9, and 10 according to the new IUPAC classification; Group VIb according to the CAS classification corresponds to metals in column 6 according to the new IUPAC classification. The content of Group VIII and Group VIb metals can be measured by X-ray fluorescence. The content of Group VIb and Group VIII metals in the catalyst is expressed as oxides, for example, after correction for loss on ignition of the catalyst sample in a muffle furnace at 550°C for 2 hours. Loss on ignition is attributed to the loss of moisture and can be determined according to ASTM D7348. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO, respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3, respectively.

[0081] According to one or more embodiments, during the selective hydrogenation stage, gasoline is contacted with the catalyst in the presence of hydrogen 2 at a temperature of 50 to 250°C, preferably 80 to 220°C, and even more preferably 90 to 200°C. According to one or more embodiments, the liquid hourly space velocity (LHSV) is 0.5 h⁻¹. -1 Up to 20h -1 1 hour preferred -1 Up to 10h -1 And even better, 2h -1 up to 6h -1 The unit of liquid hourly space velocity is m. 3 Raw materials / m 3 catalyst / hour (m 3 / m 3 / h). According to one or more embodiments, the pressure is 0.4 to 5 MPa, preferably 0.6 to 4 MPa, and even more preferably 1 to 3 MPa. According to one or more embodiments, the selective hydrogenation stage is 2 to 100 Sm. 3 / m 3 Preferred 3 to 30 Sm 3 / m 3 Hydrogen flow rate 2 (in standard m) 3 / hour) and the flow rate of the raw material to be processed (in m³ under standard conditions) 3 The process is carried out at an H2 / raw material volume ratio (expressed as / hour).

[0082] Advantageously, the selectively hydrogenated effluent 3 obtained at the outlet of selective hydrogenation unit A contains less than 1% by weight, preferably less than 0.5% by weight, and most preferably less than 0.1% by weight of diene relative to the total weight of selectively hydrogenated effluent 3.

[0083] At least a portion of the selectively hydrogenated effluent 3 is sent to fractionation unit B.

[0084] Fractionation

[0085] Fractionation of the effluent from the first selective hydrogenation stage yields at least two fractions: a gasoline fraction containing compounds having 5 or fewer carbon atoms, referred to as C5- fraction 4 or the desulfurized light gasoline fraction; a gasoline fraction containing compounds having at least 6 carbon atoms, referred to as (first) C6+ fraction 5 or the aromatics-rich gasoline fraction; and optionally, a heavy gasoline fraction as defined below.

[0086] According to one or more embodiments, C5-fraction 4 is a desulfurized (e.g., having a sulfur content of less than or equal to 10 ppm by weight) gasoline fraction and contains a large portion (e.g., at least 80 wt%, preferably 90 wt%, very preferably at least 95 wt%) of monoolefins (C2-C5 olefins) from gasoline feedstock 1.

[0087] According to one or more embodiments, C5-fraction 4 is removed from the top of the first fractionation column B1 and exits the method. For example, C5-fraction 4 can be sent to a gasoline pool. According to one or more embodiments, the cutpoint of C5-fraction 4 is carried out at a temperature below 100°C, preferably at a temperature between 40°C and 100°C. According to one or more embodiments, the cutpoint of C5-fraction 4 is between 45°C and 80°C.

[0088] The final boiling point of C5 fraction 4 is preferably selected to provide C5 fraction 4 with extremely low sulfur content (preferably less than 10 ppm by weight). Advantageously, the desulfurized C5 fraction 4 does not require a subsequent hydrodesulfurization stage. According to one or more embodiments, C5 fraction 4 contains a sulfur content of less than 100 ppm by weight, preferably less than 50 ppm by weight, and most preferably less than 10 ppm by weight.

[0089] The final boiling point of C5-fraction 4 is preferably selected to facilitate the recovery of benzene in C6+ fraction 5. According to one or more embodiments, C5-fraction 4 contains less than 10% by weight, preferably less than 5% by weight, and very preferably less than 1% by weight of benzene relative to the total weight of C5-fraction 4.

[0090] According to one or more embodiments, the C6+ fraction 5 comprises aromatic compounds with 6 to 11 carbon atoms / consistently consists of aromatic compounds with 6 to 11 carbon atoms. According to one or more embodiments, the C6+ fraction 5 comprises aromatic compounds with 6 to 10 carbon atoms / consistently consists of aromatic compounds with 6 to 10 carbon atoms. According to one or more embodiments, the C6+ fraction is an aromatic-rich gasoline fraction, preferably with the content of naphthalene and heavy compounds (e.g., aromatic compounds having 11 or more carbon atoms and / or compounds with a boiling point greater than 217°C) limited to less than or equal to 5000 ppm by weight, preferably less than or equal to 4500 ppm by weight, and very preferably less than or equal to 3000 ppm by weight.

[0091] According to one or more embodiments, C6+ fraction 5 is taken from the bottom of the first fractionation column B1. According to one or more embodiments, the cut-off point for C6+ fraction 5 is at a temperature greater than 40°C, preferably at a temperature between 45°C and 100°C. According to one or more embodiments, the cut-off point for C6+ fraction 5 is between 45°C and 80°C.

[0092] According to one or more embodiments, the C6+ fraction 5 contains compounds with a content of less than or equal to 5000 ppm by weight, preferably less than or equal to 4500 ppm by weight, and very preferably less than or equal to 3000 ppm by weight, said compounds comprising compounds with a boiling point greater than 217°C (including naphthalene) and / or aromatic compounds having at least 11 carbon atoms.

[0093] According to one or more embodiments, when C6+ fraction 5 has a content of compounds with a boiling point greater than 217°C and / or naphthalene and / or aromatic compounds having 11 or more carbon atoms at greater than 5000 ppm by weight or 4500 ppm by weight, a second fractionating column B2 can be used to separate C6+ fraction 5 into two fractions: a second C6+ fraction 52 at the top of the column, which has a content of compounds including compounds with a boiling point greater than 217°C (including naphthalene) and / or aromatic compounds having at least 6 carbon atoms at less than or equal to 5000 ppm by weight, preferably less than or equal to 4500 ppm by weight, and very preferably less than or equal to 3000 ppm by weight; and a heavy gasoline fraction 51 at the bottom of the column (referred to as the C11+ fraction), which has a content of compounds with a boiling point greater than 217°C and / or naphthalene and / or aromatic compounds having 11 or more carbon atoms at greater than or equal to 3000 ppm by weight or 4500 ppm by weight. According to one or more embodiments, the second C6+ fraction 52 substantially comprises compounds containing 6 to 9 or 10 carbon atoms. According to one or more embodiments, the heavy gasoline fraction 51 substantially comprises compounds containing at least 10 or 11 carbon atoms.

[0094] According to one or more embodiments, the heavy gasoline fraction 51 is directed to a hydrodesulfurization stage and an optional hydrodesulfurization effluent stabilization stage (a stage not described) to produce gasoline (e.g., with a sulfur content of less than 50 ppm by weight, preferably less than 10 ppm by weight).

[0095] According to one or more embodiments, the operating conditions of the second fractionation column B2 are adjusted to obtain a second C6+ fraction 52, which has a temperature difference (DT) of 130°C to 180°C, preferably 140°C to 160°C, between temperatures corresponding to 5% and 95% of the distillate weight. According to one or more embodiments, the temperature of the second C6+ fraction 52 corresponding to 5% of the distillate weight is 30°C to 80°C, preferably 50°C to 65°C, and the temperature of the aromatic-rich gasoline fraction corresponding to 95% of the distillate weight is 180°C to 220°C, preferably 190°C to 210°C. The method for determining the temperatures corresponding to 5% and 95% of the distillate weight is described in the literature Oil Gas Sci. Technol., Vol. 54 (1999), No. 4, pp. 431-438, entitled “CSD method” (CSD is an abbreviation for Conventional Simulated Distillation).

[0096] Advantageously, the first or second C6+ fraction (5 or 52) obtained from fractionation unit B contains at least 20% by weight, preferably at least 30% by weight, and very preferably at least 40% by weight (e.g. at least 50% by weight) of aromatic compounds relative to the total weight of the C6+ fraction.

[0097] The first or second C6+ fraction (5 or 52) obtained from fractionation unit B is at least partially sent to hydrogenation unit C.

[0098] hydrogenation

[0099] In hydrogenation unit C, the C6+ fraction 5 or 52 from the fractionation stage is processed in the presence of hydrogen to hydrogenate the olefins and alkenyl aromatics, and to (completely) hydrogenate (preferably substantially completely) the remaining sulfur, nitrogen and oxygen compounds.

[0100] According to one or more embodiments, pyrolysis gasoline 62 or 63 (PyGas) is fed into hydrogenation unit C, for example as a mixture with the feedstock of hydrogenation stage C, namely C6+ fraction 5 or 52. According to one or more embodiments, pyrolysis gasoline 62 is fed into the second fractionation column B2 of fractionation unit B. According to one or more embodiments, pyrolysis gasoline 61 is fed into fractionation unit B, for example as a mixture with selectively hydrotreated effluent 3.

[0101] According to one or more embodiments, the pyrolysis gasoline comprises or consists of C5-C12 fractions, with the following composition: 2% to 15% by weight of alkanes, 30% to 65% by weight of aromatics, 5% to 15% by weight of monoolefins, 15% to 30% by weight of dienes, 2% to 8% by weight of alkenyl aromatic compounds, and 20 to 2000 ppm by weight of sulfur, preferably 20 to 300 ppm by weight. This is because some difficult pyrolysis gasolines can have sulfur content up to 2000 ppm by weight, for example, for some difficult feedstocks.

[0102] According to one or more embodiments, pyrolysis gasoline is at least partially hydrotreated, for example, from a first hydrotreating stage referred to as HD1. In the case of reforming pyrolysis gasoline as an aromatics-rich fraction source, one conceivable treatment consists of two stages. The first stage (also referred to as HD1) aims at the selective hydrogenation of highly unsaturated compounds (dienes and alkenyl aromatics), and the second stage is the hydrotreating of sulfur compounds (also referred to as HD2) and the (preferably complete) hydrogenation of olefins. In the case of reforming pyrolysis gasoline as an aromatics-rich fraction source, standard practice is to separate C5- compounds for the gasoline pool (e.g., at the outlet of the HD1 stage) and send the C6+ fraction to the HD2 stage.

[0103] According to one or more embodiments, pyrolysis gasoline derived from at least a partially hydrotreated first hydrotreating stage known as HD1 has the following properties: C6-C8 fractions composed of: 3% to 21% by weight alkanes, 44% to 91% by weight aromatics, 7% to 21% by weight monoolefins and 20 to 300 ppm by weight sulfur, and for some difficult feedstocks even up to 2000 ppm by weight sulfur.

[0104] According to one or more embodiments, the hydrogenation stage is carried out in at least one fixed-bed or moving-bed catalytic reactor in the presence of one or more hydrogenation and hydrotreating catalyst beds.

[0105] According to one or more embodiments, the hydrogenation stage is carried out using a first bed comprising at least one catalyst, such that alkene compounds and optionally alkenyl aromatic compounds can be removed. According to one or more embodiments, the catalyst comprises a support and an active phase containing at least one Group VIII element and optionally at least one Group VIb element. The Group VIII element is preferably selected from nickel and cobalt, and particularly nickel. The Group VIb element, when present, is preferably selected from molybdenum and tungsten, and very preferably molybdenum. The support for the hydrogenation catalyst is preferably an oxide support. The oxide support is preferably selected from alumina, nickel aluminate, silica, silicon carbide, or mixtures of these oxides. Alumina, such as γ-alumina, is preferred, and even more preferably high-purity alumina (e.g., with a purity of at least 99.8% by weight). According to one or more embodiments, the hydrogenation catalyst comprises an alumina-based support, preferably composed of alumina.

[0106] According to one or more embodiments, the hydrotreating catalyst contains at least one Group VIII element (e.g., nickel) in an amount of 0.5% to 20% by weight, preferably 1% to 13% by weight, relative to the total weight of the catalyst, based on the weight of the metal oxide. According to one or more embodiments, the hydrogenation catalyst contains at least one Group VIb element (e.g., molybdenum) in an amount of 3% to 30% by weight, preferably 6% to 18% by weight, relative to the total weight of the catalyst, based on the weight of the metal oxide. According to one or more embodiments, the hydrogenation catalyst has a Group VIII element / Group VIb element (e.g., Ni / Mo) molar ratio of 0.2 to 4, preferably 0.3 to 2.5.

[0107] According to one or more embodiments, the catalyst is sulfided. The degree of sulfidation of the metal constituting the catalyst is preferably greater than 60%, and more preferably greater than 80%.

[0108] According to one or more embodiments, the hydrogenation catalyst contains nickel in the form of nickel oxide (NiO) at a weight of 1% to 13% relative to the total weight of the catalyst, and molybdenum in the form of molybdenum oxide (MoO3) at a weight of 6% to 18% relative to the total weight of the catalyst, and the nickel / molybdenum molar ratio is 0.3 to 2.5, and these metals are deposited on a support composed of alumina.

[0109] According to one or more embodiments, the hydrogenation catalyst contains cobalt in the form of cobalt oxide (CoO) at a weight of 1% to 13% relative to the total weight of the catalyst, and molybdenum in the form of molybdenum oxide (MoO3) at a weight of 6% to 18% relative to the total weight of the catalyst, with a cobalt / molybdenum molar ratio between 0.3 and 2.5, and these metals are deposited on a support composed of alumina.

[0110] According to one or more embodiments, during the hydrogenation stage, gasoline is contacted with a catalyst in the presence of hydrogen at a temperature of 100 to 400°C, preferably 200 to 380°C. According to one or more embodiments, the liquid hourly space velocity (LHSV) is 0.1 h⁻¹. -1 Up to 20h -1 According to one or more embodiments, the pressure is 0.1 to 5 MPaa, preferably 0.5 to 4 MPaa, and even more preferably 1 to 3.5 MPaa. According to one or more embodiments, the hydrogenation stage is 1 to 400 Sm. 3 / m 3 Or 1 to 300 Sm 3 / m 3 Hydrogen flow rate (in standard m) 3 / hour) and the flow rate of the raw material to be processed (in m³ under standard conditions) 3 The process is carried out at an H2 / raw material volume ratio (expressed as / hour).

[0111] According to one or more embodiments, the hydrogenation unit C further includes a (third) fractionation tower (not shown) to remove at least one of the following compounds: H2, H2S, light gases such as ethane, propane and butane, and compounds that may be present in the effluent leaving the catalytic hydrogenation reactor.

[0112] The hydrogenated effluent 6 obtained at the outlet of hydrogenation unit C will be directed at least partially to aromatics extraction unit D.

[0113] Extraction

[0114] The aromatic extraction unit D in this invention enables the processing of the hydrogenated effluent 6 to recover, on the one hand, a stream of non-aromatic compounds concentrated (referred to as raffinate 10) and on the other hand, a stream of aromatics concentrated relative to the composition of the hydrogenated effluent 6 (referred to as extract 11).

[0115] According to one or more implementation schemes, refer to Figure 3 The aromatic extraction unit D is a unit used for liquid-liquid extraction of aromatics.

[0116] According to one or more embodiments, a unit for liquid-liquid extraction of aromatics includes the following stages / apparatus:

[0117] -Liquid-liquid extraction is performed using a liquid-liquid extractor T1 with a solvent feed stream 9 to separate the raffinate 10 and the extract 11.

[0118] - The residual liquid 10 is washed with water in washing tower T2 (optional stage).

[0119] - Use steam stripping stage for water stripping (optional stage)

[0120] - Extract 11 was stripped using the T3 stripping section.

[0121] - Aromatics are separated using recovery tower T6 to separate aromatic stream 17 and solvent stream 9, and

[0122] - Regenerate the solvent using the solvent regeneration section (optional stage).

[0123] For simplicity, the optional water stripping section and solvent regeneration section are not presented. Figure 3 middle.

[0124] Liquid-liquid extractor T1

[0125] Liquid-liquid extraction allows for the separation of aromatics from non-aromatic compounds, such as alkanes and cycloalkanes, in hydrogenated effluent 6.

[0126] According to one or more embodiments, the feed of hydrogenated effluent 6 is substantially at the level of the midpoint (e.g., in the middle of the extractor).

[0127] According to one or more embodiments, the midpoint is a point located between the bottom and top of the liquid-liquid extractor T1. According to one or more embodiments, the midpoint corresponds to a point preferably arranged between 0.1×L and 0.9×L, more preferably between 0.2×L and 0.8×L, such as between 0.3×L and 0.7×L, or between 0.4×L and 0.6×L, where L is the length from the bottom to the top of the liquid-liquid extractor T1.

[0128] According to one or more embodiments, the solvent stream 9 is fed at a high point of the liquid-liquid extractor T1. According to one or more embodiments, the solvent stream 9 is fed at the top of the liquid-liquid extractor T1. In this application, a high point is understood to be a point located above the midpoint used for feeding the hydrogenated effluent 6.

[0129] According to one or more embodiments, the solvent comprises a compound selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea, and mixtures thereof. According to one or more embodiments, the solvent comprises or is composed of sulfolane. According to one or more embodiments, the solvent comprises at least 90% by weight, preferably at least 95% by weight (e.g., at least 99% by weight), sulfolane relative to the total weight of the solvent. According to one or more embodiments, the solvent further comprises an antisolvent, such as water. According to one or more embodiments, the antisolvent comprises or is composed of water. According to one or more embodiments, the solvent contains 0.01% to 5% by weight, preferably 0.1% to 3% by weight (e.g., 0.5% to 2% by weight) of an antisolvent, such as water, relative to the total weight of the solvent.

[0130] According to one or more embodiments, for example, the raffinate recirculation stream 15 obtained from the extract stripping section T3 is fed at the low point of the liquid-liquid extractor T1. According to one or more embodiments, the raffinate recirculation stream 15 is fed at the bottom of the liquid-liquid extractor T1. In this application, the low point is understood to be a point located below the midpoint used for feeding the hydrogenated effluent 6.

[0131] Advantageously, the liquid-liquid extractor T1 can therefore be divided into two parts. The upper part (relative to the midpoint for the feed hydrogenation effluent 6) allows for control of the aromatic yield by liquid-liquid extraction (particularly with sulfolane). The lower part of the liquid-liquid extractor T1 allows for the initial purification of aromatics using the raffinate recirculation stream 15. Thus, the liquid-liquid extractor T1 allows for the separation of the raffinate 10, which is lean in aromatics relative to the hydrogenation effluent 6, and the extract 11, which is concentrated in aromatics relative to the hydrogenation effluent 6. The raffinate 10 exits at the top of the liquid-liquid extractor T1 and is optionally sent to the water scrubbing tower T2. The extract 11 exits at the bottom of the liquid-liquid extractor T1 and is sent to the extract stripping section T3, preferably undergoing heat exchange with the solvent stream 9 (for simplicity, in...). Figure 3 (Not shown in the image). According to one or more embodiments, the liquid-liquid extractor T1 operates in adiabatic conditions.

[0132] According to one or more embodiments, the weight ratio of solvent stream 9 to hydrogenated effluent 6 is 0.1 to 50, preferably 0.5 to 20, more preferably 1 to 9, more preferably 3 to 8, such as 5 ± 1 or 6 ± 1. According to one or more embodiments, the weight ratio of recirculated stream 15 to hydrogenated effluent 6 is 0.05 to 10, preferably 0.1 to 8, more preferably 0.2 to 5, more preferably 0.3 to 2, such as 0.9 ± 0.2.

[0133] According to one or more embodiments, the extractor is operated at a pressure of 0.05 to 3 MPaa (0.5 to 30 bar absolute), preferably 0.1 to 2 MPaa (1 to 20 bar absolute), preferably 0.2 to 1.5 MPaa (2 to 15 bar absolute), preferably 0.3 to 1 MPaa (3 to 10 bar absolute), such as at 6.5 ± 2 MPaa, for example when the solvent contains sulfolane. According to one or more embodiments, the extractor is operated at a temperature of 10 to 150°C, preferably 15 to 120°C, preferably 20 to 100°C, preferably 30 to 90°C, such as 54 ± 5°C, for example when the solvent contains sulfolane.

[0134] Optional water scrubbing tower T2

[0135] The water washing of the raffinate 10 removes any solvent that may be present in it. Preferably, the raffinate 10 is cooled before entering the column. Preferably, the raffinate 10 enters at the bottom of the column, water 7 is introduced at the top, the non-aromatic feed stream 19 (from which the washed raffinate 10 is thus solvent-lean) exits at the top, and the aqueous wash liquid 18 (concentrated / solvent-rich) exits at the bottom. According to one or more embodiments, the non-aromatic feed stream 19 contains less than 100 ppm by weight, preferably less than 10 ppm by weight, and most preferably less than 1 ppm by weight of solvent. According to one or more embodiments, the aqueous wash liquid 18 is fed to a water stripping section (not shown).

[0136] Advantageously, the non-aromatic stream 19 contains less than 25% by weight, preferably less than 20% by weight, and most preferably less than 17% by weight of aromatic compounds relative to the total weight of the non-aromatic stream 19.

[0137] Extract stripping section T3

[0138] Stripping of extract 11 allows for the removal of non-aromatic compounds still present in extract 11. Extract 11, carrying aromatic compounds and solvent, is preferably introduced at the top of extract stripping section T3. In extract stripping section T3, the purity of extract 11 is improved because residual non-aromatic compounds carrying aromatic compounds (less soluble in the solvent) are extracted at the top of extract stripping section T3 in the form of gas stream 12. According to one or more embodiments, gas stream 12 is combined with water, such as water recovered at the top of water stripping section (not shown). Phase separation in condenser CD3 allows the hydrocarbon phase to be recycled to liquid-liquid extractor T1 as raffinate recirculation stream 15, while the aqueous phase 14 is optionally combined with aqueous washing liquid 18 and sent to water stripping section (not shown). The purified extract 13 was then sent to the aromatics recovery tower T6 to separate the aromatics from the solvent (especially sulfolane), and the solvent was recycled to the liquid-liquid extractor T1.

[0139] The stripping of extract 11 is preferably carried out under low pressure or even vacuum to improve the removal of non-aromatic compounds from the solvent (especially sulfolane). According to one or more embodiments, the extract stripping section T3 is operated at a column top pressure of 0.001 to 2 MPaa (0.01 to 20 bar absolute), preferably 0.005 to 1 MPaa (0.05 to 10 bar absolute), preferably 0.01 to 0.8 MPaa (0.1 to 8 bar absolute), preferably 0.03 to 0.5 MPaa (0.3 to 5 bar absolute), such as 0.14 ± 0.06 MPaa, for example when the solvent contains sulfolane. According to one or more embodiments, the extract stripping section T3 is operated at a bottom temperature of 50 to 300°C, preferably 100 to 250°C, preferably 130 to 200°C, preferably 145 to 195°C, such as 180 ± 5°C, for example when the solvent contains sulfolane.

[0140] Water vapor lift section (optional - not shown)

[0141] The stripping of the aqueous wash liquid 18 and the aqueous phase 14 allows for the removal of dissolved hydrocarbons (primarily non-aromatic hydrocarbons) from the top of the extract stripping section T3 and optionally from the water obtained from the water washing tower T2.

[0142] According to one or more embodiments, at least a portion of the water obtained at the outlet of the water stripping section is fed into the aromatics recovery tower T6 to increase the amount of stripping steam fed into the bottom of the aromatics recovery tower T6.

[0143] Aromatics Recovery Tower T6

[0144] The aromatics recovery tower T6 separates the purified extract 13 obtained from the bottom of the extract stripping section T3 into an aromatics stream 17 and a solvent stream 9. Preferably, the aromatics recovery tower T6 is operated under vacuum, particularly when the solvent contains sulfolane. Advantageously, operation under vacuum allows for the avoidance of excessive bottom temperatures that could lead to solvent decomposition. According to one or more embodiments, vapor 8, optionally combined with the solvent (regenerated), is injected into the bottom of the aromatics recovery tower T6 to improve the extraction of aromatics from the solvent (particularly sulfolane). The overhead vapor from the tower (which essentially contains aromatic compounds and optionally water) is condensed in the condenser CD6 and optionally separated by settling. According to one or more embodiments, a portion of the condensed overhead aromatic vapor is used as reflux from the aromatics recovery tower T6, while the remainder constituting the aromatics stream 17 exits the method and is preferably sent to an aromatics complex (a unit for the separation and production of aromatic compounds, particularly BTX compounds). A portion of the water 16 separated by settling in the condenser CD6 may optionally be sent to the water scrubbing tower T2, while the remainder is recycled to the water stripping section. The feed stream obtained from the bottom of the aromatics recovery tower T6 consists of regenerated solvent sent to the liquid-liquid extractor T1 and optionally to the extract stripping section T3 and / or to the solvent regeneration section (not shown).

[0145] According to one or more embodiments, the aromatics recovery tower T6 operates at a top pressure of 0.001 to 2 MPaa (0.01 to 20 bar absolute pressure), preferably 0.005 to 1 MPaa (0.05 to 10 bar absolute pressure), preferably 0.01 to 0.5 MPaa (0.1 to 5 bar absolute pressure), preferably 0.015 to 0.2 MPaa (0.15 to 2 bar absolute pressure), such as 0.06 ± 0.04 MPaa, for example when the solvent contains sulfolane. According to one or more embodiments, the aromatics recovery tower T6 operates at a bottom temperature of 50 to 300°C, preferably 100 to 250°C, preferably 120 to 200°C, preferably 130 to 195°C, such as 170 ± 25°C, for example when the solvent contains sulfolane.

[0146] Advantageously, the aromatic stream 17 contains at least 95% by weight, preferably at least 99% by weight, and most preferably at least 99.5% by weight (e.g., at least 99.5% by weight) of aromatic compounds relative to the total weight of the aromatic stream 17. Example

[0147] An embodiment of the method according to the present invention for separating aromatics derived from gasoline fractions obtained from catalytic cracking technology is as follows.

[0148] Table 1 shows the characteristics of FCC gasoline processed according to the method of the present invention.

[0149] Table 1

[0150] sulfur weight ppmS 70.6 Alkanes weight% 15.93 Olefins weight% 34.49 Diene weight% 0.92 Cycloalkanes weight% 4.72 Aromatics weight% 43.94 Including C6-C7 aromatics weight% 14.70 Including C8-C9 aromatics weight% 23.19 Including C10 aromatics weight% 5.61 Including C11+ aromatics weight% 0.44

[0151] Gasoline feedstock 1 is processed in selective hydrogenation unit A in the presence of catalyst A1. Selective hydrogenation catalyst A1 is a NiMo type catalyst on γ-alumina. The metal content in the catalyst, relative to the total weight of the catalyst, is 7 wt% NiO and 11 wt% MoO3, i.e., a Ni / Mo molar ratio of 1.2.

[0152] In a reactor containing catalyst A1, gasoline feedstock 1 is contacted with hydrogen 2. This stage of the method involves the selective hydrogenation of dienes and the conversion (increasing molecular weight) of some light thiols (RSHs) present in the feedstock.

[0153] The operating conditions used in the selective hydrogenation reactor are:

[0154] -temperature:

[0155] Total pressure: 2.5 MPaa

[0156] -H2 / Raw material volume ratio: 5 standard m 3 hydrogen / m 3 Gasoline under standard conditions (vol / vol)

[0157] -Liquid Time Space Velocity (LHSV):

[0158] Selectively hydrogenated effluent 3, having a low diene content and a low content of light sulfur compounds (which increase molecular weight during the selective hydrogenation stage), is fed into fractionation unit B to separate C5- fraction 4 at the top of the first fractionation column B1 and C6+ fraction 5 at the bottom of the column. The characteristics of C5- fraction 4 and C6+ fraction 5 are shown in Table 2. As shown in Table 2, C5- fraction 4 has a low sulfur content. C5- fraction 4 corresponds to approximately 25% by weight of selectively hydrogenated effluent 3. C6+ fraction 5 corresponds to approximately 75% by weight of selectively hydrogenated effluent 3. C6+ fraction 5 has a naphthalene content of 0.4% by weight.

[0159] Table 2

[0160] sulfur weight ppmS 93.3 Alkanes weight% 28.7 12.6 Olefins weight% 70.1 22.9 Diene weight% 0.58 0.16 Cycloalkanes weight% 0.61 6.18 Aromatics weight% 0.01 58.16 Including C6-C7 aromatics weight% 0.01 19.42 Including C8-C9 aromatics weight% 30.73 Including C10 aromatics weight% 7.43 Including C11+ aromatics weight% 0.58 Including 217℃+ weight% 0.43

[0161] C6+ fraction 5 is processed in hydrogenation unit C in the presence of a first hydrogenation catalyst C1 of the NiMo type, which can hydrogenate olefins, and a second hydrogenation catalyst C2 of the CoMo type on an alumina support, which can remove sulfur, nitrogen and oxygen compounds.

[0162] In hydrogenation unit C, the C6+ fraction 51 is contacted with hydrogen gas 2 in a reactor containing catalysts C1 and C2. This stage of the method specifically involves the hydrogenation of olefins and alkenyl aromatic compounds, as well as the conversion of sulfur and thiols present in the feedstock, and limits the hydrogenation of aromatics.

[0163] The operating conditions used in hydrogenation and hydrotreating reactors are:

[0164] -temperature:

[0165] Total pressure: 2.6 MPaa

[0166] -H2 / Raw material volume ratio: 150 standard m 3 hydrogen / m 3 Raw materials under standard conditions

[0167] -Liquid Time Space Velocity (LHSV):

[0168] In this embodiment, the effluent leaving the hydrogenation reactor is fed into the fractionation tower of hydrogenation unit C to remove H2S and light gases such as ethane, propane and butane.

[0169] The characteristics of the hydrogenated effluent 6 at the outlet of hydrogenation unit C are shown in Table 3.

[0170] Table 3

[0171] Alkanes weight% 32.3 Olefins weight% 0.0 Cycloalkanes weight% 10.8 Aromatics weight% 56.9 Including C6-C7 aromatics weight% 19.1 Including C8-C9 aromatics weight% 30.0 Including C10 aromatics weight% 7.22 Including C11+ aromatics weight% 0.58 Including 217℃+ weight% 0.42

[0172] Hydrogenated effluent 6 is then fed into the liquid-liquid extractor T1 of the aromatics extraction unit D. A solvent stream 9 containing 99.4 wt% sulfolane is added at the top, and a raffinate recirculation stream 15 is added at the bottom of the liquid-liquid extractor T1. The [solvent stream 9] / [hydrogenated effluent 6] weight ratio involved at the liquid-liquid extractor T1 is 5, and the [raffinate recirculation stream 15] / [hydrogenated effluent 6] weight ratio is 0.9. The liquid-liquid extractor T1 operates at a pressure of 0.5 to 0.8 MPa and a temperature of 54°C.

[0173] The raffinate 10 is extracted at the top of the liquid-liquid extractor T1 and then sent to an optional water scrubbing tower T2 to remove any trace amounts of sulfolane solvent entrained in the raffinate 10. The aqueous scrubbing liquid 18 consists primarily of water and sulfolane, and the non-aromatic feed stream 19 consists of the solvent-free raffinate.

[0174] For simplicity, the optional steam stripping and solvent regeneration sections are not presented. Figure 3 The optional water stripping and solvent regeneration sections allow for the treatment of the water stream used in the method according to the invention and the purification of sulfolane.

[0175] Extract 11 from liquid-liquid extractor T1 is fed to extract stripping section T3, which removes non-aromatic compounds containing solvent and aromatics, forming a raffinate recirculation stream 15 returned to liquid-liquid extractor T1. Gas stream 12 from the top of extract stripping section T3 is pre-sent to condenser CD3 to remove aqueous phase 14.

[0176] The stripping section T3 consists of a stripping tower operating at a bottom temperature of 180°C.

[0177] The purified extract 13 (which mainly contains solvent and aromatics) from the bottom of the stripping section T3 is sent to the aromatics recovery tower T6. The aromatics recovery tower T6 recovers the solvent that is recycled to the liquid-liquid extractor T1 as solvent stream 9 at the bottom, and recovers the overhead stream, which is sent to the condenser CD6. The condenser CD6 removes the water 16 and aromatics stream 17 separated by sedimentation. The aromatics recovery tower T6 operates by sending steam 8 to the bottom of the tower.

[0178] The aromatics recovery tower T6 operates at a bottom temperature of 180°C.

[0179] Table 4 shows the weight composition of the feed stream leaving aromatics extraction unit D.

[0180] Table 4

[0181] Alkanes weight% 62.9 0.0 Olefins weight% 0.0 0.0 Cycloalkanes weight% 21.1 0.0 Aromatics weight% 16.0 100.0 Including C6-C7 aromatics weight% 0.1 39.9 Including C8-C9 aromatics weight% 7.2 53.6 Including C10 aromatics weight% 7.9 6.4 Including C11+ aromatics weight% 0.8 0.1

[0182] Table 5 shows the weight distribution of the material flow entering and leaving the entire sequence using this method.

[0183] Table 5

[0184] Gasoline raw material 1 1 C5 fraction 4 0.25 Hydrogenated effluent 6 0.75 Non-aromatic feedstock 19 0.39 Aromatics feedstock 17 0.36

Claims

1. A method for processing and separating aromatic compounds from gasoline feedstock, comprising the following stages: - Selective hydrogenation of gasoline feedstock (1) to hydrogenate at least a diene contained in gasoline feedstock (1) in the presence of hydrogen (2) and produce selective hydrogenation effluent (3); - Fractionation of selectively hydrogenated effluent (3) to produce at least a C5- fraction (4) containing compounds having 5 or fewer carbon atoms and a C6+ fraction (5) containing compounds having at least 6 carbon atoms; - Fractionation of C6+ fraction (5) to produce a second C6+ fraction (52) and a C11+ fraction (51); - Hydrogenation of the second C6+ fraction (52) to hydrogenate at least the olefin contained in the second C6+ fraction (52) in the presence of hydrogen and produce hydrogenated effluent (6); - Extract aromatics from the hydrogenated effluent (6) to produce at least an aromatics stream (17) concentrated with respect to the aromatics compounds of the hydrogenated effluent (6), and a raffinate (10) concentrated with respect to the composition of the hydrogenated effluent (6) but not with the aromatics compounds. The aromatics extraction stage includes the following stages: - Aromatics are extracted from hydrogenated effluent (6) by means of a liquid-liquid extractor (T1) with a feed of solvent stream (9) to separate raffinate (10) and extract (11) which is concentrated with respect to the composition of hydrogenated effluent (6). - Extraction (11) is stripped using an extract stripping section (T3) to separate the gas stream (12) containing non-aromatic compounds and to purify the extract (13); - The gas stream (12) undergoes phase separation in the condenser (CD3) to separate the raffinate recirculation stream (15) and the aqueous phase (14); - The raffinate recirculation stream (15) is recirculated to the liquid-liquid extractor (T1), wherein the weight ratio of the raffinate recirculation stream (15) to the hydrogenated effluent (6) is 0.3 to 2. - Aromatics and solvent are separated from the purified extract (13) by means of an aromatic recovery tower (T6) to separate the solvent stream (9) and the overhead vapor containing the aromatic stream (17).

2. The method according to claim 1, wherein the gasoline feedstock (1) comprises a gasoline fraction obtained from a catalytic cracking unit.

3. The method according to claim 1 or claim 2, wherein the selective hydrogenation stage is carried out under at least one of the following operating conditions: the presence of at least one catalyst comprising a support and an active phase containing at least one Group VIII element, a temperature of 50 to 250°C, and 0.5 h. -1 Up to 20 h -1 Liquid hourly space velocity (LHSV), pressure from 0.4 to 5 MPa, and 2 to 100 Sm 3 / m 3 The volume ratio of H2 to gasoline feedstock.

4. The method according to any one of claims 1-2, wherein the fractionation stage is controlled to produce a C6+ fraction (5) having a content of less than or equal to 5000 ppm by weight of a compound with a boiling point greater than 217°C.

5. The method according to any one of claims 1-2, wherein the hydrogenation stage is carried out under at least one of the following operating conditions: the presence of at least one catalyst comprising a support and an active phase containing at least one Group VIII element, a temperature of 100 to 400°C, and 0.1 h. -1 Up to 20 h -1 Liquid hourly space velocity (LHSV), pressure from 0.1 to 5 MPaa, and pressure from 1 to 400 Sm 3 / m 3 The volume ratio of H2 to gasoline feedstock.

6. The method of claim 1, wherein the aromatic extraction stage further comprises at least one of the following stages: - The feed to the liquid-liquid extractor (T1) comprises a solvent stream (9) consisting of a solvent selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof; - The raffinate (10) is washed with water using a water scrubbing tower (T2) with water (7) as feed, to produce a non-aromatic feed stream (19) and an aqueous scrubbing liquid (18); - At least a portion of the solvent stream is regenerated by vacuum steam stripping in the solvent regeneration section (9); - The overhead vapor is condensed in a condenser (CD6) to produce an aromatic stream (17).

7. The method of claim 6, wherein the solvent stream (9) comprises sulfolane.

8. The method of claim 1, wherein the aromatic extraction stage further comprises at least one of the following stages: - The feed to the liquid-liquid extractor (T1) is a solvent stream selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof; - Water is produced by stripping hydrocarbon compounds present in the aqueous washing liquid (18) and / or the aqueous phase (14) using a water stripping section; - Feed steam (8) into the aromatics recovery tower (T6) to generate additional overhead steam containing steam, and condense the overhead steam in the condenser settling tank (CD6) to generate an aromatics stream (17) and water (16) separated by settling.

9. The method of claim 1, wherein the aromatic extraction stage further comprises at least one of the following stages: - Feed a solvent stream (9) containing sulfolane and water into the liquid-liquid extractor (T1); - The water produced in the water stripping section is recycled to the aromatics recovery tower (T6).

10. An apparatus for processing and separating aromatic compounds from gasoline feedstock, comprising the following units: - A selective hydrogenation unit for hydrogenating at least a diene contained in a gasoline feedstock (1) in the presence of hydrogen (2) and for generating a selective hydrogenation effluent (3); - A fractionation unit for fractionating the selectively hydrogenated effluent (3) and producing at least a C5- fraction (4) containing compounds having 5 or fewer carbon atoms and a C6+ fraction (5) containing compounds having at least 6 carbon atoms, and the fractionation unit includes a first fractionation column (B1) and a second fractionation column (B2), wherein the first fractionation column (B1) is used to separate the selectively hydrogenated effluent (3) into the C5- fraction (4) and the C6+ fraction (5), and the second fractionation column (B2) is used to separate the C6+ fraction (5) into a second C6+ fraction (52) and a C11+ fraction (51); - A hydrogenation unit for hydrogenating at least the olefin contained in the second C6+ fraction (52) in the presence of hydrogen and producing a hydrogenated effluent (6); - An aromatics extraction unit for extracting aromatics from the hydrogenated effluent (6) and producing at least an aromatics stream (17) concentrated with respect to the aromatics compounds in the hydrogenated effluent (6), and a raffinate (10) concentrated with respect to the composition of the hydrogenated effluent (6) but not with the aromatics compounds. The aromatics extraction unit includes the following components: - Liquid-liquid extractor (T1) is suitable for feeding a solvent stream (9) and a hydrogenated effluent (6), and is suitable for separating the raffinate (10) and the extract (11) which is concentrated with aromatics relative to the composition of the hydrogenated effluent (6). - Extract stripping section (T3), which is suitable for feeding extract (11) and for separating gas stream (12) containing non-aromatic compounds and purifying extract (13); - A condenser settling tank (CD3) is suitable for feeding a gaseous stream (12) and for separating the gaseous stream (12) to produce a raffinate recirculation stream (15) and an aqueous phase (14); - A liquid-liquid extractor (T1) suitable for feeding a recirculated feed stream of the raffinate (15); and - A recovery tower (T6) is suitable for feeding a purified extract (13) and for separating aromatics from the purified extract (13) to produce a solvent stream (9) and a tower top vapor containing an aromatic stream (17).

11. The apparatus of claim 10, wherein the aromatic extraction unit further comprises at least one of the following elements: - Liquid-liquid extractor (T1), which is suitable for feeding a solvent stream (9) containing a solvent selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof; - A water scrubbing tower (T2) is suitable for feeding water (7) and raffinate (10), and is suitable for washing the raffinate (10) with water to produce a non-aromatic stream (19) and an aqueous scrubbing liquid (18). - A solvent regeneration section, which is suitable for feeding at least a portion of the solvent stream (9) and is suitable for regenerating said portion of the solvent stream (9) by vacuum steam stripping; - A condenser (CD6) is suitable for feeding the overhead vapor and for condensing the overhead vapor to produce an aromatic stream (17).

12. The apparatus of claim 10, wherein the aromatic hydrocarbon extraction unit further comprises at least one of the following elements: - Liquid-liquid extractor (T1), which is suitable for feeding a solvent stream (9) containing a solvent selected from ethylene glycol, diethylene glycol, triethylene glycol, hexamethylphosphoramide, propylene carbonate, ethylene carbonate, sulfolane, 3-methylsulfolane, N-methylacetamide, N,N-dimethylacetamide, butyrolactone, 1-methylpyrrolidone, dimethyl sulfoxide, caprolactam, N-methylformamide, pyrrolidone-2-one, furfural, 1,1,3,3-tetramethylurea and mixtures thereof; - A water stripping section, which is suitable for feeding the aqueous washing liquid (18) and / or the aqueous phase (14), and is suitable for stripping hydrocarbon compounds from the aqueous washing liquid (18) and / or from the aqueous phase (14) to produce water; - An aromatics recovery tower (T6) suitable for feeding steam (8) and suitable for generating additional overhead steam containing steam, and a condenser settling tank (CD6) suitable for condensing the overhead steam to generate an aromatics stream (17) and water (16) separated by settling.

13. The apparatus of claim 10, wherein the aromatic hydrocarbon extraction unit further comprises at least one of the following elements: - Liquid-liquid extractor (T1), which is suitable for feeding a solvent stream containing sulfolane and water (9); - Aromatics recovery tower (T6), which is suitable for feed containing water produced by the water stripping section.

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