Device and method for converting aromatic compounds having 9 carbon atoms

Abstract

The present invention relates to a method and device for converting aromatic compounds, in which aromatic compounds from a hydrocarbonaceous feedstock (1), containing aromatic compounds having 9 carbon atoms, are isomerized in an isomerization unit (A) in the presence of a bifunctional isomerization catalyst having hydrogenation / dehydrogenation and hydroisomerization functions to produce an isomerized effluent (10) rich in trimethylbenzene. The present invention also relates to a method and device for producing aromatic compounds, including the method and device for converting aromatic compounds.

Description

[Technical field]

[0001] The present invention relates to the conversion of aromatic compounds in the context of producing aromatic compounds (benzene, toluene, para-xylene, ortho-xylene) for the petrochemical industry. The aromatic complex (aromatic compound production device) is fed with C6-C10+ feedstocks, from which alkyl aromatic compounds are extracted and then converted to the desired intermediates. The products of interest are aromatic compounds with 0, 1 or 2 methyls, with xylene having the highest market value. The present invention therefore relates to increasing the amount of available methyl groups in the aromatic complex by converting alkyl chains containing more than 2 carbons, in particular aromatic compounds containing 9 carbon atoms, i.e. the A9 fraction. [Background technology]

[0002] Prior art techniques for the conversion of A9 fractions are known, such as dealkylation (loss of two carbons) and hydrocracking (loss of one carbon atom).

[0003] Dealkylation is the intramolecular replacement of a hydrogen atom with an alkyl group.

[0004] Hydrodealkylation is a dealkylation reaction in which the removal of alkyl groups from aromatic molecules is carried out in the presence of hydrogen. Specifically, it is the cleavage of the ends of the alkyl chains "flush" with the nucleus. The catalysts can be of acid and metal type, the acid type being used especially on alkyl chains containing more than one carbon, but very inefficient for methyl, and the metal type especially when it is desired to convert methyl. The conversion of methyl is used especially to lower the gasoline cut point, for which all molecules must lose carbon, or to be used for the production of benzene, for which the reaction is maximally driven to keep only the aromatic nucleus.

[0005] Hydrogenolysis is a chemical reaction in which a carbon-carbon or carbon-heteroatom covalent bond is broken or undergoes decomposition by the action of hydrogen. Hydrodealkylation can therefore be considered as a reaction of hydrogenolysis of the carbon-carbon bond between an alkyl and an aromatic nucleus. On the other hand, hydrogenolysis also involves carbon-carbon bonds internal to alkyl groups containing more than one carbon.

[0006] For example, it may be mentioned that ethyltoluene can be converted to xylenes by hydrocracking (see US Pat. No. 5,399,633) or to toluene by dealkylation via the reaction mechanisms currently used in transalkylation units. Patent application US Pat. No. 5,399,633 relates, inter alia, to a selective hydrocracking unit processing a feedstock rich in aromatic compounds containing more than 8 carbon atoms, which consists in converting one or more alkyl groups (ethyl, propyl, butyl, isopropyl, etc.) containing at least two carbon atoms attached to the benzene nucleus into one or more methyl groups. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] French Patent Application Publication No. 3069244 Summary of the Invention [Means for solving the problem]

[0008] (Summary of the invention) In the above context, the first objective of the present description is to provide a process for producing aromatic compounds for the petrochemical industry that overcomes the problems of the prior art and allows for improved selectivity and yield of methyl compounds.

[0009] The present invention relates to the isomerization reaction (without carbon loss) of aromatic compounds containing 9 carbon atoms with alkyl chains containing 2 or 3 carbon atoms. It is therefore a matter of isomerizing the following five compounds: cumene, n-propylbenzene, o-methylethylbenzene, m-ethyltoluene and p-ethyltoluene to trimethylbenzene (TMB), increasing the amount of available methyl groups. Advantageously, by transalkylation with toluene, the net production of xylenes of the aromatic complex, especially p-xylene, can be increased.

[0010] According to a first aspect, the above mentioned objects, together with other advantages, are obtained by a method for converting aromatic compounds, said method comprising the following steps: - isomerizing aromatic compounds of a hydrocarbon feedstock, including aromatic compounds containing 9 carbon atoms (e.g., cumene, n-propylbenzene, o-ethyltoluene, m-ethyltoluene and p-ethyltoluene) in an isomerization unit in the presence of a bifunctional isomerization catalyst having a hydrogenation / dehydrogenation function and a hydroisomerization function to produce an isomerization effluent enriched in trimethylbenzenes.

[0011] According to one or more embodiments, the isomerization of aromatic compounds of a hydrocarbon feedstock is carried out under at least one of the following operating conditions: - a temperature between 250°C and 450°C, preferentially between 355°C and 390°C, for example a temperature of 385°C; - pressure 0.1 MPa absolute to 3 MPa absolute, preferentially 0.2 MPa absolute to 1.5 MPa absolute; - a molar ratio of H2 / HC between 1 and 5, preferentially between 3 and 4.5, for example a molar ratio of H2 / HC between 4; - WWH1h -1 ~30h -1 , preferentially 3 hours -1 ~12h -1 the term WWH corresponds to the weight of hydrocarbon feed injected per hour relative to the weight of catalyst fed.

[0012] According to one or more embodiments, the isomerization catalyst comprises at least one metal from Group VIIIB of the Periodic Table of the Elements as a hydrogenation / dehydrogenation functional group, at least one molecular sieve as a hydroisomerization functional group, and optionally at least one matrix.

[0013] According to one or more embodiments, the feedstock includes aromatic compounds containing 9 carbon atoms with alkyl chains containing 2 or 3 carbon atoms, such as cumene, n-propylbenzene, o-methylethylbenzene, m-ethyltoluene, and p-ethyltoluene.

[0014] According to one or more embodiments, the conversion method includes the steps of: - treating the isomerization effluent in a separation unit, which is located downstream, possibly directly downstream, of the isomerization unit; producing at least a first separated fraction and a fraction of unconverted compounds, the fraction of unconverted compounds being recycled to the inlet of the isomerization unit.

[0015] According to one or more embodiments, the conversion method includes the steps of: - treating the hydrocarbon feedstock in an extraction unit, which is located upstream, possibly directly upstream, of the isomerization unit; extracting trimethylbenzene and producing a trimethylbenzene-depleted hydrocarbon feedstock, which is sent to the isomerization unit.

[0016] According to a second aspect, the above mentioned objects, together with other advantages, are obtained by a process for the production of xylenes incorporating a conversion process according to the first aspect, comprising the following steps: sending all or a portion of the trimethylbenzene enriched isomerization effluent to an aromatics complex, preferably a transalkylation unit, to produce xylenes;

[0017] According to one or more embodiments, the method for converting aromatic compounds incorporates an aromatic complex according to at least one of the following configurations: - Pretreatment of hydrocarbon feedstocks upstream of the aromatic complex; - Treatment of at least one fraction internal to the aromatic complex.

[0018] According to one or more embodiments, a method for producing xylene includes the following steps: - passing a (e.g., essentially) aromatic effluent comprising compounds containing 9 to 10 carbon atoms (C9-C10) from the aromatic complex xylene column to an isomerization unit as a hydrocarbon feedstock.

[0019] According to a third aspect, the above mentioned objects, together with other advantages, are obtained by an aromatics conversion device comprising an isomerization unit suitable for isomerizing aromatics of a hydrocarbon feedstock comprising aromatics containing 9 carbon atoms (e.g. cumene, n-propylbenzene, o-ethyltoluene, m-ethyltoluene and p-ethyltoluene) in the presence of a bifunctional isomerization catalyst having hydrogenation / dehydrogenation and hydroisomerization functions to give an isomerized effluent enriched in trimethylbenzenes.

[0020] According to one or more embodiments, the isomerization catalyst comprises at least one metal from Group VIIIB of the Periodic Table of the Elements as a hydrogenation / dehydrogenation functional group, at least one molecular sieve as a hydroisomerization functional group, and optionally at least one matrix.

[0021] According to one or more embodiments, the conversion device includes: a separation unit located downstream, possibly directly, of the isomerization unit; said unit is suitable for treating the isomerization effluent to give at least a first separated fraction and a fraction of unconverted compounds, the latter being recycled to the inlet of the isomerization unit.

[0022] According to one or more embodiments, the conversion device includes: an extraction unit, which is located upstream, possibly directly, of the isomerization unit; suitable for extracting trimethylbenzene from the hydrocarbon feedstock for processing and resulting in a trimethylbenzene-depleted hydrocarbon feedstock, which is sent to the isomerization unit.

[0023] According to a fourth aspect, the above mentioned objects are obtained, together with other advantages, by a xylene production device incorporating a device for converting aromatic compounds according to the third aspect, including: a feed line; suitable for sending all or part of the isomerization effluent rich in trimethylbenzene to an aromatics complex, preferably a transalkylation unit, to produce xylenes.

[0024] According to one or more embodiments, the conversion device is incorporated into the aromatic complex according to at least one of the following configurations: - Pretreatment of hydrocarbon feedstocks (e.g. part of the input feedstock) upstream of the aromatic complex; - Treatment of at least one fraction internal to the aromatic complex.

[0025] According to one or more embodiments, the xylene production device includes: a feed line; suitable for conveying an (e.g. essentially) aromatic effluent comprising compounds containing 9 to 10 carbon atoms (C9-C10) from a xylene column of an aromatic complex as a hydrocarbon feed to an isomerization unit.

[0026] Other features and advantages of the embodiments according to the above-mentioned aspects and also of the devices and methods according to the above-mentioned aspects will become apparent from the following description, given by way of example only and without limitation, with reference to the following drawings, in which: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] (List of Drawings) FIG. 1 depicts an aromatics conversion device according to one or more embodiments of the present invention, including an isomerization unit, an optional trimethylbenzene extraction unit located directly upstream of the isomerization unit, and optional columns for separating products, by-products, reaction intermediates, and unconverted species.

[0028] FIG. 2 depicts an aromatics complex for the production of para-xylene, incorporating an aromatics conversion device according to one or more embodiments of the present invention.

[0029] (Description of the embodiment) In the petrochemical industry, paraxylene is one of the most commercially valuable intermediates. Its production requires methyl-substituted monoaromatic compounds; it is produced primarily by the disproportionation of toluene, the isomerization of xylenes, or the transalkylation of toluene with trimethylbenzene or tetramethylbenzene. To maximize the production of paraxylene, it is useful to maximize the amount of available methyl groups per aromatic nucleus.

[0030] With this goal in mind, methyl-substituted mono-aromatic compounds, preferably mono-aromatic compounds substituted only by methyl, can be directly upgraded, whereas this is not the case for mono-aromatic compounds with alkyl chains containing more than two carbon atoms (e.g., ethylbenzene, methylethylbenzenes (MEB), propylbenzene, etc.). It is therefore preferable to convert these mono-aromatic compounds to aromatic compounds substituted with methyl (e.g., only methyl). In this context, devices for converting aromatic compounds have been developed, including a unit for the isomerization of aromatic compounds containing nine carbon atoms, which allows to increase the amount of methyl groups on the aromatic nucleus and, inter alia, to increase the production of paraxylene. Advantageously, the isomerization unit allows, inter alia, the production of trimethylbenzene from propylbenzene and methylethylbenzene.

[0031] According to the first and third aspects and with reference to FIG. 1 , the present invention therefore relates to a method and a device for converting aromatic compounds, using / comprising an isomerization unit A suitable for isomerizing aromatic compounds (e.g. cumene, n-propylbenzene, o-ethyltoluene, m-ethyltoluene and p-ethyltoluene) of a hydrocarbon feedstock (1) comprising aromatic compounds containing 9 carbon atoms and for producing an isomerization effluent enriched in trimethylbenzenes.

[0032] (Hydrocarbon Feedstock) According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 95% by weight, preferably at least 98% by weight, highly preferably at least 99% by weight, of aromatic compounds relative to the total weight of said hydrocarbon feedstock (1). According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 93% by weight, preferably at least 95% by weight, highly preferably at least 98% by weight, of aromatic compounds containing at least 9 carbon atoms relative to the total weight of said hydrocarbon feedstock (1).

[0033] According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 50% by weight, preferably at least 60% by weight, preferentially at least 70% by weight, of aromatic molecules comprising at least one C2+ alkyl (e.g. ethyl, propyl) chain, relative to the total weight of the hydrocarbon feedstock (1).

[0034] According to one or more embodiments, the hydrocarbon feedstock (1) comprises or consists essentially of aromatic compounds containing 9 carbon atoms with alkyl chains containing 2 or 3 carbon atoms, such as cumene, n-propylbenzene, o-methylethylbenzene, m-ethyltoluene and p-ethyltoluene.

[0035] According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 93.5% by weight, preferably at least 95.5% by weight, highly preferably at least 98.5% by weight, relative to the total weight of said hydrocarbon feedstock (1), of aromatic molecules containing 9 to 10 carbon atoms. According to one or more embodiments, the hydrocarbon feedstock comprises at least one internal stream of an aromatic complex for the production of para-xylene and / or the isomerization effluent (10) is a feedstock that is at least partially sent to an aromatic complex for the production of para-xylene.

[0036] According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 93% by weight, preferably at least 95% by weight, highly preferably at least 98% by weight, of aromatic molecules containing 9 carbon atoms, relative to the total weight of said hydrocarbon feedstock (1). According to one or more embodiments, the hydrocarbon feedstock (1) comprises methylethylbenzene and / or propylbenzene and optionally trimethylbenzene, preferably little or no trimethylbenzene (e.g. less than 1% by weight, preferably less than 0.5% by weight, highly preferably less than 0.2% by weight).

[0037] According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 0.1% by weight, preferably at least 0.2% by weight, highly preferably at least 0.5% by weight, of aromatic molecules containing 10 carbon atoms, relative to the total weight of said hydrocarbon feedstock (1). According to one or more embodiments, the hydrocarbon feedstock (1) comprises dimethylethylbenzene and / or methylpropylbenzene, and optionally tetramethylbenzene and / or butylbenzene.

[0038] According to one or more embodiments, the hydrocarbon feedstock (1) comprises at least 93 wt.%, preferably at least 95 wt.%, highly preferably at least 98 wt.% of aromatic compounds selected from methylethylbenzene, propylbenzene, optionally trimethylbenzene, dimethylethylbenzene, methylpropylbenzene, and optionally tetramethylbenzene and / or butylbenzene.

[0039] (Isomerization unit) With reference to FIG. 1, the isomerization unit A is suitable for the following applications: - treating a hydrocarbon feedstock (1) containing aromatic compounds containing 9 carbon atoms with a feed hydrogen (2) in the presence of a catalyst to convert at least a portion of the hydrocarbon feedstock (1) into trimethylbenzene; and producing a conversion effluent (5) rich in trimethylbenzene.

[0040] According to one or more embodiments, the isomerization unit A comprises at least one isomerization reactor C suitable for use under the following operating conditions: - temperature: between 250°C and 450°C, preferentially between 355°C and 390°C, for example at a temperature of 385°C, and / or - pressure: 0.1 MPa absolute to 3 MPa absolute, preferentially 0.2 MPa absolute to 1.5 MPa absolute, and / or a molar ratio of H2 / HC between 1 and 5, preferentially between 3 and 4.5, for example a molar ratio of H2 / HC between 4, and / or - WWH:1h -1 ~30h-1 , preferentially 3 hours -1 ~12h -1 .

[0041] The term "WWH" corresponds to the mass of hydrocarbon feedstock injected per hour relative to the mass of catalyst fed.

[0042] According to one or more embodiments, the isomerization reactor C is a fixed bed or moving bed reactor. A moving bed may be defined as being a gravity flow bed, such as those found in catalytic reforming of gasoline. According to one or more embodiments, the isomerization reactor C is a fixed bed reactor.

[0043] According to one or more embodiments, the hydrocarbon feedstock (1) is mixed with a feed of hydrogen (2) in the isomerization reactor C and / or upstream (e.g., directly upstream) of the isomerization reactor C to form a hydrogen-rich hydrocarbon feedstock (3).

[0044] According to one or more embodiments, the isomerization unit A also comprises a heating unit B for heating the hydrocarbon feedstock (1) or the hydrogen-rich hydrocarbon feedstock (3) upstream (e.g. directly upstream) of the isomerization reactor C. A conversion effluent heat recovery facility (5) may be placed before the heating unit B, which is used to preheat the hydrocarbon feedstock (1) or the hydrogen-rich hydrocarbon feedstock (3). According to one or more embodiments, the heating unit B is suitable for use under the following operating conditions: inlet temperature 150° C. to 200° C.; and / or outlet temperature 355° C. to 390° C. (e.g. 385° C.). The heated effluent (4) from the heating unit B is sent (e.g. directly) to the isomerization reactor C.

[0045] According to one or more embodiments, the conversion effluent (5) is sent (e.g. directly) to a cooling unit D (e.g. a heat exchanger) to form a cooled conversion effluent (6). The cooling unit D may be preceded by a conversion effluent heat recovery facility (5) used to preheat the hydrocarbon feedstock (1) or the hydrogen-enriched hydrocarbon feedstock (3). According to one or more embodiments, the cooling unit D is suitable for use under the following operating conditions: inlet temperature 355°C to 390°C (e.g. 385°C); and / or outlet temperature 45°C to 60°C.

[0046] According to one or more embodiments, the cooled conversion effluent (6) is sent (e.g., directly) to a separation section E to produce a hydrogen-containing gaseous effluent (7) and an isomerization effluent (10).

[0047] According to one or more embodiments, the gaseous effluent (7) is sent to a recycle unit F suitable for: compressing and / or purifying the gaseous effluent (7); optionally extracting a purge gas (9) (e.g., methane) from the gaseous effluent (7); and / or mixing the gaseous effluent (7) with feed hydrogen (2) to form a hydrogen mixture (8); the hydrogen mixture (8) is sent to an isomerization reactor C and / or mixed (e.g., directly) with the hydrocarbon feedstock (1) to form a hydrogen-enriched hydrocarbon feedstock (3).

[0048] (Separate unit) Referring to FIG. 1 , according to one or more embodiments, the aromatics conversion device also optionally includes an optional separation unit G located downstream (e.g., directly downstream) of the isomerization unit A for treating the isomerized effluent (10) to produce at least one separated fraction, e.g., a first separated fraction (11) and a second separated fraction (12), and optionally, an unconverted compound fraction (13), which can be recycled to the inlet of the isomerization unit A.

[0049] According to one or more embodiments, the first separated fraction (11) is a hydrocarbon fraction containing compounds containing up to 8 carbon atoms (C8-); the second separated fraction (12) is an aromatic fraction containing trimethylbenzene; and the unconverted compound fraction (13) is an aromatic fraction containing methylethylbenzene and propylbenzene.

[0050] (Extraction unit) To improve the performance of the isomerization unit A, one or more embodiments propose to add an extraction (or depletion) unit H upstream (e.g. directly upstream) of the isomerization unit A to extract trimethylbenzenes and therefore reduce the content of compounds substituted (only) with methyl. These compounds do not need to be isomerized before transalkylation and therefore do not need to be processed by the isomerization unit A. In this way, the feedstock of the isomerization unit is depleted of trimethylbenzenes, allowing the isomerization unit A to mainly process aromatic compounds with at least one alkyl chain containing two or more carbons. Thus, losses in the isomerization unit A are reduced, resulting in a gain in the selectivity of the unit.

[0051] With reference to FIG. 1, the conversion device comprises an extraction unit H suitable for: - treating a hydrocarbon feedstock (1) to extract trimethylbenzene; and - producing a trimethylbenzene-enriched effluent (14) and a trimethylbenzene-depleted hydrocarbon feedstock (15), which is sent to the isomerization unit A instead of the hydrocarbon feedstock (1).

[0052] According to one or more embodiments, the trimethylbenzene-enriched effluent (14) comprises at least 50% by weight, preferably at least 60% by weight, highly preferably at least 70% by weight, of trimethylbenzene relative to the total weight of said effluent.

[0053] According to one or more embodiments, the extraction unit H comprises at least one distillation column, and / or a molecular sieve simulated moving bed, and / or a molecular sieve adsorption unit that can be regenerated under temperature and / or pressure differentials, and / or a crystallization unit, and / or a liquid / liquid extraction unit, and / or an extractive distillation unit, and / or a membrane separation unit.

[0054] According to one or more embodiments, the extraction unit H comprises at least one of the following distillation columns: - a first extraction column; suitable for recovering methylethylbenzenes and / or propylbenzenes at the top of the column and trimethylbenzenes at the bottom of the column.

[0055] According to one or more embodiments, the column of extraction unit H is suitable for use under at least one of the following operating conditions: - the pressure in the reflux vessel is substantially 0.001 to 0.1 MPag, for example substantially 0.01 MPag, and the temperature is substantially 140°C to 180°C, for example substantially 163°C; the column has substantially 50-150 theoretical plates, for example substantially 100 theoretical plates, the mass ratio of the reflux and feed rates is 1-10, preferably 4-6, the temperature at the top of the column is 150°C-190°C, preferably 160°C-175°C, and the temperature at the bottom of the column is substantially 180°C-220°C, for example substantially 203°C.

[0056] According to one or more embodiments, for example when an extraction unit H is used in combination with a separation unit G, the first separation cut (11) is a head fraction cut comprising compounds containing up to 8 carbon atoms (C8-); the second separation cut (12) is an optional purge cut (e.g., fuel gas); the unconverted compounds cut (13) is a bottom fraction cut comprising trimethylbenzene, methylethylbenzene and propylbenzene, which is sent to the extraction unit H.

[0057] (Isomerization catalyst) According to the invention, the isomerization reactor C is operated in the presence of a bifunctional isomerization catalyst, i.e. a hydroisomerization catalyst having a hydrogenation / dehydrogenation functional group or element and a hydroisomerization functional group or element.

[0058] In this patent application, the term "hydrogenation / dehydrogenation" refers to the promotion of a hydrogenation / dehydrogenation reaction that includes / consists of the incorporation / removal of a hydrogen atom in a molecule. In this patent application, the term "hydroisomerization" refers to the promotion of a hydroisomerization reaction that includes / consists of the conversion of a molecule into an isomer in the presence of hydrogen.

[0059] According to the present invention, the hydrogenation / dehydrogenation and hydroisomerization catalyst comprises at least one metal from group VIIIB of the Periodic Table of the Elements as a hydrogenation / dehydrogenation functional group or element and at least one molecular sieve as a hydroisomerization functional group or element. According to one or more embodiments, the isomerization catalyst also comprises at least one matrix.

[0060] In this patent application, the groups of chemical elements are by convention given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor in chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to metals in rows 8, 9 and 10 according to the new IUPAC classification. Groups VIIIB, IVA and VIIB according to the CAS classification correspond to metals in rows 13, 14 and 7, respectively, according to the new IUPAC classification.

[0061] (hydroisomerization element) According to one or more embodiments, the at least one molecular sieve comprises at least one zeolite molecular sieve. According to one or more embodiments, the catalyst comprises at least one one-dimensional 10MR or 12MR zeolite molecular sieve. The one-dimensional 10MR or 12MR zeolite molecular sieve has pores or channels whose openings are defined by rings containing 10 oxygen atoms (10MR openings) or rings containing 12 oxygen atoms (12MR openings). The channels of the zeolite molecular sieve with 10MR or 12MR openings advantageously comprise non-interconnected one-dimensional channels that open directly to the exterior of the zeolite. According to one or more embodiments, the one-dimensional 10MR or 12MR zeolite molecular sieve present in the hydroisomerization catalyst comprises silicon and at least one element T selected from the group consisting of aluminum, iron, gallium, phosphorus and boron. Preferably, element T comprises or consists of aluminium.

[0062] According to one or more embodiments, the one-dimensional 10MR zeolite molecular sieve of the hydroisomerization catalyst is advantageously of the framework type TON (e.g., selected from ZSM-22 and NU-10, used alone or in a mixture), FER (e.g., selected from ZSM-35 and ferrierite, used alone or in a mixture), EUO (e.g., selected from EU-1 and ZSM-50, used alone or in a mixture), AEL (e.g., SAPO-11) or *The 12MR zeolite molecular sieve of the hydroisomerization catalyst is selected from zeolite molecular sieves of the framework type MTW (e.g., selected from ZSM-48, ZBM-30, EU-2 and EU-11, used alone or as a mixture). According to one or more embodiments, the 12MR zeolite molecular sieve of the hydroisomerization catalyst is selected from zeolite molecular sieves of the framework type MTW (e.g., selected from ZSM-12, TPZ-12, Theta-3, NU-13, CZH-5, used alone or as a mixture) and MОR (e.g., selected from mordenite or LZ-211, used alone or as a mixture). The framework code is defined in the International Zeolite Association classification (IZA: http: / / www.iza-structure.org / databases / ).

[0063] According to one or more embodiments, the catalyst comprises IZM-2 zeolite, which is a crystalline microporous solid having a crystal structure described in patent application FR 2 918 050 A1. The X-ray diffraction pattern of IZM-2 zeolite contains at least the lines listed in Table 1, which shows the average d hkl The values ​​in Table 1 represent the relative intensity and the relative strength. In Table 1, VS = very strong; S = strong; m = moderate; mw = moderately weak; w = weak; vw = very weak. rel is given as a relative intensity scale where a value of 100 is given to the most intense line in the X-ray diffraction diagram: vw<15; 15≦w<30; 30≦mw<50; 50≦m<65; 65≦S<85; VS≦85.

[0064] [Table 1]

[0065] The diffraction diagram is obtained by radiation crystallographic analysis with a diffractometer using conventional powder techniques with copper Kα1 radiation (λ=1.5406 Å). Based on the positions of the diffraction peaks expressed by the angle 2θ, the lattice parameter distances d hklis calculated using the Bragg relation. d hkl Measurement error Δ(d hkl ) is calculated by Bragg's law as a function of the absolute error Δ(2θ) assigned to the measurement of 2θ. An absolute error Δ(2θ) equal to ±0.02° is generally accepted. hkl The relative intensity I assigned to each value of rel are measured according to the height of the corresponding diffraction peak. The X-ray diffraction diagram of the IZM-2 crystalline solid according to the invention is given in Table 1. hkl Contains at least a line with a value of d hkl In the value column, the average lattice spacing is given in angstroms (Å). Each of these values ​​has a measurement error Δ(d hkl ) must be assigned to

[0066] IZM-2 zeolite has a chemical composition expressed in terms of moles of oxide on an anhydrous basis and has the following general formula: XО2:aYО3:bM 2 / n X is defined as YO and Y is defined as YO, where X represents at least one tetravalent element, Y represents at least one trivalent element, M represents at least one alkali metal and / or alkaline earth metal of valence n, and a and b are YO and M, respectively. 2 / n represents the number of moles of O, a is 0 to 0.5, and b is 0 to 1.

[0067] According to one or more embodiments, X is preferentially selected from silicon, germanium, titanium, and mixtures of at least two of these tetravalent elements. According to one or more embodiments, Y is selected from aluminum, boron, iron, indium and gallium; preferentially, Y is aluminum.

[0068] According to one or more embodiments, IZM-2 zeolite has the following general formula, in terms of moles of oxide, on an anhydrous basis: SiO2:aAl2O3:bM 2 / nIn the formula given above, a represents the number of moles of Al2O3, b represents the number of moles of M 2 / n represents the number of moles of O, a is 0 to 0.5, and b is 0 to 1.

[0069] According to one or more embodiments, M is chosen from lithium, sodium, potassium, calcium, magnesium and mixtures of at least two of these metals; preferentially, M is sodium.

[0070] The Si / Al ratio of the zeolite is advantageously that obtained during synthesis or after a post-synthesis dealumination treatment known to the person skilled in the art, for example, but non-exhaustively, a hydrothermal treatment followed, optionally, by acid attack with a mineral or organic acid solution or else directly. The zeolite is preferably essentially in the acid form, i.e. the atomic ratio between the monovalent compensation cation (for example sodium) inserted in the crystal lattice of the solid and the aluminum is advantageously less than 0.1, preferably less than 0.05, highly preferably less than 0.01. According to one or more embodiments, the zeolite comprised in the composition of the hydroisomerization catalyst is advantageously calcined. According to one or more embodiments, the zeolite is exchanged by at least one treatment with a solution of at least one ammonium salt to obtain the ammonium form of the zeolite, which, once calcined, leads to the acid form of the zeolite.

[0071] According to one or more embodiments, the molecular sieve content in the hydroisomerization catalyst is between 1% and 90% by weight, preferably between 3% and 80% by weight and more preferentially between 4% and 60% by weight, relative to the total weight of the hydroisomerization catalyst.

[0072] (Matrix) According to one or more embodiments, the matrix is ​​amorphous or crystalline. According to one or more embodiments, the matrix is ​​advantageously selected from the group formed by alumina, silica, silica-alumina, clay, titanium oxide, boron oxide, zirconia and aluminates, used alone or in mixtures. Preferably, alumina is used as matrix. Preferably, said matrix may contain alumina in all its forms known to the skilled person, such as alpha, gamma, eta and delta type alumina.

[0073] According to one or more embodiments, the content of the matrix, e.g. alumina, in the hydroisomerization catalyst is between 10% and 99% by weight relative to the total weight of the hydroisomerization catalyst, i.e. providing a remainder up to 100% by weight of the elements constituting the hydroisomerization catalyst.

[0074] The catalyst support comprises a molecular sieve, optionally in a mixture with a matrix. The shaping of the support in the form of a mixture is preferably carried out by co-mixing the molecular sieve with a matrix or a precursor of the matrix, for example boehmite, which is converted to alumina by heat treatment, extruding and then heat treating.

[0075] (Hydrogenation / Dehydrogenation Elements) According to one or more embodiments, the at least one Group VIIIB metal is selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. Preferably, the at least one Group VIIIB metal is selected from the Group VIIIB noble metals; highly preferably, the at least one Group VIIIB metal is selected from palladium and platinum, and even more preferably, the at least one Group VIIIB metal is platinum.

[0076] According to one or more embodiments, the dispersion of the at least one group VIIIB metal (percentage of atoms of said metal exposed on the surface), determined by chemisorption, e.g. H2 / O2 titration or carbon monoxide chemisorption, is between 10% and 100%, preferably between 20% and 100%, more preferably between 30% and 100%. The macroscopic distribution coefficient of the at least one group VIIIB metal, obtained from its profile determined by Castaing microprobe and defined as the ratio of the concentration of the group VIIIB metal in the core of a granule (catalyst extrudate) relative to the concentration at the edge of this same granule (catalyst extrudate), is between 0.7 and 1.3, preferably between 0.8 and 1.2. The value of this ratio, in the region of 1, is evidence of the uniformity of the distribution of the at least one group VIIIB metal in the hydroisomerization catalyst.

[0077] According to one or more embodiments, the hydroisomerization catalyst also comprises at least one additional metal, which is selected from the group formed by the metals of groups IIIA, IVA and VIIB of the Periodic Table of the Elements, and is preferably selected from gallium, indium, tin and rhenium. The additional metal is preferably selected from indium, tin and rhenium.

[0078] Advantageously, the hydrogenation / dehydrogenation elements (metals) may be introduced onto the catalyst support by any method known to those skilled in the art, such as co-mulling, dry impregnation or impregnation by exchange.

[0079] According to one or more embodiments, the content of Group VIIIB metal, such as platinum, in the hydroisomerization catalyst is between 0.01% and 4% by weight, preferably between 0.05% and 2% by weight, relative to the total weight of the hydroisomerization catalyst.

[0080] According to one or more embodiments, the content of the at least one additional metal in the hydroisomerization catalyst is between 0.01% and 2% by weight, preferably between 0.05% and 1% by weight, relative to the total weight of the hydroisomerization catalyst.

[0081] According to one or more embodiments, the sulfur content in the hydroisomerization catalyst is such that the ratio of moles of sulfur to moles of at least one Group VIIIB metal is between 0.3 and 3. According to one or more embodiments, the presence of sulfur in the catalyst results from an optional sulfiding step of the hydroisomerization catalyst. According to one or more embodiments, the presence of sulfur in the catalyst results from impurities that may be present, for example, in the alumina binder.

[0082] According to one or more embodiments, the hydroisomerization catalyst used in the process according to the invention more particularly comprises, and preferably consists of: - molecular sieves; from 1% to 90% by weight, preferably from 3% to 80% by weight, even more preferably from 4% to 60% by weight; - at least one metal of group VIIIB, preferably platinum; from 0.01% to 4% by weight, preferably from 0.05% to 2% by weight; - optionally at least one additional metal selected from the group formed by the metals of groups IIIA, IVA and VIIB; from 0.01% to 2% by weight, preferably from 0.05% to 1% by weight; - optionally, sulfur; its content is preferably such that the ratio of moles of sulfur to moles of metal of group VIIIB is between 0.3 and 3; - optional at least one matrix, preferably alumina; providing a remainder up to 100% in the catalyst, relative to the total weight of the hydroisomerization catalyst.

[0083] According to one or more embodiments, the hydroisomerization catalyst is formed into cylindrical or multilobal extrudates, for example straight or twisted bilobal, trilobal or multilobal extrudates. According to one or more embodiments, the hydroisomerization catalyst is formed into crushed powder, tablets, rings, beads or wheels. Techniques other than extrusion, such as pelletizing or dredging, may advantageously be used.

[0084] In the case where the hydroisomerization catalyst contains at least one precious metal, the precious metal contained in said hydroisomerization catalyst may advantageously be reduced. One suitable method for carrying out the metal reduction is to reduce the precious metal under hydrogen (e.g., 0.4 to 40 normal m 3 / h / catalyst m 3 (Nm 3 / h / m 3 ), preferably 1 to 16 Nm 3 / h / m 3 , for example, substantially 4Nm 3 / h / m 3 ), at a temperature of 150°C to 650°C and a total pressure of 0.1 to 25 MPa. For example, the reduction may include a stationary phase at 150°C for 2 hours, followed by a temperature increase to 450°C at a rate of 1°C / min, followed by a stationary phase at 450°C for 2 hours; during the reduction step, the hydrogen flow rate is 3 ) per 1000 normal m 3 and the total pressure may be kept constant at 0.1 MPa. Any ex-situ reduction method may advantageously be envisaged.

[0085] (Aromatic Complex) According to the second and fourth aspects, the conversion method and device are integrated into a method and / or device for the production of xylenes using an aromatic complex, for example an aromatic complex. The conversion method / device then exchanges the stream with the aromatic complex. According to one or more embodiments, the aromatic complex is fed with a hydrocarbon fraction essentially containing molecules with carbon numbers ranging from 6 to 10.

[0086] According to one or more embodiments, the following configurations of the conversion device incorporated into the aromatic complex are envisaged: - the conversion device is used as a pretreatment unit upstream of the aromatic complex. In this case, external streams can be fed directly to the conversion device (e.g. 6-10 carbon reformate, A9 / A10 fraction, etc.) and the effluent from the conversion device is then sent to the aromatic complex; - one or more conversion devices are used to process one or more fractions internal to the aromatic complex. In this case, the conversion device can be partially or totally fed with one or more streams coming from the aromatic complex units (e.g. fractionation / distillation, simulated moving bed). The effluent from the conversion device is then returned to the aromatic complex; - A combination of the two configurations defined above is also possible and falls within the context of the present invention. In all cases, the effluent is then enriched in aromatic compounds containing methyl groups, which are sent in whole or in part to an aromatics complex to produce xylenes and optionally benzene. Overall, the integration of the conversion device into the aromatics complex increases the production of para-xylene, as will be shown in the embodiment of FIG. 2 described below.

[0087] According to one or more embodiments, the conversion device is suitable for treating a stream containing aromatic compounds containing 9 and optionally 10 carbon atoms internal to the aromatic complex. For example, Figure 2 shows a conversion device incorporated into an aromatic complex for treating a stream containing aromatic compounds containing 9 and 10 carbon atoms obtained from a fractionation train of the aromatic complex.

[0088] Referring to FIG. 2, according to one or more embodiments, the aromatic complex includes: - optionally, a feedstock separation unit I for separating the feedstock entering the aromatic complex into a hydrocarbon fraction containing up to 7 carbon atoms (C7-) and an aromatic fraction containing 8 or more carbon atoms (A8+); - optionally, a unit J for extraction of aromatic compounds between the feedstock separation unit I and the fractionation train KN; separating aliphatics from benzene and toluene of the C7-fraction of the complex feedstock; - fractionation train KN; making it possible to extract xylenes from other aromatic compounds; - a transalkylation unit O; converting toluene and methyl alkylbenzenes, such as trimethylbenzene, into xylenes; advantageously, this unit can also process tetramethylbenzene and, to a certain extent, benzene; - a xylene separation unit P (for example a crystallization unit or a simulated moving bed separation unit using molecular sieves and a desorbent) or a unit of the type capable of isolating para-xylene from xylene and ethylbenzene; - optionally, a unit Q for isomerizing the raffinate obtained as effluent from the xylene separation unit P, in particular converting ortho-xylene, meta-xylene and ethylbenzene to para-xylene; and a conversion device according to the invention; comprising an isomerization unit A, a separation unit G and an extraction unit H, suitable for treating a hydrocarbon feedstock (1) arising at the bottom of a xylene column M of an aromatic complex, and for producing an isomerization effluent (10).

[0089] According to one or more embodiments, the feedstock separation unit I processes the feedstock (16) entering the aromatic complex and separates a head fraction (17) (e.g., essentially) containing compounds containing 7 or less carbon atoms (C7-) and a bottom fraction (18) (e.g., essentially) containing aromatic compounds containing 8 or more carbon atoms (A8+). The bottom fraction (18) is sent to the xylene column M. Optionally, the feedstock separation unit I can also separate a light compounds fraction (19) (compounds containing 5 or less carbon atoms).

[0090] According to one or more embodiments, the input feedstock (16) is a hydrocarbon fraction containing mainly molecules with carbon numbers ranging from 6 to 10 carbon atoms. This feedstock may also contain molecules containing more than 10 carbon atoms and / or molecules containing 5 carbon atoms. The feedstock (16) entering the aromatic complex is rich in aromatic compounds and contains a minimum of 50% by weight, preferentially more than 70% by weight, of alkyl aromatic compounds. The input feedstock (16) can be produced by catalytic reforming of naphtha or can be the product of a cracking (e.g. steam cracking, catalytic cracking) unit or any other means for the production of alkyl aromatic compounds.

[0091] The head fraction cut (17) from the feed separation unit I is optionally mixed with the bottom product (20) (benzene and toluene) from the stabilization column R and sent to the aromatics extraction unit J to extract an effluent (21) containing C6-C7 aliphatic species, which is sent as an aromatics complex by-product. The aromatics cut (22) (essentially benzene and toluene), called the extract from the aromatics extraction unit J, is optionally mixed with the heavy fraction (23) from the (first) separation column S of the transalkylation unit O and sent to the (first) aromatics distillation column K of the fractionation train KN.

[0092] According to one or more embodiments, the fractionation train comprises columns K, L, M and N for the distillation of aromatic compounds, making it possible to separate the following five fractions: - fraction (24); containing compounds which are (for example essentially) aromatic and contain 6 carbon atoms (for example benzene); - fraction (25); containing compounds that are (for example essentially) aromatic and contain 7 carbon atoms (for example toluene); - fraction (26); containing compounds (for example essentially) aromatic containing 8 carbon atoms (for example xylenes and ethylbenzene); - fraction (27); containing compounds that are (for example essentially) monoaromatic and contain 9 and 10 carbon atoms; and - fraction (28); containing compounds that are (for example essentially) aromatic, the most volatile species of which are those containing 10 carbon atoms.

[0093] The first column K for distilling aromatic compounds, also called benzene column, is suitable for treating a C6-C10 (e.g. essentially) aromatic compounds (A6+) hydrocarbon feedstock (22), producing at the top a fraction (24) (benzene fraction) which is one of the desired products leaving the aromatic complex, and at the bottom a C7-C10 (e.g. essentially) aromatic compounds (A7+) effluent (29). According to one or more embodiments, the C6-C10 (e.g. essentially) aromatic compounds (A6+) hydrocarbon feedstock (22) is a C6-C7 (e.g. essentially) aromatic compounds (A6-A7) hydrocarbon feedstock.

[0094] The second column L for distilling aromatics, also called toluene column, is suitable for treating an (A7+) effluent (29) from the bottom of the benzene column; for producing at the top a fraction (25) (toluene fraction) which is sent to the transalkylation unit O; and for producing at the bottom a C8-C10 (for example essentially) aromatic (A8+) effluent (30).

[0095] The third column M for distilling aromatics, also called xylene column, is suitable for treating the effluent (30) from the bottom of the toluene column and, optionally, the aromatic fraction (18) (A8+) containing 8 or more carbon atoms of the aromatic complex feedstock; at the top, it produces a fraction (26) (a fraction of xylenes and ethylbenzene) which is sent to the xylene separation unit P; and at the bottom, it produces a C9-C10 (for example essentially) aromatic (A9+) effluent (31) as the hydrocarbon feedstock (1) for the conversion device according to the invention.

[0096] The fourth aromatics distillation column N, also known as the heavy aromatics column, is suitable for treating the trimethylbenzene-rich effluent (14) from the extraction unit H; for producing, at the top, a fraction (27) comprising (e.g. essentially) monoaromatic compounds containing 9 and 10 carbon atoms which is directed to the transalkylation unit O; and, at the bottom, a fraction (28) comprising (e.g. essentially) aromatic compounds, the most volatile species of which are aromatic compounds containing 10 carbon atoms (A10+).

[0097] In the transalkylation unit O, a fraction (27) containing (e.g., essentially) monoaromatic compounds containing 9 and 10 carbon atoms is mixed with a fraction (25) containing toluene coming from the top of the toluene column L and transalkylated with aromatic compounds without multiple methyl groups (toluene) and aromatic compounds with excess methyl groups (e.g., trimethylbenzene and tetramethylbenzene) to produce xylenes, which are fed to the first separation column S. According to one or more embodiments, the transalkylation unit O is fed with benzene (line not shown in FIG. 2 ) in cases where excess methyl groups are observed, for example, for the production of paraxylene.

[0098] According to one or more embodiments, the transalkylation unit O includes at least a first transalkylation reactor suitable for use under at least one of the following operating conditions: - Temperature: 200℃~600℃, preferentially 350℃~550℃, more preferentially 380℃~500℃; - Pressure: 2-10MPa, preferentially 2-6MPa, more preferentially 2-4MPa; - WWH: 0.5~5h -1 , preferentially 1~4 hours -1 , more preferentially 2-3 hours -1 .

[0099] According to one or more embodiments, the first transalkylation reactor is operated in the presence of a catalyst comprising a zeolite, such as ZSM-12 and / or ZSM-5. According to one or more embodiments, the second transalkylation reactor is of the fixed bed type.

[0100] According to one or more embodiments, the transalkylation unit O includes at least a second transalkylation reactor suitable for use under at least one of the following operating conditions: - Temperature: 200℃~400℃, preferentially 220℃~350℃, more preferentially 250℃~310℃; - Pressure: 1-6MPa, preferentially 2-5MPa, more preferentially 3-5MPa; - WWH: 0.5~5h -1 , preferentially 0.5 to 4 hours -1 , more preferentially 0.5 to 3 hours -1 .

[0101] According to one or more embodiments, the second transalkylation reactor is operated in the presence of a catalyst comprising a zeolite, such as a dealuminated zeolite Y (e.g., a zeolite similar to those described in the alkylation catalyst section). According to one or more embodiments, the second transalkylation reactor is of the fixed bed type.

[0102] According to one or more embodiments, the transalkylation effluent (32) from the reaction section of the transalkylation unit O is separated in a first separation column S. A fraction (33) containing at least a portion of the benzene and more volatile species (C6-) is extracted at the top of the first separation column and sent to an optional stabilization column R. A heavy fraction (23) of the effluent from the first separation column S containing compounds that are (e.g., essentially) aromatic containing at least 7 carbon atoms (A7+) is optionally recycled to a fractionation train KN, e.g., a benzene column K.

[0103] The fraction (26) containing (e.g. essentially) aromatic compounds containing 8 carbon atoms (e.g. xylene and ethylbenzene) is treated in a xylene separation unit P. Para-xylene (34) is output as the main product. The raffinate (35) from the xylene separation unit P containing (e.g. essentially) ortho-xylene, meta-xylene and ethylbenzene is fed to an isomerization unit Q.

[0104] In the isomerization reaction section (not shown) of the isomerization unit Q, the para-xylene isomer can be isomerized, while the ethylbenzene is dealkylated to give benzene in the presence of hydrogen (e.g. fed with a hydrogen source (36)). In this example, the isomerization reaction section is of the dealkylation type. According to one or more embodiments, at least one isomerization reaction section of the isomerization unit is of the isomerization type, or ethylbenzene is isomerized to xylenes. According to one or more embodiments, the isomerized effluent (37) from the isomerization reaction section is sent to a second separation column T to give, at the bottom, a para-xylene-enriched isomerate (38), which is optionally recycled to the xylene column M; and, at the top, a hydrocarbon fraction (39) containing compounds containing 7 or less carbon atoms (C7-), which is sent to a stabilization column R, for example together with a fraction (33) containing at least a portion of the benzene and more volatile species.

[0105] According to one or more embodiments, at least one isomerization reaction section is in the gas phase and suitable for use in the presence of a catalyst under at least one of the following operating conditions: - temperature: above 300°C, preferably between 350°C and 480°C; - Pressure: less than 4.0MPa, preferably 0.5-2.0MPa; - Hourly space velocity: 10h -1 (less than 10 liters per hour of volume (liters)), preferably 0.5h -1 ~6h -1 ; - hydrogen to hydrocarbon molar ratio: less than 10, preferably 3-6; the catalyst comprises at least one zeolite whose pore openings are defined by rings containing 10 or 12 oxygen atoms (10MR or 12MR) and at least one group VIIIB metal in a content between 0.1% and 0.3% by weight (reduced form) (both limits included);

[0106] According to one or more embodiments, at least one isomerization reaction section is in the liquid phase and is suitable for use in the presence of a catalyst under at least one of the following operating conditions: - temperature: less than 300°C, preferably 200°C-260°C; - pressure; less than 4 MPa, preferably 2-3 MPa; - Hourly space velocity; 10h -1 (less than 10 liters per hour and volume), preferably 2 to 4 hours -1 ; The catalyst comprises at least one zeolite whose pore openings are defined by rings containing 10 or 12 oxygen atoms (10MR or 12MR), preferentially comprising at least one zeolite whose pore openings are defined by rings containing 10 oxygen atoms (10MR), and even more preferably comprising a ZSM-5 type zeolite.

[0107] According to one or more embodiments, the stabilization column R produces at the bottom a stabilized fraction (20) comprising (for example essentially) benzene and toluene, which is possibly recycled to the inlet of the aromatics extraction unit J. The stabilization column R makes it possible, inter alia, to extract compounds containing 5 or up to 40 carbon atoms, hereinafter referred to as combustible gases or fuel gases.

[0108] The example in Figure 2 above relates to an embodiment in which the conversion device according to the invention is suitable for treating a stream containing aromatic compounds containing 9 and 10 carbon atoms resulting from a fractionation train of an aromatic complex, it should be noted that other configurations are also envisaged, either alone or in combination.

[0109] (Example) (Preparation of Catalyst A Containing IZM-2 Zeolite) Catalyst A is a catalyst containing IZM-2 zeolite, platinum and an alumina matrix.

[0110] (Synthesis of IZM-2 zeolite) IZM-2 zeolite was synthesized according to the teachings of patent FR 2 918 050 B1. A colloidal silica suspension known under the trade name Ludox HS-40 sold by Aldrich is incorporated into a solution composed of sodium hydroxide (Prolabo), 1,6-bis(methylpiperidinium)hexane dibromide structurant, sodium aluminate (Carlo Erba) and deionized water. The molar composition of the mixture is as follows: 1SiO2; 0.0042Al2O3; 0.1666Na2O; 0.1666 1,6-bis(methylpiperidinium)hexane; 33.3333H2O. The mixture is stirred vigorously for 30 minutes. After homogenization, the mixture is transferred to a Parr autoclave. The autoclave is heated at 170°C for 5 days with spindle stirring (30 rpm). The product obtained is filtered, washed with deionized water to reach a neutral pH, then dried overnight in an oven at 100°C. The solid is then introduced into a muffle furnace and calcined to remove the structuring agent. The calcination cycle includes a temperature increase to 200°C, a stationary phase at this temperature for 2 hours, a temperature increase to 550°C, then a stationary phase at this temperature for 8 hours, and finally a return to room temperature. The temperature increase is carried out at a rate of 2°C / min. The solid thus obtained is then refluxed in an aqueous ammonium nitrate solution (10 mL of solution per g of solid weight, ammonium nitrate concentration 3 M) for 2 hours to exchange the sodium alkali cations for ammonium ions. This reflux step is carried out six times with fresh ammonium nitrate solution, and the solid is then filtered off, washed with deionized water and dried overnight in an oven at 100°C. Finally, a calcination step is carried out in a fluidized bed under dry air (2 normal liters per hour and per gram of solid weight) at 550° C. for 10 hours (heating rate 2° C. / min) in order to obtain the zeolite in its acid (protonated H+) form. The solid thus obtained was analyzed by X-ray diffraction and identified as consisting of IZM-2 zeolite.Characterization by X-ray fluorescence (specifically bead assay with a PANalytical AXIOS machine operating at 125 mA and 32 kV) and ICP (specifically a SPECTROS ARCOS ICP-OES machine following the ASTM D7260 method) gave the following results for IZM-2: - The ratio of moles of silicon divided by moles of aluminum (mol / mol), Si / Al: 85; - The ratio of moles of sodium divided by moles of aluminum (mol / mol), Na / Al: 0.03.

[0111] (Forming of Carrier) IZM-2 zeolite is blended with alumina gel of type GA7001 supplied by Axens. The blended paste is extruded through a cylindrical die with a diameter of 1.6 mm. After drying overnight in an oven at 110° C., the extrudates are calcined in a fluidized bed at 550° C. for 2 hours (heating rate 5° C. / min) under dry air (2 normal liters per hour and per gram of solids). The amount of zeolite used is chosen so as to obtain about 14% by weight of zeolite in the calcined extrudates.

[0112] (Platinum impregnation) Platinum is then deposited in the extrudates by dry impregnation in a dredger with an aqueous solution of platinum tetraamine chloride Pt(NH3)4Cl2. The platinum content in the impregnation solution is adjusted to obtain about 0.3% platinum by weight on the catalyst after calcination. After impregnation, the extrudates are left to age in laboratory air for 5 hours and then dried overnight in an oven at 110°C. The extrudates are then calcined in a fluidized bed under a flow of dry air (1 normal liter per hour and per gram of solids) under the following conditions: - Ambient to 150°C: 5°C / min, - stationary phase at 150 °C for 1 h, - 150°C to 450°C ramp; 5°C / min; - stationary phase at 450°C for 1 hour, - Cool to room temperature.

[0113] Characterization by X-ray fluorescence, Castaing microprobe and H2 / O2 titration gives access to the following results for catalyst A: - Percentage of IZM-2 zeolite (dry mass): 13% by weight - Platinum percentage (dry mass): 0.31% by weight - Dispersion of platinum: 66% - Platinum distribution coefficient: 0.85.

[0114] (Preparation of Catalyst B Containing ZSM-12 Zeolite) Catalyst B is a catalyst containing ZSM-12 zeolite, platinum and an alumina matrix.

[0115] (Synthesis of ZSM-12 zeolite) The ZSM-12 zeolite is a commercial zeolite supplied by Zeolyst. Its commercial reference number is CP788. It is supplied in its ammonium form. The solid thus obtained was analyzed by X-ray diffraction and identified as consisting of ZSM-12 zeolite.

[0116] (Forming of Carrier) The ZSM-12 zeolite is blended with alumina gel of type GA7001 supplied by Axens. The blended paste is extruded through a cylindrical die of 1.6 mm diameter. After drying overnight in an oven at 110° C., the extrudates are calcined under dry air (2 normal liters per hour and per gram of solids) in a fluidized bed at 550° C. for 2 hours (heating rate 5° C. / min). The amount of zeolite used is chosen so as to obtain about 8% by weight of zeolite in the calcined extrudates.

[0117] (Platinum impregnation) Platinum is then deposited in the extrudates by dry impregnation in a dredger with an aqueous solution of platinum tetraamine chloride Pt(NH3)4Cl2. The platinum content in the impregnation solution is adjusted to obtain about 0.25% platinum by weight on the catalyst after calcination. After impregnation, the extrudates are left to age in laboratory air for 5 hours and then dried overnight in an oven at 110°C. The extrudates are then calcined in a fluidized bed under a flow of dry air (1 normal liter per hour and per gram of solids) under the following conditions: - Ambient to 150°C: 5°C / min, - stationary phase at 150 °C for 1 h, - 150°C to 450°C ramp; 5°C / min; - stationary phase at 450°C for 1 hour, - Cool to room temperature.

[0118] Characterization by X-ray fluorescence, Castaing microprobe and H2 / O2 titration gives access to the following results for catalyst B: - Percentage of ZSM-12 zeolite (dry mass): 8% by weight - Platinum percentage (dry mass): 0.24% by weight - Dispersion of platinum: 90% - Platinum distribution coefficient: 1.01.

[0119] (Preparation of Catalyst C Containing EU-1 Zeolite) Catalyst C is a catalyst containing EU-1 zeolite, platinum and an alumina matrix.

[0120] (Synthesis of EU-1 zeolite) The EU-1 zeolite is synthesized according to the teaching of patent EP 0 042 226 B1 using the organic structuring agent 1,6-N,N,N,N',N',N'-hexamethylhexamethylenediammonium. For the preparation of such a zeolite, the reaction mixture has the following molar composition: 60SiO2: 10.6Na2O: 5.27NaBr: 1.5Al2O3: 19.5Hexa-Br2: 2777H. Hexa-Br2 is 1,6-N,N,N,N',N',N'-hexamethylhexamethylenediammonium, bromine is the counterion. The reaction mixture is placed in an autoclave at 180°C for 5 days with stirring (300 rpm).

[0121] The EU-1 zeolite is first subjected to a dry calcination at 550° C. for 10 hours under a stream of dry air to remove the organic structuring agent. The solid obtained is then refluxed in an ammonium nitrate solution (100 mL of solution per gram of solid weight, 10M ammonium nitrate solution) for 4 hours to exchange the alkali metal cations with ammonium ions. This exchange step is carried out four times. The solid is then calcined in a tube furnace at 550° C. for 4 hours. X-ray diffraction analysis confirms that the EU-1 zeolite has been obtained. Characterization by X-ray fluorescence (in particular bead assay with a PANalytical AXIOS machine operating at 125 mA and 32 kV) and ICP (in particular a SPECTRO ARCOS ICP-OES machine according to the ASTM D7260 method) gives access to the following results for EU-1: - The ratio of moles of silicon divided by moles of aluminum (mol / mol), Si / Al: 15; - The ratio of moles of sodium divided by moles of aluminum (mol / mol), Na / Al: 0.01.

[0122] (Forming of Carrier) The EU-1 zeolite is blended with alumina gel of type GA7001 supplied by Axens. The blended paste is extruded through a cylindrical die with a diameter of 1.6 mm. After drying overnight in an oven at 110° C., the extrudates are calcined under dry air (2 normal liters per hour and per gram of solids) in a fluidized bed at 550° C. for 2 hours (heating rate 5° C. / min). The amount of zeolite used is chosen so as to obtain about 10% by weight of zeolite in the calcined extrudates.

[0123] (Platinum impregnation) The support thus obtained is subjected to anion exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid) so as to deposit 0.3% by weight of platinum relative to the catalyst. The wet solid is then dried at 120° C. for 12 hours and calcined in air at a temperature of 500° C. for 1 hour.

[0124] Characterization by X-ray fluorescence, Castaing microprobe and H2 / O2 titration gives access to the following results for catalyst C: - Percentage of EU-1 zeolite (dry mass): 11% by weight - Platinum percentage (dry mass): 0.29% by weight - Dispersion of platinum: 85% - Platinum distribution coefficient: 0.97.

[0125] Example 1 Example 1 illustrates the performance of isomerization unit A, in which an aromatic fraction containing mainly 9 carbon atoms is processed, the mass composition of which is detailed in Table 2 below.

[0126] [Table 2]

[0127] Once prepared, these catalysts undergo an in situ activation step in the isomerization unit. The catalysts first undergo a drying step under a nitrogen stream under the following conditions: - Nitrogen flow rate: 5NL / h / gram of catalyst; - Total pressure: 1.3 MPa absolute; - Heating rate: from ambient temperature to 150°C: 10°C / min; - Stationary phase of 30 min at 150 °C.

[0128] The nitrogen is then replaced with hydrogen and a catalytic reduction step is carried out under the following conditions: - Hydrogen flow rate: 4NL / h / gram of catalyst; - Total pressure: 1.3 MPa absolute; - Heating rate from 150℃ to 480℃: 5℃ / min; - Stationary phase at 480°C for 2 hours.

[0129] After reduction, the temperature is reduced to 425° C. before evaluating the catalytic performance, and then the catalyst is stabilized under flow of A9 feedstock and hydrogen for 24 hours under the following conditions: - Total pressure: 1.3 MPa absolute; - reactor temperature: 385°C; - Hydrogen coverage: 24 moles of H per mole of hydrocarbon; - WWH: 5 grams of hydrocarbon per gram of catalyst and per hour.

[0130] The A9 isomerization unit operates in a fixed bed under the following conditions: - Reactor pressure: 1.3MPa; - reactor temperature: 385°C; - Hydrogen coverage: 24 moles of H per mole of hydrocarbon; - WWH:4.5h -1 .

[0131] The performance of the tests for the three types of catalysts is shown in Table 3. The 5-12% increase in trimethylbenzene shows the advantage of the A9 isomerization unit described in this invention.

[0132] [Table 3]

[0133] Example 2 Example 2 illustrates the performance of an isomerization unit A using a catalyst B based on ZSM-12 in combination with an extraction unit H processing an aromatic fraction containing mainly 9 carbon atoms. The test performance is presented in Table 4 below.

[0134] [Table 4]

[0135] Advantageously, the performance of the conversion device according to the invention is improved due to the trimethylbenzene depletion of the feedstock by adding a step for extracting methyl-substituted aromatic compounds. This extraction step is carried out by extraction unit H.

[0136] Example 3 Example 3 illustrates the case where the conversion device according to the invention processes a fraction containing mainly A9 internal to the aromatic complex (see FIG. 2), since said fraction is enriched in trimethylbenzene isomers (especially methylethylbenzene).

[0137] Specifically, the (e.g., essentially) aromatic C9-C10 effluent (31) (A9+) recovered from the bottom of the xylene column M is sent to an extraction unit H as the hydrocarbon feedstock (1) of the conversion device according to the present invention.

[0138] The extraction unit H treats the hydrocarbon feedstock (1) so as to extract trimethylbenzene, thus producing a trimethylbenzene-enriched effluent (14) and a trimethylbenzene-depleted hydrocarbon feedstock (15), which is sent to the isomerization unit A.

[0139] The trimethylbenzene-enriched effluent (14) (which also contains A10+ compounds) is sent to heavy aromatics column N, which feeds transalkylation unit O.

[0140] The isomerization unit A according to the invention may be understood as a unit for the pretreatment of the A9 fraction upstream of the transalkylation unit O.

[0141] The isomerization unit A produces an isomerization effluent (10) which may contain xylenes which are extracted by separation unit G before being fed to the transalkylation unit O. In fact, the isomerization unit A may be in thermodynamic equilibrium, producing xylenes by A9+ / A7 transalkylation. It is therefore preferred to extract the xylenes so as not to adversely affect the conversion.

[0142] The inlet feed (16) (reformate) feeding the complex has the composition shown in Table 5 below. The total mass flow rate of aromatics is 250 t / h.

[0143] [Table 5]

[0144] The performance of the aromatic complexes with the conversion device according to the invention is shown in Table 6 below.

[0145] [Table 6]

[0146] The conversion device according to the invention in combination with the aromatic complex allows in Example 3 a gain in paraxylene production of the order of 6% by co-production of paraxylene and benzene.

[0147] In this patent application, the term "to comprise" is synonymous with "to include" and "to contain" and is inclusive or open-ended, not excluding other elements not listed. The term "comprise" is understood to include the exclusive and closed term "consisting of". Furthermore, in this specification, the terms "approximately", "substantially", "essentially", "solely" and "about" are synonymous with a margin of more than and / or less than 5%, preferably more than and / or less than 2%, and highly preferably more than and / or less than 1% of a given value. For example, an effluent that essentially or solely comprises compound A corresponds to an effluent that comprises at least 95%, preferably at least 98%, and highly preferably at least 99% of compound A. As another example, a composition that is substantially 100 (°C, MPa g, h -1 etc.) corresponds to a value of 95-105, preferably 98-102, highly preferably 99-101. [Brief description of the drawings]

[0148] [Figure 1] 1 illustrates an aromatics conversion device according to one or more embodiments of the present invention. [Diagram 2] 1 depicts an aromatics complex for the production of para-xylene, incorporating an aromatics conversion device according to one or more embodiments of the present invention.

Claims

1. 1. A method for converting aromatic compounds, comprising the steps of: isomerizing aromatic compounds of a hydrocarbon feedstock (1), comprising aromatic compounds containing 9 carbon atoms, in an isomerization unit (A) in the presence of a bifunctional isomerization catalyst having a hydrogenation / dehydrogenation function and a hydroisomerization function to produce an isomerized effluent (10) enriched in trimethylbenzenes.

2. 2. The process according to claim 1, wherein the isomerization of aromatic compounds of the hydrocarbon feedstock (1) is carried out under at least one of the following operating conditions: a temperature between 250°C and 450°C, preferentially between 355°C and 390°C, for example a temperature of 385°C; a pressure between 0.1 MPa absolute and 3 MPa absolute, preferentially between 0.2 MPa absolute and 1.5 MPa absolute; - H ２ / HC molar ratio of 1 to 5, preferentially 3 to 4.5, e.g. H ２ / HC molar ratio 4; - WWH1h －１ ~30 hours －１ , 3 hours as a priority －１ ~12 hours －１ the term WWH corresponds to the weight of hydrocarbon feed injected per hour relative to the weight of catalyst fed.

3. 2. The conversion process of claim 1, wherein the isomerization catalyst comprises at least one metal from Group VIIIB of the Periodic Table of the Elements as a hydrogenation / dehydrogenation functional metal, at least one molecular sieve as a hydroisomerization functional metal, and optionally at least one matrix.

4. 2. The process of claim 1, wherein the hydrocarbon feedstock (1) contains aromatic compounds containing 9 carbon atoms and having alkyl chains containing 2 or 3 carbon atoms.

5. 10. The conversion process of claim 1, comprising the steps of: - treating the isomerization effluent (10) in a separation unit (G) located downstream, possibly directly downstream, of the isomerization unit (A); giving rise to at least a first separated fraction (11) and a fraction of unconverted compounds (13), the latter being recycled to the inlet of the isomerization unit (A).

6. 10. The conversion process of claim 1, comprising the steps of: - treating the hydrocarbon feedstock (1) in an extraction unit (H), which is located upstream, possibly directly upstream, of the isomerization unit (A); extracting trimethylbenzene and producing a trimethylbenzene-depleted hydrocarbon feedstock (15), which is sent to the isomerization unit.

7. A process for the production of xylenes incorporating the conversion process of any one of claims 1 to 6, comprising the steps of: - All or part of the isomerized effluent (10) rich in trimethylbenzene is sent to an aromatics complex to produce xylenes.

8. 8. The process for producing xylenes according to claim 7, wherein the conversion process is integrated into the aromatic complex by at least one of the following configurations: - pretreatment of hydrocarbon feedstocks (1) upstream of the aromatic complex; - Treatment of at least one fraction internal to the aromatic complex.

9. 9. A method for producing xylenes according to claim 8, comprising the steps of: sending the aromatic effluent from the xylene column (M) of the aromatic complex, comprising compounds containing 9 to 10 carbon atoms, as hydrocarbon feedstock (1) to an isomerization unit (A);

10. 1. A device for converting aromatic compounds, comprising: an isomerization unit (A) suitable for isomerizing aromatic compounds of a hydrocarbon feedstock (1), including aromatic compounds containing 9 carbon atoms, in the presence of a bifunctional isomerization catalyst having a hydrogenation / dehydrogenation function and a hydroisomerization function; giving an isomerization effluent (10) enriched in trimethylbenzenes;

11. 11. The conversion device of claim 10, comprising: a separation unit (G) located downstream, possibly directly downstream, of the isomerization unit (A) and suitable for treating the isomerization effluent (10) so as to give at least a first separated fraction (11) and a fraction of unconverted compounds (13), the latter being recycled to the inlet of the isomerization unit (A).

12. 12. A conversion device according to claim 10 or 11, comprising: an extraction unit (H), located upstream, possibly directly upstream, of the isomerization unit (A); suitable for treating the hydrocarbon feedstock (1) so as to extract trimethylbenzene and to produce a trimethylbenzene-depleted hydrocarbon feedstock (15), which is sent to the isomerization unit (A).

13. 11. A xylene production device incorporating the conversion device of claim 10, comprising: a feed line suitable for sending all or part of the isomerized effluent (10) rich in trimethylbenzene to an aromatics complex to give xylenes.

14. 14. The xylene production device of claim 13, wherein the conversion device is integrated into the aromatic complex according to at least one of the following configurations: - pretreatment of hydrocarbon feedstocks (1) upstream of the aromatic complex; - Treatment of at least one fraction internal to the aromatic complex.

15. 15. The xylene production device of claim 14, comprising: a feed line suitable for sending the aromatic effluent containing compounds containing 9 to 10 carbon atoms from the xylene column (M) of the aromatic complex to the isomerization unit (A) as hydrocarbon feedstock (1).

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