Production of aromatics by conversion of syngas to methanol and alkylation of toluene

Abstract

Disclosed are a production and conversion device and method comprising / using: a fractionation train (4-6) producing a xylene fraction (24); a xylene separation unit (10) treating the xylene fraction to produce a paraxylene extract (39) and a raffinate (40); an isomerization unit (11) treating the raffinate to produce an isomerate (42) of xylenes sent to the fractionation train; a syngas production unit (14; 15) treating a hydrocarbon feedstock (30) to produce a syngas (34) containing CO and CO2; a methanol synthesis reaction section (50) treating the syngas (34) to produce methanol (51); a toluene alkylation reaction section (13) treating a fraction containing toluene (23) with the methanol (51) to produce an alkylation effluent (32) that contains xylenes and is sent to the fractionation train.

Description

[0001] Production of aromatics by conversion of synthesis gas to methanol and alkylation of toluene

[0002] Technical field

[0003] The invention relates to the production of aromatics for petrochemistry (benzene, toluene, xylenes, ie, BTX). More particularly, the subject of the invention relates to the production of aromatics (eg paraxylene) from the conversion of hydrocarbon compounds (eg biomass) into synthesis gas comprising CO and CO2.

[0004] An aromatic complex (or aromatics conversion device) is a device powered by feedstocks predominantly composed of six to ten or more carbon atoms, referred to as C6 to C10+ feedstocks. Different sources of aromatics can be introduced into an aromatic complex, the most common being derived from a catalytic naphtha reforming process.

[0005] Within an aromatic complex, regardless of the source of aromatics, benzene and aromatic alkyls (e.g. toluene, paraxylene, orthoxylene) are extracted and then converted into desired intermediates. The products of interest are aromatics with 0 (benzene), 1 (toluene) or 2 (xylenes) methyl groups, and in particular, within xylenes, paraxylene, having the highest market value.

[0006] Oxy-fuel pyrolysis and hydrocarbon gasification processes produce a large amount of recoverable carbon monoxide (CO) and carbon dioxide (CO2). Pyrolysis processes also produce aromatic compounds. When pyrolysis is catalytic, the combustion of coke present on the catalyst used in the pyrolysis reactor also produces a significant amount of CO2.

[0007] Prior art

[0008] To date, aromatic complexes can be used to produce benzene, possibly toluene, and xylenes (often paraxylene, sometimes orthoxylene). An aromatic complex generally has at least one catalytic unit with at least one of the following functions: the isomerization of aromatic compounds with 8 carbon atoms, denoted A8 compounds, to convert orthoxylene, metaxylene and ethylbenzene into paraxylene; transalkylation to produce xylenes from a mixture of toluene (and optionally benzene) and A9+ compounds such as trimethylbenzenes and tetramethylbenzenes; and the disproportionation of toluene, which can produce benzene and xylenes. The aromatic loop can produce high-purity paraxylene by adsorption separation or by crystallization, an operation well known in the prior art. This “C8-aromatic loop” includes a step of elimination of heavy compounds (i.e., C9+) in a distillation column called the “xylene column”. The overhead stream from this column, which contains the C8-aromatic isomers (i.e., A8), is then sent to the paraxylene separation process, which is most commonly a simulated moving bed adsorption separation (SMB) process to produce an extract and a raffinate, or a crystallization process in which a paraxylene fraction is isolated from the rest of the mixture constituents in the form of crystals.

[0009] The extract, which contains paraxylene, is then distilled to obtain high-purity paraxylene. The raffinate, rich in metaxylene, orthoxylene and ethylbenzene, is treated in a catalytic isomerization unit which gives back a mixture of C8 aromatics, in which the proportion of xylenes (ortho-, meta-, para-xylenes) is practically at thermodynamic equilibrium and the quantity of ethylbenzene is reduced. This mixture is again sent to the "xylene column" with the fresh feed.

[0010] Aromatic complexes producing benzene and paraxylene are overwhelmingly supplied by feedstocks derived from oil or natural gas. These complexes do not allow the production of bio-sourced aromatics. Another challenge is to recover carbon in the form of CO and CO2, and in particular bio-sourced carbon, into high value-added compounds. One object of the present invention is to overcome these drawbacks.

[0011] Summary of the invention

[0012] In the context described above, a first object of the present description is to overcome the problems of the prior art and to provide a method and a device for producing aromatics for petrochemistry making it possible to convert (for example in full) CO and CO2 produced by pyrolysis or oxycombustion, into additional aromatic compounds. The CO2 from the combustion of the coke present on the catalyst of the pyrolysis process can also be advantageously converted into aromatic compounds.

[0013] The invention is based on the conversion of carbon monoxide, i.e., CO, and carbon dioxide, i.e., CO2, into chemical compounds which are introduced into the aromatic complex, and in particular on the arrangement of several units making it possible to convert CO and CO2 into aromatic compounds in two stages: in a methanol synthesis reactor then in a toluene alkylation reactor. The aromatic compounds, and in particular xylenes, resulting from the conversion of CO and CO2 are treated within the aromatic loop.

[0014] The invention is thus based on the conversion of CO and CO2 and on the introduction of methanol into the aromatic complex. Specifically, the object of the present invention can be summarized in providing a pyrolysis unit or an oxycombustion or gasification unit for producing methanol as well as an alkylation reaction section for converting toluene by reaction with methanol into xylenes.

[0015] Advantageously, the invention makes it possible to convert CO and CO2 into aromatic compounds of interest, to selectively convert toluene into xylenes, and to remove the toluene transalkylation or disproportionation unit usually present in aromatic complexes to convert toluene.

[0016] According to a first aspect, the aforementioned objects, as well as other advantages, are obtained by a method for producing and converting a hydrocarbon feedstock, comprising the following steps: fractionating a first hydrocarbon feedstock in a fractionation train to extract at least one cut comprising benzene, one cut comprising toluene and one cut comprising xylenes and ethylbenzene; separating the cut comprising xylenes and ethylbenzene in a xylene separation unit and producing an extract comprising paraxylene and a raffinate comprising orthoxylene, metaxylene and ethylbenzene; isomerizing the raffinate in an isomerization unit and producing a paraxylene-enriched isomerate; sending the paraxylene-enriched isomerate to the fractionation train;treating a second hydrocarbon feedstock in a synthesis gas production unit, such as for example a pyrolysis unit or an oxycombustion unit, to produce a synthesis gas comprising at least carbon monoxide (CO) and carbon dioxide (CO2); treating the synthesis gas in a methanol synthesis reaction section to produce methanol; alkylating at least a portion, and preferably all, of the cut comprising toluene with methanol in an alkylation reaction section and producing an alkylation effluent comprising xylenes; and sending the effluent comprising xylenes to the xylene separation unit.;

[0017] According to one or more embodiments, the method comprises treating methanol in a purification section to separate water and produce purified methanol.

[0018] According to one or more embodiments, the purification section is adapted to separate a recycle gas comprising unconverted CO and / or unconverted CO2, and recycle the recycle gas to the inlet of the methanol synthesis reaction section.

[0019] One of the advantages of the present invention is in particular to be able, by means of recycling, to convert all of the synthesis gas. According to one or more embodiments, the synthesis gas production unit comprises a pyrolysis unit adapted to produce at least one pyrolysis effluent comprising hydrocarbon compounds of 6 to 10 carbon atoms at least partially feeding the first hydrocarbon feedstock.

[0020] According to one or more embodiments, the method comprises providing a supply of hydrogen (H2) in the synthesis gas, for example a make-up line arranged (directly) upstream of the methanol synthesis reaction section.

[0021] According to one or more embodiments, the synthesis gas production unit comprises a pyrolysis unit comprising at least one reactor used under at least one of the following operating conditions: absolute pressure between 0.1 MPa and 0.5 MPa and WH between 0.01 h -1 and 10 a.m. 1 , preferably between 0.01 h -1 and 5 a.m. -1 , and very preferably between 0.1 h -1 and 3 hours -1, WH is the ratio of the volume flow rate of feedstock to the volume of catalyst used; temperature between 400°C and 1000°C, preferably between 400°C and 650°C, preferably between 450°C and 600°C and preferably between 450°C and 590°C; zeolitic catalyst comprising and preferably consisting of at least one zeolite chosen from ZSM-5, ferrierite, zeolite Beta, zeolite Y, mordenite, ZSM-23, ZSM-57, EU-1, ZSM-11 and preferably the catalyst is a catalyst comprising only ZSM-5; or the synthesis gas production unit comprises an oxycombustion unit comprising at least one reactor used in at least one of the following operating conditions: a reactor operating in a fluidized bed; temperature between 500°C and 1000°C; pressure between 0.1 MPa and 3 MPa, preferably between 0.1 MPa and 1 MPa;or a gasification unit comprising at least one gasification furnace used under at least one of the following operating conditions: temperature between 700°C and 1400°C;

[0022] According to one or more embodiments, the methanol synthesis reaction section comprises at least one reactor used under at least one of the following operating conditions: temperature between 200°C and 450°C, preferably between 220°C and 400°C, and more preferably still between 250°C and 350°C; pressure between 1 MPa and 12 MPa, preferably between 2 MPa and 10 MPa, and more preferably between 5 MPa and 10 MPa; hydrogen to COx molar ratio in which COx represents CO and CO2, between 3 and 10, preferably between 3 and 7, very preferably between 3 and 5; space velocity of the gas at the reactor inlet between 0.2 g / g ca ta / h and 1 g / g ca your / h.

[0023] According to one or more embodiments, the alkylation reaction section comprises at least one alkylation reactor used under at least one of the following operating conditions: temperature between 20°C and 550°C; pressure between 1 MPa and 10 MPa; toluene / methanol molar ratio between 1 and 5;

[0024] PPH between 0.5 h -1 and 50 h -1 ; presence of a catalyst comprising a zeolite.

[0025] According to one or more embodiments, the isomerization unit comprises a gas-phase isomerization zone used under at least one of the following operating conditions: temperature greater than 300°C; pressure less than 4.0 MPa; hourly space velocity less than 10 h' 1; hydrogen to hydrocarbon molar ratio less than 10; presence of a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 or 12 oxygen atoms, and at least one metal from group VII IB with a content of between 0.1 and 0.3% by weight, limits included.

[0026] According to one or more embodiments, the isomerization unit comprises a liquid phase isomerization zone used under at least one of the following operating conditions: temperature less than 300 C; pressure less than 4 MPa; hourly space velocity less than 10 h' 1 ; presence of a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 or 12 oxygen atoms.

[0027] According to a second aspect, the aforementioned objects, as well as other advantages, are obtained by a device for producing and converting a hydrocarbon feedstock, comprising: a fractionation train adapted to extract at least one cut comprising benzene, a cut comprising toluene and a cut comprising xylenes and ethylbenzene from a first hydrocarbon feedstock; a xylene separation unit adapted to treat the cut comprising xylenes and ethylbenzene and produce an extract comprising paraxylene and a raffinate comprising orthoxylene, metaxylene and ethylbenzene; an isomerization unit adapted to treat the raffinate and produce an isomerate enriched in paraxylene sent to the fractionation train;a synthesis gas production unit, such as for example a pyrolysis unit or an oxycombustion unit, adapted to treat a second hydrocarbon feedstock and produce a synthesis gas comprising at least carbon monoxide (CO) and carbon dioxide (CO2); a methanol synthesis reaction section adapted to convert CO and CO2 of the synthesis gas into methanol; and an alkylation reaction section adapted to treat at least a portion, and preferably all, of the toluene-containing cut with methanol and produce an alkylation effluent comprising xylenes, in particular paraxylene, sent to the xylene separation unit.;

[0028] According to one or more embodiments, the device comprises a purification section adapted to process the methanol to separate it from water and produce purified methanol.

[0029] According to one or more embodiments, the purification section is adapted to separate a recycle gas comprising unconverted CO and / or unconverted CO2, and recycle the recycle gas to the inlet of the methanol synthesis reaction section.

[0030] According to one or more embodiments, the synthesis gas production unit comprises a pyrolysis unit adapted to produce at least one pyrolysis effluent comprising hydrocarbon compounds of 6 to 10 carbon atoms at least partially feeding the first hydrocarbon feedstock.

[0031] According to one or more embodiments, the device comprises a make-up line for providing a supply of hydrogen in the synthesis gas.

[0032] According to one or more embodiments, the alkylation reaction section is adapted to separate xylenes from a water-containing cut to produce the alkylation effluent.

[0033] According to one or more embodiments, the device further comprises a charge separation unit for separating the first hydrocarbon charge into a hydrocarbon cut with 7 carbon atoms or less sent to the benzene column of the fractionation train, and an aromatic cut with 8 carbon atoms or more sent to the xylenes column of the fractionation train.

[0034] According to one or more embodiments, the device further comprises an aromatics extraction unit between the charge separation unit and the benzene column for separating aliphatic compounds from the aromatic cut with 7 carbon atoms or less and producing an extract sent to the benzene column. According to one or more embodiments, the device further comprises a stabilization column adapted to remove a cut of volatile species from the effluents of the isomerization unit.

[0035] Embodiments according to the first aspect and the second aspect, as well as other characteristics and advantages of the methods and devices according to the aforementioned aspects, will appear on reading the following description, given for illustrative and non-limiting purposes only, and with reference to the following drawing.

[0036] List of figures

[0037] Figure 1 represents a schematic view of a process according to the present invention making it possible to increase the production of paraxylene and to dispense with toluene transalkylation and disproportionation units.

[0038] Description of the embodiments

[0039] Embodiments of the method according to the first aspect and the device according to the second aspect will now be described in detail. In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the method and device according to the present invention. However, it will be apparent to those skilled in the art that the method and device may be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0040] In the present application, the term "comprise" is synonymous with (means the same as) "include" and "contain", and is inclusive or open and does not exclude other elements not recited. It is understood that the term "comprise" includes the exclusive and closed term "consist". Furthermore, in the present description, an effluent comprising essentially or solely compounds A corresponds to an effluent comprising at least 80 or 90% by weight, preferably at least 95% by weight, very preferably at least 99% by weight, of compounds A.

[0041] The present invention can be defined as a method and a device comprising a sequence of unit operations making it possible to produce paraxylene and benzene.

[0042] One of the features of the present invention can be summarized in the use of carbon monoxide (CO) and carbon dioxide (CO2), products of a unit for pyrolysis, oxycombustion or gasification of hydrocarbon compounds, to produce methanol in order to significantly increase the quantity of aromatics produced by pyrolysis, oxycombustion or gasification of hydrocarbon compounds and to potentially recover all of the CO and CO2 produced. The method and the device according to the invention are also characterized in that they use and comprise the catalytic units and the separation units known to those skilled in the art for producing benzene and paraxylene, units which are usually found in aromatic complexes, in that the unit for transalkylation or disproportionation of toluene is not essential, and in that they use and comprise a reaction section for alkylation of toluene by methanol which produces xylenes.One of the features of the present invention consists of the selective transformation of toluene into a mixture of xylenes.

[0043] Referring to Figure 1, according to one or more embodiments, the method and device for producing and converting hydrocarbon compounds use and comprise: an optional feed separation unit 1 for separating a first hydrocarbon feed 2 from the aromatic complex into a hydrocarbon cut with 7 carbon atoms or less (C7-) and an aromatic cut with 8 carbon atoms or more (A8+); an optional aromatic extraction unit 3 between the feed separation unit 1 and a fractionation train 4-6 for separating aliphatic compounds of benzene and toluene from the C7- cut of the first hydrocarbon feed 2; the fractionation train 4-6 downstream of the optional aromatic extraction unit 3 for extracting benzene, toluene and xylenes from the other aromatics;a xylene separation unit 10 (e.g. crystallization or LMS type using a molecular sieve and a desorbent such as toluene) for isolating paraxylene from xylenes and ethylbenzene; an isomerization unit 11 for the raffinate obtained as effluent from the xylene separation unit 10 to convert in particular orthoxylene, metaxylene and ethylbenzene into paraxylene; an optional stabilization column 12, in particular for removing the more volatile species (e.g. C5-) from the aromatic complex, in particular from the effluents from the isomerization unit 11; synthesis gas production unit, such as a pyrolysis unit 14, preferably catalytic, or an oxycombustion or gasification unit 15, for treating a second hydrocarbon feedstock 30, making it possible to produce a synthesis gas 34 comprising CO, CO2 and optionally hydrogen and / or water;a methanol synthesis reaction section 50 for treating the synthesis gas 34 from the pyrolysis unit 14 or from the oxycombustion or gasification unit 15, and producing methanol 51; an optional first make-up line for providing a hydrogen supply 35 in the synthesis gas 34; an optional purification section 52 for treating the methanol, separating a water purge 53 and a recycle gas 54 comprising unconverted CO and / or unconverted CO2, and producing purified methanol 55; a toluene alkylation reaction section 13 for alkylating with the methanol 51 or the purified methanol 55 a fraction comprising toluene, and preferably all of said fraction, with methanol and producing xylenes.;

[0044] Advantageously, the methanol synthesis reaction section 50 and the toluene alkylation reaction section 13 make it possible to produce a surplus of aromatics from CO and / or CO2, by the addition of methanol (addition of a carbon atom to each toluene molecule) and gives the possibility of significantly increasing the quantity of paraxylene.

[0045] According to one or more embodiments, the purification section 52 is adapted to recycle the recycle gas 54 to the inlet of the methanol synthesis reaction section 50.

[0046] With reference to Figure 1, the feed separation unit 1 treats the first hydrocarbon feed 2 of the aromatic complex to separate a top cut comprising (eg essentially) compounds with 7 carbon atoms or less 16 (C7-) containing in particular benzene and toluene, and a bottom cut comprising (eg essentially) aromatics with 8 carbon atoms or more 17 (A8+) sent to the xylene column 6. According to one or more embodiments, the feed separation unit 1 also separates a first toluene cut 18 comprising at least 90% by weight, preferably at least 95% by weight, very preferably at least 99% by weight of toluene. According to one or more embodiments, the first toluene cut 18 is sent to the first aromatic compound distillation column 4, also called the benzene column, and / or to the second aromatic compound distillation column 5, also called the toluene column.

[0047] According to one or more embodiments, the first hydrocarbon feedstock 2 is a hydrocarbon cut containing predominantly (i.e., > 50% by weight) molecules whose carbon number ranges from 6 to 10 carbon atoms. This feedstock may also contain molecules having more than 10 carbon atoms and / or molecules with 5 carbon atoms.

[0048] The first hydrocarbon feedstock 2 of the aromatic complex is rich in aromatics (eg > 50% by weight) and preferably contains at least 20% by weight of benzene, preferably at least 30% by weight, very preferably at least 40% by weight of benzene, relative to the total weight of the first hydrocarbon feedstock 2. The first hydrocarbon feedstock 2 may be produced by catalytic reforming of a naphtha or be a product of a cracking unit (eg steam, catalytic) or any other means of producing aromatic alkyls. According to one or more embodiments, the first hydrocarbon feedstock 2 is at least partially or even entirely biosourced. According to one or more embodiments, the first hydrocarbon feedstock 2 originates (essentially) from a process for converting lignocellulosic biomass.For example, an effluent produced by conversion of lignocellulosic biomass can be treated to meet the required specifications of the first hydrocarbon feedstock 2 in order to have contents of sulfur, nitrogen and oxygenated elements compatible with an aromatic complex.

[0049] According to one or more embodiments, the first hydrocarbon feedstock 2 of the aromatic complex comprises at least 25% by weight, preferably at least 30% by weight, very preferably at least 35% by weight of pyrolysis effluent 21, relative to the total weight of the first hydrocarbon feedstock 2. According to one or more embodiments, the first hydrocarbon feedstock 2 of the aromatic complex is substantially made up of the pyrolysis effluent 21. According to one or more embodiments, the first hydrocarbon feedstock 2 may comprise a mixture of biosourced aromatic and paraffinic compounds and a mixture of non-biosourced aromatic and paraffinic compounds (for example originating from a catalytic reforming unit).

[0050] According to one or more embodiments, the first hydrocarbon feedstock 2 comprises less than 10 ppm by weight, preferably less than 5 ppm by weight, very preferably less than 1 ppm by weight of elemental nitrogen, and / or less than 10 ppm by weight, preferably less than 5 ppm by weight, very preferably less than 1 ppm by weight of elemental sulfur, and / or less than 100 ppm by weight, preferably less than 50 ppm by weight, very preferably less than 10 ppm by weight of elemental oxygen.

[0051] According to one or more embodiments, the overhead cut 16 from the charge separation unit 1, optionally mixed with the bottom product (benzene and toluene) from the stabilization column 12 defined below, is advantageously sent to the aromatics extraction unit 3 in order to extract an effluent comprising C6-C7 aliphatic species 19 which is exported as a co-product of the aromatic complex. The aromatic cut 20 (essentially benzene and toluene), called extract from the aromatics extraction unit 3, is sent to the benzene column 4. According to one or more embodiments, the aromatic cut 20 is a hydrocarbon feedstock (eg essentially) aromatic in C6-C7 (A6-A7).

[0052] According to one or more embodiments, the fractionation train comprises the aromatic compound distillation columns 4, 5 and 6 making it possible to separate the following four cuts: a cut comprising (eg essentially) benzene 22; a cut comprising (eg essentially) toluene 23; a cut comprising (eg essentially) xylenes and ethylbenzene 24; a cut comprising (eg essentially) aromatic compounds with 9 and 10 carbon atoms 29;

[0053] The benzene column 4 is suitable for: treating the aromatic cut 20 which is a hydrocarbon feedstock (e.g. essentially) aromatic in C6-C10 (A6+); producing at the top the cut comprising benzene 22 which can be one of the products sought at the outlet of the aromatic complex; and producing at the bottom an effluent (e.g. essentially) aromatic in C7-C10 27 (A7+).

[0054] The toluene column 5 is suitable for: treating the C7-C10 aromatic effluent 27 (A7+), the bottom product of the benzene column 4; producing at the top the cut comprising toluene 23 which is directed towards the toluene alkylation reaction section 13; and producing at the bottom an effluent (e.g. essentially) C8-C10 aromatic 28 (A8+).

[0055] The third aromatic compound distillation column 6, also called xylene column, is suitable for: treating the aromatic cut with 8 carbon atoms or more 17 (A8+) of the first hydrocarbon feedstock 2 and optionally the bottom effluent from the toluene column 28; producing at the top the cut comprising xylenes and ethylbenzene 24 which is directed to the xylene separation unit 10; and producing at the bottom an effluent (eg essentially) comprising C9-C10 aromatics 29 (A9+).

[0056] At the top of the toluene column 5 is obtained the cut comprising toluene 23 which is sent, at least in part, and preferably in full, to the toluene alkylation reaction section 13 for reaction with the methanol 51 or the purified methanol 55 to produce an alkylation effluent 32 comprising xylenes. In addition, a cut containing water 31 co-product of the alkylation reaction of toluene by methanol, and possibly oxygenated by-products, are extracted from the aromatic complex.

[0057] According to one or more embodiments, the toluene alkylation reaction section 13 is fed with a mixture consisting (e.g. essentially) of toluene and methanol (and optionally water). According to one or more embodiments, the toluene is used in excess.

[0058] According to one or more embodiments, the toluene alkylation reaction section 13 comprises at least one alkylation reactor adapted to be used under at least one of the following operating conditions: temperature between 20°C and 550°C or between 100°C and 500°C, preferably between 200°C and 450°C, and more preferably still between 200°C and 300°C; pressure between 1 MPa and 10 M Pa or 1 MPa and 8 MPa, preferably between 2 MPa and 7 MPa, and more preferably between 3 MPa and 5 MPa; toluene / methanol molar ratio between 1 and 5, and preferably between 1 and 4;

[0059] PPH between 0.5 h -1 and 50 h -1 , preferably between 1 h -1 and 10 a.m. -1 , and more preferably between 1.5 h -1 and 8 a.m. -1 .

[0060] The term PPH corresponds to the weight of injected hourly hydrocarbon charge relative to the weight of loaded catalyst.

[0061] According to one or more embodiments, the alkylation reactor is operated in the presence of a catalyst comprising a zeolite. According to one or more embodiments, the catalyst is based on ZSM-5 zeolite, preferably based on ZSM-5 zeolite modified by the addition of oxides of various elements (B, Al, Si, P, Zn, Sb, P and Mg), very preferably based on ZSM-5 zeolite comprising phosphorus.

[0062] According to one or more embodiments, the alkylation reactor is of the fixed bed type.

[0063] The alkylation effluent 32 comprising xylenes from the toluene alkylation reaction section 13 is sent to the xylene separation unit 10. According to one or more embodiments, the alkylation effluent 32 comprising xylenes from the toluene alkylation reaction section 13 is sent to the toluene column 5. Advantageously, the excess toluene used is recycled to the toluene column 5 as a component of the alkylation effluent 32 comprising xylenes. According to one or more embodiments, the alkylation effluent 32 comprising xylenes from the toluene alkylation reaction section 13 is sent directly to the xylene separation unit 10, for example when the toluene content in the alkylation effluent 32 is low (eg <5% by weight) or when the toluene alkylation reaction section 13 comprises a section suitable for separating the toluene from the xylenes.

[0064] The fraction comprising xylenes and ethylbenzene 24 is treated in the xylene separation unit 10 to produce a fraction or extract 39 comprising paraxylene and a raffinate 40. The extract 39 can then be distilled (e.g. if adsorption separation in LMS), for example by means of an extract column and then an additional toluene column (not shown) in the case where toluene is used as a desorbent, to obtain high-purity paraxylene exported as the main product. The raffinate 40 from the xylene separation unit 10 comprises (e.g. essentially) orthoxylene, metaxylene and ethylbenzene and feeds the isomerization unit 11.

[0065] According to one or more embodiments, the xylene separation unit 10 also separates a second toluene cut (not shown) comprising at least 90% by weight, preferably at least 95% by weight, very preferably at least 99% by weight of toluene. The second toluene cut may be, for example, a portion of the toluene used as a desorbent when the xylene separation unit 10 comprises an LMS adsorption unit. According to one or more embodiments, the second toluene cut is sent to the benzene column 4 and / or the second toluene column 5.

[0066] In the isomerization reaction section (not shown) of the isomerization unit 11, the paraxylene isomers are isomerized while the ethylbenzene can be: isomerized into a mixture of C8 aromatics, for example if it is desired to produce mainly paraxylene; and / or dealkylated to produce benzene, for example if it is desired to produce both paraxylene and benzene. According to one or more embodiments, the effluents from the isomerization reaction section are sent to a second separation column (not shown) to produce at the bottom an isomerate 42 enriched in paraxylene preferably recycled to the xylene column 6; and to produce at the top a hydrocarbon cut comprising compounds with 7 carbon atoms or less 43 (C7-) sent to the optional stabilization column 12.

[0067] According to one or more embodiments, the isomerization unit 11 comprises a first isomerization zone working in the liquid phase, and / or a second isomerization zone working in the gas phase. According to one or more embodiments, the isomerization unit 11 comprises a first isomerization zone working in the liquid phase, and a second isomerization zone working in the gas phase. According to one or more embodiments, a first portion of the raffinate 40 is sent to the liquid-phase isomerization unit, to obtain a first isomerate directly and at least partially feeding the separation unit 10, and a second portion of the raffinate 40 is sent to the gas-phase isomerization unit to obtain an isomerate which is sent to the xylene column 6.

[0068] According to one or more embodiments, the gas phase isomerization zone is suitable for use under at least one of the following operating conditions: temperature above 300°C, preferably from 350°C to 480°C; pressure below 4.0 MPa, and preferably from 0.5 MPa to 2.0 MPa; hourly space velocity below 10 h -1 (10 liters per liter per hour), preferably between 0.5 h -1 and 6 a.m. -1; hydrogen to hydrocarbon molar ratio less than 10, and preferably between 3 and 6; presence of a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 or 12 oxygen atoms (10 MR or 12 MR), and at least one metal from group VII IB with a content of between 0.1 and 0.3% by weight (reduced form), limits included. According to one or more embodiments, the liquid phase isomerization zone is suitable for use in at least one of the following operating conditions: temperature less than 300°C, preferably 200°C to 260°C; pressure less than 4 MPa, preferably 2 MPa to 3 MPa; hourly space velocity (WH) less than 10h' 1 (10 liters per liter per hour), preferably between 2 h' 1 and 4 a.m. 1; in the presence of a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 or 12 oxygen atoms (10 MR or 12 MR), preferably a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 oxygen atoms (10 MR), and even more preferably a catalyst comprising a ZSM-5 type zeolite.

[0069] The term WH corresponds to the volume of hourly hydrocarbon charge injected relative to the volume of catalyst charged.

[0070] According to one or more embodiments, the optional stabilization column 12 produces: at the bottom a stabilized cut comprising (eg essentially) benzene and toluene 44 optionally recycled at the inlet of the charge separation unit 1 and / or the aromatic extraction unit 3; and at the top a cut of volatile species 45 (eg C5-) removed from the aromatic complex.

[0071] According to one or more embodiments, the second hydrocarbon feedstock 30 is a mixture of hydrocarbon compounds having an elemental oxygen content greater than 1% by weight, preferably greater than 3% by weight, very preferably greater than 5% by weight relative to the total weight of said second hydrocarbon feedstock 30. According to one or more embodiments, the second hydrocarbon feedstock 30 comprises or consists of lignocellulosic biomass or one or more constituents of lignocellulosic biomass chosen from the group formed by cellulose, hemicellulose and lignin.

[0072] Lignocellulosic biomass can consist of wood, agricultural waste or plant waste. Other non-limiting examples of lignocellulosic biomass material are agricultural residues (straw, corn stalk, etc.), forestry residues (first thinning products), forestry products, dedicated crops (short rotation coppice), residues from the agri-food industry, household organic waste, waste from wood processing facilities, used construction wood, and paper, whether recycled or not.

[0073] Lignocellulosic biomass may also be derived from by-products of the paper industry such as Kraft lignin, or black liquors from the manufacture of paper pulp. Lignocellulosic biomass may advantageously undergo at least one pretreatment step before its introduction into the process according to the invention. Preferably, the biomass is ground and dried until the desired particle size is obtained. A feedstock having a particle diameter of between 0.3 mm and 0.5 mm may advantageously be obtained. Typically, the particle size of lignocellulosic biomass is a particle size sufficient to pass through a 1 mm sieve up to a particle size sufficient to pass through a 30 mm sieve.

[0074] According to one or more embodiments, when the second hydrocarbon feedstock 30 is solid (e.g. biomass type feedstock), the second hydrocarbon feedstock 30 is advantageously loaded into a pneumatic drive or transport compartment so as to be driven into a pyrolysis or oxycombustion reactor or a gasification furnace by a drive fluid. Preferably, the drive fluid used is nitrogen gas. However, it is also envisaged that other non-oxidizing drive fluids may be used. Preferably, synthesis gas produced during the process may be recycled and used as a drive fluid.Said synthesis gas consists mainly of a gaseous, non-condensable effluent comprising at least carbon monoxide (CO), carbon dioxide (CO2), optionally / preferably hydrogen (H2), and also advantageously comprising light olefins comprising from 2 to 4 carbon atoms. In this way, the costs of carrying out pyrolysis or oxycombustion or gasification can be considerably reduced. The second hydrocarbon feedstock 30 can be loaded into a feed hopper or other device which makes it possible to bring said feedstock into the drive compartment in an appropriate quantity. In this way, a constant quantity of feedstock is delivered into the drive compartment.

[0075] The drive fluid advantageously transports the second hydrocarbon feedstock 30 from the drive compartment into the pyrolysis or oxycombustion reactor or the gasification furnace through a feed tube.

[0076] Typically, the feed tube is cooled to maintain the temperature of the second hydrocarbon feedstock 30 at a required level prior to its entry into the pyrolysis or oxy-combustion reactor or the gasification furnace. The feed tube may be cooled by lining the tube, typically with an air-cooled or liquid-cooled jacket. However, it is also contemplated that the feed tube will not be cooled.

[0077] According to one or more embodiments, the pyrolysis unit 14 comprises at least one pyrolysis reactor (e.g. fluidized bed) suitable for use in at least one of the operating conditions listed below.

[0078] According to one or more embodiments, the pyrolysis step is carried out at a temperature between 400°C and 1000°C, preferably between 400°C and 650°C, preferably between 450°C and 600°C and preferably between 450°C and 590°C. In particular, the use of hot regenerated catalyst from a catalyst regeneration step can ensure reactor temperature ranges.

[0079] The pyrolysis step is also advantageously carried out at an absolute pressure of between 0.1 MPa and 0.5 MPa and at a WH of between 0.01 h -1 and 10 a.m. 1 , preferably between 0.01 h -1 and 5 a.m. -1 , and very preferably between 0.1 h -1 and 3 hours -1 . The WH is the ratio of the volume flow rate of charge to the volume of catalyst used.

[0080] According to one or more embodiments, the pyrolysis step is catalytic and carried out in the presence of a catalyst. Preferably, said step operates in the presence of a zeolite catalyst comprising and preferably consisting of at least one zeolite chosen from ZSM-5, ferrierite, Beta zeolite, Y zeolite, mordenite, ZSM-23, ZSM-57, EU-1, ZSM-11 and preferably the catalyst is a catalyst comprising only ZSM-5. The zeolite used in the catalyst used in the catalytic pyrolysis step can advantageously be doped preferably with a metal chosen from iron, gallium, zinc and lanthanum.

[0081] Under these conditions, the second hydrocarbon feedstock 30 will first undergo rapid pyrolysis in the reactor by contacting the hot catalyst from the regenerator which in this stage acts as a thermal vector. The gases resulting from this pyrolysis will then react on the catalyst which this time plays its role as a catalyst to catalyze the reactions producing the desired chemical intermediates.

[0082] In the pyrolysis unit 14, the second hydrocarbon feedstock 30 is in particular converted at least partially into a pyrolysis effluent 21 comprising hydrocarbon compounds whose carbon number ranges from 6 to 10 carbon atoms. The pyrolysis effluent 21 preferably feeds the first hydrocarbon feedstock 2 of the aromatic complex. The pyrolysis unit 14 also produces a synthesis gas 34 comprising CO, CO2 and optionally hydrogen, and by-products 33.

[0083] The products obtained at the end of the pyrolysis step are advantageously recovered in the form of a gaseous effluent comprising BTX.

[0084] Said gaseous effluent comprising the products obtained at the end of the pyrolysis step is then advantageously sent to a fractionation section so as to separate at least the following cuts: a gaseous fraction of incondensables, comprising at least CO and CO2; a liquid cut called BTX, comprising hydrocarbon compounds whose carbon number ranges from 6 to 10 carbon atoms; a liquid cut mainly comprising compounds having a number of carbon atoms greater than 9, i.e. at least 50% by weight of C9+ compounds; and water.

[0085] Said gaseous fraction of incondensables may also advantageously comprise light olefins comprising from 2 to 4 carbon atoms.

[0086] The coked catalyst as well as the second unconverted hydrocarbon feedstock usually called "char" are advantageously withdrawn from the reactor and preferably sent to a stripper so as to eliminate the potentially adsorbed hydrocarbons and thus avoid their combustion in the regenerator and this by contacting with at least one gas chosen from water vapor, an inert gas such as for example nitrogen, and a part of the gaseous fraction of incondensables resulting from the fractionation of the gaseous effluent resulting from the pyrolysis step.

[0087] Said coked catalyst and the second unconverted hydrocarbon feedstock, optionally stripped, are advantageously sent to a regenerator where coke and char are burned by adding air or oxygen, thus producing regenerated catalyst and a CO2-rich combustion gas.

[0088] According to one or more embodiments, the regenerated catalyst is advantageously recycled into the reactor of the pyrolysis stage in order to undergo another cycle.

[0089] Advantageously, the pyrolysis step of the process according to the invention allows the production of at least 10% by weight and preferably at least 15% by weight of aromatics relative to the total mass of the reaction products obtained, with a selectivity of at least 65% and preferably at least 70% in BTX.

[0090] The pyrolysis step also produces at least one BTX cut (pyrolysis effluent 21) and a gaseous fraction of incondensables (synthesis gas 34) comprising at least CO and CO2.

[0091] The process also makes it possible to obtain, in addition to the BTX cut, a heavier liquid fraction, mainly aromatic, called the “C9+ cut” which can advantageously be used in a process external to the process according to the invention.

[0092] Preferably, at least a portion of the gaseous fraction of incondensables is recycled, preferably via a compressor, into the reactor of the pyrolysis stage. This gaseous flow then serves as a fluid for carrying the charge in said reactor. In this case, a purge of said recycled gaseous effluent is preferably carried out, preferably either upstream or downstream of said compressor.

[0093] According to one or more embodiments, the pyrolysis effluent 21 is a hydrocarbon fraction containing predominantly (i.e., > 50% by weight) molecules whose carbon number ranges from 6 to 10 carbon atoms. The pyrolysis effluent 21 may also contain molecules having more than 10 carbon atoms and / or molecules with 5 carbon atoms. The pyrolysis effluent 21 is rich in aromatics (eg > 50% by weight) and preferably contains at least 20% by weight of benzene, preferably at least 30% by weight, very preferably at least 40% by weight of benzene, relative to the total weight of the pyrolysis effluent 21. According to one or more embodiments, the pyrolysis effluent 21 is treated to meet the required specifications of the first hydrocarbon feedstock 2 as described above in order to have contents of sulfur, nitrogen and oxygenated elements compatible with an aromatic complex.

[0094] According to one or more embodiments, the synthesis gas 34 (leaving the pyrolysis unit 14) comprises at least a portion of the gaseous fraction of incondensables and preferably comprises at least in part the combustion gas rich in CO2. According to one or more embodiments, the synthesis gas 34 produced by the pyrolysis unit 14 comprises a mixture containing predominantly (e.g. comprising at least 50% by weight) CO and CO2. According to one or more embodiments, the synthesis gas 34 comprises at least 20% by weight of CO, preferably at least 30% by weight of CO, very preferably at least 40% by weight of CO (e.g. at least 50% by weight of CO), relative to the total weight of the synthesis gas 34.According to one or more embodiments, the synthesis gas 34 comprises at least 0.2% by weight of hydrogen, preferably at least 0.5% by weight of hydrogen, very preferably at least 0.8% by weight of hydrogen, relative to the total weight of the synthesis gas 34. According to one or more embodiments, the synthesis gas 34 at the outlet of the pyrolysis unit 14 contains at least 20% by weight of CO2, relative to the total weight of the synthesis gas 34. According to one or more embodiments, the synthesis gas 34 at the outlet of the pyrolysis unit 14 contains approximately 30% (eg ± 10% by weight) by weight of CO2, relative to the total weight of the synthesis gas 34. According to one or more embodiments, the synthesis gas 34 contains methane, ethylene and propylene (eg less than 10% by weight) as well as ethane, propane and water. (eg less than 3% by weight).

[0095] According to one or more embodiments, the by-products 33 comprise the C9+ fraction mainly consisting of more or less alkylated di and tri aromatics. This cut can be used directly as bunker fuel, for example, or undergo hydrotreatment and / or hydrocracking to improve its properties and use it as Jet Fuel or diesel.

[0096] In the oxycombustion or gasification unit 15, the second feedstock 30 is converted into a synthesis gas comprising CO, CO2 and optionally water.

[0097] According to one or more embodiments, the oxycombustion unit 15 comprises at least one reactor used in at least one of the following operating conditions: a reactor operating in a fluidized bed; temperature between 500°C and 1000°C; pressure between 0.1 MPa and 3 MPa, preferably between 0.1 MPa and 1 MPa.

[0098] According to one or more embodiments, the oxycombustion step is carried out in the presence / by injection of a gas source comprising at least 80% by weight of oxygen, preferably at least 90% by weight of oxygen, very preferably at least 95% by weight of oxygen, relative to the total weight of the gas source. According to one or more embodiments, the gas source is a source of pure oxygen, such as a gas comprising at least 99% by weight of oxygen, preferably at least 99.5% by weight of oxygen relative to the total weight of the gas source. The control of the temperature of the hearth can be carried out by adjusting the O2 concentration at the reactor inlet. This adjustment of the O2 concentration can be done via the recycling of combustion fumes.

[0099] According to one or more embodiments, the gasification unit 15 comprises at least one gasification furnace used under at least one of the following operating conditions: temperature between 700°C and 1400°C.

[0100] According to one or more embodiments, the synthesis gas 34 (leaving the oxycombustion or gasification unit 15) comprises a mixture containing mainly (e.g. comprising at least 50% by weight) CO and CO2. According to one or more embodiments, the synthesis gas 34 comprises at least 70% by weight of CO2, preferably at least 75% by weight of CO2, relative to the total weight of the synthesis gas 34. According to one or more embodiments, the synthesis gas 34 comprises less than 4% by weight of CO, preferably less than 2% by weight of CO, relative to the total weight of the synthesis gas 34. According to one or more embodiments, the synthesis gas 34 comprises water, such as for example at least 18% by weight of water, preferably at least 20% by weight of water, relative to the total weight of the synthesis gas 34.

[0101] According to one or more embodiments, a hydrogen supply 35 supplied by a make-up line is added to the synthesis gas 34 so that the molar ratio H2 / (CO+CC>2) of the synthesis gas 34 at the inlet of the methanol synthesis reaction section 50 is between 3 and 10, preferably between 3 and 8, preferably between 3 and 7, preferably between 3 and 6, very preferably between 3 and 5. The make-up hydrogen can advantageously come from any process allowing the production of hydrogen, such as for example a steam reforming process or a catalytic reforming process, the electrolysis of water, the dehydrogenation of alkanes, and its hydrogen purity is most often between 75 and 99.9% volume. It is understood that the hydrogen supply 35 can be provided directly into the methanol synthesis reaction section 50 and then mixed with the synthesis gas 34.

[0102] In the methanol synthesis reaction section 50, the synthesis gas 34, preferably enriched with a hydrogen supply 35, is converted at least partially into methanol and water. The methanol synthesis reaction from CO2 and CO is well known to those skilled in the art (see for example: US5631302, US4238403, EP 3402 773, and Renewable Energy, 146 (2020), 1192-1203).

[0103] According to one or more embodiments, the methanol synthesis reaction section 50 comprises at least one reactor used under at least one of the following operating conditions: temperature between 200°C and 450°C, preferably between 220°C and 400°C, and more preferably still between 250°C and 350°C; pressure between 1 MPa and 12 MPa, preferably between 2 MPa and 10 MPa, and more preferably between 5 MPa and 10 MPa; H2 / COX (CO and CO2) molar ratio between 3 and 10, preferably between 3 and 7, very preferably between 3 and 5; space velocity of the gas at the reactor inlet between 0.2 g / g ca ta / h and 1 g / g ca your / h.

[0104] According to one or more embodiments, the reactor of the methanol synthesis reaction section 50 is adapted to operate in a fluid bed or fixed bed, preferably in a fixed bed.

[0105] According to one or more embodiments, the methanol synthesis reaction is carried out in the presence of a hydrogenation catalyst. According to one or more embodiments, said catalyst is a catalyst for the hydrogenation of CO2. According to one or more embodiments, the catalyst for the hydrogenation of CO2 comprises copper (e.g. in oxide form) and optionally at least one promoter chosen from the following elements: Zn, Zr, Si, Al, Ti, Cr, Ga, Ce (e.g. in oxide form), and optionally a support (e.g. a refractory oxide such as alumina). According to one or more embodiments, the catalyst for the hydrogenation of CO2 is of the CuO / ZnO / AhCh type. According to one or more embodiments, the catalyst for the hydrogenation of CO2 comprises 50-75% by weight of CuO, 15-35% by weight of ZnO and 5-20% of AI2O3, relative to the total weight of the catalyst.

[0106] According to one or more embodiments, the synthesis gas 34 can be purified before being introduced into the methanol synthesis reaction section 50. The purification of the synthesis gas aims to remove sulfur compounds, nitrogen compounds, halogens, heavy metals and transition metals. The main technologies for purifying synthesis gases are: adsorption, absorption, catalytic reactions.

[0107] The various purification methods are well known to those skilled in the art; reference may be made, for example, to: Oil & Gas Science and Technology - Rev. IFP Energies nouvelles, 68 (2013), No. 4; and to Applied Energy, 237 (2019), 227-240.

[0108] In the optional purification section 52, the methanol 51 is treated to separate water 53 and a recycle gas 54 comprising unconverted CO and / or unconverted CO2, and to produce purified methanol 55. The recycle gas 54 is preferably recycled to the inlet of the methanol synthesis reaction section 50. The water-methanol separation can be carried out by distillation. According to one or more embodiments, the purified methanol 55 comprises at least 99.1% by weight of methanol. According to one or more embodiments, the water 53 comprises at least 99.99% by weight of water. Water 53, a co-product of the methanol synthesis reaction, is purged and removed from the process or sent to an electrolyzer to produce hydrogen or used upstream of the pyrolysis unit 14 or the oxycombustion or gasification unit 15 for biomass pretreatment operations.

[0109] Advantageously, the combination of a methanol synthesis reaction section 50, followed by a toluene alkylation reaction section 13 makes it possible to produce additional aromatics from CO and CO2, products of the pyrolysis unit 14 or the oxycombustion or gasification unit 15.

[0110] In this application, the groups of chemical elements are given by default according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VI II B according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification; group VI B according to the CAS classification corresponds to the metals of column 6 according to the new IUPAC classification.

[0111] Examples

[0112] Example 1 of reference process

[0113] An example of a reference process for transforming a feedstock comprising a mixture of aromatic compounds from a lignocellulosic biomass conversion process based on catalytic pyrolysis conversion is used.

[0114] The reference process example is similar to the process shown in Figure 1. However, the reference process example does not implement the following units: pyrolysis unit 14; methanol synthesis reaction section 50; purification section 52; toluene alkylation reaction section 13; stabilization column 12.

[0115] In this reference process example, hydrocarbon feedstock 2 consists of pyrolysis effluent 21.

[0116] The flow rates of aromatic compounds from the pyrolysis effluent 21 to be treated, at the inlet of the aromatic complex, are as follows: benzene: 2.63 t / h; toluene: 5.64 t / h; ethyl benzene: 0.15 t / h; and xylenes: 3.56 t / h.

[0117] A total of 11.98 t / h of aromatic compounds.

[0118] In the reference process, all the toluene is converted by a disproportionation unit into benzene and xylenes. The xylenes from the feed and produced by disproportionation are isomerized into paraxylene, which is separated from the mixture of xylenes at thermodynamic equilibrium at the outlet of the isomerization unit, by means of an adsorption unit in LMS. This set of unit operations allows, in the best case (assuming a selectivity of 100% for each unit operation) to produce the following compounds: benzene: 5.02 t / h; paraxylene: 6.96 t / h; total aromatics: 11.98 t / h.

[0119] Example 2 of the process according to the invention

[0120] The example process according to the invention makes it possible both to increase the total quantity of aromatics produced for the same feed rate as in the reference process, and to increase the quantity of paraxylene.

[0121] The exemplary method according to the invention is similar to the method shown in Figure 1. However, the exemplary method according to the invention does not use the stabilization column 12.

[0122] Compared to the reference process flowsheet, the following units are added: pyrolysis unit 14; methanol synthesis reaction section 50; purification section 52; toluene alkylation reaction section 13 for alkylating toluene with methanol.

[0123] According to the example of the process according to the invention, and with the same second hydrocarbon feedstock 30 and the same unit operation yields as in the example of the reference process, the following performances are obtained in Table 1 compared to those of the reference process. Table 1

[0124] Table 1 shows that the implementation according to the invention makes it possible to produce 7% more aromatics and 20% more paraxylene. The invention also produces an excess of 83.8 t / h of methanol.

[0125] The invention therefore makes it possible to significantly increase the quantity of paraxylene produced and to benefit from co-production of methanol, a product also desired by industry.

Claims

Claims 1. A method for producing and converting a hydrocarbon feedstock, comprising the following steps: fractionating a first hydrocarbon feedstock (2) in a fractionation train (4-6) to extract at least one cut comprising benzene (22), one cut comprising toluene (23) and one cut comprising xylenes and ethylbenzene (24); separating the cut comprising xylenes and ethylbenzene (24) in a xylene separation unit (10) and producing an extract comprising paraxylene (39) and a raffinate (40) comprising orthoxylene, metaxylene and ethylbenzene; isomerizing the raffinate (40) in an isomerization unit (11) and producing an isomerate (42) enriched in paraxylene; sending the isomerate (42) enriched in paraxylene to the fractionation train (4-6); treating a second hydrocarbon feedstock (30) in a synthesis gas production unit (14;15) to produce a synthesis gas (34) comprising at least carbon monoxide and carbon dioxide; treating the synthesis gas (34) in a methanol synthesis reaction section; (50) to produce methanol (51); alkylating at least a portion of the cut comprising toluene (23) with methanol (51) in a toluene alkylation reaction section (13) and produce an alkylation effluent (32) comprising xylenes sent to the xylene separation unit (10).

2. A method according to claim 1, comprising treating methanol (51) in a purification section (52) to separate water (53) and produce purified methanol (55).

3. A method according to claim 2, comprising separating a recycle gas (54) comprising unconverted CO and / or unconverted CO2 in the purification section (52), and recycling said recycle gas (54) to the inlet of the methanol synthesis reaction section (50).

4. Method according to any one of the preceding claims, in which the synthesis gas production unit (14; 15) comprises a pyrolysis unit (14) adapted to produce at least one pyrolysis effluent (21) comprising hydrocarbon compounds of 6 to 10 carbon atoms at least partially feeding the first hydrocarbon feedstock (2).

5. A method according to any one of the preceding claims, comprising providing a supply of hydrogen (35) in the synthesis gas (34).

6. Method according to any one of the preceding claims, in which the synthesis gas production unit (14; 15) comprises: a pyrolysis unit (14) comprising at least one reactor used under at least one of the following operating conditions: absolute pressure between 0.1 MPa and 0.5 MPa and WH between 0.01 h'1 and 10 a.m. 1 , preferably between 0.01 h' 1 and 5 a.m. 1 , and very preferably between 0.1 h' 1 and 3 a.m. 1 , WH is the ratio of the volume flow rate of feed to the volume of catalyst used; temperature between 400°C and 1000°C, preferably between 400°C and 650°C, preferably between 450°C and 600°C and preferably between 450°C and 590°C; zeolitic catalyst comprising and preferably consisting of at least one zeolite chosen from ZSM-5, ferrierite, zeolite Beta, zeolite Y, mordenite, ZSM-23, ZSM-57, EU-1, ZSM-11 and preferably the catalyst is a catalyst comprising only ZSM-5; or an oxycombustion unit (15) comprising at least one reactor used in at least one of the following operating conditions: a reactor operating in a fluidized bed; temperature between 500°C and 1000°C; - pressure between 0.1 MPa and 3 MPa, preferably between 0.1 MPa and 1 MPa; or a gasification unit comprising at least one gasification furnace used under at least one of the following operating conditions: temperature between 700°C and 1400°C.

7. A method according to any one of the preceding claims, wherein the methanol synthesis reaction section (50) comprises at least one reactor used under at least one of the following operating conditions: temperature between 200°C and 450°C, preferably between 220°C and 400°C, and more preferably still between 250°C and 350°C; pressure between 1 MPa and 12 MPa, preferably between 2 MPa and 10 MPa, and more preferably between 5 MPa and 10 MPa; hydrogen to COx molar ratio in which COx represents CO and CO2, between 3 and 10, preferably between 3 and 7, very preferably between 3 and 5; gas space velocity at the reactor inlet between 0.2 g / g ca ta / h and 1 g / gcata / h.

8. A method according to any one of the preceding claims, wherein the toluene alkylation reaction section (13) comprises at least one alkylation reactor used under at least one of the following operating conditions: temperature between 20°C and 550°C; pressure between 1 MPa and 10 MPa; toluene / methanol molar ratio between 1 and 5; PPH between 0.5 h -1 and 50 h -1 ; presence of a catalyst comprising a zeolite.

9. A method according to any one of the preceding claims, wherein the isomerization unit (11) comprises a gas-phase isomerization zone used under at least one of the following operating conditions: temperature above 300°C; pressure below 4.0 MPa; hourly space velocity below 10 h' 1; hydrogen to hydrocarbon molar ratio less than 10; presence of a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 or 12 oxygen atoms, and at least one metal from group VI 11 B with a content of between 0.1 and 0.3% by weight, limits included.

10. A method according to any one of the preceding claims, wherein the isomerization unit (11) comprises a liquid phase isomerization zone used under at least one of the following operating conditions: temperature less than 300 C; pressure less than 4 MPa; hourly space velocity less than 10 h' 1 ; presence of a catalyst comprising at least one zeolite having channels whose opening is defined by a ring with 10 or 12 oxygen atoms. 11 Device for producing and converting a hydrocarbon feedstock, comprising: a fractionation train (4-6) adapted to extract at least one cut comprising benzene (22), a cut comprising toluene (23) and a cut comprising xylenes and ethylbenzene (24) from a first hydrocarbon feedstock (2); a xylene separation unit (10) adapted to treat the cut comprising xylenes and ethylbenzene (24) and produce an extract comprising paraxylene (39) and a raffinate (40) comprising orthoxylene, metaxylene and ethylbenzene; an isomerization unit (11) adapted to treat the raffinate (40) and produce an isomerate (42) enriched in paraxylene sent to the fractionation train (4-6); a synthesis gas production unit (14; 15) adapted to treat a second hydrocarbon feedstock (30) and produce a synthesis gas (34) comprising at least carbon monoxide and carbon dioxide; a methanol synthesis reaction section (50) adapted to treat the synthesis gas (34) and produce methanol (51); a toluene alkylation reaction section (13) adapted to treat at least a portion of the cut comprising toluene (23) with the methanol (51) and produce an alkylation effluent (32) comprising xylenes sent to the xylene separation unit (10).

12. Apparatus according to claim 11, wherein the toluene alkylation reaction section (13) is adapted to separate xylenes from a water-containing cut (31) to produce the alkylation effluent (32).

13. Device according to claim 11 or claim 12, further comprising a charge separation unit (1) for separating the charge (2) into a hydrocarbon cut with 7 carbon atoms or less (16) sent to the benzene column (4) of the fractionation train (4-6), and an aromatic cut with 8 carbon atoms or more (17) sent to the xylenes column (6) of the fractionation train (4-6).

14. Device according to claim 13, further comprising an aromatic extraction unit (3) between the charge separation unit (1) and the benzene column (4) for separating the aliphatic compounds (19) from the aromatic cut with 7 carbon atoms or less (16) and producing an extract (20) sent to the benzene column (4).

15. Conversion device according to any one of claims 11 to 14, further comprising a stabilization column (12) adapted to remove a cut of volatile species (45) from the effluents of the isomerization unit (11).

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