FR3112774A1 - Device and method for producing aromatics by biomass pyrolysis and reverse water gas conversion. - Google Patents

Abstract

Apparatus and method for the conversion of aromatic compounds, comprising/using: a fractionation train (4-7); a xylene separation unit; an isomerization unit (11); a pyrolysis unit (13) for processing biomass (30) and producing pyrolysis effluent (31) sent to the fractionation train, and producing pyrolysis gas (32); a reverse water gas conversion (RWGS) reaction section (50) for treating the pyrolysis gas (32) and producing an RWGS gas (51); a separation unit (52) for separating water and unconverted CO2 from the RWGS gas (51) and producing a separation gas (53); a Fischer-Tropsch synthesis reaction section (14) for at least partially treating the separation gas (53), producing a synthesis effluent (35) sent at least partially to the pyrolysis unit (13). Figure 1 to be published

Description

Device and process for the production of aromatics by biomass pyrolysis and reverse water gas conversion.

The invention relates to the production of aromatics for the petrochemical industry (benzene, toluene, paraxylene, orthoxylene). More particularly, the object of the invention is to be able to increase the production of aromatics produced by a biomass pyrolysis process. By converting all of the CO and the CO2 by-product of biomass pyrolysis, all of the biosourced carbon can be recovered.

The aromatic complex (or device for converting aromatic compounds) is supplied with fillers mainly composed of six to ten or more carbon atoms denoted C6 to C10+ fillers. Different sources of aromatic compounds can be introduced into an aromatic complex, the most widespread being the catalytic reforming process of naphthas. Mixtures of aromatic compounds obtained by conversion process of lignocellulosic biomass can also, after purification treatment, be introduced into an aromatic complex. For example, the catalytic pyrolysis process of lignocellulosic biomass can be considered as a source of aromatics.

Within an aromatic complex, whatever the source of aromatics, benzene and aromatic alkyls (e.g. toluene, paraxylene, orthoxylene) are extracted and then converted into the 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.

To date, aromatic complexes make it possible to produce benzene, possibly toluene, and xylenes (often paraxylene, sometimes orthoxylene). An aromatic complex generally has at least one catalytic unit having at least one of the following functions:
- the isomerization of aromatic compounds with 8 carbon atoms, denoted A8 compounds, making it possible 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 makes it possible to produce benzene and xylenes.

The aromatic loop makes it possible to produce high purity paraxylene by separation by adsorption or by crystallization, an operation well known in the prior art. This "C8-aromatic loop" includes a step for removing heavy compounds (i.e., C9+) in a distillation column called the "xylene column". The overhead from this column, which contains the C8-aromatic isomers (i.e., A8), is then sent to the paraxylene separation process which is very generally a simulated moving bed adsorption (LMS) separation process to producing an extract and a raffinate, or a crystallization process in which a fraction of paraxylene is isolated from the rest of the constituents of the mixture in the form of crystals.

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 a mixture of C8 aromatics, in which the proportion of xylenes (ortho-, meta-, para-xylenes) is practically at thermodynamic equilibrium and the amount of ethylbenzene is reduced. This mixture is again sent to the “xylene column” with the fresh feed.

All industrial processes for the isomerization of C8-aromatics make it possible to isomerize xylenes. The transformation of ethylbenzene depends, on the other hand, on the type of process and catalyst chosen. Indeed, petrochemical complexes use an isomerization unit called "isomerizing" (i.e., isomerization of ethylbenzene into a mixture of C8 aromatics) or "dealkylating" (i.e., dealkylation of ethylbenzene into benzene), in order to favor the production (at the exit of the aromatic loop) respectively either of paraxylene alone, or of benzene and paraxylene.

The choice of an “isomerizing” isomerization makes it possible, as indicated above, to maximize the production of paraxylene, which is the compound with the highest added value at the output of the aromatic complex. The combination within an aromatic complex of an “isomerizing” isomerization and of an isomerization in the liquid phase as described for example in the patents US8697929, US7371913, US4962258, US6180550, US7915471, US10035739 and US10029958 makes it possible in particular to maximize the amount of paraxylene produced while having a reduced loss of aromatic rings compared to an aromatic complex according to the prior art.

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 device and a process for the production of aromatics for the petrochemical industry allowing, when the aromatic compounds are produced by pyrolysis of biomass, to convert CO and CO2, by-products of the pyrolysis section, into paraffins and additional aromatic compounds.

The invention is based on the conversion of carbon monoxide, i.e., CO, and carbon dioxide, i.e., CO2, into paraffins and aromatic compounds which are introduced into the aromatic complex, and on the arrangement of one or more units for converting CO and CO2 into a mixture of liquid hydrocarbons mainly consisting of olefins, this hydrocarbon mixture being recycled to the biomass pyrolysis section to be converted therein in particular into aromatic compounds. Specifically, the object of the present invention can be summarized as adding a reverse water gas conversion unit (or RWGS or "Reverse Water Gas Shift" according to the English terminology) to at least partially convert the CO2 into CO and thus obtain a CO+H2 synthesis gas, and a Fischer-Tropsch catalytic unit, preferably operated at high temperature and/or in the presence of an iron catalyst, this catalytic unit making it possible to convert the CO+ synthesis gas H2 into a liquid hydrocarbon mixture. At least part and preferably all of the effluent leaving the Fischer-Tropsch reaction zone is recycled to the inlet of the biomass pyrolysis section.

According to a first aspect, the aforementioned objects, as well as other advantages, are obtained by a device for converting a charge of aromatic compounds, comprising:
- a fractionation train adapted to extract at least one cut comprising benzene, one cut comprising toluene and one cut comprising xylenes and ethylbenzene from the feed;
- a xylene separation unit suitable for treating the cut comprising xylenes and ethylbenzene and producing an extract comprising paraxylene and a raffinate (40) 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 pyrolysis unit suitable for treating biomass, producing at least one pyrolysis effluent comprising hydrocarbon compounds with 6 to 10 carbon atoms supplying at least partially the charge, and producing a pyrolysis gas comprising at least CO, CO2 and H2;
- an RWGS reaction section adapted to treat the pyrolysis gas and produce an RWGS gas enriched in CO and water;
- a separation unit suitable for separating water and unconverted CO2 from the RWGS gas and producing a CO-enriched separation gas;
- a Fischer-Tropsch synthesis reaction section adapted to at least partially treat the separation gas, produce a synthesis effluent comprising hydrocarbon compounds with 3 to 22 carbon atoms, and send the synthesis effluent at least partially to the pyrolysis unit.

According to one or more embodiments, the device further comprises a first make-up line to provide an H2 supply in the pyrolysis gas.

According to one or more embodiments, the device further comprises a second make-up line to provide an H2 supply in the separation gas.

According to one or more embodiments, the fractionation train is suitable for extracting a cut of C9-C10 mono-aromatics from the feed.

According to one or more embodiments, the device further comprises a transalkylation unit suitable for treating the C9-C10 mono-aromatic cut with the cut comprising toluene and producing xylenes sent to the fractionation train.

According to one or more embodiments, the device further comprises a selective hydrogenolysis unit is suitable for:
- treat the cut of mono-aromatics in C9-C10; And
- produce a hydrogenolysis effluent enriched in methyl-substituted aromatic compounds sent to the transalkylation unit.

According to one or more embodiments, the Fischer-Tropsch synthesis reaction section is adapted to recycle the synthesis effluent in its entirety in the pyrolysis unit.

According to a second aspect, the aforementioned objects, as well as other advantages, are obtained by a process for converting a charge of aromatic compounds, comprising the following steps:
- fractionating the feed 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;
- Isomerize the raffinate in an isomerization unit and produce an isomerate enriched in paraxylene;
- sending the paraxylene-enriched isomerate to the fractionation train;
- treating biomass in a pyrolysis unit to produce at least one pyrolysis effluent comprising hydrocarbon compounds of 6 to 10 carbon atoms supplying at least partially the charge and producing a pyrolysis gas comprising at least CO, CO2 and H2;
- treating the pyrolysis gas in a reaction section of RWGS to produce an RWGS gas enriched in CO and water;
- separating water and unconverted CO2 from the RWGS gas in a separation unit to produce a CO-enriched stripping gas;
- treating at least part of the separation gas in a Fischer-Tropsch synthesis reaction section to produce a synthesis effluent comprising hydrocarbon compounds with 3 to 22 carbon atoms; And
- send the synthesis effluent at least in part to the pyrolysis unit.

According to one or more embodiments, the pyrolysis unit comprises at least one reactor used under the following operating conditions:
- presence of a catalyst, preferably a zeolite catalyst, preferably a zeolite catalyst comprising at least one zeolite chosen from ZSM-5, ferrierite, Beta zeolite, Y zeolite, mordenite, ZSM-23, ZSM- 57, EU-1, ZSM-11, preferably a catalyst comprising only a ZSM-5 type zeolite; the zeolite used in the catalyst can advantageously be doped with a metal chosen from iron, gallium, zinc and lanthanum;
- a temperature between 400 and 1000°C, preferably between 400 and 650°C, more preferably between 450 and 600°C and very preferably between 450 and 590°C;
- an absolute pressure of between 0.1 and 0.5 MPa;
- a VVH of between 0.01 and 10 h ^-1 , preferably between 0.01 and 5 h ^-1 , preferably between 0.1 and 3 h ^-1 and very preferably between 0.1 and 3 h ^-1 (The VVH is the ratio of the volume flow rate of charge to the volume of catalyst used).

According to one or more embodiments, the Fischer-Tropsch synthesis reaction section is used under the following operating conditions:
- temperature between 250°C and 400°C, preferably between 300°C and 350°C, and very preferably still between 300°C and 340°C;
- pressure between 1 and 5 MPa, preferably between 1.5 and 4 MPa, and very preferably between 2 and 3 MPa (eg at 2.5 MPa ±2);
- Catalyst comprising iron as the active phase;
- volume flow rate of the synthesis effluent of between 0.2 and 3 L/g _cat /h, and preferably between 0.5 and 1.5 L/g _cat /h.

According to one or more embodiments, the isomerization unit comprises a gas phase isomerization zone and/or a liquid phase isomerization zone, in which the gas phase isomerization zone is used under the conditions following operations:
- temperature above 300°C;
- pressure less than 4.0 MPa;
- hourly space velocity less than 10 h ^-1 ;
- hydrogen to hydrocarbon molar ratio less than 10;
- 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, and at least one group VIII metal with a content between 0.1 and 0 .3% by weight, limits included, relative to the total weight of the catalyst, and
wherein the liquid phase isomerization zone is used under the following operating conditions:
- temperature below 300 C;
- pressure less than 4 MPa;
- hourly space velocity less than 10 h ^-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.

According to one or more embodiments, the transalkylation unit comprises at least one first transalkylation reactor used under the following operating conditions:
- temperature between 200°C and 600°C;
- pressure between 2 and 10 MPa;
- PPH between 0.5 and 5 h ^-1 .

According to one or more embodiments, the method further comprises providing an H2 supply in the pyrolysis gas by means of a first make-up line.

According to one or more embodiments, the method further comprises providing an H2 supply in the separation gas by means of a second make-up line.

According to one or more embodiments, the method further comprises the synthesis effluent is recycled in its entirety in the pyrolysis unit.

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

figure

FIG. 1 represents a schematic view of a process according to the present invention making it possible to increase the production of aromatic compounds.

Embodiments of the device according to the first aspect and of the method according to the second aspect will now be described in detail. In the following detailed description, many specific details are exposed in order to provide a more in-depth understanding of the device. However, it will be apparent to those skilled in the art that the device can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

In this application, the term "include" is synonymous with (means the same as) "include" and "contain", and is inclusive or open ended and does not exclude other unrecited material. It is understood that the term “include” includes the exclusive and closed term “consist”. In addition, in the present description, an effluent comprising essentially or only 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.

The present invention can be defined as a device and a process comprising a sequence of unit operations making it possible to produce aromatic compounds such as paraxylene and benzene.

The device and the process according to the invention are characterized in that they comprise and use 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.

One of the characteristics of the present invention consists in the use of CO, a by-product of a biomass pyrolysis unit, to increase the production of aromatic compounds.

Surprisingly, the combination of a reaction section for converting CO2 into CO by reaction of RWGS and a reaction section for converting a mixture comprising CO and H2 leaving the reaction section of RWGS in a Fischer-Tropsch unit and the recycling of all of the effluent from said reaction section at the inlet of the pyrolysis unit makes it possible to significantly increase the quantity of aromatics produced by pyrolysis of the biomass. Thus the CO2 produced during the Fischer-Tropsch synthesis is again converted into CO and recycled to the Fischer-Tropsch synthesis unit, it is therefore possible to convert all of the CO2.

Referring to Figure 1, according to one or more embodiments, the device for converting aromatic compounds comprises:
- an optional charge separation unit 1 to separate an input charge 2 of 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 aromatics extraction unit 3 between the charge separation unit 1 and a fractionation train 4-7 to separate the aliphatic compounds of benzene and toluene from the C7- cut of the charge of the complex;
- the fractionation train 4-7 downstream of the optional aromatics extraction unit 3 making it possible to extract benzene, toluene and xylenes from the other aromatics;
- an optional transalkylation unit 8 converting toluene (and optionally benzene) and methylalkylbenzenes such as trimethylbenzenes into xylenes - advantageously this unit can also process tetramethylbenzenes;
- an optional selective hydrogenolysis unit 9 suitable for treating a cut comprising aromatic compounds with 9 and 10 carbon atoms and producing a hydrogenolysis effluent enriched in methyl-substituted aromatic compounds;
- an optional separation unit (not shown) for separating the hydrogenolysis effluent disposed (eg directly) downstream of the selective hydrogenolysis unit 9, to produce a plurality of liquid effluent cuts;
a xylene separation unit 10 (eg of the crystallization or simulated moving bed type using a molecular sieve and a desorbent such as toluene) making it possible to isolate the paraxylene from the xylenes and from the ethylbenzene;
- a unit 11 for isomerization of the raffinate obtained as effluent from the xylene separation unit 10 in order to convert in particular orthoxylene, metaxylene and ethylbenzene into paraxylene;
- an optional stabilization column 12, making it possible in particular to remove the more volatile species (eg C5-) from the aromatic complex, in particular from the effluents from the transalkylation unit 8 and/or from the isomerization unit 11;
- a pyrolysis unit 13, preferably catalytic, for treating biomass 30, producing at least one pyrolysis effluent 31 supplying at least partially the input charge 2 of the aromatic complex, a pyrolysis gas 32 comprising at least CO, CO2 and H2, and a line of middle distillates 33 which, after an optional hydrotreating and/or hydrocracking step, can be upgraded in the form of jet fuel, diesel or marine fuel;
- a first optional extra line 34 to provide an H2 supply and adjust the H2/CO ratio of the pyrolysis gas 32;
- an RWGS reaction section 50 for treating the pyrolysis gas 32 coming from the pyrolysis unit 13, and producing an RWGS 51 gas enriched in CO and water (and thus depleted in CO2 and H2);
- a separation unit 52, for treating the RWGS gas 51 in order to separate water and unconverted CO2 and produce a separation gas 53 enriched in CO (and thus depleted in CO2, H2 and water), the unconverted CO2 54 being optionally recycled to the inlet of the RWGS reaction section 50, the separated water 55 being purged out of the aromatic complex;
- a second optional extra line 56 to provide an H2 supply and adjust the H2/CO ratio of the CO-enriched gas 53;
- an optional hydrotreatment unit (not shown) adapted to hydrotreat the pyrolysis effluent 31, being preferably adapted to reduce the content of oxygenated compounds in the pyrolysis effluent 31, and being preferably arranged upstream of the optional unit load separation 1, such as upstream of the input load line 2; And
- a Fischer-Tropsch synthesis reaction section 14 for converting the separation gas 53 and sending at least part of the synthesis effluent 35 to the pyrolysis unit 13;

With reference to figure 1, the charge separation unit 1 processes the input charge 2 of the aromatic complex to separate a head cut comprising (e.g. essentially) compounds with 7 or less carbon atoms 16 (C7-) containing in particular benzene and toluene, and a bottoms cut comprising (e.g. essentially) aromatics with 8 or more carbon atoms 17 (A8+) sent to the xylene column 6. According to one or more embodiments, the unit 1 also separates a first cut of toluene 18 comprising at least 90% by weight, preferably at least 95% by weight, very preferably at least 99% by weight of toluene relative to the total weight of the first cut of toluene 18. According to one or more embodiments, the first toluene cut 18 is sent to the first aromatic compounds distillation column 4, also called benzene column, and/or to the second aromatic compounds distillation column 5, also called toluene column.

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

The input charge 2 of the aromatic complex is rich in aromatics (e.g. > 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 with respect to the total weight of Input Feed 2. Input Feed 2 may be produced by catalytic reforming of a naphtha or be a product of a cracking unit (e.g. steam, catalytic) or any other means of producing naphtha. aromatic alkyls.

According to one or more embodiments, the input load 2 is at least partly biobased. According to one or more embodiments, the input charge 2 comes at least in part from a lignocellulosic biomass conversion process. For example, an effluent produced by conversion of lignocellulosic biomass can be treated to meet the specifications required for input load 2 as described above in order to present contents of sulphurous, nitrogenous and oxygenated elements compatible with an aromatic complex. . According to one or more embodiments, the input charge 2 comprises less than 10 ppmw, preferably less than 5 ppmw, very preferably less than 1 ppmw of elemental nitrogen, and/or less than 10 ppmw, preferably less 5 ppmw, very preferably less than 1 ppmw elemental sulfur, and/or less than 100 ppmw, preferably less than 50 ppmw, most preferably less than 10 ppmw elemental oxygen.

The overhead cut 16 from the charge separation unit 1, optionally mixed with the bottoms product 44 (benzene and toluene) from the stabilization column 12 which will be defined below, is sent to the extraction unit of the aromatics 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 fraction 20 (essentially benzene and toluene) called the extract from the aromatics extraction unit 3, optionally mixed with the heavy fraction 21 from the transalkylation unit 8 which will be defined below, is sent to the benzene column 4. According to one or more embodiments, the aromatic cut 20 is a C6-C7 (A6-A7) (e.g. essentially) aromatic hydrocarbon-based feedstock.

According to one or more embodiments, the fractionation train comprises the aromatic compound distillation columns 4, 5, 6 and 7 making it possible to separate the following 5 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 25;
- a cut comprising (eg essentially) aromatic compounds, the most volatile species of which are aromatics with 10 carbon atoms 26.

The benzene column 4 is suitable for: treating the aromatic cut 20 which is an (e.g. essentially) aromatic C6-C10 (A6+) hydrocarbon feedstock; produce at the head the cut comprising benzene 22 which may be one of the desired products at the output of the aromatic complex; and producing an (e.g. essentially) aromatic C7-C10 27 (A7+) effluent in the bottom.

The toluene column 5 is suitable for: treating the aromatic C7-C10 27 (A7+) effluent, the bottom product of the benzene column 4; produce at the head the cut comprising toluene 23 which is sent to the transalkylation unit 8; and producing an (e.g. essentially) aromatic C8-C10 28 (A8+) effluent in the bottom.

The third distillation column for aromatic compounds 6, also called a xylene column, is suitable for: treating the aromatic cut with 8 or more carbon atoms 17 (A8+) of the aromatic complex charge and optionally the bottom effluent from the column toluene 28; produce at the head the cut comprising xylenes and ethylbenzene 24 which is sent to the xylene separation unit 10; and producing an effluent in the bottom (e.g. essentially) comprising C9-C10 aromatics 29 (A9+).

The fourth distillation column for aromatic compounds 7, also called the heavy aromatics column, is optional and is suitable for: treating the bottom effluent from the xylene column 29; produce at the top the fraction comprising C9-C10 mono-aromatics; and producing at the bottom the cut comprising (e.g. essentially) aromatic compounds, the most volatile species of which are aromatics with 10 carbon atoms 26 (A10+). Preferably, the bottom section 26 comprises C11+ compounds.

In the transalkylation unit 8, the fraction comprising C9-C10 mono-aromatics 25 (and/or the hydrogenolysis effluent enriched in methyl-substituted aromatic compounds described below) is mixed with the cut comprising toluene 23 coming from the head of the toluene column 5, and feeds the reaction section of the transalkylation unit 8 to produce xylenes by transalkylation of aromatics lacking methyl groups (toluene), and in excess of methyl groups ( e.g. tri- and tetra-methylbenzenes). According to one or more embodiments, the transalkylation unit 8 is supplied with benzene (line not shown in Figure 1), for example when an excess of methyl groups is observed for the production of paraxylene. According to one or more embodiments, the transalkylation unit 8 directly treats the bottoms effluent from the xylene column 29.

According to one or more embodiments, the transalkylation unit 8 comprises at least one first transalkylation reactor adapted to be used under at least one of the following operating conditions:
- temperature between 200°C and 600°C, preferably between 350°C and 550°C, and even more preferably between 380°C and 500°C;
- pressure between 2 and 10 MPa, preferably between 2 and 6 MPa, and more preferably between 2 and 4 MPa;
- PPH (ratio of the feed rate to the weight of catalyst) between 0.5 and 5 h ^-1 , preferably between 1 and 4 h ^-1 , and more preferably between 2 and 3 h ^-1 .

According to one or more embodiments, the first transalkylation reactor is operated in the presence of a catalyst comprising zeolite, for example ZSM-5. According to one or more embodiments, the second transalkylation reactor is of the fixed bed type.

According to one or more embodiments, the effluents from the reaction section of the transalkylation unit 8 are separated in a first separation column (not shown) downstream of said reaction section of the transalkylation unit 8. A cut comprising at least part of the benzene and the more volatile species 38 (C6-) is extracted at the top of the first separation column and is sent to an optional stabilization column 12, allowing in particular to remove the more volatile species (e.g. C5-) of the aromatic complex. The heavy fraction of the effluents from the first separation column comprising (e.g. mainly) aromatics with at least 7 carbon atoms 21 (A7+), is optionally recycled to fractionation train 4-7, for example to benzene column 4.

The cut comprising xylenes and ethylbenzene 24 is treated in the xylene separation unit 10 to produce a fraction or an extract 39 comprising paraxylene and a raffinate 40. The extract 39 can then be distilled (e.g. if separation by LMS adsorption), 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. mainly) orthoxylene, metaxylene and ethylbenzene and feeds the isomerization unit 11.

According to one or more embodiments, the xylene separation unit 10 also separates a second toluene cut 41 comprising at least 90% by weight, preferably at least 95% by weight, very preferably at least 99% by weight of toluene relative to the total weight of the second toluene cut 41. The toluene cut 41 may for example be part of the toluene used as a desorbent when the xylene separation unit 10 comprises a so-called simulated moving bed adsorption unit. According to one or more embodiments, the second toluene cut 41 is sent to the transalkylation unit 8.

In the isomerization reaction section (not shown) of the isomerization unit 11, the paraxylene isomers are isomerized whereas 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 produce at the top a hydrocarbon cut comprising compounds with 7 carbon atoms or less 43 (C7-) sent to the optional stabilization column 12, for example with the cut comprising at least a part of the benzene and the more volatile species 38.

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, as described in the previously listed patents . 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 part of the raffinate 40 is sent to the liquid phase isomerization unit, to obtain a first isomerate which directly and at least partially feeds the separation unit 10, and it is sent to the gas phase isomerization unit a second part of the raffinate 40 to obtain an isomerate which is sent to the xylene column 6.

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 less than 4.0 MPa, and preferably from 0.5 to 2.0 MPa;
- hourly space velocity of less than 10 h ^-1 (10 liters per liter and per hour), preferably between 0.5 h ^-1 and 6 h ^-1 ;
- hydrogen to hydrocarbon molar ratio of less than 10, and preferably between 3 and 6;
- 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), and at least one group VIII metal with a between 0.1 and 0.3% by weight (reduced form), limits included, relative to the total weight of the catalyst.

According to one or more embodiments, the liquid phase isomerization zone is suitable for use under at least one of the following operating conditions:
- temperature below 300°C, preferably 200°C to 260°C;
- pressure less than 4 MPa, preferably 2 to 3 MPa;
- hourly space velocity (HSV) less than 10 h ^-1 (10 liters per liter and per hour), preferably between 2 and 4 h ^-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.

The term VVH corresponds to the volume of hourly hydrocarbon charge injected relative to the volume of catalyst charged.

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

According to one or more embodiments, the selective hydrogenolysis unit 9 is suitable for:
- treat mono-aromatics having between 9 and 10 carbon atoms 25; And
- produce a hydrogenolysis effluent enriched in methyl-substituted aromatic compounds 46.

Specifically, the selective hydrogenolysis unit 9 can be adapted to treat aromatics having between 9 and 10 carbon atoms 25 by converting one or more alkyl group(s) with at least two carbon atoms (ethyl groups, propyl, butyl, isopropyl, etc.) attached to a benzene ring, in one or more methyl group(s), i.e. formed from a single CH ₃ group . The major advantage of the selective hydrogenolysis unit 9 is to increase the content of CH ₃ groups and lower the content of ethyl, propyl, butyl, isopropyl, etc., groups in the charge of the isomerization unit 11 to increase the rate of production of xylenes, and in particular of paraxylene, in said isomerization unit 11.

According to one or more embodiments, the selective hydrogenolysis unit 9 comprises at least one hydrogenolysis reactor adapted to be used under at least one of the following operating conditions:
- temperature between 300°C and 550°C, preferably between 350°C and 500°C, and even more preferably between 370°C and 450°;
- pressure between 0.1 and 3 MPa, preferably between 0.2 and 2 MPa, and more preferably between 0.2 and 1 MPa;
- H ₂ /HC (hydrocarbon feed) molar ratio of between 1 and 10, and preferably between 1.5 and 6;
- PPH between 0.1 and 50 h ^-1 (eg 0.5-50 h ^-1 ), preferably between 0.5 and 30 h ^-1 (eg 1-30 h ^-1 ), and more preferably between 1 and 8:00 ^p.m. (eg 2:00 p.m. ^-8 :00 p.m., 5:00 ^p.m.- 8:00 p.m.).

According to one or more embodiments, the hydrogenolysis reactor is operated in the presence of a catalyst comprising at least one metal from group VIII of the periodic table, preferably nickel and/or cobalt, deposited on a porous support comprising at least one refractory oxide, crystalline or not, with structured porosity or not. In one or more embodiments, the Group VIII metal is nickel. The presence of a promoter (Group VIB, VIIB, VIII, IB, IIB) is also possible. The catalyst is supported on a refractory oxide (e.g. alumina, silica), optionally treated with a base to neutralize it.

According to one or more embodiments, the hydrogenolysis reactor is of the fixed bed type, and the catalyst support is in the form of extrudates. According to one or more embodiments, the hydrogenolysis reactor is of the moving bed type, and the catalyst support is in the form of approximately spherical beads. A moving bed can be defined as being a bed with gravity flow, such as those encountered in the catalytic reforming of gasolines.

In the pyrolysis unit 13, the biomass 30 is in particular converted at least partially into a pyrolysis effluent 31 comprising hydrocarbon compounds whose carbon number ranges from 6 to 10 carbon atoms. The pyrolysis effluent 31 feeds the input charge 2 of the aromatic complex. The pyrolysis unit 13 also produces a pyrolysis gas 32 comprising CO and H2, and a line of middle distillates 33.

According to one or more embodiments, the pyrolysis effluent 31 feeds the optional hydrotreatment unit before feeding the input feed 2 of the aromatic complex. Advantageously, the optional hydrotreatment unit makes it possible to reduce the content of oxygenated compounds of the pyrolysis effluent 31 to the specifications required by the input charge 2 of the aromatic complex.

According to one or more embodiments, the biomass is lignocellulosic biomass or one or more lignocellulosic biomass constituents selected from the group consisting of cellulose, hemicellulose and/or lignin. According to one or more embodiments, the lignocellulosic biomass comprises at least the following compounds: wood, agricultural waste, plant waste, agricultural residues (straw, corn stalk, etc.), residues of logging (products from first thinning), logging products, dedicated crops (short rotation coppice), residues from the agro-food industry, household organic waste, waste from wood processing facilities, used construction wood, recycled or non-recycled paper, by-products from the paper industry (Kraft lignin, black liquors from the manufacture of paper pulp, etc.).

According to one or more embodiments, the biomass is sent to at least one pretreatment unit (not shown) before its introduction into the pyrolysis unit 13. Preferably, the biomass is ground and dried, until a target particle size is obtained. A filler having a particle diameter of between 0.3 and 0.5 mm can advantageously be obtained. Typically, the particle size of the lignocellulosic biomass to be pyrolyzed 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.

According to one or more embodiments, the optionally pretreated biomass is loaded into a drive compartment or pneumatic transport so as to be driven into the pyrolysis unit 13 by a drive fluid. Preferably, the drive fluid used is nitrogen gas. However, it is also contemplated that other non-oxidizing drive fluids may be used. Preferably, the pyrolysis gas 32 produced during the process can be partially recycled and used as drive fluid. In this way, the cost of carrying out pyrolysis can be considerably reduced. Biomass can be loaded into a feed hopper or other device that allows biomass to be fed into the entrainment compartment in an appropriate amount. In this way, a constant amount of biomass is delivered to the entrainment compartment.

According to one or more embodiments, the entrainment fluid advantageously transports the biomass from the entrainment compartment into the pyrolysis unit 13 through a feed tube. Preferably, the feed tube is cooled to maintain the temperature of the biomass at a required level before it enters the pyrolysis unit 13. The feed tube can be cooled by jacketing the tube, typically with a jacket cooled by air or liquid cooled. However, it is also contemplated that the feed tube is not cooled.

According to one or more embodiments, the pyrolysis unit 13 comprises at least one pyrolysis reactor adapted to operate in a fluid bed or a fixed bed. According to one or more embodiments, the pyrolysis unit 13 comprises at least one pyrolysis reactor adapted to operate in a fluid bed. According to one or more embodiments, the pyrolysis unit 13 comprises at least one pyrolysis reactor adapted to operate in a fluid bed. According to one or more embodiments, the pyrolysis reactor is suitable for use under at least one of the following operating conditions:
- presence of a catalyst, preferably a zeolite catalyst, preferably a zeolite catalyst comprising at least one zeolite chosen from ZSM-5, ferrierite, Beta zeolite, Y zeolite, mordenite, ZSM-23, ZSM- 57, EU-1, ZSM-11, preferably a catalyst comprising only a ZSM-5 type zeolite; the zeolite used in the catalyst can advantageously be doped with a metal chosen from iron, gallium, zinc and lanthanum;
- a temperature between 400 and 1000°C, preferably between 400 and 650°C, more preferably between 450 and 600°C and very preferably between 450 and 590°C;
- an absolute pressure of between 0.1 and 0.5 MPa;
- a VVH of between 0.01 and 10 h ^-1 , preferably between 0.01 and 5 h ^-1 , preferably between 0.1 and 3 h ^-1 and very preferably between 0.1 and 3 h ^-1 (The VVH is the ratio of the volume flow rate of charge to the volume of catalyst used).

According to one or more embodiments, the biomass undergoes rapid pyrolysis in the reactor by contacting the hot catalyst coming from a regenerator which in this step acts as a thermal vector. The gases resulting from this pyrolysis will then react on the catalyst which this time plays its role of catalyst making it possible to catalyze the reactions producing the desired chemical intermediates.

The products obtained at the end of the catalytic pyrolysis step are advantageously recovered in the form of a gaseous pyrolysis mixture comprising at least part of BTX (Benzene, Toluene, Xylenes). Said gas mixture is then advantageously sent to a fractionation section so as to separate at least the following cuts:
ο the pyrolysis effluent 31,
ο the pyrolysis gas 32,

ο middle distillates 33; And
ο water (not shown).

According to one or more embodiments, the coked catalyst as well as the unconverted biomass 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 bringing into contact with a gas chosen from steam, an inert gas such as for example nitrogen and optionally a part of the pyrolysis gas 32. Said coked catalyst and the char, optionally stripped, are advantageously sent to a regenerator where coke and char are burned by adding air or oxygen. The catalyst thus regenerated is advantageously recycled in the reactor of the catalytic pyrolysis step in order to undergo another cycle. The catalytic 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 at least 65% and preferably at least 70% in BTX. The process also makes it possible to obtain, in addition to the pyrolysis effluent 31 and the pyrolysis gas 32, a heavier liquid fraction, mainly aromatic called middle distillates 33 which can advantageously be recovered in a process outside the process according to the invention. .

According to one or more embodiments, part of the pyrolysis gas 32 is recycled, preferably via a compressor, into the reactor of the catalytic pyrolysis step. This gaseous stream then serves as a driving fluid for the charge in said reactor. In this case, purging of said recycled gaseous effluent is inevitable and is preferably carried out, preferably either upstream or downstream of said compressor.

According to one or more embodiments, the pyrolysis effluent 31 is a hydrocarbon fraction containing mainly (i.e., > 50% by weight) molecules whose carbon number ranges from 6 to 10 carbon atoms. The pyrolysis effluent 31 may also contain molecules having more than 10 carbon atoms and/or molecules with 5 carbon atoms. The pyrolysis effluent 31 is rich in aromatics (e.g. > 50% by weight, preferably at least 65% by weight, very preferably at least 75% by weight), contains at least partly BTX, 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 31. According to one or more embodiments, the pyrolysis effluent 31 is treated to be specifications required of the input charge 2 as described above in order to present contents of sulphurous, nitrogenous and oxygenated elements compatible with an aromatic complex. According to one or more embodiments, the input charge 2 comprises less than 10 ppmw, preferably less than 5 ppmw, very preferably less than 1 ppmw of elemental nitrogen, and/or less than 10 ppmw, preferably less 5 ppmw, very preferably less than 1 ppmw elemental sulfur, and/or less than 100 ppmw, preferably less than 50 ppmw, most preferably less than 10 ppmw elemental oxygen.

According to one or more embodiments, the charge 2 of the aromatic complex comprises at least 60% by weight, preferably at least 80% by weight, very preferably at least 90% by weight, such as at least 95% by weight, of pyrolysis effluent 31 relative to the total weight of the load.

According to one or more embodiments, the pyrolysis gas 32 produced by the pyrolysis unit 13 consists of a mixture containing mainly (e.g. comprising at least 50% by weight) hydrogen, CO and CO2. According to one or more embodiments, the pyrolysis gas 32 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 pyrolysis gas 32. According to one or more embodiments, the pyrolysis gas 32 comprises at least 0.2% by weight of H2, preferably at least 0.5% by weight of H2, very preferably at least 0.8% by weight of H2 relative to the total weight of the pyrolysis gas 32. According to one or more embodiments, the pyrolysis gas 32 at the outlet of the pyrolysis unit 13 contains approximately 30% (e.g. ± 10% by weight ) weight of CO2 relative to the total weight of the pyrolysis gas 32. According to one or more embodiments, the pyrolysis gas 32 further comprises alkanes comprising from 1 to 3 carbon atoms and light olefins comprising from 2 to 4 carbon atoms. According to one or more embodiments, the pyrolysis gas 32 contains ethylene and propylene (e.g. less than 10% by weight) as well as water (e.g. less than 3% by weight).

According to one or more embodiments, the middle distillates 33 comprise compounds having a number of carbon atoms greater than or equal to 9. According to one or more embodiments, the middle distillates 33 comprise at least 50% by weight of compounds in C9+. C9+ compounds are mainly (e.g. at least 50 wt. %) composed of optionally alkylated di- and tri-aromatics. The middle distillates 33 can be upgraded directly to bunker fuel, for example, or undergo hydrotreatment and/or hydrocracking to improve their properties and upgrade them to jet fuel or diesel.

According to one or more embodiments, an H2 supply fed by the optional make-up line 34 is added to the pyrolysis gas 32 so that the H2/CO2 molar ratio of the pyrolysis gas 32 at the inlet of the RWGS reaction section 50, or between 1 and 10, preferably between 1 and 8, very preferably between 1 and 5. The hydrogen content of the pyrolysis gas 32 is preferably modified by adding hydrogen, so as to at least reach the stoichiometry of the RWGS reaction: CO2 + H2 CO + H2O. According to one or more embodiments, an excess of H2 will be used so that the gas of RWGS 51 obtained at the outlet of the reaction section of RWGS 50 has the composition required for conversion by Fischer-Tropsch reaction.

In the reaction section of RWGS 50, the pyrolysis gas 32 optionally enriched by an H2 supply is converted at least partially into a gas (51) enriched in CO and water (and thus depleted in CO2 and H2). Specifically, the RWGS reaction is the reaction of CO2 and H2 to form CO and water.

The RWGS reaction is well known to those skilled in the art, see for example Journal of CO2 Utilization 21 (2017) p.423–428. According to one or more embodiments, the reaction section of RWGS 50 is adapted to be operated under at least one of the following operating conditions:
- temperature between 400°C and 800°C, preferably between 500°C and 800°C, and even more preferably between 650°C and 750°C;
- pressure between 0.1 and 10 MPa, preferably between 0.1 and 5 MPa, and more preferably between 0.1 and 2.5 MPa;
- Space velocity of the pyrolysis gas 32 at the reactor inlet of between 5000 and 20000 mL/g _cata /h.

According to one or more embodiments, the catalyst used in the reaction section of RWGS 50 is chosen from the list consisting of catalysts based on iron or alkali metals (eg potassium). According to one or more embodiments, the catalyst for the RWGS reaction is chosen from the list consisting of catalysts based on Fe/Al2O3, Fe-Cu/Al2O3, Fe-Cs/Al2O3 and CuO-Fe2O3 doped with Cs. Conversions of 70% by weight of CO2 are commonly obtained with the operating conditions described above.

According to one or more embodiments, the reaction section of RWGS 50 is adapted to operate in a fluid bed or a fixed bed. According to one or more embodiments, the reaction section of RWGS 50 is adapted to operate in a fixed bed.

According to one or more embodiments, the gas of RWGS 51 comprises at least 20% molar, preferably at least 30% molar of CO, very preferably at least 40% molar (e.g. at least 50% molar of CO) of CO in the mixture of CO and CO2. According to one or more embodiments, the conversion of CO2 to CO (per pass) in the RWGS reactor is greater than 40%, preferably greater than 50% and preferably greater than 60%.

In the water and unconverted CO2 separation unit 52, the RWGS gas 51 is treated to produce a CO-enriched (and thus CO2, H2 and water-depleted) separation gas 53, CO2 unconverted 54 optionally being recycled to the inlet of the RWGS reaction section 50, the separated water 55 being purged out of the aromatic complex. According to one or more embodiments, the separation and recycling of the unconverted CO2 can be carried out by membrane. Advantageously, the recycling of the unconverted CO2 makes it possible to completely convert the CO2. According to one or more embodiments, the separated water 55, thus produced in the reaction section of RWGS 50, is used in the method according to the invention in unit operations for the pretreatment of the biomass upstream of the pyrolysis step. .

According to one or more embodiments, the separation gas 53, before mixing with hydrogen (line 56), comprises at least 80% by weight of CO, preferably at least 90% by weight of CO, very preferably at least 95% weight of CO (e.g. at least 97% weight of CO). According to one or more embodiments, the separation gas 53 comprises less than 15% weight of H2O, preferably less than 10% weight of H2O, very preferably less than 5% weight of H2O.

According to one or more embodiments, an H2 supply supplied by the optional make-up line 56 is added to the separation gas 53 so that the H2/CO molar ratio of the separation gas 53 at the inlet of the Fischer reaction section -Tropsch 14, i.e. between 0.5 and 2, preferably between 0.6 and 1. This adjustment in terms of the H2 /CO ratio can be made downstream of the reaction section of RWGS 50.

According to one or more embodiments, it is not necessary to treat the pyrolysis gas 32 and/or the RWGS gas 51 and/or the separation gas 53 in an additional dedicated unit. The pyrolysis gas can be sent directly to the Fischer-Tropsch reaction section 14. Thus, the aromatics produced will retain their biobased character. According to one or more embodiments, the pyrolysis gas 32 and/or the RWGS gas 51 and/or the separation gas 53 can be purified before being converted into a mixture of hydrocarbons in the Fischer-Tropsch reaction section 14. According to one or more embodiments, the purification methods serve in particular to reduce the content of sulfur compounds, nitrogen compounds, halogens, heavy metals and transition metals. The main syngas purification technologies are: adsorption, absorption, catalytic reactions. These 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, Vol. 68 (2013), No. 4 or at Applied Energy 237 (2019) 227–240.

In the Fischer-Tropsch reaction section 14, the separation gas 53 is in particular converted at least partially into a synthesis effluent 35 comprising hydrocarbon compounds whose carbon number ranges from 3 to 22 carbon atoms. The synthesis effluent 35 at least partially feeds the pyrolysis unit 13.

According to one or more embodiments, the Fischer-Tropsch reaction section 14 is adapted to be operated under at least one of the following operating conditions:
- temperature between 250°C and 400°C, preferably between 300°C and 350°C, and very preferably still between 300°C and 340°C;
- pressure between 1 and 5 MPa, preferably between 1.5 and 4 MPa, and very preferably between 2 and 3 MPa (eg at 2.5 MPa ±2);
- Catalyst comprising iron as the active phase;
- volume flow rate of the synthesis effluent of between 0.2 and 3 L/g _cat /h, and preferably between 0.5 and 1.5 L/g _cat /h.

According to one or more embodiments, the catalyst of the Fischer-Tropsch reaction section 14 is prepared by (co)precipitation or (co)impregnation. According to one or more embodiments, the catalyst of the Fischer-Tropsch reaction section 14 comprises between 70 and 90% by weight of Fe2O3, between 1 and 5% by weight of CuP, between 1 and 5% by weight of K2O, between 0.01 and 0.1% by weight of NaO and between 10 and 20% by weight of alumina and/or silica and/or zeolite (silicalite) relative to the total weight of the catalyst. For example, the catalyst may comprise 78.4 wt% Fe2O3, 3.4 wt% CuP, 2.6 wt% K2O, 0.04 wt% Na2O and 15 wt% SiO2).

According to one or more embodiments, the Fischer-Tropsch reaction section 14 is adapted to operate in a fluid bed, a fixed bed, or in a slurry (e.g. catalyst maintained in suspension in a liquid medium consisting of the reaction products, the agitation of this reaction medium results from the injection of synthesis gas within the liquid phase), fluid bed technology being the preferred embodiment. These different reactor technologies are well known to those skilled in the art, reference may be made to: International Journal of Chemical Reactor Engineering 2014; 12(1): 1–26. The method of catalyst fabrication depends on the mode of operation of the Fischer-Tropsch reaction section 14. For fluid bed operation, catalysts are preferably attrition resistant. For example, catalysts based on molten iron, prepared by fusion, satisfy this requirement.

According to one or more embodiments, the synthesis effluent 35 comprises a mixture of hydrocarbons that are liquid at room temperature. According to one or more embodiments, the synthesis effluent 35 comprises a mixture comprising olefins from C3 to C22, for example at a content of at least 50% by weight relative to the total weight of the synthesis effluent 35. According to one or more embodiments, the content by weight of C3 to C22 olefins is at least 60% by weight, and preferably at least 70% by weight relative to the total weight of the synthesis effluent 35. According to one or more embodiments, the synthesis effluent 35 further comprises C3 to C22 paraffins, for example at a content of between 20 and 35% by weight and optionally oxygenated compounds, for example at a content of between 1 and 5% by weight relative to the total weight of the synthesis effluent 35. According to one or more embodiments, the synthesis effluent 35 also comprises aromatic compounds, for example at a content of between 1 and 10% by weight relative to the total weight of the synthesis effluent 35. According to one or several embodiments, the synthesis effluent 35 is recycled in its entirety in the pyrolysis unit 13.

Thus the combination of a Fischer-Tropsch reaction section 14 and the recycling of the synthesis effluent 35 to the pyrolysis unit 13 makes it possible to produce additional aromatics from CO and CO2, by-products of the pyrolysis unit 13.

The device and the method according to the invention thus make it possible to obtain gains of up to 100% by weight in aromatic compounds, the gain being mainly a gain of paraxylene (of the order of 170% by weight), the quantity of benzene remaining substantially unchanged.

In the present 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 D.R. Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification; group VIb according to the CAS classification corresponds to the metals of column 6 according to the new IUPAC classification.

Examples

Example of reference device

An example of a reference device for converting a feed comprising a mixture of aromatic compounds from a process for converting lignocellulosic biomass based on conversion by catalytic pyrolysis is used.

The example reference device is similar to the device represented in FIG. 1 except that the transalkylation unit 8 is replaced by a disproportionation unit (not represented). A disproportionation reaction is called a transalkylation reaction when the charge does not include heavy aromatics (e.g. A9 and A10). In a transalkylation reactor, toluene disproportionation reactions also occur. All of this is well known to those skilled in the art.

Additionally, the example reference device does not implement the following units:
- column of heavy aromatics 7;
- selective hydrogenolysis unit 9;
- stabilization column 12;
- Fischer-Tropsch reaction section 14;
- reaction section of RWGS 50;
- separation section 52.

The flow rates of said aromatic compounds of the feed to be treated, at the inlet of the feed separation unit 1 are as follows:
- benzene: 2.63 t/h;
- toluene: 5.64 t/h;
- ethylbenzene: 0.15 t/h; And
- xylenes: 3.56 t/h.

That is a total of 11.98 t/h of aromatic compounds.

Furthermore, the pyrolysis unit 13 produces CO and CO2, which are not converted into other chemical compounds. The flow of CO produced is 22.25 t/h, the flow of CO2 15.99 t/h.

In the reference device, all of the toluene is converted by a disproportionation unit into benzene and xylenes. The xylenes in 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 a simulated moving bed adsorption unit . This set of unit operations makes it possible, in the best case (assuming 100% selectivity for each unit operation), to produce the following compounds:
- benzene: 5.02 t/h;
- paraxylene: 6.96 t/h
- aromatic total: 11.98 t/h.

Example of device according to the invention

The example of a device according to the invention makes it possible to increase the total quantity of aromatics produced for the same biomass feed rate at the inlet of the catalytic pyrolysis as in the reference device, and in particular to increase the quantity of paraxylene produced.

The example device according to the invention is similar to the device represented in FIG. 1 but does not implement the following optional units:
- column of heavy aromatics 7;
- selective hydrogenolysis unit 9;
- stabilization column 12.

Compared to the reference device diagram, the RWGS reaction section 50 and the separation section 52 are notably added, as well as the Fischer-Tropsch synthesis reaction section 14. This section treats all of the CO (CO produced by the pyrolysis catalyst and CO formed in the RWGS unit).

The gas stream from the catalytic pyrolysis section 13 containing CO, CO2 and hydrogen is introduced into a reaction section of RWGS 50, with a hydrogen make-up 34. At the outlet of the reaction section of RWGS 50, the water formed 55 and the unconverted CO2 54 are separated by condensation by means of a membrane system in the separation unit 52. The unconverted CO2 54 is recycled to the inlet of the reaction section of RWGS 50. The conversion, thanks to this CO2 recycling, is complete. The water formed 55 can advantageously be used upstream of the catalytic pyrolysis unit for the biomass pretreatment operations.

The separation gas 53 mainly contains (i.e. > 50% by weight) hydrogen and CO. After addition of a make-up of hydrogen 56, it is sent to the Fischer-Tropsch synthesis reaction section 14 operated at a temperature between 300° C. and 350° C. and a pressure of 2.5 MPa ±2.

At the outlet of the Fischer-Tropsch reaction section 14, a synthesis effluent 35 is obtained mainly composed of hydrocarbons, CO 2 and unconverted CO. The synthesis effluent 35 contains 58.94% by weight of olefins, 29.4% by weight of paraffins, 3.74% by weight of aromatic compounds and 7.92% by weight of oxygenated compounds.

All of the synthesis effluent 35 is recycled to the inlet of the catalytic pyrolysis section 13 of the biomass to be converted there. The conversion of this hydrocarbon effluent from the Fischer-Tropsch reaction section 14 in the catalytic pyrolysis unit 13 makes it possible to produce a surplus of aromatic compounds, as well as paraffins. The CO2 that was produced in the Fischer-Tropsch reaction section 14 is also recycled to the catalytic pyrolysis unit 13, it will then be converted into CO in the reaction section of RWGS 50.

Thus the conversion of CO and CO2 resulting from pyrolysis and Fischer-Tropsch reactions into aromatic and paraffinic compounds is complete. All of the carbon resulting from the conversion of biomass is converted into compounds with high added value.

Example of reference device Example of device according to the invention Make-up H2 for RWGS (t/h)

Entrance to the aromatic complex

paraffins
Benzene
Toluene
Ethylbenzene
Xylenes
A9+A10 aromatics

Products (t/h)
Benzene
p-xylene
Total aromatics

paraffins
water
CO (t/h)
CO2 (t/h)
H2 (t/h)
0



0
2.63
5.64
0.15
3.56
0


5.02
6.96
11.98

0
0
22.25
15.99
0.338
4,684



4,548
3.20
7,906
0.15
8,092
3,966


4.24
19,074
23,314

4,548
27.38
0
0
0

Table 1 shows that the implementation according to the invention makes it possible to produce 95% more aromatics by weight (23.3 t/h instead of 11.98 t/h). This increase in aromatic compounds essentially concerns paraxylene, which went from 6.96 t/h to 19 t/h, i.e. a gain of 170%. A quantity of water equal to 27.38 t/h is also produced, it can be used in the biomass pretreatment stages upstream of the catalytic pyrolysis unit.

Claims (15)

Device for converting a load (2) of aromatic compounds, comprising:
- a fractionation train (4-7) adapted to extract at least one cut comprising benzene (22), one cut comprising toluene (23) and one cut comprising xylenes and ethylbenzene (24) from the feed ( 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) suitable for treating the raffinate (40) and producing an isomerate (42) enriched in paraxylene sent to the fractionation train (4-7);
- a pyrolysis unit (13) suitable for treating biomass (30), producing at least one pyrolysis effluent (31) comprising hydrocarbon compounds with 6 to 10 carbon atoms supplying at least partially the load (2), and producing a pyrolysis gas (32) comprising at least CO, CO2 and H2;
- an inverted water shift reaction section (50) adapted to treat the pyrolysis gas (32) and produce an inverted water shift gas (51) enriched in CO and water;
- a separation unit (52) adapted to separate water (55) and unconverted CO2 (54) from the reverse water conversion gas (51) and produce a separation gas (53) enriched in CO ;
- a Fischer-Tropsch synthesis reaction section (14) adapted to at least partially treat the separation gas (53), produce a synthesis effluent (35) comprising hydrocarbon compounds with 3 to 22 carbon atoms, and send the synthesis effluent (35) at least partly to the pyrolysis unit (13). A conversion device according to claim 1, further comprising a first make-up line (34) to provide an H2 supply in the pyrolysis gas (32). A conversion device as claimed in claim 1 or claim 2, further comprising a second make-up line (56) for supplying H2 to the stripping gas (53). Conversion device according to any one of the preceding claims, in which the fractionation train (4-7) is adapted to extract a cut of C9-C10 mono-aromatics (25) from the feed (2). Conversion device according to claim 4, further comprising a transalkylation unit (8) adapted to treat the C9-C10 mono-aromatic cut (25) with the cut comprising toluene (23) and produce xylenes sent to the split train (4-7). Conversion device according to claim 5, further comprising a selective hydrogenolysis unit (9) suitable for:
- treat the cut of mono-aromatics in C9-C10 (25); And
- producing a hydrogenolysis effluent enriched in methyl-substituted aromatic compounds (46) sent to the transalkylation unit (8). Conversion device according to any one of the preceding claims, in which the Fischer-Tropsch synthesis reaction section (14) is adapted to recycle the synthesis effluent (35) in its entirety to the pyrolysis unit (13). Process for converting a charge (2) of aromatic compounds, comprising the following steps:
- fractionating the feed (2) in a fractionation train (4-7) 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;
- Isomerize the raffinate (40) in an isomerization unit (11) and produce an isomerate (42) enriched in paraxylene;
- sending the isomerate (42) enriched in paraxylene to the fractionation train (4-7);
- treating biomass (30) in a pyrolysis unit (13) to produce at least one pyrolysis effluent (31) comprising hydrocarbon compounds of 6 to 10 carbon atoms supplying at least partially the charge (2) and producing a pyrolysis gas (32) comprising at least CO, CO2 and H2.
- treating the pyrolysis gas (32) in an inverted water gas conversion reaction section (50) to produce an inverted water conversion gas (51) enriched in CO and water;
- separating water (55) and unconverted CO2 (54) from the reverse water conversion gas (51) in a separation unit (52) to produce a CO enriched separation gas (53);
- at least partially treating the separation gas (53) in a Fischer-Tropsch synthesis reaction section (14) to produce a synthesis effluent (35) comprising hydrocarbon compounds of 3 to 22 carbon atoms; And
- sending the synthesis effluent (35) at least in part to the pyrolysis unit (13). . Conversion process according to Claim 8, in which the pyrolysis unit (13) comprises at least one reactor used under the following operating conditions:
- presence of a catalyst, preferably a zeolite catalyst, preferably a zeolite catalyst comprising at least one zeolite chosen from ZSM-5, ferrierite, Beta zeolite, Y zeolite, mordenite, ZSM-23, ZSM- 57, EU-1, ZSM-11, preferably a catalyst comprising only a ZSM-5 type zeolite; the zeolite used in the catalyst can advantageously be doped with a metal chosen from iron, gallium, zinc and lanthanum;
- a temperature between 400 and 1000°C, preferably between 400 and 650°C, more preferably between 450 and 600°C and very preferably between 450 and 590°C;
- an absolute pressure of between 0.1 and 0.5 MPa;
- a VVH of between 0.01 and 10 h ^-1 , preferably between 0.01 and 5 h ^-1 , preferably between 0.1 and 3 h ^-1 and very preferably between 0.1 and 3 h ^-1 . Conversion process according to any one of Claims 8 to 9, in which the Fischer-Tropsch synthesis reaction section (14) is used under the following operating conditions:
- temperature between 250°C and 400°C, preferably between 300°C and 350°C, and very preferably still between 300°C and 340°C;
- pressure between 1 and 5 MPa, preferably between 1.5 and 4 MPa, and very preferably between 2 and 3 MPa;
- Catalyst comprising iron as the active phase;
- volume flow rate of the synthesis effluent of between 0.2 and 3 L/g _cat /h, and preferably between 0.5 and 1.5 L/g _cat /h. . Conversion process according to any one of Claims 8 to 10, in which the isomerization unit (11) comprises a gas-phase isomerization zone and/or a liquid-phase isomerization zone,
wherein the gas phase isomerization zone is used under the following operating conditions:
- temperature above 300°C;
- pressure less than 4.0 MPa;
- hourly space velocity less than 10 h ^-1 ;
- hydrogen to hydrocarbon molar ratio less than 10;
- 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, and at least one group VIII metal with a content between 0.1 and 0 .3% weight, terminals included, and
wherein the liquid phase isomerization zone is used under the following operating conditions:
- temperature below 300 C;
- pressure less than 4 MPa;
- hourly space velocity less than 10 h ^-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. Conversion process according to any one of Claims 8 to 11, in which the transalkylation unit (8) comprises at least one first transalkylation reactor used under the following operating conditions:
- temperature between 200°C and 600°C;
- pressure between 2 and 10 MPa;
- PPH between 0.5 and 5 h ^-1 . A conversion method according to any of claims 8 to 12, further comprising supplying H2 to the pyrolysis gas (32) by means of a first make-up line (34). A conversion process according to any of claims 8 to 13, further comprising supplying H2 to the stripping gas (53) by means of a second make-up line (56). Conversion process according to any one of Claims 8 to 14, in which the synthesis effluent (35) is recycled in its entirety to the pyrolysis unit (13).