EP-4735406-A1 - 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 CO 2 ; 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.

Inventors

• JOLY, JEAN-FRANCOIS
• LAROCHE, CATHERINE
• CHAHEN, LUDOVIC
• FRECON, JACINTHE

Assignees

• IFP Energies nouvelles

Dates

Publication Date

20260506

Application Date

20240613

Claims (1)

1. 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 preceding claim, comprising providing a supply of hydrogen (35) in the synthesis gas (34). 6. A method according to any one of the preceding claims, wherein 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 h' 1 , preferably between 0.01 h' 1 and 5 h' 1 , and very preferably between 0.1 h' 1 and 3 h' 1 , the WH being 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; zeolite 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; space velocity of the gas at the reactor inlet between 0.2 g/g cat /h and 1 g/gcat/h. 8. A method according to any preceding claim, 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, in which the isomerization unit (11) 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 VI 11 B with a content of between 0.1 and 0.3% by weight, limits included. 10. A method according to any preceding claim, 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 10h' 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 xylene 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).

Description

Production of aromatics by conversion of synthesis gas to methanol and alkylation of toluene Technical field The invention relates to the production of aromatics for petrochemistry (benzene, toluene, xylenes, i.e., BTX). More particularly, the subject of the invention relates to the production of aromatics (e.g. paraxylene) from the conversion of hydrocarbon compounds (e.g. biomass) into synthesis gas comprising CO and CO2. An aromatic complex (or aromatic compound conversion device) is a device fed with feedstocks predominantly composed of six to ten or more carbon atoms, denoted C6 to C10+ feedstocks. Different sources of aromatic compounds can be introduced into an aromatic complex, the most common being from a catalytic reforming process of naphthas. 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. The processes of oxycombustion pyrolysis and gasification of hydrocarbon compounds produce a lot of recoverable carbon monoxide (CO) and carbon dioxide (CO2). Pyrolysis processes also produce aromatic compounds. When pyrolysis is catalytic, the combustion of the coke present on the catalyst used in the pyrolysis reactor also produces a significant amount of CO2. Previous technique To date, aromatic complexes can produce benzene, possibly toluene, and xylenes (often paraxylene, sometimes orthoxylene). An aromatic complex generally has at least one catalytic unit exhibiting 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 produces benzene and xylenes. The aromatic loop makes it possible to 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 removing 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 very generally 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 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 back 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. The aromatic complexes producing benzene and paraxylene are overwhelmingly supplied by feedstocks from oil or natural gas. These complexes do not allow the production of bio-sourced aromatics. Another challenge is to valorize carbon in the form of CO and CO2, and in particular bio-sourced carbon, into high added-value compounds. An object of the present invention is to overcome these drawbacks. Summary of the invention 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 originating from the combustion of the coke present on the catalyst of the pyrolysis process can also be advantageously converted into aromatic compounds. The invention is based on the conversion of carbon monoxide, i.e., CO, and carbon dioxide, i.e., CO2, into chemical compounds that are introduced into the aromatic complex, and in particular on the arrangement of several units for converting CO and CO2 into aromatic compounds in two stages: in a methanol synthesis reactor and 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. 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 m