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BR-102020025461-B1 - DEVICE AND PROCESS FOR CONVERTING AROMATIC COMPOUNDS BY ALKYLATION OF BENZENE WITH ETHYLENE

BR102020025461B1BR 102020025461 B1BR102020025461 B1BR 102020025461B1BR-102020025461-B1

Abstract

DEVICE AND PROCESS FOR CONVERTING AROMATIC COMPOUNDS BY ALKYLATION OF BENZENE BY ETHYLENE. The present invention relates to a device and process for converting aromatic compounds, comprising/using: a fractionation train (4-7) adapted to extract at least one cut comprising benzene (22), a cut comprising toluene (23) and a cut comprising xylenes and ethylbenzene (24) from the feed (2); a xylene separation unit (10) adapted to treat the cut comprising xylenes and ethylbenzene and produce an extract comprising paraxylene (39) and a raffinate (40) comprising orthoxylene, metaxylene and ethylbenzene; an isomerization unit (11) to treat the raffinate and produce an isomerate (42) enriched with paraxylene sent to the fractionation train; and an alkylation reaction section (13) for treating at least part of the cut comprising benzene with an ethylene source (30) and producing an alkylation effluent (31) comprising ethylbenzene sent to the isomerization unit.

Inventors

  • Jean-Francois Joly
  • Frederic Feugnet

Assignees

  • IFP Energies Nouvelles

Dates

Publication Date
20260317
Application Date
20201214
Priority Date
20191217

Claims (15)

  1. 1. Device for converting a feedstock (2) of aromatic compounds, characterized in that it comprises: - a fractionation train (4-7) adapted to extract at least one cut comprising benzene (22), a cut comprising toluene (23) and a cut comprising xylenes and ethylbenzene (24) from the feedstock (2); - a xylene separation unit (10) adapted to treat the cut comprising ethylbenzene (24) and produce an extract comprising para-xylene (39) and a raffinate (40) comprising ortho-xylene, meta-xylene and ethylbenzene; - an isomerization unit (11) adapted to treat the raffinate (40) and produce a para-xylene-enriched isomer stream (42) sent to the fractionation train (4-7); and an alkylation reaction section (13) adapted to treat at least part of the cut comprising benzene (22) with an ethylene source (30) and produce an alkylation effluent (31) comprising ethylbenzene sent to the isomerization unit (11).
  2. 2. Conversion device according to claim 1, characterized in that it further comprises a transalkylation reaction section (14) adapted to trans-alkylate polyethylbenzenes present in the alkylation effluent (31) and produce an ethylbenzene-enriched cut (32; 47).
  3. 3. Conversion device according to claim 1 or 2, characterized in that it further comprises a fractionation unit (15) adapted to treat the alkylation effluent (31) and produce a plurality of fractionation cuts comprising at least one ethylbenzene cut (33) sent to the isomerization unit (11), a benzene cut (35).
  4. 4. Conversion device according to claim 2 or 3, characterized in that the fractionation unit (15) is arranged downstream of the transalkylation reaction section (14) and is adapted to treat the ethylbenzene-enriched cut (32; 47).
  5. 5. Conversion device according to claim 2 or 3, characterized in that the fractionation unit (15) is adapted to produce at least one polyethylbenzene cut (36), and in that the transalkylation reaction section (14) is arranged downstream of the fractionation unit (15) and is adapted to treat at least a portion of said polyethylbenzene cut (36).
  6. 6. Conversion device according to any of the preceding claims, characterized in that the fractionation train (4-7) is adapted to extract a cut of C9-C10 mono-aromatics (25) from the charge (2).
  7. 7. Conversion device according to claim 6, characterized in that it further comprises 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 fractionation train (4-7).
  8. 8. Conversion device according to any of the preceding claims, characterized in that it further comprises a dismutation unit (48) adapted to treat the cut comprising toluene (23) and produce a cut enriched with xylenes (50) recycled to the isomerization unit (11).
  9. 9. Process for converting a feedstock (2) of aromatic compounds, characterized in that it comprises the following steps: - fractionating the feedstock 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 para-xylene (39) and a raffinate (40) comprising ortho-xylene, meta-xylene and ethylbenzene; - isomerizing the raffinate (40) in an isomerization unit (11) and producing a para-xylene-enriched isomer stream (42); - sending the para-xylene-enriched isomer stream (42) to the fractionation train (4-7); - alkylating by except a portion of the cut comprising benzene (22) as a source of ethylene (30) in an alkylation reaction section (13) and produce an alkylation effluent (31) comprising ethylbenzene; and send the alkylation effluent (31) comprising ethylbenzene to the isomerization unit (11).
  10. 10. Conversion process according to claim 9, characterized in that the alkylation reaction section (13) comprises at least one alkylation reactor, which is used under the following operating conditions: - temperature between 20°C and 400°C; - pressure between 1 and 10 MPa; - benzene/ethylene molar ratio between 2 and 10; - PPH between 0.5 and 50 h-1.
  11. 11. Conversion process according to claim 10, characterized in that the alkylation reactor is operated in the presence of a catalyst comprising a zeolite.
  12. 12. Conversion process according to any one of claims 9 to 11, characterized in that 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 below 4.0 MPa; - hourly space velocity below 10 h⁻¹; - hydrogen-to-hydrocarbon molar ratio below 10; - in the presence of a catalyst comprising at least one zeolite exhibiting channels whose opening is defined by a ring of 10 or 12 oxygen atoms, and at least one group VIII metal with a content between 0.1 and 0.3% by weight, inclusive; and - wherein the liquid-phase isomerization zone is used under the following operating conditions: - temperature below 300°C; - pressure below 4 MPa; - hourly space velocity below at 10 h-1;- in the presence of a catalyst containing at least one zeolite that has channels whose opening is defined by a ring of 10 or 12 oxygen atoms.
  13. 13. Conversion process according to any one of claims 9 to 12, characterized in that it further comprises the following step: - trans-alkylating polyethylbenzenes present in the alkylation effluent (31) in a transalkylation reaction section (14) and producing an ethylbenzene-enriched cut (32; 47), and - sending the ethylbenzene-enriched cut (32; 47) to the isomerization unit (11).
  14. 14. Conversion process according to claim 13, characterized in that the transalkylation reaction section (14) comprises at least one transalkylation reactor used under the following operating conditions: - temperature between 200°C and 400°C; - pressure between 1 and 6 MPa; - PPH between 0.5 and 5 h-1.
  15. 15. Conversion process according to claim 14, characterized in that the transalkylation reactor (14) is operated in the presence of a catalyst comprising a zeolite.

Description

Technical field [001] The present invention relates to the conversion of aromatics in the context of the production of aromatics for petrochemicals (benzene, toluene, para-xylene, ortho-xylene). More particularly, the object of the invention is to be able to control the respective quantities of benzene and para-xylene and, in particular, to be able to produce only para-xylene. [002] The aromatic complex (or aromatic compound conversion device) is fed by charges mostly composed of ten or more carbon atoms, designated as C6 to C10+ charges. Different sources of aromatic compounds can be introduced into an aromatic complex, the largest being the catalytic reforming process of naphthas. Mixtures of aromatic compounds obtained by lignocellulosic biomass conversion processes can also be introduced, after purification treatment, into an aromatic complex. For example, the catalytic pyrolysis process of lignocellulosic biomass can be considered as a source of aromatics. [003] Within the aromatic complex, whatever the source of aromatics, benzene and aromatic alkyls (e.g., toluene, para-xylene, ortho-xylene) are extracted from it, then converted into desired intermediates. The products of interest are aromatics with (benzene), (toluene), (xylenes), methyl groups and, in particular, within the xylenes, para-xylene, having the highest commercial value. [004] Therefore, it is convenient to have methyl groups so that all aromatic nuclei that leave the aromatic complex have 2 methyl groups (for example, para-xylene, ortho-xylene). State of the art [005] Currently, aromatic complexes allow the production of benzene, possibly toluene, and xylenes (frequently para-xylene, sometimes ortho-xylene). An aromatic complex generally has at least one catalytic unit that exhibits at least one of the following functions: - isomerization of 8-carbon aromatic compounds, denoted A8 compounds, which allow the conversion of ortho-xylene, meta-xylene, and ethylbenzene into para-xylene; - trans-alkylation allowing the production of xylenes from a mixture of toluene (and optionally benzene) and A9+ compounds, such as trimethylbenzenes and tetramethylbenzenes; and - dismutation of toluene, which allows the production of benzene and xylenes. [006] The aromatic ring allows the production of high-purity para-xylene by separation or by adsorption or by crystallization, an operation well known in the state of the art. This "aromatic 8-ring" includes a step to eliminate heavy compounds (i.e., C9+) in a distillation column called a "xylene column". The top stream from this column, which contains the aromatic C8 isomers (i.e., A8), is then sent to the para-xylene separation process, which is usually a simulated moving bed (SMB) adsorption separation process to produce an extract and a raffinate, or a crystallization process, in which a para-xylene fraction is isolated from the rest of the mixture constituents in the form of crystals. [007] The extract, which contains para-xylene, is then distilled to obtain high-purity para-xylene. The refined product, rich in meta-xylene, ortho-xylene, and ethylbenzene, is treated in a catalytic isomerization unit that re-establishes a mixture of aromatics at C8, in which the production of xylenes (ortho, meta, para-xylenes) is practically in thermodynamic equilibrium and the amount of ethylbenzene is weakened. This mixture is sent back to the "xylene column" with the fresh feed. [008] All industrial processes for the isomerization of C8 aromatics allow the isomerization of xylenes. The transformation of ethylbenzene, however, depends on the type of process and catalyst chosen. The reason is that petrochemical complexes use an isomerization unit called an "isomerizer" (i.e., isomerization of ethylbenzene into a mixture of C8 aromatics) or a "dealkylator" (i.e., dealkylation of ethylbenzene into benzene), in order to prioritize the production (at the aromatic ring exit), respectively, of either only para-xylene, or of benzene and para-xylene. [009] The choice of an "isomerizing" isomerization allows, as indicated above, maximizing the production of para-xylene, which is the compound with the highest added value in the output of the aromatic complex. The association within an aromatic complex of an "isomerizing" isomerization and a liquid-phase isomerization as described, for example, in patents US8697929, US 7371913, US 4962258, US6180550, US7915471, US10035739 and US10029958, notably allows maximizing the amount of para-xylene produced, having a reduced loss of aromatic cycles compared to an aromatic complex according to the state of the art. Summary of the invention [0010] In the context described above, a first object of the present description is to overcome the problems of the prior art and provide a device and a process for the production of aromatics for the petrochemical industry, which allow, for any type of feedstock that feeds an aromatic complex, adjusting the respective amounts of benzene and para-xylene,