EP1846348A1 - Procédé pour la fabrication d éthylbenzène et la transalkylation au xylène - Google Patents
Procédé pour la fabrication d éthylbenzène et la transalkylation au xylèneInfo
- Publication number
- EP1846348A1 EP1846348A1 EP05713284A EP05713284A EP1846348A1 EP 1846348 A1 EP1846348 A1 EP 1846348A1 EP 05713284 A EP05713284 A EP 05713284A EP 05713284 A EP05713284 A EP 05713284A EP 1846348 A1 EP1846348 A1 EP 1846348A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- transalkylation
- stream
- xylene
- benzene
- unit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
- C07C15/02—Monocyclic hydrocarbons
- C07C15/067—C8H10 hydrocarbons
- C07C15/08—Xylenes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C6/00—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions
- C07C6/08—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions by conversion at a saturated carbon-to-carbon bond
- C07C6/12—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions by conversion at a saturated carbon-to-carbon bond of exclusively hydrocarbons containing a six-membered aromatic ring
- C07C6/126—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions by conversion at a saturated carbon-to-carbon bond of exclusively hydrocarbons containing a six-membered aromatic ring of more than one hydrocarbon
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/18—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65
Definitions
- This invention relates to an improved process for the conversion of aromatic hydrocarbons. More specifically, the present invention concerns a combination process for liquid-phase transalkylation of benzene with Co- + alkylaromatics to obtain ethylbenzene that would otherwise be lost via dealkylation to benzene or toluene in a subsequent gas-phase transalkylation process, thus obtaining a higher overall yield of xylenes.
- the xylene isomers are produced in large volumes from petroleum as feedstocks for a variety of important industrial chemicals. The most important of the xylene isomers is para-xylene, the principal feedstock for polyester, which continues to enjoy a high growth rate from large base demand.
- Ortho-xylene is used to produce phthalic anhydride, which supplies high-volume but relatively mature markets. Meta-xylene is used in lesser but growing volumes for such products as plasticizers, azo dyes and wood preservers. Ethylbenzene generally is present in xylene mixtures and is occasionally recovered for styrene production, but is usually considered a less-desirable component of Cg aromatics. [0003] Among the aromatic hydrocarbons, the overall importance of xylenes rivals that of benzene as a feedstock for industrial chemicals.
- Xylenes and benzene are produced from petroleum by reforming naphtha but not in sufficient volume to meet demand, thus conversion of other hydrocarbons is necessary to increase the yield of xylenes and benzene. Often toluene is de-alkylated to produce benzene or selectively disproportionated to yield benzene and Cg aromatics from which the individual xylene isomers are recovered. [0004] A current objective of many aromatics complexes is to increase the yield of xylenes and to de-emphasize benzene production. Demand is growing faster for xylene derivatives than for benzene derivatives.
- US 5,847,256 discloses a process for producing xylene from a feedstock containing C9 alkylaromatics with ethyl-groups over a catalyst containing a zeolite component that is preferably mordenite and with a metal component that is preferably rhenium.
- US 5,942,651 discloses a flowscheme for a gas-phase transalkylation process in the presence of two zeolite containing catalysts to produce xylenes and benzene.
- the first catalyst contains a hydrogenation metal component and a zeolite component from the group including MCM-22, PSH-3, SSZ-25, ZSM-12, and zeolite beta.
- the second catalyst contains ZSM-5, and is used to reduce the level of saturate coboilers necessary for a high-purity benzene product.
- US 5,952,536 discloses a gas-phase transalkylation process using a catalyst comprising a zeolite from the group including SSZ-26, Al-SSZ-33, CIT-I, SSZ-35, and SSZ-44.
- the catalyst also comprises a mild hydrogenation metal such as nickel or palladium, and is used to convert aromatics with at least one alkyl group including benzene.
- a mild hydrogenation metal such as nickel or palladium
- the present invention a process for transalkylation of benzene and Cg + alkylaromatics, is integrated with a separate transalkylation process.
- the integrated process increases selectivity to xylenes by addressing the preservation of ethylbenzene in a first transalkylation unit that would otherwise be lost in a second transalkylation unit, thus resulting in a higher overall yield of valuable xylenes from both units.
- the first transalkylation unit is substantially liquid-phase
- the second separate transalkylation process is substantially gas-phase.
- the process is also useful as an apparatus for xylene production from light and heavier aromatics.
- the liquid-phase transalkylation process can be integrated into a modern aromatic complex flow scheme to provide an increased yield of para-xylene isomer.
- FIGURE schematically illustrates the major equipment used in performing the process of this invention.
- Cc alkylaromatics carried by a line 10 is admixed with benzene from a line 12 to form a combined line 14 and enters a transalkylation reactor 16.
- a line 18 carries the effluent from the transalkylation reactor 16 to a combination point with a second transalkylation product stream in a line 20 to form a combined stream in a line 22 that enters a separation column 24.
- Separation column 24 separates the combined stream into an overhead of benzene taken by a line 26; a bottoms stream of Cg + alkylaromatics including ethylbenzene and xylene taken by a line 32; and a sidecut stream of toluene removed by a line 30.
- the overhead stream in line 26 is recycled back to transalkylation reactor 16 by line 12 after benzene is either removed or added via a line 28.
- the bottoms stream in line 32 is flowed to a second separation column 38 from which an overhead stream of ethylbenzene and xylene is taken by a line 40 and a bottom stream of Cg + alkylaromatics is withdrawn by a line 42.
- the ethylbenzene and xylene stream is sent via line 40 to a para-xylene production unit 66 to produce para-xylene by a line 68.
- the sidecut stream in line 30 is ultimately recycled to a second transalkylation reactor 58 by a line 46 after toluene is either removed or added via a line 44.
- Toluene in line 46 is admixed with line 42 to form a combined line 48 that enters a third separation column 50.
- Separation column 50 separates the combined stream into bottoms stream of C ⁇ ⁇ + alkylaromatics (called heavies) withdrawn by a line 52, and an overhead stream of C ⁇ Q, C9 alkylaromatics, and lighter compounds (including C7 alkylaromatics) carried by a line 54 to second transalkylation reactor 58. Hydrogen is added to second transalkylation reactor 58 via a line 56.
- a line 60 After contact with a transalkylation catalyst, a line 60 carries the effluent to a stabilizer column 64 from which an overhead stream of light end hydrocarbons (called light-ends gas, which generally comprises at least ethane) is taken by a line 62 and a bottom stream of second transalkylation product is withdrawn by line 20.
- light-ends gas which generally comprises at least ethane
- the feedstream to the present process generally comprises alkylaromatic hydrocarbons of the general formula CgH( ⁇ n )Rn, where n is an integer from 0 to 5 and each R may be CH3, C2H5, C3H7, or C4H9, in any combination.
- Suitable alkylaromatic hydrocarbons include, for example but without so limiting the invention, benzene, toluene, ortho-xylene, meta-xylene, para-xylene, ethylbenzene, ethyltoluenes, propylbenzenes, tetramethylbenzenes, ethyl-dimethylbenzenes, diethylbenzenes, methylpropylbenzenes, ethylpropylbenzenes, triethylbenzenes, di-isopropylbenzenes, and mixtures thereof.
- the feed stream preferably comprises benzene and C9 "1" aromatics and suitably is derived from one or a variety of sources.
- the molar ratio of benzene to Cc) + aromatics is preferably from 0.5 to 10.
- Feedstock may be produced synthetically, for example, from naphtha by catalytic reforming or by pyrolysis followed by hydrotreating to yield an aromatics-rich product.
- the feedstock may be derived from such product with suitable purity by extraction of aromatic hydrocarbons from a mixture of aromatic and nonaromatic hydrocarbons and fractionation of the extract.
- aromatics may be recovered from a reformate stream.
- the reformate stream may be produced by any of the processes known in the art.
- the aromatics then may be recovered from the reformate stream with the use of a selective solvent, such as one of the sulfolane type, in a liquid-liquid extraction zone.
- the recovered aromatics may then be separated into streams having the desired carbon number range by fractionation.
- extraction may be unnecessary and fractionation may be sufficient to prepare the feedstock.
- Benzene may also be recovered from the product of transalkylation.
- a preferred component of the feedstock is a heavy-aromatics stream comprising C9 aromatics and CJO aromatics.
- C ⁇ ⁇ + aromatics also may be present, typically in an amount of 50 wt-% or less of the feed.
- the heavy-aromatics stream generally comprises at least 90 wt-% aromatics, and may be derived from the same or different known refinery and petrochemical processes as the benzene and toluene feedstock and/or may be recycled from the separation of the product from transalkylation.
- the feedstock is preferably transalkylated in the liquid-phase and in the substantial absence of hydrogen. Substantial absence of hydrogen means without the addition of hydrogen beyond what may already be present and dissolved in a typical liquid aromatics feedstock. In the case of partial liquid-phase, hydrogen may be added in an amount less than 1 mole per mole of alkylaromatics.
- the feedstock is transalkylated in the gas-phase
- hydrogen is added with the feedstock and recycled hydrocarbons in an amount of from 0.1 moles per mole of alkylaromatics up to 10 moles per mole of alkylaromatic.
- This ratio of hydrogen to alkylaromatic is also referred to as hydrogen to hydrocarbon ratio.
- the transalkylation reaction preferably yields a product having increased xylene content of at least greater than 1 wt-% and also comprises ethylbenzene.
- the unit preferably comprises a recycle gas compressor to assist in recycling of hydrogen recovered from the reactor effluent in a separator vessel.
- transalkylation zone Preferably, one zone will be liquid-phase and one zone will be gas- phase.
- Each transalkylation zone will continue to be described in generic terms below. Note that details of heat integration and additional flow details within the zones have not been shown in the schematic figure because they are well known to the art.
- the feed to a transalkylation reaction zone usually first is heated by indirect heat exchange against the effluent of the reaction zone and then is heated to reaction temperature by exchange with a warmer stream, steam or a furnace. The feed then is passed through a reaction zone, which may comprise one or more individual reactors.
- transalkylation effluent or transalkylation product An aromatics-rich stream is recovered as a net column bottoms stream which is referred to herein as the transalkylation effluent or transalkylation product.
- the present invention incorporates a transalkylation catalyst in at least one zone. Conditions employed in the transalkylation zone normally include a temperature of from 100° to 540 0 C. The transalkylation zone is operated at moderately elevated pressures broadly ranging from 100 kPa to 6 MPa absolute. The transalkylation reaction can be effected over a wide range of space velocities, with higher space velocities effecting a higher ratio of para-xylene at the expense of conversion.
- the weight hourly space velocity (WHSV) of the present invention generally is in the range of from 0.1 to 20 hr ⁇ l.
- these transalkylation conditions comprise a temperature from 200° to 300°C, a pressure from 10 to 50 kg/cm ⁇ , and a weight hourly space velocity from 0.5 to 15 IH" 1 .
- the transalkylation effluent is separated into a light recycle stream, a mixed Cg aromatics product and a heavy-aromatics stream.
- the mixed Cg aromatics product can be sent for recovery of para-xylene and other valuable isomers.
- the light recycle stream may be diverted to other uses such as to benzene and toluene recovery, but alternatively is recycled partially to the transalkylation zone.
- the heavy recycle stream contains substantially all of the C9 and heavier aromatics and may be partially or totally recycled to the transalkylation reaction zone.
- transalkylation catalysts that may be suitably used in the present invention.
- a catalytic composite comprising a mordenite component having a Si ⁇ 2/Al2 ⁇ 3 mole ratio of at least 40:1 prepared by acid extracting AI2O3 from mordenite prepared with an initial S1O2/AI2O3 mole ratio of 12:1 to 30:1 and a metal component selected from copper, silver and zirconium.
- US 4,083,866 describes a process for transalkylation of alkylaromatic hydrocarbons that uses a zeolitic catalyst.
- Friedel-Crafts metal halides such as aluminum chloride have been employed with good results and are suitable for use in the present process.
- Hydrogen halides, boron halides, Group I-A metal halides, iron group metal halides, etc. have been found suitable.
- Refractory inorganic oxides combined with the above-mentioned and other known catalytic materials, have been found useful in transalkylation operations. For instance, silica-alumina is described in US 5,763,720. [0021] Crystalline aluminosilicates have also been employed in the art as transalkylation catalysts.
- zeolites that are particularly suited for this purpose include, but are not limited to, zeolite beta, zeolite MTW, zeolite Y (both cubic and hexagonal forms), zeolite X, mordenite, zeolite L, zeolite ferrierite, MFI, and erionite.
- Zeolite beta is especially preferred and is described in US 3,308,069 according to its structure, composition, and preferred methods of synthesis.
- Y zeolites are broadly defined in US 3,130,007, which also includes synthesis and structural details.
- Mordenite is a naturally occurring siliceous zeolite which can have molecular channels defined by either 8 or 12 member rings. Donald W.
- Zeolite L is defined in US 3,216,789, which also provides information on its unique structure as well as its synthesis details.
- Other examples of zeolites that can be used are those having known structure types, as classified according to their three- letter designation by the Structure Commission of the International Zeolite Association ("Atlas of Zeolite Structure Types", by Meier, W. M.; Olsen, D. H; and Baerlocher, Ch., 1996) of MFI, FER, ERI, and FAU.
- Zeolite X is a specific example of the latter structure type that may be used in the present invention.
- the zeolite structure type MTW is also suitable.
- a refractory binder or matrix is optionally utilized to facilitate fabrication of the catalyst, provide strength and reduce fabrication costs.
- the binder should be uniform in composition and relatively refractory to the conditions used in the process.
- Suitable binders include inorganic oxides such as one or more of alumina, magnesia, zirconia, chromia, titania, boria, thoria, phosphate, zinc oxide and silica.
- the zeolite may be present in a range from 5 to 99 wt-% of the catalyst and the refractory inorganic oxide may be present in a range of from 5 to 95 wt-%.
- Preferred transalkylation catalysts are a type Y zeolite having an alumina or silica binder or a beta zeolite having an alumina or silica binder.
- Alumina is an especially preferred inorganic oxide binder.
- the catalyst also contains an optional metal component.
- One preferred metal component is a Group VIII (IUPAC 8-10) metal, preferably a platinum-group metal, i.e., platinum, palladium, rhodium, ruthenium, osmium and iridium. Alternatively a preferred metal component is rhenium. Of the preferred platinum-group, platinum metal itself is especially preferred.
- This optional metal component may exist within the final catalytic composite as a compound such as an oxide, sulfide, halide, or oxyhalide, in chemical combination with one or more of the other ingredients of the composite, or, preferably, as an elemental metal.
- This component may be present in the final catalyst composite in any amount which is catalytically effective, generally comprising 0.01 to 2 wt-% of the final catalyst calculated on an elemental basis.
- the component may be incorporated into the catalyst in any suitable manner such as coprecipitation or cogelation with the carrier material, ion exchange or impregnation. Impregnation using water-soluble compounds of the metal is preferred, for example with chloroplatinic acid or perrhenic acid. Rhenium may also be used in conjunction with a platinum-group metal.
- the catalyst may optionally contain a modifier component.
- Preferred metal modifier components of the catalyst include, for example, tin, germanium, lead, indium, and mixtures thereof. Catalytically effective amounts of such metal modifiers may be incorporated into the catalyst by any suitable manner. A preferred amount is a range of 0.01 to 2.0 wt-% on an elemental basis.
- Gas-phase means units that require addition of hydrogen, and generally contain hydrogen gas phase recycle loop systems around a reactor system.
- An integrated aromatics complex will generally incorporate the transalkylation unit of the present invention along with a reforming unit, an alkyl-aromatic isomerization unit, a para-xylene separation unit, and an optional second transalkylation unit.
- the reforming unit will be used to generate the aromatic species that may be further separated in other units.
- Benzene is transalkylated in combination with A9+ aromatics to form xylenes and ethylbenzene in the transalkylation unit.
- Toluene may be further transalkylated in the optional second transalkylation unit to form additional xylenes in a transalkylation unit which are then processed in a loop comprising the isomerization and para-xylene separation units.
- the para- xylene separation unit may be either a crystallization or adsorptive based separation process well known to the art, which selectively removes the para-xylene in high purity while rejecting a non-equilibrium mixture of other xylenes and ethylbenzene.
- the non-equilibrium mixture depleted in para-xylene, is contacted with an alkylaromatic isomerization catalyst in another process well-known in the art.
- the isomerization process re-equilibrates the mixture back to an equilibrium amount of para-xylene and converts ethylbenzene to xylenes which can be recycled back to the para-xylene separation unit for further recovery.
- a 'loop' This loop is defined herein as a 'para-xylene production' unit, wherein the loop produces para-xylene, which is recovered as a product from the process.
- the flow scheme of the present invention provides a benefit by producing more of the desirable Ag material, which is the valuable xylenes and ethylbenzene.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
La présente invention décrit l’utilisation de deux catalyseurs de transalkylation pour faire réagir des composés aromatiques avec un nombre d’atomes de carbone de neuf (et des nombres d’atomes de carbone plus élevés) avec du benzène pour former des produits aromatiques avec un nombre d’atomes de carbone de huit. Le système à deux catalyseurs préserve les groupes éthyle sur les produits aromatiques plus lourds qui, autrement, perdraient leurs groupes éthyle avec la plupart des catalyseurs de transalkylation en phase gazeuse pour former de l’éthane gazeux indésirable avec du benzène ou du toluène. Ainsi, en utilisant l’étape de transalkylation pour protéger l'éthylbenzène, on peut obtenir un meilleur rendement de paraxylène ou autres produits aromatiques avec un nombre d'atomes de carbone de huit dans un complexe intégré.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2005/004243 WO2006088439A1 (fr) | 2005-02-11 | 2005-02-11 | Procédé pour la fabrication d’éthylbenzène et la transalkylation au xylène |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1846348A1 true EP1846348A1 (fr) | 2007-10-24 |
Family
ID=36916746
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05713284A Withdrawn EP1846348A1 (fr) | 2005-02-11 | 2005-02-11 | Procédé pour la fabrication d éthylbenzène et la transalkylation au xylène |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP1846348A1 (fr) |
WO (1) | WO2006088439A1 (fr) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114426456A (zh) * | 2020-10-10 | 2022-05-03 | 中国石油化工股份有限公司 | 苯与重芳烃烷基转移和甲苯甲基化的组合工艺 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TW504501B (en) * | 1995-02-10 | 2002-10-01 | Mobil Oil Corp | Process for converting feedstock comprising C9+ aromatic hydrocarbons to lighter aromatic products |
-
2005
- 2005-02-11 WO PCT/US2005/004243 patent/WO2006088439A1/fr not_active Application Discontinuation
- 2005-02-11 EP EP05713284A patent/EP1846348A1/fr not_active Withdrawn
Non-Patent Citations (1)
Title |
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See references of WO2006088439A1 * |
Also Published As
Publication number | Publication date |
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WO2006088439A1 (fr) | 2006-08-24 |
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