CN106573855A

CN106573855A - Aromatics production process

Info

Publication number: CN106573855A
Application number: CN201580034836.6A
Authority: CN
Inventors: M·莫立尼尔; K·J·诺布; D·J·斯坦利; T·S·万德博尔; 曹春社; 郑晓波; T·勒卢尔; J·拉乌尔; S·克劳德尔; I·普雷沃; J·皮古瑞尔; C·费尔南德斯
Original assignee: Exxon Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 2014-08-15
Filing date: 2015-06-18
Publication date: 2017-04-19
Anticipated expiration: 2035-06-18
Also published as: CN106573855B; JP2017524039A; JP6615888B2; CN110790625A; CN110790625B; KR101920578B1; KR20170031729A; WO2016025077A1

Abstract

In a process for producing para-xylene, at least one feed comprising C6+ aromatic hydrocarbons is supplied to a dividing wall distillation column to separate the feed into a C7- aromatic hydrocarbon-containing stream, a C8 aromatic hydrocarbon-containing stream and a C9+ aromatic hydrocarbon-containing stream. At least part of the C8 aromatic hydrocarbon- containing stream is then supplied to a para-xylene recovery unit to recover para-xylene from the C8 aromatic hydrocarbon-containing stream and produce a para-xylene depleted stream. The para-xylene depleted stream is contacted with a xylene isomerization catalyst in a xylene isomerization zone under conditions effective to isomerize xylenes in the para- xylene depleted stream and produce an isomerized stream, which is then at least partially recycled to the para-xylene recovery unit.

Description

The production method of aromatic hydrocarbon

Inventor:Michel Molinier、Kevin J.Knob、Dennis J.Stanley、Terri Vander Pol、Chunshe James Cao、Xiaobo Zheng、Thierry Leflour、Jacques Rault、Stephane Claudel、Isabelle Prevost、Jerome Pigourier、Celia Fernandez

Cross-Reference to Related Applications

This application claims in the priority and rights and interests of the U.S. Provisional Application 62/037645 of the submission on the 15th of August in 2014, its Full content is incorporated herein by.

Invention field

The present invention relates to a kind of method for producing aromatic hydrocarbon, the method for particularly producing xylol.

Background of invention

Benzene, toluene and dimethylbenzene (BTX) are important aromatic hydrocarbons, and world wide is continuously increased to their demand. For dimethylbenzene, proportionally increase with the increase of the demand to polyester fiber and thin film especially for the demand of dimethylbenzene Plus, and generally increased with the speed of annual 5-7%.Benzene is unusual value product as chemical raw material.Toluene is also have The petrochemical of value, which is used as the solvent in chemical production processes and intermediate and as high octane gasoline component. However, in many modern aromatics combined units, some or all of benzene and/or toluene pass through transalkylation or methylate or which Combination changes into more dimethylbenzene.

The main source of benzene, toluene and dimethylbenzene (BTX) is catalytic reformate, its by make Petroleum with carrier Hydrogenation/dehydrogenation catalyst contact and produce.Resulting reformate is paraffin hydrocarbon and required C₆To C₈Aromatic compounds are answered Hybrid compound, and the also heavy aromatic hydrocarbon of significant quantity.In removing lightweight (C_5-) after paraffin hydrocarbon component, remaining reformation is produced Thing is usually used multiple distilation steps and is separated into containing C_7-、C₈And C₉₊Fraction.Then can be from containing C_7-Fraction reclaim Benzene, leaves the fraction rich in toluene, should be rich in the fraction of toluene generally by methylating or with part containing C₉₊Fraction alkyl Transfer produces extra C₈Aromatic compounds.Containing C₈Fraction be fed in xylene production loop, wherein generally by absorption Or xylol is reclaimed in crystallization, and the stream of the depleted xylol for obtaining is carried out into catalyzed conversion so that xylene isomerizationization is returned Balanced distribution and the level of ethylbenzene is reduced, otherwise ethylbenzene will be accumulated in xylene production loop.

Although realizing desired chemical reaction to maximize xylol production while reducing valuable aromatics point In terms of the loss of son, catalysis technique becomes more efficiently, but is still constantly needed to realize the section of hardware cost and energy resource consumption Save, to reduce the overall production cost of xylol.

Summary of the invention

According to the present invention, it has now been found that partition distillation column is provided for separating hydrocarbon flow, particularly right at some Run in xylene production combined unit containing C_7-、C₈And C₉₊Fraction effective and energy efficiency measure.

In the first embodiment, C is included by least one₆₊The feedstock of aromatic hydrocarbon is to partition distillation column will enter Material is separated into containing C_7-The stream of aromatic hydrocarbon, containing C₈The stream of aromatic hydrocarbon and contain C₉₊The stream of aromatic hydrocarbon.Then, will at least a portion Containing C₈The stream of aromatic hydrocarbon is fed to paraxylene recovery unit, with from containing C₈The stream of aromatic hydrocarbon reclaims xylol, and produces The stream of depleted xylol, which makes depleted xylol in xylene isomerization Qu Zhong with xylene isomerization catalyst Xylene isomerization contact under conditions of producing isomerization stream in stream.Then, by least one of isomerization stream It is recycled to paraxylene recovery unit.

In another embodiment, the method is also included from containing C_7-At least a portion aliphatic hydrocarbon is removed in the stream of hydrocarbon, To produce C_7-The stream of aromatic hydrocarbon enrichment, which is supplied to separative element with by C_7-The stream of aromatic hydrocarbon enrichment is separated into containing benzene Stream and the stream containing toluene.Stream of at least a portion containing toluene and at least a portion contain C₉₊The stream of hydrocarbon is effectively being produced Contact with transalkylation catalyst under conditions of transalkylated product containing dimethylbenzene, the transalkylated product is sent into two Toluene recovery unit.

It is desirable that the method also include by from (a1 or a2 or a3) containing C₈At least a portion of the stream of aromatic hydrocarbon is supplied Ethylbenzene removal unit should be arrived, the ethylbenzene removal unit is located at the upstream of paraxylene recovery unit and in effectively removing containing C₈Aromatics Operate under conditions of ethylbenzene in the stream of hydrocarbon.It is desirable that the condition in ethylbenzene removal unit will effectively contain C₈The material of aromatic hydrocarbon Stream remain essentially in condition in gas phase, and xylene isomerization area effectively by the stream of depleted xylol substantially It is maintained at liquid phase.

In a third embodiment, will be comprising C₆₊The feedstock of the mixture of aliphatic hydrocarbon and aromatic hydrocarbon to distillation column with Raw material is separated into containing C_7-The stream of hydrocarbon and contain C₈₊The stream of hydrocarbon.From containing C_7-The stream of hydrocarbon remove at least a portion aliphatic hydrocarbon with Produce C_7-The stream of aromatic hydrocarbon enrichment, the C_7-The stream of aromatic hydrocarbon enrichment is supplied to separative element therefrom to reclaim benzo product The raw stream containing toluene.At least a portion contains C₈₊The stream of hydrocarbon is effectively made containing C₈₊Ethylbenzene dealkylation in the stream of hydrocarbon is simultaneously Produce comprising benzene and C₈₊Contact with ethylbenzene dealkylation catalyst under conditions of the dealkylation effluent of hydrocarbon, which is distilled in partition It is separated into containing C in tower_7-The stream of aromatic hydrocarbon, containing C₈The stream of aromatic hydrocarbon and contain C₉₊The stream of aromatic hydrocarbon.Then C will be contained₈Virtue The stream of race's hydrocarbon is sent to paraxylene recovery unit, with from containing C₈In the stream of aromatic hydrocarbon reclaim xylol and produce it is depleted right The stream of dimethylbenzene, which is with xylene isomerization catalyst effectively by the xylene isomerization in the stream of depleted xylol And contact under conditions of producing isomerization stream, isomerization stream is recycled to into partition distillation column.Make the stream containing toluene At least a portion and at least a portion contain C₉₊The stream of hydrocarbon is under conditions of effectively the transalkylated product comprising dimethylbenzene is produced Contact with transalkylation catalyst, the transalkylated product enters separative element.

Description of the drawings

Fig. 1 is the flow chart of the method for being produced xylol according to first embodiment of the invention by catalytic reformate.

Fig. 2 is the flow chart of the method for being produced xylol according to second embodiment of the invention by catalytic reformate.

Fig. 3 is the stream of the method for producing xylol according to the improvement of second embodiment of the invention from catalytic reformate Cheng Tu.

Fig. 4 is the flow chart of the method for being produced xylol according to third embodiment of the invention by catalytic reformate.

Fig. 5 is described for separating C in aromatics combined unit_7-/C₈/C₉₊The partition tower fractionating system of stream.

Fig. 6 is described for separating C in aromatics combined unit_7-/C₈/C₉₊The conventional 2 tower fractionating systems of stream.

Fig. 7 is described for separating the C in aromatics combined unit_7-/C₈/C₉₊3 fraction diverter fractionating systems of stream.

The detailed description of embodiment

Xylol is produced by catalytic reformate needs the fractionating step of a large amount of high costs.In order to reduce investing and operate Cost, the present invention adopt one or more partition distillation column with by various C₆₊Hydrocarbon-fraction is at least separated into containing C_7-The material of aromatic hydrocarbon Stream, containing C₈The stream of aromatic hydrocarbon and contain C₉₊The stream of aromatic hydrocarbon.Then can be from containing C_7-Reclaim benzene in the stream of aromatic hydrocarbon, and first Benzene can be used for by containing C with least a portion₉₊The stream of aromatic hydrocarbon carries out transalkylation to prepare extra dimethylbenzene.Then C will be contained₈The stream of aromatic hydrocarbon and the additional xylenes produced by transalkylation reaction are fed to comprising xylol and reclaim single The xylol production loop of unit and xylene isomerization unit.In reformate feedstocks, contained at least a portion ethylbenzene can lead to Dealkylation is crossed into benzene or by being isomerized to dimethylbenzene, is removed in the upstream or downstream of paraxylene recovery unit.

As its name suggests, term " partition distillation column " refers to the distillation column of the specific form known of partition.Partition is vertical The part divided equally inside distillation column, but the top or bottom of tower are not extended to, therefore, tower is carried out similar to conventional tower Backflow and reboiling.Partition provides the impermeable baffle plate of fluid so as to separate the inside of tower.The entrance of tower is located at partition Side, and one or more side stream positioned at relative side.Partition enables not having the side of entrance in tower with more steady Fixed mode is operated so that for the impact of the fluctuation of inlet flow rate, condition or composition is minimized.The increase of stability can be permitted Remove the method for one or more streams of sideing stream to design and operate the tower in Xu Congta, the stream of sideing stream has and tower top The different composition of stream or bottom of towe stream.

The ability that three or more product streams are prepared from single tower makes it possible to carry out component using less distillation column Separate, and may reduction fund and running cost.Partition distillation column can serve as single distillation column or can use multiple Partition distillation column, can be used with serial or parallel connection arrangement.Partition distillation column can also be tied with one or more conventional distil-lation towers Close and use.When the optimal feed entrance point to tower is higher than most preferably to side stream position, embodiment of the present invention is particularly suitable. If feed entrance point is in conventional distil-lation tower higher than position of sideing stream, the offside fractional composition that flows downward of liquid charging stock in tower With appreciable impact.Charging mobility, the condition of feed stream or the change of composition change the composition that sides stream, and cause stable The production of stream of sideing stream becomes difficult to achieve.

In some embodiments, as shown in Fig. 1,2,3 and 5, replace the shunting of conventional reformation product using partition distillation column Device removes C with fractional distillation from catalytic reformate stream_5-Remaining C after aliphatic hydrocarbon₆₊Hydrocarbon flow.

In some embodiments, as shown in figure 4, the charging of partition distillation column by part by C₆₊Aromatics hydrocarbon flow constitute and Part is made up of the effluent from xylene isomerization unit, when by from C₈₊During aromatic fraction Jing dealkylation removing ethylbenzene Produce the C₆₊Aromatics hydrocarbon flow, the C₈₊Aromatic fraction is from conventional reformate diverter.

It can therefore be seen that partition distillation column is for the various chargings run in modern xylol production combined unit Cost-effective piece-rate system is provided with product stream.

Now with reference to the accompanying drawing present invention more particularly described below.

Fig. 1 show according to first embodiment of the invention be used for prepare xylol method, wherein aromatics will be contained The catalytic reformate feed stream of compound supplies depentanizer region 12 to remove C by pipeline 11_5-Fraction.Pentane and lighter Hydrocarbon removed by pipeline 13, and C₆₊Tower bottom distillate adds in partition distillation column 15 to separate the tower bottom distillate by pipeline 14 Into containing C_7-、C₈And C₉₊The stream of aromatic hydrocarbon.In partition distillation column 15, detached fuel gas is collected via pipeline 20.

C will be contained from partition distillation column 15_7-Stream deliver to extractive distillation or liquid-liquid extraction unit via pipeline 16 17, wherein aliphatic hydrocarbon is removed by pipeline 18, leaves the stream rich in benzene and toluene, and which is fed to alkene saturation via pipeline 19 Area 21.Olefin saturation zone 21 can be the dress of clay or the olefin contaminants in any other effective removing aromatic streams Put, including catalytic process, add with optional hydrogen.Effluent Jing pipelines 22 from olefin saturation zone 21 are fed to another partition Distillation column 23, collects benzene by pipeline 24 from the tower, and toluene adds transalkylation 26, and C via pipeline 25₈₊Fraction leads to Cross pipeline 27 to be added in dimethylbenzene distillation column 28.

From the recovery of reformate partition tower 15 containing C₈The stream of aromatic hydrocarbon is fed to olefin saturation zone 37 by pipeline 29.Alkene Hydrocarbon saturation region 37 can be the device of clay or the olefin contaminants in any other effective removing aromatic streams, including Catalytic process, is added with optional hydrogen.Effluent from olefin saturation zone 37 is fed to dimethylbenzene distillation column by pipeline 38 28.Preferably, from the effluent and C in pipeline 27 of olefin saturation zone 37₈₊The supply centre of fraction is supplied separately and above it To tower 28, this is because the stream in pipeline 38 is more light than the stream in pipeline 27.

Dimethylbenzene distillation column 28 is by tower top depleted C₉₊Stream separate with the charging to distillation column 28.The top stream is then P-xylene separation area 41 is fed to via pipeline 39, wherein xylol is pressed by absorption or Crystallization Separation or combination Usual manner is separated, and Jing pipelines 42 are reclaimed.Residual toluene in top stream is removed simultaneously from p-xylene separation section 41 Transalkylation section 26 is sent into by pipeline 43, and the stream of remaining depleted xylol is added to ethylbenzene by pipeline 40 and removes With xylene isomerization area 44.When by adsorption stripping dimethyl benzene, adsorbent used preferably comprises zeolite.Allusion quotation used Type adsorbent includes naturally occurring or synthetic crystalline aluminosilicate zeolitic, such as X zeolite or Y or its mixture.These zeolites are preferred Exchanged with cation such as alkali metal or alkaline-earth metal or rare-earth cation.Adsorption tower is preferably Simulation moving bed tower (SMB), and Using strippant, such as p-diethylbenzene, to difluorobenzene, diethylbenzene or toluene or its mixture.

In ethylbenzene removing and xylene isomerization area 44, the removing of ethylbenzene is preferably carried out in the gas phase and by taking off alkane Base is melted into benzene or is carried out by being isomerizated into dimethylbenzene.When it is benzene that preferred method is dealkylation, it is possible to use ethylbenzene Any Conventional catalytic method of dealkylation.However, in a preferred embodiment, presence of the dealkylation in catalyst Under carry out, (which has such as U.S. Patent number 4, the restricted index 1 defined in 016,218 catalyst comprising intermediate pore size zeolite 12) and hydrogenation component to, optionally and non-acidic binder, such as silicon dioxide is combined.The example bag of suitable intermediate pore size zeolite Include ZSM-5 (U.S. Patent number 3,702,886 and Re.29,948)；ZSM-11 (U.S. Patent number 3,709,979)；ZSM-12 is (beautiful State's patent No. is 3,832,449)；ZSM-21 (U.S. Patent number 4,046,859)；ZSM-22 (U.S. Patent number 4,556,477)； ZSM-23 (U.S. Patent number 4,076,842)；ZSM-35 (U.S. Patent number 4,016,245)；ZSM-38 (U.S. Patent number 4, 406,859)；ZSM-48 (U.S. Patent number 4,397,827)；ZSM-57 (U.S. Patent number 4,046,685) and the ZSM-58 (U.S. The patent No. is 4,417,780).The example of suitable hydrogenation component includes 8-10 races metal (i.e. Pt, Pd, Ir, Rh, Os, Ru, Ni, Co And Fe), the 14th race's metal (i.e. Sn and Pb), the oxidation of the 15th race's metal (i.e. Sb and Bi) and the 7th race's metal (i.e. Mn, Tc and Re) Thing, hydroxide, sulfide or free metal form (i.e. zeroth order).Noble metal (i.e. Pt, Pd, Ir and Rh) or Re are preferred Hydrogenation component.The combination of this noble metal or non-noble metal catalyzed version, the combination of such as Pt and Sn can be used.As herein It is used, the numbering plan such as Chemical and Engineering News of the race of the periodic table of elements, 63 (5), 27 (1985) institutes It is open.

In a preferred embodiment, by dealkylation catalyst before dealkylation reactor is introduced or anti- Device situ is answered, selectivity deactivates in the following way：Make catalyst and select deactivator, such as in liquid-carrier extremely A kind of few organosilicon contact the catalyst calcination subsequently selectivity deactivated at a temperature of 350-550 DEG C.Selectivity goes The diffusion property of the process change catalyst of activation so that catalyst need at least 50 minutes with 120 DEG C and 4.5 ± Adsorb the 30% of o-Dimethylbenzene balancing capacity under the ortho-xylene partial pressure of 0.8mm mercury column.The selectivity ethylbenzene dealkylation that deactivates is urged One example of agent is described in U.S. Patent number 5, and in 516,956, entire contents are incorporated herein by.

Include for about 400 °F of temperature to about using the appropraite condition of the gas phase dealkylation of the ethylbenzene of above-mentioned catalyst 1000 °F (204 to 538 DEG C), pressure are for about 0 to about 1000psig (100 to 7000kPa), and weight (hourly) space velocity (WHSV) (WHSV) is for about 0.1 To about 200hr^-1, hydrogen is for about 0.5 to about 10 with the mol ratio of hydrocarbon.Preferably, these conversion conditions include about 660 °F to about The temperature of 900 °F (350 DEG C to 480 DEG C), about 50 to about 400psig (446 to 2860kPa) pressure, about 3 arrive about 50hr^-1's WHSV, hydrogen are for about 0.7 to about 5 with the mol ratio of hydrocarbon.Weight of the WHSV based on carbon monoxide-olefin polymeric, i.e. active catalyst and such as The gross weight of the binding agent that fruit uses.The conversion condition is selected to cause containing C₈The raw material of aromatic hydrocarbon is basic in ethylbenzene removing area 44 It is upper to be in gas phase.

In ethylbenzene removing and xylene isomerization area 44, xylene isomerization is it is also preferred that realize in the gas phase.This area Any gas phase catalysis isomerization method known to technical staff can be used in the xylene isomerization in feasible region 44, but one Preferred catalyst system and catalyzing is planted using the intermediate pore size zeolite with the o-Dimethylbenzene scattering nature different from ethylbenzene Removal of catalyst. Therefore, in one embodiment, xylene isomerization catalyst is at 120 DEG C and in the o-Dimethylbenzene of 4.5 ± 0.8mm mercury column Need the 30% of the balancing capacity of o-Dimethylbenzene was absorbed less than 50 minutes under partial pressure.

Select to remove the condition with the xylene isomerization adopted in xylene isomerization region 44 in ethylbenzene, so that depleted Xylene isomerization in the stream of xylol, so as to produce with the stream higher concentration than depleted xylol to two The isomerization stream of toluene.Suitable condition includes the temperature of about 660 °F to about 900 °F (350 DEG C to 480 DEG C), and about 50 to about The pressure of 400psig (446 to 2860kPa), about 3 to about 50hr^-1WHSV, the mol ratio of hydrogen and hydrocarbon is for about 0.7 to about 5. Weight of the WHSV based on carbon monoxide-olefin polymeric, if the i.e. gross weight of active catalyst and the binding agent for using.

Describe in U.S. Patent number 5,516,956 a kind of for operating ethylbenzene removing and xylene isomerization region 44 Method for optimizing.

Remove from ethylbenzene and partition distillation column 15 is supplied by pipeline 45 with the effluent in xylene isomerization region 44, with The effluent is separated into containing C_7-、C₈And C₉₊The stream of aromatic hydrocarbon.

From the recovery of reformate partition distillation column 15 containing C₉₊The stream of aromatic hydrocarbon is fed to heavy aromatic via pipeline 48 Hydrocarbon distillation column 49, which also receives the bottom steam from dimethylbenzene distillation column 28 via pipeline 51.Heavy aromatic hydrocarbon distillation column 49 The C that will be supplied by pipeline 48 and 51₉₊Aromatic hydrocarbon be separated into remove in pipeline 52 containing C₉/C₁₀/ light C₁₁Fraction and contain C₁₁+ Fraction, which passes through pipeline 53 and is fed to gasoline pool, fuel oil sump or dials head tower.Then C will be contained₉/C₁₀/ light C₁₁Fraction 52 Feed together with the stream rich in toluene supplied via pipeline 25 and 43 to transalkylation 26, optionally full by alkene After area, the olefin saturation zone is, for example, any other mode of clay treatment or removing olefin contaminants, including being catalyzed Journey, is added with optional hydrogen.In fig. 1 it is shown that olefin saturation zone is combined in individual unit 26 with transalkylation reaction zone, but The purpose of the schematic diagram is not restricted.Skilled in the art realises that alkene saturation can be in transalkylation Carry out in trip unit detached with transalkylation.Additionally, alkene saturation is only carried out when needed, therefore, if for example Stream 52 needs to remove alkene, and the olefin(e) centent in stream 25 is made except olefin hydrocarbon is unnecessary, then only stream 52 will pass through Olefin saturation zone.

Any transalkylation method well known by persons skilled in the art can be used, but a kind of preferred method is adopted With U.S. Patent number 7, the multistage catalyst system and catalyzing described in 663,010, entire contents are incorporated herein by.This body System includes (i) first catalyst, and which includes first molecular sieve of the restricted index in the range of 3-12, and contains 0.01 to 5 weight At least one source of the first metallic element of 6-10 races and (ii) second catalyst at least one periodic table of elements of amount %, Which includes the second molecular sieve and at least one periodic table of elements 6-10 comprising 0 to 5 weight % with restricted index less than 3 At least one source of the second metallic element of race, wherein first catalyst or the second catalyst are 5:95 to 75:25 model In enclosing, and wherein the first catalyst is located at the upstream of the second catalyst.

For the first catalyst restricted index for 3-12 suitable molecular sieve example include ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57 and ZSM-58, wherein it is preferred that ZSM-5.For the constraint of the second catalyst Index less than 3 suitable molecular sieves example include β zeolites, Y zeolite, super steady Y (USY), dealuminzation Y (Deal Y), modenite, ZSM-3, ZSM-4, ZSM-12, ZSM-18, NU-87 and ZSM-20, wherein it is preferred that ZSM-12.Having in the first and second catalyst Include ferrum, ruthenium, osmium, nickel, cobalt, rhenium, molybdenum, stannum and noble metal such as platinum, rhodium, iridium or palladium with the instantiation of metal.

Transalkylation method can be carried out in any suitable reactor, including radial-flow type, fixed bed, continuously to dirty Or fluidized-bed reactor.Condition in first and second catalyst beds with identical or different, but can generally include 100-1000 DEG C Temperature, preferred 300-500 DEG C of temperature；The pressure of 790 to 7000kPa-a (absolute kPa), preferably in 2170-3000kPa- Pressure in the range of a, hydrogen are 0.01-20, preferred 1-10 with the mol ratio of hydrocarbon；With 0.01 to 100hr^-1WHSV, preferably exist 1-20hr^-1In the range of.

Effluent from transalkylation 26 is fed to regulator 55 via pipeline 54, wherein collecting light gas simultaneously Remove via pipeline 56.Side line stream from regulator 55 is recycled to depentanizer 12, regulator bottom via pipeline 57 Thing is optionally fed to benzene/methylbenzene/C8+ partitions tower 23 by olefin saturation zone 21 by pipeline 58.

Compared with the aromatic compounds combined unit of prior art of partition tower section 15 is replaced using conventional distil-lation unit, One advantage of the embodiment shown in Fig. 1 is to be fed to the reformate C in xylol loop₈The major part of fraction C₉₊Content is removed.In lesser degree, identical advantage is also applied for isomerate C₈Fraction, which also has the C for reducing₉₊Evaporate Divide (if any), will also be removed.Due to from reformer section and the C from both isomerized parts₈Aromatic hydrocarbon evaporates It is all depleted C to divide₉₊, so they can be positioned at the C received from alkyl crosspoint₈The loading tray of aromatics hydrocarbon-fraction Benzenol hydrorefining 28 is sent at the feed column of top.This is in FIG by expecting in the pipeline 38 above stream in pipeline 27 Stream is illustrated.If additionally, the C in pipeline 38 in stream₉₊Content of material in the specification of Disengagement zone 41, then this part or all of material Stream can bypass benzenol hydrorefining 28 and be fed directly into Disengagement zone 41, as shown in dotted line 70.According to real in partition tower section 15 The severity of existing fractional distillation and Disengagement zone 41 are for C₉₊The toleration of compound, it may be considered that the group of any of the above-described selection or both Close.Compared with the prior art aromatics combined unit for not having partition tower, the gross energy for reducing benzenol hydrorefining 28 is disappeared by these options Consumption.

In the improvement (not shown) of method shown in Fig. 1, ethylbenzene removing and xylene isomerization region 44 are divided into into two Single reactor, two reactors are all located at the downstream of p-xylene separation section 41.Two reactors can be in parallel or series Arrangement, in the case of the latter, ethylbenzene elimination reaction device is usually located at the upstream of xylene isomerization reaction device.In the improvement In, ethylbenzene elimination reaction device can be operated under conditions of dramatically different with xylene isomerization reaction device.For example, ethylbenzene removing is anti- Answer device substantially can operate in the gas phase, and xylene isomerization reaction device substantially can operate in the liquid phase it is different to reduce Xylene loss during structure.

Fig. 2 show according to second embodiment of the invention be used for prepare xylol method, between again in which use Wall distillation column replaces conventional reformation product splitter and is removing the C from catalytic reformate stream with fractional distillation_5-Aliphatic hydrocarbon it Remaining C afterwards₆₊Hydrocarbon flow.Therefore in this second embodiment, the catalytic reformate feed stream containing aromatic compounds is by managing Line 111 supplies depentanizer region 112 to remove C_5-Fraction.Pentane and lighter hydrocarbon are removed by pipeline 113, and C₆₊Bottom of towe Fraction is by pipeline 114 into partition distillation column 115 so that tower bottom distillate is separated into containing C_7-、C₈And C₉₊The stream of aromatic hydrocarbon.

By C_7-Stream delivers to extractive distillation or liquid-liquid extraction unit 117 by pipeline 116, and wherein aliphatic hydrocarbon passes through pipeline To leave the stream rich in benzene and toluene, which passes through pipeline 119 and feeds to olefin saturation zone 121 for 118 removings.Olefin saturation zone 121 Can be the device of olefin contaminants in clay or any other effective removing aromatic streams, including catalysis process, with Optional hydrogen is added.Effluent from 121 effluent of olefin saturation zone is fed to another partition distillation column via pipeline 122 123, benzene is collected via pipeline 124 from which, toluene is fed to transalkylation 126, and C via pipeline 125₈₊Fraction passes through Pipeline 127 is connected to dimethylbenzene distillation column 128, is preferably directed towards the bottom of the dimethylbenzene distillation column 128.

It is different from the embodiment shown in Fig. 1, in the second embodiment shown in Fig. 2, from reformate partition tower 115 Reclaim containing C₈The stream of aromatic hydrocarbon is fed to ethylbenzene elimination reaction area 131 by pipeline 129, and which is located at dimethylbenzene distillation column 128 Upstream and separate with xylene isomerization section.Optionally, in pipeline 129 containing C₈The stream of aromatic hydrocarbon can pass through alkene Saturation region is fed to ethylbenzene elimination reaction area 131, and the olefin saturation zone is, for example, clay treatment or removes appointing for olefin contaminants What alternate manner, including catalysis process, are added with optional hydrogen.

As in the implementation of figure 1, the removing of ethylbenzene can be carried out in gas phase or liquid phase, but is preferably entered in the gas phase OK, and by dealkylation carried out for benzene or by being isomerized to dimethylbenzene.When it is benzene that preferred method is dealkylation, Suitable and preferred catalyst and condition with regard to dealkylation is with reference to described by the embodiment of Fig. 1.

The effluent that part 131 is removed from ethylbenzene is fed to deheptanizer 133 via pipeline 132, fuel gas via Pipeline 134 from wherein removing, C₆/C₇Stream is re-introduced into depentanizer region 112, and dimethylbenzene enrichment via pipeline 135 Effluent olefin saturation zone 137 is fed to by pipeline 136, usually clay or any other means are removing alkene Hydrocarbon pollutant, including catalytic process, are added with optional hydrogen.Effluent from olefin saturation zone 137 is fed by pipeline 138 To dimethylbenzene distillation column 128, preferably with pipeline 127 in heavy C₈₊Fraction is separately and above.

The overhead of dimethylbenzene distillation column 128 is fed to p-xylene separation area 141 via pipeline 139, wherein right Dimethylbenzene is generally separated by the combination of absorption or crystallization or both, and is reclaimed by pipeline 142.Residual toluene is by diformazan Benzene separated region 141 is removed, and Jing pipelines 143 send into transalkylation section 126, and stream Jing of remaining depleted xylol is managed Line 140 sends into xylene isomerization region 144.P-xylene separation region 141 substantially with above-mentioned p-xylene separation area Domain 41 is similar.

Xylene isomerization region 144 can be operated in gas phase or liquid phase, but is preferably operated in the liquid phase.This area skill Known to art personnel, any liquid-phase catalysis isomerization method may be used in xylene isomerization region 144, but a kind of excellent The catalyst system and catalyzing of choosing is described in U.S. Patent Application Publication No. 2011/0263918 and 2011/0319688, and both is all interior Appearance is incorporated herein by.

Condition in xylene isomerization section 144 is passed through and is selected, so that the dimethylbenzene in the stream of depleted xylol is different Structure, while keep the stream of depleted xylol to lie substantially in liquid phase, so as to produce with the material than depleted xylol The isomerization stream of the higher para-xylene concentration of stream.Suitable condition includes about 230 DEG C to about 300 DEG C of temperature, about 1300 to The pressure of about 2100kPa and about 0.5 to about 10hr^-1Weight (hourly) space velocity (WHSV) (WHSV).

Effluent from xylene isomerization region 144 is supplied to shunt between as follows via pipeline 145：Jing pipelines 161 are recycled to benzenol hydrorefining 128, are recycled to deheptanizer 133 via pipeline 146 or are redirected into via pipeline 147 Ethylbenzene elimination reaction area 131.Xylene isomerization region in pipeline 145 is flowed between pipeline 161, pipeline 146 and pipeline 147 Go out thing be re-directed to can be optimized according to the ethyl-benzene level of the effluent and overall composition.

From the recovery of reformate partition distillation column 115 containing C₉₊The stream of aromatic hydrocarbon is fed to heavy virtue via pipeline 148 Race hydrocarbon distillation column 149, which also receives the tower base stream from dimethylbenzene distillation column 128 via pipeline 151.Heavy aromatic hydrocarbon distills The C that tower 149 will be supplied by pipeline 148 and 151₉₊Aromatic hydrocarbon be separated into remove in pipeline 152 containing C₉/C₁₀/ light C₁₁Evaporate Point, and contain C₁₁+ fraction, which is provided to gasoline pool by pipeline 153, fuel oil sump or dials head tower.Then C will be contained₉/ C₁₀/ light C₁₁Fraction 152 combined with the stream rich in toluene supplied via pipeline 125 and 143 and be fed to alkyl crosspoint 126, optionally by after olefin saturation zone, the olefin saturation zone is, for example, clay or any other can remove alkene The method of pollutant, including catalytic process, are added with optional hydrogen.In fig. 2, olefin saturation zone is combined with transalkylation zone In individual unit 126, but the purpose of the schematic diagram is not restricted.Skilled in the art realises that alkene saturation can be Carry out positioned at transalkylation upstream and in unit detached with transalkylation.Additionally, alkene saturation is only when needed Carry out, so if such as stream 152 needs to remove alkene, and the olefin(e) centent in stream 125 causes removing alkene unnecessary, Then only stream 152 will be by olefin saturation zone.Suitable transalkylation method is described with reference to figure 1 above embodiment.

Any transalkylation method well known by persons skilled in the art can be used, but a kind of preferred method is adopted With U.S. Patent number 7, the multistage catalyst system and catalyzing described in 663,010, entire contents are incorporated herein by.This body System includes (i) first catalyst, and which includes first molecular sieve of the restricted index in the range of 3-12, and contains 0.01 to 5 weight In at least one periodic table of elements of amount %, at least one source in the first metallic element source of 6-10 races and (ii) second are catalyzed Agent, its include with restricted index less than 3 the second molecular sieve and the periodic table of elements comprising 0 to 5 weight % in 6-10 At least one source of the second metallic element of race, wherein the weight ratio of first catalyst or second catalyst is 5:95 To 75:In the range of 25, and wherein described first catalyst is located at the upstream of second catalyst.

Restricted index for the first catalyst includes ZSM-5, ZSM-11, ZSM- for the example of the suitable molecular sieves of 3-12 22nd, ZSM-23, ZSM-35, ZSM-48, ZSM-57 and ZSM-58, wherein it is preferred that ZSM-5.For the restricted index of the second catalyst The example of the suitable molecular sieves less than 3 include β zeolites, Y zeolite, super steady Y (USY), the Y (DealY) of dealuminzation, modenite, ZSM-3, ZSM-4, ZSM-12, ZSM-18, NU-87 and ZSM-20, wherein it is preferred that ZSM-12.Having in the first and second catalyst Include ferrum, ruthenium, osmium, nickel, cobalt, rhenium, molybdenum, stannum and noble metal such as platinum, rhodium, iridium or palladium with the instantiation of metal.

Transalkylation method can be carried out in any suitable reactor, and including radial-flow type, fixed-bed type is continuous downward Stream or fluidized-bed reactor.Condition in first and second catalyst beds with identical or different, but can generally include 100-1000 DEG C temperature, preferred 300-500 DEG C of temperature；The pressure of 790-7000kPa-a (absolute kPa), preferably in 2170- Pressure in the range of 3000kPa-a, hydrogen are 0.01-20, preferred 1-10 with the mol ratio of hydrocarbon；With 0.01 to 100hr^-1's WHSV, preferably in 1-20hr^-1In the range of.

Effluent Jing pipelines 154 from transalkylation 126 are fed to regulator 155, collect lightweight gas wherein Simultaneously Jing pipelines 156 are removed body.Side line from regulator 155 flows through pipeline 157 and is recycled in depentanizer 112, regulator Bottoms is optionally fed to benzene/methylbenzene/C via olefin saturation zone 121 via pipeline 158₈+ partition tower 123.

As shown in Fig. 1 embodiments, if the C in pipeline 138 in stream₉₊Specification of the content of material in Disengagement zone 141 Interior, then part or all of the stream can bypass benzenol hydrorefining 128 and be fed directly into Disengagement zone 141, such as 170 institute of dotted line Show.

Fig. 3 shows that the various of the process shown in Fig. 2 possibly improve, and identical to indicate using identical reference Component.In such a improvement, to the isomerization C in region 131 (referring to Fig. 2)₈Aromatic hydrocarbon recirculation flow 147 is substituted by The C of depleted xylol₈Aromatic hydrocarbon recirculation flow 163 (referring to Fig. 3), which is obtained in the upstream of isomerization unit 144, and is followed again Circulation 147 is obtained in the downstream of isomerization unit 144.Selected when ethylbenzene to be removed the catalyst used in region 131 as mentioned above When selecting property is deactivated, due to ethylbenzene it is similar with the molecular dimension of xylol, xylene loss tend to charging in two Toluene concentration and increase.Therefore, although o-Dimethylbenzene and meta-xylene are restricted in being diffused into catalyst pores, xylol- As ethylbenzene-easily will react on active site, so as to increase xylene loss.However, due to from Disengagement zone The 141 depleted xylol of effluent, which passes through pipeline 163 and adds ethylbenzene dilute in charging in removing the charging in area 131 Xylol content and the xylene loss for therefore removing area 131 by ethylbenzene will be reduced.

Another kind of improvement shown in Fig. 3 of second embodiment is by a part for the effluent from isomerization section 144 P-xylene separation area 141 is recycled directly to via pipeline 162.When the isomerization zone 144 of liquid phase is producing less benzene to not When operating under conditions of producing benzene, or when this benzene yield does not affect the performance of p-xylene separation part 141, in such as Fig. 2 It is already shown, it can be advantageous that a recirculation part is direct to two via pipeline 161 from the effluent of isomerization section 144 Toluene tower 128.Additionally, when liquid-phase isomerization part 144 is producing less benzene to not producing benzene and the less C of generation₉₊Aromatic compounds Thing is not to producing C₉₊When operating under conditions of aromatic compounds, or when this yield does not affect p-xylene separation part 141 During performance, as shown in Figure 3, it can be advantageous that a part for the effluent from isomerization section 144 is direct via pipeline 162 It is recycled to p-xylene separation section 141.From the benzene yield and C of liquid-phase isomerization₉₊Aromatics yield is generally and unit Operation temperature about and it is also relevant with the ethyl-benzene level of unit feed.Therefore, depending on catalyst in ethylbenzene removing area 131 Efficiency and depending on catalyst in liquid-phase isomerization unit 144 state (liquid-phase isomerization catalyst generally circulation early stage Operate at high temperature at low temperature and in circulation late period), and depending on the absorption used in p-xylene separation area 141 Agent and the type of strippant, can optimize distribution of the liquid-phase isomerization material effluent by pipeline 146,161 and 162.It is such Implement in other process programs that recirculation 162 and 161 can also be envisioned herein.

In the further improvement shown in Fig. 3, gas phase ethylbenzene elimination reaction area 131 is entered optionally by olefin saturation zone Material, replaces with the removing of gas phase ethylbenzene and xylene isomerization region, and the olefin saturation zone is, for example, clay treatment or any other Means are added with optional hydrogen with removing olefin contaminants, including catalytic process.Therefore, except being melted into by ethylbenzene dealkylation Benzene is removed into the ethylbenzene outside dimethylbenzene by ethylbenzene isomerization, and xylene isomerizationization also will be carried out in region 131.Properly The example of ethylbenzene removing/xylene isomerization system of combination be disclosed in above-mentioned U.S. Patent number 5,516,956.It is logical Crossing carries out some xylene isomerizations in region 131, is fed to deheptanizer 133 and and then via pipeline via pipeline 132 136,138 and 139 further to the region 131 of separate section 141 effluent, have higher to two than Fig. 2 methods described Toluene concentration.The ratio of xylol and dimethylbenzene be this means higher than the scheme described in Fig. 2, therefore less point will be needed From unit 141.It should be noted that the idea that xylene isomerization function is added to ethylbenzene removing part also apply be applicable to set herein Other process programs thought.

Another the optional side of improvement from stream 138 to liquid-phase isomerization area 144 as shown in Figure 3 of method shown in Fig. 2 The addition on road 164.When stream 138 contains seldom or do not contain xylol, it is favourable to the xylene isomerization in stream 138 , then dimethylbenzene is recycled in benzenol hydrorefining 128 and Disengagement zone 141 by pipeline 161, to reduce the stream in these parts Amount, so as to reduce the running cost of correlation.When the isomerization efficiency in region 131 is low, this alternative is more particularly suitable for , this is because little or no xylene isomerization catalyst is added in region 131, and therefore region 131 Major function is ethylbenzene removing, if additionally, stream 129 is by 163 serious dilution of stream.

Method shown in Fig. 2 it is as shown in Figure 3 another improvement be from benzenol hydrorefining 128 stream 165 to point From the optional increase of the effluent pipeline 140 in area 141.When in benzenol hydrorefining 128, stream is collected in the position rich in o-Dimethylbenzene When 165, this liquid-phase isomerization area 144 that is recycled to allows the stream with low xylol content to be isomerized to be close to balance Dimethylbenzene and do not cycle through 141st area of separation, therefore can reduce by the flow of the separate section and associative operation into This.This improvement is also applied for other process programs envisioned herein.

Another improvement as shown in Figure 3 of method shown in Fig. 2 is from stream 148 to alkene saturation and transalkylation The optionally increase of bypass stream 166 in area 126.As the C of stream 148₁₁When+content is low, when the end of reformate fraction stream 111 When point is low, this may occur, and at least a portion of the stream 148 can bypass heavy aromatic hydrocarbon tower 149, and via pipeline 166 are directed to alkene saturation and transalkylation reaction zone 126, so as to reduce the fortune by the flow of heavy aromatic hydrocarbon tower 149 and correlation Battalion's cost.This improvement is also applied for the scheme shown in Fig. 1, Fig. 2 and Fig. 4.As it was previously stated, in figure 3, show olefin saturation zone Combined with transalkylation reaction zone in individual unit 126, but the purpose of the schematic diagram is not restricted.Those skilled in the art Known alkene saturation can be carried out in positioned at transalkylation upstream unit detached with transalkylation.Additionally, Alkene saturation is only carried out when needed, so if such as stream 152 and 166 needs to remove alkene, and the alkene in stream 125 Content causes to remove alkene, then only stream 152 and 166 will be by olefin saturation zone.

Another optionally improvement of scheme shown in Fig. 3 is from two isomerized parts i.e. gas phase isomerization area 131 and liquid phase Isomerisation cycle stream is separated in isomerization zone 144.Then can be by these recycle streams according to their C₉Aromatic content is two The different feeds point of toluene tower 128 is provided (referring to the pipe that gas phase isomerization material effluent is fed in Fig. 3 benzenol hydrorefining 128 Line 138 and liquid-phase isomerization material effluent is fed to into benzenol hydrorefining 128 pipeline 161), therefore reduce the size and energy of tower Amount is consumed.

Fig. 4 shows the method for preparing xylol according to third embodiment of the invention, wherein being produced using conventional reformation The fractional distillation of thing diverter removes C from catalytic reformate stream₅Remaining C after-aliphatic hydrocarbon₆₊Hydrocarbon flow.Therefore, in the 3rd embodiment party In case, the reformate feed stream containing aromatic hydrocarbon is supplied depentanizer area 202 to remove C by pipeline 201₅- fraction.Pentane and Lighter hydrocarbon is removed by pipeline 203, and C₆₊Tower bottom distillate adds conventional reformate diverter 205 by pipeline 204, with Bottom fraction is separated into containing C₇- and C₈₊The stream of aromatic hydrocarbon.

From the C of reformate diverter 205₇- stream delivers to extractive distillation or liquid-liquid extraction unit via pipeline 206 207, wherein aliphatic hydrocarbon is removed by pipeline 208 to leave the stream rich in benzene and toluene, its pass through pipeline 209 deliver to alkene satisfy With area 211.Olefin saturation zone 211 can be clay or any other olefin contaminants effectively removed in aromatic stream Device, including catalytic process added with optional hydrogen.Effluent from olefin saturation zone 211 is fed to by pipeline 212 Partition distillation column 213, adds transalkylation 216, C by pipeline 215 from benzene, toluene is wherein collected by pipeline 214₈₊Evaporate Divide and dimethylbenzene distillation column 218 is added by pipeline 217.

Contain C from what reformate diverter 205 was reclaimed₈₊The stream of aromatic hydrocarbon is fed to ethylbenzene removing by pipeline 219 Area 221, optionally by olefin saturation zone, such as clay treatment or any other mode are removing olefin contaminants, including catalysis Process, is added with optional hydrogen.Ethylbenzene removing in region 221 turns to benzene and light (C by de- ethyl preferably as described above₂) Gas, is preferably carried out in the gas phase.Or, ethylbenzene removing can also be carried out by way of being isomerized to dimethylbenzene.

The effluent that section 221 is removed from ethylbenzene is fed to another partition distillation column 223 by pipeline 222, via pipeline 224 from wherein removing fuel gas, C₆/C₇Stream is re-introduced to depentanizer section 202, C via pipeline 225₉₊Stream via Pipeline 227 is fed to heavy aromatic hydrocarbon tower 226, and the C rich in dimethylbenzene₈Stream is fed to alkene saturation via pipeline 228 Area 229, typically any technique that can remove olefin contaminants, including Catalytic processes, are added with optional hydrogen.It is full from alkene P-xylene separation area 232 is fed to via pipeline 231 with the effluent in area 229, which is also received from diformazan via pipeline 233 The overhead of benzene distillation tower 218.Xylol generally passes through absorption or crystallization or its combination in p-xylene separation area 232 Middle separation, and reclaim via pipeline 234.Residual toluene is separated from p-xylene separation area 232, and Jing pipelines 235 send Enter transalkylation reaction zone 216, while the stream of remaining depleted xylol is fed to xylene isomerization area via pipeline 237 236。

Any Xylene isomerization process well known by persons skilled in the art may be used to xylene isomerization area 236 In, but a kind of preferred method is to carry out and use catalyst system and catalyzing, such as U.S. Patent Application Publication No. 2011/ in the liquid phase Described in 0263918 and 2011/0319688, both of which content is incorporated herein by.

Effluent from xylene isomerization area 236 is supplied by pipeline 238 between being recycled to by pipeline 239 Wall distillation column 223 imports shunting between ethylbenzene removing area 221 again via pipeline 241.When ethylbenzene removes area 221 very high When conversion ratio (about 50% or higher) is operated, the slip-stream for importing ethylbenzene removing area again by pipeline 241 will be very little, and big portion Divide isomerization section effluent redirect to partition distillation column 223 via pipeline 239.

From the C of partition distillation column 223₉₊Stream is fed to heavy aromatic hydrocarbon distillation column 226 by pipeline 227, its also Jing Tower base stream from dimethylbenzene distillation column 218 is received by pipeline 242.Heavy aromatic hydrocarbon distillation column 226 is by 227 He of pipeline The C of 242 supplies₉₊Aromatic hydrocarbon be separated into remove in pipeline 243 containing C₉/C₁₀Fraction and and contain C₁₁Fraction, its pass through pipe Line 244 is fed to gasoline pool.Then optionally polluted by olefin saturation zone such as clay treatment or any other removing alkene After the means of thing, including catalytic process, add with optional hydrogen, C will be contained₉/C₁₀Fraction 243 provide with Jing pipelines 215 The stream rich in toluene send into transalkylation 216 together.In fig. 4 it is shown that olefin saturation zone and transalkylation reaction zone Combine in individual unit 216, but the purpose of the schematic diagram is not restricted.Alkene saturation known to those skilled in the art Can carry out in positioned at transalkylation upstream unit detached with transalkylation.Additionally, alkene saturation only exists Carry out when needing, so if such as stream 243 needs to remove alkene, and the olefin(e) centent in stream 215 causes to take off Except alkene, then only stream 243 will be by olefin saturation zone.

Any transalkylation method well known by persons skilled in the art may be used in transalkylation 216, but A kind of preferred method adopts U.S. Patent number 7, the multistage catalytic system described in 663,010, as above in the face of Fig. 1 embodiments It is described.

Effluent from transalkylation 216 is fed to regulator 246 via pipeline 245, wherein collecting lightweight gas Body is simultaneously removed via pipeline 247.Side line stream from regulator 246 is recycled to depentanizer 202 via pipeline 249, stable Device bottoms is fed to partition distillation column 213 via pipeline 248, optionally passes through olefin saturation zone 211.

As can be seen that in second shown in Fig. 2 to 4 and the 3rd embodiment, for flowing out dividing for thing from reformate Evaporate the C rich in EB of middle recovery₈Mixture of aromatic compounds carries out ethylbenzene removing in region 131, in 221, and be directed to it is depleted right The stream of dimethylbenzene carries out xylene isomerization in specific-use section 144, in 236.It is different with dimethylbenzene that this arrangement removes ethylbenzene Structureization departs from, so that the isomerization of the dimethylbenzene stream of substantial amounts of depleted para-position is carried out in the liquid phase (without gas phase Isomerization unit), and EB removings are carried out in the gas phase for a small amount of stream rich in EB.It reduce and divide from xylol From the reboiling of the liquid efflunent in area 141,232, (which is the isomery of the dimethylbenzene of depleted para-position in gas phase isomerization unit Required for changing) related cost, when two kinds of catalytic reactions are carried out in same unit 44, as shown in Figure 1.Further, since Liquid-phase isomerization catalyst is typically free of metal and gas phase isomerization catalyst includes the base metal such as rhenium of noble metal or costliness, Therefore xylene isomerization is separated the cost for reducing catalyst with ethylbenzene removing.Further total xylene can be increased to return Road efficiency, this is because the condition of each technique can be provided independently from, to maximize which in whole factory's service life Yield and efficiency.

(illustrated in the Fig. 7 being described below) according to the 4th embodiment, can be by being replaced with conventional distil-lation tower Improving the scheme shown in Fig. 1 to 3, which allows to separate three fraction first partition tower 15,115：That is C_7-Fraction as top point, C₈Fraction is used as sideing stream and C₉₊Fraction is used as bottom fraction.When by C₈Level is distributed into EB removings area 131 (Fig. 2 or 3) or 211 (Fig. 4), when, the solution causes C₈More C in fraction₉Ethylbenzene removal unit is sent to, with the situation phase using partition tower Than.Some C₉Component will by dealkylation be toluene, therefore transalkylation charging in toluene/C₉₊Ratio will increase, and virtue Benzene in race's combined unit/PX ratios will also increase, and this is interesting when target is more benzene productions, and condition is Catalyst system and catalyzing in EB removal units can process heavier raw material, and the EB without EB removal units described in appreciable impact is removed Efficiency.In this case, C₉₊Fraction can be containing some remaining C₈Aromatic compounds, and heavy virtue should be directed into Race's hydrocarbon distillation column is directed to dimethylbenzene distillation column.

Some config options are not described herein, but in scope disclosed by the invention, i.e.,：A () is in figure below In shown scheme, the partition tower 23 in Fig. 1, the partition tower 213 in partition tower 123 and Fig. 4 in Tu2 ＆3 can use benzene and first The conventional equipment of benzene column replaces；The partition tower 115 in partition tower 15 and Tu2 ＆3 of (b) in the scheme shown in figure below, in Fig. 1 Can be replaced with the device of conventional light reformate diverter and heavy reformate splitter column, as shown in Figure 6；(c) Below in the scheme shown in Tu2 ＆3, EB removal units 131 (Fig. 2) or EB are removed and xylene isomerization unit 131 (Fig. 3) Can be optionally located between the de- pentane device 112 and partition tower 115 in stream 114, rather than the partition tower in stream 129 115 downstream；(d) similarly, in the scheme shown in Fig. 4 below, EB removes unit 221 and can be optionally located at logistics 204 On de- pentane device 202 and reformate diverter 205 between, rather than under the reformate diverter 205 in stream 219 Trip.

Referring now to the following non-limiting example present invention more particularly described below.

Embodiment 1

This embodiment illustrates and the conventional light and heavy reformate diverter in the allocation plan described in Fig. 1 to 3 (Fig. 6) compare, with the benefit of partition tower (Fig. 5).

The embodiment is rich in based on 85 weight % obtained from the reformation of the feed naphtha with following carbon number distribution C₆₊The stream of aromatic hydrocarbon：

C7-	17%
		C7	31%
C8	32%
		C9+	20%

With reference to Fig. 5, by 220t/h rich in C₆₊The charging (stream 301) of aromatic hydrocarbon is fed to partition tower 302, its Operate under conditions of 83 DEG C of the pressure of 1.4kPa, condenser temperature, and 209 DEG C of reboiler temperature.Partition tower (DWC) 302 contains There are 58 theoretical trays, including condenser (N ° 1 of plate) and reboiler (N ° 58 of plate).DWC technologies are related in charging or prefractionation device, And the vertical separation between the product side of three product towers.The separation of low boiler cut and high boiling fraction occurs in feed side, The separation of intermediate boiling fraction occurs in product side.The prefractionation device side of DWC distributes interim key thing between the top and the bottom, permits Perhaps very big motility come match at the top of king-tower and bottom composition.

In the embodiment shown in fig. 5, the vertical wall 303 in partition tower 302 extends downwardly into N ° of column plate for N ° 11 from column plate 37, and allow for each in these column plates to be separated into 2 regions：Feed zone and extraction area positioned at wall per side.By rich C6+ Aromatic hydrocarbon feed stream 301 is introduced in partition tower 302 at N ° of 13 plates of the feed zone side of wall section.Partition tower 302 is allowed in N ° 1 of plate The upper C produced as liquid distillation_7-Fraction (stream 304), as sideing stream for N ° 23 of the plate extracted out on area side 303 in wall C₈Fraction (stream 305) and C₉₊Fraction (stream 306) is used as tower bottom product.Condensation is carried out using air cooler, is removed 30MW, guarantees reboiling by heating medium, and 33.3MW heats, and preferably above partition are provided under 214 DEG C of minimum temperature 15 DEG C of the bottom temp of tower 302.

The fractionation performance of partition tower 302 is summarized as follows：

Toluene recovery rate (is defined as C_7-Toluene in fraction (stream 304) is divided by the toluene in charging (stream 301)) be 99.9 weight %.

C₈The aromatic hydrocarbon response rate (is defined as C₈EB+PX+MX+OX in fraction (stream 305) is divided by charging (stream 301) EB+PX+MX+OX) for 99 weight %.

C₈C in fraction (stream 305)₉Aromatic content is 5 weight %.

In order to realize above-mentioned separating property, 2 distillations that conventional fractionation will need to implement using series connection as shown in Figure 6 Tower.Therefore, with reference to Fig. 6, by the rich C of 220t/h₆₊Aromatic hydrocarbon feedstock (stream 401) is fed to N ° of the column plate of the first distillation column 402 On 15.First distillation column 402 contains 29 theoretical trays, and in the pressure of 1.4kPa, 83 DEG C of condenser temperature and 175 DEG C Reboiler temperature under work.Condensation is carried out using air cooler, removes 26.7MW, guarantees reboiling by heating medium, 29.6MW heats, preferably 15 DEG C higher than the bottom temp of the first tower of temperature are provided under 180 DEG C of minimum temperature.First distillation Tower 402 allows to be incorporated as the C for liquid distillation in N ° of 1 last time of plate_7-Fraction (stream 403) and as the C of tower bottom product₈₊Fraction (stream 404).

The fractionation performance of the first distillation column 402 is summarized as follows：

Toluene recovery rate (is defined as C_7-Toluene in fraction (stream 403) is divided by the toluene in charging (stream 401)) be 99.9 weight %.

C₈The aromatic hydrocarbon response rate (is defined as C₈₊EB+PX+MX+OX in fraction (stream 404) is divided by charging (stream 401) EB+PX+MX+OX in) for 99.5wt%.

The tower bottom product (stream 404) of the first distillation column 402 is fed to containing 29 theoretical trays, in the pressure of 1.4kPa 144 DEG C of power, condenser temperature, the after-fractionating tower 405 worked under the conditions of 197 DEG C of reboiler temperature.Condensation is cooled down using air Device is carried out, and removes 13.7MW, guarantees reboiling by heating medium, and 19.5MW heats are provided under 202 DEG C of minimum temperature, excellent Temperature of the choosing than high 15 DEG C of the bottom temp of the second tower.After-fractionating tower 405 allows to be incorporated as liquid distillation in N ° of 1 last time of plate C₈Fraction (stream 406) and as the C of tower bottom product₉₊Fraction (stream 407).

The fractionation performance of after-fractionating tower 405 is summarized as follows：

C₈The aromatic hydrocarbon response rate (is defined as C₈EB+PX+MX+OX in fraction (stream 406) is divided by charging (stream 404) EB+PX+MX+OX) for 99.5wt%.

C₈C in fraction (stream 406)₉Aromatic content is 5 weight %.

Therefore, the fractionation performance of the system being made up of 2 fractionating columns (Fig. 6) connected similar to partition tower (Fig. 5) point Evaporate performance.However, compared with the conventional equipment shown in Fig. 6, the next door tower energy efficiency shown in Fig. 5 is higher, because performing identical The heat demand of fractionation performance is reduced to 33.3MW from 49.1MW.Compared with conventional equipment, another advantage of partition tower is Reduce the half of the fractionating system hardware (number of tower, reboiler etc.) needed for obtaining needed for fractionation performance.

Embodiment 2

With reference now to Fig. 7, this embodiment illustrates implement 3 fraction distillation column in the allocation plan shown in Fig. 1 to 3 and not It is effect of the partition tower as reformate diverter 15,115.

In the embodiment of Fig. 7, containing 58 theoretical trays and in 1.4kPa, condenser temperature is 83 DEG C, then is boiled Device temperature is the rich C that 220t/h is supplied on N ° 20 of the plate of the 3- fraction distillation column 502 worked at 202 DEG C₆₊Aromatics hydrocarbon charging (stream 501).The 3- fraction distillation column 502 produces the C as liquid distillation on N ° 1 of plate_7-Fraction (stream 503), from N ° 40 work of tower For the C for sideing stream₈Fraction (stream 504) and C₉₊Fraction (stream 505) is used as bottom product.Using the air cooling of removing 31MW Device is condensed, and guarantees reboiling by heating medium, provides 33.7MW heats, preferably in height under 207 DEG C of minimum temperature In 15 DEG C of distillation column bottom temp.

Compared with the partition tower in embodiment 1, the fractionation performance of 3- fraction distillation column 502 declines, and is summarized as follows：

Toluene recovery rate (is defined as C₇Toluene in fraction (stream 503) is divided by the toluene in charging (stream 501)) be 99.9 weight %.

C₈The aromatic hydrocarbon response rate (is defined as C₈EB+PX+MX+OX in fraction (stream 504) is divided by charging (stream 501) EB+PX+MX+OX) for 87 weight %.

C₈C in fraction (stream 504)₉Aromatic content is 15 weight %.

However, the ethylbenzene response rate realized with 3- fraction distillation column (98 weight %) (is defined as C₈EB in fraction divided by EB in charging) similar to the partition tower (98.5 weight %) in embodiment 1.

The performance of the distillation scheme of embodiment 1 and embodiment 2 is summarized in table 1 below, and wherein Qr represents heat demand.

The disclosures of all patents, test program and other files (including priority document) are by quoting completely simultaneously Enter, if this disclosure not contradiction and allow it is this be incorporated to had jurisdiction.

Although having specifically described illustrative form disclosed herein, without departing from spirit and scope of the present disclosure In the case of, the various other modifications that will be readily apparent to one having ordinary skill and easily can make can be by Understand.And it is therefore not desirable to scope of the following claims is limited to embodiments described herein and description, but claim All features of the patentability novelty being present herein are interpreted as including, including all features that will be processed as this The equivalent of open those skilled in the art.

When numerical lower limits and numerical upper limits are listed herein, cover the scope from any lower limit to any upper limit, and clearly Ground is within the scope of the invention.Term " including " is synonymous with term " including ".Similarly, compositionss are worked as, before element or component group When there is transitional phrases " including " in face, it will be appreciated that we are further contemplated in compositionss, component or enumerating for component had before Cross phrase " substantially by ... constitute ", " by ... constitute ", " be selected from ... and constitute " or " being ", vice versa.

Claims

1. a kind of method for producing xylol, methods described include：

(a1) will be comprising C₆₊At least one raw material supply of aromatic hydrocarbon is to partition distillation column so that the raw material is separated into containing C_7-Virtue The stream of race's hydrocarbon, containing C₈The stream of aromatic hydrocarbon and contain C₉₊The stream of aromatic hydrocarbon；

(b1) by described containing C₈At least a portion of the stream of aromatic hydrocarbon is fed to paraxylene recovery unit, with from described containing C₈ Xylol is reclaimed in the stream of aromatic hydrocarbon and the stream of depleted xylol is produced；

(c1) xylene isomerization in the stream for effectively making the depleted xylol simultaneously produces the condition of isomerization stream Under, at least a portion and xylene isomerization catalyst of the stream of the depleted xylol are made in xylene isomerization area Contact；With

(d1) at least a portion of the isomerization stream is recycled to into the paraxylene recovery unit.

2. the method described in claim 1, wherein the described at least one raw material to (a1) is included by from reformate streams Middle removing C_5-The C that hydrocarbon is produced₆₊The mixture of aromatics and aliphatic hydrocarbon.

3. the method described in claim 2, also includes：

(e1) from described containing C_7-At least a portion aliphatic hydrocarbon is removed in the stream of aromatic hydrocarbon, to produce C_7-The material of aromatic hydrocarbon enrichment Stream.

4. the method described in claim 3, also includes：

(f1) by the C_7-At least a portion of the stream of aromatic hydrocarbon enrichment is fed to separative element therefrom to reclaim benzo generation Stream containing toluene；

(g1) under conditions of effectively the transalkylated product containing dimethylbenzene is produced, make at least one of the stream containing toluene Divide and described containing C₉₊At least a portion of the stream of aromatic hydrocarbon is contacted with transalkylation catalyst；With

(h1) at least a portion of the transalkylated product is fed to into the separative element in (f1).

5. the method described in claim 4, wherein the separative element in (f1) includes other partition distillation column.

6. the method any one of claim 1-5, also includes：

(i1) by described containing C₈At least a portion of the stream of aromatic hydrocarbon is fed to ethylbenzene removing area；With

(j1) it is described containing C in effectively removing₈In the stream of aromatic hydrocarbon under conditions of at least a portion ethylbenzene, make described containing C₈Aromatics The stream of hydrocarbon is contacted in ethylbenzene removing area with the first catalyst.

7. the method described in claim 6, wherein the condition in ethylbenzene removing area is effectively by described containing C₈The material of aromatic hydrocarbon Stream remains essentially in gas phase.

8. the method described in claim 7, wherein ethylbenzene removing area is located at the upstream of the paraxylene recovery unit.

9. the method described in claim 7, wherein ethylbenzene removing area is located at the downstream of the paraxylene recovery unit.

10. the method described in claim 8 or 9, wherein ethylbenzene removing area is also containing effectively making institute under the described conditions State containing C₈Second catalyst of the xylene isomerization in the stream of aromatic hydrocarbon.

Method any one of 11. claim 1-10, wherein the condition in the xylene isomerization area effectively will The stream of the depleted xylol remains essentially in liquid phase.

Method any one of 12. claim 1-10, wherein the condition in the xylene isomerization area effectively will The stream of the depleted xylol remains essentially in gas phase.

A kind of 13. methods for producing xylol and benzene, the method include：

(a2) will be comprising C₆₊The raw material supply of aliphatic hydrocarbon and the mixture of aromatic hydrocarbon is to partition distillation column so that the raw material to be separated Into containing C_7-The stream of hydrocarbon, containing C₈The stream of hydrocarbon and contain C₉₊The stream of hydrocarbon；

(b2) contain C from described_7-At least a portion aliphatic hydrocarbon is removed in the stream of hydrocarbon, to produce C_7-The stream of aromatic hydrocarbon enrichment；

(c2) by the C_7-At least a portion of the stream of aromatic hydrocarbon enrichment is fed to separative element with by the C_7-Aromatic hydrocarbon is rich The stream of collection is separated into the stream containing benzene and the stream containing toluene；

(d2) by described containing C₈At least a portion of the stream of hydrocarbon is fed to paraxylene recovery unit, with from described containing C₈Hydrocarbon Stream reclaims xylol and produces the stream of depleted xylol；

(e2) xylene isomerization in the stream for effectively making the depleted xylol simultaneously produces the condition of isomerization stream Under, at least a portion and xylene isomerization catalyst of the stream of the depleted xylol are made in xylene isomerization area Contact；

(f2) at least a portion of the isomerization stream is recycled to into paraxylene recovery unit；

(g2) under conditions of effectively the transalkylated product containing dimethylbenzene is produced, make at least one of the stream containing toluene Divide and described containing C₉₊At least a portion of the stream of hydrocarbon is contacted with transalkylation catalyst；With

(h2) at least a portion dimethylbenzene in transalkylated product is fed to into paraxylene recovery unit.

Method described in 14. claim 13, wherein to (a2) the raw material by C is removed from reformate streams_5-Hydrocarbon And produce.

Method described in 15. claim 13 or 14, also includes：

(i2) will be from the described containing C of (a2)₈At least a portion of the stream of aromatic hydrocarbon is fed to and reclaims positioned at the xylol The ethylbenzene removing area of unit upstream；With

(j2) it is described containing C in effectively removing before (d2)₈In the stream of aromatic hydrocarbon under conditions of at least a portion ethylbenzene, in institute Make in stating ethylbenzene removing area described containing C₈The stream of aromatic hydrocarbon is contacted with the first catalyst.

Method described in 16. claim 15, wherein ethylbenzene removing area is also described comprising effectively making under the described conditions Containing C₈Second catalyst of the xylene isomerization in the stream of aromatic hydrocarbon.

Method described in 17. claim 15 or 16, wherein the condition in ethylbenzene removing area is effectively by described containing C₈Aromatics The stream of hydrocarbon remains essentially in gas phase.

Method any one of 18. claim 13-17, also includes：

(k2) at least a portion of the stream of the described depleted xylol from (d2) is fed to different positioned at the dimethylbenzene The ethylbenzene removing area of structure region upstream；With

(l2) before (e2) under conditions of at least a portion ethylbenzene in the stream for effectively removing the depleted xylol, The stream of the depleted xylol is made to contact with the first catalyst in the ethylbenzene removing area.

Method described in 19. claim 18, wherein the condition in ethylbenzene removing area effectively will be described depleted to diformazan The stream of benzene remains essentially in gas phase.

Method any one of 20. claim 13-19, wherein the condition in the xylene isomerization area effectively will The stream of the depleted xylol remains essentially in liquid phase.

Method any one of 21. claim 13-20, wherein will be from least a portion of (g2) transalkylation Product is fed to the separative element in (c2), and the separative element effectively divides from the transalkylated product From dimethylbenzene, and by the C_7-The stream of aromatic hydrocarbon enrichment is separated into the stream containing benzene and the stream containing toluene.

Method any one of 22. claim 13-21, wherein the separative element in (c2) includes other partition Distillation column.

Method described in 23. claim 22, also includes：

(m2) from the other partition distillation column removing C₈₊Hydrocarbon residue stream；With

(n2) by the C₈₊At least a portion of hydrocarbon residue stream is fed to paraxylene recovery unit.

A kind of 24. methods for producing xylol and benzene, the method include：

(a3) will be comprising C₆₊The raw material supply of the mixture of aliphatic hydrocarbon and aromatic hydrocarbon is contained to distillation column so that the raw material is separated into C_7-The stream of hydrocarbon and contain C₈₊The stream of hydrocarbon；

(b3) from described containing C_7-At least a portion aliphatic hydrocarbon is removed in the stream of hydrocarbon, to produce C_7-The stream of aromatic hydrocarbon enrichment；

(c3) by the C_7-At least a portion of the stream of aromatic hydrocarbon enrichment is fed to piece-rate system therefrom to reclaim benzo generation Stream containing toluene；

(d3) effectively make it is described containing C₈₊Ethylbenzene dealkylation generation in the stream of hydrocarbon is comprising benzene and C₈₊The de- alkyl of hydrocarbon Under conditions of changing effluent, make described containing C₈₊At least a portion of the stream of hydrocarbon is contacted with ethylbenzene dealkylation catalyst；

(e3) the dealkylation effluent is fed to partition distillation column the dealkylation effluent is separated into containing C_7- The stream of aromatic hydrocarbon, containing C₈The stream of aromatic hydrocarbon and contain C₉₊The stream of aromatic hydrocarbon；

(f3) by described containing C₈At least a portion of the stream of aromatic hydrocarbon is fed to paraxylene recovery unit, with from described containing C₈ Xylol is reclaimed in the stream of aromatic hydrocarbon and the stream of depleted xylol is produced；

(g3) xylene isomerization in the stream for effectively making the depleted xylol simultaneously produces the condition of isomerization stream Under, at least a portion of the stream of the depleted xylol is contacted with xylene isomerization catalyst；

(h3) at least a portion of the isomerization stream is recycled to into the partition distillation column；

(i3) under conditions of effectively the transalkylated product containing dimethylbenzene is produced, make at least one of the stream containing toluene Divide and described containing C₉₊At least a portion of the stream of hydrocarbon is contacted with transalkylation catalyst；With

(j3) at least a portion of the transalkylated product is fed to into the piece-rate system in (c3), wherein described point Also effectively dimethylbenzene is separated from the transalkylated product from (i3) from system.

Method described in 25. claim 24, wherein the piece-rate system in (c3) includes other partition distillation column.