CN106488897A - The method preparing dimethylbenzene - Google Patents

Abstract

In the method preparing xylol, C will be comprised₆₊The feed steam of aromatic hydrocarbons is separated into the stream containing toluene, containing C₈The stream of aromatic hydrocarbons and contain C₉₊The stream of aromatic hydrocarbons.The stream containing toluene is made to contact methylating agent so that as dimethylbenzene and prepared by toluene conversion the effluent stream that methylates.By xylol from containing C₈Aromatic stream and the effluent stream that methylates reclaim to prepare the stream of depleted xylol in xylol exhausting section, then its by the effective isomerization of dimethylbenzene in the stream of depleted xylol and prepare isomerization stream liquid-phase condition under contact xylene isomerization catalyst.C will be contained₉₊Stream and transalkylation catalyst in effective conversion C₉₊Aromatic compounds are to C_8‑Aromatic compounds and contacting under conditions of preparing transalkylation stream, it is recycled to xylol exhausting section together with isomerization stream.

Description

The method preparing dimethylbenzene

Inventor:Michel Molinier, Jeevan S.Abichandani, Jeffrey L.Andrews, Timothy P.Bender, Robert G.Tinger, Dennis J.Stanley, George J.Wagner

Mutually the quoting of related application

This application claims on June 30th, 2014 submit to the U.S. Provisional Application of Application No. US62/018,726 and The priority of the european patent application of Application No. EP 14180052.4 and rights and interests that August in 2014 is submitted on the 6th, all this They are generally introduced this specification as reference by a little applications.Association request is the US 62/018 that on June 30th, 2014 submits to, 724 U.S. Provisional Application (there is docket number 2014EM155) and the application number of _ _ _ _ _ _ _ _ _ _ _ submission For _ _ _ _ _ _ _ _ _ _ _ U.S. Patent application (there is docket number 2015EM128).

Technical field

The present invention relates to preparing dimethylbenzene and the method especially preparing xylol.

Background technology

The main source of dimethylbenzene is catalytic reformate, and it is by hydrogenation/dehydrogenation catalyst on Petroleum contact carrier Preparation.Produced reformate is paraffin hydrocarbon and C in addition to substantial amounts of heavy arene₆-C₈The COMPLEX MIXED of aromatic compounds Thing.Removing lightweight (C₅-) after paraffin hydrocarbon component, the remainder of reformate is generally used multiple distilation steps and separates Become to contain C_7-、C₈And C₉₊Fraction.Then benzene can be from containing C_7-Fraction reclaim to leave the component rich in toluene, it is general Contain C for by toluene disproportionation and/or with part₉₊The transalkylation of the fraction of-aromatic compounds and prepare other C₈Aromatics Compound.Containing C₈Fraction be delivered to dimethylbenzene preparation loop, wherein reclaim xylol, general pass through absorption or crystallize, And generated depleted xylol stream accept catalyzed conversion with just this xylene isomerizationization return balanced distribution direction. Then generated isomerization of xylenes stream can be recycled to paraxylene recovery unit.

Although benzene and toluene are important aromatic hydrocarbons, for dimethylbenzene, especially xylol demand exceed for benzene with And the demand of toluene and current annual rate of growth are 5-7%.Therefore always exploitation is maximized to the production, simultaneously of xylol There is demand in the aromatic compounds technology of preparing of related capital construction and production cost minimum.

Content of the invention

According to of the present invention, developed prepare xylol optionally together with benzene and/or o-Dimethylbenzene changing together Enter method, the unit that wherein will methylate adds xylol to produce in complex with by reformate or similar aromatic fraction In toluene and/or benzene be converted into extra dimethylbenzene.This unit style that methylates standby rich in xylol but almost do not have or do not have There is the C of extra ethylbenzene₈Aromatic products.As a result, the production of dimethylbenzene segregation section and running cost can reduce and at least The xylene isomerization section of a part can be with the lower liquid phase process of use cost.If necessary, by adding gas phase isomerization Unit and/or by convey a part of depleted xylol stream to transalkylation and/or by using conventional skill Art is such as distilled or ethylbenzene is separated by film or selective absorption or a combination thereof from dimethylbenzene stream, can avoid The accumulation of ethylbenzene in xylene production loop.

Thus, on the one hand, the present invention relates to the method preparing xylol, wherein will comprise C₆₊The feed steam of aromatic hydrocarbons is extremely It is separated into the stream containing toluene less, containing C₈The stream of aromatic hydrocarbons and contain C₉₊The stream of aromatic hydrocarbons.It is being diformazan effectively by toluene conversion Benzene and preparation methylate under conditions of effluent stream, make the stream that at least a portion contains toluene contact methylating agent.From containing C₈The stream of aromatic hydrocarbons and the effluent stream that methylates reclaim xylol to prepare the stream of at least one depleted xylol. Effectively by xylene isomerization in the stream of depleted xylol and prepare isomerization stream liquid-phase condition under, make at least The stream contact xylene isomerization catalyst of a part of depleted xylol, this isomerization stream is recycled to this xylol Recycling step.In effective conversion C₉₊- aromatic compounds are to C_8-- aromatic compound and under conditions of preparing transalkylation stream, At least a portion is made to contain C₉₊- stream contacts transalkylation catalyst, and this transalkylation stream is recycled to toluene methylation step One or more of and xylol recycling step.

On the other hand, the present invention relates to preparing the device of xylol, this device comprises catalytic reforming unit, and it is used for making Standby comprise C₆₊The reformate streams of aromatic hydrocarbons；First piece-rate system, it is used at least being separated into described reformate streams Stream containing toluene, containing C₈The stream of aromatic hydrocarbons and contain C₉₊The stream of aromatic hydrocarbons；Toluene methylation unit, it is used for described containing first Toluene conversion in the stream of benzene is dimethylbenzene and prepares the effluent stream that methylates；Second piece-rate system, it is used for from institute State containing C₈The stream of aromatic hydrocarbons, described methylate effluent stream and transalkylation effluent stream reclaim xylol to prepare The stream of at least one depleted xylol；Liquid phase xylene isomerization unit, it is used for will be depleted right in described at least one Xylene isomerization in the stream of dimethylbenzene is to prepare the first isomerization stream；Recirculating system, it is used for recirculation at least A part of described first isomerization stream is to described second piece-rate system；And transalkylation, it is used for conversion described Containing C₉₊C in the stream of aromatic hydrocarbons₉₊Aromatic compounds are to C_8-Aromatic compounds and prepare transalkylation effluent stream.

Brief description

Accompanying drawing 1 is the flow process of the method preparing xylol according to first embodiment of the invention from catalytic reformate Figure.

Accompanying drawing 2 be illustrate according to first embodiment of the invention be modified to prepare xylol from catalytic reformate Method flow chart.

Accompanying drawing 3 be illustrate according to first embodiment of the invention be modified to further prepare from catalytic reformate right The flow chart of the method for dimethylbenzene.

Accompanying drawing 4 is that being still modified to further from catalytic reformate system according to first embodiment of the invention is described The flow chart of the method for standby xylol.

Detailed Description Of The Invention

The present invention is open to prepare xylol from reformate or similar aromatic fraction, optionally together with benzene and/or neighbour The method of dimethylbenzene and device.In the method for the invention, the unit that will methylate adds xylol to produce in complex So that the toluene in reformate component and/or benzene to be converted into extra dimethylbenzene.Because this unit that methylates can prepare C₈Virtue Race's product, it is rich in xylol but little or no extra ethylbenzene, the production of dimethylbenzene segregation section and operating into Originally can reduce and xylene isomerization section can be with the lower liquid phase process of use cost.It is possible if desired to by adding Gas phase isomerization unit and/or by the stream of the depleted xylol of transport portion to transalkylation, and/or by using Conventional technique is such as distilled or film or selective absorption or a combination thereof avoid from dimethylbenzene stream separation ethylbenzene The accumulation of ethylbenzene in xylene production loop.

Any known in the art methyl is added to the method for phenyl ring the demethylation step that can be used for the inventive method.So And, in some preferred embodiments, this demethylation step uses the methylation catalyst of height para-selectivity, such as specially Profit number be US6,423,879 and US6,504,072 United States Patent (USP)s use those, entire contents are incorporated herein by reference. Above-mentioned catalyst comprises molecular sieve, when in 120 DEG C of temperature and 2,2- dimethylbutane pressure 60 support (8kPa) measurement its There is 2,2- dimethylbutane diffusion parameter 0.1-15sec^-1, such as 0.5-10sec^-1.As used herein, specific porous crystalline The diffusion parameter of material is defined as D/r²×10⁶, wherein D is diffusion coefficient (cm²/ sec) and r be crystal radius (cm).Wanted The diffusion parameter asked stems from absorption measurement, and condition assumes that plane sheets model describes this diffusion process.Thus, for giving Determine sorbate load Q, numerical value Q/Q_∞, wherein Q_∞It is balance sorbate load, be mathematically relevant to (Dt/r²)^1/2, wherein t is to need Reach the time (second) that sorbate loads Q.The explanation of plane sheets model is existed by J.Crank " The Mathematics of Diffusion ", Oxford University Press, Ely House, London, 1967 are given, and entire contents are incorporated herein As reference.

It is usually intermediate pore size aluminosilicate zeolites for para-selectivity methylation procedure molecular sieve.Intermediate pore size zeolite Be normally defined those that aperture is about 5 to about 7 angstroms, thus this zeolite freely absorb molecule such as normal hexane, 3- methylpentane, Benzene and p-xylene.Another kind of Common definitions of intermediate pore size zeolite are related to restriction index test, and it is disclosed in United States Patent (USP) In US 4,016,218, disclosure of the documents is incorporated herein by reference.In this case, the limit of intermediate pore size zeolite Index processed is about 1-12, does not introduce oxide modifier and in any steam treatment with independent before adjusting catalyst diffusibility Measure this zeolite.The particular instance of suitable intermediate pore size zeolite includes ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-48 and MCM-22, and ZSM-5 and ZSM-11 is particularly preferred.

Intermediate pore size zeolite as above is especially effective for the methylation method of the present invention, this is because their hole Dimension and shape is conducive to the preparation that xylol is with respect to other xylene isomers.The expansion of the conventionally form of these zeolites Scattered parameter value exceedes above-mentioned 0.1-15sec^-1Scope.However, by this catalyst of strict steam treatment so that implementing to urge Agent micro pore volume controlled be reduced to non-steam treatment catalyst not less than 50% and preferred 50-90%, can reach For the diffusibility required for this catalyst.By under 90 DEG C and 75 support normal hexane pressure before and after steam treatment Measure the normal hexane adsorption capacity of catalyst and obtain the reduction of micro pore volume.

The steam treatment of zeolite is at least about 950 DEG C, preferably from about 950 to about 1075 DEG C, and most preferably from about 1000 to about 1050 DEG C of temperature is implemented to last about 10 minutes to about 10 hours, preferably 30 minutes to 5 hours.

For realize required diffusibility and micro pore volume controlled reduction it may be desirable to by zeolite steam treatment it Front with least one oxide modifier, be such as selected from least one oxide group of periodic chart 2-4 race and 13-16 race element Close.Most preferably, described at least one oxide modifier is selected from the oxide of boron, magnesium, calcium, lanthanum and most preferably phosphorus.At some In the case of, this zeolite can be combined with more than one oxide modifier, the combining of such as phosphorus and calcium and/or magnesium, this be by The steam treatment severity obtaining required for target diffusion rate score can be reduced in adopting in such a way.In some embodiment party In case, it is present in the oxide modifier total amount in this catalyst, based on element metering, can be about 0.05 to about 20wt%, And preferably from about 0.1 to about 10wt%, the weight based on final catalyst.

If modifying agent includes phosphorus, pass through Patent No. 4,356,338,5,110,776,5,231,064 and 5, The method of 348,643 United States Patent (USP) conveniently realizes and for modifying agent to be combined into this catalyst, the entire disclosure of these documents Content is incorporated herein by reference.By making zeolite, or can individually or with binding agent or host material be combined, connect Touch suitable phosphorus compound solution, be followed by and be dried with roasting so that phosphorus is converted into its oxide form, and be easily accomplished The process of phosphorus-containing compound.Contact with phosphorus-containing compound generally about 25 DEG C to about 125 DEG C implement about 15 minutes little to about 20 When.In contact mixture, the concentration of phosphorus can be about 0.01 to about 30wt%.Suitable phosphorus compound includes, but not office Be limited to, phosphonic acids, phosphinous acid, phosphorous acid and phosphoric acid, above-mentioned acid salt and ester and contain phosphorus halide.

After contact phosphorus-containing compound, this porous crystalline material can be dried and roasting is to be converted into oxide shape by phosphorus Formula.Roasting can carry out in an inert atmosphere or in the presence of oxygen for example in atmosphere, about 150 to 750 DEG C, preferably from about 300 to 500 DEG C carry out at least 1 hour, preferred 3-5 hour.Similarity method known in the art can be used for other modification oxygen Compound is combined into the catalyst for this alkylation.

In addition to this zeolite and modified oxide, the catalyst for this methylation procedure can include adopting in resistance to the method One or more binding agent of temperature and other condition or host material.Above-mentioned material includes activity and inactive Material such as clay, silicon dioxide and/or metal-oxide such as aluminium oxide.The latter can come from natural or is in include titanium dioxide The gelatinous precipitate of the mixture of silicon and metal-oxide or gel form.Using active material, tend to change and urge The conversion ratio of agent and/or selection rate and be frequently not thus preferably.Non-active material suitably as diluent with The quantity controlling conversion in given method allows to economically and obtains product in an orderly manner and react without using controlling Other measures of speed.These materials can combine and be existed with improving catalyst into natural clay, such as bentonite and Kaolin Crushing strength under commercial operating conditions.Described material, that is, the binding agent as this catalyst such as clay, oxide.Phase Hope and the catalyst with excellent crushing strength is provided, this is because expectation prevents this catalyst down from becoming powder in commercial Application Last shape material.Just frequently with these clays and/or adhesive oxides just to improving the purpose of catalyst crushing strength.

The natural clay being combined with this porous crystalline material includes montmorillonite and Kaolin series, this series include Become class and take off rock, and commonly known as Dixie, the Kaolin of McNamee, Georgia and Florida clay or wherein main Mineral constituents are wanted to be galapectite, kaolinite, the other materials of dickite (dickite), nacrite or anauxite.Above-mentioned Clay can be used by the original state of initial recovery or initially stand roasting, acid treatment or chemical modification.

In addition to above-mentioned material, porous crystalline material can be with porous matrix material such as silica-alumina, dioxy SiClx-magnesium oxide, silica-zirconium oxide, silica-thorium oxide, silica-beryllia, silica-titania And ternary composition such as silica-alumina-thoria, silica-alumina-zirconium oxide, silica-zirconia Aluminum-magnesium oxide and silica-magnesiazirconia are combined.

The relative scale change of porous crystalline material and inorganic oxide matrix is wide in range, and the former content range is about 1 To about 90 weight % and more generally, especially when this composite is prepared with bead form, scope is about the 2 of this composite To about 80wt%.Preferably, matrix material comprises silicon dioxide or kaolinton.

Methylation catalyst for the inventive method can optional precoking.Catalyst can not burnt by initial filling Enter within this methylation reaction device and carry out this precoking step.Then, carry out with this reaction, coke laydown is in catalyst On surface and thereafter can be by controlling in institute via the periodic regeneration being exposed to oxygen-containing atmosphere at elevated temperatures In the range of needing, typically about 1 to about 20wt% and preferably from about 1 to about 5wt%.

Toluene methylation according to the inventive method can be realized with any of methylating agent, it is preferable that methyl Agent includes mixture and/or the methanol of carbon monoxide and hydrogen.

Suitable condition for this methylation reaction includes such as 500 to 600 DEG C of 350 to 700 DEG C of temperature, absolute pressure 100 and 7000kPa, weight (hourly) space velocity (WHSV) 0.5 arrives 1000hr^-1, and toluene for methanol molar ratio (reactor charging in) be At least about 0.2, for example, from about 0.2 to about 20.Suitable implement the method fixing, in mobile or fluid catalyst beds.As Fruit wishes the degree that continuous control coking loads, then preferably mobile or fluidized bed configuration.Using mobile or fluid bed structure Make, the degree that coking loads can be by the change severity that continuous oxidation regenerates in catalyst regenerator and/or frequency Controlled.For a kind of embodiment of the suitable bed process of toluene methylation is included the one of toluene dose location downstream Individual or multiple positions section injection methylating agent stage by stage.Said method is disclosed in United States Patent (USP) US 6, in 642,426, the document Full content be incorporated herein by reference.

Using the method for the present invention, toluene can with methanol alkylation with least about 75wt% (based on whole C₈Virtue Race's product) selection rate at least about 15wt% one way aromatic compound conversion rate and less than 1wt% trimethylbenzene life Xylol is prepared under product level.Unreacted toluene and methylating agent and part water by-product can be recycled to this first Glycosylation reaction device and heavy byproduct are delivered to fuel and are disposed.C₈Fraction sends into p-xylene separation section, and it typically passes through classification Crystallize or para-xylene product stream is reclaimed from this alkylation effluent by selective absorption or the two operation and stays Under depleted xylol stream, it mainly comprises C₇And C₈Hydrocarbon.Because toluene methylation unit makes reformate C₈In fraction Xylol content improves, and p-xylene separation section size can reduce.This is significant advantage, due to from capital cost and Running cost is used for seeing, p-xylene separation section is one of technique of most expensive in aromatic compounds joint enterprise.

After reclaiming xylol in p-xylene separation section, by the stream of remaining depleted xylol in recirculation Before returning p-xylene separation section, isomerization returns to balance.In the method for the invention, the isomery of the stream of depleted xylol Change in liquid-phase isomerization unit, or individually or in parallel with gas phase isomerization unit come to implement so that this unit simultaneously or Blocked operation.

Any liquid-phase catalysis isomerization method known to the person skilled in the art can be used for this liquid phase xylene isomerization Unit, but a kind of preferred catalyst system and catalyzing is disclosed in U.S. of Publication No. US2011/0263918 and US2011/0319688 In state's patent application, the full content of wherein every document is incorporated herein by reference.Liquid-phase isomerization side used in this application The suitable condition of method includes about 230 DEG C to about 300 DEG C of the temperature of selection and pressure about 1300 to about 3500kPa, to keep lean Stream containing xylol is substantially at liquid phase.In some embodiments, weight (hourly) space velocity (WHSV) (WHSV) can be about 0.5 to about 10hr^-1.

If it does, gas phase isomerization unit can also use any of isomerization catalyst system, but preferably make With ethylbenzene some or all in the stream of depleted xylol effectively being converted and making this dimethylbenzene return equilibrium concentration Catalyst system.Ethylbenzene removing can be realized by dealkylation to benzene or by isomerization to dimethylbenzene.A kind of preferred gas Phase isomerization method is disclosed in United States Patent (USP) US5, and in 516,956, entire contents are incorporated herein by reference.Gas phase isomerization The suitable condition of method includes temperature about 660 °F to about 900 °F (350 DEG C to 480 DEG C), pressure about 50 to about 400psig (446 To 2860kPa), weight (hourly) space velocity (WHSV) about 3- about 50hr^-1And hydrogen is for hydrocarbon mol ratio about 0.7 to about 5.

The method of the present invention also using transalkylation with will reformate charging in C₉Aromatic compounds, C₁₀Aromatics Compound and some C₁₁Aromatic compounds, or directly or through anti-with the benzene from the method other parts or toluene Answer and be converted into balance dimethylbenzene.Then the dimethylbenzene in transalkylation effluent can be delivered to p-xylene separation section and use In reclaiming xylol, it is conveniently provided to this toluene methylation in any benzene of transalkylation process generation or toluene simultaneously Unit is used for upgrading to extra dimethylbenzene further.Any liquid phase or vapor-phase transalkylation unit can be used for this method, But a kind of preferred unit is using being disclosed in United States Patent (USP) US7, the multistage catalyst system and catalyzing in 663,010, wherein all interior Appearance is incorporated herein by reference.This transalkylation may be used in dimethylbenzene and C₉₊Aromatic compounds charging produce benzene with And toluene, as the U.S. Patent Application Publication of Publication No. US2012/0149958, wherein full content is incorporated herein Can serve as the charging of toluene methylation unit as reference, wherein this benzene and/or toluene to prepare to xylol exhausting section The charging of higher p-xylene purity.In addition, the benzene charging of the benzene outside some or all devices or introducing can be with C₉₊Virtue Compounds of group carries out transalkylation to produce toluene and/or dimethylbenzene.Finally, this C₉₊Aromatic molecules can be with fractional distillation Become the concentration C being made up of propylbenzene and methyl-ethyl benzene₉Stream, it carries out transalkylation to prepare toluene and second with benzene Benzene.Then this toluene and ethylbenzene can process in toluene methylation unit and is used for back with producing xylol and light olefin Receive.In addition to the toluene by reforming sections and/or the preparation of this transalkylation section, introduced toluene can also be delivered to this toluene first The xylol that base unit is used for increment produces.The toluene of above-mentioned introducing is preferably removed oxygen and is used for storing above-mentioned introducing The storage tank of toluene is preferably covered with nitrogen.Referring now to the following drawings, the present invention is more specifically disclosed.

Accompanying drawing 1 illustrates the xylol preparation method according to first embodiment of the invention, wherein by pipeline 11 by stone brain Oily feedstock is provided to catalytic reforming unit (for example, semi regenerative reformer, reforming with recycle device or continuous catalysis weight Engagement positions) 12.From the effluent of this catalytic reforming unit 12 be aliphatic and aromatic hydrocarbon complex mixture and, removing C is removed in pentanizer (not shown)_5-After fraction, remaining C₆₊Fraction is delivered to reformate diverter 15 by pipeline 13. Hydrogen also produces in catalytic reforming unit 12 and removes for gas phase isomerization section as described below via pipeline 14, or uses Various units in refinery, or in hexamethylene unit or any other petrochemical process, if this aromatics Compound joint enterprise be not be close to refinery set up if.Alternatively, this hydrogen with export sales or can be used for Fuel or torch emptying.

Reformate diverter 15, it can be optionally dividing wall type (dividing-wall) distillation column, separate in pipeline 13 In C₆₊Fraction, in one embodiment, becomes containing C_6-Overhead fraction stream, containing C₇Intermedium stream and contain C₈₊ Bottom steam.Containing C_6-Overhead fraction stream also can comprise this toluene some or all and/or the C being present in pipeline 13₈ Aromatic compounds together with their non-aromatic azeotropic mixture, depending on specific economic goal.(do not show in another embodiment Show), reformate diverter 15 separates C in pipeline 13₆₊Fraction becomes containing C_7-Overhead fraction stream and contain C₈₊Bottom of towe Stream, eliminates the recovery of intermedium stream.Again, containing C_7-Overhead fraction stream also can comprise some or all being present in The C of pipeline 13₈Aromatic compounds together with their non-aromatic azeotropic mixture, depending on specific economic goal.

Return to accompanying drawing 1, containing C_6-Overhead fraction stream, or in alternate embodiment contain C_7-Tower top evaporate Part-streams, are delivered to extraction section 17 from reformate diverter 15 via pipeline 16, and it can be liquid-liquid extraction process, distillation Extract type procedure or a combination thereof.Non-aromatic compound raffinate removes via pipeline 18 from extraction section 17 and can be used for Olefin(e) oligomerization or reformate alkylation, or deliver to steam crackers as charging or refinery's gasoline component is total Close or as fuel.This raffinate can be used for charging and produced with preparing extra aromatic molecules to aromatisation unit simultaneously Raw hydrogen.Remove via pipeline 19 from the aromatic products of extraction section 17 and provide to benzene column 21, optionally using clay or After person's molecular sieve catalyst pretreatment is to remove trace amounts of olefin or other low concentration impurity.Benzene column 21 extracts from aromatics Take product removing water entrainment and benzene product via pipeline 22, collect generally as the side stream of benzene column 21.This benzene column bottom of towe is produced Thing is rich in toluene, although it may comprise some trace dimethylbenzene and heavy Alkylaromatics simultaneously, and via pipe Line 23 is delivered to toluene methylation section 31.In pipeline 22 benzene or can reclaim for sale or hydrogenation with prepare hexamethylene or Toluene methylation section 31 can be delivered to for extra xylene production.

Toluene methylation section 31 also receives via pipeline 32 and contains C from reformate diverter 15₇Intermedium stream even With methylating agent feed, usually methanol (being not shown in accompanying drawing 1) or dimethyl ether.It should be noted that in pipeline 16 (from reformation Product splitter 15 contains C_6-Overhead fraction stream) and pipeline 32 (contain C from reformate diverter 15₇Intermediate material Stream) between shunting can be used for the non-aromatic compound concentration that effective control is transported to toluene methylation section 31, this is due to leaving Reformate shunting 15 will remove via pipeline 18 via the non-aromatic compound of pipeline 16 to extraction section 17.Therefore via pipeline 16 other logistics can reduce in the overall non-aromatic compound content to toluene methylation section 31 charging.

In toluene methylation section 31, from the toluene of pipeline 23 and 32, optionally together with the benzene from tower 21, with first Alcohol reacts to prepare dimethylbenzene and water.In some cases, C₈Aromatic compounds are also delivered to first via pipeline 23 and 32 Benzylation section 31, to implement ethylbenzene to the dealkylation of benzene in toluene methylation section 31, and subsequently benzene in described section 31 Methylate to toluene or dimethylbenzene.

Toluene can be vaporized by toluene stove and/or heat transmission equipment (not shown) before entering toluene methylation section 31 This toluene and heat it to requiring to maintain the temperature of methylation reaction, it depends on the catalyst for this methylation procedure Species.Some catalyst need for this toluene to be preheated to 400 DEG C, and this toluene is preheated to 600 DEG C by other catalyst requirement. In process heat exchangers equipment and/or stove, toluene can be heated to these temperature, this depends on available in this process Thermoreceptor.For example in stove, the toluene being heated to high temperature can reach the temperature decomposing toluene to coke or heavy hydrocarbon, These can affect rate of heat transfer.Can be by adding diluent, such as nitrogen, hydrogen together with toluene in the upstream of heat transfer setting Gas, fuel gas, steam or a combination thereof are reducing this decomposition rate.The mol ratio of these diluent and toluene can from 0.01 to More than 10 changes.Can also be by using suitable metallurgy for pipeline or controlling first in convection section or radiant section Benzene decomposes, as understood by a person skilled in the art.Example includes carbon steel, rustless steel, titanium or other alloy.Special painting Material and applying can be used for making toluene decomposition minimize and so that coking is minimized.Further, it is possible to use additive agent Toluene coking is made to minimize.

Because this methylating agent, typically methanol comprehensively and are widely distributed in this inside reactor, improve The efficiency of methylation reaction.Can by by this methylating agent using many different in the way of introduce this fixed bed or fluid bed is anti- Answer device, such as via single decanting point, some decanting points or even via structure of distributor.This methylating agent can or It is dispersed within this reactor via the nozzle stretching into this reactor vessel or via internal distributed network.Stretch into this anti- The nozzle answering device can be one, several or many.Alternatively, this methylating agent can introduce via internal distribution This fixed bed or fluid bed.This internal distribution can be single decanting point, several decanting point or many decanting points.Several Or in the case of many decanting points, this allotter can comprise the main line from one or more common manifold branches, and in addition Sub- main line can be from each main line branch to form main line grid.This main line can be designed with uniform diameter and this is common With the diameter of collector or identical or different, or the taper of various diameter and different length.Along each common manifold or Person's main line can have a kind of or some or many nozzles to introduce this methylating agent.The size of these nozzles and length can With similar or different, enter required distribution within this reactor depending on this methylating agent.The allotter of this inside, dry If line and nozzle are used in fluid bed or fixed bed reactors, can be heat-insulated.Decide whether heat-insulated possible change smelting The study of the Chinese classic requires, and its scope can be from carbon steel or to rustless steel or to titanium or other species alloys of being usually used.Dividing The decomposition temperature of methylate fluid and the body temperature preferably shorter than methylating agent of cloth network internal, this is those skilled in the art Known.Can by common feed diluent, such as nitrogen, hydrogen, fuel gas, steam or a combination thereof reduce methyl The decomposition rate of agent.These diluent can be changed to more than 10 by 0.01 for the mol ratio of methylating agent.For first The ideal Distribution system of base agent is fractal orchestration, and it comprises the main line of enormous quantity level and nozzle, and both of which is located at This conversion zone radial direction and axially two directions are everywhere.This fractal distribution system be designed in this reactor axially with Identical or different rates introduce this methylating agent.The distribution of this axial direction can also be controlled by two or more fractal and join Device, and via common engineering method outside this reactor, that is, valve, pump, restricting orifice etc. control methylating agent Speed.

Collected by pipeline 33 from the process tail gas of this toluene methylation section 31 and can be used for olefin(e) oligomerization unit Or reformate alkylation or steam crackers or refinery can be transported to be used for olefin recovery or use Make fuel gas.Product surplus from toluene methylation section 31 is fed to dimethylbenzene distillation column 35 via pipeline 34, and it is by this first Base product is divided into the C rich in xylol₈Aromatic compounds overhead fraction stream and C₉₊Bottom steam.Because C₉Aromatics The quantity of compound is few, C₉Aromatic compounds are in distillation column bottom loop, i.e. the time of staying in reboiler loop, are very high. These C₉Then aromatic compounds when be exposed to high temperature and long-time when, can be polymerized or be condensed into higher level hydrocarbon component, It can make bottom loop or heat transmission equipment fouling.Additive can be used for controlling the speed of heavy polyreaction or condensation. Alternatively C₉Another source of aromatic compounds can add this distillation column to dilute the C from this toluene methylation process₉ Aromatic compounds.This C in addition originating₉Aromatic compounds can introduce, or between continuous mode or intermittent mode or half Have a rest pattern, and with this toluene methylation C₉Aromatic compounds together from this system remove, or continuously or interval or Semi-batch pattern.In addition the C in source₉Aromatic compounds can introduce this distillation column in any position of distillation column, such as this area skill Art personnel can determine that.

Before this dimethylbenzene distillation column 35, the product stream from this toluene methylation section 31 can be via toluene distillation The conveying of tower (not shown) is to reclaim unconverted toluene from dimethylbenzene and heavier component.Fresh toluene also can be via this toluene Distillation column conveys.Product stream and fresh toluene can be identical or different to the feed entrance point of this toluene distillation tower, As those skilled in the art can determine that.Furthermore, it is possible to there be other streams, it can be delivered to toluene distillation tower, for example, come From naphtha reformer, xylene isomerization unit, disproportionation device, transalkylation or comprise toluene and heavy aromatics The dimethylbenzene of any other unit and heavy stream.Via traditional type of cooling such as air fin, water cooler or The toluene being derived from this toluene distillation unit after person's process cooler or a combination thereof reclaims generally as liquid overhead product, These types of cooling or in parallel or in series layout.Toluene also can reclaim as vapor product, or evaporates in overhead In point, any one cooling device upstream or as distillation column side run-off.Equally, this toluene can as product liquid from One of distillation column column plate reclaims, such as 3-5 column plate below the overhead fraction of distillation column.If this is particularly effective being somebody's turn to do Distillation column comprises the component lighter than toluene or multiple component, such as water or light hydrocarbon, and it can reduce toluene by dilution Concentration.Detached with heavy aromatics and impurity for toluene distillation column be may also be divided wall column (divided wall column), its There are one or more subregions.Then the toluene being reclaimed can be recirculated back to toluene methylation section 31 and this heavier component is defeated Deliver to downstream for processing further.

From the C rich in xylol for the dimethylbenzene distillation column 35₈Aromatic compounds overhead fraction stream is via pipeline 36 It is delivered to segregation section 37, wherein para-xylene product reclaims via pipeline 38.Segregation section 37 can be based on absorption method or crystallization Method or the two any combinations, but can have with optimal control xylol from the separation of three kinds of separate material flows anyway There is～20% xylol content (the C of reformate₈Part), there is a kind of stream of preferably >=75% xylol content (toluene methylation process effluent), and have balance (～24%) xylol content a kind of stream (transalkylation and/ Or hydroisomerization effluent).Above-mentioned optimization can produce the phase that the notable scale down of overall segregation section 37 and public work consume Save when more.Above-mentioned optimization can include the stream independent of balance dimethylbenzene material conveying enrichment xylol, such as Patent No. 8,168,845；8,529,757；8,481,798；8,569,564；8,580,120；The U.S. of publication number US2012/0241384 Patent application；And as the United States Patent (USP) disclosure of the U.S. Provisional Patent Application of application number 61/946,052, wherein this article The full content offered is incorporated herein by reference.Alternatively, from this adsorption process xylol enrichment product or Person's intermediate product, it has the p-xylene purity less than 99.7wt%, can be delivered to this crystalline element to be enriched with to diformazan Benzene is to high concentration.Equally, p-xylene purity is less than the crystallized product of 99.7wt% or intermediate product can be delivered to this suction Attached process is to be enriched with xylol to higher concentration.

It is constantly present a small amount of toluene in the dimethylbenzene charging to p-xylene separation section 37.If Simulation moving bed (SMB) absorbing unit is used for reclaiming xylol, then being present in toluene fraction in dimethylbenzene charging is that " thick " toluene produces by fractional distillation Thing, it can comprise trace dimethylbenzene or water.This stream can be fed directly to toluene methylation section 31 and need not any place Reason, to remove micro dimethylbenzene or water, feeds to improve methanol jointly due to generally comprising water to toluene methylation section 31 charging Utilization rate and to suppress feeding preheating coking.In segregation section 37, adsorption process and the combination both crystallization process may include The small-sized SMB unit (not shown) of operation in series or in parallel and small-sized crystalline element (not shown), this SMB unit mainly causes Power is in being directed generally to from rich in xylol stream from the balance p-xylene separation of dimethylbenzene stream and this crystalline element P-xylene separation.

Reclaim xylol after, from segregation section 37 the depleted xylol of remaining liquid phase effluent via pipeline 39 collect and via pipeline 41 with liquid phase feeding to liquid phase xylene isomerization section 42, and wherein xylene isomerizationization is to balance. From the effluent of liquid-phase isomerization section 42 comprise close to balance xylol (～24%) and by pipeline 43 provide to Dimethylbenzene reruns tower 44, and it also receives via pipeline 45 from reformate diverter 15 and contains C₈₊Bottom steam.C₈Rectifying column Tops stream removes as overhead fraction and feeds to segregation section 37 via pipeline 46 from the dimethylbenzene tower 44 that reruns, wherein Para-xylene product is collected via pipeline 38.

(not shown) in some embodiments, can be delivered directly to from the effluent of liquid-phase isomerization section 42 and separate Section 37 (no separating in dimethylbenzene reruns tower 44), condition is the heavy arene concentration prepared by through liquid-phase isomerization section 42 Within the prescribed limit of the separation process for segregation section 37.United States Patent (USP) US7,989,672, the full content of this patent draws Enter herein as reference, teach the C that crystalline element highest is allowed₉₊Aromatic compounds concentration, it can also be in limit model Enclose interior apply to moving-bed adsorption method, or crystallization and moving-bed adsorption method hybrid.Just directly from Liquid-phase isomerization unit feed, to moving-bed adsorption unit, can remove in the following way through this absorbing unit Handled C₉Aromatic compounds：Obtain all or part strippant stream and through being designed to remove in desorbing C in agent₉The fractionating column processing of aromatic compounds, or as heavy component, i.e. boiling point is higher than strippant, or as lightweight Component, i.e. boiling point is less than strippant.Strippant example includes toluene, p-diethylbenzene or naphthane.Other possible solutions Vapor can also use, and this depends on for xylol and absorption raffinate, i.e. meta-xylene, o-Dimethylbenzene and ethylbenzene Relative selectivity.United States Patent (USP) US8,697,929, entire contents are incorporated herein by reference, and teach C₉Aromatic compounds Formation can reduce, condition is that dissolved hydrogen is delivered to liquid isomerization unit jointly, thus reduces in moving-bed adsorption The heavy thing quantity purging is needed within method.In this case, C₉The formation of aromatic compounds can sufficiently low to pass through Introduce liquid-phase isomerization product (isomerate) to dimethylbenzene to rerun the top tray of tower 44 or benzenol hydrorefining 35 and provide Appropriate separation from xylene fraction.The technical staff that the dissolved hydrogen of any presence can pass through fractional distillation design field arranges from system Go out.

Formation C through liquid-phase isomerization catalyst₉It is also ethyl-benzene level present in charging that aromatic compounds are formed Function.In feeding to liquid isomerization unit, EB does not exist or the minimizing of EB can reduce C₉Aromatic compounds formed so that C before absorbing unit₉The fractional distillation of aromatic compounds is not required.EB can use for EB selectively film or absorption Technology removes from this liquid-phase isomerization unit feed.

Alternatively, the effluent of the depleted xylol of the segregation section 37 collected via pipeline 39 can be in gas Feed to gas phase xylene isomerization section 48 via pipeline 47 under the situation of phase, wherein by xylene isomerizationization to balance.It is derived from The effluent of gas phase isomerization section 48 is comprised close to balance xylol (～24%) and is fed to by pipeline 49 stable Tower 51, wherein contains C₇Overhead fraction stream remove via pipeline 52 and by C₈₊Bottom steam is collected and is entered by pipeline 53 Expect to rerun tower 44 to dimethylbenzene.When the gas phase isomerization method for isomerization section 48 is ethylbenzene dealkylation type, then Overhead fraction stream in pipeline 52 comprises dealkylated product benzene and some by-product toluene.When for isomerization section 48 Gas phase isomerization method when being ethylbenzene isomerization type, then the overhead fraction stream in pipeline 52 comprise less benzene and Toluene by-product.However, being which kind of situation, benzene can be delivered to extraction section 17 and as production marketing or deliver to hexamethylene Alkane unit.Benzene can also be processed for other diformazan in toluene methylation section 31 or in transalkylation section (as described below) Benzene prepares (referring to other aromatic compounds integration scenarios of following discloses).Toluene effluent from isomerization section 48 can be in first Benzylation section 32 or process in transalkylation section for other dimethylbenzene preparation.Merging gas phase in pipeline 52 Benzene/methylbenzene stream can be fed directly to toluene methylation unit, thus reduce fractional distillation cost and make capital apply maximization.

The C removing from this stabilizer 51 via pipeline 53₈₊Bottom steam together with from reformate knockout tower 15 containing C₈₊ Bottom steam 45 and optionally, be delivered to dimethylbenzene together from the effluent of this liquid-phase isomerization section 42 and rerun tower 44.Dimethylbenzene reruns tower 44 from these streams separation C₉₊Aromatic compounds and via pipeline 54 provide C₉₊Aromatic compounds To heavy aromatic compounds tower 55, it also receives the C from benzenol hydrorefining 35 via pipeline 56₉₊Bottom stream.Heavy aromatic Compound tower 55 is from stream 54 and 56 and removing C₉Aromatic compounds, C₁₀Aromatic compounds and some C₁₁Aromatic compounds And these components are fed to transalkylation section 58, the more heavy compounds warp in stream 54 and 56 simultaneously via pipeline 57 Collected for supply to fuel oil sump and/or another hydrocarbon processing unit by pipeline 59, this hydrocarbon processing unit can be upgraded, and this is heavier Matter compound is to more desirable, valuable product or multi-products.

In transalkylation section 58, by C₉Aromatic compounds, C₁₀Aromatic compounds and some C₁₁Aromatic compounds or Reacted and be converted into balance dimethylbenzene directly or through with the benzene from technical process other parts or toluene.To the greatest extent Pipe is in operation toluene methylation unit (such as toluene methylation section 31) and transalkylation (such as transalkylation section 58) Aromatic compounds combined unit in there are multiple choices to optimize the preparation of xylol, but because toluene methylation is for right The selectivity of dimethylbenzene is high, and transalkylation produces mixed xylenes product, therefore in preferred embodiments, will be in virtue The toluene being fully incorporated in compounds of group combined unit or preparing is delivered to toluene methylation section 31 rather than is transported to alkyl Transfer leg 58.Toluene source in combined unit, as described in fig. 1, including in office from reformate knockout tower 15 Select toluene in pipeline 32, from this benzene column 21 the toluene in pipeline 23, in this toluene methylation section effluent not Conversion toluene, from this p-xylene separation section 37 " thick " toluene, when described gas phase isomerization be EB dealkylation type When the toluene that produces in the by-product toluene of gas phase isomerization section 48 and transalkylation section 58, and the toluene of input Any stream (not shown).Thus, there is no toluene in transalkylation section 58 effluent or having less toluene again It is recycled to transalkylation section 58.In preferred embodiments, the benzene from benzene column 21 is delivered to transalkylation section 58 (in accompanying drawing Do not show in 1), its quantity makes methyl with respect to the ratio optimization of ring so that maximizing the preparation of dimethylbenzene in described unit. In transalkylation section 58, untreated benzene can be to reclaim for sale or hydrogenation to prepare hexamethylene or can be delivered to first Benzylation section 31 is used for other dimethylbenzene preparation.Effluent from transalkylation section 58 is provided to stabilizer by pipeline 60 51.

Optionally, in the case of needing o-Dimethylbenzene preparation, rerun some or all of of tower 44 from dimethylbenzene Bottom stream can feed to ortho-xylene column 62 via pipeline 61.O-Dimethylbenzene product is pressed overhead fraction via pipeline 63 and is received Collection, ortho-xylene column bottom of towe heavy product is delivered to heavy aromatics tower 55 via pipeline 64 simultaneously.If preparing excessive neighbour two Toluene exceeds to produce to be needed, then this o-Dimethylbenzene some or all of can be through liquid-phase isomerization section 42 or gas phase isomerization section 48 or transalkylation section 58 process to prepare more xylol.

The a kind of of accompanying drawing 1 display packing improves as illustrated in fig 2, and wherein identical Ref. No. is used for indicating those The same section of accompanying drawing 1 display.Especially, in the method showing in fig 2, non-aromatic compound or benzene is not provided to return Receive, therefore omit extraction section 17 and the benzene column 21 of accompanying drawing 1.Therefore, during here is improved, will reform in depentanizer (not shown) The C of device effluent_5-After fraction removes, effluent is fed to reformate segregation section 15 via pipeline 13, and it will contain C₆/C₇ Overhead fraction stream with containing C₈₊Bottom steam separate.Containing C₆/C₇Overhead fraction stream feed to toluene via pipeline 16 The section that methylates 31, does not have benzene extraction step, and as in accompanying drawing 1 embodiment, containing C₈₊Bottom steam via pipeline 45 feed and rerun tower 44 to dimethylbenzene.The stabilizer 51 overhead fraction liquid that another significant change impact is collected via pipeline 52 Body C₆/C₇Stream.This stream or the import being recycled to transalkylation section 58 via pipeline 71, or follow again via pipeline 72 Ring to the import of toluene methylation section 31 or two selections any combinations.Determine for a part of stream 52 to be recycled to alkane The influence factor that group-transfer is still recycled to toluene methylation includes required catalyst length of the cycle in transalkylation section (can be by there is light component such as C in it to transalkylation section feeding₆/C₇And extend) and in transalkylation section 58 Required methyl/chain rate rate.

Another kind of improvement of the method for accompanying drawing 1 display illustrates, wherein identical Ref. No. is reused for marking in fig. 3 The same section of bright those accompanying drawings 1 display.Especially, in the method showing in fig. 3, omit the gas phase dimethylbenzene of accompanying drawing 1 Isomerization section 48.Instead, via pipeline 39 collect segregation section 37 depleted xylol effluent and can be via pipe , with liquid phase feeding to liquid phase xylene isomerization section 42, wherein xylene isomerizationization is to balance for line 41.Alternatively, segregation section The effluent of 37 depleted xylol, collects via pipeline 39, is transferred to transalkylation section 58 via pipeline 44, wherein remaining Ethylbenzene translates into benzene and some xylene isomerizationization will occur via transalkylation catalyst system.Segregation section 37 is flowed Go out two selections of thing, i.e. any combinations of liquid-phase isomerization or transalkylation, are all acceptable.Guiding segregation section 37 flows out Thing depends on the ethyl-benzene level in described segregation section 37 effluent to the decision of a kind of or other method.Alternatively, arrive Or the purging stream from liquid-phase isomerization section 42 can be processed through toluene methylation section 31, or through ethylbenzene isomerization Unit (not shown) is processed, to control this ethylbenzene concentration.Although the embodiment of accompanying drawing 2 shows the extraction wherein eliminating accompanying drawing 1 Take section 17 and benzene column 21, it should be understood that the method for accompanying drawing 3 can be real using the extraction section 17 of accompanying drawing 1 presence and benzene column 21 Apply.

Be applied to accompanying drawing 1-3, each further improvements in methods is shown in accompanying drawing 4, wherein benzenol hydrorefining 35 and diformazan Benzene reruns tower 44 combination in single tower.In this embodiment, now by the effluent of toluene methylation section 31 together with being derived from C in pipeline 53 for the stabilizer 51₈₊Bottom steam, from reformate diverter 15 contain C₈₊Bottom stream 45 and optionally From effluent in pipeline 43 for the liquid-phase isomerization section 42, it is transported to larger dimethylbenzene via pipeline 34 and reruns tower 44.

(not shown) in the improvement of any one method is shown in accompanying drawing 1-4, will be defeated for the product from toluene methylation section 31 Deliver to knockout drum, it produces three single phases, it includes liquid hydrocarbon stream, aqueous water and methanol stream, and olefin-containing Waste gas stream.This separation can be implemented using the cooling between tank in one or more tanks, and this cooling adopts air, cold But water or some suitable coolant streams including cryogen.This tank or can be with either in a horizontal or vertical or its group Close.Horizontal retort can comprise interior panelling.Horizontal tank can comprise water receptor to collect aqueous phase.Can using internal demister pad with Tail gas carrying of liquids is minimized.Vertical tank also can comprise and horizontal tank identical structure, and such as those skilled in the art can set Meter.Also the stream between the combination cooling tank of cooler can be used.Coolant heat exchanger may be alternatively located within this knockout drum.This point Also can be combined with flash cold column with the fund of saving from tank.

This hydrocarbon flow can be further via the such as distilling period of toluene distillation tower and/or dimethylbenzene distillation column 35 etc at Reason is to be further separated out hydrocarbon.This water/methanol stream is delivered to methanol stripper tower to remove dealkylation, methanol and other from water Oxygenatedchemicalss.The stream comprising methanol, hydrocarbon and other oxygenatedchemicalss can be recycled back into toluene methylation section 31.Should Water stream can comprise such as formic acid, acetic acid or the like acid, and it can reduce the pH of stream.This water stream can with caustic alkali, ammonia, Sodium carbonate or any other nertralizer known to those skilled in the art process and neutralize.This waste water stream can be not Process with position；Such as in this reactor effluent arrive methanol stripper bottom, or between any position.Last Before reclaiming valuable olefin component, the stream of conveying olefin-containing is to processing to remove pollutant further.

In one embodiment, toluene methylation section 31 comprise reactor, catalyst regenerator, catalyst cooler, Heat exchange equipment, and gas/solid separation equipment.This reactor effluent can comprise catalyst granules, using gas/solid separation equipment Such as cyclone separator, centrifuge, pneumatic filter, liquid filter, column scrubber or even tower, storage tank or settler, Or it can be separated by a combination thereof with reactor effluent stream.This equipment may be located at this reactor vessel, citing For cyclone separator or multiple cyclone separator, but preferably beyond this reactor vessel.This gas/solid equipment can position In the upstream of any heat transmission equipment or the downstream of this heat transmission equipment for reclaiming heat from this reactor effluent stream.On State heat transmission equipment to include producing the steam generator of steam that pressure is 10psig to 1200psig or using carrying out autoreactor The heat transmission equipment of heat content heat process fluid of effluent stream or a combination thereof.Flue gas from this regenerator also comprises Catalyst fines, it must reduce to be discharged into air.Reclaiming these particulates from flue gas can be using many different Method, including cyclone separator or multiple cyclone separator, electrostatic precipitator, column scrubber, centrifuge or a combination thereof.Should Flue gas solid reclaimer can be in such as CO boiler or any other heat exchange being generally used for flue gas operation The upstream of class process heat transmission equipment of equipment or downstream.The catalyst reclaiming from this reactor effluent or this regenerator Granule may return to this conversion zone or this regenerator region or the two or directly or indirectly, for example, warp Discharge by intermediate store container or from this system.

Catalyst can be taken out and be delivered to heat transmission equipment also known as catalyst cooler from this regenerator, to remove The heat being produced in a regenerator by the burning of coke on this catalyst and other hydrocarbon.Extracting catalyst out from regenerator can To be continuous or interval and variable bit rate.Then cooled catalyst charge is returned to this regenerator.By control System is via the catalyst flowing of this catalyst cooler and/or the amount of heat of removing, the temperature of catalyst bed in a regenerator It is controlled.Depending on the quantity of coking calcination in a regenerator, catalyst cooler in maximum rate and can shut down it Between run.The catalyst discharged from regenerator using the slide-valve or other suitable Valve controlling that control solid flowing Stream, this solid includes the solid fluidizing by suitable vapor stream (ventilation medium), and both injecting catalyst is cold for this vapor stream But the pipeline in device is also injected into the pipeline beyond catalyst cooler.This ventilation medium can be air, steam, nitrogen, hydrocarbon and/ Or other suitable gas, it can also inject within this catalyst cooler to guarantee in catalyst cooler internal solids Fluidisation, and control the heat transfer coefficient from fluidized catalyst, therefore ensure that the suitable heat transfer to cooling medium for the hot catalyst. This catalyst cooler also may be used to preboiler feedwater, produce the steam of different pressures, preheating and gasification process stream or Heating air.This catalyst cooler be typically connected to regenerator, be connected to for carrier absolute construction or completely or Partly (insert) in this regenerator vessel.

Referring now to following non-limiting embodiments, the present invention is more specifically disclosed.

Embodiment 1

This simulation embodiment explanation is based on and conventional aromatic combined unit identical raw material, increases using methanol How alkylation of toluene unit improves xylol yield, in reformation and transalkylation in this aromatic compounds combined unit Section produces dimethylbenzene.In this embodiment it is assumed that whole dimethylbenzene translates into xylol (no o-Dimethylbenzene generation).Should Result is shown below in table 1.

In Table 1, each aromatic compounds combined unit qualitatively and quantitatively using same materials feeds (1245.3kTa Petroleum).In addition reforming sections provide like products state in all of situation, and Product Status are listed in name Claim in the row #1 of " critical compression ratio reformate ".The row #2 of title " dimethylbenzene reclaims (unique) " shows heavy iff reclaiming Xylol during engagement positions dimethylbenzene produces (no transalkylation).Entitled " dimethylbenzene reclaims and transalkylation " Row #3 is shown in the xylol preparation in conventional aromatic combined unit, wherein increases transalkylation another to produce Outer dimethylbenzene.The row #4 of entitled " being reclaimed using the dimethylbenzene of TAM and transalkylation " is shown and combines dress from aromatic compounds Put and prepare xylol, wherein the aromatics that routine has transalkylation is increased to using the alkylation of toluene unit of methanol In compound combined unit.

As shown in table 1, based on same materials charging and reforming sections yield, conventional aromatic combined unit to two Toluene yield is 560.9kTa and for wherein increasing the ordinary combination device using the alkylation of toluene unit of methanol, right Diformazan benzene yield is 645.1kTa.

Further, since higher marginal benefit, xylol production interests are usually above benzene production.Benzene can be delivered to this alkane Group-transfer section is used for other xylene production, but this produces the rate limit with ring by methyl.But if methylbenzyl Change section can be utilized, then all benzene can be converted into dimethylbenzene-and be further converted to xylol-if asked. Therefore for row #4,135.2kTa benzene in addition is available for further xylol and produces.In this case, this joint The quantity of device xylol can increase to～829kta, and the combined unit of xylol yield no toluene methylation relatively is several Improve 50%.

Therefore, the alkylation of toluene unit of methanol and transalkylation are adopted in aromatic compounds combined unit Combination, under same materials charging and reforming sections yield, there is provided more significantly higher than conventional aromatic combined unit Xylol yield.Instead, to realize xylol yield similar to using methanol alkylation toluene unit and transalkylation The conventional aromatic combined unit of unit combination, required charging less it is allowed to refinery's section upstream smallerization.Change speech It, it is right to be allowed using the alkylation of toluene unit of methanol and the combination of transalkylation in aromatic compounds combined unit Diformazan benzene yield is similar to the conventional aromatic production using less crude oil.

Although the present invention is disclosed by reference to specific embodiment and is illustrated, those skilled in the art Member is it will be understood that the present invention can provide, for itself, the conversion not necessarily herein illustrating.Thus, for this cause, it is Determine the true scope of the present invention, should entirely by reference to appending claims.

Claims (20)

1. the method preparing xylol, the method includes：

(a1) C will be comprised₆₊The feed steam of aromatic hydrocarbons is at least separated into the stream containing toluene, containing C₈The stream of aromatic hydrocarbons and contain C₉₊ The stream of aromatic hydrocarbons；

(b1) make at least a portion effectively by toluene conversion for dimethylbenzene and under conditions of producing the effluent stream that methylates The described stream containing toluene is contacted with methylating agent；

(c1) from described containing C₈Aromatic stream and the described effluent stream recovery xylol that methylates are at least one lean to produce Stream containing xylol；

(d1) effectively by the liquid phase of xylene isomerization in the stream of described depleted xylol and generation isomerization stream Under the conditions of, so that the stream of the described at least one depleted xylol of at least a portion is contacted with xylene isomerization catalyst；

(e1) described at least a portion isomerization stream is recycled to (c1)；

(f1) effectively by C₉₊Aromatic compound conversion is C_8-Under conditions of aromatic compounds and generation transalkylation stream, make At least a portion contains C₉₊Stream contact with transalkylation catalyst；And

(g1) described at least a portion transalkylation stream is recycled to one or more of (b1) and (c1).

2. the method for claim 1 wherein that the feed steam in (a1) comprises by removing C from reformate streams_5-Hydrocarbon and The C producing₆₊Aromatic hydrocarbons and the mixture of aliphatic hydrocarbon.

3. the method for claim 1 or claim 2, wherein makes the described stream containing toluene stand extraction non-aromatic to remove The described aromatic streams containing toluene are wherein separated into benzene stream and first by the compound and generation aromatic streams containing toluene Benzene stream, and wherein provide described toluene stream to contact (b1) further.

4. the method for claim 1 or claim 2, wherein separates (a1) and also produces the stream containing benzene.

5. the method for claim 4, wherein provides all described streams containing toluene to contact (b1).

6. the method for claim 3 or 4, wherein provides a part of described benzene stream or the described stream containing benzene to contact (f1) to optimize the ratio that methyl is with respect to ring.

7. the method for aforementioned any one of claim, is wherein separated (a1) and is implemented by dividing wall type distillation column.

8. the method for any one of claim 4-7, wherein provides described at least a portion stream containing benzene to contact (b1).

9. the method for aforementioned any one of claim, wherein said methylating agent comprises methanol.

10. the method for aforementioned any one of claim, wherein contact (b1) are implemented in the presence of a catalyst, and described catalyst comprises The diffusion ginseng of 2,2- dimethylbutane when measuring at 120 DEG C of temperature and the 2,2- dimethylbutane pressure of 60 supports (8kPa) Number is the about 0.1-15 second^-1Porous crystalline material.

The method of 11. claim 10, wherein said porous crystalline material is included in experience at a temperature of at least 950 DEG C and adopts and steams The ZSM-5 formerly processing of vapour.

The method of 12. aforementioned any one of claim, and also include：

(h1) effectively by xylene isomerizationization in the stream of described depleted xylol with make ethylbenzene dealkylation or isomery Change and produce under isomerization and the gas phase condition of stream of depleted ethylbenzene, make the described at least one of at least a portion depleted right The stream of dimethylbenzene is contacted with xylene isomerization catalyst；And

(i1) stream of the described isomerization of at least a portion and depleted ethylbenzene is recycled to (c1).

The method of 13. claim 12, wherein said gas phase condition effectively makes the second in the stream of described depleted xylol Benzene dealkylation and generation by-product toluene stream, and also comprise to provide described by-product toluene stream to contact (b1).

The method of 14. aforementioned any one of claim, wherein by least a portion C in described transalkylation stream_7-Aromatics Compound is recycled to contact (b1).

The method of 15. aforementioned any one of claim, wherein by a part of C in described transalkylation stream_7-Aromatic compounds It is recycled to contact (f1).

The method of 16. aforementioned any one of claim, and also include：

(j1) from described containing C₈The stream of aromatic hydrocarbons, in described methylate effluent stream and described transalkylation stream at least A kind of recovery o-Dimethylbenzene.

The method of 17. aforementioned any one of claim, and also include：

(k1) reclaim unconverted toluene from the described effluent stream that methylates；And

(l1) described unconverted toluene is supplied to contact (b1).

18. devices preparing xylol, this device comprises：

(a2) catalytic reforming unit, it comprises C for preparation₆₊The reformate streams of aromatic hydrocarbons；

(b2) the first piece-rate system, it is used for described reformate streams being at least separated into stream containing toluene, containing C₈Aromatic hydrocarbons Stream and contain C₉₊The stream of aromatic hydrocarbons；

(c2) toluene methylation unit, it is used for the toluene conversion in the described stream containing toluene is dimethylbenzene and preparation first Base effluent stream；

(d2) the second piece-rate system, it is used for from described containing C₈The stream of aromatic hydrocarbons, described methylates effluent stream and alkyl turns Advection goes out material and flows back to receipts xylol to prepare the stream of at least one depleted xylol；

(e2) liquid phase xylene isomerization unit, it is used for the diformazan in the stream of described at least one depleted xylol Benzene isomerization is to prepare the first isomerization stream；

(f2) recirculating system, it is used for the described first isomerization stream of recirculation at least a portion to described second segregative line System；And

(g2) transalkylation, it is used for conversion described containing C₉₊C in the stream of aromatic hydrocarbons₉₊Aromatic compounds are to C_8-Aromatics Compound and prepare transalkylation effluent stream.

The device of 19. claim 18, and also comprise：

(h2) gas phase xylene isomerization unit, it is used for isomerization two in the stream of described at least one depleted xylol Toluene is to prepare the second isomerization stream；And

(i2) the second recirculating system, it is used for the described second isomerization stream of recirculation at least a portion and separates to described second System.

The device of 20. claim 18 or 19, and also comprise：

(j2) the 3rd piece-rate system, it is used for from described containing C₈The stream of aromatic hydrocarbons, described methylates effluent stream and alkyl turns Advection goes out one or more of material stream and reclaims o-Dimethylbenzene.