CN1226267C - Azeotropic distillation process - Google Patents
Azeotropic distillation process Download PDFInfo
- Publication number
- CN1226267C CN1226267C CN 02805492 CN02805492A CN1226267C CN 1226267 C CN1226267 C CN 1226267C CN 02805492 CN02805492 CN 02805492 CN 02805492 A CN02805492 A CN 02805492A CN 1226267 C CN1226267 C CN 1226267C
- Authority
- CN
- China
- Prior art keywords
- carboxylic acid
- aliphatic carboxylic
- water
- acid esters
- oil phase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
- C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
- C07C51/46—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation by azeotropic distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
- B01D3/36—Azeotropic distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
Abstract
A process of azeotropic distillation which comprises the following steps (1) to (5): step (1): a step of azeotropically distilling a solution to be distilled containing water, an aliphatic carboxylic acid and an aliphatic carboxylate using an entrainer to give an aliphatic carboxylic acid having a reduced water content and an overhead fraction having a concentrated water content, step (2): a step of condensing the overhead fraction to give a gas and a liquid condensate being separated into a water phase and an oil phase, step (3): a step of withdrawing the water phase and the oil phase of the condensate separately, step (4): a step of distilling a part or all of the water phase thus withdrawn to give an overhead fraction containing the above aliphatic carboxylate and having a reduced water content, and step (5): a step of distilling the overhead fraction in step (4) together with a part or all of the oil phase in step (3) to give a fraction containing the above aliphatic carboxylate and recovering a part or all of the aliphatic carboxylate fraction to the outside of the azeotropic distillation system.
Description
Technical field
The present invention relates to Azotropic distillation method.The present invention is in that for example to separate the occasion that removing anhydrates reclaims aliphatic carboxylic acid by component distillation the water-based feed streams of acetate from fatty family carboxylic acid effective especially.The present invention relates in the solvent of fatty family carboxylic acid in liquid phase oxidation reaction is made the process of aromatic carboxylic acid, to be suitable for reclaiming method as the aliphatic carboxylic acid of solvent.
Background technology
Azotropic distillation method is in being difficult to the mixture of fractionation by distillation, can the distillatory separation performance be improved with the material (entrainer) of a certain composition formation azeotropic mixture by adding.The example suitable as the industry of Azotropic distillation method has, and in the mixture of acetate and water, interpolation is carried out component distillation with n-propyl acetate or n-butyl acetate that water forms azeotropic mixture, obtains the method for high purity acetate etc. from the mixed solution of acetate and water.
Think the aspect that Azotropic distillation method can be suitable for to be to make aromatic carboxylic acid.When promptly in the aromatic carboxylic acid manufacturing processed, reclaiming the process of solvent, applicable Azotropic distillation method.
The manufacturing of aromatic carboxylic acids such as terephthalic acid is normally carried out in the solvent that contains aliphatic carboxylic acids such as acetate.But there is water to generate in this manufacturing process, so must prevents in the reaction system that sealing accumulates.Therefore, to from reactor, take out the mixed vapour of aliphatic carboxylic acid and water, to contain the feed streams distillation of the phlegma of this steam, water is separated with aliphatic carboxylic acid, and at least a portion of the aliphatic carboxylic acid of dehydration will be recycled to reaction raw materials liquid Preparation tank etc.
If notice in the aliphatic carboxylic acid, when acetate is widely used as above-mentioned solvent, from the mixture of acetate and water, separates except that anhydrating with rectification method usually, but installation cost and change expense at a glance, it is favourable that component distillation just becomes.
The main points of view of azeotropic distillation technology exploitation can be divided into the aftertreatment of separation performance, control performance, minimizing reflux ratio, azeotropic distillation column overhead fraction phlegma substantially.Usually reflux ratio is big, and run stability is good, and along with reflux ratio diminishes, run stability is variation gradually.In addition, if reflux ratio is reduced to a certain limit when following, the separation performance rapid deterioration of component distillation itself.This limit is commonly called minimum reflux ratio, the method that this value is returned with supply position (highly), feeding pipeline number, the phegma of supplying with supply liquid in liquid compositions, entrainer kind, the azeotropic distillation column, entrainer return method etc. and different.
If when turning round with very high reflux ratio, though control performance and separation performance are met, such running consumes big energy, unfavorable economically, make reflux ratio as far as possible near minimum reflux ratio so be actually, reduce energy consumption as far as possible, turn round.
The Azotropic distillation method of separating acetic acid and water all has open in communiques such as Japan special permission communique clear 62-41219 number, open 94-14292 number of Korean Patent, open communique 2000-72714 number of Japan's special permission, WO98/45239 number.
Japan's special permission communique proposes for clear 62-41219 number, after azeotropic distillation column overhead vapours phlegma being carried out the separation of liquid liquid, as the method that reduces the oil-phase component that aqueous phase side was mixed with, particularly be conceived to the isobutyl acetate and the impurity aliphatic carboxylic acid esters, of oil-phase component, water liquid is carried out stripping and method that their are reclaimed.Yet, its objective is as oil-phase component and sneak into water and damnous countermeasure, but be not the technology that can solve the caused problem of impurity aliphatic carboxylic acid esters, fully.Above-mentioned aliphatic carboxylic acid esters, enters distillation tower together along with feeding, accumulates in oil phase.The method of the clear 62-41219 communique of special permission communique record is that the part that prevents the impurity aliphatic carboxylic acid esters, that accumulates is like this followed water and the technology of losing, but above-mentioned aliphatic carboxylic acid esters, accumulates and problem that concentration rises in the not mentioned oil phase.The separation performance of acetate and water worsened when the rising of above-mentioned aliphatic carboxylic acid ester concentration made component distillation, and effective constituent (acetate) is lost.
Thereafter each company has proposed also to prevent that impurity (aliphatic carboxylic acid esters) is accumulated in the technology of oil phase.
For example the open 94-14292 communique of Korean Patent proposes, with the condensation of azeotropic distillation column overhead vapours and phlegma carry out after liquid liquid separates, the impurity fat carboxylic ether's who is present in oil phase one side method is reclaimed in distillation.Yet there is following point in this method, and owing to the separation performance of above-mentioned aliphatic carboxylic acid esters, in the oil phase and entrainer is poor, above-mentioned aliphatic carboxylic acid esters,'s separation needs big energy.
In addition, special permission proposes for open communique 2000-72714 number, allows the overhead vapours partial condensation of azeotropic distillation column, and makes the impurity aliphatic carboxylic acid esters, in the entrap bubble be absorbed in the method to reclaim in the acetate.Yet, have entrainer with this method partial condensation and mix, can not only above-mentioned aliphatic carboxylic acid esters, be extracted, can cause effective constituent (entrainer composition) loss and polluted product.
The WO98/45239 communique proposes, and with the overhead vapours partial condensation of azeotropic distillation column, distills residual gas, to reclaim impurity aliphatic carboxylic acid esters,'s method.This technology is also improved on use heat this point, but can not separate above-mentioned aliphatic carboxylic acid esters,, has the same problem of putting down in writing with other patents of technology on this aspect in the special use that will be designed for recovery.In addition, also exist in the same communique because of azeotropic form in water concentration low, so through component distillation dewater must a large amount of entrainers of use problem.The amount of the entrainer that uses during component distillation is formed decision by azeotropic, usually to the weight ratio of water more than 1 times, for example be 2～5 times.Therefore, except that the requirement of entrainer own was big, usually because entrainer recycles, and boiling point is lower than acetate, and the material (as methyl acetate and the p-Xylol when making terephthalic acid) that is insoluble in water was accumulated in entrainer one side.Therefore, as the amount that contains impurity increases, and the oil phase amount just significantly increases.Thereby the allowed band that can contain as a kind of aliphatic carboxylic acid esters, of impurity is narrow and small.
As mentioned above, impurity aliphatic carboxylic acid esters,'s recovery, preferably corresponding with following whole problem: make the material balance of distillation system, reduce the used energy of Separation and Recovery, high purity ground reclaims, and avoids the change loss with simple equipment.Impurity aliphatic carboxylic acid esters,'s special-purpose recovery system had been proposed for this reason.
The present invention considers these situations and carries out, and is conceived to new approaches that impurity aliphatic carboxylic acid esters,'s the concentration of the aqueous phase of phlegma that the condensation of azeotropic distillation column overhead fraction is obtained draws with the ratio of the concentration of entrainer as starting point.Reclaiming organic composition from this aqueous phase almost is essential operation, and this point is behaved known, but the present invention actively uses this operation, has found to suppress the technology that the impurity aliphatic carboxylic acid esters, increases.Thereby the present invention constructs by this technology, and by introducing simple process, hope can provide and reduce the energy usage quantity, and the Azotropic distillation method of the good separation performance of tool.
Summary of the invention
The present invention relates in the operation of component distillation, be present in the impurity aliphatic carboxylic acid esters,'s who is accumulated in the entrainer in the azeotropic distillation column recovery.The present inventor is conceived to above-mentioned aliphatic carboxylic acid ester concentration in the water of azeotropic distillation column overhead fraction phlegma and boils high in the oil phase frequently of agent concentration together, reclaim above-mentioned aliphatic carboxylic acid esters, from aqueous phase, just find the simpler and easy and above-mentioned aliphatic carboxylic acid esters, of less energy-consumption ground recovery of the method that reclaims than the approach that was conceived in the past.The present invention finishes according to these discoveries.
Be main points of the present invention, be to comprise at least the Azotropic distillation method of following operation (1)～(5).
Operation (1): moisture, aliphatic carboxylic acid and aliphatic carboxylic acid esters,'s solution to be distilled entrainer component distillation obtains the operation of the overhead fraction that aliphatic carboxylic acid that water content reduces and moisture is concentrated.
Operation (2): make the overhead fraction condensation, obtain gas and be divided into water and the operation of oil phase biphase phlegma.
Operation (3): the operation of from phlegma, telling water and oil phase.
Operation (4): part or all of the water that will get distilled, and obtains containing above-mentioned aliphatic carboxylic acid esters, and the operation of the overhead fraction that water content reduces.
Operation (5): part or all of the oil phase that the overhead fraction that operation (4) is obtained is got with operation (3) distilled, and part or all of the above-mentioned aliphatic carboxylic acid esters, of distillation gained is recycled to operation outside the component distillation system.
The simple declaration of accompanying drawing
Fig. 1 is the schema of an example of enforcement distillating method of the present invention.
Symbol is among the figure: 11 are azeotropic distillation column, and 13 is liquid liquid separator tank (decanting vessel), and 21 is stripping tower, and 24 is the entrainer recovery tower.
The optimised form that carries out an invention
Below example of the present invention is elaborated.
In this specification sheets, " solution to be distilled " is meant and contains the mixing solutions of wanting the purified target substance and will reducing the material (to call " material that will reduce " in the following text) of its concentration." entrainer " fingering row component distillation and the 3rd composition that adds.And " azeotropic scope " is meant the scope that is at least 0.1 weight % in this scope as entrainer concentration in the whole composition of liquid phase existence." azeotropic distillation column " is meant the distillation tower of above-mentioned solution to be distilled of distillation and entrainer.
(explanation of operation (1))
Among the present invention,, comprise solution to be distilled entrainer component distillation, obtain the operation of the overhead fraction that target substance aliphatic carboxylic acid that water content reduces and moisture is concentrated moisture, aliphatic carboxylic acid and aliphatic carboxylic acid esters, at first as operation (1).
Concentration for the water in the mixture that reduces fatty family carboxylic acid and water by component distillation, usually liquid effluent contains the aliphatic carboxylic acid that water content reduces at the bottom of distilling the tower that hope obtains at the bottom of the tower, and obtains the azeotropic mixture steam of main moisture and entrainer from cat head.At this moment for reaching the purpose that re-uses aliphatic carboxylic acid etc., the concentration of the entrainer at the bottom of the best tower in the liquid effluent is below 100ppm, and according to the requirement of economy etc., preferably in the azeotropic distillation column overhead fraction phlegma concentration of aliphatic carboxylic acid below 1000ppm.The part of liquid effluent is carried out recirculation as the batching of material solution at the bottom of the tower in the liquid phase oxidation reaction system of the aromatic hydrocarbons that alkyl replaces.
Below treat retort solution and entrainer describes.
Solution to be distilled of the present invention is the mixing solutions that contains target substance and the material that will reduce, and, needing only entrainer that is added and the material that will reduce generation azeotropic mixture and its azeotropic temperature low-boiling words than target substance, all the other all do not have special restriction.In addition, also can contain the material that this component distillation is not produced great effect.
As long as entrainer of the present invention can have effect, be not particularly limited.And, need not to be single component, can be to form the mixture of ingredients more than 2 kinds of heterogeneity azeotropic mixture with the material that will reduce, but also can contain a part of resolvent of this composition.
Azeotropic distillation column of the present invention can be packing tower or tray column.The supply position for the treatment of retort solution is not particularly limited, but normally in the stage casing of azeotropic distillation column, for making separation efficiency the highest, preferably considers to form in the tower decision optimum position.The running of this azeotropic distillation column can be under normal pressure, add depress or reduce pressure under implement under the various conditions, its mode can be intermittent type or continous way.Better be under normal pressure, to implement in a continuous manner.
Above-mentioned aliphatic carboxylic acid esters, can be any concentration during component distillation, but stable and high density divides dried up this respect to consider from aliphatic carboxylic acids such as acetate, in containing the oil phase of entrainer to contain 3～50 weight % for well.
Think among the present invention that the purified target substance is an aliphatic carboxylic acid, normally saturated the or unsaturated aliphatic carboxylic acid of carbonatoms 2～6.Can enumerate the representative examples of saturated aliphatic carboxylic of carbonatoms 2～4 preferably, for example acetate, propionic acid, butyric acid etc.The material that reduces concentration is a water.
And impurities aliphatic carboxylic acid esters,'s kind does not have special restriction in the present invention's solution to be distilled, the ester of common available above-mentioned target substance aliphatic carboxylic acid, concrete available methyl acetate.
The kind of the aliphatic carboxylic acid of entrainer consideration coexistence is selected, and can use the known compound of the component distillation of the mixing solutions that is used for fatty family carboxylic acid and water.Usually use can form the compound of azeotropic mixture with water, for example, and ester classes such as butyl formate, n-propyl acetate, isobutyl acetate, n-butyl acetate, pentyl acetate, n-butyl propionate, isobutyl propionate; Ethers such as dichlormethyl ether, methyl isoamyl ether, allyl group isoamyl ether, di-n-butyl ether, halogenated hydrocarbons such as Ethylene Dichloride, chlorobenzene, ketones such as monochloroacetone, butyrone, methyl butyl ketone, allylacetone, aromatic hydrocarbons such as toluene, dimethylbenzene, ethylbenzene etc.Better be to use the ester class in these entrainers.Wherein preferably n-propyl acetate or n-butyl acetate.
In addition, among the present invention, solution to be distilled is to be used for the occasion of the solvent of the manufacturing of aromatic carboxylic acids such as two benzoic acids etc., can contain in the solution to be distilled from this aromatic carboxylic acid to make other materials such as p-Xylol, methyl acetate of raw material and the resolvent of entrainer.
The composition of aliphatic carboxylic acid and water is arbitrarily in the solution to be distilled.Usually, the present invention is applicable to that water ratio is the scope of 4～99 weight %, the fatty family carboxylic acid of scope that is preferably 10～70 weight % and the mixing solutions of water.
As the concrete solution to be distilled that is applicable to the inventive method, can be used in the solvent of fatty family carboxylic acid liquid-phase oxidation to the alkyl substituent aromatic hydrocarbon to make the solution that is reclaimed in the refining aromatic carboxylic acid manufacturing process.For example can be used to from the mixed vapour condensation regenerant of the liquid-phase oxidation reactor of alkyl substituent aromatic hydrocarbon, water absorbs the regenerant of acetate in the steam etc. in the waste gas that above-mentioned reactor is emitted.The regenerant of the also available at least a portion evaporation back condensation that makes the reaction mother liquor that is reclaimed, aromatic carboxylic acid and reaction mother liquor carried out the regenerant of the washings that is used to wash in reaction mother liquor that solid-liquid separation reclaims or this operation etc., can therefrom select any liquid and quantity to be used.These liquid can mix, but also independent processing.
(explanations of operation (2), (3))
After the operation of the present invention (1), operation (2) is arranged, even the overhead fraction condensation obtains gas and is divided into water and the operation of oil phase biphase phlegma, and operation (3), promptly from phlegma, tell the operation of each phase.
Among the present invention, component distillation by operation (1), can obtain containing liquid effluent at the bottom of the tower of the target substance that the material concentration that will reduce descended at the bottom of the tower, obtain mainly the steam (overhead fraction) of the azeotropic mixture formed by material that will reduce and entrainer from cat head.In operation (2), the vapour condensation that will obtain from cat head obtains phlegma and steam.This phlegma is normally by based on the water of the material that will reduce and the two phase liquid that constitutes based on the oil phase of entrainer.In operation (3), this biphase phlegma is divided into water and oil phase then.As this separation means, available decanting vessel etc. carry out liquid liquid separation etc., as long as but can achieve the goal and just it not had special restriction.For telling two-phase like this, preferably use the material that will reduce and the entrainer that can produce inhomogenous azeotropic mixture, promptly constitute the water and mutual inhomogeneous mixing of oil phase of phlegma.
In the water and oil phase of the phlegma that operation (2) obtains, the above-mentioned aliphatic carboxylic acid esters,'s who reclaims from oil phase amount, the preferably above-mentioned aliphatic carboxylic acid esters,'s who reclaims from water below 20 times of amount.For example can try to achieve from " concentration of the above-mentioned aliphatic carboxylic acid esters, the oil phase flow * oil phase of time per unit " and " the above-mentioned aliphatic carboxylic acid esters,'s of the water flow * aqueous phase of time per unit concentration ".If when above-mentioned value surpassed 20 times, few from the callable aliphatic carboxylic acid esters,'s of water quantitative change, effect of the present invention can diminish, therefore better below 18 times, good especially below 15 times.
In the two-phase of getting, at least a portion that better will be mainly the phase (oil phase) of entrainer is sent into azeotropic distillation column and is carried out recirculation.The method of sending entrainer back to has the cat head full dose remelting of scrap and tells a part from the midsection remelting of scrap.Its theoretical value of amount of sending into the entrainer that carries out recirculation of azeotropic distillation column can be from drawing from the boil water yield of distillation tower discharge and the composition of vapor of mixture.In fact at the bottom of aliphatic carboxylic acid concentration of family that can be from azeotropic distillation column overhead fraction phlegma and the Ta in the liquid effluent entrainer concentration obtain only azeotropic dosage.For replenishing the partially azeotropic agent that loses outside the effusion system, can supply with new entrainer in addition.
On the other hand, mainly be that the phase (water) of the material that will reduce has at least a part to be supplied in the following operation (4).Remaining water can be used as phegma and returns azeotropic distillation column.Also can after sending into operation (4), whole water send its part back to azeotropic distillation column as phegma.And after being utilized during the course based on the main component water of the phase (water) of the material that will reduce, its part also can go out of use.As the method that water returns as phegma, method of returning from the component distillation column overhead and the method for returning at midsection are for example arranged.By the ratio of (the backflow water yield/discharge water yield), the quantity of reflux of water is set in about 0.1～3 usually.
(explanation of operation (4))
In operation (4), part or all of the water that will get distilled, and obtains containing the above-mentioned aliphatic carboxylic acid esters,'s that water content reduced overhead fraction.
Specifically can enumerate, for example will send into distillation tower, obtain the method for the above-mentioned aliphatic carboxylic acid that water content reduces from this distillation tower cat head from (is principal constituent with the material water that will reduce) water that the phlegma of azeotropic distillation column overhead fraction is got.What obtain at the bottom of the Tata from distillation through distillation mainly is water.This water can be discarded to system, also a part can be returned azeotropic distillation column as phegma.
(explanation of operation (5))
In the operation (5), part or all distillation of the oil phase that overhead product that operation (4) is obtained and operation (3) are got, and part or all of the above-mentioned aliphatic carboxylic acid esters, that distillation is obtained is recycled to outside the system.
Distillation tower purpose in the operation (5) is to reclaim entrainer.Part or all of oil phase is supplied to the distillation tower of operation (5) in the azeotropic distillation column overhead fraction phlegma that the overhead fraction and the operation (3) of operation (4) are got, and distills.By distillation, entrainer is separated with the impurity aliphatic carboxylic acid esters.In addition, control makes among the aliphatic carboxylic acid esters, of this operation the supply that is distilled composition of operation (5), and the overhead fraction that obtains from operation (4) more than 20% is relatively good from energy efficiency.
The entrainer that is reclaimed at the bottom of the tower can part or all be recovered to outside the system, also can part or all return azeotropic distillation column.In addition, part or all of the above-mentioned aliphatic carboxylic acid esters, of impurity can be recovered to outside the system.
And to the distillation tower of operation (5), azeotropic distillation column overhead fraction phlegma (being entrainer and above-mentioned aliphatic carboxylic acid esters,'s mixture) and operation (2) resulting gas can be supplied with together as part or all oil-phase component and oil phase in addition of the oil phase of getting.
In addition, as Japan special permission communique clear 6-131091 number is put down in writing, when oil phase that operation (3) is got and the resulting entrainer of operation (5) return azeotropic distillation column, the circulating fluid of entrainer can be cut apart, a part is returned the component distillation column overhead, another part returns midsection, adopts reflection easily to change the effect of operating condition and the method for energy rapid answer.And to operation (2) and the resulting water of operation (4), such as Japan special permission make a report flat 10-504556 number the record, also available will returning at midsection as the water of azeotropic distillation column phegma, the operation by its quantity comes the method for the impurity concentration at the bottom of the control tower.
And in order to reclaim the aromatic hydrocarbons that the alkyl that is accumulated in the entrainer replaces, it directly can be separated from entrainer, also can such as Japan's special permission make a report flat 10-504556 number record it is told from the component distillation midsection.Also for another example the WO97/29068 communique put down in writing the same, the cut of telling is made with extra care.
The following describes the method that the present invention who is suitable for Azotropic distillation method of the present invention makes aromatic carboxylic acid.
At first itself describe with regard to the aromatic carboxylic acid manufacture method.
The target compound aromatic carboxylic acid is represented any aromatic carboxylic acid, for example aromatic monocarboxylate, aromatic dicarboxylic acid, aromatic tricarboxylic acids etc.For example when phenyl ring is arranged as aromatic nucleus, the aromatic hydrocarbons that alkyl such as corresponding monoalkylated benzenes, dialkyl benzene, trialkyl benzene replace can be carried out oxidation, makes than the method for good utilisation liquid-phase oxidation.Wherein, method of the present invention is applicable to aromatic dicarboxylic acid, particularly is the occasion of terephthalic acid at aromatic carboxylic acid, the aromatic hydrocarbons that replaces as the alkyl of raw material at this moment, available p-Xylol.
When in liquid phase, carrying out oxidizing reaction, make solvent with aliphatic carboxylic acid usually.As the aliphatic carboxylic acid of liquid phase oxidation reaction solvent, for example, with acetate for well, 2～6 times of weight of the aromatic hydrocarbons that the usage quantity of this solvent normally replaces with respect to the raw material alkyl.And moisture concentration 4～25 weight % normally in the oxidizing reaction system are preferably 7～20 weight %.
Carry out liquid-phase oxidation at the aromatic hydrocarbons that alkyl is replaced and make in the oxidizing reaction of aromatic carboxylic acid, use catalyzer usually.Transistion metal compounds such as for example available manganese, cobalt, iron, chromium, nickel are made catalyzer.Available bromine compounds is made promotor.Without the bromine compounds catalyzer time, can use the promotor as cobalt catalyst such as acetaldehyde and methyl ethyl ketone.
Oxygenant can use molecular oxygen and air, but uses air usually.The air that the oxygen concn that also available mixture of oxygen forms raises, the opposite air that also can reduce with the oxygen concn of rare gas elementes such as mixing nitrogen.
Preferably suitably select the temperature of reaction of liquid-phase oxidation, be generally 120～220 ℃.For example in the method for oxidation that does not use the bromine compounds catalyzer, temperature of reaction is more fortunately below 160 ℃ usually.Pressure can suitably be selected too, and preferably solvent (for example acetate) becomes the gasiform pressure range.
Oxidation reaction heat is mainly removed through aqueous acetic acid solvent flash distillation (flash evaporation).The cut (exhaust) that promptly leaves oxidation reactor mainly contains vaporized acetate and water, also contains low-boiling products in a spot of oxidation reaction by-products and unreacted alkyl substituent aromatic hydrocarbon etc. in addition.This steam becomes liquid through condenser cooling, condensation, and its part is re-used as oxidation solvent and is back in the oxidation reactor usually.And another part is to be admitted to dehydration tower for removing the water that oxidizing reaction generates, and for component distillation of the present invention, the acetate of dehydration is re-used as oxidation solvent and sends in the oxidation reactor.
The liquid-phase oxidation of the aromatic hydrocarbons that alkyl replaces usually with one, carry out with a plurality of reactors in case of necessity.Reaction solution after oxidizing reaction finishes is sent into 1 or the successive partial crystallization device of step-down successively more than 2 if necessary, hurried cooling effect by solvent is cooled to it and separately the corresponding temperature of pressure, the most of crystallization of the aromatic carboxylic acid that generates is separated out, and becomes soup compound.Soup compound can any Crystallization Separation means, are separated into aromatic carboxylic acid crystalline filter cake and oxidizing reaction mother liquor as rotary vacuum filter method, centrifugal separation or other appropriate separation methods.Aromatic carboxylic acid crystalline filter cake removes the solvent of attachment removal in case of necessity with after acetate or the water washing with moisture eliminator.Again as required, by form slurries again in the reaction mother liquor that is mainly formed by water, recrystallize after adding the water conservancy project preface reduces the impurity in the crystallization, makes with extra care.After operations such as solid-liquid separation, washing, drying, obtain aromatic carboxylic acid then.
With Fig. 1 Azotropic distillation method of the present invention is described below and uses this method to carry out the method that aromatic carboxylic acid is made.Fig. 1 is the schema of an example that is suitable for the still-process of the inventive method.The 11st, azeotropic distillation column.The aliphatic carboxylic acid esters, of moisture, (acetate etc.) aliphatic carboxylic acid and impurity etc. retort solution by pipeline 40,41,42 etc. (in occasion with a plurality of supply lines supplies, usually the composition of each solution to be distilled is different mutually), and entrainer is by pipeline 15, supply with azeotropic distillation column respectively, carry out component distillation.
For supplying with the required heat of distillation, with heat exchanger 14 heating.Available heated oil and heating steam are used as thermal source.Here show the atmospheric boiling point temperature use than acetate high, specifically be the example of 0.35MPa steam.
Contain and to reduce the material of concentration and the azeotropic mixture steam of entrainer (component distillation overhead fraction) by component distillation and be sent to water cooler 12, here condensation from the cat head of azeotropic distillation column 11.Resulting phlegma is separated into 2 phases in liquid liquid separator tank 13, get from dividing here.Preferably select suitable separation means according to the character of azeotropic mixture.
In Fig. 1, be that the part of the phase (water) of principal constituent is sent into stripping tower 21 through pipeline 17 with the material that will reduce concentration in the liquid liquid separator tank 13.And the part of water is back to azeotropic distillation column 11 through the water that pipeline 16 can be used as backflow.Entrainer is recycled through pipeline 15.Pipeline 15 and pipeline 16 are connected to the cat head or the midsection of azeotropic distillation column 11 as required.The pipeline 15 and 16 that enters this azeotropic distillation column 11 can be respectively one or more.The material that can use the common pipeline to make entrainer and will reduce is sent azeotropic distillation column 11 together back to, also can return by pipeline separately.
The target substance (for example aliphatic carboxylic acid) that reduces with water content is that the liquid of principal constituent takes out at the bottom of the tower of azeotropic distillation column 11 through pipeline 19.And target substance is when being used for the aliphatic carboxylic acid of aromatic carboxylic acid manufacture method of the present invention, takes out mainly the liquid that aromatic hydrocarbons that the raw material alkyl by water and aromatic carboxylic acid replaces is formed from the pipeline 22 of midsection.
Reclaim organic composition (in aromatic carboxylic acid manufacture method of the present invention, mainly being the impurity aliphatic carboxylic acid esters) in the stripping tower 21, the material that will reduce through the isolating water of component distillation etc. is used for the aromatic carboxylic acid manufacturing processed through pipeline 18 circulations, effectively be utilized there, perhaps go out of use.The organic composition that is reclaimed in the stripping tower 21 is sent into entrainer recovery tower 24 through pipeline 23, is separated into entrainer and impurity aliphatic carboxylic acid esters, at this.Entrainer is recovered at the bottom of tower, is returned azeotropic distillation column 11 through pipeline 25 and 15.Above-mentioned aliphatic carboxylic acid esters, is recovered through pipeline 26.This aliphatic carboxylic acid esters, can preserve as requested, also part or all can be circulated in the oxidizing reaction operation of making aromatic carboxylic acid.With branching entrainer and at least a portion of above-mentioned aliphatic carboxylic acid esters,'s mixture directly import this entrainer recovery tower 24 through pipeline 27.Though do not express among the figure, can utilize water cooler 12 that the gas that is produced is imported in the entrainer recovery tower 24 yet.
According to Fig. 1 the method that the present invention reclaims the impurity aliphatic acid ester is specifically described.
Be recycled to the outer above-mentioned aliphatic carboxylic acid esters,'s of system amount, promptly the resulting amount of operation (5) is represented with this amount of substance that pipeline 26 is discharged.Can contain impurity such as entrainer, water, aliphatic hydrocarbon in this ejecta, be liquid, gas or their mixture.The water liquid of the overhead fraction condensation liquid phase by azeotropic distillation column 11 imports the above-mentioned aliphatic carboxylic acid esters,'s of recovery process amount, uses this amount of substance that flows into through pipeline 17 to represent.With respect to the outer above-mentioned aliphatic carboxylic acid esters,'s who is reclaimed of system total amount, recovery ratio more than 30%, better more than 40%, imports recovery process through water more fortunately more than 20%, is preferably from energy efficiency.
And in the entrainer recovery process, can be in the liquid effluent 25 at the bottom of the tower of entrainer recovery tower 24 with the above-mentioned aliphatic carboxylic acid esters, of minute quantity.Therefore among the present invention, utilize through water and through oil phase and import the aliphatic carboxylic acid esters,'s of recovery process amount, the ratio of the aliphatic carboxylic acid esters,'s who imports through water amount can be calculated above-mentioned recovery ratio.
The above-mentioned aliphatic carboxylic acid esters,'s who imports without water logistics imports entrainer recovery towers 24 through pipeline 27.This logistics can be gas, liquid, or their mixture, and is the same as WO98/45239 communique record, also the gas that can also be taken place with water cooler 12.
And in the oil phase that liquid liquid separator tank 13 obtains the concentration ratio normally 1: 100～1: 2 of impurity aliphatic carboxylic acid esters, and entrainer, it is disadvantageous only reclaiming above-mentioned aliphatic carboxylic acid esters, from this oil phase.On the other hand, if observe the concentration of aqueous phase, this ratio normally 1: 1～15: 1 helps above-mentioned aliphatic carboxylic acid esters,'s recovery.Therefore, the ratio that reclaims above-mentioned aliphatic carboxylic acid esters, from water reduces more, and the load of recovery process raises, if this recovery ratio is low excessively, it is remarkable that the increase of energy expenditure becomes.So this recovery ratio is better more than 20%.The adjusting of this recovery ratio, the adjusting of the flow of approach shown in flow that can be by approach shown in the pipeline 27 and the pipeline 28 is carried out.In addition, under the situation by the adjusting of the approach shown in the pipeline 28, preferably do not change water quantity of reflux total amount and regulate.And the water that stripping tower 21 is discharged is recycled to liquid liquid separator tank 13 and also may improves this recovery ratio.
In the present invention, impurity aliphatic carboxylic acid esters,'s distribution when for example carrying out the separation of liquid liquid with liquid liquid separator tank, big more with the ratio of (this material total amount of aqueous phase)/(this material total amount in the oil phase) expression, the effect of the inventive method is good more.It for example can be drawn by (the above-mentioned aliphatic carboxylic acid esters,'s of water flow * aqueous phase of time per unit concentration)/(above-mentioned aliphatic carboxylic acid esters,'s concentration in the oil phase flow * oil phase of time per unit).
Usually above-mentioned aliphatic carboxylic acid esters,'s concentration is 1～50 weight % in the oil phase, and this concentration depends on the amount of wanting the above-mentioned aliphatic carboxylic acid esters, that reclaims through the approach shown in the pipeline 25 and this material partition rate at water and oil phase.
Under the identical condition of water yield, change the occasion of entrainer kind at this material, the high entrainer of the partition rate in the oil phase in this way, above-mentioned aliphatic carboxylic acid esters,'s absolute magnitude is big more in oil phase.This means that this amount that enters oil phase together increases, the oil phase total amount that promptly contains entrainer increases, and this is all having shortcoming aspect equipment and the energy consumption.Particularly the energy consumption aspect will all reclaim entrainer from cat head, and institute's heat requirement increases.But in the process that enforcement pipeline 16 such water reflux, by keeping the discharge from this material of pipeline 17, reduce the water quantity of reflux of pipeline 16, the heat increase that can make entrainer increase part reduces.Enumerate the impurity aliphatic carboxylic acid esters, who attends by oil phase in the WO98/45239 communique and increased, and do not carried out the example that water refluxes.
Therefore, the present invention better is that to attend by the impurity aliphatic carboxylic acid esters,'s of oil phase amount be below 20 times of amount that attend by the above-mentioned aliphatic carboxylic acid esters, of water, below 17 times, is better implementing below 15 times more fortunately, perhaps better is to carry out water to reflux.The flow quantity of the concentration that the amount that attends by here in addition, depends on this material and this approach of flowing through long-pending.
Among Fig. 1, represent recovery process, also tower 21 and 24 can be linked and the reboiler that saves tower 24 is represented this operation with 2 distillation towers.
Necessary Separation and Recovery impurity aliphatic carboxylic acid esters,'s component distillation, the present invention has bigger effect.Better form as above-mentioned suitable example of the present invention, the method of the operating condition of may command azeotropic distillation column, it can make aliphatic carboxylic acid concentration in the azeotropic distillation column overhead fraction 1, below the 000ppm, and the entrainer concentration at the bottom of this component distillation Tata in the liquid effluent is below 100ppm, and the concentration of the impurity aliphatic carboxylic acid esters, in the entrainer is below 25%.
Embodiment
Illustrate in greater detail specific form of the present invention by the following examples, but the present invention only otherwise surmount its main points, is not subjected to the restriction of the following example.
Embodiment 1
Use contains the conduct solution to be distilled of the aqueous mixture of acetate and methyl acetate, makes entrainer with n-butyl acetate, distills processing continuously with distillation flow process as shown in Figure 1.
Solution to be distilled is from carrying out liquid-phase oxidation by p-Xylol to make the solution that is reclaimed each operation of terephthalic acid process, the mixture that total feed rate of its time per unit is made up of acetate 116.9 weight parts, water 25.5 weight parts, methyl acetate 1.3 weight parts, they are fed to theoretical plate number respectively as 3 different chargings of forming is on 21 the 7th, 16, the 21 block of column plate of azeotropic distillation column 11.Liquid effluent is the concentrated acetate of time per unit 128.2 weight parts at the bottom of the tower that is taken out at the bottom of the tower of azeotropic distillation column.At the bottom of the tower in the liquid effluent butylacetate concentration below 250ppm.
P-Xylol is discharged and reclaimed from the stage casing by pipeline 22, is that 13 entrainer recovery tower 24 distills recovery with methyl acetate by theoretical plate number.Obtain containing the water of azeotropic composition and the steam of entrainer from the cat head of azeotropic distillation column 11,, be recovered in liquid liquid separator tank 13 its cooling.All introducing theoretical plate numbers through pipeline 17 by the water liquid in liquid liquid separator tank 13 isolating 2 liquid phases is 8 stripping tower 21, divides two pipelines 18 and 28 to discharge after removing organic composition.Pipeline 18 discharge as waste water, pipeline 28 enters azeotropic distillation column 11 as recirculation water.By wastewater flow rate (W
w) and as the amount (W that returns of recirculation water
r) the decision backflow water yield, so that by W
r/ W
wDefined recirculation water ratio reaches desired value.In the present embodiment, the amount (W of the water liquid of discharging at time per unit
w) be 17.3 weight parts, recirculation water (W
r) amount is 11 weight parts, at recirculation water than being to implement under 0.64 the condition.The organic composition that stripping tower 21 reclaims moves into entrainer recovery tower 24 through pipeline 23.Entrainer has carried out the separation of liquid liquid in liquid liquid separator tank 13 after, supply with azeotropic distillation columns 11 through pipeline 15 circulations.The loss part of entrainer is replenished by pipeline 30.In addition,, be provided with pipeline 27 as requested, entrainer introduced on the 8th block of column plate of entrainer recovery tower 24 for reclaiming methyl acetate.The flow through azeotropic dosage of this pipeline 27 of adjustment is set the amount of the outer methyl acetate of the system that is recycled to and is imported the ratio of the amount of the methyl acetate in the recovery process through the water liquid of overhead condensation liquid.Concrete is, with the amount that is recycled to the outer methyl acetate of system as the amount of the methyl acetate by pipeline 26, calculate as the amount of the methyl acetate by pipeline 17 through the amount of the methyl acetate of the water liquid importing recovery process of overhead condensation liquid.
With respect to the amount that is recycled to the outer methyl acetate of system, the amount that imports the methyl acetate of recovery process through the water liquid of overhead condensation liquid is 24%, the concentration of the n-butyl acetate in the recovery methyl acetate of pipeline 26 is 0.90%, and the heat that entrainer recovery tower 24 uses is 1.3Gcal/hr.
Embodiment 2
Except with among the embodiment 1 with respect to the amount that is recycled to the methyl acetate the system, the amount that imports the methyl acetate of recovery process through the water liquid of overhead condensation liquid is reduced to beyond 15%, other all distill processing equally with embodiment 1.The heat that uses in the entrainer recovery tower 24 is 2.0Gcal/hr.
Can determine that like this increase as if the ratio that directly reclaims methyl acetate from oil phase, the heat of use also increases.
Describe the present invention in detail or with reference to specific embodiment, but those skilled in the art know, can not break away from the spirit and scope of the present invention and do various changes and correction.
The Japan special permission application (special be willing to 2001-051553) of the application to be proposed February 27 calendar year 2001 comprises its content as reference here.
The possibility of the utilization on the industry
According to the present invention, still-process that can be complicated carries out to low energy consumption azeotropic distillation. So this Have good effect on the bright method earthquake expense He in the environmental protection, and owing to it simply has stability The effect that loss high, active ingredient reduces.
Claims (11)
1. Azotropic distillation method is characterized in that, comprises following operation (1)～(5) at least,
Operation (1) is the solution to be distilled entrainer component distillation with the ester of the saturated or unsaturated aliphatic carboxylic acid of the saturated or unsaturated aliphatic carboxylic acid of moisture, carbonatoms 2-6 and carbonatoms 2-6, obtain the saturated or unsaturated aliphatic carboxylic acid of the carbonatoms 2-6 that water content reduces and the operation of the overhead fraction that moisture is concentrated
Operation (2) is to make this overhead fraction condensation, obtains gas and is divided into water and the operation of oil phase biphase phlegma,
Operation (3) is the operation of getting water and oil phase from this phlegma,
Operation (4) is part or all distillation of the water that will get, obtains containing the operation of the overhead fraction that above-mentioned aliphatic carboxylic acid esters, and water content reduce,
Part or all of operation (5) oil phase that to be overhead fraction that operation (4) is obtained get with operation (3) distilled, and part or all of the above-mentioned aliphatic carboxylic acid esters, of this distillation gained is recycled to the outer operation of component distillation system.
2. Azotropic distillation method according to claim 1 is characterized in that, the concentration of the above-mentioned aliphatic carboxylic acid esters, during component distillation in the oil phase is 3～50 weight %.
3. Azotropic distillation method according to claim 1 and 2 is characterized in that, at least a portion of the oil phase that operation (3) is got is returned azeotropic distillation column.
4. Azotropic distillation method according to claim 1 is characterized in that, the aliphatic carboxylic acid esters, of operation (5) gained more than 20% from the overhead fraction of operation (4) gained.
5. Azotropic distillation method according to claim 1 is characterized in that, among the aliphatic carboxylic acid esters, of operation (5) gained, from part or all aliphatic carboxylic acid esters, of the oil phase of getting below 80%.
6. Azotropic distillation method according to claim 1 is characterized in that, the aliphatic carboxylic acid esters,'s of operation (5) gained a part is returned azeotropic distillation column.
7. Azotropic distillation method according to claim 1 is characterized in that, the water that at least a portion operation (3) is got returns azeotropic distillation column as reflux solution.
8. Azotropic distillation method according to claim 1 is characterized in that, in operation (5), part or all of the oil phase that the overhead fraction and the operation (3) of operation (4) gained are got and the gas of operation (2) gained distill together.
9. Azotropic distillation method according to claim 1, it is characterized in that the above-mentioned aliphatic carboxylic acid esters,'s who is reclaimed amount is below 20 times of amount from the above-mentioned aliphatic carboxylic acid esters, that water reclaimed of this phlegma from the oil phase of the phlegma of operation (2) gained.
10. the manufacture method of aromatic carboxylic acid, it comprises that the aromatic hydrocarbons that alkyl is replaced is in the aliphatic carboxylic acid solvent of 2-6 times of weight, water-content in solvent is 4-25 weight %, there is the catalyzer that contains transistion metal compound, temperature is to carry out liquid-phase oxidation with molecular oxygen and air under 120-220 ℃ the condition, resulting slurries as resultant of reaction are carried out solid-liquid separation, obtain aromatic carboxylic acid, it is characterized in that, with the cut vapour condensation that produces in the oxidizing reaction, with the part of phlegma as solvent refluxing in oxidation reactor, another part is carried out component distillation as solution to be distilled with each described method in the claim 1～9, the aliphatic carboxylic acid of water content minimizing is used as the solvent of liquid-phase oxidation.
11. the manufacture method of aromatic carboxylic acid according to claim 10 is characterized in that, the aliphatic carboxylic acid esters, that the operation (5) of at least a portion is reclaimed carries out recirculation in the arene oxidizing that alkyl is replaced makes any operation of aromatic carboxylic acid.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001051553 | 2001-02-27 | ||
| JP51553/01 | 2001-02-27 | ||
| JP51553/2001 | 2001-02-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1492850A CN1492850A (en) | 2004-04-28 |
| CN1226267C true CN1226267C (en) | 2005-11-09 |
Family
ID=18912316
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02805492 Expired - Lifetime CN1226267C (en) | 2001-02-27 | 2002-02-18 | Azeotropic distillation process |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN1226267C (en) |
| WO (1) | WO2002068375A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1300088C (en) * | 2005-03-25 | 2007-02-14 | 扬子石油化工股份有限公司 | Method for recovering raw material, solvent and by-product generated in procedure of producing aromatic carboxylic acid |
| CN101854989A (en) * | 2007-07-18 | 2010-10-06 | 因维斯塔技术有限公司 | Azeotropic distillation with entrainer regeneration |
| CN102020549B (en) * | 2009-09-10 | 2013-07-24 | 中国石油化工股份有限公司 | Continuous production method for separating acetic acid from water by azeotropic distillation |
| CN103012102B (en) * | 2011-09-27 | 2014-09-17 | 中国石油化工股份有限公司 | Method of recovering acetic acid and water in production of aromatic carboxylic acid |
| CN109467501B (en) * | 2018-08-03 | 2024-02-20 | 内蒙古蒙维科技有限公司 | Process and device for refining acetic acid and regenerating entrainer in polyvinyl alcohol mother liquor recovery unit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW483886B (en) * | 1998-08-11 | 2002-04-21 | Du Pont | Method for recovering methyl acetate and residual acetic acid in the production of pure terephtalic acid |
-
2002
- 2002-02-18 WO PCT/JP2002/001372 patent/WO2002068375A1/en active Application Filing
- 2002-02-18 CN CN 02805492 patent/CN1226267C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| WO2002068375A1 (en) | 2002-09-06 |
| CN1492850A (en) | 2004-04-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1022827C (en) | Technology for nitration of ortho-dichlorobenzene with mixed acid processing | |
| CN1058700C (en) | Process for purifying acetic acid | |
| CN1163289C (en) | Cascade reboiling of ethylbenzene/styrene columns | |
| CN1550480A (en) | Method for manufacturing polymeriable substance | |
| CN1259291C (en) | Tower processing method and equipment | |
| CN1099405C (en) | Process for refining butylacrylate | |
| CN1572767A (en) | Extraction process for removal of impurities from mother liquor in the synthesis of carboxylic acid | |
| CN1272303C (en) | Prodn. process of propenoic acid | |
| CN1472187A (en) | Preparing method for acrylic acid | |
| CN1287113A (en) | Process for producing (methyl) propenoic acid | |
| CN100389848C (en) | Method for purifying (meth) acrylic acid | |
| CN1137079C (en) | Method for preparing acrylic acid and acrylic acid esters | |
| CN1914145A (en) | Method for producing aromatic carboxylic acid | |
| CN1178892C (en) | Process for purifying propenoic acid | |
| CN1277799C (en) | Process for producing (meth)acrylic acid compound | |
| CN1226267C (en) | Azeotropic distillation process | |
| CN103183607B (en) | A kind of production method mixing fragrant dioctyl phthalate | |
| CN1117062C (en) | Process for generating vinyl carboxylate esters | |
| CN100342951C (en) | Separation apparatus, reaction apparatus and method for producing aromatic carboxylic acid | |
| CN1914146A (en) | Method for azeotropic distillation | |
| US5959140A (en) | Process for producing aromatic carboxylic acid | |
| CN1236835C (en) | Azeotropic distillation method | |
| CN1867537A (en) | System and method for acetic acid recovery during terephthalic acid production | |
| CN100519503C (en) | Method of recovering acetic acid in process of preparing aromatic carboxyl acid | |
| JP2002326001A (en) | Azeotropic distillation method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: Tokyo, Japan Patentee after: MITSUBISHI CHEMICAL Corp. Address before: Tokyo, Japan Patentee before: MITSUBISHI RAYON Co.,Ltd. |
|
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20171024 Address after: Tokyo, Japan Patentee after: MITSUBISHI RAYON Co.,Ltd. Address before: Tokyo, Japan Patentee before: MITSUBISHI CHEMICAL Corp. |
|
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20051109 |