CN88100630A

CN88100630A - The preparation method of the p-Xylol of purity at least 99.5%

Info

Publication number: CN88100630A
Application number: CN88100630.0A
Authority: CN
Inventors: 冈特·普派尔
Original assignee: Krupp Koppers GmbH
Current assignee: Krupp Koppers GmbH
Priority date: 1987-02-06
Filing date: 1988-02-05
Publication date: 1988-11-09
Also published as: TR23271A; ES2006067A6; WO1988005766A1; CN1016685B; KR890700559A; PT86712A; PT86712B

Abstract

The inventive method is from the head product that goes out of p-Xylol content at least 99%.Head product imports inert liq with liquid state and is preferably in the water, and inert liquid temperature remains on below the pure p-Xylol fusing point.The crystal of wherein separating out separated with liquid and with its fusion.Molten mass promptly is made up of at least 99.5% p-Xylol purity.

Description

The present invention relates to produce the method for the p-Xylol of purity at least 99.5% with the head product of p-Xylol content at least 99%.

At present industrial almost all is to produce pure p-Xylol with dimethylbenzene cut (the about 135-145 of Kp ℃) without exception, in the dimethylbenzene cut except three kinds of xylene isomers and also may contain ethylbenzene and non-aromatics.This class dimethylbenzene cut is to use coking plant benzene, and reformate or pyrolysis gasoline obtain through distillation and/or extraction, and it is formed with different the changing of originating, and wherein p-Xylol content is generally the 16-20%(body).In order to isolate p-Xylol from used various starting materials, the industrial serial of methods that proposed, these methods are all operated according to separation known mode such as crystallization and absorption.Adopting which kind of separation method is according to the decision of the composition of used starting material, as for its detailed problem, need not here to be discussed in detail, because these methods are not purposes of the present invention.In any case but these methods of industrial application can't make p-Xylol reach at least 99% purity.

But some supplier has used sorbent material more particularly and provides the p-Xylol of purity at least 99.5% to market recently, and this has correspondingly caused the requirement to this very straight product certainly.

But the existing equipment of many manufacturing p-Xylol can't guarantee that the p-Xylol of producing reaches this purity.In order to reach this purpose, just existing equipment must be transformed by novel improved separation method.But therefore bring the research and development investment except meeting like this and existing equipment is stopped production long period of time, the production loss that causes therefrom is same accrued to be uneconomic investment factor.

Therefore the industrial a kind of method of developing that presses for can be used the p-Xylol that existing equipment is produced purity at least 99.5% with it, need not to transform existing installation again simultaneously and need not to interrupt running.

Is from head product by the present invention in order to the method for finishing this task, p-Xylol content at least 99% in the head product, and available existing equipment makes without difficulty.Wherein according to the present invention, can consider liquid head product is introduced inert liq, its temperature remains on below the pure p-Xylol fusing point, the crystal that will stir in tripping device then and separate out is separated from inert liq and subsequently with its fusing, in this process, will remain the residual liquid that is in the melting plant and separate, can from melting plant, emit the satisfactory p-Xylol of purity afterwards with the fused crystal.

That is to say that key is to consider to have used the operation steps that is located at after the existing installation in the methods of the invention, so just needn't transform or with its stopping production this equipment fully.

Can be regarded as p-Xylol as inert liq among the present invention and do not dissolve fully or minute quantity dissolved liquid is only arranged, object lesson can be enumerated: the mixture of being made up of as methyl alcohol, ethanol and ethylene glycol water and some alcohol.

But preferably use water as inert solvent, it is suitable especially and see that from the investment angle advantage is also arranged to have shown that water is implemented the inventive method.

As previously mentioned, the temperature of inert liq should remain below the fusing point of pure p-Xylol below 13.26 ℃ when importing liquid head product.Preferably under 0-12 ℃ fluid temperature, operate.If use water as inert liq, so in case of necessity can be to wherein adding an amount of frostproofer such as ethylene glycol.

Other details of the inventive method can be found out from dependent claims and be explained with reference to flow process shown in the accompanying drawing following, has only schematically expressed the necessary equipment of explanation the inventive method among the figure.

The head product of the p-Xylol content at least 99% that comes from not shown preposition production unit imports mixing tank 2 through conduit 1 with liquid state, and temperature is lower than the desired inert liq of pure p-Xylol fusing point and imports through conduit 3.The mixture that forms is sent into tripping device 6 by the pump 4 that is contained in the conduit 5, and the agitator 7 that motor drives wherein is housed.The p-Xylol crystal that forms in the tripping device 6 can rise and is pressed in the receptor 9 through conduit 8 by the agitator 7 that is provided in the liquid because of the density difference, and the agitator 10 that motor drives wherein is housed equally.To emit and send into tripping device 12 through conduit 11 from receptor be separating centrifuge or the filtration unit to liquid-mixed crystal after about 5-30 minute residence time.The residence time of p-Xylol crystal-liquid mixture is depended on the radiating rate of heat of crystallization in the inert liq during the crystallization.It is fast more to dispel the heat, and the residence time is short more.Crystal separates with liquid after conduit 13 is sent in the melting plant 14 in tripping device 12, and steam heating coil 15 wherein is housed.Crystal is fusion once more under the heating coil effect in melting plant 14.Some residual liquids are separated and as the heavier bottom that is collected at melting plant 14 mutually with this, the fusion crystal then from melting plant 14 tops through conduit 16 dischargings, be the satisfactory product of purity, its p-Xylol content at least 99.5%.

The residual liquid that melting plant 14 bottoms are gathered moves in the filtrate reservoir 18 through conduit 17.Valve 19 is housed in the conduit 17.Can adjust the liquid output like this and therefore the separating layer between fusion p-Xylol and the inert liq in the melting plant be remained on the constant level.The liquid that also imports from device 12 in the filtrate reservoir 18 through conduit 20.Tell the hydrocarbon that is contained in the inert liq in this reservoir 18 by being separated.Hydrocarbon is told and can be emitted through conduit 21 at fluid surface as light phase, and said hydrocarbon is essentially the mixture of o-Xylol and m-xylene and ethylbenzene.This mixture can return the head product production technique.

The inert liq that separates with hydrocarbon is collected at filtrate reservoir 18 bottoms and can sends into interchanger 24 after conduit 22 is by pump 23.This interchanger links to each other with coolant loop 25, can make the inert liq in the interchanger 25 carry out just returning mixing tank 2 through conduit 4 after the necessary secondary cooling like this.After pump 23, also be provided with valve 26 in the conduit 22, can monitor the amount of liquid that infeeds interchanger 24 with this.In addition conduit 27 is connected in the conduit 22, can makes not crystalliferous liquid emit and import liquid flow the conduit 22 from tripping device 6 bottoms thus, wherein valve 28 is in order to regulate the liquid output.

Tripping device 6 is connected with mixing tank 2 through conduit 29, can crystal-liquid mixture shunting be returned mixing tank 2 from tripping device 6 by this conduit in case of necessity, wherein regulates fractional flow with valve 30.Can improve the crystallization effect of p-Xylol like this.

The industrial applicibility of the inventive method can illustrate with following examples.Wherein p-Xylol content 99% and temperature are that 25 ℃ head product mixes with the about 5 ℃ water of 1: 8 ratio and temperature in mixing tank 2.P-Xylol promptly can deposit out and can put among the melting plant 14 through after the tripping device 12 as vacuum filter by crystalline form within short several minutes.And from then on promptly emit the p-Xylol that purity reaches 99.6-99.7% in the melting plant through conduit 16.

Claims

1, produces the method for purity with the head product of p-Xylol content at least 99% at least 99.5% p-Xylol, it is characterized in that, liquid head product is introduced inert liq, its temperature remains on below the pure p-Xylol fusing point, the crystal that will stir in tripping device then and separate out is separated from inert liq and subsequently with its fusing, in this process, will remain the residual liquid that is in the melting plant and separate, can from melting plant, emit the satisfactory p-Xylol of purity afterwards with the fused crystal.

2, according to the method for claim 1, it is characterized in that, preferably adopt and use water as inert liq.

According to the method for claim 1 and 2, it is characterized in that 3, the inert fluid temperature preferably remains 0-12 ℃ when importing head product.

4, according to the method for claim 1-3, it is characterized in that, when using water as inert liq in case of necessity also to wherein adding frostproofer such as ethylene glycol.

According to the method for claim 1-4, it is characterized in that 5, after telling the crystal phase inert liq is imported the filtrate reservoir, wherein liquid separates with the hydrocarbon of bringing into simultaneously through being separated and carries out secondary cooling back loopback again and go into technical process.

6, according to the method for claim 1-5, it is characterized in that, head product preparation technology is gone in the hydrocarbon loopback of mainly being made up of o-Xylol and p-Xylol and ethylbenzene that separates with inert liq in the filtrate reservoir.

7, according to the method for claim 1-6, it is characterized in that the same filtrate reservoir that imports a large amount of treatment liq of the inert liq of telling in the melting plant.

8, according to the method for claim 1-7, it is characterized in that, the shunting of crystal liquid mixture was gone into mixing tank from the tripping device loopback before telling the crystal phase, wherein liquid head product is imported among the inert liq.