DE2006863A1 - Process for the recovery of styrene and xylenes from Krackol - Google Patents

Description

Dr. Hans-Heinrich Willrath _{n QC} . . ■ · ■ _D - © 2 Wiesbaden ii.Pebr. 1970

"-. '■ Dr. Dieter Weber 4UUböt? 4" / * "** ^{1327 i: t} / ^e e

_ ' ^r -Güstav-Freytag-Stri6e 25 -

PATENT LAWYERS -. , · .® (08121) 3/2720

Telegram address: WILLPATENT --... ■ -. '■.

Postal check: Frankfurt / Main 6763 ", _ _, j

Bank: Dresdner Bank AG. Wiesbsden Xf ti J

Account no. 8768Ö7. - ———

Toray Industries, Inc. 2, Nihonbashi-Muromachi 2-chome Chuo-ku, Tokyo / Japan

Process for the production of styrene and xylenes

from Kraeköi

Priorities: v. February 17, 1969 in Japan Note No .: 11 104/69

v. August 26 , 1969 in Japan, Note No. s 66> 886/69

The present invention relates to a method of extraction aromatic hydrocarbons found in cracking oil are contained and which are produced as by-products in the production of ethylene by thermal decomposition (cracking) obtained from naphtha. The present invention also relates to a process for the recovery of styrene and xylene from the cracking oil directly by extractive distillation under Use of the solvents defined below.

Ethylene, which is one of the most important intermediate products in the petrochemical industry, is Refinery gas, a natural gas or obtained from naphtha

109337/1678 - 2 -

nen. However, cracking naphtha is the main method for the production of ethylene in most parts of the world where there is not enough natural gas.

In the cracking of naphtha, naphtha is thermally cracked at around 800 C, and ethylene is recovered in the process a yield of about 20 to about 35 weight percent. Simultaneously a large amount of byproducts called "cracking oil" are obtained. The oil consists of many different connections. Since there is a large amount of unsaturated hydrocarbons, such as olefins, Containing dienes, acetylene derivatives, etc., it is very difficult to get a specific component directly from the Separate and refine cracking oil.

(In the present invention, the term "means unsaturated Hydrocarbons ** Hydrocarbons with a olefinic double bond or an acetylenic triple bond, does not mean, however, the double bond of an aromatic ring.) Venn however a large amount of the Cracking oil is formed and it contains a large amount of aromatic hydrocarbons, it is very important these aromatic hydrocarbons to reduce the Exploiting ethylene costs.

So far, aromatic hydrocarbons such as benzene, Toluene and xylene, which are contained in the cracking oil which is obtained in the production of ethylene, are

109837/1670

won that in the first stage "unsaturated hydrocarbons, such as monoolefins and dienes, were hydrogenated to form saturated hydrocarbons, and aromatic" hydrocarbons were then separated off by extraction. Namely, hydrocarbons with up to 5 carbon atoms and hydrocarbons with more than 9 carbon atoms were first removed from the cracking oil by distillation, the resulting mixture was hydrogenated to convert unsaturated hydrocarbons such as olefins, dienes and acetylene derivatives, and then became aromatic hydrocarbons separated from the mixture by extraction using solvents such as diethylene glycol, sulfolane and N-methylpyrrolidone. Benzene, toluene, xylene and other aromatic hydrocarbons were separated by further distillation of the resulting hydrocarbons . the quality on the Xylolqualxtät regard was to determine However, provided that in this xylene about kO to 50 wt -.. contained $> ethylbenzene such xylene may be unsuitable as a raw material for the production of p-xylene the composition of this xylene, viz. an add Ammensierung of aromatic hydrocarbons with 8 carbon atoms, depends on the conditions of the thermal degradation of the naphtha. Ordinary cracking oil, however, has about 30 to kO % by weight of styrene instead of ethylbenzene oil before the hydrogenation. Styrene contained in the cracking oil is converted into ethylbenzene by hydrogenation. Try to get more ethylene by cracking it

■■ -: '-. . · ■: .- '■ - ■■ ■ "■ - ■ ■'. ■■■■ '■ _ 4 -

109837/1678

Obtaining the naphtha under more severe cracking conditions also tended to reduce the styrene content in the Increase cracking oil. Hence, it is difficult to make xylene good Quality, namely xylene with a high concentration of p-xylene, can be obtained from cracking oil using known methods. In addition, in the prior art methods, it is necessary to supply a large amount of hydrogen gas use, because of the hydrogenation of the styrene contained in the gas oil.

According to the invention, a new and advantageous one is obtained Process for the production of aromatic hydrocarbons, especially of styrene and xylene from cracking oil, and this process consists in concentrating the aromatic C 8 hydrocarbons hydrocarbons with up to about 5 »preferably 7 carbon atoms and more than 9 carbon atoms, made by cracking oil fractional distillation separates a xylene-containing fraction at the top of the Destillati oiricolonne and a styrene containing residue at the bottom of the distillation column recovered by extractive distillation, and, if necessary, hydrogenated the fraction containing the xylene.

It is an object of this invention to make aromatic hydrocarbons, particular xylenes and styrene, from which when cracked to obtain cracked oil obtained from naphtha. It is also an object of the invention to have xylene at a high concentration on p-xylene from a hydrocarbon fraction with 8 carbon atoms, which is contained in cracking oil to win *.

1Ü9837 / 1678

Another object of the invention is to make styrene directly Obtain cracking oil. The other objects of the invention will hereinafter become apparent in detail.

The present invention relates to a method of extraction more aromatic. Hydrocarbons from cracking oil, which consists in that one

(l.) hydrocarbons having up to about 51, preferably about 7 carbon atoms and more than 9 carbon atoms, removed from the cracking oil by fractional distillation,

(2.) the fraction consisting mainly of xylene from the top of the distillation column and the residue consisting essentially of styrene and solvent from the bottom of the distillation column duxdi extractive distillation of the middle fraction from stage (l.) Decreases and:

(3.) If necessary, the xylene-containing fraction obtained in stage (2.) is hydrogenated.

In the present invention, it is sometimes preferred that the method be carried out in the following manner:

(l.) M an separates hydrocarbons with about 5 carbon atoms or less from cracking oil by fractional distillation,

(2.) trannt benaol, toluene (as a fraction with lower

1Ö903 7/167 β - ⁶ -

Boiling temperature as xylenes or styrenes) and hydrocarbons with at least about 9 carbon atoms (as a residue with a higher boiling temperature than xylenes or styrenes) by fractional distillation,

(ß.) Draws off the xylene fraction from the top of the distillation column and styrene from the bottom of the distillation column by extractive distillation of the xylenes and styrene-containing fraction obtained in step (2.) and

(4.) hydrogenates the xylene fraction.

According to the present invention, benzene, toluene, xylene and styrene can be efficiently and economically extracted from the cracking oil be won.

The cracking oil used in the present invention may consist of by-products of a plant, the ethylene duKh heat breakdown (cracking) of naphtha at about 700 to 1000 ° C. The cracking oil consists of a large number of components and it is difficult to determine its composition really to be determined, as different compositions result under different cracking conditions. at of the present invention, however, all cracking oils are to be considered useful, from which hydrocarbons with up to to 5 carbon atoms were removed. It is not necessary, to completely remove these hydrocarbons,

109837/1678 " ⁷ "

but the total remaining content of these hydrocarbons should not exceed about 1% by weight. As above mentioned, it is not possible to precisely determine the cracking oil composition. but usually a Krackol, that is about 30 to 80 wt containing aromatic hydrocarbons can be used. Of course the invention is not limited to the above-mentioned contents * The cracking oils are industrially.light as by-products from investment available, the olefins (ethylene) by cracking ÜJapht.fe to produce. '

The stage of removal of hydrocarbons with up to '5 (-7) ■' ■ carbon atoms and with more than 9 carbon atoms from the cracking oil is usually through fractional distillation carried out. All known Distillate chains are in the present invention useful. Usually the distillation is done at a Temperature of about 70 C under normal atmospheric pressure with a reflux ratio of about 2, preferably at a temperature of 135 C and 150 C des to normal Atmospheric pressure converted value and with a reflux ratio carried out by 3. In this distillation, 2 distillation columns are preferably used.

Regarding the step of separating aromatic hydrocarbons as main components from such cracking oil, namely the separation of the faction with a lower one Boiling point as xylene or styrene and the return

10983 771676

Stand with a higher boiling point than xylene or Styrene from the cracking oil, remains the choice and control the operating conditions of the distillation stage to the person skilled in the art left. However, it is preferred that this fraction have some parts of an aromatic hydrocarbon with 8 carbon atoms and that the residue consists of hydrocarbons with at least 9 carbon atoms consists.

If a distillation column is used for this distillation is, the fraction with a lower boiling temperature is recovered from the top of the column, while the fraction desirable aromatic hydrocarbons from the Middle of the column and the residue is recovered from the bottom of the column. Of course it is also possible to have two or to use more distillation columns. The distillation is carried out under atmospheric pressure or reduced pressure. Normally, the distillation takes place at one Temperature of 70 C, under normal atmospheric pressure and with a reflux ratio of two. However, these operating conditions are intended to go beyond the scope of the inventive concept do not restrict.

The desired product fraction thus obtained consists of aromatic hydrocarbons with 8 carbon atoms as main components. However, since benzene and toluene easily are separable from the fraction, it is possible to include a large amount of benzene and toluene in the fraction.

10 9837/1678

sen, even if these quantities are greater than the quantities of Are xylene and styrene. However, it is preferred that the The total amount of benzene and toluene should not exceed 10% by weight. On the other hand, it is not desirable that a large amount of hydrocarbons with at least 9 carbon atoms are contained in this fraction since they are an obstacle to the subsequent extractive distillation represent. The total amount of these hydrocarbons should be less than about 1 wt .- ^.

The separation of xylene and styrene from the fraction is carried out successfully carried out by extractive distillation. The extractive distillation step is carried out in this way that the fraction obtained in the above-mentioned operation is placed in a column in the middle of this column introduces, and also, a solvent defined below into the column near the top thereof Column feeds and then the fraction containing concentrated xylene from the top of the column and concentrated Styrene is recovered from the bottom of the column together with solvent. Be in the extractive distillation one or more distillation columns is used, but is it is preferable to use two distillation columns.

Suitable solvents are, for example, a dialkyl acetamide such as dimethylacetamide, a dialkyl sulfoxide such as methyl sulfoxide, an alkyl carbonate such as ethylene carbonate and propylene carbonate, a lactone such as ίΤ-butyrolactone and

109837/167 8. -io-

Methyl- ^ T-butyrolactone, a lactam, such as £ -caprolactarn, Phenol, an alkylphenol, an alkyl salicylate, Aniline, an alkyl aniline, a phthalic acid alkyl ester Tetraalkylurea, a NjN-dialkylcarbamic acid ester, a glycol monoalkyl ether such as diethylene glycol monoalkyl ether and triethylene glycol monoalkyl ether, and N-methylpyrrolidone.

1 to 50 moles of solvent, preferably 2 to 10 moles Solvents based on 1 mole of styrene in the feed are used as solvents for the extractive distillation used.

In the extractive distillation stage, it is preferred to use a polymerization inhibitor such as hydroquinone to cause thermal polymerization of styrene impede. In addition, the temperature and pressure in the extractive distillation stage should be controlled. The temperature can be set at the bottom (cooker) of the

lation column are below 120 C and is preferably in the range of about 80 to 110 C. The pressure should be according to the structure of the distillation column and the nature of the solvent can be determined. However, the pressure can usually range from about 10 to 200 ram Hg absolute, preferably in the range from about 20 to 100 mm Hg absolute at the top of the column. Essentially anyone can known inhibitors are used, such as, for example, hydroquinone, tert-butylcatechol, pnenothiazine, sulfur etc. The amount of used in the distillation step

109837/1678 - 11 -

Inhibitors can be 10 to 500 ppm, b & added by weight of the charge, or more. The preferred reflux ratio is in the range of 10-20.

It is considered surprising that styrene is derived from cracking oil can be obtained directly according to the present invention can. ·

In the extractive distillation step of the present invention, styrene may be of high purity and high yield are obtained when a solvent is used the present ι A dialkylacetamide, such as dime thylacetamid, a dialkyl sulfoxide such as dimethyl sulfoxide, an alkylene carbonate such as ethylene carbonate and Propylencarbona.t, a Lactone, such as (T-butyrolactone and methyl- O- butyrolactone, a lactam, such as ^ -caprolactam, phenol, an alkylphenol, an alkyl salicylate, aniline, an alkylaniline, an alkyl phthalate, a tetraalkylurea, an alkyl NjNmonoate, such as a dialkylcarbamic acid ester Diethylene glycol monoalkyl ethers or triethylene glycol monoalkyl ethers, such as N-methylpyrrolidotf.

Previously, styrene was obtained by dehydrogenating ethylbenzene of high purity and distilling the resulting products won under high pressure. Ethylbenzene was obtained by reacting ethylene and benzene or separated it removes xylene fractions by desullation. One was that Believes that it would be particularly beneficial to use ethylbenzene

109837/167 8

.- ■ "■■ '. - 1 O _

Obtainable from the xylene fraction, since large amounts of the xylene fraction are easily found in the petroche »! see industry can be obtained. Since the boiling points of p-xylene and m-xylene are close to that of ethylbenzene, but 6s is sometimes required, a distillation column with as much as 350 trays for the separation of ethylbenfcol to use from the xylene fraction. Therefore, such a method possesses both technical and economical Disadvantage.

On the other hand, the method was also examined, which consists in converting the ethylbenzene contained in the xylene fraction into styrene by dehydration and to obtain the styrene obtained in this way by distillation. In this Metjode but are xylenes, particularly o-xylene (boiling point 144.4 ⁰ C) ₁ near the boiling point (l45,2 ° C) of styrene, and so it is practically impossible to separate styrene from the resultant mixture by ordinary distillation. Therefore, the method of separating styrene from a xylene fraction presents an unsolved problem at present in practice. Some improved methods have been proposed for this mode of operation, as follows:

(l.) The method of separating styrene by extraction using an aqueous silver salt solution,

(2.) the method of separating styrene by aaeotropic

10 9837/1678

(3 *) the method of separating styrene by extractive Distillation using dialkylformamide, especially dimethylformamide as a solvent and

(kt) the method of separating styrene by polymerizing styrene in the xylene fraction.

However, these methods still presented problems. The method (l ·) is expensive because of the silver salt <. The method (£,) has a low separation effect. The method (3) is troublesome because styrene and xylene form alcfcrope with dimethylformamide, and so it is practically impossible to obtain styrene and xylene from the solvent by distillation. The method (k.) Is impracticable in practice.

However, styrene can pass through from the xylene fraction extractive distillation using those mentioned above Solvent can be obtained.

In the present invention, the residue thus obtained consists essentially of styrene and solvent. Styrene can easily be separated from the residue by normal distillation under reduced pressure. It is preferred that the pressure be set within the range of about 20 to 100 mm Hg absolute at the top of the column

109837 / ^ 7 8 ■. _xk

To prevent this, it is preferred that the temperature at each tray of the column is kept below 120 ° C. It is also preferred to use an inhibitor in this distillation and in the extractive distillation. Styrene can be recovered as a fraction from the top of the column.

The extractive distillation stage consists of The fraction taken off at the top of the column consists mainly of xylene, but toluene, benzene and others can also be used saturated and unsaturated aliphatic hydrocarbons may be included. The parliamentary group can, as it is, or after washing with water using a catalyst such as Wo, Co, Ni and combinations of these metals, be hydrogenated. The hydrogenation can be carried out under a pressure of 10 to 200 kg / cm absolute and at a temperature from 100 to 400 C. During this hydrogenation it may be advisable to use a mixture with the xylene fraction of the extractive distillation and the lower fraction and / or that obtained in the distillation of the cracked oil Residue to use.

According to the present invention, from the cracking oil aromatic hydrocarbons such as benzene, toluene, xylene and styrene can be successfully obtained. Particularly can according to the present invention xylene with good quality (with a high concentration of p-xylene and a low concentration of ethylbenzene)

- 15 -

109837/1678

and moreover, styrene with higher purity can be used can be obtained directly from cracked oil. Paraxylene is an important one Raw material for terephthalic acid, and styrene is also important as a raw material for plastics, Thus, the present invention should substantially reduce the cost of these products.

The following examples are provided for further explanation the invention.

example 1

Cracked oil of a depen ^ ranized soil product with a Salary of $ 7.5 wt. Styrene was obtained from an industrial plant for cracking naphtha. Lower fractions, the boiling temperatures of which were up to 130 C, and higher fractions above 150 C were fractionated by Distillation of this cracked oil removed.

The remaining C ^ l was extractive distilled, wob0i two distillation columns were used * The first column, which had a tray number of 50, was under 70 mm absolute at 60 ° C using a reflux ratio of 12 and the second column, which had a tray number of 60, below 20 mm Hg absolute at 45 ° C operated using a reflux ratio of 15. The oil was in the middle tray of the first column fed, and dimethylacetamide was added in the same amount as the Ql (with a content of 300 ppm

■ .. 1 0 9Ö3 7/1 6 7 8

tert-butylcatechol) fed from the top of the column. The residue from the bottom of the first column was fed to the middle bottom of the second column, and dimethylacetamide was fed in an amount 0.5 times the amount of the residue at the top of the second column. The top fractions of the second column were returned to the center of the first column and the mixture "of styrene and solvent" was obtained from the bottom of the second column.

This mixture was under reduced pressure at 80.degree fractionated with a reflux ratio of 3, and thus styrene was obtained from the top of the column with a 99 »2 $ purity and in an $ 86 yield on the amount of styrene contained in the cracking oil.

The top fraction of the first extractive distillation column and the lower fraction were mixed with one another. The mixture was washed with water and hydrogenated at 330 ° C. under a kO atmosphere in the presence of Co — Ho catalysts. The xylene contained in the reaction mixture thus obtained was composed of 21 wt -. <F> ethylbenzene, 18 wt .- # p-xylene, 36 wt -. <F> m-xylene and 25 parts by weight jt o-xylene together. Comparatively xylene contained without the separation of styrene 45 wt .- ^ Ä'thylbenzol and 12 wt -.% P-xylene.

- 17 -

109837/167 8.

Example 2

The same procedure as in Example 1 was followed, but using; of 4-methyl-tz-butyrolactone instead of the dimethylacetamide of Example 1 as a solvent.

Styrene was obtained with a purity of 98 ^ and in a 75 $ yield, based on the styrene in the cracking oil, won.

The xylenes contained in the reaction mixture consisted of 25 wt .- $ ethylbenzene, 17 wt .- $ p-xylene, jk wt. -Jft m-xylene and 24 wt .- $ o-xylene together.

Example 3

A cracking oil containing 7% by weight of styrene was obtained by fractional distillation of the by-product of an ethylene producing plant after hydrocarbons containing up to 5 carbon atoms had been removed. The low fractions with boiling temperatures of up absolutely to 85 C under 15Q mm Hg were from the - separated · ■ 'cracked oil by fractional distillation, and "the higher fractions with boiling temperatures of at least 8O ⁰ C under k3 mm Hg were separated by fractional distillation. Fractions of hydrocarbons

■ i '"' - ^; :: · ■ '■ ■ - ■ ■■■■■

\ etopen with 8 carbon atoms as the main part were / obtained. . ^v -. ""^; - .-, - - ^! . V ■ ■■ --'_ f. '■■ ^: ■■■''' - '- "■' ■■■ - ■■ ■. ■ - 18 -

f -. ■■ - ■ ". ■■ ... .--. ■■■ -.-.>,., - ■■■ ..

; ·,] ■■■■■■■. "109837/1878

The fractions were extractive distilled. Two distillation columns were used for the extractive distillation used. The first column, made up of 50 trays composed, was below 50 mm Hg absolute at 55 ° C and operated at a reflux ratio of 15, while 'the second column with 60 plates below 20 mm Hg absolute operated at 45 C and a reflux ratio of 20 became.

The fractions were fed into the middle tray of the first column, and dimethyl sulfoxide (with a content of 500 ppm tert-butylcatechol) was in an amount fed to 2 times the amount of the fractions at the top of the first column. The residue at the bottom of the first column was fed into the middle tray of the second column, and dimethyl sulfoxide was added in an amount of the 0.5 times the amount of the residue is fed to the top of the second column. The top fractions of the second column were returned to the middle tray of the first column.

The residue at the bottom of the second column consisted essentially of styrene and dimethyl sulfoxide. The return

ο was under reduced pressure at 65 C and eggian Refined reflux ratio of 2, and so the rectifying column became styrene with a purity of 98.5% and in an 80 ^ -igen yield, based on the in

d «M cracking oil contained styrene, obtained ·

109837/1678

^ 19 -

18 wt .- ^ ρ-xylene $> ethylbenzene,, - - o-xylene 35 wt .- # m-XyIöl and 25 wt -'ja together from the fraction xylenes obtained consisted of wt...

Example k

The same extractive distillation as in Example 3 · was also carried out here, but instead of Dimethyl sulfoxide as solvent tetramethyl urea used.

Styrene was obtained from the residue of the second column with a purity of 97% and a yield of 70%. ,

The xylenes thus obtained consisted of 27 wt .- ^ Ethylbenzene, 1 ^ 5 wt .- ^ p, xylene, 33.5 wt .- ^ M-xylene and. 23 wt .- ^ έ o-xylene together.

Example 5

The same extractive distillation as in Example 3 was carried out with the exception that instead of Dimethylsulfoxyd.as solvent propylene carbonate was used.

The residue from the second column was converted into styrene 97 $ purity and in a 75 $ yield, be based on the amount of styrene in the cracking oil recovered.

- 2ο -

The top fraction of the first column was in the presence of Co-Mo catalysts under 30 atmospheres pressure Hydrogenated at 300 ° C.

The xylene obtained in this way was composed of 26 wt .- ^ ethylbenzene, 17 wt .- ^ p-xylene oil, 3k wt .- ^ m-xylene and 23 wt .- ^ o-xylene.

Example 6

A cracking oil with a content of 7 wt .- ^ styrene was obtained one by fractional distillation of the by-product of an ethylene producing plant to hydrocarbons with up to 5 carbon atoms to remove. The lower ones Fractions with boiling temperatures of up to 70 ° C. below 150 mm Hg absolute were passed through by the cracking oil fractional distillation separated, and higher fractions with a boiling point of at least 75 ° C below 43 mm Hg absolute were obtained by fractional distillation severed. Hydrocarbon fractions having 8 carbon atoms as a major part were obtained.

These fractions were extractive distilled. Two distillation columns were used for this extractive distillation used. The first column was under 100 mm Hg absolute at 60 C with a reflux ratio of 12 and the second Column below 20 mm Hg absolute at 40 ° C and with a reflux ratio operated by 15. These fractions were fed into the middle tray of the first column, and di-

Hi 9 8 3 7/1 6 7 8

methylacetamide was used in an amount 2 times the amount the fractions fed to the top of the column. The residue at the bottom of the first column was introduced into the middle trays of the second column, and dimethylacetamide was used in an amount of 0.5 times the middle of the The residue fed from the top of the second column. the Top fractions from the second column became the middle tray recycled between the feed and the bottom of the first column.

The residue at the bottom of the second column was composed essentially of styrene and dimethylacetamide. The residue was distilled under reduced pressure at 70 ° C. with a reflux ratio of 3, and so at the top of the column was styrene of 99 > 7% purity and in a $ 99 yield, based on the amount of styrene in the cracking oil. The top fractions of the first column were hydrogenated under 50 atm pressure at 380 C in the presence of Co-Mo catalysts. The xylene fraction obtained in this way was composed of 20% by weight of ethylbenzene, 18% by weight of p-xylene oil, 36% by weight of m-xylene and 26% by weight of o-xylene.

On the other hand, the xylenes in the reaction mixture after hydrogenation without separation of the styrene by extractive distillation contained k8 % by weight of ethylbenzene and 12% by weight of p-xylene,

109837/1870

Example 7

The same procedure was used as in Example 6 except that dimethylacetamide was used in place of as solvent ^ f-butyrolactone was used

Styrene with a purity of> $ 2 and in a yield of $ 85 was obtained. The xylene contained in the reaction mixture was composed of 21 wt .- ^ ethylbenzene, 18 wt .- # p-xylene, 36 wt .- ^ rw-xylene and 25 wt .- # o-xylene.

Examples 8 to 2k

Styrene and xylene were derived from each other and from different compositions made up of styrene and. Xylene passed., separated by extractive distillation using different solvents. With these extractive Distillations each distillation column had a capacity of 2.5 w height and 30 mm inside diameter and was now filled with wire meshes of 3x3.

Each composition was at a loading tray was fed to each column at a height of 1.8 meters, and each solvent was fed to a feed tray at a height of 2.4 meters fed into each column.

Xylene was recovered as a fraction at the top of the column and styrene was recovered as a residue at the bottom of the column. These examples gave the following results: i

109837/1678 -23-

co OO CjO

-4.

ro

example
.lio. composition 30th
30th
20th
10
[10] speed
the "feed
(cm ³ / h) Solvent ■ -. phenol speed
the "feed"
(cm ³ A) V Salary everyone
component
(GeWc- #) ) 30th m-cresol 120 8th o-xylene (50)
Styrene (50) Styrene (50) 30th Salicylic
acid -
methyl-
ester 1.2.0 . '.' ■ ■ '9 · o-xylene (50)
Styrene (50) Styrene (50)
o-xylene (50) 30th aniline 120 10 Styrene
o-xylene
m-xylene
p-xyl oil
Ethyl-
benzene 1 Styrene (50)
o-xylene 30th Phthalic
acid-
monomethyl
ester 120 11 Styrene (40)
o-xylene (30)
m-xylene (30) 30th Tetramethyl
urine st off 120 12th 3Q N, N-diethyl
carbamine
acid ethyl
ester 120 - 13. 30th 120 14th

ro

uo

(Continued)

K) O O cn 00 CD CO

Ui
I. Operating conditions pressure
(mm Hg) temperature
rc) Reflux
relationship fraction
($ Purity) Result Residue
($ Purity) 1
Yo
1 50 55 13th Styrene
© -Xylene Styrene (97) 50 55 13th Styrene
o-xyl oil (2)
(98) Styrene (94) 40 50 13th Styrene
o-xylene
m-xylene
p-xyl oil
ethyl
benzene (5) Styrene (92) 109837 / 50 55 13th Styrene
o-xylene jis)
(19.5)
(10)
(10) Styrene (95) 200 co
-J
co 30th 45 13th Styrene
o-xylene (H)
(96) Styrene (92) 6863 50 55 13th Styrene
o-xylene (6)
(94) Styrene (93) 50 55 13th Styrene
o-xylene
m-xylene ill) Styrene (94) (2.3)
47.5
(49.2) (Continued)

SD OO

example
No » composition Speed
the feed
(cmVb) solvent Diethylene
glycol mono-
ethyl ether speed
the "feed
(Cm ³ Zh) Salary everyone
component
(Gew, - #) 30th Dimethyl
sulfoxide 120 Styrene (50)
o-xylene (50j 30th AthyIen-
carbonate 120
¹ 16 Styrene (50)
o-xylene (SO) 30th Propylene
carbonate 120 17th Styrene (50)
o-xylene (50) 30th ίΤ-butyro-
lapton 120 18th Styrene (50)
o-xylene (50) 30th Caprolaetam; 120 ■ _; . 1 ° '■ ■ Styrene (50)
o-xylene (50) 30th 120 20th Styrene (50
o-xylene / 20
m-xylene (30

(Continued)

NJ OO CD OO CD LO

I.
NJ Operating conditions pressure
(now Hg) temperature
(oc) Reflux
relationship Result fraction
($> Sophistication) (8th)
(92) Residue
($ Purity) I. 50 55 13th Styrene
o-xylene (99) Styrene (94) ru
I. 50 55 13th o-xylene (98) Styrene (96) 109837/167 30th 45 13th o-xylene (98) Styrene (94) OD 30th 45 13th o-xylene (99) Styrene (95) 2006 40 50 13th o-xylene (39)
(60) Styrene (98.5) 863 30th 45 13th Styrene
o-xylene
m-xylene Styrene (94) (Port setting)

co CO CO -J

CD CO

example
No. composition 3 5
10
10
: io; speed
the «feed
(cm ³ A) solvent speed
the _o feed
(CIH ³ A) Salary everyone
component
(Wt .- ^) 30th 120 21st Styrene (50)
o-xylene (50) Styrene (50}
o-xylene (50) ko 4-methyl- <if-
butyrolactone 100 22nd Styrene (5 °)
o-xylene (50) Styrene (50)
o-xylene (50) ko Dimethyl
acetamide 100 23 Styrene
o-xylene
m-xylene
ρ-xyI oil
Ethyl-
benzene 1 Styrene (50)
o-xylene (50) 30th Dirnethyl
acetamide 120 2k 30th Diethyl
acetamide ¹ - cf 1 ^ O nothing - cf 2 nothing

OO I

NJ O CD CD OO cn co

Operating conditions pressure
(mm Hg) temperature
( ⁰ C) Reflux
relationship Result fraction
d » purity) (98) Residue
{$> Purity) I. ko 50 13th o-xylene (99.5) Styrene (96) OO
I. 50 55 13th o-xylene (0.8)
(48.2)
17th
(17)
(17) Styrene (99) λ
O
co 50 55 13th Styrene
o-xylene
m-xylene
P-XyI oil
ethyl
benzene (97) Styrene (99.5) co
co
-J
CD
-J
OO 50 55 12th o-xylene (80) Styrene (95) 2006863 50 55 13th o-xylene (80) Styrene (83) 50 55 13th o-xylene Styrene (83)

In this table each gives a percentage for the hydrocarbons substance purity the concentrate ratio, excluded the solvent. To be sure, in these examples solvent mainly from the soil of the columns together with styrene obtained as a residue.

109837/1670

Claims (7)

Claims 1.) Process for the separation of aromatic hydrocarbons with mainly 8 carbon atoms, especially for Separation of styrene from a mixture containing xylene and styrene, preferably for the recovery of Styrene and xylene from cracking oil, characterized in that that the hydrocarbon mixture or pretreated Subjected cracking oil together with a solvent to an extractive distillation and xylene as a distillate and styrene wins as residue. 2.) The method according to claim 1, characterized in that the solvent used is a dialkyl acetamide, such as dimethylacetamide, a dialkyl sulfoxide, such as dimethyl sulfoxide, an alkylene carbonate, such as ethylene carbonate or propylene carbonate, a lactone, such as 4 "-butyrolactone or methyl-0 (-utyrolactone, a lactam such as j ^ -caprolactam, phenol Alkylphenol, an alkyl salicylate, aniline Alkyl aniline, an alkyl phthalate, a tetraalkyl urea, an N, N-dialkylcarbamic acid ester, a glycol monoalkyl ether, such as diethylene glycol monoalkyl ether or triethylene glycol monoalkyl ether, or N-methylpyrrolidone is used, 3.) Method according to claim 1 and 2, characterized in that that one as a pretreated Kreköl in the manufacture of ethylene by cracking naphtha as a by-product 109837/1678 -31- preserved cracked oil is used from the hydrocarbons with less than 5 carbon atoms, preferably with less than 7 carbon atoms, and hydrocarbons with at least 9 carbon atoms removed. 4.) Method according to claim 1 to 3, characterized in that that the extractive distillation at a temperature below 120 C under a pressure of less than 200 mm Hg absolute and with a reflux ratio of 10 to 30 performs. 5.) Method according to claim 1 to 4, characterized in that that the extractive distillation in the presence of a Pdymerization inhibitor performs. 6.) Method according to claim 1 to 5, characterized in that that the distillate of the extractive distillation in the presence of a catalyst under a pressure of about Hydrogenated 10 to 200 kg / cm absolute and at a temperature of about 100 to 400 ° C. 7.) The method according to claim 6, characterized in that a catalyst with at least one of the metals molybdenum, cobalt and nickel is used. 109 837/1678