DE2263601A1 - PROCESS FOR SEPARATING CYCLOPENTADIENE, CYCLOPENTENE AND / OR PENTADIEN-1,3 - Google Patents

Description

Process for separating cyclopentadiene, cyclopentene and / or 1,3-pentadiene

The invention relates to a method for separating Cyclopentadiene and cyclopentene and / or 1,3-pentadiene, in which a cyclopentadiene containing Cyclopenten- and / or PencatUen-1, 3-carbon hydrogen fraction distilled in the presence of n-pentane becomes, υτη the cyclopentadiene in the form of the azeotrope with n-pentane to separate and at the same time cyclopentadiene and / or Peirüaciien-1,3 with a lower content of cyclopentadiene.

Cyclopentene is referred to (which is referred to as "CPE") or 1,3-pentadiene (also called piperylene including £ ugly the ^c ISS-and trans-isomers, which is referred to as "PPL" refers v.'ird) is a valuable Substance as starting material for the production of chewing-techuk-like substances, resinous substances and organic compounds.

When polymers using these compounds as a starting material with the help of a certain catalyst, such as an organometallic compound, the desired Polymerization reaction due to the presence of cyclopentadiene (hereinafter referred to as "CPD") or higher acetylene The starting material is strongly inhibited or disturbed and it is there It is necessary to remove these connections as completely as possible beforehand. Each of these connections must not be in a Meη fr ο of more ^ If 1 # are present and a fetched one is desirable

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from no more than 1000 parts to rone million parts (PPM).

On the other hand, cyclopontadiene is also a suitable compound as a starting material for dicyclopentadiene (hereinafter al? · "DGPD" designated), cyclopentene (CPE) or the like. When cyclopentadiene is thermally dimerized with the formation of dicyclopentadiene, high concentrations of other diolefins deteriorate Cyclopentadiene, such as piperylene and isoprene, the purity of the dicyclopentadiene obtained, especially these diolefins with codimers Form cyclopentadiene. If, in addition, cyclopentadiene is the equivalent If a certain catalyst is hydrogenated to cyclopentene, the presence of high proportions of diolefins other than cyclopentadiene makes the effort required for the hydrogenation considerable and there are also higher levels of by-products are formed, making it difficult to obtain the resulting cyclopentene (CPE) to clean.

Under these circumstances it is very desirable to _{separate cyclopentadiene (CPD), which contains hardly any other diolefins, from a C 1} raw material fraction and at the same time to obtain cyclopentene (CPE) and / or piperylene (PPL) with a lower content of cyclopentadiene. Particularly in view of the fact that large amounts of the C ^ fraction (a mixture of C ^ hydrocarbons) are now obtained as a by-product of the production of ethylene by the thermal cracking of hydrocarbons, the separation of usable CPE, PPL or CPD takes place the fraction Fowie the separation of isopropene therefrom of great value. The C ^ fraction, however, eats a mixture of a very large number of different hydrocarbons and it is therefore extremely difficult to isolate the specific desired substance from such a mixture, for example only the desired substance free from the aforementioned polymerisation retarders CPD (and higher acetylenes). It is known that a fraction containing CPD is obtained from CPE and / or PPL as a secondary product in the separation of isoprene. For example, US Pat. No. 3,510,405 describes that said CPE and PPL fractions are obtained in considerable concentrations. The specific removal of the harmful substance CPD from such a fraction

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has not yet been achieved!;.

As shown in Table 1, the boiling point of CPD is close at the boiling points of PPL (especially the trans isomer) and CPE, making it difficult to separate the compound by ordinary distillation.

TABLE 1

Boiling point ο d Comp he ne i n-th of the n ^ frac tion

n-pentane 36.1 ⁰ C Propyl acetylene 40.2 Cyclopentadiene 41.0 trans-piperylene 42.0 ei8-piperylene 44.1 Cyelopents 44.2 eifs-Propenyla eetylen 44.6 Cyelopentane 49.3 Dieyclor, entadien 170.0

Invention? I? GeniH <? it has now been found that by distillation a CPW-containing fraction of CPE and / or PPL in the presence of n-pentane, the CPD in the form of an azeotropic mixture can be easily separated from the fraction with n-peritane.

It has also been found that, in addition to this azeotropic distillation, an extraction process or a performance of the extractive distillation, which is carried out in combination with it, enables PPL or PPE free of polymerization-inhibiting substances, such as CPD (and higher), in an economical manner and without difficulty to obtain acetylenes) from a CPE PPL fraction.

The method according to the invention can be used for treatment any GPIv- i-ij-j / orcr PPI— Fr a ^ t j on apply, the Cyclopciii. £ ■ "■■;. <: ·

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(CPD) contains. The C ^ fractions, like the a] .3 By-product in the production of ethylene by thermal cracking of hydrocarbons, the C ^ fraction obtained by the dehydrogenation of C, paraffin and / or C, --Olefin is obtained, or which are reduced by partial hydrogenation of a CPD fraction obtained CPE Group generally consist of numerous Kohlenwassastoffen with boiling points in the range of 20 to 50 ⁰ C. in addition to these components, they also contain minor amounts of Cg and C.- - fractions, if they are obtained by technical processes. A fraction which contains CPE and / or PPL in high concentration is preferred for carrying out the process according to the invention. Such a fraction can be obtained by adding the C ^ fraction, such as one of the fractions enumerated above, to one of the treatments: distillation, extraction, extractive distillation, selective hydrogenation and heating to dimerize CPD or the other treatments in the is subjected to the desired order or a combination of these treatments. In order to achieve better effects, these treatments are preferably carried out in combination with a process for the recovery of isoprene. In general, it is desirable to fractionate the product, which consists predominantly of the fraction in the boiling range between 40 and 50 ° C., by distillation. This distillation removes acyclic pentanes, acyclic pentenes, isoprene and the like from the C ^ fraction and thus a fraction is obtained which contains trans-PPL, cis-PPL, CPE, CPD and in some cases higher acetyls, such as propenyl acetylene, Contains propyl acetylene and the like. If CPD is present in large proportions in the starting material and if it is not necessary to obtain high-purity dicyclopentadiene (DCPD), some or most of the DCPD can be removed beforehand by dimerization with heating. In addition to the above-mentioned fractions, fractions of CPE and / or PPL which are suitable according to the invention and which contain CPD include, for example, a starting material which was obtained by first heating the C 1 fraction to remove most of the CPD contained therein to dimerize, after which it was distilled to remove the fraction with boiling points of more than ^ Ί π 50 C and in which the distillate,

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subjected to extractive distillation v-rrde. To obtain U from isoprene, PPL, CPE, residual CPD and the like, after which the isoprene was removed by distillation; a starting material which was obtained by initially subjecting the C ₁ fraction obtained by the dehydrogenation of pentanes and / or pentenes to extraction or extractive distillation, an isoprene, PPL, CPE and CPD containing Fraction was obtained and thereafter the isoprene was removed from the fraction by distillation; or a starting material by distillation of the C, - fraction to remove distillates having boiling points below 40 ⁰ C, Mmerisieren the major part of CPD by heating and subsequent distillation of the fraction for the removal of the bottom liquid with boiling points greater than 50 ⁰ C, was obtained.

The process according to the invention is also preferably carried out using the CPE-CPD fraction, which is obtained by partial Hydrogenation of CPD was obtained.

If it is desired to obtain DCPD in high purity by the process according to the invention, the azeotropic Distillation can be carried out without first the dimerization reaction is carried out by CPD, CPD being separated from the other diolefins as a CPD-n-pentane azeotrope, and then the dimerization can be carried out.

These methods of treating the C ^ fraction can be made more economical Way can be combined with different process steps for separating isoprene.

Thus, the method made accessible by the invention comprises the distillation of a fraction of CPE and / or PPL, the CPD. contains, in the presence of n-pentane, which is added in an amount corresponding to the amount required for the azeotropic composition with the CPD to be removed, or im Excess over this amount, whereby the n-pentane-CPD azeotrope with lower proportions of diolefins other than CPD is obtained and at the same time the CPE and / or PPL fraction with a lower one Content of CPD is obtained. The term used here

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"CPD to be removed" means there; - CI ¹ D, which "is distilled out as raffinate in the azeotropic distillation.

The invention is based on the discovery that CPD forms an azeotrope with n-pentane with a minimum boiling point. Although the composition of the azeotrope varies depending on the pressure, the temperature and the presence of a third compound, it is in the two-component system of n-pentane and CPD at normal pressure about 27 mol percent CPD and 73 mol percent n-pentane and has an azeotropic temperature of about 35 C. The boiling point of the CPD-n-pentane azeotrope differs from the boiling points of CPD and / or PPL by about 7 to 9 ^° C. Compared to a boiling point ^{difference of about 1 to 3 °} C. between CPD and CPE or PPL without the presence of n-pentane is facilitated by such a difference in removing CPD and it is possible to obtain CPE and / or PPL which contains practically no CPD. The amount of the n-pentane to be added is 2.7 times or more, preferably 2.7 to 1,000 times, in terms of molar ratio, the amount of the CPD to be removed, and even if it is added in excess, the Gently distill off excess n-pentane, like the azeotrope.

The n-pentane to be used for the purposes of the invention does not have to be necessarily have high purity. For example, a hydrocarbon mixture containing n-pentane is used, preferably a pentane fraction (isopentane-n-pentane mixture), which is a by-product of natural gas cleaning or petroleum refining was obtained; a fraction obtained as a raffinate in the recovery of isoprene by extraction or extractive distillation or fractions are used in which n-pentane was further enriched, for example by distillation. the Addition of n-pentane is of course not necessary if the required amount of n-pentane or a larger proportion is already present in the process stage in which the CPE and / or PPL-CPD fraction used as starting material is obtained.

These n-pentane Froktion or n-pentane containing FIM + ion K "nn before distillation of CPE and / or PPL CPD-Fri ^ ction zußonetz ⁴ .. be. In another embodiment, these materials may

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in the middle and / or lower 3il eiru => r distillation column to be introduced. In each EaIl, the starting material is distilled an azeotrope consisting of CPD and n-pentane, as well as other low-boiling constituents at the top of the column, while the CPE and / or PPL fraction with a lower CPD content are obtained from the bottom of the column. This azeotropic Distillation can preferably be carried out at normal pressure.

If CPD / or PPL-CPD fraction to be removed in a substantially satisfactory degree from the CPE and, it is preferred to perform the distillation by introduction of n-pentane in AEEN lower part of the azeotropic distillation column, whereby the n-pentane Concentration is kept above a certain concentration value because the azeotropic composition fluctuates due to the presence of a third component in some hatred. The concentration varies depending on the amount of CPD and the type and proportion of the third component.

If in this azeotropic distillation the residence time in the Distillation column is long when the temperature in the column is high or when the starting material has a high concentration of CPD, part of the CPD is diraerized to DCPD under the action of heat in the course of the azeotropic distillation. In this case the DCPD goes as an impurity in the fraction in the bottom of the column, i.e. in the CPE- and / or PPL-Fr- ^ k +. ion over. If it is desired or if it is necessary, -He swamp « To free fraction from the DCPD, the fraction can be vacuum distilled or subjected to steam distillation using another column, whereby the DCPD very easily can be removed. Another method of removing DCPD is to pass the CPE and / or PPL fraction through an im To distill off the lower part of the branch line and to withdraw the DCPD from the bottom of this azeotropic distillation column.

It is clear that the CPE and / or PPL fraction obtained go that the is free of CPU, if necessary the necessary to achieve the ^ e--

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desired purity can be further / purified, in-denj in subjected to a next stage of distillation, extraction, extractive distillation, hydrogenation or the like. if the starting material is a mixture of CPE and PPL, it can also be separated into its individual components by numerous methods will. As will be described below, extractive distillation or extraction are most preferred.

The ara head of the column contains CPD-n-pentane azeotrope obtained, although this also depends on the process conditions, almost no diolefins which tend to encode with GPD. The heating of the azeotrope therefore leads to highly pure DCPD. In a preferred embodiment of the invention, the azeotrope is formed of a n-pentane-DCPD mixture, which is then heated to the destination is subjected to isolate the DCPD while the n-pentane preparation is returned from the top of the distillation column to the ^ zeotropic distillation column. According to a different performance the mixture of n-pentane and DCPD can be returned directly to the azeotropic distillation column without DCPD to isolate, and the DCPD can be shared from the Surapf of this column withdrawn with the CPE and / or PPL fraction and then separated off in a separate column from the CPE and / or PPL fraction v / earth, v / ob when high purity DCPD is obtained. While the method in which CPD also contains other diolefins is dimerized by heating, it is difficult to produce DCPD in a purity of more than 95 percent, enables one Method in which the CPD-n-pentane azeotrope is heated as such, that DCPD in high yield and in a purity of more than 95 percent is obtained.

If CPE is also produced by hydrogenating CPD, the azeotrope of CPD and n-pentane can be hydrogenated directly according to the invention to convert the CPD to CPE, although generally accepted methods for this purpose are to use DCPD thermally cracking to convert it to CPD and then hydrogenating the CPD to CPE.

The invention provides an advantageous method for ^ 'nel i, if desired, a CPD fraction with a low

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/ ooer through

Proportion of diolefins other than GPD is obtained and /

if desired, a GPE and / or PPij action ^ it one

low CPD content is achieved.

The following description refers to the separation of CPE and PPL (and higher acetylenes). This separation is carried out by extraction or extractive distillation with the aid of a polar solvent. AIp polar solvents can be dimethylformamide, disthylformamide, dimethylscetamide and other N-alkyl-substituted fatty acid amides, N-methylpyrrolidone, furfural, acetonitrile, acetone and the like and their aqueous Solutions or mixtures known for the separation of conjugated diolefins can be used. A particularly preferred polar solvent is one of the aforementioned N-alkyl-substituted fatty acid amides, which is represented by the following general formula RGONR ₁ R ₂ , in which each of the radicals R and R .. has a hydrogen atom or a lower alkyl group 1 to "5 carbon atoms and R _{2 stands} for a lower alkyl group with 1 to 3 carbon atoms. Due to their extraction capacity and their boiling point and the like, the above-mentioned amides are preferred Inhibit polymerization of conjugated diolefin or higher acetylene, or compounds that act as chain transfer agents to prevent the formation of a high polymer. For example, furfural, nitrobenzene, o-nitrophenol, m-dinitrobenzene, sodium nitrite, t-butyl catechol and the like are used for ?? ieh or in combination in amounts of 0.01 to 10 wt fo added. The addition of these compounds enables δ'ι, ρ extractive distillation or extraction to be carried out over a long period of time.

The following table shows the relative volatility of each of the components in typical solvents.

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• n-pentane Relative TABEL Z Dimethyl
formamide Furfural Solvents Aceto
nitrile 2-methylbutene-2 Dimethyl
acetamide Volatility in different 0.20 0.20 N-methy1-
pyrrolidone 0.31 Isoprene
CPE
trans-PPL 0.23 Diethyl
formamide 0.59 0.55 0.20 0.70 cis-PPL 0.58 0.30 0.91
1.00
1.56 0.80
1.00
1.17 0.54 0.91
1.00
1.69 CPD 1.05
1.00
1.50 0.63 1.76 1.33 1.13
1.00
1.57 1.89 approx
CD
CD
OO
ro
OO Propyla cetylene 1.69 1.00
1.00
1.39 2.27 1.89 1.80 1.77 2.03 1.57 3.48 1.71 2.28 2.96 3.85 1.70 3.54 2.65

Note: infinite dilution, O ⁰ C (except "with acetonitrile- 23 C)

As can be seen from the table ίετ, the solubility in these solvents the order: higher aceijrien, CPD, PPL and CPE.

The extraction or extractive distillation is carried out according to the method known in this field and is described in made so that CPE is obtained as a raffinate and PPL as an extract. If there is higher acetylene in the feed, the higher acetylene comes into the PPL fraction. The following description deals primarily with the extractive Distillation. However, the extraction process is carried out in the same way. In the method according to the invention when the azeotropic distillation is performed first, in the extraction or extractive distillation of CPD Receive free CPE as raffinate The PPL is shared with the solvent obtained from the bottom of the column. They are then transferred to a "absorption column" and heated on the boiling point of the solvent in a PPL fraction and a solvent separately. The regenerated solvent is returned. It is preferred to use part of the PPL fraction back into the extract / ion column, preferably returned to the bottom or bottom of the column in order to lower the bottom or bottom temperature and to balance the material to care. This process step is carried out according to the known "sump reflux" method.

If there is higher acetylene in the feed, the higher acetylene will go to the PPL fraction. If desired, To remove the higher acetylene, the PPL fraction becomes in one

or k

tion ^ T or A second stage of an extractive / extractive distillation column

fed. The column is operated under such conditions that the PPL is obtained as the raffinate and the higher acetylene is obtained as an extract, so that a PPL is obtained which is free from higher acetylene. The extraction or the extractive distillation in the second stage to remove higher acetylene can also be carried out before the first stage. However, such a process can not lead to any advantage because dip BEPC ^ ickur ~ - "ev; I öhnl f only ^oirion. Ehr rerin ^ s share of higher Acetvlen contains Besides Dora Vann the same purpose be achieved if other known methods used. will,

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like the selective hydrogenation of the higher acetylene. *: In this way CPE and PPL are obtained which are practically free from CPD and higher acetylene.

As described above, the CPD is in the loading removed by first the azeotropic distillation is made with n-pentane and then CPE, PPL and higher acetylene are made by extraction or extractive distillation separated in two stages. The following describes the case in which after the separation of CPE and PPL (and higher Acetylene) by extraction or extractive distillation, CPD from either or both of these fractions by azeotropic Distillation using n-pentane is removed. ·

When the starting material CPE-PPL fraction containing CPD is first subjected to the above-mentioned extraction or extractive distillation with a polar solvent, a CPE fraction is obtained as a raffinate and a PPL fraction (and higher acetylene) is obtained as an extract. In this case the CPD present in the feed usually mixes with the TPL fraction and not with the CPE fraction. However, it can sometimes happen that a small amount of CPD, depending on the solvent and process conditions, mixes with the CPE fraction. Even if this is possibly due to incomplete separation, the reason for this can also be the following fact: The CPD contained in the feed is converted into DCPD by dimerization during the extraction or extractive distillation by dimerization and this is enriched in the solvent. Then, when the temperature in the desorption column and the like increases, DCPD is decomposed during the recycling of the regeneration solvent to CPD, which is then flushed into the raffinate at the top of the extraction or extractive distillation column (see US Pat. No. 3,510,405). According to the invention, if desired, the small amount of sn CPD, which is present in CPE, by performing an azeotropic distillation with the addition of n-pentane, as described above, or either by V / n crude with a lienophilic compound such as maleic anhydride and the like, or by dimerization

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Ground heat away. If higher acetylene in the PPL fraction is present, it can be removed in the same manner as in the cases where azeotropic distillation is in the first place is carried out. In this case, however, part of the CPD can be removed along with the higher acetylene. That still in CPD remaining in the PPL fraction can also be removed in the same manner as in cases where the azeotropic Distillation is done first using n-pentane.

In this way, the C ^ - used as the starting material Fraction divided by extraction or extractive distillation into a CPE fraction and a PPL fraction, which are practical contain no higher acetylene. Then the CPD contained in one or both of the fractions is purified by azeotropic distillation removed with n-pentane, whereby e? is possible the CPE and PPL essentially free of CPD and higher acetylene.

The invention is from the following description in context with the accompanying drawings, which illustrate the essence of the invention, more clearly visible. The procedure can however, any modifications and additions can be made, as long as the essential parts of the invention are retained. For example, a common distillation method and a process for CPD dimerization can be attached, and the already the modifications enumerated to remove higher acetylene can be employed without departing from the essence of the invention is deviated.

In Figure 1, the embodiment is shown in which first the azeotropic distillation is carried out with n-pentane to remove CPD and then the extractive distillation is carried out in the first stage to separate a CPE fraction and a PPL fraction, followed by the extractive distillation the second stage is carried out in order to remove the higher acetylene contained in the PPL fraction. In this way, practically ^dip} <^ in CPD un ^ k "iri höheror acetylene are obtained in the starting material CPE and PPL in high purity, contain.

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According to Figure 2, the Ausgangsme-> r ° ^is: .al drrch DIE extractive distillation of the first stage first divided into a CPE fraction and a PPL fraction, after which the higher acetylene contained in the PPL-fraction is separated and in the distillation exträctiven the second stage is removed. The CPD contained in the CPE and PPL fraction is then removed by subjecting these fractions to azeotropic deptulation with n-pentane in order to obtain CPE or PPL in high purity from the starting material, which essentially contain no CPD and higher acetylene .

According to Figure 1, the cation used as the starting material fed through a line 1 and n-pentane or a n-pentane-containing hydrocarbon mixture is through a Line 2 is introduced into the middle part of a distillation column 3. A heating device arranged in the lower part of the column (Reboiler) 4 is heated by a heat source such as steam to perform azeotropic distillation. The n-pentane can either be there? C ^ fraction in the line fed beforehand or introduced into the column 3 through a separate line at a suitable point, as in FIG the figure is shown. A CPD-n-pentane-Az.eotrop is distilled off through a line 5 arranged at the top of the column and is condensed by a condenser 6. A portion of the condensed material is flowed as tail flow through line 7 into the Recirculated top of the column, while the remainder is withdrawn from the system through a line 8. A faction that contains practically no CPD, is through a line 9 from the Taken from the bottom of the column and introduced into the middle part of an extractive distillation column 10 of the first stage. A solvent is introduced through line 12 into the upper part of the column 10 and allowed to pour down and a heat source such as steam is fed to a heating device (reboiler) 11 in order to carry out the extractive distillation. A less soluble CPE fraction is distilled off from line provided at the top of the column and with Condensed with the aid of a capacitor 14. Part of the condensate is then returned to the column through line 15,

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while the remainder of the condensate is recovered through line 16 as high purity CPE. The PPL fraction (which contains higher acetylene), which is dissolved in the solvent, is withdrawn through a line 17 provided in the bottom of the column and is then introduced into the upper part of a stripping column ^ in which the stripping of the dissolved material and the The solvent is regenerated by heating with a heating device 19. A PPL fraction containing higher acetylene is allowed to distill off from a ^{line 20 provided at the top of the column 31} and is condensed with the aid of a condenser. A portion of the condensate is returned as reflux through a line 22 to the column. The remaining portion of the condensate is then fed through a line 24 to the middle part of the extractive distillation column 28 of the second stage. In this case it is desirable to lead part of the remaining condensate back to the distillation column 10, preferably in the bottom thereof, through a line 25, in order to reduce the bottom temperature and to ensure equalization of the material. The solvent, which no longer contains any dissolved material, is drawn off through line 26 at the bottom of the column 18 and cooled in a cooler 27, then introduced into the upper part of the extractive distillation column 10 through line 12

In the extractive distillation column 28, the solvent is allowed to flow down through a line 34 from the upper part of the column and ds. Heating takes place with the aid of a heating device 29. This extractive distillation is carried out in such a way that sppL is distilled to the top of the column, while higher acetylene and a very small part of the PPL are withdrawn from the bottom of the column together with the solvent. The PPL fraction, which has been distilled off through a line 30 at the top of the column, is condensed in a condenser. Part of the condensate is returned as reflux to the column through line 32, while the remainder is obtained from line 33 as a PPL fraction which contains practically no CPD and no higher acetylene. The solvent in which higher acetylene UNU a very small proportion of PPL are dissolved is passed through line 35 from the bottom of

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The column is withdrawn and introduced into the upper second desorption column 36. In this, the solvent is boiled by heating the column with a heating device 41 in order to strip off the dissolved material. Higher acetylene and a very small proportion of PPL are distilled off through line 37 at the top of the column and condensed in a condenser 38. Part of the condensate is returned to the column as reflux through line 39, while the remainder is withdrawn from the system through line 44. In this case, it is also desirable to recycle part of the remainder of the condensate into the column 28, preferably in its bottom, in order to lower the bottom after opening of the column and to ensure the material balance. The regenerated solvent is drawn off from the bottom of the column 36 through line 42 and cooled in a cooler 43. The solvent is then returned to the top of the extractive distillation column 28. Since the solvent is gradually contaminated with polymers of diolefin and the like, it is necessary to withdraw some of the solvent at an appropriate point (not shown) and replace it with fresh solvent.

In those cases where there is no higher acetylene in the feed is present or if it is permissible that this higher acetylene comes into the PPL fraction or if, for example, later instead the extractive distillation a selective hydrogenation of these higher acetylenes is carried out, the extractive Second stage distillation can be omitted. In this case, the PPL fraction can be removed through a line 23, which is represented by a dashed line.

This way, CPE and PPL, which are practically no CPD and contain no higher acetylene, can be obtained without difficulty and nevertheless economically from a C ^ fraction, which Contains components with very close boiling points.

Figure 2 is a C ^ fraction as the starting material a line 51 learns the middle part of an extractive distillation column 52 fed to the first stage. A regenerated

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Solvent from desorption ^ oil onre ' ^! is allowed to flow down through line 58 from the upper part of the column. The extractive distillation is carried out by heating the lower part of the column with the aid of a heating device 53 provided at the bottom and this distillation is carried out in such a way that the less soluble CPE is separated off and obtained at the top of the column, while the more soluble PPL is withdrawn from the sump together with the solvent. The CPE fraction is distilled off through line 54 at the top of the column and condensed in a condenser 55. A portion of the condensate is returned to column 52 as reflux through line 56. The remaining part is withdrawn from line 57 as the CPE fraction which contains practically no PPL and no higher acetylene. In some cases, depending on the CPD concentration in the starting material (especially in the case of a high concentration) or on the operating conditions of the desorption column 61 (especially in the case of a high temperature) or depending on the kind of the solvent, however, CPD mixes to the CPE Group. If it is desired to remove this CPD, the CPE fraction is transferred, for example, to a distillation column 95 in which the CPD is removed by azeotropic distillation in the presence of n-pentane. In this way, CPE can be obtained which does not contain CPD and a higher acetylene content.

The solvent which contains PPL, CPD and higher acetylene (PPL fraction) is drawn off through line 59 ^ m the bottom of the column and is then introduced into the upper part of a desaption column 61. In this column the desorption of the dissolved! Material carried out by heating the column with a heater or cooker 62. This regenerates the solvent. The PPL fraction is distilled off from line 63 at the top of the column and condensed using a condenser 64. A portion of the condensate is then returned to the column as reflux through line 65, while the remainder is introduced into the middle part of the extractive distillation column 69 of the second stage through line 66. It is desirable, eir ^ r. Part of the rectal portion of the condensate: to lead back through line 60 into the bottom of column 52,

- 18 3098 2 8/1144 ^BAD ORIGINAL

the bottoms temperature of the column door z \, lower and balancing material to bring about the. The regenerated solvent is drawn off from the bottom of the column 61 through line 67 and cooled in a cooler 68. It is then returned to the top of column 52 through line 58.

In the extractive distillation column 69 of the second stage ', the regenerated solvent is allowed to flow down through a line 77 provided at the top of the column. The heating is carried out with the aid of a digester or heating device 70, whereby the extractive distillation is carried out in such a way that PPL in this case forms a less soluble fraction, while the higher acetylene is a more soluble fraction. The PPL fraction which is practically free of higher acetylene (but which contains CPD) is obtained through a line at the top of the column and condensed in a condenser 72. A portion of the condensate is returned to the column through line 73 while the remainder of the condensate is introduced into the middle portion of an azeotropic distillation column 87 to remove CPD. The higher acetylene and a small amount of PPL, which is dissolved in the solvent, are withdrawn from the bottom through line 76 and introduced into the upper part of the second desorption column 78. The column is heated with the aid of a digester or heater 79 in order to regenerate the solvent by removing or desorbing the dissolved material. The dissolved material is distilled off through line 80 at the top of the column and then condensed in a condenser 81. Part of the condensate is returned to the column as reflux through line 82, while the remainder is discharged from the system through line 83. In this case, too, it is desirable to return some of the remainder of the condensate through pipeline 75 'to the bottom of column 69 in order to reduce the temperature of the column bottom and to ensure equalization of the material. The regenerated solvent is drawn off from the bottom of column 78 through line 84, cooled in a cooler 85 and then returned through Le- ^: ur.g 77 in the column (->") .

BATHROOM ORIGINAL - 19 -

309828/1 1 46

The PPL fraction, which contains practically no ηοϊιεΓοε Acf-tyl en and which is withdrawn from line 74 is fed to the azeotropic distillation column 87. Although n-pentane or a Carbon-hydrogen mixture of the PPL fraction containing n-pentane can be added before the distillation, they can also fed through a separate line 86 to a suitable point of the column 87 in the manner shown in the drawing v / earth. The interior of the column 87 is with the help of a Heating device 88 heated. This causes a CPD-n-pentane azeotrope and a more volatile component through line 89 distilled off at the top of the column and condensed in a condenser 90. Part of the condensate is drained through a pipe returned to the column. The rest is through line 92 withdrawn from the system. On the other hand, PPL is obtained from the bottom of the column through line 93, which is practically no CPD and does not contain higher acetylene.

The CPE fraction, which is obtained as distillate from the top of the column, is fed in the same volume through line 57 to the middle T- ³ JJ of an azeotropic distillation column 95, while n-pentane or a hydrocarbon mixture containing n-pentane is fed through line 94 of the column 95 is fed. The interior of the column 95 is then heated with the aid of a digester or a heating device 96, the CPD contained in the CPE being distilled off from the top of the column through line 97 as an aseotropic mixture with n-pentane (if a more volatile component is present, this is distilled also with from). The azeotrope is condensed in condenser 98. Part of the condensate is returned to the column through line 99, while the remainder is withdrawn from the system through line 100. In this case, CPE is obtained from the bottom of the column through line 101, which contains practically no CPD.

Furthermore, in cases where the starting material is no contains higher acetylene, or if higher acetylene is present, is permissible if this is mixed with the PPL fraction, or if it can later be converted by selective hydrogenation can, the extractive distillation of the second stage can be omitted. The PPL fraction is then indicated by a dashed line

- 20 -

309828/1 1 44

BATH ORIGINAL

Lines indicated line 102 of the 2z.eotror.en desi ill ation column 87 supplied.

In this way, CPE and PPL containing practically no CPD and higher acetylene become without difficulty and economical Obtained from a C ^ fraction which contains components with very close boiling points.

According to another embodiment not shown in the drawings the extractive distillation of the second stage can be omitted by adding a higher acetylene concentrate to the Vapor phase as a branch stream from the lower part of the desorption column the first stage is withdrawn.

The invention will now be described in more detail by way of the following examples. In these examples the ^ values mean Mole percent unless otherwise stated.

example 1

obtained by thermal Cräcken of naphtha C ^ fraction was freed from fractions having boiling points below about 40 ⁰ C and about 50 C by a conventional distillation, a fraction was obtained with a boiling range of about 40 to 50 C, as the starting material was used for this example. This fraction consists of 19.9 ^ CPD, 41.3% trans-PPL 19.8 io cis PPL 14.9% CPE and 4.1 $ of other compounds. To this fraction was added n-pentane, the feed composition shown in Table 3 being achieved. Thereafter, about 19 ml of the fraction were introduced into the bottom of a distillation column for partial distillation, which had a diameter of 0.6 cm and a height of 50 cm and was provided with a rotating belt. This column had about 40 theoretical plates. After the distillation was carried out under total reflux for ^R for 45 minutes, boiling distillates were initially taken off at a reflux ratio of 120 and the ^ nschliesFcnden distillates were continuously at Einern he ^ · ^1: ^^ Rüc-: flu -ve: ^ ' ^:: '' vm ltnin ISO removed, v, oV: l, the composition of Kopfder-tillater, and the bottom residue

~ 21 - 309828 / 1U4 ^BAD ORIGINAL

was determined at the times, which ζυ 10, 2C, 30 and 40. i> of the added amount of the starting material were aodestilliert. The results are shown in Table ^. In order to numerically show the concentration of n-pentane with a boiling point of 36 ^° C. and CPP with a boiling point of 41 ^° C., the ratio of CPD / (CPD + n-pentane) at the top of the column to CPD / (CPD + n-pentane) calculated in the bottom of the column and also given in the table.

- 22

309828/1 144

CD (O CD N> OD

Together
setting of the
Starting
materials Together
setting at
Distillation
beginning swamp TABLE 3 Together
setting on
Point of
Destilla
tion of $ 20 swamp Together
setting on
Point of
distillation
from 30% Together
setting on
Point of
distillation
from $ 40 1, swamp I. head Together
setting on
Point of
Destilla
tion of $ 10 head Head swamp head ro part of
Destilla 37.0 Head swamp 37.0 41.5 ro tion column ____ 36.0 6.42 36.0 3-37 36.0 37.5 36.5 0.66 temperature
ro 7.31 16.63 61.40 36.0 37.0 08/10 52.80 6 56 1.33 3.02 20.80 CPD 63.30 76.30 16.40 13.31 4.88 83.60 21.50 85.50 43-10 87.00 36.60 n-pentane 15.18 1.86 8.06 81.10 58.70 4.25 11.20 5.56 28.00 7.50 21.90 trans-PPL 7.28 0.24 5.92 3.12 18.18 0.73 8.03 0.99 14.72 1.30 16.01 cis-PPL 5.44 t * 1.80 0.53 9.11 t 3.10 t 10.73 0.17 4.03 CPE 1.49 4.97 9.47 t 6.55 1.34 6:00 am 1.39 2.12 1.01 3.07 other ver
ties 10.34 17.91 .89 1.94 2.58 10.75 1.79 7.13 2.99 3.35 .09 CPD CPD / (CPD + n-pentane)
at the head of the column - 1. 14.09 7.68 2.39 CPD + n-pentane CPD / (Ci'D + n-pentane}
in the column sump 1.83

ro

* t: traces

K) CD CO

cn

22636D1

The ratio of OPD / (CPD + n-pentane) εηο the top of the column to that in the bottom of the column is greater than 1 in each point, which indicates that CPD and n-pentane form an azeotrope with a minimum boiling point and da8 the boiling point of the azeotrope is below 36 ^° C., which makes it easy to separate CPD in the form of the azeotrope with n-pentane from PPL and / or CPE and the like.

Example 2

5-pentane mixtures CPD-n (Experiments 1 to 5) _{f is} the n-pentane and CPD in different, contain ratios listed in Table 4 were prepared, and 20 ml of each mixture were introduced into the apparatus used in Example 1. After the distillation had been carried out under complete reflux for about 1 hour, about 0.2 ml of the initially boiling distillate was collected at a reflux ratio of 120, while at the same time about 0.2 ml of the suinp fraction was taken as a sample. Both samples were analyzed. The results are shown in Table 4.

309828 / 11U

TABEL

attempt
Kr. component composition
of the starting material
<*) Composition on
Head of the column Composition in
Bottom of the column
<*) 1 n-pentane 83.9 78.1 89.0 CPD 11.1 21.9 11.0 2 n-pentane 84.4 76.5 84.6 CPD 15.6 23-5 15.4 3 n-pentane 76.4 73.5 77.4 CPD 23.6 26.5 22.6 A. n-pentane 71.7 72.6 71.5 CPD 28.3 27.4 28.5 5 n-pentane 64.3 72.5 64.0 CPD 35.7 27.5 36.0

UI

CJ) CO CT) O

The CPD concentrations shown in Table 4 at the top of the Column un-i were the concentrations in the bottom of the column on the ordinate uni AbszissenadEe of a graphic representation (not shown), which were graded on the same scale, and the values of the respective experiments were entered in the graphic representation.

The azeotropic composition of CPD and n-pentane can be determined by reading the point at which the resulting Curve and the line on which the CPD concentrations at the top and bottom of the column become the same, i.e., the diagonal line, intersect. This composition was 73% n-pentane and 27? O CPD.

Example 3

Using the same Cc fraction with a boiling range of about 40 to 50 ^° C. and the same device as in Example 1, a comparison was made between the case of adding n-pentane and the case in which no n-pentane was added was carried out. The results are shown in Table 5. The concentration ratio in the top distillate to the concentration in the bottom residue with regard to the individual components was calculated from the results. This ratio is also shown in Table 5. In addition, the ratio of the CPD concentration in the top distillate / CPD concentration in the bottom residue to the concentration of each component in the top / the concentration of each component in the bottom residue was determined for Trans-PPL, Cis-PPL and CPE and listed in Table 6.

- 26 -

BAD ORIGINAL 309828/1 UA

Table 5

composition

of the starting material. {%)

of the head de st illate (%) of the sump residue (%)

Concentration in top distillate / concentration in Sump residue

When adding n-pentane

O CO OO K) OO

n-? entan 41.1 70.7 CPD 8.4 15.2 Trans-PPL ' 25.7 4.0 Cis-PPL 12.5 1.0 CFE 9.3 • 0.1 Other connections 3.0 9.0 Without addition of n-pentane

n-pentane

CPD

Trans-PPL

Cis-PPL

CPE

Other connections

17.4 42.8 20.6 15.2 4.0

44.2

27.7

4.1

2.2

21.8 40.0 8.1

26.4 13.0 9.5 3.0

15.9 43.1 21.5 15.4 4.1

1.77 1.88

0.151 0.077 0.01 3.00

2.78

0.643

0.191

5.31

5.31

Ni CT) CO

ro-

-j

Table 6

CPD concentration in
Head distillate

CPD concentration in
Sump residue

'Concentration of each component in the head distillate

Concentration of each component in the sump residue

With the addition of n-pentane

CO O Trans-PPL n-pentane O Cis-PPL CD CO CPB NJ CO "" " without the addition of

Trans-PPL

Cis-PPL

CPE

12.5 24.4 188

4.5 15.0 20.0

ro

cn do

As can be seen from Table 6 shown above, there are great differences in the case where n-pentane is added in separating CPD from PPL, CPE and the like from the case where no n-pentane is added. If, for example, trans-PPL is considered, the ratio with addition of n-pentane is 12.5 and without addition of n-pentane 4.5, which indicates the significant simplification of the separation, which is achieved by adding n-pentane is achieved.

Example 4

This example illustrates the removal of CPD from CPE containing about 1000 parts of CPD per 1 million part of CPE (1000 ppm) by azeotropic distillation with n-pentane. The sample was prepared by adding n-pentane to the CPD-containing CPE in such an amount that the concentration of the n-pentane can reach about 70 $ 4. This sample was treated according to the same procedure as in. Example 1 and the compositions of the top distillates and bottom residues at the point of the start of the distillation of 10Jjj, 20% and 30% were analyzed and the ratio CPD / (CPD + n-pentane) certainly. All the results obtained are shown in Table 7.

309828/1

Table 7

O CO CO

composition

of the output s materials

at the point at the point where the distillation of 10% begins

at the point of
distillation
from 2O? 4

at the point of distillation of 30%

Part of the distillation column

Temperature (- ⁰ C)

n-pentane CPB (ppm)

CPJS

CPD χ

CPD + n-pentane

30.5 379 head swamp
37.0 38.0

head
37.0

swamp
40.0

69.5 99.2 63.8 98.9 52.3 (300) (2860) (91) (1170) (59) 0.5 36.2

143

1.0 47.7
97

Head swamp
37.5 40.0

98.8 52.3

(572) (25)

1.1 47.7

48

Head swamp

57.5 44.0

98.5 40.5 (328) tons

1.5 59.5 332 0

O I

m co cn

From the results shown above, it can be seen that the CPD initially present in a concentration of about 1000 ppm in the CPE used as the starting material was removed to the extent that it is only present in traces at the time of distillation of 30% of the sample. In addition, the CPD / (CPD + n-pentane) ratio at the top of the column is always greater than that at the bottom of the column, which obviously indicates the formation of an azeotrope. This shows that the azeotrope is more volatile than n-pentane.

Example 5

_{The C 1} fraction obtained by steam cracking naphtha was freed from a fraction with a boiling point below AO ⁰ C by distillation and the fraction is ^{heated to about 100 0} C in order to dimerize most of the CPD contained therein. After that, the? Fraction (which consists mainly of C ^ fraction and DCPD) removed by distillation, a fraction with a boiling range from 40 to 50 ⁰ C being obtained. This fraction is used as the starting material for this example. The fraction has the composition shown in Table 8.

According to the procedure shown in Fig. 1, the fraction shown in Table 8 is introduced in an amount of 667 ha / hour into a distillation column 3 having 150 actual trays in the 45th tray from the top of the column. Then 70 mol / hour of n-pentane are fed to the 80th tray from the top of the column through a special line. The reflux is adjusted so that an amount of 3700 mol / hour is recycled. In this V / else the azeotropic distillation under normal pressure at a column top temperature of 36 ⁰ C and 63 ⁰ C by Sumpftemeperatur is performed. This distillation gives 130 mol / hour of a top fraction and 607 haul / hour of the bottom fraction. The CPD content of the bottom fraction is 20 ppm.

- 31 -

309828/1 UA

Then this fraction is fed to the 150th tray from the top of the column of an extractive distillation column 10 having 200 actual trays and dimethylformamide containing 1 wt. ^C / o metadinitrobenzene and 200 ppm sodium nitrite is added at a rate of 7600 mol / hour Head of the column introduced. An overhead distillate from a column 18 is returned to the bottom of the column 10 at a rate of 530 mol / hour. The extractive distillation is carried out at a reflux rate of 1900 mol / hour under normal pressure at a column top temperature of 46 ⁰ C and a bottom temperature of 130 ⁰ C. With the help of this process, a CE6 fraction which contains 3 ppm CPD is obtained at the top of the column, and a solvent which contains 967.7 mol / hour of a PPL fraction is obtained in the bottom of the column. The bottom liquid is introduced into a stripping or desorption column18 with 40 actual trays at the location of the 15th tray from the top. The stripping is done with a flow of 450 mol / hour, wherein a proportion of v ^o n 530 mol / is returned hour into the column 10 at atmospheric pressure, a column head temperature of 43 C and a column bottom temperature of 163 ° C. This gives a PPL fraction containing 20 ppm CPD at a ratio of 437.7 Llol / hour. The solvent regenerated in the bottom of the column is returned to the extractive distillation column 10 after cooling to 43 ^{° C.}

Table 8 shows the composition (in M0IJ6) and the Amount (haul / hour) of each fraction obtained in the method described above.

- ^ 2 309828/1144

Table 8

Charging the azeotropic distillation column 3

Top fraction sump fraction from column 3 tion

Column 3

Head fraction Head fraction extraction of the tive distile desorption column ne 10

Mon, e; e (moles / hour) 667 130 607 169 (860 , 3 437.7 Isoprene 1.3 6.8 _ _ (3 _ n-fentan - 53.9 (240 ppm) 1, ppm) - CFD 3.5 11.6 (20 ppm) (100 ppm) (20 ppm) 2-methylbutene-2 2.5 18.0 0.3 (65 0 - Trans-PPL 37.6 9.1 39.3 74, ppm) 54.5 Cis-PPL 29.1 0.4 31.8 24, ppm) 44.2 CP2 19.6 0.2 21, 6 - 5 1.1 ** Cyclopentane 6.2 - 6.8 - 4th - Higher acetylene 0.1 - 0.1 0.1 Cg group 0.1 - 0.1 0.1

Cyclopentane present in the feed mixes with the CPE fraction. This can be removed by distillation if necessary.

The extractive distillation of the second stage is carried out as follows: 437.7 mol / hour of the column top fraction from the desorption column 18 are transferred to the extractive distillation column 28 of the second stage, which has 70 actual trays, at the point of the 35th tray from the top, introduced. The regenerated solvent having the same composition as the above-mentioned solvent is allowed to flow down from the upper part at a rate of 1,600 mol / hour. At the same time, 350 mol / hour of a top fraction from the second desorption column 36 are returned to the bottom of the column 28. The extractive distillation is carried out at a reflux of 400 fetch / hour, atmospheric pressure, a head temperature of 43 ⁰ C and a bottom temperature of 130 ⁰ C. As a result, 433.6 mol / hour of a PPL fraction are obtained as the top fraction, which contains practically no higher acetylene and no CPD, with only 95 ppm of the higher acetylene being present. From the bottom of the column, higher acetylene and part of the PPL are drawn off in the form of a solution in the solvent and introduced into the 15th tray at the top of the desorption column 36 of the second stage, which has 40 actual trays. The bottom of the column is then heated in order to carry out the desorption of the higher acetylene and part of the PPL dissolved in the solvent under normal pressure with a reflux of 400 mol / hour, the amount returned to the column 28 being 350 mol / hour. The solvent from the bottom of the column is returned to the extractive distillation column 28 after cooling to 43 ° C. The composition (mol? O) and the amount (mol / hour) of each fraction obtained from the curtain described above are shown in Table 9.

309828/1 IU

Table 9

Top fraction of the desorption column 18

Head fraction the extractive distillation column 28

Top fraction of desorption " column 36

Mer.ne (mole / hour) Isoprene co n-pentane O CPD OO 2-IIethylbutene-2 co Trans-PPL _> Cic-PPL CPU I ». Cyclopentane higher acetylene C r- fraction
D.

437.7

■ (20 ppm)

433.6

(5ppm)

4.1

0.1

54.5 54.7 32.9 44.2 44.2 47.0 1.1 1.1 - 0.1 (95 ppm) 10.0 0.1 (45 ppm) 10.0

T ¹ O

CD U)

VJl

Example 6

The process steps of this example correspond to those of example 5, with the modification that instead of n-pentane a fraction containing n-pentane is used. Even the second stage extractive distillation carried out in Example 5 to remove higher acetylene omitted in this example. The fraction containing n-pentane is used as the raffinate in the process of extraction of isoprene obtained from a Cp fraction and has the following Composition:

Table 10 11.9 (MoljS) C ^ fraction 30.5 Isopentane 34.7 n-pentane Penten3 (except 18.5 2-methylbutene-2) 4.2 2-methylbutene ~ 2. 0.2 Isoprene

100

_{The C r} fraction used as feed (667 mol / hour) is fed to the 45th tray from the top of the distillation column 3, which is 150 actual trays to v / e. The fraction containing n-pentane described above is fed to the 80th tray from the top at a rate of 203 mol / hour through a separate line. Under a reflux rate of 2800 mol / hour, the azeotropic distillation under normal pressure at / Aopftem-temperature of 33 C and a bottom temperature of 63 ⁰ C is performed. In this way, 268 haul / hour of a top fraction and 602 mol / hour of a bottom fraction are obtained. The CPD content in the soil fraction is 24 ppm. Thereafter, this fraction is fed to the 150th tray of the extractive distillation column 10, which has 200 actual trays. Then the solvent that the

- 36 -

309828 / 1U4

is the same as in Example 5, introduced into the top of the column at a rate of 7600 mol / hour. In addition, 530 mol / hour of the top distillate of column 18 are returned to the column bottom. In this way, the extractive distillation is carried out under a reflux of 1900 mol / hour under normal pressure at a column top temperature of 46.degree. C. and a bottom temperature of 130.degree. This distillation gives a CPE fraction containing 2 ppm of CPD at the top at a rate of 168.5 ha / hour, while a solvent containing 963.5 mol / hour of PPL is obtained in the bottom. The bottom liquid thus obtained is introduced into the 15th tray of the desorption column 18, which has 40 actual trays. Here the desorption at a reflux of 450 mol / hr, a recycled into column 10 amount of 530 mol / hour, under normal pressure, at a Köpftemperatur of 43 ° C and a bottom temperature of 163 ⁰ C is performed. In this way, 433.5 mol / hour of an FPL fraction are obtained which contains 25 ppm of CPD. The regenerated solvent at the bottom of the column v / ill be in the extractive distillation column is returned after it cooled to 43 ⁰ C wurde..Tabelle 11 shows the composition (MoIJo) and the amount (mol / hour) of each fraction obtained by the above-described Procedure is obtained.

- 37 -

309828/1 IU

Table 11

Feeding top fraction sump fractionator azeotro- the column "tion of the
pen distillation 3 column 3.
lation colon-3

no

Head fraction- Head fraction of the tion of the extractive desorptives Distillation column 18 column 10

O CD CO K> OO

Previous year 03

Amount (mol / h)

Isopentane

Isoprene

n ~ Fentan

Pentene ·. (except 2-methylbubsn-2)

2-1-Ia thylbutene-2

CPD

Trans-PPL

Cis-PPL

CPS

Cyclopentane

higher acetylene

Cg group

268

602

168.5

433.5

- 9.1 - - - (25 - - 23.1 - - 55 , 1.3 3.5 - - - 43, , - 26.2 (355 ppm) 0.1 - 0, - 14.0 (492 ppm) 0.2 - - 2.5 • 8.3 0.5 1.8 - 0, ppm) 3.5 8.8 (24 ppm) (2 ppm) 0, 4th 37.6 4.0 39.9 (130 ppm) 7th 29.1 1.9 31.4 (12 ppm) 7th 19.6 1.1 21.2 73.8 6.2 - 6.8 24.1 1 0.1 - 0.1 - 1
rc 0.1 - 0.1 - co O

Example 7

The process steps of this example are identical to those of Example 5, with the exception that the process scheme is applied according to FIG. 2 and that the extractive distillation of the second / second stage to remove higher Acetylene is omitted.

The C (fraction of the composition shown in Table O is fed as a feed to the 150th tray from the top of the extractive distillation column 52, which has 200 actual trays, at a rate of 66 [moles / hour]. A solvent is then added in a At a rate of 8000 mol / hour, 550 mol / hour of a top distillate from column 61 are returned to the bottom of the column, so that the extractive distillation is carried out under a reflux of 2000 mol / hour under normal pressure a. column head temperature of 45 ⁰ C and a Sumpftemeperatur of '130 ⁰ C made. in this case, v / ground obtained from the top of the column 195 moles / hour of a CPE fraction. one dissolved in the solvent PPL fraction is removed from the bottom of the column and is fed to the 15th tray from the top of desorption column 61, which has 40 actual trays, stripping is carried out at a reflux of 450 moles / hour, one in di e performed column 52 the recirculated amount of 550Hol / hour under normal pressure and at a column top temperature of 43 C and a bottom temperature of 163 ⁰ C. A PPL fraction is obtained from the top of the column at a rate of 472 mol / hour. The regenerated solvent obtained in the bottom of the column is returned to the extractive distillation column after cooling to 45 ° C. with the aid of a cooler. The PPL fraction thus obtained is counted through line 102 to the 45th tray from the top, fed to the distillation column 87, which has 150 actual trays. In this column - is through another

- 39 309828/1 UA

Line to the 80th floor n-pentane at a rate of 68 moles / hour fed to the azeotropic distillation is carried out under a reflux of 2400 mol / hour under normal pressure at a column top temperature of 37 ⁰ C and a bottom temperature of 63 ⁰ C. This process gives 109.9 mol / hour of a top fraction and 430.1 mol / hour of a bottom fraction containing 35 ppm of CPD.

Thereafter, the CPE fraction from the top of the extractive distillation column 52 is fed to the 45th tray, calculated from the top, of the distillation column 95, which has 150 actual trays. Another line then supplies 3 mol / hour of n-pentane to the 80th tray of the column. The azeotropic distillation is carried out at a reflux of 600 mol / hour under normal pressure at a column top temperature of 37.degree. C. and a bottom temperature of 64.degree. In this case, be 35 8 mol / hour of a head "fraction and obtain 162.2 moles / hour of a bottoms fraction. The fraction is a CPE fraction which contains practically no CPD, ie only 20 ppm CPD.

In Table 12 is the composition (mol%) and the amount (Mol / hour) of each fraction obtained in the above-described operation.

309828 / 11U

K-n-e (Moi / h) feed
the extrak
tive De
stillations
column 52 Table 12 Headframe
tion
De 3orp-
ti-: ns ko
lonne 61 Head fracture
tion of
azeotropic
pen De-
still-
tion co-
lonne 87 Swamp-
frak-
tion
from Ko
lonne
87 Head fracture
tion of
azeotropic
pen Ko
lonne 95 Sump frac
tion of
Column 95 -xr Isoprene 667 Head fracture
tion
column
52 472 1O? ₉ 9 430.1 35.8 162.2 O f. \ η-pentane 1.3 195 0.5 2.0 18.2 _ νΛ /
CD
CD CiD - 3.3 - 61.3 (165 ppm) 8.2 (130 ppm) CO 2-: othylbutene-2 3.5 - 4.8 20.2 (35 ppm) 2.8 (20 ppm) CO Tr-ns-PPL 2.5 0.5 - - - 42.3 1.1 C :. c-FPL 37.6 8.6 53.2 15.6 54.6 - (120 ppm) Cr υ 29.1 (100 ppm) 41, 1 0.9 45.0 - (27 ppm) Cyclopentane 19.6 (22 ppm) 0.2 - 0.2 28.5 73.4 holisres acetylene 6.2 66.4 - - - - 25.5 Ο, ς group 0.1 21, 2 0.1 - 0.1 - - 0.1 - 0.1 - 0.1 - _ -

CO CD O

Claims (1)

Claims 1. Process for separating cyclopentadiene, cyclopentene and / or 1,3-pentadiene from a cyclopentadiene-containing cyclopentene and / or 1,3-pentadiene hydrocarbon fraction, characterized in that this fraction is distilled in the presence of n-pentane, thereby separating the cyclopentadiene as an azeotrope with n-pentane and a cyclopentene and / or 1,3-pentadiene fraction with lower content of cyclopentadiene wins. 2. The method according to claim 1 _5, characterized in that a C ^ fraction with a boiling range of 40 to 50 ⁰ C is used as the starting fraction. 3. The method according to claim 1 or 2, characterized in that a fraction is used as the starting fraction which was obtained by first heating the C (hydrocarbon mixture obtained as a by-product of the cracking of hydrocarbons) in order to dimerize most of the cyclopentadiene , was then distilled to remove the fraction with boiling points of more than 50 ⁰ C »then the distillate was subjected to extraction or extractive distillation, a mixture of isoprene, 1,3-pentadiene, cyclopentene and residual cyclopentadiene was obtained and therefrom Isoprene by distillation em-icr-nt v / urde. 309828/1 144 4. The method according to claim 1, characterized in that a fraction is used as the starting fraction obtained by adding a Cc-hydrocarbon mixture formed by the dehydrogenation of pentanes and / or pentenes was first subjected to extraction or extractive distillation and from the mixture of isoprene thus obtained, 1,3-pentadiene, cyclopentene and cyclopentadiene the isoprene was removed by distillation. 5. The method according to claim 1, characterized in that a fraction is used as the starting fraction, which is obtained by distilling a C, - coblenwasscr · - substance mixture and removing the distillate with a boiling point below 40 ⁰ C, dimerize most of the cyclopentadiene by heating and anschliaßende distillation for removal of the fraction was obtained having a boiling point of greater than 5O ⁰ C. 6. The method according to claim 1, characterized that the starting fraction is a fraction obtained by partial hydrogenation of cyclopentadiene Cyclopentene and cyclopentadiene are used. 7. Process according to Claims 1 to 6, characterized in that n-pentane is added in an amount which is about 2.7 times or more, based on the molar amount of the cyclopentadione to be removed. 0. The method according to claims 1 to 7, characterized in that g e - - 45 309828/1 UA 22636Q1 indicates that n-pentane is added in the form of a hydrocarbon mixture containing n-pentane. 9. Process according to Claims 1 to 8, characterized in that there is the azeotropic distillation carries out at normal pressure. 10. The method according to claims 1 to 9, characterized g e k e η η ζ e i c h η et that the n-pentane is introduced into the middle or lower part of a distillation zone. 11. The method according to claims 1 to 9, characterized that one has the n-pentane before the azootropic Distillation mixed with the starting fraction. 12. The method according to claims 1 to 11, characterized in that " that the azeotrope obtained is heated to form an n-pentane-dicycloperitadiene mixture. 13. Process for the separation of cyclopentene and pentadiene ~ 1 , 3 with low ^^ e content of cyclopentadiene from a hydrocarbon fraction, ^ ie contains cyclopentene, 1,3-pentadiene and cyclopentadiene, as characterized in that this fraction is in the presence distilled from n-pentane to remove cyclopentadiene as an azeotrope with n-pentane and a mixture of cyclopentene and 1,3-pentadiene with a low content of cyclopentadiene rev / innt and the resulting mixture using a polar solvent of 1ϊ: -ι ~ - 44 ~ 309828/1 1 AA BAD ORlBlNAt Subjected to traction or extractive distillation, with cyclopentene as the less soluble fraction and pentadiene-1,3 can be obtained as a more soluble fraction. 14. Process for the separation of cyclopentene and pentadiene 1,3 with a lower content of cyclopentadiene from a hydrocarbon fraction, which contains cyclopentene, 1,3-pentadiene and cyclopentadiene, characterized in that that this fraction can be obtained using a polar solvent extraction or extractive distillation subject, with cyclopentene being more soluble Fraction and a mixture of 1,3-pentadiene and cyclopentadiene as a more soluble fraction together with the solvent are obtained, the more soluble fraction freed from the solvent and the freed from the solvent Fraction distilled in the presence of n-pentane, the cyclopentadiene being removed as an azeotrope with n-pentane and 1,3-pentadiene is obtained. 15. The method according to claim 14, characterized in that one also the less soluble Fraction distilled in the presence of n-pentane in order to remove entrained cyclopentadiene as an azeotrope with n-pentane and the cyclopentene wins. 16. Process for the separation of cyclopentene and 1,3-pentadiene with lower: content of cyclopentadiene and higher acetylene from a hydrocarbon action, the cyclopentene - 45 - 3 0 9 8 2 ^{8/1 U 4 BAD Or} 'G / .Mal Contains 1,3-pentadiene, cyclopentadiene and higher acetylene, characterized in that this fraction is distilled in the presence of n-pentane to give cyclopentadiene to remove as an azeotrope with n-pentane and to obtain a mixture of cyclopentene, 1,3-pentadiene and higher acetylene, the mixture obtained using a polar solvent of a first stage extraction or extractive Subjected to distillation, with cyclopentene as the less soluble fraction and a mixture of 1,3-pentadiene and higher acetylene as a more soluble fraction together with the solvent v / ground, the mixture of the Strips solvent and the mixture using a second stage extraction or extractive distillation subjected to a polar solvent, with pentadiene-1,3 obtained as the less soluble fraction and the higher Acetylene is removed as the more soluble fraction. 17- Process for the separation of cyclopentene and 1,3-pentadiene with a lower content of cyclopentadiene and higher acetylene from a hydrocarbon fraction, the cyclopentene, Contains 1,3-pentadiene, cyclopentadiene and higher acetylene, characterized in that these Fraction from a first stage extraction or extractive distillation using a polar solvent subject, with cyclopentene as the less soluble fraction and a mixture of 1,3-pentadiene, cyclopentadiene and higher acetylene as a more soluble fraction together - 46 309828/1144 SAD ORiGiNAL ground with the solvent, the mixture of the Strips off solvent, the mixture obtained is distilled in the presence of n-pentane to form the cyclopentadiene as an azeotrope to remove with n-pentane and a mixture of pentadiene-1,3 ■ and higher acetylene and the mixture obtained in a second stage of extraction or extractive distillation using a polar solvent, with 1,3-pentadiene recovered as the less soluble fraction and removing the higher acetylene as the more soluble fraction. 18. Process for the separation of cyclopentene and 1,3-pcntadiene with a lower content of cyclopentadiene and higher acetylene from a carbon fraction, cyclopentene, 1,3-pentadiene » Contains cyclopentadiene and higher acetylene, characterized in that this fraction a first stage of extraction or extractive distillation using a polar solvent subjected to cyclopentene as a less soluble fraction and a mixture of 1,3-pentadiene, cyclopentadiene and higher Acetylene to win as a more soluble fraction together with the solvent, the mixture from the solvent stripping the resulting mixture using a second stage extraction or extractive distillation subjected to a polar solvent, with pentadiene-1,3, that verum'oinigt with a small amount of cyclopentadiene int; as a less soluble fraction and a mixture of higher - Al - 309828/1 UA Acetylene with a larger proportion of cyclopentadiene can be obtained as the more soluble fraction, and the contaminated 1,3-pentadiene distilled in the presence of n-pentane to remove the cyclopentadiene as an azeotrope with n-pentane and to obtain the pure 1,3-pentadiene. 19. The method according to claim 18, characterized in that also the obtained cyclopentene distilled in the presence of n-pentane in order to remove entrained cyclopentadiene as an azeotrope with n-pentane and to obtain pure cyclopentene. 309828/1 1