JPS6044586A - Separation of ethylenic unsaturated hydrocarbon from hydrocarbon mixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved process for the separation of ethylenically unsaturated hydrocarbons from hydrocarbon mixtures containing them.

Various hydrocarbon mixtures have been obtained from the pyrolysis of petroleum products such as naphtha, gas oil, kerosene, crude oil, etc. A typical hydrocarbon mixture from a cracking operation is pyrolysis gasoline containing aromatic and cycloparaffinic compounds, generally having 5 to 10 carbon atoms. A typical hydrocarbon mixture obtained after removal of hydrocarbons containing 5 carbon atoms is shown in Table A.

Table A Benzene 33-37 Toluene 16-2゜Ethylbenzene 1-2 7) /mXylene 5-7 0-xylene 2-3 Styrene 6-8 Dimethylcyclopentadiene <I C9 aromatics ~1 α-methylstyrene (1 Vinyl Toluene 2.5-3 Indene 2.5-3 Methylindene 1 Naphthalene 1 Phenylacetylene 0.1 [The above hydrocarbon mixtures were used to illustrate typical hydrocarbon mixtures, and It is to be understood that hydrocarbon mixture compositions can vary widely and are not intended to define such mixtures.

A mixture of the above is found in the middle section. One of the industrially valuable components of CJ+ is styrene. Economic means of separating this preferred component have long been sought. Separating styrene from these mixtures by fractional distillation separates the other components, which have boiling points very close to that of styrene,
In particular, the presence of 0-xylene makes it impractical. Table B shows the boiling points of styrene and other hydrocarbons.

Table B Compound Boiling point °C α-methylstyrene 163.4 n-propylbenzene 159.2 Cumene 152.4 Cyclooctane 148.5 Styrene 145.2 0-xylene 144.4 3-Methyloctane 143-144 Cyclooctene 138-143 Phenylacetylene 142.4 4-Methyloctane 141-142 7,-xylene 139.1 p-xylene 138.4 Ethylbenzene 136.2 Toluene 110. One widely used process for utilizing styrene is to hydrogenate the styrene to form ethylbenzene, which is then separated from the styrene by precision fractional distillation.

After this distillation, the ethylbenzene is then purified by dehydrogenation to styrene and distillation again. This method is extremely complex and expensive.

The disadvantages of the aforementioned methods have prompted research into the direct separation of styrene from hydrocarbon mixtures without first converting the styrene to ethylbenzene.

British Patent No. 1,038,606 proposes a method for extracting styrene from a hydrocarbon mixture using an aqueous solution of a silver salt such as AgNO3, followed by treatment with a mixture of clay to prevent slime formation. There is. This method has the disadvantage of being expensive due to the use of silver salts.

U.S. Pat. No. 3,328,267 also proposes a process consisting of extractive distillation for the separation of styrene using a di-lower-alkylformamide, such as dimethylformamide, as the extractive distillation solvent. This process also utilizes polymerization inhibitors such as quinones or hydroxynes or preferably p-tert-butylpyrocatechol. However, the styrene produced by this method has the undesirable property of being pale yellow in color. It is also necessary that the polymerization inhibitor has a 7+'4 effect at low temperatures.

U.S. Patent No. 3,580,839 (Frberst)
entitled ``Recovery of Aromatic Hydrocarbons from Hydrocarbon Mixtures by Selective Extraction Using Substituted Piperazine Solvents'', in which piperazine derivatives having the general formula (where X is formyl or acetyl and R is lower alkyl.) Lower (1-4G') from a hydrocarbon mixture
It is proposed to be used as an extractant for mono- and dinuclear aromatic hydrocarbons which may have aliphatic hydrocarbon substituents. Therefore, this method separates a hydrocarbon mixture into two fractions; one containing mainly aromatic hydrocarbons, such as benzene, toluene, xylene, ethylbenzene and styrene, and the other mainly containing paraffins, olefins and cycloparaffins. Separation into other fractions is proposed. Piperazine derivatives can be used in pure form or mixed with other extractants such as tetramethylsulfone, diethylene glycol or triethylene glycol. N-formyl-N'-methylpiperazine is the preferred extractant. This process aims at general separation of the products.

In U.S. Pat. No. 3,684,665, Abe et al. describe a process for the separation of styrene from hydrocarbons, including xylenes, in which the styrene is concentrated in a solvent, from which the styrene can then be recovered. proposed a method consisting of extractive distillation using Suitable solvents include dialkyl sulfoxides, alkylene carbonates, lactones, lactams, phenol, alkylphenols, salicylic acid, alkyl esters, aniline, alkylanilines, phthalic acid alkyl esters, tetraalkylureas, #, Included are dialkyl acetamides such as dimethylacetamide, along with #'-dialkylcarbamate esters and glycol monoalkyl esters such as hishyethylene glycol monoalkyl ether and N-methylpyrrolidone. The use of polymerization inhibitors such as hydroquinone, tert-butylcatechol, phenothiazine, sulfur or mixtures thereof acts to prevent styrene polymerization. This process, however, has the disadvantage that, especially at temperatures above 100 DEG C., polymerization losses are high and styrene is produced which is undesirably yellow in color.

In Japanese Patent No. 3,763,015, Morimoto
et al. describe another extractive distillation process using polar organic solvents in the coexistence of nitrile polymerization inhibitors. Following extractive distillation, the styrene-containing solvent is treated with nitric acid and then distilled again to remove impurities and separate the styrene from the solvent. Suitable solvents for this process are shown as diethylacetamide, β-methylpropionitrile, butyllactone, N-methylpyrrolidone, dimethylformamide and dimethylsulfoxide.

A preferred polymerization inhibitor is sodium nitrite or potassium nitrite, which is used in combination with a compound having at least one nitro, nitroso, quinoid, phenolic or hydroxyl group in the molecule. The preferred additive is p −t
ert-butyl-catechol, hydroquinone, p-benzoquinone, p-dinitrosobenzene, α-nitro-β-
naphthol, 0-nitrone naphthol and α-naphthoquinone. This process produces a yellow styrene product that requires further treatment with nitric acid to remove colored impurities. Another problem is a decrease in yield due to polymerization.

In view of the foregoing shortcomings of the prior art, monovinylidene aromatic or other ethylenically unsaturated hydrocarbons can be removed from hydrocarbon mixtures containing them at the same time by completely preventing polymerization to produce substantially pure, color-free products. It would be highly desirable to provide an effective separation method for producing products.

The present invention provides a method for preparing a hydrocarbon mixture containing unsaturated hydrocarbons by (a) having more than one amino group, and (1) having sufficient amino acid concentration to selectively separate the unsaturated hydrocarbons from the hydrocarbon mixture. is electronegative, (2) inhibits polymerization of unsaturated hydrocarbons, and (3) allows separation of amines from unsaturated hydrocarbons following selective separation of unsaturated hydrocarbons from a hydrocarbon mixture. (b) separating the amine/hydrocarbon mixture into at least two parts, one of which contains the amine and the unsaturated hydrocarbon; A method for separating ethylenically unsaturated hydrocarbons from a hydrocarbon mixture is provided.

It is then possible to separate the unsaturated hydrocarbons from the amine fraction, or to carry out the entire subsequent process without separation.

Soluble amine (hereinafter referred to as "amine") means an amine that is soluble in the styrene/hydrocarbon mixture within the operating temperature range.

Surprisingly, in the extractive distillation process using amines as described above, ethylenically unsaturated hydrocarbons are extracted from hydrocarbon mixtures containing them in U.S. Pat. Effective separation can be achieved without the addition of other solvents and/or polymerization inhibitors as described in the above. Using this method, aliphatic unsaturated hydrocarbons such as butadiene or acetylene or monovinylidene aromatics such as styrene or vinyltoluene with unexpectedly high purity and/or desirable color can be produced without significant losses due to polymerization. You can get it without any problems. In a preferred embodiment of the invention, the amine is N-(aminoethyl)piperazine (AEP)
It is. In a particularly preferred embodiment, AEPk is used as an amine solvent or as an extractant in an extractive distillation process for the separation of styrene from styrene-containing hydrocarbon mixtures. Due to the removal of color by ARP, styrene with the color desired on the market can often be recovered in purity greater than 99%.

An understanding of the invention will be facilitated by reference to the accompanying drawings.

FIG. 1 is a schematic diagram illustrating an embodiment of the invention particularly useful for the separation of vinyltoluene from vinyltoluene and other CO aromatics or acetylene from mixtures containing butadiene and butenes, and FIG. 1 is a schematic diagram illustrating a more preferred embodiment of the invention, which embodiment is particularly effective for separating styrene from hydrocarbon mixtures consisting primarily of hydrocarbons having 6 to 10 carbon atoms.

The method of the invention is best illustrated through a basic discussion of extractive distillation. Extractive distillation refers to a process in which high-boiling substances, often referred to as extractive distillation solvents, are added to alter the specific volatility of the hydrocarbon mixture to be subsequently separated using the extractive distillation process.

Generally, there are two main reasons for adding powerful solvents. The first reason is to change the specific volatility of one or more components in the feed stream. In particular, one or more components are distilled together as long as they have similar vapor pressures and do not change the non-volatility of the components. for example,
Solvents change the non-volatility of unsaturated compounds and also change the specific volatility of materials with acetylene unsaturation compared to materials with ethylenic unsaturation.

A second reason for using a solvent is to prevent azeotrope formation of the raw mixture components. Generally, the added solvent has a higher boiling point than the components in the feed mixture, thus preventing the formation of azeotropes.

With particular reference to the accompanying drawings, FIG. 1 shows one embodiment of the present invention for separating ethylenically unsaturated hydrocarbons, such as vinyltoluene, from a hydrocarbon mixture containing them using an extractive distillation column. Illustrated schematically. In the illustrated embodiment, a hydrocarbon mixture containing unsaturated hydrocarbons is fed by line 10 to extractive distillation column 101 . Amine solvent, preferably N-aminoalkylpiperazine, is added to column 101 via line 11. Because it is generally desirable to maintain a high concentration of amines throughout the extractive distillation column, and because amines generally have low volatility as chain components of hydrocarbon feedstocks, amines are preferably used to transfer hydrocarbon feedstocks to extractive distillation columns. It is also added to the tower at the point above. It is also preferred to add the solvent at a point sufficient below the top of the distillation column to make the amine concentration in the rising vapors negligible before passing the overhead product out. The vapor exiting the top of column 101 is directed to overhead condenser 12 to condense the vapor. A portion of the condensed vapor is returned to column 101 as a liquid overflow. Line 13 is vinyltoluene and α
- methylstyrene, dicyclopentadiene or generally α
- 1.2.4- or 1,2.3- containing methylstyrene and/or dicyclopentadiene) Distillate from the separation of vinyltoluene from a hydrocarbon mixture containing methylbenzene carry away. The material to be extracted, i.e. ethylenically unsaturated hydrocarbons such as vinyltoluene, and the high boiling point components (bottoms) of the hydrocarbon feedstock are passed through line 14 to column 1.
01 is taken out from the bottom of the tower. Because amines have relatively high boiling points, the bottoms removed by line 14 generally contains a high concentration of amine. The materials removed through line 14 generally pass through reboiler 15 where some of their components are returned to column 101 as reboiler steam.

Most of the bottoms material is not returned to column 101 and enters stripping column 202. As illustrated in the embodiment shown in FIG.
It has been introduced in 2.

Further addition of amines is not necessary for the process of the invention, but is preferred, especially when the bottoms exiting column 101 contain high boiling materials other than phenylacetylene or amines. The unsaturated hydrocarbons leave column 202 as vapor,
It is led to a condenser 22 to condense the gaseous substances. A portion of the condensed material is returned to column 202 and the remainder is withdrawn via line 23. The material in line 23 is essentially pure, ie, at least 98% pure, preferably at least 99% pure, and of good color.

The amine, along with any impurities it may contain, leaves the bottom of the stripping column and a portion of this material passes through boiler 24. Since the residue portion generally contains some impurities such as high boilers and polymeric materials or the like, the amine is effectively purified prior to reuse. As such a purification method, a method of subsequent distillation is generally effective. In FIG. 1, the amine is introduced into a total purification column 303, and highly volatile impurities are distilled off via line 30.
Purification is carried out by returning the product to both the extractive distillation column and the stripping column. Heavier or less volatile impurities can be removed through line 31.

FIG. 2 illustrates a preferred embodiment of the present invention that is particularly useful for total styrene recovery from hydrocarbon products obtained from the cracking of petroleum products such as naphtha, gas oil, kerosene, or crude oil and the like. The preferred embodiment shown in FIG. 2 includes: 0) a first extractive distillation column 111 for separating styrene from liquids with close boiling points such as xylenes, especially 0-xylene, and ethylbenzene; (b) an amine solvent; (c) a second extractive distillation column 333 for the removal of high boiling substances and impurities from styrene, (6) (g) a solvent recovery column 444 for removing high boilers and impurities such as phenylacetylene from the amine; and (g) a solvent purification column 555 for removing heavy impurities such as polymers from the amine.

The recovery of styrene from hydrocarbon mixtures obtained from cracking operations typically requires a pre-distillation column (not shown) for the removal of light hydrocarbons, such as those having 5 or fewer carbon atoms, and generally 11 or more columns. A pre-distillation column (not shown) for the removal of heavy hydrocarbons, such as those containing carbon atoms, is often included in column 11.
It is advantageously used prior to introducing hydrocarbons into 1. In such a case, the removal of light and heavy hydrocarbons is effectively carried out under conditions that produce a hydrocarbon fraction having a boiling point of 120° C. to 160° C., preferably 125° C. to 155° C., at normal pressure. .

In such an operation, a styrene-containing hydrocarbon mixture is introduced through line 2 into the first extractive distillation column. A hydrocarbon mixture is introduced into column 111. At the same point that the hydrocarbon mixture is introduced into column 111, the amine is introduced into the first extractive distillation column.

In order to reduce the amine concentration in the overhead product, this amine inlet is located several trays (which may be the number of effective or theoretical plates) below the top of the column 111. The exhaust vapor from the top of column 111 is conducted to an overhead condenser where all of the vapor is condensed and a portion thereof is returned to the column. Line 4 withdraws the distillate for further processing and/or subsequent use. Generally speaking, the distillate consists primarily of xylene and ethylbenzene. The materials discharged from the bottom of column 111 are generally separated from impurities such as styrene, amines, phenylacetylene, and high-boiling hydrocarbons (C#) and polymeric materials through the bottom line 5 and solvent storage. It is sent to the ripping tower 222. The remainder of this material is passed through a partial reboiler and returned to column 111.

In the solvent stripper column 222, the amine is
) t) separate. The separated amine is withdrawn from the bottom of column 222 and introduced near the top of the extractive distillation column. The separated styrene, generally containing phenylacetylene and other impurities, exits the top of column 222, is condensed and a portion of the condensate is passed through the inlet 7 to column 333 at a point below the point of introduction of the amine. lead to. In this second extractive distillation column 333,
The styrene is separated from the phenylacetylene and high boiling materials and exits the top of column 333 in a relatively pure form, preferably at least 99% pure. The relatively pure material is condensed and transferred in line 8 for further use. The amine containing phenylacetylene and/or high boilers Mx exits column 333 and a portion thereof is sent via line 9 to solvent recovery column 444. In the solvent recovery column 444,
Amine and phenylacetylene are separated. The phenylacetylene exiting from the top of column 444 is condensed and sent to line 4.
1, move part of c4a for next use. The amine containing impurities, such as polymeric materials, is now removed from line 42 and column 444. A portion of this material is passed through the IJ boiler and returned to column 444. A second, relatively large portion of this material is passed through line 43.
Returned to line 3 for reuse in the first extractive distillation column.

The remaining amine and high boiling point impurities are transferred to line 42.
is introduced into the solvent purification column 555. In column 555, the amine is separated from high boiling impurities. The relatively pure separated amine exits the top of column 555 and is returned to line 3 for continued recycling in column 111. Heavy impurities are withdrawn from the bottom of column 555 in line 44.

For those skilled in the art, it is possible to modify, delete, or add certain process features according to the particular process parameters selected, and such selections may be made for reasons of economy, convenience, and energy conservation. Obviously, this will depend on various practical considerations.

For example, although it is preferred that there be a high concentration of ethylenically unsaturated hydrocarbons to be separated in the hydrocarbon feedstock, lower concentrations are also suitable and within the scope of the present invention. However,
Pre-distillation can be carried out efficiently in order to obtain hydrocarbon feedstocks containing unsaturated hydrocarbons in high concentrations and thus improving the overall efficiency of the separation process. Furthermore, components exhibiting volatility similar to the amine may reduce the practical performance of the amine and should preferably be removed. In addition to the above description, it is clear that multiple separation columns are used at various points in the overall process, such as introduction of hydrocarbon feedstock, amine recovery, etc., and/or purification of various streams. It must have become. Additionally, the extractive distillation portion of the process in which the amine is used as a solvent may be carried out in one or more column columns, with an amine solvent recovery operation between the columns.

With respect to the materials used in the practice of this invention, the hydrocarbon mixture from which the ethylenically unsaturated hydrocarbon is separated is at least two species, one of which is the ethylenically unsaturated hydrocarbon from which the ethylenically unsaturated hydrocarbon is subsequently separated. It is a mixture of the above hydrocarbons.

An ethylenically unsaturated hydrocarbon is an ethylenically unsaturated hydrocarbon between two carbon atoms that are not part of an aromatic ring.
hydrocarbons such as acetylene, alkadienes such as butadiene, monovinylidene aromatics such as acetylene and styrene, alkyl-substituted styrenes such as vinyltoluene, and ethylvinylbenzene and vinylnaphthalene. Other hydrocarbon components may contain ethylenic unsaturation, such as vinyltoluene, which is often present in the separation of styrene from pyrolyzed petroleum products, but generally the other components are primarily aliphatic and This includes cycloaliphatic and aromatic hydrocarbons. Additionally, the hydrocarbon mixture may optionally include one or more inorganic components or hydrocarbon components with substituent groups. The process of the invention is a method of preparing monovinylidene aromatics, especially styrene or vinyltoluene.
It is particularly effective for separation from hydrocarbon mixtures containing one or more aromatic components other than styrene and/or vinyltoluene. Such other aromatic components generally include benzene, toluene, ethylbenzene, o-, p-
and m-xylene and/or indene. In particular, the process of the invention provides the separation of styrene from pyrolysis gasoline and vinyltoluene and α-methylstyrene, dicyclopentadiene, or 1,2.4- or 1.2.3-
) It is preferably used for the separation of vinyltoluene from a mixture of trimethylbenzene.

The amines used in the practice of this invention are amines containing one or more amino groups and (1) ethylenically unsaturated to permit selective separation of unsaturated hydrocarbons from hydrocarbon mixtures. sufficiently electronegative compared to the hydrocarbon, (2) to inhibit polymerization of the ethylenically unsaturated hydrocarbon, and (3) subsequent to separation of the unsaturated hydrocarbon from the hydrocarbon mixture, from the unsaturated hydrocarbon. has a sufficiently high boiling point to allow separation of the amines. The term "soluble" means that the amine forms a solution with the hydrocarbon mixture (i.e., the combination of amine and hydrocarbon mixture has the appearance of a uniformly dispersed or uniform liquid by visual inspection without magnification). means. Generally speaking, when the boiling point of the amine exceeds the boiling point of the unsaturated hydrocarbon to be separated, at least 20°C is preferred at the pressure used in the process. 30 degrees Celsius is high enough. Of course, the greater the boiling point difference, the easier the subsequent separation will be.

An amine that is sufficiently electronegative for the purposes of the present invention is sufficient to maintain the specific volatility of the unsaturated hydrocarbon undergoing separation with respect to other components in the mixture, especially those having boiling points close to the unsaturated hydrocarbon. It is the amine that allows selective separation of unsaturated hydrocarbons from hydrocarbon mixtures (generally reducing the specific volatility of unsaturated hydrocarbons).

In addition to changes in the specific volatility of unsaturated hydrocarbons, amines also prevent the polymerization of unsaturated hydrocarbons, with the same treatment in the presence of amines compared to the same hydrocarbons treated without amines. Fewer unsaturated hydrocarbons are polymerized during the separation process. It is so effective that it contains less than 1%, preferably less than 0.5% by weight of unsaturated hydrocarbons, and does not polymerize during the separation step according to the method of the invention.

Generally, the amines utilized in the method of the invention are at least two
amino or substituted amino groups, one amino group is preferably unsubstituted, and amino or substituted amino groups are separated by two or more, preferably two carbon atoms. ing.

Representative amines are diethylenetriamine and N-aminoalkylpiperazine. The amines most effectively utilized will vary depending on the hydrocarbon being separated, but generally the amines preferably utilized herein are N-aminoalkylpiperazines having 1 to 4 carbon atoms, most preferably The amine is N-aminoethylpiperazine.

The conditions under which the separation of unsaturated hydrocarbons is most conveniently carried out are:
It depends on a number of factors, including the particular amine used and the composition of the hydrocarbon mixture and the unsaturated hydrocarbons separated therefrom. As a particular embodiment, in a preferred embodiment where an extractive distillation column is used to separate a hydrocarbon mixture containing O-xylene and styrene, the extractive distillation column or columns advantageously have a number of theoretical plates of 90 to 130. , and preferably has a theoretical plate number of 115 to 125. This number of stages has been effectively achieved by packing the column with packing material such as regular sheet backing or dumped backing. The extractive distillation process is carried out at a combination of pressure and temperature conditions that are sufficiently effective for separation but do not promote undesired polymerization. Generally, this makes effective use of the bottom temperature of 120°C to 140°C, and
All means that a temperature of 35°C is preferred.

Very high temperatures often promote undesirable reactions and reduce the overall economic efficiency of the process. To help save energy costs and reduce undesirable reactions, the process is generally conducted under reduced pressure. Conveniently, the bottom pressure labor fee is 70 to 125 ran11? Keep it at 110 to 12
A range of 0 mHf is preferred. Similar considerations of efficiency and suppression of undesirable reactions are applied here. The temperature at the top of the column conveniently ranges from 45°C to 70°C, preferably from 45°C to 55°C. Conveniently, the overhead pressure is in the range of about 30 to 45 tmnHf, 3
5 to 45 tmnH? is preferred. The amine/styrene ratio of the hydrocarbon feedstock conveniently ranges from about 5 to about 9;
A ratio of about 8 is preferred.

Styrene from diphenylacetylene by extractive distillation
In another preferred embodiment, the extractive distillation column or columns advantageously have a number of theoretical plates of 70 to 80.
However, a number of stages from 70 to 75 is preferred. The columns used for separation are typically bubble cap, sheep or bulb type trays. The number of plates can also be obtained by packed columns using packing such as sheets or dumped parayoung. Additionally, the extractive distillation process is carried out at a combination of pressure and temperature conditions that are sufficiently effective for separation but do not promote undesirable polymerization. Generally speaking, this means that bottom temperatures of 140°C to 160°C are effectively used, with temperatures of 145°C to 150°C being preferred. Higher temperatures often result in undesirable overall acceleration of reactions, while lower temperatures reduce the economic efficiency of the process. The process is generally operated at reduced pressure, saving energy costs and preventing undesired reactions. Advantageously 100 to 120 mm fi
A bottom pressure of t is used, with a pressure of about 100 mm H9 being preferred.

Similar considerations of efficiency and suppression of undesirable reactions apply here as well. The column overhead temperature conveniently ranges from 45°C to 70°C, preferably from 45°C to 55°C.
℃ range. The overhead pressure is conveniently between 30 and 45°C.
mllf and a pressure of 35 to 4 qwn H1 is preferred. The amine/styrene ratio in the hydrocarbon feedstock advantageously ranges from 7 to 9, preferably about 8.

EXAMPLE 1 A total mixture obtained by pyrolysis of a petroleum fraction such as naphtha is separated in one of the conventional methods, such as by distillation at normal or reduced pressure, and is separated at about 125°C to 155°C.
The boiling point distillate between This fraction contains styrene, xylenes, ethylbenzene, paraffins, naphthalene, polyalkyl-substituted aromatics, phenylalkynes, and
It contained dienes with 9 carbon atoms and typically had an APHA color of 65.

Representative examples of such mixtures are:

Component Weight % Light hydrocarbons 0.6 Benzene and toluene 6.0 Ethylbenzene 8.0 Regular p-xylene 32.0 0-xylene 14.0 Styrene 37.8 C-9 fraction 0.7 C-8 fraction and other aromatics 0.7 This mixture was fed to a packed column about 50 m high with a number of theoretical plates of about 100 to about 125, and at a point about 20 m below the top of the column. Introduced. AEP"f: The column was fed at a point near the top, e.g., about 2 m below the top g, at a weight ratio of AEP:hydrocarbon feed of about 3:1. The reflux ratio was about 7
．． It was 5.

The pressure and temperature at the top was about 60°C after about 30m down, and the reboiler temperature was about 130°C. Even with this high temperature, polymerization losses were less than 0.2 inches based on the styrene present in the feed. The top product of this column contained only about 1.0% styrene, and the bottom product contained almost all of the styrene originally present in the feed. Styrene, AEP
The bottoms product containing the raw phenylacetylene was sent to a stripping column where it was recovered substantially free of ARP't styrene, phenylacetylene and colorants. The styrene/phenylacetylene containing hydrocarbon mixture was sent from the top of this column to a second packed distillation column of about 30 m height with about 70 to 80 theoretical plates and introduced about 30 m below the top of the column. The AEP recovered from the bottom of the stripping tower acts as a solvent and
ARP at a point approximately 2.5m below the top of the distillation column:
The hydrocarbon feed was fed at a weight ratio of approximately 8:1. The reflux ratio was approximately 4. Top pressure and temperature are each about 35
rmnII? and about 50'C, and the reboiler temperature was about 55C.

The top product of this second packed distillation column contained approximately 99.6% pure styrene and was colorless. Since ARP acts as a very efficient inhibitor, the polymerization of styrene is inhibited by this second process.
It was practically zero in the distillation column. Since the colored compounds present remained in the AEP, high purity, low colored styrene was obtained from the top of the second column. The APHA color of the styrene product from the second extractive distillation column was 5 or less. The higher the reflux ratio of the extractive distillation column, the greater the dilution of the extractant due to the total increase in the amount of non-extractant material in the liquid overflow; the effect of this dilution is generally a reduction in specific volatility. I want to be noticed. The optimum reflux ratio is easily determined for a particular process set up by a skilled operator.

Example 2 The method of Example 1 was changed by <9 except that diethylenetriamine was used as the amine. A styrene-rich fraction was also obtained here.

Example 3 α-methylstyrene, 1,2.4- ) Limethylbenzene production 1゜2.3-) 'J In the presence of N-aminoethylpiperazine, vinyl is extracted from a hydrocarbon mixture containing mainly aromatic hydrocarbons with 9 carbon atoms, including All toluene was removed.

The top product from the extractive distillation column contained less than about 2 units of vinyltoluene, while the bottom product contained vinyltoluene, indene, and aminoethylpiperazine. Vinyl toluene with excellent color was easily obtained from indene distillation/or aminoethylpiperazine using an additional extractive distillation column.

Example 4 A hydrocarbon stream containing primarily four carbon atom hydrocarbons including acetylene, butadiene, butene, isobutyne, and butane is fed to an extractive distillation column and then in the presence of N-aminoethylpiperazine. Distilled below.

The material exiting the top of the extractive distillation column contained most of the butadiene, butene, isobutyne, and butane contained in the hydrocarbon feed. The column bottoms consisted essentially of ARP and acetylenes, with only minor amounts of other 04 hydrocarbons present.

Example 5゜ A total of hydrocarbon streams of the following composition were treated.

Isopentane 12 1-pentene 4 Isoprene 18 n-pentane 23 Methyl-substituted butenes 8.4 Other pentenes 3.2 Cyclopentadiene 5.6 Pentadienes 10.5 Other C hydrocarbons 4.6 Other hydrocarbons 8.5 Feed a hydrocarbon stream of the above composition to a full-scale distillation column to separate this stream into a top product containing light components (e.g. C4 hydrocarbons tA) and a bottom product consisting of the remaining components of this stream. separated. A separated hydrocarbon stream containing heavy components is fed to a second distillation column to produce a bottoms product containing all polybutadienes and other heavy components and other components, particularly isopentane, n-pentane and imprene alloys. The top product was separated. Top product kN- from this column
C-aminoethyl)piperazine and 93 parts of ARP per part of the overhead product were mixed and the entire resulting mixture was fed to the third distillation column. The specific volatility of the bulk hydrocarbon component in this stream (now sufficiently different from that of isoprene,
A high purity imprene with a diameter of 98 mm was obtained. One method for obtaining isoprene is to remove the pure isoprene fraction from the side of the column. In another method, no side stream is used and the bottoms product contains a mixture of isoprene, ARP, and 7 clopentadiene. In this method,
Isoprene is easily separated from AEP and/or cyclopentadiene using an additional extractive distillation column.

Alternatively, when ARP is not used, isoprene can only be recovered as a mixture with significant amounts of impentane, n-pentane, cyclopentadiene, and various other components.

Isoprene gold of varying purity can be obtained by the above-described process using varying weight ratios of AEP:isoprene-containing hydrocarbon streams. Specifically, as the relative concentration of ARP to the isoprene-containing hydrocarbon stream decreases, the recovered isogrene generally contains greater amounts of other components.

The above description and examples are intended to fully illustrate the invention and its advantages and should not be construed as limiting the invention. Further variations of the invention will be apparent to those skilled in the art. All such variations are considered to be within the scope of the invention as defined by the claims.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating aspects of the invention. 101...extractive distillation column, 202...stripping column, 303...purification column FIG. 2 is a second schematic diagram illustrating an embodiment of the present invention. 111...First extractive distillation column, 222...
・Solvent) IJ tube tower, 333...Second extractive distillation column, 444...Solvent recovery column, 555...
...Solvent purification tower. Patent Applicant: The Dow Chemical Company 1. ,
';H,, :7.・Procedural amendment (method) October 4, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Indication of the case Patent Application No. 149707 of 1982 2, Title of the invention 3, Relationship with the case of person who makes amended meals Patent applicant

Claims (1)

[Scope of Claims] 1. (a) A hydrocarbon mixture containing an unsaturated hydrocarbon has more than one amine group, and (1) is sufficiently electronegative to selectively separate the hydrocarbons. (2) inhibit polymerization of the unsaturated hydrocarbon, and (3) sufficient to permit separation of the amine from the unsaturated hydrocarbon following selective separation of the unsaturated hydrocarbon from the hydrocarbon mixture. (b) separating the amine/hydrocarbon mixture into at least two parts, one of which contains the amine and the unsaturated hydrocarbon; A method for separating ethylenically unsaturated hydrocarbons from a hydrocarbon mixture, characterized by: 2. The method according to claim 1, wherein the separation in step (b) is carried out behind distillation. 3. The method according to claim 2, wherein the amine is N-(aminoalkyl)piperazine. 4, N-C aminoalkyl)piperazine has 1 to 4 carbon atoms
The method according to claim 3, having a lower alkyl group of 5. The method according to claim 1, wherein the amine is N-aminoethylpiperazine. 6. The method according to claim 3, wherein the ethylenically unsaturated hydrocarbon is a monovinylidene aromatic hydrocarbon. 7. The method of claim 4, wherein the hydrocarbon mixture includes O-xylene and the monovinylidene aromatic hydrocarbon is styrene. 8. The method according to claim 3, wherein the ethylenically unsaturated hydrocarbon is butadiene or substituted butadiene. 9. 9. The method of claim 8, wherein the ethylenically unsaturated hydrocarbon is isogrene. 10. (α) contacting a hydrocarbon mixture containing an ethylenically unsaturated hydrocarbon with N-aminoethylpiperazine;
(b) separating the aminoethylpiperazine/hydrocarbon mixture into at least two portions, one of which contains aminoethylpiperazine and an ethylenically unsaturated hydrocarbon; and (C) separating the aminoethylpiperazine portion from the ethylenically unsaturated hydrocarbon. A method for separating ethylenically unsaturated hydrocarbons from a hydrocarbon mixture, characterized by separating saturated carbon and hydrogen. 11. The method of claim 10, wherein the hydrocarbon stream contains O-xylene and the ethylenically unsaturated hydrocarbon in the stream is styrene. 12, the hydrocarbon stream is α-methylstyrene, 1,2.4-
)'J Methylbenzene and H/or 1,2.3-) IJ
11. The method of claim 10, which contains methylbenzene and wherein the ethylenically unsaturated hydrocarbon is vinyltoluene. 13. Process according to claim 10, wherein the hydrocarbon stream contains n-bencune, cyclopentadiene and/or impentane and the ethylenically unsaturated hydrocarbon is isoprene. 14. Contacting a mixture containing at least two liquids with close boiling points with N-aminoethylpiperazine, and extractively distilling at least one of the liquids with close boiling points, and extracting from the residue a mixture containing at least two liquids with close boiling points. A method for separating liquids having close boiling points, characterized in that at least one of the liquids having a 15. A method for inhibiting the polymerization of styrene, which comprises contacting a styrene-containing stream with an N-aminoalkylpiperazine. 16, #-(aminoalkyl/I/)piperazine is N-(
10. The method according to any one of claims 1 to 9, wherein the compound is (aminoethyl)piperazine. 17. (a) A hydrocarbon mixture containing phenylacetylene and styrene having 1.1: more amino groups,
and (1) has sufficient electronegative properties to selectively separate styrene from phenylacetylene, (2) inhibit polymerization of styrene, and (3) styrene following selective separation of styrene from a hydrocarbon mixture. (b) contacting the amine/hydrocarbon mixture with a styrene-based amine, preferably a diamine, having a boiling point sufficiently different from that of styrene to allow separation of the styrene-based amine; A process for the separation of styrene from phenylacetylene, characterized in that it is separated into at least two parts, one of which contains a major amount of a phenylacetylene-containing amine. 18. The method of claim 17, wherein the amine is N-aminoalkylpiperazine. 19. The method according to claim 18, wherein the aminoalkylpiperazine is N-aminoethylpiperazine. In addition, the separated styrene has a purity greater than 99.5% and an APHA color as low as 5J.
The method described in section.