JPS62123138A - Method for separating and recovering cyclopentadiene - Google Patents

Abstract

PURPOSE:To separate and to recover the titled compound from a specific by- product cracked petroleum advantageously, by separating <=5C fraction from >=9C fraction under dimerization condition of the titled compound and under cracking condition of the titled compound by distillation and separating 6C-8C fraction by distillation. CONSTITUTION:A by-product cracked petroleum 11 containing >=5C fraction prepared as a by-product in production of olefins by thermal cracking of liquid hydrocarbon is fed to a first distillation column 1 and distilled at <=150 deg.C bottom temperature of the column to give <=5C fraction 12 from the top of the column and >=6C fraction 13 from the bottom of the column. Then, the >=6C fraction is fed to a second distillation column 2 and distilled at >=160 deg.C bottom temperature of the column to give >=9C fraction 15 from the bottom of the column and a distillate solution 14 containing the titled compound and 6-8C fraction from the top of the column. The distillate solution is further distilled by a third distillation column 3 to give 6-8C fraction 17 from the bottom of the column and the titled high-purity compound useful as a raw material for synthetic resin, agricultural chemicals, drugs, etc., from the top of the column by relatively simple operations and efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for separating and recovering cyclopentadiene. Specifically, the present invention is directed to by-product cracked oil (also referred to as by-product cracked gasoline) containing a fraction of 05 or higher, which is produced as a by-product when olefins are produced by thermally decomposing liquid hydrocarbons 1, such as naphtha.

) relates to a method for separating and recovering cyclopentadiene from

[Conventional technology]

Cyclopentadiene is useful as a raw material for synthetic resins, agricultural chemicals, medicines, etc. Cyclopentadiene is found in the low-boiling fraction of coal tar, coke oven gas, and is known to be produced during hydrocarbon cranking.

As a method for selectively recovering cyclopentadiene from these sources, for example, 04 or lower hydrocarbon fractions are separated by distillation from the thermal decomposition products produced when olefins are produced by thermally decomposing naphtha. The following method has been proposed in which a C5 fraction is separated by distillation from the remaining 05 or higher fraction (cracked gasoline) and cyclopentadiene is separated and recovered from the C5 fraction.

■ A method of dimerizing cyclopentadiene in the C5 fraction and separating it by distillation I (U.S. Patent No. 2.7 (74t,
77/No. and 2,707.7/6), ■ C5
The above fractions are passed through a distillation column by raising the temperature of the column, preventing dimerization at the bottom of the column, and taking out a fraction of 0.05 or less from the top of the column. (see U.S. Patent Nos. 2.733-, !73, 2.W33.J-3 and Co, /≦7.t70), A method of distilling, decomposing, and then distilling (U.S. Pat. Nos. 2 and 7)
j 3. ．． (see Japanese Patent Publication No. 4-373341); (1) a method of dimerizing cyclopentadiene in the C5 fraction, distilling it, decomposing it, dimerizing it, and then distilling it first (see Japanese Patent Publication No. Sho G4-373341);

[Problem that the invention seeks to solve]

However, in the method (2) above, there is a problem in that the codimer of cyclopentadiene and other dienes, such as imbrene, and dicyclopentadiene have similar boiling points and are difficult to separate. In addition, in method (1) above, dimerization at the bottom of the distillation column can be prevented, but there is a temperature range between the top and the bottom that promotes dimerization (about 70~/4t There is no way to prevent the existence of cyclopentadiene (temperature range of The disadvantage is that it is difficult to separate it from the molecule. Also.

In the method (2) above, since the decomposed cyclopentadiene is passed through a distillation column, dimerization occurs in the column, resulting in a lower recovery rate and a decrease in the purity of the obtained cyclopentadiene! ~6% by weight, which poses a problem in that high purity cannot be obtained. Furthermore, in method ■ above, cotton weight%
Dicyclopentadiene with a high degree of purity can be obtained, but 8
Since the printing process is complicated, the operation is complicated, and the cost is high, so it cannot be said to be industrially advantageous.

[Means for solving problems]

In view of the conventional separation and recovery technology for cyclopentadiene described above, the present inventors have conducted extensive studies on a method for separating and recovering cyclopentadiene from thermal decomposition products of hydrocarbon oil with high purity and in an industrially advantageous manner. As a result, it was found that cyclopentadiene could be easily separated and recovered from the C5 fraction remaining after separating the C5 fraction from the thermal decomposition product. That is, after separating the C4 or lower hydrocarbon fraction from the thermal decomposition product, the remaining C4 or higher fraction is distilled under conditions that promote preferential dimerization of cyclopentadiene. Distill and separate the C5 fraction to obtain one bottom liquid (
aS or higher fraction) Distillation is carried out under conditions in which cyclopentadiene is preferentially decomposed into cyclopentadiene to distill a fraction containing cyclopentadiene and 06 to C8 fractions, and this is converted into cyclopentadiene. The present invention was achieved by discovering that a fraction consisting of cyclopentadiene with high purity at the top of the column can be obtained by distilling under conditions that separate the 06-C8 fraction and the 06-C8 fraction.

That is, (1) the gist of the present invention is to separate and recover cyclopentadiene from a by-product cracked oil containing a fraction of 05 or higher, which is produced when producing olefins by thermally decomposing liquid hydrocarbon oil; The by-product cracked oil is supplied to the first distillation column, and the distillation column is heated to a bottom temperature of /! operating under distillation conditions of θ°C or below; (1) distilling a distillate containing a fraction of 05 or less from the top of the first distillation column, while distilling a distillate containing a fraction of 06 or less from the bottom of the column; Obtaining a bottoms containing the above fractions and supplying it to a first distillation column; ■ Operating the second distillation column under distillation conditions with a bottom temperature of 760° C. or higher; ■ The second distillation column. A bottoms containing 09 and above fractions is discharged from the bottom of the distillation column, while a distillate containing cyclopentadiene and 06 to C8 fractions is obtained from the top of the column, and is added to the third column.
and (i) supplying cyclopentadiene and 06 in the third distillation column.
-C8 fractions are distilled and separated, and a distillate consisting of purified cyclopentadiene is distilled out from the top of the column, while a bottoms consisting of C6-C8 fractions is obtained from the bottom of the column.

A method for separating and recovering cyclopentadiene.

exists in

Hereinafter, the present invention will be explained in detail.

The present invention uses liquid hydrocarbon oil 1, for example, from a by-product cracked oil (cracked gasoline) containing a fraction of 05 or higher, which is produced when producing olefins by thermally decomposing petroleum fractions such as naphtha and kerosene. This is to separate and recover pentagene.

In the present invention, cyclopentadiene contained in the by-product cracked oil containing the C5 or higher fraction is separated and recovered by a combination of distillation conditions including three-stage distillation.

First, the by-product cracked oil is supplied to the first distillation column, and the distillation column is heated to a bottom temperature of /! Operating under conditions of θ°C or lower, fractions of 0.5 or lower, such as isoprene and cyclopentadiene, are distilled from the top of the column, while fractions of 0.6 or higher, including dicyclopentadiene, are distilled from the bottom of the column. Drain the liquid. The first distillation column is operated under temperature conditions where cyclopentadiene is preferentially dimerized to dicyclopentadiene, and under conditions where C5 and C6 fractions can be separated by distillation. 20
Using a distillation column with more than one plate, the bottom temperature can be adjusted to /! The operation is carried out at θ°C or lower, preferably in the range of 700 to 0°C, and with the tower top pressure in the range of reduced pressure to increased pressure. If the bottom temperature exceeds 710° C., on the contrary, the decomposition reaction of dicyclopentadiene to cyclopentadiene occurs preferentially, resulting in a decrease in the recovery rate of cyclopentadiene, which is not preferable.

The bottoms of the first distillation column are then supplied to a second distillation column,
The distillation column is operated at a bottom temperature of 0° C. or higher, and a fraction containing cyclopentadiene and 06 to C8 fractions is distilled from the top of the column, while a fraction of 09 and above is distilled from the bottom of the column. The bottom liquid containing .

The second distillation column is operated under temperature conditions where dicyclopentadiene is preferentially decomposed into cyclopentadiene, and under conditions where a C8 fraction and a C9 fraction can be separated by distillation.1 Usually,
Using a distillation column with the number of theoretical plates of 2Q or more, the bottom temperature of the column should be 72.
The operation is carried out at a temperature of 0° C. or higher, preferably in the range of 770 to 220° C., and with the tower top pressure within the range of slightly reduced pressure to ten thousand mouths pressure.

If the bottom temperature of the column is less than 760°C, the decomposition reaction of dicyclopentadiene to cyclopentadiene is slow and the recovery rate of cyclopentadiene is significantly reduced, which is not preferable.

Conventionally, the distillate from the second distillation column is hydrogenated to convert cyclopentadiene into cyclopentadiene.

This is recovered as a raffinate, but in the method of the present invention, the distillate is fed to the third distillation column I, and cyclopentadiene is separated and recovered by distillation.

That is, high-purity cyclopentadiene is distilled from the top of the distillation column, and a6-Os fraction is obtained from the bottom of the column.
Bottoms containing mainly aromatic hydrocarbons such as benzene, toluene and hxylene is extracted. The bottom liquor is then subjected to hydrogenation treatment.

Aromatic hydrocarbon components are separated and recovered.

The third distillation column is operated under distillation conditions that allow separation of cyclopentadiene and the C6 fraction.1 Usually, a distillation column with 20 or more theoretical plates is used, and the bottom temperature is maintained within the range of /θ to ZO°C. , the tower top temperature is 30~! Operation is performed within the θ°C range.

FIG. 1 is a process diagram showing an example of a specific configuration of the method of the present invention in a mock contract. In the figure, (1) is a first distillation column, (2) is a second distillation column, and (3) is a third distillation column.

In addition, 0°C is a by-product cracked oil supply pipe, (6) is a first distillation column distillate extraction pipe, C1 is a first distillation column bottoms extraction pipe, α◆ is a second distillation column distillate extraction pipe, (g) represents the first distillation column distillate extraction pipe, αQ represents the third distillation column distillate (cyclopentadiene fraction) extraction pipe, and α represents the 3M distillation column bottoms extraction pipe, respectively.

〔Example〕

Next, specific embodiments of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example/04 from the pyrolysis product obtained by pyrolysis of naphtha
By-product cracked oil (shiku a) obtained by distilling and separating the following fractions
Pentadiene≦, 3ti, dicyclopentadiene, /%
Cyclopentadiene was separated and recovered from the 05-C9 hydrocarbons (containing 05-C9 hydrocarbons) by the distillation process shown in FIG.

That is, the by-product cracked oil is supplied to the first distillation column (theoretical plate number: 30) which is operated at the bottom temperature/0°C, normal pressure, and reflux ratio λ, and from the bottom of the column, the bottoms (cyclo Extract C6-C9 hydrocarbons including pentadiene theta, dicyclopentadienta, and 4t. The bottoms are supplied to the λ-th distillation column (theoretical plate number = 30) operated at a bottom temperature of 790°C, normal pressure, and a reflux ratio of 0.1, and from the top of the column, the distillate (cyclopentadiene≦ "'L 06~ containing dicyclopentadiene θ%
CB hydrocarbon) was extracted. The distillate is heated to the bottom temperature θ
The mixture was supplied to a third distillation column (theoretical plate number: 30) operated at a temperature of 0.degree. C., a pressure, and a reflux ratio of 20, and the distillate was extracted from the top of the column. Please note that the composition of the distillate is as follows.

Cyclopentagenta! ,! Polydicyclopentadiene 0. ♂% Cyclopentane 0.7% Cyclopentene 0.2% Methylpentane 0.7% Pentane-Isoprene 0.2% Cyclopentadiene easily changes to dicyclopentadiene even at room temperature. Therefore, in terms of dicyclopentadiene, we obtained 3% pig.

〔Effect of the invention〕

By the method of the present invention, highly pure cyclopentadiene can be efficiently separated and recovered from by-product cracked oil with relatively simple operations.

[Brief explanation of drawings]

FIG. 1 is a process diagram schematically showing an example of a specific configuration of the method of the present invention. /: seventh distillation column, , 2: second distillation column, 3: third distillation column. //: By-product cracked oil supply pipe, 7: Nidiclopentadiene distillate extraction pipe. Patent applicant Mitsubishi Chemical Industries, Ltd. Agent Patent attorney Necessity - 7 others Rei 1 Mi

Claims (1)

[Claims] (1) In separating and recovering cyclopentadiene from by-product cracked oil containing a C_5 or higher fraction, which is a by-product when producing olefins by thermally decomposing liquid hydrocarbon oil, [1] The by-product supplying the cracked oil to a first distillation column, and operating the distillation column under distillation conditions with a bottom temperature of 150°C or less; [2] containing a fraction of C_5 or less from the top of the first distillation column; Distilling the distillate, on the other hand, obtaining a bottoms containing a C_6 or higher fraction containing dicyclopentadiene from the bottom of the column, and supplying it to a second distillation column, [3] the second distillation The column is operated under distillation conditions with a bottom temperature of 160° C. or higher; [4] Bottoms containing a C_9 or higher fraction are discharged from the bottom of the second distillation column; Obtaining a distillate containing cyclopentadiene and C_6 to C_8 fractions and supplying it to a third distillation column, and [5] In the third distillation column, cyclopentadiene and C
It is characterized by distilling and separating the _6 to C_8 fractions, distilling and obtaining a distillate consisting of purified cyclopentadiene from the top of the column, and obtaining a bottoms consisting of C_6 to C_8 fractions from the bottom of the column. Separation and recovery method for cyclopentadiene.