JP3991650B2 - Method for simultaneous production of norbornene and tetracyclododecene - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to a reactor, and the reaction is continuously heated in the reactor to form norbornene and tetracyclododecene. The present invention relates to a continuous simultaneous production method of cyclododecene.
[0002]
[Prior art]
As a resin material excellent in optical characteristics, transparency, heat resistance, low hygroscopicity, electrical characteristics, and the like, cyclic olefin-based resins have attracted attention. As the cyclic olefin-based resin, a ring-opening polymer of a norbornene-based monomer, a hydrogenated product of the ring-opening polymer, an addition polymer, an addition copolymer with ethylene, and the like are known. Norbornene and tetracyclododecene are typical norbornene-based monomers.
[0003]
Norbornene can be synthesized by reacting ethylene and cyclopentadiene with heat. Tetracyclododecene can be synthesized by heating and reacting norbornene and cyclopentadiene. These reactions are generally called Diels-Alder reactions. Instead of cyclopentadiene, the dimer dicyclopentadiene can be used. Dicyclopentadiene is easily pyrolyzed to cyclopentadiene under heating reaction conditions.
[0004]
By carrying out the two reactions collectively, norbornene and tetracyclododecene can be produced simultaneously. Specifically, ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene were continuously supplied to the reactor, and heated and reacted in the reactor to generate norbornene and tetracyclododecene. By circulating at least a part of norbornene through the reactor, norbornene and tetracyclododecene can be produced simultaneously and continuously.
[0005]
At the beginning of the reaction, pre-synthesized norbornene is supplied to the reactor. In the subsequent continuous reaction, at least a part of norbornene generated by the reaction of ethylene and cyclopentadiene is circulated to the reactor, thereby allowing external reaction. Can produce norbornene and tetracyclododecene at a desired ratio simply by continuously supplying ethylene and cyclopentadiene and / or dicyclopentadiene. In the above reaction, unreacted ethylene can also be circulated to the reactor.
[0006]
Japanese Patent Publication No. 1-60011 discloses a process in which an olefin having 2 to 22 carbon atoms, cyclopentadiene or dicyclopentadiene, and norbornene are heated in a reactor, and a part of norbornene is recycled to the reactor. A process for producing a product mixture comprising norbornene and tetracyclododecene containing has been proposed. When an olefin having 3 or more carbon atoms is used instead of ethylene, substituted norbornenes and substituted tetracyclododecenes having an alkyl group or an alkylene group are formed.
[0007]
However, norbornene (that is, unsubstituted “2-norbornene”) has a high freezing point (melting point = 44 to 44.5 ° C.) and a small difference from the boiling point (94 to 97 ° C. at 98.5 kPa). When norbornene is separated from the reaction mixture by distillation, there is a problem that norbornene is easily solidified in a condenser at the top of the distillation column. Norbornene is also prone to solidification in the circulation line.
[0008]
Japanese Patent Laid-Open No. 4-9340 discloses cyclopentadiene and / or dicyclopentadiene and an olefin compound in order to prevent the occurrence of obstruction such as blockage in the reaction apparatus due to precipitation or adhesion of by-products. In a method for producing a tetracyclododecene derivative having a polar group by an alder-type thermal addition reaction, a method for supplying a norbornene derivative having a polar group to be produced as an intermediate product to a reaction system has been proposed. However, this method is complicated and is limited to a method for producing tetracyclododecene having a polar group. Substituted norbornenes are generally liquid at room temperature, so there is no risk of clogging due to solidification.
[0009]
In order to solve the norbornene solidification problem, several methods have been proposed in which a solvent is added to the raw material to prevent solidification in the condenser of the distillation column during the separation of norbornene.
[0010]
Japanese Patent No. 290481 (JP-A-3-128333) discloses a reaction containing tetracyclododecene by reacting a mixture of ethylene, cyclopentadiene or dicyclopentadiene and norbornene with an aromatic solvent by heating. A method has been proposed in which the product is recovered from the bottom of the first purification tower, and unreacted norbornene and cyclopentadiene or dicyclopentadiene are recovered together with an aromatic solvent from the top of the tower and recycled. Japanese Patent Laid-Open No. 2000-26327 proposes a method using an aliphatic solvent instead of an aromatic solvent in the above method.
[0011]
JP-A-2001-139500 discloses that ethylene, crude cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to a reactor together with a hydrocarbon solvent having a boiling point of 50 to 180 ° C. Subsequently, a method for simultaneous production of norbornene and tetracyclododecene is disclosed, which includes a step of separating ethylene and then separating a fraction containing norbornene and a solvent and circulating it to a reactor. This publication describes that the separated ethylene can be reused as a raw material.
[0012]
Japanese Patent Application Laid-Open No. 2001-139502 also discloses a method of using a solvent having a boiling point of 50 to 180 ° C. in order to prevent solidification of circulating norbornene when 2-norbornene is used. The publication proposes a method of separating unreacted olefins such as ethylene from the reaction mixture and circulating at least a part thereof into the reactor.
[0013]
According to the above method using a solvent, the problem of solidification of circulating norbornene can be reduced. However, the method of mixing and reacting a raw material comprising ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene has the following problems.
[0014]
First, when a solvent is added to the raw material, the reaction rate is lowered and the batch size is reduced as compared with the reaction using only the raw material, and the productivity is lowered. Second, unreacted ethylene separated from the reaction mixture can be introduced into an ethylene tank using a compressor and reused as a raw material, but norbornene contained in ethylene is liquid condensed in the compressor. Then the problem of solidification occurs.
[0015]
[Problems to be solved by the invention]
An object of the present invention is to prevent a decrease in productivity due to the addition of a solvent to a raw material in a simultaneous production process of norbornene and tetracyclododecene including a circulation step of unreacted ethylene and norbornene, and after the reaction step An object of the present invention is to provide a method for simultaneous production of norbornene and tetracyclododecene, which can prevent liquid coagulation in the recovery step of unreacted ethylene and norbornene and the accompanying blockage of the apparatus.
[0016]
As a result of diligent research to solve the above problems, the present inventors have carried out a continuous heating reaction by charging only the raw material into the reactor without using a solvent in the raw material charging stage, and ( ii) In the step of recovering unreacted ethylene after the reaction step, ethylene is contacted with a solvent to remove norbornene contained in ethylene, and (iii) the solvent after contact with ethylene is mixed with the liquid reaction mixture, Then, a mixed solution of norbornene and a solvent was separated from the mixture, and (iv) the norbornene and the solvent were separated from the mixed solution, and at least a part of the separated norbornene was circulated to the reactor while heating. The separated solvent can be recycled to the contact step with unreacted ethylene.
[0017]
According to the method of the present invention, a raw material composed of ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene is continuously supplied to the reactor without adding a solvent, and the heating reaction is continuously performed in the reactor. Therefore, productivity is not reduced. Moreover, since the unreacted ethylene is brought into contact with the solvent and norbornene is absorbed by the solvent, coagulation due to liquid condensation of norbornene in the ethylene recovery step is prevented.
[0018]
Since the liquid reaction product mixed with the solvent is distilled to separate the mixed solution of norbornene and the solvent, the solidification of norbornene in the condenser of the distillation tower can be suppressed. By heating the norbornene circulation line, it is possible to prevent the norbornene from solidifying in the circulation line. The present invention has been completed based on these findings.
[0019]
[Means for Solving the Problems]
Thus, according to the present invention, ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to the reactor, and are continuously heated and reacted in the reactor to form norbornene and tetracyclododecene. In the method for simultaneously producing norbornene and tetracyclododecene,
(1) Step 1, in which ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to the reactor, and are continuously heated and reacted in the reactor.
(2) The reaction mixture obtained in step 1 is continuously gas-liquid separated, and the separated ethylene is brought into contact with a solvent to transfer norbornene contained in ethylene into the solvent to be separated; and Mixing the solvent after contact with ethylene with the liquid reaction mixture, step 2,
(3) After step 2, recovering ethylene brought into contact with the solvent and circulating it to the reactor 3,
(4) Step 4 of separating the fraction containing norbornene and the solvent and the other fraction from the liquid reaction mixture in which the solvent is mixed after Step 2.
(5) Step 5 after Step 4, in which tetracyclododecene is separated and recovered from other fractions,
(6) Step 6 of separating norbornene and the solvent from the fraction containing norbornene and the solvent after Step 4.
(7) After step 6, recovering norbornene and circulating at least part of the norbornene to the reactor while heating, and
(8) After step 6, the solvent is recovered and recycled to step 2
A process for simultaneous production of norbornene and tetracyclododecene is provided.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a process flow diagram of one embodiment of the present invention. In FIG. 1, 1 indicates a cyclopentadiene and / or dicyclopentadiene tank. Cyclopentadiene can be supplied to the reactor as a raw material as it is, but usually dicyclopentadiene, which is easily available, is used. Dicyclopentadiene is thermally decomposed into a cyclopentadiene under heating reaction conditions. A mixture of cyclopentadiene and dicyclopentadiene may be used as a raw material.
[0021]
As cyclopentadiene and / or dicyclopentadiene, one having a high purity exceeding 95% by weight can be used (Japanese Patent Laid-Open No. 6-9437), but crude cyclopentadiene containing a relatively large amount of impurities and / or Alternatively, dicyclopentadiene (JP 2001-139500 A, JP 2001-139502 A) may be used.
[0022]
In FIG. 1, 2 indicates an ethylene tank. Examples of ethylene include naphtha, natural gas, ethylene obtained by steam cracking a gas fraction obtained from petroleum refining; ethylene obtained by ethane dehydrogenation or ethanol dehydration; and the like.
[0023]
Cyclopentadiene and / or dicyclopentadiene is sent from the tank 1 through the supply line 3 to the reactor 5. Ethylene is sent from the tank 2 through the supply lines 4 and 3 to the reactor 5. The transfer pump and compressor used to deliver each reactant are not shown.
[0024]
At the start of the reaction, norbornene is supplied to the reactor 5, and a separately synthesized one is used as the norbornene. In FIG. 1, the supply line of norbornene supplied at the start of the reaction is omitted. Norbornene can be synthesized by heating and reacting ethylene with cyclopentadiene and / or dicyclopentadiene. After the reaction starts, ethylene and cyclopentadiene and / or dicyclopentadiene are present in the reaction system, so norbornene is also generated under the synthesis conditions of tetracyclododecene. If the produced norbornene is used after being circulated in the reactor, it is not necessary to supply norbornene separately except at the start of the reaction.
[0025]
The supply ratio (molar ratio) of each reactant to the reactor is usually 0.5 to 20 mol, preferably 1 to 1 mol of dicyclopentadiene (cyclopentadiene is converted to dicyclopentadiene). 15 mol, and norbornene is usually 1 to 20 mol, preferably 2 to 15 mol.
[0026]
The proportion of each reactant is determined according to the desired proportion of norbornene and tetracyclododecene produced. More specifically, in a continuous process, an excess of norbornene suitable for circulation is formed and the amount of norbornene required to produce the desired proportion of tetracyclododecene upon reaction with cyclopentadiene. To determine the proportion of each reactant. Depending on the desired proportion of each reactant, the respective flow rate is controlled. The ratio of norbornene and tetracyclododecene produced is selected from the range of 5:95 to 95: 5 in molar ratio.
[0027]
Each reactant is continuously supplied to the reactor 5. Prior to feeding to the reactor 5, each reactant or a mixture thereof may be preheated as necessary. The reaction temperature in the reactor 5 is usually 100 to 400 ° C, preferably 170 to 280 ° C. The pressure is usually 1 to 50 MPa, preferably 2 to 20 MPa. The residence time is usually 0.1 to 10 hours, preferably 0.2 to 5 hours. The space velocity is usually 0.1 to 50 / h, preferably 0.5 to 20 / h.
[0028]
As the reactor, any type of reactor such as a complete mixing type or a piston flow type can be used. The reactor may be a single stage or a multistage. Two or more reactors may be used connected in series or in parallel.
[0029]
In this way, ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to the reactor, and are continuously heated and reacted in the reactor (step 1).
[0030]
The reaction mixture obtained by the reaction in the reactor 5 is continuously sent to the ethylene separation / washing tower 6, where a gaseous component mainly composed of unreacted ethylene (hereinafter referred to as “unreacted ethylene”) and , Norbornene, tetracyclododecene, dicyclopentadiene and the like liquid components (hereinafter referred to as “liquid reaction mixture”).
[0031]
The ethylene separation / washing tower 6 typically gas-liquid-separates the reaction mixture sent from the reactor 5 by flashing, and contacts the separated unreacted ethylene with a solvent with a scrubber at the top of the tower. In this case, norbornene contained in the unreacted ethylene is absorbed by the solvent, and the unreacted ethylene is washed. At the same time, in the ethylene separation / washing tower 6, the solvent after washing is mixed with the liquid reaction mixture. The ethylene separation / washing tower 6 is a facility for continuously performing the above series of steps.
[0032]
In order to perform gas-liquid separation in the ethylene separation / washing tower 6, the pressure in the ethylene separation / washing tower 6 is made lower than the pressure in the reactor 5 before the reaction mixture is fed to provide a differential pressure. The pressure difference is preferably 2 to 50 MPa, more preferably 5 to 20 MPa. In this way, the reaction mixture obtained in step 1 is separated into gas and liquid and separated into unreacted ethylene and a liquid reaction mixture.
[0033]
The separated unreacted ethylene contains a small amount of norbornene and may contain a very small amount of cyclopentadiene, dicyclopentadiene, tetracyclododecene, and the like. When norbornene is contained in ethylene by about several percent by weight, norbornene is easily solidified in the ethylene recovery line during the continuous reaction.
[0034]
The unreacted ethylene subjected to gas-liquid separation is brought into contact with a solvent, and norbornene contained therein is absorbed in the solvent and washed. When ethylene contains cyclopentadiene, dicyclopentadiene, and tetracyclododecene, these are also absorbed in the solvent. In FIG. 1, the solvent supply line is omitted.
[0035]
It is desirable to employ a method in which a scrubber is disposed in the upper part of the ethylene separation / washing tower 6 and unreacted ethylene is passed through the scrubber and then brought into contact with a solvent. A scrubber is an absorption device of a type in which liquid is dispersed in gas as fine droplets or liquid film pieces. It is preferable to employ a method in which a solvent is sprayed and brought into contact with unreacted ethylene rising in the column using a cyclone scrubber or a venturi scrubber.
[0036]
Solvents include aromatic solvents such as xylene, benzene and toluene; alicyclic solvents such as ethylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane and dimethylcyclohexane; 3-ethylpentane and 2,3-dimethylpentane. , 3,3-dimethylpentane, 2,2,4-trimethylpentane, isohexane, isoheptane and other aliphatic solvents; Among these, aromatic solvents are preferable, and xylene is more preferable. As xylene, o-xylene, m-xylene, p-xylene, and a mixture thereof can be used.
[0037]
The amount of the solvent used is not particularly limited, but it is used in such an amount that the content of norbornene contained in the unreacted ethylene is usually reduced to 1% by weight or less, preferably 0.7% by weight or less. The solvent flow rate is 99% by weight or more, preferably 99.3% by weight or more, and particularly preferably 99% by weight or more, depending on the flow rate of unreacted ethylene introduced into the ethylene separation / washing tower 6 and the norbornene content in ethylene. It is desirable to adjust so that high purity ethylene of 5% by weight or more is recovered.
[0038]
It is desirable to control the flow rate so that the amount of the solvent is preferably 1 to 50% by weight, more preferably 5 to 30% by weight, based on the reaction mixture. If the amount of the solvent is too small, norbornene contained in the unreacted ethylene cannot be sufficiently absorbed, and the ethylene recovery line or the like is likely to be clogged. When the amount of the solvent is too large, productivity is lowered.
[0039]
A liquid reaction mixture separated from the unreacted ethylene and gas and liquid is guided to the lower part of the ethylene separation and washing tower 6. The solvent after making it contact with unreacted ethylene in the tower upper part falls, and a solvent and a liquid reaction mixture are mixed there.
[0040]
The temperature condition of the ethylene separation and washing tower 6 is preferably 50 to 200 ° C., more preferably 100 to 170 ° C. at the bottom, and preferably 0 to 70 ° C., more preferably 20 to 50 ° C. at the top. If the temperature at the bottom of the column is too high, the reaction proceeds and the composition of the liquid reaction mixture varies. If the temperature at the top of the column is too high, solvent vapor may enter the ethylene recovery line 7 and liquid condense in the line, causing clogging. If the temperature at the top of the column is too low, the absorption rate of norbornene by the solvent may decrease, or the liquid reaction mixture may solidify when the solvent is mixed with the liquid reaction mixture.
[0041]
In this way, the unreacted ethylene that has been gas-liquid separated is brought into contact with the solvent, norbornene contained in the ethylene is absorbed into the solvent and washed, and the solvent after being brought into contact with the unreacted ethylene is liquid. Mixed with the reaction mixture (step 2).
[0042]
After step 2, ethylene purified by washing is transferred from the top of the ethylene separation and washing tower 6 to the ethylene tank 2 through the ethylene recovery line 7 and circulated to the reactor 5. A compressor is used to transfer ethylene, but the compressor is omitted in FIG. From the ethylene tank 2, the recovered ethylene and new ethylene are sent to the reactor 5 so that the total amount becomes a predetermined amount. In this way, the recovered ethylene is circulated to the reactor (step 3).
[0043]
From the bottom of the ethylene separation / washing tower 6, the liquid reaction mixture mixed with the solvent is transferred to the first purification tower 8. In the first purification column 8, a mixed solution containing the solvent and the liquid reaction mixture is distilled, and a fraction containing norbornene, cyclopentadiene, dicyclopentadiene, and the solvent is distilled from the top of the column. The fraction distilled from the top of the first purification column 8 is mainly composed of norbornene and a solvent, but in addition, it is desirable to distill a component having a molecular weight of 140 or less.
[0044]
The distillation conditions in the first purification column 8 are such that the column bottom pressure is preferably 1 to 40 kPa, more preferably 10 to 20 kPa, and the column bottom temperature is preferably 80 to 190 ° C, more preferably 120 to 170 ° C. . The tower top pressure is preferably 1 to 40 kPa, more preferably 10 to 20 kPa, and the tower top temperature is preferably 10 to 170 ° C, more preferably 40 to 80 ° C. Other fractions other than the fraction distilled from the top of the column remain at the bottom of the first purification column 8. Thus, after step 2, the fraction containing norbornene and the solvent and the other fraction are separated from the liquid reaction mixture in which the solvent is mixed (step 4).
[0045]
The fraction from the bottom of the first purification column 8 is transferred to the second purification column 9. In the second purification column 9, distillation is performed, and a tetracyclododecene fraction is extracted from the top of the column. From the bottom of the column, heavy components such as cyclopentadiene trimer to which cyclopentadiene is added by Diels-Alder reaction are extracted.
[0046]
The operating conditions of the second purification tower 9 are such that the tower bottom temperature is preferably 80 to 190 ° C., more preferably 120 to 170 ° C., and the tower bottom pressure is preferably 0.05 to 20 kPa, more preferably 0.1 to 0.1. 5 kPa. The tower top temperature is preferably 10 to 150 ° C., more preferably 60 to 100 ° C., and the tower top pressure is preferably 0.05 to 20 kPa, more preferably 0.1 to 5 kPa. Thus, after Step 4, tetracyclododecene is separated and recovered from other fractions (column bottom components) (Step 5).
[0047]
On the other hand, a fraction containing norbornene and a solvent is transferred to the third purification tower 10 from the top of the first purification tower 8. In the third purification tower 10, distillation is performed, and norbornene is separated and recovered from the top of the tower, and the solvent is separated and recovered from the middle of the tower.
[0048]
The operating conditions of the third purification tower 10 are such that the tower top temperature is preferably 10 to 150 ° C., more preferably 30 to 70 ° C., and the tower top pressure is preferably 5 to 50 kPa, more preferably 20 to 35 kPa. The tower bottom temperature is preferably 60 to 170 ° C, more preferably 100 to 150 ° C, and the tower bottom pressure is preferably 5 to 50 kPa, more preferably 20 to 35 kPa. Thus, after Step 4, norbornene and the solvent are separated from the fraction containing norbornene and the solvent (Step 6).
[0049]
At least a part of norbornene recovered from the top of the third purification column 10 is circulated to the reactor 5 through the norbornene circulation line 11. The remaining norbornene is extracted from the top of the third purification column 10 to the outside of the reaction system. The norbornene circulation line 11 is partially or wholly heated so that the norbornene does not solidify in the line 11. The temperature of the circulation line 11 is preferably adjusted to 30 to 97 ° C, more preferably 35 to 60 ° C. The circulation line 11 can be heated, for example, by passing a heating medium such as warm water through a jacket (not shown) disposed thereon. The recovered norbornene contains a small amount of cyclopentadiene, but is reused as a raw material together with norbornene. In this way, after step 6, norbornene is recovered and at least part of it is circulated to the reactor while heating (step 7).
[0050]
The solvent recovered from the middle part of the third purification column 10 is circulated through the solvent circulation line 12 to the top of the ethylene separation / washing tower 6 where it is brought into contact with unreacted ethylene. If the amount of solvent recovered is reduced due to loss, add the same amount of solvent as lost. The addition of the solvent is performed from a solvent supply line (not shown). Thus, after step 6, the solvent is recovered and recycled to step 2 (step 8). Unreacted dicyclopentadiene is extracted from the bottom of the third purification column 10.
[0051]
Although the manufacturing method of the present invention includes the above steps 1 to 8, additional steps and equipment may exist as necessary. For example, heating equipment can be installed in the piping from the ethylene separation and cleaning tower 6 to the first purification tower 8, the piping from the first purification tower 8 to the third purification tower 10, and the like. By installing such heating equipment, solidification of the reaction mixture can be more effectively prevented. The heating condition is preferably 10 to 90 ° C, more preferably 20 to 70 ° C. Moreover, you may add antioxidant, a polymerization inhibitor, etc. in a reaction material (raw material).
[0052]
According to the production method of the present invention, there is no change in the recovered ethylene flow rate and the recovered norbornene flow rate even during continuous operation for 1000 hours or longer, or even 5000 hours or longer, and the compressor is not stopped or the circulation line is not blocked. Further, according to the present invention, the conversion rate of dicyclopentadiene is usually 70 to 100%, preferably 90 to 100%, and the total yield of tetracyclododecene and norbornene after purification is usually 50 to 100%, Preferably, 80 to 100% (based on charged dicyclopentadiene) can be achieved.
[0053]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following Examples and Comparative Examples,% is based on weight unless otherwise specified.
[0054]
[Example 1]
<Step 1>
A mixed liquid (DCP / NB = 1/8 molar ratio) of dicyclopentadiene (DCP) from the dicyclopentadiene tank 1 and norbornene (NB) from a norbornene supply line (not shown) is supplied to the reactor 5. On the way, 149 NM of ethylene (Et) from the ethylene tank 2 ^Three The raw material mixture composition was adjusted to DCP / NB / Et (1/8/4 molar ratio) by contacting with the mixture solution at a rate of / h. This raw material mixture was continuously fed into the reactor 5 having a capacity of 200 L at a flow rate of 400 kg / h. In the reactor 5, the heating reaction was continuously carried out under the operating conditions of a residence time of 30 minutes, a reaction temperature of 210 ° C., and a reaction pressure of 7 MPa.
[0055]
<Step 2>
The reaction mixture was sent from the reactor 5 to the ethylene separation and washing tower 6 and separated into a gas component and a liquid component. After gas-liquid separation, the composition of the gas component (unreacted ethylene) is 95.5% for Et, 0.2% for cyclopentadiene (CPD), 4.0% for NB, and 0 for tetracyclododecene (TCD). 3%. The composition of the liquid component (liquid reaction mixture) was 0.3% CPD, 0.6% DCP, 7.4% TCD, 89.9% NB, and 0.5% heavy component. It was.
[0056]
A gaseous component (unreacted ethylene) is passed through a scrubber at the top of the ethylene separation and washing tower 6, in which xylene is sprayed at a flow rate of 56 L / h to come into contact with unreacted ethylene, and NB, CPD in ethylene and TCD was absorbed into xylene and the ethylene was washed. Ethylene recovered from the ethylene separation and washing tower 6 has a purity of 99.5% and a flow rate of 29 NM. ^Three / H.
[0057]
<Step 3>
The ethylene recovered from the ethylene separation / washing tower 6 was pressurized by a compressor (a booster; not shown), and returned to the ethylene tank 2 through the ethylene circulation line 7. The recovered ethylene was supplied from the ethylene tank together with additional ethylene to the reactor 5 for reuse.
[0058]
<Step 4>
At the bottom of the ethylene separation and washing tower 6, xylene after contacting with unreacted ethylene was mixed with a liquid component (liquid reaction mixture). The composition ratio of the liquid mixture at this time was 77.2% for NB, 6.4% for TCD, 0.2% for CPD, 0.5% for DCP, 0.4% for heavy components, and 14% for xylene. It was 1%.
[0059]
In order to separate TCD and NB from this mixed solution, the reaction mixed solution was transferred to the first purification tower 8. In the first purification column 8, a compound (fraction) having a molecular weight of 140 or less containing NB, CPD, DCP and xylene was separated from the top of the column, and the remaining compounds (other fractions) containing TCD were extracted from the bottom of the column. . The first purification tower 8 was operated at a tower bottom temperature of 154 ° C. and a tower bottom pressure of 17 kPa. The tower top pressure at this time was 16 kPa.
[0060]
<Step 5>
The liquid mixture (other fractions) extracted from the bottom of the first purification tower 8 was transferred to the second purification tower 9, and TCD was separated and recovered from the top of the tower in the second purification tower 9. The purity of the separated and recovered TCD was 99.2%. Heavy components recovered from the bottom of the tower were discarded.
[0061]
<Step 6>
The liquid mixture distilled from the top of the first purification tower 8 was transferred to the third purification tower 10. The third purification tower 10 was operated under the conditions of a pressure of 28 kPa and a tower bottom temperature of 125 ° C., and NB was separated and recovered from the tower top and xylene from the middle of the tower. At this time, the tower top temperature was 53 ° C., and the pressure was 27 kPa. The purity of NB separated by the third purification tower 10 was 97%, and xylene was mixed 3%. The DCP recovered from the tower bottom was discarded.
[0062]
<Step 7>
A part of the NB separated and recovered in the third purification tower 10 was returned to the reactor 5 through the norbornene circulation line 11 heated to 40 ° C. and reused as a raw material. Although some amount of CPD is contained in the recovered NB, it can be reused as a raw material together with NB.
[0063]
<Step 8>
On the other hand, xylene separated and recovered from the third purification tower 10 was returned to the top of the ethylene separation and washing tower 6 through the solvent circulation line 12 and reused as an ethylene washing solvent. Since the recovered xylene was less than the amount of xylene to be added in the ethylene separation and washing tower 6, the amount of lost xylene was added from a solvent supply line (not shown).
[0064]
<Result>
The above operation was carried out continuously for over 5,000 hours, but there was no change in the recovered ethylene flow rate, recovered norbornene flow rate, etc., and the compressor was not stopped or the norbornene circulation line was not blocked. It was conducted.
[0065]
The DCP conversion was 98.4%, the total yield of TCD and NB after purification was 85.0% (based on the charged DCPD), and the production ratio of NB / TCD was 1.34 / 1.0. . The total production rate of TCD and NB was 340 kg / h.
[0066]
[Comparative Example 1]
In Example 1, continuous operation was performed in the same manner as in Example 1 except that ethylene was separated using a distillation tower that did not perform ordinary solvent washing instead of the ethylene separation and washing tower 6. After 70 hours from the start of continuous operation, the recovered ethylene could not be circulated. When the operation was stopped and the inside of the compressor was inspected, accumulation of stuck norbornene was confirmed.
[0067]
[Comparative Example 2]
In Example 1, continuous operation was performed in the same manner as in Example 1 except that norbornene circulation line 11 was not heated and norbornene was circulated in reactor 5 while maintaining the room temperature (about 25 ° C.). After 20 hours from the start of continuous operation, the recovered norbornene circulation flow rate decreased to 120 kg / h, and after 40 hours, the circulation of norbornene was stopped and the supply of norbornene to the reactor 5 was stopped. The operation was stopped and the inside of the norbornene circulation line 11 was inspected. As a result, deposition of the adhered norbornene was confirmed.
[0068]
【The invention's effect】
According to the present invention, in the simultaneous production method of norbornene and tetracyclododecene, including a step of circulating unreacted ethylene and norbornene, it is possible to prevent a decrease in productivity due to the addition of a solvent to the raw material and Provided is a method for simultaneous production of norbornene and tetracyclododecene, which can prevent liquid coagulation in the recovery step of unreacted ethylene and norbornene and the accompanying blockage of the apparatus.
[0069]
That is, according to the production method of the present invention, it is possible to prevent coagulation of norbornene in the distillation step and the recovery step, which has been a problem in the conventional simultaneous production method of norbornene and tetracyclododecene, and to reduce the reaction rate ( No reduction in productivity).
[Brief description of the drawings]
FIG. 1 is a process flow diagram of one embodiment of a production method of the present invention.
[Explanation of symbols]
1: Cyclopentadiene / dicyclopentadiene tank
2: Ethylene tank
3: Supply line
4: Ethylene supply line
5: Reactor
6: Ethylene separation washing tower
7: Ethylene circulation line
8: First purification tower
9: Second purification tower
10: Third purification tower
11: Norbornene circulation line
12: Solvent circulation line

Claims (3)

Ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to the reactor, and are continuously heated and reacted in the reactor to form norbornene and tetracyclododecene. In the simultaneous manufacturing method,
(1) Step 1, in which ethylene, cyclopentadiene and / or dicyclopentadiene, and norbornene are continuously supplied to the reactor, and are continuously heated and reacted in the reactor.
(2) The reaction mixture obtained in step 1 is continuously gas-liquid separated, and the separated ethylene is brought into contact with a solvent to transfer norbornene contained in ethylene into the solvent to be separated; and Mixing the solvent after contact with ethylene with the liquid reaction mixture, step 2,
(3) After step 2, recovering ethylene brought into contact with the solvent and circulating it to the reactor 3,
(4) Step 4 of separating the fraction containing norbornene and the solvent and the other fraction from the liquid reaction mixture in which the solvent is mixed after Step 2.
(5) Step 5 after Step 4, in which tetracyclododecene is separated and recovered from other fractions,
(6) Step 6 of separating norbornene and the solvent from the fraction containing norbornene and the solvent after Step 4.
(7) After step 6, norbornene is recovered and at least a part of the norbornene is heated and circulated to the reactor, and (8) after step 6, the solvent is recovered and circulated to step 2. Step 8
A process for simultaneously producing norbornene and tetracyclododecene, comprising the steps of: The production method according to claim 1, wherein, in the step 2, unreacted ethylene which has undergone gas-liquid separation is introduced into an absorption tower provided with a scrubber, and ethylene is passed through a scrubber at the top of the absorption tower, and in that case, contacted with a solvent. The process according to claim 1, wherein, in the step 7, the temperature of the line for circulating norbornene to the reactor is adjusted to 30 to 97 ° C and the norbornene is circulated to the reactor while heating.

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