JPS60116634A - Preparation of cyclopentadiene - Google Patents

Abstract

PURPOSE:To evaporate the desired substance, to recover it, and to remove residues in the system out of the system, by feeding successively a mixture of liquid dicyclopentadiene and a heavy inert oil to a liquid level of a heavy inert oil heated to a specific temperature so that dicyclopentadiene is decomposed into cyclopentadiene. CONSTITUTION:The horizontal thermal cracking device 1 is charged with the heavey inert oil 2, and heated to 200-300 deg.C (preferably to 220-280 deg.C). A mixture of dicylopentadiene from the pipe 3 and a heavy inert oil from the pipe 4 is successively fed to the liquid level of the device by the feed pump 5. Undecomposed dicyclopentadiene in instantly decomposed cyclopentadiene is condensed by the partial condenser at 10-90 deg.C, the distillate is introduced into the total condenser 7, and the desired substance in liquid is obtained from the outlet 8. EFFECT:A thermal cracking device will not cause clogging without setting a vaporizer even if the device is a simple one and it is operated for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously producing cyclopentadiene by thermally decomposing liquid dicyclopentadiene.

Conventionally, it has been known to supply liquid dicyclopentadiene as it is to a thermal decomposer to produce cyclopentadiene.

However, in this method, the interior of the thermal decomposer is clogged in a relatively short period of time due to the polymers generated by thermal polymerization of the raw material dicyclopentadiene and the thermal decomposition products such as cyclopentadiene, and the thermal decomposition operation continues. There was a serious drawback that it was impossible to do so.

Therefore, as an improvement method, a method has been proposed in which the raw material is vaporized in advance before the thermal decomposer and gaseous dicyclopentadiene is supplied to the thermal decomposer (for example, U.S. Pat. No. 2,801,277
(See No. 0 and Specification No. 3772396).

However, in this method, an extremely large amount of thermal polymerization products are produced as by-products in the evaporator during heating and vaporization, thereby clogging the evaporator. In order to prevent this, it is necessary to discharge the liquid containing the thermal polymer while the concentration of the thermal polymer is low.Therefore, this method does not cause problems such as blockage of the evaporator and large loss of raw materials. It's hard to avoid.

In addition, dicyclopentadiene and heavy inert hydrocarbons are supplied as raw materials to a distillation column, and while the heavy inert hydrocarbons are removed from the bottom of the column, gaseous dicyclopentadiene is recovered from the top of the column. A method has also been proposed in which cyclopentadiene is obtained by cooling, storing it in a drum, vaporizing it, and supplying it to a pyrolysis heater (Japanese Patent Application Laid-open No. 153727/1983). However, with this method, it is necessary to install a new evaporator along with the pyrolyzer, and when including incidental equipment, the entire device becomes large-scale, and when considering the cost including the construction cost, it is not necessarily economical. It is difficult to say that it is a politically effective method.

The present invention solves the above-mentioned drawbacks of the prior art, does not cause clogging of the pyrolyzer by thermal polymers, and uses an extremely simple device.
The object of the present invention is to provide a method that can economically produce cyclopentadiene with high purity.

That is, the present invention continuously supplies a mixture of liquid dicyclopentadiene and heavy inert oil from above the liquid surface of heavy inert oil heated to 200 to 300'C. The present invention relates to a method for producing cyclopentadiene, which comprises decomposing it into cyclopentadiene, recovering it by evaporation, and removing the residue in the system containing the above-mentioned heavy inert oil from the system.

As the raw material dicyclopentadiene used in the present invention, in addition to commercially available dicyclopentadiene, it is also possible to use a distiller containing 70% by weight or more of dicyclopentadiene obtained by decomposition of petroleum. can. In this case, it is preferable that components having a boiling point of 90° C. or lower are not included as impurities. If it contains impurities with a boiling point of 9°C or less, they will be mixed into the liquid cyclopentadiene as impurities when the evaporated methylcyclopentadiene is cooled and recovered, for example, in a dephlegmator.Vl, cyclopentadiene This is because it causes a decrease in the purity of pentagene.

Note that dicyclopentadiene has the formula It is a compound represented by

Heavy inert oils are oils that have a boiling point of 300°C or higher and are thermally and chemically stable under the thermal decomposition conditions of raw material methyldicyclopentadiene, such as light oil produced by petroleum refining, Machine oil, spindle oil, etc., heavy aromatic oil produced as a by-product in the reforming reaction of naphtha, heavy oil produced as a by-product in the thermal decomposition of naphtha, silicone oil, etc. can be used.

When dicyclopentadiene is supplied from above the liquid surface of heavy inert oil heated to 200 to 300°C, dicyclopentadiene is cyclopentane at the same time. For example, a condenser is used. If the evaporated matter is simply coagulated and collected, undecomposed dicyclopentadiene will also be collected at the same time, reducing the purity of the obtained cyclopentadiene. Therefore, the following method is recommended: good. That is, the evaporated product is first used in a partial condenser whose temperature is adjusted to 10 to 90°C to aggregate undecomposed dicyclopentadiene, reduce it to a decomposition reaction system, and use it for the decomposition reaction. On the other hand, the cyclopentadiene that has passed through the partial condenser is recovered in the total condenser.

The mixture of dicyclopentadiene and heavy inert oil has a weight ratio of dicyclopentadiene/heavy inert oil of 4/1 to 1.
Preferably, the ratio is in the range 00/1. The heavy inert oil used here is necessary to always prevent the increase in viscosity of the residue due to thermal polymerization by-products, and if the amount is small, the increase in viscosity cannot be effectively prevented. On the other hand, if the amount is too large, the heating burden will increase and the resistance to thermal energy will increase.

The feeding rate of the mixture of dicyclopentadiene and heavy inert oil is appropriately determined depending on the scale of the equipment, etc.
5 kg/hour is preferred, particularly 2 to 3.5 kg/hour. If the supply rate is too low, the production efficiency of clopentadiene decreases, and if the supply rate is too high, the thermal decomposition efficiency of dicyclopentadiene tends to decrease.

The amount of heavy inert oil to be initially present may be determined as appropriate depending on the scale of the equipment, the above-mentioned supply amount, etc., but is preferably 4 to 9 kg.

Removal of residues in the system, including heavy inert oil, may be carried out as appropriate to prevent the amount of residue in the system from becoming too large or too small, and may be carried out continuously or intermittently. Bye. Preferably, the residual amount in the system is maintained at 50 to 150% by volume based on the initial residual amount.

Next, preferred embodiments of the present invention will be explained using the drawings.

The drawing is a schematic diagram of an apparatus for implementing the method of the present invention.6 When implementing the method of the present invention, first, heavy inert oil 2 is charged into a seed type pyrolyzer 1, and heated at 200 to 300°C. Preferably, it is heated to 220 to 280°C. Next, a mixture of dicyclopentadiene supplied from the raw material pipe 3 and heavy inert oil supplied from the pipe 4 is continuously supplied onto the liquid surface of the heavy inert oil by the feed pump 5.

In the seed type thermal decomposer 1, most of the raw material dicyclopentadiene is instantaneously thermally decomposed into cyclopentadiene, which is simultaneously evaporated. The evaporated product is cooled and cyclopentadiene is recovered.

However, at this time, a part of the raw material dicyclopentadiene is also evaporated without being thermally decomposed. The composition of this vapor varies depending on the thermal decomposition conditions of the raw material dicyclopentadiene, but it contains 70 to 95% cyclopentadiene.

Therefore, in order to obtain cyclopentadiene with high purity,
Preferably, a dephlegmator 6 is connected to the seed pyrolyzer 1 . This demultiplexer 6 has a simple structure, and preferably has a large number of thin tubes therein, around which the cooling medium is passed. Purification and separation takes place as the steam passes through the capillary.

A commonly used multi-vessel plate type non-drop tower.

Although the merciless effect is much higher, the dimerization reaction is likely to occur inside the dropless column, and dicyclopentadiene may be produced.In this case, the overall thermal decomposition yield will decrease, and Heat loss also increases, so care must be taken when using it.

The cooling temperature in the decentralizer 6 is set to 10 to 90°C, preferably 25°C.
Adjust to ~70°C. If the cooling temperature is lower than 10℃, a flashing phenomenon will occur inside the dephlegmator, disrupting the dropletless purification and separation state, and the distillation efficiency will drop significantly, the amount returned from the dephlegmation will increase, and thermal decomposition will occur. The time for high-temperature heat treatment in the vessel becomes longer, and as a result, thermal polymerization reactions are more likely to occur, and the problem of increased viscosity of thermal decomposition residue oil is more likely to occur. Moreover, if the cooling temperature is made higher than 90° C., a part of the raw material dicyclopentadiene will be distilled out, so that the distillation efficiency will similarly decrease and the purity of cyclopentadiene will be significantly reduced. Therefore, the cooling temperature inside the dephlegmator should be set at 10 to 90℃.
Adjust to

The distillate from the demultiplexer 6 is then introduced into the total condenser 7 for cooling and condensation, and liquid cyclopentadiene is removed from the outlet 8.

Thermal decomposition residual oil is discharged from the outlet 9 as appropriate in relation to the amount of raw material supplied.
is discharged from.

In this way, according to the present invention, cyclopentadiene can be efficiently produced without clogging the pyrolyzer even during long-term operation with a simple device without providing a raw material vaporizer in front of the pyrolyzer. It can be obtained in high purity.

Next, examples of the present invention will be shown.

Example 1 Spindle oil (manufactured by Maruzen Oil Co., Ltd.) was charged in advance into a seed-type pyrolyzer, and the spindle oil was heated to a temperature of 260°C. After adjusting the cooling temperature in the partial condenser connected to the top of this type pyrolyzer to 30°C, 97 parts by weight of commercially available liquid dicyclopentadiene (purity 95.2%) was mixed with heavy inert oil. and 3 parts by weight of spindle oil was fed to the dephlegmator at a constant rate of 2.3 kg/hour. As a result, 99.1% (thermal decomposition distillation rate) of the raw material dicyclopentadiene was distilled from the partial condenser, and the amount of cyclopentadiene in the distillate was 94.9%. was 0.4%, and other impurities were 4.7%. Therefore, the thermal decomposition yield (thermal decomposition distillation rate x cyclopentadiene purity in the distillate) of the raw material dicyclopentadiene was 94.0%.

In addition, the heavy inert residue mainly composed of spindle oil was extracted from the seed type pyrolyzer at a constant rate of 0.09 kg/hour and operated for 500 hours. The heavy inert oil whose main component was oil was colored blackish brown, but almost no increase in viscosity was observed.

Examples 2-6 The operation was carried out in the same manner as in Example 1 except that the conditions shown in the table below were used. The results obtained are shown in the table below.

[Brief explanation of the drawing]

The drawing is a schematic diagram of an apparatus for carrying out the method of the present invention. 1...Seed type pyrolyzer, 6...Different condenser, 7... Total condenser. Agent Patent Attorney Kunihiko Wakabayashi

Claims (1)

[Claims] 1. Continuously supply a mixture of liquid dicyclopentadiene and heavy inert oil from above the liquid surface of the heavy inert oil heated to a temperature of 200 to 300° C. to produce dicyclopentadiene. It is decomposed into cyclopentadiene and recovered by evaporation.
A method for producing cyclopentadiene, which comprises removing the residue in the system containing the heavy inert oil to the outside of the system. 2. The method for producing cyclopentadiene according to claim 1, wherein the mixture of liquid dicyclopentadiene and heavy inert oil has a weight ratio of 471 to 100/1. 3. The method for producing cyclopentadiene according to claim 1 or 2, wherein the feed rate of the mixture of liquid dicyclopentadiene and heavy inert oil is 1 to 4.5 kg/hour. 4. The method according to claim 1, 2, or 3, in which cyclopentadiene and p-deaf dicyclopentadiene are separated by a dephlegmator whose temperature is adjusted to 10 to 90°C. Method for producing cyclopentadiene. 5. Claims 1, 2, and 3, in which the cyclopentadiene separated by the partial condenser is recovered by the total condenser.
4. The method for producing cyclopentadiene according to item 4.