JPH0430380B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for continuously producing methylcyclopentadiene by thermally decomposing liquid dimethyldicyclopentadiene. Conventionally, it has been known to produce cyclopentadiene by supplying liquid dicyclopentadiene as it is to a thermal decomposer, and it is also known to produce methylcyclopentadiene from liquid dimethyldicyclopentadiene in accordance with this method. There is. However, in this method, the interior of the thermal decomposer is clogged in a relatively short period of time due to polymers produced by thermal polymerization of raw material dimethyldicyclopetadiene and thermal decomposition products such as methylcyclopentadiene, and thermal decomposition operation is interrupted. There was a serious drawback that it could no longer be continued. 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 dimethyldicyclopentadiene is supplied to the thermal decomposer (for example, US Pat. No. 2,801,270 and US Pat.
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, 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 avoids the problems of evaporator clogging and large raw material loss. hard. 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 and cooled. A method has also been proposed in which cyclopentadiene is obtained by storing the cyclopentadiene in a drum, vaporizing it, and supplying it to a thermal decomposition 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 if you include incidental equipment, the entire installation will be large-scale, and it is not always economical to consider the cost, including the construction cost. It is difficult to say that it is a politically effective method. The present invention eliminates the drawbacks of the prior art described above, and provides a method that can economically produce high-purity methylcyclopentadiene using extremely simple equipment without clogging the thermal decomposer with thermal polymers. The purpose is to A mixture of liquid dimethyldicyclopentadiene and spindle oil (former/latter weight ratio: 4/1 to 100/1) is continuously poured onto the liquid surface of spindle oil heated to a temperature in the range of 240 to 350°C. supply to,
Dimethylcyclopentadiene is decomposed into methylcyclopentadiene, evaporated to form a distillate, and the distillate is heated through a dephlegmator whose temperature is adjusted to 40 to 130°C.
The present invention relates to a method for producing methylcyclopentadiene, which comprises separating methylcyclopentadiene and dimethyldicyclopentadiene, recovering methylcyclopentadiene, and removing residues in the system, including the spindle oil, from the system. As the raw material dimethyldicyclopentadiene used in the present invention, in addition to commercially available dimethyldicyclopentadiene, it is also possible to use a distillate containing 70% by weight or more of dimethyldicyclopentadiene obtained by decomposing petroleum products, etc. can. In this case, it is preferable that components having a boiling point of 130° C. or lower are not included as impurities. If impurities with a boiling point of 130°C or lower are contained, they will be mixed into the liquid methylcyclopentadiene as impurities when the evaporated methylcyclopentadiene is cooled and recovered, for example, in a dephlegmator, and the methylcyclopentadiene will be mixed in as an impurity. This is because it causes a decrease in purity. Note that dimethyldicyclopentadiene has the formula It is a mixture represented by When dimethyldicyclopentadiene is supplied from above the liquid surface of heavy inert oil heated to 240-350°C, dimethyldicyclopentadiene is almost simultaneously decomposed into methylcyclopentadiene and evaporated. Methylcyclopentadiene may be evaporated and recovered by a known method. For example, a condenser is used. As for the recovery method, if the evaporated material is simply coagulated and recovered, terminally decomposed dimethyldicyclopentadiene will also be recovered at the same time, resulting in a decrease in the purity of the obtained methylcyclopentadiene.
It is better to do as follows. That is, the evaporated matter is
First, a decentralizer whose temperature is adjusted to 40 to 130℃
The terminally decomposed dimethyldicyclopentadiene is aggregated, reduced to the decomposition reaction system, and subjected to the decomposition reaction. On the other hand, methylcyclopentadiene that has passed through the partial condenser is recovered in a total condenser. The mixture of dimethyldicyclopentadiene and spindle oil is dimethyldicyclopentadiene/
The weight ratio of spindle oil needs to be in the range of 4/1 to 100/1. The spindle used here is necessary to always prevent the increase in viscosity of the residue due to the thermal polymerization by-product, 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 dimethyldicyclopentadiene and spindle oil is appropriately determined depending on the scale of the apparatus, etc., but is preferably 1 to 4.5 kg/hour, particularly preferably 2 to 3.5 kg/hour. If the supply rate is too low, the production efficiency of methylcyclodiene will decrease, and if it is too high, the thermal decomposition efficiency of dimethyldicyclopentadiene will tend to decrease. The amount of spindle oil that is initially present may be determined as appropriate depending on the scale of the apparatus, the above-mentioned supply rate, etc., but is preferably 4 to 9 kg. Further, the removal of spindle oil-containing residues in the system may be carried out as appropriate so that the residues in the system do not become too large or too small, and may be carried out continuously or intermittently. Preferably, the amount of residue in the system is maintained at 50 to 150% by volume based on the initial residue. Next, preferred embodiments of the present invention will be explained using the drawings. The drawing is a schematic illustration of an apparatus for carrying out the method of the invention. When carrying out the method of the present invention, first, spindle oil 2 is charged into the tank-type pyrolyzer 1, and this is
It is heated to 240-350°C, preferably 260-320°C. Next, a mixture of dimethyldicyclopentadiene supplied from the raw material pipe 3 and spindle oil supplied from the pipe 4 is continuously supplied onto the liquid surface of the spindle oil by the feed pump 5. In the tank type thermal decomposer 1, most of the raw material dimethyldicyclopentadiene is instantaneously thermally decomposed into methylcyclopentadiene, which is simultaneously evaporated. The evaporated product is cooled and methylcyclopentadiene is recovered. However, at this time, a part of the raw material dimethyldicyclopentadiene is also evaporated while remaining thermally decomposed. The composition of this vapor varies depending on the thermal decomposition conditions of the raw material dimethyldicyclopentadiene, but it contains 70 to 95% methylcyclopentadiene. Therefore, in order to obtain methylcyclopentadiene with high purity, it is preferable to connect a dephlegmator 6 to the tank type pyrolysis 1. It is preferable that the demultiplexer 6 has a simple structure, has a large number of thin tubes inside, and allows the cooling medium to pass around it.
Purification and separation takes place as the steam passes through the capillary.
The commonly used multi-vessel plate type distillation tower has several stages of high distillation efficiency, but dimerization reactions tend to occur inside the distillation tower, and dimethyldicyclopentadiene may be produced, and in this case, the overall As the thermal decomposition yield decreases and heat loss also increases,
Care must be taken when using it. The cooling temperature in the decentralizer 6 is adjusted to 40-130°C, preferably 60-95°C. If the cooling temperature is lower than 40℃, a flashing phenomenon will occur inside the dephlegmator, which will disturb the purification and separation state by distillation, and the distillation effect will be significantly reduced. As the time for high-temperature heat treatment in the tank becomes longer, thermal polymerization reactions are more likely to occur, and the problem of increased viscosity of the thermal decomposition residue oil is more likely to occur. Moreover, if the cooling temperature is made higher than 130° C., part of the raw material methyldicyclopentadiene will be distilled out, so the distillation effect will similarly decrease and the purity of methylcyclopentadiene will be significantly reduced. Therefore,
Adjust the cooling temperature in the condenser to 40-130℃. The distillate from the decondenser 6 is then introduced into the total condenser 7 for cooling and condensation, and liquid methylcyclopentadiene is removed from the outlet 8. Thermal decomposition residual oil is adjusted as appropriate in comparison to the amount of raw material supplied.
It is discharged from the discharge port 9. In this way, according to the present invention, methylcyclopentadiene can be produced using a simple device without clogging the pyrolyzer even during long-term operation without providing a raw material vaporizer in front of the pyrolyzer. It can be obtained efficiently and with high purity. Next, the present invention will be explained based on examples.
The present invention is not limited to this. Example 1 Spindle oil (manufactured by Maruzen Oil Co., Ltd.) was charged in advance into a tank-type pyrolyzer, and the spindle oil was heated to a temperature of 300°C. After adjusting the cooling temperature in the partial condenser connected to the top of this tank-type pyrolyzer to 70°C, commercially available liquid methyl dicyclopentadiene (purity 96.1%) was used.
97 parts by weight and 3 parts by weight of spindle oil were supplied to the dephlegmator. As a result, 99.4% (thermal decomposition distillation rate) of the raw material methyldicyclopentadiene was distilled from the differential condenser, and the purity of methylcyclopentadiene in the distillate was 99.5%.
0.9%, and other impurities were 3.6%. Therefore, the thermal decomposition yield (thermal decomposition distillation rate x purity of methylcyclopentadiene in the distillate) of the raw material methyldicyclopentadiene was 94.9%. In addition, the heavy inert residue mainly composed of spindle oil from the tank-type thermal separator is extracted at a constant rate of 0.09 kg/hour.
After 500 hours of operation, the heavy inert residue, which was mainly composed of spindle oil, extracted from the tank-type pyrolyzer was colored dark brown, but almost no increase in viscosity was observed. Examples 1-2 and Comparative Examples 1-4 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.

[Table] As is clear from the results shown in the table above, according to the present invention, high-purity methylcyclohexadiene can be efficiently obtained using a simple device without clogging the thermal decomposer even during long-term operation. I can do it.

[Brief explanation of drawings]

The drawing is a schematic diagram of an apparatus for carrying out the method of the invention. 1... Tank type pyrolyzer, 6... Partial condenser, 7... Total condenser.

Claims (1)

[Scope of Claims] 1. A mixture of liquid dimethyldicyclopentadiene and spindle oil (former/latter in a weight ratio of 4/1 to 4/1 to 350°C) 100/1),
Dimethyldisclopentadiene is decomposed into methylcyclopentadiene, evaporated to form a distillate, and the distillate is heated to 40 to 130°C using a dephlegmator.
A method for producing methylcyclopentadiene, which comprises separating methylcyclopentadiene and dimethyldicyclopentadiene, recovering methylcyclopentadiene, and removing residues in the system, including the spindle oil, from the system. 2 A mixture of liquid dimethyldicyclopentadiene and spindle oil (former/latter in a weight ratio of 4/
1. The method for producing methylcyclopentadiene according to claim 1, wherein the feed rate of 1 to 100/1) is 1 to 4.5 kg/hour. 3. The method for producing methylcyclopentadiene according to claim 1 or 2, wherein methylcyclopentadiene separated by a partial condenser is recovered by a total condenser.