JP2020152666A - Method for producing dicyclopentadiene and isoprene - Google Patents

Abstract

To provide a method for producing dicyclopentadiene and isoprene which can simultaneously produce industrially useful dicyclopentadiene, while producing industrially useful isoamylene from a hydrocarbon having 5 carbon atoms.SOLUTION: There is provided a method for producing dicyclopentadiene and isoprene including: a separation step of obtaining a first mixture containing a normal form and a second mixture containing an iso form from a feedstock material mixture containing an iso form and a normal form of a hydrocarbon having 5 carbon atoms; a first dehydrogenation step of bringing the first mixture into contact with cyclization-dehydrogenation catalyst to obtain a first product containing cyclopentadiene; a second dehydrogenation step of bringing the second mixture into contact with a dehydrogenation catalyst to obtain a second product containing isoprene; and a recovery step of subjecting a third mixture containing the first product and the second product to dimerization of cyclopentadiene and extractive distillation to obtain dicyclopentadiene and isoprene.SELECTED DRAWING: None

Description

The present invention relates to a method for producing dicyclopentadiene and isoprene.

Various uses have been conventionally proposed for hydrocarbons having 5 carbon atoms. For example, isoprene is in high demand as a main component of synthetic rubber and the like, and is widely used industrially. Isoprene can be obtained, for example, by extracting and distilling from a C5 distillate containing a hydrocarbon having 5 carbon atoms as a main component, which is produced as a by-product when naphtha is thermally decomposed to produce ethylene. Further, Patent Document 1 describes that isoprene is produced by recovering isoprene from the extraction residual oil of the extraction distillation and dehydrogenating the isoamylene.

Japanese Unexamined Patent Publication No. 2015-151391

However, in the method described in Patent Document 1, the hydrocarbon having 5 carbon atoms remaining after the recovery of isoamylene becomes a loss. Therefore, a manufacturing process that enables more effective use of resources is expected.

The present invention provides a method for producing dicyclopentadiene and isoprene, which can produce industrially useful isoamylene from a hydrocarbon having 5 carbon atoms and at the same time produce industrially useful dicyclopentadiene. With the goal.

One aspect of the present invention is to obtain a first mixture containing the normal body and a second mixture containing the iso body from a raw material mixture containing a normal body and an iso body of a hydrocarbon having 5 carbon atoms. The separation step, the first dehydrogenation step of contacting the first mixture with the cyclization dehydrogenation catalyst to obtain the first product containing cyclopentadiene, and the second mixture and the dehydrogenation catalyst. From a second dehydrogenation step to obtain a second product containing isoprene and a third mixture containing the first product and the second product of cyclopentadiene. The present invention relates to a method for producing dicyclopentadiene and isoprene, which comprises a recovery step of obtaining dicyclopentadiene and isoprene by dehydrogenation and extraction distillation.

In one embodiment, the third mixture may further contain a C5 fraction containing a hydrocarbon having 5 carbon atoms as a main component. At this time, the recovery step may be a step of obtaining a raw material mixture containing dicyclopentadiene, isoprene, and a normal form and an iso form of a hydrocarbon having 5 carbon atoms.

The raw material mixture obtained in the recovery step can be used as the raw material mixture in the separation step.

In one embodiment, the recovery step comprises dimerizing cyclopentadiene by heating the third mixture to obtain dicyclopentadiene and a fourth mixture containing isoprene (A-1). The step may include a step (A-2) of obtaining isoprene by extraction distillation of the fourth mixture.

In one embodiment, the recovery step is a step (B-1) of obtaining isoprene and a fifth mixture containing cyclopentadiene by extraction distillation of the third mixture, and heating of the fifth mixture. The step may include a step (B-2) of dicyclopentadiene dicyclopentadiene to obtain dicyclopentadiene.

According to the present invention, there is provided a method for producing dicyclopentadiene and isoprene, which can produce industrially useful isoamylene from a hydrocarbon having 5 carbon atoms and at the same time produce industrially useful dicyclopentadiene. Will be done.

Hereinafter, preferred embodiments of the present invention will be described in detail.

In the production method according to the present embodiment, from a raw material mixture containing a normal body and an iso body of a hydrocarbon having 5 carbon atoms, a first mixture containing the normal body and a second mixture containing the iso body are used. The first dehydrogenation step of contacting the first mixture with the cyclization dehydrogenation catalyst to obtain the first product containing cyclopentadiene, and the second mixture and dehydration. Cyclo from a second dehydrogenation step of contacting a prime catalyst to obtain a second product containing isoprene and a third mixture containing the first product and the second product. It comprises a recovery step of obtaining dicyclopentadiene and isoprene by dehydrogenation and extraction distillation of pentadiene.

According to the production method according to the present embodiment, industrially useful isoamylene and dicyclopentadiene can be co-produced from a hydrocarbon having 5 carbon atoms.

Hereinafter, each step of the manufacturing method according to the present embodiment will be described in detail.

<Separation process>
In the separation step, a first mixture containing a normal body and a second mixture containing an iso body are obtained from a raw material mixture containing a normal body and an iso body of a hydrocarbon having 5 carbon atoms.

Examples of the normal form of the hydrocarbon having 5 carbon atoms include n-pentane, 1-pentene, 2-pentene, 1,3-pentadiene, and 1,4-pentadiene.

Examples of the isopentane of the hydrocarbon having 5 carbon atoms include isopentane, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene.

In the raw material mixture, the molar ratio of the iso form to the normal form may be, for example, 0.1 to 10, preferably 0.2 to 5, and more preferably 0.5 to 2.

In the separation step, the method for separating the first mixture and the second mixture from the raw material mixture is not particularly limited, and for example, distillation, extraction distillation, distillation separation via conversion of olefin to alcohol, membrane separation, etc. This can be done using any separation method. Of these, membrane separation is preferable as the separation method from the viewpoints of productivity, device scale, and energy intensity.

The separation membrane used for membrane separation is not particularly limited as long as the raw material mixture can be separated into a first mixture and a second mixture, and a polymer membrane, an inorganic membrane, a carbon membrane or the like can be used. it can. Among them, from the viewpoint of heat resistance and chemical resistance, an inorganic film is preferable, a ceramic film, a metal film and an alloy film are more preferable, a ceramic film is further preferable, and a zeolite membrane such as a silicalite film is particularly preferable.

Further, the membrane separation can be performed by using an arbitrary type of membrane separation module such as a flat plate type, a tubular type, a laminated flat plate type, and a multi-tube type. Among them, a flat plate type or multi-tube type membrane separation module is preferable from the viewpoint of separation efficiency and miniaturization of the apparatus, and a multi-tube type separation membrane module is preferable from the viewpoint of ease of replacement of the separation membrane. Is more preferable.

The first mixture may be a mixture containing a normal body as a main component (for example, 70% by mass or more). The amount of the normal body in the first mixture is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass.

The second mixture may be a mixture containing an iso-form as a main component (for example, 70% by mass or more). The amount of the iso-form in the second mixture is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass.

<First dehydrogenation process>
The first dehydrogenation step is a step of contacting the first mixture with a cyclized dehydrogenation catalyst to obtain a first product containing cyclopentadiene. In the first dehydrogenation step, cyclopentadiene is produced by the cyclization dehydrogenation reaction of the normal form in the first mixture.

The conditions of the cyclization dehydrogenation catalyst and the cyclization dehydrogenation reaction are not particularly limited, and any catalyst and conditions capable of converting at least a part of the normal form into cyclopentadiene can be used without particular limitation.

The cyclization dehydrogenation catalyst may have, for example, a carrier and an active metal supported on the carrier.

As the carrier, an inorganic carrier is preferable, and an inorganic oxide carrier is more preferable. Further, the carrier preferably contains at least one element selected from the group consisting of Al, Mg, Si, Zr, Ti and Ce, and at least one element selected from the group consisting of Al, Mg and Si. It is more preferable to include it.

A preferred embodiment of the cyclization dehydrogenation catalyst is shown below.

The cyclization dehydrogenation catalyst of this embodiment is a catalyst in which a carrier containing Al and a Group 2 metal element is supported by a supported metal containing a Group 14 metal element and Pt. Here, the Group 2 metal element means a metal element belonging to Group 2 of the periodic table in the periodic table of long-periodic elements based on the provisions of IUPAC (International Genuine Applied Chemistry Association), and is a Group 14 metal element. Means a metal element belonging to Group 14 of the periodic table in the periodic table of long-periodic elements based on the provisions of IUPAC (International Genuine Applied Chemistry Association).

The Group 2 metal element may be at least one selected from the group from, for example, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba). Among these, the Group 2 metal element is preferably Mg.

The Group 14 metal element may be, for example, at least one selected from the group consisting of germanium (Ge), tin (Sn) and lead (Pb). Among these, the Group 14 metal element is preferably Sn.

The cyclization dehydrogenation catalyst may be a cyclization dehydrogenation catalyst other than the above. For example, a preferred example of a cyclization dehydrogenation catalyst other than the above is a catalyst using Cr as a supporting metal in the above embodiment.

The conditions of the cyclization dehydrogenation reaction are not particularly limited, and for example, the reaction temperature may be 300 to 800 ° C., 400 to 700 ° C., or 500 to 650 ° C. When the reaction temperature is 300 ° C. or higher, the amount of cyclopentadiene produced tends to be further increased. When the reaction temperature is 800 ° C. or lower, the caulking rate does not become too high, so that the high activity of the cyclized dehydrogenation catalyst tends to be maintained for a longer period of time. The reaction pressure, that is, the air pressure in the reactor may be 0.01 to 1 MPa, 0.05 to 0.8 MPa, or 0.1 to 0.5 MPa. If the reaction pressure is within the above range, the dehydrogenation reaction tends to proceed easily, and a more excellent reaction efficiency tends to be obtained.

Further, when the cyclization dehydrogenation reaction is carried out in a continuous reaction form in which the raw material gas is continuously supplied, the weight space velocity (hereinafter referred to as "WHSV") is, for example, 0.1 h ^-1 or more. It may be 0.5h ^-1 or more. Further, the WHSV may be 20h ^-1 or less, and may be 10h ^-1 or less. Here, WHSV is the ratio (F / W) of the supply rate (supply amount / hour) F of the raw material gas (first mixture) to the mass W of the cyclization dehydrogenation catalyst. When the WHSV is 0.1 h ^-1 or more, the reactor size can be made smaller. When the WHSV is 20 h ^-1 or less, the yield of cyclopentadiene can be further increased. The amount of the raw material gas and the catalyst used may be appropriately selected in a more preferable range depending on the reaction conditions, the activity of the catalyst, and the like, and the WHSV is not limited to the above range.

The reaction form of the cyclization dehydrogenation reaction may be, for example, a fixed bed type, a moving bed type or a fluidized bed type. Of these, the fixed floor type is preferable from the viewpoint of equipment cost.

The first product contains cyclopentadiene produced by the cyclization dehydrogenation reaction. The first product may further contain components other than cyclopentadiene, eg, the uncyclized normal form.

<Second dehydrogenation process>
The second dehydrogenation step is a step of contacting the second mixture with the dehydrogenation catalyst to obtain a second product containing isoprene. In the second dehydrogenation step, isoprene is produced by the dehydrogenation reaction of the iso-form in the second mixture.

The conditions of the dehydrogenation catalyst and the dehydrogenation reaction are not particularly limited, and any catalyst and conditions capable of converting at least a part of the isoform into isoprene can be used without particular limitation.

As the dehydrogenation catalyst, for example, a catalyst in which a carrier containing Al and a Group 2 metal element is supported by a supported metal containing a Group 14 metal element and Pt (hereinafter, also referred to as a first dehydrogenation catalyst). Can be used. Here, the Group 2 metal element means a metal element belonging to Group 2 of the periodic table in the periodic table of long-periodic elements based on the provisions of the IUPAC (International Union of Pure and Applied Chemistry). The Group 14 metal element means a metal element belonging to Group 14 of the periodic table in the periodic table of long-periodic elements based on the provisions of the IUPAC (International Union of Pure and Applied Chemistry).

As the Group 2 metal element, Mg is particularly suitable, and as the Group 14 metal element, Sn is particularly suitable.

Further, as the dehydrogenation catalyst, for example, a catalyst in which tin and an active metal are supported on an inorganic oxide carrier (hereinafter, also referred to as a second dehydrogenation catalyst) can be used. As the active metal, platinum, ruthenium, iridium and the like can be preferably used.

In the second dehydrogenation step, the dehydrogenation reaction may be carried out using either one of the first dehydrogenation catalyst and the second dehydrogenation catalyst, and the first dehydrogenation catalyst and the second dehydrogenation catalyst may be used. The dehydrogenation reaction may be carried out using both of the above.

The conditions of the dehydrogenation reaction in the second dehydrogenation step are not particularly limited, and for example, the reaction temperature may be 300 to 800 ° C., 400 to 700 ° C., or 500 to 650 ° C. .. When the reaction temperature is 300 ° C. or higher, the amount of isoprene produced tends to increase further. When the reaction temperature is 800 ° C. or lower, the caulking rate does not become too high, so that the high activity of the dehydrogenation catalyst tends to be maintained for a longer period of time. The reaction pressure, that is, the air pressure in the reactor, may be 0.01 to 1 MPa, 0.05 to 0.8 MPa, or 0.1 to 0.5 MPa. If the reaction pressure is within the above range, the dehydrogenation reaction tends to proceed easily, and a more excellent reaction efficiency tends to be obtained.

Furthermore, the dehydrogenation reaction in the second dehydrogenation step, when performing source gas in the reaction form of continuously feeding a continuous, weight hourly space velocity (. Hereinafter referred to as "WHSV") is, for example 0.1 h ^{- It} may be ¹ or more, and may be 0.5h ^-1 or more. Further, the WHSV may be 20h ^-1 or less, and may be 10h ^-1 or less. Here, WHSV is the ratio (F / W) of the supply rate (supply amount / hour) F of the raw material gas (second mixture) to the mass W of the dehydrogenation catalyst. When the WHSV is 0.1 h ^-1 or more, the reactor size can be made smaller. When the WHSV is 20 h ^-1 or less, the conversion rate to isoprene can be further increased. The amount of the raw material gas and the catalyst used may be appropriately selected in a more preferable range depending on the reaction conditions, the activity of the catalyst, and the like, and the WHSV is not limited to the above range.

The reaction type of the second dehydrogenation reaction may be, for example, a fixed bed type, a moving bed type or a fluidized bed type. Of these, the fixed floor type is preferable from the viewpoint of equipment cost.

The second product contains isoprene produced by the dehydrogenation reaction. The second product may further contain a component other than isoprene, for example, an iso-form other than isoprene.

<Recovery process>
The recovery step is a step of obtaining dicyclopentadiene and isoprene from a third mixture containing the first product and the second product by dimerization and extraction distillation of cyclopentadiene.

The third mixture contains cyclopentadiene and isoprene, cyclopentadiene is converted to dicyclopentadiene by a dimerization reaction and recovered, and isoprene is recovered by extraction distillation. The third mixture may further contain a hydrocarbon having 5 carbon atoms other than cyclopentadiene and isoprene, and the hydrocarbon having 5 carbon atoms is used in the above-mentioned separation step after the recovery of dicyclopentadiene and isoprene. It can be used as a raw material mixture.

In addition to the first product and the second product, the third mixture may further contain a C5 fraction containing a hydrocarbon having 5 carbon atoms as a main component. As a result, cyclopentadiene and isoprene in the C5 fraction are recovered by dimerization and extraction distillation, and hydrocarbons having 5 carbon atoms other than cyclopentadiene and isoprene in the C5 fraction are efficiently used as raw material compounds in the above-mentioned separation step. It can be used well. That is, by blending the C5 fraction with the third mixture, the normal and iso-forms which are the raw material components are added to the reaction cycle consisting of the separation step, the first dehydrogenation step, the second dehydrogenation step and the recovery step. Can be introduced efficiently.

The C5 fraction contains a hydrocarbon having 5 carbon atoms as a main component (for example, 70% by mass or more). The amount of the hydrocarbon having 5 carbon atoms in the C5 fraction is preferably 80% by mass or more, more preferably 90% by mass or more.

The C5 fraction may be, for example, a C5 fraction produced by thermal cracking of naphtha, or a light hydrocarbon mixture derived from a heavy oil catalytic cracking apparatus.

The C5 fraction preferably contains both a normal form and an iso form of a hydrocarbon having 5 carbon atoms. The molar ratio of the iso form to the normal form in the C5 fraction is not particularly limited, but may be, for example, 0.2 to 5, preferably 0.5 to 2.

The C5 fraction may further contain cyclopentadiene. In this case, the dimerization in the recovery step produces industrially useful dicyclopentadiene from the cyclopentadiene.

The C5 fraction may further contain isoprene. In this case, industrially useful isoprene is recovered by extraction distillation in the recovery step.

In the recovery step, the order of dimerization and extraction distillation is not limited. In a preferred embodiment, the recovery step may be a step of dimerizing cyclopentadiene in the third mixture to obtain dicyclopentadiene, and then recovering isoprene by extraction distillation. Further, in another preferred embodiment, the recovery step may be a step of recovering isoprene and cyclopentadiene by extraction distillation of the third mixture and dimerizing the recovered cyclopentadiene to obtain dicyclopentadiene. Good. Each aspect will be described in detail below.

(First aspect)
In the first aspect, the recovery step is a step (A-1) of dimerizing cyclopentadiene by heating the third mixture to obtain dicyclopentadiene and a fourth mixture containing isoprene. It comprises the step (A-2) of obtaining isoprene by extraction distillation of the fourth mixture.

In step (A-1), the cyclopentadiene in the third mixture is dimerized to give dicyclopentadiene. In addition, the components other than cyclopentadiene are subjected to the subsequent step (A-2) as a fourth mixture.

In step (A-2), isoprene is recovered by extraction distillation of the fourth mixture. Further, the fourth mixture may contain a hydrocarbon having 5 carbon atoms other than isoprene, and the hydrocarbon having 5 carbon atoms is reused as a raw material mixture in the above-mentioned separation step after extraction distillation. ..

The conditions for the dimerization reaction in step (A-1) are not particularly limited, and can be used without particular limitation as long as the conditions can dimerize cyclopentadiene to produce dicyclopentadiene. From the viewpoint of suppressing the increase in cyclopentadiene and the reaction efficiency, the dimerization of cyclopentadiene is preferably carried out by using the Diels-Alder reaction, and the Diels-Alder reaction in the liquid phase using a non-catalytic continuous reactor is performed. It is more preferable to use it. The residence time of the hydrocarbon mixture when carrying out the Diels-Alder reaction using a continuous reactor is preferably 0.5 hours or more, more preferably 1 hour or more, and 6 hours or less. It is preferably 4 hours or less. With such a residence time, the dimerization reaction can be sufficiently advanced, and the side reaction between cyclopentadiene and isoprene, piperylene, etc. is suppressed, and dicyclopentadiene can be obtained more efficiently. it can.

The reaction temperature of the dimerization reaction in step (A-1) is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, preferably 250 ° C. or lower, and preferably 150 ° C. or lower. More preferred. By setting such a reaction temperature, the dimerization reaction can be sufficiently proceeded, and the above-mentioned side reaction can be suppressed to obtain dicyclopentadiene more efficiently.

The dicyclopentadiene produced by the dimerization reaction may be recovered from the mixture after the reaction by a method such as distillation separation or the like. In addition, the components other than dicyclopentadiene in the mixture after the reaction are recovered as a fourth mixture and subjected to step (A-2).

The conditions for extraction distillation in step (A-2) are not particularly limited as long as the conditions are such that isoprene can be separated and recovered. The extraction distillation in step (A-2) can be carried out by, for example, a method such as extraction separation using an extractant containing dimethylformamide or the like.

The components other than isoprene in the fourth mixture can be recovered and used as a raw material mixture in the separation step.

(Second aspect)
In the second aspect, the recovery step is a step (B-1) of obtaining isoprene and a fifth mixture containing cyclopentadiene by extraction distillation of the third mixture, and heating of the fifth mixture. Includes the step (B-2) of distilling cyclopentadiene according to the above to obtain dicyclopentadiene.

In step (B-1), isoprene and a fifth mixture containing cyclopentadiene are recovered by extraction distillation of the third mixture, respectively. The third mixture may contain a hydrocarbon having 5 carbon atoms other than isoprene and cyclopentadiene, and the hydrocarbon having 5 carbon atoms is reused as a raw material mixture in the above-mentioned separation step after extraction distillation. To.

In step (B-2), dicyclopentadiene is obtained by the dimerization reaction of cyclopentadiene recovered in step (B-1).

The conditions for extraction distillation in step (B-1) are not particularly limited as long as they can separate and recover cyclopentadiene and isoprene, respectively. The extraction distillation in step (B-1) can be carried out by, for example, a method such as extraction separation using an extractant containing acetonitrile, n-methylpyrrolidone or the like.

The components of the third mixture other than cyclopentadiene and isoprene can be recovered and used as a raw material mixture in the separation step.

The conditions for the dimerization reaction in step (B-2) are not particularly limited, and can be used without particular limitation as long as the conditions can dimerize cyclopentadiene to produce dicyclopentadiene. From the viewpoint of suppressing the increase in cyclopentadiene and the reaction efficiency, the dimerization of cyclopentadiene is preferably carried out by using the Diels-Alder reaction, and the Diels-Alder reaction in the liquid phase using a non-catalytic continuous reactor is performed. It is more preferable to use it. The residence time of the hydrocarbon mixture when carrying out the Diels-Alder reaction using a continuous reactor is preferably 0.5 hours or more, more preferably 1 hour or more, and 6 hours or less. It is preferably 4 hours or less. With such a residence time, the dimerization reaction can be sufficiently advanced, side reactions are suppressed, and dicyclopentadiene can be obtained more efficiently.

The reaction temperature of the dimerization reaction in step (B-2) is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, preferably 250 ° C. or lower, and preferably 150 ° C. or lower. More preferred. By setting such a reaction temperature, the dimerization reaction can be sufficiently proceeded, and side reactions can be suppressed to obtain dicyclopentadiene more efficiently.

The dicyclopentadiene produced by the dimerization reaction may be recovered from the mixture after the reaction by a method such as distillation separation or the like.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
Using the C5 fraction having the composition shown in Table 1, the reaction cycle including the following separation step, first dehydrogenation step, second dehydrogenation step and recovery step was examined.
The C5 fraction having the composition shown in Table 1 is mixed with the first product obtained in the first dehydrogenation step described later and the second product obtained in the second dehydrogenation step described later. It is used for the recovery process. In the recovery step, dicyclopentadiene and isoprene are recovered by dimerization and extraction distillation of cyclopentadiene, and other C5 fractions are supplied to the separation step described later.
In the separation step, the C5 fraction that has undergone the recovery step is separated into a first mixture containing a normal form and a second mixture containing an iso form. The first mixture is subjected to the first dehydrogenation step described below, and the second mixture is subjected to the second dehydrogenation step described below.
In the first dehydrogenation step, the first mixture is brought into contact with the cyclized dehydrogenation catalyst to give the first product containing cyclopentadiene. In the second dehydrogenation step, the second mixture is brought into contact with the dehydrogenation catalyst to give a second product containing isoprene. The first and second products are fed to the recovery step as described above, which circulates the normal form in the C5 fraction to dicyclopentadiene and the iso form to isoprene in the system.

In the above reaction cycle, the yields of dicyclopentadiene and isoprene recovered through the recovery step (yields (% by mass) with respect to the amount of the C5 fraction used as the raw material) were determined. The results are shown in Table 2.

(Comparative Example 1)
A reaction system in which only the recovery step is carried out was examined.
That is, in the reaction system of Comparative Example 1, the C5 fraction having the composition shown in Table 1 is subjected to dimerization and extraction distillation of cyclopentadiene to recover dicyclopentadiene and isoprene. The rest of the dicyclopentadiene and isoprene after recovery is purged out of the system.

The yield of dicyclopentadiene and isoprene recovered in such a reaction system (yield (% by mass) with respect to the amount of C5 fraction used as a raw material) was determined. The results are shown in Table 2.

(Comparative Example 2)
The reaction cycle in which the first dehydrogenation step was not carried out was examined.
That is, in Comparative Example 2, the C5 fraction having the composition shown in Table 1 is mixed with the second product obtained in the second dehydrogenation step described later and subjected to the recovery step. In the recovery step, dicyclopentadiene and isoprene are recovered by dimerization and extraction distillation of cyclopentadiene, and other C5 fractions are supplied to the separation step described later.
In the separation step, the C5 fraction that has undergone the recovery step is separated into a first mixture containing a normal form and a second mixture containing an iso form. The first mixture is purged out of the system. The second mixture is subjected to the second dehydrogenation step described below.
v In the second dehydrogenation step, the second mixture is brought into contact with the dehydrogenation catalyst to give a second product containing isoprene. The second product is fed to the recovery step as described above, whereby the iso-form in the C5 fraction circulates in the system until it becomes isoprene.

The yield of dicyclopentadiene and isoprene recovered in such a reaction cycle (yield (% by mass) with respect to the amount of C5 fraction used as a raw material) was determined. The results are shown in Table 2.

Claims (5)

A separation step of obtaining a first mixture containing the normal body and a second mixture containing the iso body from a raw material mixture containing a normal body and an iso body of a hydrocarbon having 5 carbon atoms.
The first dehydrogenation step of contacting the first mixture with a cyclized dehydrogenation catalyst to obtain a first product containing cyclopentadiene.
A second dehydrogenation step of contacting the second mixture with a dehydrogenation catalyst to obtain a second product containing isoprene.
A recovery step of obtaining dicyclopentadiene and isoprene from the first product and a third mixture containing the second product by dimerization and extraction distillation of cyclopentadiene.
A method for producing dicyclopentadiene and isoprene, which comprises. The third mixture further contains a C5 fraction containing a hydrocarbon having 5 carbon atoms as a main component.
The production method according to claim 1, wherein the recovery step is a step of obtaining a raw material mixture containing dicyclopentadiene, isoprene, and a normal form and an iso form of a hydrocarbon having 5 carbon atoms. The production method according to claim 2, wherein the raw material mixture obtained in the recovery step is used as the raw material mixture in the separation step. The recovery process
The step (A-1) of dimerizing cyclopentadiene by heating the third mixture to obtain dicyclopentadiene and a fourth mixture containing isoprene.
The step (A-2) of obtaining isoprene by the extraction distillation of the fourth mixture, and
The production method according to any one of claims 1 to 3, which comprises. The recovery process
The step (B-1) of obtaining isoprene and a fifth mixture containing cyclopentadiene by extraction distillation of the third mixture.
The step (B-2) of dimerizing cyclopentadiene by heating the fifth mixture to obtain dicyclopentadiene, and
The production method according to any one of claims 1 to 3, which comprises.