JP7664284B2 - Method for producing dicyclopentadiene and isoprene - Google Patents

Description

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

Conventionally, dicyclopentadiene (DCPD) and isoprene have been known as useful compounds used for applications such as polymer raw materials. For example, Patent Document 1 proposes a method for producing dicyclopentadiene and isoprene by dimerization and extractive distillation from a hydrocarbon mixture such as a C5 fraction obtained when ethylene is produced by cracking naphtha, as a method for producing dicyclopentadiene, isoprene, and piperylene.

International Publication No. 2018/163828

However, in the method described in Patent Document 1, the ratio of dicyclopentadiene and isoprene produced depends on the composition of the hydrocarbon mixture, such as the C5 fraction. Therefore, it was difficult to adjust the production balance, such as increasing the proportion of dicyclopentadiene in the total production of dicyclopentadiene and isoprene or increasing the proportion of isoprene, depending on demand. If the production balance cannot be adjusted, problems may occur in which the supply of one of dicyclopentadiene and isoprene is in excess of demand and the supply of the other is insufficient relative to demand.

Therefore, the present disclosure aims to provide a method for producing dicyclopentadiene and isoprene that allows adjustment of the production balance of dicyclopentadiene and isoprene.

One aspect of the present disclosure relates to a method for producing dicyclopentadiene and isoprene, comprising: a separation step of separating a hydrocarbon mixture containing normal and iso forms of hydrocarbons having a carbon number of 5 into a portion and a remainder; a dehydrogenation step of dehydrogenating a first mixture containing the portion of the hydrocarbon mixture to obtain a first product containing isoprene; an isomerization/cyclization/dehydrogenation step of isomerizing and cyclization/dehydrogenating a second mixture containing the remainder of the hydrocarbon mixture to obtain a second product containing cyclopentadiene; a first recovery step of recovering dicyclopentadiene from a mixed product obtained by mixing the first product and the second product by dimerizing the cyclopentadiene and extractive distillation; and a second recovery step of recovering isoprene from the non-recovered product in the first recovery step by extractive distillation, in which at least a portion of the iso form is isomerized to the normal form in the isomerization step.

In one aspect, the production method may be a production method in which the ratio between the amount of dicyclopentadiene recovered in the first recovery step and the amount of isoprene recovered in the second recovery step is controlled by controlling the ratio between the portion and the remainder of the hydrocarbon mixture.

In one embodiment, the isomerization, cyclization, and dehydrogenation process may be a process for producing the cyclopentadiene by contacting the second mixture with a catalyst having isomerization, cyclization, and dehydrogenation capabilities.

In one embodiment, the isomerization, cyclization, dehydrogenation process may be a process in which the second mixture is contacted with a catalyst having isomerization ability, and then with a catalyst having cyclization and dehydrogenation ability, thereby producing the cyclopentadiene.

According to the present disclosure, a method for producing dicyclopentadiene and isoprene can be provided that allows adjustment of the production balance of dicyclopentadiene and isoprene.

FIG. 1 is a flow diagram showing an example of an apparatus for producing dicyclopentadiene and isoprene for carrying out a method for producing dicyclopentadiene and isoprene according to an embodiment of the present invention. FIG. 2 is a flow diagram showing another example of an apparatus for producing dicyclopentadiene and isoprene for carrying out the method for producing dicyclopentadiene and isoprene according to an embodiment of the present invention. FIG. 2 is a flow diagram showing another example of an apparatus for producing dicyclopentadiene and isoprene for carrying out the method for producing dicyclopentadiene and isoprene according to an embodiment of the present invention.

A preferred embodiment of the present disclosure is described in detail below.

<Production Method of Dicyclopentadiene and Isoprene>
The method for producing dicyclopentadiene and isoprene according to the present embodiment includes a separation step of separating a hydrocarbon mixture containing normal and iso forms of hydrocarbons having a carbon number of 5 into a part and a remainder, a dehydrogenation step of dehydrogenating a first mixture containing the part of the hydrocarbon mixture to obtain a first product containing isoprene, an isomerization/cyclization/dehydrogenation step of isomerizing and cyclization/dehydrogenating a second mixture containing the remainder of the hydrocarbon mixture to obtain a second product containing cyclopentadiene, a first recovery step of recovering dicyclopentadiene from a mixed product obtained by mixing the first product and the second product by dimerizing the cyclopentadiene and extractive distillation, and a second recovery step of recovering isoprene from the non-recovered product in the first recovery step by extractive distillation. In the isomerization treatment, at least a part of the iso form is isomerized to a normal form.

According to the production method of this embodiment, the production balance of dicyclopentadiene and isoprene can be adjusted. This is because the hydrocarbon mixture is separated into a part and the remainder, and the dehydrogenation process is performed on one part and the isomerization cyclization dehydrogenation process is performed on the other part. In the isomerization cyclization dehydrogenation process, at least a part of the iso form is isomerized to a normal form and a cyclization dehydrogenation process is performed, so that the amount of cyclopentadiene produced is greater than that in the dehydrogenation process. Therefore, when the proportion of the remainder of the hydrocarbon mixture is increased, the production amount of dicyclopentadiene increases, and when the proportion of the part of the hydrocarbon mixture is increased, the production amount of isoprene increases. In this way, by adjusting the ratio of the part of the hydrocarbon mixture to the remainder, the production balance of dicyclopentadiene and isoprene can be adjusted without changing the composition of the hydrocarbon mixture such as the C5 fraction supplied as a raw material.

In addition, in conventional methods, when dicyclopentadiene is produced from a hydrocarbon mixture containing normal and iso forms of hydrocarbons having five carbon atoms, a step of separating the iso form and the normal form is carried out. However, according to the production method of this embodiment, by carrying out an isomerization cyclization dehydrogenation step, dicyclopentadiene can be produced efficiently without carrying out a step of separating the iso form and the normal form.

Each step of the manufacturing method according to this embodiment is described in detail below.

(Separation process)
The separation step is a step of separating a hydrocarbon mixture containing normal and iso isomers of hydrocarbons having a carbon number of 5 into a part and a remainder. In this step, the method of separation is not particularly limited as long as the hydrocarbon mixture can be separated into the part and the remainder at any ratio. The separation step can be performed using a separator such as a system equipped with a flow detection means and a control device connected to a gas distribution valve. The composition of the part and the remainder of the separated hydrocarbon mixture may be the same. The part and the remainder after separation may each be mixed with other components such as a hydrocarbon mixture of different compositions.

Examples of normal hydrocarbons with 5 carbon atoms include n-pentane, 1-pentene, 2-pentene, 1,3-pentadiene (also known as piperylene), and 1,4-pentadiene.

Examples of iso-forms of hydrocarbons with five carbon atoms include isopentane, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, and 2-methyl-1,3-butadiene (also known as isoprene).

The hydrocarbon mixture may contain other components in addition to the normal and iso forms of hydrocarbons having 5 carbon atoms. Examples of other components include cyclopentane, cyclopentene, cyclopentadiene, and 2,2-dimethylpropane (also known as neopentane).

The total amount of normal and iso hydrocarbons having 5 carbon atoms in the hydrocarbon mixture is not particularly limited, but may be, for example, 50 to 100% by mass, 60 to 98% by mass, or 70 to 96% by mass, based on the total amount of the hydrocarbon mixture.

In the isomerization cyclization dehydrogenation step in the production method of this embodiment, the isomer can be isomerized to a normal isomer by isomerization, so the higher the content of the isomer in the hydrocarbon mixture, the more likely it is that the dicyclopentadiene yield improvement effect will be obtained compared to conventional production methods that do not perform isomerization. Therefore, the content of the isomer of the hydrocarbon having 5 carbon atoms in the hydrocarbon mixture is not particularly limited, but may be 10% by mass or more, 20% by mass or more, 40% by mass or more, 50% by mass or more, or 60% by mass or more based on the total amount of the hydrocarbon mixture. In addition, the content of the isomer of the hydrocarbon having 5 carbon atoms in the hydrocarbon mixture is not particularly limited, but may be 90% by mass or less, or 80% by mass or less based on the total amount of the hydrocarbon mixture.

The hydrocarbon mixture may be a C5 fraction. The C5 fraction may be, for example, a C5 fraction produced by thermal cracking of naphtha, a light hydrocarbon mixture derived from a heavy oil catalytic cracker, or a piperylene-enriched C5 fraction obtained in a C5 diene extraction process.

A portion of the hydrocarbon mixture separated in the separation step is made into a first mixture, either as is or after being mixed with other components, and is dehydrogenated in the dehydrogenation step. The remainder of the hydrocarbon mixture separated in the separation step (the hydrocarbon mixture other than the above-mentioned portion) is made into a second mixture, either as is or after being mixed with other components, and is isomerized and cyclized in the isomerization-cyclization-dehydrogenation step.

In the separation process, the mass ratio of the flow rate of the portion to the flow rate of the hydrocarbon mixture at the inlet of the separation process (flow rate of the portion of the hydrocarbon mixture/flow rate of the hydrocarbon mixture) may be adjusted arbitrarily within the range of 0 to 1 depending on the demand for dicyclopentadiene and isoprene, respectively. In this specification, the mass ratio is referred to as the separation rate.

(Dehydrogenation process)
In the dehydrogenation step, the first mixture is dehydrogenated to obtain a first product containing isoprene. The first product may contain piperylene.

The dehydrogenation step may be carried out, for example, by passing the first mixture through a reactor filled with a dehydrogenation catalyst. As the reactor, various reactors used in gas phase reactions using solid catalysts can be used. Examples of the reactor include a fixed bed reactor, a radial flow reactor, and a tubular reactor.

The reaction format of the dehydrogenation reaction may be, for example, a fixed bed type, a moving bed type, or a fluidized bed type. Of these, the fixed bed type is preferred from the viewpoint of equipment costs.

There are no particular limitations on the dehydrogenation catalyst and the conditions for the dehydrogenation reaction, and any catalyst and conditions can be used without particular limitations as long as they are capable of converting at least a portion of the saturated hydrocarbons and monoenes contained in the hydrocarbon mixture into isoprene.

The dehydrogenation catalyst may be the same as the cyclization dehydrogenation catalyst used in the cyclization dehydrogenation process described below.

From the standpoint of reaction efficiency, the reaction temperature of the dehydrogenation reaction, i.e., the temperature inside the reactor, may be 300 to 800°C, 400 to 700°C, or 500 to 650°C. If the reaction temperature is 300°C or higher, the dehydrogenation reaction tends to be more promoted. If the reaction temperature is 800°C or lower, the coking rate does not become too high, so the high activity of the dehydrogenation catalyst tends to be maintained for a longer period of time.

The reaction pressure, i.e., the air pressure inside the reactor, may be 0.01 to 1 MPa, 0.03 to 0.8 MPa, or 0.05 to 0.5 MPa. If the reaction pressure is within the above range, the dehydrogenation reaction tends to proceed more easily, and even better reaction efficiency tends to be obtained.

When the dehydrogenation step is carried out in a continuous reaction form in which the first mixture (feed) is continuously supplied, the weight hourly space velocity (hereinafter referred to as "WHSV") may be, for example, 0.1 h ^-1 or more, or 0.5 h ^-1 or more. In addition, the WHSV may be 20 h ^-1 or less, or 10 h ^-1 or less. Here, the WHSV is the ratio (F/W) of the feed rate (feed mass/time) F of the feed to the mass W of the 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 dehydrogenation reaction tends to be more promoted. The amounts of the feed and the catalyst used may be appropriately selected from more preferable ranges depending on the reaction conditions, the activity of the catalyst, etc., and the WHSV is not limited to the above range.

The dehydrogenation catalyst may be, for example, a catalyst in which an active metal is supported on an inorganic oxide carrier. The active metal source may be at least one selected from the group consisting of platinum, tin, chromium, iron, bismuth, molybdenum, manganese, cobalt, cerium, ruthenium, and iridium.

The dehydrogenation step is preferably carried out in an atmosphere containing hydrogen or steam. This can further suppress catalyst deterioration and promote the production of isoprene.

When the dehydrogenation step is carried out in an atmosphere containing hydrogen, the hydrogen concentration in the atmosphere is preferably 5 to 95 mol%, and more preferably 5 to 30 mol%. By keeping the hydrogen concentration within the above range, the effect of suppressing catalyst deterioration can be further improved and the production of isoprene can be further promoted.

When the dehydrogenation step is carried out in an atmosphere containing steam, the steam concentration in the atmosphere is preferably 5 to 95 mol%, and more preferably 20 to 65 mol%. By keeping the steam concentration within the above range, the effect of suppressing catalyst deterioration can be further improved and the production of isoprene can be further promoted.

(Isomerization Cyclization Dehydrogenation Step)
In the isomerization/cyclodehydrogenation step, the second mixture is isomerized and cyclized/dehydrogenated to obtain a second product containing cyclopentadiene.

The isomerization cyclization dehydrogenation process may be a process of producing cyclopentadiene by contacting the second mixture with a catalyst having isomerization ability and then with a catalyst having cyclization ability and dehydrogenation ability, or a process of producing cyclopentadiene by contacting the second mixture with a catalyst having isomerization ability, cyclization ability and dehydrogenation ability. In the former case, the isomerization cyclization dehydrogenation process may include an isomerization process of isomerizing the second mixture and a cyclization dehydrogenation process of cyclizing the second mixture after the isomerization process. In the isomerization process, the iso form of the hydrocarbon having 5 carbon atoms contained in the second mixture is isomerized to a normal form of the hydrocarbon having 5 carbon atoms by an isomerization reaction. In the cyclization dehydrogenation process, cyclopentadiene is produced by the cyclization dehydrogenation reaction of the normal form.

The following describes the case where the isomerization/cyclization/dehydrogenation process has an isomerization process and a cyclization/dehydrogenation process.

In the isomerization process, the catalyst having isomerization ability and the conditions for the isomerization reaction are not particularly limited, and any catalyst and conditions that can isomerize at least a portion of the isomer to the normal isomer can be used without any particular restrictions.

As a catalyst having isomerization ability, for example, a zeolite catalyst can be used. It is preferable that the zeolite used is at least partially in the hydrogen form.

As a zeolite catalyst, the selectivity of the isomerization reaction can be further improved by using intermediate pore zeolites having a structure such as zeolite ZSM-5, ZSM-11, and ferrierite.

From the viewpoint of improving moldability, the zeolite catalyst may further contain a molding aid within the scope of the present disclosure without impairing the physical properties or catalytic performance of the catalyst. The molding aid may be, for example, at least one selected from the group consisting of a thickener, a surfactant, a water retention agent, a plasticizer, a binder raw material, etc. The molding process for molding the zeolite catalyst may be performed at an appropriate stage in the manufacturing process of the zeolite catalyst, taking into account the reactivity of the molding aid.

The zeolite catalyst may support platinum or palladium as the active metal. By supporting the active metal, it is expected that the isomerization reaction of the paraffin components will occur.

The conditions for the isomerization reaction are not particularly limited, and for example, the reaction temperature may be 150 to 500°C, 200 to 400°C, or 250 to 350°C. If the reaction temperature is 150°C or higher, isomerization from the iso form to the normal form tends to proceed more easily. If the reaction temperature is 350°C or lower, the amount of light hydrocarbons produced tends to be smaller. The reaction pressure, i.e., the air pressure inside 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 isomerization reaction tends to proceed more easily, and even better reaction efficiency tends to be obtained.

In addition, when the isomerization reaction is carried out in a continuous reaction form in which the second mixture (feed) is continuously supplied, the weight hourly space velocity (WHSV) may be, for example, 0.1 h ⁻¹ or more, or 0.5 h ⁻¹ or more. In addition, the WHSV may be 20 h ⁻¹ or less, or 10 h ⁻¹ or less. 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 isomerization rate from the iso form to the normal form can be made higher. The amount of the feed and the catalyst used may be appropriately selected from 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 format of the isomerization reaction may be, for example, a fixed bed type, a moving bed type, or a fluidized bed type. Of these, the fixed bed type is preferred from the viewpoint of equipment costs.

In the cyclization-dehydrogenation process, the catalyst having a catalyst having cyclization and dehydrogenation capabilities and the conditions for the cyclization-dehydrogenation reaction are not particularly limited, and any catalyst and conditions that can convert at least a portion of the normal isomer to cyclopentadiene can be used without particular limitations.

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

The carrier is preferably an inorganic carrier, more preferably an inorganic oxide carrier. The carrier preferably contains at least one element selected from the group consisting of Al, Mg, Si, Zr, Ti and Ce, more preferably contains at least one element selected from the group consisting of Al, Mg and Si.

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 supports 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 long-form periodic table of elements based on the provisions of IUPAC (International Union of Pure and Applied Chemistry), and the Group 14 metal element means a metal element belonging to Group 14 of the long-form periodic table of elements based on the provisions of IUPAC (International Union of Pure and Applied Chemistry).

The Group 2 metal element may be, for example, at least one selected from the group consisting of 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 those described above. For example, a suitable example of a cyclization dehydrogenation catalyst other than those described above is a catalyst using Cr as the supported metal in the above embodiment.

The conditions for 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. If the reaction temperature is 300°C or higher, the amount of cyclopentadiene produced tends to be greater. If the reaction temperature is 800°C or lower, the coking rate does not become too high, so the high activity of the cyclization dehydrogenation catalyst tends to be maintained for a longer period of time. The reaction pressure, i.e., the air pressure inside the reactor, may be 0.01 to 1 MPa, 0.03 to 0.8 MPa, or 0.05 to 0.5 MPa. If the reaction pressure is within the above range, the dehydrogenation reaction tends to proceed more easily, and better reaction efficiency tends to be obtained.

In addition, when the cyclization dehydrogenation reaction is carried out in a continuous reaction form in which the second mixture (feed) after the isomerization treatment is continuously supplied, the weight hourly space velocity (WHSV) may be, for example, 0.1 h ⁻¹ or more, or 0.5 h ⁻¹ or more. In addition, the WHSV may be 20 h ⁻¹ or less, or 10 h ⁻¹ or less. 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 made higher. The amounts of the feed and catalyst used may be appropriately selected from more preferable ranges 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 format 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 bed type is preferred from the viewpoint of equipment costs.

Next, the case where the isomerization, cyclization, and dehydrogenation process is a process for producing cyclopentadiene by contacting the second mixture with a catalyst having isomerization, cyclization, and dehydrogenation capabilities will be described below.

In the isomerization cyclization dehydrogenation process, the catalyst having isomerization ability, cyclization ability, and dehydrogenation ability and the conditions for the isomerization cyclization dehydrogenation reaction are not particularly limited, and any catalyst and conditions can be used without particular limitation as long as they are capable of isomerizing at least a portion of the iso form to the normal form and converting at least a portion of the normal form to cyclopentadiene.

Examples of catalysts having isomerization, cyclization and dehydrogenation capabilities include zeolite catalysts that use a crystalline metallosilicate as a carrier and have an active metal supported on the carrier.

Crystalline metallosilicates contain at least one metal atom selected from transition metals or post-transition metals in a zeolite, and have Lewis acidity and strong solid basicity.

Crystalline metallosilicates have a crystal structure similar to that of crystalline aluminosilicates, such as zeolite ZSM-5, ZSM-11, ZSM-12, zeolite beta, mordenite, and ferrierite.

The metal atoms contained in the zeolite are not particularly limited as long as they are transition metal atoms or post-transition metal atoms, and examples of such metal atoms include titanium (Ti), vanadium (V), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), zirconium (Zr), indium (In), and tin (Sn). Among these, zinc (Zn), nickel (Ni), and iron (Fe) are preferred from the viewpoint of excellent reactivity in the dehydrogenation reaction. The metal atoms contained in the zeolite may be one type alone or two or more types may be used.

From the viewpoint of improving moldability, the zeolite catalyst may further contain a molding aid within the scope of the present disclosure without impairing the physical properties or catalytic performance of the catalyst. The molding aid may be, for example, at least one selected from the group consisting of a thickener, a surfactant, a water retention agent, a plasticizer, a binder raw material, etc. The molding process for molding the zeolite catalyst may be performed at an appropriate stage in the manufacturing process of the zeolite catalyst, taking into account the reactivity of the molding aid.

The zeolite catalyst may be a catalyst in which platinum is supported on a carrier using a platinum (Pt) source. Examples of the platinum source include tetraammineplatinic (II) acid, tetraammineplatinic (II) acid salts (e.g., nitrates, etc.), tetraammineplatinic (II) acid hydroxide solution, dinitrodiammineplatinic (II) nitric acid solution, hexahydroxoplatinic (IV) acid nitric acid solution, and hexahydroxoplatinic (IV) acid ethanolamine solution.

The conditions for the isomerization cyclization dehydrogenation reaction are not particularly limited and can be, for example, the same as the conditions for the isomerization reaction in the isomerization step described above or the conditions for the cyclization dehydrogenation reaction in the cyclization dehydrogenation step described above.

It is preferable that the isomerization step and the cyclization-dehydrogenation step, or the isomerization-cyclization-dehydrogenation step, are carried out in an atmosphere containing hydrogen or steam. This makes it possible to further suppress deterioration of the catalyst and promote the production of cyclopentadiene.

When the isomerization step and the cyclization-dehydrogenation step, or the isomerization-cyclization-dehydrogenation step, are carried out in an atmosphere containing hydrogen, the hydrogen concentration in the atmosphere is preferably 5 to 95 mol%, and more preferably 5 to 30 mol%. By keeping the hydrogen concentration within the above range, the effect of suppressing catalyst deterioration can be further improved, and the production of cyclopentadiene can be further promoted.

When the isomerization step and the cyclization-dehydrogenation step, or the isomerization-cyclization-dehydrogenation step, are carried out in an atmosphere containing steam, the steam concentration in the atmosphere is preferably 5 to 95 mol%, and more preferably 20 to 65 mol%. By keeping the steam concentration within the above range, the effect of suppressing catalyst deterioration can be further improved, and the production of cyclopentadiene can be further promoted.

The piperylene concentration in the second mixture at the inlet of the isomerization cyclodehydrogenation step may be 0% by mass or more, 2% by mass or more, 5% by mass or more, or 10% by mass or more. The higher the piperylene concentration, the higher the dicyclopentadiene yield tends to be.

The concentration of the isoform of the hydrocarbon having 5 carbon atoms in the second mixture at the inlet of the isomerization cyclization dehydrogenation step may be 10% by mass or more, 20% by mass or more, 40% by mass or more, 50% by mass or more, or 60% by mass or more, and may be 90% by mass or less, or 80% by mass or less. The higher the concentration of the isoform, the lower the yield of dicyclopentadiene tends to be. However, according to the production method of this embodiment, the isoform can be isomerized to the normal isomer by the isomerization treatment, so that the yield of dicyclopentadiene can be improved even if the concentration of the isoform is within the above range.

(First recovery step)
In the first recovery step, dicyclopentadiene is recovered from a mixed product obtained by mixing the first product and the second product by dimerization of cyclopentadiene and extractive distillation. In the first recovery step, distillation of the mixed product may be performed before dimerization of cyclopentadiene. Hereinafter, in the first recovery step, the step of dimerizing cyclopentadiene is referred to as the dimerization step, the distillation step before the dimerization step is referred to as the first distillation step, and the distillation step after the dimerization step is referred to as the second distillation step. Each step will be described below.

(First distillation step)
In the first distillation step, the gas fraction generated by the reactions in the dehydrogenation step and the isomerization/cyclodehydrogenation step, and the low boiling point components of the C5 fraction are separated by distillation to obtain a fraction enriched in cyclopentadiene. The distillation can be performed, for example, by extractive distillation. The fraction enriched in cyclopentadiene obtained in the first distillation step can be supplied to the dimerization step. When the first distillation step is performed before the dimerization step, the fraction enriched in cyclopentadiene after the first distillation step is supplied to the dimerization step.

(Dimerization step)
In the dimerization step, the cyclopentadiene produced in the dehydrogenation step and the isomerization/cyclization/dehydrogenation step is dimerized to produce dicyclopentadiene.

The conditions of the dimerization reaction in the dimerization step are not particularly limited, and any conditions that can dimerize cyclopentadiene to produce dicyclopentadiene can be used without particular limitations. From the viewpoint of suppressing the multimerization of cyclopentadiene and reaction efficiency, the dimerization of cyclopentadiene is preferably carried out using the Diels-Alder reaction, and more preferably using the Diels-Alder reaction in a liquid phase using a continuous reactor without a catalyst. In addition, the residence time of the treated material when carrying out the Diels-Alder reaction using a continuous reactor is preferably 0.5 hours or more, more preferably 1 hour or more, preferably 6 hours or less, and more preferably 4 hours or less. By setting such a residence time, the dimerization reaction can be sufficiently progressed, and side reactions between cyclopentadiene and isoprene, piperylene, etc. can be suppressed, and dicyclopentadiene can be obtained more efficiently.

The reaction temperature of the dimerization reaction is preferably 50°C or higher, more preferably 60°C or higher, and is preferably 250°C or lower, more preferably 150°C or lower. By setting the reaction temperature at such a level, the dimerization reaction can be sufficiently progressed, and the above-mentioned side reactions can be suppressed, so that dicyclopentadiene can be obtained more efficiently.

The reaction pressure of the dimerization reaction, i.e., the air pressure inside the reactor, may be 0.01 to 1 MPa, 0.05 to 0.8 MPa, or 0.1 to 0.6 MPa. If the reaction pressure is within the above range, the dimerization reaction tends to proceed more easily, and even better reaction efficiency tends to be obtained.

(Second distillation step)
In the second distillation step, the dicyclopentadiene produced in the dimerization step is separated from other components and recovered. In the second distillation step, a high boiling point component may be further separated and recovered from the other components. The distillation can be performed by extractive distillation.

(Second recovery step)
In the second recovery step, isoprene is recovered from the non-recovered material in the first recovery step by extractive distillation.

In the manufacturing method of this embodiment, dicyclopentadiene and isoprene can be produced through the above steps.

<Dicyclopentadiene manufacturing equipment>
Next, an apparatus for producing dicyclopentadiene and isoprene according to an embodiment of the present disclosure and a method for producing dicyclopentadiene and isoprene using the same will be described with reference to the drawings. Fig. 1 is a flow diagram showing an example of an apparatus for producing dicyclopentadiene and isoprene for carrying out the method for producing dicyclopentadiene and isoprene according to an embodiment.

The dicyclopentadiene and isoprene production apparatus 100 shown in FIG. 1 comprises a separator 10, a dehydrogenation reactor 20, an isomerization reactor 30, a cyclization dehydrogenation reactor 40, a first distiller 50, a dimerization reactor 60, a second distiller 70, and an isoprene extractor 80, as well as flow paths L1 to L16 and L21 to L23 connected to these reactors.

When dicyclopentadiene and isoprene are produced using the production apparatus 100 shown in FIG. 1, first, the hydrocarbon mixture (first stream) is supplied to the separator 10 through the flow path L1, and separated into the second stream and the fourth stream at an arbitrary separation rate (separation process). As a result, a part of the first stream becomes the second stream, and the remainder becomes the fourth stream. The second stream is supplied to the dehydrogenation reactor 20 through the flow path L2, and a third stream having an enriched olefin ratio is obtained through the dehydrogenation process. Meanwhile, the fourth stream is supplied to the isomerization reactor 30 through the flow path L4, and a fifth stream having an increased ratio of normal isomers is obtained through the isomerization process. The fifth stream is supplied to the cyclization dehydrogenation reactor 40 through the flow path L5, and a sixth stream having at least a part of the normal isomers converted to cyclopentadiene (CPD) through the cyclization dehydrogenation process is obtained.

The third and sixth streams are joined through flow paths L3 and L6, respectively, to obtain a seventh stream obtained by mixing these. The seventh stream is supplied to the first distiller 50 through flow path L7, and the gas fraction (eighth stream) and the low boiling point component (ninth stream) of the C5 fraction produced by the dehydrogenation reaction in the dehydrogenation reactor 20 and the cyclization dehydrogenation reaction in the cyclization dehydrogenation reactor 40 are distilled and separated by the first distillation step to obtain a tenth stream enriched in cyclopentadiene. The tenth stream is supplied to the dimerization reactor 60 through flow path L10, and the cyclopentadiene contained in the tenth stream is converted to dicyclopentadiene (DCPD) by the Diels-Alder reaction to obtain an eleventh stream (dimerization step). The eleventh stream is supplied to the second distiller 70 through a flow path L11, and separated by a distillation operation into dicyclopentadiene (twelfth stream), a high boiling point component of the C5 fraction (thirteenth stream), and a fourteenth stream enriched in isoprene. The fourteenth stream is supplied to the isoprene extractor 80 through a flow path L14, and separated into isoprene (fifteenth stream) and other components (sixteenth stream). Through the above steps, dicyclopentadiene and isoprene are produced.

In the production apparatus 100 shown in FIG. 1, at least a portion of the low boiling point components distilled and separated in the first distiller 50 may be supplied to flow path L1 through flow path L21 as the 21st stream, mixed with the first stream, and supplied again to the separator 10. At least a portion of the components other than isoprene extracted in the isoprene extractor 80 may be supplied to flow path L1 through flow path L22 as the 22nd stream, mixed with the first stream, and supplied again to the separator 10. Furthermore, at least a portion of the components other than dicyclopentadiene distilled and separated in the second distiller 70 may be supplied to flow path L4 through flow path L23 as the 23rd stream, mixed with the fourth stream, and supplied again to the isomerization reactor 30.

In the production apparatus 100, the ratio between the amount of dicyclopentadiene recovered in the second distiller 70 and the amount of isoprene recovered in the isoprene extractor 80 can be controlled by controlling the ratio between the part and the remainder of the hydrocarbon mixture separated by the separator 10. That is, if it is desired to increase the proportion of isoprene produced according to the demand for dicyclopentadiene and isoprene, the proportion of the part of the hydrocarbon mixture can be increased and the supply amount of the second stream supplied to the isomerization reactor 30 can be increased. On the other hand, if it is desired to increase the proportion of dicyclopentadiene produced, the proportion of the remainder of the hydrocarbon mixture can be increased and the supply amount of the fourth stream supplied to the isomerization reactor 30 can be increased. Note that raw materials other than the part and the remainder of the hydrocarbon mixture may be added to the second stream and the fourth stream.

The dicyclopentadiene and isoprene production apparatus 200 shown in FIG. 2 comprises a separator 10, a dehydrogenation reactor 20, an isomerization cyclization dehydrogenation reactor 90, a first distiller 50, a dimerization reactor 60, a second distiller 70, and an isoprene extractor 80, as well as flow paths L1 to L4, L6 to L16, and L21 to L24 connected to these reactors.

When dicyclopentadiene and isoprene are produced using the production apparatus 200 shown in FIG. 2, dicyclopentadiene and isoprene can be produced in the same manner as when dicyclopentadiene and isoprene are produced using the production apparatus 100, except that the fourth stream is subjected to an isomerization cyclization dehydrogenation process in the isomerization cyclization dehydrogenation reactor 90 instead of the isomerization process in the isomerization reactor 30 and the cyclization dehydrogenation process in the cyclization dehydrogenation reactor 40. In addition, in the production apparatus 200 shown in FIG. 2, at least a portion of the low boiling point components distilled and separated in the first distiller 50 may be supplied to the flow path L1 through the flow path L21 as the 21st stream, mixed with the first stream, and supplied again to the separator 10. In addition, at least a portion of the components other than isoprene extracted in the isoprene extractor 80 may be supplied to the flow path L1 through the flow path L22 as the 22nd stream, mixed with the first stream, and supplied again to the separator 10. Furthermore, at least a portion of the components other than dicyclopentadiene separated by distillation in the second distiller 70 may be supplied as a 23rd stream through a flow path L23 to a flow path L4, mixed with the 4th stream, and supplied again to the isomerization cyclodehydrogenation reactor 90.

The dicyclopentadiene and isoprene production apparatus 300 shown in FIG. 3 comprises a separator 10, a dehydrogenation reactor 20, an isomerization reactor 30, a cyclization dehydrogenation reactor 40, a first distiller 50, a dimerization reactor 60, a second distiller 70, and an isoprene extractor 80, as well as flow paths L1 to L16 and L21 to L24 connected to these reactors.

When dicyclopentadiene and isoprene are produced using the production apparatus 300 shown in FIG. 3, the hydrocarbon mixture (first stream) is supplied to the dehydrogenation reactor 20 through flow paths L1 and L2, and a third stream enriched in olefin content is obtained through the dehydrogenation process. The third stream is supplied to the first distiller 50 through flow paths L3 and L7, and the gas component (eighth stream) and the low boiling point component (ninth stream) of the C5 fraction produced by the dehydrogenation reaction in the dehydrogenation reactor 20 are distilled and separated by the first distillation process to obtain a tenth stream enriched in cyclopentadiene content. At least a portion of the low boiling point component distilled and separated in the first distiller 50 is supplied to the flow path L24 through flow path L21 as the twenty-first stream. On the other hand, the tenth stream is supplied to the dimerization reactor 60 through flow path L10, and thereafter, dicyclopentadiene and isoprene are produced in the same manner as when the production apparatus 100 is used. At least a portion of the components other than isoprene extracted in the isoprene extractor 80 is supplied as a 22nd stream through flow path L22 to flow path L24. Then, the 21st stream and the 22nd stream join together to form a 24th stream, which is supplied to the separator 10 through flow path L24. In this embodiment, the 24th stream, which is a mixture of the 21st stream and the 22nd stream, becomes the hydrocarbon mixture supplied to the separator 10.

The 24th stream is then separated into a second stream and a fourth stream at an arbitrary separation ratio by separator 10, and thereafter dicyclopentadiene and isoprene are produced in the same manner as when production apparatus 100 is used.

In the manufacturing apparatus 300 shown in FIG. 3, the first stream may be supplied to flow path L1 after removing hydrocarbons having a carbon number of 6 or more and gasoline components by distillation separation.

In addition, in the manufacturing apparatus 300 shown in FIG. 3, at least a portion of the components other than dicyclopentadiene extracted in the second distiller 70 may be supplied to flow path L4 through flow path L23 as the 23rd stream, mixed with the fourth stream, and supplied again to the isomerization reactor 30.

The above describes a preferred embodiment of the present disclosure, but the present disclosure is not limited to the above embodiment.

The present disclosure will be explained in further detail below with reference to examples, but the present disclosure is not limited to these examples.

[Manufacturing conditions]
The conditions for each reactor when producing dicyclopentadiene and isoprene in the examples and comparative examples are shown below.
<Dehydrogenation Reactor>
Reaction temperature: 550° C.
Reaction pressure: -50 kPaG (51.3 kPa)
Reaction atmosphere: Hydrocarbon/Steam=1/3 (mass ratio)
WHSV:0.2h ^-1
<Isomerization Reactor>
Reaction temperature: 300° C.
Reaction pressure: 100 kPaG (201.3 kPa)
Reaction atmosphere: Hydrocarbon/hydrogen = 1/1 (mass ratio)
WHSV:5.0h ^-1
<Cyclization dehydrogenation reactor>
Reaction temperature: 500° C.
Reaction pressure: -50 kPaG (51.3 kPa)
Reaction atmosphere: Hydrocarbon/Hydrogen/Steam = 1/1/3 (mass ratio)
WHSV:1.0h ^-1
<Dimerization Reactor>
Reaction temperature: 90°C
Reaction pressure: 400 kPaG (501.3 kPa)
<Membrane separator>
A membrane separator having a silicalite membrane with mullite as a support as a separation membrane was used.

Example 1
A C5 fraction obtained by separating dienes from a steam cracker using naphtha as a raw material was used as a hydrocarbon mixture (first stream), and dicyclopentadiene and isoprene were produced by carrying out a separation step, a dehydrogenation step, an isomerization step, a cyclization dehydrogenation step, a first distillation step, a dimerization step, a second distillation step, and an isoprene extraction step using the production apparatus shown in Figure 1. The numbers of the flow paths L1 to L16 in Figure 1 correspond to the numbers of the streams passing through the corresponding flow paths. The production apparatus is not provided with flow paths L21 to L23.

The first stream was fed to the separator 10 through the flow path L1 and separated into the second stream and the fourth stream at an arbitrary separation rate (separation process). As a result, a part of the first stream was made into the second stream and the remainder was made into the fourth stream. The second stream was fed to the dehydrogenation reactor 20 through the flow path L2, and a dehydrogenation process was performed to obtain a third stream with an enriched olefin ratio. Meanwhile, the fourth stream was fed to the isomerization reactor 30 through the flow path L4, and an isomerization process was performed to obtain a fifth stream with an increased ratio of normal isomers. The fifth stream was fed to the cyclization dehydrogenation reactor 40 through the flow path L5, and a cyclization dehydrogenation process was performed to obtain a sixth stream in which a part of the normal isomers was converted into cyclopentadiene (CPD).

The third and sixth streams were joined through flow paths L3 and L6, respectively, to obtain a seventh stream in which they were mixed. The seventh stream was supplied to the first distiller 50 through flow path L7, and the gas fraction (eighth stream) and the low boiling point component (ninth stream) of the C5 fraction produced by the dehydrogenation reaction in the dehydrogenation reactor 20 and the cyclization dehydrogenation reaction in the cyclization dehydrogenation reactor 40 were distilled and separated in the first distillation step to obtain a tenth stream enriched in cyclopentadiene. The tenth stream was supplied to the dimerization reactor 60 through flow path L10, and the cyclopentadiene contained in the tenth stream was converted to dicyclopentadiene (DCPD) by the Diels-Alder reaction to obtain an eleventh stream (dimerization step). The 11th stream was supplied to the second distiller 70 through the flow path L11, and separated by a distillation operation into dicyclopentadiene (12th stream), a high boiling point component of the C5 fraction (13th stream), and a 14th stream enriched in isoprene. The 14th stream was supplied to the isoprene extractor 80 through the flow path L14, and separated into isoprene (15th stream) and other components (16th stream). Through the above steps, dicyclopentadiene and isoprene were produced.

The proportion of components contained in each stream and the relative flow rate of each stream are shown in Table 1. The relative flow rates shown in Table 1 indicate the flow rate of each stream when the ratio of the flow rate to the dehydrogenation reactor 20 to the inlet flow rate at the separator 10 (hereinafter referred to as the "separation ratio") is 0.5.

Table 2 shows the relationship between separation rate and each product yield when the separation rate is 0, 0.2, 0.5, 0.7, or 1.

(Comparative Example 1)
Dicyclopentadiene and isoprene were produced in the same manner as in Example 1, except that the isomerization reactor 30 was removed from the production apparatus shown in FIG. 1 and a production apparatus equipped with a membrane separator capable of separating iso isomers and normal isomers was used instead of the separator 10.

More specifically, the first stream, which is the same as that in Example 1, was fed to a membrane separator through flow path L1 and separated into a second stream consisting of isoforms and a fourth stream consisting of normal forms. The second stream was fed to a dehydrogenation reactor 20 through flow path L2, where a dehydrogenation process was carried out to obtain a third stream enriched in olefins. Meanwhile, the fourth stream was fed to a cyclization dehydrogenation reactor 40 through flow path L4, where a cyclization dehydrogenation process was carried out to obtain a sixth stream in which a portion of the normal forms was converted to cyclopentadiene (CPD). Thereafter, the same operations as in Example 1 were carried out. In Comparative Example 1, the fourth stream was fed to the cyclization dehydrogenation reactor 40, so there was no fifth stream. The numbers of flow paths L1 to L4 and L6 to L16 in FIG. 1 correspond to the numbers of the streams passing through the corresponding flow paths.

In the above process, the first stream is separated into a second stream consisting of iso-isomers and a fourth stream consisting of normal-isomers by a membrane separator, and the separation ratio is dependent on the hydrocarbon mixture and cannot be adjusted. Table 3 shows the proportions of the components in each stream and the relative flow rates of each stream.

Example 2
Dicyclopentadiene and isoprene were produced in the same manner as in Example 1, except that the C5 fraction obtained from the catalytic cracking unit was used as the hydrocarbon mixture (first stream). Table 4 shows the proportions of components contained in each stream and the relative flow rates of each stream. The relative flow rates shown in Table 4 indicate the flow rates of each stream when the separation rate is 0.5. Table 5 shows the relationship between the separation rate and the yield of each product when the separation rate is 0, 0.2, 0.5, 0.7, or 1.

(Comparative Example 2)
Dicyclopentadiene and isoprene were produced in the same manner as in Comparative Example 1, except that the C5 fraction obtained from the catalytic cracking unit was used as the hydrocarbon mixture (first stream). Table 6 shows the proportions of the components contained in each stream and the relative flow rates of each stream.

Example 3
The series of steps in the production method of Example 1 was set as the first cycle, and this series of steps was repeated. When the series of steps was repeated, 90 mass% of the 9th stream was supplied to the 21st stream, 90 mass% of the 13th stream was supplied to the 23rd stream, and 90 mass% of the 16th stream was supplied to the 22nd stream, thereby recycling the components. The 21st and 22nd streams were mixed with the 1st stream of the next cycle and supplied to the separator 10 as the 1' stream, and the 23rd stream was mixed with the 4th stream of the next cycle and supplied to the isomerization reactor 30 as the 4' stream. The series of steps was performed for 50 cycles or more, and it was confirmed that the components of each stream were stable.

Table 7 shows the proportion of components contained in each stream and the relative flow rate of each stream from the 50th cycle onwards when the components have stabilized. The relative flow rates shown in Table 7 indicate the flow rate of each stream when the ratio of the flow rate to the dehydrogenation reactor 20 to the inlet flow rate at the separator 10 (separation rate) is 0.5. Table 8 shows the relationship between the separation rate and each product yield when the separation rate is 0, 0.2, 0.5, 0.7 or 1. The results shown in Table 8 are for the case when the separation rate in all cycles is the value shown in the table.

Example 4
The series of steps in the production method of Example 2 was set as the first cycle, and this series of steps was repeated. When the series of steps was repeated, 90 mass% of the 9th stream was supplied to the 21st stream, 90 mass% of the 13th stream was supplied to the 23rd stream, and 90 mass% of the 16th stream was supplied to the 22nd stream, thereby recycling the components. The 21st and 22nd streams were mixed with the 1st stream of the next cycle and supplied to the separator 10 as the 1' stream, and the 23rd stream was mixed with the 4th stream of the next cycle and supplied to the isomerization reactor 30 as the 4' stream. The series of steps was performed for 50 cycles or more, and it was confirmed that the components of each stream were stable.

Table 9 shows the proportion of components contained in each stream and the relative flow rate of each stream from the 50th cycle onwards when the components have stabilized. The relative flow rates shown in Table 9 indicate the flow rate of each stream when the ratio of the flow rate to the dehydrogenation reactor 20 to the inlet flow rate at the separator 10 (separation rate) is 0.5. Table 10 shows the relationship between the separation rate and each product yield when the separation rate is 0, 0.2, 0.5, 0.7 or 1. The results shown in Table 10 are for the case where the separation rate in all cycles is the value shown in the table.

As is clear from the results shown in Tables 1 to 6, when the same hydrocarbon mixture is used, the production balance of dicyclopentadiene and isoprene cannot be adjusted in the production method of the comparative example, whereas it was confirmed that the production balance of dicyclopentadiene and isoprene can be adjusted by changing the separation rate in the production method of the example. Furthermore, as is clear from the results shown in Tables 7 to 10, it was confirmed that dicyclopentadiene and isoprene can be obtained in a stable and high yield (relative flow rate) by repeatedly performing a series of steps while recycling the components, and that the production balance of dicyclopentadiene and isoprene can be adjusted by changing the separation rate.

10...separator, 20...dehydrogenation reactor, 30...isomerization reactor, 40...cyclization dehydrogenation reactor, 50...first distillation reactor, 60...dimerization reactor, 70...second distillation reactor, 80...isoprene extractor, 90...isomerization cyclization dehydrogenation reactor, L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, L13, L14, L15, L16, L21, L22, L23, L24...flow path, 100, 200, 300...dicyclopentadiene and isoprene production apparatus.

Claims (4)

A separation step of separating a hydrocarbon mixture containing normal isomers and iso isomers of hydrocarbons having a carbon number of 5 into a part and a remainder;
a dehydrogenation step of dehydrogenating a first mixture comprising said portion of said hydrocarbon mixture to obtain a first product comprising isoprene;
an isomerization/cyclodehydrogenation step of isomerizing and cyclodehydrogenating a second mixture comprising the remainder of the hydrocarbon mixture to obtain a second product comprising cyclopentadiene;
a first recovery step of recovering dicyclopentadiene from a mixed product obtained by mixing the first product and the second product by dimerizing the cyclopentadiene and extractive distillation;
a second recovery step of recovering isoprene from the non-recovered product of the first recovery step by extractive distillation;
having
In the isomerization treatment, at least a portion of the iso isomer isomerized to a normal isomer. The method for producing dicyclopentadiene and isoprene according to claim 1, wherein the ratio between the amount of dicyclopentadiene recovered in the first recovery step and the amount of isoprene recovered in the second recovery step is controlled by controlling the ratio between the portion and the remainder of the hydrocarbon mixture. The method for producing dicyclopentadiene and isoprene according to claim 1 or 2, wherein the isomerization, cyclization, and dehydrogenation process is a process for producing the cyclopentadiene by contacting the second mixture with a catalyst having isomerization, cyclization, and dehydrogenation capabilities. The method for producing dicyclopentadiene and isoprene according to claim 1 or 2, wherein the isomerization, cyclization, and dehydrogenation process is a process for producing the cyclopentadiene by contacting the second mixture with a catalyst having isomerization ability and then with a catalyst having cyclization ability and dehydrogenation ability.

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