KR20210022870A - Method for preparing styrene and benzene - Google Patents

Abstract

The present invention relates to a method for preparing styrene and benzene. Provided is the method for preparing styrene and benzene, comprising the steps of: supplying a feed stream to a C6 separation column, supplying a top draw stream of a C6 separation column to a hydrodesulfurization process unit, and supplying a bottom draw stream to a C7 separation column; supplying the top draw stream from the C7 separation column to a dealkylation reaction unit, and supplying the bottom draw stream to a C8 separation column; recovering styrene from the C8 separation column top draw stream; and recovering benzene from the stream discharged from the hydrodesulfurization process unit and the dealkylation reaction unit.

Description

Method for producing styrene and benzene TECHNICAL FIELD [METHOD FOR PREPARING STYRENE AND BENZENE]

The present invention relates to a method for producing styrene and benzene, and more particularly, to a method for producing styrene and benzene in which energy is saved by simultaneously producing styrene and benzene.

The naphtha cracking process (Naphtha Cracking Center; hereinafter referred to as'NCC') thermally decomposes naphtha, a gasoline fraction, at a temperature of about 950°C to 1,050°C, resulting in ethylene, propylene, butylene, and basic raw materials for petrochemical products. It is a process that produces BTX (Benzene, Toluene, Xylene), etc.

Conventionally, benzene and styrene were prepared through separate processes using such naphtha as a raw material, using a by-product of the process of producing ethylene and propylene, such as pyrolysis gasoline (Raw Pyrolysis Gasoline, RPG).

The benzene manufacturing process is largely a hydrogen desulfurization process (Gasoline Hydrogenation, GHT), a line separation process (Prefraction, PF), an extraction distillation process (Extractive Distillation, EXT), and a dialkylation process (Hydrodealkylation, HDA) using an RPG raw material stream It was carried out including. In this case, by supplying the C7+ hydrocarbon from the raw material stream to the hydrodesulfurization process (GHT) without separate separation, there is a problem that the amount of hydrogen used increases due to an increase in the flow rate supplied to the hydrodesulfurization process (GHT). In addition, since the C6 hydrocarbon and the C7+ hydrocarbon are separated after the hydrodesulfurization process (GHT), and the C7+ hydrocarbon is subjected to a dialkylation reaction again, there is a problem that double energy is consumed.

In addition, the styrene extractive distillation process is a process of directly producing styrene from RPG through an extractive distillation (EXT) process.In order to separate C8 hydrocarbons before supplying RPG to EXT, RPG is used as C7-hydrocarbon, C8 Prefractionation (PF) steps of hydrocarbons and C9+ hydrocarbons are performed in advance. However, the separated C7- and C8 hydrocarbons are mixed again because they have to undergo a hydrodesulfurization process (GHT) step. After performing the GHT step, the C7- and C8 hydrocarbons are separated again. As such, performing the step of separating the C7- and C8 hydrocarbons twice leads to waste of cost and energy in the process. .

KR 2017-0018426 A

The problem to be solved in the present invention is to provide a method for producing energy-saving styrene and benzene in order to solve the problems mentioned in the technology behind the present invention.

That is, the present invention combines the conventional styrene extraction distillation process and the benzene production process in the production method of styrene and benzene, thereby omitting the line separation process in the benzene production process, thereby saving process energy, and By installing a C6 separation column in front of the hydrodesulfurization process unit, it is intended to provide a method for producing styrene and benzene that can further reduce process energy.

According to an embodiment of the present invention for solving the above problems, in the present invention, the raw material stream is supplied to the C6 separation column, the upper discharge stream of the C6 separation column is supplied to the hydrodesulfurization process unit, and the lower discharge stream is C7 separation. Supplying to the column; Supplying an upper discharge stream from the C7 separation column to a dialkylation reaction unit, and supplying a lower discharge stream to a C8 separation column; Recovering styrene from the C8 separation column overhead stream; And recovering benzene from the stream discharged from the hydrodesulfurization process unit and the dialkylation reaction unit.

According to the method for producing styrene and benzene of the present invention, by combining the styrene extraction distillation process and the benzene production process to produce styrene and benzene at the same time, the pre-separation process step in the benzene production process can be omitted.

In addition, by installing the C6 separation column in the benzene manufacturing process at the front of the hydrodesulfurization process unit and the second extractive distillation process unit in the styrene extractive distillation process, the RPG raw material stream supplied to the styrene extractive distillation process is greatly reduced, resulting in a styrene extractive distillation process. It can effectively reduce the energy used in

In addition, since the hydrodesulfurization reaction occurs in the dialkylation reaction unit, the toluene and xylene-rich stream separated in the styrene extraction distillation process is supplied to the dialkylation reaction unit without going through a separate hydrodesulfurization unit. In addition to the reaction, after the hydrodesulfurization reaction, benzene may be produced through the first extractive distillation process unit. Through this, the stream supplied to the hydrodesulfurization process unit may be reduced, thereby further reducing process energy.

1 is a flowchart illustrating a method for producing styrene and benzene according to an embodiment of the present invention.
2 is a process flow diagram according to a method for producing benzene according to Comparative Example 1.
3 is a flowchart illustrating a method of manufacturing styrene and benzene according to Comparative Example 2.

The terms or words used in the description and claims of the present invention should not be construed as being limited to a conventional or dictionary meaning, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term'stream' may mean the flow of fluid in the process, and may also mean the fluid itself flowing in the pipe. Specifically, the'stream' may mean both the fluid itself and the flow of the fluid flowing in a pipe connecting each device. In addition, the fluid may mean gas or liquid.

In the present invention, the term'C# hydrocarbons' in which'#' is a positive integer refers to all hydrocarbons having # carbon atoms. Thus, the term'C8 hydrocarbon' refers to a hydrocarbon compound having 8 carbon atoms. Also, the term'C#+ hydrocarbon' refers to all hydrocarbon molecules having # or more carbon atoms. Thus, the term'C9+ hydrocarbon' refers to a mixture of hydrocarbons having 9 or more carbon atoms. In addition, the term'C#-hydrocarbon' refers to all hydrocarbon molecules having # or fewer carbon atoms. Thus, the term'C7-hydrocarbon' refers to a mixture of hydrocarbons having up to 7 carbon atoms.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

According to the present invention, a method for producing styrene and benzene is provided. A method for producing styrene and benzene, comprising: feeding a raw material stream to a C6 separation column, feeding an upper discharge stream of the C6 separation column to a desulfurization reactor, and supplying a lower discharge stream to a C7 separation column; Supplying an upper discharge stream from the C7 separation column to a dialkylation reactor, and supplying a lower discharge stream to a C8 separation column; Recovering styrene from the C8 separation column overhead stream; And recovering benzene from the stream discharged from the desulfurization reactor and the dialkylation reactor.

According to an embodiment of the present invention, the raw material stream may include raw pyrolysis gasoline (RPG). The pyrolysis gasoline may be a by-product of a process of producing ethylene and propylene as a raw material of naphtha among units constituting a naphtha cracking center (NCC). As the raw material stream, the RPG may include at least one selected from the group consisting of PFO (Pyrolysis 　 Fuel 　 Oil) and PGO (Pyrolysis Gas Oil).

The PFO and PGO are process fuel oils and may be a mixture of C5+ hydrocarbons. For example, the C5+ hydrocarbon mixture is isopentane (Iso-Pentane), normal pentane (n-Pentane), 1,4-pentadiene (1,4-Pentadiene), dimethylacetylene (Dimethylacetylene), 1-pentene (1-Pentene), 3-methyl-1-butene (3-Methyl-1-butene), 2-methyl-1-butene (2-Methyl-1-butene), 2-methyl-2-butene (2- Methyl-2-butene), isoprene (Iso-Prene), trans-2-pentene (trans-2-Penstene), cis-2-pentene (cis-2-Penstene), trans-1,3-pentadiene (trans -1,3-Pentadiene), Cyclopentadiene, Cyclopentane, Cyclopentene,, Benzene, Toluene, Ethylbezene, m-xylene (m -xylene), o-xylene, p-xylene, styrene, dicyclopentadiene, indene, and indane It may include at least one selected.

The naphtha decomposition process thermally decomposes naphtha, a gasoline fraction, at a temperature of about 950°C to 1,050°C to produce ethylene, propylene, butylene, and BTX (Benzene, Toluene, Xylene), etc., which are basic raw materials for petrochemical products. It is a facility to do.

Among the processes constituting the conventional naphtha decomposition process, the benzene manufacturing process is to manufacture benzene using pyrolysis gasoline (RPG), and the process performed in the benzene manufacturing process is largely a hydrogenation desulfurization process (Gasoline Hydrogenation, GHT), and line separation. It may include a process (Prefractionation, PF), an extractive distillation process (Extractive Distillation, EXT), and a dialkylation process (Hydrodealkylation, HDA).

Among the above, the GHT process is a process of separating C5 hydrocarbons and C6+ hydrocarbons after hydrogenation and desulfurization reactions are performed using RPG as a raw material. Such a GHT process is performed in various ways. For example, the GHT process includes a primary GHT reactor in which a hydrogenation reaction proceeds; A C5 separation column in which C5 hydrocarbons are separated; A second GHT reactor in which the hydrogenation reaction proceeds; And a stripper through which the desulfurization reaction proceeds, in a manner that the RPG sequentially passes.

C5 hydrocarbons and C6+ hydrocarbons are produced through the GHT process, and the C6+ hydrocarbons are sent to the C6 separation column of the PF process. The unit performing the PF process consists of a C6 separation column and a C9 separation column. The raw material introduced from the GHT process is first introduced into a C6 separation column, where it is separated into C6 hydrocarbons and C7+ hydrocarbons. The C6 hydrocarbons are introduced into the EXT process, and the C7+ hydrocarbons are separated into C10+ hydrocarbons and C7 to C9 hydrocarbons in a C9 separation column, and the separated C7 to C9 hydrocarbons are introduced into the HDA process.

The EXT process is a process for producing benzene or the like from C6 hydrocarbons produced in the PF process, and the process is performed using equipment such as an extractor, a stripping device, and a recovery tower. In addition, the HDA process uses C7+ hydrocarbons introduced from the PF process as a raw material, and after producing benzene through a dialkylation reaction in a high-temperature and high-pressure reactor, it is introduced into the benzene separation tower together with the benzene produced in the EXT process. It is a process that produces benzene.

Conventional styrene extractive distillation process is a process that directly produces styrene from RPG through an extractive distillation (EXT) process.To separate C8 hydrocarbons before supplying RPG to EXT, RPG is converted to C7-hydrocarbons and C8 hydrocarbons. And a prefraction (PF) step of a C9+ hydrocarbon. However, the separated C7- and C8 hydrocarbons are mixed again because they have to undergo a hydrodesulfurization process (GHT) step. After performing the GHT step, the C7- and C8 hydrocarbons are separated again. As such, performing the step of separating the C7- and C8 hydrocarbons twice leads to waste of cost and energy in the process. .

As described above, in the related art, benzene and styrene were prepared through respective processes using RPG. On the other hand, in the manufacturing method of styrene and benzene according to the present invention, by combining the styrene extraction distillation process and the benzene manufacturing process to simultaneously manufacture styrene and benzene, the pre-separation (PF) process step in the benzene manufacturing process can be omitted. have. In addition, by installing the C6 separation column in the benzene manufacturing process at the front of the hydrodesulfurization process unit and the second extractive distillation process unit in the styrene extractive distillation process, the RPG raw material stream supplied to the styrene extractive distillation process is greatly reduced, resulting in a styrene extractive distillation process. It can effectively reduce the energy used in In addition, since the hydrodesulfurization reaction occurs in the dialkylation reaction unit, the toluene and xylene-rich stream separated in the styrene extraction distillation process is supplied to the dialkylation reaction unit without going through a separate hydrodesulfurization unit. In addition to the reaction, after the hydrodesulfurization reaction, benzene can be produced through the extraction distillation process part of the benzene production process. Through this, the stream supplied to the hydrodesulfurization process unit may be reduced, thereby further reducing process energy.

According to an embodiment of the present invention, a method for producing styrene and benzene may be described with reference to FIG. 1.

According to an embodiment of the present invention, the raw material stream (RPG FEED) is supplied to the C6 separation column (DeC6), the upper discharge stream of the C6 separation column (DeC6) is supplied to the hydrodesulfurization process unit 100, and the bottom is discharged. The stream can be fed to a C7 separation column (DeC7). In this case, the upper discharge stream of the C6 separation column (DeC6) may include C6-hydrocarbons, and the lower discharge stream may include C7+ hydrocarbons. Specifically, the upper discharge stream of the C6 separation column (DeC6) is benzene (Benzene), isopentane (Iso-Pentane), normal pentane (n-Pentane), 1,4-pentadiene (1,4-Pentadiene), dimethyl Acetylene (Dimethylacetylene), 1-pentene (1-Pentene), 3-methyl-1-butene (3-Methyl-1-butene), 2-methyl-1-butene (2-Methyl-1-butene), 2- Methyl-2-butene, Iso-Prene, trans-2-Penstene, cis-2-Penstene, trans- 1,3-pentadiene (trans-1,3-Pentadiene), cyclopentadiene (Cyclopentadiene), cyclopentane (Cyclopentane), may include cyclopentene (Cyclopentene), and the like. In addition, the lower discharge stream of the C6 separation column (DeC6) is toluene, ethylbenzene, m-xylene, o-xylene, and p-xylene. xylene), styrene, dicyclopentadiene, indene, indane, and the like.

According to an embodiment of the present invention, the hydrodesulfurization process unit may be a hydrodesulfurization reaction in the presence of separately supplied hydrogen and a catalyst in the upper discharge stream of the C6 separation column (DeC6) supplied. The catalyst may be a catalyst capable of selective hydrogenation. For example, the catalyst may include at least one selected from the group consisting of palladium, platinum, copper, and nickel. In some cases, the catalyst may be used by being supported on at least one carrier selected from the group consisting of gamma alumina, activated carbon, and zeolite.

As a specific example, the upper discharge stream of the C6 separation column (DeC6) containing the C6-hydrocarbon may be supplied to the hydrodesulfurization process unit 100 to undergo the above-described hydrodesulfurization process step. Specifically, the process step of the hydrodesulfurization process unit 100 includes a first GHT reactor in which a hydrogenation reaction is performed in the upper discharge stream of the C6 separation column (DeC6); A C5 separation column in which C5 hydrocarbons are separated; A second GHT reactor in which the hydrogenation reaction proceeds; And a stripper in which the desulfurization reaction proceeds.

While passing through the hydrodesulfurization process unit 100, impurities such as C5 hydrocarbons and fuel gas may be removed from the upper discharge stream of the C6 separation column (DeC6).

A raw material stream containing C5+ hydrocarbons may be additionally supplied to the hydrodesulfurization process unit 100. For example, the raw material stream containing C5+ hydrocarbons is a bottom discharge stream of a C4 separation column (not shown) in the NCC process, cyclopentadiene, pentadiene, isoprene, cyclopentene, 1-pentene, 3-methyl-1 -Butene, cyclopentane, 2-methyl-butene, normalpentane, benzene and C6 non-aromatic hydrocarbons. Conventionally, the lower discharge stream of the C4 separation column was mixed with the above-described RPG and supplied to the C6 separation column (DeC6). However, since the lower discharge stream of the C4 separation column contains benzene, but does not contain styrene, when supplied to the C6 separation column (DeC6), an unnecessary process is performed. Accordingly, in the present invention, the discharge stream below the C4 separation column is separately supplied to the hydrodesulfurization process unit 100 to reduce the flow rate supplied to the C6 separation column (DeC6), and energy can be saved by not going through unnecessary process steps. .

The stream discharged from the hydrodesulfurization process unit 100 may contain C6 aromatic hydrocarbons. As a specific example, the exhaust stream of the hydrodesulfurization process unit 100 may be a stream rich in benzene, which is supplied to the first extractive distillation process unit 200 and undergoes the above-described extraction (Extractive Distillation, EXT) process to benzene ( BZ Prod.) can be separated and recovered. Specifically, the EXT process may be performed using one or more devices such as an extractive distillation column, a stripping device, a solvent recovery column, and a separation column, while producing high-purity benzene. Specifically, the first extractive distillation process unit 200 may remove non-aromatic hydrocarbons and C7+ aromatic hydrocarbons from the supplied stream and separate benzene.

According to an embodiment of the present invention, the C6 separation column (DeC6) lower discharge stream including the C7+ hydrocarbon may be supplied to a C7 separation column (DeC7) to be separated into C7 hydrocarbons and C8+ hydrocarbons. Specifically, in the C7 separation column (DeC7), the upper discharge stream containing C7 hydrocarbons may be supplied to the dialkylation reaction unit 300, and the lower discharge stream containing C8+ hydrocarbons may be supplied to the C8 separation column (DeC8). have.

The upper discharge stream of the C7 separation column (DeC7) including the C7 hydrocarbon may be supplied to the dialkylation reaction unit 300 to undergo a dialkylation reaction. The upper discharge stream of the C7 separation column (DeC7) may include C7 aromatic hydrocarbons. The dialkylation reaction unit 300 may be a dialkylation reaction of a C7 aromatic hydrocarbon in the upper discharge stream of the supplied C7 separation column (DeC7) to produce benzene. The dialkylation reaction may be a reaction in which an alkyl group is removed from a benzene ring by adding hydrogen to an aromatic hydrocarbon containing an alkyl group. At this time, the upper discharge stream of the C7 separation column (DeC7) is a stream rich in toluene, and benzene can be produced by removing the alkyl group bonded to the benzene ring of the toluene while passing through the dialkylation reaction. .

The C7 separation column (DeC7) lower discharge stream containing the C8+ hydrocarbons may be fed to a C8 separation column (DeC8) to be separated into an upper discharge stream containing C8 hydrocarbons and a bottom discharge stream containing C9+ hydrocarbons. The separated C8 separation column (DeC8) upper discharge stream may include C8 aromatic hydrocarbons. As a specific example, the upper discharge stream of the C8 separation column (DeC8) may be a styrene-rich stream.

Styrene may be recovered from the upper discharge stream of the C8 separation column (DeC8). Specifically, the upper discharge stream of the styrene-rich C8 separation column (DeC8) is supplied to the second extractive distillation process unit 400 to separate and recover styrene (SM Product) through the above-described extraction (Extractive Distillation, EXT) process. can do. Specifically, the EXT process may be performed using one or more devices such as an extractive distillation column, a stripping device, a solvent recovery column, and a separation column, while producing high-purity styrene.

Styrene is separated in the second extractive distillation process unit 400, and the stream containing the remaining C8 aromatic hydrocarbons is supplied to the dialkylation unit 300 to undergo a dialkylation reaction. The dialkylation reaction unit 300 may be a dialkylation reaction of a supplied C8 aromatic hydrocarbon to produce benzene. At this time, the stream containing the C8 aromatic hydrocarbon may be a stream rich in xylene, and benzene can be produced by removing the alkyl group bonded to the benzene ring of the xylene while passing through the dialkylation reaction. have.

In the dialkylation reaction unit 300, the dialkylation reaction and the hydrodesulfurization reaction are simultaneously performed by the addition of hydrogen. Therefore, in order to separate styrene in the upper discharge stream of the C7 separation column (DeC7) and the second extractive distillation process unit 400 supplied to the dialkylation reaction unit 300 and use the remaining by-product stream to produce benzene, Without having to go through the hydrodesulfurization process unit 100, it is directly supplied to the dialkylation reaction unit 300 to perform the hydrodesulfurization reaction simultaneously with the dialkylation reaction, thereby reducing process cost.

The stream supplied to the dialkylation reaction unit 300 separates styrene from the upper discharge stream of the C7 separation column (DeC7) and the second extractive distillation unit 400, and in addition to the remaining by-product stream, the first extractive distillation unit ( Benzene is separated in 200), and a stream containing C7+ aromatic hydrocarbons among the remaining by-products may be further supplied.

The dialkylation reaction unit 300 discharge stream is mixed with the hydrodesulfurization process unit 100 discharge stream and supplied as a mixed stream to the first extractive distillation unit 200 to separate benzene while going through the EXT process step. I can. In this case, the mixed stream of the discharge stream of the hydrodesulfurization process unit 100 and the discharge stream of the dialkylation reaction unit 300 may include C6 aromatic hydrocarbons. More specifically, the mixed stream of the discharge stream of the hydrodesulfurization process unit 100 and the discharge stream of the dialkylation reaction unit 300 may contain benzene in high purity.

As described above, the method for producing styrene and benzene according to the present invention is shown in the description and drawings, but the description and drawings are described and illustrated only in the essential configuration for understanding the present invention, and are shown in the description and drawings. In addition to one process and apparatus, processes and apparatuses not separately described and not shown may be appropriately applied and used to carry out the method for producing styrene and benzene according to the present invention.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are intended to illustrate the present invention, and that various changes and modifications can be made within the scope of the present invention and the scope of the technical idea are obvious to those skilled in the art, and the scope of the present invention is not limited thereto.

Example

Example 1

With respect to the process flow diagram shown in FIG. 1, the process was simulated using the Aspen Plus simulator of Aspen. At this time, the supply flow rate of the RPG supplied to the C6 separation column (DeC6) was set to 78 ton/hr, and the RPG supply flow rate supplied to the hydrodesulfurization process unit 100 was set to 17.5 ton/hr.

As a result of the process simulation, the flow rate of the stream according to the process flow is shown in Table 1 below.

Stream Flow (ton/hr) Stream supplied from DeC6 to the hydrodesulfurization process 44.3 Stream supplied from the hydrodesulfurization process unit to the first extractive distillation process unit 50.4 Stream from DeC6 to DeC7 33.7 Stream supplied from DeC7 to the dialkylation reaction section 6.4 Stream from DeC7 to DeC8 22.4 Stream supplied from DeC8 to the second extractive distillation process unit 10.2 Stream supplied from the second extractive distillation process unit to the dialkylation reaction unit 4.9 Stream supplied from the dialkylation reaction section to the first extractive distillation process section 13.9 Stream supplied from the first extractive distillation process unit to the dialkylation reaction unit 7.0 Benzene stream separated in the first extractive distillation process unit 43.1 Styrene stream separated in the second extractive distillation process unit 5.0

Comparative example

Comparative Example 1

With respect to the process flow diagram shown in FIG. 2, the process was simulated using the Aspen Plus simulator of Aspen. At this time, the RPG supply flow rate supplied to the hydrodesulfurization process unit 100 was set to 93.0 ton/hr. 2, unlike in Example 1, the RPG stream is supplied to the hydrodesulfurization process unit 100, and the C5 hydrocarbons are separated from the hydrodesulfurization process unit 100 and then discharged from the hydrodesulfurization process unit 100. The resulting stream is subjected to a pre-separation process through a C6 separation column (DeC6) and a C9 separation column (DeC9). Specifically, an upper discharge stream containing C6 hydrocarbons from the C6 separation column is supplied to the first extractive distillation process unit 200, and a lower discharge stream containing C7+ hydrocarbons is supplied to the C9 separation column. In the C9 separation column, the lower discharge stream containing C9+ hydrocarbons is separated, and the upper discharge stream containing C7 to C8 hydrocarbons is supplied to the dialkylation reaction unit 300 to undergo a dialkylation reaction, and then the first extractive distillation process. It will be supplied to the government 200. The first extractive distillation process unit 200 separates benzene (BZ prod.) from the stream supplied from the C6 separation column (DeC6) and the dialkylation reaction unit 300. At this time, a stream containing C7+ hydrocarbons among the by-product streams from which benzene is separated in the first extractive distillation process unit 200 is supplied to the dialkylation reaction unit 300.

As a result of the process simulation, the flow rate of the stream according to the process flow is shown in Table 2 below.

Stream Flow (ton/hr) Stream supplied to DeC6 from the hydrodesulfurization process 83.3 Stream supplied from DeC6 to the first extractive distillation process unit 55.3 Stream from DeC6 to DeC9 28.0 Stream supplied from DeC9 to the dialkylation reaction section 13.7 Stream supplied from the dialkylation reaction section to the first extractive distillation process section 15.5 Stream supplied from the first extractive distillation process unit to the dialkylation reaction unit 7.0 Benzene stream separated in the first extractive distillation process unit 44.7

2 is a general benzene production process, in which a raw material stream is subjected to a hydrodesulfurization reaction, a pre-separation step and a dialkylation reaction step are performed to separate benzene through an extractive distillation process. In this case, referring to Table 2 above, The flow rate of the RPG stream supplied to the hydrodesulfurization process unit 100 is 83.3 ton/hr, which can be confirmed a lot compared to Example 1, which is 61.8 ton/hr. In addition, since the flow rate of the RPG stream supplied to the hydrodesulfurization process unit 100 does not pass through DeC6 as in Example 1, a large amount of C7+ hydrocarbons is contained. In this way, when a large amount of stream is supplied to the hydrodesulfurization process unit 100 to perform a hydrodesulfurization reaction, a large amount of energy is required.

In addition, since a large amount of C8 aromatic hydrocarbons are contained in the stream supplied to the first extractive distillation unit 200, there is a disadvantage in that energy consumption is large even in the extractive distillation process.

Comparative Example 2

With respect to the process flow diagram shown in FIG. 3, the process was simulated using the Aspen Plus simulator of Aspen. At this time, the supply flow rate of the RPG supplied to the C7 separation column (DeC7) was set to 78 ton/hr, and the RPG supply flow rate supplied to the hydrodesulfurization process unit 100 was set to 17.5 ton/hr. 3 is a general process configuration in which a styrene extraction distillation process is introduced into a benzene production process. 3, unlike in Example 1, the RPG stream is supplied to the C7 separation column (DeC7) instead of the C6 separation column (DeC6), and the upper discharge stream containing the C7-hydrocarbon in DeC7 is supplied to the hydrodesulfurization process unit ( 100), and the stream containing C8+ hydrocarbons is fed to a C8 separation column (DeC8). At this time, in the DeC6, the stream containing C6 is supplied to the first extractive distillation process unit 200, and the stream containing C7+ hydrocarbons undergoes a dialkylation reaction in the dialkylation reaction unit 300, and then the first It is supplied to the extractive distillation process unit 200, and the first extractive distillation process unit 200 separates benzene from the supplied stream.

In addition, the DeC7 lower discharge stream supplied to DeC8 recovers a stream containing C9+ hydrocarbons as a lower discharge stream, and the stream containing C8 hydrocarbons is supplied to the second extractive distillation process unit 400 to separate styrene. At this time, the second extractive distillation process unit 400 separates styrene and the stream containing C8+ aromatic hydrocarbons as the remaining by-products is not supplied to the dialkylation unit 300, but is mixed with the DeC7 upper discharge stream to be hydrogenated. It is supplied to the desulfurization process unit 100.

As a result of the process simulation, the flow rate of the stream according to the process flow is shown in Table 3 below.

Stream Flow (ton/hr) Stream supplied from DeC7 to the hydrodesulfurization process 55.6 Stream from DeC7 to DeC8 22.4 Stream supplied from DeC8 to the second extractive distillation process unit 10.2 Stream supplied from the second extractive distillation process unit to the hydrodesulfurization process unit 4.9 Stream supplied to DeC6 from the hydrodesulfurization process 66.6 Stream supplied from DeC6 to the first extractive distillation process unit 55.3 Stream supplied from DeC6 to the dialkylation reaction section 11.3 Stream supplied from the dialkylation reaction section to the first extractive distillation process section 13.9 Stream supplied from the first extractive distillation process unit to the dialkylation reaction unit 7.0 Benzene stream separated in the first extractive distillation process unit 43.1 Styrene stream separated in the second extractive distillation process unit 5.0

Referring to Table 3, it can be seen that the flow rate of the stream supplied to the C7 separation column (DeC7) to produce styrene is 78 ton/hr, compared to Example 1, which is 33.7 ton/hr. Through this, it can be seen that in the case of Example 1 compared to Comparative Example 2, energy for manufacturing styrene will be reduced. In addition, in the case of Comparative Example 2, the second extractive distillation process unit 400 used styrene. The stream containing C8+ aromatic hydrocarbons as a residual by-product after separation is not supplied to the dialkylation reaction unit 300, but is mixed with the DeC7 upper discharge stream and supplied to the hydrodesulfurization process unit 100. Accordingly, in the case of Comparative Example 2, it can be seen that the flow rate supplied from DeC7 to the hydrodesulfurization process unit 100 is 60.5 ton/hr, which is increased compared to Example 1, which is 44.3 ton/hr. Therefore, there is a problem that the use of hydrogen is increased in the hydrodesulfurization process unit 100.

In addition, in the case of Comparative Example 2, the discharge stream of the hydrodesulfurization process unit 100 requires a step for additionally separating C6 hydrocarbons and C7+ hydrocarbons in a C6 separation unit (DeC6), and the DeC6 bottom containing the separated DeC7+ hydrocarbons The discharge stream undergoes a dialkylation reaction in the dialkylation reaction unit 300. In this case, the DeC6 separation column is not installed at the front end of the hydrodesulfurization reaction unit 100, but is installed at the rear end, and the flow rate of the stream going through the unnecessary separation step and the hydrodesulfurization step increases, thereby reducing waste of energy in the process Will result.

100: hydrodesulfurization process unit 200: first extractive distillation process unit
300: dialkylation reaction unit 400: second extractive distillation process unit
DeC6: C6 separation unit DeC7: C7 separation unit
DeC8: C8 separation unit DeC9: C9 separation unit

Claims (11)

Supplying the raw material stream to the C6 separation column, the upper discharge stream of the C6 separation column to the hydrodesulfurization process unit, and the lower discharge stream to the C7 separation column;
Supplying an upper discharge stream from the C7 separation column to a dialkylation reaction unit, and supplying a lower discharge stream to a C8 separation column;
Recovering styrene from the C8 separation column overhead stream; And
The method for producing styrene and benzene comprising the step of recovering benzene from the stream discharged from the hydrodesulfurization process unit and the dialkylation reaction unit. The method of claim 1,
The method for producing styrene and benzene, wherein the C8 separation column upper discharge stream contains C8 aromatic hydrocarbons. The method of claim 1,
The C7 separation column upper discharge stream is a method for producing styrene and benzene containing C7 aromatic hydrocarbons. The method of claim 1,
Separating benzene from the stream discharged from the hydrodesulfurization process unit and the dialkylation reaction unit,
A method for producing styrene and benzene to separate benzene by supplying a mixed stream of the hydrodesulfurization process part discharge stream and the dialkylation reaction part discharge stream to the first extractive distillation process part. The method of claim 4,
The mixed stream of the hydrodesulfurization process unit discharge stream and the dialkylation reaction unit discharge stream contains C6 aromatic hydrocarbons. The method of claim 1,
The step of recovering styrene from the C8 separation column upper discharge stream,
The method for producing styrene and benzene to separate styrene by supplying the upper discharge stream of the C8 separation column to a second extractive distillation process unit. The method of claim 6,
Styrene is separated in the second extractive distillation process unit, and the stream containing the remaining C8 aromatic hydrocarbons is supplied to the dialkylation reaction unit. The method of claim 1,
A method for producing styrene and benzene, wherein a raw material stream containing C5+ hydrocarbons is additionally supplied to the hydrodesulfurization process unit. The method of claim 1,
The hydrodesulfurization process unit is a method for producing styrene and benzene to perform a hydrodesulfurization reaction in the presence of hydrogen and a catalyst separately supplied to the supplied stream. The method of claim 1,
The dialkylation reaction unit is a method for producing styrene and benzene by dialkylating an aromatic hydrocarbon in the supplied stream to produce benzene. The method of claim 1,
The process for producing styrene and benzene, wherein the feed stream comprises pyrolysis gasoline.

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