KR20210035452A - Method for preparing propylene - Google Patents

Abstract

The present invention relates to a method for preparing propylene, including the steps of: supplying a C4 mixture stream containing n-butane, i-butane, 1,3-butadiene, 1-butene, and 2-butene to a hydrogenation reactor to convert the 1,3-butadiene into the 1-butene and the 1-butene into the 2-butene; supplying the stream discharged from the hydrogenation reactor to a first distillation column to separate propane from the top discharge stream, and supplying the bottom discharge stream to a metathesis reactor; producing propylene from the bottom discharge stream supplied from the first distillation column and a separately supplied ethylene stream in the metathesis reactor; supplying the stream discharged from the metathesis reactor to a second distillation column to separate the unreacted ethylene stream from the top discharge stream, and supplying the bottom discharge stream to a third distillation column; and receiving the bottom discharge stream of the second distillation column, separating propylene from the top discharge stream, and supplying the bottom discharge stream containing the unreacted C4 mixture to the hydrogen reactor.

Description

Propylene production method {METHOD FOR PREPARING PROPYLENE}

The present invention relates to a process for producing propylene, and more particularly to a process for producing propylene from a C4 mixture stream.

Naphtha pyrolysis is a method of breaking the carbon-carbon ring by applying heat of 1,000 ℃ or more by supplying naphtha with steam at high temperature, and to produce by-products such as ethylene, propylene, butadiene and BTX (Benzene-Toluene-Xylene mixture). Is used.

Here, the C4 hydrocarbon mixture (raw C4) containing a single bond, a double bond, or a triple bond, including butadiene, is separated from each other through a series of purification processes.

Specifically, 1,3-butadiene, which is useful as a raw material for synthetic rubber, is first separated from the C4 hydrocarbon mixture (raw C4) by extraction or extractive distillation. Raffinate-1 remaining after 1,3-butadiene is removed from the mixture of the C4 hydrocarbon compound (raw C4) is a trace amount of 1,3-butadiene, isobutene, 1-butene, 2-butene, n-butane and Contains i-butane.

When the raffinate-1 is reacted with methanol, isobutene and methanol react with each other to form methyl tertiary butyl ether (MTBE), and by separating MTBE from raffinate-1, raffinate-1 Isobutene is separated at After isobutene is removed from the raffinate-1, the remaining raffinate-2 contains 1-butene, 2-butene, n-butane, i-butane, and trace amounts of 1,3-butadiene.

Raffinate-2 containing, 1-butene, 2-butene, n-butane, i-butane and trace amounts of 1,3-butadiene can be used for various purposes, as one of which, metathesis (METHATHESIS) Through it can be used for the purpose of producing propylene.

Conventionally, in order to prepare propylene using the raffinate-2 stream, 1-butene in the stream was converted to 2-butene to increase the content of 2-butene, and then reacted with ethylene in a metathesis reactor to prepare propylene. Then, the propylene was separated, and the streams containing the unreacted C4 compound and the unreacted ethylene were circulated to each of the metathesis reactors to participate in the metathesis reaction again.

However, when a by-product is generated in the metathesis reactor and the unreacted C4 compound stream containing the by-product is circulated to the metathesis reactor, it acts as a catalyst poison in the metathesis reactor, thereby deteriorating catalyst performance in the metathesis reactor.

JP 2008-519033 A

The problem to be solved in the present invention includes 1-butene, 2-butene, n-butane, i-butane and trace amounts of 1,3-butadiene in order to solve the problems mentioned in the technology behind the background of the invention. It is to provide a method for producing propylene in high purity from a raffinate-2 stream.

That is, according to the present invention, by removing impurities that act as catalyst poisons in the conventional metathesis reactor to reduce catalyst performance in the metathesis reactor, and removing propane, propylene can be produced with high purity.

According to an embodiment of the present invention for solving the above problems, a C4 mixture stream containing the present n-butane, i-butane, 1,3-butadiene, 1-butene and 2-butene is supplied to a hydrogenation reactor. Converting 1,3-butadiene to 1-butene and 1-butene to 2-butene; Supplying the hydrogenation reactor discharge stream to a first distillation column to separate propane from the upper discharge stream, and supplying the lower discharge stream to the metathesis reactor; In the metathesis reactor, producing propylene from an ethylene stream supplied separately from the supplied hydrogenation reactor effluent stream; Supplying the metathesis reactor discharge stream to a second distillation column to separate an unreacted ethylene stream from an upper discharge stream, and supplying a lower discharge stream to a third distillation column; And receiving the second distillation column lower discharge stream, separating propylene from the upper discharge stream, and supplying a lower discharge stream containing an unreacted C4 mixture to a hydrogenation reactor.

According to the method for producing propylene of the present invention, propylene is produced through metathesis reaction of an ethylene stream and a C4 mixture stream comprising 1-butene, 2-butene, n-butane, i-butane and trace amounts of 1,3-butadiene. , The unreacted C4 mixture stream contained in the metathesis reactor discharge stream in which the metathesis reaction has been completed is circulated to a hydrogenation reactor rather than a metathesis reactor to contain 1,3-butadiene, which is contained in an unreacted C4 mixture stream and acts as a catalyst poison of the metathesis reactor. Can be removed.

In addition, the present invention provides propane produced by hydrogenation of propylene contained in trace amounts in the unreacted C4 mixture stream in the process of hydrogenating the unreacted C4 mixture stream by circulating the unreacted C4 mixture stream to the hydrogenation reactor by installing a first distillation column at the rear end of the hydrogenation reactor. By removing, propylene can be separated and recovered with high purity in the third distillation column.

1 is a process flow diagram according to a method for producing propylene according to an embodiment of the present invention.
2 is a process flow diagram according to the method for producing propylene according to Comparative Example 1.
3 is a process flow diagram according to the method for producing propylene according to Comparative Example 2.

Terms and words used in the description and claims of the present invention should not be construed as being limited to their usual or dictionary meanings, 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# mixture' in which'#' is a positive integer refers to a mixture containing all hydrocarbons having # carbon atoms. Thus, the term'C4 mixture' refers to a mixture comprising a hydrocarbon compound having 4 carbon atoms.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1 to aid in understanding the present invention.

According to the present invention, a method for producing propylene is provided. As a method for producing propylene, a C4 mixture stream containing n-butane, i-butane, 1,3-butadiene, 1-butene and 2-butene is supplied to a hydrogenation reactor 100 to obtain 1,3-butadiene. Converting to butene and converting 1-butene to 2-butene; Supplying the hydrogenation reactor 100 discharge stream to the first distillation column 200 to separate propane from the upper discharge stream, and supplying the lower discharge stream to the metathesis reactor 300; In the metathesis reactor 300, producing propylene from an ethylene stream supplied separately from the supplied first distillation column 200 bottom discharge stream; Supplying the metathesis reactor 300 discharge stream to the second distillation column 400 to separate the unreacted ethylene stream from the upper discharge stream, and supplying the lower discharge stream to the third distillation column 500; And receiving the lower discharge stream of the second distillation column 400, separating propylene from the upper discharge stream, and supplying the lower discharge stream containing the unreacted C4 mixture to the hydrogenation reactor 100. A manufacturing method can be provided.

According to an embodiment of the present invention, the C4 mixture stream may be a raffinate-2 stream separated from a Naphtha Cracking Center (NCC).

The naphtha pyrolysis is a method of breaking the carbon-carbon ring by applying heat of 1,000° C. or higher by supplying naphtha together with steam at a high temperature to produce by-products such as ethylene, propylene, butadiene and BTX (Benzene-Toluene-Xylene mixture). Can be used for.

Here, including butadiene, a C4 hydrocarbon mixture (raw C4) including a single bond, a double bond, or a triple bond may be separated from each other through a series of purification processes.

Specifically, 1,3-butadiene, which is useful as a raw material for synthetic rubber, is first separated from the C4 hydrocarbon mixture (raw C4) by extraction or extractive distillation. Raffinate-1 remaining after 1,3-butadiene is removed from the mixture of the C4 hydrocarbon compound (raw C4) is a trace amount of 1,3-butadiene, isobutene, 1-butene, 2-butene, n-butane and i-butane.

When the raffinate-1 is reacted with methanol, isobutene and methanol react with each other to form methyl tertiary butyl ether (MTBE), and by separating MTBE from raffinate-1, raffinate-1 Isobutene is separated at Raffinate-2 remaining after isobutene is removed from raffinate-1 may include 1-butene, 2-butene, n-butane, i-butane, and trace amounts of 1,3-butadiene. At this time, n-butane and i-butane act as inert substances that do not participate in the metathesis reaction.

According to an embodiment of the present invention, the content of 1-butene contained in the C4 mixture stream is 30% to 60% by weight, the content of 2-butene is 10% to 40% by weight, 1,3- The content of butadiene may be 1% by weight or less. For example, the content of 1-butene contained in the C4 mixture stream is 30% to 55% by weight, 35% to 55% by weight or 40% to 50% by weight, and the content of 2-butene is 10% by weight. % To 35% by weight, 15% to 35% by weight, or 20% to 30% by weight.

1,3-butadiene contained in an amount of 1% by weight or less in the C4 mixture stream acts as a catalyst poison in the metathesis reactor 300 for producing propylene through a metathesis reaction of 2-butene and ethylene, preventing conversion to propylene. can do.

In addition, the content of 1-butene contained in the C4 mixture stream is 30% by weight to 60% by weight, and in order to increase the n-butene conversion rate in the metathesis reactor 300, it is necessary to convert 1-butene into 2-butene. desirable.

In contrast, in the present invention, before supplying the C4 mixture stream to the metathesis reactor 300, the C4 mixture stream is supplied to the hydrogenation reactor 100 to convert 1,3-butadiene into 1-butene, and 1-butene. Conversion to 2-butene may be included. Through this, 1,3-butadiene contained in a trace amount in the C4 mixture stream is removed, and the purity of 2-butene is improved, thereby improving propylene production.

The hydrogenation reactor 100 may convert 1,3-butadiene contained in the C4 mixture stream into selective 1-butene and convert 1-butene into 2-butene through a hydrogenation reaction. For example, the hydrogenation reaction temperature is in the range of 30 ℃ to 120 ℃, 40 ℃ to 100 ℃ or 50 ℃ to 80 ℃, the reaction pressure is in the range of 5 KG to 40 KG, 5 KG to 30 KG or 5 KG to 20 KG Can be

According to an embodiment of the present invention, by supplying the C4 mixture stream to the hydrogenation reactor 100 to convert 1,3-butadiene into 1-butene, the content of 1,3-butadiene in the discharge stream of the hydrogenation reactor 100 May be less than or equal to 0.1% by weight. For example, the content of 1,3-butadiene in the discharge stream of the hydrogenation reactor 100 may be 0 wt% to 0.1 wt%, 0 wt% to 0.01 wt%, or 0 wt% to 0.001 wt%. By producing propylene from a C4 mixture stream containing 1,3-butadiene within the above range, high purity 1-butene and high conversion propylene can be produced. For example, the content of 1-butene in the discharge stream of the hydrogenation reactor 100 may be 20% to 50% by weight, 25% to 45% by weight, or 30% to 40% by weight. In addition, the content of 2-butene in the discharge stream of the hydrogenation reactor 100 may be 20% to 50% by weight, 25% to 45% by weight, or 30% to 40% by weight.

As such, before producing propylene, a C4 mixture stream is supplied to the hydrogenation reactor 100 to convert 1,3-butadiene, which is a catalyst poison, to 1-butene, and 1-butene to 2-butene, thereby 1,3 -In addition to the effect of removing butadiene, the effect of increasing the content of 2-butene can be realized.

In the hydrogenation reactor 100, the unreacted C4 mixture is recycled from the lower discharge stream of the third distillation column 500 to be described later, and the unreacted C4 mixture stream contains a trace amount of propylene produced through metathesis reaction. . As such, when the unreacted C4 mixture stream containing a trace amount of propylene is circulated to the hydrogenation reactor 100, the propylene is converted to propane.

The content of propane in the discharge stream of the hydrogenation reactor 100 may be 0.5% to 6% by weight. For example, the content of propane in the discharge stream of the hydrogenation reactor 100 may be 0.5% to 5.5% by weight, 0.5% to 5% by weight, or 0.5% to 4% by weight. As described above, since propane contained in the discharge stream of the hydrogenation reactor 100 is difficult to separate through distillation from propylene, it must be removed before the third distillation column 500 in order to separate propylene with high purity.

According to an embodiment of the present invention, propane may be separated by supplying the discharge stream of the hydrogenation reactor 100 to the first distillation column 200. Specifically, in the first distillation column 200, propane contained in the discharge stream of the hydrogenation reactor 100 is separated and removed from the upper discharge stream, and the lower discharge stream from which the propane is removed is transferred to the metathesis reactor 300. Can supply.

The content of propane in the lower discharge stream of the first distillation column 200 may be 0% to 1% by weight. For example, the content of propane in the lower discharge stream of the first distillation column 200 may be 0 wt% to 0.8 wt%, 0 wt% to 0.5 wt%, or 0 wt% to 0.1 wt%. In this way, propylene is produced by supplying the lower discharge stream of the first distillation column 200 from which propane is removed to the metathesis reactor 300, and high purity through the second distillation column 400 and the third distillation column 500 Propylene can be separated.

The operating pressure of the first distillation column 200 may be 1 KG to 20 KG. For example, the operating pressure of the first distillation column 200 may be 1 KG to 17 KG, 1 KG to 15 KG, or 1 KG to 10 KG. By operating the first distillation column 200 at a pressure within the above range, propane may be selectively separated.

In addition, the operating temperature of the first distillation column 200 may be 30 ℃ to 90 ℃. For example, the operating temperature of the first distillation column 200 may be 30 °C to 80 °C, 35 °C to 80 °C, or 40 °C to 70 °C. By operating the first distillation column 200 at a temperature within the above range, propane may be selectively separated.

According to an embodiment of the present invention, the lower discharge stream of the first distillation column 200 is supplied to the metathesis reactor 300 to metathesis reaction with an ethylene stream separately supplied to the metathesis reactor 300 to produce propylene. Can be manufactured.

The metathesis reaction may be carried out under heterogeneous conditions. In some cases, the metathesis reaction may be carried out under pressure. For example, the metathesis reaction may be carried out at a pressure in the range of 1 KG to 100 KG, 5 KG to 70 KG, or 10 KG to 50 KG. In addition, the metathesis reaction may be carried out at a temperature in the range of 250°C to 500°C, 250°C to 400°C, or 250°C to 350°C.

In the metathesis reactor, a metathesis reaction and an isomerization reaction may be performed simultaneously. Specifically, propylene may be produced from the lower discharge stream of the first distillation column 200 and the ethylene stream through a metathesis reaction, and 1-butene may be converted to 2-butene through an isomerization reaction to participate in the metathesis reaction.

A catalyst for accelerating each of the metathesis reaction and isomerization reaction may be filled in the metathesis reactor. The catalyst may include, for example, at least one selected from the group consisting of a transition metal and an oxide thereof. The transition metal may include, for example, tungsten, molybdenum, and rhenium. As a specific example, tungsten trioxide (WO ₃ ) may be included as a catalyst for the metathesis reaction, and magnesium oxide (MgO) may be included as a catalyst for the isomerization reaction.

In some cases, the catalyst may be used in a form supported on a silica carrier.

In addition, depending on the case, a diluent that is inert under the reaction conditions can be used. The diluent may include, for example, a paraffinic or cycloparaffinic hydrocarbon.

Conventionally, in order to improve the propylene production, the unreacted C4 mixture from the lower discharge stream of the third distillation column 500 was recycled to the metathesis reactor 300. Accordingly, a by-product is generated in the metathesis reactor 300, and the unreacted C4 mixture stream containing the by-product is circulated to the metathesis reactor 300 to act as a catalyst poison in the metathesis reactor 300, and thus the metathesis reactor 300 ) There was a problem of deteriorating the catalyst performance. In contrast, the present invention uses the hydrogenation reactor 100 and the first distillation column 200 to convert a trace amount of 1,3-butadiene into 1-butene from an unreacted C4 mixture stream to generate from 1,3-butadiene. By solving the catalyst poison problem and removing propane, propylene can be produced with high purity.

According to an embodiment of the present invention, the discharge stream of the metathesis reactor 300 is supplied to the second distillation column 400, and the unreacted ethylene stream from the upper discharge stream is distilled in the second distillation column 400. Separated, the bottom discharge stream may be supplied to the third distillation column (500).

The operating pressure of the second distillation column 400 may be 1 KG to 50 KG. For example, the operating pressure of the second distillation column 400 may be 10 KG to 50 KG, 10 KG to 40 KG, or 20 KG to 30 KG. By operating the second distillation column 400 at a pressure within the above range, unreacted ethylene may be selectively separated from the upper discharge stream.

In addition, the operating temperature of the second distillation column 400 may be 10 °C to 200 °C. For example, the operating temperature of the second distillation column 400 may be 10 °C to 150 °C, 10 °C to 130 °C, or 20 °C to 100 °C. By operating the second distillation column 400 at a temperature within the above range, unreacted ethylene can be selectively separated from the upper discharge stream.

The upper discharge stream of the second distillation column 400 may be recycled to the metathesis reactor 300. Specifically, the upper discharge stream of the second distillation column 400 containing unreacted ethylene may be supplied to the metathesis reactor 300 and may be used for metathesis reaction with 2-butene to produce propylene. In this way, by reusing the unreacted ethylene, it is possible to reduce the manufacturing cost.

According to an embodiment of the present invention, the lower discharge stream of the second distillation column 400 is supplied to the third distillation column 500, and propylene is separated from the upper discharge stream through distillation in the third distillation column 500. And, it is possible to separate the unreacted C4 mixture from the bottoms effluent stream.

The operating pressure of the third distillation column 500 may be 1 KG to 50 KG. For example, the operating pressure of the third distillation column 500 may be 1 KG to 40 KG, 1 KG to 30 KG, or 10 KG to 20 KG. By operating the third distillation column 500 at a pressure within the above range, propylene can be separated from the upper discharge stream with high purity.

In addition, the operating temperature of the third distillation column 500 may be 10 °C to 200 °C. For example, the operating temperature of the third distillation column 500 may be 20°C to 150°C, 30°C to 130°C, or 40°C to 110°C. By operating the third distillation column 500 at a temperature within the above range, propylene can be separated from the upper discharge stream with high purity.

The content of propylene in the upper discharge stream of the third distillation column 500 may be 95% by weight or more. For example, the content of propylene in the upper discharge stream of the third distillation column 500 may be 95% by weight to 100% by weight, 96% by weight to 100% by weight, or 97% by weight to 100% by weight. By separating the upper discharge stream of the third distillation column 500 containing propylene in an amount within the above range, high purity propylene may be provided.

The lower discharge stream of the third distillation column 500 may be supplied to the hydrogenation reactor 100 as a stream containing an unreacted C4 mixture.

The content of propylene in the unreacted C4 mixture stream may be 0.1% to 10% by weight. For example, the content of propylene in the unreacted C4 mixture stream may be 0.1 wt% to 9 wt%, 0.1 wt% to 8 wt%, or 0.1 wt% to 6 wt%. When the unreacted C4 mixture stream containing propylene in the above range is supplied to the hydrogenation reactor 100, the propylene is converted to propane and thus separation from propylene is difficult, but in the present invention, as described above, the hydrogenation reactor ( 100) The above problem was solved by removing the propane by installing the first distillation column 200 at the rear end.

Above, although the method for producing propylene according to the present invention is shown in the drawings, the description and drawings are described and illustrated only essential configurations for understanding the present invention, in addition to the processes and apparatuses shown in the description and drawings. , Processes and devices not separately described and not shown may be appropriately applied and used to carry out the method for producing propylene 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 AspenPlus simulator of AspenTech.

Specifically, a C4 mixture stream (C4 Raffinate-2) containing 1-butene, 2-butene, n-butane, i-butane and a trace amount of 1,3-butadiene is supplied to the hydrogenation reactor 100 to obtain a trace amount of 1 ,3-butadiene was converted to 1-butene and 1-butene was converted to 2-butene.

The discharge stream of the hydrogenation reactor 100 was supplied to the first distillation column 200, propane was separated from the upper discharge stream of the first distillation column 200, and the lower discharge stream was transferred to the metathesis reactor 300. Supplied. At this time, it was confirmed that the content of propane in the lower discharge stream of the first distillation column 200 was 0.1% by weight or less.

In the metathesis reactor 300, propylene was produced by reacting a separately supplied ethylene stream (Ethylene) with 2-butene in the lower discharge stream of the first distillation column 200. At this time, the isomerization reaction in which 1-butene is converted to 2-butene in the metathesis reactor 300 was also carried out.

The discharge stream of the metathesis reactor 300 in which the reaction was completed was supplied to the second distillation column 400 to separate unreacted ethylene from the upper discharge stream and recycled to the metathesis reactor 300. In addition, the lower discharge stream of the second distillation column 400 was supplied to the third distillation column 500.

The third distillation column 500 receives the lower discharge stream of the second distillation column 400, separates propylene from the upper discharge stream, and partially unreacted C4 mixture stream (Recycle C4) from the lower discharge stream. After purging, it was recycled to the hydrogenation reactor (100). In this case, when the C4 mixture stream and the unreacted C4 mixture stream are subjected to hydrogenation in the hydrogenation reactor 100 and then discharged, the content of 1,3-butadiene in the discharge stream of the hydrogenation reactor 100 is 0.001% by weight or less. Confirmed.

At this time, the flow rate of C4 Raffinate-2 supplied to the hydrogenation reactor 100 is 40.0 ton/hr, the flow rate of the stream supplied to the first distillation column 200 is 40.0 ton/hr, and the metathesis reactor 300 The flow rate of the supplied stream is 39.0 ton/hr, the flow rate of the ethylene stream supplied to the metathesis reactor 300 is 12.9 ton/hr, and Recycle C4 recycled from the third distillation column 500 to the hydrogenation reactor 100 The flow rate was confirmed as 11.0 ton/hr.

Comparative example

Comparative Example 1

With respect to the process flow diagram shown in FIG. 2, the process was simulated using the AspenPlus simulator of AspenTech.

Specifically, a C4 mixture stream (C4 Raffinate-2) containing 1-butene, 2-butene, n-butane, i-butane and a trace amount of 1,3-butadiene is supplied to the hydrogenation reactor 100 to obtain a trace amount of 1 ,3-butadiene was converted to 1-butene and 1-butene was converted to 2-butene.

The hydrogenation reactor 100 discharge stream was fed to the metathesis reactor 300.

In the metathesis reactor 300, propylene was produced by reacting a separately supplied ethylene stream (Ethylene) with 2-butene in the discharge stream of the hydrogenation reactor 100. At this time, the isomerization reaction in which 1-butene is converted to 2-butene in the metathesis reactor 300 was also carried out.

The discharge stream of the metathesis reactor 300 in which the reaction was completed was supplied to the second distillation column 400 to separate unreacted ethylene from the upper discharge stream and recycled to the metathesis reactor 300. In addition, the lower discharge stream of the second distillation column 400 was supplied to the third distillation column 500.

The third distillation column 500 receives the lower discharge stream of the second distillation column 400, separates propylene from the upper discharge stream, and partially unreacted C4 mixture stream (Recycle C4) from the lower discharge stream. After purging, it was recycled to the metathesis reactor 300. At this time, it was confirmed that the content of 1,3-butadiene in the unreacted C4 mixture stream supplied to the metathesis reactor 300 was 0.1% by weight.

At this time, the flow rate of C4 Raffinate-2 supplied to the hydrogenation reactor 100 is 40.0 ton/hr, the flow rate of the stream supplied to the metathesis reactor 300 is 40.0 ton/hr, and the flow rate supplied to the metathesis reactor 300 The flow rate of the ethylene stream was 12.2 ton/hr, and the flow rate of Recycle C4 recycled from the third distillation column 500 to the metathesis reactor 300 was 10.0 ton/hr.

Comparative Example 2

With respect to the process flow diagram shown in FIG. 3, the process was simulated using the AspenPlus simulator of AspenTech.

Specifically, a C4 mixture stream (C4 Raffinate-2) containing 1-butene, 2-butene, n-butane, i-butane and a trace amount of 1,3-butadiene is supplied to the hydrogenation reactor 100 to obtain a trace amount of 1 ,3-butadiene was converted to 1-butene and 1-butene was converted to 2-butene.

The hydrogenation reactor 100 discharge stream was fed to the metathesis reactor 300. At this time, it was confirmed that the content of propane in the discharge stream of the hydrogenation reactor 100 was 0.9% by weight.

In the metathesis reactor 300, propylene was produced by reacting a separately supplied ethylene stream (Ethylene) with 2-butene in the discharge stream of the hydrogenation reactor 100. At this time, the isomerization reaction in which 1-butene is converted to 2-butene in the metathesis reactor 300 was also carried out.

The discharge stream of the metathesis reactor 300 in which the reaction was completed was supplied to the second distillation column 400 to separate unreacted ethylene from the upper discharge stream and recycled to the metathesis reactor 300. In addition, the lower discharge stream of the second distillation column 400 was supplied to the third distillation column 500.

The third distillation column 500 receives the lower discharge stream of the second distillation column 400, separates propylene from the upper discharge stream, and partially unreacted C4 mixture stream (Recycle C4) from the lower discharge stream. After purging, it was recycled to the hydrogenation reactor (100).

At this time, the flow rate of C4 Raffinate-2 supplied to the hydrogenation reactor 100 is 40.0 ton/hr, the flow rate of the stream supplied to the metathesis reactor 300 is 40.0 ton/hr, and the flow rate supplied to the metathesis reactor 300 The flow rate of the ethylene stream was 12.8 ton/hr, and the flow rate of Recycle C4 recycled from the third distillation column 500 to the hydrogenation reactor 100 was confirmed to be 10.0 ton/hr.

Experimental example

In the manufacturing process of Example 1 and Comparative Examples 1 to 2, the n-butene conversion rate (%) in the metathesis reactor 300, the production amount of propylene produced (ton/hr), and the purity of propylene (%) are shown in the following table. It is shown in 1.

n-butene conversion rate (%) Propylene production (ton/hr) Propylene purity (%) Example 1 78.9 32.8 99.99 Comparative Example 1 72.5 30.9 99.99 Comparative Example 2 76.3 32.5 98.82

Referring to Table 1, in the propylene production method according to the present invention (Example 1), the n-butene conversion rate was 78.9%, the propylene production amount was 32.8 ton/hr, and Recycle C4 was supplied to the metathesis reactor 300. Compared with Example 1, it was confirmed that the n-butene conversion rate was 6.4% higher and the propylene production amount was 1.9 ton/hr higher. This may be a result of 1,3-butadiene produced as a by-product of the metathesis reaction in Comparative Example 1 being included in Recycle C4 and supplied to the metathesis reactor 300 to act as a catalyst poison.

In addition, compared to Comparative Example 2 in Example 1, it was confirmed that the n-butene conversion rate was 2.6% higher, the propylene production amount was 0.3 ton/hr higher, and the propylene purity was 1.17% higher. In Comparative Example 2, Recycle C4 was supplied to the hydrogenation reactor 100 to remove 1,3-butadiene generated as a by-product of the metathesis reaction, but propylene contained in Recycle C4 was converted to propane through hydrogenation reaction, The separation of propane and propylene may be the result of a difficult problem.

100: hydrogenation reactor 200: first distillation column
300: metathesis reactor 400: second distillation column
500: third distillation column

Claims (10)

A C4 mixture stream comprising n-butane, i-butane, 1,3-butadiene, 1-butene and 2-butene is fed to a hydrogenation reactor to convert 1,3-butadiene to 1-butene, and 1-butene. Converting to 2-butene;
Supplying the hydrogenation reactor discharge stream to a first distillation column to separate propane from the upper discharge stream, and supplying the lower discharge stream to the metathesis reactor;
In the metathesis reactor, producing propylene from an ethylene stream supplied separately from the supplied hydrogenation reactor effluent stream;
Supplying the metathesis reactor discharge stream to a second distillation column to separate an unreacted ethylene stream from an upper discharge stream, and supplying a lower discharge stream to a third distillation column; And
Receiving the second distillation column lower discharge stream, separating propylene from the upper discharge stream, and supplying a lower discharge stream containing an unreacted C4 mixture to a hydrogenation reactor. The method of claim 1,
The method for producing propylene in which the content of 1,3-butadiene in the discharge stream of the hydrogenation reactor is 0.1% by weight or less. The method of claim 1,
The content of 1-butene in the discharge stream of the hydrogenation reactor is 20% to 50% by weight, and the content of 2-butene is 20% to 50% by weight. The method of claim 1,
Propane content in the hydrogenation reactor discharge stream is 0.5% by weight to 6% by weight of propylene production method. The method of claim 1,
The content of propane in the lower discharge stream of the first distillation column is 0 wt% to 1 wt%. The method of claim 1,
In the metathesis reactor, the metathesis reaction and the isomerization reaction are performed simultaneously. The method of claim 6,
A method for producing propylene in which a catalyst for accelerating each of the metathesis reaction and isomerization reaction is filled in the metathesis reactor. The method of claim 1,
The second distillation column head effluent stream is recycled to the metathesis reactor. The method of claim 1,
The content of propylene in the unreacted C4 mixture stream is 0.1% to 10% by weight. Propylene production method. The method of claim 1,
The propylene production method in which the content of propylene in the upper discharge stream of the third distillation column is 95% by weight or more.

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