KR102050834B1 - Producing method of Butadiene - Google Patents

Abstract

The present invention relates to a method for producing butadiene, and more specifically, the compressor used in the compression step of the manufacturing process is one stage or two stages, the separation of the reaction product produced from the reactor by the extraction distillation column (Extractive distillation column, EDC), the pressure of the extractive distillation column provides a method for producing butadiene, characterized in that 1 to 6 kg / cm ² .
According to the butadiene production method of the present invention, it is possible to simplify the process equipment and improve the energy efficiency.

Description

Producing method of Butadiene

The present invention relates to a process for producing butadiene which can simplify process equipment and reduce the energy consumed.

Industrially, 1,3-butadiene is one of the important chemicals used in various fields. For example, it is used as an intermediate of many petrochemical products such as synthetic rubber and electronic materials. Butadiene is one of the most important basic oils in the petrochemical market and its demand and value are gradually increasing.

Methods for preparing 1,3-butadiene include extracting from C4 fraction through naphtha cracking, direct dehydrogenation of n-butene, and oxidative dehydrogenation of n-butene ( oxidative dehydrogenation reaction method.

Among them, a method of producing 1,3-butadiene by reacting butane or butene with oxidative dehydrogenation is to reduce the risk of explosion of reactants, and to inject nitrogen and steam in addition to raw materials to prevent coking of catalyst and to remove heat of reaction. do. According to the reaction, 1,3-butadiene as the main product, carbon monoxide, carbon dioxide, and the like by-products are additionally generated.

Subsequently, when the light product is separated and removed from the reaction product, a C4 mixture including 1,3-butadiene is obtained, and when purified, the 1,3-butadiene of high purity is obtained. Meanwhile, some or all of the separated and removed gas products may be recycled.

Typically, butadiene production according to the method described above was conventionally performed according to the process flow chart shown in FIG.

 In this case, however, a high pressure was required to reduce the amount of dissolved oxygen and the high absorption performance of the reaction product relative to the absorption solvent used in the separation step of the reaction product during the process. Therefore, not only the enormous energy consumption is required, but also the process equipment is complicated and the investment cost burden also increases.

Therefore, there is a need for an improved method for producing butadiene more economically and efficiently by mitigating pressure conditions required for the process and simplifying the installation.

Method for separating 1,3-butadiene from C4 fraction using acetylene conversion process (Korea Patent No. 10-1111015)

In order to solve the above problems, the inventors of the present invention can reduce the pressure conditions required for separation by using an extractive distillation column in the step of separating the reaction product, and as shown in Figure 1 during the conventional butadiene manufacturing process Separation steps from the absorption tower and deaeration tower can be combined into one stage of the extractive distillation column, and compressors installed in at least three stages can be simplified to one or two stages, resulting in excessive energy consumption. The present invention was completed by confirming that butadiene can be economically produced without.

It is therefore an object of the present invention to reduce the pressure conditions required in the conventional separation step and thus provide a method for producing butadiene economically without excessive energy consumption.

Conducting a dehydrogenation reaction by introducing a first stream including C4 oil, steam, oxygen (O ₂ ), and nitrogen (N ₂ ) into a catalyst-filled reactor;

Cooling the reaction product obtained from the reactor;

Compressing the cooled reaction product;

Separating butadiene, a C4 mixture except butadiene, and a gas product in the compressed reaction product; And

Recovering and purifying the separated butadiene; including,

The compressor used in the compression step is one or two stages, and the separation of the reaction product is performed through an extractive distillation column (EDC), and the pressure of the extractive distillation column is 1 to 6 kg / cm ^2. It provides the manufacturing method of butadiene characterized by the above-mentioned.

If necessary, the process includes, after the separation step, circulating a second stream comprising any one of C4 mixture except carbonadiene, carbon monoxide, carbon dioxide, nitrogen, and combinations thereof, back into the reactor, and including a purge. The third flow may further comprise venting out of the reaction system.

According to the butadiene production method of the present invention,

Compared with the conventional butadiene manufacturing process, the separation of the reaction product through the absorption tower and degassing column during the process is carried out through an extractive distillation column (hereinafter referred to as 'EDC') pressure throughout the manufacturing process The condition can be lowered.

Specifically, the use of EDC can lead to the linear separation of the C4 mixture and gas products containing 1,3-butadiene, it is possible to perform the separation process at a significantly lower pressure than conventional.

In addition, the existing compression plant can be simplified according to the reduced pressure conditions, and the two processes separated by the absorption tower and the degassing column can be combined into a single step of the extractive distillation column (EDC). It can be simplified.

In addition, there is an advantage that the purity and yield of the recovered material are also improved.

As a result, according to the butadiene production method of the present invention, while recovering butadiene in high yield, it is possible to reduce the energy and equipment investment cost consumed in the process.

1 is a process flowchart of a conventional butadiene production method.
2 is a process flowchart of a butadiene production method according to the present invention.

Hereinafter, the content of the present invention will be described in more detail. However, the following contents are described only for the most representative embodiments in order to help the understanding of the present invention, and the scope of the present invention is not limited thereto, and the present invention should be understood to cover all ranges equivalent to the following contents.

The present invention,

Conducting a dehydrogenation reaction by introducing a first stream including C4 oil, steam, oxygen (O ₂ ), and nitrogen (N ₂ ) into a catalyst-filled reactor;

Cooling the reaction product obtained from the reactor;

Compressing the cooled reaction product;

Separating butadiene, a C4 mixture excluding butadiene, and a gas product in the compressed reaction product; And

Recovering and purifying the separated butadiene; including,

The compressor used in the compression step is one or two stages, the separation of the reaction product is carried out through an extractive distillation column (hereinafter referred to as 'EDC') of the extractive distillation column, the pressure of the extractive distillation column Silver is 1 to 6 kg / cm ² provides a method for producing butadiene.

The process flow diagram related to the butadiene production method of the present invention as described above is shown in FIG. According to Figure 2 it can be seen that the conventional absorption tower and degassing tower during the process is replaced by EDC, the compressor is installed in one or two stages.

In addition, the butadiene production method of the present invention after the separation step is circulated a second stream including any one of the C4 mixture, carbon monoxide, carbon dioxide, nitrogen and combinations thereof except butadiene, and re-introduced into the reactor, purge The third flow comprising a) may further comprise venting out of the reaction system.

According to the butadiene production method of the present invention, when compared with the conventional butadiene production process, it is possible to lower the pressure conditions of the overall manufacturing process by performing the separation step of the reaction product passed through the absorption tower and degassing column through the EDC. .

Specifically, the use of EDC can lead to the linear separation of the C4 mixture and gas products containing 1,3-butadiene, it is possible to perform the separation process at a significantly lower pressure than conventional.

In addition, it is possible to simplify the existing compression equipment according to the reduced pressure conditions, as well as to combine the two processes separated into absorption tower and degassing tower in a single step of the EDC can simplify the process equipment.

In addition, there is an advantage that the purity and yield of the recovered material are also improved.

As a result, according to the butadiene production method of the present invention, while recovering butadiene in high yield, it is possible to reduce the energy and equipment investment cost consumed in the process.

The butadiene production apparatus used in the butadiene production method of the present invention is an individual for introducing each component of the first stream including C4 fraction, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) into the reactor, respectively. It may include a pipeline, or may include a plurality of individual pipelines which are branched in one pipeline directly connected to the reactor, the components included in the first flow is separately introduced.

Where connected to this pipeline and the place where the oxidative dehydrogenation reaction occurs is provided as a reactor, the front end of the reactor may further include a mixing device for mixing them before the components included in the first stream is introduced into the reactor.

Also, between the reactor and the gas separation device, a quenching device including a cooling tower for cooling the reaction product obtained from the reactor, a compressor for compressing the reaction product, and water contained in the reaction product. It further includes a dewatering device for removal.

In particular, it further comprises an EDC for separating the reaction product passed through the quench device and the compressor.

In addition, the solvent recovery tower for separating and removing the solvent used in the EDC may further include.

If necessary, the butadiene production unit is a reactor containing a second stream comprising at least one selected from the group consisting of nitrogen (N ₂ ), carbon monoxide (O ₂ ) and carbon dioxide (CO ₂ ) in the separated C4 mixture and gas products. It may further include an inert recycle line that allows re-introduction into the outlet and a discharge line for discharging a third flow including a purge out of the system.

The apparatus may further include a solvent recovery tower and a butadiene purification tower for purifying the recovered butadiene with high purity.

Hereinafter, a method for preparing butadiene according to the present invention that can be performed through the butadiene production apparatus will be described in detail for each step.

First, the butadiene manufacturing method of the present invention is a step of proceeding the oxidative dehydrogenation reaction by introducing a first stream containing C4 oil, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) into the catalyst filled reactor Perform

In one embodiment of the present invention, the first stream may be a stream in which C4 oil, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) are introduced into the reactor through each individual pipeline.

And in another embodiment of the present invention, the first flow is branched in a pipeline in which C4 fraction, steam, oxygen (O ₂ ) and nitrogen (N ₂ ) are directly connected to the reactor, The components included in the first stream pass through a plurality of separate pipelines which are separately introduced and then are mixed again by a mixing device which may be a stream which is mixed in the one pipeline again or may be placed in front of the reactor and then the reactor It may be a flow flowing in.

Specifically, the C4 fraction, steam, oxygen and nitrogen included in the first stream may be introduced into the pipeline in a gaseous state, and the gas may be pre-heated and introduced to a temperature favorable for the oxidative dehydrogenation reaction.

Specifically, the C4 fraction may be C4 raffinate-1, 2, 3 remaining after separating useful compounds from the C4 mixture produced by naphtha cracking, or C4 compounds obtainable through ethylene dimerization. .

Preferably from the group consisting of n-butane, trans-2-butene, cis-2-butene and 1-butene One or two or more mixtures selected, more preferably a mixture comprising butane, isobutane, 2-butene, 1-butene, isobutene, butadienes and acetylenes.

The steam or nitrogen (N ₂ ) in the oxidative dehydrogenation reaction, while reducing the risk of explosion of the reactant, is introduced for the purpose of preventing the coking (coking) of the catalyst and the removal of the reaction heat. In addition, the oxygen (O ₂ ) is introduced into the oxidant (oxidant), and reacts with the C4 fraction to cause a dehydrogenation reaction.

On the other hand, the catalyst charged in the reactor is not particularly limited as long as it can be produced by the oxidative dehydrogenation reaction of the C4 fraction, but may be preferably a ferrite catalyst or a bismuth molybdate catalyst. More preferably, a bismuth molybdate-based catalyst may be used, and the bismuth molybdate-based catalyst includes one or more selected from the group consisting of bismuth, molybdenum, and cobalt, for example. Can be. However, the type and amount of the reaction catalyst may vary depending on the specific conditions of the reaction.

The type of the reactor is not particularly limited as long as the oxidative dehydrogenation reaction can proceed. Such as a tubular reactor, a tank reactor, or a fluidized bed reactor. As another example, the reactor may be a fixed bed reactor or may be a fixed bed multi-tubular reactor or a plate reactor.

The first flow described above is introduced into the reactor to perform a reaction such as Scheme 1 or 2 below as the main reaction.

Scheme 1

C ₄ H ₈ + _1/2 O ₂ → C ₄ H ₆ + H ₂ O

Scheme 2

C ₄ H ₁₀ + O ₂ → C ₄ H ₆ + 2H ₂ O

The reaction product obtained from the reactor comprises a C4 compound comprising butadiene (1,3-butadiene) and also includes gas products such as carbon monoxide (CO), carbon dioxide (CO ₂ ) and nitrogen (N ₂ ).

After the reaction product is obtained through the reactor inflow step of the above-described first flow, it may further include a dehydration step of removing water remaining in the reaction product.

This is because when the water remains in the reaction product, the device may be corroded by moisture in the separation and purification process of the reaction product, or impurities may accumulate in the solvent.

The dehydration method is not particularly limited. In addition, the dehydrating agent used in the dehydration step is also not particularly limited, but may be, for example, a drying agent (moisture adsorbent) such as calcium oxide, calcium chloride, and molecular sieve. Preferably, it may be a molecular sieve, in which case there are advantages such as ease of regeneration and ease of handling.

After the reaction product is obtained and dehydrated as necessary, a post-treatment process as described below is performed.

First, the reaction product obtained from the reactor may typically be in the form of a hot gas, and therefore needs to be cooled before being fed to the separation device. Therefore, the reaction product is cooled to enter the quenching apparatus including a cooling tower (quenching tower).

The cooling method is not particularly limited. For example, a cooling method of directly contacting the cooling solvent and the reaction product may be used, or a cooling method of indirect contacting the cooling solvent and the reaction product may be used.

The cooled reaction product is then passed through a compressor to compress.

In the past, a lot of energy was consumed in the compression step because high pressure conditions were required in order to compress the inert gas (particularly N ₂ ) or in consideration of the separation efficiency due to the use of an absorption solvent in the separation step.

However, in the present invention, since the EDC is used in the subsequent separation step, the required pressure condition and the energy consumed are reduced, and the type of the compressor, which has been required for three or more stages in the past, can be simply installed and used in one or two stages.

Next, the step of separating the butadiene, C4 mixture except the butadiene and the gas product in the compressed reaction product.

In particular, the present invention uses EDC. EDC is one of extraction methods, which means adding a large amount of solvent and distilling the mixture by using affinity difference with the solvent. In the conventional butadiene manufacturing method, it is possible to collectively perform a series of independent processes of absorbing butadiene as an absorption solvent in an absorption tower and then removing other gas components through the degassing process in order to separate reaction products. In this case, there is an advantage that the required pressure conditions can also be significantly reduced.

Specifically, the use of the EDC may induce line separation of the gas product and the C4-class compound. That is, the compressed gaseous reaction product is introduced into the EDC, and an extraction solvent is introduced at the top of the distillation column, so that 1,3-butadienes, acetylenes, and a small amount of cis-2-butene having a high affinity with the solvent in the C4 fraction. Can be obtained at the bottom of the column together with the solvent. In addition, the upper part of the tower recovers raffinator-1- (BBR-1) containing butane, isobutane, 2-butene, 1-butene, isobutene and the like. The number of stages of the EDC column may vary depending on the composition to be separated, preferably 20 to 60 stages, more preferably 25 to 55 stages. In the embodiment of the present invention, a total number of stages of 42 stages was used, of which 6 stages of solvent and 35 stages of reaction product were added.

A solvent having a polarity is used as the extraction solvent, and mainly N (nitrogen) alkylated solvents are used, and examples thereof include dimethylformamide (DMF), diethylformamide, dimethylacetamide and acetonitrile. Can be. These polar solvents in the anhydrous state have good relative volatilities and suitable boiling points and are suitable for application in the present invention, of which dimethylformamide (DMF) is most preferred.

In particular, the pressure of the EDC is preferable to 1~6 kg / cm ² as in the present step, it is more preferable to 3~4kg / cm ^2. Specifically, the top pressure of the extractive distillation column is characterized in that 1~5 kg / cm ^2, the lower pressure 3~6kg / cm ^2. If the pressure is less than the above preferred range, the distillation efficiency is reduced, even if the pressure is exceeded, the distillation efficiency is reduced or unnecessary energy is consumed to cause side reactions.

In addition, the top temperature of the EDC is preferably -90 to -50 ° C, more preferably -80 to -60 ° C, and the bottom temperature is preferably 80 to 120 ° C, more preferably It is 95-105 degreeC. If the temperature is less than the above preferred range, distillation efficiency is reduced, even if it is exceeded, distillation efficiency is reduced or unnecessary energy is consumed and side reactions may occur.

The EDC may be composed of 40 to 200 stages as necessary.

Meanwhile, after separation of the reaction product through the EDC, a second stream including any one of C 4 mixture, carbon monoxide, carbon dioxide, nitrogen, and combinations thereof except butadiene is circulated and re-introduced into the reactor, if necessary, and purged ( The third flow comprising purge may further comprise evacuating out of the reaction system.

The second stream may be a concentrated stream comprising one or more selected from the group consisting of nitrogen and carbon dioxide, circulated along an internal circulation line and reintroduced into the reactor. The second stream may further include unreacted raw materials and butadiene in addition to nitrogen (N ₂ ) and carbon dioxide (CO ₂ ), and the carbon dioxide included in the second stream may be re-introduced into the reactor through an internal circulation to be in the reactor. It may act as a mild oxidant or as a diluent gas in the oxidative dehydrogenation reaction.

In addition, the third flow is a purge stream, which is discharged out of the system through a discharge line separate from the second flow. The third stream may further include nitrogen (N ₂ ), carbon dioxide (CO ₂ ), unreacted raw materials, 1,3-butadiene, and the like.

Next, butadiene is recovered and purified.

Specifically, the extraction solvent containing butadiene is supplied to a solvent recovery tower, separated and recovered, and the remaining butadiene is supplied to a purification tower and recovered by high purity.

The method for separating and recovering the extraction solvent is not particularly limited to any one method, and for example, a distillation separation method may be used. According to the distillation separation method, an extraction solvent in which butadiene is dissolved by a reboiler and a condenser is supplied to a solvent recovery tower, followed by distillation. Butadiene is extracted from the upper vicinity through the distillation separation process.

The extraction solvent separated in the above process is extracted from the bottom of the solvent recovery column, the extracted extraction solvent can be re-supplied to the shearing process and used again. Since the absorbing solvent may contain impurities, some of the absorbing solvent may be extracted before being recycled to remove impurities by a known purification method such as distillation, decantation, sedimentation, contact treatment with an adsorbent or ion exchange resin, and the like. Can be.

On the other hand, butadiene obtained from the top of the solvent recovery column is supplied to the butadiene purification tower and high boiling point, low boiling point components are removed during this purification tower, resulting in high purity butadiene (1,3-butadiene).

The purity of butadiene (1,3-butadiene) finally obtained through the series of steps described above is preferably 99.0% to 99.9%.

According to the butadiene production method of the present invention, while it is possible to recover butadiene in the above high purity, it is possible to remarkably reduce the investment cost of energy and process equipment consumed, thereby improving the convenience and economic efficiency of the process.

Hereinafter, Examples, Comparative Examples, and Experimental Examples are described to help understand the present invention. However, the following descriptions are merely examples of the contents and effects of the present invention, and the scope and effects of the present invention are not limited thereto.

[ Example  One]

Butadiene was prepared in a reactor filled with a bismuth molybdate-based catalyst according to the present invention. At this time, the compressor was set to one stage, and dimethylformamide (DMF) was used as an extraction solvent for extracting and distilling the reaction product obtained from the reactor in an EDC.

Specific reaction conditions in the extraction distillation column (EDC) are shown in Table 1 below.

Upper temperature (℃) -61.13 Lower temperature (℃) 103.34 Solvent inflow (kg / h) 50000 Recirculation mass 0.56 Upper pressure (kg / cm ² ) 3.0 Lower pressure (kg / cm ² ) 3.5

 [ Comparative example  One]

Butadiene was prepared in the same manner as in Example 1, but without using an extractive distillation column (EDC) in the separation step of the reaction product, an absorption tower for selectively separating and absorbing butadiene in the reaction product and the gas product included in part A degassing tower to remove the was used independently.

Dimethylformamide (DMF) was used as an absorption solvent used to selectively absorb butadiene in the absorption tower.

Specific reaction conditions in the absorption tower is shown in Table 2, specific reaction conditions in the degassing column is shown in Table 3.

Upper temperature (℃) 9.0 Lower temperature (℃) 43.6 Solvent inflow (kg / h) 68428 Upper pressure (kg / cm ² ) 12.0 Lower pressure (kg / cm ² ) 12.5

Upper temperature (℃) 22.6 Lower temperature (℃) 117.3 Recirculation mass 0.2 Upper pressure (kg / cm ² ) 3.0 Lower pressure (kg / cm ² ) 3.5

[ Experimental Example  One]

When preparing butadiene according to the above examples and comparative examples, the amount of each reaction product obtained separately is shown in Table 4 below. The numerical values stated are parts by weight.

Example 1 (EDC BTM) Comparative Example 1 (Degassing Tower BTM) O ₂ - - N ₂ - - CO ₂ - - CO - - Water - 0.0023 IC4 (Iso-butane) - - Acetaldehyde 0.0003 0.0002 ACOH (Acetic acid) - - 1C4E (1-butene) 0.0002 0.0002 IC4E (Iso-butene) - - 1,3-Butadiene 0.1109 0.0835 N-BUTANE - - VA (vinyl acetylene) - - T2C4E (trans-2-butene) 0.0001 0.0002 C2C4E (cis-2-butene) 0.0006 0.0004 Acrolein 0.0007 0.0005 Furan 0.0010 0.0007 Butenone 0.0012 0.0004 Benzene 0.0002 0.0002 Acrylic acid - - Maleic anhydride - - BD Dimer - - Styrene 0.0001 0.0008 Benzaldehyde 0.0001 0.0021 Phenol - - Benzoic acid - 0.0006 Phthalic anhydride - 0.0003 Dimethyl formamide (DMF) 0.8846 0.8642 Furural - 0.0245 Tar - 0.0189

Comparing the amount of each reaction product obtained through Table 4, in the case of Example 1, the yield and purity of the obtained butadiene (1,3-butadiene), although the process was carried out at a significantly lower temperature than Comparative Example 1 You can see that it is higher.

Butadiene production method according to the present invention can be effectively used in the mass production of butadiene for industrial use, because butadiene can be obtained with high purity and high efficiency while reducing energy and investment cost.

Claims (8)

Conducting a dehydrogenation reaction by introducing a first stream including C4 oil, steam, oxygen (O ₂ ), and nitrogen (N ₂ ) into a catalyst-filled reactor;
Cooling the reaction product obtained from the reactor;
Compressing the cooled reaction product;
Separating butadiene, a C4 mixture except butadiene, and a gas product in the compressed reaction product; And
Recovering and purifying the separated butadiene; including,
The compressor used in the compression step is one or two stages, and the separation of the reaction product is performed through an extractive distillation column (EDC),
The upper (top) pressure is 1~5 kg / cm ^2, the lower (bottom) pressure in the extractive distillation column is 3~6kg / cm ^2,
The top temperature in the extractive distillation column is -80 to -60 ℃, the bottom temperature is 95 to 105 ℃ manufacturing method of butadiene. The method of claim 1,
Dehydrating the reaction product before the cooling step of the reaction product further comprising the step of producing a butadiene. The method of claim 1,
After separating the reaction product, a second stream comprising any one of C 4 mixture, but not carbon dioxide, carbon dioxide (CO ₂ ) and nitrogen (N ₂ ) and combinations thereof except for butadiene is circulated to return to the reactor. And a third stream comprising the input and purging further comprises venting out of the reaction system. The method of claim 1,
Recovery and purification of the butadiene is a method for producing butadiene, characterized in that the distillation of the solvent in the solvent recovery column and supplying the remaining butadiene to the purification tower. The method of claim 1,
Butadiene production method characterized in that it further comprises the step of purifying the butadiene recovered after the recovery step of butadiene in a purification tower. The method of claim 1,
The reaction product obtained from the reactor comprises butadiene, carbon monoxide (CO), carbon dioxide (CO ₂ ) and nitrogen (N ₂ ) method for producing butadiene. delete delete

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