KR20170070824A - Method for producing conjugated diene and apparatus for producing conjugated diene - Google Patents

Abstract

The present invention relates to a method and an apparatus for producing a conjugated diene, and more particularly, to a method for producing a conjugated diene, which comprises (a) subjecting a raw material gas containing a monoolefin having 4 or more carbon atoms to an oxidative dehydrogenation reaction under a catalyst, ; (b) contacting the product gas with cooling water to condense byproducts; (c) absorbing the cooled product gas in an absorption solvent to produce an absorption solution; (d) degassing the absorption liquid; And (e) stripping the deodorized absorbent solution to obtain a crude conjugated diene. In the step (b), coagulant is added to the wastewater discharged after coming into contact with the product gas And coagulating and precipitating the conjugated diene. The present invention also relates to a method and an apparatus for producing a conjugated diene.
According to the present invention, the effluent can be treated by a biological method used in a wastewater treatment plant by cooling the product gas to condense by-products and then coagulating the discharged wastewater to adjust the pH and reduce the content of the organic matter. There is an effect of providing a conjugated diene producing method and a producing apparatus.

Description

TECHNICAL FIELD [0001] The present invention relates to a conjugated diene producing method and an apparatus for producing conjugated diene,

The present invention relates to a method and an apparatus for producing conjugated dienes, and more particularly, to a method and apparatus for producing conjugated dienes. More particularly, the present invention relates to a method for producing conjugated dienes, The present invention relates to a conjugated diene production method and apparatus capable of being treated by a biological method used in a wastewater treatment plant.

Generally, 1,3-butadiene can be prepared by oxidative dehydrogenation of a monoolefin such as n-butane in the presence of a catalyst.

However, by-products are included in the product gas containing 1,3-butadiene produced by the oxidative dehydrogenation reaction. Generally, pure water is added to remove the by-products during cooling and washing in a quencher which cools the product gas by condensing the product gas. However, the waste water discharged after cooling contains the by-products Because it has high acidity due to very low pH and high chemical oxygen demand (Chemical Oxygen Demand), there is a problem that it can not be treated by biological methods generally used in wastewater treatment plants.

Accordingly, research and development of a method for effectively treating wastewater discharged after cooling of the generated gas is urgently required.

JP 2011-006381 A JP 2011-006395 A

In order to overcome the problems of the prior art, the present invention has been made to solve the problems of the prior art by condensing waste water by condensing byproducts by cooling the product gas, adjusting the pH of the wastewater discharged, reducing the content of organic matter, And it is an object of the present invention to provide a conjugated diene production method and apparatus capable of being treated by a biological method.

These and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention provides a process for producing a conjugated diene, comprising the steps of: (a) preparing a product gas containing a conjugated diene by oxidative dehydrogenation reaction of a feed gas containing a monoolefin having 4 or more carbon atoms under a catalyst; (b) contacting the product gas with cooling water to condense byproducts; (c) absorbing the cooled product gas in an absorption solvent to produce an absorption solution; (d) degassing the absorption liquid; And (e) stripping the deodorized absorbent solution to obtain a crude conjugated diene. In the step (b), the coagulant is introduced into the wastewater discharged after coming into contact with the product gas Thereby aggregating and precipitating the conjugated diene.

The present invention also relates to an oxidative dehydrogenation reactor for oxidatively dehydrogenating a raw material gas containing a monoolefin having 4 or more carbon atoms under a catalyst, a washing tower for washing and cooling the product gas produced from the reactor, A deasphalting tower for deasphalting the absorption liquid and a separation tower for distilling and separating the crude deoxidation reaction product and an absorption solvent into an absorption solvent, And a wastewater treatment apparatus for separating the wastewater discharged from the washing tower into a supernatant and a precipitate by agglomeration and sedimentation.

According to the present invention, the effluent can be treated by a biological method used in a wastewater treatment plant by cooling the product gas to condense by-products and then coagulating the discharged wastewater to adjust the pH and reduce the content of the organic matter. There is an effect of providing a conjugated diene producing method and a producing apparatus.

1 is a process diagram schematically showing an oxidative dehydrogenation reaction and a wastewater treatment process according to the present invention.
Fig. 2 is a photograph showing the discharged wastewater and the waste water flocculated according to Examples 1 to 5 of the present invention into a supernatant and a precipitate. Fig.

Hereinafter, the present invention will be described in detail.

The present inventors have found that when the wastewater discharged after cooling the product gas is coagulated by using a specific coagulant during the production of the conjugated diene, the organic matter content of the wastewater is reduced, the pH is controlled, and the discharged wastewater is treated by a biological method The present invention has been completed on the basis of this fact.

The method for producing the conjugated diene according to the present invention will be described in detail as follows.

The method for producing a conjugated diene includes the steps of: (a) preparing a product gas containing a conjugated diene by oxidative dehydrogenation reaction of a raw material gas containing a monoolefin having 4 or more carbon atoms under a catalyst; (b) contacting the product gas with cooling water to condense byproducts; (c) absorbing the cooled product gas in an absorption solvent to produce an absorption solution; (d) degassing the absorption liquid; And (e) stripping the deodorized absorbent solution to obtain a crude conjugated diene. In the step (b), the coagulant is introduced into the wastewater discharged after coming into contact with the product gas Thereby causing flocculation and sedimentation.

The monoolefin having 4 or more carbon atoms may be, for example, N-butene, and the N-butene may be 1-butene, cis-2-butene, trans-2-butene or a mixture thereof.

The catalyst is not particularly limited as long as it can be used in an oxidative dehydrogenation reaction. For example, it may be a molybdate-bismuth-based catalyst or a ferrite-based catalyst. The molybdate-bismuth-based catalyst may be, for example, a composite oxide catalyst comprising molybdenum, bismuth and cobalt. The ferrite-based catalyst may be, for example, a composite containing zinc, manganese, magnesium, cobalt, aluminum, Oxide catalyst.

The oxidative dehydrogenation reaction may be, for example, a reaction for producing butadiene by reacting a feed gas containing N-butene and a molecular oxygen-containing gas under a catalyst.

The cooling step (b) is a step for cooling the product gas and condensing and cleaning by-products in the product gas. The product gas produced in the product gas production step (a) is cooled by countercurrent contact with the cooling water have. In this case, the chemical oxygen demand (COD) of the wastewater discharged after contact with the product gas may be 10,000 to 200,000 ppm, 10,000 to 100,000 ppm, or 30,000 to 70,000 ppm, and the organic substance concentration may be 5,000 to 50,000 ppm, 10,000 To 50,000 ppm, or from 10,000 to 30,000 ppm, and the pH may be, for example, 1 to 4, 1 to 3, or 1.5 to 2.

In the present description, the chemical oxygen demand (COD) can be measured by a measuring method used in this technical field, and can be measured, for example, by the COD _MN method (process test method) which is an oxidation-reduction titration method using KMnO ₄ .

In the step (b), the coagulant injected into the wastewater discharged after coming in contact with the generated gas may include acid, aldehyde, ketone, etc. contained in the wastewater discharged after coming into contact with the generated gas For example, iron salts, magnesium salts or a mixture thereof, and specific examples thereof include ferrous chloride (FeCl ₂ ), ferric chloride Ferric chloride (FeCl ₃ ) and magnesium chloride (MgCl ₂ ).

Examples of the byproducts include acrolein, butenone, acrylic acid, benzaldehyde, phenol, acetophenone, benzoic acid, phthalic anhydride, , Fluorenone (Fluorenone), and anthraquinone (Anthraquinone).

The coagulant may be a mixture of iron salt and magnesium salt in a weight ratio of 5: 1 to 1: 5, 3: 1 to 1: 3, 2: 1 to 1: 2, or 0.9: 1.1 to 1.1: 0.9 , It is easy to coagulate within the range of the weight ratio and there is an effect of preventing pipeline corrosion.

Examples of the coagulant include a ferrous salt and a magnesium salt having a pH of 5: 1 to 1: 1, 3: 1 to 1: 1, or 2: 1 to 1: 1 1 or less than 1: 1 or less than 1: 1 or more than 1: 3 or less than 1: 1 or more when the pH of the wastewater is more than 11 To 1: 2 by weight, and it is easy to agglomerate within the weight ratio.

The flocculant may be an aqueous solution having a concentration of 10,000 to 100,000 ppm, 20,000 to 80,000 ppm, 30,000 to 60,000 ppm, or 45,000 to 55,000 ppm, for example.

The coagulant may be added at a concentration of 5,000 to 50,000 ppm, 8,000 to 30,000 ppm, or 10,000 to 25,000 ppm, for example, to the discharged wastewater. In this range, waste of coagulant consumption is prevented, It has an effect of preventing side effects such as pipeline corrosion caused by excessive flocculant after flocculation.

The method for preparing the conjugated diene may further include adjusting pH of the discharged wastewater to 3 to 11, 5 to 9, 7 to 8, or 7.0 to 7.5 by introducing a pH adjusting agent into the coagulant before the coagulant is introduced, The pH adjusting agent may be, for example, a basic aqueous solution having a concentration of 1 to 5 normal, 1 to 3 normal, 1 to 2 normal, or 1 to 1.5 normal concentration. Within this range, .

The basic aqueous solution is, for example, an aqueous solution of sodium hydroxide or an aqueous solution of ammonia, preferably an aqueous solution of sodium hydroxide. In this case, the process and work are easy.

The absorption solvent in the absorption liquid preparation step (c) selectively absorbs the conjugated diene, and may be, for example, a C ₆ to C ₁₀ saturated hydrocarbon, a C ₆ to C ₈ aromatic hydrocarbon, or an amide compound.

In the deaeration treatment step (d), nitrogen or oxygen dissolved in the absorption solution is removed before the absorption solution is subjected to a stripping process, and a stripping process is performed to remove the nitrogen A crude conjugated diene is obtained (e). The stripping is not particularly limited as long as it is a stripping method capable of separating the crude conjugated diene from the absorption solvent, but may be, for example, distillation separation. The term " crude " refers to a non-purified state. The crude conjugated diene produced by the above conjugated diene production method has a relatively high purity and can be used as it is without further purification. However, the present invention further includes a purification step of purifying the crude conjugated diene to obtain a high purity conjugated diene can do.

An apparatus for producing a conjugated diene according to the present invention comprises an oxidative dehydrogenation reactor for subjecting a raw material gas containing a mono-olefin having 4 or more carbon atoms to an oxidative dehydrogenation reaction under a catalyst, a wash tower for cooling a produced gas produced by the reactor by water, A deasphalting tower for deasphalting the absorption liquid, a separation tower for distilling and separating the crude deoxidation reaction product from the crude oxidative dehydrogenation reaction product and the absorption solvent, And a wastewater treatment device for separating the wastewater discharged from the washing tower into a supernatant and a precipitate by agglomeration and sedimentation.

The reactor used for the oxidative dehydrogenation reaction is not particularly limited as long as it is a conventional reactor used in this technical field. For example, the reactor may be a tubular reactor, a shaping reactor, a fluidized bed reactor or a fixed bed reactor, Tubular reactor or plate reactor.

The coagulation may be carried out, for example, by a coagulant, and the wastewater treatment apparatus may include a coagulant input unit for introducing the coagulant.

As another example, the wastewater treatment apparatus may include a supernatant filtration unit for filtrating and discharging separated supernatant after coagulation of wastewater.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory only and are not to be taken by way of illustration in the practice of the practice of this invention. And it is natural that such variations and modifications are included in the appended claims.

[Example]

Example  One

In the oxidative dehydrogenation reactor filled with 1,200 cc of the bismuth-molybdate catalyst (molar ratio of Mo 12, Bi 1, Fe 3 and Co 9), the temperature was 320 ° C., the pressure was 14.7 psi, the space velocity was 100 h ^-1 , An oxidative dehydrogenation reaction was carried out using steam under the molar ratio of butene 1, steam / butene 4 and nitrogen / butene 12.

Subsequently, the product gas was introduced into the lower portion of the washing tower, and the cooling water was sprayed to the upper portion of the washing tower, and the product gas was cooled to 100 ° C or lower. The cooled product gas was discharged to the top of the washing tower and subjected to a degassing and stripping process to obtain crude butadiene.

The wastewater used for the cooling was discharged to the lower portion of the washing tower and transferred to the wastewater treatment apparatus. At this time, the pH of discharged wastewater was 1.5 to 2.0, the chemical oxygen demand (COD) was 50,000 ppm, and the organic matter concentration was 20,000 ppm.

Then, the discharged wastewater was adjusted to a pH of 7 using 1 normal sodium hydroxide, and ferric chloride (FeCl3) and magnesium chloride (MgCl2) were mixed at a weight ratio of 1: 1 with the coagulant input portion The flocculant was added in the form of a 50,000 ppm aqueous solution at a concentration of 10,000 ppm relative to the effluent wastewater. Thereafter, the mixture was rapidly stirred at 300 rpm for 5 minutes and then slowly stirred at 150 rpm for 10 minutes. Thereafter, the agglomerated precipitate was left to stand for 1 hour so that all the precipitate could be precipitated, and the phases were separated.

The supernatant was filtered, and the weight of the aggregated precipitate was measured. The content of organic matter in the precipitate was measured by thermogravimetric analysis (TGA). The content of the organic component was measured by gas chromatography (Gas Chromatography, GC). The results are shown in Table 1 below.

Example  2

In Example 1, the same procedure as in Example 1 was carried out except that the concentration of the flocculant was adjusted to 25,000 ppm with respect to the wastewater.

Example  3

In Example 1, the same procedure as in Example 1 was carried out except that the concentration of the flocculant was adjusted to 50,000 ppm with respect to the wastewater.

Example  4

The procedure of Example 1 was repeated except that the coagulant was mixed in a weight ratio of 3: 1 in Example 1.

Example  5

In Example 4, the same procedure as in Example 1 was carried out except that the concentration of the flocculant was adjusted to 25,000 ppm with respect to the wastewater.

Example  6

In Example 4, the same procedure as in Example 1 was carried out except that the concentration of the flocculant was adjusted to 50,000 ppm with respect to the wastewater.

Example  7

The procedure of Example 1 was repeated, except that the coagulant was mixed in a weight ratio of 1: 3.

Example  8

In Example 7, the same procedure as in Example 7 was performed except that the concentration of the flocculant was adjusted to 25,000 ppm of the wastewater.

Example  9

In Example 7, the same procedure as in Example 7 was performed except that the concentration of the flocculant was adjusted to 50,000 ppm with respect to the wastewater.

Comparative Example  One

Except that the coagulant and NaOH were not administered in Example 1 above.

Comparative Example  2

The same procedure was followed except that the coagulant was not administered in Example 1 above.

division Example Comparative Example One 2 3 4 5 6 7 8 9 One 2 Wastewater pH 7 1.5 12 Weight of sediment (g) 0.43 0.57 0.84 0.49 0.77 1.23 0.20 0.54 0.57 - - Each component in the precipitate (% by weight) Organic matter 30.0 33.0 39.0 - 31.0 31.0 - 36.0 37.5 - - Carbon 5.0 8.0 4.0 - 8.0 6.0 6.0 7.0 - - Minerals 65.0 59.0 58.0 - 61.0 63.0 58.0 55.5 - - system 100 100 100 - 100 100 100 100 - - Supernatant organic matter
(ppm) 1528 1112 747 1879 1260 885 1228 958 672 19425 841

As shown in Table 1, in the case of Examples 1 to 9 in which wastewater was flocculated according to the present invention, it was confirmed that organic matter and the like were flocculated by the flocculant to precipitate the precipitate (see FIG. 2). However, in the case of Examples 1, 4, and 7, the amounts of agglomerated precipitates could not be measured by TGA, and the contents of the respective components in the sediment and the weights of the respective precipitates showed that the agglomerates It was confirmed that the amount of agglomeration of the organic material increases according to the concentration of the solution. Further, it was confirmed from the GC analysis results that the organic substance concentration in the supernatant was reduced as compared with Comparative Examples 1 and 2 in which the raw wastewater was used as it was from Examples 1 to 9 above.

Thus, the present inventors have found that the wastewater discharged after cooling the product gas is agglomerated using a specific flocculant, and as a result, the chemical oxygen demand (COD) of the wastewater is reduced and the pH is controlled to control the discharged wastewater to be biologically It can be confirmed that the process can be carried out also by the method shown in FIG.

Claims (12)

(a) an oxidative dehydrogenation reaction of a raw material gas containing a monoolefin having 4 or more carbon atoms under a catalyst to produce a product gas containing a conjugated diene;
(b) contacting the product gas with cooling water to condense byproducts;
(c) absorbing the cooled product gas in an absorption solvent to produce an absorption solution;
(d) degassing the absorption liquid; And
(e) stripping the deodorized absorbent solution to obtain a crude conjugated diene,
(B) adding coagulant to the wastewater discharged after coming into contact with the product gas, and coagulating and precipitating the wastewater. The method according to claim 1,
Wherein the coagulant is an iron salt, a magnesium salt or a mixture thereof. 3. The method of claim 2,
Wherein the coagulant is at least one selected from the group consisting of ferrous chloride, ferric chloride, and magnesium chloride. 3. The method of claim 2,
Wherein the coagulant is a mixture of iron salt and magnesium salt in a weight ratio of 5: 1 to 1: 5. The method according to claim 1,
Wherein the coagulant is introduced into an aqueous solution having a concentration of 10,000 to 100,000 ppm. The method according to claim 1,
Wherein the coagulant is added to the discharged wastewater at a concentration of 5,000 to 50,000 ppm. The method according to claim 1,
Further comprising the step of adjusting the pH of the discharged wastewater to 3 to 11 by adding a pH adjusting agent before the coagulant is added. 8. The method of claim 7,
Wherein the pH adjusting agent is a basic aqueous solution having a concentration of 1 to 5 normal. 9. The method of claim 8,
Wherein the basic aqueous solution is an aqueous sodium hydroxide solution or an aqueous ammonia solution. The method according to claim 1,
Wherein the product gas and the cooling water are in countercurrent contact. An oxidative dehydrogenation reactor in which a raw material gas containing a monoolefin having 4 or more carbon atoms is subjected to an oxidative dehydrogenation reaction under a catalyst, a water washing step in which the product gas produced from the reactor is washed and cooled, An absorption tower for producing an absorption liquid, a deaeration tower for deaerating the absorption liquid, and a separation tower for distilling and separating the dehydrogenated absorption solution from the crude oxidation dehydrogenation reaction product and the absorption solvent,
And a wastewater treatment apparatus for separating the wastewater discharged from the washing tower into a supernatant and a precipitate by agglomeration and sedimentation. 12. The method of claim 11,
Wherein the wastewater treatment apparatus includes a supernatant filtration unit.

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