KR101566048B1 - A process for preparing conjugated diene - Google Patents

Abstract

The present invention relates to a process for the production of conjugated dienes, which effectively removes heavy by-products and water, thereby providing a high boiling point solid-state by-product, heavy by-product pipeline, The present invention has an advantage that it can be applied directly to a commercialization process as well as an effect of providing a production process of a conjugated diene which is high in productivity, economical, excellent in work stability and convenience because the pipe clogging does not occur originally.

Description

A process for preparing conjugated diene < RTI ID = 0.0 >

More particularly, the present invention relates to a process for producing a conjugated diene, and more particularly, to a process for producing a conjugated diene, which comprises the steps of: (1) preparing a conjugated diene having a high boiling point at a room temperature by using heavy by- The present invention relates to a process for producing a conjugated diene.

In the chemical raw material market, demand for propylene has been increasing recently.

In the past, propylene was mainly produced as an olefin plant, in particular, a by-product of an ethylene plant. Processes have already been developed to increase the propylene yield in olefin plants, as this supply system can no longer meet the future demand for propylene. This process basically converts the relatively long olefins obtained from the olefin plant, for example olefins of 4 to 6 carbon atoms, into, for example, short-chain olefins of carbon atoms 2 and 3, in particular propylene (three carbon atoms) Based on the principle of.

In addition, techniques for recycling crude C4 discharged as residues in the olefin plant have been developed. For example, naphtha is separated from olefin plants into ethylene, propylene, and crude C4, C4 was extracted and extracted from C4-Raffinate-2 remaining after extraction of isotyped butane from C4-Raffinate-1 obtained after extraction of butadiene to obtain n-butene Followed by extraction with C4-Raffinate-3.

However, the reaction product obtained during the production of the conjugated diene is advantageously used as a purification step in the conventional purification step by extractive distillation at room temperature and atmospheric pressure to remove liquid water and heavy components, and Cox in the gaseous phase, 1,3-butadiene-containing reactant. The obtained normal and isotactic butane and 1,3-butadiene-containing reactants may further include a step of separating each butane and 1,3-butadiene, or, if necessary, a step of separating the n- Rich stream to circulate the n-butane rich stream.

However, due to heavy by-products which are solid at room temperature at a high boiling point included in the reaction product, problems such as the occlusion of the condenser in the condenser often occur, It is urgent to present a solution to the problem.

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, they have found that a heavy by-product is in a solid state at 20 to 29 캜, and is contacted with an organic solvent mixed with water It has been found that the clogging of pipelines, especially condensers, can be prevented by performing the treatment process, and the present invention has been accomplished.

That is, an object of the present invention is to provide a process for producing a conjugated diene in which a high boiling point is solid at room temperature and heavy by-product, in particular, .

In order to achieve the above object, in the present invention,

Comprising contacting a reaction product gas comprising water (steam), heavy by-products, and a conjugated diene with an organic solvent which is mixed with water in the process of preparing the conjugated diene by oxidative dehydrogenation from an alkene, And a process for producing the conjugated diene.

Hereinafter, the present invention will be described in detail.

The present invention is characterized in that it comprises the step of contacting a reaction product gas containing water, a heavy by-product, and a conjugated diene with an organic solvent which is mixed with water in a process for producing a conjugated diene.

Specifically, i) an oxidative dehydrogenation reaction by continuously passing a reactant containing an alkene, air, and steam through a catalyst layer to produce a reaction product comprising a conjugated diene and residual water and heavy by-products Obtaining a gas; And ii) contacting the reaction product gas with an organic solvent which is mixed with water to remove water and heavy by-products contained in the reaction product.

The term conjugated diene used in the present invention includes, but is not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, do.

The alkene used in the present invention may also be an olefin plant, i.e., a cracking furnace for cracking hydrocarbons and an olefin plant comprising a downstream fractionation step for separating the cracking product into individual fractions. However, it is not so limited, and it is also possible, for example, to utilize a particular product stream from a refinery to produce olefins.

That is, as the starting material for producing the conjugated diene, the alkene may be a hydrocarbon having 2 to 4 carbon atoms, such as ethylene or propylene, or a hydrocarbon such as ethylene, propylene, and crude C4, which is separated from the olefin plant, Lt; / RTI >

Further, C4-Raffinate-2 remaining after extraction of isotactic butane from C4-Raffinate-1 obtained by extractive distillation of crude C4 and obtained after extraction of butadiene, (C4-Raffinate-3) remaining after extraction of normal type butenes are also applicable.

C4-Raffinate-3 is typically present in an amount of about 10.3 wt% isotyped butane, about 64.2 wt% of normal type butane, about 5.4 wt% isotypedene, about 8.2 wt% About 5.7 wt% of trans-butene, about 3.3 wt% of 2-cis butene, and the like. The process for producing butadiene as a conjugated diene from C4-raffinate-3 is a process comprising: Molybdate catalyst at a reaction temperature of 300 to 600 DEG C, preferably at a reaction temperature of 320 to 500 DEG C and a reaction temperature of 50 to 5000 DEG C, in a molar ratio of 1: 0.5 to 10: 1 to 50, using a bismuth- -1. ≪ / RTI >

Specifically, the amount of air, which is another reactant, with the C4 mixture is precisely controlled using a mass flow controller. In order to inject steam, liquid water is supplied to each reactor by injecting water using a syringe pump. The temperature of the portion where the liquid water is injected is maintained at 150 to 300 ° C, preferably 180 to 250 ° C, and the water injected by the syringe pump is immediately vaporized to completely mix with other reactants (C4 mixture and air) To pass through the catalyst layer.

The bismuth-molybdate-based catalyst is a multicomponent bismuth molybdate catalyst. The bismuth-molybdate catalyst includes Mo 1-15, Bi 1-10, Fe 1-10, Co 1-10, K 0.01-1.5, and Cs 0-1.5 Is preferably a catalyst having a compositional ratio.

Specifically, the multicomponent bismuth molybdate catalyst is composed of a metal component having a divalent cation, a metal component having a trivalent cation, bismuth and molybdenum as constituent components, and a multicomponent bismuth molybdate It is possible to manufacture a catalyst for dating. As the metal component having a divalent cation, cobalt and nickel are preferably used, and most preferably, cobalt is used. According to one embodiment of the present invention, a multicomponent bismuth molybdate consisting of cobalt, cesium, iron, bismuth and molybdenum The highest activity was observed in the oxidative dehydrogenation reaction using the libate catalyst.

As the precursor of cesium, cesium nitrate and precursor of cobalt may be used as the precursor of cobalt (Cobalt nitrate) (II) nitrate), Iron (III) nitrate as a precursor of iron, Bismuth (III) nitrate as a precursor of bismuth, Ammonium molybdate as a precursor of molybdenum, Lt; / RTI > In order to maximize the yield of butadiene production to be achieved in the present invention, the ratio of cesium / cobalt / iron / bismuth / molybdenum precursor is preferably 1/10/1 to 5/1 to 2/5 to 20 .

The cesium, cobalt, iron, and bismuth precursors are simultaneously dissolved in distilled water, and the molybdenum precursor is separately dissolved in distilled water and then mixed with each other. At this time, an acidic solution (for example, nitric acid) Can be added. When the precursors are completely dissolved, the precursor solution containing cesium, cobalt, iron, and bismuth is injected into the molybdenum-containing precursor solution to deposit the metal components. The coprecipitated solution is stirred for 0.5 to 24 hours, preferably 1 to 2 hours, so that sufficient coprecipitation is achieved.

Water and other liquid components are removed from the stirred solution using a vacuum or centrifugal concentrator to obtain a solid component sample. The obtained solid sample is dried at 20 to 300 ° C, preferably 80 to 200 ° C for 24 hours. The solid catalyst thus produced is put into an electric furnace, and the catalyst can be produced by heat treatment at a temperature of 300 to 800 ° C, preferably 400 to 600 ° C, more preferably 450 to 500 ° C.

The oxidative dehydrogenation reaction using the catalyst of the present invention thus obtained is carried out by adsorbing alkene, which is a starting material, on the catalyst, and then reacting with two hydrogen atoms of oxygen adsorbed in the catalyst lattice to form conjugated dienes, water and heavy by- -products), and the reaction proceeds in such a manner that the molecular oxygen as the reactant fills the vacancy site of the catalyst lattice.

At this time, the heavy by-products are in a solid state at room temperature of 20 to 29 캜, and examples thereof include phenol, benzoic acid, benzophenone, fluorenone, maleic anhydride, phthalic anhydride, coumarin and the like.

In this case, the bismuth-molybdate catalyst is filled and fixed It is preferable to use a shell-tube reactor or the like having multiple tubes and a coolant circulation unit on the outside thereof in view of the reaction efficiency. In addition, the reactor for the conjugated diene process used in the present invention is preferably a two-stage reactor connected in series through a pipeline to perform an oxidative dehydrogenation reaction and then sequentially carry out a contact process with an organic solvent mixed with water desirable.

The reaction product thus formed is contacted with an organic solvent mixed with water instead of being subjected to a separate extraction step as in the conventional method, so that water and heavy by-products are removed. As described in the following examples, it is possible to effectively isolate the conjugated diene while preventing the condenser from clogging the pipe.

The organic solvent which can be used herein includes, but is not limited to, acetonitrile, N-methylpyrrolidone, N, N-dimethylformamide (DMF), acetone, ethanol, propanol, butanol and pentanol The use of more than one species is more preferable considering the aspect of mixing with water.

In addition, contact with the organic solvent is performed at the upper end of a condenser connected in series to the lower end of the reactor, and supply of the solvent is preferably performed using an LC pump. The feed rate is set to 0.5 to 2 h ^-1 and is set to be about 1 to 2% in consideration of the GHSV (Gas Hourly Space Velocity) of the feed.

After the post-treatment using the organic solvent, it is further preferable to further carry out the post-cooling treatment at 20 ° C or lower to dissolve the heavy by-products to prevent clogging of the conduit or the condenser.

According to the present invention, it is possible to provide a high-boiling point high-boiling point solid-state by-product pipe (heavy by-product), particularly a pipe of a condenser, The present invention has an advantage of providing a process for producing a conjugated diene excellent in work stability and convenience, and has an advantage that it can be directly applied to a commercialization process.

1 is a schematic diagram of an apparatus including a contact process according to an embodiment of the present invention.
FIGS. 2 to 4 are photographs showing the occlusion phenomenon at the inlet-side outer circumferential surface, the inner circumferential surface, and the channel inner side, respectively, of the channel of the condenser when the reaction product is distilled after the oxidative dehydrogenation reaction according to the prior art (Comparative Example 1).
FIGS. 5 to 7 show results obtained by connecting a glass condenser to the lower end of the reactor in order to visually observe a change in post-treatment of the reaction product with acetonitrile after the oxidative dehydrogenation reaction according to Example 1 of the present invention. FIG. 5 is a photograph of the glass capacitor before the test of Example 1, FIG. 6 is a photograph of the glass capacitor tested according to Comparative Example 1, and FIG. 7 is a photograph of the glass capacitor after the test of Example 1.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

< Comparative Example  1>

The butadiene production was carried out at 320 ° C under a molar ratio of 75 h ^-1 at a space velocity of ¹ , oxygen / butene = 1, steam / butene = 4 and nitrogen / The reaction product gas containing butadiene at the bottom of the reactor filled with the catalyst was passed through a condenser through which cooling water flows, and then collected in the waste water container. When the water level reached a certain level, the waste water was taken out and discarded.

As a result, the feed amount of the starting material butene was 0.625 g / min, and the yield from butene to butadiene was measured to be 92%. The heavy byproducts were benzoic acid 0.13%, phthalic anhydride 0.19%, cyclohexene dicarboxylic anhydride 0.20% It was confirmed that 0.04% of coumarin, 0.56% of benzophenone, 0.06% of fluorenone, 0.04% of anthraquinone and 0.08% of undetermined heavy byproduct were detected. After the completion of the process for about 24 hours, the outer and inner circumferential surfaces of the condenser, (Fig. 2 to 4 and 6).

< Example  1>

Butadiene production was carried out at 320 ° C under a molar ratio condition of 75 h ^-1 at a space velocity of ¹ , oxygen / 1-butene = 1, steam / 1-butene = 4 and nitrogen / As shown in FIG. 1, the reactor was transferred to a reactor connected in series at the lower end of the reactor filled with the catalyst, and acetonitrile was injected into the upper part of the condenser by using an LC pump for reaction product gas containing butadiene. The injection rate was set to 1.5 h ^-1 and the process was then collected in a waste water container in the same manner as in Comparative Example 1, and when the water level reached a certain level or higher, the waste water was drained and discarded.

As a result, the amount of the starting material, 1-butene, was 0.625 g / min, and the yield from butene to butadiene was measured to be 92%. As the heavy byproducts, benzoic acid 0.13%, phthalic anhydride 0.19%, cyclohexene dicarboxylic anhydride 0.20 , 0.04% of coumarin, 0.06% of benzophenone, 0.06% of fluorenone, 0.04% of anthraquinone and 0.08% of undetermined heavy byproducts. After completion of the process for about 24 hours, the outer and inner circumferential surfaces of the condenser inlet, No duct closure was observed in all the medial sides (see Figures 5 and 7).

< Example  2>

The same procedure as in Example 1 was repeated except that 1-butene was replaced with 2-butene as a starting material.

As a result, the amount of the starting material, 2-butene, was 0.417 g / min, and the yield of 2-butene to butadiene was measured to be 78%. As the heavy byproduct, 0.5% benzoic acid, 0.78% phthalic anhydride, It was confirmed that 0.17% of an anhydride, 0.08% of coumarin, 0.35% of benzophenone, 0.55% of fluorenone, 0.08% of anthraquinone and 0.62% of undetermined heavy by-product were obtained. After completion of the process for about 24 hours, the outer and inner circumferential surfaces, And duct occlusion was not observed in the inside of the duct.

< Comparative Example  2>

The same procedure as in Example 1 was repeated except that acetonitrile was replaced with diethyl ether which is an organic solvent which is immiscible in water.

As a result, the amount of the starting material, 1-butene, was 0.625 g / min, and the yield from butene to butadiene was measured to be 92%. As the heavy by-product, benzoic acid 0.13%, phthalic anhydride 0.19%, cyclohexene dicarboxylic anhydride 0.2% , 0.04% of coumarin, 0.56% of benzophenone, 0.06% of fluorenone, 0.04% of anthraquinone and 0.08% of unidentified heavy-chain by-products (same as in Comparative Example 1), and after completion of the process for about 24 hours, And the inner circumferential surface, and the inside of the channel.

As a result, according to Examples 1 and 2 of the present invention, a pipe having a high boiling point at a room temperature and being solid by heavy by-product compared to Comparative Examples 1 and 2, in particular, It was confirmed that the effect of providing a conjugated diene production process excellent in productivity, economy, operation stability and convenience was excellent.

Claims (12)

In the process of preparing conjugated dienes by oxidative dehydrogenation from alkenes, an organic solvent mixed with water is added to the reaction product gas containing water, heavy by-products and conjugated dienes using an LC pump And separating the water and the heavy by-product together with the organic solvent.
I) Oxidative dehydrogenation of reactants containing alkene, air and steam is continuously passed through the catalyst bed to produce reaction product gas comprising conjugated diene, residual water and heavy by-products ; And ii) injecting an organic solvent mixed with water into the reaction product gas using an LC pump to separate water and heavy by-products contained in the reaction product together with the organic solvent. Diene manufacturing process.
3. The method according to claim 1 or 2,
The organic solvent mixed with water is at least one selected from the group consisting of acetonitrile, N-methylpyrrolidone, N, N-dimethylformamide (DMF), acetone, ethanol, propanol, butanol and pentanol To produce a conjugated diene.
3. The method according to claim 1 or 2,
Wherein the heavy by-products are solid at room temperature (20 to 29 占 폚).
3. The method according to claim 1 or 2,
Wherein the alkene is a hydrocarbon having 2 to 4 carbon atoms.
6. The method of claim 5,
Wherein the alkene is a C4 mixture comprising normal type butane and isotyping butene, or C4-Raffinate-3.
The method according to claim 6,
The C4-raffinate-3 is obtained by separating naphtha into ethylene, propylene and crude C4 in the olefin plant and extracting C4-Raffinate (C4-Raffinate- (C4-Raffinate-3) remaining after extraction of normal type butene from C4-Raffinate-2 remaining after extraction of isotyping butane in Wherein the conjugated diene is produced by a process comprising the steps of:
3. The method according to claim 1 or 2,
The oxidative dehydrogenation reaction can be carried out by using a bismuth-molybdate-based catalyst in a reactant containing normal type butene: oxygen: steam at a molar ratio of 1: 0.5 to 10: 1 to 50, To 5,000 h &lt; ^{-1 &} gt ;.
3. The method according to claim 1 or 2,
Wherein the oxidative dehydrogenation reaction is carried out using a shell-and-tube reactor having a multi-tube filled with a bismuth-molybdate-based catalyst and fixed thereon and having a refrigerant circulation unit at the outside thereof, .
3. The method according to claim 1 or 2,
And the yield of the obtained conjugated diene is 90 to 92%.
3. The method according to claim 1 or 2,
Wherein the conjugated diene is selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and piperylene.
3. The method according to claim 1 or 2,
Wherein the step of bringing the reaction product gas into contact with an organic solvent mixed with water is carried out at an injection speed of 0.5 to 2 h ^-1 by using an LC pump on the top of a condenser connected in series to the lower end of the reactor .

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