KR20130036467A - A process for preparing conjugated diene - Google Patents

Abstract

PURPOSE: A manufacturing process of a conjugated diene is provided to have high productivity, work stability, and excellent convenience by preventing the duct of a condenser from being clogged. CONSTITUTION: A manufacturing process of a conjugated diene by an oxidative dehydrogenation includes a step of contacting reaction product with water, heavy byproducts, and conjugated diene to a water miscible organic solvent. The water miscible organic solvent is selected one or more from acetonitrile, N-methylpyrrolidone, N,N- dimethylformamide, acetone, ethanol, propanol, butanol, and pentanol. The heavy byproduct is in a solid state at 20-29 >=.

Description

A process for preparing conjugated diene

The present invention relates to a process for the production of conjugated dienes, and specifically, a blockage of a pipeline by a heavy by-product that is a solid at room temperature of a high boiling point, in particular, a blockage of a pipeline of a condenser. It relates to a process for producing conjugated diene that does not occur.

In the chemical raw materials market, the demand for propylene is increasing recently.

In the past, propylene was produced mainly as a byproduct of olefin plants, in particular ethylene plants. Since only this supply system can no longer meet the future demand for propylene, a process has already been developed to increase propylene yield in olefin plants. This process basically converts relatively long chain olefins obtained in an olefin plant, for example olefins having 4 to 6 carbon atoms, for example short chain olefins having 2 and 3 carbon atoms, in particular propylene (three carbon atoms). It is based on the principle of letting.

In addition, techniques for recycling crude C4 discharged as a residue from the olefin plant have also been developed, for example, naphtha is separated into ethylene, propylene, and crude C4 in an olefin plant, Normal type butene from C4-Raffinate-2 remaining after extraction of isotype butane in C4-Raffinate-1 obtained after extraction of butadiene by extraction distillation of C4. And extraction of C4-Raffinate-3 after extraction.

However, the reaction product obtained during the process of producing the conjugated diene is conventionally extracted and distilled advantageously at room temperature and atmospheric pressure to remove liquid water, heavy components, and gaseous Cox, and normal type and iso type butane and A 1,3-butadiene containing reactant is obtained. In addition, the obtained butan and 1,3-butadiene-containing reactants of the normal and iso-type may further comprise the step of separating each butane and 1,3-butadiene or, if necessary, the normal-type butane in the hydrocarbon-containing fraction. It may further comprise the step of feeding and circulating to an n-butane rich stream.

However, due to the heavy by-product that is a solid at room temperature of the high boiling point included in the reaction product, for example, the conduit of the condenser is often caused, so It is urgent to present a solution.

Accordingly, the present inventors have intensively researched to solve the above-mentioned problems. As a result, the heavy by-products are in a solid state at 20 to 29 ° C., and then contacted with an organic solvent mixed with water without undergoing a separate complicated treatment process. By carrying out the treatment process it was confirmed that the blockage of the conduit of the conduit, in particular condenser (condenser) can be blocked at the source to complete the present invention.

That is, an object of the present invention is a process for producing conjugated diene in which a blockage by a heavy by-product that is a solid at room temperature of a high boiling point, especially a condenser, is not generated. To provide.

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

In a process for producing conjugated diene from oxidative dehydrogenation from alkene, comprising contacting a reaction product gas comprising water (steam), heavy by-products, and conjugated diene with an organic solvent mixed with water It provides a process for producing a conjugated diene, characterized in that.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely.

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

Specifically, iii) a reaction product containing conjugated diene, residual water and heavy by-products by oxidative dehydrogenation while continuously passing the reactants containing alkenes, air and steam through the catalyst bed. Obtaining a gas; And ii) contacting the reaction product gas with an organic solvent mixed with water to remove water and heavy by-products included in the reaction product.

First, 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 or piperylene and the like. do.

In addition, the alkenes used in the present invention may be those produced from an olefin plant, i.e., an olefin plant comprising a cracking furnace for cracking hydrocarbons and a downstream fractionation step for separating the cracking product into respective fractions. However, it is not limited to this, for example, it is also possible to use a particular product stream from a refinery for producing olefins.

That is, alkenes as starting materials for producing conjugated dienes are hydrocarbons having 2 to 4 carbon atoms such as ethylene and propylene, or ethylene or propylene in ethylene, propylene, and crude C4 separated from the olefin plant described above. It may be.

Furthermore, the crude C4 was extracted and distilled to extract C-Raffinate-1 (C4-Raffinate-1) obtained after the extraction of butadiene, followed by the extraction of iso-type butane C4-Raffinate-2 (C4-Raffinate-2). C4-Raffinate-3, which remains after extraction of the normal type butene from C, is also applicable.

C4-Raffinate-3 is typically about 10.3 wt% of isotype butane, about 64.2 wt% of normal type butane, about 5.4 wt% of isotype butene, about 8.2 wt% of 1-butene, 2 -About 5.7 wt% of trans butene, about 3.3 wt% of 2-cis butene, and the like, but the process for producing butadiene as conjugated diene from C4- raffinate-3 comprises a stream rich in normal type butene: oxygen: steam A reaction temperature of 300 to 600 ° C., preferably a reaction temperature of 320 to 500 ° C. and a 50 to 5000 h ratio using a bismuth-molybdate catalyst in the reaction product contained in the molar ratio of 1: 0.5 to 10: 1 to 50 It is preferably carried out at a space velocity of -1.

Specifically, the amount of air, which is the C4 mixture and another reactant, was precisely controlled using a mass flow controller, and vaporized while injecting liquid water using a syringe pump to inject steam to be supplied to each reactor. Maintain the temperature of the part where liquid water is injected at 150 ~ 300 ℃, preferably 180 ~ 250 ℃, and vaporize the water injected by the syringe pump immediately by mixing with other reactants (C4 mixture and air). To pass through the catalyst bed.

At this time, the bismuth-molybdate catalyst is a multi-component bismuth molybdate catalyst, Mo 1-15, Bi 1-10, Fe 1-10, Co 1-10, K 0.01-1.5, and Cs 0-1.5 It is preferable that it is a catalyst which has a composition ratio.

Specifically, the multicomponent bismuth molybdate catalyst has a metal component having a divalent cation, a metal component having a trivalent cation, bismuth and molybdenum as constituents, and various multicomponent bismuth molybdates depending on the type and ratio of the constituents. It is possible to prepare a date catalyst. Cobalt and nickel are preferably used as the metal component having a divalent cation, and cobalt is most preferably used. According to one embodiment of the present invention, a multicomponent bismuth mole composed of cobalt, cesium, iron, bismuth, and molybdenum is used. Ribdate catalysts showed the highest activity for oxidative dehydrogenation.

Metal precursors for preparing these catalysts can be used as long as they are commonly used in the art. In the present invention, cesium nitrate as a precursor of cesium, and cobalt nitrate as a precursor of cobalt (cobalt) II) Nitrate), iron (Iron (III) Nitrate) as the precursor of iron, bismuth nitrate (Bismuth (III) Nitrate) as the precursor of bismuth, ammonium molybdate (Ammonium Molybdate) as the precursor of molybdenum Use The precursor ratio can be changed in various ways, in order to maximize the butadiene production yield to achieve in the present invention, the cesium / cobalt / iron / bismuth / molybdenum precursor ratio of 1 to 10/1 to 5 / 0.1 to 2/5 to 20 To adjust.

The cesium, cobalt, iron and bismuth precursors are simultaneously dissolved in distilled water and molybdenum precursors are separately dissolved in distilled water and then mixed with each other. In this case, an acidic solution (eg, nitric acid), etc., is used to increase the solubility depending on the precursor. Can be added. When the precursors are completely dissolved, the precursor solution containing cesium, cobalt, iron and bismuth is injected into the precursor solution containing molybdenum to co-precipitate the metal components. The co-precipitated solution is stirred for 0.5 to 24 hours, preferably 1 to 2 hours, to allow sufficient coprecipitation.

Water and other liquid components are removed from the stirred solution using a vacuum or centrifugal concentrator to obtain a sample of solid components. The obtained solid sample is dried at 20 to 300 ° C, preferably 80 to 200 ° C for 24 hours. After the solid catalyst thus produced is put into an electric furnace, the catalyst may be prepared 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 adsorbs the starting material alkene to the catalyst, and then reacts with two hydrogens of the alkene adsorbed oxygen in the catalyst lattice to produce conjugated diene, water and heavy by-products. -products), and the reaction proceeds through the pathway where the reactant molecular oxygen fills the empty oxygen sites of the catalyst lattice.

At this time, the heavy by-product is a solid state at room temperature of 20 to 29 ℃, for example, phenol, benzoic acid, benzophenone, fluorenone, maleic anhydride, phthalic anhydride, coumarin and the like.

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

The reaction product thus produced is contacted with an organic solvent mixed with water to remove water and heavy by-products by contacting with an organic solvent mixed with water instead of a separate extraction process as in the conventional method, as illustrated in the following examples. It is possible to effectively separate conjugated diene while preventing the blockage of the condenser.

The organic solvent usable here is not limited thereto, but may be selected from the group consisting of acetonitrile, N-methylpyrrolidone, N, N-dimethylformamide (DMF), acetone, ethanol, propanol, butanol and pentanol. It is more preferable to use species or more in view of mixing well with water.

In addition, the contact with the organic solvent is made at the top of the condenser connected in series to the bottom of the reactor, the supply of the solvent is preferably carried out using an LC pump. The feed rate is 0.5 to 2 h ^-1 and is preferably set to be about 1 to 2% in consideration of gas hourly space velocity (GHSV) of the feed.

After the post-treatment using the organic solvent, it is more preferable to further perform a cooling post-treatment step of 20 ° C. or less to dissolve heavy by-products to prevent blockage of the conduit or condenser.

According to the present invention, because the pipeline by the heavy by-product, which is a solid at room temperature of high boiling point, in particular, conduit of condenser (condenser) does not occur inherently, productivity is high, economical, Not only is the effect of providing a process for producing conjugated diene having excellent work stability and convenience, but also has the advantage of being directly applicable to the commercialization process.

1 is a schematic diagram of an apparatus including a contact process according to an embodiment of the present invention.
2 to 4 are photographs showing the occlusion phenomenon in the outer peripheral surface and the inner peripheral surface of the inlet side of the condenser and the inner side of the conduit, respectively, during the distillation of the reaction product after the oxidative dehydrogenation reaction according to the prior art (Comparative Example 1).
5 to 7 show the results of connecting the glass condenser to the bottom of the reactor in order to visually observe the change in the post-treatment of the reaction product with acetonitrile after the oxidative dehydrogenation reaction according to Example 1 of the present invention. 5 is a photograph of the glass capacitor before the test of Example 1, Figure 6 is a photograph of the glass capacitor experimented in accordance with Comparative Example 1, Figure 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 scope of the present invention is not limited thereto.

< Comparative example  1>

Butadiene production was carried out at 320 ° C. under a molar ratio of space velocity 75 h ⁻¹ , oxygen / butene = 1, steam / butene = 4, nitrogen / butene = 12. The reaction product gas containing butadiene at the bottom of the reactor filled with catalyst was passed through a condenser flowing with cooling water, and then collected in a wastewater container, and when a certain level or more was reached, the wastewater was extracted and disposed of.

As a result, the starting material butene input was 0.625 g / min, and the yield of this butene to butadiene was determined to be 92%. The types of heavy by-products were 0.13% benzoic acid, 0.19% phthalic anhydride, 0.20% cyclohexene dicarboxylic anhydride, Coumarin 0.04%, benzophenone 0.56%, fluorenone 0.06%, anthraquinone 0.04%, and unidentified heavy by-products 0.08% were observed. An obstruction was observed in (see FIGS. 2-4, 6).

< Example  1>

Butadiene production was carried out at 320 ° C. under molar ratios of space velocity 75 h ⁻¹ , oxygen / 1-butene = 1, steam / 1-butene = 4, nitrogen / 1-butene = 12. As shown in Figure 1, the catalyst was transferred to a reactor connected in series at the bottom of the reactor filled with acetonitrile was injected into the top of the condenser by using an LC pump to the butadiene-containing reaction product gas to pass through the condenser. The injection rate was 1.5 h ^-1 and sprayed, and then the process was collected in the wastewater container in the same manner as in Comparative Example 1, and when the predetermined level or more, the wastewater was extracted and discarded.

As a result, the input amount of starting material 1-butene was 0.625 g / min, and the yield of this butene to butadiene was measured at 92%. %, Coumarin 0.04%, benzophenone 0.56%, fluorenone 0.06%, anthraquinone 0.04%, and unidentified heavy by-products 0.08%. No duct occlusion was observed both on the medial side (see FIGS. 5 and 7).

< Example  2>

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

As a result, the input amount of starting material 2-butene was 0.417 g / min, and the yield of 2-butene to butadiene was measured at 78%, and the heavy by-product type was 0.5% benzoic acid, 0.78% phthalic anhydride, and cyclohexane dicarboxylic acid. Anhydrous 0.17%, coumarin 0.08%, benzophenone 0.35%, fluorenone 0.55%, anthraquinone 0.08%, and unidentified heavy by-products were also 0.62%. No pipeline occlusion was observed both inside and within the pipeline.

< Comparative example  2>

The same process as in Example 1 was repeated except that acetonitrile was replaced with diethyl ether, an organic solvent that was not mixed with water.

As a result, the starting material 1-butene dosage was 0.625 g / min, and the yield of butene to butadiene was measured at 92%. The heavy by-product types were 0.13% benzoic acid, 0.19% phthalic anhydride, and 0.2% cyclohexene dicarboxylic anhydride. , Coumarin 0.04%, benzophenone 0.56%, fluorenone 0.06%, anthraquinone 0.04%, and unidentified heavy by-products 0.08% (same as Comparative Example 1), after the completion of the process for about 24 hours, the outer peripheral surface of the conduit entry side of the condenser Pipe obstruction was observed both in the inner circumferential surface and in the inner side of the conduit.

As a result, according to Examples 1 and 2 of the present invention, a pipeline by a heavy by-product that is a solid at room temperature with a higher boiling point compared to Comparative Examples 1 and 2, in particular, a condenser pipeline. It was confirmed that the blockage does not occur at the source, and thus, the effect of providing a process for producing conjugated diene having high productivity, economical efficiency, and excellent work stability and convenience was found to be excellent.

Claims (12)

Contacting a reaction product gas comprising water, heavy by-products and conjugated diene with an organic solvent mixed with water, in the process of producing conjugated diene from an alkene by oxidative dehydrogenation. A process for producing a conjugated diene comprising the.
Iii) oxidative dehydrogenation of the reactants containing alkenes, air and steam continuously through the catalyst bed to obtain a reaction product gas comprising conjugated diene, residual water and heavy by-products. Making; And ii) contacting the reaction product gas with an organic solvent mixed with water to remove the water and heavy by-products contained in the reaction product.
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 Manufacturing process of conjugated diene.
3. The method according to claim 1 or 2,
The heavy by-products is a process for producing conjugated diene, characterized in that the solid at 20 to 29 ℃ (room temperature).
3. The method according to claim 1 or 2,
The alkene is a process for producing a conjugated diene, characterized in that using a hydrocarbon having 2 to 4 carbon atoms.
6. The method of claim 5,
The alkene is a C4 mixture comprising an excess of normal type butane and iso type butene, or C4-Raffinate-3 (C4-Raffinate-3) manufacturing process of the conjugated diene.
The method according to claim 6,
The C4-raffinate-3 is obtained by separating naphtha into ethylene, propylene, and crude C4 in an olefin plant, and extracting and distilling a double crude C4 to obtain C4-raffinate-1 (C4-Raffinate). C4-Raffinate-3 (C4-Raffinate-3) remaining after extraction of the normal type butene from C4-Raffinate-2 remaining after extraction of iso-type butane in -1). The manufacturing process of conjugated diene characterized by the above-mentioned.
3. The method according to claim 1 or 2,
The oxidative dehydrogenation reaction is carried out using a bismuth-molybdate catalyst in a reactant containing a stream: oxygen: steam in a molar ratio of 1: 0.5 to 10: 1 to 50 and a reaction temperature of 300 to 600 ° C. and a temperature of 50 to 5000 ° C. Process for producing a conjugated diene, characterized in that carried out at a space velocity of h ^-1 .
3. The method according to claim 1 or 2,
The oxidative dehydrogenation reaction includes a multi-tube fixed by filling a bismuth-molybdate-based catalyst and is carried out using a shell-tube reactor having a refrigerant circulation unit at an outer side thereof. .
3. The method according to claim 1 or 2,
The yield of conjugated diene obtained satisfies 90 to 92%.
3. The method according to claim 1 or 2,
Wherein said 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,
The process of contacting the reaction product gas with the organic solvent mixed with water is a process for producing a conjugated diene, characterized in that the injection pump is carried out at a spray rate of 0.5 to 2 h ^-1 using an LC pump on top of the condenser connected in series at the bottom of the reactor .

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