Styrene production process

FIELD: industrial organic synthesis.

SUBSTANCE: ethylbenzene blend obtained through blending fresh ethylbenzene and recycled ethylbenzene with styrene content not above 0.1 wt % is subjected to catalytic dehydrogenation in presence of water steam at feed-to-steam weight ratio 1:2, temperature 600°C, ethylbenzene blend supply space velocity 0.5-1.0 h-1, and reactor pressure maintained within a range of 45 to 80 kPa absolute. Multistep rectification gives rectified styrene with concentration of desired product at least 99.8% and phenylacetylene impurity level not higher than 0.01 wt %. Recycled ethylbenzene is blended with fresh ethylbenzene and resulting ethylbenzene blend containing no more than 0.1 wt % styrene is supplied to dehydrogenation unit.

EFFECT: increased ethylbenzene-to-styrene conversion, improved process selectivity, and reduced level of phenylacetylene in commercial product.

5 tbl

 

The invention relates to the field of catalytic processes, namely the obtaining of styrene by catalytic dehydrogenation of ethylbenzene, and can be used in the petrochemical industry.

Known methods for producing styrene by catalytic dehydrogenation of ethylbenzene on micaceous iron catalysts at temperatures 560-640°in the presence of water vapor, followed by separation of styrene from the products of dehydrogenation of ethylbenzene by multistage distillation with sequential allocation benzatropine faction, return ethylbenzene and styrene-rectified. CBM product of the column selection styrene-rectified subjected to additional distillation with return of distilled styrene in the column selection styrene-rectified (Kirpichnikov P.A. and other "Album of technological schemes of the main production of the synthetic rubber industry", HP, "Chemistry", 1980, p.100; Oil, gas and petrochemicals abroad, 1991, 8, p.100-102).

In known methods for producing styrene content of the styrene in return ethylbenzene up to 1.5 wt.%, which results when it is mixed with fresh ethylbenzene to styrene content in etilbenzene the charge coming into the dehydrogenation reactor, at the level of 0.4% wt. The conversion of ethylbenzene in this method usually does not exceed 60% wt. (U.S. patent No. 3326996, CL 260-669, publ. 1967; AMR the wines and other "Styrene", M, Tsniiteneftehim, 1996, ñ.38).

The closest in technical essence and the achieved result to an alleged invention is a Method of producing styrene (Patent RF №2120933, class C 07 C 15/46, 1998), which is chosen for the prototype.

According to the prototype of the receipt of the styrene-based process for the catalytic dehydrogenation of ethylbenzene in the environment of water vapor, where acibenzolar the mixture obtained after mixing of the fresh and return (recycling) of ethylbenzene, styrene content in the mixture at a level of not more than 0,15% wt. subjected to dehydrogenation at micaceous iron catalyst. The process is carried out at a temperature of 600-640°C, the mass ratio of raw materials: water vapor equal to 1:2 and a space velocity of etilbenzene charge 1 hour-1. The conversion of ethylbenzene is 67,9% wt., when the selectivity of the conversion of ethylbenzene to styrene 96,7%.

Simultaneously with the main reaction is the conversion of ethylbenzene to styrene by free-radical mechanism

under the action of high temperatures is formed from styrene by-product of phenylacetylene:

which adversely affects the quality of commercial styrene.

In accordance with GOST 10003-90 trademark styrene mass fraction of phenylacetylene (%) in the styrene tough schedule is planned:

- top grade, no more than0,01
- grade 1, no more than0,02

The disadvantages of this method are:

- low efficiency of the process, where the conversion of ethylbenzene reaches 67,9%, and the selectivity of conversion of ethylbenzene to styrene does not exceed 96,7%;

- high styrene content in etilbenzene charge for dehydrogenation (0,15% wt.), that does not allow trademark styrene desired quality content phenylacetylene less than 0.01% wt.

The purpose of the proposed invention is to improve the efficiency of the production of styrene by increasing the conversion and selectivity of the dehydrogenation of ethylbenzene to styrene, while also improving the quality of styrene by reducing the content of impurities phenylacetylene.

This goal is achieved the intended method of producing styrene, which is carried out by catalytic dehydrogenation of ethylbenzene in the presence of water vapor with subsequent separation of the products of the dehydrogenation of ethylbenzene by multistage distillation emitting benzatropine faction, etilbenzene fraction of recycling that is returned to the mixing with the original (fresh) ethylbenzene fed to the dehydrogenation, and styrene-rectified by maintaining the Oia concentration of styrene in etilbenzene the charge at the level not higher than 0.1% wt.

Comparative analysis of the proposed method with the prototype allows to conclude that the claimed method differs from the known content (concentration) of styrene in etilbenzene the charge applied to the dehydrogenation of not higher than 0.1% wt. This trick allows us to conclude that the proposed solution meets the criterion of "novelty".

Analysis of the known methods for producing styrene showed that the trend of decrease in the content (concentration) of styrene in etilbenzene the charge supplied to the dehydrogenation leads to increased conversion of ethylbenzene and improve the selectivity of the process of obtaining styrene. However, only the fact of maintaining the mass fraction of styrene in etilbenzene the charge supplied to the dehydrogenation, at the level of 0.1% allows to increase the conversion of ethylbenzene to styrene of 70% and above while reducing the mass fraction of impurities phenylacetylene (by-product) in the styrene less than 0.01%.

The essence of the proposed invention consists in the following. Acibenzolar the mixture obtained by the mixing of fresh ethylbenzene and benzene recycle content (concentration) of styrene is not higher than 0.1% wt. subjected to dehydrogenation at micaceous iron catalyst in the presence of steam at a mass ratio of raw materials: water vapor equal to 1:2, the temperature of 600°and volume / min net and feed etilbenzene charge 1 h -1according to the reaction equation:

The possible limits of the process of dehydrogenation:

- temperature°600-640
volumetric feed rate
etilbenzene charge, h-10,5-1,0
pressure (abs.) kPa45-80
- mass ratio etilbenzene
mixture and water vapor, not less than1:2

Under the influence of high temperatures on the free-radical mechanism, the formation of impurities phenylacetylene, which negatively affects the quality of commercial styrene

Contact the gas (the product of dehydrogenation)containing styrene, unreacted ethylbenzene, by-products, including mixed phenylacetylene, and water vapor is subjected to multi-stage distillation to obtain a styrene-rectified with the concentration of the basic substance (styrene) at least 99.8% by weight. and impurities phenylacetylene not more than 0.01% wt.

Return ethylbenzene-recycling is mixed with the original ethylbenzene and received ethylbenzene charge, with a styrene content of not higher than 0.1%is returned to the dehydrogenation unit.

Example (comparative, the prototype). Acibenzolar the mixture obtained after mixing of the fresh and return ethylbenzene, styrene content in a mixture of 0.15% wt. were subjected to dehydrogenation on the oxide catalyst. The process was carried out at a temperature of 600°C, the mass ratio of raw materials: water vapor equal to 1:2 and a space velocity of etilbenzene charge 1 hour-1. The conversion of ethylbenzene amounted to 67.9% at a selectivity of conversion of ethylbenzene to styrene 96,7%. The content of phenylacetylene in commodity styrene 0,015% wt.

Example 2. Acibenzolar the mixture obtained after mixing of the fresh and return ethylbenzene, styrene content in the mixture of 0.1% wt. were subjected to dehydrogenation on the oxide catalyst. The process was carried out with temperature 600°C, the mass ratio of raw materials: water vapor equal to 1:2 and a space velocity of etilbenzene charge 1 hour-1. The conversion of ethylbenzene was 70,0% wt. when the selectivity of the conversion of ethylbenzene to styrene 98,1%. The content of phenylacetylene in commodity styrene 0,010% wt.

The data of the other samples shown in the table.

Thus, the decrease in the concentration of styrene in etilbenzene the charge to less than 0.1% wt. increases the conversion of ethylbenzene to styrene, the improvement of the selectivity of the process and to decrease the content of phenylacetylene in the commodity situation.

Table

The influence of the content of styrene in etilbenzene the charge on the dehydrogenation process and the quality of commercial styrene
ExamplesThe styrene content in etilbenzene charge, wt.%The conversion of ethylbenzene to styrene,

wt.%.
The selectivity of the conversion of ethylbenzene to styrene, %The content of phenylacetylene in commodity styrene, wt.%
1 (prototype)0,1567,996,70,015
20,1070,098,10,010
30,0875,498,80,005
40,0478,299,20,003
5 (comparative)0,1269,197,60,012

The method of producing styrene by catalytic dehydrogenation of ethylbenzene in the presence of water vapor, followed by separation benzatropine faction return etilbenzene faction and styrene-rectified, characterized in that the concentration of styrene in etilbenzene the charge coming into the dehydrogenation reactor, is maintained at a level not higher than 0.1 wt.%, about jenna feed rate of etilbenzene mixture is 0.5-1.0 h -1the pressure in the reactor is maintained in the range 45-80 kPa (abs.), and the content of phenylacetylene in the styrene-rectified not more than 0.01 wt.%.



 

Same patents:

FIELD: petrochemical industry; methods of production of styrene.

SUBSTANCE: the invention is pertaining to the field of petrochemical industry, in particular, to the method of production of styrene. The invention provides for dehydrogenation of the ethylbenzene charge gained after mixing of the fresh ethylbenzene with the recycled ethylbenzene on the ferrioxide catalytic agent at presence of the steam at the mass ratio of the raw to the steam of no less than 1:2, at the temperature of 580-640°С and the volumetric speed of feeding of the ethylbenzene charge of 0.23-0.45 m3/h. The hydrocarbon condensate (the product of the dehydrogenation) containing styrene, the unreacted ethylbenzene, the by-products including the phenyl acetylene impurity before the stage of the rectification is hydrogenated using the palladium-containing catalytic agents at the temperature of 20-30°С, the volumetric speed of 4.5-5.0 m3/h-1 and at the volumetric ratio of the hydrogen : raw - 35-45. The technical result of the invention is the increased purity of the produced styrene without reduction of productivity of the whole process of the marketable styrene.

EFFECT: the invention ensures the increased purity of the produced styrene without reduction of productivity of the whole process of the marketable styrene.

1 tbl, 8 ex

FIELD: organic chemistry, chemical technology, catalysts.

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12 cl, 2 tbl

FIELD: hydrogenation-dehydrogenation catalysts.

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22 cl, 2 tbl, 16 ex

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4 cl, 2 tbl, 2 ex

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61 cl, 2 tbl, 2 dwg, 2 ex

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EFFECT: improved preparing method.

1 tbl, 6 ex

FIELD: hydrogenation-dehydrogenation catalysts.

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9 cl, 1 dwg, 3 tbl, 7 ex

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2 ex

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36 cl

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3 cl, 2 dwg, 4 tbl, 7 ex

FIELD: petrochemical industry; methods of production of styrene.

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1 tbl, 8 ex

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4 cl, 20 ex, 2 tbl, 2 dwg

FIELD: chemistry of aromatic compounds, chemical technology.

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61 cl, 2 tbl, 2 dwg, 2 ex

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EFFECT: improved method for isolation.

1 tbl, 2 dwg, 5 ex

FIELD: petrochemical processes.

SUBSTANCE: method provides for three-stage isolation of aromatic hydrocarbons in the separation, absorption, and separation stages using, as absorbent, ethylbenzene rectification bottom residue. Loaded absorbent containing diethylbenzene isomer mixture serves as starting material for production of alkylaromatic hydrocarbons including divinylbenzene.

EFFECT: reduced loss of aromatic hydrocarbons and improved economical efficiency of styrene production process.

2 dwg, 1 tbl, 5 ex

The invention relates to the chemical industry, in particular to prevent spontaneous polymerization vinylaromatic hydrocarbons, and can be used in the process of their separation from mixtures and/or purification by distillation

The invention relates to the field of petrochemical synthesis, namely the method of obtaining a linear unsaturated dimer-methylstyrene

The invention relates to a technology for purifying styrene from inhibitor and moisture and can be used in the synthetic rubber industry, in particular when cleaning for the synthesis of styrene butadiene-styrene rubber

The invention relates to improvements in the separation of styrene from unreacted ethylbenzene obtained at the stage of dehydrogenation of ethylbenzene to form styrene

FIELD: petrochemical processes.

SUBSTANCE: method provides for three-stage isolation of aromatic hydrocarbons in the separation, absorption, and separation stages using, as absorbent, ethylbenzene rectification bottom residue. Loaded absorbent containing diethylbenzene isomer mixture serves as starting material for production of alkylaromatic hydrocarbons including divinylbenzene.

EFFECT: reduced loss of aromatic hydrocarbons and improved economical efficiency of styrene production process.

2 dwg, 1 tbl, 5 ex

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