The method of producing styrene

 

(57) Abstract:

The invention relates to the petrochemical industry and can be used in the process for the joint production of propylene oxide and styrene. Styrene produced by the catalytic dehydration of methylphenylcarbinol catalyst containing alumina. Use fraction methylphenylcarbinol containing heavy products with a boiling point between 150 and 400oC in the amount of 0.5 to 30 wt. %, which adds water vapor or a mixture of water vapor and hydrogen-containing gas, or nitrogen, or carbon dioxide, or mixtures thereof, and heated to reaction temperature in a single stream prior to being fed into the catalytic zone. This method allows to increase the output of styrene and service life of the catalyst. table 1.

The invention relates to the petrochemical industry and can be used in the process of joint receipt of polypropyleneoxide and styrene.

There is a method of dehydration of methylphenylcarbinol in the vapor phase at a temperature of 270-350oC in the presence of the oxide catalyst dehydration, with the introduction into the reaction zone from 0.1 to 4 moles of steam per 1 mol of the raw material dehydration. Moreover, the raw material may contain not more than 60 wt.% of acetophenone. (PA is residual high yield of styrene.

The closest in technical essence is a method of producing styrene by dehydration of methylphenylcarbinol on the catalyst is aluminum oxide (A. C. the USSR 1309518, MKI C 07 C 15/46, 1995) in a two-stage adiabatic reactors with intermediate heating of the contact strip and the intermediate separation of resin from the faction of methylphenylcarbinol supplied to the dehydration, in order to increase the yield of styrene selected resin in an amount of 0.6 to 3 wt. %injected into a fraction methylphenylcarbinol supplied to the dehydration. The disadvantage of this method is the low duration of operation of the catalyst by reducing his activity as a result of tasmainia and deposits it sodium salt.

To increase the output of styrene catalytic dehydration of methylphenylcarbinol carried out on the catalyst containing alumina, using raw materials containing 0.5-30 wt.%heavy products, having a boiling point of 150 to 400oC, formed during oxidation of benzene to cumene hydroperoxide, epoxidation of propylene and separation of the products of the epoxidation process the joint production of propylene oxide and styrene. In raw materials add water vapor, or a mixture of water vapor and hydrogen is P CLASS="ptx2">

Heavy products are usually a mixture of esters and ethers of methylphenylcarbinol, and are injected into the charge supplied to the dehydration by any known method, for example, a special introduction pre-separated from the heavy product fraction or the introduction of these products by the use of a special mode of rectification during the separation of tar and heavy from the composition of the products of the epoxidation of propylene by hydropredict ethylbenzene.

Distinctive features of the invention are the use of raw materials containing heavy products with a boiling point between 150 and 400oC in the amount of 0.5-30 wt. percent, and heating in a single stream with water vapor, or a mixture of water vapor and hydrogen, or nitrogen, or carbon dioxide, or mixtures thereof, to the reaction temperature before entering the catalytic zone. When comparing essential features of the invention with the prototype, it is possible to draw a conclusion on the conformity of the proposed technical solution the criterion of "novelty". In the prototype used a different number of heavy products and are heavy products have a different composition. Add in methylphenylcarbinol heavy, has a different composition determined boiling point, which were wound the reaction before entering the catalytic zone provides additional amount of styrene due to the decomposition of these wastes and to increase the service life of the catalyst by reducing the processes of its pitch. The introduction of new distinctive characteristics in combination with the achieved effect is not described in any similar way, refers to the "inventive step" of the proposed method. The claimed invention meets the criterion of "industrial applicability" because it is feasible in industry, for example, in an industrial process, the joint production of propylene oxide and styrene.

The inventive method is illustrated by the following examples:

Example 1 (comparative)

On dehydration in a two-stage adiabatic reactor serves 1000 g/h fraction methylphenylcarbinol, pre-cast from resin. Fraction of methylphenylcarbinol contains 28,1 wt.%of acetophenone, to 71.9 wt. %methylphenylcarbinol and a minor amount of ethylbenzene, benzaldehyde, benzoic acid. As catalyst, use of active alumina. In the reactor serves water vapor when the mass ratio of the fraction of methylphenylcarbinol : water vapor, which is 1 : 1,1. The dehydration is carried out at 320oin each stage.

When this conversion methylphenylcarbinol amounted to the value of 98.1 per cent. The output of styrene on the decomposed methylphenylcarbinol $ 94.2 mol.%.

After 400 hours. presumably carbinol was 92.6 mol.%.

Example 2 (comparative)

The experience is conducted according to the procedure as in example 1. In a fraction of methylphenylcarbinol injected resin, selected from the faction of methylphenylcarbinol when it is cleaned in the amount of 3% by weight fraction. The dehydration is carried out at 320oC in each stage and the dilution fraction methylphenylcarbinol water vapor / mass ratio of 1:1,1. Volumetric feed rate fraction methylphenylcarbinol 0.6 h-1. When this conversion methylphenylcarbinol amounted to 98.1%. The output of styrene on the decomposed methylphenylcarbinol reached 97.2 mol.%.

After 30 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 89.3 per cent. The output of styrene on the decomposed methylphenylcarbinol was value to 83.5 mol.%.

Example 3

The experience is conducted according to the procedure as in example 1. In a fraction of methylphenylcarbinol impose heavy products, highlighted by distillation in the temperature range 150-400oC from the faction resins obtained when cleaning methylphenylcarbinol. The number of heavy products entered thus in a fraction of methylphenylcarbinol amounted to 30 wt. %. According to the results of the analysis by chromatography of heavy products contained, by weight. %: a simple ether methylphenylethylamine products. The dehydration is carried out at 320oC in each stage and the dilution fraction methylphenylcarbinol water vapor / mass ratio of 1:1,1 using as the catalyst active-alumina. When this conversion methylphenylcarbinol was 99.4%, the conversion of heavy products with 97.1%. The output of styrene on the decomposed methylphenylcarbinol was 109,3 mol.%.

Additionally, the resulting ethylbenzene and acetophenone, with access to the decomposed methylphenylcarbinol respectively to 2.4 mol.% and to 3.5 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 96,3%. The output of styrene on the decomposed methylphenylcarbinol amounted to the value of 106.5 mol.%.

Example 4

The experience carried out by the method of example 3. In the course of the separation fraction methylphenylcarbinol from the resin by the method of rectification it impose heavy products in an amount of 5 wt. %, wikipaedia within 150-400oC. According to the results of chromatographic analysis of the composition of heavy products includes, in wt.%: a mixture of ethers of phenylethanol and methylphenylcarbinol 45,8; a mixture of ethers of phenylethanol and methylphenylcarbinol with monopropylene - 40,1; a mixture of benzoate of phenylethanol and methylphenylene heavy products - 97,7%. The output of styrene on the decomposed methylphenylcarbinol was 98,01 mol.%.

Additionally, the resulting ethylbenzene, with access to the decomposed methylphenylcarbinol - 1 mol.% and acetophenone, with access to the decomposed methylphenylcarbinol - 2,3 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 96,3%. The output of styrene on the decomposed methylphenylcarbinol was value to 96.8 mol.%.

Example 5

Dehydration of methylphenylcarbinol carried out according to the method of example 3, with the introduction of a faction of methylphenylcarbinol of 0.5% heavy products using as a catalyst the aluminum oxide containing molybdenum in an amount of 3 wt.% based on the metal.

Conversion methylphenylcarbinol was 98.4%; conversion of heavy products - 97,7%. The output of styrene on the decomposed methylphenylcarbinol was of 97.8 mol.%.

Additionally, the resulting ethylbenzene, with access to the decomposed methylphenylcarbinol to 0.7 mol.% and acetophenone, with access to the decomposed methylphenylcarbinol -1,3 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 96,3%. The output of styrene on the decomposed methylphenylcarbinol was the greates what Itanium as catalyst the aluminum oxide containing molybdenum in an amount of 3 wt.% and 0.5 wt.% iron, calculated on the metal.

Conversion methylphenylcarbinol was 98,8%; conversion of heavy products - 98,0%. The output of styrene on the decomposed methylphenylcarbinol were $ 97.6 mol.%.

Additionally, the resulting ethylbenzene and acetophenone, with a total output of 2.2 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 97.3%. The output of styrene on the decomposed methylphenylcarbinol amounted to the value of 94.6 mol.%.

Example 7

Dehydration of methylphenylcarbinol carried out in the conditions of example 4 using as the catalyst of zeolite NaX. The temperature in the reactor 250oC. Volumetric feed rate fraction methylphenylcarbinol - 2 h-1the dilution fraction methylphenylcarbinol water vapor / mass ratio equal to 1: 0.5 in.

Conversion methylphenylcarbinol was 98,3%; conversion of heavy products - 98,9%. The output of styrene on the decomposed methylphenylcarbinol amounted 97,3 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 96,3%. The output of styrene on the decomposed methylphenylcarbinol amounted to the value 95,7 in the reactor 280oC. Volumetric feed rate fraction methylphenylcarbinol - 0.8 h-1. The experience is carried out at a dilution fraction methylphenylcarbinol water vapor and hydrogen mass ratio equal to 1:0,4:0,1.

Conversion methylphenylcarbinol was 99.7%; the conversion of heavy products - 97,7%. The output of styrene on the decomposed methylphenylcarbinol was is 98.8 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 96,3%. The output of styrene on the decomposed methylphenylcarbinol amounted to the value of 96,4 mol.%.

Example 9

Dehydration of methylphenylcarbinol carried out in the conditions of example 4. The temperature in the reactor 300oC. Volumetric feed rate fraction methylphenylcarbinol - 0.6 h-1. The experience is carried out at a dilution fraction methylphenylcarbinol water vapor and nitrogen mass ratio equal to 1:0,4:0,2.

Conversion methylphenylcarbinol amounted to 98.2%; conversion of heavy products - 97,7%. The output of styrene on the decomposed methylphenylcarbinol amounted to 96.8 mol.%.

Additionally, the resulting ethylbenzene and acetophenone, with total access to the decomposed methylphenylcarbinol 1,8 mol.%.

After 200 hours. continuous operation conversion METHYLPHENOL.%.

Example 10

Dehydration of methylphenylcarbinol carried out in the conditions of example 4. The temperature in the reactor 300oC. Volumetric feed rate fraction methylphenylcarbinol - 0.6 h-1. Experience conducting dilution fraction methylphenylcarbinol water vapor and CO2mass ratio equal to 1:0,4:0,02.

Conversion methylphenylcarbinol was 99.4%; the conversion of heavy products is 97.6%. The output of styrene on the decomposed methylphenylcarbinol amounted to 96.3 mol.%.

Additionally, the resulting ethylbenzene, with access to the decomposed methylphenylcarbinol to 0.9 mol.% and acetophenone, with access to the decomposed methylphenylcarbinol - 2,4 mol.%.

After 200 hours. continuous operation conversion methylphenylcarbinol amounted to the value of 96,4%. The output of styrene on the decomposed methylphenylcarbinol was value for 91.1 mol.%.

The quality of the styrene-rectified received on the proposed method of producing styrene by dehydration of methylphenylcarbinol, given in the table.

As seen from the above examples, the use of the proposed method of producing styrene by dehydration of methylphenylcarbinol will allow to increase the output of styrene to obtain an additional amount of acetophenone and Ativ the phase dehydration fraction methylphenylcarbinol on the catalyst, containing aluminum oxide in the presence of water vapor and the additive resin, characterized in that the resin used heavy products, having a boiling point of 150 - 400oC and formed on the stages of the oxidation of benzene to cumene hydroperoxide, epoxidation of propylene and separation of the products of the epoxidation process the joint production of propylene oxide and styrene in the amount of 0.5 - 30 wt.%, the process is carried out by adding a faction of methylphenylcarbinol water vapor or water vapor and hydrogen-containing gas, or nitrogen, or carbon dioxide, or mixtures thereof and heated in the same thread before serving in the catalytic zone.

 

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