The method of producing styrene

 

(57) Abstract:

The invention relates to the production of styrene, in particular to a method for producing styrene by catalytic dehydrogenation of ethyl benzene in a two-stage adiabatic reactor at an elevated temperature in the presence of water vapor, benzene and toluene at a weight ratio of the ethyl benzene: benzene: toluene: water vapor equal to 1:0,03-0,08:0,095-0,22:2,26-3,06, which includes cooling, condensation of the contact strip, the separation of the aqueous and hydrocarbon phases, separation of the hydrocarbon phase is styrene, unreacted ethylbenzene, benzene, toluene and heavy products. According to the invention, a stream of benzene and toluene overheat above the reaction temperature and injected into the reactor in two streams to the first and second stages when the weight ratio of the input streams 1: 3-6. Technical result - increase the selectivity of the process and reducing the consumption of steam (energy). 1 Il.

The invention relates to the petrochemical industry and can be used in the production of styrene.

A known method of producing styrene (U.S. Pat. UK N 1176972) by the catalytic dehydrogenation of ethylbenzene in 556-704oC in the presence of water from toluene ethylbenzene 12.5-63,5 wt. %. The conversion of ethylbenzene is 63,5; selectivity of 93 mol.% (91,2 wt.% and the flow of water vapor to 4.68 tonnes per tonne of styrene in catalyzate.

The process is characterized by low conversion and significant energy consumption.

The closest in technical essence is a method of producing styrene (A. S. N 1018935, 1983) catalytic dehydrogenation of ethylbenzene at 550-650oC in the presence of water vapor, benzene and toluene at a molar ratio of benzene: benzene: toluene: water vapor equal to 1:0,04- 0,11:0,11-0,25:14-18, or a weight ratio of 1: 0,03-0,08:0,095-0,22:2,38-3,06. The conversion of ethylbenzene to 73.1%, a selectivity of 93 mol.% and the flow rate of water vapor 4,11 tonnes per tonne of styrene.

The process is characterized by low selectivity and high energy costs.

The aim of the invention is to increase the selectivity of the process and reduce energy consumption.

This goal is achieved by a method of producing styrene by catalytic dehydrogenation of ethylbenzene in the adiabatic reactor at an elevated temperature in the presence of water vapor, benzene and toluene at a weight ratio of the ethyl benzene: benzene: toluene equal 1:0,03 - 0,08:0,095 - 0,22, including cooling, condensation of contact of the gas times the Ola, benzene, toluene and heavy products. When the dehydrogenation is carried out in a two-stage adiabatic reactor at a weight ratio of ethylbenzene: steam 1:and 2.26 - 3,06, benzene and toluene overheat above the reaction temperature and injected into the reactor in two streams to the first and the second stage at a weight ratio of input streams 1:3-6.

The scheme of the proposed method to obtain styrene shown in the drawing.

Ethylbenzene coming from a warehouse line 1, is mixed with the return ethylbenzene from lines 2 and water vapor from line 3 and line 4 enters the evaporator 5 and the temperature of 150-180oC line 6 in the superheater 7, heated with superheated steam (not shown). In the superheater 7 proeminently the mixture is heated to a temperature of 500-550oC. the Superheated proeminently mixture according to line 8, mixed with superheated to 680-750oC water vapor from line 9, benzene and toluene with a temperature of 680 - 750oC from line 10 to line 11 enters the first stage of two-stage adiabatic reactor 12. In a reactor loaded with a catalyst based on oxides of iron, potassium and other components at a temperature of 580-650oC and a pressure close to atmospheric, goes prtray 580-615oC is heated to the reaction temperature 590 - 650oC due to the indirect heat exchange with superheated steam (not shown), is fed to the second stage reactor 12. Superheated to 680-750oC stream of benzene and toluene on line 13 is fed into the reaction zone of the second stage reactor. The second stage reactor 12 is loaded with a catalyst, similar to the first stage reactor.

Contact the gas from the second stage reactor 12 at a temperature of 580-615oC on line 14 is supplied to the cooling in the waste heat boiler 15. Contact the gas is cooled steam condensate from line 35.

In the exhaust-heat boiler 15 due to the heat of the cooling gas contact with 580-615oC to 180 - 260oC get the water vapor pressure of 2.5 to 4.5 ATA, line 36, mingling with the steam from the network on line 34, is used in the process of dehydrogenation of ethylbenzene.

Contact the gas from the recovery boiler 15 line 16 enters the scrubber 17 where it is cooled to a temperature 102-130oC, cleaned from mechanical impurities and heavy hydrocarbons and then on line 18 is directed to the condensation of 19. The condensate line 20 is sent to the decanter 21, from which the aqueous phase in line 22 is supplied to the cleaning, and then purified water condensate ispara 21 to line 23 is sent to superheat furnace 29 and used as fuel.

The hydrocarbon condensate from the decanter 21 through line 24 is directed to the rectification column of styrene in column 25.

On the column 25 through line 26 is allocated benzene, toluene, ethylbenzene, and line 30 styrene with severe products.

On the column 27 is allocated benzene and toluene and line 28 is directed to superheat furnace 29 where to overheat 680-750oC.

Return ethylbenzene from the column 27 is provided by 2.

Styrene with heavy products on line 30 is supplied to the column 31. On the column 31 through line 32 is allocated commodity styrene, and lines 33 - distillation residues of the distillation of styrene (KORS).

The introduction of benzene and toluene in the reaction zone of a two-stage adiabatic reactor for the dehydrogenation of ethylbenzene at a certain ratio to the speed of the reactor allows to increase the selectivity of the process of obtaining styrene and reduce the consumption of water vapor.

Example 1

The process is carried out according to a known method. On the dehydrogenation serves 350 kg/h of benzene. Benzene and toluene is introduced into the reaction zone by a single thread with ethylbenzene. The ratio of benzene: benzene: toluene: water vapor stand 1: 0,055:0,158:2,72 by weight. The dehydrogenation exercise of wantof when the temperature at the inlet to each stage of the reactor 620oC.

The conversion of ethylbenzene was 73.1%, the selectivity to styrene of 91.3 wt.% and the flow rate of water vapor 4,11 tonnes per tonne of styrene in contact with gas.

Example 2

The process is carried out according to the proposed method. On the dehydrogenation serves 350 kg/h of benzene. Benzene and toluene is introduced into the reaction zone two threads at a weight ratio of threads on the first and the second stage reactor of 1:3 to line 10 of the superheating furnace 29 in the first stage reactor and line 13 in the second stage reactor from overheating of the furnace 29. The temperature of the streams in lines 10 and 13 is 690oC.

The total ratio of benzene: benzene: toluene: water vapor stand 1: 0,055: 0,158: 2,62 by weight. The dehydrogenation is carried out in a two-stage reactor on one of the known catalysts based on oxides of iron, potassium and other components when the temperature at the inlet to each stage of the reactor 620oC.

The conversion of ethylbenzene was $ 73.3%, the selectivity to styrene of 91.8 wt.% and the flow rate of water vapor 3.9 tons per ton of styrene in contact with gas.

Example 3

The process is carried out according to the proposed method. On the dehydrogenation serves 350 kg/h of benzene. Benzene and toluene is introduced into the reaction zone two threads Eector and 13 in the second stage reactor from overheating of the furnace 29.

The temperature of the streams in lines 10 and 13 is 705oC.

The total ratio of benzene: benzene: toluene: water vapor stand 1: 0,055: 0,158: 2,44 by weight. The dehydrogenation is carried out in a two-stage reactor on one of the known catalysts based on iron, potassium and other components when the temperature at the inlet to each stage of the reactor 620oC.

The conversion of ethylbenzene was 73,4%, the selectivity to styrene of 92.5 wt.% and the flow of water vapor to 3.6 tonnes per tonne of styrene in contact with gas.

Example 4

The process is carried out according to the proposed method. On the dehydrogenation serves 350 kg/h of benzene. Benzene and toluene is introduced into the reaction zone two threads at a weight ratio of threads on the first and the second stage reactor 1:5 - line 10 of the superheating furnace 29 in the first stage reactor and line 13 in the second stage reactor from overheating of the furnace 29. The temperature of the streams in lines 10 and 13 is 710oC.

The overall ratio of benzene: benzene: toluene: water vapor stand 1: 0,055: 0,158: 2.26 and weight. The dehydrogenation is carried out in a two-stage reactor on one of the known catalysts based on oxides of iron, potassium and other components when the temperature at the entrance to the wt.% and the flow rate of water vapor 3.3 g per tonne of styrene in contact with gas.

Example 5

The process is carried out according to the proposed method. On the dehydrogenation serves 350 kg/h of benzene. Benzene and toluene is introduced into the reaction zone two threads at a weight ratio of threads on the first and the second stage reactor 1:6 - line 10 of the superheating furnace 29 in the first stage reactor and line 13 in the second stage reactor from overheating of the furnace 29. The temperature of the streams in lines 10 and 13 is 720oC.

The total ratio of benzene: benzene: toluene: water vapor stand 1: 0,055:0,158: 2.26 and weight. The dehydrogenation is carried out in a two-stage reactor on one of the known catalysts based on oxides of iron, potassium and other components when the temperature at the inlet to each stage of the reactor 620oC.

The conversion of ethylbenzene was $ 73.5%, the selectivity to styrene br93.1 wt.% and the flow rate of water vapor 3.3 g per tonne of styrene in the contact gas.

The method of producing styrene by catalytic dehydrogenation of ethylbenzene in the adiabatic reactor at an elevated temperature in the presence of water vapor, benzene, toluene at a weight ratio of the ethyl benzene : benzene : toluene, equal 1 : 0,03 - 0,08 : 0,095 - 0,22, including cooling, condensation of the contact strip, the separation of water and carbon from the products, characterized in that the dehydrogenation is carried out in a two-stage adiabatic reactor at a weight ratio of ethylbenzene : steam 1 : and 2.26 - 3,06, benzene and toluene overheat above the reaction temperature and injected into the reactor in two streams to the first and second stages when the weight ratio of the input streams 1 : 3 - 6.

 

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