Benzene isolation process

FIELD: petrochemical processes.

SUBSTANCE: process involves extractive rectification in presence of extractant mainly containing aliphatic N-alkylamide, while toluene is introduced into rectification column point disposed between extractant inlet and the top of column.

EFFECT: reduced loss of extractant with distillate.

6 cl, 3 dwg, 6 tbl, 6 ex

 

The invention relates to the field of chemistry, particularly to a process of separating benzene from hydrocarbon mixtures containing aromatic and nonaromatic hydrocarbons by extractive distillation.

The need to use special methods of separation for separation of benzene from mixtures thereof with non-aromatic hydrocarbons due to the presence of significant deviations from the law of Raul in mixtures of benzene with saturated hydrocarbons, which results in rectifying the allocation of benzene to the content of impurities of saturated hydrocarbons, having a boiling point of at 15-20°above the boiling point of benzene. The use of extractive distillation for the separation and purification of aromatic hydrocarbons is widely known from the patent literature. As selective extractants proposed the use of N-methylpyrrolidone (Patent DE No. 2026693, IPC 7/08 C 07 C, publ. 23.12.1971), N-substituted morpholines (US Patent No. 5252200, IPC With 10 G 21/20, publ. 12.10.1993), dimethyl sulfoxide (US Patent No. 5399244, IPC 01 D 3/40, publ. 21.03.1995) and many others, including alkylamides. The advantage of alkylamides (dimethylformamide and dimethylacetamide) before other extractants is to lower the temperature of its boiling point. In addition, alkylamide contain trace amounts of hydrolysis products, which enter the reaction with impurities of serosoderjaschei compounds, additionally cleansing from them allocated benzene. Using alkylamides proposed, in particular, in US patent No. 3114783 (IPC 10 G 7/08, publ. 17.12.1963) and US patent No. 3884769 (IPC 01 D 3/34, publ. 20.05.1975).

However, the study found that these extractants form azeotrope with a number of saturated hydrocarbons having 6 and 7 carbon atoms, which leads to the ablation of extractants with the distillate of the column extractive distillation, and the content of the extractant in the distillate can reach several percent.

The closest in technical essence to the present invention is a method of separation of benzene (Patent GB No. 1556003, IPC 7/08 C 07 C, publ. 14.11.1979) from mixtures thereof with non-aromatic hydrocarbons by extractive distillation in the presence of an extractant containing N-alkylamide, according to which in order to reduce loss of the extractant with the distillate to the point extractive distillation column located between the point of introduction of the extractant and the top of the column, to supply water. The quantity of water and working conditions column extractive distillation pick up so that the water has completely evaporated and was bred in the composition of the distillate in the form of an azeotrope with the hydrocarbon.

The main disadvantage of this method is the use of water, as even a small water in output from the column saturated ex who ragent leads to its hydrolysis and corrosion of equipment, as well as the quality of benzene and need drying.

The present invention is the elimination of the loss of the extractant as a result of hydrolysis in the process of separating benzene from hydrocarbon mixtures containing aromatic and nonaromatic hydrocarbons by extractive distillation with simultaneous reduction of losses of extractant with process flows.

The problem is solved by the method of separation of benzene from hydrocarbon mixtures containing aromatic and nonaromatic hydrocarbons by extractive distillation in the presence of an extractant containing mainly aliphatic N-alkylamide, at which point the column extractive distillation, located between the point of introduction of the extractant and the top of the column component serves to help reduce the loss of the extractant with the distillate, and as the above component using toluene.

As extractant preferably dimethylformamide or dimethylacetamide.

Can also be used as a solvent of dimethylformamide or dimethylacetamide, containing 5-10 wt.% of toluene. This reduces the boiling point of the extractant without a noticeable decrease in its separating ability. In addition, it simplifies the process of separation of toluene needed to reduce p the losses of extractant, from recycled extractant.

Toluene, to help reduce the loss of extractant is introduced into the point extractive distillation column located between the point of introduction of the extractant and the top of the column in such a quantity that the relative volatility of the hydrocarbons forming an azeotrope with the extractant, is increased relative to the extractant to a degree sufficient for the separation of these hydrocarbons from the extractant. To do this, depending on the composition nah enough to deliver toluene, can be used to reduce losses of extractant with distilled water, in a volume ratio to the distillate, equal to 0.4 to 5.0:1.

For more efficient use of toluene in the column is injected above the point of feed of the extractant, so that at the point of introduction of the toluene concentration of the extractant in a mixture with hydrocarbons was significantly less than the concentration at the point of introduction of the extractant. The insertion point of toluene, to help reduce the loss of the extractant with the distillate, is located in the column so that between it and the input location extractant set from 2 to 15 theoretical plates.

It should be noted that above the point of introduction of the toluene in the extractive distillation column is a zone of rectification efficiency, necessary for the separation of toluene from nah.

E is strigent after separation of benzene and at least parts of toluene and separated from the extractant toluene returned to the extractive distillation column.

Separation of benzene and toluene from the extractant, and benzene from toluene carry out rectification. This can be used in different ways, including sequential separation from the extractant benzene and at least parts of toluene or separation from a solvent mixture of benzene with at least a part of the toluene, followed by the separation of benzene from toluene.

One option method is the option in which the extractant selected from the extractive distillation column, separated from the benzene and at least a portion of the toluene by distillation in the desorption column (desorber) with the selection of benzene from the top of desorber, and toluene - through side outlet located below the input of the extractant in desorber, followed by purification selected from toluene impurities of the extractant in an additional distillation column with the return of toluene and cubic product of this column in the extractive distillation column.

The advantage of this method over the known is the use to reduce losses of extractant component, not reacts with the extractant, quite easily detachable from both the extractant and the benzene conventional rectification. In addition, for whom adelene benzene in the proposed method it is possible to use a mixture of benzene with non-aromatic hydrocarbons, containing impurities of toluene, which simplifies the selection of benzene from benzylideneamino fractions of catalytic reforming, pyrolysis and other

The use of the method is illustrated by the following drawings and examples. See the drawings and the examples do not exhaust all of the options for implementing the method, and any other technological solutions, while respecting the essence of the invention set forth in the claims.

The original hydrocarbon mixture (Figure 1) on line 1 serves for the separation in the extractive distillation column K-1. In the same column at a point above the point of feed hydrocarbon mixture, served by lines 2 extractant and at a point above the place of entry of the extractant, served by lines 3 toluene. From the top of the K-1 on line 4 select nonaromatic hydrocarbons. From the cube K-1 rich extractant and toluene direct on line 5 in desorber K-2. From the top of K-2 on line 6 select the benzene. From the cube K-2 desorbed extractant in line 7 refer to the column K-3, in which the rectification from the top of the column to separate the toluene returned to K-1, line 3, from the extractant returned to K-1 on line 2.

Possible that from the top of desorber K-2 (2) line 6 select the benzene and at least a portion of the toluene, which is directed to the separation in the column K-3. From the cube K-2 desorbed extractant on line 2 of the TP is to participate in K-1. From the top of the To-3 line 7 select benzene, and from Cuba To-3 line 3 - toluene, return-1.

Alternatively, when from the top of K-2 (Figure 3) in line 6 select benzene from a cube K-2 desorbed extractant line 2 and return-1. Toluene is withdrawn from the K-2 side shoulder strap in the vapour or liquid phase and line 7 is sent to the column K-3 purification of toluene from the impurities of the extractant. Purified toluene from the top of the To-3 line 3 returns in K-2, and the extractant containing toluene, taken from the cube K-3 and the return line 9 To 2 below the sampling point of toluene or line 10 serves on the mixture of desorbed with an extractant selected from the cube K-2.

The submitted drawings do not contain necessary for the implementation of process heat exchangers and capacitive equipment and pumps, as well as possible schemes of heat recovery.

Below are examples illustrating the practical use of the proposed method.

Example 1

Method of extraction of benzene is carried out according to the scheme presented in figure 1.

The selection of benzene from a hydrocarbon mixture containing aromatic and non-aromatic hydrocarbons is carried out in the extractive distillation column having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 160 mm, filled with nozzle efficiency 40 theoretical plates (TT) in prisutstvuyuthie as extractant. Column equipped with a reboiler and a reflux condenser. The pressure in the atmospheric column. In column 6, 19 and 29 of theoretical plates, counting from Cuba columns give, respectively, the following threads:

- the original hydrocarbon mixture in an amount of 200 ml/hour at a temperature of 70°C;

- dimethylformamide in an amount of 500 ml/hour at a temperature of 80°C;

the toluene in the amount of 210 ml/hour at a temperature of 70°C.

The compositions of the incoming and outgoing flows are presented in table 1.

From the top of column K-1 at a temperature of 73°With selected non-aromatic hydrocarbons as distillate in the amount of 42 ml/hour. Reflux the number is 5. The composition of the distillate is presented in table 1.

From the cube column K-1 mixture of the extractant with benzene and toluene with a temperature of 136°send to desorber K-2 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 140 mm, filled with nozzle efficiency 36 TT 18 TT as the cube of the column. The pressure in desorber atmospheric. Desorber equipped with a reboiler and a reflux condenser. From the top of desorber taken at a temperature of 80°With 160 ml/h of benzene, the composition of which is presented in table 1. Reflux the number in the column is equal to 3.5.

From the cube of desorber mixture of the extractant with toluene to a temperature of 154°refer to the column rectification of toluene For-3 from the extractant, is within a diameter of 20 mm and a packing layer in the form of coils of nichrome wire with a height of 100 mm, filled with nozzle efficiency 26 TT 6 TT as the cube of the column. The pressure in the atmospheric column. Column equipped with a reboiler and a reflux condenser. Reflux the number in the column is equal to 2. From the top of the column is taken at a temperature of 111°With 210 ml/h of toluene, which is returned to the extractive distillation column.

From the cube columns are selected at a temperature of 160°500 ml/hour of dimethylformamide, do not contain toluene, which is also returned to the extractive distillation column.

The analysis of selected products and circulating dimethylformamide showed no products of its hydrolysis. The total loss of the extractant with the fraction of aromatic hydrocarbons and benzene are 0,0006 wt.% from the circulating solvent. The volume ratio of toluene to the distillate of the column extractive distillation is 5:1.

Example 2

Method of extraction of benzene is carried out according to the scheme presented in figure 3.

The selection of benzene from a hydrocarbon mixture containing aromatic and non-aromatic hydrocarbons is carried out in the extractive distillation column having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 160 mm, filled with nozzle efficiency 40 theoretical plates (TT) in the presence of dimethylformamide containing 10 wt.% toluene, as a solvent. Alanna equipped with a reboiler and a reflux condenser. The pressure in the atmospheric column. In column 6, 19 and 29 of theoretical plates, counting from Cuba columns, served respectively the following threads:

- the original hydrocarbon mixture in an amount of 200 ml/hour at a temperature of 70°C;

- dimethylformamide containing 10 wt.% toluene, in the amount of 550 ml/hour at a temperature of 80°C;

the toluene in the amount of 100 ml/hour at a temperature of 70°C.

The compositions of the incoming and outgoing flows are presented in table 2.

From the top of column K-1 at a temperature of 73°With selected non-aromatic hydrocarbons as distillate in the amount of 42 ml/hour. Reflux the number is 5. The composition of the distillate is presented in table 2.

From the cube of the column a mixture of the extractant with benzene and toluene with a temperature of 138°send to desorber K-2 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 140 mm, filled with nozzle efficiency 36 TT 20 TT as the cube of the column. The pressure in desorber atmospheric. Desorber equipped with a reboiler and a reflux condenser. From the top of desorber taken at a temperature of 80°With 160 ml/h of benzene, the composition of which is presented in table 2. Reflux the number in the column is equal to 3.5.

From the cube of desorber taken at a temperature of 158°485 ml/hour of dimethylformamide containing 10 wt.% toluene, which is returned to the extractive column rectify the promotion.

As a side selection of desorber 3 TT, counting from Cuba in the vapor phase is taken at a temperature of 147°With a mixture containing 63 wt.% toluene and 37 wt.% the extractant, which is directed to the separation in the column K-3, having a diameter of 20 mm and a packing layer in the form of coils of nichrome wire with a height of 100 mm, filled with nozzle efficiency 26 TT 3 TT as the cube of the column. The pressure in the atmospheric column. Column equipped with a reboiler and a reflux condenser. Reflux the number in the column is equal to 3.5. From the top of the column is taken at a temperature of 111°C 100 ml/HR of toluene, which is returned to the extractive distillation column.

From the cube columns are selected at a temperature of 158°With 65 ml/hour of dimethylformamide containing 10 wt.% toluene, which is also returned to the extractive distillation column.

The analysis of selected products and circulating dimethylformamide showed no products of its hydrolysis. The total loss of the extractant with the fraction of aromatic hydrocarbons and benzene amount of 0.0005 wt.% from the circulating solvent. The volume ratio of toluene to the distillate of the column extractive distillation is equal to 2.4:1.

Example 3

Method of extraction of benzene is carried out according to the scheme presented in figure 2.

The selection of benzene from a hydrocarbon mixture containing aromatic and non-aromatic in levaditi, exercise in the extractive distillation column having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 160 mm, filled with nozzle efficiency 40 theoretical plates (TT) in the presence of dimethylacetamide containing 10 wt.% toluene, as a solvent. Column equipped with a reboiler and a reflux condenser. The pressure in the atmospheric column. In column 11, 23 and 25 theoretical plates, counting from Cuba columns give, respectively, the following threads:

- the original hydrocarbon mixture in an amount of 200 ml/hour at a temperature of 70°C;

- dimethylacetamide, containing 10 wt.% toluene, in the amount of 600 ml/hour at a temperature of 80°C;

the toluene in the amount of 150 ml/hour at a temperature of 70°C.

The compositions of the incoming and outgoing flows are presented in table 3.

From the top of column K-1 taken at a temperature of 72°With non-aromatic hydrocarbons as distillate in the amount of 42 ml/hour. Reflux the number is 5. The composition of the distillate is presented in table 3.

From the cube of the column a mixture of the extractant with benzene and toluene with a temperature of 134°send to desorber K-2 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 140 mm, filled with nozzle efficiency 36 TT 18 TT as the cube of the column. The pressure in desorber atmospheric. Desorber SN is been the reboiler and reflux condenser. From the top of desorber taken at a temperature of 93°From 310 ml/hour of a mixture of benzene with toluene, which is sent for further separation. Reflux the number in the column is equal to 0.6.

From the cube of desorber taken at a temperature of 170°With 600 ml/hour dimethylacetamide, containing 10 wt.% toluene, which is returned to the extractive distillation column.

A mixture of benzene with toluene separated in the rectification column K-3, having a diameter of 20 mm and a packing layer in the form of coils of nichrome wire height 130 mm, filled with nozzle efficiency 32 CT 6 CT as the cube of the column. The pressure in the atmospheric column. Column equipped with a reboiler and a reflux condenser. Reflux the number in the column is equal to 1.7. From the top of the column is taken at a temperature of 81°With 160 ml/h of benzene, the composition of which is presented in table 3. From the cube columns are selected at a temperature of 125°With 150 ml/h of toluene, which is returned to the extractive distillation column.

The analysis of selected products and circulating dimethylacetamide showed no products of its hydrolysis. The total loss of the extractant with the fraction of aromatic hydrocarbons and benzene are 0,0006 wt.% from the circulating solvent. The volume ratio of toluene to the distillate of the column extractive distillation is equal to 3.6:1.

Example 4

Method of extraction of benzene carry out the Hema, presented in figure 2.

The selection of benzene from a hydrocarbon mixture containing aromatic and non-aromatic hydrocarbons is carried out in the extractive distillation column K-1 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 185 mm, filled with nozzle efficiency 46 theoretical plates (TT) in the presence of dimethylacetamide containing 5 wt.% toluene, as a solvent. Column equipped with a reboiler and a reflux condenser. The pressure in the atmospheric column. In column 11, 23 and 38 of theoretical plates, counting from Cuba columns give, respectively, the following threads:

- the original hydrocarbon mixture in an amount of 200 ml/hour at a temperature of 70°C;

- dimethylacetamide, containing by weight 5% toluene, in the amount of 500 ml/hour at a temperature of 80°C;

- toluene, 16 ml/hour at a temperature of 70°C.

The compositions of the incoming and outgoing flows are presented in table 4.

From the top of the column at a temperature of 72°With selected non-aromatic hydrocarbons as distillate in the amount of 42 ml/hour. Reflux the number is 5. The composition of the distillate is presented in table 4.

From the cube of the column a mixture of the extractant with benzene and toluene with a temperature of 136°send to desorber K-2 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire high is th 140 mm, filled with nozzle efficiency 36 TT 18 TT as the cube of the column. The pressure in desorber atmospheric. Desorber equipped with a reboiler and a reflux condenser. From the top of desorber taken at a temperature of 85°With 176 ml/hour of a mixture of benzene with toluene, which is sent for further separation. Reflux the number in the column is 1.5.

From the cube of desorber at a temperature of 172°select 500 ml/hour dimethylacetamide containing 5 wt.% toluene, which is returned to the extractive distillation column.

A mixture of benzene with toluene separated in the rectification column K-3, having a diameter of 20 mm and a packing layer in the form of coils of nichrome wire height 130 mm, filled with nozzle efficiency 32 TT 12 TT as the cube of the column. The pressure in the atmospheric column. Column equipped with a reboiler and a reflux condenser. Reflux the number in the column is 1.5. From the top of the column at a temperature of 81°select 160 ml/h of benzene, the composition of which is presented in table 4. From the cube columns are selected at a temperature of 125°16 ml/HR of toluene, which is returned to the extractive distillation column.

The analysis of selected products and circulating dimethylacetamide showed no products of its hydrolysis. The total loss of the extractant with the fraction of aromatic hydrocarbons and benzene are 0,0003 wt.% from circulating former is Magenta. The volume ratio of toluene to the distillate of the column extractive distillation equal to 0.4:1.

Example 5

Method of extraction of benzene is carried out according to the scheme presented in figure 3.

The selection of benzene from a hydrocarbon mixture containing aromatic and non-aromatic hydrocarbons is carried out in the extractive distillation column K-1 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire, 200 mm high, filled with nozzle efficiency 50 theoretical plates (TT) in the presence of dimethylformamide containing 5 wt.% toluene, as a solvent. Column equipped with a reboiler and a reflux condenser. The pressure in the atmospheric column. In column 12, 28 and 35 theoretical plates, counting from Cuba columns give, respectively, the following threads:

- the original hydrocarbon mixture in an amount of 200 ml/hour at a temperature of 70°C;

- dimethylformamide containing 5 wt.% toluene, in the amount of 650 ml/hour at a temperature of 80°C;

the toluene in the amount of 150 ml/hour at a temperature of 70°C.

The compositions of the incoming and outgoing flows are presented in table 5.

From the top of the column at a temperature of 69°With selected non-aromatic hydrocarbons as distillate in the amount of 50 ml/hour. Reflux the number equal to 2.5. The composition of the distillate is presented in table 5.

From the cube columns mixture extrag the NTA with benzene and toluene with temperature 139° With send in desorber K-2 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 140 mm, filled with nozzle efficiency 36 TT 20 TT as the cube of the column. The pressure in desorber atmospheric. Desorber equipped with a reboiler and a reflux condenser. From the top of desorber taken at a temperature of 80°With 150 ml/h of benzene, the composition of which is presented in table 5. Reflux the number in the column is equal to 3.5.

From the cube of desorber taken at a temperature of 159°From 575 ml/hour of dimethylformamide containing 5 wt.% toluene, which is returned to the extractive distillation column.

As a side selection of desorber 3 TT, counting from Cuba, in the vapor phase at a temperature of 145°select a mixture containing 68 wt.% toluene and 32 wt.% the extractant, which is directed to the separation in the column K-3, having a diameter of 20 mm and a packing layer in the form of coils of nichrome wire with a height of 100 mm, filled with nozzle efficiency 26 TT 5 TT as the cube of the column. The pressure in the atmospheric column. Column equipped with a reboiler and a reflux condenser. Reflux the number in the column is equal to 3.5. From the top of the column is taken at a temperature of 111°With 150 ml/h of toluene, which is returned to the extractive distillation column.

From the cube columns are selected at a temperature of 159°75 ml/hour of dimethylformamide containing 5 wt.% that is wala, which is also returned to the extractive distillation column.

The analysis of selected products and circulating dimethylformamide showed no products of its hydrolysis. The total loss of the extractant with the fraction of aromatic hydrocarbons and benzene amount of 0.0005 wt.% from the circulating solvent. The volume ratio of toluene to the distillate of the column extractive distillation is 3:1.

Example 6

Method of extraction of benzene is carried out according to the scheme presented in figure 2.

The selection of benzene from a hydrocarbon mixture containing aromatic and non-aromatic hydrocarbons is carried out in the extractive distillation column K-1 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 185 mm, filled with nozzle efficiency 46 theoretical plates (TT) in the presence of dimethylacetamide as a solvent. Column equipped with a reboiler and a reflux condenser. The pressure in the atmospheric column. In column 11, 23 and 38 of theoretical plates, counting from Cuba columns give, respectively, the following threads:

- The original hydrocarbon mixture in an amount of 200 ml/hour at a temperature of 70°C.

- dimethylacetamide in an amount of 500 ml/hour at a temperature of 80°C.

- toluene, 16 ml/hour at a temperature of 70°C.

The compositions of the streams are presented in table 6./p>

From the top of the column is taken at a temperature of 72°With non-aromatic hydrocarbons as distillate in the amount of 42 ml/hour. Reflux the number is 5. The composition of the distillate is presented in table 6.

From the cube of the column a mixture of the extractant with benzene and toluene with a temperature of 136°send to desorber K-2 having a diameter of 32 mm and a packing layer in the form of coils of nichrome wire height 140 mm, filled with nozzle efficiency 36 TT 18 TT as the cube of the column. The pressure in desorber atmospheric. Desorber equipped with a reboiler and a reflux condenser. From the top of desorber taken at a temperature of 85°With 176 ml/hour of a mixture of benzene with toluene, which is sent for further separation. Reflux the number in the column is 1.5.

From the cube of desorber taken at a temperature of 172°500 ml/hour dimethylacetamide, which is returned to the extractive distillation column.

A mixture of benzene with toluene separated in the rectification column having a diameter of 20 mm and a packing layer in the form of coils of nichrome wire height 130 mm, filled with nozzle efficiency 32 TT 12 TT as the cube of the column. The pressure in the atmospheric column. Column equipped with a reboiler and a reflux condenser. Reflux the number in the column is 1.5. From the top of the column is taken at a temperature of 81°With 160 ml/h of benzene, the composition of which is presented in table 6. the C cube columns are selected at a temperature of 125° With 16 ml/HR of toluene, which is returned to the extractive distillation column.

The analysis of selected products and circulating dimethylacetamide showed no products of its hydrolysis. The total loss of the extractant with the fraction of aromatic hydrocarbons and benzene are 0,0003% of the circulating solvent. The volume ratio of toluene to the distillate of the column extractive distillation equal to 0.4:1.

Table 1
Component wt.%PowerTolueneThe extractantThe distillateBenzene
Hydrocarbons, C54,8223,00
Hydrocarbons With614,3867,00
Hydrocarbons, C7
tKip.up to 90°0,92of 4.38
Heptane0,140,620,01
Methylcyclohexane 0,240,670,12
Benzene79,500,5was 2.7699,86
Toluene99,49of 1.570,01
Dimethylformamide0,01100<0,002<0,001
Table 2
Component wt.%PowerTolueneThe extractantThe distillateBenzene
Hydrocarbons, C54,8222,80
Hydrocarbons With614,3866,70
Hydrocarbons With7
tKip.up to 90°0,924,33
Heptane0,140,610,01
Methylcyclohexane0,24 0,770,10
Benzene79,500,52,7999,88
Toluene99,49101,100,01
Dimethylformamide0,0190<0,001<0,001

Table 3
Component wt.%PowerTolueneThe extractantThe distillateBenzene
Hydrocarbons With54,8222,90
Hydrocarbons With614,3868,46
Hydrocarbons, C7
tKip.up to 90°0,924,33
Heptane0,140,610,01
Meth is cyclohexan 0,240,770,06
Benzene79,500,32,9099,92
Toluene99,69100,030,01
Dimethylacetamide0,0190<0,002<0,001
Table 4
ComponentPowerTolueneThe extractantThe distillateBenzene
Hydrocarbons, C54,8222,90
Hydrocarbons With614,3869,86
Hydrocarbons With7
tKip.up to 90°0,924,33
Heptane0,140,610,01
Methylcyclohexane0,240,770,06
Benzene79,500,31,5099,92
Toluene99,6950,030,01
Dimethylacetamide0,0195<0,001<0,001

<0,001
Table 5
Component wt.%PowerTolueneThe extractantThe distillateBenzene
Hydrocarbons With621,3185,1
Heptane3,4513,70,01
Methylcyclohexane0,130,450,03
Benzene75,110,30,50at 99.95
Toluene99,6950,250,01
Dimethylformamide0,01 <0,001<0,001
Table 6
ComponentPowerTolueneThe extractantThe distillateBenzene
Hydrocarbons With54,8223,10
Hydrocarbons With614,3869,55
Hydrocarbons, C70,92
tKip.up to 90°to 4.41
Heptane0,140,620,01
Methylcyclohexane0,240,790,06
Benzene79,500,31,5099,92
Toluene99,690,030,01
Dimethylacetamide0,01100<0,001

1. Method of extraction of benzene from hydrocarbon mixtures containing aromatic and nonaromatic hydrocarbons by extractive distillation in the presence of an extractant containing aliphatic N-alkylamide, at which point the column extractive distillation, located between the point of introduction of the extractant and the top of the column component serves to help reduce the loss of the extractant with the distillate, characterized in that the above-mentioned component using toluene.

2. The method according to claim 1, characterized in that the extractant used is dimethylformamide or dimethylacetamide, or dimethylformamide containing 5-10 wt.% toluene, or dimethylacetamide, containing 5-10 wt.% of toluene.

3. The method according to claim 1, wherein toluene, to help reduce the loss of the extractant with distilled water, served in a volume ratio to the distillate, equal to 0.4 to 5.0:1.

4. The method according to claim 2, characterized in that the insertion point of toluene, to help reduce the loss of the extractant with distilled water, placed in a column so that between it and the input location extractant set from 2 to 15 theoretical plates.

5. The method according to claim 1 or 2, characterized in that the extractant after separation of benzene and at least parts of toluene and separated from the extractant toluene return in columns the extractive distillation.

6. The method according to claim 5, characterized in that the extractant selected from the extractive distillation column, separated from the benzene and at least a portion of the toluene by distillation in the desorption column with the selection of benzene from the top of desorber, and toluene through the side outlet located below the input of the extractant in desorber, followed by purification selected from toluene impurities of the extractant in an additional distillation column with the return of the cubic product of this column in the column extractive distillation or desorber.



 

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16 cl, 3 dwg

FIELD: petrochemical processes.

SUBSTANCE: C4-hydrocarbon fractions obtained by cracking and/or pyrolysis of hydrocarbon feedstock in presence of amine-type extractant are subjected to rectification additionally involving butylene-isobutylene fraction resulting from butylene-to-isobutylene isomerization and containing 30-70% butylenes, 25-65% isobutylene, and 3-8% butanes. Weight ratio of C4-hydrocarbon fractions to added butylene-isobutylene fraction is 1:(3-7).

EFFECT: increased separation efficiency.

3 ex

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: C5-hydrocarbons with different degrees of saturation are separated by extractive rectification in extractive rectification column using dimethylformamide as extractant followed by desorption of pentenes or pentadienes therefrom and passing desorbed extractant to extractive rectification column. Part of hot desorbed extractant is subjected to liquid-phase mixing with starting hydrocarbons at vigorous stirring, after which resulting mixture is introduced into column in liquid form.

EFFECT: reduced power consumption.

2 dwg, 1 tbl, 5 ex

The invention relates to a method of separating a mixture WITH4hydrocarbons by extractive distillation in the presence of the extractant on the basis of acetonitrile and can be used in the synthetic rubber industry, in particular the separation of the cracking butane-butylene fraction (BBF)

The invention relates to a method of purification of benzene from coke production and benzene obtained from fractions of pyrolysis oil from impurities saturated and unsaturated hydrocarbons, thiophene and carbon disulfide

The invention relates to the petrochemical industry, for the purification of benzene, obtained from a liquid hydrocarbon, C6-C7- fractions of pyrolysis oil from impurities unsaturated hydrocarbons

The invention relates to the field of production of benzene and high-octane mixtures

The invention relates to a method of separation of aromatic hydrocarbons from mixtures thereof with non-aromatic methods liquid extraction or extractive rectificatio and can be used in refining and petrochemical industries

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: C5-hydrocarbons with different degrees of saturation are separated by extractive rectification in extractive rectification column using dimethylformamide as extractant followed by desorption of pentenes or pentadienes therefrom and passing desorbed extractant to extractive rectification column. Part of hot desorbed extractant is subjected to liquid-phase mixing with starting hydrocarbons at vigorous stirring, after which resulting mixture is introduced into column in liquid form.

EFFECT: reduced power consumption.

2 dwg, 1 tbl, 5 ex

FIELD: petrochemical processes.

SUBSTANCE: C4-hydrocarbon fractions obtained by cracking and/or pyrolysis of hydrocarbon feedstock in presence of amine-type extractant are subjected to rectification additionally involving butylene-isobutylene fraction resulting from butylene-to-isobutylene isomerization and containing 30-70% butylenes, 25-65% isobutylene, and 3-8% butanes. Weight ratio of C4-hydrocarbon fractions to added butylene-isobutylene fraction is 1:(3-7).

EFFECT: increased separation efficiency.

3 ex

FIELD: petroleum industry.

SUBSTANCE: process in carried out in column having divider arranging in longitudinal direction to form the first section, the second one and the third bottom joint section, wherein extractive scrubber is includes before divider.

EFFECT: simplified technology.

16 cl, 3 dwg

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: catalysate of reforming of long gasoline fractions containing more than 2% benzene is separated by rectification into three fractions: light-boiling fraction containing mainly nonaromatic C4-C6-hydrocarbons and no more than 1%, preferably no more than 0.5%, benzene; high-boiling fraction containing mainly aromatic and nonaromatic hydrocarbons C7 or higher and no more than 1%, preferably no more than 0.5%, benzene; and benzene fraction boiling within a range of 70-95°C and containing no more than 0.1%, preferably no more than 0.02%, toluene and no more than 0.02% nonaromatic hydrocarbons with boiling temperature above 110°C. Benzene fraction is routed into benzene isolation process involving extractive rectification with polar aprotic solvent having ratio of dipole moment to square root of molar volume above 0.3 db/(cm3/g-mole)1/2, preferably above 0.4 db/(cm3/g-mole)1/2, and boiling temperature 150 to 250°C.

EFFECT: improved quality of benzene.

4 dwg, 2 tbl, 5 ex

FIELD: petrochemical processes.

SUBSTANCE: process involves extractive rectification in presence of extractant mainly containing aliphatic N-alkylamide, while toluene is introduced into rectification column point disposed between extractant inlet and the top of column.

EFFECT: reduced loss of extractant with distillate.

6 cl, 3 dwg, 6 tbl, 6 ex

FIELD: petrochemical processes.

SUBSTANCE: invention provides a process flow rate comprising at least (i) zone of extractive rectification in presence of polar extractant to produce distillate mainly containing butanes and butane(s); (ii) desorption zone wherein desorption of extractant gives stream containing mainly 1,3-butadiene and. as impurities, at least 2-butene(s) and acetylene hydrocarbons; and (iii) optionally rectification zone for mainly 1,3-butadiene-containing stream. In the latter, α-acetylene hydrocarbons are subjected to liquid-phase selective hydrogenation with hydrogen or hydrogen-containing mixture in presence of solid catalyst containing metal(s) exhibiting high activity in hydrogenation process, preferably non-precious metal(s) on solid support. Temperature is maintained within a range 5 to 75°C at contact time ensuring hydrogenation of no more then 6%, preferably no more than 2% of butadiene present. After hydrogenation, 1,3-butadiene is optionally additionally separated from impurities via rectification.

EFFECT: simplified process.

13 cl, 3 dwg, 2 tbl, 10 ex

FIELD: industrial organic synthesis.

SUBSTANCE: crude 1,3-butadiene is recovered from C4-fraction by extractive distillation using selective solvent on column separated by a partition installed along longitudinal direction of the column to form first and second subzones and underlying common column zone. The column is connected to preswitched flush column. Distillation column operation is controlled by energy supply with the aid of lower evaporator and distribution of a series of theoretical plates within underlying common zone to create bottom stream therefrom consisting of purified solvent.

EFFECT: simplified process technology.

23 cl

FIELD: petroleum processing.

SUBSTANCE: separation of crude C4-fraction comprises rectification of C4-fraction containing butanes, butenes, 1,3-butadiene, and small amounts of other hydrocarbons, including C4-acetylenes, 1,2-butadiene, and C5-hydrocarbons, via extractive distillation using selective solvent. Crude C4-fraction is fed to middle part of first extractive distillation column and selective solvent is added to column above crude C4-fraction introduction point. Vaporous side stream containing C4-acetylenes together with 1,3-butadiene1,2-butadiene, C5-hydrocarbons, and selective solvent, wherein concentration of C4-acetylenes is below self-decomposition threshold, is withdrawn from the first distillation column from the point below crude C4-fraction introduction point. Top stream containing crude C4-fraction components, which are less soluble in selective solvent than C4-acetylenes, are withdrawn from upper part of the first extractive distillation column.

EFFECT: optimized order of process operations.

21 cl, 1 dwg

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: in particular, invention aims at producing extraction dearomatized component from reformat of gasoline fraction, which component may be used in production of petroleum solvents such as hexane solvents. Process comprising countercurrent extraction of aromatic hydrocarbons with liquid selective extractant to separate dearomatized component (raffinate) and subsequent extractive rectification of resulting extract phase by distilling off aromatic hydrocarbons is characterized by that liquid selective extractant is diethylene glycol or triethylene glycol, countercurrent extraction is carried out at 125-140°C, extractive rectification is carried out using process steam in presence of saturated selective extractant wherein evaporation of water is performed with the aid of energetic steam, unsaturated selective extractant after extractive rectification and recycled gasoline are sent to extraction stage preliminarily using unsaturated selective extractant as heat carrier to generate process steam, and energetic steam condensate is used to heat recycled gasoline to 80-130°C.

EFFECT: enhanced process efficiency.

3 cl, 1 dwg, 1 tbl, 3 ex

FIELD: petrochemical processes.

SUBSTANCE: hydrocarbon mixture obtained by extractive distillation of C4-fraction using selective solvent, which mixture contains those C4-hydrocarbons, which are better soluble in selective solvent than butanes and butenes, is subjected to continuous separation. Mixture is supplied to first distillation column, wherein it is separated into top stream, containing 1,3-butadiene, propine, and, if necessary, other low-boiling components and, if necessary, water, and bottom stream containing 1,3-butadiene, 1,2-butadiene, acetylenes, and, if necessary, other high-boiling components. Proportion of 1,3-butadiene in bottom stream of the first distillation column is controlled in such a way as to be high enough to dilute acetylenes beyond the range wherein acetylenes can spontaneously decompose. Top stream from the first distillation column is passed to second distillation column, wherein it is separated into top stream, containing propine, and, if necessary, other low-boiling components and, if necessary, water, and bottom stream containing pure 1,3-butadiene.

EFFECT: simplified process and reduced power consumption.

4 cl

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