SU988812A1 - Method for drying oil layer formed in stratifying products of synthesis of pyridine bases - Google Patents

Description

The invention relates to a method of drying the oil layer, the formation of tsegos when exfoliating the products of the synthesis of pyridine bases and can be used in the chemical industry. The closest to the invention in its technical essence is a method of drying the oil layer formed during the delamination of the synthesis products in the production of 2-methyl-5-vinylpyridine, 2-picoline and corrosion inhibitors, which consists in drying the oil-azeotropic layer by distillation with condensation of the upper stream, subsequent delamination of the condensate obtained and return of its upper layer to the distillation column. After condensation, the heterodzotropic mixture is exfoliated in a Florentine vessel. The upper hydrocarbon layer is returned to the drying column, and the aqueous layer is sent for processing to the distillation column together with the aqueous layer of the Cl process. However, in the Florentine vessel, especially in the presence of a large amount of ammonia, delamination is difficult, and the oil layer returned to recycling contains up to l.30% of water, which leads to its re-evaporation to unproductive energy consumption. In turn, the aqueous layer contains a large amount of pyridine bases (/ 20-25%). It is sent for separation into a distillation column of the pyridine bases from the aqueous layer. A large number of pyridine bases in the water layer increases the load on the column and, accordingly, increases the energy consumption for their distillation. In addition, the drying of the oil layer according to a known method is not deep enough. It can be carried out to a residual water content of at least fjO, 9-l%. The aim of the invention is to reduce the energy consumption for drying the oil layer and increasing the degree of drying. This goal is achieved by the fact that, according to the method of sedimentation of the oil layer, when degassing the products of the synthesis of pyridine bases, the heteroazeotropic distillation is carried out in the presence of aromatic, alicyclic or

paraffin hydrocarbons in the amount of 4-30 wt.% in the oil layer with condensation of the upper steam flow, subsequent delamination and return of the upper layer of condensate to the column in two streams, the first of which is fed to the top of the column, and the second - to the plate of the column; which corresponds to the composition of the return stream.

Benzene, n-hexane, toluene, cyclohexane, methylcyclohexane and others can be used as hydrocarbons. The introduction of them provides recycling with a water content of about 5%.

Returning the oil layer of distillate to the column in two streams resulted in a deeper drying of the oil layer, since according to the method, a recycle containing a small amount of water as compared with the initial mixture is directed to the column plate with the corresponding composition of the liquid phase, which contributes to a more complete removal of water from the bottom of the column. Another part of the recycling to the upper plates contributes to a more intensive removal of water from the upper part of the column.

The method is most effective when drying a raw material containing ammonia, which significantly worsens the distribution of pyridine bases between water and the oil layer.

The drawing shows the technological scheme of the proposed method.

The oil layer is fed via line 1 to the drying column 2, heated through the boiler 3. A steam stream is taken from the top of the column, which is condensed in condenser 4 and exfoliated in a septic tank 5. The upper hydrocarbon layer is returned to the column by two streams: lines b - to the top of the column and along line 7 to 10-15 plates below.

The aqueous layer through line 8 is directed to distilling the organic material together with the aqueous layer formed during the separation of the products of the synthesis of pyridine bases. A drained oil layer is taken from the bottom of the column along line 9. Polines 10 feed the system with hydrocarbons.

The reduction of energy consumption in the process of drying is achieved due to the fact that reflux with a lower concentration of water enters the drying column, than in the prototype. With heteroazeotropic drying (according to the prototype), for every 100 kg of reflux, 30 kg of water are returned, which must again be evaporated. According to the proposed method for 100 kg of reflux, 2-5 kg of water are returned. Wherein

For evaporation of 30 kg of water, 16170 kcal / h is required, and for evaporation of 5 kg of water contained in reflux using the proposed method, 5X539 2695 kcal are required. , 0 is 6 times less. Approximately as many calories are required for evaporation of 1 kg of solvent introduced with reflux as for 1 kg of pyridine bases (/ 85-94 kcal / k. Therefore, a small amount of solvent entering with reflux does not cause such heat consumption as evaporation water.

Example 1. In a separating funnel load 1.0 ml of benzene, 8 ml of pyridine bases (PO) and 10 ml of water. PO include pyridine, 2-picoline, 4-picoline, 2,4-lutidine, methyl ethyl pyridine (MEP), 4-vinyl pyridine, methyl vinyl pyridine (MBP), 4-methyl-3-ethyl pyridine in equal weight quantities. The mixture is stirred for 15 minutes, exfoliated for 30 minutes and the layers formed are analyzed for the content of pyridine bases.

The results of the analysis are given in table. one.

Example 2 (for comparison). In the separating funnel load the mixture of the same composition as in example 1, but without benzene. The contents of the funnel are mixed and allowed to exfoliate for 30 minutes, after which the content of the components in each of the layers is determined and the distribution coefficients of the components are calculated. The results of the analysis are given in table. 2

Thus, when carrying out an extraction with a composition close to that of the actual mixture, the water content in the oil layer is 30% by weight, and the PO content in the aqueous layer is 20% by weight.

Example 3. The drying of the oil layer / obtained during the synthesis of MEP is carried out according to the scheme shown in the drawing in the presence of 4% benzene. The effectiveness of the drying column 20 plates.

The mixture with the following composition, may, is received for drying.

Water9.0

IEP. 81.0

Picolin 10.0

On the 10th (the score of the plates hereinafter from the top of the column), the plate of the column is served with 100 g / h of the indicated mixture and 4 g / h of benzene. 27 g / h of the mixture is taken from the top of the column, which is layered into two layers. This forms 7 g / h of the aqueous layer and 20 g / h of the oil layer.

The composition of the aqueous layer, wt.%: Water 95; SO 5. The composition of the oil layer: May. %: water 3.5; benzene 16.0; ON 80.5.

The oil layer is returned to the column at two points: the top of the column and the 7th plate. The ratio of flows is 1: 1. Pyridine bases containing 0.20% water are taken from the cube.

Example 4. On the 10th plate of a continuous column, with an efficiency of 20 plates, an oil layer is fed in an amount of 100 g / h. The composition of the oil layer, May.%: Water 9, MEP 81; the amount of picolines is 10%.

On the same plate serves 4 g / h, methylcyclohexane. 26.6 g / h of the mixture is taken into the distillate, which is layered into two layers. 10.8 g / h of an aqueous layer and 15.8 g / h of an oily layer are obtained.

The composition of the aqueous layer, wt.%: Water 96, the amount of 4; The composition of the oil layer, wt.%: Water 3, O {methylcyclohexane 22; amount 75

The oil layer is returned to the column in two streams - on the top of the column and on the 10th plate. ,

The ratio of return streams is 8: 1.

From the cube, pyridine bases are taken in the amount of 73.4 g / h with a water content of 0.15%.

Example5. An oil layer in the amount of 100 g / h of the composition specified in Example 3 is fed to the plate for a continuous column with an efficiency of 20 plates.

Together with the oil layer, 4 g / h of toluene is fed. 26.6 g / h of the mixture is taken from the top of the column, which is stratified into two layers. 8.8 g / h of the aqueous layer and 17.8 g / h of the oily layer are obtained. The composition of the aqueous layer, May.%: Water 96.2, the amount of 3.8. The composition of the oil layer, May.%: Water 2.0; toluene 21.4; amount of 76.6.

The oil layer is returned to the column in two streams: in the upper part of the column in the amount of 2 g / h and on the 15th plate in the amount of 15.8 g / h. Ratio of flows.

From the cube of the column I select pyridine bases (73.4 g / h). Vrda content in the bottom product is 0.03%.

Example 250 g of a mixture having the composition specified in Example 3 is dried on a batch column with an efficiency of 20 plates in the presence of 25 g of cyclohexane. 65 g of aqueous PO azeotropes are distilled off (23.6% for the whole mixture). In the cube get dried software with a moisture content of 0.1%. The distillate is stratified into two layers: 24 g of the aqueous layer and 41 g of the oil layer. The composition of the oil layer, wt.%: Cyclohexane 61, water 3, the amount of PO 36. The composition of the aqueous layer, may.%: Water 96.95; cyclohexane 0.05; amount of software, 3.0. As you can see, in the presence of "0%

cyclohexane on a batch column, even without recycling the oil layer, is obtained in distillate. an oil layer containing o / 10 times less water and an aqueous layer containing l-5 times less PO than with a heteroazeotropic distillation in the absence of a peeler (see example 9 for comparison). Example 7. Drying

mixtures of pyridine bases with water having the composition specified in Example 3. 247 g of this mixture and 74 g of heptane are charged to the flask, and then dispersed on a batch column with an efficiency of 20 plates. 110 g of the mixture are distilled off into a distillate, which is exfoliated into two layers — a lower (aqueous) layer of 20.5 g and an upper (oil) layer.

89.5 g. The aqueous layer has the following composition, wt.%: Water 95.1, - PO 4.88; n-heptane 0.02. The oil layer has the following composition, wt.%: PO 14.2; water 3.30; heptane 82.5.

In the cube, dried pyridine bases with a water content of 0.2% remain (211 g).

Thus, drying in the presence of 30% heptane makes it possible to obtain

WATER LAYER, containing 3 times

less PO, and an oil layer containing 9 times less water than that obtained by distillation in the absence of n-heptane (see example 9 for comparison).

Example 8. To the products of the synthesis of 4-picoline, o-xylene was added with the calculation of its content in the initial mixture. 738 g of a mixture of the following composition are obtained, wt%: lightly boiling 0.12; formaldehyde 0.49; meganol 4.16; p-xylene 0,0015; m-xylene 0.1; o-xylene 10.95; 2-picoline 1.02; 2,6-lutidine 0.26; 4-picoline 53.59; 4-vinylpyridine 0; 69; water

28.5.

The mixture is dispersed on a batch column with an efficiency of 10 plates equipped with a sump for exfoliating distillate. A distillate is collected that stratifies into two layers — aqueous and oily. The oil layer is returned to the column in the form of reflux in the amount of 60 g / h. 277 g of a water layer and 84 g of an oil layer are obtained. 377 g of dried 4-picoline is left in the cube.

The composition of the aqueous layer of distillate, wt.%: Boiling 0.02, formaldehyde 1.25; methanol 10.55; p-xylene 0.004, m-xylene 0.14; o-xylene 0.34; 2-picoline 0.79; 4-picoline 13.27; water 73,636.

The composition of the oil layer, wt.%: Boiling 0.85; formaldehyde 0.17;

methanol 1.48; m-xylene 0.41, - o-xyLOL 73.29, 2-picoline 1.28; 2, b-lutidine 0.05; .4-picoline 20.92; 4-vinylpyridine 0.02, - water 1.53.

The composition of cubic liquid (commodity picoline), wt.%: Light boilers 0.04; methanol 0.08; m-xylene 0.01; o-xylene 4.85, 2-picoline 1.13; 2.6 lutidine 0.51; 4-picoline 91.68; 4-vinylpyridine 1.35; water 0.35.

It follows from the above data that in the presence of - 10% o-xylene, an oil layer can be obtained, which is returned to the column with 1.53% by weight of water in contrast to 30.63% of the prototype water.

Example 9 (for comparison). The oil fon synthesis layer was dried on a batch column with an efficiency of 20 plates.

391 g of an oil layer is loaded into a cube, having the following composition, wt%: water 7.8; NH 0.95; VPO 23.85 MEP 57.11; Z-EP-0.16; 2.3 + 2.5 lutidines, 0.07; 4-picolin-0.08; 2-picoline 1.49; paraldehyde 5.63.

20% of the loaded oil layer is distilled off into the distillate, i.e. 66 g

which is exfoliated into two layers, the upper (oily) layer and the lower (aqueous) layer. Get 39.3 g of the oil layer and 27 g of the aqueous layer, the composition of which, wt.%: Oil layer: water 30.63, - MEP 18.00, - 3-ethylpyridine 0.10f 2.3 + 2.5 -Lutidines 0.10; 4-picoline 3.17, 2-picoline 24.4b; paraldehyde 23,61, bottom layer: in. 63.33; ammonia 13.78; IEP 6.59; Z-EP-0.08; 2.3 + 2.5 lutidines, 0.08; 4-picoline 0.92; 2-picoline 9.13, paraldehyde 7.07.

In a cube, there are 324.7 g of dried pyridine bases of the following composition, wt%: water 0.95; VPO 29.20; IEP 66.10; 3-ethylpyridine 0.18, 2.3 + 2.5-lutidenes 0.15; 4-picoline 1.34; 2-picoline 3.07.

The proposed method of drying the oil layer improves the separation of the phases, reduces the content of pyridine bases in the water layer and the water content in the oil layer, and also reduces the energy consumption for

aushka.

Table 1

0.0710.56

1.3312.6

1.05.7

0.9910.24

0,809,2

0.196.5

0.448.5

0.2313.9

0.2711.0 0.127.0

94,564.50

92.48 9.47 5.7 10.34 11.50 34.2 19.38 60.5 40.74

56.4 0.048

Pyridine

2-picolin

4-picolin

2,3-lutidine

NEP

4-Vinylpyridine

Profit center

J

4-Methyl-3-ethylpyridine

Water

Claims (1)

1. Baseline data for the design of the integrated production of 2-methyl-5-vinylpyridine-2-picoline and corrosion inhibitors. Regulations, I Zslavl, NIIMSK, 1979 (prototype). Rets / g Sepxf / eso (/ frafff / ffftf / i / cffff g