RU2089536C1 - Method of preparing tert-butanol - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: present invention describes method of preparing tert-butanol from isobutylene-containing hydrocarbon mixtures by hydration in the presence of heterogeneous acid type catalysts at elevated temperatures and pressure in flow and reaction-extraction type reactors to produce alcohols by rectification. The claimed method comprises preliminarily contacting initial hydrocarbon mixture with water in prereactor, water is fed in amount of 1 to 25 % of total amount at water to isobutylene water ratio from 0.4 to 5.0 to recover the resulting tert-butanol as extract in stream of unreacted hydrocarbons. The resulting extract containing 15-20 % tert-butanol is directed to separate alcohol to residual content of 1-5 wt% by rectification. After separation of tert-butanol the extract is contacted with the remaining amount of water in counter-flow reaction-extraction reactor at water to isobutylene molar ratio from 25 to 150. Water containing 0.1-1.0 wt% tert-butanol is supplied to top portion of reaction-extraction reactor and water containing no tert-butanol is supplied to the portion located 5-15 trays higher. EFFECT: more efficient preparation method. 2 cl

Description

 The invention relates to the production of tert. butanol by hydration of isobutylene contained in hydrocarbon mixtures of various origin on acid type catalysts. The resulting tert. butanol can be used either as a commercial product or as a raw material for the production of monomers for synthetic rubbers.

A known method of producing alcohols by hydration on acid-type catalysts, in particular sulfonation, [1] where isoolefin-containing hydrocarbons and water are fed into a direct-flow reactor at a hydration temperature of 100 ^o C and a pressure of 30 ata.

 The method has the following disadvantages: tert. butanol is mainly excreted in the composition of an aqueous solution of tert. butanol, subsequent separation of tert. butanol from water requires significant energy consumption due to unfavorable phase equilibrium and the formation of an azeotrope; under the indicated conditions, the process proceeds with a low conversion of less than 60% and low selectivity; the oligomer yield of more than 10%; some of the hydrocarbons can evaporate, and vapors rising up make the operation of the reactor difficult.

 Known methods for producing tert. butanol in once-through reactors in the presence of an acid type catalyst, a polar solvent and an emulsifier [2,3] in order to homogenize the reaction mass.

 The use of additional products for the homogenization of the reaction mass complicates the process technology, leads to the formation of undesirable by-products and increases the cost of tert. butanol.

The closest in technical essence to the proposed invention is the method [4] where the hydrocarbons and water are supplied countercurrent to each other. The isobutylene-containing hydrocarbon mixture is supplied to the bottom of the reactor, and water is fed to the top of the reactor. The hydration temperature is 80-90 ^o C, the molar ratio of the source of isobutylene to water can vary from 1:80 to 1: 115. The main part of the tert. butanol is excreted in the aqueous solution and separated by distillation. The hydrocarbon stream taken from above the reactor contains not more than 0.5% tert. butanol and is purified from alcohol by distillation.

 The disadvantages of this method are: high metal consumption of the process and the complexity of the technological scheme, since it requires separation tert. butanol from both hydrocarbons and water; high energy intensity of the separation stage tert. butanol from water due to the presence of an azeotrope in a difficultly separated mixture of tert. butanol and water; high water content in tert. butanol 15 wt. due to the presence of an alcohol-water azeotrope and close boiling points of the components.

 The aim of the invention is to simplify the process technology, reducing the metal process and reducing energy consumption. In addition to the above in the proposed method receive tert butanol containing not more than 10 wt. water.

 A method for producing tert. butanol from isobutylene-containing hydrocarbon mixtures by hydration in the presence of heterogeneous acid-type catalysts at elevated temperature and pressure in reactors of flow and reaction-extraction type with the separation of alcohols by distillation, which consists in the fact that the initial hydrocarbon mixture is preliminarily contacted in the prereactor with water supplied in an amount of from 1 to 25% of the total amount with a molar ratio of water to isobutylene from 0.4 to 5.0 with the conclusion of the resulting tert. butanol as an extract in a stream of unreacted hydrocarbons. The resulting extract containing 15-50% tert. butanol, sent to the separation of alcohol to a residual content of 1-5 wt. by rectification, and after separation tert. butanol extract is contacted with the remaining amount of water in a countercurrent reaction-extraction reactor at a molar ratio of water to isobutylene from 25 to 150.

 Water can be introduced into the reaction-extraction reactor in two streams. One stream containing 0.1-1.0 wt. tert. butanol, sent to the upper part of the catalyst layer and another stream not containing tert. butanol, 5-15 plates above the catalyst layer.

 The supply of water in two streams is not a mandatory intake, but this is very important, since it allows the separation of tert. butanol from its aqueous solution, obtained in a countercurrent reaction-extraction reactor, with softer requirements for the residual alcohol content in water, in particular up to 1% tert. butanol. This, in turn, allows to reduce energy costs for one of the most energy-intensive process units. The amount of input water that does not contain tert. butanol, close to the amount required for the synthesis of tert. butanol in the process.

 Water containing tert. butanol, can be sent to the prereactor to replenish the water flow in the prereactor for the hydration of isobutylene.

 The technological scheme of one of the variants of the proposed method is presented in the drawing.

 The initial hydrocarbon mixture and water are fed into the flow prereactor 1. The prereactor can be of various types, in particular isothermal (tubular), adiabatic, etc.

 A water stream is taken from the upper part of the prereactor and passes through the anion exchange filter 2, where sulfuric acid is absorbed, and is collected in the tank 3. From the tank 3 by the pump 4, water is returned through the cooler 5 to the prereactor 1.

 Unreacted hydrocarbons are extracted with tert. butanol. The extract formed in the prereactor containing 15-50% tert. butanol is taken from above the prereactor and sent to the separation of alcohol from hydrocarbons in a distillation column 6, heated through a boiler 7.

 Unreacted hydrocarbons containing 1-5% tert are selected from the top of the column. butanol and sent to the condenser 8. Part of the condensate is returned to the column 6 as a reflux. The other part goes to get tert. butanol in a countercurrent reaction-extraction reactor 9 in the lower part (under the catalyst layer).

 In the upper part (above the catalyst layer and / or on the catalyst layer) of the reactor 9, water is supplied either from the bottom of the column 10 or fresh.

 Unreacted hydrocarbons are taken from above the reactor 9.

 The aqueous solution is tert. butanol, selected from the cube of the reaction-extraction reactor 9, is subjected to separation in a distillation column 10 per third. butanol and water. Column 10 is heated through a boiler 11. Tert. butanol containing 15 wt. water, is taken from the top of the column and condenses in the condenser 12. A part of the condensate is returned to the column 10 as a reflux. The other part is selected as the target product.

 From the cube of the column 10 is selected water, which may contain up to 1.0 wt. tert. butanol, and is sent to the hydration in the reactor 9.

 In the upper part of the reactor 9, tertiary free water may be supplied. butanol, and water containing 0.1-1.0 wt. tert. butanol. Part of the water containing up to 1.0% tert. butanol, may in this case be filed in the prereactor 6.

 Other process flow diagrams are possible.

Example 1. In the lower part of the prereactor made of X18H10T steel with a diameter of 32 mm, a height of 6000 mm, filled with KU-2FPP catalyst in an amount of 4.2 L and water as a continuous phase, a 4000 ml / h fraction of C ₄ hydrocarbons containing 50 wt. isobutylene.

The amount of fresh water was 170 ml / h. The molar ratio of water to isobutylene was 0.4: 1. The temperature in the prereactor 90 ^o C, pressure 20 ata. In the upper part of the prereactor, tert. butanol with unreacted hydrocarbons. Received tert. butanol in the form of an extract in a stream of unreacted hydrocarbons was removed from the top of the prereactor.

 The amount of the selected stream was 4160 ml / h, composition, wt.

Hydrocarbons C ₄ 42
Isobutylene 37.4
Tret. butanol 18.7
Water 1.9
Tret. butanol isolated from the above stream by distillation in the amount of 630 ml / h, contained 7.5 wt. water.

Rectification column operation mode:
Reflux value 0.5-1.0
Top pressure 5.0 ata
Top temperature 40-50 ^o C
The temperature of the cube 135-140 ^o C
The fraction of hydrocarbons C ₄ after separation tert. butanol to a residual content of 1% in the amount of 3460 ml / h was sent to the lower part of the countercurrent reaction-extraction apparatus with a diameter of 32 mm The height of the catalyst layer is 6 m. The volume of the catalyst is 4.2 l.

The pressure in the reactor is 20 kg / cm ² , the temperature is 90-95 ^o C.

Water was supplied to the top of the extractor in an amount of 17450 ml / h. The molar ratio of water to isobutylene is 50: 1. From the upper part of the extractor, a C ₄ fraction containing 0.9% isobutylene and 0.1 wt. tert. butanol in an amount of 1940 ml / h.

 From the bottom of the reactor, water containing less than 0.03 wt. hydrocarbons and 6% tert. butanol in an amount of 19100 ml / h.

 Tert. Was isolated from said water. butanol containing 4.0% hydrocarbons and 14.4 wt. water, in an amount of 1670 ml / h by distillation in a column with a diameter of 20 mm

The operation of the rectification column: reflux ratio 1, pressure 1.1 ata, top temperature 80 ^o C, cube temperature 100 ^o C.

 Water taken from the bottom of the rectification column containing 0.1% tert-butanol was returned to the reaction-extraction reactor. At the same time, 270 ml / h of tert-free water was fed into the prereactor. butanol.

 The amount of water supplied to the prereactor is 1% of the total amount supplied to the synthesis of tert. butanol water.

Example 2. In the lower part of the prereactor made of X18H10T steel with a diameter of 32 mm and a height of 6000 mm, filled with KU-2FPP catalyst in an amount of 4.2 L and water as a continuous phase, a C ₄ hydrocarbon fraction in an amount of 4000 ml / h was fed, containing 55 wt. isobutylene, fresh water in an amount of 410 ml / h and a recycle water layer in an amount of 1900 ml / h, taken from the top of the reactor. The molar ratio of water fed to the prereactor to isobutylene fed with a C ₄ hydrocarbon fraction was 5: 1. The temperature in the prereactor 85-90 ^o C, pressure 17 ata. At the top of the reactor, tert. butanol with unreacted hydrocarbons, and the resulting tert. butanol in the form of an extract in a stream of unreacted hydrocarbons is discharged from above the prereactor.

 The amount of the selected stream was 4100 ml / h, composition, wt.

Hydrocarbons C ₄ 38.5
Isobutylene 14.1
Tret. butanol 43.5
Water 3.9
From the upper part of the prereactor below the output of the hydrocarbon extract, a stream containing up to 10% t. butanol, in an amount of 1900 ml / h, which is cooled at 17 ^o C and return down the prereactor.

 The conversion of isobutylene is 70% Tert. butanol isolated from the spent fraction by distillation in an amount of 1630 ml / h, contained 8.2 wt. water.

The fraction of hydrocarbons C ₄ after separation tert. butanol to a residual content of 5% and containing 23% isobutylene in an amount of 2600 ml / h was sent to the lower part of the counter-current reaction-extraction reactor, 32 mm in diameter. The height of the catalyst layer was 6 m. The volume of the catalyst was 4.2 l.

The operating mode of the reactor: pressure 20 kg / cm ² , temperature 90-95 ^o C.

 Water was supplied to the top of the reactor in an amount of 8066 ml / h.

 The molar ratio of water to isobutylene is 65: 1.

From the top of the extractor, a C ₄ fraction containing 0.5% isobutylene and 0.1 wt. tert. butanol in an amount of 2008 ml / h.

 Water containing 0.02 wt.% Was taken from the bottom of the reactor. hydrocarbons and 6% tert. butanol in the amount of 8563 ml / h.

 In the distillation column under the conditions set forth in example 1, was allocated 618 ml / h tert. butanol containing 15 wt. water.

 Water with a residual content of tert. butanol less than 0.1 wt. returned to the reaction-extraction reactor in an amount of 7943 ml / h

 123 ml / h of tertiary-free water was supplied to the top of the reaction-extraction reactor. butanol.

 Water was supplied to the prereactor in an amount of 25% of the total amount of water directed to the synthesis of tert. butanol.

 Example 3. Under the conditions described in example 2, the hydrocarbon fraction was fed into a countercurrent reaction-extraction apparatus having an additional plate section above the catalyst layer. The section has 5 strainers. Water was introduced in two streams. Water containing 0.1% tert was added to the upper part of the catalyst layer. butanol in an amount of 7950 ml / h. 605 ml / h of fresh water was introduced into the upper part of the dish section.

 A hydrocarbon fraction containing 0.5% isobutylene in an amount of 2006 ml / h was taken from the upper part of the reaction-extraction reactor.

Water containing 5.2% tert was taken from a cube of a reaction-extraction reactor. butanol in an amount of 8910 ml / h. From an aqueous solution tert. butanol by distillation was isolated tert. butanol. The rectification column mode, having a diameter of 20 mm and a nozzle height (nichrome rings of 2 x 2 mm in size) 0.5 m: pressure 1.1 ata, temperature, ^o C top 80, 100 cubic meters, reflux value 1.0.

 A tert was selected on top of the column. butanol containing 15 wt. water in an amount of 665 ml / h.

 Water containing up to 0.1% tert was taken from the bottom of the rectification column. butanol in the amount of 8360 ml / h.

 Part of the water in the amount of 7950 ml / h was fed into the upper part of the catalyst layer of the reaction-extraction reactor. Part of the water in an amount of 410 ml / h was sent to the prereactor.

 The molar ratio of water to isobutylene in the reaction-extraction reactor was 73: 1.

 The amount of water supplied to the prereactor was 20% of the total amount of water supplied to the hydration.

 Example 4. Under the conditions set forth in example 1, water containing about 0.1% tert was introduced into the catalyst layer into the reaction-extraction reactor. butanol, in the amount of 6585 ml / h. The reaction-extraction reactor included an additional plate section above the catalyst layer having 15 sieve plates, to which fresh water was supplied in an amount of 170 ml / h. A 2010 ml / h hydrocarbon mixture containing 0.5% isobutylene was taken from the top of the reactor.

 8145 ml / h of water containing 14.1% tert was withdrawn from the bottom of the reactor. butanol, from which 1650 ml / hr of tert. butanol containing 15% water and 6510 ml / h of water containing 0.1% tert. butanol. Part of the water in an amount of 170 ml / h was fed into the prereactor.

 The molar ratio of water to isobutylene in the reaction-extraction reactor was 25: 1.

 The amount of water supplied to the prereactor is 2.5% of the total amount of water.

 Example 5. Under the conditions described in example 2, 17000 ml / h of water was supplied to the reaction-extraction reactor.

 On top of the reactor, 2008 ml / h of a hydrocarbon fraction containing 0.5% isobutylene and 0.1% tert was taken. butanol.

17510 ml / h of water containing 3.0% tert-butanol was withdrawn from the bottom of the reactor, from which 665 ml / h of tert was isolated. butanol containing 15 wt. water, by distillation. The amount of water after separation tert. butanol was 17000 ml / h. The content of tert-butanol in the water was less than 0.1 wt.%
The molar ratio of water to isobutylene was 150: 1.

 The amount of water supplied to the pre-reactor is 11% of the total amount of water supplied to the hydration.

Claims (2)

 1. The method of producing tert-butanol from isobutylene-containing hydrocarbon mixtures by hydration in the presence of heterogeneous acid-type catalysts at elevated temperature and pressure in flow and reaction-type extraction reactors with the separation of tert-butanol by distillation, characterized in that the initial hydrocarbon mixture is preliminarily contacted in prereactor with water supplied in an amount of from 1 to 25 wt. of the total amount, with a molar ratio of water to isobutylene from 0.4 to 5.0 with the conclusion of the resulting tert-butanol in the form of an extract in a stream of unreacted hydrocarbons, the extract is sent to the separation of tert-butanol with 15 to 50 wt. up to 1 5% and then subjected to contact with the rest of the water in a countercurrent reaction-extraction reactor at a molar ratio of water to isobutylene from 25 to 150.  2. The method according to claim 1, characterized in that in the upper part of the catalyst layer countercurrent reaction-extraction reactor serves water containing 0.1 to 1.0 wt. tert-butanol, and 5 to 15 plates above water that does not contain tert-butanol.