RU2086527C1 - Method for production of tertiary butanol - Google Patents

Abstract

FIELD: production of tert-butanol by hydration of isobutylene with the help of catalyst of acid type. SUBSTANCE: method involves production of tert-butanol by contacting of isobutylene-containing hydrocarbon mixtures with water. The process is carried out in the presence of catalyst of acid type and it is followed by rectification of mixture. Origin hydrocarbon mixture and water are fed into reactor, molar ratio of water is 0.4-5.0 moles per 1 mole of isobutylene. Tert-butanol is fed for rectification as its extract in the stream of hydrocarbons being unreacted. EFFECT: improved efficiency. 3 cl

Description

 The invention relates to the field of producing tert-butanol by hydration of isobutylene contained in hydrocarbon mixtures 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 isobutylene, an important monomer for the production of synthetic rubbers.

There is a method of producing alcohol by hydration on acid-type catalysts, in particular, sulfocationite [1] where isoolefin-containing hydrocarbons and water are fed to the top of the direct-flow reactor. The hydration temperature is 100 ^o C and a pressure of 30 ata.

 The method has the following disadvantages: tretret. 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 these conditions, the process proceeds with a low conversion of less than 60% and low selectivity; the yield of oligomers is more than 10%. Some hydrocarbons can evaporate and vapors, rising upward, impede the operation of the reactor.

 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 an increase in 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 supply of the isobutylene-containing hydrocarbon mixture is carried out in the lower part, and water in the upper part of the reactor. The hydration temperature is 80-90 ^o C, the molar ratio of the source isoolefin hydrocarbon to the source water is less than 50. The main part of tert.butanol is removed in the composition of the aqueous solution and separated by distillation. The hydrocarbon stream, taken at the top of the reactor, contains not more than 0.5% tert.butanol and is purified from alcohol by rectification.

The disadvantages of this method are:
high metal consumption of the process and the complexity of the technological scheme, since it is necessary to separate tert.butanol from both hydrocarbons and water;
high energy intensity of the stage of separation of 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 more than 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 from 1 to 10% water, i.e. significantly less than in the method [4]
We propose a method for producing tert-butanol from isobutylene-containing hydrocarbon mixtures by contacting them with water in the presence of an acid catalyst, followed by rectification of the mixture removed from the reactor, the initial hydrocarbon mixture and water being supplied to the reactor in a molar ratio of 0.4 to 5.0 mol of water per 1 mol of isobutylene and the output of the resulting tert. rectification of butanol is carried out as an extract in a stream of unreacted hydrocarbons.

 The proposed method is carried out in the reactor in the presence of hydrocarbon and aqueous phases, and the phase separation can be organized in the upper part of the reactor or in the lower part of the reactor, or in a separate apparatus, taken out of the reactor. The hydrocarbon mixture in the phase separation at the top of the reactor is fed to the lower part, and during the phase separation at the bottom of the reactor to the upper part. The tert-butanol extract in the hydrocarbon stream is taken from the reactor zone in which the phase separation is organized. Source water, regardless of the location of the phase separation can be supplied anywhere in the reactor.

The most preferred method is the supply of the original C ₄ fraction and the source water to the lower part of the once-through reactor, while the tert-butanol hydrocarbon extract is discharged from the top of the reactor.

In one embodiment of the proposed method, a stream is withdrawn from the reactor, containing mainly water, which is cooled at 10-50 ^° C. and returned to the part of the reactor opposite to the part from which it is withdrawn.

The need to use the indicated recycle water supply arises when processing C ₄ fractions rich in isobutylene, and is associated, in particular, with the problem of efficient removal of reaction heat.

 The reaction system (reactor) can be made either in the form of a single apparatus, or in the form of a “split apparatus”, which is a combination of two or more apparatuses connected by flows in such a way that the liquid flow from the upper (lower) part of each of them is fed down (up) of the subsequent apparatus.

 The proposed method allows to simplify the technological scheme, since tert.butanol is easily separated from unreacted hydrocarbons and the energy-intensive and metal-intensive stage of separation of tert.butanol from water is excluded. Metal consumption is also reduced by reducing the size of the reactor, due to the lower molar ratio of hydrocarbons and water. Allocated tert. butanol usually contains from 7 to 10 wt. water and, if desired, in a column for separating tert.butanol from hydrocarbons, tert.butanol containing from 1 wt. water, as water is removed along with hydrocarbons on top of the column.

Example 1. In the lower part of the reactor, made of steel grade X18H10T, 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 an aqueous solution of tert-butanol containing 5 wt. tert.butanol, served in an amount of 4000 ml / h fraction of hydrocarbons C ₄ containing 50 wt. isobutylene. 170 ml / h of water are supplied to the top of the reactor. The molar ratio of feed water to feed isobutylene is 0.4: 1. The temperature in the reactor is 100 ^o C, pressure 20 ata. From the upper part of the reactor, the resulting tert-butanol is withdrawn in the form of an extract in a stream of unreacted hydrocarbons.

The amount of the selected stream was 4160 ml / h, composition, wt.):
Hydrocarbons C ₄ 42
Isobutylene 37.4
Tert.butanol 18.7
Water 1.9
The conversion of isobutylene was 27% Tert.butanol, isolated from the stream of unreacted hydrocarbons by distillation in the amount of 630 ml / h, contained 7.5 wt.% Water as an impurity.

Example 2. In the lower part of the reactor, made of steel X18H10T, 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 an aqueous solution of tert-butanol containing 8 wt. tert.butanol, served in an amount of 4000 ml / h fraction of hydrocarbons C ₄ containing 55 wt. isobutylene, 410 ml / h of fresh water and 1900 ml / h of a recycle water layer taken from the top of the reactor. The molar ratio of the total water fed to the bottom of the reactor to isobutylene fed with a C ₄ hydrocarbon fraction is 5: 1. The temperature in the reactor is 85-90 ^o C, pressure 17 ata. In the upper part of the reactor, the resulting tert-butanol is withdrawn as an extract in a stream of unreacted hydrocarbons.

The amount of the selected stream was 4100 ml / h, composition, wt.):
Hydrocarbons C ₄ 38.5
Isobutylene 14.1
Water 3.9
Tert.butanol 43.5
From the upper part of the reactor, below the outlet of the hydrocarbon extract, a stream containing predominantly water in an amount of 1900 ml / h is removed, which is cooled at 17 ^° C and returned to the bottom of the reactor.

 The conversion of isobutylene was 17% Tert.butanol, isolated from the stream of unreacted hydrocarbons by distillation in an amount of 1630 ml / h, contained 8.2 wt.% Water as an impurity.

Example 3. In the lower part of the reactor, made of steel X18H10T, 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 an aqueous solution of tert-butanol containing 10 wt. tert.butanol, served in an amount of 4000 ml / h fraction of hydrocarbons C ₄ containing 55 wt. isobutylene, 400 ml / h of fresh water and 1720 ml / h of a recycle water layer taken from the top of the reactor.

The molar ratio of the total water supplied to the bottom of the reactor to isobutylene supplied with a C ₄ fraction is 5: 1. The temperature in the reactor is 70 ^o C, pressure 15 ata.

 From the upper part of the reactor, the resulting tert-butanol is withdrawn in the form of an extract in a stream of unreacted hydrocarbons. The amount of the selected stream was 3870 ml / h, composition, wt.

Hydrocarbons C ₄ 41.0
Isobutylene 15.1
Tert.butanol 40.0
Water 3.9
Isobutylene conversion was 70%
The flow of unreacted hydrocarbons with tert-butanol is directed to the allocation of tert-butanol by azeotropic distillation.

 On top of the reactor below the outlet of the hydrocarbon extract, the recycle aqueous stream in the amount indicated above is withdrawn, which is returned to the reactor.

 The azeotropic distillation column operates at a reflux number of 1. From the top of the azeotropic distillation column, 28 ml / h of the aqueous layer, which is returned to the tert-butanol synthesis reactor as part of fresh water, and a hydrocarbon layer, which is 3,000 ml / h, are removed after separation. the azeotropic distillation columns are returned to food and 2456 ml / h are taken as a by-product.

 From the cube of the azeotropic distillation column, tert.butanol containing 6.5 wt. water.

Example 4. In the lower part of the reactor, made of steel X18H10T, 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 an aqueous solution of tert-butanol containing 10 wt. tert.butanol, served in an amount of 4000 ml / h fraction of hydrocarbons C ₄ containing 55 wt. isobutylene, 379 ml / h of fresh water and 534 ml / h of recycle water layer taken from the top of the reactor.

The molar ratio of the total water fed to the bottom of the reactor to isobutylene fed with a C ₄ hydrocarbon fraction is 2: 1. The temperature in the reactor is 85 ^o C, pressure 17 ata.

 From the upper part of the reactor, the resulting tert-butanol is withdrawn in the form of an extract in a stream of unreacted hydrocarbons. The amount of the selected stream was 4092 ml / h, composition, wt.

Hydrocarbons C ₄ 38.9
Isobutylene 16.6
Tert.butanol 40.8
Water 3.7
Isobutylene conversion was 65%
Unreacted hydrocarbons are separated from tert.butanol by distillation, while 1510 ml / h of tert.butanol containing 7.4 wt.

 On top of the reactor below the outlet of the hydrocarbon extract, the recycle aqueous stream in the amount indicated above is withdrawn, which is returned to the reactor.

Example 5. In the upper part of the reactor, made of steel X18H10T, with a diameter of 32 mm and a height of 6000 mm, filled with KU-2FPP catalyst in an amount of 3.2 l and a mass transfer nozzle made in the form of a trihedral helix of nichrome wire with a face length of 2 mm and a spiral height of 3-5 mm, taken in an amount of 1 liter and arranged uniformly in three layers along the height of the reactor, feeds a fraction of C ₄ hydrocarbons containing 55 wt. isobutylene, 960 ml / h of fresh water and 1726 ml / h of a recycle water layer, taken from the remote settling zone.

The molar ratio of the total water fed to the reactor to isobutylene fed with a C ₄ hydrocarbon fraction is 2: 1. The temperature in the reactor is 85 ^o C, pressure 17 ata.

 From the bottom of the reactor carry out the withdrawal of the reaction mass in the remote settling zone. From the upper part of the remote slop zone, the resulting tert is withdrawn. butanol as an extract in a stream of unreacted hydrocarbons. The number of selected stream amounted to 12179 ml / h, composition, wt.

Hydrocarbons C ₄ 39.7
isobutylene 21.8
Tert.butanol 35.3
Water 3.2
Isobutylene conversion was 55%
Unreacted hydrocarbons are separated from tert.butanol by distillation, and 3782 ml / h of tert.butanol containing 7.2 wt% water as an impurity are released.

 Recycled water stream in the amount indicated above containing 9.2 wt. tert.butanol, which is returned to the reactor.

Claims (3)

 1. The method of producing tert-butanol from isobutylene-containing hydrocarbon mixtures by contacting them with water in the presence of an acid catalyst, followed by rectification of the mixture removed from the reactor, characterized in that the initial hydrocarbon mixture and water are fed into the reactor at a molar ratio of water to isobutylene from 0.4 up to 5.0 and the output of the resulting tert.butanol for distillation is carried out as an extract in a stream of unreacted hydrocarbons.  2. The method according to claim 1, characterized in that the initial hydrocarbon mixture and water are fed into the lower part of the once-through reactor and the hydrocarbon extract of tert-butanol is discharged from above the reactor. 3. The method according to claims 1 and 2, characterized in that a stream containing predominantly water is removed from the reactor, which is cooled at 10 50 ^{° C.} and returned to the part of the reactor opposite to the part from which it is withdrawn.