RU2462447C1 - Method of producing tertiary butyl alcohol - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: tertiary butyl alcohol is used as a semi-product in organic synthesis, particularly for producing isobutylene and isoprene, which are used in production of butyl rubber and isoprene rubber. The method involves liquid-phase hydration of isobutylene or isobutylene-containing hydrocarbon mixture with water at high temperature in the presence of tertiary butyl alcohol as a solvent with forward feeding of the stream of initial reactants into a shelf-type column reactor filled with several layers of a sulphocationite catalyst, with subsequent extraction of the end product from the obtained reaction mixture by fractionation. The reactor is filled with five catalyst layers, wherein the amount of catalyst increases from layer to layer in the direction of feeding the stream of material, characterised by that the catalyst is in the layers in the following ratio, as a percentage of the total volume of the catalyst: in the first layer 5-7; in the second layer 8-10; in the third layer 12-15; in the fourth layer 20-24; in the fifth layer 43-56.

EFFECT: method increases conversion of isobutylene and increases selectivity on the end product.

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Description

The invention relates to the field of petrochemistry, and more specifically to methods for producing tertiary butyl alcohol (TBS), which is used as an intermediate in organic synthesis, in particular for the production of isobutylene and isoprene, used in the production of butyl rubber and isoprene rubber.

A known method of producing TBS by the liquid-phase reaction of isobutylene in the form of an isobutylene-containing hydrocarbon fraction with water at a temperature of 80-90 ° C with a countercurrent flow of feeds of the initial reagents into a column reactor filled with a sulfocationite catalyst. Water and the isobutylene-containing fraction is supplied at a volume ratio of (7-10): 1, which corresponds to a molar ratio of water: isobutylene (80-110): 1. The resulting TBS is removed from the reactor as part of two reaction streams, which are a dilute solution of TBS in hydrocarbons and a dilute solution of TBS in water. The performance of the process is 100 g of isobutylene per 1 liter of catalyst per hour. From the obtained TBS solutions are isolated by distillation [S.Yu. Pavlov. Isolation and purification of monomers for synthetic rubber. L., "Chemistry", 1987, p.133-136].

The disadvantage of this method is the low rate of hydration reaction due to the mutual insolubility of the starting reagents, as well as the complexity of the technology and increased energy costs associated with the allocation of TBS from two diluted solutions.

A known method for producing TBS by the liquid-phase reaction of isobutylene in the form of an isobutylene-containing hydrocarbon fraction with water at a temperature of 70-110 ° C with a direct-flow feed of the feed of the reactants into a vertical reactor filled with a sulfocationite catalyst. Water and isobutylene are supplied at a molar ratio of (5-20): 1. To increase the mutual solubility of the reagents, the hydration reaction is carried out in the presence of a homogenizer - a polar solvent of ethyl cellosolve in an amount of 10-70% wt. to water and a nonionic emulsifier. The productivity of the isobutylene process is 150-170 g / l · h. TBS is isolated by distillation from the obtained reaction mixture [SU 512622, 01/30/1983].

The disadvantage of this method is the formation of undesirable by-products from the solvent with the participation of TBS, the complexity of the technology and the increased energy costs associated with the allocation of TBS from a dilute mixture with water and ethyl cellosolve.

Closest to the claimed is a known method for producing TBS by a liquid-phase reaction of isobutylene or an isobutylene-containing hydrocarbon mixture with water at a temperature of 30-110 ° C, preferably 50-90 ° C, with a direct-flow feed of the starting reagents into a reactor filled with a sulfocationic catalyst. Preferably, 2-5 series reactors are used. Reactors with a fixed catalyst bed are used with uniform loading of the amount of catalyst in each reactor / bed. To increase the mutual solubility of the reactants, the hydration reaction is carried out in the presence of TBS as a solvent in an amount of 21.6-78% wt. in the reaction zone. The conversion of isobutylene reaches 55%. From the obtained reaction mixture TBS is isolated by distillation [US 4307257, 12/22/1981 - prototype].

The disadvantage of this method is the conversion of about 1% of isobutylene into by-products - isobutylene dimers and oligomers, which complicate the isolation of TBS and impair its quality. Another disadvantage is the insufficient conversion of isobutylene, which increases the production costs for the allocation of unreacted isobutylene.

The objective of the proposed method is to increase the conversion of isobutylene and increase the selectivity for trimethylcarbinol and, as a result, increase the technical and economic indicators of the process.

This problem is solved by the method of producing tertiary butyl alcohol by the reaction of liquid-phase hydration of isobutylene or an isobutylene-containing hydrocarbon mixture with water at elevated temperature in the presence of TBS as a solvent with a direct-flow feed of the starting reagents into a shelf-type column reactor filled with sulfocathionite catalyst, followed by isolation of TBS from the resulting TBS the reaction mixture by distillation, and the reactor is filled with five layers of catalyst, the amount of which increased Chiva from layer to layer in the direction of feed stream flow. The catalyst layers are located in the following ratio,% of the total catalyst volume:

in the first layer 5-7; in the second layer 8-10; in third 12-15; in the fourth layer 20-24; in the fifth layer 43-56.

As isobutylene feedstock, concentrated isobutylene containing 90.0-99.9% of isobutylene or isobutylene-containing hydrocarbon fractions with different isobutylene contents, in particular industrial butylene-isobutylene and isobutane-isobutylene fractions containing 10-60% isobutylene, are used.

The catalyst used is cation exchange resins in the H-form, in particular cation exchangers based on sulfonated copolymers of styrene and divinylbenzene.

Macroporous sulfocathionites, in particular KU-23, Duolite C26, Amberlyst 15, Lewatit K2629, Dowex 50, Purolite CT275, are preferably used.

The process is carried out using a column-type column reactor filled with a catalyst. The reactor contains five catalyst beds, with the amount of catalyst increasing from layer to layer in the feed direction. The proportion of catalyst located on the last fifth layer is approximately fifty percent of the total volume of the loaded catalyst in all five layers.

The streams of the starting reagents are fed directly into the reactor. To control the temperature in the reactor, it is possible to cool the reaction stream between the catalyst layers in external heat exchangers.

The hydration reaction is preferably carried out at a temperature of 50-100 ° C and a pressure of 13-25 atm, sufficient to maintain the products of the reaction mixture in the liquid phase.

Water and isobutylene are fed into the reactor, preferably at a molar ratio of (1-4): 1. The flow of water for the reaction can be carried out on one or separately on several layers of catalyst.

The reaction is carried out preferably at a content of 20-60% wt. TBS as a solvent in the reaction zone. The indicated content of TBS can be provided by recycling part of the obtained TBS and / or recycling part of the reaction mixture containing TBS coming out of the reactor to the reactor inlet, as well as feeding TBS obtained in another process to the reactor. The TBS can be recycled to the reactor as part of a water stream for the reaction and / or a stream of isobutylene feed.

An essential distinguishing feature of the proposed method is the location of the catalyst in five layers, and the catalyst content increases from layer to layer, with the following ratio of the amount of catalyst in the layers,% of the total catalyst volume:

in the first layer 5-7; in the second layer 8-10; in third 12-15; in the fourth layer 20-24; in the fifth layer 43-56.

The above distribution of the amount of catalyst allows to increase the conversion of isobutylene, solving the problem of reducing the rate of hydration reaction as it reaches equilibrium. Therefore, an increase in the quantitative content of the catalyst from layer to layer in the direction of supply of the reactants leads to an increase in the conversion of isobutylene and the selectivity of the process. Moreover, the described distribution of the catalyst content, increasing the speed of the chemical reaction, allows to reduce the loss of isobutylene in the subsequent stage of isobutane dehydrogenation, if the isobutane-isobutylene fraction is introduced as a raw material.

The proposed method for producing tertiary butyl alcohol allows to increase the conversion of isobutylene to 85-95%, and to reduce the conversion of isobutylene into by-products - isobutylene dimers and oligomers - up to 0.3%.

The industrial applicability of the proposed method is confirmed by the following examples.

Example 1

In a reactor, which is a vertical metal pipe made of 12X18H10T steel with an internal diameter of 12 mm and a length of 1400 mm, 100 ml of Purolite CT275 sulfation-cation catalyst are loaded (particle size 0.5-1.0 mm, static exchange capacity 5.2 mEq H ⁺ per 1 g of dry catalyst). The catalyst has five layers with the following distribution between them: the first layer is 6 ml, the second layer is 9 ml, the third is 14 ml, the fourth is 22 ml, and the fifth is 49 ml.

A hydrocarbon mixture containing 45.0% isobutylene (the rest isobutane, n-butane and n-butenes up to 100) is fed to the top of the reactor as isobutylene feedstock at a rate of 48.60 g / h. Together with isobutylene feed water is supplied at a rate of 7.76 g / h and a recycle stream containing 91.33% wt. TBS, 8.51% water and 0.16% isobutylene dimers, at a rate of 63.18 g / h.

In the reactor, the temperature is 64-75 ° C, the pressure is 14-15 atm.

From the bottom of the reactor, the reaction mixture is withdrawn at a rate of 119.54 g / h and fed to a distillation column to isolate TBS. Unconverted hydrocarbons are distilled off at the top of the column at a rate of 31.10 g / h. The content of isobutylene in the distillate is 14.05% wt.

Distillation column bottoms in an amount of 88.44 g / h contains 91.33% wt. TBS, 8.51% water and 0.16% isobutylene dimers. A portion of this bottoms liquid in an amount of 63.18 g / h is returned to the reactor. The remainder in the amount of 25.26 g / h is removed from the process and then used, in particular, as a raw material for the production of isoprene.

The conversion of isobutylene in the process is 80.0%, the yield of isobutylene dimers is 0.18%.

Example 2

The process is carried out analogously to example 1, however, the catalyst brand Purolite CT275 have five layers with the following distribution between them: the first layer of 7 ml, the second layer of 10 ml, the third 15 ml, fourth 20 ml, fifth 52 ml.

In the reactor, the temperature is 68-78 ° C, the pressure is 15-16 atm.

The conversion of isobutylene in the process is 83.5%, the yield of isobutylene dimers is 0.20%.

Example 3

The process is carried out analogously to example 1, however, a Lewatit K2629 brand catalyst is used (particle size 0.31-1.25 mm, static exchange capacity 4.7 mEq H ⁺ per 1 g of dry catalyst) and the catalyst is placed in five layers with the following distribution between them: the first layer of 5 ml, the second layer of 8 ml, the third 12 ml, the fourth 20 ml, the fifth 55 ml.

In the reactor, the temperature is 66-78 ° C, the pressure is 15-16 atm.

The conversion of isobutylene in the process is 85.0%, the yield of isobutylene dimers is 0.23%.

Example 4

The process is carried out analogously to example 1, however, concentrated isobutylene with a basic substance content of 98% at a rate of 71.50 g / h is used as raw material. Together with isobutylene, water is supplied at a speed of 26.45 g / h and a recycle stream containing 93.05% wt. TBS, 6.81% water and 0.14% isobutylene dimers, at a rate of 50.05 g / h.

In the reactor, the temperature is 63-73 ° C, pressure 13-15 atm.

The conversion of isobutylene in the process is 95.0%, the yield of isobutylene dimers is 0.15%.

Claims (1)

A method of producing tertiary butyl alcohol by liquid-phase hydration of isobutylene or an isobutylene-containing hydrocarbon mixture with water at elevated temperature in the presence of tertiary butyl alcohol as a solvent with a direct-flow feed of the starting reagents into a shelf-type column reactor filled with several layers of sulfation-cation catalyst, followed by isolation from rectification of the target product the resulting reaction mixture, while the reactor is filled with five layers of catalyst, in which the amount of catalyst is increased from layer to layer in the direction of flow of the feed stream, characterized in that the catalyst is arranged in layers in the following ratio,% of the total catalyst volume:
in the first layer 5-7;
in the second layer 8-10;
in the third 12-15;
in the fourth layer 20-24;
in the fifth layer 43-56.