RU2355712C1 - Method of butyl rubber obtainment - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention concerns butyl rubber obtainment. Butyl rubber is obtained by copolymerisation of isoprene with isobutylene in the presence of catalyst in chloromethyl medium, with isobutylene extracted by fractionator distillate of trimethylcarbinol dehydration. Further catalyst is deactivated, rubber is degassed, return products are fractioned in separation tower for isobutylene-chloromethyl and isobutylene-isoprene fractions, with further extraction of chloromethyl from isobutylene-chloromethyl fraction and division of isobutylene-isoprene fraction into isobutylene and isoprene-containing fraction. Bottom product of fractionator for trimethylcarbinol product dehydration is fed to additional fractionator. Additional fractionator distillate is fed to fractionator for trimethylcarbinol dehydration products. Bottom product of additional fractionator is fed to isobutylene-isoprene fraction division.

EFFECT: reduced quantity of oxygen-containing admixtures and isobutylene loss, stabilised copolymerisation process, prolonged polymerisation reactor run, increased butyl rubber output.

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Description

The invention relates to a technology for the production of butyl rubber, used for the production of automobile cameras, rubber products, halobutyl rubber, and can be used in the petrochemical industry.

A known method of producing butyl rubber by copolymerization of isobutylene with isoprene in chloromethyl medium in the presence of a Friedel-Crafts catalyst, followed by distillation of the solvent and non-polymerized monomers by aqueous degassing, their compression, condensation, drying and rectification of return products, including the preparation of isomethylene isopropylene and copolymerization , averaging a suspension of butyl rubber, concentration of rubber crumbs and drying in drying machines [Synthetic rubber. / Ed. Garmonova I.V. - L .: Chemistry, 1983, p. 293-300].

The disadvantages of this method of producing butyl rubber are the insufficient purity of isobutylene monomer, high costs of the catalytic complex, low mileage of polymerization reactors, difficulties in controlling the molecular parameters of rubber.

A known method for producing butyl rubber, including the production of isobutylene by hydration to trimethylcarbinol (TMK) and the dehydration of TMK to isobutylene, the preparation of a mixture of isobutylene and isoprene in chloromethyl, the copolymerization of isobutylene and isoprene in chloromethyl in the presence of a Friedel-Crafucomolase and degenezumers cumeflumerization catalyst, degeneration, carafucamazes and degenerates chloromethyl by condensation, compression, drying and rectification, isolation, drying of rubber. In this case, isobutylene with other decomposition products of trimethylcarbinol obtained by dehydration of trimethylcarbinol to isobutylene, or a mixture of it with isobutylene that is formed during the processing of non-polymerized monomers during rectification, is first washed with water from carbonyl and nitrogen-containing soluble impurities, and then separated azeotropic drying is treated with dry alkali at a volumetric feed rate of liquid isobutylene of 2.5-10 h ^-1 and a temperature of 35-65 ° C and served on pr the preparation of the charge [RF Patent No. 2155194, IPC C08F 210/12, publ. 08.27.2000].

The main disadvantage of this method is the high consumption of energy in the processing of the cube of the isobutylene rectification column through the hydration and dehydration stages and the high consumption of isobutylene monomer per ton of polymer.

The closest in technical essence to the claimed method is a method for producing butyl rubber by copolymerization of isobutylene with isoprene, including the production of isobutylene by hydration of isobutylene contained in the initial isobutylene-containing fractions in TMK, and the dehydration of TMK into isobutylene with its subsequent isolation from the products of the dehydration and hydration of ТМ for the preparation of a mixture of isobutylene, isoprene and chloromethyl, for the copolymerization of isobutylene with isoprene in the presence of catal congestion, rubber degassing, processing of non-polymerized monomers and chloromethyl diluent by condensation, compression, drying and rectification, isolation and drying of rubber, the distillation distillation residue of isobutylene extracted from TMC dehydration products being subjected to fractionated isobutylene-containing rectification rectification, washing from nitrogen-containing compounds and hydration of isobutylene, and bottoms containing butenes, TMC, hydrate by-products ii isobutylene and dehydration TMK carbonyl compound is fed together with the spent hydrocarbon fraction of C ₄ derived from the hydration of isobutylene to distillation, distilled unsaturated C ₄ hydrocarbons, then the remaining product is fed to further processing by distillation of a dedicated distillate is subjected to distillation together with the original isobutylene-containing fractions, and bottoms — dimers of isobutylene, TMK, esters — are fed to the preparation of motor fuels or used for a known purpose [P RF patent No. 2179983, IPC C08F 210/12, publ. 02/27/2002, bull. No. 6].

The disadvantage of this method is that the bottom residue of the distillation of isobutylene isolated from TMK dehydration products is returned to the start of processing the isobutylene-containing fraction, and the bottom residue, which is from 5 to 10 wt.% Of the total amount of isobutylene, goes through all energy-intensive stages - rectification of isobutylene-containing fractions, concentration of TMK from an aqueous solution by distillation, dehydration of TMK and purification by rectification of isobutylene monomer. In this case, losses of isobutylene occur at the stage of distillation of linear С ₄ and insufficient run of polymerization reactors is observed.

The objective of the invention is to reduce the amount of oxygen-containing impurities in isobutylene fed to the polymerization, isobutylene losses, increased conversion, increased travel time of polymerization reactors with the production of butyl rubber without compromising quality.

The problem is solved in that in the proposed method for the production of butyl rubber by copolymerization in the presence of a catalyst in an environment of isoprene chloromethyl with isobutylene, a distillate of a trimethicarbinol dehydration distillation product distillate column, rubber degassing, return product rectification on an isobutylene-chloromethyl-isobutylene-isobutylene-isobutylene-isoprene-isobutylene-separation column separation of chloromethyl from the isobutylene-chloromethyl fraction and separation of the isobutylene-isoprene fraction into isobutylene and iso a pre-containing fraction, while the distillation column product of the trimethylcarbinol dehydration column is fed to the additional distillation column, the distillate of the distillation column is fed to the distillation column of the trimethylcarbinol dehydration product, and the distillation column product of the distillation column is directed to the separation of the isobutylene-isoprene fraction.

In contrast to the known method, these technical methods, in particular the additional rectification of hydrocarbons of the cube of the isobutylene distillation column isolated from TMC dehydration products, allow isolated isobutylene from the top of the additional distillation column to be fed, bypassing all the energy-intensive stages of isobutylene purification and processing, to the isobutylene rectification column, isolated from TMC dehydration products. The processing of hydrocarbons from the cube of the additional distillation column together on the column for isolating isobutylene from the isobutylene-isoprene fraction of the polymerization return processing unit allows completely isolating isobutylene from this stream, and sending heavy hydrocarbons, including oxygen-containing hydrocarbons, from the column cube with the C ₅ fraction to the separation unit isoprene from the C ₅ pyrolysis fraction.

An additional advantage of this method of producing butyl rubber is that eliminating the recycle of the bottom residue of the isobutylene rectification column makes it possible to increase the productivity of the isobutylene hydration and dehydration units, facilitates the operation of the isobutylene separation columns from isobutylene-containing fractions and the isobutylene rectification after TMC dehydration.

The proposed method is carried out according to the scheme shown in the drawing, as follows. Isobutylene isolated from TMC dehydration products is fed to rectification column 2 through line 1. Isobutylene from the top of column 2 is fed through line 3 to azeotropic drying to column 4. Dried isobutylene is fed through line 5 to the polymerization unit. Hydrocarbons from the cube of column 2 along line 6 are sent to column 7 for additional rectification. Isobutylene from the top of column 7 via line 8 is returned to the cube of column 2, and bottoms containing heavy hydrocarbons are sent via line 9 to the isobutylene-isoprene fraction separation column.

The mixture obtained by mixing isobutylene in line 5, isoprene in line 10 and return chloromethyl containing from 1 to 6 wt.% Of isobutylene (isobutylene-chloromethyl fraction) fed through line 11 is fed to copolymerization in reactor 12, carried out in the presence of Friedel catalyst -Crafts, for example, a solution of aluminum chloride in chloromethyl, supplied through line 13. The reaction products are a suspension of butyl rubber in chloromethyl, non-polymerized isobutylene and isoprene are withdrawn from reactor 12 through line 14 to rubber degassing in the presence of water vapor a hot water circulation, antiaglomeratora crumb rubber, antioxidant, and an aqueous alkali solution (in the figure, these flows are not shown). Degassing is carried out in a degassing system 15, operating under slight excess pressure in the first stage and a vacuum of 0.04-0.08 MPa in the subsequent stages of degassing.

A suspension of rubber in water is sent along line 16 to concentration, isolation and drying of rubber to compartment 17, and degassing vapors containing chloromethyl, unpolymerized isobutylene and isoprene, water are fed through line 18 to condensation, compression and drying (not shown in the drawing).

In the department 17, the rubber suspension is concentrated in water, the rubber is pressed from water, and the rubber is dried in a worm-squeezed drying unit. The finished butyl rubber on line 19 is sent for briquetting and packaging (not shown in the drawing).

After compression and drying, the hydrocarbon condensate is sent to a tank 20, from where, through line 21, return products are rectified to column 22, along the top of column 22, part of the isobutylene-chloromethyl fraction is sent to line 24 to column 24 to separate chloromethyl from the top of the column. The main part of the isobutylene-chloromethyl fraction along line 11 is fed to the charge preparation unit.

From column 24 through line 26, chloromethyl is sent to prepare a catalyst solution, and bottoms from column 24 through line 25 are fed into the cube of column 22.

The isobutylene-isoprene fraction from the bottom of the column 22 is fed via line 27 to the isobutylene-isoprene fraction separation column 28, and the bottom product of column 7 is supplied via line 9 to the same line 27 for co-processing and distillation of the isobutylene return from line 29. Cubic the product from column 28 containing isoprene, C ₅ hydrocarbons, isobutylene dimers and a heavy residue is sent via line 30 to the C ₅ pyrolysis fraction processing unit.

Obtaining butyl rubber by the proposed method is illustrated by the following examples.

Example 1

Butyl rubber is produced by a known method. The isobutylene-containing fraction coming to production is rectified from heavy hydrocarbons, washed with water from water-soluble impurities, isobutylene is isolated from this fraction by hydration and subsequent dehydration of TMC. Further, isobutylene is subjected to rectification to separate from heavy and oxygen-containing compounds. Isobutylene, riding the top of this column, is fed to azeotropic drying, and then to prepare the mixture, which is a mixture of isobutylene and isoprene in chloromethyl. Hydrocarbons from the cube of the isobutylene rectification column are returned and mixed with the initial isobutylene-containing fraction entering the production.

The resulting mixture is fed into the polymerization reactor, which also serves a solution of a catalyst - aluminum chloride in chloromethyl. The resulting suspension of the polymer in chloromethyl and non-polymerized monomers is withdrawn from the polymerization unit to a degassing unit. A crumb of rubber in water after two stages of degassing is sent for concentration, drying on extruder machines and briquetting. And degassing vapors, consisting of chloromethyl, non-polymerized isobutylene, isoprene and water, are fed to the processing unit for the return of polymerization products. In the first distillation column upstream, the isobutylene-chloromethyl fraction is distilled off, from which chloromethyl, which is used to prepare the catalyst, is distilled off on the next column by dissolving aluminum chloride in it. The bottoms product of this column is returned to the cube of the first distillation column. The isobutylene-isoprene fraction from the bottom of the first column is fed to the isobutylene recovery column.

Isobutylene fed to the polymerization from the bottom of the azeotropic drying column according to this scheme contains 0.0005-0.0006 wt.% Carbonyl compounds.

The mode of copolymerization of isobutylene with isoprene. The composition of the mixture, wt.%: Isobutylene - 22.5, isoprene - 0.70, chloromethyl - 76.8. The temperature of the mixture minus 90 ° C, the temperature of the catalyst complex minus 90 ° C. The concentration of the catalyst solution in chloromethyl is 0.12 wt.%. The duration of the polymerization cycle is 58 hours. The dosage of the catalyst is 0.028% by weight of the monomers. The conversion of monomers is 80.5%. The production of butyl rubber by one reactor is 2.988 t / h. Product quality: Mooney viscosity (MB1 + 8, 125 ° C) 50.0 ± 2.0. Uncertainty 1.6 ± 0.13 mol.%.

Example 2

Butyl rubber is obtained by the proposed method. The isobutylene-containing fraction coming to production is rectified from heavy hydrocarbons, washed with water from water-soluble impurities, isobutylene is isolated from this fraction by hydration and subsequent dehydration of TMC. Further, isobutylene is subjected to rectification to separate from heavy and oxygen-containing compounds. Isobutylene, riding the top of this column, is fed to azeotropic drying, and then to prepare the mixture, which is a mixture of isobutylene and isoprene in chloromethyl. Hydrocarbons from the cube of the isobutylene distillation column are fed to the additional distillation column to further recover isobutylene. The isobutylene highlighted at the top of this column is returned to the distillation column, and the bottoms product is sent to the isobutylene-isoprene fraction separation column to the processing unit for recycling the polymerization products. The average composition of the bottom product of the column additional distillation, wt.%:

divinyl 0,07 isobutylene 82.9 trans butylene 0.33 cis-butylene 0.35 acetone + isopropanol 0.68 amylene 0.58 isoprene 0,03 TMK 6.22 MTBE 0.06 sec-butanol 0.01 methyl isopropyl ketone 0.25 isopropyl tert-butyl ether 1.17 methyl ethyl ketone 0.67 isobutylene dimers 1.51 esters 5.22

The resulting mixture is fed into the polymerization reactor, which also serves a solution of a catalyst - aluminum chloride in chloromethyl. The resulting suspension of the polymer in chloromethyl and non-polymerized monomers is withdrawn from the polymerization unit to a degassing unit. A crumb of rubber in water after two stages of degassing is sent for concentration, drying on extruder machines and briquetting. And degassing vapors, consisting of chloromethyl, non-polymerized isobutylene, isoprene and water, are fed to the processing unit for the return of polymerization products. In the first distillation column upstream, the isobutylene-chloromethyl fraction is distilled off, from which chloromethyl, which is used to prepare the catalyst, is distilled off on the next column by dissolving aluminum chloride in it. The bottom product of this column is returned to the bottom of the column for the separation of isobutylene-chloromethyl and isobutylene-isoprene fractions. The isobutylene-isoprene fraction from the bottom of the first column is fed to the isobutylene recovery column. The cube of the column for additional rectification of isobutylene is fed into the feed of the same column for joint processing and recovery of isobutylene. The bottoms product of this column is sent to a C ₅ pyrolysis fraction processing unit. The composition of the bottom product of the recovery column of isobutylene recovery,% wt .:

α + isobutylene 0.02 sum of β-butylenes 0.03 isopentane 1.5 n-pentane 51.07 Amylene Amount 0.753 cyclopentane 0.21 isoprene 45.46 amount of oxygen compounds 0.318 sum of isobutylene dimers 0.692 sum of isobutylene trimers 0.083 sum of isobutylene tetramers 0.0271 sum of isoprene dimers 0.108

Isobutylene, completely extracted from the isobutylene-isoprene fraction at the top of the column, is sent to the preparation of the mixture.

Isobutylene fed to the polymerization from the bottom of the azeotropic drying column in accordance with this method contains not more than 0.0001 wt.% Carbonyl compounds.

The mode of copolymerization of isobutylene with isoprene. The composition of the mixture, wt.%: Isobutylene - 30.0, isoprene - 0.93, chloromethyl - 69.07. The temperature of the mixture minus 90 ° C, the temperature of the catalyst complex minus 90 ° C. The concentration of the catalyst solution in chloromethyl is 0.08 wt.%. The duration of the polymerization cycle is 76 hours. The dosage of the catalyst is 0.016% by weight of the monomers. The conversion of monomers to 85.7%. The production of butyl rubber by one reactor is 3.5 t / h. Product quality: Mooney viscosity (MB1 + 8, 125 ° C) 50.0 ± 2.0. Uncertainty 1.6 ± 0.13 mol.%.

As can be seen from the examples, the use of the proposed method can significantly reduce the amount of oxygen-containing impurities in isobutylene, and due to this, increase the concentration of isobutylene in the charge and reduce losses of isobutylene, increase conversion and increase the run time of reactors with rubber production without deterioration.

Claims (1)

A method of producing butyl rubber by copolymerization in the presence of a catalyst in the environment of isoprene chloromethyl with isobutylene, distillate of a distillate of a rectification column of trimethylcarbinol dehydration products, rubber degassing, distillation of return products on an isobutylene-chloromethyl and isobutylene-isoprene fraction separation isobutylene fraction, followed by isolation and the separation of the isobutylene-isoprene fraction into isobutylene and isoprene-containing fraction, characterized in that the cubes the first product of the trimethylcarbinol dehydration product distillation column is fed to the additional distillation column, the distillate of the additional distillation column is fed to the distillation column of the trimethylcarbinol dehydration product, and the still product of the additional distillation column is sent to the separation of the isobutylene-isoprene fraction.