DD204481A1 - PROCESS FOR RECOVERING SOLVENTS AND MONOMERS - Google Patents

Abstract

The invention relates to a process for the quantitative recovery of solvents and monomers from the liquid fractions of polymer suspensions containing oligomers, polymeric solids and active catalyst components. The method is particularly suitable when used as a solvent aliphatic hydrocarbons, as a monomer norbornene (Bicyclo (2,2,1) heptene (2)) and ZIEGLER NATTA type catalysts. According to the invention, the recovery of the solvent and of the monomer takes place simultaneously and without prior inactivation of the catalyst by feeding the liquid fractions of polymer suspensions to a two- or multi-stage evaporation plant, wherein the second or last evaporator is fed with a high-boiling hydrocarbon as flux, in which oligomers , polymeric solids and catalyst components are enriched. The solvent and monomer mixtures are introduced into a column for further workup of the mixture. The flux-enriched catalyst is decomposed by the addition of gaseous ammonia. It is possible to recover both pure solvent, pure monomer and monomer in admixture with the solvent.

Description

2Ί R 7

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VEB Leuna-Werke Leuna,

"Walter Ulbricht" ' ' *

LP 8155

Title of the invention

Process for the recovery of solvents and monomers

Field of application of the invention

The invention relates to a process for the quantitative recovery of solvents and monomers from the liquid fractions of polymer suspensions, in which oligoaere, polymeric pesticides and active catalyst components are included.

The process is particularly suitable if the solvents used are aliphatic hydrocarbons, as monomer norbornene (bicyclo (2,2,1) heptene (2) 5 and ZIEGLER-iJATTA type catalysts).

Characteristic of the known technical solutions

According to the state of the art, for the recovery of solvents from polymerization mixtures obtained by polymerization of conventional olefinic hydrocarbons, the active catalyst components are first of all

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decomposed by addition of hydroxyl groups or basic nitrogen compounds, the decomposition products then extracted with polar solvents (alcohol, water) or aqueous acids and then the polymer separated from the solvent · Before re-etching of the solvent, the polar substances must be separated. (DE-PS 1 420 461, DE-PS 2 315 480, DE-PS 1 163 030).

It is also well known to recover the solvents by concentrating the polymer filtrate in a forced circulation evaporator to remove the solvents overhead. This method has been used in polypropylene production where the solvent used was an isopropanol / n-heptane mixture. as unsuitable. It was therefore proposed that the contaminated solvent one

1. or · to supply a second evaporator and to recover larger amounts of the solvent overhead and the residue from the 1 # or · 2 stage together with a high-boiling aromatic hydrocarbon (flux) one

2. or 3 «to supply evaporator stage. The high boiling hydrocarbon has an initial boiling point above the boiling point of the solvent. Pure, the solvent mixture isopropanol / n-heptane temperatures of 150 ⁰ C to 370 ⁰ G or greater 148.9 ⁰ C specified. The recovery of monomers does not occur (DE-PS 1 520-700, DE-PS 1 645 207).

Object of the invention

The aim of the invention is an energetically favorable recovery of both the solvent and the unreacted monomer from the liquid portions of Polymersuspeosionen.

Essence of the invention

The invention has for its object to develop a method in which from a polymer filtrate, the solution of

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Monoinerea (norbornene), Oligoineren, polymeric solids and active catalyst components consists, without prior inactivation of the catalyst is an energetically favorable, quantitative recovery of the solvent and the monomer occurs · The recovered solvent and the monomer should be free of polar substances and largely free of aromatic hydrocarbons, and the resulting residues should be a safe remedy. (Combustion) ·

The object is achieved by a process for the recovery of solvents and monomers from the liquid contents of polymer suspensions, in addition to the solvents, in particular aliphatic hydrocarbons, and the monomers, in particular ÜTorbornen (bicyclo (2,2,1) heptene * (2) ), including QIigomers, polymeric pesticides and active catalyst components, preferably of the ZIEGLER NATTA type, wherein according to the invention the contaminated liquid mixture is introduced into a first evaporator stage or into a series of consecutively connected evaporator stages, in which or most of which the solvent is and the monomer is evaporated, then the concentrated mixture is fed together with a flux to a second or last stage of the evaporator, in which the residual solvent and residual monomers are recovered, and the flux, in addition to the oligomers and small amounts of solvent and monomers rem contains the catalyst in enriched form, is fed to a container in which the active catalyst is decomposed

Before introducing the contaminated liquid mixture into the first evaporator stage, it is expediently heated to boiling temperature. In the first stage, the evaporation usually takes place under atmospheric pressure, while in the second or last stage it is preferably carried out under reduced pressure

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is carried out·

An energetically favorable process procedure is achieved if the solvent and monomer vapors from the individual evaporator stages are introduced directly into a rectification column.

The temperatures in the evaporator stages and the degree of enrichment of oligomers, polymeric solid and catalyst components in the flux are suitably chosen so that the monomer is not thermally decomposed and the required heat transfer in the apparatus and the ability to convey the flux are ensured.

"Preferably, a high-boiling hydrocarbon or a mixture of hydrocarbons having a boiling point above 200 ⁰ C is used as a flux." The decomposition of the active catalyst is carried out by adding gaseous ammonia · The residue can be fed to a combustion plant ·

The initial concentration of the starting mixture can be carried out either in a single evaporation stage or in a series of evaporation stages, if this simplifies the technological realization.

The separation of the vapors from the evaporators into a purified solvent and horbornene or monomer is achieved by rectification.

Compared with the technology for recovering the solvent by adding steam, heating steam is saved in the process according to the invention and the losses of solvent and monomers! significantly lowered ·

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embodiment

The invention will be explained below with reference to an example and the accompanying drawing · According to the drawing, the contaminated liquid portion of the polymer suspension, consisting of solvent, monomers, oligomers, polymeric pesticide and catalyst at a temperature of about · 20 ⁰ C occurs through the Line 1 in the heat exchanger 2 a · In this heat exchanger, the contaminated liquid is heated to boiling temperature and passes via line 3 into the separation vessel 4 of the 1st evaporation stage. Via the line 5, the liquid is passed into the evaporator 6, are evaporated in the ca · SOf ₀ of the occurred through the line 3 liquid mixture · A vapor-liquid mixture passes back via the line 7 in the separation vessel 4, in which the Liquid is separated and continues to circulate while the steam leaves the separation vessel 4 via the line 8. The concentrated residue from the separation vessel 4 passes via line 9, into which a high-boiling hydrocarbon, a vacuum distillate from the petroleum processing, as flux from the line 10 The liquid from the separation tank 12 passes through the line 13 to the evaporator 14, in which the remaining amounts of solvent and monomers are evaporated. Via the line 15, a vapor-liquid mixture is returned to the separation vessel 12, while via line 16, the enriched with oligomers, polymeric fine grain and undecomposed catalyst flux is fed into the container 17. With ammonia from the line 18, the catalyst is decomposed. The contaminated flux is supplied via line 19 to a combustion plant. Via the line 20 leave the vapors of the solvent and Uorb'ornens the separation vessel 12 and are with the vapors from the

The product vapor obtained at the top of the column 21 passes via the line 22 into the condenser 23 and is condensed there. A portion of the condensate is fed via the lines 24 and 25 to the column 21 as reflux, while the other The bottom product of column 21 is withdrawn via lines 27 and 28. A portion of the bottoms liquid passes via line 29 into evaporator 30 and recirculates via line 31. With a sharp separation and depending on the boiling position can be recovered as distillate or as bottoms largely pure solvent or substantially pure monomer. It is also possible to obtain the monomer in admixture with the solvent. When using a hexane fraction as solvent and norbornene as monomer, it is possible to save approximately 40 to 50 % of heating steam compared to the known processes.

Claims (4)

~ 7π λ η ι α π r * invention claim 1. A process for the recovery of solvents and monomers from the liquid fractions of polymer suspensions, in addition to the solvents, in particular aliphatic hydrocarbons, and the monomers, in particular ITorbornen (Bicyclc (2,2,1) hepten- (2)), also oligomers, polymers Solids and active catalyst components, preferably of the ZIEGLER-NATTA type, characterized in that the contaminated liquid mixture is introduced into a first evaporator stage (4; 6) or into a series of successive stages of the fermenter, in which or most of which the solvent and the monomer is then passed, the concentrated mixture is then fed together with a flux of a second or last evaporator stage (12; 14), in which the residual solvent and residual monomers are recovered, and the flux, in addition to the Oligomereη and small amounts of solvent and monomer the Kataly in an enriched form, fed to a container (17), where the active catalyst is decomposed » 2 · Method according to item 1, characterized in that the solvent and monomer vapors from the individual evaporator stages are introduced directly into a rectification column (21). 3. The method according to item 1 and 2, characterized in that a high-boiling hydrocarbon or a mixture of hydrocarbons having a boiling point above 200 ⁰ C is used as the flux. 4. The method according to item 1 and 3, characterized in that the decomposition of the active catalyst is carried out by adding gaseous ammonia · This includes 1 sheet drawing For this ή Ropes drawings