DD144907A1 - METHOD FOR THE CONTINUOUS PREPARATION OF WAESSED PROPYLENEHLORHYDRIN SOLUTIONS - Google Patents

Abstract

According to the invention, the enrichment and deposition of the water-insoluble by-product of the chlorohydrinization of propene, of dichloropropane, can be prevented in the reactor. So far, this succeeds only by sufficient introduction of stripping gas. This diminished but the space-time yield, as it reduces the reactor capacity. By a conically shaped discharge of the product over Head of the reactor creates a laminar flow and prevents the swirling back of the dichloropropane in the reactor, or its Deposition on the liquid surface and on the reactor walls, According to the invention no stripping gas for discharging the Dichloropropane needed more. Furthermore, a gas space in the reactor avoided what the safe use of the oxygenated Electrolysis chlorin and optionally air (as stripper gas) allows.

Description

Applicant: VEB Chemische Werke Buna 4212 Schkopau

Authorized representative: Dipl.-Chem * Ortrud Heyer

in the combine

VEB Chemical Works Buna 4212 Schkopau

Title of the invention

Process for the continuous formation of aqueous propylene chlorohydrin solutions

Field of application of the invention

The invention relates to a process for the continuous preparation of aqueous propylene chlorohydrin solutions by reacting propylene and chlorine in water in a bubble column reactor in the presence of stripper gas.

16.JOL. 19 73 * & nü!

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Characteristic of the known technical solutions

It is generally known that the preparation of alkylene chlorohydrins, for example propylene chlorohydrin, is carried out by reacting alkylene and chlorine in water in bubble column reactors in order to achieve the finest possible distribution of the reacting gases in the aqueous medium. "In the chlorohydrination, water-soluble dichloroalkenes are formed by lifting reactions. for example, bichloropropane, which, by virtue of its increased solubility for the reacting agent, continues to give rise to an additional formation of dichloroalkanes. "(W _e G ₄ , Domask, K * A, Kobe, Ind _e and Enge Chem. VoI * 46, p. 680). 689)

Therefore, in practice by supplying Strippergae ensured that the water-insoluble phase of the dichloroalkanes is discharged as quickly as possible from the bubble column reactor or · can not form a water-insoluble liquid phase * This reduces the residence time of the dichloroalkane, but with increasing Strippergasmenge occurs Reduction of space-time yields to · (B _e P. 738 171)

DE-OS 2107 960 and DE-OS 2022 819 describe a process in which the reacting gases are finely distributed by means of jet mixing nozzles and the dichloroalkane formation is reduced by short passages in the reaction tubes. However, the highly corrosive medium requires corrosion resistant materials for the compressors.

A reduction of Dichloralkanbildung is achieved according to DE-PS 1156 394 by a cascade connection of the reactors. By connecting in series, for example, four reaction towers and introducing all the water required into the first tower, the chlorine ion concentration in the first reactors is kept low. The desired concentration of alkene chlorohydrin is reached only in the fourth reactor and thus also the residence time of the same at high chlorine ion

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Concentration diminished (High chloride ion concentration favors the formation of dichloroalkanes.) The disadvantage of this circuit is that all four reactors fail in case of damage to one reactor.

Aim of the invention

The aim of the invention is to reduce the formation of the product by-products in the reaction of propylene and chlorine in water, for example of dichloroalkanes, to prevent the segregation of the reaction mixture or the compact separation of water-insoluble dichloroalkanes and to reduce the stripping gas volume. To increase the yield of propylene chlorohydrin.

Explanation of the essence of the invention

- Problem de r invention

The invention is based on the object of developing an improved economical process for the preparation of aqueous propylene chlorohydrin solutions by reacting propylene and chlorine in water under known reaction conditions in a bubble column reactor with or without the presence of stripping gas (preferably air) according to the object of the invention.

Features of the invention

The object is achieved in that the reaction of the reactants takes place in the completely filled with the reaction mixture bubble column, discharged the reaction mixture via a conical reactor head or via a triehter «or spherical installation on the reactor head and the

Separation of the reaction mixture in the aqueous phase and the gas phase made outside the bubble column

By the method according to the invention existing in the known processes gas chambers in the reactor are reduced or "completely avoided, which is safety advantage" Surprisingly, the segregation of the reaction mixture in the reactor in the gas and liquid phase and the deposition of a water-insoluble phase is prevented, so that to u _e a "represents dichloropropane not settle as an oily film on the surface of the reaction mixture * the fine distribution of the dichloropropane in the reaction medium enables a reduction of the stripping gas quantity and the dichloropropane is continuously discharged at a shorter residence time in the reactor, with no accumulation of dichloropropane in the reaction mixture occurs. In contrast to the solution according to the invention, the by-produced dichloroalkane precipitates in the known processes as an oily layer in the bubble column reactor at the interface of liquid and gas phase. This oily layer on the surface of the bubble column is swept back into the reactor by the vigorous turbulence in the liquid and thus dichloroalkane is enriched in the reactor. In the case of the lateral product discharge hitherto customary in the prior art, the discharge of the dichloroalkanes is made more difficult by the ratio of large liquid surface area to small discharge area, and thus the residence time of the dichloroalkanes in the reactor is also increased. In addition, the expulsion of the dichloroalkanes requires a large excess of stripping gas, which, however, reduces the space-time yield of propylene chlorohydrin and makes the deposition of dichloroalkane, for example dichloropropane, more difficult.

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In the procedure according to the invention, therefore, no excess of inert gases or of propylene is required in order to expel dichloroalkane from the reactor by the stripping action. While avoiding a gas space in the reactor can be used as stripper gas even air as the risk of explosion in the reactor void ·

Furthermore, the introduced propylene can be fully utilized, as previously unconverted Px'opylen was discharged in the exhaust gas from the reactor by the large Strippergas ·

The reaction of propylene and chlorine in water is carried out under the usual reaction conditions, wherein the introduced propylene can only be fully utilized if the operating mode is set up in such a way that the excess of chlorine is ensured.

The segregation of the reaction mixture takes place after exiting the bubble reactor in a separate device, which is protected by safety-related installations from explosion hazard ·

The invention will be explained in more detail by the following examples:

Example 1;

Experimental reactor with lateral product discharge

In a 400 cm high bubble reactor (10 cm 0, 26 1 content) was introduced at a molar ratio of propene to chlorine (1: 1) gas · The reaction temperature was adjusted to 50 ⁰ C and the chlorohydrin concentration to about 5 % · Da Stripper gas (Ng) was driven, differed on the liquid surface (gas space 2 1) already

After a short drive, an oily layer of dichloropropane was removed, which was only insufficiently removed by the lateral discharge. " In order to remove the continuously forming dichloropropane (DGP) from the reactor by means of a stripping gas stream (M ₂ ), as much nitrogen had to be introduced as propene was used,

Experimental reactor with conical product discharge

At the same 400 cm high bubble reactor (Example 1), the lateral discharge was closed and the product was now discharged through a cone-shaped discharge above the top of the reactor · Since now there was no gas space in the reactor (in which dangerous gas mixtures could accumulate), air could be used as stripper gas. Although no enrichment of DCP in the reactor occurred without .Stripperga3, in the interest of a better propene distribution, approximately 10 % of air was added to it.

Comparing Example 2 with Example 1, the space-time yield is improved by about 50 % and the amount of stripping gas compared to experiment 1 has been reduced to 5-10 % under otherwise identical experimental conditions in the conical discharge over head In both experiments, the dichloropropane should be discharged completely · Compared to Example 1, in Example 2 the load and product discharge are doubled in the same time with the same good turnover.

Claims (1)

14337 Erfindun gsanapruch Process for the continuous preparation of aqueous propylene chlorohydrin solutions by reacting propylene and chlorine in water under known reaction conditions in a bubble column reactor with or without stripping gas, characterized in that the reaction of the reactants in the completely filled with the reaction mixture bubble column, the reaction mixture via a conical reactor head or is discharged via a funnel-shaped or cone-shaped installation at the reactor head and the separation of the reaction mixture into the aqueous phase and the gas phase is carried out outside the bubble column.