CS235995B2 - Method of 1,2-dichlorethane production - Google Patents

Abstract

Process for producing 1,2-dichloroethane by reaction ethylene and chlorine in the solvent in the presence mixed catalyst from anhydrous ferric chloride and other components of the mixture and optionally in the presence of an inhibitor to prevent byproduct formation at a temperature of from 20 to 200 ° C and at atmospheric or increased pressure and separation 1,2-dichloroethane from the chlorination mixture by rain, It is characterized by having another component the mixture is ammonia, primary, secondary or tertiary alkylamine, aralkylamine, arylamine or an alicyclic amine or polyamine or a salt of this nitrogen base with halogen, especially ammonium chloride, while the latter the component is present in the mixture in an equivalent amount, based on the amount ferric chloride and chloride concentration % ferric is 0.005 to 0.5% by weight, based on the amount of solvent.

Description

The present invention relates to a process for the preparation of 1,2-dichloroethane.

The preparation of 1,2-dichloroethane by reaction of ethylene with chlorine in 1,2-dichloroethane as solvent and reaction medium is already known. As a major by-product, this reaction is formed

1.1.2- trichloroethane by substitution of dichloroethane. To suppress this substitution reaction, it is used as catalysts in addition to the chlorides of elements IV. to VI. % of the periodic system, in particular anhydrous ferric chloride, partly in the presence of oxygen, since ferric chloride is readily available and inexpensive.

The resulting crude dichloroethane-containing catalyst is generally withdrawn from the recovery vessel and treated with water and / or aqueous alkali solutions to remove the catalyst and the hydrogen chloride contained in the crude product and then distilled in a known manner.

The use of ferric chloride as a catalyst has certain disadvantages in the addition chlorination of ethylene. Thus, in the presence of water, ferric chloride is corrosive to the metallic materials of the reactors, columns or heat exchangers when they come into contact with the catalyst. Chlorine of the technical grade, which is usually used for chlorination, always contains traces of moisture as well as hydrogen chloride from undesirable side reactions.

If the thermal energy released in the chlorination of ethylene is to be recoverable, the reaction must be carried out at temperatures above the boiling point of dichloroethane at atmospheric pressure. Since the degree of corrosion increases considerably with increasing temperature, it is inevitable to equip the chlorination reaction apparatus with corrosion-resistant materials, thereby adversely affecting the economy of the process used.

It has now been found that the corrosion caused by ferric chloride catalyst in the production of 1,2-dichloroethane in corrosion-resistant reactors can be greatly reduced when the ferric chloride catalyst is used with certain additives. In addition, it has been found that these additives also have an advantageous effect on the formation of a by-product which is thereby reduced.

The present invention provides a process for the preparation of 1,2-dichloroethane by reacting ethylene with chlorine in a solvent in the presence of a mixed catalyst consisting of anhydrous ferric chloride and another component of the mixture, and optionally an inhibitor to prevent by-products formation at 20 to 200 ° C. atmospheric or elevated pressure and separation

1,2-dichloroethane from the chlorination mixture by distillation, characterized in that the other component of the mixture is ammonia, primary, secondary or tertiary alkylamine, aralkylamine, arylamine or alicyclic amine or polyamine or a halogenated salt of this nitrogenous base, in particular ammonium chloride; the component is present in the mixture in an equivalent amount based on the amount of ferric chloride and the concentration of ferric chloride is 0.005 to 0.5% by weight based on the amount of solvent.

According to a preferred embodiment of the process according to the invention, 1,2-dichloroethane is used as the solvent and oxygen is used as inhibitor and.

Further details of the process according to the invention must be made:

Catalyst ae generally dissolves or suspends in the solvent present in the reactor. However, the catalyst ae may also be prepared outside the reaction solution by suspending anhydrous ferric chloride together with another catalyst component, for example in 1,2-dichloroethane, and feeding the suspension to the reactor. It is also possible to add anhydrous ferric chloride and ammonia or an amine to the solvent present in the reactor. In the subsequent reaction, hydrogen chloride is formed in sufficient quantity to form the corresponding ammonium or ammonium salt.

The process according to the invention is to be regarded as technically progressive, since in its use it greatly suppresses the corrosion when using the corrosion-resistant metal reactors that occur and which are disadvantageous in the known production methods.

1,2-dichloroethane. Further, it has been found that, with the exception of a small amount of the first 1,1,2-trichloroethane substitution product and a corresponding small amount of hydrogen chloride, no further by-products are formed under the conditions of the process of the invention. The reaction solution remains light, even over a longer reaction time, if the additives according to the invention are present in the reaction solution in the approximately equivalent amount due to the ferric chloride present. Alternatively, as a consequence of the reaction, the dark-colored reaction mixture again brightens during the further course of the reaction depending on the addition of said compounds. Finally, it has been found that the conversion in the process according to the invention is almost quantitative at a high yield per unit of space and time.

The process according to the invention can be carried out, for example, in a loop-shaped reactor as described in DB-OS 24 27 045 or in any other reactor suitable for carrying out the process.

The present invention is illustrated in more detail by the following non-limiting examples.

Example 1

A 2 L loop reactor was charged with 2.0 kg 1,2-dichloroethane and 4 g anhydrous ferric chloride. To this mixture was added 0.42 g of ammonia as a 0.67% (w / w) solution in dichloroethane at a temperature of 30 to 40 ° C. The upstream part of the reactor loop comprises a layer of packed bodies. Underneath this layer of packed bodies ae feed tubes are provided to the reactor for ethylene, chlorine and air, through which at least 60 l / h of chlorine and ethylene and 15 l / h of air are supplied. The reaction liquid is circulated in the mammoth reactor system while the mixed catalyst is uniformly suspended in the liquid phase. During the reaction, the reaction temperature in the reaction mixture was maintained at 77 ° C. The concentration of the mixed catalyst dissolved in the reactor liquid, determined as ferric chloride, was 0.13% by weight after several days.

In the water cooler above the reactor, the dichloroethane vapors discharged from the reactor are condensed and then one portion of the condensate corresponding to the amount produced is vented and withdrawn while the excess portion of the condensate is returned to the reaction zone. A further portion of dichloroethane is separated from the off-gas consisting mainly of inert gases by means of a cooled charge. After several days of continuous operation, the mixed catalyst was substantially completely dissolved in the liquid contained in the reactor and the colorimetric determination of the iron content of the liquid contained in the reactor indicated the ferric chloride content and 0.13% by weight. The amount of 1,2-dichloroethane formed per hour is 262 g. The process is carried out continuously for 14 days.

The analysis of the product A formed in the condenser and / or the liquid B contained in the reactor after the completion of the reaction yields the following values:

product A product B

(.% by weight) (Ž by weight)

c ₂ h ₅ ci <0.002 <0.002 1,2-dichloroethane 99.94 99.82 1,1,2-trichloroethane 0.04 0.14 HCl <0.001 - other 0.01 0.04

Example 2

The procedure is analogous to Example 1, except that 50 ml of 1,2-dichloroethane containing 0.4% by weight of 1,1,2-trichloroethane are added dropwise to the reaction mixture circulating in the reactor by means of a dropping funnel. The amount of 1,2-dichloroethane produced per hour is 326 g. The duration of the experiment is 8 days.

The analysis of product A produced in the condenser or liquid B contained in the reactor yields the following values after completion of the reaction:

product A product B weight) (% weight)

c ₂ h ₅ ci <0.002 <0.002 1,2-dichloroethane 99.87 99.6, 1,1,2-trichloroethane 0.10 0.34 HCl <0.001 - other 0.03 0.05

Example 3

The procedure is analogous to that described in Example 1 except that the concentration of ferric chloride in the reaction mixture and the molar ratio of ferric chloride to ammonia vary.

The following table shows the extent to which these changes were made and how these changes affected the 1,2-trichloroethane and hydrogen chloride content of the condenser product.

FeCl ₃ concentration table (% by weight) molar ratio of FeCl ₃ : HN ₃ % by weight 1,1,2-trichloroethane * weight HCl 0.07 1: 2 0.2 0.004 0.34 1: 2 0.6 0,002 0.45 1: 1.5 0.1 0.001 0.32 1 - 1 0.06 <0.001

The amount of 1,2-dichloroethane produced per hour is 260 g for the ferric chloride concentration and the experiment duration is 19 days.

The analysis of the product A produced in the condenser or the liquid B contained in the reactor gives the following values after completion of the reaction:

4® product A (% by weight) product B (56% by weight)

C ₂ H ₅ Cl 4 0.002 <0.002 1,2-dichloroethane 99.93 99.78 1,1,2-trichloroethane 0.06 0.19 HCl 0.001 - other 0.01 0.03

Example 4

The procedure is analogous to Example 1 except that 1,35 g of 1,2-dichloroethane is used and instead of ammonia 1,3 g of trimethylamine dissolved in 30 ml of 1,2-dichloroethane is used and this solution is introduced into the reaction solution. The amount of 1,2-dichloroethane produced per hour is 276 g and the duration of the experiment is 6 days. Soli The colorimetrically determined content of ferric chloride in the solution is 0.13% by weight on average.

Analysis of the product A formed in the condenser yields the following values after completion of the reaction:

Product A (% by weight)

c ₂ h ₅ ci 1,2-dichloroethane 99.86 1,1,2-trichloroethane 0.13 HCl 0.01 other 0.006

Example 5

The procedure is analogous to Example 4, but adding, as a catalyst, 1.7 g of ferric chloride and 0.65 g of diaminoethane to the reaction solution. The colorimetrically determined iron (III) chloride content of the Sine solution averaged 0.07% by weight. 268 g of dichloroethane are obtained every hour and the experiment lasts more than 3 days.

The analysis of the product A produced in the capacitor provides the following values.

Product A (% by weight)

1,2-dichloroethane

1.1.2- trichloroethane HCl other

99.13

0.85

0.02

0.01

Example 1 id 6

The procedure is analogous to Example 1, but 1.5 g of 2-dichloroethane are used for the reaction, and the amount of catalyst is 3.3 g of ferric chloride and 3.0 g of triethanolamine. The colorimetric determination of the ferric chloride content in the reaction solution of Sine averaged 0.25% by weight. One hour and 268 g of dichloroethane were obtained and the experiment lasted for more than 6 days.

The analysis of product A produced in the capacitor gives the following values:

Product A (% by weight)

c ₂ h ₅ ci <0.002 1,2-dichloroethane 99.65 1,1,2-trichloroethane 0.33 HCl 0.007 other 0.01

Example 7

(a) In a 2-liter round-bottomed flask fitted with a stirrer, a dropping funnel and a reflux condenser, add 2 kg of 1,2-dichloroethane 8 to 2.1 g of iron chloride. The mixture was heated to boiling with stirring and then 0.2 g of ammonia dissolved in 58 g of dichloroethane was added dropwise so that the total amount of catalyst was 2.3 g.

The mixture is then refluxed for a further 5 hours and the iron chloride content of the solution is 0.11% by weight.

b) The mixture of dichloroethane and catalyst is then charged into the loop reactor as described in Example 1 and then fed about 60 L / h of chlorine and ethylene together with about 5 L / h of air into the reactor. One hour is obtained with 273 S of dichloroethane and the experiment lasts 8 days.

The analysis of product A, which is obtained in the capacitor, gives the following values:

product A (96% by weight)

C ₂ H ₅ Cl. <0.002

1,2-dichloroethane 99.51

1,1.2-Trichloroethane 0,48

HCl 0,002 other 0,009

Example

a) The procedure is analogous to Example 7a), except that 1.5 kg of 1,2-dichloroethaau and 12 g of ferric chloride are heated with stirring. A solution of 2.7 g of hydrogen chloride in 750 g of dichloroethane was added dropwise thereto, followed by the dropwise addition of a solution of 1.26 g of ammonia in 273 g of dichloroethane. After cooling, the reaction mixture is filtered and the residue on the filter is dried. 14.4 g of dry catalyst are obtained.

X

(b) In order to produce 1,2-dichloroethane, 4 g of the catalyst prepared in (a) and 2 g of ferric chloride are suspended in 2.7 kg of 1,2-dichloroethane and, after concentrating the mixture to about 2 liters, The mixture is introduced into a loop reactor as described in Example 1. Hourly, 60 L of chlorine and ethylene and 15 liters of air are introduced into the loop reactor and the reaction is started in the manner and under the reaction conditions given in Example 1. 266 g of 1,2-dichloroethane are obtained and the experiment takes 6 days. The content of ferric chloride, which was measured colorimetrically in the reaction solution, was an average of 0.15% by weight.

The analysis of the product A produced in the condenser or the liquid B contained in the reactor after the completion of the reaction gives the following values:

product A product B (8 weight) (8 weight)

C ₂ H ₅ Cl 0.004 0.006 1,2-dichloroethane 99.93 99.74 1,1,2-trichloroethane 0.06 0.23 HCl 0,002 0.03 other 0.003 -

Example 9

In the 1,2-dichloroethane reactor, corrosion testing samples are placed at four locations and subjected to the process conditions of the invention. After 20 days, samples are taken from the reactor to detect corrosion damage. When using a catalyst according to the invention consisting of a mixture of ferric chloride and ammonia and maintaining a reaction temperature of 100 to 110 ° C, the average degree of corrosion for non-alloy steel is less than 0.05 mm per year. If, on the other hand, the process is carried out in any way exclusively using ferric chloride as the catalyst, then the average degree of corrosion for the non-alloy steel is 0.43 mm per year.

Claims (1)

SUBJECT OF THE INVENTION A process for preparing 1,2-dichloroethane by reacting ethylene with chlorine in a solvent in the presence of a mixed catalyst of anhydrous ferric chloride and another component of the mixture and optionally in the presence of an inhibitor to prevent the formation of by-products at 20 to 200 ° C and atmospheric or elevated pressure; separating 1,2-dichloroethane from the chlorination mixture by distillation, characterized in that the other component of the mixture is ammonia, primary, secondary or tertiary alkylamine, aralkylamine, arylamine or alicyclic amine or polyamine or a halogenated salt of this nitrogenous base, in particular ammonium chloride, the other component being present in the mixture in an equivalent amount based on the amount of ferric chloride and a concentration of ferric chloride of 0.005 to 0.5% by weight based on the amount of solvent.