CS235975B2 - Mixed catalyst - Google Patents

Abstract

Die Erfindung betrifft ein Katalysatorgemisch, bestehend aus wasserfreiem Eisen-III-chlorid sowie einer weiteren Gemischkomponente, zur Herstellung von 1,2-Dichlorethan durch Reaktion von Ethylen mit Chlor in einem Lösungsmittel bei Normal- oder Überdruck, welches dadurch gekennzeichnet ist, daß die weitere Gemischkomponente eine in Bezug auf die Eisen-III-chlorid-Menge etwa äquivalente Menge einer Stickstoffbase oder ein Salz dieser Base ist.

Description

(54) Mixed catalyst

Mixed catalyst consisting of anhydrous ferric chloride and one other component of the mixture for the production of 1,2-dichloroethane by reaction of ethylene with chlorine in a solvent at atmospheric or elevated pressure, characterized in that the other component of the mixture is an equivalent amount of ammonia, primary, secondary or tertiary alkylamine , aralkylamine, arylamine or an alicyclic amine or polyamines or a salt of this nitrogenous base with halogen, in particular ammonium chloride, based on the amount of ferric chloride.

The present invention relates to a mixed catalyst for the production 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. 1,1,2-Trichloroethane is a major by-product of this reaction by substituting 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The resulting crude dichloroethane-containing catalyst is generally withdrawn from the reaction vessel and treated with water or aqueous alkali solutions to remove the catalyst and the hydrogen chloride present in the crude product, followed by distillation in a known manner.

The use of ferric chloride as a catalyst is associated with certain disadvantages in the addition chlorination of ethylene. Thus, ferric chloride in the presence of water acts 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.

Accordingly, the present invention provides a mixed catalyst consisting of anhydrous ferric chloride and one additional component of the mixture to produce 1,2-dichloroethane by reacting ethylene with chlorine in a solvent at atmospheric or elevated pressure, characterized in that the other component of the mixture is an equivalent amount of ammonia, a primary, secondary or tertiary alkylamine, aralkylamine, arylamine or alicyclic amine or polylylamine or a salt of this nitrogenous base 8 with halogen, in particular ammonium chloride, based on the amount of ferric chloride.

Further details of the catalyst according to the invention are as follows:

The catalyst of the invention is generally dissolved or suspended in the solvent present in the reactor. However, the catalyst may also be prepared outside the reaction solution by suspending anhydrous ferric chloride together with the other catalyst component in, for example, 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. The subsequent reaction then produces a sufficient amount of hydrogen chloride to form the corresponding ammonium or ammonium salt.

The catalyst according to the invention is to be regarded as technically advanced, since its use greatly suppresses the corrosion of the corrosion-resistant metal reactors that occur and which is disadvantageous in the known processes for the production of 1,2-dichloroethane. Further, it has been found that, with the exception of the smallest possible amount of the first substitution product of N -tricbooroethane and the subsequent small amounts of hydrogen chloride, no other by-products are formed under the process conditions of the invention. The reaction solution remains light, even over a longer reaction time, if the additives of the invention are present in approximately equivalent bridges in the reaction solution with respect to the ferric chloride present. Alternatively, as a consequence of the reaction, the dark-colored reaction mixture is lightened again during the subsequent 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 catalyst process according to the invention can be carried out, for example, in a spruce reactor as described in DE-OS 24 27 045 or in any other reactor suitable for carrying out the process.

The following examples illustrate the invention but do not limit it in any way.

Example 1

A 2 L loop reactor was charged with 2.0 kg of 1.2 L of ethane and 4 g of anhydrous iron chloride. To this mixture was added 0.42 g of ammonia as a 0.67% (% by weight) solution in dichloromethane at a temperature of 3 ° ^{to -40} ° C. Ascending ^and part of the loop reactor comprises a layer of packed beads. Underneath this layer of packed bodies there are feed tubes to the reactor for ethylene, chlorine and air, through which about 60 l / ha of ethylene and 15 l / h of air are supplied. The reaction liquid is circulated in the mosquito reactor system while the mixed catalyst is uniformly suspended in the liquid phase. During the reaction, the reaction temperature in the reatone mixture is drowned at ca. to ⁷⁷ ° C. The treatment of the mixed catalyst dissolved in the liquid contained in the reactor, referred to as ferric chloride, was ^0.13 % after a few days.

In a water cooler located above the reactor, condensation of the vaporized chloroethane removed from the reactor is condensed, and then one portion of the condensate due to the amount produced is vented and removed by means of a portion of the condenser. while excess condensate is returned to the reaction zone. By means of a cooled charge, another part of the hydrogen chloride is separated from the waste gas, consisting mainly of inert gases. After several days of continuous operation, the mixed catalyst was substantially completely span in the reactor liquid and the colorimetric determination of the iron content of the reactor contained in the reactor indicated the iron chloride content. 0.13% wt. The amount of 1,2-dichloroethane produced per hour is 262 g. The process is carried out continuously for 14 days.

The aialysis of the product A formed in the condenser or of the liquid B contained in the reactor after the completion of the reaction gives the following value:

Product A (% C possible) Product B (% hImage) c ₂ H ₅ ci <0.002 <0.002 1,2-dichloroethane 99.94 99.82 1,1,2-trc chlo г editn 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 wt. The hourly amount of 1,2-dichloroethene is 326 g. The duration of the experiment is 8 days.

The analysis of the product A produced in the condenser and / or the liquid B contained in the reactor provides, after the reaction is completed, the following values:

Product A Product B

- (% w / w) (% w / w)

c ₂ H ₅ ci <0.002, <0.002 1'-dichloroethane 99.87 99.61 1,1,2-trichloroethane 0.10 0.34 HCl <0.001 - sjt <to: i 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 salt as well as 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 content of 1,1,2-tetraacetate and hydrogen chloride in the product formed in the capacitor.

Concentration FeCl3 (hmoSnostttf.). ratio FeClyN4 % ЬтоттШ 1,1,2-trichlsrgthjnu % 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 ^ 01

The amount of 1,2-dichloroethane produced per hour is 0.32% w / _w for the experiment with a ferric chloride concentration of 260 g and the duration of the experiment is 19 days.

The analysis of the product A produced in the condenser and / or the liquid B contained in the reactor gives 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-ictlsrθthao 99.93 99.78 1, 1, 2- ^ 1οΗ1ογοΏιβο 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 1,3 g of trimethylamine dissolved in 30 ml of 1,2-dichloroethane is used instead of ammonia. The solution is introduced into the reaction solution. The molar amount of 1,2-dichloroethane formed per hour is 276 g and the duration of the experiment is 6 days. Furthermore, the colorimetrically determined content of selesium 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 (% hootnootic)

c ₂ H ₅ ci - 1,2-dictlsrettjo 99.86 1,1,2-Trichloroethane 0.13 HCl 0.01 other 0.006

Example 5.

The procedure is analogous to that of Example 4, except that 1.7 g of iron chloride and 0.65 g of diaminoethane are added as catalyst to the reaction solution. The average iron chloride content of the solution was found to be 0.07% by weight on average. 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 gives the following value:

Product A (% ^ о ^ сю ^ т)

CgH ₅ Cl - 1,2-dichloroethane 99.13 1,1,2-trichloroethane 0.85 HCl 0.02 other 0.01

Example 6

The procedure is analogous to Example 1, but using 1.5 kg of 1,2-dichloroethane and an addition of 1.5 kg. 3.3 g of ferric chloride and 3.0 g of triethanolamine. The colorimetrically determined iron chloride content in the reaction solution was 0.25% tomoirot on average. Though 268 g of dichloroethham are obtained and the experiment lasts for more than 6 days.

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

Product A (% WNo)

c ₂ H ₅ or 1'-dichloroethane <0.002 99.65 1,2,2-tricloroethane 0.33 HCl 0.007 other 0.01

Example 7

(a) Into a 2-liter round-bottomed flask equipped with a stirrer, a dropping funnel and a reflux condenser, add 2 kg of 1,2-dichloroethane and 2,1 g of ferric 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 to the total catalyst volume of 2.3 g. The mixture was then refluxed for an additional 5 hours and then colorimetrically determined. the ferric chloride content of the solution being 0.11% by weight.

b) The mixture of dichloroethane and catalyst is then charged to the styrene reactor described in Example 1, and then about 60 L / h of chlorine and ethylene are fed together with about 5 L / h of air into the reactor. 273 g of dichloroethane are obtained hourly and the experiment lasts for days.

The analysis of product A obtained in the condenser yields the following values:

Product A (% Moisture)

c ₂ H ₅ ci <0.002 1,2-dichloroethane 99.51 1,1,2-trichloroethane 0.48 HCl 0,002 other 0.009

Example 8

a) First, the procedure is analogous to that of Example 7a), however, while stirring 1.5 kg of 1.2 L of 110 L with 10 g of iron chloride are heated to boiling. 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.

(b) In order to produce 1,2-dichloroethane, 4 g of the catalyst prepared in (a) and 2 g of iron (II) chloride are suspended in 2.7 kg of 1,2-dichloroethane and, after the volume has been concentrated, to a volume of about 2 liters of the mixture is introduced into a spruce reactor as described in Example 1. 60 liters of chlorine and ethylene and 15 liters of air are introduced per hour in a loop reactor and the reaction is started in a manner and under reaction conditions which are in Example 1. 266 g of 1,2-dictloroethane are obtained and the experiment lasts 6 days. The content of ferric chloride, which was measured colorimetrically in the reaction solution, was 0.15% on average.

Ί

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

Product B (% w / w)

Product A (% by weight)

c ₂ H ₅ ci 0.004 0.006 1,2-dichloroethane 99.93 99.74 1,1,2ltгithtorethal 0.06 0.23 4 H01 0,002 0.03 other 0.003 l

Example 9

In the reactor for the 1,2-dichloroethane technical production, corrosion testing samples are placed at four locations in the reactor and subjected to the process conditions of the invention. After 20 days, samples were taken from the reactor to detect corrosion damage. When using the catalyst according to the invention. A mixture of ferric chloride and. ammonia and observing the actual temperature is ^{00 i} I 11 ⁰ C ^or N ^with the average growth knrose ^p en for unalloyed steel of less than 0.05 mm per one year. If, on the other hand, the process is carried out in any way exclusively using ferric chloride as the catalyst, the average degree of corrosion for the non-alloy steel is 0.43 mm per year.

Claims (1)

SUBJECT . OF THE INVENTION Mixed catalyst consisting of anhydrous ferric chloride and one other constituent of the mixture for the production of 1,2. chlorine in a solvent at atmospheric or elevated pressure, characterized in that the other component of the mixture is an equivalent amount of ammonia, primary, secondary or tertiary alkylamine, aralkylamine, arylamine or alicyclic amine or polyamines or a halogenated salt of this nitrogenous base, in particular ammonium chloride on the torturous ferric chloride.