JPS5920233A - Manufacture of 1,2-dichloroethane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 1.2~Dichloroethane is an industrial Okawa product, which is mainly thermally decomposed to backtrack vinyl chloride. 1.2-Dichloroethane is obtained primarily by direct addition of chlorine to ethylene in the presence of a catalytic amount of a Lewis acid, usually iron chloride ([l)]. The reaction is carried out both in the gas phase and also in the liquid phase, which is usually predominantly 1,2-dichloroethane, with liquid phase reactions generally being preferred.

Since hydrogen chloride is produced during the thermal decomposition of 1.2-dichloroethane to vinyl chloride, for its reuse, besides the direct chlorination of ethylene, ethylene and oxygen or Reactions with air and hydrogen chloride are also carried out. This reaction is referred to as oxychlorination of ethylene. In this second reactor, there is typically a “polymerization grade”.
Ethylene supplied as ' is used. Of course, it is also possible to use ethylene that is not very pure.

The catalytic production of acetaldehyde from ethylene and oxygen results in waste that is often not subsequently used due to contamination and is incinerated.

The object of the present invention is to provide a method for the catalytic production of acetaldehyde from ethylene and oxygen (e.g.
183 specification 1)) is an economical and environmentally friendly use of the waste gas. In this case, it is known to incinerate the waste gas from the degassing of the reaction and intermediate storage of the crude acetaldehyde. However, due to the high ethylene gold layer in the waste gas, it is desirable to utilize the waste gas to increase the economics of the process. Such utilization is covered by West German Patent No. 1148536.
No. 1154450 and No. 1156.159
It is described in the specification of No. 5. According to DE 1148 566 and DE 1154 450, a post-reaction of the ethylene-containing waste gas into acetaldehyde is carried out;
According to Hoso 4T, ethylene is isolated from waste gas. Both methods are expensive in terms of investment and energy.

By the way, a method has been discovered that is capable of removing ethylene-containing waste gas from an acetaldehyde production plant at a small cost. arises due to the need to discharge the charged inert gas and the by-products formed, and ethylene 58-70
Contains 111*%. Other waste gases, preferably arising from storage of crude acetaldehyde, may also be included. It is a gas dissolved under pressure in the wash water during aldehyde production, which is released during almost pressure-free storage of the crude aldehyde, and which has a c2H4 content of 50-60% by weight.
) gives waste gas.

The reaction of ethylene with hydrogen chloride and oxygen or air or oxygen-enriched air (oxychlorination) is carried out by known methods at 180-650°G, preferably at 200-200°G.
It is carried out at 50° C. in the presence of a copper-containing catalyst which may additionally contain alkali gold-streaked chloride.

Copper in the form of copper salts and optionally alkali metal chlorides are preferably adsorbed on inert, finely divided materials, such as aluminum oxide. The catalyst particles can be stacked in a so-called fixed bed or in fluidized form in the reaction chamber (see German Patent Application No. 1518930, German Patent Application No. 1518931, German Patent Application No. 1518932, West German Patent Application No. No. 262<5133, West German Patent No. 271'8878, West German Patent No. 274240
No. 9 Specification 11, European Patent No. 0005176 Specification lJ).

In detail, the present invention has a temperature of 200 to 25,000 and a pressure of 1
．． Ethylene is oxychlorinated with hydrogen chloride and oxygen or air at 7 to 5 bar in the presence of a catalyst containing copper chloride (■) on a carrier and optionally with the addition of nitrogen, at 1°2 - by condensing off the dichloroethane from the reaction gas and, in the case of oxygen, returning the residual gas mainly by circulation to the oxychlorination zone;
．． A process for producing 2-dichloroethane, the process comprising using at least a portion of the ethylene in the form of an ethylene-containing waste gas obtained from a catalytic process for producing acetaldehyde from ethyl chloride and oxygen.

Furthermore, the following advantageous embodiments of the invention may be mentioned: a) using the reaction waste gas from the reaction part of the contact process for producing acetaldehyde as the ethylene-containing waste gas; b) using crude as the ethylene-containing waste gas using the stored waste gas from the degassing of an intermediate storage of acetaldehyde: C) the reaction waste gas from the reaction part of the catalytic process for producing acetaldehyde as ethylene-containing waste gas and the degassing of the intermediate storage of crude acetaldehyde; Use a mixture of stored gases: d) Composition with the following width: Argon 11-18% Oxygen 6.5-5% Nitrogen 2-9% Carbon dioxide 10-22% Ethylene
Using an ethylene-containing waste gas having an excellent pressure of 57 to 70: θ) Contact method for producing acetaldehyde The ethylene-containing waste gas is compressed to a pressure of 1.7 to 1.7 in an oxychlorination system.
Pressure is increased to 1 to 4 bar above 5 bar, dried and fed to the oxychlorination system.

The process according to the invention allows an economical use of ethylene-based waste gases from the production of acetaldehyde and from storage vessels utilized in the purification of acetaldehyde. Another advantage is that the waste gas from the catalytic reaction of ethylene and oxygen to acetaldehyde does not need to undergo any other treatment except drying and compression, and can be directly combined with other gases into the oxychlorination reaction. It can be loaded into a container. Variations in the aldehyde treatment conditions do not affect the quality or yield of the 1,2-dichloroethane produced.

Below, j! of acetaldehyde (Figure 1) and 1゜2-dichloroethane (Figure 2). ! ! The method of the present invention will be explained based on the flow sheet of the production equipment: aqueous/hydrochloric acid catalyst solution (
For example, Ou(J 210 ucJ,.

Oxygen via conduit 2 into a reactor 1 filled with PdCj2) and under a pressure of, for example, 4.5 bar.

and a mixture of fresh ethylene or recycle gas (composition see below) is introduced via conduit 3, which is conducted by °C conduits 4 and 5. At that time, the molar ratio of ethylene to oxygen is 2:
It is 1. In reactor 1, ethylene and oxygen react at 130°C to form acetaldehyde. Ethylene undergoes 65 to 40 reactions during each pass, with a selectivity of 95% to acetaldehyde. The remaining 5% is divided into 6 by-products and 2 CI) as waste gas pressure loss. The pressure in the system is maintained by adding fresh ethylene through conduit 4. The addition of oxygen is controlled by the concentration of oxygen in the circulating gas, which must be below 9 liters.

The gaseous reaction mixture is separated in a fog collector 6 from the catalyst liquid which is returned to the reactor via conduits T and 3 and passed to a cooler 8 where most of the heat of reaction is removed and the water vapor is removed. Condense approximately 1/2.

Hot condensate at 110° C. is fed to reactor 1 using pump 9. The gas leaving the cooler 8, still hot, with all the acetaldehyde passes through another cooler 10, where most of the acetaldehyde is condensed with water. Approximately 25°C
The gas leaves this cooler 10 and flows from below into a cleaning tower 11 filled with packing bodies, where residual acetaldehyde is washed out. Circulating gas is compressed (water seal pump 1)
2) is returned to reactor 1 via conduits 5 and 3.

It has the following composition: Argon 12
~18, oxygen 4-5, nitrogen 2-8, carbon dioxide 10-2
0, ethi 1/in 58-70. (-Others (methane, ethane, methylene chloride, ethylene chloride) 0.2 to 1.45°) To keep the ethylene concentration in the circulating gas constant and to avoid an increase in the concentration of inert gas, This so-called reactor gas from which a quantity of gas has to be taken off has the same composition as the recycle gas and is brought to pressure by means of a compressor 13-.

The crude acetaldehyde leaving the cooler 10 and the washing tower 11 via a common line 14 is intermediately stored in a crude aldehyde container 15 . This contains dissolved cycle gas, which is mostly generated under 1.5 par during storage of the crude aldehyde. After passing through a cleaning liquid 16 to remove the acetaldehyde, this so-called stored waste gas has the following composition (heavy fill:%): argon 2-6,
Oxygen 0.5-1.5, Nitrogen 6-20, Carbon dioxide 25-
35, Ethane 150-60, Others (methane, ethane,
Methylene chloride, ethylene chloride) 11 to 2.65° is compressed in a compressor 17 to a C pressure cuff bar, and combined with the compressed reactor gas in 13. Reactor gas and storage R
The waste gas is mixed in a ratio of approximately (7-8)=1, so that the lateral composition of the waste gas dI compound does not differ significantly from that of the reactor gas.

The waste gas mixture still retains some moisture up to 12°C, corresponding to the vapor pressure of water, and for this purpose the waste gas mixture is passed through drying 18 and then heated with about 11 to 18 parts of argon and about 18 parts of oxygen. 6.5-5 width, nitrogen 2-9q6, carbon dioxide 10-2
Section 2, those with a composition of 57 to 70% ethylene and 0.2 to 1.8% of others (methane, ethane, methylene chloride, ethylene chloride) (heavy penalty section) go through conduit 19 to produce 1,2-dichloroethane. Sudame's oxychlorination device (
Figure 2) Enter K.

The waste gas mixture from line 19 and hydrogen chloride from line 20 are fed into line 21 for fresh ethylene and together with the lower part of the oxychlorination reactor 22, where ethylene, hydrogen chloride and , and oxygen to 200~2
The reaction is carried out in the presence of flowing catalyst particles at 50'O and 1.7-5 bar. The catalyst is e.g. A as a carrier.
0u (J2 and K (J) on l2O3. The gas mixture leaving the reactor 22 is approximately
°OK Cool down. The cooled gas mixture is further cooled to 10° C. in a water cooler 25 and in a brine cooler 26, with the crude 1° 2-dichloroethane and water condensing and reaching the collection vessel 27; Separation into two phases takes place here.

The uncondensed gas is returned to the reactor 22 as a circulating gas via the compressor 28 and the four pipes 29. This cycle gas consists of nitrogen, carbon dioxide, carbon oxide, oxygen and a small amount of carbon dioxide.
, 2-dichloroethane and ethylene. The circulating gas is supplied with fresh oxygen via conduit 30. In addition, nitrogen is added to the circulating gas through conduit 31 in order to keep the concentration above combustible constant. Already before the compressor 28, the C and ethane/C added through the constant pressure maintenance of the reactor are added.
A portion of the circulating gas corresponding to the combustion to O and CO2 is continuously removed, the 1.2-dichloroethane is separated off in a 1.2-dichloroethane recovery device 32 and sent to incineration.

The aqueous phase above the collection container 27 is passed through the conduit 24 to the cooling tower 2.
Return to 3. An alkaline solution is introduced into this aqueous phase from conduit 33 through conduit 2.
Add to 4. The reaction water, which is newly formed in each case during the oxychlorination of ethylene, is taken off at the bottom of the cooling tower 23 via 28'f34. Since the reaction water has been converted to lλ with 1,2-dichloroethane/
1,7-5 bar) to a temperature above 160'O in column 35, the escaping water vapor and 1°2-dichloroethane are sent via conduit 36 to condenser 24+C, and 1,
The water from which 2-dichloroethane and ethylene were separated is sent to column 3.
5 into the flow channel.

The inert gas and by-products introduced through line 19 together with the aldehyde exhaust gas leave the oxychlorination reactor 22 almost unaffected and without any adverse effect on the oxychlorination. Exemplary ethylene and ethylene from the acetaldehyde treatment waste gas react to 1,2-dichloroethane with the same conversion vehicle and the same yield. The amount of nitrogen added through conduit 31 varies depending on the amount of inert gas already contained in the acetaldehyde waste gas. With this method, the loss of ethylene and 1,2-dichloroethane remains constant in the oxychlorination waste gas discharged from 62 to the combustion, irrespective of whether acetaldehyde waste gas is used from line 19 or not. isn't it.

Example 1 Process as described with respect to FIGS. 1 and 2. Compressor 13 supplies 450kl of reactor gas with the following composition (weight: 11%)? /h is compressed: Ar: 15.
45.02: 4.78, N2: 3.0.

Do2: 12.77.02H4163,33,OH,
:0.02C2H6: 0.1.0)13C2:0.4
5.02H5C1: o, i 0 The compressor 17 compresses 59 ky/h of stored waste with the following composition: Ar: 3.63.02: 0.97: l'2
: 6-95.002: 31.9, C2H4: 5
4.55, OH,: 0.005.02H6: 0.07
5.0H3CJ: 1.53, C2H3CJ: 0
．． 39° The following composition (weight i%): Ar: 14.08.02:4.
64, N2: 3-46.002: 14@98%
02H4'62.32, OH4: 0.02, C2H
6: 0.1, CHsCJ-: 0.57.02H5c
J: a mixture of waste gases with 0.13 (509
kl? /h) is fed to the oxychlorination device via conduit 19.

The reaction in reactor 22 takes place at 4 bar and 23°C. The amounts of fresh ethylene, hydrogen chloride, oxygen, and chamber additions as well as conversion rates and yields are listed in the following table. The highly dilute alkaline liquid injected from conduit 24 into cooling tower 23 is aqueous caustic soda at 60°C.

EXAMPLE 2 (COMPARATIVE EXAMPLE) The process is carried out as in Example 1, but no waste gas is supplied through conduit 19. Same as Example 1 C2) 14:HCJ,'
:C2 molar ratio of 1:1.92:0.63, the amount of hydrogen chloride and the amount of acid accumulated are reduced accordingly. Details are clear from the table.

Example 6 The oxychlorination of ethylene is carried out analogously to Example 1, but the oxygen is used in the form of air and is not introduced into circulation, but the reactor is treated on the one-pass principle. Ethylene losses are higher than in the circulation process since the amount of waste gas is significant due to the high nitrogen content of the air. Details are listed in the table.

Example 4 (comparative example) The procedure is as in Example 6, but no waste gas is supplied via conduit 19. Same as example 3, 02H4:HC,L:02
In order to maintain the molar ratio of = 1: 1.89: 0.86, the amount of hydrogen chloride and the amount of air are reduced accordingly.

Details are listed in the table.

Comparison of Examples 1 and 2 and Examples 3 and 4 shows that 8.45 = 1 of 1,2-dichloroethane is formed according to the invention, since the ethylene-containing waste of the acetaldehyde operation is This is because there is no need to additionally supply the gas as an ethylene source to the oxychlorination plant and to combust it for expensive post-treatment or environmental burden as in the past.

[Brief explanation of drawings]

Figure 1 shows the flow sheet of the acetaldehyde equipment,
and! Figure g2 shows a flow sheet truss for producing 1,2-dichloroethane. 1... Reactor, 8.10... Cooler, 13.17.
... Compressor, 18... Drying, 19... Conduit, 22.
・・Oxychlorination reactor

Claims (1)

Claims: 1. Ethylene is converted to hydrogen chloride and oxygen in the presence of a catalyst containing copper chloride on a carrier at a temperature of 200-250° C. and a pressure of 1.7-5 par, and optionally with the addition of nitrogen. Alternatively, oxychlorination with air can be carried out, with 1,2-dichloroethane being condensed and separated from the reaction gas. and in the case of using oxygen, the residual gas is mainly recycled back to the oxychlorination zone to produce 1,2-dichloroethane. A process for producing 1,2-dichloroethane, characterized in that it is used in the form of an ethylene-containing waste gas obtained from a conventional process. 2. Using the reaction section gas from the reaction section of the catalytic process for producing 7cetaldehyde as ethylene-containing waste gas, especially i! '1; Scope of request The method described in item 1. 6. Use the stored waste gas from the degassing of the U411 acetaldehyde intermediate storage as waste gas containing ethylene.1-
The method according to claim 1, wherein the method comprises: 4. Claims characterized by a mixture of the reaction part gas of the contact process for producing acetaldehyde' as ethylene-containing local gas and the storage gas j)) from the degassing of an intermediate storage of crude acetaldehyde The method described in item 1. 5. Composition of the following weight 1fiqb: Argon, 11-18% oxygen, 6.5-5% nitrogen, 2-9% carbon monoxide, 10-22% ethylene
57-70% Others (methane, ethane, methylene chloride, ethylene chloride) with a ratio of 0.2-1.8% ff'f B? Range 1st to 4th term of l search
Which of the following terms is 1? 411 This method. The ebrene-containing waste gas from the catalytic process for producing 6,7 acetaldihyde is compressed to a pressure of 1 to 4 bar above the pressure of 1.7 to 5 bar in the oxychlorination system, dried and The method according to any one of claims 1 to 5, wherein the method is supplied to a machine yarn.