JPS61180730A - Method for purifying 1,2-dichloroethane - Google Patents

Abstract

PURPOSE:To remove industrially and advantageously chlorine in liquid 1,2- dichloroethane, by introducing a specific amount of ethylene into the 1,2- dichloroethane containing the chlorine, and catalytically reacting them in the presence of a catalyst supporting a specified amount of a metal chloride on a porous carrier under specific conditions. CONSTITUTION:>=2mol, particularly 3-10mol, based on 1mol chlorine, ethylene 2 is introduced into liquid 1,2-dichloroethane 1 containing the chlorine, and catalytically reacted at 40-160 deg.C, particularly 40-120 deg.C and 10-500hr<-1>, particularly 10-200hr<-1> space velocity in the presence of a catalyst supporting <=0.5wt%, preferably 0.1-0.5wt%, particularly 0.1-0.3wt% metal chloride, particularly ferric chloride or cupric chloride on a porous carrier, particularly active carbon or alumina in a reactor (A) to remove the chlorine corroding equipment, and causing abnormal reaction in the above-mentioned liquid 1 industrially and advantageously as compared with the conventional method. The resultant treated solution 3 can be directly fed to the thermal decomposition step.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] Invention II'i Liquid containing chlorine 7. The present invention relates to a method for substantially removing chlorine from colichloroethane.

[Conventional technology]

In recent years, attention has been paid to the reaction of ethylene and chlorine in a reaction medium containing 8-dichloroethane as a main component in the presence of a metal chloride catalyst such as iron chloride from a point of 60~/≦O@cO. In this high-temperature method, the reaction product, dichlorothane, is removed from the reactor as steam by the heat of reaction between ethylene and chlorine.
In that case, the reaction zone can be effectively cooled by the latent heat of vaporization of 8-1 dichloroethane, so a special reaction zone cooling means is used to directly direct the vapor of 8-1 dichloroethane to purify 8-1 dichloroethane. If it is supplied to a rectification column for distillation, the heat source of the rectification column can be saved.

[Problem that the invention seeks to solve]

In the above-mentioned high temperature method, most of the chlorine reacts with ethylene and is converted to 8-1 dichloroethane, but a trace amount of chlorine is carried out from the reactor and distillation column with the evaporated 1,-1 dichloroethane Kfifl. It is contained in the 2-dichloroethane liquid.

7. If chlorine is contained in the 2-dichloroethane solution, it will corrode downstream equipment, such as transportation piping and tanks. Special K: If water coexists in the 2-dichloroethane solution, corrosion will occur significantly, and iron will be eluted into the dichloroethane solution. This iron dissolved/, Kodichloroethane 7. When using codichloroethane in a pyrolysis furnace, coking is promoted and 7
．． This causes an abnormal reaction of 2-dichloroethane. Therefore, it is desired that the cordichloroethane used in the J-dichloroethane thermal decomposition furnace contains as little iron as possible dissolved, that is, it is chlorine-free 1,1-dichloroethane.

Conventionally, various methods for removing chlorine from 7,2-dichloroethane have been proposed. For example, 1,2 containing chlorine
- There is a known method of removing chlorine by washing dichloroethane with alkaline water, but this method requires steps such as washing with water and dehydration), which not only increases equipment costs but also causes loss due to the alkali dissolution. It has its drawbacks. Also,
It is also known to remove chlorine in 1,2-dichloroethane by adsorbing it to a porous adsorbent such as activated carbon, Moleculer Sheep, or activated aluminum, but this method does not have sufficient adsorption capacity and requires a large amount of This method requires a large amount of adsorbent and further has problems such as the need to shorten the regeneration cycle of the adsorbent.

[Means for deciding issues]

The present inventors have conducted intensive studies on a method for improving the above-mentioned drawbacks of the conventional method and removing chlorine from liquid λ-dichloroethane. The present invention was completed by discovering that chlorine can be substantially removed.

That is, an object of the present invention is to provide an industrially advantageous method for reducing chlorine in liquid 1,2-dichloroethane containing chlorine.

Such an object of the present invention is to obtain a chlorine-containing liquid 1,-2-
To dichloroethane, 1 mole of chlorine in liquid 1,-dichloroethane, 2 moles or more of ethylene is introduced, and this is heated at a temperature of 41Q~/150°C and 10-joohr-
” at the opening speed of O・-!
This can be easily achieved by a method for purifying cordichloroethane, which is characterized by carrying out a catalytic reaction with a catalyst supported in an amount of less than i% by weight.

The present invention will be explained in more detail below.

In the method of the present invention, the liquid containing chlorine/J-dichloroethane is generally obtained by reacting ethylene and chlorine in the presence of a metal chloride catalyst. ethylene and chlorine in the presence of a metal chloride catalyst in a reaction medium based on liquid 1,2-dichloroethane, in particular /, λ-dichloroethane containing ≦Ow
1. Perform a liquid phase reaction at a reaction temperature of 160°C. - When producing monodichloroethane, liquid /J-dichloroethane containing trace amounts of chlorine obtained by evaporating the reaction medium with the heat of reaction, and impurities in 1,-dichloro, such as butadiene, chlorobunn, trichloride, etc. In order to increase the boiling point of ethane etc., liquid 1,2-dichloroethane containing a trace amount of chlorine obtained by chlorinating the recovered J-dichloroethane can be used.

The amount of chlorine contained in the above liquid/2-dichloroethane varies somewhat depending on its origin, but is usually 7,000 chlorine.
ppm or less, especially K/0-2.000 ppm.

Among the objects to be treated by the method of the present invention, the above ethylene and chlorine are subjected to a liquid phase reaction at high temperature. - A method for creating monodichloroethane (hereinafter referred to as high temperature method) will be described in further detail.

The high temperature method described above involves continuously feeding ethylene and chlorine into a reaction medium containing 1,1 dichloroethane as a main component containing an effective amount of a metal chloride catalyst, and at a reaction temperature of 60 to 6θ℃. This is done by carrying out a liquid phase reaction. At that time, it is preferable to add an effective amount of a side reaction inhibitor such as benzene, cresol, phenol, or other aromatic 8-group hydrocarbon, or fIR element to the liquid phase of the reaction medium.

Examples of metal chloride catalysts to be present in the reaction medium include ferric chloride, aluminum chloride, antimony chloride, copper chloride, etc., and the amount used is usually / / as the catalyst concentration in the liquid phase of the reaction zone. θ~≦00Oppm, especially 30~
A range of 2.000 ppm (by weight) is practical.

In addition, the supply ratio of ethylene and chlorine is usually O6 in molar ratio.
The blowing rate of ethylene and chlorine gas into the reactor is usually in the range of 9 to 3, preferably 80 to 10, and the superficial gas velocity of the reactor is usually 0 to 400, respectively.
0 m/hr 1 preferably j 00 ” to 000
m/hr range.

Further, the reaction temperature is a temperature at which at least the upper liquid level layer of the reaction medium boils under the pressure inside the reactor, and the temperature is usually 60~/≦oC, preferably 20~/! It is in the range of I°C. If the reaction temperature is difficult to control and is higher than 160°C, the amount of by-products such as 1,1,2-)dichloroethane increases significantly, and the chlorine supply pressure needs to be increased, making it impractical. Not.

The advantage is that the reaction zone can be effectively cooled by the latent heat of vaporization of the reaction medium, and no special cooling means are required for cooling the reaction zone. In this high-temperature method, if the reaction product, dichloroethane, is supplied to the cordichloroethane rectification column using all or part of the steam at the top of the reactor, the reaction heat produced can be used as a heat source for rectification. It can be used as a chemical, which is extremely advantageous industrially.

In the above-mentioned high-temperature process, it flows out from the top of the reactor /, J-
Dichloroethane vapor or 'obtained by supplying the vapor to a 1,1 dichloroemene rectification column and distilling it for purification/1.2
- Contains chlorine usually 9000 ppm or less, preferably 70 to 2000 ppm, such as dichloroethane/2
-dichloroethane is preferably treated by the method of the invention.

In the method of the present invention, a specific amount of ethylene is introduced into the liquid dichloroethane containing a trace amount of chlorine as described above, and this is brought into contact with a catalyst having a specific amount of metal chloride supported on a porous carrier under specific conditions. React to remove chlorine.

In the method of the present invention, the amount of the chlorine-containing liquid is directly above 1 mole of chlorine contained, preferably 3 to 10
This is the range of Gumoru. If the amount of ethylene introduced is less than 2 moles per mole of chlorine, the removal reaction will be insufficient and chlorine will remain in the liquid dichloroethane, which is not preferred. The ethylene used is preferably high-purity ethylene, but may contain inert impurities such as methane, ethane, carbon oxide, and nitrogen.

In the method of the present invention, a specific amount of metal chloride supported on a porous carrier is used as a catalyst.

As the metal chloride, ferric chloride, cupric chloride, aluminum chloride, antimony chloride, etc. are used, but I#I
/c ferric chloride and cupric chloride are preferred. In addition, the porous carrier may include activated carbon, silica, silica-alumina,
Two sieves, alumina, etc. are used, and activated carbon and alumina are particularly preferred.

The metal chloride can be supported on the above-mentioned porous carrier by a commonly used method such as the soaking method, the evaporation drying method, or the IIJT fog drying method. The above-mentioned porous carrier is immersed in a solvent, and after being left for day and night, it is heated to a temperature of 100~- in a pixel air stream.
A method such as drying at 0° C. is used. The amount of metal chloride supported is 0.5% by weight or less, preferably 0.1 to 0.1% by weight. !
The weight is smooth, preferably 0. /~0.3 weight range. When the supported amount of the metal chloride exceeds o, z x t %, a part of the gold FiI4 chloride becomes liquid /
- It is not preferable because it requires an operation to dissolve the eluted metal chloride in dichloroethane and convert it into a liquid state from the dichloroethane.

In the method of the present invention, for example, a required amount of ethylene is introduced into liquid 1, cordichloroethane containing chlorine, and 0.1% by weight or less of a metal chloride is supported on a porous carrier under specific conditions. The catalytic reaction is carried out by passing the catalyst in a downward flow or in a downward flow through a packed bed filled with a catalyst. It is preferable to allow liquid 2-dichloroethane to pass through the catalyst packed bed in a downward flow since flow of the catalyst can be prevented.

The contact reaction conditions for liquid/J-dichloroethane and the above catalyst include a reaction temperature of 4 to/≦θ°C, preferably 4 to/≦θ°C.
It is in the range of 0°C to / 0°C. The pressure may be a pressure that maintains 1,2-dichloroethane in a liquid state,
Usually above normal pressure, preferably from normal pressure to 10 kg/cr/l
is within the range of In addition, the space velocity of the liquid (hereinafter referred to as BV) is 10 to 700 hr-', preferably 10A
- The range is 00hr-1, the residence time is 7-360
Second, it is necessary to increase the amount of the preferred medium charged, and it is also necessary to cool the liquid/0.2-dichloroethane with a special cooling device, which is not industrially practical.

In addition, when the temperature is higher than 740°C, the production amount of KFi/, due to the chlorination of Kodichloroethane/, /, 2-) Lichloroethane increases.1. - Undesirable loss of monodichloroethane and the need to increase the pressure to keep it below the boiling point. Furthermore, if the space velocity is less than / Ohr, the device becomes very large, which makes it unsuitable for industrial use, and j0
If θhr-' is larger than θhr-', the reaction will not be completed sufficiently and chlorine will remain, which is not preferable.

When the liquid 1,1-dichloroethane containing chlorine and ethylene is passed through the packed bed filled with the catalyst and subjected to a contact reaction, the chlorine in the liquid 2-dichloroethane is removed.

[For production]

In the method of the present invention, ethylene is introduced into liquid 7,2-dichloroethane containing chlorine and brought into contact with a metal chloride-supported catalyst under specific conditions. - It is presumed that the chlorine in 1,1-dichloroethane is substantially removed.

[Example 71911] Next, the embodiments of the present invention will be explained in more detail through implementation and comparison, but the present invention is not limited to the following examples as long as they do not exceed the gist thereof.

The reaction was carried out according to the reaction flow shown in FIG. 7 of Example f11. First, after dissolving anhydrous ferric chloride in 7,2-dichloroethane, activated carbon was immersed in the solution and evaporated to dryness, thereby supporting ferric chloride on the activated carbon. A catalyst was produced. This catalyst? 00Bg is the inner diameter! 3. ! ■ φ, length tool 8 UBJ/4 m Reactor (A) tc packed (packed bed height u03). Conduit (1) has a chlorine content of 3! ppm by weight liquid 1. - 1 dichloroethane (xna) was supplied at a flow rate of /00 Ic9/hr, and diethylene was supplied through conduit (2) at a flow rate of /Mφr to dissolve ethylene in 1,1 dichloroethane, which was then subjected to the above reaction. 6(A)
K supply, temperature to °C, pressure j kg/ct/l
A contact reaction was carried out with a catalyst under the conditions of 100 G and a space velocity of 00 hr". The reaction results obtained are shown in Table 1.

Examples Co-da and Comparative Example 7-Ko Gold JIE [Products were carried out in the same manner as in Example 99/, except that the type and amount of the compound supported and the type of porous carrier were changed as shown in Table 1. The results are shown in Table 1.

Comparison 9 $3 The same procedure as Run 91/ was carried out except that the reactor (5) was not charged with any catalyst. The results are shown in Table 1.

〔Effect of the invention〕

According to the method of the present invention, by introducing ethylene into liquid 1,2-dichloroethane containing chlorine and causing a contact reaction with a metal chloride supported catalyst under specific conditions, liquid
- Since chlorine in dichloroethane can be substantially removed, it is industrially advantageous compared to conventional methods. Furthermore, since the method of the present invention does not use a soluble catalyst, the treated liquid does not need to be subjected to catalyst removal operations (e.g., washing with water, distillation, etc.), and can be fed as is to the thermal decomposition process of 8-dichloroethane. can. Therefore, from this point as well, the present invention has great industrial significance.

[Brief explanation of drawings]

Claims (1)

[Claims] (1) To liquid 1,2-dichloroethane containing chlorine, 2 moles or more of ethylene is introduced per 1 mole of chlorine in the liquid 1,2-dichloroethane, and the mixture is heated at 40 to 160°C.
1. A method for purifying 1,2-dichloroethane, which comprises carrying out a catalytic reaction with a catalyst having 0.5% by weight or less of a metal chloride supported on a porous carrier at a temperature of 10 to 500 hr^-^1 and a space velocity of 10 to 500 hr^-^1.