SU368737A1 - Method of producing 1,1,2,2-tetrachloroethane - Google Patents

Description

one

The invention relates to a method for producing 1,1,2,2-tetrachloroethane.

It is known to obtain 1,1,2,2-tetrachloroethane by the oxidative chlorination of cis and / or granc-dichloroethylene in the presence of a fluidized bed of catalyst — supported metal chlorides. However, side reactions, for example, dehydrochloro-irovan reactions, lead to the formation of chlorine derivatives of unsaturated C2 compounds.

To reduce the formation of side chlorine derivatives, the reagents are diluted with hydrogen chloride.

The disadvantage of this method is an increase in the volume of the reaction mass and the presence of a complex system for the separation of gases.

In order to reduce the formation of by-products, it is proposed to carry out the process in the presence of a catalyst on a carrier, the specific temperature of which is 10-200, with a molar ratio of HC1: {cis - CHSINS-f trans CHC1 CHC) equal to 0.8-2, and (i (wc-CHCl CHCl -b + t / ans-CHC1 CHa), equal to 0.2-0.6.

Preferably, cis- and / or trans-dichloroethylene are fed into the reaction zone at a rate of 0.5-20 mol / l-l of catalyst.

Usually, dichloroethylene is fed into the reaction zone in a mixture with tetra.chloroethane at a molar ratio of less than 2. The process is most often carried out at a temperature of 200-360 ° C and a pressure of 1 - 10 bar.

As a catalyst carrier, it is better to use attapulgite with a specific surface of 10-160 or a mixture of silica gel with MgO with a specific surface of 40-200.

The process can use a supported catalyst with a specific surface area of more than 1.

The oxidative chlorination reaction is carried out up to 70% conversion of cis and / or transdichlorethylene. Unreacted dichloroethylene is recycled after separation from other reaction products.

100% conversion of dichloroethylene is achieved by increasing the reaction temperature.

and / or an increase in the residence time of the reactants in the catalytic zone, which leads to a decrease in the selectivity of the process, the formation of various chlorinated ethylene compounds and combustion products, and / or a decrease in productivity.

Cis- and / or gran-dichloroethylene, hydrogen chloride and molecular gas

oxygen is passed at 200-360 ° C, preferably at a temperature of 280 ° C, through a fluidized catalyst zone. Conversion of raw materials 70%, preferably 40%. From the effluent, 1,1,2,2-tetrachloroethane formed is separated, at least in part, and unreacted cis- and / or trans-dichloroethylene, returned to the reaction.

The particle size of the carrier is 10-900 lcd, average specific surface area is -1, preferably 10. The average particle size of the carrier is 20-400 microns, preferably 40-120 microns.

The carrier is one or more substances selected from the group consisting of alumina, magnesia, graphite, activated carbon, aluminosilicates, preferably clays and silica.

The catalyst may contain one of the elements selected from the group consisting of alkali and alkaline earth metals, bismuth, cadmium, chromium, cobalt, copper, tin iron, magnesium, manganese, nickel, platinum, rare earth elements, thorium, vanadium, zirconium.

Example 1. Oxidative chlorination reaction of a mixture of cis- and g / 7ax-dichloroethylene, containing 62 mol. % g ys-isomsra and 38 mol. The% granule isomer is carried out in a glass reactor (bh 65 mm, h 1000 mm) with external heating (electrical resistance).

The lower part of the reactor is an inverted cone filled with 2 mm glass beads. The height of the catalytic bed at rest after fluidization is 450 mm.

To prepare the catalyst, clay of the type of attapulgite is sprayed with an aqueous solution of two-water copper chloride and potassium chloride to a final content of 6.7 and 4.9 wt. % respectively of copper and potassium cations in the dry catalyst. The average specific surface area of the carrier, which has been in operation for 100 hours, is BO. The particle size of the catalyst is 100-315 microns, 50% of these particles have a size; 210 microns.

At the bottom of the inverted cone at a pressure of 1.05 bar, 2.37 mol / hour-l of cis- and t / 5ns-dichloroethylene, catalyst, air, gaseous hydrogen chloride are fed and heated to the temperature of the catalytic layer 315 + 0.2 ° C. The molar ratio of hydrogen chloride: (g {is-dichloroethylene + trans - dichloroethylene) is 1.35, and oxygen: (1 {y-dichlorethylene + grand-dichloroethylene) is 0.37. The effluent from the catalytic zone is cooled and washed with water in a washing column.

The condensed organic layer is separated by decantation and distilled, the separation of 1,1,2,2-tetrachloroethane from unreacted cis and trans-dichloroethylene. The gaseous products left after cooling and washing with water are sent to a column in which they are irrigated with countercurrent 1,1,2,2-tetrachloroethane, previously separated and cooled to 0 ° C. The gas at the outlet of this column contains less than 0.5% cis- and trans-dichlorostille. The wash solution is distilled to separate 1,1,2,2-tetrachloroethane and dissolved cis and trans-dichloroethylene.

All recovered cis and trans dichloroethylene are recovered and sent to the reactor. One part of the separated 1,1,2,2-tetrachloroethane is sent to the second washing column.

gas and the other is rectified and retracted as the target product.

Conversion of cis- and granc-dichloroethylene, 62.2%, hydrogen chloride, 95.5%. At the stage of recovery unreacted

cis- and grasd-dichlorethylene yield 98.7%. The yield of rectified 1,1,2,2-tetrachloroethane is 97.3% (in terms of the loaded cis- and trax-dichloroethylenes). In addition, 1.3% of 1,1,2-trichloroethane and 0.27% of pentachloroethane are obtained in terms of loaded cis and trans-dichloroethylene. Combustion less than 0.2%. Trichlorethylene is 0.5% (in terms of loaded cis and tra c-dichloroethylene). Example 2. The same reaction is carried out.

in a similar reactor (bh 112 mm), equipped, in addition, with a catalytic layer cooling system consisting of a stainless steel pipe immersed in a catalytic layer through which coolant with a temperature of 160 ° C circulates.

The catalyst, as in example 1, the height of the catalytic layer 550 mm, the temperature of the catalytic layer 308 ± 2 ° C. At a pressure of 1.1 bar, 3.5 mol / hour-l of catalyst is fed.

mixtures of cis- and trans-dichlorethylene vapors, hydrogen chloride and oxygen.

The molar ratio of t uc-dichloroethylene:: (cis-dichlorethylene 4-trans-dichlorethylene) is 57.8%.

The effluent from the catalytic zone is cooled to 25 ° C, which makes it possible to condense most of the 1,1,1,2,2-tetrachloroethane formed, in which cis- and trans-dichloroethylenes and a very small amount of hydrogen chloride are dissolved. Uncondensed Efluent contains unreacted cis- and trans-dichloroethylenes, oxygen, hydrogen chloride and very small amounts of uncondensed 1,1,2,2tetrachloroethane and traces of carbon dioxide. The fraction (% by volume) is separated, washed with 1,1,2,2-tetrachloroethane to recover the contained dichloroethylene, and discarded. The remaining 95% is returned to the reaction,

mixing with fresh reagents.

After condensation, the condensed solvents and solvents are distilled to separate the cis and gran dichloroethylene, which are returned to the reactor and used for

purification of 1,1,2,2-tetrachloroethane.

After establishing the specified mode, the feedstock containing (mol%) is supplied to the reactor:

cis and grasse-dichloroethylene 35,6

Hydrogen chloride 47.8

12.8

Oxygen

1,1,2,2-tetrachloroethane

Carbon dioxide

Nitrogen

Other

Conversion of cis- and granc-dichlorethylene 55.9%.

The total yield of 1,1,2,2-tetrachloroethane is 97.6% (in terms of taken cis and trans-dichloroethylenes). In the course of the reaction, 1.1% 1,1,2-trichl is formed: orethane and 0.3% pentachloroethane in terms of taken cis- and grasc-dichloroethylenes.

Combustion less than 0.2%. Trichlorethylene is produced; 0.4% (in terms of taken cis and trans-dichloroethylene).

Hydrogen chloride is used at 98.5%, oxygen at 98.7%.

Subject invention

1. A method of producing 1,1,2,2-tetrachloroethane by the oxidative chlorination of cis and / or granc-dichloroethylene at an elevated temperature in the presence of a fluidized bed of catalyst — metal chlorides on a carrier, characterized in that, in order to reduce the formation of by-products,

Claims (6)

1.1 is carried out in the presence of a catalyst on a no, 6 1.8 0.3 siter, the specific surface of which is 10-200, with a molar ratio of HC1: (h "c-CHC1 CHC1 + gran-CHC1 CHC1) equal to 0.8--2, and O2: (g {is-CHC1 CHC1 + + gran-CHC1 CHC1), equal to 0.2-0.6. 2. A method according to claim 1, characterized in that cis- and / or gran-dichloroethylene is fed into the reaction zone at a rate of 0.5-20 mol / hour-l of catalyst. 3. Method according to paragraphs. 1 and 2, characterized in that the dichlorethylene is fed to the reaction zone in a mixture with tetrachloroethane at a molar ratio of less than 2 between them. 4. Method according to paragraphs. 1-3, characterized in that the process is carried out at a pressure of 1 -10 bar and a temperature of 200-360 ° C. 5. Method according to paragraphs. 1-4, characterized in that an attapulgite with a specific surface of 10-160 or a mixture of silica gel with MgO with a specific surface of 40-200 is used as a carrier. 6. A method according to claim 1, characterized in that a supported catalyst is used on a carrier with a specific surface area of more than 1.