DE1229999B - Process for the production of 1, 2-dichloroethane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Tnt. CL:

C07c

German IQ .: 12 ο -2/01

Number: 1 229 999

File number: C 32010IV b / 12 ο

Filing date: January 31, 1964

Opening day: December 8, 1966

It is known (see. French Patent 1262 725), 1,2-dichloroethane by reaction of Ethylene with hydrogen chloride in the fluidized bed of a fluidized catalyst or via fixed bed catalysts to manufacture. It is advisable to keep the ethylene conversion as high as possible. This is known to be possible by using an increased amount of hydrogen chloride after the equation

C ₂ H ₄ + 2 HCl + V ₂ O ₂ -> C ₂ H ₄ Cl ₂ + H ₂ O

running process in favor of a higher ethylene conversion influenced. As the extraction of the desired Reaction product in the art is now expediently carried out so that the Reaction gases leaving the reactor are cooled with water and condensed according to their vapor pressure The excess causes the unreacted hydrogen chloride to convert to aqueous hydrochloric acid of hydrogen chloride inevitably an increased amount of aqueous hydrochloric acid. This aqueous hydrochloric acid cannot be returned to the oxychlorination reactor because the water formed during the reaction must be removed from the process.

In order to keep the amount of aqueous hydrochloric acid as low as possible, it was proposed (cf. Documents of the Belgian patent specification 608 678) to use an excess of ethylene and one To introduce part of the reaction gases back into the oxychlorination reactor in a cycle. Because now Again, the oxychlorination of ethylene due to the high heat of reaction released is expedient is operated with air as the gas supplying oxygen, the proportion of the cycle gas is understandable low and the proportion of unreacted ethylene remains high.

It has now been found that 1,2-dichloroethane can be advantageously produced if one is in a

1st stage excess ethylene, hydrogen chloride and excess oxygen in the form of air in the presence of a known oxychlorination catalyst by appropriate adjustment of the proportions of the starting materials with more than 90% conversion of hydrogen chloride at 180 to 35O ⁰ C, the residual gases from this stage after washing of the unconverted hydrogen chloride and the resulting condensation of a large part of the 1,2-dichloroethane formed in one

2nd stage with chlorine (80 to 120 mol percent, based on the ethylene used in this stage) in the presence an iron-containing catalyst at 80 to 250 ° C.

Process for the production of 1,2-dichloroethane

Applicant:

Chemical works Hüls Aktiengesellschaft, Mari

Named as inventor:

Dr. Franz Broich,

Dr. Günther Maahs, Mari

The smooth course of the chlorination m of the second stage is particularly surprising because the ethylene concentration is very low in the exhaust gas of the first stage. In addition, the post-chlorination is not disturbed by the tensile amounts of dichloroethane and water contained in the exhaust gas.

The 1st oxychlorination stage is carried out as follows: Using a catalyst known per se, such as B. copper chloride, which is optionally stabilized with alkali metal chloride, optionally with the addition of Iron or chromium salts or rare earth salts on aluminum oxide carrier material the gases, ethylene, hydrogen chloride and air are conducted at temperatures between 180 and 350 ° C. the The proportions of these gases are adjusted so that the conversion of hydrogen chloride > 90%. This conversion is achieved by using excess ethylene over and above the stoichiometric amounts and oxygen can be used in the form of air. The proportions are accordingly given by the following Ranges limited:> 1 to 3 moles of ethylene: 2 moles of hydrogen chloride:> 0.5 to 1.0 moles of oxygen in the form of air.

The second chlorination stage is carried out as follows: Via an iron or iron-containing catalyst, e.g. B. scrap iron or an impregnated with iron salts inert carrier are at 80 to 25O ⁰ C the residual gases from the oxychlorination step, after washing out the unreacted hydrogen chloride and the resulting condensation of a major portion of the resulting 1,2-dichloroethane, mixed with chlorine is passed. The proportion of added chlorine depends on the ethylene contained in the residual gas and should be between 80 and 120 mol percent according to the equation

C ₂ H ₄ + Cl ₂ -► C ₂ H ₄ Cl ₂
calculated amount.

609 730/409

In addition to being used as a solvent, 1,2-dichloroethane is primarily used as an intermediate in the manufacture of vinyl chloride used.

example

Preparation of the catalyst for stage 1

• 1250 g of y-aluminum oxide with a surface area of 232 m ² / g and a grain size of 0.08 to 0.15 mm are _{mixed with 1700 ml of a methanolic solution of 495 g of CuCl 2} · 2 H ₂ O and left to stand for 1 hour. The supernatant liquid (100 ml) is then poured off and the contact is dried in a vacuum drying cabinet. The finished contact has a surface area of 150 m ^a / g and contains 10.4% Cu.

Iron turnings are used as a catalyst for stage 2 used. The device shown in the drawing is used for chlorination.

The reactor 1 consists of a nickel tube (6 cm diameter, 150 cm height), equipped with electrical Heater 2, a cooling jacket 3, a sieve 4 on the bottom, a stirring device 5 and several Thermocouples 6, and contains 1900 ml of catalyst. Behind the reactor 1 there is a cyclone 7 and a washing tower 8, which is sprinkled with water. The gas outlet 9 of the washing tower is with the post-reactor 10 (stage 2), into which the chlorine measured by a flow meter is also metered at 11 will. The post-reactor consists of glass (6 cm diameter, 140 cm height), half filled with iron turnings. It has an electrical heater 12 and thermocouples 13 for temperature measurement. Downstream are a washing tower 14 (lye wash) and several cold traps 15 in which the rest Product is condensed.

The reactor 1 is ^{heated to 200 °} C. and charged with 137 l / h of ethylene, 220 l / h of hydrogen chloride and 393 l / h of air. In the reactor a temperature of 238 provides a ⁰ C, which is maintained by external cooling.

In the washing tower 8 (water), 345 g of 1,2-dichloroethane are precipitated every hour; An unreacted amount of hydrogen chloride of 10.3 g / h is found in the water; this corresponds to a hydrogen chloride conversion of 97% · The exhaust gas consists of 311 gaseous 1,2-dichloroethane, 9.01 water vapor and a non-condensable gas mixture (350 l / h) which still contains 3% ethylene. The ethylene concentration in the entire exhaust gas is therefore 2.69% · This exhaust gas is mixed with 8.4 l / h of chlorine and passed into the heated to 100 ⁰ C reactor 10th In the subsequent alkaline wash 14 0.11 g of unreacted chlorine are found per hour; this corresponds to a chlorine conversion of 99.5%. After the condensation of 1,2-dichloroethane in the cold traps 15, no more ethylene can be detected in the exhaust gas. The degree of purity of the 1,2-dichloroethane from stage 1 is 99.8%, from stage 2 99.5% (determined by gas chromatography). ,

Claims (2)

Claim: Process for the production of 1,2-dichloroethane, characterized in that one in one 1st stage excess ethylene, hydrogen chloride and excess oxygen in the form of air in the presence of a known oxychlorination catalyst by appropriate adjustment of the proportions of the starting materials with more than 90% conversion of hydrogen chloride at 180 to 35O ⁰ C, the residual gases from this stage after washing of the unconverted hydrogen chloride and the resulting condensation of a large part of the 1,2-dichloroethane formed in one 2nd stage with chlorine (80 to 120 mole percent, based on the ethylene employed in this step) in the presence of an iron-containing catalyst at 80 reacted to 25O ⁰ C. 1 sheet of drawings 609 730/409 11.66 © Bundesdruckerei Berlin