The method of producing chlorine-methanes

 

(57) Abstract:

The invention relates to the production of chlorine-methanes, preferably chloroform. The process includes initiated chlorination of methyl chloride, methylene chloride or a mixture of the chlorine in the liquid phase at the boiling temperature of the reaction mass under pressure, determined by the resistance of systems rectification, removal of hydrogen chloride and an additional selection of reaction products from the vapor phase, recycling the unreacted methyl chloride and methylene chloride in the chlorination. The distillation is performed under a pressure determined by the resistance of the system to remove hydrogen chloride, with sampling of vapor phase comprising hydrogen chloride, methyl chloride and parts of methylene chloride. By reducing the formation of carbon tetrachloride improving environmental parameters, simplified method and reduces the specific energy consumption by reducing the temperature and pressure of the chlorination process. 5 C.p. f-crystals, 1 table.

The invention relates to chemical technology and for the production of chlorine-methanes, primarily chloroform.

A known method of producing chlorine-methanes thermal chlorination of methyl chloride in steam the Oia from hydrogen chloride is split into a system of distillation columns. The disadvantages of the method are the complexity of the process and apparatus registration process associated with conducting the reaction at a high temperature, the presence of chlorine breakthrough after chlarotera, the formation of by-products (haratani and chlorethylene), which requires additional treatment of the reaction mass, the low output of chloroform. Thus, the output of chloroform is 20% when the ratio of chloroform:carbon tetrachloride 3,6:1.

Another known method of producing chlorine-methanes by partial chlorination of the mixture of methyl chloride and methylene chloride in a molar ratio of chlorine:chlorine-methanes from 0.15:1 to 0.21:1 at a molar ratio of methyl chloride to methylene chloride to about 1.5:1 [U.S. Pat.USA N 4927981, 22.05.90] leads to reduce the formation of impurities, however, is characterized by technological complexity and hardware design. Initiate the chlorination is carried out at a temperature of 220-500oC under pressure 13-130 ATM during the process in the reactor of ideal displacement.

Closest to the proposed combination of essential characteristics is a method of producing chlorine-methanes by chlorination of methyl chloride with chlorine in the liquid phase in the presence of initiators, in particular porofor the ion mass selected in a liquid phase, with almost all of hydrogen chloride dissolved in the reaction mass, which is sent on the rectification. On the first column rectification emit hydrogen chloride. In the second column emit unreacted methyl chloride, which, together with the received return methylene chloride in the chlorination.

A known method of producing chlorine-methanes is characterized by a low output of chloroform and relatively high yield of carbon tetrachloride. Thus, when the amount of chlorine introduced 1.53 mol per 1 mol of methyl chloride, the yield of chloroform is 38.5% when the mass ratio of the obtained chloroform and carbon tetrachloride 4:1. A known method of producing chlorine-methanes is also characterized by the complexity of instrumentation associated with the use of high pressure which does not allow to remove the heat of reaction by boiling the reaction mass and increases the concentration of hydrogen chloride in the reaction mass, resulting for separation of hydrogen chloride and methyl chloride requires two distillation columns.

The technical task of the present invention is to reduce the formation of carbon tetrachloride, which can improve the environmental couples the pressure of the chlorination process.

The specified technical task is solved in that in the method of producing chlorine-methanes, including initiated chlorination of methyl chloride, methylene chloride or a mixture of the chlorine in the liquid phase at elevated temperature and pressure with subsequent selection of the products of the reaction, by distillation, removing hydrogen chloride and recycling unreacted methyl chloride and methylene chloride in the chlorination, the latter is carried out at the boiling temperature of the reaction mass under pressure, determined by the resistance of systems rectification and removal of hydrogen chloride, the selection of the reaction products are advanced from the vapor phase, and the distillation is performed under a pressure determined by the resistance of the system to remove hydrogen chloride, with the selection of the vapor phase, consisting of hydrogen chloride, methyl chloride and parts of methylene chloride.

The concentration of chlorine-methanes in the reaction mass is maintained within the range, wt.%:

Methylene chloride - 55-70

Chloroform - 25 - 40

Carbon tetrachloride - To 5

Recycling the unreacted methyl chloride and methylene chloride perform primarily by fractional condensation of the vapor phase from the distillation feed condensate chlorination.

Inlinestring or mercury dump.

The turbulization of the reaction mass exercise at least with elements of movement of the fluid in the Central zone of chlorination reactor in the upward direction together with the incoming chlorine and chloride formed by hydrogen, and the walls of the reactor chlorination or in the external circuit in the opposite direction.

The removal of hydrogen chloride can be achieved by absorption of water from the receipt of hydrochloric acid.

Example 1. Chlorination of methylene chloride is conducted in a laboratory setup, including the chlorination reactor, dosing of chlorine and methylene chloride, distillation column for separation of the products of the chlorination system and the absorption of hydrogen chloride. The reactor is a glass cylinder with a height of 650 mm and a diameter of 30 mm, which is installed inside the glass liner with the holes for the turbulence in the reaction mass. Submission of methylene chloride and chlorine are carried out by the individual nozzles in the lower part of the reactor. Products of chlorination output by flowing pipe from the upper part of the reactor. Initiate the chlorination is carried out using two fluorescent lamps rated at 20 watts each.

In the reactor Bay>Chloroform - 28,5

Carbon tetrachloride and 1.5

Within 5 h serves chlorine with the speed of 1.26 mol/h and methylene chloride - 1,29 mol/h Temperature in the reactor 40oC, the pressure is close to atmospheric. Vapor-liquid stream withdrawn from the reactor by flowing pipe and sent to a distillation column efficiency 40 so so, equipped with a brine refrigerator (-20oC) on which the light fraction emit hydrogen chloride and methylene chloride. Last condense and return to the chlorination. The conversion of chlorine is 100%. Hydrogen chloride absorbs water to form a hydrochloric acid. After the experience in Cuba distillation column receive 732 g of chloroform raw content of chloroform 95,1 wt.%. The selectivity of the process according to the chloroform per unreacted methylene chloride - 96,1%.

Example 2. Chlorination of methylene chloride is carried out in a glass reactor U-shaped with a crosspiece at the top, allowing the turbulization of the reaction mixture circulating in the loop reactor. Digester volume of 50 ml In a reactor filled with 60 g of a solution of chlorine-methanes composition, wt.%:

Methylene chloride - 62,7

Chloroform - 35,2

Carbon tetrachloride - 2,1

Iniciirovanii/h, the methylene chloride is 0.33 mol/h Products of chlorination was allocated in the system described in example 1. After the experience in Cuba distillation column obtained 186,5 g of chloroform raw content of chloroform was 94.2 wt.%. The selectivity of the process according to the chloroform per unreacted methylene chloride was 95.5%.

Examples 3-7. Chlorination of methylene chloride, methyl chloride or mixtures of these chlorine-methanes carried out in the reactor described in example 2. Separation of the products of chlorination with recycling of methylene chloride and methyl chloride were performed on the system described in example 1. The duration of each experience - 5 o'clock Specific conditions and results of experiments are shown in the table. The experiments in examples 1-6 were conducted under optimal conditions, for example 7 - in boundary conditions. Example 7 shows that increasing the concentration of chloroform in the solution of more than 40 wt.% and the decrease in the concentration of methylene chloride below 55 wt.% accompanied by the formation of increased amounts of carbon tetrachloride, while the selectivity of the process according to the chloroform is significantly reduced.

Increasing the concentration of methylene chloride is higher than 70 wt.% while reducing the concentration of chloroform below 25 wt.% impractical due to increase the>/P>Thus, the process according to the proposed method improves the selectivity of the chlorination up to 90-97% (compared to 84% on prototype) and to reduce the number of side unusable product of carbon tetrachloride. The method is simple and energy efficient due to the low temperature and pressure during the process of chlorination.

1. The method of producing chlorine-methanes, including initiated chlorination of methyl chloride, methylene chloride or a mixture of the chlorine in the liquid phase at elevated temperature and pressure with subsequent selection of the products of the reaction, by distillation, removing hydrogen chloride and recycling unreacted methyl chloride and methylene chloride in the chlorination, wherein the chlorination is carried out at the boiling temperature of the reaction mass under pressure, determined by the resistance of systems rectification and removal of hydrogen chloride, the selection of the reaction products are advanced from the vapor phase, and the distillation is performed under a pressure determined by the resistance of the system to remove hydrogen chloride, with sampling of vapor phase comprising hydrogen chloride, the methyl chloride and parts of methylene chloride.

2. The method according to p. 1, otlichnazia vapor phase from the distillation feed condensate chlorination.

3. The method according to p. 1, characterized in that the concentration of chlorine-methanes in the reaction mass is maintained within the range, wt.%:

Methylene chloride - 55 - 70

Chloroform - 25 - 40

Carbon tetrachloride - To 5

4. The method according to p. 1, characterized in that the initiation of the chlorination process carried out by the action of actinic light, such as incandescent, fluorescent or mercury lamps.

5. The method according to p. 1, characterized in that the turbulization of the reaction mass exercise at least with elements of movement of the fluid in the Central zone of chlorination reactor in the upward direction together with the incoming chlorine and chloride formed by hydrogen, and the walls of the reactor chlorination or in the external circuit in the opposite direction.

6. The method according to p. 1, characterized in that the removal of hydrogen chloride is carried out by absorption of water from the receipt of hydrochloric acid.

 

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1 ex, 1 dwg

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5 cl, 4 ex, 1 tbl

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