Method for producing 1,2-dichloroethane

 

(57) Abstract:

Usage: 1,2 - dichloroethane used as raw material for large-scale production of vinyl chloride monomer to polymer materials, also as solvent. The inventive ethylene chlorination is carried out at a temperature of 20 - 65oC, with the selection of the product from the liquid phase, which is directed in parallel to the reactor chlorination of ethylene at the boiling temperature of the reaction mass (84 - 90oC) selection of the product from the vapor phase. Accumulating in the chlorination reactor at a temperature of 84 - 90 deg catalyst fed into the reactor(s) chlorination at a temperature of 20 - 65oC or disposed of. The ratio of 1,2 - dichloroethane obtained at a temperature of 20 - 65oC and boiling of the reaction mass change from 1 to 4.5. 1 C.p. f-crystals, 2 tab.

The invention relates to a method for producing 1,2-dichloroethane (EDC), used as raw material for large-scale production of vinyl chloride monomer to polymer materials, and also as a solvent.

The main quantity of 1,2-dichloroethane (EDC) in the world is produced by the method of liquid-phase chlorination of ethylene in the environment of EDC in the presence of various skating homolytic directions of reaction.

Known methods for producing EDC liquid-phase chlorination of ethylene on technological characteristics can be divided into two groups: the processes carried out at the boiling temperature of the reaction mass [1] and the processes carried out at temperatures below the boiling point of the reaction mixture [2]

When the chlorination of ethylene at a temperature below the boiling point of the reaction mass (20 65oC) in the presence of catalysts obtained EDC is taken from the liquid phase, therefore it needs to be cleaned from the catalyst. Cleaning is carried out by a multistage aqueous-alkaline leaching and subsequent azeotropic drying or distillation (rectification).

When using aqueous-alkaline leaching EDC catalyst and/or the inhibitor is destroyed and removed from the process wastewater. The method of separation of the catalyst and/or inhibitor from EDC by distillation or rectification requires high energy costs.

The reaction of the additive chlorination of ethylene is highly exothermic:the amount of heat released during the synthesis of one mole of EDC, enough to evaporate six mol EDC. In this regard, developed and implemented in industry the direct chlorination of ethylene in boiling reaction is W ith reaction heat for distillation or rectification product, and also to eliminate the water and alkaline leaching and azeotropic drying. However, compared with the method of obtaining EDC at relatively low temperatures (20 65oC) chlorination of ethylene at the boiling temperature of the reaction mass has a lower additive selectivity and a large number of troublesome waste (polyvinyl chloride and oligomers).

The greatest application as a catalyst in the chlorination of ethylene to EDC received trichloride iron [1, 2] which allows to obtain the target product with a relatively high additive selectivity at the level of 98% However, given the scale of production of EDC, the attainable degree of transformation of raw materials into the target product is not satisfactory, so even a small degree of non-target areas leads to the formation of many thousands of tons of troublesome by-products.

In recent years, industrial production processes EDC implemented catalysts complex type, providing the selectivity of the target area more than 99% for example, by chlorination of ethylene in the presence of catalysts consisting of trichloride iron and nitrogen bases, provided 99,5 99,9% selectivity is with ethylene in the liquid EDC at a temperature of 20 70oC in the presence of 0.002 to 0.3 wt. catalyst consisting of FeCl3and NH3and oxygen or air [4] Obtained EDC raw with dissolved and suspended therein a catalyst withdrawn from the reactor through an overflow and sent to a distillation column for separation of the target product. The EDC distillation is conducted prior to the selection of the catalyst. Remaining in the lower part of the column EDC (50 to 80% of incoming distillation) with dissolved and suspended therein a catalyst returns to the reactor chlorination of ethylene.

The present invention is a method of obtaining EDC interaction of chlorine with ethylene in the liquid EDC in the presence of soluble jelitkomplekt catalysts are aimed at improving the environmental performance of the process by reducing the number of generated by-products and reducing the amount of wastewater to reduce flow catalytic systems per unit produced EDC due to the organization of recycling, as well as simplify the process of purification of EDC from the catalyst.

The proposed method for EDC is as follows. Chlorination of ethylene is carried out at a temperature of 20 65oC, with the selection of the product from the liquid f is parallel operating reactor ethylene chlorination at the boiling temperature of the reaction mass (84 - 90oC), where due to the heat of reaction of EDC is evaporated and thereby separated from the catalyst. The ratio of the quantity supplied to the evaporation of the EDC from the reactor(s) chlorination of ethylene at a temperature of 20 65oWith the number obtained in the chlorination reactor at the boiling temperature of the reaction mass can be changed in the range from 1 to 4.5. Accumulating in the chlorination reactor at a temperature of 84 90oC catalyst continuously or intermittently in a solution of EDC in number of 2 to 12 wt. from the amount fed to the evaporation EDC is sent to the reactor(s) chlorination at a temperature of 20 65oC, and the deactivation of the catalyst taken for recycling. Evaporated EDC condense, then part of it, equal to the number of EDC needed to maintain a given level of the reaction mixture, return to the chlorination reactor at the boiling temperature of the reaction mass. The remaining part of the EDC is taken as the product.

Chlorination of ethylene to EDC conducted on laboratory and industrial settings. The content of high-boiling impurities (polyvinyl chloride and oligomers) is determined after the EDC distillation and separation of the catalyst.

Example 1 (comparative). Gloriou what Borom product from the vapor phase is conducted in a laboratory setup, including lead bubbler type reactor (H=1000 mm, D=70 mm), cleaning systems and dosing of chlorine and ethylene, as well as condensing distribution system. To compensate for heat loss to the reactor equipped electroholography clutch.

Charged to the reactor 1800 g of EDC and 20 g [C5H5NC2H4Cl]+FeCl4]-used as a catalyst. Chlorine and ethylene are served with a cost of 15.0 and 15.5 l/h, respectively. The performance of the reactor is 66 g of the product 1 including Periodically through 200 h add 2.0 g of catalyst.

Additional features of the process are shown in table 1.

Example 2 (comparative). Chlorination of ethylene in the environment of EDC in the presence of a catalyst at a temperature of 35oC selection of the product from the liquid phase is conducted in a laboratory setup, including glass bubbler-type reactor with a volume of 1.5 liters, equipped with a stirrer, heating jacket and a reflux condenser, and system cleaning and dosing of chlorine and ethylene.

Charged to the reactor 999 g of EDC and 1.0 g [C5H5NC2H4Cl]+[FeCl4]-used as a catalyst. Chlorine and ethylene served with costs 10,0 1 and the congestion in the reaction mass in it constantly serves 0,045 g in 1 h of catalyst in the form of a 10% aqueous solution of EDC.

Additional features of the process are given in table.1.

Example 3. Chlorination of ethylene was conducted as in example 1, except that in the chlorination reactor (evaporator) continuously served EDC obtained in three reactors as in example 2, in the amount of twice the amount of EDC, directly synthesized in the reactor evaporator. From the liquid phase reactor evaporator select the reaction mass in the amount of 8.0 15.0 g 1 h (depending on the concentration of catalyst), and fed into the reactor chlorination of ethylene at a temperature of 35oC to ensure it constant concentration of catalyst in the range 0.1 to 0.15 wt.

Additional features of the process are given in table.1.

Example 4. Chlorination of ethylene was conducted as in example 3, only in the chlorination reactor (evaporator) continuously served EDC from six reactors as in example 2, in the amount of 4.5 times the amount of EDC, directly synthesized in the reactor evaporator. From the liquid phase reactor evaporator select the reaction mass in the number of 22.0

34,0 g 1 h (depending on the concentration of catalyst), and fed into the chlorination reactor ethylene CLASS="ptx2">

Additional features of the process are given in table.1.

Example 5 (comparative). Chlorination of ethylene to EDC at the boiling temperature of the reaction mass (85 90oC) is carried out in leaded or enameled reactor column type (H=8400 mm, d=1400 mm). The excess heat of reaction away by circulating the reaction mixture through a remote refrigerator and due to the evaporation of EDC.

Charged to the reactor 9,50 m3(12000 kg) EDC and 120 kg of compound [C5H5NC2H4Cl]+[FeCl4]-used as a catalyst. In the reactor serves 1000 m3/h (in recalculation on 100% chlorine content2) 95 to 97% of chlorine and 1050 1100 m3/h of ethylene. Evaporating from the reactor EDC condense, then part of it, equal to the number of EDC needed to maintain a given level of the reaction mixture, return to the reactor. The remainder, equal to the number of synthesized EDC (4419 kg/h), taken as the product.

To maintain the high selectivity of the process in the reaction mass periodically through 250 300 h add 20 to 30 kg of catalyst in the form of a 10% aqueous solution of EDC.

The flow of catalyst per ton of product is 0,023 0,027 kg

Output per ton of prody and oligomers 0,035 0,050

Additional features of the process are given in table. 2.

Example 6 (comparative). Chlorination of ethylene to EDC carried out in a lead-lined reactor column type by volume of 10 m3equipped with cooling "shirt" and built a lead coil heat exchanger to maintain the desired reaction temperature, and bubblers for the supply and distribution of chlorine and ethylene.

Charged to the reactor to 7.64 m3(9500 kg) EDC and 10 kg of compound [C5H5NC2H4Cl]-[FeCl4]+used as a catalyst in the form of a 10% aqueous solution of EDC. Chlorine and ethylene served with spending 200 and 220 m3/h respectively (in recalculation on 100% concentration). The temperature in the reactor support 453oC. Received EDC raw selected through the overflow in the number 884 kg in 1 h, the Catalyst in the reaction mass is added continuously in the number 0,826 kg per hour in a 10%-aqueous solution of EDC. Its concentration is maintained within the range of 0.09 to 0.15% by weight of the reaction mixture. EDC raw with the aim of dissolved catalyst, chlorine and hydrogen chloride is subjected to an aqueous-alkaline leaching and azeotropic drying, the catalyst is destroyed and his conclusion is that, kg:

1,2-dichloroethane 999,0 999,5

1,1,2-trichloroethane 0,2 0,4

Low-boiling impurities 0,3 0,5

The polyvinyl chloride and oligomers 0,012 0,020

Additional features of the process are given in table.2.

Example 7. Chlorination of ethylene is conducted simultaneously by two methods: during boiling of the reaction mixture (85 90oC) in the reactor evaporator with a continuous selection of the target product from the vapor phase (as in example 6) and five reactors at a temperature of 45oC (same as in example 5) with a continuous flow received productiv number 4419 kg/h into the reactor evaporator. From reactor evaporator as the product is taken 8838 kg/h of evaporated EDC and as a solution of the catalyst 170 500 kg/h of the reaction mass, depending on the concentration of catalyst, which is sent in a reactor operating at a temperature of 45oC to provide them the concentration of the catalyst is 0.1 to 0.15 wt.The ratio of the quantity supplied to the evaporation of EDC reactor operating at a temperature of 45oC, to the amount of EDC produced directly in the reactor evaporator, is 1.

The flow of catalyst per ton of product 0,016 0,024 kg

Output per tonne of product (kg):

1,2-dichloroethane 998,0 998,7

example 8. Chlorination of ethylene was conducted as in example 7, only the reactor evaporator serves to evaporation 12376 kg/h EDC obtained in 14 reactors satellites. From reactor evaporator as the product is taken 16781 kg/h of evaporated EDC and as a solution of the catalyst 690 1400 kg/h of the reaction mass, depending on the concentration of catalyst, which is sent to the reactor satellites to provide them the concentration of catalyst is 0.1 to 0.15 wt. The ratio of the quantity supplied to the evaporation of EDC reactors, satellites, to the amount of EDC produced directly in the reactor evaporator, equal to 2.8.

The flow of catalyst per ton of product 0,010 0,012 kg

Output per tonne of product (kg):

1,2-dichloroethane 998,5 999,0

1,1,2-trichloroethane 0,3 0,7

Low-boiling impurities 0,4 0,7

The polyvinyl chloride and oligomers 0,018 0,028

Additional features of the process are given in table.2.

The proposed method for EDC by combining two processes chlorination of ethylene allows the full use of their advantages:

to increase the selectivity (to reduce the output of polyvinyl chloride and oligomers) of the process of chlorination of ethylene by receiving part of the product of Eirca, obtained by the chlorination of ethylene at a temperature below the boiling EDC;

to reduce the consumption of the catalyst by separating it from EDC raw in the reactor evaporator followed by a return to the reactor satellites.

Thus, the proposed method for EDC will bring the most common method of chlorination of ethylene at a temperature below the boiling EDC in accordance with the environmental requirements of modern technological processes.

1. Method for producing 1,2-dichloroethane by reacting chlorine with ethylene at 20 90oWith in the environment of 1,2-dichloroethane as a solvent in the presence of recirculation in the process of a soluble catalyst in the amount of 0.05 to 5.0 wt. in the calculation of the solvent, characterized in that the chlorination of ethylene is carried out in the reactor or reactors at 20 65oWith, the product obtained with the catalyst fed into the reactor or reactors operating at the boiling temperature of the reaction mass 84 90oWith the same catalyst, from which the top select 1,2-dichloroethane vapor state as the target product, and the bottom display a catalyst in a solution of 1,2-dichloroethane in the amount of 2 to 12 wt. in the calculation of the applied is to 1,2-dichloroethane, obtained at 20 65oAnd when boiling the reaction mass equal to 1-4,5:1.

2. The method according to p. 1, characterized in that 5 to 20 wt. the catalyst solution in 1,2-dichloroethane from the bottom of the reactor, operating at the boiling temperature of the reaction mass, sent for recycling.

 

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