The method of producing vinyl chloride

 

(57) Abstract:

Usage: as a monomer in the production of the most important polymeric materials. The inventive dehydrochlorination of 1,2-dichloroethane in the vapor phase at 280-400oC, preferably at 325-350oC, in the presence of hydrogen addition at a molar ratio to ethylene dichloride, 0,02-0,25:1, Treherne catalyst containing Pt or Pd - Al2O3. Significantly reduced process temperature, decreases the quantity of generated by-products, as well as tar and soot, and energy consumption. table 2.

The invention relates to a method for producing vinyl chloride heavy chlorine-containing monomer used in the production of the most important polymeric materials and products based on them.

In industry the vinyl chloride basically get thermal dehydrochlorination of 1,2-dichloroethane in the hollow tubular reactors. To achieve an acceptable practice for conversion dichloroethane ( 50%), the reaction is carried out at high temperatures (500-550oC) [1]

The disadvantages of this process include: high temperature reactions leading to the formation of by-products, as well as tar and soot, and relatively miscellenous to introduce additives, accelerating the process of dehydrochlorinating (chlorine [2,3] oxygen [4]). Thus, the use of the most effective according to [3] initiator of chlorine reduces the temperature of the pyrolysis of dichloroethane to 400-420oC and increase its conversion to 70% According to the calculations [3] reducing the temperature to 420oAt the speed of transformation of dichloroethane to reduce the number of the resulting resinous products 10 times. Thereby the reduction of fuel consumption in pyrolysis furnaces by 25% and water consumption for quenching the products of the process approximately 55%

Technological design of this process is difficult and not achieve a high conversion of dichloroethane at considerable expense to add chlorine.

There are also known methods for producing vinyl chloride by dehydrochlorination of 1,2-dichloroethane in the presence of catalysts. Thus, in [5] as the catalyst recommend deposited on fluorinated alumina Nickel metal for enhancing the conversion of 1,2-dichloroethane up to 98% at relatively low temperatures (350 to 400oC) and contact times (()) to about 30 C. In [6,7] described methods for producing vinyl chloride in the presence of catalysts based on magnesium chloride and kobany in [5] and provide 98-100% conversion and selectivity 97-98% at lower contact times ( 10-11). In [8] recommend the catalytic dehydrochlorination carried out with the addition of oxygen, although as described in [8], it has virtually no effect on the performance of the catalytic process.

The closest in technical essence and the achieved effect is the way (prototype), described in [9] where the catalyst using platinum coated on fluorinated alumina. The process is carried out in the presence of an inert diluent, such as nitrogen, in the range of 350-450oC. under optimal conditions (400oC, the molar dilution with nitrogen of 1:1, t 1.6 (C) conversion of 1,2-dichloroethane and the selectivity to vinyl chloride are 97-98 and 97-99%, respectively.

The main disadvantage of such a method of producing vinyl chloride is the need for a temperature high enough to achieve high process performance.

The purpose of the invention, the activation of the catalyst, lowering the process temperature while maintaining its high performance.

This is achieved by carrying out the catalytic dehydrochlorination in the presence of hydrogen at a molar ratio of N2/C2H4Cl2from 0.02 to 0.25 for palladium or Latinoamerica katalizatorov obtain vinyl chloride is illustrated by examples 1, 4, 5, 7-9, 11-15 (table 1) and 16-21 (table 2). In examples 2, 3, 6, 10 are provided for comparing experimental data obtained in the absence of hydrogen, i.e., in terms of the prototype. From a comparison with data obtained with the prototype, it is necessary that the hydrogen intensifies the catalytic process: the reaction rate of dehydrochlorination and conversion of 1,2-dichloroethane significantly increased (examples 3 and 4, 6 and 7, 10 and 11). The addition of hydrogen at a molar ratio of N2/C2H4Cl20.25 initial mixture has no significant effect on the selectivity to vinyl chloride. If more than the specified molar ratio along with the dehydrochlorination start to flow processes hydrodechlorination of 1,2-dichloroethane and the product of its dihydrochloride with the formation of ethylene, ethane, ethylchloride etc. This leads to a noticeable decrease in the selectivity to vinyl chloride.

The dehydrochlorination of 1,2-dichloroethane accompany the process of coke formation, which reduces the activity of the catalyst over time. This is illustrated by the examples of 2.3, which presents the experimental results obtained on the first and third hour of the experiment. In the presence of hydrogen significantly retard the deactivation of the catalyst that bring the oC increase associated processes that may adversely affect the catalyst activity and selectivity to vinyl chloride. At temperatures below 325oC achieving high performance leads to poor performance of the reactor.

The preferred palladium catalyst in comparison with platinum in relation to the selectivity of the process is illustrated by examples 14 and 15.

Examples. The process is carried out in cellopane flow-circulation (table 1) or flow (table 2) installations. In eraksoy reactor of 30 cm3download the catalyst (the grain size of 0.25 to 0.5 mm) in the amount shown in the tables. As the palladium catalyst used (examples 1-13, 16-22) or platinum (examples 14, 15) supported on activated alumina in amounts of 0.5 wt. metal by weight of the catalyst. Supply of vaporous 1,2-dichloroethane in the reactor is performed by the saturation of nitrogen. In examples 1-20 feed rate dichloroethane vapor in the reactor is 1,24 nl/h, in examples 21, 22 0,62 nl/h In examples 6-9, 14, 15 in the reaction gas mixture to dilute it further to add nitrogen in the amount of 4.5 nl/h

Analysis of the reaction mixture is performed with chromatographic and litty experiments are shown in tables.

The method of producing vinyl chloride by dehydrochlorination of 1,2-dichloroethane in the vapor phase at elevated temperature in the presence of a catalyst containing platinum on alumina, wherein the process is conducted in the presence of additives of hydrogen at a molar ratio with dichloroethane 0,02 - 0,25 1 and use tragerdy catalyst containing Pt or Pd deposited on gamma-Al2O3and the process is conducted at 280 400oWith, preferably 325 350oC.

 

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26 cl, 1 tbl

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3 cl, 3 ex, 1 dwg

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EFFECT: improved method of synthesis.

2 cl, 1 tbl, 1 dwg, 4 ex

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