Vinyl chloride production process

FIELD: industrial organic synthesis.

SUBSTANCE: gas-phase thermal dehydrochlorination of 1,2-dichloroethane is conducted in presence of hydrogen chloride as promoter dissolved in feed in concentration between 50 and 10000 ppm.

EFFECT: increased conversion of raw material and reduced yield of by-products.

4 cl, 1 tbl, 8 ex

 

Vinyl chloride (I) is one of the most important monomers. Based on it will have a large number of polymers having a wide range of different properties (mechanical, electrical, optical and other).

In the global industrial practice, I get mostly balanced method from ethylene through a stage of the gas, thermal dehydrochlorination (pyrolysis) 1,2-dichloroethane (EDC) (Bunten M.J. et. al. Encyclopedia of Polymer Science and Engineering. Volumes 17 and Supplement. - Jhon Wiley & Sons Inc.,1989, p.247 [1]). This method has several disadvantages, namely: low conversion of EDC in one pass, the formation of large quantities of by-products, coke and tar.

To improve the technical and economic indicators of the process of pyrolysis of EDC serves to hold it in presence of various substances, which are called promoters or initiators. Their use can improve the conversion of EDC, to reduce the formation of coke and some by-products.

Known methods of pyrolysis of EDC in the presence of molecular chlorine (USSR Author's certificate No. 218680, 1966; UK Patent№1225210, 1969 [2, 3]), oxygen (USSR Author's certificate No. 1066979 [4]), inorganic and organic halogen derivatives (U.S. Patent№4851597, 1989 [5]).

Chlorinated and brominated derivatives of acetone, in particular hexachlor or hexabrominated, initiate pyrolysis of EDC is the mass ratio of 0.01-0.00001:1 (U.S. Patent No. 4584420, 1986). The yield of I increases with the number of harmful by-products - chloroprene and acetylene.

Significantly increases the conversion of EDC during pyrolysis in the presence of 250-1000 ppm mass. benzotrichloride (U.S. Patent No. 5210345, 1993). Conversion of EDC in the absence of additives accounted for in the conditions of the experiments 51.8%, and in the presence of 500 ppm was 81%. It is noted that the concentration of Chlorella (mg/100 grams EDC) decreases from 0.4 to virtually no. In normal commercial practice chloral and chloralhydrate try to remove from EDC entering the pyrolysis (see, for example, U.S. patents№№3488398, 3996300, 4151212, 4172099), because of their corrosiveness with respect to the materials of the reactor. However, the authors of the invention described in international application WO 96/35653, A1 (published 14.11.96), consider that, if the materials from which the equipment was manufactured, corrosion resistant chloral and chloralhydrate, their use in the pyrolysis of EDC is very useful. In the presence of 300 ppm of Chlorella output I in the experiment increases by approximately 10%. In industrial furnaces was increased conversion rates by 5-10% and reducing the number of vinylacetylene almost to zero.

In the known methods initiated by the pyrolysis of EDC are some important downsides. Thus, the use of molecular chlorine is difficult because of its high is corrosive, the necessity of using large quantities (1% wt.) [2] to achieve the effect, complicating the design of the reactor. The latter is due to the fact that molecular chlorine recommended to serve in several points of the reaction zone (Avetyan MG, Kernerman, VA, etc.//Himprom., 1988, No. 2, p.70-74) or in the transfer line (U.S. Patent No. 4590318, 1986). It was proposed to use instead of molecular chlorine mixture of carbon tetrachloride and chlorine with low content of the latter (Lashmanova NV etc.// Himprom., 1988, No. 7, s). The increase in the conversion of EDC was 8-18%, but increased the yield of by-products - chloroprene and 1,1,2-trichloroethane 2-3 kg/hour. Increase the yield of these substances is highly undesirable, because they complicate further purification BX and recycle EDC.

The use of oxygen as initiator of the EDC pyrolysis involves additional costs, namely with the use of the catalyst [4]. In addition, it was found that in the process of pyrolysis in the presence of oxygen, oxides of carbon, which inhibit the process (Avetyan MG, Sonin EV// Chem. prom., 1993, No. 10, pp.481-482).

The use of pyrolysis such initiators as thionyl chloride, sulfurylchloride, nitrosylchloride [5], leads to the need to develop measures for cleaning flows from sulphur compounds, oxides of nitrogen. Organic initiators, hexachloro the Academy of Sciences, octachloropropane, trichloroethylene, hexachloroacetone etc. must be specifically synthesized and purified.

The purpose of this invention is the improvement of the process of pyrolysis of EDC, namely the increase of conversion and the yield of by-products through the use of cheap, easily accessible to the initiator.

This objective is achieved in that the method is initiated by pyrolysis of EDC as the initiator of the use of hydrogen chloride. The concentration of hydrogen chloride varies in the range of 50-10000 ppm mass.

The EDC pyrolysis expediently carried out at temperatures 350-650°C, at atmospheric or elevated pressures up to 40 bar (4 MPa) and a residence time of 0.1-30 seconds. The significant improvement in the conversion of EDC has been observed in the presence of 100 ppm of hydrogen chloride. During pyrolysis in the presence of 400 ppm conversion increases by 7%, and in the presence of 500 ppm by 14%. Further increase in the concentration of hydrogen chloride in the original EDC does not significantly affect the growth of conversion (at a concentration of 1000-9000 ppm hydrogen chloride increased conversion of 16%). More strongly on the concentration of hydrogen chloride depends on the output of some by-products of pyrolysis (see table).

The essence of the present invention is illustrated in the examples below.

All experiments carried out in the reactor, representing quartz is a new tube, placed in a shirt with electric heating. To the outlet of the reactor is attached hardening vessel filled with glass rings process and irrigated with distilled water, colored indicator (color indicators methyl orange). Then in the course of the stream are two traps cooled to minus 70°C. for each experiment the temperature in the evaporator is maintained within the range 280-285°With, in the reactor, 480-485°C. the Time EDC in the reaction zone is 4-6 seconds. Hydrogen chloride is dissolved in the supply EDC. In the experiments used the EDC with a purity of at least 99.8%. During the experience through a pyrolysis system is 15-20 grams of EDC. After establishing steady conditions the duration of the experiments was 1-2 hours. Organic pyrolysis products analyzed by GLC. The amount of hydrogen chloride (original product) is determined by titration. Conversion of EDC and outputs of the pyrolysis products is calculated as the arithmetic average of the data of 4-6 experiments.

Example 1. (Experience without the addition of hydrogen chloride). EDC enters the evaporator, heated to 280-285°and then in a quartz tube reactor with approximately constant speed. The temperature in the reaction zone is in the range 480-485°C. the Sin output is cooled in the quenching column with distilled water and the main part is not transformed EDC condenses down. Not the condensed part of the flow enters the cooled trap. Based on the data analysis of pyrolysis products calculate the conversion. It is in the above-mentioned conditions 33%.

Example 2. In EDC dissolved 60 mass ppm hydrogen chloride. This solution is fed into the evaporator. The temperature in the evaporator and the reactor are 280-285 and 480-485°s, respectively. Further, all operations are performed as in example 1. Conversion of EDC is 33%. The output of 1,1,2-trichloroethane is reduced in 2 times.

Examples 3-8. The EDC pyrolysis is conducted under conditions comparable with example 1, in the presence 100, 270, 400, 500, 1000, 9000 ppm mass of hydrogen chloride, respectively. The results are shown in the table.

The given examples show that the number of such side products, such as trichloroethylene, perchloroethylene, 1,1,2-trichloroethane, 1,1,2,2-tetrachlorethane greatly reduced, despite the fact that the conversion of EDC increases. This can be explained by the fact that during the pyrolysis of EDC on the generation stage free radical chain process of the hydrogen chloride formed an additional chlorine atom, and chlorethylene radical, as a source of additional adverse reactions disappear.

CH2Cl-CH2CL→CH2CL-CH2+CL

CH2CL-CH2+HCl→CH2CL-CH3+CL

The chlorine atoms play kluczewo the role in the development of free radical chain process.

Thus, the process of pyrolysis of EDC in the presence of hydrogen chloride can improve conversion and reduce the formation of by-products. The use of hydrogen chloride as an initiator (promoter) is very convenient because it is not a scarce product, soluble in EDC (about 15000 ppm wt.) and he, in turn, is the product of pyrolysis.

1. The method of producing vinyl chloride by gas-phase, thermal dehydrochlorination (pyrolysis) of 1,2-dichloroethane, wherein the process is carried out in the presence of initiator (promoter), which is hydrogen chloride, the concentration of which is 50-10000 ppm mass.

2. The method according to claim 1, characterized in that the pyrolysis takes place at temperatures 350-650°and pressures from atmospheric up to 40 bar (4mpa).

3. The method according to claim 1 or 2, characterized in that the residence time of the reaction mixture in the pyrolysis zone is 0.1-30 s



 

Same patents:

FIELD: chemical technology, in particular method for vinylchloride production.

SUBSTANCE: claimed method includes fast gas cooling in quenching column followed by separation of pyrolysis products. Quenching and separation are carried out by barbotage through the layer of liquid concentrated by-products of these gases in quenching column cube. Then steam/gas mixture is brought into contact with returning condensate in regular filling layer of rectification tower with simultaneous purification of steam/gas mixture in rectification zone upstream. Liquid concentrated by-products are additionally rectified in vacuum with isolating and recovery of products having boiling point higher than the same for dichloroethane and distillate recycling. Method of present invention also makes it possible to produce perchloroethylene and tricloroethylene.

EFFECT: vinylchloride of high quality; reduced effort and energy consumption.

2 tbl, 4 dwg, 2 ex

FIELD: chemical industry, in particular method for production of value monomer such as vinylchloride.

SUBSTANCE: claimed method includes passing of reaction mixture containing dichloroethane vapor trough catalytic layer providing dehydrochlorination of dichloroethane to vinylchloride. Catalyst has active centers having in IR-spectra of adsorbed ammonia absorption band with wave numbers in region of ν = 1410-1440 cm-1, and contains one platinum group metal as active component, and glass-fiber carrier. Carrier has in NMR29Si-specrum lines with chemical shifts of -100±3 ppm (Q3-line) and -110±3 ppm (Q4-line) in integral intensity ratio Q3/Q4 from 0.7 to 1.2; in IR-specrum it has absorption band of hydroxyls with wave number of ν = 3620-3650 cm-1 and half-width of 65-75 cm-1, and has density, measured by BET-method using argon thermal desorption, SAr = 0.5-30 m2/g, and specific surface, measured by alkali titration, SNa = 10-250 m2/g in ratio of SAr/SNa = 5-30.

EFFECT: method with high conversion ratio and selectivity.

3 cl, 2 ex

FIELD: chemical industry, in particular method for production of value products from lower alkanes.

SUBSTANCE: claimed method includes passing of gaseous reaction mixture containing at least one lower alkane and elementary chlorine through catalytic layer. Used catalyst represents geometrically structured system comprising microfiber with diameter of 5-20 mum. Catalyst has active centers having in IR-spectra of adsorbed ammonia absorption band with wave numbers in region of ν = 1410-1440 cm-1, and contains one platinum group metal as active component, and glass-fiber carrier. Carrier has in NMR29Si-specrum lines with chemical shifts of -100±3 ppm (Q3-line) and -110±3 ppm (Q4-line) in integral intensity ratio Q3/Q4 from 0.7 to 1.2; in IR-specrum it has absorption band of hydroxyls with wave number of ν = 3620-3650 cm-1 and half-width of 65-75 cm-1, and has density, measured by BET-method using argon thermal desorption, SAr = 0.5-30 m2/g, and specific surface, measured by alkali titration, SNa = 10-250 m2/g in ratio of SAr/SNa = 5-30.

EFFECT: method of increased yield.

3 cl, 4 ex

The invention relates to the production of parameningeal by alkylation of phenol, alpha-methylstyrene and the catalyst for this process
The invention relates to a technology for chlorohydrocarbons by the chlorination of olefins and subsequent separation of the products of chlorination on target and by-products, in particular to a method of rectification of a mixture of chlorinated propylene with obtaining allyl chloride of high purity
The invention relates to a technology for chlorohydrocarbons by the chlorination of olefins and subsequent separation of the products of chlorination on target and by-products, in particular to a method of rectification of a mixture of chlorinated propylene with obtaining allyl chloride of high purity

The invention relates to the processing of the products of oxidative pyrolysis gas metadatareader
The invention relates to the chemical industry and plastics

The invention relates to the production of vinyl chloride

The invention relates to a method for producing vinyl chloride by thermal pyrolysis of dichloroethane

FIELD: chemical industry, in particular method for production of value monomer such as vinylchloride.

SUBSTANCE: claimed method includes passing of reaction mixture containing dichloroethane vapor trough catalytic layer providing dehydrochlorination of dichloroethane to vinylchloride. Catalyst has active centers having in IR-spectra of adsorbed ammonia absorption band with wave numbers in region of ν = 1410-1440 cm-1, and contains one platinum group metal as active component, and glass-fiber carrier. Carrier has in NMR29Si-specrum lines with chemical shifts of -100±3 ppm (Q3-line) and -110±3 ppm (Q4-line) in integral intensity ratio Q3/Q4 from 0.7 to 1.2; in IR-specrum it has absorption band of hydroxyls with wave number of ν = 3620-3650 cm-1 and half-width of 65-75 cm-1, and has density, measured by BET-method using argon thermal desorption, SAr = 0.5-30 m2/g, and specific surface, measured by alkali titration, SNa = 10-250 m2/g in ratio of SAr/SNa = 5-30.

EFFECT: method with high conversion ratio and selectivity.

3 cl, 2 ex

FIELD: organic synthesis catalysts.

SUBSTANCE: catalyst is prepared from allyl chloride production wastes comprising 30-50% 1,3-dichloropropenes, 30-60% 1,2-dichloropropane, and 3-5% 1,2,3-trichloropropane, which are treated at 5-10°C with 30-50% dimethylamine aqueous solution in such amount as to ensure stoichiometric ratio of dimethylamine with respect to 1,3-dichloropropenes. Resulting mixture is held at 20-25°C for 0.5-1.0 h and then 40-44 sodium hydroxide solution is added in stoichiometric amount regarding dimethylamine, after which clarified waste is added to dimethylamine at 60-70°C and stirring in amount ensuring stoichiometric ratio of dimethylamine to 1,3-dichloropropenes contained in clarified waste. Mixture is aged for 2-3 h, organic phase is separated, and remaining interaction phase is supplemented by C1-C4-alcohol or benzyl alcohol at alcohol-to-dimethylamine molar ratio 1:(1-3).

EFFECT: reduced expenses on starting materials.

2 cl, 3 ex

The invention relates to cleaning and getting 1,1-dottorato, which is used for foaming plastics or as a propellant in aerosols

The invention relates to a method of processing organochlorine waste by method of hydrogenolysis
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The invention relates to a method for separation of the products of pyrolysis of dichloroethane in the production of vinyl chloride

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FIELD: organic synthesis catalysts.

SUBSTANCE: catalyst is prepared from allyl chloride production wastes comprising 30-50% 1,3-dichloropropenes, 30-60% 1,2-dichloropropane, and 3-5% 1,2,3-trichloropropane, which are treated at 5-10°C with 30-50% dimethylamine aqueous solution in such amount as to ensure stoichiometric ratio of dimethylamine with respect to 1,3-dichloropropenes. Resulting mixture is held at 20-25°C for 0.5-1.0 h and then 40-44 sodium hydroxide solution is added in stoichiometric amount regarding dimethylamine, after which clarified waste is added to dimethylamine at 60-70°C and stirring in amount ensuring stoichiometric ratio of dimethylamine to 1,3-dichloropropenes contained in clarified waste. Mixture is aged for 2-3 h, organic phase is separated, and remaining interaction phase is supplemented by C1-C4-alcohol or benzyl alcohol at alcohol-to-dimethylamine molar ratio 1:(1-3).

EFFECT: reduced expenses on starting materials.

2 cl, 3 ex

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