Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/013—Preparation of halogenated hydrocarbons by addition of halogens
  • C07C17/02—Preparation of halogenated hydrocarbons by addition of halogens to unsaturated hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/25—Preparation of halogenated hydrocarbons by splitting-off hydrogen halides from halogenated hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C19/00—Acyclic saturated compounds containing halogen atoms
  • C07C19/01—Acyclic saturated compounds containing halogen atoms containing chlorine
  • C07C19/043—Chloroethanes
  • C07C19/045—Dichloroethanes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C21/00—Acyclic unsaturated compounds containing halogen atoms
  • C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
  • C07C21/04—Chloro-alkenes
  • C07C21/06—Vinyl chloride
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

• the present invention relates to a new process for the production of liquid 1,2-dichloroethane (hereinafter referred to as DCE) obtained by the direct cold chlorination of ethylene with chlorine in the presence of a Lewis acid catalyst. , allowing to obtain by direct evaporation, after separation of the catalyst, pure quality DCE for cracking (thermal cracking) in Vinyl Chloride monomer (VCM).
• DCE liquid 1,2-dichloroethane
• VCM Vinyl Chloride monomer
• the invention also relates to an installation for its implementation.
• the two main industrial processes for producing DCE are: the cold direct chlorination process (at a temperature of less than or equal to 80 ° C.) from ethylene and chlorine and at a pressure of 1 to 2 bar, particularly in a loop reactor, in the presence of a FeCb-based catalyst formed in situ; the reaction takes place in liquid DCE in the presence of dissolved IC2.
• the crude DCE is distilled in several columns to reach the required purity (> 99.5%) for cracking; and the process by high-temperature chlorination (temperature above 80 ° C.), from ethylene and chlorine, and under a pressure such that the product EDC can be directly recovered in the gas phase (free from the catalyst) or by boiling, either by relaxation; however, the DCE obtained under these conditions requires generally complementary distillation steps to achieve pure quality for cracking.
• DE 33 47 153 discloses a process for producing DCE by direct cold chlorination from ethylene and chlorine, in the presence of a FeCb and amine catalyst, wherein the product obtained is passed through a column. in order to obtain DCE with a purity of 99.9%, a part of the column foot containing catalyst being recycled to the reactor. The distillation step is not avoided.
• WO 96/03361 or EP 772 576 discloses a method and a device for the production of DCE by direct chlorination from ethylene and chlorine, in the presence of a catalyst based on FeCb and NaCl; the main stream of DCE leaving the reactor is recycled to the latter, while part of the DCE is vaporized by expansion, the vapor part being free of catalyst and having after condensation and recovery of its vaporization heat a purity of minus 99.9%, while the liquid portion of DCE (at the expander) is recycled to the reactor.
• the exemplary embodiment indicates a chlorination temperature of 90 ° C., so it is not a question of cold direct chlorination.
• WO 01/21564 or EP 1 214 279 discloses a method of heat recovery during the production of DCE by direct high temperature chlorination from ethylene and chlorine; the DCE vapors leaving the reactor are compressed and serve to feed evaporators of drying columns and / or distillation of the DCE or heat exchangers. This is not cold direct chlorination.
• the document EP 0795 531 in the name of the applicant describes a process for converting light by-products having a boiling point very close to that of the DCE (83.7 ° C. at atmospheric pressure) formed during thermal cracking. of the DCE, in which the chlorination of said light by-products is carried out directly after the direct chlorination reactor, in the presence of the products of this reactor, at a temperature of between 20 ° C. and 80 ° C., with molecular chlorine. This is not cold direct chlorination.
• the document DE 199 16 753 or EPl 044950 describes in a process for the production of DCE by direct chlorination at a temperature of between 75 and 125 ° C., from ethylene and chlorine, with recovery of the heat of chlorination reaction, for to heat DCE distillation columns from oxychlorination and craniality. No indication is given on the treatment of DCE obtained by direct chlorination and it is not a question of cold direct chlorination.
• Another problem is that it is necessary to work in excess of chlorine to reach a good productivity (from 500 to 1500 ppm of IC2 dissolved in the DCE) and with a low level of energy, which forbids to use any process of obtaining good DCE for cracking by simple expansion of the mixture leaving the reactor.
• the dechlorination step allows removal of the excess chlorine dissolved in the DCE stream leaving the direct chlorination reactor.
• the stages of evaporation and condensation can be achieved by the implementation of energy saving systems, such as mechanical vapor compression or multi-effect evaporation, with considerable reductions in steam consumption.
• Another advantage of this process is that the thus separated catalyst can be recycled to the chlorine direct chlorine reactor, then operating with a lower excess of chlorine, resulting in less reactor corrosion, an improvement in the quality of the raw DCE coming out of it, as well as an improvement in productivity.
• Another advantage is that a purge of the recycled DCE containing the catalyst can also be used to improve the chlorination of the light by-products formed during thermal cracking of the DCE.
• this method has the advantage of being able to integrate into a project to improve or increase the capacity of an existing installation, by releasing capacity on the distillation train in place, in a relatively simple way, and by decreasing aqueous effluents from the washing of raw DCE.
• the subject of the present invention is a process for the production of liquid 1,2-dichloroethane (DCE), obtained by cold direct chlorination of ethylene, the presence of a Lewis acid catalyst, which makes it possible, after separation of the catalyst, to obtain DCE of sufficient purity to give by cracking vinyl chloride monomer (VCM); characterized in that it comprises a step of dechlorination of the flow of liquid DCE leaving the chlorination reactor, making it possible to eliminate the excess dissolved chlorine, followed by a step of direct evaporation on the entire flow of liquid DCE exiting of the reactor, allowing the catalyst to be separated from the evaporated fraction of the DCE stream for cracking.
• DCE 1,2-dichloroethane
• the dechlorination step allowing removal of the excess chlorine dissolved in the liquid DCE stream leaving the direct chlorination reactor, is carried out either by chemical reaction by introduction of ethylene into this flow of liquid DCE, either by stripping with an inert gas.
• the liquid DCE is brought to a vaporization temperature of between 75 ° C. (under a pressure of 0.77 bar, ie 0.077 MPa) and 120 ° C. (under a pressure of 2.8 bar or 0.28 MPa), and preferably at a temperature of about 84 ° C. under a pressure of 1 bar (0.1 MPa).
• the DCE vapors undergo mechanical compression, preferably at a pressure ranging from 1.1 to 2.8 bar (ie 0.1 to 0.28 MPa), and more particularly at about 1.6 bar (0.16 MPa) and a condensation at a temperature between 85 and 120 0 C, and more particularly at about 106 0 C, for recovering the condensation energy.
• This energy can be advantageously used for the vaporization of the DCE.
• the evaporation and condensation stages of the DCE are carried out in particular by heat exchangers of the multi-effect type.
• the evaporation and condensation steps are continued by a secondary purification step of the DCE.
• this secondary treatment step of the DCE allows the separation of light compounds such as ethylene and ethyl chloride, which can have an adverse effect, depending on the conditions of cracking, for the thermal cracking of the liquid fraction of DCE purified good for cracking.
• a portion of the DCE liquid fraction of the catalyst-enriched evaporation foot is used for the chlorination of the light by-products obtained in the DCE cracking step.
• light by-products include unsaturated aliphatic hydrocarbons, such as benzene, chloroprene or trichlorethylene. These products are difficult to separate from the DCE by distillation.
• the Lewis acid type catalyst is based on ferric chloride (FeCl 3).
• the present invention also relates to an installation for carrying out the process described above, which comprises, after a cold direct chlorination reactor (1) fed with chlorine (2) and ethylene (3), a dechlorination capacity (5). ) by introducing ethylene (6) into the flow of raw liquid DCE (4) leaving the reactor, followed by an evaporation device (9), the inlet (8) of which is fed with all of said flow of Dechlorinated liquid DCE exiting said reactor (1), whose outlet (1 1) corresponds to the liquid DCE, concentrated in catalyst, which is recycled wholly or partly (12) to the reactor (1), and whose outlet (10) corresponds to the vaporized DCE good for cracking.
• the evaporation device (9) consists of any device comprising a heat exchanger providing the necessary energy for vaporizing the DCE.
• a device comprising a compressor operating at a discharge pressure of between 1.1 and 2.8 bar (ie between 0.1 and 0.28 MPa), and in particular of about 1, 6 bar (0.16 MPa).
• the evaporation (9) and condensation (15) devices comprise a series of multi-effect type heat exchangers.
• the flow of liquid DCE and gas (18) leaving the condensation device (15) undergoes treatment in a secondary purification device (19), comprising in particular at least one distillation or stripping column. inert gases, to remove gases (21) such as ethylene, hydrogen chloride and ethyl chloride and to provide even more pure DCE (20) for cracking.
• a portion (13) of the concentrated liquid DCE catalyst (1 1) from the evaporation device (9) is introduced into a chlorination reactor (14) of the sub- light products (17) from the DCE cracking step in CVM, with chlorine feed (16), whose products (22) after washing and distillation make it possible to recover pure DCE.
• the gains obtained in vapor saving because the DCE resulting from direct chlorination no longer crosses the traditional distillation columns are much higher than the expenditures in electricity due to the compressor.
• DCE 1,2-dichloroethane
• the outflow (4), flow 59862 Kg / h, of said reactor (1) comprises raw DCE, mixed with FeCb chlorine, ethyl chloride and 1, 1, 2-trichloroethane (Tl 12).
• This flow (4) is then sent into a dechlorination capacity (5) with introduction of ethylene (6), flow rate 64 Kg / h, a portion of the non-consumed ethylene being extracted in (7) with DCE at tension of steam, flow rate OKg / h, and recycled to a chlorination unit of "light" by-products (14), which will be detailed below.
• the flows in DCE, C2H4, EtCI and Tl 12 are respectively 48635 - 44 - 8 - and 39 kg / h; the assembly is then sent to a secondary purification device (19) comprising in particular a distillation column or stripping by inert gases, to eliminate the gases (21) such as ethylene whose flow is 44 Kg / hr and ethyl chloride, flow rate 7Kg / h, and provide pure DCE (20) for cracking, at a flow rate of 47593 Kg / h.
• gases (21) such as ethylene whose flow is 44 Kg / hr and ethyl chloride, flow rate 7Kg / h, and provide pure DCE (20) for cracking, at a flow rate of 47593 Kg / h.
• the chlorination unit for "light” by-products (14) is fed by a so-called purge part (13) coming from the evaporation device (9) of the DCE, flow rate 1994 kg / h, containing FeCl3, 840 ppm , and of Tl 12, flow rate Kg / h, as well as by IC2 (16), flow rate 200 Kg / h, and light compounds (17), flow rate 3000 Kg / h, resulting from the step of cracking of the DCE in CVM after passing through a distillation column; the products (22) leaving this unit after washing and distillation make it possible to recover good DCE for cracking.
• the produced DCE is recovered by overflow, then it is dechlorinated by a stripping with nitrogen and finally it is sent towards a heated evaporator: the DCE evaporated then recondensed represents the production, the foot of the evaporator is either stored or sent towards chlorinator.
• the test takes place in two stages:
• First step duration of 1 1 Oh without recycling of the foot of the evaporator to the chlorinator
• Second step duration of 392h with recycling of the foot of the evaporator to the chlorinator.
• the FeCb content in the chlorinator gradually increases to reach 380 ppm at the end of the test.
• the effect of the iron content is sensitive from the beginning of the recycling: to maintain the content of 1% of ethylene in the vents, 600 ppm of chlorine dissolved in the chlorinator must be worked.
• Table 1 below shows the composition of the chlorinator during the test and the purity of the DCE produced by the process (determined by gas chromatography: GC, expressed in% by weight), with the content of T112, expressed in% weight.
• the purity of the DCE is stable and corresponds to that of the DCE good for cracking.

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• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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• 2006
  • 2006-07-13 FR FR0652951A patent/FR2903685B1/fr not_active Expired - Fee Related
• 2007
  • 2007-06-14 US US12/373,338 patent/US20110034870A1/en not_active Abandoned
  • 2007-07-10 EP EP07804005A patent/EP2041052A2/de not_active Withdrawn
  • 2007-07-10 CN CNA2007800263556A patent/CN101563307A/zh active Pending
  • 2007-07-10 US US12/373,388 patent/US20100036180A1/en not_active Abandoned
  • 2007-07-10 KR KR1020087032185A patent/KR101076248B1/ko not_active IP Right Cessation
  • 2007-07-10 WO PCT/FR2007/051629 patent/WO2008007012A2/fr active Application Filing

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