Process and plant for producing vinyl chloride from 1,2-dichloroethane

Abstract

The present invention relates to a method for producing vinyl chloride by catalytic pyrolysis of 1,2-dichloroethane, in which the heat required for the pyrolysis is supplied via a liquid or condensed heat-transfer medium (4), which is heated at least in part by thermal energy obtained when hydrogen (10), ammonia (11), or a hydrogen-ammonia mixture is oxidized. The present invention also provides a plant for producing vinyl chloride by catalytic pyrolysis of 1,2-dichloroethane, comprising at least one reactor (1) in which the pyrolysis takes place and at least one first heating device (6) for heating the reaction medium (13) in the reactor (1) by means of the heat-transfer medium (4), the at least one first heating device (6) being designed to oxidize the hydrogen (10) and / or ammonia (11), e.g., to combust the hydrogen (10) and / or ammonia (11), thereby generating thermal energy that can heat the heat-transfer medium (4).

Description

[Technical Field]

[0001] The present invention relates to a method for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane, in which the heat required for the thermal cleavage is supplied via a liquid or condensing heat transfer medium. The present invention also provides a plant for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane, in which the heat required for the thermal cleavage is supplied via a liquid or condensing heat transfer medium, the plant comprising at least one reactor in which the thermal cleavage occurs, at least one first heating device for heating the heat transfer medium, and a conduit system for supplying the heated heat transfer medium (4) to the reactor (1). The at least one first heating device operates on a fuel that burns without producing carbon dioxide, preferably hydrogen or ammonia or a mixture of hydrogen and ammonia, more preferably hydrogen. That is, the heat transfer medium is heated in the at least one first heating device by thermal energy generated by the oxidation of hydrogen or another fuel that burns without producing carbon dioxide.

[0002] The thermal cleavage of 1,2-dichloroethane to produce vinyl chloride, which is particularly needed for the production of polyvinyl chloride, follows the reaction scheme shown below.

[0003] C2H4Cl2 → C2H3Cl+HCl (1) This is an endothermic reaction that can be carried out under high pressures of 1 to 3 MPa, at temperatures of 450 to 600 °C, in the gas phase without a catalyst, along with pyrolysis, or in the presence of a catalyst that allows pyrolysis to be carried out at lower temperatures. [Background technology]

[0004] For example, European Patent Application Publication No. 0264065 describes a method for producing vinyl chloride by the uncatalyzed thermal cleavage of 1,2-dichloroethane. The 1,2-dichloroethane is heated in a first vessel and then transferred to a second vessel without further heating by vaporizing it under a lower pressure than in the first vessel. The gaseous 1,2-dichloroethane is then fed to a cracking furnace where cleavage into vinyl chloride and hydrogen chloride occurs. The temperature of the 1,2-dichloroethane upon leaving the second vessel is between 220 and 280°C. In the cracking furnace, the tubes in which the 1,2-dichloroethane undergoes thermal cleavage are heated by fossil fuels. In the radiant zone of the cracking furnace, the gaseous 1,2-dichloroethane is heated to 525 and 533°C, respectively.

[0005] EP 0264065 A1 also mentions that a temperature control medium can be used to preheat the liquid, fresh 1,2-dichloroethane, which in turn is heated in the convection zone of the cracking furnace by flue gases generated by the burners that heat the cracking furnace. Suitable temperature control media include heated high-boiling liquids such as mineral oil, silicone oil, and molten biphenyl. However, this only achieves preheating to a temperature of 150 to 220°C, while the pyrolysis itself is carried out at a temperature of approximately 530°C. Therefore, this known method does not provide for the pyrolysis to be carried out at temperatures in the range of 200 to 400°C, as required herein, and all heating using a liquid heat transfer medium.

[0006] A complex plant for producing vinyl chloride generally consists of:

[0007] - Plants for the production of 1,2-dichloroethane from ethene and chlorine ("direct chlorination"), or - Plants for the production of 1,2-dichloroethane from ethene, hydrogen chloride and oxygen ("oxychlorination"); - plants for the distillation and purification of 1,2-dichloroethane, - a plant for the thermal cleavage of distilled and purified 1,2-dichloroethane to vinyl chloride and hydrogen chloride, and -Plants for the distillative removal of hydrogen chloride and unreacted 1,2-dichloroethane and the purification of vinyl chloride.

[0008] The hydrogen chloride obtained by thermal cleavage of 1,2-dichloroethane can be returned to the oxychlorination plant where it can again be reacted with ethene and oxygen to produce 1,2-dichloroethane.

[0009] The above-mentioned complex may also include a plant for incinerating liquid and / or gaseous chlorinated hydrocarbons. These are produced as by-products in the vinyl chloride production process and are primarily removed during the distillation of 1,2-dichloroethane. The hydrogen chloride produced in the incineration of these substances is fed to other production processes as aqueous hydrochloric acid or similarly returned to the oxychlorination plant. The waste heat from the incineration is used in the existing steam generation process.

[0010] In the process for the cleavage of 1,2-dichloroethane to vinyl chloride and hydrogen chloride described in German Patent Application Publication No. 10252891, a catalyst is used that allows for a reduction in the operating temperature during endothermic cleavage. However, even in this process, the tubular reactor is fired with a primary energy carrier such as oil or gas, and the furnace is divided into a radiant zone and a convective zone. In the radiant zone, the heat required for pyrolysis is transferred to the reactor tubes primarily by radiation from the furnace walls, which are heated by burners. In the convective zone, the energy content of the hot flue gases leaving the radiant zone is utilized by convective heat transfer, allowing 1,2-dichloroethane to be preheated, vaporized, or superheated as a reactant in the pyrolysis reaction.

[0011] Various measures for energy conservation and / or heat recovery in plants for producing 1,2-dichloroethane are known in the prior art. Such measures significantly reduce operating costs and thus contribute to the economic efficiency of the plant and the reduction of its CO2 emissions. These include, for example, utilizing the heat of reaction from an exothermic reaction step to heat a heat sink in the process. WO 2014 / 108159 describes in detail various known measures for heat recovery in plants for producing vinyl chloride, citing corresponding references.

[0012] EP 0 225 617 A describes a method for producing vinyl chloride by thermal cleavage of 1,2-dichloroethane, which, in some cases, involves the recovery of waste heat from the flue gas of a fired cracking furnace by the production of steam. However, the relatively low flue gas temperatures mean that such a process is not very economical. The thermal cleavage of 1,2-dichloroethane also occurs at relatively high temperatures in this process. The reactants are first preheated to approximately 243°C, then partially vaporized by depressurization and partially vaporized by steam pressurization, and then thermally cleaved in a cracking furnace at temperatures of 435°C to 497°C without the use of a catalyst. Heating with heat transfer oil is not described and is not possible at these temperatures.

[0013] EP 0002021 A1 describes a process for the catalytic dehydrohalogenation of 1,2-dichloroethane to vinyl chloride using a Lewis acid-treated zeolite catalyst. When using such a catalyst, the reaction can be carried out at elevated pressures and temperatures in the range of 200°C to 400°C, thus significantly lower than conventional thermal decomposition of 1,2-dichloroethane. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] European Patent Application Publication No. 0264065 [Patent Document 2] DE 10252891 A1 [Patent Document 3] International Publication No. 2014 / 108159 [Patent Document 4] European Patent Application Publication No. 0225617 [Patent Document 5] European Patent Application Publication No. 0002021 Summary of the Invention [Problem to be solved by the invention]

[0015] It is an object of the present invention to provide an improved process for the production of vinyl chloride by the thermal cleavage of 1,2-dichloroethane in which reduced operating costs are realized. A further object of the present invention is to improve the CO balance of the process for producing vinyl chloride. [Means for solving the problem]

[0016] The above object is achieved by a method for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane of the type set out in the opening paragraphs and having the features of claim 1.

[0017] According to the present invention, the liquid or condensed heat transfer medium is heated at least in part, at least temporarily, by the thermal energy generated in the oxidation of hydrogen, ammonia, or an ammonia-hydrogen mixture. Such an operating mode is CO₂-neutral. The use of a catalyst for the thermal cleavage of 1,2-dichloroethane allows the temperature range in which the reaction occurs to be shifted to a sufficiently low temperature, more specifically to a range of about 200°C to about 400°C, so that the reactor can be heated by the heat transfer medium instead of the direct combustion of fossil fuels used in existing methods. Instead of a tubular cracking furnace, it is possible to use, for example, a shell-and-tube heat exchanger, in which the tubes are filled with a catalyst bed and the heat transfer medium flows through the shell space, preferably in a loop.

[0018] According to a preferred embodiment of the method of the present invention, at least part or all of the hydrogen to be oxidized is produced in an upstream electrolysis unit. The electrolysis unit can preferably be configured to carry out chlor-alkali electrolysis. The chlorine gas produced can then be used for direct chlorination in the vinyl chloride production process. Alternatively, the electrolysis unit can be configured for water electrolysis. In this case, the oxygen produced can be used in oxychlorination. Finally, the electrolysis unit can be configured for hydrogen chloride electrolysis. Preferably, the hydrogen chloride produced in the thermal cleavage of 1,2-dichloroethane is electrochemically cleaved and / or the chlorine gas produced is reused in the chlorination of ethene in the production process.

[0019] It is further advantageous that the heat required for the reaction is at least temporarily provided in part by heating the heat transfer medium by combustion of hydrogen and / or ammonia, while all of the heat required for the reaction can be provided by oxidation of hydrogen and / or ammonia.

[0020] It is also possible to heat the heat transfer medium, at least temporarily, partly by the thermal energy generated by the oxidation of hydrogen and / or ammonia and partly by the combustion of a fuel other than these fuels. In this preferred variant of the method, most of the heat required for the reaction is provided by a first heating device that can be heated by hydrogen and / or ammonia, but at least one second heating device that operates on a fuel other than the above-mentioned fuels is provided and can be used at least temporarily. In these cases, the first heating device can be inhibited or, if necessary, completely stopped for a certain period of time, or the heat transfer medium can be directed so that its flow bypasses the first heating device.

[0021] For example, the at least one second heating device may be designed as an incineration plant for incinerating liquid and / or gaseous chlorinated hydrocarbons, such as those produced as by-products in vinyl chloride production plants.

[0022] The use of a liquid or condensed heat transfer medium to provide the entire heat of reaction required for the pyrolytic cleavage of 1,2-dichloroethane is made possible by carrying out the reaction in the presence of a suitable catalyst, which allows for a significant reduction in reaction temperature compared to conventional processes that do not use a catalyst. When using such a catalyst, the reaction temperature can be reduced, for example, from temperatures of about 430°C to about 530°C, which are typical in conventional processes, to temperatures in the range of about 200°C to 400°C. Heating to temperatures in this range is possible, for example, when using heat transfer oil, or molten salts can also be used. Suitable catalysts include, for example, those listed in the above-mentioned European Patent Application Publication No. 0002021.

[0023] The process for purely thermal EDC cleavage (without catalyst in a pyrolysis furnace) or for thermocatalytic EDC cleavage (with the supply of heat and the use of a catalyst) usually consists of the following substeps:

[0024] - preheating liquid 1,2-dichloroethane to its vaporization temperature at a given pressure; - vaporizing preheated 1,2-dichloroethane; - 1,2-dichloroethane vapor may be superheated to the reaction temperature range (if the previous vaporization was not carried out within the reaction temperature range), - Carrying out the cleavage reaction (purely thermally or catalytically thermally) while supplying heat.

[0025] The present invention provides a method that allows for heating for the catalytic thermal cleavage reaction using a liquid or condensed heat transfer medium, as well as for upstream preheating, vaporization, or superheating of 1,2-dichloroethane using the heat transfer medium. It is not necessary for all of these steps to be heated by a heat transfer medium. The method of the present invention includes heating from at least one of the above substeps to any desired combination, and the individual substeps can be sequentially subdivided (in terms of equipment) into individual steps.

[0026] For the purposes of the present method, "heating" refers to the transfer of heat to the starting material 1,2-dichloroethane and / or the reaction mixture via a heat transfer medium. This allows the starting material 1,2-dichloroethane to be heated, vaporized, and / or superheated. Heat can be supplied to the reaction mixture in the reactor at a constant temperature level (isothermal reaction control). The reaction mixture can also be further heated, with the heat supplied by heating being used in part to supplement the heat required for the reaction and in part to further heat the reaction mixture. Finally, the heat supply to the reaction mixture via heating can be adjusted so that the sensible heat content of the reaction mixture is at least partially used to supplement the heat demand for the reaction, and the reaction mixture in the reactor is cooled compared to the reactor inlet temperature. Heating, and further heat transfer to the starting material 1,2-dichloroethane, can be carried out by a liquid heat transfer medium, accompanied by cooling / reducing the sensible heat content of the heat transfer medium, and / or by a condensed heat transfer medium previously vaporized by a heating device.

[0027] For the purposes of the method of the present invention, the heating devices for the heat transfer medium may be devices (heaters and / or evaporators or devices combining the functions of a heater and an evaporator) that can be heated by hydrogen, ammonia, or an ammonia-hydrogen mixture (first heating device) or a fossil fuel, such as heating oil or preferably natural gas (second heating device). Alternatively, they may be heat transfer devices (heaters and / or evaporators or devices combining the functions of a heater and an evaporator) that are heated by waste heat from a plant for incinerating by-products of a chemical plant, preferably a plant for incinerating by-products of a combined plant for the production of vinyl chloride. Such devices are well known to those skilled in the art.

[0028] Generally, the heat requirements of a plant for catalytic thermal cleavage of 1,2-dichloroethane can only be partially met by the incineration of by-products from a combined plant for the production of vinyl chloride. Therefore, in the preferred operating mode, the heat transfer medium is first heated by waste heat from the combustion of the by-products, and the remaining heat required is provided by the combustion of hydrogen, ammonia, or a hydrogen-ammonia mixture in the first heating unit.

[0029] According to a preferred embodiment of the method of the present invention, a liquid or condensed heat transfer medium is circulated in a loop comprising at least one first heating device operating by oxidation of hydrogen, ammonia or a hydrogen-ammonia mixture and a reactor for catalytic thermal cleavage of 1,2-dichloroethane, in which heat exchange occurs between the reaction medium and the heat transfer medium. The above-mentioned loop also preferably comprises at least one second heating device operating by combustion of at least one fuel different from the above-mentioned fuel.

[0030] According to a preferred embodiment of the method of the present invention, at least one first heating device and at least one second heating device are connected in series in a loop. In this case, the heat transfer medium flows through the conduit loop first through the second heating device and then through the first heating device located downstream of it. Alternatively, the flow through the two heating devices can be in opposite directions. Alternatively, the two heating devices can be arranged in a quasi-parallel connection, i.e., the conduit loop including the heating devices is connected such that the associated conduits can be closed, for example via valves, so that the heat transfer medium can flow through the second heating device without flowing through the first heating device, or vice versa, if necessary.

[0031] According to a preferred embodiment of the method of the present invention, the heat transfer medium circulates in the loop countercurrent to the flow of the reaction medium through the reactor. This variant is advantageous for efficient heat transfer. Alternatively, the heat transfer medium can flow cocurrently to the flow of the reaction medium.

[0032] According to a preferred embodiment of the method of the present invention, the second heating device is at least temporarily powered by waste heat from a plant for incinerating by-products of the vinyl chloride production plant. This variant has the advantage that the waste heat used essentially comes from plant components within the same plant complex, which means that the energy balance of the method can be improved.

[0033] In a preferred embodiment of the method of the present invention, the second heating device is permanently operated at full load. The remaining energy required for thermal cleavage can be supplied to the heat transfer medium by the first heating unit heated by hydrogen and / or ammonia. In this embodiment of the method, the second heating device is preferably permanently at operating temperature.

[0034] According to a preferred embodiment of the process of the present invention, the thermal cleavage of 1,2-dichloroethane is carried out in the temperature range of 200° C. to 400° C. This is a preferred temperature range that can be easily achieved with a liquid heat transfer medium, such as a heat transfer oil.

[0035] The present invention further provides a plant for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane, in which the heat required for the thermal cleavage of 1,2-dichloroethane and preferably also for preheating, vaporizing and / or superheating the 1,2-dichloroethane is supplied via a liquid or condensing heat transfer medium, said plant comprising at least one reactor in which the thermal cleavage takes place, at least one first heating device for heating the liquid heat transfer medium, and a conduit system for supplying the heated heat transfer medium to the reactor, wherein the at least one first heating device is designed for the oxidation of hydrogen and / or ammonia, i.e., heat can be generated by oxidation, preferably by combustion, of one of the above-mentioned fuels.

[0036] In this case, it is particularly preferred if the plant comprises at least one electrolysis unit upstream of the at least one first heating device, in particular an electrolysis unit for carrying out chlor-alkali electrolysis, water electrolysis or hydrogen chloride electrolysis, and the hydrogen produced is supplied to the at least one first heating device, optionally also after mixing with ammonia.

[0037] The plant may further include at least one second heating unit for heating the reaction medium, designed for the combustion of at least one fuel other than hydrogen and ammonia, such as methane, natural gas, and / or liquid and / or gaseous waste from a chemical plant. In this case, the heat transfer medium preferably flows first through the second heating unit. The remaining heat required for the cleavage of 1,2-dichloroethane and for preheating the 1,2-dichloroethane for vaporization and / or superheating can be provided by the first heating unit. The first heating unit can preferably be designed to be adjustable to achieve a predetermined final temperature within the heat transfer medium.

[0038] In a preferred development of the invention, the conduit system forms a heat transfer medium loop which includes a reactor and at least one first heating device operated with hydrogen, ammonia or a hydrogen-ammonia mixture.

[0039] According to a preferred variant of the invention, the heat transfer medium loop also includes at least one second heating device. In this case, the flow order is preferably such that the medium flows first through the second heating device. Therefore, the terms "first" and "second" heating devices referred to in this specification simply refer to functionally different types of heating devices and do not define the order in which the heat transfer medium flows through them.

[0040] In a preferred development of the invention, the first heating device and the second heating device are arranged in series or in parallel in the loop of the heat transfer medium.

[0041] According to a preferred variant of the invention, means are provided for transferring heat from the heat transfer medium to the reaction medium flowing through or present in the reactor.

[0042] In a preferred development of the invention, the reactor comprises a shell-and-tube heat exchanger, the tubes of which are filled with a catalyst bed and have a shell space through which a heat transfer medium flows, preferably circulating in a loop.

[0043] The invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0044] [Figure 1] 1 shows a schematic simplified plant diagram of a plant according to the invention for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane. [Figure 2] 1 shows a schematic diagram of a reactor with a shell-and-tube heat exchanger, the tubes of which are packed with a catalyst bed. DETAILED DESCRIPTION OF THE INVENTION

[0045] Reference is now made to the drawings used to explain in more detail exemplary embodiment variants of the method of the present invention. The depictions in Figures 1 and 2 are schematic and greatly simplified, showing only those plant components relevant to the context of the present invention. The plant comprises a reactor 1, to which a reactor inlet stream 2 of 1,2-dichloroethane (EDC) is supplied, for example, via at least one conduit, in which the 1,2-dichloroethane is thermally decomposed into vinyl chloride monomer (VCM) under the influence of heat, with the formation of vinyl chloride accompanied by the evolution of hydrogen chloride. The enumerated products of the method leave the reactor 1 in a reactor outlet stream 3.

[0046] Reactor 1 is incorporated into a loop 18 of heat transfer medium 4 formed by a conduit system 8 such that heat is supplied to reactor 1 via a liquid heat transfer medium, e.g., heat transfer oil, preferably flowing countercurrently to the reaction medium, thereby heating the reaction medium 13 (see FIG. 2 ) flowing through reactor 1 to a temperature of, e.g., 300° C. to 400° C., at which catalytic thermal cleavage of 1,2-dichloroethane to vinyl chloride occurs within reactor 1.

[0047] The loop 18 of the heat transfer medium 4 will be described in more detail below. The loop 18 of the heat transfer medium 4 includes a pump 5 for circulating the heat transfer medium 4 in the loop 18, downstream of which the heat transfer medium first flows through an optional second heating device 7 according to the teachings of the present invention, and when the second heating device 7 is operating, the heat transfer medium 4 can be heated by at least one fuel other than hydrogen and / or ammonia, for example methane, natural gas and / or the combustion of liquid and / or gaseous waste from a chemical plant, or by thermal energy from the waste heat of a chemical plant, for example from a vinyl chloride production plant.

[0048] Downstream of the second heating device 7, the heat transfer medium 4 flows through a first heating device 6, which is combusted with hydrogen 10, ammonia 11, or an ammonia-hydrogen mixture to heat the heat transfer medium 4. As shown in Figure 1, the hydrogen 10 used for heating can be produced, for example, in an upstream electrolysis unit 9. The electrolysis unit 9 can preferably be configured to perform chlor-alkali electrolysis, water electrolysis, or hydrogen chloride electrolysis.

[0049] In the exemplary embodiment, the second heating device 7 and the first heating device 6 are arranged one behind the other in the direction of flow within the conduit system 8 of the loop 18 and are therefore connected in series. However, alternatively, the two heating devices can also be connected in parallel with each other, i.e., unlike in Figure 1, the two heating devices are integrated into the conduit system 8 in such a way that the heat transfer medium 4 flows through at least one or the other of the two heating devices while bypassing the other heating device.

[0050] In the variant shown in FIG. 1 in which two heating devices 6 and 7 are arranged in series, as well as in variants with a parallel connection not shown, valves not shown in FIG. 1 may be provided for switching the heating devices on and off or for blocking the conduits in loop 18 at appropriate locations. In addition, one or more regulating devices (also not shown in FIG. 1) may be provided for regulating the heat power supplied by the first and / or second heating devices 6 and 7 according to the heating requirements of the reaction medium in reactor 1.

[0051] The variant of the invention shown in Figure 1 may further comprise a device 19 capable of preheating, vaporizing and superheating the reactor inlet stream 2 by means of the heat content of the flow of heat transfer medium 4, although these options do not necessarily have to be implemented all together but can be implemented in any combination. The device 19 is arranged in the loop of the heat transfer medium, preferably downstream of the reactor 1. [Explanation of symbols]

[0052] 1. Reactor 2. Reactor inlet flow 3. Reactor Outlet 4 Heat Transfer Media 5 Recirculation Pump 6. First heating device 7 Second heating device 8. Pipeline System 9. Electrolysis Unit 10 Hydrogen 11 Ammonia 12 Heat Transfer Means 13 Reaction medium 14 Shell and tube heat exchanger 15 tubes 16 Catalyst bed 17 Shell Space 18 Loops 19 Apparatus for preheating and / or vaporization and / or superheating

Claims

1. 1. A process for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane, characterized in that the heat required for said catalytic thermal cleavage is supplied via a heat transfer medium that is a liquid or condensed heat transfer medium (4), said heat transfer medium (4) being heated at least in part, at least temporarily, by thermal energy produced in the oxidation of hydrogen (10), ammonia (11) or a hydrogen-ammonia mixture.

2. 2. The method of claim 1, wherein at least part or all of the hydrogen (10) to be oxidized is produced in an upstream electrolysis unit (9).

3. 3. The method according to claim 1, wherein the oxidation of the hydrogen (10) and / or the ammonia (11) is carried out by combustion of the hydrogen (10) and / or the ammonia (11).

4. 2. The method according to claim 1, characterized in that the 1,2-dichloroethane is preheated and / or vaporized and / or superheated by the heat transfer medium (4).

5. 2. The method according to claim 1, characterized in that the heat transfer medium (4) is at least temporarily heated partly by thermal energy generated by the oxidation of hydrogen (10) and / or ammonia (11) and partly by combustion of a fuel different from hydrogen and ammonia, or the heat transfer medium is heated completely by thermal energy generated by the oxidation of hydrogen (10) and / or ammonia (11).

6. 2. The method according to claim 1, characterized in that at least one first heating device (6) operating by oxidation of hydrogen (10) and / or ammonia (11) and further at least one second heating device (7) operating by combustion of at least one fuel different from hydrogen and ammonia are used to heat the liquid heat transfer medium (4).

7. 7. The method according to claim 6, characterized in that the heat transfer medium (4) is circulated in a loop (18), the loop (18) comprising the at least one first heating device (6) and a reactor (1) for the catalytic thermal cleavage of 1,2-dichloroethane, and heat is exchanged between the reaction medium (13) in the reactor (1) and the heat transfer medium (4).

8. 8. A method according to claim 7, characterized in that said loop (18) includes said second heating device (7).

9. 8. The method according to claim 7, characterized in that the at least one first heating device (6) and the at least one second heating device (7) are connected in series within the loop (18).

10. 8. The method according to claim 7, characterized in that the heat transfer medium (4) circulates in the loop (18) countercurrent to the flow of the reaction medium (13) through the reactor (1).

11. 2. The method of claim 1, wherein the catalytic thermal cleavage of the 1,2-dichloroethane is carried out in a temperature range of 200°C to 400°C.

12. 1. A plant for producing vinyl chloride by catalytic thermal cleavage of 1,2-dichloroethane, wherein the heat required for the catalytic thermal cleavage of 1,2-dichloroethane is supplied via a heat transfer medium, which is a liquid or condensed heat transfer medium (4), the plant comprising at least one reactor (1) in which the catalytic thermal cleavage takes place, at least one first heating device (6) for heating the heat transfer medium (4), and a conduit system (8) for supplying the heated heat transfer medium (4) to the reactor (1), characterized in that the at least one first heating device (6) is designed for the oxidation of hydrogen (10) and / or ammonia (11).

13. 13. The plant of claim 12, wherein the heat is further required for preheating, vaporizing and / or superheating the 1,2-dichloroethane.

14. 14. Plant according to claim 12 or 13, characterized in that the at least one first heating device (6) is designed for the combustion of hydrogen (10) and / or ammonia (11).

15. 14. A plant according to claim 12 or 13, characterized in that the plant comprises at least one electrolysis unit (9) upstream of the at least one first heating device (6), and hydrogen (10) produced in the electrolysis unit (9) is supplied to the at least one first heating device (6).

16. 14. Plant according to claim 12 or 13, characterized in that the plant further comprises at least one second heating device (7) for the combustion of at least one fuel different from hydrogen and ammonia for heating the heat transfer medium (4).

17. 17. The plant of claim 16, wherein the at least one fuel comprises methane, natural gas, and / or liquid and / or gaseous waste from a chemical plant.

18. 17. The plant according to claim 16, characterized in that the conduit system (8) circulates the heat transfer medium (4) in a loop (18) including the reactor (1) and the at least one first heating device (6).

19. 19. Plant according to claim 18, characterized in that said loop (18) comprises said at least one second heating device (7).

20. 17. The plant according to claim 16, characterized in that the at least one first heating device (6) and the at least one second heating device (7) are arranged in series or in parallel in the loop (18) of the heat transfer medium (4).

21. 14. A plant according to claim 12 or 13, characterized in that means (12) are provided for transferring heat from the heat transfer medium (4) to a reaction medium (13) flowing through the reactor (1).

22. 14. A plant according to claim 12 or 13, characterized in that the reactor (1) comprises a shell-and-tube heat exchanger (14) whose tubes (15) house a flow-through catalyst bed (16).

23. 23. A plant according to claim 22, characterized in that the heat transfer medium (4) flows through the shell space (17) of the reactor (1).

24. 14. The plant according to claim 12 or 13, characterized in that at least one device (19) for preheating and / or vaporizing and / or superheating the 1,2-dichloroethane is integrated into the conduit system (8) of the heat transfer medium (4).

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