EP1503975A2

EP1503975A2 - Method for producing unsaturated halogenic hydrocarbons and device suitable for use with said method

Info

Publication number: EP1503975A2
Application number: EP03732303A
Authority: EP
Inventors: Michael Benje; Horst Ertl; Ingolf Mielke; Thomas Wild; Peter Kammerhofer; Peter Schwarzmaier
Original assignee: Uhde GmbH
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 2002-05-02
Filing date: 2003-04-30
Publication date: 2005-02-09
Also published as: RU2316533C2; HK1080068A1; DE10219723B4; JP2006510573A; AU2003239827A8; WO2003093207A3; AU2003239827A1; CN1653022A; RU2004135106A; DE10219723A1; JP4804750B2; US7309471B2; NO20045273L; WO2003093207A2; CA2483981A1; US20050124835A1; ZA200408235B; CN100343208C

Abstract

The invention relates to a method for producing ethylenically unsaturated aliphatic halogenic hydrocarbons by the thermal cleavage of saturated aliphatic halogenic hydrocarbons. According to said method, an educt gas stream is introduced into a reactor, which comprises at least one supply conduit that opens into said reactor. The supply conduit feeds a heated gas formed from cleavage promoters and radicals into the reactor. The method permits an increase in the yield of the cleavage reaction.

Description

description

Process for the production of unsaturated halogenated hydrocarbons and device suitable therefor

The present invention relates to a method for producing unsaturated halogen-containing hydrocarbons from saturated halogen-containing hydrocarbons and to a device which is particularly suitable for carrying out the method. A preferred process relates to the production of vinyl chloride (hereinafter also referred to as "NC") from 1,2-dichloroethane (hereinafter also referred to as "DCE").

The incomplete thermal cleavage of DCE to obtain VC has been carried out on an industrial scale for many years. Cracking furnaces are used in which the DCE is partially split into VC and hydrogen chloride at furnace inlet pressures of 0.8 to 4 MPa and at temperatures of 450 to 550 ° C. Typical gap conversions are around 55 mol% of the DCE used.

The process requires considerable amounts of energy for the various process steps, such as heating the DCE to the gap temperature, the reaction itself and the subsequent purification of the product mixture. A group of measures aimed at improving the economics of the process aims at

Energy recovery from, for example, as proposed in EP-B-276,775, EP-A-264,065 and DE-A-36 30 162.

A further improvement in the economics of the process could consist in striving for the highest possible turnover in the cleavage reaction. For this purpose, so-called gap promoters (hereinafter also referred to as "pyrolysis promoters") have already been added to the reactant gas. These are compounds which, under the conditions prevailing in the reactor, become free radicals disintegrate and intervene in the chain reaction that leads to the formation of the desired products. The use of such compounds is known, for example, from US-A-4,590,318 or DE-A-3,328,691.

Further processes in which cracking promoters are used in the pyrolysis of DCE are known from WO-A-96 / 35,653, US-A-4,584,420, US-A-3,860,595, DE-A-1, 952,770 and DE -A-1, 953,240. All these processes have in common that these cracking promoters are added to the gas mixture to be cracked and that radicals are generated from them by thermal decomposition. This is a step of radical generation upstream of the addition of the gap promoters

State of the art cannot be inferred.

The older and not previously published WO-A-02 / 94,743 describes a method and an apparatus for carrying out free radical gas phase reactions. Thereby, a by thermal decomposition of gap promoters in an upstream

Gas containing radicals generated outside the reactor is introduced into the reactor.

From WO-A-00 / 29,359 it is additionally known that the service life of the catalyst can be extended by the presence of hydrogen. The hydrogen is mixed with the feed gas here.

It has also already been proposed to mix a feed gas containing DCE with a hot particle and / or gas stream or a hot gas stream and to use the heat transferred from the latter for the pyrolysis of EDC.

In the process described in US Pat. No. 5,488,190, the pyrolysis of the reactant gas in a cracking furnace is replaced by what is known as ultrapyrolysis, in which the hot particles or gases transfer their energy to the reactant gas as quickly as possible and in which the pyrolysis is carried out within less than a quarter of a second. This document also suggests the name

Adding particle promoters or gases to gap promoters. The heat of reaction for the cleavage of the DCE is completely introduced into the reaction zone by the injected hot medium. Furthermore, it has already been proposed to split DCE into radicals with the aid of laser light and to use them in radical chain reactions, such as for the preparation of vinyl chloride. Examples of this can be found in SPIE, Vol. 458 Applications of Lasers to Industrial Chemistry (1984), pp. 82-88, in Umschau 1984, number 16, p. 482 and in DE-A-2,938,353, DE-C-3,008,848 and EP-A-27,554. To date, this has

However, technology has not found its way into industrial production. One reason may be that the reactors proposed so far are not suitable for continuous operation.

With the present invention, a method is provided which a

Compared to conventional methods, prolonged continuous operation of a cracking furnace is permitted.

In comparison to the known processes, according to the invention, starter radicals are generated from fission promoters by means of non-thermal or thermal decomposition in one or more spatially limited areas inside or outside the reactor, but separately from the actual fission reaction, which in a subsequent step are characterized by the Reactor moving gas stream can be initiated. The subsequent thermal cleavage of the starting material is promoted by the provision of increased concentrations of starter radicals in spatially limited areas of the reactor interior. In addition, such conditions are used in the generation of the starter radicals that the formation of coke is minimized.

An object of the present invention is to provide a pyrolysis process of halogen-containing aliphatic hydrocarbons, with which larger conversions are possible compared to conventional processes at an otherwise identical operating temperature or with which a lowering of the operating temperature is possible compared to conventional processes with otherwise identical conversions.

It has now been found that by introducing small amounts of gases containing starter radicals into the reactor an increase in the Product yield in the continuous pyrolysis can be achieved without having to add large amounts of these gases.

In one embodiment (hereinafter referred to as "variant I"), the present invention relates to a process for the production of ethylenically unsaturated halogen-containing aliphatic hydrocarbons by thermal cleavage of saturated halogen-containing aliphatic hydrocarbons, comprising the measures: a) introducing a feed gas stream containing heated gaseous halogen-containing aliphatic hydrocarbon into one Reactor, in the interior of which at least one supply line for a gas opens, b) introducing a heated gas, which contains radicals generated by thermal or non-thermal decomposition of gap promoters, through the at least one supply line opening into the reactor, the heated gas being generated of radicals through thermal

Decomposition has at least the temperature which corresponds to the temperature of the reaction mixture in the reactor at the point of the mouth of the feed line and the heated gas in the case of the generation of the radicals by non-thermal decomposition has at least the temperature which is the temperature of the dew point of the reaction mixture corresponds to the point of the mouth of the feed line in the reactor, and c) setting such a pressure and such a temperature inside the reactor so that hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon are formed by thermal cleavage of the halogen-containing aliphatic hydrocarbon, with the proviso that that in the case of radical generation by thermal decomposition, this is done by heating a gas containing diluted inert promoters or by passing a containing a promoter

Gases over a heat source, the surface of which is flushed with inert gas.

In a further embodiment (hereinafter referred to as "variant II") relates The invention relates to a process for the production of ethylenically unsaturated halogen-containing aliphatic hydrocarbons by thermal cleavage of saturated halogen-containing aliphatic hydrocarbons, comprising the measures: a) introducing a feed gas stream containing heated gaseous halogen-containing aliphatic hydrocarbon into a reactor, in the interior of which there is at least one feed line for a heated and cracked promoter Gas flows, d) thermal or non-thermal generation of radicals from fission promoters by means of a suitable device within a predetermined volume inside the reactor, e) introducing the heated gas and fission promoters containing gas through the feed line into the predetermined volume, the heated gas in the case of generation of the radicals by thermal decomposition has at least the temperature which is the temperature of the reaction mixture prevailing at the point of the mouth of the feed line ches in the reactor, and wherein the heated gas in the case of the generation of radicals by non-thermal decomposition has at least the temperature which corresponds to the temperature of the dew point of the reaction mixture at the location of the mouth of the feed line in the reactor, and c) adjusting such Pressure and such a temperature inside the reactor, so that hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon are formed by thermal cleavage of the halogen-containing aliphatic hydrocarbon.

The method according to the invention is described using the DCE / VC system as an example. It is also suitable for the production of other halogen-containing unsaturated hydrocarbons from halogen-containing saturated hydrocarbons. All these reactions have in common that the cleavage is a radical chain reaction in which, in addition to the desired product, undesired by-products are formed, which lead to coking of the plants in continuous operation. The production of vinyl chloride from 1,2-dichloroethane is preferred.

Any gas that contains radicals derived from gap promoters can be used as the heated gas for introduction into the feed gas stream via the feed line (s).

In variant I of the process according to the invention, radicals are formed from gap promoters in the feed line to the reactor, preferably shortly before the feed line opens into the reactor. The feed line can open into the reactor wall or preferably into the interior of the reactor in order to avoid wall reactions of the radicals generated. In this variant, the radical generating device is located in the feed line or preferably at the end of the reactor and the radicals formed are fed into the reactor through the feed line.

According to variant II of the method according to the invention, the gas containing the gap promoters is fed via a feed line into a predetermined volume of the reactor interior and the gap promoters are split into radicals there by the action of a radical generating device. The feed line can also open into the reactor wall or preferably into the

Inside of the reactor to prevent recombination of the generated radicals on the reactor wall. In this variant, the supply line and

The radical generating device is separated from one another and the radicals are formed in the interior of the reactor by the action of the radical generating device.

For both variants of the method according to the invention, it may also be appropriate to install a further feed line near the mouth of the feed line for the radical or gas containing cracking promoters, through which heated inert gas can be introduced into the area of the reactor into which the radicals can be initiated or in which radicals are generated from the gap promoters. This inert gas is used to dilute the reactive components and to prevent coke deposits from forming. Examples of gap promoters are known per se. These are usually halogen-containing, preferably chlorine-containing compounds or molecular oxygen. Examples of this can be found in the already mentioned US-A-4,590,318 and DE-A-3,328,691. Under the special conditions of the process according to the invention, DCE, for example, is also to be regarded as a promoter of the pyrolysis reaction, since, for example, at elevated temperatures which are set for thermal radical generation, it breaks down into radicals which promote the further course of the pyrolysis reaction. Furthermore, these radicals can also be generated by non-thermal decomposition of the DCE, for example by means of electrical discharges or photolytically.

Preferred cleavage promoters are molecular chlorine, nitrosyl chloride, trichloroacetyl chloride, chloral, hexachloroacetone, benzotrichloride, monochloromethane, dichloromethane, trichloromethane, carbon tetrachloride or hydrogen chloride.

The gas to be introduced and containing cracking promoters or radicals generated therefrom may also contain inert gas and / or gases which are constituents of the reaction system.

Examples of inert gases are among those in the reactor

Inert gases such as nitrogen, noble gases, e.g. Argon, or carbon dioxide.

Examples of gases which are components of the reaction system are hydrogen chloride or dichloroethane.

Since the introduction of the radical-containing gas should not reduce the temperature in the reactor, it is advisable to select the temperature of gases containing non-thermally generated radicals at least so high that they at least match the temperature of the gas flow at the point where the feed line opens into the

Reactor corresponds, while the temperature of gases containing thermally generated radicals is usually considerably higher than the temperature of the gas stream at the point of entry of the feed line into the reactor. When the radicals are generated by non-thermal decomposition, it is also possible for the gas containing radicals or gap promoters, which is heated and to be introduced into the reactor, to have a temperature which is below the temperature of the reaction mixture at the point where the feed line opens into the reactor , However, it is necessary that the temperature of the gas containing radicals or crack promoters, heated and introduced into the reactor has at least the temperature of the dew point of the reaction mixture at the point of the mouth of the feed line in the reactor.

The gas to be introduced is preferably heated only shortly before it is introduced or injected into the feed gas stream. Typical temperatures of the gas to be introduced are in the range from 250 to 1500 ° C., preferably 300 to 1000 ° C.

Typical temperatures of the educt gas flow are in the range from 250 to 500 ° C.

The effect caused by the gas introduced is dependent not only on the selected temperature but also on the nature of the gas and also on its quantity. Usually a total of not more than 10% by weight, preferably not more than 5% by weight, particularly preferably 0.0005 to 5% by weight, based on the

Total mass flow in the reactor.

Typically, more than 90%, preferably more than 95%, of the required heat of reaction is supplied by heating the reactor walls, while the heat supplied by the hot, radical-containing gas in the case of thermal

Radical generation for upstream decomposition of the promoter substance is used. In the case of non-thermal radical generation, the heat supplied by the hot radical-containing gas serves to keep its temperature above the dew point temperature of the reaction mixture at the point of introduction.

It is believed that the introduction of a heated gas containing radicals promotes the radical chain reaction in the reactant gas, which ultimately leads to an increased Concentration of radicals and an increased turnover in the cleavage reaction leads.

All devices known to the person skilled in the art for this purpose can be used as supply lines for the heated gas containing radicals. Examples of this are pipelines which open into the reactor and which preferably have a nozzle at their end on the reactor side. Feed lines are preferred which have a heating device for the heated gas immediately before their end on the reactor side.

The mouth of the feed lines can be in the reactor wall. The feed lines preferably open into the interior of the reactor, in particular into the middle of the gas flow in the reactor, so that the heated gas does not come into contact with the reactor walls if possible.

The radicals can be generated from gap promoters in the feed line to the reactor. However, it is also possible to attach a device for generating radicals to the end of the supply line for the gas containing the gap promoter, or the device for generating free radicals is arranged inside the reactor and generates an increased radical concentration within a predetermined volume, and the supply line to the reactor flows into this predetermined volume and allows the introduction of heated gas, such as gas containing inert gas and / or cracking promoters.

Radicals can be generated from gap promoters by thermal or non-thermal processes. Examples of non-thermal processes are photolytic fission by means of electromagnetic radiation or particle radiation or the generation of non-thermal plasmas by means of electrical discharges.

In variant I of the method according to the invention, in the case of radical generation by thermal decomposition, a gas diluted with inert gas and containing cracking promoters is used, or the cracking promoter containing gas is passed over a heat source, the surface of which is flushed with inert gas. These measures significantly reduce the tendency to form coke.

In a preferred embodiment, the gas containing radicals, diluted with inert gas and to be introduced, is electrically heated in the feed line immediately before it is introduced into the reactor.

In a further preferred embodiment, the gas containing cracking promoters, preferably diluted with inert gas and to be introduced, is passed at the end of the feed line immediately before being introduced into the reactor through a device for generating radicals, in particular through an electrical discharge path.

Another preferred variant of the method according to the invention comprises

Generation of a thermal plasma from inert gas, cooling of the thermal plasma by supplying inert gas to the desired temperature, so that a gas is generated at a temperature which is sufficiently high to be able to generate radicals from a cracking promoter, mixing this gas with a Gap promoter and introducing this mixture containing radicals into the

Reactor.

A further preferred variant of the method according to the invention relates to the use of gases which are derived from gap promoters and in which by means of an electrical discharge, preferably a spark, barrier or

Corona discharge, radicals have been generated.

Another preferred variant of the method according to the invention relates to the use of gases which are derived from gap promoters and in which radicals have been generated by means of a microwave discharge or a high-frequency discharge. Yet another preferred variant of the method according to the invention relates to the use of gases which are derived from gap promoters and in which heat and radicals have been generated simultaneously by means of a chemical reaction. Examples of this are the combustion or the catalytic conversion of an excess of chlorine with hydrogen in or shortly before the confluence of the

Feed into the reactor. For example, a chlorine oxyhydrogen gas flame can be used, an excess of chlorine being used and in which an inert gas is preferably added. The reaction of an excess of chlorine with hydrogen in the presence of inert gas on a catalytically active surface, e.g. on platinum.

Yet another preferred variant of the process according to the invention relates to the use of gases which are derived from gap promoters and in which radicals have been generated in the feed line to the reactor or in a predetermined volume inside the reactor by means of a photochemical reaction. On

An example of this is the use of a radiation source, such as an excimer lamp, a mercury vapor lamp, a laser, which is attached to the reactor and is suitable for generating radicals, and the radiation of electromagnetic radiation suitable for generating radicals or of particle radiation, such as alpha or beta Particles, in the feed line to the reactor or in the reactor.

In a further preferred embodiment of the process according to the invention, a reactor is used which has at least one catalytically active metal arranged on a gas-permeable support.

Any metal, including metal alloys, which is stable under the reaction conditions prevailing in the reactor, for example does not melt, can be used as the catalytically active metal. It is believed that metallic surfaces and / or metal halides formed during the cleavage reaction

Lower the activation energy of one or more steps of the radical chain reaction and thereby cause the reaction to accelerate further. A metal or a metal alloy from subgroup 8 of the periodic table of the elements, in particular iron, cobalt, nickel, rhodium, ruthenium, palladium or platinum, as well as alloys of these metals with gold, is preferably used as the catalytically active metal.

Rhodium, ruthenium, palladium and platinum are very particularly preferred.

All carriers known to the person skilled in the art can be used as the gas-permeable carrier, which can be attached to selected areas of the inner wall of the reactor and / or the inside of the reactor and which are provided with feed lines for flushing gas.

This can be a cage, which is formed, for example, by a grid or a perforated metal plate, which can accommodate a catalyst bed and can be flowed through by the purge gas, for example by central introduction by means of a perforated tube.

Furthermore, the gas-permeable support can be a gas-permeable plate which is surrounded by a flat structure, such as a wire mesh, made of catalytically active metal.

The gas-permeable carrier is preferably a porous one

Moldings. This can consist of the catalytically active metal. It is preferably a porous ceramic which is coated in particular with the catalytically active metal; or it is a porous ceramic that is doped with the catalytically active metal.

The catalytically active metal can be attached in any form in or on the gas-permeable support. Such arrangements are known to the person skilled in the art.

For example, the catalytically active metal can be in the form of moldings with the largest possible surface-to-volume ratio. The catalytically active metal is preferably applied as a coating and / or as a doping on or in the gas-permeable carrier. In order to maintain the longest possible operating time, it is necessary to maintain the catalytic activity of the metal for as long as possible and / or to be able to restore or regenerate it while the reactor continues to operate.

It has been found that this can be achieved by flushing the catalytic surface with a gaseous reducing agent.

All gaseous reducing agents for coking products can be used as the gaseous reducing agent at the temperatures prevailing in the reactor. Examples of this are hydrogen or a mixture of hydrogen and inert gas.

The gaseous reducing agent is supplied via the gas-permeable support and is fed through this to the catalytically active metal.

The gaseous reducing agent can be supplied continuously or at predetermined time intervals.

The gaseous reducing agent is supplied undiluted or together with inert gases such as nitrogen and / or noble gases.

The temperature of the gaseous reducing agent supplied via the gas-permeable carrier is expediently adapted to the temperature which prevails in the interior of the reactor at the location of the gas-permeable carrier.

Through a continuous or intermittent injection of hot gases into the

Reaction mixture, the sales in the pyrolysis reaction can be increased and the product yield increased; The parallel purging with inert gas and / or reducing agent can efficiently prevent or slow down the coking of the surface of the catalytically active metal which may be attached to the inside of the reactor, thereby prolonging the operating time of the cracking furnace and further increasing the turnover of the cracking reaction. The operation of the reactor is not interrupted during the rinsing process. Instead of or together with the gaseous reducing agent, gap promoters can also be fed to the catalytically active metal in the reactor via the gas-permeable carrier. Examples of this are listed above.

Preferably, at least one feed line for hot gas containing gap promoters opens in the vicinity of the entry of the feed gas stream into the reactor.

As a result, a heated gas formed from cleavage promoters and containing radicals can be introduced into the reactor at this point, a high concentration of radicals already being present when the reactant gas enters the reactor, which contributes to an efficient course of the chain reaction.

In a preferred variant of the process according to the invention, a heated gas formed from gap promoters and containing radicals is introduced into the feed gas stream as it passes through the reactor via a plurality of feed lines.

The number of feed lines in the first third of the reactor is very particularly preferably greater than in the second third and / or in the third third.

The process according to the invention can be carried out using the conventional methods

Pressures and / or temperatures are operated. Common operating pressures are in the range of 0.8 to 4 MPa (furnace inlet); Common operating temperatures are in the range from 450 to 550 ° C (furnace exit) and in the range from 250 to 350 ° C (furnace entrance). The endothermic cleavage reaction requires a constant supply of energy; this takes place when the gas to be split passes through the

Reactor.

With the method according to the invention, a lowering of the usual operating temperatures is possible. This enables a more economical procedure. Instead of lowering the operating temperatures is a

Yield increase possible. Another embodiment of the process according to the invention relates to the thermal cracking of the product gas in an adiabatic post-reactor downstream of the reactor, comprising the measures: f) introducing the product gas stream containing heated halogen-containing aliphatic hydrocarbon, hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon from the reactor into an adiabatic post-reactor, in which the reaction is continued using the heat supplied by the product gas stream while cooling the product gas, and in the interior of which at least one feed line for a heated gas formed from gap promoters and containing radicals opens, and g) optionally introducing one from gap promoters by thermal or non- formed thermal decomposition, radical-containing heated gas through the feed line (s) opening into the adiabatic post-reactor, the temperature of the heated ten gas in the case of

Generation of the radicals by thermal decomposition has at least the temperature of the reaction mixture prevailing at the point of the feed line and the heated gas in the case of generation of the radicals by non-thermal decomposition has at least the temperature of the temperature of the dew point of the

Reaction mixture at the point of the mouth of the feed line corresponds to the adiabatic post-reactor, with the proviso that in the case of radical generation by thermal decomposition, this takes place by heating a gas containing dilution promoters diluted with inert gas or by passing a gas containing a promoter

Gases over a heat source, the surface of which is flushed with inert gas.

The process according to the invention can only include measures f) and g) in the adiabatic post-reactor, without using an upstream reactor, in the interior of which at least one feed line for a heated one

Gas flows. However, the method according to the invention with measures f) and g) in the adiabatic post-reactor is preferred, combined with the use of an upstream reactor in whose interior at least one feed line for a heated gas opens.

The invention also relates to a reactor for carrying out the process defined above, comprising the elements: i) feed line for the educt gas stream containing saturated halogen-containing aliphatic hydrocarbon opening into the reactor, ii) at least one feed line for a heated gas opening into the interior of the reactor, iii) source connected to the supply line for a gap promoter, iv) device installed in the supply line for generating radicals from gap promoters, v) optionally heating device for heating the gas in the

Supply line, vi) heating device for heating and / or maintaining the

Temperature of the gas stream in the reactor, and vii) discharge from the reactor leading to the product gas stream of the thermal cleavage containing ethylenically unsaturated halogen-containing aliphatic hydrocarbon.

In a further preferred embodiment, the invention also relates to a reactor for carrying out the process defined above, comprising the elements: i) feed line for the feed gas stream containing saturated halogen-containing aliphatic hydrocarbon which opens into the reactor, ii) at least one feed line for a feed opening into the interior of the reactor heated gas, iii) source for a gap promoter connected to the supply line, viii) device for producing

Radicals from gap promoters v) optionally heating device for heating the gas in the feed line, vi) heating device for heating and / or maintaining the

In a likewise preferred embodiment, the invention relates to a reactor for carrying out the process defined above, comprising the elements: i) feed line for the feed gas stream containing saturated halogen-containing aliphatic hydrocarbon, ix) opening into the reactor, inside the reactor, the device installed within a predetermined volume Generates radicals in the inside of the reactor from gap promoters, x) at least one supply line for a heated gas containing gap promoters opening into the predetermined volume inside the reactor, iii) source connected to the supply line for a gap promoter, v) heating device for heating the gas in the feed line, vi) heating device for heating and / or maintaining the temperature of the gas stream in the reactor, and vii) discharge line leading from the reactor for the product gas stream of the thermal cleavage containing ethylenically unsaturated halogen-containing aliphatisc hen hydrocarbon.

All types known to those skilled in the art for such reactions can be used as the reactor. A tubular reactor is preferred.

The reactor according to the invention can be followed by an adiabatic post-reactor which preferably contains the elements ii), iii) and iv) or ii), iii) and viii) or ix), x), iii) and v) defined above. In the adiabatic post-reactor, the required heat of reaction is supplied by the heat of the product gas stream supplied, which cools down as a result. Instead of combining the reactor according to the invention with an adiabatic post-reactor containing the elements ii), iii) and iv) or ii), iii) and viii) or ix), x), iii) and v), such an adiabatic post-reactor can also be used with a known reactor which does not have the elements ii), iii) and iv) or ii), iii) and viii) or ix), x), iii) and v).

The supply line for the heated gas preferably consists of metal pipelines which open into the wall or preferably the interior of the reactor and which have a nozzle at their reactor end and which preferably have an electrical heating device for the heated gas directly in front of their reactor end. In a preferred variant, this heating device consists entirely of ceramic.

Another preferred embodiment of the reactor according to the invention comprises a generator for a thermal plasma, for example one

High-frequency plasma generator, which is connected to the supply line for the gas containing radicals to the reactor, the high-frequency plasma generator being connected to a further supply line for a gap promoter and optionally with a further supply line for an inert gas.

The high-frequency plasma generator is preferably attached to the outer reactor wall in the vicinity of the junction of the feed line into the reactor.

A further preferred embodiment of the reactor according to the invention comprises a device for generating an electrical discharge, preferably a spark, barrier or corona discharge, which is connected to the feed line to the reactor. This is also preferably attached to the outer reactor wall in the vicinity of the inlet of the feed line into the reactor.

A further preferred embodiment of the reactor according to the invention comprises a device for generating a microwave discharge or a high-frequency discharge, which is connected to the feed line to the reactor. This is likewise preferably attached to the outer reactor wall in the vicinity of the junction of the feed line into the reactor.

Yet another preferred embodiment of the reactor according to the invention comprises a device in which heat and radicals are simultaneously generated by means of a chemical reaction and which has at least two feed lines for the reactants and a burner which opens directly into the reactor.

A further preferred embodiment of the reactor according to the invention comprises a radiation source which is arranged in the feed line to the reactor or the radiation of which is conducted into the feed line to the reactor. This is also preferably attached to the outer reactor wall in the vicinity of the inlet of the feed line into the reactor.

In a very preferred embodiment of the reactor according to the invention

Inside the reactor there is at least one porous ceramic in the form of a candle, the surface of which is coated with catalytically active metal and / or which is doped with catalytically active metal, and the candle is provided with a feed line for a gaseous reducing agent and / or a gap promoter for transmission equipped with the catalytically active metal.

Further particularly preferred embodiments of the process and reactor according to the invention are described below with reference to FIGS. 1 to 9.

Show it

Figure 1: A preferably used device for heating and introducing a heated gas formed from gap promoters containing radicals into a cracking reactor shown in longitudinal section

Figure 2: An arrangement of the device of Figure 1 in a reaction tube shown in longitudinal section Figure 3: tubular reactor with device according to Figure 1 in longitudinal section

FIG. 4: A preferred device for generating radicals by means of a non-thermal plasma and for introducing the heated gas formed from crack promoters and containing radicals into a cracking reactor shown in FIG

longitudinal section

Figure 5: Another preferred device for generating radicals by a non-thermal plasma and for introducing the heated gas formed from gap promoters containing radicals into a

Fission reactor shown in longitudinal section

Figure 6: An arrangement of the devices of Figure 4 or 5 in a reaction tube shown in longitudinal section

Figure 7: Another preferred device for generating radicals from gap promoters by radiation and for introducing the gas formed from gap promoters containing radicals into a gap reactor shown in longitudinal section

Figure 8: A modification of the device of Figure 7 shown in longitudinal section

Figure 9: Another modification of the device of Figure 7 shown in longitudinal section

In a particularly preferred variant of the process according to the invention, the feed gas stream comes into contact with a gas containing radicals as it is passed through the reactor, which gas was generated in one or more heating devices of the type outlined in FIG. 1.

The heating device is an electrically operated heating cartridge (1), which is preferably provided with a ceramic jacket and which is in one Housing (2) is arranged, which has one or more concentric annular gaps (3).

The housing (2) can consist of ceramic and / or metal. The housing preferably has a cylindrical shape.

The heating cartridge (1) is fixed in the housing (2) by means of a gastight, pressure and temperature resistant bushing (4). This is preferably a bushing (4) provided with a screw thread, into which the heating cartridge can be screwed and fixed.

The housing (2) has a gas inlet (5) through which a gas stream containing gap promoters and optionally diluted with inert gas can be introduced. The gas inlet (5) is preferably located on the outer wall of the housing (2).

A plurality of concentric annular gaps (3) are preferably formed in the housing, through which gas containing the gap promoter flows. These ring gaps (3) have at least two openings through which gas containing the gap promoter flows into and out of the ring gap. These are preferably

Openings are made at the front and rear end of the heater. The consequence of this is that the gas flow flows through each annular gap along the entire length of the heating device and that the direction of flow of the gas flow reverses in each annular gap. The gas flow moves in the illustrated embodiment from the outside of the

Housing (2) through the annular gaps (3) is deflected several times in the annular gaps (3), and finally flows along the heating cartridge (1) fitted inside and then through a gas outlet (6), which is preferably designed as a nozzle, in the reaction space.

The housing (2) can also only have an annular gap. In this case, the gas immediately flows along the heating cartridge (1) through the gas outlet (6) into the reaction space. The embodiment shown in FIG. 1 with several annular gaps offers the advantage that the outer wall of the heating device does not heat up or does not heat up significantly above the temperature prevailing in the reaction space due to the strong heating of the gas containing the gap promoter on the heating cartridge (1). This prevents the build-up of coke deposits on the outer wall.

In a further embodiment, the outer wall of the heating device, in particular the part of the heating device which projects into the reaction space, can be coated with an inert material, e.g. B. a metal oxide, ceramic, boron nitride or silicon nitride.

Furthermore, the inner wall of the heating device opposite the heating cartridge (1) can be coated with such materials.

In a further embodiment, the device has at least two separate gas feed lines, one feed line being used to feed an inert gas and the other feed line being used to feed a promoter substance. The feed line for the promoter substance is preferably arranged such that mixing with the inert gas takes place only shortly before entering the reaction space.

The heating device shown in Figure 1 is provided on its outer wall with a cone (8), on the outside of which there is a thread (7). The cone (8) and that part of the heating device which forms the sealing edge for the line seal are made of materials which have approximately the same thermal expansion, in particular of the same material.

A possible arrangement of the heating device on the reaction tube is shown in Figure 2. A holder (10) is welded to the reaction tube (9) and has a thread (11) and a projection (12) which forms a circumferential sealing edge. If the heating device described in FIG. 1 is screwed into the holder (10), the projection (12) cuts into the cone (8) and thus forms a reliable seal.

This sealing principle is already described in DE-A-44 20 368.

As already described in 44 20 368, an additional seal can be provided by a stuffing box packing (not shown in FIG. 2).

The heating device shown in Figure 1 can be in a conventional tubular reactor for the production of ethylenically unsaturated halogen-containing aliphatic

Hydrocarbons are incorporated by thermal splitting of saturated halogen-containing aliphatic hydrocarbons.

Such an installation is shown schematically in FIG. 3.

The tubular reactor comprises an oven and a reaction tube.

In general, an oven fired with a primary energy source, such as with oil or gas, is divided into a so-called radiation zone (16) and a convection zone (17).

In the radiation zone (16), the heat required for the pyrolysis is transferred to the reaction tube primarily by radiation from the furnace walls heated by the burner.

In the convection zone (17), the energy content of the hot flue gases emerging from the radiation zone is used by convective heat transfer. Thus the starting material of the pyrolysis reaction, e.g. EDC, preheated, evaporated or overheated. It is also possible to generate water vapor and / or preheat combustion air.

In a typical arrangement, as is shown, for example, in EP-A-264,065, liquid EDC is first preheated and in the convection zone of the cracking furnace then evaporated outside the cracking furnace in a special evaporator. The vaporous EDC is then again fed to the convection zone and overheated there, the pyrolysis reaction already being able to start. After overheating, the EDC enters the radiation zone, where the conversion to vinyl chloride and hydrogen chloride takes place.

As a result of the high temperatures prevailing in the radiation zone and the high temperatures in the entrance of the convection zone, it is advantageous not to arrange the device sketched in FIG. 1 directly within these zones, since otherwise e.g. A defined temperature setting of the heated and radical-containing gas or gas mixture initiated to promote the cracking reaction is not possible or is possible only with difficulty.

For this reason, an arrangement as shown schematically in FIG. 3 is preferred.

Here, the cracking furnace is expanded by at least two additional, non-heated compartments (18) which can be thermally insulated. Loops of the reaction tube are then guided through these compartments (18) from the actual radiation or convection zone (16, 17). In these loops, preferably on the arches of the loops and ending in the straight lengths of these loops, the heating device according to FIG. 1 (19) for introducing a gas containing heated radicals is then mounted, that is to say built into the reaction tube, so that the educt gas stream flows thereon Can be brought into contact with the gas containing heated radicals.

The loops of the reaction tube which are led from the radiation or convection zone (16, 17) into the unheated compartments (18) are preferably provided with thermal insulation.

In a further particularly preferred variant of the invention

In the process, the educt gas stream comes into contact with a radical-containing non-thermal plasma which has been generated in one or more devices of the type outlined in FIGS. 4 and 5 as it passes through the reactor. FIGS. 4 and 5 show a device known per se for the upstream generation of radicals by a non-thermal plasma from a vaporous gap promoter or a mixture of gap promoter and inert gas, and the feeding of the plasma into the reactor according to the invention.

Radicals are generated in a volume separated from the reaction space of the cracking reaction by means of an electrical discharge from a gaseous cracking promoter. The undiluted cleavage promoter can be used, or the promoter can be diluted with an inert gas such as nitrogen or noble gas. The electrical discharge is preferably a

Barrier or corona discharge. The radicals thus generated are then fed into the actual reaction space of the reactor according to the invention.

The device shown in FIGS. 4 and 5, preferably used in the reactor according to the invention, is known from DE-A-19648 999. The known device is used for the treatment of surfaces by means of high pressure plasma.

Advantageously, the device for generating a non-thermal plasma is combined with a sealing system, as is already the case for

Introduction of a measuring probe into a cracking furnace for the production of vinyl chloride is known from DE-A-4420 368.

In a departure from the procedure described in DE-A-196 48 999, the device for generating plasma is, according to the invention, much higher

Pressures of at least 5 bar, preferably 12 to 26 bar, operated.

In contrast to the operation at atmospheric pressure known from DE-A-196 48 999, e.g. a barrier discharge requires significantly higher electrical voltages.

The device for plasma generation which is preferably used according to the invention comprises a gas inlet (43) and a plasma generation area (32) at least two electrodes (33, 34) and a gas outlet (28) which opens into a reaction space (46), the reaction space (46) and plasma generation area (32) being spatially separated from one another.

An example of those used in the reactor according to the invention and in DE-A-196

The device described in 48 999 is discussed in more detail below with reference to FIG. 4, which shows a longitudinal section.

The device has an essentially cylindrical housing (20) with a rear end (21) and a front end (22). Along its outside

(23) the housing (20) is provided with a cone (24) and a thread (25). Housing (20) consists of a conductive material, such as metal, preferably steel or another metal, which is stable under the conditions prevailing in the reactor.

The cylindrical housing (20) tapers in the region of its front end (22) and has an opening serving as a gas outlet (28) in the region of its cylinder axis (26). This opening can be formed by a nozzle. In the area of its rear end (21), the housing (20) carries a flange (29) which has channels and feeds which are described below.

In the interior of the housing (20) there is a ceramic tube (30) which is arranged axially symmetrically to the axis (26) and is closed on one side in the region of the gas outlet (27). The outside diameter of this ceramic tube (30) is selected such that there is an annular gap on the inside (31) of the housing (20), which is referred to below as the plasma generation area (32). The inside of the ceramic tube (30) is coated with the aid of a metal application, for example a conductive silver application, and forms an electrode (33) of a plasma generating device. The other electrode (34) is formed by the electrically conductive housing (20) itself. The ceramic tube (30) and the annular-gap-shaped plasma generation area (32) are therefore located between the electrode (33) designed as an inner coating and the electrode (34) formed by the housing (20). In the interior of the ceramic tube (30) there is another tube (35) which is also arranged axially symmetrically to the cylinder axis (26) but is open on both sides. This further tube (35) is fixed at a distance within the ceramic tube (30) by means of a spring (37) which is supported against the closed end (36) of the ceramic tube (30) in the region of the front end (22) of the housing (20) , so that there is also an annular gap (38) between the outside of the further tube (35) and the conductively coated inside of the ceramic tube (30). The spring (37) is, for example, three or four-winged and in any case enables unimpeded gas passage from the interior of the further tube (35) into the annular gap (38).

The spring (37) also connects a high-voltage supply (39) arranged axially symmetrically within the further tube (35), with which the electrically conductive coating forming an electrode (33), as a result of which an alternating current can be supplied to it. In contrast, the housing (20) forming the other electrode (34) is grounded, so that it can be touched safely.

The flange (29) at the rear end (21) of the cylindrical housing (20) essentially serves for the supply of gas and high voltage as well as for grounding and for guiding the gas flow through the various gaps within the housing

(20). The cylindrical flange (29) is fastened to it with screws (40) which engage in the outer region of the cylindrical housing (20). In the middle, the flange (29) has an insulating, gas-tight and pressure-resistant bushing (41) through which the high-voltage feed (39) is guided axially into the housing (20). Furthermore, the flange (29) has a gas inlet (43) which leads from an outer connection piece via a channel (42) into the inner region of the further tube (35), the rear side of the further tube (35) seals with a sealing web (44) of the flange (29).

Furthermore, the flange (29) on its side facing the housing (20) has an annular groove (45), the diameter of which is dimensioned such that it seals the annular gap (38) between the further tube (35) and the ceramic tube (30) annular gap of the plasma generation area (32) between the ceramic tube (30) and the inside of the housing (31) sealingly connects.

To operate the device, the gas inlet (43) is acted upon by the selected gas or gas mixture and a high-frequency high voltage is applied between the high-voltage supply (39) and the housing (20). The voltage and frequency to be selected depend on the type of gas, the geometry of the arrangement, the type of surface treatment and other factors and can be chosen freely by a person skilled in the art.

The gas passes from the gas inlet (43) into the interior of the further tube (35), flows through this further tube (35) to the spring (37), enters the area between the spring (37) and the closed end of the ceramic tube (30) and back down into the annular gap (38) between the ceramic tube (30) and another tube (35). The gas then returns to the flange (29) in its annular groove (45) and is again deflected, this time upwards, into the annular gap between the outside of the ceramic tube (30) and the inside of the housing (20), which forms the plasma generation area (32) , After flowing through this plasma generation area, the gas reaches the area of the gas outlet (28) and leaves the device in the reaction space (46), where the reaction to be initiated takes place.

Since the conductive coating of the ceramic tube (30) has the same electrical potential as the high-voltage supply (39), the gas remains electrically unaffected both within the further tube (35) and in the annular gap (38). The gas is diverted through the further pipe (35) and the annular gap (38) essentially for the purpose of internal cooling of the device. The working gas thus acts as a cooling gas at the same time, which saves further internal cooling.

Only in the plasma generation area (32) is the gas between the electrodes (33), formed by the conductive coating of the ceramic tube (30), and (34), formed by the housing (20), and is created by the high-frequency high voltage partially ionized, that is, set in the plasma state desired for the generation of radicals. When operating the device, the flow rate should be chosen so high that the plasma state is maintained even after the plasma gas has escaped through the gas outlet (28).

In a further embodiment, the outer wall of the device used according to the invention, in particular the part of the device which protrudes into the reaction space, can be coated with an inert material, e.g. B. a metal oxide, ceramic, boron nitride or silicon nitride to slow down or prevent the deposition of coke.

In a further embodiment shown in FIG. 5, the device has one or more bores (47) in the housing (20) instead of the gas outlet (28), through which gas containing radicals can escape into the reaction space (46).

The device used according to the invention is preferably provided on its outer wall with a cone (24) and a thread (25).

A preferred arrangement of the devices according to Figures 4 and 5 am

Reaction tube is shown in Figure 6.

A holder (49) is welded to the reaction tube (48) and has a thread (50) and a projection (51) which forms a circumferential sealing edge. If the device described in FIG. 4 or FIG. 5 is screwed into the holder, the sealing edge (51) cuts into the cone (46) and a reliable metallic seal is formed.

This sealing principle is known from DE-A-4,420,368. As already described there, an additional seal can be provided by a

Stuffing box packing (not shown in the figure). The entire device can be attached to the reactor in the same manner as shown in FIG.

In a further particularly preferred variant of the process according to the invention, the feed gas stream comes with one during passage in the reactor

Radical containing gas in contact which has been generated in one or more devices of the type outlined in Figures 7, 8 and 9.

In this device, radicals are generated by photolysis of a promoter substance, the promoter substance being gaseous either in / a form or in

Mixture with an inert gas and / or with a gaseous reducing agent can be present.

The photolysis takes place in a compartment separated from the actual reaction space, which is flowed through by the respective gas (mixture) and is split photolytically into radicals. The gas (mixture) containing radicals then enters the actual reaction space through an opening which can be designed as a nozzle.

During the flow, but possibly also after exiting the nozzle, the promoter substance is photolyzed by interaction with the light from a suitable light source. Radicals are formed, which then promote the reaction taking place in the actual reaction space. This procedure has the advantage that only small amounts of the promoter substance are used.

The direct addition of a promoter substance, already known from the literature, into the reaction space leads to the generation of radicals by thermal decay of the promoter at the temperature level of the reaction to be influenced, for example in the range from 450 to 550 ° C. or by heterogeneous decay (wall reactions). The promoter must be added in amounts that already have a noticeable effect on the

Represent reaction system and in addition to the desired increase in turnover leads to an increased formation of by-products, ie to a deterioration in selectivity and an increase in the rate of coke formation. These disadvantages compensate for the economic advantage gained from the increase in sales and lead to the fact that the use of promoter substances has so far not been able to establish itself in industrial practice.

The procedure described here circumvents this disadvantage in that the promoter substance is specifically and effectively decomposed into radicals in a compartment separated from the actual reaction and therefore only the addition of small amounts of promoter substance is necessary.

Promoter substances in the production of halogen-containing ethylenically unsaturated hydrocarbons are mostly substances which form chlorine radicals under the reaction conditions of the process. This can be chlorine itself, but also chlorine compounds such as CCI ₄ or other chlorinated hydrocarbons. In the method described here, the promoter substance can also be DCE, which is then preferably diluted with an inert gas.

To carry out the method variant described, light from a light source suitable for the purposes described is coupled through a light guide or an optically transparent window, preferably a quartz window, into a compartment separated from the actual reaction space and shines through the compartment itself and preferably also a part of the adjacent reaction space.

In the compartment, the promoter gas (which can consist of the pure promoter substance or can be a mixture of the promoter substance with an inert gas) forms a gas cushion which chemically largely decouples the light guide or the optical window from the reaction space. The purpose of this measure will be explained in the following using the example of EDC splitting.

An undesirable side reaction of the EDC cleavage is the deposition of coke on the reactor walls. The process of coke separation is slower on non-metallic materials such as quartz than on metallic ones Materials. This fact has recently been used to slow down the formation of coke in reactor tubes by applying non-metallic coatings to the inner wall of the tube. In spite of this fact, coke would also deposit on the optical window if it were directly exposed to the reaction mixture, for example if it were inserted directly into the reactor wall.

This problem has already been described in DE-A-30 08 848. The photochemical initiation of the cleavage reaction by direct irradiation of light into the reaction space is proposed there, both with metal halide lamps and with lasers as the light source. It also describes the observation that when using continuously operating light sources, such as metal halide lamps, the window quickly covers itself with by-products, while it remains free when using lasers.

As a remedial measure, working with high flow velocity in the

Area of the optical window proposed so that the by-products formed are formed in a noticeable amount only downstream of the window.

A disadvantage of this procedure, however, is that the “self-cleaning” of the window is probably limited to the use of pulsed lasers, since here a brief local heating of the gas in and around the coke particles generates pressure surges which the coke particles or the coke layer The use of pulsed lasers is not explicitly mentioned in DE-A-30 08 848, but it is in DE-A-29 38 353, to which DE-A-30 08 848 expressly refers is taken.

The experiments on which DE-A-30 08 848 and DE-A-29 38 353 are based were carried out in quartz reactors. In industrial reactors made of metal, however, coke is already formed in the inlet area of the reactor and thus “upstream” of a possibly attached optical window. Possible causes for this are, on the one hand, that coke precursors are formed by wall reactions in the entry area and, on the other hand, that even with careful Distillative cleaning of the educt DCE in industrial Process with which educt small amounts of coke precursors are introduced into the reactor. There is therefore a need for further processes which can be easily implemented in industrial practice and in which coke formation can be effectively avoided.

The present invention circumvents these disadvantages and a method or a reactor is made available in which light can be coupled into a reactor operated under the conditions of VC production or under similar conditions. For this purpose, a promoter substance is first split photolytically in a compartment separated from the actual reaction space and then introduced into the reaction space.

FIG. 7 shows a device which is preferably used in the reactor according to the invention for the photolytic generation of radicals from gap promoters. A bracket is welded to an arc of the reaction tube, which is inside

Has thread (52) and a circumferential sealing edge (53). A conical sleeve (54) can be screwed into this holder, the front end of which can be designed as a nozzle and which, for better screwability, e.g. can have a hexagon socket (55). If the conical sleeve (54) is screwed into the holder (56), this forms with the sealing edge (53) of the holder a seal which is reliable under the conditions of the reaction. This proven sealing principle has already been described in DE-A-44 20 368.

Using the same sealing principle, a further sleeve (57) can be screwed into the holder (56), which contains an optically transparent window (58), e.g. B. a quartz window, which can be coated with a semipermeable metal layer (59), the metal preferably being a hydrogenation catalyst and very particularly preferably a platinum metal.

The optical window is clamped between brackets (60, 61) which have circumferential recesses (62) on their sides facing the window, each of which receives a seal (63, 64), preferably a metal seal and very particularly preferably a gold seal. The window (58) is pressed against the holder (61) by the holder (60). This can be done by screwing the bracket (60) to a bearing ring or bearing blocks (65) which is provided, for example, with blind holes (66).

The brackets (60) and (61), the recesses (62) and the thicker one

Seals are dimensioned so that when the assembly is screwed on, a defined surface pressure of the seals is established and the optical window is not damaged.

The intermediate space (67) between the sleeves (54) and (57) is provided with one or more gas feed lines and forms a compartment separated from the reaction space (68) and from the outer space (69).

The pyrolysis of, for example, DCE to VC takes place in the reaction space (68). The entire arrangement is mounted on an arc of the reaction tube which protrudes from the actual radiation zone of the furnace and is thermally insulated from it.

An inert gas flows through the gas inlet (70), e.g. Nitrogen or a rare gas, or a mixture of an inert gas with a promoter substance or a gaseous one

Promoter substance in the compartment (67). The gas leaves the compartment and flows through the opening (71) into the reaction space.

Due to the permanent purging of the compartment, the optical window is separated from the reaction space (68) by a gas cushion. Therefore coke precursors such as acetylene, benzene or chloroprene cannot reach the window and form coke deposits there.

In a preferred embodiment, the optical window is coated with an optically semipermeable metal layer, the metal being a hydrogenation catalyst, for example palladium. If a small amount of hydrogen is now added to the promoter gas, coke precursors that reach the optical window despite being rinsed are reduced on its surface. As a result, no coke deposits can form on the surface of the window.

The light from the light source shines through the optical window and transfers energy to the molecules of the promoter substance, which thereby breaks down into radicals (photolysis), which then promote the reaction taking place in the actual reaction space (68). The generation of radicals and their subsequent transport into the reaction space is normally difficult because of the prevailing ones

Pressure ratios (typically 9 - 25 bar) quickly recombine the radicals.

In the arrangement according to the invention, however, the entire compartment and preferably also the reaction space are irradiated. The result of this is that the desired radicals are also formed in the opening (71) and in the zone of the reaction space adjacent to this opening from the promoter substance and can therefore intervene safely in the reaction process. Therefore, high flow rates of the initiator or purge gas are not required in order to quickly transport radicals generated in the compartment into the reaction space.

This also means that the initiation can be carried out with very small amounts of promoter gas, as a result of which the reaction system intervenes only to a small extent and the formation of undesired by-products is largely suppressed.

In a further preferred embodiment and the embodiment shown in FIG. 8, the compartment (67) has a further gas inlet (72) which is guided up to near the surface of the optical window (58). It is thus possible to purge the window and its immediate surroundings with inert gas or a mixture of inert gas and hydrogen, while the promoter substance or a mixture of promoter substance and inert gas is added through the gas inlet (70) become. With such an arrangement, the optical window can be protected even better against coke deposits.

Another preferred embodiment shown in FIG. 9 is similar to the embodiment shown in FIG. The further gas inlet (72) is here in

Directed the opening (71) and serves to supply the promoter substance. The gas inlet (70) only serves to supply inert or purge gas. In this way, the radicals are generated from the promoter substance in the vicinity of the reaction space (68) and away from the optical window (58). This enables the optical window (58) to be protected further against coke deposits.

Any light source whose light is suitable for photolysis of the promoter substance used can be used as the light source. This can be a UV lamp (e.g. a metal halide lamp) or a laser. When using lasers, it is irrelevant in the arrangement proposed here whether a pulsed laser or a continuous beam laser is used. Excimer lamps can also be used as light sources.

The radiation used can be coupled in different ways. For example, the light can be coupled in through an optical fiber bundle (as indicated in FIG. 8). Furthermore, the light source (e.g. in the case of using a metal vapor or excimer lamp) can be installed directly in the sleeve (57) behind the optical window. In this case, appropriate cooling should preferably be provided. The light can also be coupled into the sleeve (57) through a further window and deflected onto the window (58) by a mirror.

In a special embodiment, a device analogous to DE-A-198 45 512 or DE-Gbm-200 03 712 is used for coupling the light. The known devices are used to observe processes in the combustion chamber of internal combustion engines in operation and are used, for. B. used in the form of so-called spark plug adapters. In addition to their actual purpose, the optical observation of combustion processes, these are Due to their pressure and temperature resistance, devices are also suitable for coupling light into chemical reactors in which pressure and temperature conditions are similar to those in running internal combustion engines.

If such devices are used, the optical window shown in FIGS. 7, 8 and 9 with the described sealing system could be omitted. The light feed would then be screwed into a partition in the sleeve (55) in the form of an adapter analogous to one or more so-called spark plug adapters.

The device for the photolytic generation of radicals from gap promoters can be attached to the reactor according to the invention in the same manner as shown in FIG. 3.

Claims

claims

1. A process for the production of ethylenically unsaturated halogen-containing aliphatic hydrocarbons by thermal cleavage of saturated halogen-containing aliphatic hydrocarbons comprising the

Measures: a) introducing a feed gas stream containing heated gaseous halogen-containing aliphatic hydrocarbon into a reactor, in the interior of which at least one supply line for a gas opens, b) introducing a heated gas, which contains radicals generated by thermal or non-thermal decomposition of fission promoters, by the at least a feed line opening into the reactor, the heated gas in the case of the generation of the radicals by thermal decomposition having at least the temperature which prevails at the point of the feed line temperature of the

Corresponds to the reaction mixture in the reactor and the heated gas in the case of the generation of the radicals by non-thermal decomposition has at least the temperature which corresponds to the temperature of the dew point of the reaction mixture at the point of the mouth of the feed line in the reactor, and c) setting such a pressure and a temperature inside the reactor such that hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon are formed by thermal cracking of the halogen-containing aliphatic hydrocarbon, with the proviso that in the case of radical generation by thermal decomposition, this gas is heated by heating a cracking agent diluted with inert gas takes place or by passing a gas containing cracking promoters over a heat source, the surface of which is flushed with inert gas.

2. Process for the production of ethylenically unsaturated halogen-containing aliphatic hydrocarbons by thermal cleavage of saturated halogen-containing aliphatic hydrocarbons comprising the Measures: a) introducing a feed gas stream containing heated gaseous halogen-containing aliphatic hydrocarbon into a reactor, in the interior of which at least one supply line for a heated gas containing fission promoters opens, d) thermal or non-thermal generation of radicals from fission promoters by means of a suitable device inside a predetermined volume inside the reactor, e) introducing the heated gas containing fission promoters through the feed line into the predetermined volume, the heated gas in the

If the generation of the radicals by thermal decomposition has at least the temperature which corresponds to the temperature of the reaction mixture in the reactor at the point of the mouth of the feed line, and the heated gas in the case of the generation of the radicals by non-thermal

Decomposition has at least the temperature which corresponds to the temperature of the dew point of the reaction mixture at the point of the mouth of the feed line in the reactor, and c) Setting such a pressure and such a temperature inside the reactor so that by thermal cracking of the halogen-containing aliphatic hydrocarbon hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon are formed.

3. The method according to claim 1 or 2, characterized in that 1, 2-dichloroethane is used as the saturated halogen-containing aliphatic hydrocarbon, from which vinyl chloride is produced by thermal cleavage.

4. The method according to claim 1 or 2, characterized in that the heated gas is generated from cracking promoters which are chlorine-containing compounds, preferably molecular chlorine, nitrosyl chloride, trichloroacetyl chloride, chloral, hexachloroacetone, benzotrichloride, monochloromethane, dichloromethane, trichloromethane, tetrachloromethane or chlorine.

5. The method according to claim 1 or 2, characterized in that the heated gas has a temperature in the range of 500 to 1500 ° C.

6. The method according to claim 1 or 2, characterized in that the total amount of the heated gas added to the reactor does not exceed

10% by weight, based on the total mass flow in the reactor.

7. The method according to claim 1, characterized in that the generation of the radicals from gap promoters is carried out by a device attached to the end of the supply line for the gap promoters containing gas for generating radicals.

8. The method according to claim 1 or 2, characterized in that the gas to be introduced is electrically heated in the feed line immediately before it is introduced into the reactor.

9. The method according to claim 1 or 2, characterized in that the gas to be introduced is generated from a gas containing fission promoters, which was generated by mixing with a heated inert gas, the heated inert gas by diluting a thermal plasma with

Inert gas is generated.

10. The method according to claim 1 or 2, characterized in that the radicals are generated from gap promoters by means of a spark, barrier or corona discharge.

11. The method according to claim 1 or 2, characterized in that the radicals are generated from gap promoters by means of a microwave discharge or high-frequency discharge.

12. The method according to claim 1, characterized in that the heated gas to be introduced contains radicals generated by means of a chemical reaction, in particular by reacting an excess of chlorine with hydrogen has been generated in the presence of inert gas on a catalytically active surface.

13. The method according to claim 1 or 2, characterized in that in the vicinity of the mouth of the supply line for the radical and / or gap promoters containing heated gas, a further supply line is provided, through which in the area of the reactor into which the radicals are introduced or in which radicals are generated from the gap promoters, heated inert gas is supplied.

14. The method according to claim 1 or 2, characterized in that a reactor is used which has at least one catalytically active metal arranged on a gas-permeable support in the interior.

15. The method according to claim 14, characterized in that the catalytically active metal is selected from the 8th subgroup of the periodic table of the elements, in particular from the group consisting of rhodium, ruthenium, palladium or platinum and alloys of these metals with gold.

16. The method according to claim 14, characterized in that the catalytically active metal is formed as a layer and / or as a doping on or in the gas-permeable carrier, preferably on or in a porous carrier, and with a gaseous feed supplied by the gas-permeable carrier Promoter of the pyrolysis reaction and / or a gaseous reducing agent is flushed.

17. The method according to claim 1 or 2, characterized in that at least in the vicinity of the entry of the feed gas stream into the reactor, a feed line for the heated gas opens into the reactor.

18. The method according to claim 17, characterized in that the feed gas stream comes into contact with a plurality of feed lines for the heated gas opening into the reactor as it passes through the reactor.

19. The method according to claim 18, characterized in that the number of feed lines opening into the first third of the reactor is greater than in the second third and / or in the third third.

20. The method according to claim 1 or 2 for the thermal cleavage of the

Product gas in an adiabatic post-reactor downstream of the reactor comprising the measures: f) introducing the product gas stream containing heated halogen-containing aliphatic hydrocarbon, hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon from the

Reactor in an adiabatic post-reactor, in which the reaction is continued using the heat supplied by the product gas stream while cooling the product gas, and in the interior of which at least one supply line for a heated gas formed from gap promoters and containing free radicals opens, and g) optionally introducing one heated gas, which contains radicals generated by thermal or non-thermal decomposition of gap promoters, by the feed line (s) opening into the adiabatic post-reactor or thermal or non-thermal generation of radicals from gap promoters by means of a suitable device within a predetermined volume inside of the adiabatic post-reactor, the temperature of the heated gas in the case of the generation of the radicals by thermal decomposition having at least the temperature at the point of the mouth of the feed line into the adiabatic post-reactor in the reaction mixture prevails, and in the case of the generation of the radicals by non-thermal decomposition has at least the temperature which corresponds to the dew point of the reaction mixture at the location of the mouth of the feed line in the adiabatic post-reactor, with the proviso that in the case of radical generation by thermal

This is decomposed by heating a gas containing diluted inert promoters or by passing one Gas containing cracking promoters via a heat source, the surface of which is flushed with inert gas.

21. A process for the production of ethylenically unsaturated halogen-containing aliphatic hydrocarbons by thermal cleavage of saturated halogen-containing aliphatic hydrocarbons, comprising the measures: a) introducing a feed gas stream containing heated gaseous halogen-containing aliphatic hydrocarbon into a reactor, b) setting such a pressure and such a temperature in the

Interior of the reactor, so that hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon are formed by thermal cleavage of the halogen-containing aliphatic hydrocarbon, f) introducing the product gas stream containing heated halogen-containing aliphatic hydrocarbon, hydrogen halide and ethylenically unsaturated halogen-containing aliphatic hydrocarbon from the reactor into an adiabatic reactor Post-reactor in which the reaction utilizing the heat supplied by the product gas stream while cooling the

Product gas is continued, and in the interior of which at least one supply line for a heated gas opens, and g) introducing a heated gas which contains radicals generated by thermal or non-thermal decomposition of fission promoters, through the supply line (s) or thermal opening into the adiabatic post-reactor or non-thermal generation of radicals from gap promoters by means of a suitable device within a predetermined volume inside the adiabatic post-reactor, the temperature of the heated gas in the case of the generation of the radicals by thermal decomposition at least that

Has temperature, which prevails in the reaction mixture at the point of the mouth of the feed line in the adiabatic post-reactor, and in the case of the generation of the radicals by non-thermal decomposition has at least the temperature which corresponds to the dew point of the reaction mixture at the point of the mouth of the feed line into the adiabatic post-reactor, with the proviso that in the case of radical generation by thermal decomposition, this is diluted by heating an inert gas

Gas containing gap promoters takes place or by passing a

Gas containing cracking promoters via a heat source, the

Surface is flushed with inert gas.

22. A reactor for carrying out the method according to claim 1 comprising the

Elements: i) feed line for the feed gas stream containing saturated halogen-containing aliphatic hydrocarbon opening into the reactor, ii) at least one feed line for a heated gas opening into the interior of the reactor, iii) source for a gap promoter connected to the feed line, iv) in the feed line attached device for generating radicals from gap promoters, v) optionally heating device for heating the gas in the feed line, vi) heating device for heating and / or maintaining the

23. A reactor for carrying out the method according to claim 1 comprising the elements:

i) feed line for the feed gas stream containing saturated halogen-containing aliphatic hydrocarbon opening into the reactor, ii) at least one feed line for a heated gas opening into the interior of the reactor, iii) source for a gap promoter connected to the supply line, viii) device for producing

Radicals from gap promoters iv) optionally heating device for heating the gas in the feed line, vi) heating device for heating and / or maintaining the gas

24. A reactor for carrying out the method according to claim 2 comprising the elements:

i) opening into the reactor feed line for the feed gas stream containing saturated halogen-containing aliphatic hydrocarbon, ix) device inside the reactor, which generates radicals within a predetermined volume inside the reactor from gap promoters, x) at least one into the predetermined volume inside the Reactor opening supply line for a heated gas and containing gap promoters, iii) source connected to the supply line for a gap promoter, v) heating device for heating the gas in the supply line, vi) heating device for heating and / or maintaining the

25. Reactor according to one of claims 22, 23 and 24, characterized in that the reactor is a tubular reactor.

26. Reactor according to one of claims 22, 23 and 24, characterized in that this is followed by an adiabatic post-reactor, which preferably contains the elements ii), iii) and iv) defined in claim 22.

27. Reactor according to one of claims 22, 23 and 24, characterized in that this is followed by an adiabatic post-reactor, which preferably contains elements ii), iii) and viii) defined in claim 23.

28. Reactor according to one of claims 22, 23 and 24, characterized in that this is followed by an adiabatic post-reactor, which preferably contains the elements ix), x), iii) and v) defined in claim 24.

29. Reactor for carrying out the method according to claim 20, characterized in that the adiabatic downstream of the reactor

Post-reactor contains elements ii), iii) and iv) defined in claim 22 or elements ii), iii) and viii) defined in claim 23.

30. Reactor according to one of claims 22, 23 and 24, characterized in that the feed line for the heated gas is a metal pipeline which opens into the reactor and which has a nozzle at its reactor-side end and which is preferably immediately before its reactor-side End has an electric heater for the heated gas.

31. Reactor according to one of claims 22, 23 and 24, characterized in that it has a generator for a thermal plasma, which is connected to the feed line to the reactor, the feed line having a further feed line for an inert gas and a further feed line for a gap promoter is connected.

32. Reactor according to one of claims 22, 23 and 24, characterized in that it is a device for generating an electrical discharge has, preferably a spark, barrier or corona discharge, which is connected to the feed line to the reactor.

33. Reactor according to one of claims 22, 23 and 24, characterized in that it has a device for generating a microwave discharge or a high-frequency discharge, which is connected to the feed line to the reactor.

34. Reactor according to one of claims 22, 23 and 24, characterized in that it has a device in which by means of a chemical

Reaction heat and radicals are generated at the same time, and which has at least two feed lines for the reactants and a burner or a catalytically active surface which opens directly into the reactor.

35. Reactor according to one of claims 22, 23 and 24, characterized in that it has a radiation source which is arranged in the feed line to the reactor or whose radiation is conducted into the feed line to the reactor.

36. Reactor according to one of claims 22, 23 and 24, characterized in that there is at least one porous ceramic in the form of a candle inside the reactor, the surface of which is coated with catalytically active metal and / or which is doped with catalytically active metal , and that the candle is equipped with a feed line for a gaseous reducing agent and / or a gap promoter for forwarding to the catalytically active metal.

37. Reactor according to one of claims 23 or 24, characterized in that at least one device is provided as the device viii) or ix), which comprises an electrically operated heating cartridge (1) which by means of a gas-tight, pressure and temperature-resistant bushing (4 ) is fixed in a housing (2), the housing (2) having at least one gas inlet (5) and a gas outlet (6) and wherein the inert gas inside the housing (2) is passed over the heating cartridge (1).

38. Reactor according to claim 37, characterized in that in the housing (2) a plurality of concentric annular gaps are formed, which on their longitudinal sides

The ends each have openings through which the gas containing the gap promoters is directed and deflected, so that the gas flow moves from the outside of the housing (2) through the annular gaps (3), the direction of flow in successive annular gaps (3) reverses, so that the gas flow from the outside of the housing (2) through the

Annular gap (3) moves, flows along the inside of the heating cartridge (1) and is then passed through the gas outlet (6) into the reaction chamber.

39. Reactor according to claim 38, characterized in that the gas outlet (6) is designed as a nozzle.

40. Reactor according to claim 37, characterized in that the heating cartridge (1) is provided with a ceramic jacket.

41. Reactor according to claim 37, characterized in that the housing (2) consists of ceramic and / or metal.

42. Reactor according to claim 37, characterized in that the bushing (4) is provided with a screw thread into which the heating cartridge (1) is screwed and fixed.

43. Reactor according to claim 37, characterized in that the outer wall of the housing (2) is coated with an inert material.

44. Reactor according to claim 37, characterized in that the

Heating cartridge (1) opposite inner wall is coated with inert material.

45. The reactor as claimed in claim 37, characterized in that the device has at least two separate gas feed lines, one feed line serving to feed an inert gas and the other feed line serving to feed a promoter substance.

46. Reactor according to claim 37, characterized in that the device is provided on its outer wall with a cone (8), on the outside of which there is a thread (7).

47. Reactor according to claim 37, characterized in that this one

Reaction tube (9) to which a holder (10) having a thread (11) and a projection (12) is welded, into which the device viii) or ix) is screwed.

48. Reactor according to claim 37, characterized in that it comprises an oven and a loop-shaped reaction tube in the oven, the oven having a radiation zone (16), a convection zone (17) and at least one non-heated compartment (18) into which Loops of the reaction tube are led out of or into the radiation or convection zone (16, 17), the at least one device viii) or ix) being located in at least one compartment (18) and being installed in the reaction tube, so that the feed gas stream can be brought into contact with a heated gas containing radicals at these points.

49. Reactor according to claim 27, characterized in that it has at least one device viii) or ix) according to claim 37.

50. Reactor according to one of claims 23 or 24, characterized in that as device viii) or ix) at least one device for generating and introducing a radical-containing non-thermal plasma is provided comprising a gas inlet (43), a plasma generation area (32) with at least two electrodes (33, 34) and a gas outlet (28) which opens into a reaction space (46), wherein Reaction space (46) and plasma generation area (32) are spatially separated.

51. Reactor according to claim 50, characterized in that the device viii) or ix) has a substantially cylindrical housing (20) with a rear

End (21) and a front end (22), and that the housing (20) along its outside (23) is at least partially provided with a cone (24) and a thread (25) made of a conductive material, which is among the conditions prevailing in the reactor is stable.

52. Reactor according to claim 50, characterized in that the device viii) or ix) in the interior of the housing (20) has a ceramic tube (30), which is arranged axially symmetrically to the axis (26) and is closed on one side in the region of the gas outlet (28), the The outside diameter is selected such that there is an annular gap on the inside (31) of the housing (20) in which the plasma is generated.

53. Reactor according to claim 52, characterized in that the inside of the ceramic tube (30) is coated with a metal application and forms an electrode (33) of a plasma generating device and the other electrode (34) through the electrically conductive housing (20) is formed

54. Reactor according to claim 53, characterized in that in the interior of the ceramic tube (30) there is a further tube (35) which is arranged axially symmetrically with respect to the cylinder axis (26) and is open on both sides and which is by means of a against the closed end (36) of the ceramic tube (30) supporting spring (37) in the region of the front end (22) of the housing (20) within the ceramic tube (30) is fixed at a distance, so that between the outside of the further tube (35) and the inside of the

Ceramic tube (30) forms an annular gap (38).

55. Reactor according to claim 54, characterized in that the spring (37) also connects a high-voltage feed (39) arranged axially symmetrically within the further tube (35) to the electrically conductive coating forming the electrode (33).

56. Reactor according to claim 55, characterized in that the device viii) or ix) at the rear end (21) of the cylindrical housing (20) has a cylindrical flange (29) which is fastened to the outer region of the cylindrical housing (20), has in the middle an insulating, gas-tight and pressure-resistant passage (41) through which a

High-voltage supply (39) is guided axially into the housing (20) and has a gas inlet (43) which leads from an outer connection piece via a channel (42) into the inner region of the further pipe (35), the rear side the further tube (35) is sealed with a sealing web (44) of the flange (29).

57. Reactor according to claim 56, characterized in that the flange (29) on its side facing the housing (20) has an annular groove (45), the diameter of which is dimensioned such that it seals the annular gap (38) between another tube ( 35) and ceramic tube (30) with the annular gap of

Plasma sealing area (32) between the ceramic tube (30) and the inside of the housing (31) sealingly connects.

58. Reactor according to claim 50, characterized in that the outer wall of the device viii) or ix), in particular the part protruding into the reaction space, is coated with a metal oxide, ceramic, boron nitride or silicon nitride.

59. Reactor according to claim 50, characterized in that it has a reaction tube (48) to which a thread (50) and a

Projection (51) having holder (49) is welded, into which the device viii) or ix) is screwed.

60. Reactor according to claim 50, characterized in that it comprises an oven and a loop-shaped reaction tube in the oven, the oven having a radiation zone (16), a convection zone (17) and at least two non-heated compartments (18) into which Loops of the reaction tube are guided out of or into the radiation or convection zone (16, 17), the at least one device viii) or ix) being located in at least one compartment (18) and being installed in the reaction tube, so that the feed gas stream can be brought into contact with a heated gas containing radicals at these points.

61. Reactor according to claim 27, characterized in that it has at least one device viii) or ix) according to claim 50.

62. Reactor according to one of claims 23 or 24, characterized in that at least one device for generating and introducing a gas containing radicals is provided as the device viii) or ix) comprising a separate from the actual reaction space with this but via at least one opening in connection standing compartment which has devices for introducing a gas containing cracking promoters and devices for irradiating this gas, so that in

Compartment photolytically radicals are generated, which emerge through the at least one opening in the reaction space.

63. Reactor according to claim 62, characterized in that the device viii) or ix) has an optical window and / or another light supply in the

Has compartment.

64. Reactor device according to claim 63, characterized in that the optical window and / or the translucent termination of the other light supply line is coated with an optically semitransparent layer which consists of a metal which is suitable as a hydrogenation catalyst.

65. The reactor as claimed in claim 62, characterized in that the device viii) or ix) comprises two conical sleeves (54, 57) which are fitted in such a way that a space (67) is formed between the sleeves (54) and (57). forms, which is provided with at least one gas supply line, that one separated from the reaction space (68) and from the outer space (69)

Forms compartment and that the sleeve (57) which is arranged further away from the reactor contains an optically transparent window (58) and / or another light supply line.

66. Reactor according to claim 62, characterized in that

Irradiation devices are provided which allow the entire compartment and the adjoining reaction space to be irradiated.

67. Reactor according to claim 65, characterized in that the space

(67) has a further gas inlet (72) which is guided into the compartment close to the surface of the optical window and / or the other light feed line and the purging of the optical window and / or the other light feed line and its surroundings with inert gas or with inert gas and enables hydrogen.

68. Reactor according to claim 62, characterized in that it has a reaction tube to which a holder (53) having a thread (52) and a projection is welded, into which the device viii) or ix) is screwed.

69. Reactor according to claim 62, characterized in that it comprises an oven and a loop-shaped reaction tube in the oven, the oven having a radiation zone (16), a convection zone (17) and at least one non-heated compartment (18) into which Loops of the reaction tube are led out of or into the radiation or convection zone (16, 17), the at least one device viii) or ix) being located in at least one compartment (18) and into the reaction tube is installed so that the educt gas flow can be brought into contact with a heated and radical-containing gas at these points.

70. Reactor according to claim 27, characterized in that it has at least one device viii) or ix) according to claim 50.