EP1740675A1

EP1740675A1 - Method for the production of olefins and synthesis gas

Info

Publication number: EP1740675A1
Application number: EP05732387A
Authority: EP
Inventors: Bernd Bartenbach; Julian PRÖLSS; Petra Schmitz-Bäder; Christian Weichert; Kai Rainer Ehrhardt
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2004-04-22
Filing date: 2005-04-21
Publication date: 2007-01-10
Also published as: CN1942559B; DE102004019649A1; US20090152499A1; JP2007533696A; CA2561980A1; WO2005103205A1; CN1942559A; KR20070007148A

Abstract

The invention relates to a method for simultaneously producing at least one olefin and synthesis gas.

Description

Process for the production of olefins and synthesis gas

description

The present invention relates to a process for the simultaneous production of at least one olefin, optionally additionally at least one unsaturated hydrocarbon different from olefins and synthesis gas.

It is known for the production of olefins to subject saturated aliphatic hydrocarbons (paraffins) and their mixtures to a catalytically induced, autothermal, oxidative dehydrogenation. For example, A. Beretta et al. in Chem. Eng. Be. 56 (2001), 779 - 787 the influence of a heterogeneous catalyst in the high temperature production of ethene. A. Beretta et al. further describe in J. Catal. 184 (1999), 455-468 the influence of a Pt / Al ₂ O ₃ catalyst on the oxidative dehydrogenation of propane in a tubular reactor and in J. Catal. 184 (1999), 469-478 the production of olefins by platinum-catalyzed oxidative dehydrogenation of propane under autothermal conditions.

M. Huff et al. describe in J. Phys. Chem. 97 (1993), 11815-11822 the production of ethene by oxidative dehydrogenation of ethane and in J. Catal. 149 (1994), 127-141 the production of olefins by oxidative dehydrogenation of propane and butane. The reaction takes place in each case over catalyst monoliths which are coated with Pt, Rh or Pd.

WO 00/14180 describes a process for the production of olefins, in which paraffins are reacted with oxygen in the presence of a monolithic catalyst based on a metal of subgroup VIII under autothermal conditions.

A. S. Bodke et al. report in Science 285 (1999), 712-715 about an increase in the selectivity in the partial oxidation of ethane to ethene by adding hydrogen to the reaction mixture. The reaction takes place in the presence of a platinum-tin catalyst.

WO 01/14035 describes a process for the production of olefins, in which paraffins or paraffin mixtures are reacted with oxygen in the presence of hydrogen and a catalyst based on a metal of subgroup VIII under autothermal conditions.

In the documents mentioned above, regardless of the assumed mechanism of the gas phase reaction, the presence of a heterogeneous catalyst is regarded as essential for successful autothermal production of olefins.

It is known to produce acetylene in uncatalyzed processes which are based on the pyrolysis or partial oxidation of hydrocarbons. For example, natural gas, various petroleum fractions (eg naphtha) and even residual oils (immersion flame processes) can be used as starting substances. In principle, thermodynamic and kinetic parameters have a decisive influence on the choice of reaction conditions in the pyrolytic or oxidative production processes of acetylene. Important prerequisites for such processes are generally a rapid supply of energy, short dwell times of the starting materials or reaction products, low partial pressure of acetylene and rapid quenching of the gases formed. For example, EP-A-1 041 037 describes a process for the production of acetylene and synthesis gas by thermal treatment of a starting mixture which contains one or more hydrocarbons and also an oxygen source, the starting mixture being heated to a maximum of 1400 ° C. in a reactor Bring reaction and then cooled.

It is also known to produce olefins in uncatalyzed high temperature processes. R.M. Deanesly describes in petrol. Refiner, 29 (September 1950), 217, the autothermal cracking of hydrocarbon streams for the production of ethene. The reaction gases are passed through heat exchangers in which the feed streams are preheated.

R. L. Mitchel describes in petrol. Refiner, 35, No. 7, pp. 179 - 182 the mechanism of the non-catalytic gas phase oxidation of hydrocarbons and the influence of various parameters on this reaction. This article deals essentially with the oxidation to alcohols, aldehydes, etc. The aspect of oxidative dehydrogenation is only mentioned in passing and for the formation of olefins, especially ethene and propene, a maximum yield in a temperature range of 700 to 800 ° C.

WO 00/06948 describes a process for recycling a hydrocarbon-containing fuel using an exothermic pre-reaction in the form of a so-called "cold flame".

WO 00/15587 describes a process for the production of monoolefins and synthesis gas by oxidative dehydrogenation of gaseous paraffinic hydrocarbons by autothermal cracking of ethane, propane and butanes. The reaction can take place in the presence or absence of a catalyst, but teaching is used to convert a fuel-rich, non-ignitable mixture to a catalyst.

GB-A-794,157 describes a process for the production of acetylene and ethylene by partial combustion of methane and / or ethane in two successive reaction zones, the first reaction zone being operated at a pressure above atmospheric pressure and the second at a lower pressure.

GB-A-659,616 describes a process for the oxidative cracking of non-aromatic hydrocarbon streams, in which they are preheated to a temperature in the range from 540 to 870 ° C., with a temperature likewise in this range. mixes richly preheated oxygen-containing gas and then subjects it to partial combustion. The preheating temperature is above the self-ignition temperature of the mixture. The oxygen content is in a range from 10 to 35% based on the hydrocarbon used. The reaction zone used is designed to generate a vortex flow of the reaction gases, so that in this process the combustion gases are mixed with fresh fuel in the reaction zone.

GB-A-945,448 describes a process for the production of olefins from saturated aliphatic hydrocarbon streams by reaction with oxygen at temperatures of less than 700 ° C. The temperature is still above the autoignition temperature. The ratio of hydrocarbon feed to oxygen in the reaction is greater than about 2: 1. The reactants used are mixed in a mixing zone to produce turbulence, and the resulting vortex flow can continue into the reaction zone. Thus, even with this method, fuel gases can be mixed with fresh fuel in the reaction zone.

US 3,095,293 describes a process for the production of ethene by incomplete combustion of naphtha in the presence of water vapor. Acetylene and CO ₂ are first removed from the reaction gas by absorption processes, then the reaction gas is fed to several cooling steps in heat exchangers and partially condensed, ethene is isolated as the main product from the condensate and the uncondensed fraction is burned, using the heat generated to generate the water vapor. With regard to the combustion device used, reference is made to US 2,750,434.

US 2,750,434 describes a process for converting hydrocarbons into unsaturated hydrocarbons, aromatic hydrocarbons and acetylene. For this purpose, these are subjected to a cracking process at high temperatures in the range from approximately 700 to 1900 ° C. and short reaction times in the millisecond range. The reaction takes place in a tangential reactor with a permanent pilot flame, which generates hot combustion gases, which are brought into contact with the supplied hydrocarbon. There is thus first a separate combustion in the pilot flame and then in a subsequent step the further implementation of the hydrocarbons used in the presence of the combustion gases.

The object of the present invention is to provide a process for the simultaneous production of olefins and other economically interesting coupling products. Starting hydrocarbons available in petrochemical Verbund sites should preferably be used, in particular the use of higher alkanes and aromatic-rich hydrocarbon mixtures should also be possible. Surprisingly, it was found that this problem was solved by a method can be achieved by subjecting very fuel-rich (rich) starting hydrocarbon mixtures to a single-stage, autothermal, non-catalyzed reaction at relatively low temperatures (≤ 1400 ° C).

The present invention therefore relates to a process for the simultaneous production of at least one olefin and synthesis gas, in which

a) provides a starting mixture which contains at least one hydrocarbon and at least one oxygen source, the fuel number of the mixture being at least 4,

b) the starting mixture is heated to a temperature of at most 1400 ° C. and subjected to a one-stage, autothermal, non-catalyzed reaction at this temperature in a reaction zone,

c) subjecting the reaction gas obtained in step b) to rapid cooling.

In the context of the present invention, the fuel number is defined as the stoichiometric ratio of the oxygen required for complete combustion of the hydrocarbon contained in the starting mixture used to the oxygen available for combustion. According to a general definition, the number of fuels corresponds to the reciprocal of the number of air. The fuel number of the starting mixture is preferably at least 5.

An autothermal conversion is understood to mean a conversion in which the thermal energy required results from partial combustion of a feedstock.

According to the invention, the autothermal conversion of the starting mixture takes place in one stage. The term one-stage is understood both macroscopically and microscopically. The one-step reactions do not include those in which the reaction takes place successively in several reaction zones. The one-stage reactions also do not include those in which the reaction takes place in several stages in a single reaction zone. This is the case, for example, if part of the hydrocarbon used is first burned and another part is reacted in the form of a mixture with the hot reaction gases resulting from this combustion. One-stage in the sense of the invention thus also means "without a separate pre-reaction". In individual cases, this does not apply to heating the starting mixture in an exothermic pre-reaction in the form of a so-called "cold flame", as described in WO 00/06948. This form of preheating should be permitted in the method according to the invention, but is not a preferred embodiment.

The one-step process according to the invention preferably comprises an essentially complete mixing of the hydrocarbon used and the oxygen source before the autothermal reaction. Suitable devices for realizing a one-step implementation are described in more detail below. In general, the reaction zone is designed as a system with low backmixing. This preferably has essentially no macroscopic mass transfer against the direction of flow.

According to the invention, the autothermal reaction of the starting mixture continues to be non-catalytic, i.e. in the absence of catalysts, as described for example for the oxidative dehydrogenation of saturated hydrocarbons from the prior art.

The method according to the invention serves the simultaneous production of several valuable products. At least one olefin is preferably obtained, which is selected from ethene and / or propene. In addition, other higher olefins such as butenes, pentene, etc. can be obtained.

Hydrogen and carbon monoxide are obtained as further valuable products in the process according to the invention, which can be isolated as mixtures (so-called synthesis gas). Synthesis gas is an important d-building block that is used in many ways (oxo synthesis, Fischer-Tropsch synthesis, etc.).

In addition, further unsaturated hydrocarbons can be obtained as valuable products in the process according to the invention. These are preferably selected from alkynes, especially acetylene (ethyne), aromatics, especially benzene, and mixtures thereof. In a special embodiment, the process is suitable for at least partial dealkylation of alkylated aromatics, e.g. of BTX fractions. Other valuable products that may arise are e.g. short chain alkanes such as methane. Suitable process configurations for obtaining at least one of the aforementioned additional products are described in more detail below.

The process according to the invention enables the production of the aforementioned valuable products, in particular olefins, from a large number of different starting hydrocarbons and hydrocarbon mixtures. The composition of the reaction gas can be controlled, among others, using the following parameters:

Composition of the starting mixture (type and amount of hydrocarbons, type and amount of oxygen source, additional components) and - reaction conditions in the autothermal, uncatalyzed reaction (reaction temperature, residence time, supply of reactants to the reaction zone).

Step a) A fuel-rich (fat) starting mixture is provided for the reaction. The number of fuels at the time of initiation of the autothermal reaction is preferably at least 5, particularly preferably at least 6.5 and in particular at least 9.

The hydrocarbon provided in step a) is preferably selected from alkanes, aromatics and alkane and / or aromatic-containing hydrocarbon mixtures. In principle, hydrocarbon mixtures can contain the individual components in any amount. In the case of mixtures which have at least one alkane and at least one aromatics, both alkanes and aromatics can be in excess. Suitable alkanes are e.g. B. low molecular weight, under normal conditions gaseous CC ₄ alkanes (methane, ethane, propanes, butanes) and higher molecular weight, under normal conditions liquid or solid alkanes, for example C ₅ -C ₃₀ alkanes (pentanes, hexanes, heptanes, octanes, nonanes , Etc.). Suitable aromatics are e.g. B. benzene, condensed aromatics such as naphthalene and anthracene, and their derivatives. These include, for example, alkylbenzenes, such as toluene, o-, m- and p-xylene and ethylbenzene.

The hydrocarbons are preferably used in step a) in the form of a naturally or technically available hydrocarbon mixture. These are preferably selected from natural gases, liquid gases (propane, butane, etc.), light petrol, pyrolysis gasoline and mixtures thereof. The hydrocarbon mixture is preferably selected from light petroleum, pyrolysis gasoline or fractions or secondary products of the pyrolysis gasoline, and mixtures thereof. Pyrolysis gasoline is obtained from steam cracking from naphtha and is characterized by its high aromatic content. Preferred secondary products of pyrolysis gasoline are its

(Partial) hydrogenation. Another preferably used aromatic mixture is the BTX aromatic fraction, which essentially consists of benzene, toluene and xylenes.

For the production of product mixtures which have high proportions of olefins, in particular ethene and / or propene, hydrocarbons which consist of at least one alkane or contain a high proportion of alkane are preferably used.

For the production of product mixtures which contain high proportions of non-alkylated aromatics (e.g. benzene) or aromatics with low proportions of alkyl substituents, hydrocarbons which consist of alkyl aromatics or contain a ^' high proportion of alkyl aromatics are preferably used. These are subjected to a partial or complete dealkylation under the conditions of the autothermal, non-catalyzed reaction according to the invention.

The oxygen source used in step a) is preferably selected from molecular oxygen, oxygen-containing gas mixtures, oxygen-containing compounds and mixtures thereof. In a preferred embodiment, molecular oxygen is used as the oxygen source. This enables the salary of the To keep the starting mixture of inert compounds low. However, it is also possible to use air or air / oxygen mixtures as the oxygen source. As oxygen-containing compounds, for example, water, preferably in the form of water vapor, and / or carbon dioxide are used. The use of carbon dioxide can be recycled carbon dioxide from the reaction gas obtained in the autothermal reaction.

The starting mixtures used in the process according to the invention can contain at least one further component in addition to the hydrocarbon and oxygen components. These include, for example, recycled reaction gas and recycle gases from the separation of the reaction gas, such as hydrogen, crude synthesis gas, CO, CO ₂ and unreacted starting materials, and further gases for influencing the yield and / or selectivity of certain products, such as hydrogen.

Step b)

Step b) of the process according to the invention basically comprises the following individual steps: optionally preheating at least one component, optionally premixing at least some of the components, initiating the autothermal reaction, autothermal reaction. Since the reaction in step b) takes place in one step according to the invention, preheating and / or premixing is only carried out under conditions which do not permit a separate prereaction. The only exception is an exothermic pre-reaction in the form of a so-called "cold flame". With regard to preheating by means of a cold flame, reference is made to the disclosure of WO 00/06948.

In a first embodiment of the method according to the invention, the starting mixture provided in step a) is not additionally heated before it is used in step b). In a second embodiment, the starting mixture provided in step a) is heated to a temperature which is lower than the self-ignition temperature of the mixture before being used in step b). Alternatively, heating takes place through an exothermic pre-reaction in the form of a cold flame.

Initiation of the autothermal reaction and autothermal implementation go directly into one another.

Before the reaction, the components forming the starting mixture can be partially or completely premixed. Before, during or after the premixing, some or all of the components can be preheated. Gaseous components are preferably not preheated before the autothermal reaction is initiated. Liquid components are preferably evaporated and only then mixed with gaseous components or fed to the initiation of the autothermal reaction. In a suitable embodiment of the apparatus, when using liquid components, reactors are used which use the "cold flame" concept. In the autothermal reaction, the starting mixture is heated to a temperature of at most 1400 ° C. This can be done by supplying energy and / or an exothermic reaction of the starting mixture. The initiation of the exothermic reaction can take place in the presence or in the absence of a catalyst. The exothermic reaction, such as the autothermal reaction, is preferably initiated in the absence of a catalyst. In a suitable embodiment, the, optionally preheated, starting mixture is ignited, followed immediately by the autothermal reaction in the reaction zone.

The starting mixture is ignited in a suitable device. These include special burners in which the starting mixture is reacted with the formation of flames.

The initiation of the autothermal reaction is followed by the reaction in at least one reaction zone under autothermal conditions. This conversion is preferably carried out essentially adiabatically, i. H. there is essentially no heat exchange with the surroundings. The heat of reaction released by partial combustion of the starting mixture serves for the thermal treatment of the starting mixture to produce a product mixture according to the invention which comprises at least one olefin, optionally at least one unsaturated hydrocarbon and synthesis gas different from olefins. The reaction types on which this implementation is based include combustion (total oxidation), partial combustion (partial oxidation or oxidative pyrolysis) and pyrolysis reactions (reactions without the participation of oxygen).

The reaction in step b) is preferably carried out at a temperature in the range from 600 to 1300 ° C., preferably from 800 to 1200 ° C.

The residence time of the reaction mixture in the reaction zone is preferably 0.01 s to 1 s, particularly preferably 0.02 s to 0.2 s.

The reaction for producing the product mixture obtained according to the invention can be carried out by the process according to the invention at any pressure, preferably in the range of atmospheric pressure.

The devices used for implementation in step b) must be suitable for realizing a one-stage implementation. In general, the reaction zone is designed as a system with low backmixing. This preferably has essentially no macroscopic mass transport against the flow direction. The device used in step b) preferably enables the autothermal conversion to be stabilized in a narrow flame front.

The components forming the starting mixture are preferably mixed completely before the reaction. If the mixture is not completely mixed, there may be losses in the yield of the desired target compounds. In a suitable apparatus configuration, the reaction zone is designed as a tubular reactor.

A so-called pore burner can advantageously be used for the implementation in step b). Such burners are described, for example, in the dissertation by K. Pickenecker, University of Erlangen-Nuremberg, VDI Progress Reports, Series 6, No. 445 (2000), to which reference is made in full here. Furthermore, a premixing burner lock as described in EP-A-1 182 181 can preferably be used in step b). Reference is also made in full to the disclosure of this document.

Step c)

The reaction of the reaction mixture in step b) is followed, according to the invention, by rapid cooling of the reaction gases obtained in step c). This can be done by direct cooling, indirect cooling or a combination of direct and indirect cooling. In direct cooling (quenching), a coolant is brought into direct contact with the hot reaction gases in order to cool them down. With indirect cooling, thermal energy is extracted from the reaction gas without it coming into direct contact with a coolant. Indirect cooling is preferred, since this generally enables the thermal energy transferred to the coolant to be used effectively. For this purpose, the reaction gases can be brought into contact with the exchange surfaces of a conventional heat exchanger. The waste heat systems used in Texaco gasification and steam crackers, for example, are suitable. The heated coolant can be used, for example, to heat the starting materials in the process according to the invention or in a different endothermic process. Furthermore, the heat extracted from the reaction gases can also be used, for example, to operate a steam generator. A combined use of direct cooling (Vörquensch) and indirect cooling is also possible, the reaction gas obtained in step c) preferably being cooled to a temperature of less than 1000 ° C. by direct cooling (Vorquensch). Direct cooling can be carried out, for example, by feeding quench oil, water, steam or cold return gases. When using hydrocarbon agents as quenching agents, cracking processes can be initiated at the same time (cracking of the hydrocarbons contained in the quenching agent).

Step d)

For working up, the reaction gas obtained in step c) can be subjected to at least one separation and / or purification step d). For the separation, the reaction gas can, for example, be subjected to a fractional condensation or the liquefied reaction gases can be subjected to a fractional distillation. Suitable devices and methods are known in principle to the person skilled in the art. Separate Components can be isolated from the reaction gas, for example by washing with suitable liquids, or obtained by fractional adsorption / desorption. For example, alkynes, in particular acetylene, can be separated off using an extractant, for example N-methylpyrrolidone or dimethylformamide.

As described above, the process according to the invention enables the production of additional unsaturated hydrocarbons other than olefins.

In a special embodiment of the method according to the invention, this involves at least one dealkylated aromatic, in particular benzene. For this purpose, the starting mixture provided in step a) contains at least one alkyl aromatic. This starting mixture is then preferably selected from pyrolysis gasoline and partially hydrogenated pyrolysis gasoline. A preferably used aromatic mixture is the BTX aromatic fraction. According to this embodiment, the reaction in step b) is preferably carried out at a temperature in the range from 900 to 1250 ° C., preferably from 950 to 1150 ° C. In this embodiment, the residence time of the reaction mixture in the reaction zone is preferably 0.05 s to 1 s.

In a further special embodiment of the method according to the invention, this is at least one alkyne. For this purpose, the starting mixture provided in step a) contains at least one alkane. According to this embodiment, the reaction in step b) is preferably carried out at a temperature in the range from 1150 to 1400 ° C., preferably from 1250 to 400 ° C. In this embodiment, the residence time of the reaction mixture in the reaction zone is preferably 0.01 s to 0.1 s.

The invention is illustrated by the following, non-limiting examples.

Examples:

The following examples were carried out in a tubular reactor (length to diameter ratio (LJD) = 60), which was operated adiabatically to a good approximation. Liquid feed streams were pre-evaporated. All feed streams were premixed and fed to the reactor. The initiation and stabilization of the autothermal reaction was ensured by using a pore burner (foam ceramic with a porosity of approx. 80%). The cracked gas was quenched by indirect cooling.

Example 1: The partial oxidation of ethane in a gas mixture which consists of 61% by volume of ethane, 21% by volume of oxygen and 18% by volume of nitrogen provides ethylene with a molar carbon yield at an ethane conversion of 83% of 51%. The cracked gas continues to consist of methane, synthesis gas (CO and H ₂ ), water vapor and nitrogen. In addition, small amounts of propene, CO ₂ and soot are produced. Example 2:

The partial oxidation of ethane (33% by volume of the raw gas) and xylene (12% by volume of the raw gas) with oxygen (24% by volume of the raw gas) with the addition of water vapor (31% by volume of the raw gas) yields ethylene with a molar carbon yield of 23%. The yields are 4% for toluene and 19% for benzene. Other cracked gas components are methane, synthesis gas, water vapor and soot and small amounts of propene and CO ₂ .

Example 3:

The partial oxidation of octane (35% by volume of the raw gas) with oxygen (35% by volume of the raw gas) with the addition of water vapor (30% by volume of the raw gas) provides ethylene with a molar carbon yield of 48%. The yields are 12% for propene and 4% for benzene. Other fission gas components are methane, synthesis gas, water vapor and small amounts of ethyne, CO ₂ and soot.

Example 4:

The partial oxidation of partially hydrogenated pyrolysis gasoline from a steam cracker (85% by volume aromatics / 15% by volume aliphates) with oxygen (16% by volume of the raw gas) in the presence of water vapor (40% by volume of the raw gas) provides ethylene with a molar carbon yield of 10% and benzene with a molar carbon yield of 33%. Other cracked gas components are methane, synthesis gas, water vapor, soot and small amounts of ethyne, toluene, xylene and CO ₂ .

Claims

claims

1. A process for the simultaneous production of at least one olefin and synthesis gas, in which

5 a) provides a starting mixture which contains at least one hydrocarbon and at least one oxygen source, the fuel number of the mixture being at least 4,

o b) the starting mixture is heated to a temperature of at most 1400 ° C. and subjected to a one-stage, autothermal, uncatalyzed reaction at this temperature in a reaction zone, c) the reaction gas obtained in step b) is subjected to rapid cooling.

2. The method of claim 1, wherein the fuel number of the starting mixture is at least 5, particularly preferably at least 6.5, in particular at least 9. 0 The method according to one of claims 1 or 2, wherein the reaction zone is designed as a system with low backmixing.

4. The method according to any one of the preceding claims, wherein the hydrocarbon used in step a) 5 is selected from alkanes, aromatics and alkane and / or aromatic-containing hydrocarbon mixtures.

5. The method according to claim 4, wherein the hydrocarbon in step a) is used in the form of a naturally or technically available hydrocarbon mixture.

6. The method according to claim 5, wherein the hydrocarbon mixture is selected from natural gases, liquefied gases, petroleum fractions and pyrolysates and mixtures thereof Mixtures of these. 8. The method according to any one of the preceding claims, wherein the oxygen source used in step a) is selected from molecular oxygen, oxygen-containing gas mixtures, oxygen-containing compounds and mixtures thereof.

9. The method according to claim 8, wherein air or air / oxygen mixtures are used as oxygen source in step a).

10. The method according to claim 8, wherein the oxygen source used in step a) comprises water vapor and / or carbon dioxide as the oxygen-containing compound.

11. The method according to any one of claims 1 to 10, wherein the starting mixture provided in step a) is not additionally heated before its use in step b).

12. The method according to any one of claims 1 to 10, wherein the starting mixture provided in step a) before its use in step b) is additionally heated to a temperature which is lower than the self-ignition temperature of the mixture or wherein the heating by exothermic pre-reaction in the form a cold flame occurs.

13. The method according to any one of the preceding claims, wherein the heating of the starting mixture in step b) is carried out by the supply of energy and / or an exothermic reaction of the starting mixture.

14. The method of claim 13, wherein the heating comprises an exothermic reaction of the starting mixture that is initiated in the presence of a catalyst.

15. The method according to any one of the preceding claims, wherein the reaction in step b) takes place at a temperature in the range from 600 to 1300 ° C, preferably from 800 to 1200 ° C.

16. The method according to any one of the preceding claims, wherein in step b) the residence time of the reaction mixture in the reaction zone is 0.01 s to 1 s, particularly preferably 0.02 s to 0.2 s.

17. The method according to any one of the preceding claims, wherein the rapid cooling of the reaction mixture in step c) is carried out by direct cooling, indirect cooling or a combination of direct and indirect cooling.

18. The method according to any one of the preceding claims, wherein the reaction mixture obtained in step c) is subjected to at least one separation and / or purification step d).

19. The method according to any one of the preceding claims, in which at least one unsaturated hydrocarbon other than olefins is additionally obtained.

20. The method according to claim 19, wherein the starting mixture provided in step a) contains at least one alkyl aromatic and at least one dealkylated aromatic is obtained as an unsaturated hydrocarbon other than olefins.

21. The method according to claim 20, wherein the reaction in step b) takes place at a temperature in the range from 900 to 1250 ° C, preferably from 950 to 1150 ° C.

22. The method according to any one of claims 20 or 21, wherein in step b) the residence time of the reaction mixture in the reaction zone is 0.05 s to 1 s.

23. The method according to claim 19, wherein the starting mixture used in step a) contains at least one alkane and at least one alkyne is obtained as an unsaturated hydrocarbon other than olefins.

24. The method according to claim 23, wherein the reaction in step b) takes place at a temperature in the range from 1150 to 1400 ° C, preferably from 1250 to 1400 ° C.

25. The method according to any one of claims 23 or 24, wherein in step b) the residence time of the reaction mixture in the reaction zone is 0.01 s to 0.1 s.