WO2014135445A1

WO2014135445A1 - Chemical conversion method at a constant hydrogen halide partial pressure

Info

Publication number: WO2014135445A1
Application number: PCT/EP2014/053889
Authority: WO
Inventors: Stefan Bitterlich; Steffen Tschirschwitz; Jochen BÜRKLE; Michael HÜBNER
Original assignee: Basf Se
Priority date: 2013-03-07
Filing date: 2014-02-27
Publication date: 2014-09-12
Also published as: CN105189416A; EP2964594A1

Abstract

The invention relates to a method, preferably an isomerization method, for chemically converting at least one hydrocarbon in the presence of an ionic liquid and a hydrogen halide (HX). The chemical conversion is carried out in a device (V1), a gas phase being in direct contact with a liquid reaction mixture in the device (V1). The gas phase and the liquid reaction mixture each contain the hydrogen halide, and at least one hydrocarbon and the ionic liquid are additionally contained in the liquid reaction mixture. Gaseous HX is introduced into the device (V1) such that the hydrogen halide partial pressure is kept at a constant level in the gas phase. Among others, the ionic liquid used in the respective chemical conversion, in particular in an isomerization method, can be regenerated using the method according to the invention.

Description

The present invention relates to a chemical conversion process, preferably an isomerization process, of at least one hydrocarbon in the presence of an ionic liquid and a hydrogen halide (HX). The chemical reaction is carried out in a device (V1), wherein in the device (V1) is a gas phase in direct contact with a liquid reaction mixture. The gas phase and the liquid reaction mixture each contain the hydrogen halide, in the liquid reaction mixture additionally at least one hydrocarbon and the ionic liquid are included. Gaseous HX is introduced into the device (V1) so that the hydrogen halide partial pressure is kept constant in the gas phase. By means of the process according to the invention, it is possible to regenerate (inter alia) the ionic liquid used in the particular chemical reaction, in particular in an isomerization.

Ionic liquids, in particular acidic ionic liquids, are suitable, inter alia, as catalysts for the isomerization of hydrocarbons. A corresponding use of an ionic liquid is disclosed for example in WO 201 1/069929, where a special selection of ionic liquids in the presence of an olefin is used for the isomerization of saturated hydrocarbons, in particular for the isomerization of methylcyclopentane (MCP) to cyclohexane. An analogous process is described in WO 201 1/069957, although the isomerization does not take place in the presence of an olefin, but rather with a copper (II) compound.

In general, ionic liquids on the one hand and hydrocarbons (organic phases) on the other hand are immiscible or very difficult to mix, forming two separate phases. In order to be able to use the catalysis effect mentioned, intensive contact must be established between the organic phase and the ionic liquid. For this purpose, the two phases are often mixed in stirred tanks with intensive stirring to obtain dispersions. Depending on parameters such as the type of ionic liquid or the organic phase or the phase ratio, the dispersion may be present either as a dispersion of an ionic liquid in the organic phase or it may be a dispersion of the organic phase in the ionic liquid.

Especially in a continuous procedure is in a chemical reaction process, especially in an isomerization, over the organic phase, a subset and / or constituents of the ionic liquid used, in particular the anion portion, in the form of metal halides such as aluminum chloride and / or hydrogen halides such as HCl, discharged, causing a Reduction of the activity of the chemical reaction method, preferably used as a catalyst, ionic liquid is observed.

EP-A 2 455 358 relates to processes for the regeneration and activity maintenance of an ionic liquid used as catalyst, in particular in connection with the preparation of alkylates by alkylation reactions. In this case, hydrogen halide or halogenated hydrocarbons are added to the catalyst (acidic ionic liquid) in the feed stream during the alkylation reaction. The addition of the hydrogen halide or halogenated hydrocarbon may also be continuous. Furthermore, EP-A 2 455 358 discloses an analogous process for the preparation of alkylates by alkylation reaction using isobutene and C4-alkenes as a feed stream and acidic ionic liquids as a catalyst. However, in neither of the two processes disclosed in EP-A 2 455 358 is the addition of a hydrogen halide carried out so that the hydrogen halide partial pressure is kept constant above the corresponding reaction mixture in a gas phase.

A. Berenblyum (Applied Catalysis, A: General 315 (2006) 128-134) discloses studies on the catalytic activity of chloroaluminate-containing ionic liquids in connection with the isomerization of heptane. Investigations are carried out on the HCl solubility in the chloroaluminate-containing ionic liquid and on the aluminum chloride distribution between chloroaluminate-containing ionic liquid and heptane. In the investigated system, HCl is identified as catalytically active component and aluminum chloride as cocatalyst. The loss of activity of the chloroaluminate-containing ionic liquid is attributed to the loss of HCl and the formation of an acid-soluble oil that poisoned the catalyst. The experiments are (at least partially) carried out with continuous addition of HCl, but even there is no indication that above the corresponding reaction mixture in a gas phase, the hydrogen halide partial pressure is kept constant.

US-A 2010/0065476 discloses methods for measuring and adjusting the flow of a halogen-containing additive in a continuous reactor process, for example in alkylations of olefins or aromatics or in dehydrogenation processes. The halogen-containing additives may be Bronsted acids such as hydrogen chloride, hydrogen bromide or fluorinated alkanesulfonic acids and metal halides such as sodium chloride or copper chloride. Furthermore, this document discloses apparatuses for carrying out the corresponding processes, comprising a reactor containing an ionic liquid, measuring devices for determining the halogen concentration in the reactor outlet and a control system for controlling the halogen concentration. The addition of the halogen-containing additive is not necessarily fixed to a mold in the process according to US-A 2010/0065476, as gaseous hydrogen chloride or a solid such as sodium chloride can be used as a halogen-containing additive, for example, in dissolved form in the continuous reactor process can be added. If a gaseous halogen-containing additive such as hydrogen chloride is used, however, US-A 2010/0065476 contains no indication that the partial pressure of, for example, hydrogen chloride must be kept constant above the respective reaction mixture in a gas phase. Moreover, the process described in US-A 2010/0065476 involves a continuous sampling and halide analysis of the feed stream for the reaction as a mandatory ingredient. In principle, this costly procedure can be dispensed with in the present invention.

US-A-2007/0249485 discloses a process for regenerating spent acidic ionic liquids used as a catalyst wherein the corresponding ionic liquid is contacted with at least one metal in a regeneration zone in the absence of hydrogen. For example, aluminum, gallium or zinc can be used as metal, the ionic liquid is preferably used for catalysis of Friedel-Crafts reactions. A similar method is disclosed in US-A 2007/0142217, wherein there the regeneration is carried out additionally in the presence of a Brönsted acid such as hydrogen chloride. WO 201/006848 discloses a process for converting an alkylation unit for HF or sulfonic acid and an alkylation unit for ionic liquids. In this process, among other things, the ionic liquid used as a catalyst is regenerated by adding hydrogen halide or a haloalkane. In WO 201 1/006848, however, there is no indication that when using a hydrogen halide over the corresponding reaction mixture in a gas phase, the hydrogen halide partial pressure is kept constant.

The object underlying the present invention is to provide a novel process for the chemical reaction of at least one hydrocarbon in the presence of an ionic liquid, in particular for the isomerization of at least one hydrocarbon in the presence of an ionic liquid.

The object is achieved by a chemical reaction of at least one hydrocarbon in a device (V1) in the presence of an ionic liquid and a hydrogen halide (HX), characterized in that in the device (V1), a liquid reaction mixture containing at least one Hydrocarbon, the hydrogen halide and the ionic liquid, and a gas phase containing the hydrogen halide, wherein the liquid reaction mixture and the gas phase are in direct contact with each other and wherein in the device (V1) gaseous hydrogen halide is introduced, so that during the chemical reaction the hydrogen halide partial pressure in the gas phase is kept constant.

By the method according to the invention can be carried out advantageously of a chemical reaction, in particular an isomerization of hydrocarbons. Due to the gaseous addition of a hydrogen halide (HX) at a constant hydrogen halide partial pressure in the gas phase, the catalytic activity of the corresponding ionic liquid is kept substantially constant. The effect can be further enhanced if, in addition to the hydrogen halide, preferably hydrogen chloride, a metal halide, in particular aluminum chloride, is added to the ionic liquid present in the device (V1) or is in constant contact with the metal halide.

In a particularly simple and thus advantageous manner, the inventive method can be carried out by the hydrogen halide partial pressure in the device (V1) is kept constant in that the pressure in the device (V1) is controlled such that gaseous hydrogen halide recurring or continuously in the device (V1) is initiated. Preferably, in this embodiment, the gaseous hydrogen halide is introduced from a reservoir into the device (V1), wherein a shut-off device, preferably a valve or a tap, is located between the device (V1) and the reservoir. With device technology relatively simple effort thus the pressure in the gas phase (over the reaction mixture) in the device (V1) can be measured continuously, when falling below a (predetermined) threshold value for the pressure, the obturator, while exceeding the threshold for the Pressure the obturator is closed again.

Furthermore, it is advantageous if (in addition to the addition of hydrogen halide in the device (V1)), the metal halide is not added directly into the device (V1) to the ionic liquid, but if the metal halide initially outside the device (V1) in a device or Apparatus (V2) is premixed with one of the main components located in the device (V1). This may initially be the ionic liquid itself, which originates from the reaction effluent of the device (V1) and is separated from the reaction effluent with a phase separation unit, preferably a phase separator, and returned to the device (V1). However, it is particularly advantageous to add the metal halide to the feed stream containing the hydrocarbons to be subjected to a chemical reaction, in particular an isomerization, in the apparatus (V1). In this variant, the expenditure on equipment of the metal halide addition is simpler, because the corresponding apparatus (V2), detached from its concrete mode of operation, does not have to be made of corrosion-resistant material, which, when added to the recirculated ionic liquid or added directly into the device (V1 ) is usually necessary because many ionic liquids are highly corrosive. Furthermore, when the metal halide is added to the hydrocarbonaceous stream, it is also not necessary for the corresponding apparatus to be designed for high reaction pressures.

The chemical conversion process according to the invention of at least one hydrocarbon in the presence of an ionic liquid at constant hydrogen halide partial pressure in the gas phase of the device (V1) is defined in more detail below.

In the context of the present invention, the term "chemical reaction process" or "chemical reaction" is understood in principle to mean any chemical reaction or chemical reaction known to the person skilled in the art in which at least one hydrocarbon is chemically reacted, modified or changed in any other way with respect to its composition or structure becomes.

Preferably, the chemical reaction method is selected from alkylation, polymerization, dimerization, oligomerization, acylation, metathesis, polymerization or copolymerization, isomerization, carbonylation, or combinations thereof. Alkylations, isomerizations, polymerizations, etc. are known in the art. Particularly preferred in the context of the present invention, the chemical reaction process is an isomerization.

In the context of the present invention, the chemical reaction, preferably the isomerization, is carried out in a device (V1) which is known to the person skilled in the art. Suitable devices (V1) are for example reactors, other reactors, stirred tank or a stirred tank cascade. The device (V1) is preferably a reactor or a stirred tank cascade.

In principle, any hydrocarbons may be present in the device (V1) in the process according to the invention. The person skilled in the art, on the basis of his general knowledge, knows for which specific chemical reaction processes which hydrocarbons and in which compositions are most suitable. Optionally, compounds (in the form of mixtures) may also be present which are not hydrocarbons themselves. In the following text, the composition of the hydrocarbons contained in the device (V1) is illustrated by the preferred as a chemical reaction in the context of the present invention isomerization.

Preferably, in the chemical reaction in the device (V1), in particular in the isomerization, as the hydrocarbon methylcyclopentane (MCP) or a mixture of methylcyclopentane (MCP) with at least one further hydrocarbon selected from cyclohexane, n-hexane, iso-hexanes n Heptane, iso-heptane, methylcyclohexane or dimethylcyclopentanes used. The corresponding hydrocarbons are thus fed into the device (V1).

More preferably, in the chemical reaction, in particular in the isomerization, a mixture of methylcyclopentane (MCP) with at least one further hydrocarbon selected from cyclohexane, n-hexane, iso-hexanes n-heptane, iso-heptanes, methylcyclohexane or dimethylcyclopentanes, wherein the concentration ratio MCP / cyclohexane is preferably at least 0.2. In the context of the present invention, methylcyclopentane (MCP) is particularly preferably isomerized to cyclohexane.

Preferably, in the process according to the invention after the chemical reaction, in particular after the isomerization, as the hydrocarbon, cyclohexane or a mixture of cyclohexane with at least one further hydrocarbon selected from methylcyclopentane (MCP), n-hexane, iso-hexane, n-heptane, iso Heptane, methylcyclohexane or dimethylcyclopentane.

Particularly preferably, after the chemical reaction, in particular after the isomerization, a mixture of cyclohexane, MCP and at least one further hydrocarbon is obtained. Preferably, the further hydrocarbon is selected from n-hexane, iso-hexane, n-heptane, iso-heptane, methylcyclohexane or dimethylcyclopentane. Furthermore, it is preferred in the process according to the invention that after the isomerization in the resulting mixture, which is preferably contained in the below described phase (B), a lower proportion of MCP and open-chain linear hydrocarbons is present compared to the corresponding composition of hydrocarbons or the phase (B) before the isomerization. Suitable ionic liquids in the context of the present invention are in principle all ionic liquids known to the person skilled in the art. An overview of suitable ionic liquids can be made in the case of isomerization For example, WO 201 1/069929 are taken. Preferred within the scope of the present invention is an acidic ionic liquid.

In the context of the present invention, preference is given to using (acidic) ionic liquids in which the anion comprises at least one metal component and at least one halogen component.

In the context of the present invention, the ionic liquid is preferably used as a catalyst in a chemical reaction, preferably in the alkylation or isomerization, in particular in an isomerization. In addition, they may have a dissolving power for another, used in the corresponding reaction catalyst.

In the method according to the invention, in the (preferably acidic) ionic liquid in the anion of the ionic liquid, the metal component is preferably selected from Al, B, Ga, In, Fe, Zn and Ti and / or the halogen component selected from F, Cl, Br or I, in particular from Cl or Br. More preferably, the (preferably acidic) ionic liquid has as anion a halogen illumination with the composition Al _n X _{(3n + 1)} with 1 <n <2.5 and X = halogen, preferably X = F, Cl , Br or I, in particular X = Cl, on.

In principle, all cations known to those skilled in the art are suitable as cations. Examples of these are an unsubstituted or at least partially alkylated ammonium ion or an optionally alkyl-side chain heterocyclic (monovalent) cation, in particular a pyridinium ion, an imidazolium ion, a pyridazinium ion, a pyrazolium ion, an imidazolinium ion, a thiazolium ion, a triazolium ion, a pyrrolidinium ion, an imidazolidinium ion or a phosphonium ion. Preferably, the at least partially alkylated ammonium ion contains one, two or three alkyl radicals having (each) 1 to 10 carbon atoms. If two or three alkyl substituents with the corresponding ammonium ions are present, the respective chain length can be selected independently of one another, preferably all alkyl substituents have the same chain length. Particularly preferred are trialkylated ammonium ions having a chain length of 1 to 3 carbon atoms. The heterocyclic cation is preferably an imidazolium ion or a pyridinium ion.

Preferably, the ionic liquid comprises as cation an ammonium ion, more preferably trialkylammonium, and / or as anion a chloroalumination of the composition Al _x Cl _{3x + 1} with 1 <x <2.5.

Particularly preferably, the ionic liquid, in particular the acidic ionic liquid, contains as cation at least partially alkylated ammonium ion and as anion a chloroalumination with the composition Al _n Cl _{(3n + 1)} with 1 <n <2.5. Examples of such particularly preferred ionic liquids are trimethylammonium chloroaluminate and triethylammonium chloroaluminate. In principle, all conceivable hydrogen halides can be used as hydrogen halide (HX), for example hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen bromide (HBr) or hydrogen iodide (HI). Optionally, the hydrogen halides can also be used as a mixture, but preferably only one hydrogen halide is used in the context of the present invention.

It is preferable to use the hydrogen halide (HX) whose halogen component (X) coincides (at least partially) with the halogen component in the anion of the above-described (acidic) ionic liquid. Preferably, the hydrogen halide (HX) is hydrogen chloride (HCl) or hydrogen bromide (HBr). Most preferably, the hydrogen halide (HX) is hydrogen chloride (HCl). Furthermore, it is preferred that the hydrogen halide (HX) is dry, in particular it is dry hydrogen chloride. In the device (V1) is a liquid reaction mixture containing (as components) at least one hydrocarbon containing hydrogen halide (HX) and the ionic liquid. The individual components of the liquid reaction mixture according to the above definitions, if appropriate, may also contain 2 or more hydrogen halides and / or ionic liquids. In other words, the liquid reaction mixture is the components which participate in the above-described chemical reaction, preferably in the isomerization, (active).

In the apparatus (V1), and in particular in the liquid reaction mixture, the ionic liquid is used as catalyst and the hydrogen halide as cocatalyst in a chemical reaction, preferably in an alkylation or isomerization, in particular in an isomerization.

Furthermore, in the device (V1) is a gas phase containing the hydrogen halide (HX). The hydrogen halide in the gas phase and the hydrogen halide in the liquid reaction mixture are the same in chemical definition.

In the device (V1), the liquid reaction mixture and the gas phase are in direct contact with each other. As a rule, the liquid reaction mixture forms one, two or more separate phases, that is, different from the gas phase. The liquid reaction mixture and the gas phase can For example, in the device (V1) is located for example in the lower part of the one or two separate phases existing liquid reaction mixture, wherein the gas phase is again in the upper part of the corresponding device (V1). At the interface between the liquid reaction mixture and the gas phase there is therefore a direct contact between the two "main phases" (ie liquid reaction mixture and gas phase.) It is also possible for the liquid reaction mixture and the gas phase to be mixed, for example by intensive stirring but the separation in the reaction mixture on the one hand and gas phase on the other hand is maintained.

In the context of the present invention, at least one hydrogen halide (HX), preferably hydrogen chloride (HCl), is introduced into the device (V1) in gaseous form. Due to the gaseous introduction of the hydrogen halide, the gas phase described above forms in the device (V1). The gaseous introduction of the hydrogen halide is carried out so that during the chemical reaction, in particular during the isomerization, the hydrogen halide partial pressure in the gas phase is kept constant. In the context of the present invention, the term "constant hydrogen halide partial pressure" (in the gas phase) is understood as meaning that the hydrogen halide partial pressure is constant (in the gas phase) if it does not exceed 20% during the operating time of the device (V1). , preferably at most 10%, more preferably at most 5%, in particular at most 1%, deviates from the mean value determined over the operating time of the device (V1). In the present invention, the hydrogen halide partial pressure (PHX) is defined as follows:

PHX = XHX Ptotai (equation 1) with

χ _Η χ = molar fraction of the hydrogen halide in the gas phase, and

Ptotai = total pressure of the gas phase over the reaction mixture.

The hydrogen halide partial pressure ρ _Η χ is calculated for the case that in the gas phase over the reaction mixture no or only negligible amounts of substances except hydrogen halide and hydrocarbon are present as follows: PHX = Ptotai - PKW (equation 2) with

Ptotai = total pressure of the gas phase over the reaction mixture,

PKW = vapor pressure of the hydrocarbons of the reaction mixture at reaction temperature

The hydrogen halide partial pressure ρ _Η χ can preferably be determined by taking from the gas phase of the device (V1) a sample of defined amount and the HX mole fraction according to a method known to the skilled person (eg introducing the gas into a defined NaOH solution and then Back titration) is determined and the determined mole fraction according to equation 1 with the total pressure of the gas phase in (V1) is multiplied.

If appropriate, the hydrogen halide partial pressure ρ _Η χ can also be estimated according to Equation 2, provided that passenger car is known. p _K w and p _to t _a i can be determined by the methods known in the art, in particular measurement of the pressure p _to t _a i by means of a conventional pressure measuring device and determination of PKW by means of a temperature-vapor pressure correlation (vapor pressure curve), for a given hydrocarbon, or a hydrocarbon mixture is usually known or can be determined by the skilled person known measuring methods. The hydrogen halide partial pressure in the gas phase can in principle assume any desired values in the context of the process according to the invention. Preferably, the hydrogen halide partial pressure in the gas phase is between 1, 1 and 5 bara, preferably between 2 and 4 bara. In a preferred embodiment of the present invention, the hydrogen halide partial pressure in the gas phase is kept constant by controlling the pressure in the device (V1) by returning or continuously introducing gaseous hydrogen halide into the device (V1). In the context of the present invention, a "continuous introduction of gaseous hydrogen halide" is understood to mean that the corresponding addition is maintained over a relatively long period of time, preferably over at least 50%, more preferably over at least 70%, even more preferably over at least 90%, in particular over Preferably, the continuous introduction is carried out so that the corresponding device for gaseous introduction (addition) of the hydrogen halide over the aforementioned periods in operation. In the context of the present invention, a "recurring introduction of gaseous hydrogen halide" of the hydrogen halide is understood to mean that the appropriate gaseous introduction (addition) takes place at regular or irregular intervals .The time intervals between the individual additions are at least 1 h, preferably at least one day In the context of the present invention, the term "recurring" furthermore means at least two, for example 3, 4, 5, 10 or also 100 individual additions. The concrete number of individual additions depends on the duration of operation. This ideally goes against infinity.

In other words, a recurring introduction of gaseous hydrogen halide in the context of the present invention is understood to mean the addition of a plurality of partial amounts of metal halide with a time delay. The addition of a single subset can take from several seconds to several minutes, possibly even slightly longer periods are conceivable. According to the invention, the time interval between the respective addition of a single subset is at least ten times as long as the duration of the addition of the corresponding subset. Optionally, in the context of the present invention, the embodiment of a "recurring addition" with the embodiment of a "continuous addition" may also be combined with one another.

Furthermore, it is preferred that the gas phase in the device (V1) is connected via a shut-off device to a reservoir, the reservoir containing at least 90 mol%, particularly preferably more than 98 mol%, of the hydrogen halide and a pressure which is greater than the hydrogen halide partial pressure of the gas phase in the device (V1).

Preferably, in this embodiment, the gaseous hydrogen halide is introduced from a reservoir into the device (V1), wherein a shut-off device, preferably a valve or a tap, is located between the device (V1) and the reservoir. With device technology relatively simple effort thus the pressure in the gas phase (over the reaction mixture) in the device (V1) recurrently, but preferably continuously measured, when falling below a (predetermined) threshold value for the pressure, the obturator open, while when exceeded the threshold value for the pressure the shut-off valve is closed again.

Furthermore, in one embodiment of the present invention, it is preferable that the pressure in the device (V1) be kept constant by using a two-point control system acting on a shut-off device to a hydrogen halide reservoir. In a preferred embodiment of the present invention, in the device (V1) -in addition to the gaseous phase-two further phases (A and B) are contained, which together form the liquid reaction mixture. Optionally, further phases may also be present in the liquid reaction mixture. In this case, the phase (A) contains at least one ionic liquid according to the above description, wherein the proportion of ionic liquid in the phase (A) is greater than 50 wt .-%. The phase (A) is preferably a phase containing ionic liquids which is immiscible or only very difficult to mix with hydrocarbons and / or which contains at most 10% by weight of hydrocarbons. In general, the hydrogen halide (HX) is contained in both phase (A) and phase (B).

For example, in phase (A) mixtures of two or more ionic liquids may be contained, preferably the phase (A) contains an ionic liquid. In addition to the ionic liquid, other components which are miscible with the ionic liquid can also be present in the phase (A). These may be hydrocarbons from phase (B) described below, which typically have limited solubility in ionic liquids. Furthermore, phase (A) may also contain cocatalysts used in isomerization reactions using ionic liquids. A preferred example of such cocatalysts are the hydrogen halides already mentioned above, in particular hydrogen chloride. In addition, in phase (A) may also contain constituents or decomposition products of the ionic liquids, which may arise, for example, during the isomerization process. Preferably, in phase (A), the proportion of ionic liquid is greater than 80 wt .-%.

The phase (B) is characterized in the context of the present invention in that it contains at least one hydrocarbon, wherein the content of hydrocarbon in the phase (B) is greater than 50 wt .-%. Phase (B) is preferably a hydrocarbon-containing phase which is immiscible or only very difficult to mix with ionic liquids and / or which contains at most 1% by weight of ionic liquids (based on the total weight of the phase).

The concrete composition of phase (B) depends on the chosen chemical reaction method. Phase (B) undergoes a change in composition during a chemical reaction process. The specific hydrocarbons which may be present in phase (B) before and after the chemical reaction, in particular the isomerization, have already been described above. Furthermore, it is preferred that in the device (V1) the ionic liquid to greater than 50 wt .-% in a phase (A) is contained, which has a higher viscosity than a phase (B), in which greater than 50 wt. -% at least one hydrocarbon is contained, and the phases (A) and (B) are in direct contact with each other, for example by forming together a heterogeneous mixture.

In one embodiment of the present invention, the chemical reaction, in particular the isomerization, takes place in a dispersion (D1) in which the phase (B) is dispersed in the phase (A). The direction of dispersion (that is, the information as to which phase is in disperse form in the other phase) can be determined by examining a sample under transmitted light under a light microscope, optionally after adding a dye which selectively dyes the phase. The phases (A) and (B) have the above definitions. The dispersion (D1) can be prepared by methods known to those skilled in the art, for example, such a dispersion can be produced by intensive stirring of the phases. In a further embodiment of the present invention, in the dispersion (D1), the volume ratio of the phase (A) to phase (B) is in the range of 2.5 to 4 to 1 [vol / vol], preferably in the range of 2.5 to 3 to 1 [vol / vol].

Furthermore, in a preferred embodiment of the method according to the invention, at least one metal halide is added to the device (V1) during the chemical reaction, preferably during the isomerization. The addition of the metal halide is thus in addition to the introduction (addition) of the gaseous hydrogen halide (HX). The addition of the metal halide in the device (V1) can be carried out in a recurring or continuous manner.

Preferably, the anion of the ionic liquid and the metal halide are identical with respect to the respective halogen component and the metal component. In principle, all metal halides known to those skilled in the art which fulfill this criterion are suitable. Preferably the metal halide is selected from AlX _3, BX _3, GaX _3, lnX _3, FeX _3, ZnX ₂ and T1X4 with X = halogen, preferably X = Cl or Br, more preferably X = Cl. In particular, the metal halide is AICI ₃ . Further, it is preferable that the halogen components of ionic liquid, the hydrogen halide (HX) and the metal halide match.

If the ionic liquid used in the device (V1) contains, for example, Al ₂ Cl ₇ as an anion, it is possible to use AICI ₃ as the metal halide. In the case of mixed-component anions such as, for example, Al ₂ BrCl ₆ ^{", it is} possible to use, for example, a corresponding mixture of AlCl ₃ and AlBr _3. The same applies analogously to the case in which the metal component of the anion is corresponding ionic liquid contains two or more components such as Al or Cu with regard to the selection of the corresponding metal component of the metal halide used. The addition of at least one metal halide into the device (V1) can be repeated or continuous. In this case, the metal halide can be added in liquid or solid form. It should also be noted that the metal halide need not be added directly into the device (V1), but the metal halide can first be added in another device, for example in a contact device (V2), one or more of the components involved in the chemical reaction process , From this other device, the metal halide together with the or said component (s) in the device (V1) out (indirect addition of the metal halide according to (V1)). The (over) guiding or (over) guiding the metal halide together with the mentioned component (s) from the other device into the device (V1) takes place according to the methods known to the person skilled in the art, for example using pumps.

Preferred for the addition of the metal halide are the two embodiments which are defined in more detail in the following text in conjunction with Figures 1 and 2. Both embodiments are such an indirect addition, wherein the metal halide is first added to the system via the contact device (V2), from where it enters the device (V1). In the context of the present invention, a "continuous addition" of the metal halide is understood to mean that the corresponding addition over a relatively long period, preferably over at least 50%, more preferably over at least 70%, even more preferably over at least 90%, in particular over the entire Preferably, the continuous addition is carried out so that the corresponding device for introducing (adding) the metal halide (eg a rotary valve) is in operation for the aforementioned periods.

In the context of the present invention, a "recurring addition" of the metal halide is understood as meaning that the corresponding addition takes place at regular or irregular intervals Phase (B) The time intervals between the individual additions are at least 1 h, preferably at least one day Within the scope of the present invention, the term "recurring" furthermore includes at least two, for example 3, 4, 5, 10 or even 100 individual Additions understood. The concrete one Number of individual additions depends on the operating time. This ideally goes against infinity.

In other words, a recurring addition of the metal halide in the context of the present invention is understood to mean the time-limited addition of a plurality of charges of metal halide. The addition of a single batch can take from several seconds to several minutes, possibly even slightly longer periods are conceivable. According to the invention, the time interval between the respective addition of a single batch is at least ten times as long as the duration of the addition of a single batch. Optionally, in the context of the present invention, the embodiment of a "recurring addition" with the embodiment of a "continuous addition" may also be combined with one another. In the context of the present invention, the addition of the metal halide is particularly preferably carried out in such a way that in the device (V1) a concentration of

> 70%, preferably> 90% of the saturation concentration of the metal halide. It is also possible that there is a supersaturation of metal halide in the device (V1). If this is the case, an (additional) solid phase of metal halide is formed in the device (V1). Preferably, in the phase (B) (described below), a concentration of> 70%, preferably> 90%, of the saturation concentration of the metal halide is set. The term "saturation concentration" is to be understood in accordance with IUPAC: Compendium of Chemical Terminology, 2nd Edition (the "Gold Book"), compiled by A.D. McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford (1997).

Preferably, in the case of a recurring addition of the metal halide, the respectively next addition is carried out in such a way that a concentration of

> 70%, preferably> 90% of the saturation concentration of the metal halide, preferably in the phase (B), readjusted. The next addition to each

Metal halide thus takes place when the metal halide concentration has fallen below the above limits. In particular, the periodic addition of the metal halide is such that the aforementioned saturation-related metal halide concentrations in phase (B) are constantly maintained. The next addition of metal halide thus takes place before the metal halide concentration has fallen below the above limits.

Preferably, the continuous addition of the metal halide is such that in the device (V1) a concentration of> 70%, preferably> 90% of the saturation concentration of the metal halide is maintained continuously. In particular, this is maintained in phase (B). Furthermore, it is preferred that the metal halide and the gaseous hydrogen halide (HX), preferably AICI ₃ and hydrogen chloride, are added simultaneously to the device (V1). In a further preferred embodiment of the present invention, the device (V1) contains the following phases: i) the phase (A) containing the ionic liquid,

ii) the phase (B) containing at least one hydrocarbon,

iii) optionally the phase (C) containing solid metal halide, preferably solid AIX ₃ , and

iv) the phase (D) containing gaseous HX.

The process according to the invention, in particular the isomerization, is preferably carried out continuously. The compounds (products) formed during the chemical reaction, in particular during the isomerization, can be removed from the device (V1) by methods known to the person skilled in the art. For example, from the device (V1), in which the chemical reaction is carried out, a stream are discharged, in which the phase (B) and the phase (A) are contained, wherein in the phase (B) at least one hydrocarbon is contained which was produced during the chemical reaction. This current in turn is preferably introduced into a phase separation device (phase separation unit). Phase separation devices as such are known to the person skilled in the art. This phase separation device is preferably a phase separator.

Preferably, the device (V1) is a reactor or a stirred tank cascade, and downstream of the device (V1) is a phase separator, preferably a phase separator. Furthermore, it is preferred that the reactor or the stirred tank cascade and optionally the phase separation device are coupled on the gas side.

Further, it is preferable that in the phase separation device, the phase (A) containing the ionic liquid is separated from the phase (B) containing at least one hydrocarbon, preferably the phase (A) is returned to the device (V1) , is returned in particular to the reactor or to the starting point of the stirred tank cascade. A first stream comprising at least 70% by weight, preferably at least 90%, of the phase (A) and a second stream containing at least 70%, preferably at least 90%, of the phase (B) are preferably present in the phase separation apparatus. separated from each other. The above figures in% refer to the corresponding amounts contained in the stream, which is introduced into the phase separator. Furthermore, it is preferred in the context of the present invention for the device (V1) to be preceded by a contact device (V2), which is preferably a fluidized bed, a fluidized bed or a stirred vessel, the metal halide initially being added to the contact device (V2) and being supplied by there in the device (V1) is performed. The metal halide may be added in solid or liquid, more preferably in solid form.

The contact device (V2) can in turn be followed by a device (V3) for liquid or liquid / liquid separation, which is preferably a phase separator, a gravity separator, a hydrocyclone, a dead end filter or a crossflow filter. Optionally, the device (V3) for FesW-liquid or liquid / liquid separation apparatus in the contact device (V2) integrated, for example such that (V2) is a stirred tank having a stirring zone and a rest zone arranged above this, in which a through Gravity caused separation of solid and liquid takes place. Preferably, a solids-enriched stream separated in the device (V3) for FesW liquid or liquid / liquid separation is returned to the contact device (V2).

Regardless of the presence of a downstream device (V3) for FesWlüssig- or liquid / liquid separation, it is preferred in connection with the contact device (V2) that the metal halide in the contact device (V2) recurring or continuously by means of a device for metering or delivery of solid or liquid is added; in the case of the solid preferably with a rotary valve or a pneumatic conveying, in the case of liquid preferably by means of a pump.

Likewise, it is preferred that the liquid flows through the contact device (V2), which contains the substances to be converted in the device (V1) and / or which is supplied to the device (V1). In a preferred embodiment, the presence of a second, in particular solid, phase in the contact device (V2) is constantly monitored optically or by means of another suitable device or method, preferably by means of a turbidity measurement, and when the second phase disappears by means of a device for Dosing or promotion of solid metal halide registered in the contact device (V2). In a preferred embodiment of the present invention, the contact device (V2) flows through the recirculated phase (A), which originates from the above-described phase separation device, in particular the phase separator, and (V2) is located between the phase separation device and the device (V1) (V2), if appropriate downstream of a device (V3) for solid / liquid separation or liquid / liquid separation.

From the discharge of the device (V1), in particular from the hydrocarbon-containing discharge of a device downstream of the device (V1) phase separation unit, preferably a phase separator, is preferably isolated in the present invention, cyclohexane. Methods and apparatus for the separation of cyclohexane from such a discharge or stream, in particular when it is a hydrocarbon mixture, are known in the art. If appropriate, further purification steps (for example washing with an aqueous and / or alkaline phase), which are likewise known to the person skilled in the art, can be carried out before the separation of the cyclohexane.

In FIG. 1, the process according to the invention is again clarified in accordance with a preferred embodiment, which is preferably carried out as isomerization. "MX" means metal halide, "f" means solid and "I" means liquid or dissolved "I L" means ionic liquid "AO" means shut-off valve connected to the reservoir (R). "PC" means a pressure measuring device which is connected to a control device in such a way that it acts on at least one pressure-influencing device ("actuator"). "A" means phase (A), with the corresponding major component of that phase in parentheses (in the present case, ionic liquid presented in device (V1)) "B" means phase (B), where "KW1" represents a first hydrocarbon mixture and "KW2" for a second hydrocarbon mixture which is formed in the device (V1) in the context of a chemical reaction, preferably an isomerization, from KW1.

The reacted at least one hydrocarbon-containing phase B (KW1) is continuously fed into the device (V1), optionally in addition a metal halide (MX) in (V1) is introduced. (V1) contains, under operating conditions, liquid reaction mixture and a gas phase in contact with it. This is connected via the obturator (AO) with the reservoir (R), which contains a gas which consists of more than 90 mol%, more preferably more than 98 mol%, of the hydrogen halide and a pressure above the pressure of Has gas phase over the reaction mixture. In (V1) is located in the gas phase, a pressure measuring device which is connected to a control device. The entirety of pressure measuring device and control device is referred to in Fig. 1 as (PC). (PC) controls the position of the obturator (AO) in such a way that when falling below a threshold value for the pressure, the obturator is opened, on exceeding a threshold value for the pressure, the obturator is closed. The detailed design of this scheme can be done by various known to the expert 5 types.

Hereinafter, the present invention will become apparent from the examples. General experimental conditions:

10

The following substances or compositions are used for the experiments:

Ionic liquid (A) having the composition (CH ₃ ) ₃ NHAl ₂ Cl ₇ , a 15 hydrocarbon mixture (B) with the components methylcyclopentane, cyclohexane, n-hexane and isohexane and additionally, for the example according to the invention, gaseous HCl. The ionic liquid is hereinafter also referred to as "IL" and the hydrocarbon mixtures B and B1 as "organic" or "organic phase".

20

The experimental arrangement is shown in FIG.

The ionic liquid (CH ₃ ) ₃ NHAl ₂ Cl _{7 is} initially charged at 60 ° C. in a 250 ml double-walled stirred reactor (V1). The hydrocarbon mixture (MCP, CH, n-

25 hexane, isohexane) is metered in (30 g / h) and withdrawn from a phase separator (PT), which is mounted directly on the reactor. In the reactor (V1), the reaction of the hydrocarbon mixture, an isomerization of methylcyclopentane to cyclohexane instead. The isomerized hydrocarbon mixture is referred to as B1. The level of the reactor is

30 regulated by adjusting the variable overflow between V1 and PT. In this case, a dispersion of B1 in A is passed into the phase separator, in which separate the two phases. The ionic liquid as the heavier phase (A) falls as the lower phase and is conveyed by a pump back into the reactor (V1). The upper organic phase (B1) is withdrawn and by

35 gas chromatography analyzed for their composition.

Example 1 :

Composition Organic Phase (B) Start:

40-27% by weight of n-hexane

52% by weight MCP

20% by weight CH 1% by weight of i-hexanes

Reaction temperature: 60 ° C

Capacity: 185 ml (257 g) I L

Organic feed: 30 g / h

5 HCI feed: 20 Nml / h (0-1 18 h)

40 Nml / h (from 1 to 18 h)

Phase ratio IL / organic ~ 5 (V / V)

Stirrer: blade stirrer, speed = 900 rpm

10 implementation

In this experiment, 20 Nml / h HCl gas are additionally metered with a gas burette in the gas space of the reactor. Based on the organic feed of 30 g / h corresponds to 0, 1 wt .-%. After a test time of 1 18 h, the HCI dosage 15 is increased to 40 Nml / h HCl (corresponds to 0.2 wt .-%). Balance tests have shown that the HCI gas, which is metered into the gas space of the reactor, dissolves very quickly in the organics. It can therefore be assumed that at least 95% of the HCI gas is dissolved in the liquid phase.

20 results

By contacting with gaseous HCl, a constant MCP conversion can be achieved over a long period of time, and the rapid decrease in activity as in the

25 Comparative example can thus be prevented.

Comparative Example 2:

Composition Organic Phase (B) Start:

30-27% by weight of n-hexane

52% by weight MCP

20% by weight CH

1% by weight of i-hexanes

Reaction temperature: 60 ° C Capacity: 185 ml (257 g) IL

Organic feed: 30 g / h

Phase ratio IL / organic ~ 5 (V / V)

Stirrer: blade stirrer, speed = 900 rpm

Results

After initial high activity, MCP sales drop below 180% within 180 hours.

Claims

Patent claims

1 . Chemical reaction process of at least one hydrocarbon in a device (V1) in the presence of an ionic liquid and a

Hydrogen halide (HX), characterized in that in the device (V1) there is a liquid reaction mixture containing at least one hydrocarbon, the hydrogen halide and the ionic liquid, and a gas phase containing the hydrogen halide, the liquid reaction mixture and the gas phase being in are in direct contact with one another and gaseous hydrogen halide is introduced into the device (V1), so that the hydrogen halide partial pressure in the gas phase is kept constant during the chemical reaction.

2. The method according to claim 1, characterized in that the hydrogen halide (HX) is hydrogen chloride, preferably dry hydrogen chloride.

3. The method according to claim 1 or 2, characterized in that the hydrogen halide partial pressure in the gas phase is between 1, 1 and 5 bara, preferably between 2 and 4 bara.

4. The method according to any one of claims 1 to 3, characterized in that the ionic liquid comprises as anion at least one metal component and at least one halogen component and / or that in the

Device (V1) at least one metal halide is added during the chemical reaction.

5. The method according to claim 4, characterized in that the metal halide is added repeatedly or continuously into the device (V1) and / or the anion of the ionic liquid and the metal halide match with regard to the respective halogen component and the metal component. 6. Method according to claim 4 or 5, characterized in that

i) in the anion of the ionic liquid the metal component is selected from Al, B, Ga, In, Fe, Zn and Ti and/or the halogen component is selected from F, Cl, Br or I, and/or

ii) the metal halide is selected from AIX ₃ , BX ₃ , GaX ₃ , lnX ₃ , FeX ₃ , ZnX ₂ and TiX ₄ with X = halogen, preferably X = Cl or Br. Method according to one of claims 4 to 6, characterized in that the ionic liquid has as _anion a halogenoalumination with the composition Al _n as a cation an ammonium ion, more preferably trialkylammonium, and/or as an anion a chloroalumination of the composition Al _n CI _(3n+ i ₎ with 1 <n <2.5.

Method according to one of claims 1 to 7, characterized in that in the device (V1) in the liquid reaction mixture, the ionic liquid is contained to greater than 50% by weight in a phase (A) which has a higher viscosity than a phase (B), in which at least one hydrocarbon is contained to a proportion of greater than 50% by weight, and the phases (A) and (B) are in direct contact with one another.

Method according to one of claims 1 to 8, characterized in that in the device (V1) the ionic liquid is used as a catalyst and the hydrogen halide as a co-catalyst in a chemical reaction, preferably in an alkylation or isomerization, in particular in an isomerization.

Method according to one of claims 1 to 9, characterized in that the device (V1) is a reactor or a stirred tank cascade, and/or a phase separation device, preferably a phase separator, is located downstream of the device (V1).

Method according to claim 10, characterized in that in the phase separation device the phase (A) containing the ionic liquid is separated from the phase (B) containing at least one hydrocarbon, the phase (A) preferably being fed into the device (V1 ) is returned, in particular into the reactor or to the starting point of the stirred tank cascade.

Method according to claim 10 or 1 1, characterized in that the reactor or the stirred tank cascade and optionally the phase separation device are coupled on the gas side.

Method according to one of claims 4 to 12, characterized in that the metal halide and the gaseous hydrogen halide (HX), preferably AICI ₃ and hydrogen chloride, are added simultaneously to the device (V1).

14. The method according to any one of claims 1 to 13, characterized in that the pressure in the device (V1) is kept constant by using a two-point control system which acts on a shut-off element to a hydrogen halide reservoir.

5

15. The method according to any one of claims 1 to 14, characterized in that the following phases are contained in the device (V1): the phase (A) containing the ionic liquid,

the phase (B) containing at least one hydrocarbon, optionally the phase (C) containing solid metal halide, preferably ALX ₃ , and

the phase (D) containing gaseous HX.

15 16. Method according to one of claims 1 to 15, characterized in that the hydrogen halide partial pressure in the gas phase is kept constant by increasing the pressure in the device (V1) by recurring or continuous introduction of gaseous hydrogen halide into the device (V1). is regulated.

0

17. The method according to one of claims 1 to 16, characterized in that the gas phase in the device (V1) is connected to a reservoir via a shut-off element, the reservoir containing at least 90 mol% of the hydrogen halide and having a pressure, which is greater than 5 the hydrogen halide partial pressure of the gas phase in the device (V1).