EP2260533A1

EP2260533A1 - Ionic liquid-containing catalyst ink and the use thereof in the production of electrodes, ccms, gdes and meas

Info

Publication number: EP2260533A1
Application number: EP09717503A
Authority: EP
Inventors: Oemer Uensal; Sigmar Braeuninger; Xiao Steimle; Alexander Panchenko
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2008-02-29
Filing date: 2009-02-26
Publication date: 2010-12-15
Also published as: CN102017264A; JP2011515795A; WO2009109512A1; CA2716777A1; KR20100129750A; US20110003071A1

Abstract

The invention relates to a catalyst ink which contains at least one catalytically active material and at least one ionic liquid, to a method for producing said catalyst ink, to a method for producing a membrane electrode assembly (MEA) containing at least one membrane and at least one electrode, by applying said catalyst ink to a membrane or by applying said catalyst ink to the optional gas diffusion layer, to the use of said catalyst ink in the production of a membrane electrode assembly (MEA), of a catalyst-coated membrane (CCM) or a gas diffusion electrode (GDE) and to the use of an ionic liquid for producing a catalyst ink.

Description

Ionic liquid-containing catalyst ink and its use in electrode, CCM, GDE and MEA production

description

The present invention relates to a catalyst ink containing at least one catalytically active material and at least one ionic liquid, a process for producing such a catalyst ink, a process for producing an MEA by applying such a catalyst ink to a membrane or to a GDL, the use a catalyst ink in the manufacture of an MEA; and the use of an ionic liquid to prepare a catalyst ink.

In fuel cells, a fuel with an oxidant at separate locations on two electrodes is converted into electricity, heat and water. Suitable fuels are hydrogen or a hydrogen-rich gas and liquid fuels such as methanol, ethanol, formic acid, ethylene glycol, etc., are used as the oxidant oxygen or air. The process of energy conversion in the fuel cell is characterized by high efficiency. Therefore, fuel cells are gaining in importance, especially in combination with electric motors as an alternative to conventional internal combustion engines. Due to their compact design and power density, polymer electrolyte fuel cells (PEM fuel cells) are particularly suitable for use in motor vehicles.

In general, a PEM fuel cell is constructed from a stacked array of membrane electrode assemblies (MEA), with bipolar gas supply and current conduction plates typically placed between each two MEAs. An MEA is generally composed of a polymer electrolyte membrane, which is provided on both sides with a respective catalyst layer (Catalyst Coated Membrane, CCM), on each of which in turn a gas diffusion layer (GDL) is applied. Further, an MEA can also be obtained by applying each of a gas diffusion electrode (GDE) each comprising a cathode or an anode catalyst layer on a gas diffusion layer on both sides of a membrane. One of the above-mentioned catalyst layers therefore serves as an anode for the oxidation of hydrogen and the second catalyst layer serves as a cathode for the reduction of oxygen. The gas distribution layers are generally composed of carbon fiber paper, carbon woven or carbon nonwoven fabric and have a high porosity, which allow good access of the reaction gases to the catalyst layers and a good dissipation of the reaction products and the cell stream. In order to achieve the best possible bond between the polymer electrolyte membrane and the catalyst layers applied on both sides with the best possible contact between the anode and the cathode to the polymer electrolyte membrane, the catalyst layers are generally applied to the membrane in the form of a so-called catalyst ink , It is also possible that such a catalyst ink is applied to a GDL for producing a GDE, and this GDE is hot-pressed with a corresponding membrane. A catalyst ink generally contains an electrocatalyst, an electron conductor, optionally a polymer electrolyte, and a solvent.

Corresponding catalyst inks and processes for their preparation are already known from the prior art.

No. 5,330,860 discloses a process for producing a membrane-electrode assembly by applying an ink, the catalytically active particles, a hydrocarbon having at least one ether, epoxy or ketone group and an alcohol group and optionally a binder, preferably perfluorinated sulfonyl fluoride polymers or perfluorinated sulfonic acid polymers. A preferred hydrocarbon solvent in the catalyst ink according to US Pat. No. 5,330,860 is 1-methoxy-2-propanol.

M. Uchida et al., J. Electrochem. Soc, Vol. 142, no. 2, 1995, pages 463 to 468 disclose a method of making polymer electrolyte fuel cells. In this method, a catalyst ink containing Nafion ^®, a catalyst of elemental platinum on a carbon support and a mixture of iso-propanol, ethanol and specific organic solvents selected from esters, ethers, acetone, ketones, amines, carboxylic acids, alcohol and non-polar solvents, used.

EP 1 176 655 A1 discloses a process for producing a membrane-electrode assembly by applying a liquid composition comprising a fluorocopolymer, at least one electrocatalyst and a mixture of a solvent having a low boiling point, for example 1, 1, 2-trifluoro- 1, 2-dichloroethane, a solvent having an average boiling point, for example, ethanol or hexane, and a solvent having a high boiling point, for example, isobutanol, n-butanol or toluene.

EP 0 731 520 A1 discloses a catalyst ink for the production of membrane-electrode assemblies by printing comprising at least one catalytically active material, at least one proton-conducting polymer and essentially water as Solvent. The catalyst ink according to EP 0 731 520 A1 contains at most 10% by weight of organic solvents.

WO 2004/054021 A2 discloses a catalyst ink comprising water, at least one solid catalyst, at least one polymer electrolyte in protonated form and at least one polar, aprotic organic solvent, for example dimethylsulfoxide, N, N-dimethylacetamide, N, N-dimethylformamide, N- Methylpyrrolidone, and others.

In general, catalyst inks known in the art include at least one ionomer, at least one catalytically active material, soluble or at least dispersible therein, and at least one solvent selected from organic solvents, water, and mixtures thereof. A disadvantage of these catalyst inks is that the ionomers present in the catalyst inks can be distributed inhomogeneously in the electrode produced from the catalyst ink and thus the power of the fuel cell is reduced. Furthermore, electrodes made from the known catalyst inks often have insufficient porosity, for example, no advantageous combination of microporous and macroporous pores is obtained.

The object of the present invention is to provide improved catalyst inks which make electrode layers accessible, which are distinguished by a particularly advantageous porosity. The electrodes prepared from the catalyst ink of the present invention are said to have both microporous and macroporous properties because the smaller pores increase the surface area thereby increasing catalyst activity and utilization, while the larger pores facilitate mass transport of both the substrates and the products of the electrochemical reaction , guarantee. Furthermore, it is an object of the present invention to provide catalyst inks which simplify or improve the production and above all the reproducibility of the production of membrane-electrode assemblies.

These objects are achieved according to the invention by a catalyst ink containing at least one catalytically active material and at least one ionic liquid.

At least one catalytically active material is present in the catalyst ink according to the invention. It is possible according to the invention that a catalytically active material is present, but it is also possible for a mixture of different catalytically active materials to be present. Suitable catalytically active materials are preferably catalytically active metals. These are known to the person skilled in the art. Suitable catalytically active metals are generally selected from the group consisting of platinum, palladium, iridium, rhodium, ruthenium and mixtures thereof, more preferably platinum and / or ruthenium. In a most preferred embodiment, platinum alone or a mixture of platinum and ruthenium is used. It is also possible to use the polyoxymetalates known to the person skilled in the art.

The preferably used catalytically active metals or mixtures of different metals may optionally contain other alloying additives selected from the group consisting of cobalt, chromium, tungsten, molybdenum, vanadium, iron, copper, nickel, silver, gold, iridium, tin, etc., and mixtures thereof.

In a further preferred embodiment, the at least one catalytically active material is applied to a suitable carrier material. Suitable support materials are known to the person skilled in the art, for example electron conductors selected from the group consisting of carbon black, graphite, carbon fibers, carbon nanoparticles, carbon foams, carbon nanotubes and mixtures thereof.

Which of the above-mentioned catalytically active metals is used depends on the intended field of application of the finished fuel cell. If a fuel cell is produced which is to be operated with hydrogen as fuel, it is sufficient if only platinum is used as the catalytically active material. A catalyst layer composed of this catalyst ink according to the invention can be used in a fuel cell both for the anode and for the cathode.

In a fuel cell which is to be operated as a fuel with a reformate gas containing carbon monoxide, it is advantageous if the anode catalyst has the highest possible resistance to poisoning by carbon monoxide. In such a case, preference is given to using platinum / ruthenium-based electrocatalysts. Also in the production of a direct methanol fuel cell electrocatalysts based on platinum / ruthenium are preferably used. For the production of the anode layer in such a fuel cell, it is therefore preferred that the catalyst ink of the invention comprises both metals. In order to produce the cathode layer of such a fuel cell, it is generally sufficient if platinum is used alone as the catalytically active metal.

According to the invention, it is possible for the same catalyst ink according to the invention to be used for double-sided coating of an ion-conducting polyelectrolyte membrane for producing a CCM, but it is likewise possible for various catalyst inks comprising different catalytically active metals to coat the catalyst be used on both sides of a polymer electrolyte membrane. The catalyst ink according to the invention can also be used to produce a GDE by coating a GDL.

The at least one catalytically active material is generally present in the catalyst ink according to the invention in an amount of from 0.1 to 3 parts by weight, preferably from 0.2 to 2 parts by weight, more preferably from 0.8 to 2 parts by weight, based in each case on the total catalyst ink.

Furthermore, the catalyst ink according to the invention contains at least one ionic liquid.

Ionic liquids in the sense of the present invention are preferred

(A) Salts of the general formula (I)

in which n represents 1, 2, 3 or 4, [A] ^{+ represents} a quaternary ammonium cation, an oxonium cation, a sulfonium cation or a phosphonium cation, and [Y] "^{" represents} a one-, two-membered -, trivalent or tetravalent anion is, or

(B) mixed salts of the general formulas (II)

[A ¹ ] ⁺ [A ² ] ⁺ [Yf (IIa) where n = 2,

[A ¹ ] ⁺ [A ² ] ⁺ [A ³ ] ⁺ [Y] "- (IIb), where n = 3 or [A ¹ ] ⁺ [A ² ] ⁺ [A ³ ] ⁺ [A ⁴ ] ⁺ [ Yf (Mc), where n = 4 and

where [A ¹ ] ⁺ , [A ² ] \ [A ³ J ⁺ and [A ⁴ ] ^{+ are selected,} independently of one another, from the groups named for [A] ⁺ and [Y] "^" that mentioned under (A) Has meaning.

Preferably, the at least one ionic liquid has a melting point of less than 180 ⁰ C. Further, preferably, the melting point of the at least one ionic liquid at -50 ⁰ C to 150 ⁰ C, more preferably at -20 ⁰ C to 120 ⁰ C, and further more preferably at -20 to 100 ^° C. In a particularly preferred embodiment, the at least one ionic liquid is liquid at room temperature, ie 25 ^° C. The ionic liquids according to the invention are organic compounds, ie at least one cation or an anion of the ionic liquid contains an organic radical.

Compounds suitable for forming the cation [A] ⁺ of ionic liquids are e.g. B. from DE 102 02 838 A1. Thus, such compounds may contain oxygen, phosphorus, or in particular nitrogen atoms, for example at least one nitrogen atom, preferably 1-10 nitrogen atoms, particularly preferably 1-5, very particularly preferably 1-3 and in particular 1-2 nitrogen atoms. Optionally, other heteroatoms such as oxygen or phosphorus atoms may be included. The nitrogen atom is a suitable carrier of the positive charge in the cation of the ionic liquid from which, in equilibrium, a proton or an alkyl radical can then be transferred to the anion to produce an electrically neutral molecule.

In the event that the nitrogen atom is the carrier of the positive charge in the cation of the ionic liquid, in the synthesis of the ionic liquids, a cation can first be generated by quaternization on the nitrogen atom of, for example, an amine or nitrogen heterocycle. The quaternization can be carried out by alkylation of the nitrogen atom. Depending on the alkylating reagent used, salts with different anions are obtained. In cases where it is not possible to form the desired anion already during the quaternization, this can be done in a further synthesis step. Starting from, for example, an ammonium halide, the halide can be reacted with a Lewis acid to form a complex anion from halide and Lewis acid. Alternatively, replacement of a halide ion with the desired anion is possible. This can be done by adding a metal salt to precipitate the metal halide formed, via an ion exchanger, or by displacing the halide ion with a strong acid (to release the hydrohalic acid). Suitable methods are, for example, in Angew. Chem. 2000, 1 12, pp. 3926 to 3945 and the literature cited therein.

Suitable alkyl radicals by which the nitrogen atom in the amines or nitrogen heterocycles can be quaternized, for example, are Ci-C ₁₈ alkyl, preferably C _r C-io-alkyl, more preferably C ₆ alkyl and most preferably methyl. The alkyl group may be unsubstituted or have one or more identical or different substituents.

Preference is given to those compounds which contain at least one five- to six-membered heterocycle, in particular a five-membered heterocycle, which has at least one nitrogen atom and optionally one oxygen atom, particular preference is given to those compounds which have at least one five- to six-membered heterocycle Heterocycle containing one, two or three nitrogen atoms and one oxygen atom, most preferably those having two nitrogen atoms. Further preferred are aromatic heterocycles.

Particularly preferred compounds used as ionic liquids are those which have a molecular weight of less than 1000 g / mol, very particularly preferably less than 500 g / mol.

Furthermore, preference is given to those cations which are selected from the compounds of the formulas (IVa) to (IVw)

(IVi) (IVj) (IVj ')

(IVm) (IVm ') (IVn)

(IVn ')

(IVr ") (IVs) (ivt)

(IVu) (IVv) (IVw)

and oligomers containing these structures.

Further suitable cations are compounds of the general formula (IVx) and (IVy)

R ² R ²

₃ 1 "H ₁ I +.,

R - P-R S-R

I i

R R

(IVx) (IVy)

and oligomers containing this structure.

In the above formulas (IVa) to (IVy)

the radical R is hydrogen, a carbon-containing organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic, unsubstituted or interrupted by 1 to 5 heteroatoms or functional groups radical having 1 to 20 carbon atoms, and the radicals R ¹ to R ⁹ independently of one another are hydrogen, a sulfo group or a carbon-containing organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic, unsubstituted or interrupted by 1 to 5 heteroatoms or functional groups radical having 1 to 20 Carbon atoms, wherein the radicals R ¹ to R ⁹ , which in the abovementioned formulas (IV) are bonded to a carbon atom (and not to a heteroatom) may additionally be halogen or a functional group, or two adjacent radicals from the series R ¹ to R ⁹ together also represent a bivalent, carbon-containing organic, saturated or unsaturated, acyclic or cyclic, aliphatic, aromatic or araliphatic, unsubstituted or interrupted or substituted by 1 to 5 heteroatoms or functional groups Residue with 1 to 30 carbon atoms.

Suitable hetero atoms in the definition of the radicals R and R ¹ to R ^{9 are in} principle all heteroatoms in question which are capable of formally a -CH ₂ -, a -CH =, a -C≡ or a = C = group to replace. When the carbon-containing group contains heteroatoms, oxygen, nitrogen, phosphorus and silicon are preferable. As preferred groups, in particular -O-, -NR'-, -N =, -PR'-, -PR ' ₂ and -SiR' ₂ - may be mentioned, wherein the radicals R 'to the remaining part of the carbon-containing Rest is. The radicals R ¹ to R ⁹ are, in the cases in which those in the above formulas (IV) to a carbon atom (and not to a heteroatom) bound also be bound directly via the heteroatom.

Suitable functional groups are in principle all functional groups which may be bonded to a carbon atom or a heteroatom. Suitable examples are -OH (hydroxy), = 0, especially as carbonyl group, -NH ₂ (amino), -NHR ', -NR ₂ = NH (imino), -COOH (carboxy), -CONH ₂ (carboxamide), -SO ₃ H (sulfo) and -CN (cyano) called. Fractional groups and heteroatoms can also be directly adjacent, so that combinations of several adjacent atoms, such as -O- (ether) .- COO- (ester), -CONH- (secondary amide) or -CONR'- (tertiary) res amide) are included, for example, di (Ci-C4-alkyl) amino, C1-C4alkyloxycarbonyl or CrC ₄ alkyloxy. The radicals R 'are the remaining part of the carbon-containing radical.

A halogen is, for example, fluorine.

The radical R preferably stands for

unbranched or branched, unsubstituted or one to several times with hydroxy, halogen, phenyl, cyano, C 1 -C 6 -alkoxycarbonyl and / or SO ₃ H substituted CrCi ₈ alkyl having a total of 1 to 20 carbon atoms, such as

Methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1-propyl (isobutyl), 2-methyl-2-propyl (tert-butyl), 1-pentyl, 2 Pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 2,2-dimethyl-1-propyl, 1-hexyl , 2-hexyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4 -Methyl 2-pentyl, 2-methyl-3-pentyl, 3

Methyl 3-pentyl, 2,2-dimethyl-1-butyl, 2,3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, 2,3-dimethyl 2-butyl, 3,3-dimethyl-2-butyl, 1-heptyl, 1-octyl, 1 - Nonyl, 1-decyl, 1-undecyl, 1-dodecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, benzyl, 3-phenylpropyl, 2-hydroxyethyl, 2-cyanoethyl, 2- (methoxycarbonyl) -ethyl, 2- (Ethoxycarbonyl) -ethyl, 2- (n-butoxycarbonyl) -ethyl, trifluoromethyl, difluoromethyl, fluoromethyl, pentafluoroethyl, heptafluoropropyl, heptafluoroisopropyl, nona-fluorobutyl, nonafluoroisobutyl, undecylfluoropentyl, undecylfluoroisopentyl, 6-

Hydroxyhexyl and propylsulfonic acid,

Glycols, butylene glycols and their oligomers having 1 to 100 units and a hydrogen or a Ci-Cs-alkyl as an end group, such as R ^A O- (CHR ^B -CH ₂ -O) _n -CHR ^B -CH ₂ - or

R 1 is - (CH ₂ CH ₂ CH ₂ CH ₂ O) _n -CH ₂ CH ₂ CH ₂ CH ₂ O- with R ^A and R ^{B is} preferably hydrogen, methyl or ethyl and n is preferably 0 to 3, in particular 3-oxabutyl, 3-oxapentyl, 3,6-dioxaheptyl, 3,6-dioxaoctyl, 3,6,9-trioxadecyl, 3,6,9-trioxa-undecyl, 3,6,9, 12-tetraoxatridecyl and 3,6,9, 12-tetraoxatetradecyl,

Vinyl,

1-propen-1-yl, 1-propen-2-yl and 1-propen-3-yl, and

- N, N-di-C ₁ -C ₆ -alkyl-amino, such as N, N-dimethylamino and N, N-diethylamino.

The radical R particularly preferably represents unbranched and unsubstituted C 1 -C ₈ -alkyl, such as, for example, methyl, ethyl, 1-propyl, 1-butyl, 1-pentyl, 1-hexyl, 1-heptyl, 1-octyl, 1-decyl, 1 Dodecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, especially for methyl, ethyl, 1-butyl and 1-octyl, and for CH ₃ O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ - and CH ₃ CH ₂ O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ - where n is 0 to 3.

The radicals R ¹ to R ⁹ are preferably each independently

Hydrogen,

Fluorine,

a functional group,

optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and / or interrupted by one or more oxygen atoms and / or one or more substituted or unsubstituted imino groups interrupted CrCis-alkyl, optionally C ₂ -C ₈ -alkenyl which is substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and / or interrupted by one or more oxygen atoms and / or one or more substituted or unsubstituted imino groups,

optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted C ₆ -C ₂ -aryl,

optionally containing heteroatoms and / or heterocycles is by functional groups, aryl, alkyl, aryloxy, alkyloxy, halo-, _{_5-Ci2} cycloalkyl,

optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted C ₅ -C ₂ -cycloalkenyl, or

- denote a optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted five to six-membered, oxygen and / or nitrogen atoms heterocycle, or

two adjacent radicals together with the atoms to which they are attached, for

an unsaturated, saturated or aromatic ring optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and optionally interrupted by one or more oxygen atoms and / or one or more substituted or unsubstituted imino groups.

In optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles Ci-C- ₈ -alkyl is preferably methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1 -propyl (isobutyl), 2-methyl-2-propyl (tert Butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 2.2 Dimethyl-1-propyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl , 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2-methyl-3-pentyl, 3-methyl-3-pentyl, 2,2-dimethyl-1-butyl, 2,3-dimethyl-1 -butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, heptyl, octyl, 2-ethylhexyl, 2 , 4,4-trimethylpentyl, 1,1,3,3-tetramethylbutyl, 1 -nonyl, 1-decyl, 1-undecyl, 1-dodecyl, 1-tridecyl, 1-tetradecyl, 1-pentadecyl, 1-hexadecyl, 1 -Heptadecyl, 1-octadecyl, cyclopentylmethyl, 2-cyclopentylethyl, 3-cyclopentylpropyl, cyclohexylmethyl, 2-cyclohexylethyl, 3-cyclohexylpropyl, benzyl (phenylmethyl), diphenylmethyl (benzhydryl), triphenyl methyl, 1-phenylethyl, 2-phenylethyl, 3-phenylpropyl, α, α-dimethylbenzyl, p-tolylmethyl, 1- (p-butylphenyl) -ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p-methoxybenzyl, m-ethoxybenzyl, 2-cyanoethyl, 2-cyanopropyl, 2-methoxycarbonylethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1, 2-di- (methoxycarbonyl) -ethyl, methoxy, ethoxy, formyl, 1, 3 Dioxolan-2-yl, 1, 3-dioxan-2-yl, 2-methyl-1,3-dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2-hydroxyethyl, 2- Hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 6-hydroxyhexyl, 2-aminoethyl, 2-aminopropyl, 3-aminopropyl, 4-aminobutyl, 6-aminohexyl, 2-methylaminoethyl, 2-methylaminopropyl, 3-methylaminopropyl, 4- Methylaminobutyl, 6-methylaminohexyl, 2-dimethylaminoethyl, 2-dimethylaminopropyl, 3-dimethylaminopropyl, 4-dimethylaminobutyl, 6-dimethylaminohexyl, 2-hydroxy-2,2-dimethylethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 6-phenoxyhexyl, 2-methoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 6-M ethoxyhexyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl, 6-ethoxyhexyl, acetyl, CnF ₂ _(n-a) + (ib) H2a + b where n is 1 to 30, 0 <a <n and b = 0 or 1, for example CF _3, C ₂ F _5, CHzC ^ -C ^ F ^. ^, C ₆ F _13, C ₈ F _17, C ₁₀ F _21, C ₂ F _25, Chlorm eth yl, 2-chloroethyl, trichloromethyl, 1, 1-dimethyl-2-chloroethyl, methoxymethyl, 2-butoxyethyl, diethoxymethyl, diethoxyethyl, 2-isopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, 2-methoxyisopropyl, 2- (methoxycarbonyl) -ethyl, 2- (ethoxycarbonyl) ethyl, 2- (n-butoxycarbonyl) ethyl, butylthiomethyl, 2-dodecylthioethyl, 2-phenylthioethyl, 5-hydroxy-3-oxa-pentyl, 8-hydroxy-3,6-dioxa- octyl, 11-hydroxy-3,6,9-trioxa undecyl, 7-hydroxy-4-oxa-heptyl, 11-hydroxy-4,8-dioxa-undecyl, 15-hydroxy-4,8,12-trioxa pentadecyl, 9-hydroxy-5-oxa-nonyl, 14-hydroxy-5,10-dioxa-tetradecyl,

5-Methoxy-3-oxa-pentyl, 8-methoxy-3,6-dioxa-octyl, 11-methoxy-3,6,9-trioxa-undecyl, 7-methoxy-4-oxa-heptyl, 1 1-methoxy 4,8-dioxa-undecyl, 15-methoxy-4,8,12-trioxapentadecyl, 9-methoxy-5-oxa-nonyl, 14-methoxy-5,10-dioxa-tetradecyl, 5-ethoxy-3 - oxa-pentyl, 8-ethoxy-3,6-dioxa-octyl, 1-ethoxy-3,6,9-trioxa-undecyl, 7-ethoxy-4-oxo-heptyl, 1-ethoxy-4,8 dioxa undecyl, 15-ethoxy-4,8,12-trioxa-pentadecyl, 9-ethoxy-5-oxa-nonyl or 14-ethoxy-5,10-oxa-tetradecyl.

In optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles and / or interrupted by one or more oxygen atoms and / or one or more substituted or unsubstituted imino groups C ₂ -C ₁₈ alkenyl it is preferably vinyl, 2-propenyl, 3-butenyl, cis-2-butenyl, trans-2-butenyl or C _n F ₂ (na) - (ib) H ₂ ab with n <30, O ≤ a ≤ n and b = 0 or 1.

When optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles C ₆ -C ₂ -aryl is preferably phenyl, ToIyI, XyIyI, α-naphthyl, ß-naphthyl, 4- Diphenylyl, chlorophenyl, dichlorophenyl, trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, / so-propylphenyl, tert-butylphenyl, dodecylphenyl, Methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, hexyloxyphenyl, methylnaphthyl, isopropylnaphthyl, chloronaphthyl, ethoxynaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- Nitrophenyl, 4-nitrophenyl, 2,4-dinitrophenyl, 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, methoxyethylphenyl, ethoxymethylphenyl, methylthiophenyl, isopropylthiophenyl or tert-butylthiophenyl or C ₆ F _(5-a) H _a with 0 <a <5.

Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles C ₅ -C ₂ -cycloalkyl is preferably cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, Diethylcyclohexyl, butylcyclohexyl, methoxycyclohexyl, dimethoxycyclohexyl, diethoxycyclohexyl, butylthio cyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl, C _n F ₂ ( _n ) - (ib) H 2a-b with n <30, 0 <a <n and b = 0 or 1 and a saturated or unsaturated bicyclic system such. Norbornyl or norbornenyl.

May optionally be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted _{_C5-Ci2} cycloalkenyl, it is preferably 3-cyclopentenyl, 2-cyclohexenyl, 3-cyclohexenyl, 2,5- Cyclohexadienyl or C _n F ₂ (na) -3 (ib) H 2a-3b with n <30, 0 <a <n and b = 0 or 1.

An optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles substituted five- to six-membered, oxygen and / or nitrogen atoms heterocycle is preferably furyl, pyrryl, pyridyl, indolyl, benzoxazolyl , Dioxolyl, dioxy, benzimidazolyl, dimethylpyridyl, methylquinolyl, dimethylpyrryl, methoxyfuryl, dimethoxypyridyl or difluoropyridyl.

If two neighboring radicals together form an unsaturated, saturated or aromatic radical, if appropriate by functional groups, aryl, alkyl, aryloxy, alkyloxy,

Halogen, heteroatoms and / or heterocycles-substituted and optionally interrupted by one or more oxygen atoms and / or one or more substituted or unsubstituted imino groups ring, it is preferably 1, 3

Propylene, 1,4-butylene, 1,5-pentylene, 2-oxa-1,3-propylene, 1-oxa-1,3-propylene, 2-oxa-1,3-propylene, 1-oxa-1, 3-propenylene, 3-oxa-1, 5-pentylene, 1-aza-1, 3-propenylene, 1-ci

C ₄ alkyl 1 -aza-1, 3-propenylene, 1, 4-buta-1, 3-dienylene, 1 -zaza-1, 4-buta-1,3-dienylene or 2-aza-1 , 4-buta-1,3-dienylene.

If the abovementioned radicals contain oxygen atoms and / or substituted or unsubstituted imino groups, the number of oxygen atoms and / or imino groups pen not limited. As a rule, it is not more than 5 in the radical, preferably not more than 4, and very particularly preferably not more than 3.

If the abovementioned radicals contain heteroatoms, then between two heteroatoms there are generally at least one carbon atom, preferably at least two carbon atoms.

Particularly preferably, the radicals R ¹ to R ⁹ independently of one another are hydrogen, straight-chain or branched, unsubstituted or C 1 -C ₆ -alkyl which is monosubstituted to hydroxyl, halogen, phenyl, cyano, C 1 -C ₆ -alkoxycarbonyl and / or SO ₃ H having in total from 1 to 20 carbon atoms, such as, for example, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1-propyl (isobutyl), 2-

Methyl 2-propyl (tert -butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3 Methyl 2-butyl, 2,2-dimethyl-1-propyl, 1-hexyl, 2-H exyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1 pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2-methyl-3-pentyl, 3-methyl-3-pentyl, 2,2-dimethyl-1 butyl, 2,3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl,

2-ethyl-1-butyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, 1-heptyl, 1-octyl, 1-nonyl, 1-decyl, 1-undecyl, 1 - Dodecyl, 1-tetradecyl, 1-hexadecyl, 1-octadecyl, benzyl, 3-phenylpropyl, 2-hydroxyethyl, 2-cyanoethyl, 2- (methoxycarbonyl) -ethyl, 2- (ethoxycarbonyl) -ethyl, 2- (n-butoxy -carbonyl) -ethyl, trifluoromethyl, difluoromethyl, fluoromethyl, pentafluoroethyl, heptafluoropropyl, heptafluoroisopropyl, nona-fluorobutyl, nonafluoroisobutyl, undecylfluoropentyl, undecylfluoroisopentyl, 6-hydroxyhexyl and propylsulfonic acid,

Glycols, butylene glycols and their oligomers having 1 to 100 units and a hydrogen or a C 1 to C ₈ alkyl as an end group, such as

R ^A O- (CHR ^B -CH ₂ -O) _n -CHR ^B -CH ₂ - or

Vinyl,

1-propene-1yl, 1-propen-2-yl and 1-propen-3yl, and

N, N-di-C ₁ -C ₆ -alkylamino, such as, for example, N, N-dimethylamino and N, N-

Diethylamino. Most preferably, the radicals R ¹ to R ⁹ independently of one another are hydrogen or C 1 -C ₈ -alkyl, such as, for example, methyl, ethyl, 1-butyl, 1-pentyl, 1-hexyl, 1-heptyl, 1-octyl, for phenyl, 2-hydroxyethyl, 2-cyanoethyl, 2- (methoxycarbonyl) ethyl, 2- (ethoxycarbonyl) ethyl, 2- (n-butoxycarbonyl) ethyl, N, N-dimethylamino, N, N-diethylamino, for chlorine and for CH ₃ O- (CH ₂ CH ₂ O) _n - CH ₂ CH ₂ - and CH ₃ CH ₂ O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ - with n being equal to 0 to 3.

Very particular preference is given as pyridinium ions (IVa) to those in which - one of the radicals R ¹ to R ^{5 is} methyl or ethyl and the remaining radicals R ¹ to R ^{5 are} hydrogen,

R ^{3 is} dimethylamino and the remaining radicals R ¹ , R ² , R ⁴ and R ^{5 are} hydrogen, all radicals R ¹ to R ^{5 are} hydrogen,

R ^{2 is} carboxy or carboxamide and the remaining radicals R ¹ , R ² , R ⁴ and R ^{5 are} hydrogen, or

R ¹ and R ² or R ² and R ^{3 is} 1,4-buta-1,3-dienylene and the remaining radicals

R ¹ , R ² , R ⁴ and R ^{5 are} hydrogen, and in particular those in which - R ¹ to R ^{5 are} hydrogen, or one of the radicals R ¹ to R ^{5 is} methyl or ethyl and the remaining radicals R ¹ to R ^{5 are} hydrogen. Very particularly preferred pyridinium ions (IVa) are selected from the group consisting of 1-methylpyridinium, 1-ethylpyridinium, 1- (1-butyl) pyridinium, 1- (1-hexyl) pyridinium, 1- (1-octyl) pyridinium, 1 - (1-Hexyl) pyridinium, 1- (1-octyl) pyridinium, 1- (1-dodecyl) pyridinium, 1- (1-tetradecyl) pyridinium, 1- (1-hexadecyl) pyridinium, 1 , 2-Dimethylpyridinium, 1-ethyl-2-methylpyridinium, 1- (1-butyl) -2-methylpyridinium, 1- (1-hexyl) -2-methylpyridinium, 1- (1-octyl) -2-methylpyridinium, 1 - (1-dodecyl) -2-methylpyridinium, 1- (1-tetradecyl) -2-methylpyridinium, 1- (1-hexadecyl) -2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1,2-diethylpyridinium, 1 (1-butyl) -2-ethylpyridinium, 1- (1-hexyl) -2-ethylpyridinium, 1- (1-octyl) -2-ethylpyridinium, 1- (1-dodecyl) -2-ethylpyridinium, 1- ( 1-tetradecyl) -2-ethylpyridinium, 1- (1-hexadecyl) -2-ethylpyridinium, 1, 2-dimethyl-5-ethylpyridinium, 1,5-diethyl-2-methylpyridinium, 1- (1 Butyl) -2-methyl-3-ethyl-pyridinium, 1- (1-hexyl) -2-methyl-3-ethylpyridinium and 1 (1-Octyl) -2-methyl-3-ethylpyridinium, 1- (1-dodecyl) -2-methyl-3-ethylpyridinium, 1- (1-tetradecyl) -2-methyl-3-ethyl- pyridinium, 1- (1-hexadecyl) -2-methyl-3-ethylpyridinium and mixtures thereof. Very particularly preferred pyridazinium ions (IVb) are those in which - R ¹ to R ^{4 are} hydrogen, or one of the radicals R ¹ to R ^{4 is} methyl or ethyl and the remaining radicals R ¹ to R ^{4 are} hydrogen. Very particularly preferred pyrimidinium ions (IVc) are those in which

R ^{1 is} hydrogen, methyl or ethyl and R ² to R ^{4 are} independently hydrogen or methyl, or

R ^{1 is} hydrogen, methyl or ethyl, R ² and R ^{4 are} methyl and R ^{3 is} hydrogen.

Very particularly preferred pyrazinium ions (IVd) are those in which

R ^{1 is} hydrogen, methyl or ethyl and R ² to R ^{4 are} independent of one another

Are hydrogen or methyl,

R ^{1 is} hydrogen, methyl or ethyl, R ² and R ^{4 are} methyl and R ^{3 is} hydrogen,

R ¹ to R ^{4 are} methyl, or

R ¹ to R ^{4 are} hydrogen.

Very particular preference is given to using as imidazolium ions (IVe) those in which

R ^{1 is} hydrogen, methyl, ethyl, 1-propyl, 1-butyl, 1-pentyl, 1-hexyl, 1-octyl, 2-hydroxyethyl or 2-cyanoethyl and R ² to R ⁴ are each independently hydrogen, methyl or ethyl are.

Very particularly preferred imidazolium ions (IVe) are selected from the group consisting of 1-methylimidazolium, 1-ethylimidazolium, 1- (1-butyl) -imidazolium, 1- (i-octyl) -imidazolium, 1- (1-dodecyl) -imidazolium, 1- (1-tetradecyl) -imidazolium, 1- (1-hexadecyl) -imidazolium, 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1- (1-butyl) -3-methylimidazolium, 1 - (1-Butyl) -3-ethylimidazolium, 1- (1-hexyl) -3-methylimidazolium, 1- (1-hexyl) -3-ethylimidazolium, 1- (1-hexyl) -3-butyl -imidazolium, 1- (1-octyl) -3-methylimidazolium, 1- (1-octyl) -3-ethylimidazolium, 1- (1-octyl) -3-butylimidazolium, 1- (1-dodecyl) -3-methylimidazolium , 1- (1-dodecyl) -3-ethylimidazolium, 1- (1-dodecyl) -3-butylimidazolium, 1- (1-dodecyl) -3-octylimidazolium, 1 - (1-tetradecyl) -S-methylimidazolium, 1- (1-tetradecyl) -3-ethylimidazolium, 1- (1-tetradecyl) -3-butylimidazolium, 1- (1-tetradecyl-1-S-octylimidazolium, 1 - ( 1-hexadecyl) -3-methylimidazolium, 1- (1-hexadecyl) -3-ethylimidazolium, 1- (1-hexadecyl) -3-butylimidazolium, 1- (1-hexadecyl) -3-octylimidazolium, 1,2-dimethylimidazolium , 1,2,3- trimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1- (1-butyl) -2,3-dimethylimidazolium, 1- (1-hexyl) -2,3-dimethylimidazolium, 1 - (1-octyl) -2,3-dimethylimidazolium, 1, 4-dimethylimidazolium, 1, 3,4-trimethylimidazolium, 1, 4-dimethyl-3-ethylimidazolium, 3-butylimidazolium, 1, 4-dimethyl 3-octylimidazolium, 1, 4,5-trimethylimidazolium, 1, 3,4,5-tetramethylimidazolium, 1, 4,5-trimethyl-3-ethylimidazolium, 1, 4,5-trimethyl-3-butylimidazolium, 1 , 4,5-trimethyl-3-octylimidazolium and 1 - (prop-1 -en-3-yl) -3-methylimidazolium.

Very particular preference is given as Pyrazoliumionen (IVf), (IVg) or (IVg ') such, in which

Are hydrogen or methyl.

Very particularly preferred pyrazolium ions (IVh) are those in which

R ¹ to R ^{4 are} independently hydrogen or methyl.

Very particular preference is given to using as 1-pyrazolinium ions (IVi) those in which, independently of one another, R ¹ to R ^{6 are} hydrogen or methyl.

Very particular preference is given to using 2-pyrazolinium ions (IVj) or (IVj ') as those in which

R ^{1 is} hydrogen, methyl, ethyl or phenyl and R ² to R ^{6 are} independently hydrogen or methyl.

Very particular preference is given to using as 3-pyrazolinium (IVk) or (IVk ') such, in which

R ¹ and R ^{2 are} independently hydrogen, methyl, ethyl or phenyl and R ³ to R ^{6 are} independently hydrogen or methyl. Very particularly preferred as Imidazoliniumionen (IVI) are those in which R ¹ and R ^{2 are} independently hydrogen, methyl, ethyl, 1-butyl or phenyl, R ³ and R ^{4 are} independently hydrogen, methyl or ethyl, and R ⁵ and R ^{6 are} independently hydrogen or methyl. Very particular preference is given to imidazolinium ions (IVm) or (IVm ') those in which

R ¹ and R ^{2 are} independently hydrogen, methyl or ethyl and R ³ to R ^{6 are} independently hydrogen or methyl.

Very particular preference is given as Imidazoliniumionen (IVn) or

(IVn ') those in which

R ¹ to R ^{3 are} independently hydrogen, methyl or ethyl and R ⁴ to R ^{6 are} independently hydrogen or methyl.

Very particular preference is given to using 1, 2,4-triazolium ions (IVq), (IVq ') or (IVq ") those in which

- R ¹ and R ^{2 are} independently hydrogen, methyl, ethyl or phenyl and R ^{3 is} hydrogen, methyl or phenyl.

Very particular preference is given to using as 1,3,3-triazolium ions (IVr), (IVr ') or (IVr ") those in which

R ^{1 is} hydrogen, methyl or ethyl and R ² and R ^{3 are} independent of each other

R ² and R ³ together are 1, 4-buta-1, 3-dienylene.

Very particularly preferred pyrrolidinium ions (IVs) are those in which

R ^{1 is} hydrogen, methyl, ethyl or phenyl and R ² to R ^{9 are} independently hydrogen or methyl.

Very particular preference is given to using as imidazolidinium ions (IVt) those in which

R ¹ and R ^{4 are} independently hydrogen, methyl, ethyl or phenyl and R ² and R ³ and R ⁵ to R ^{8 are} independently hydrogen or methyl.

Very particular preference is given to using as ammonium ions (IVu) those in which R ¹ to R ^{3 are} independently Cr to C ₈ alkyl, or

R ¹ and R ² together are 1, 5-pentylene or 3-oxa-1, 5-pentylene and R ^{3 is} Ci-Ci ₈ - alkyl, 2-hydroxyethyl or 2-cyanoethyl.

Very particularly preferred ammonium ions (IVu) are methyltri (1-butyl) ammonium, N, N-dimethylpiperidinium and N, N-dimethylmorpholinium.

Examples of the tertiary amines of which the quaternary ammonium ions of the general formula (IVu) are derived by quaternization with the abovementioned radicals R, are diethyl-n-butylamine, diethyl-tert-butylamine, diethyl-n-pentylamine, diethyl hexylamine, diethyloctylamine, diethyl (2-ethylhexyl) amine, di-n-propylbutylamine, di-n-propyl-n-pentylamine, di-n-propylhexylamine, di-n-propyloctylamine, di-n-propyl (2 -ethyl-hexyl) -amine, di-isopropylethylamine, di-iso-propyl-n-propylamine, di-isopropyl-butylamine, di-isopropylpentylamine, di-iso-propylhexylamine, di-isopropyloctylamine, di-iso-propyl (2 ethylhexyl) amine, di-n-butylethylamine, di-n-butyl-n-propylamine, di-n-butyl-n-pentylamine, di-n-butylhexylamine, di-n-butyloctylamine, di-n-butyl (2-ethylhexyl) -am in, Nn-butylpyrrolidine, N-sec-butylpyrrodidine, N-tert-butylpyrrolidine, Nn-pentylpyrrolidine, N, N-dimethylcyclohexylamine, N, N-diethylcyclohexylamine, N, N-di-n -butylcyclohexylamine, N-n-propylpiperidine, N-iso-propylpiperidine, Nn-butyl -piperidine, N-sec-butylpiperidine, N-tert-butylpiperidine, Nn-pentylpiperidine, Nn-butylmorpholine, N-sec-butylmorpholine, N-tert-butylmorpholine, Nn-pentylmorpholine, N-benzyl-N-ethylaniline, N-benzyl N-propylaniline, N-benzyl-N-iso-propylaniline, N-benzyl-Nn-butylaniline, N, N-dimethyl-p-toluidine, N, N-diethyl-p-toluidine, N, N-di -n-butyl-p-toluidine, diethylbenzylamine, di-n-propylbenzylamine, di-n-butylbenzylamine, diethylphenylamine, di-n-propylphenylamine and di-n-butylphenylamine.

Preferred quaternary ammonium salts of the general formula (IVu) are those which can be derived from the following tertiary amines by means of quaternization with the abovementioned radicals R, such as diisopropylethylamine, diethyl-tert-butylamine, diisopropylbutylamine, di-n -butyl-n-pentylamine, N, N-di-n-butylcyclohexylamine and tertiary amines of pentyl isomers.

Particularly preferred tertiary amines are di-n-butyl-n-pentylamine and tertiary amines of pentyl isomers. Another preferred tertiary amine having three identical residues is triallylamine.

Very particular preference is given as guanidinium ions (IVv) to those in which - R ¹ to R ^{5 are} methyl.

As a very particularly preferred guanidinium ion (IVv) may be mentioned N, N, N ', N', N ", N" - hexamethylguanidinium. Very particular preference is given to using as cholinium ions (IVw) those in which R ¹ and R ² independently of one another are methyl, ethyl, 1-butyl or 1-octyl and R ^{3 is} hydrogen, methyl, ethyl, acetyl, -SO ₂ OH or -PO (OH) ₂ is,

R ^{1 is} methyl, ethyl, 1-butyl or 1-octyl; R ^{2 is} -CH ₂ -CH ₂ -OR ⁴ -; and

R ³ and R ^{4 are} independently hydrogen, methyl, ethyl, acetyl, -SO ₂ OH or -PO (OH) ₂ , or - R ^{1 is} a -CH ₂ -CH ₂ -OR ⁴ group, R ^{2 is} a - CH ₂ -CH ₂ -OR ⁵ group and R ³ to R ^{5 are} independently hydrogen, methyl, ethyl, acetyl, -SO ₂ OH or - PO (OH) ₂ .

Particularly preferred cholinium ions (IVw) are those in which R ^{3 is} selected from hydrogen, methyl, ethyl, acetyl, 5-methoxy-3-oxa-pentyl, 8-methoxy-3,6-dioxo-octyl, 1 1-methoxy 3,6,9-trioxa undecyl, 7-methoxy-4-oxa-heptyl, 1 1-methoxy-4,8-dioxa undecyl, 15-methoxy-4,8,12-trioxa-pentadecyl, 9- Methoxy-5-oxa-nonyl, 14-methoxy

5,10-oxa-tetradecyl, 5-ethoxy-3-oxa-pentyl, 8-ethoxy-3,6-dioxa-octyl, 1 1 -ethoxy-3,6,9-trioxa-undecyl, 7-ethoxy-4 -oxa-heptyl, 1-ethoxy-4,8-dioxa-undecyl, 15-ethoxy-4,8,12-trioxa-pentadecyl, 9-ethoxy-5-oxa-nonyl or 14-ethoxy-5,10- oxa-tetradecyl.

Very particularly preferred phosphonium ions (IVx) are those in which - R ¹ to R ^3, independently of one another, are C 1 -C ₈ -alkyl, in particular butyl, isobutyl, 1-hexyl or 1-octyl.

Among the above-mentioned heterocyclic cations, the pyridinium ions, pyrazolinium, pyrazolium ions and imidazolinium and imidazolium ions are preferable. Furthermore, ammonium ions are preferred.

Particular preference is given to 1-methylpyridinium, 1-ethylpyridinium, 1- (1-butyl) pyridinium, 1- (1-hexyl) pyridinium, 1- (1-octyl) pyridinium, 1- (1-hexyl) -pyridinium , 1- (1-octyl) -pyridinium, 1- (1-dodecyl) -pyridinium, 1- (1-tetradecyl) -pyridinium, 1- (1-hexadecyl) -pyridinium, 1, 2-dimethylpyridinium, 1 Ethyl 2-methylpyridinium, 1- (1-butyl) -2-methylpyridinium, 1- (1-hexyl) -2-methylpyridinium, 1- (1-octyl) -2-methylpyridinium, 1- (1-dodecyl) 2-methylpyridinium, 1- (1-tetradecyl) -2-methylpyridinium, 1- (1-hexadecyl) -2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1, 2-diethylpyridinium, 1- (1-butyl) -2-ethylpyridinium, 1- (1-hexyl) -2-ethylpyridinium, 1- (1-octyl) -2-ethylpyridinium, 1- (1-dodecyl) -2-ethylpyridinium, 1- (1-tetradecyl) -2-ethylpyridinium, 1- (1-hexadecyl) -2-ethyl-pyridinium, 1,2-dimethyl-5-ethylpyridinium, 1,5-diethyl-2-methylpyridinium, 1- (1-butyl) 2-methyl-3-ethyl-pyridinium, 1- (1-hexyl) -2-methyl-3-ethyl-pyridinium, 1- (1-octyl) -2-methyl-3-ethyl-pyr idinium, 1- (1-dodecyl) -2-methyl-3-ethylpyridinium, 1- (1-tetra-) decyl) -2-methyl-3-ethylpyridinium, 1- (1-hexadecyl) -2-methyl-3-ethylpyridinium, 1-methyl in idazole, 1-ethylimidazolium, 1- (1-butyl) imidazolium, 1- (1-octyl) imidazolium, 1- (1-dodecyl) imidazolium, 1- (1-tetradecyl) imidazolium, 1- (1-hexadecyl) imidazolium, 1,3-dimethyl imidazolium , 1-ethyl-3-methylimidazolium, 1- (1-butyl) -3-methylimidazolium, 1- (1-hexyl) -3-methylimidazolium, 1- (1-octyl) -3-methylimidazolium, 1 - (1-Dodecyl) -3-methylimidazolium, 1- (1-tetradecyl) -3-methylimidazolium, 1- (1-hexadecyl) -3-methylimidazolium, 1, 2-dimethylimidazolium, 1,2,3-trimethylimidazolium , 1-ethyl-2,3-dimethylimidazolium, 1- (1-butyl) -2,3-dimethylimidazolium, 1- (1-hexyl) -2,3-dimethylimidazolium and 1- (1-octyl) -2 , 3-dimethylimidazolium, 1, 4-dimethylimidazolium, 1, 3,4-trimethylimidazolium, 1, 4-dimethyl-3-ethylimidazolium, 3-butylimidazolium, 1, 4-dimethyl-3-octylimidazolium, 1, 4 , 5-trimethylimidazolium, 1, 3,4,5-tetramethylimidazolium, 1, 4, 5-trimethyl-3-ethylimide azolium, 1, 4,5-trimethyl-3-butylimidazolium, 1, 4,5-trimethyl-3-octylimidazolium and 1- (prop-1 -en-3-yl) -3-methylimidazolium, most preferably 1 ethyl-2,3-dimethylimidazolium.

As anions, in principle, all anions can be used.

The ion [Y] "^{" of} the ionic liquid is for example selected from the group consisting of F ^" , BF ₄ ^" , PF ₆ ^" , CF ₃ SO ₃ ^" , (CF ₃ SO ₃ ) ₂ N ^" , CF ₃ CO ₂ ^" , CCI ₃ CO ₂ ^" and mixtures thereof, the group of sulfates, sulfites and sulfonates of the general formula: SO4 ^{2 "} , HSO ₄ ^" , SO ₃ ^{2 "} , HSO ₃ ^" , ROSO ₃ ^" , R ³ SO ₃ ^" and Mixtures thereof,

the group of phosphates of the general formula: PO ₄ ^{3 "} , H PO ₄ ^2" , H ₂ PO ₄ ^" , R ^a" PO ₄ ^{2 "} , HR ³ PO ₄ ^" , R ^a R ^b PO ₄ ^" and mixtures thereof,

the group of phosphonates and phosphinates of the general formula: R ³ HPO ₃ ^' , R ^a R ^b PO ₂ ^" , R ^a R ^b PO ₃ ^" and mixtures thereof, the group of phosphites of the general formula: PO ₃ ^{3 "} , HPO ₃ ^{2 "} , H ₂ PO ₃ ^" , R ^{a "} PO ₃ ^2" , R ³ HPO ₃ ^" , R ³ R ^b PO ₃ ^~ and mixtures thereof, - the group of phosphonites and phosphinites of the general formula: R ^a R ^b PO ₂ ^" , R ³ HPO ₂ ^" , R ³ R ^b P0 ^" , R ³ HPO ^" and mixtures thereof, the group of carboxylic acids of the general formula: R ^a COO ^" and mixtures thereof, - the group of borates of the general formula: BO ₃ ^{3 "} , HBO ₃ ^2" , H ₂ BO ₃ ^" , R ³ R ^b BO ₃ ^" , R ³ HBO ₃ ^" , R ³ BO ₃ ^2" , B (OR ³ ) (0R ^b ) (0R ^c ) ( 0R ^d ) ^" , B (HSO ₄ ) ^" , B (R ³ SO ₄ ) ^" and mixtures thereof, the group of boronates of the general formula: R ^a BO ₂ ^{2 "} , R ^a R ^b BO ^" and mixtures thereof, the group of carbonates and carbonic esters of the general formula: HCO ₃ ^" , CO ₃ ^2" , R ³ CO ₃ ^" and Mixtures thereof, the group of silicates and silicic acid esters of the general formula: SiO ₄ ^{4 "} , HSiO ₄ ^3" , H ₂ SiO ₄ ^{2 "} , H ₃ SiO ₄ ^" , R ³ SiO ₄ ^{3 "} , R ^a R ^b Si0 ₄ ^{2 "} R ^a R ^b R ^c Si0 ₄ ^" , HR ³ SiO ₄ ^{2 "} , H ₂ R ³ SiO ₄ ^" , HR ^a R ^b Si0 ₄ ^" and mixtures thereof, the group of alkyl or aryl silane salts of the general Formula: R ³ SiO ₃ ^{3 "} ,

R ^a R ^b Si0 ₂ ^{2 "} , R ^a R ^b R ^c Si0 ^" , R ^a R ^b R ^c SiO ₃ ^" , R ^a R ^b R ^c SiO ₂ ^" , R ^a R ^b Si0 ₃ ^{2 "} and mixtures thereof, the group of the carboxylic imides, bis (sulfonyl) imides, sulfonyl imides and cyanamide of the general formula:

the group of methides of the general formula:

SO, -R ^a

/ ^ \

R ^b -O ₂ S SO ₂ -R ^C

the group of alkoxides and aryloxides of the general formula: RO ^" and mixtures thereof,

the group of halometallates of the general formula [M _q Hal _r ] ^{s "} , where M is a metal and Hal is fluorine, q and r are positive integers and indicate the stoichiometry of the complex and s is an integer positive number and indicating the charge of the complex and mixtures thereof,

the group of complex metal ions such as Fe (CN) ₆ ^{3 "} , Fe (CN) ₅ ^4" , MnO ₄ ^" , Fe (CO) ₄ ^" and mixtures thereof. Herein, R ^a, R ^b, R ^c and R ^d are each independently hydrogen, Ci-C ₃₀ - alkyl, optionally substituted by one or more nonadjacent oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino n groups interrupted C ₂ -C ₈ -alkyl, C ₆ -C ₄ -aryl, C ₅ -C ₂ -cycloalkyl or a five- to six-membered, oxygen, nitrogen and / or sulfur atoms containing heterocycle, wherein two of them together unsubstituted, saturated or aromatic, optionally interrupted by one or more oxygen and / or sulfur atoms and / or one or more unsubstituted or substituted imino groups ring, said radicals each additionally by functional groups, aryl, alkyl, aryloxy, alkyloxy, Halogen, heteroatoms and / or heterocycles can be substituted.

Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles CrCi ₈ alkyl are, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, Hexyl, heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 1,1-dimethylpropyl, 1,1-dimethylbutyl, 1,1,3,3- Tetramethylbutyl, benzyl, 1-phenylethyl, α, α-dimethylbenzyl, benzhydryl, p-tolylmethyl, 1- (p-butylphenyl) -ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p -methoxybenzyl, m-ethoxybenzyl, 2- Cyanoethyl, 2-cyanopropyl, 2-methoxycarbonethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1, 2-di- (methoxycarbonyl) -ethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, diethoxymethyl, diethoxyethyl, 1, 3-dioxolan-2-yl, 1, 3-dioxan-2-yl, 2-methyl-1,3-dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2-isopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, chloromethyl, trichloromethyl, trifluoromethyl, 1, 1-Dim ethyl 2-chloroethyl, 2-methoxyisopropyl, 2-ethoxyethyl, butylthiomethyl, 2-dodecylthioethyl, 2-phenylthioethyl, 2,2,2-trifluoroethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 6 Hydroxyhexyl, 2-aminoethyl, 2-aminopropyl, 4-aminobutyl, 6-aminohexyl, 2-methylaminoethyl, 2-methylaminopropyl, 3-methylaminopropyl, 4-methylaminobutyl, 6-methylaminohexyl, 2-dimethylaminoethyl, 2-dimethylaminopropyl , 3-dimethylaminopropyl, 4-dimethylaminobutyl, 6-dimethylaminohexyl, 2-hydroxy-2,2-dimethylethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 6-phenoxyhexyl, 2-methoxyethyl, 2 Methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 6-methoxyhexyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl or 6-ethoxyhexyl.

Optionally interrupted by one or more non-adjacent oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino interrupted C _Σ -C-is-alkyl, for example, 5-hydroxy-3-oxapentyl, 8-hydroxy-3,6 dioxaoctyl, 1-hydroxy-3,6,9-trioxaundecyl, 7-hydroxy-4-oxaheptyl, 1-hydroxy-4,8-dioxaundecyl, 15-hydroxy-4,8,12-trioxapentadecyl, 9-hydroxy 5-oxa-nonyl, 14-hydroxy-5,10-oxatetradecyl, 5-methoxy-3-oxapentyl, 8-methoxy-3,6-dioxo-octyl, 11-methoxy-3,6,9-trioxaundecyl, 7 -Methoxy-4-oxaheptyl, 1-methoxy-4,8-dioxa- undecyl, 1 5-methoxy-4,8,12-trioxapentadecyl, 9-methoxy-5-oxanonyl, 14-methoxy-5,10-oxatetradecyl, 5-ethoxy-3-oxapentyl, 8-ethoxy-3,6-dioxaoctyl , 11-ethoxy-3,6,9-trioxaundecyl, 7-ethoxy-4-oxaheptyl, 1-ethoxy-4,8-dioxaundecyl, 15-ethoxy-4,8,12-trioxapentadecyl, 9-ethoxy-5- oxanonyl or 14-ethoxy-5,10-oxatetradecyl.

If two radicals form a ring, these radicals can be taken together, for example, as fused building block 1, 3-propylene, 1,4-butylene, 2-oxa-1,3-propylene, 1-oxa-1,3-propylene, 2-oxa 1, 3-propenylene, 1-aza-1, 3-propenylene, 1-C 1 -C ₄ -alkyl-1-aza-1, 3-propenylene, 1, 4-buta-1, 3-dienylene, 1-aza-1, 4-buta-1, 3-dienylene or 2-aza-1, 4-buta-1, 3-dienylene mean.

The number of non-adjacent oxygen and / or sulfur atoms and / or imino groups is basically not limited, or is automatically limited by the size of the remainder or the ring building block. As a rule, it is not more than 5 in the respective radical, preferably not more than 4 or very particularly preferably not more than 3. Furthermore, at least one, preferably at least two, carbon atoms (e) are generally present between two heteroatoms.

Substituted and unsubstituted imino groups may be, for example, imino, methylimino, iso-propylimino, n-butylimino or tert-butylimino.

The term "functional groups" is to be understood as meaning, for example, the following: carboxy, carboxamide, hydroxy, di- (C 1 -C ₄ -alkyl) -amino, C 1 -C ₄ -alkyloxycarbonyl, cyano or C 1 -C ₄ -alkoxy to C ₄ alkyl, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl or tert-butyl.

Optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles Cε-Cu-aryl are, for example, phenyl, ToIyI, XyIyI, α-naphthyl, ß-naphthyl, 4-diphenylyl, chlorophenyl, dichlorophenyl, Trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, iso-propylphenyl, tert-butylphenyl, dodecylphenyl, methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, hexyloxyphenyl, methylnaphthyl, isophenylphenyl, chlorothiphtyl, eth oxynaphthyl, 2, 6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or A-nitrophenyl, 2,4- or 2,6-dinitrophenyl , 4-dimethylaminophenyl, 4-acetylphenyl, methoxyethylphenyl or ethoxymethylphenyl.

Optionally C ₅ -C 12 -cycloalkyl which is substituted by functional groups, aryl, alkyl, aryloxy, halogen, heteroatoms and / or heterocycles are, for example, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, diethylcyclohexyl, butylcyclohexyl, methoxycyc - lohexyl, dimethoxycyclohexyl, diethoxycyclohexyl, butylthiocyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl and a saturated or unsaturated bicyclic system such as norbornyl or norbornenyl.

A five- to six-membered, oxygen, nitrogen and / or sulfur-containing heterocycle is, for example, furyl, thiophenyl, pyryl, pyridyl, indolyl, benzoxazolyl, dioxolyl, dioxy, benzimidazolyl, benzothiazolyl, dimethylpyridyl, methylquinolyl, dimethylpyryl, methoxyfuryl , Dimethoxypyridyl, difluoropyridyl, methylthiophenyl, isopropylthiophenyl or tert-butylthiophenyl.

Particularly preferred anions are selected from the group consisting of selected from the group consisting of F ^" , BF ₄ ^" , PF ₆ ^" , CF ₃ SO ₃ ^" , (CF ₃ SOs) ₂ N ^" , CF ₃ CO ₂ ^" , from the Group of sulfates, sulfites and sulfonates of the general formula: SO ₄ ^{2 "} , HSO ₄ ^" , SO ₃ ^{2 "} , HSO ₃ ^" , ROSO ₃ ^" , R ³ SO ₃ ^" , from the group of phosphates of the general formula PO ₄ ^{3 "} , HPO ₄ ^2" , H ₂ PO ₄ ^" , R ³ PO ₄ ^2" , from the group of the borates of the formula BO ₃ ^{3 "} , H BO ₃ ^2" , H ₂ BO ₃ ^" , from the group of Silicates and silicic acid esters of the formula SiO ₄ ^{4 "} , HSiO ₄ ^3" , H ₂ SiO ₄ ^{2 "} , H ₃ SiO ₄ ^" , the carboxylic acid imides, bis (sulfonyl) imides, and sulfonylimides of the general formulas depicted above, and mixtures thereof, wherein R ^a and R ^{b are more} preferably selected from methyl, ethyl, propyl or butyl.

In a particularly preferred embodiment, ionic liquids of the formula I with [A] ⁺ equal to 1-ethyl-2,3-dimethylimidazolium and [Y] ⁺ are ethylsulfate, ie 1-ethyl-2,3-dimethylimidazolium ethylsulfate used.

In a preferred embodiment, at least one organic solvent and / or water is present in the catalyst ink according to the invention in addition to the at least one ionic liquid.

Suitable solvents are those which are already known to those skilled in the art from the prior art as suitable for use in catalyst inks. Examples of suitable organic solvents are selected from the group consisting of monohydric and polyhydric alcohols, nitrogen-containing polar solvents, glycols, glycol ether alcohols, glycol ethers and mixtures thereof. Particularly suitable are, for example, propylene glycol, dipropylene glycol, glycerol, ethylene glycol, hexylene glycol, dimethylacetamide (DMAc), dimethylformamide (DMF), N-methylpyrrolidone (NMP), n-propanol and mixtures thereof. In a further embodiment of the process according to the invention, water may also be present in the catalyst ink according to the invention. If at least one organic solvent and water are present in addition to the at least one ionic liquid in the catalyst ink according to the invention, this mixture is present in an amount of generally from 0.1 to 5 parts by weight, preferably from 0.8 to 4 parts by weight, more preferably from 1 to 3 Parts by weight, based in each case on the total catalyst ink. The at least one organic solvent is generally present in an amount of from 0.1 to 5 parts by weight, preferably from 0.5 to 2.5 parts by weight, more preferably from 1 to 2 parts by weight, based in each case on the total catalyst ink. Water is generally present in an amount of from 1 to 4 parts by weight, preferably from 1 to 3.5 parts by weight, more preferably from 1 to 3 parts by weight, based in each case on the total catalyst ink.

In addition to the above-mentioned components, at least one ionomer, preferably having acidic properties, is generally present in the catalyst ink according to the invention. The ionomers dispersed in the catalyst ink according to the invention are known to the person skilled in the art and are disclosed, for example, in WO-A 03/054991.

Preferably, at least one ionomer is used which has sulfonic acid, carboxylic acid and / or phosphonic acid groups and their salts. Suitable ionomers containing sulfonic acid, carboxylic acid and / or phosphonic acid groups are likewise known to the person skilled in the art. Under sulfonic, carboxylic and / or phosphonic acid groups groups of the formulas -SO ₃ X, -COOX and -PO3X2 are to be understood, where X is H, NH ₄ ^+, NH ₃ R ^1+, NH ₂ R _'3 ^+, NHR ' ₃ ⁺ , NR' ₄ ⁺ , Na ⁺ , K ⁺ or Li ⁺ , where R 'is any radical, preferably an alkyl radical which optionally has one or more further radicals, for example one or more perfluorinated radicals, which are described for Fuel cells usually protons can present conditions.

Examples of preferred ionomers are sulfonic acid-containing polymers selected from the group consisting of perfluorinated sulfonated hydrocarbons such as Nafion® from EI Dupont, sulfonated aromatic polymers such as sulfonated polyaryl ether ketones such as polyether ether ketones (sPEEK), sulfonated polyether ketones (sPEK), sulfonated polyether ketone ketones (sPEKK), sulfonated Polyether ether ketone ketones (sPEEKK), sulfonated polyether ketone ether ketone ketone (sPEKEKK), sulfonated polyarylene ether sulfones, sulfonated polybenzobisbenzazoles, sulfonated polybenzothiazoles, sulfonated polybenzimidazoles, sulfonated polyamides, sulfonated polyetherimides, sulfonated polyphenylene oxides, eg. As poly-2,6-dimethyl-1, 4-phenylene oxides, sulfonated polyphenylene sulfides, sulfonated phenol-formaldehyde resins (linear or branched), sulfonated polystyrenes (linear or branched), sulfonated polyphenylenes and other sulfonated aromatic polymers. The sulfonated aromatic polymers may be partially or completely fluorinated. Other sulfonated polymers include polyvinylsulfonic acids, copolymers composed of acrylonitrile and 2-acrylamido-2-methyl-1-propanesulfonic acids, acrylonitrile and vinylsulfonic acids, acrylonitrile and styrenesulfonic acids, acrylonitrile and methacryloxyethylenoxypropanesulfonic acids, acrylonitrile and methacryloxyethyleneoxytetrafluoroethylenesulfonic acids, etc. The polymers can again be partially or completely fluorinated. Other groups of suitable sulfonated polymers include sulfonated polyphosphazenes such as poly (sulfophenoxy) phosphazenes or poly (sulfoethoxy) phosphenes. The polyphosphazene polymers may be partially or fully fluorinated. Sulfonated polyphenylsiloxanes and copolymers thereof, poly (sulfoalkoxy) phosphazenes, poly (sulfotetrafluoroethoxypropoxy) siloxanes are also suitable.

Examples of suitable carboxylic acid group-containing polymers include polyacrylic acid, polymethacrylic acid and any copolymers thereof. Suitable polymers are, for. B. copolymers with vinylimidazole or acrylonitrile. The polymers may in turn be partially or fully fluorinated.

Suitable polymers containing phosphonic acid groups are, for. Polyvinylphosphonic acid, polybenzimidazole phosphonic acid, phosphonated polyphenylene oxides, e.g. For example, poly-2,6-dimethyl-phenylene oxides, etc. The polymers may be partially or completely fluorinated.

In addition to cation-conducting, d. H. acidic, polymers are also anionic, d. H. basic, polymers conceivable, but the proportion of acidic ionomers must predominate. These carry, for example, tertiary amine groups or quaternary ammonium groups. Examples of such polymers are disclosed in US-A 6,183,914; JP-A 11273695 and Slade et al., J. Mater. Chem. 13 (2003), 712-721.

Furthermore, acid-base blends are suitable as ionomers, as described, for. In WO 99/54389 and WO 00/09588. These are generally polymer blends comprising a sulfonic acid group-containing polymer and a polymer having primary, secondary or tertiary amino groups as disclosed in WO 99/54389 or polymer blends prepared by blending polymers containing basic groups in the side chain contained with sulfonate, phosphonate or carboxylate groups, in the acid or salt form, containing polymers. Suitable sulfonate, phosphonate or carboxylate-containing polymers are mentioned above, see sulfonic acid, carboxylic acid or phosphonic acid-containing polymers. Polymers containing basic groups in the side chain are those polymers obtained by side-chain modification of organometallic-deprotonatable engineering-aryl backbone polymers having arylene-containing N-basic groups, wherein tertiary basic nitrogen groups, e.g. B. tertiary amine or basic nitrogen-containing heterocyclic aromatic compounds such as pyridine, pyrimidine, triazine, imidazole, pyrazole, Triazole, thiazole, oxazole, etc. containing aromatic ketones and aldehydes and the metalated polymer. In this case, the metal alkoxide formed as an intermediate compound can either be protonated with water in a further step or be etherified with haloalkanes (W00 / 09588).

The above-mentioned ionomers may be further crosslinked. suitable

Crosslinking reagents are z. B. Epoxidvernetzer such as the commercially available Decanole®. Suitable solvents in which the crosslinking can be carried out can be chosen inter alia as a function of the crosslinking reagent and the ionomers used. Suitable among others are aprotic solvents such as DMAc (N, N-dimethylacetamide), DMF (dimethylformamide), NMP (N-methylpyrrolidone) or mixtures thereof. Suitable crosslinking processes are known to the person skilled in the art. Preferred ionomers are the aforementioned sulfonic acid group-containing polymers. Particular preference is given to perfluorinated sulfonated hydrocarbons such as Nafion®, sulfonated aromatic polyether ether ketones (sPEEK), sulfonated polyether ether sulfones (sPES), sulfonated polyetherimides, sulfonated polybenzimidazoles, sulfonated polyether sulfones and mixtures of the polymers mentioned. Particularly preferred are perfluorinated sulfonated hydrocarbons such as Nafion® and sulfonated polyetheretherketones (sPEEK). These can be used alone or in mixtures with other ionomers. It is also possible to use copolymers which contain blocks of the abovementioned polymers, preferably polymers containing sulfonic acid groups. An example of such a block copolymer is sPEEK-PAMD.

The degree of functionalization of the ionomers, the sulfonic acid, carboxylic acid and / or

Containing phosphonic acid groups is generally 0 to 100%, preferably 0.1 to 100%, more preferably 30 to 70%, particularly preferably 40 to 60%. Sulfonated polyetheretherketones used with particular preference have degrees of sulfonation of from 0 to 100%, more preferably from 0.1 to 100%, even more preferably from 30 to 70%, particularly preferably from 40 to 60%. This is understood to mean a sulfonation of 100% or a functionalization of 100%, ie. H. Each repeating unit of the polymer contains a functional group, in particular a sulfonic acid group.

In the ink according to the invention, the polyazoles described with respect to the membrane materials may also be present as ionomers. The abovementioned ionomers can be used alone or in mixtures in the catalyst inks according to the invention. Mixtures may be used which contain further polymers in addition to the at least one ionomer or other additives, e.g. As inorganic materials, catalysts or stabilizers.

Preparation processes for the ion-conducting polymers described as ionomers are known to the person skilled in the art. Suitable preparation processes for sulfonated polyaryletherketones are, for. In EP-A 0 574 791 and WO 2004/076530.

Some of the said ion-conducting polymers (ionomers) are commercially available, for. Nafion® from E.I. Dupont. Other suitable commercially available materials that can be used as ionomers are perfluorinated and / or partially fluorinated polymers such as "Dow Experimental Membrane" (Dow Chemicals USA), Aciplex® (Asahi Chemicals, Japan), Raipure R-1010 (PaII Rai Manufacturing Co., USA), Flemion (Asahi Glas, Japan) and Raymion® (Chlorin Engineering Cop., Japan). The at least one ionomer is generally present in the catalyst ink of the invention in an amount of 0.5 to 4 parts by weight, preferably 1 to 3 In addition to the components mentioned, the catalyst ink according to the invention may contain further additives, for example wetting agents, flow control agents, defoamers, pore formers, stabilizers, pH adjuvants and the like. Modifiers and other substances.

Furthermore, the catalyst ink according to the invention preferably contains at least one electron conductor component with at least one electron conductor. Suitable electron conductors are known to the person skilled in the art. In general, the electron conductor is electrically conductive carbon particles. As electrically conductive carbon particles, it is possible to use all carbon materials with high electrical conductivity and high surface area which are known in the field of fuel or electrolysis cells. Preferably, carbon blacks, graphite, carbon nanotubes or activated carbons are used.

The present invention also relates to a process for the preparation of the catalyst ink according to the invention by mixing at least one catalytically active material and at least one ionic liquid.

In a preferred embodiment of this process, a catalyst ink containing at least one ionomer, at least one organic solvent and / or water and at least one ionic liquid is mixed with at least one catalytically active material. This mixing can be carried out by any of the methods known to the person skilled in the art, for example in apparatuses known to the person skilled in the art, for example stirred reactors, Kugelschüttel mixers or continuous mixing devices, optionally with the use of ultrasound. The mixing is carried out according to the invention at a temperature at which the processability of the individual component is given, and the ionic liquid is present in liquid form or in dissolved form in a solvent. Suitable solvents are mentioned above. Suitable temperatures are, for example, 0 to 150 ^° C., preferably 20 to 120 ^° C. The process according to the invention for preparing the catalyst ink according to the invention can be carried out at any pressure at which the present components can be processed; above all, the process according to the invention is carried out at one pressure in which the ionic liquid is liquid, for example 1 bar to 10 bar, preferably 1 to 5 bar.

The weight ratio of catalytically active material to at least one ionomer to at least one organic solvent and / or water is 0.5 to 1.5: 1.5 to 2.5: 0.5 to 4, preferably 0.8 to 1.2 : 1, 8 to 2.2: 0.8 to 3.2, more preferably 1: 2: 1 to 3. To this mixture containing catalytically active material, ionomer and organic solvent and / or water are then 0.01 to 1 Parts by weight of ionic liquid, preferably 0.05 to 0.8 parts by weight of ionic liquid, in each case based on the mixture containing catalytically active material, ionomer and organic solvent and / or water added.

Furthermore, the catalyst ink of the invention may contain at least one binder. This binder is selected, for example, from fluorine-containing polymers, for example polytetrafluoroethylene, poly (fluoroethylene propylene), polyvinylidene fluoride (PVdF) or mixtures thereof. In general, the weight ratio of catalytically active substance to binder is 10: 1 to 1:10, preferably 8: 1 to 1: 8, more preferably 7: 2 to 2: 7, for example 6: 2 to 6: 4.

Furthermore, the present invention also relates to a method for producing a membrane-electrode assembly (MEA) comprising at least one membrane, at least one electrode and optionally at least one gas diffusion layer, by applying the catalyst ink of the invention to a membrane or by applying the catalyst ink according to the invention on the optionally existing gas diffusion layer. The membrane is generally constructed of any materials known to those skilled in the art, for example the ionomers already mentioned above. These membranes are suitable for fuel cells with an operating temperature of up to 100 ⁰ C. Suitable membranes for use in fuel cells at temperatures above 100 ⁰ C to 200 ⁰ C, for example, known to the person skilled in membranes based on polyazoles and H ₃ PO _4, for example described in EP 1379573, EP 1427517, EP 1 379 573 and EP 1 425 336. The polymers based on polyazole contain recurring azole units of the general formula (I) and / or (II)

wherein

Ar are the same or different and are a four-membered aromatic or heteroaromatic, mono- or polynuclear group, Ar ^{1 are} identical or different and is a divalent aromatic or heteroaromatic, mononuclear or polynuclear group,

Ar ^{2 are the} same or different and is a two or trivalent aromatic or heteroaromatic, mono- or polynuclear group and

X is the same or different and is oxygen, sulfur or an amino group carrying a hydrogen atom, a 1-20 carbon atom group, preferably a branched or unbranched alkyl or alkoxy group, or an aryl group as another moiety.

Preferred aromatic or heteroaromatic groups are derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenylsulfone, quinoline, pyridine, bipyridine, anthracene and phenanthrene, which may optionally also be substituted.

In this case, the substitution pattern of Ar ^{1 is} arbitrary, in the case of phenylene, for example, Ar ¹ may be ortho, meta and para-phenylene. Particularly preferred groups are derived from benzene and biphenylene, which may optionally also be substituted.

Preferred alkyl groups are short chain alkyl groups of 1 to 4 carbon atoms, e.g. For example, methyl, ethyl, n- or i-propyl and t-butyl groups.

Preferred aromatic groups are phenyl or naphthyl groups. The alkyl groups and the aromatic groups may be substituted. Preferred substituents are halogen atoms such as. As fluorine, amino groups or short-chain alkyl groups such as. For example, methyl or ethyl groups.

Preference is given to polyazoles having repeating units of the formula (I) in which the radicals X within a repeating unit are identical.

In principle, the polyazoles can also have different recurring units which differ, for example, in their radical X. Preferably, however, it has only the same X radicals in a repeating unit.

In a further embodiment of the present invention, the polymer containing recurring azole units is a copolymer containing at least two units of formula (I) and / or (II) which differ from each other.

In a particularly preferred embodiment of the present invention, the polymer containing recurring azole units is a polyazole which contains only units of the formula (I) and / or (II).

The number of recurring azole units in the polymer is preferably an integer greater than or equal to 10. Particularly preferred polymers contain at least 100 recurring azole units.

In the context of the present invention, polymers containing recurring benzimidazole units are preferred. The preferred polyazoles, but especially the polybenzimidazoles are characterized by a high molecular weight. Measured as intrinsic viscosity, this is at least 0.2 dl / g, preferably 0.2 to 3 dl / g.

Further preferred polyazole polymers are polyimidazoles, polybenzothiazoles, polybenzoxazoles, polyoxadiazoles, polyquinoxalines, polythiadiazoles poly (pyridines), poly (pyrimidines), and poly (tetrazapyrene).

The preparation of such polybenzimidazoles (PBI) is carried out according to EP 1 379 573 usually by reacting, for example, 3,3 ', 4,4'-tetraaminobiphenyl with isophthalic acid or diphenyl-isophthalic acid or their esters in the melt. The resulting prepolymer solidifies in the reactor and is then mechanically comminuted. Subsequently, the powdery prepolymer is polymerized in a solid phase polymerization at temperatures of up to 400 ° C and the desired Polybenzimidazole obtained. To produce polymer films, the PBI is dissolved in a further step in polar, aprotic solvents, such as, for example, dimethylacetamide (DMAc), and a film is produced by means of processes known to the person skilled in the art. For use in a fuel cell the ability to lonen- line of this membrane by soaking in H3PO ₄ must be established. If the catalyst ink according to the invention is first applied to a suitable polymer electrolyte membrane, a so-called CCM (catalyst-coated membrane) is obtained, which after application of at least one gas diffusion layer GDL yields an MEA. It is also possible according to the invention that the catalyst ink is applied to at least one gas diffusion layer GDL, whereby a gas diffusion electrode (GDE) is obtained, which results in an MEA after application of a membrane. Methods for combining the individual layers are known to the person skilled in the art, for example hot pressing or gluing.

In general, the catalyst ink according to the invention in homogeneously dispersed

Form applied to the ion-conducting polymer electrolyte membrane or gas diffusion layer for the preparation of an MEA. To produce a homogeneously dispersed ink, known auxiliaries can be used, for example high-speed stirrers, ultrasound and / or ball mills.

The homogenized ink can then be applied by various techniques to an ion-conducting polymer electrolyte membrane, for example, printing, spraying, doctoring, rolling, brushing and brushing, screen printing, inkjet printing, etc.

By applying the catalyst ink of the present invention, at least a portion of the present ionic liquid is trapped in the pores of the polymer electrolyte membrane. In a preferred embodiment, the method according to the invention for producing an MEA comprises immersing the coated polymer electrolyte membrane in an aqueous bath, preferably in water or in dilute acid, for example dilute H ₂ SO ₄ or diluted HNO 3, with a concentration of, for example, 0.2 to 1, 2 molT ¹ , preferably 0.5 or 1, 0 moH ^"1 , at a temperature of RT to 100 ⁰ C, preferably 60 to 100 ⁰ C, particularly preferably 80 ⁰ C. In this immersion, the ionic liquid is largely For example, to more than 90% by weight, the undepleted ionic liquid then contributes to the ionic conductivity of the finished MEA.

In a preferred embodiment, after applying the catalyst ink of the invention, the thus-coated polymer electrolyte membrane is annealed examples game, at room temperature, that is 25 ⁰ C to 100 ⁰ C. In the case of a GDE, the temperature may be even room temperature to 200 ⁰ C.

The present invention therefore also relates to the use of the catalyst ink of the invention in the manufacture of a membrane-electrode assembly (MEA), a catalyst-coated membrane (CCM) or a gas diffusion electrode (GDE).

The present invention also relates to the use of an ionic liquid for the preparation of a catalyst ink. In the methods and uses of the invention, reference is made to the preferred embodiments with respect to the catalyst ink of the invention.

The present invention will be described by the following examples.

Examples: Example 1: Catalyst with ionic liquid (IL) (EMIMEtOSO3)

One part by weight of catalyst (PtRu / C, Pt: 42 wt .-%, Ru: 32 wt .-%) is stirred with 50 parts by weight EMIMEtOSO3 at room temperature and then filtered with suction. The sample is thoroughly washed several times with DI water and filtered with suction. The sample dried at 40 ^° C. in vacuo overnight is then analyzed for N and S. The results are summarized in Table 1.

Table 1: Result of N and S analysis:

Example 2: Preparation of the anode ink without IL

Two parts by weight of Nafion ionomer in H ₂ O (10% strength by weight) (EW1 100, from DuPont) and one part by weight of dimethylacetamide (DMAc) are introduced into a glass bottle and stirred up with the magnetic stirrer. Then one part by weight of catalyst (PtRu / C, Pt: 42 wt .-%, Ru: 32 wt .-%) is weighed and slowly added to the mixture with stirring. The mixture is stirred for about 5 to 10 minutes at room temperature with the magnetic stirrer. The sample is then treated with ultrasound until the value of the registered energy is 0.015 KWh. This value refers to a batch size of 20 g.

Example 3: Preparation of the anode ink with IL (EMIMEtOSO3)

Two parts by weight of Nafion ionomer in H ₂ O (10% strength by weight) (EW1 100, from DuPont), two parts by weight of dimethylacetamide (DMAc) and x (x = 0.1, 0.25, 0.5) parts by weight EMI-MEtOSO3 are placed in a glass bottle and stirred with the magnetic stirrer. Then a portion of catalyst (PtRu / C, Pt: 42 wt .-%, Ru: 32 wt .-%) is weighed and slowly added to the mixture with stirring. The mixture is stirred for about 5 to 10 minutes at room temperature with the magnetic stirrer. The sample is then treated with ultrasound until the value of the registered energy is 0.015 KWh. This value refers to a batch size of 20 g. Example 4: Preparation of the cathode ink

One part by weight of catalyst (Pt / C Pt: 70% by weight), two parts by weight of Nafion and three parts by weight of water are weighed in a glass bottle. After that, Fox grinding beads (1 to 1, 2 mm) are added to the batch and shaken well by hand. The weight of the grinding beads corresponds to half of the total batch. The ink is dispersed for 60 minutes on the Kugelschüttelmischer (Skandex) at level 3. The ink is separated from the grinding beads by sieving. Then, five parts by weight of n-propanol (based on the amount to be filtered off) are added with stirring and the batch is stirred on a magnetic stirrer for 10 minutes at 500 rpm. touched.

Example 5: Preparation and Cell Measurement of CCM Catalyst-coated membranes (CCM) are prepared by screen printing from the anode side with the anode ink and by spraying from the cathode side with the cathode ink. The sPEEK membranes used (degree of sulfonation = 43%) are present in the Na salt form. The active area is 25 cm ² . The CCM are then activated in 0.5 molar HNO ₃ at 55 ⁰ C for two hours. The samples are then dried at room temperature.

For the cell tests with the CCM thus produced, gas diffusion layers of the type 21 BA from the company SGL and on the cathode side H2315 1X11 from the company Freudenberg are used on the anode side. The samples are the stoichiometry tested 3 (min. 49 ml / h), the cathode stoichiometry 3 (min. 130 ml / min of air) at 70 ⁰ C, 1 M MeOH, anodes. The performances of the samples at 0.3 A / cm ² are compared in Table 2.

Table 2: Performance of the samples at 0.3 A / cm ²

Claims

claims

A catalyst ink containing at least one catalytically active material and at least one ionic liquid.

2. catalyst ink according to claim 1, characterized in that the at least one catalytically active material at least one catalytically active metal is selected from the group consisting of platinum, palladium, iridium, rhodium, ruthenium and mixtures thereof.

3. catalyst ink according to claim 1 or 2, characterized in that the melting point of the at least one ionic liquid at -50 ⁰ C to 150 ⁰ C.

4. catalyst ink according to one of claims 1 to 3, characterized in that the at least one ionic liquid is liquid at room temperature.

5. Catalyst ink according to one of claims 1 to 4, characterized in that the at least one ionic liquid is 1-ethyl-2,3-dimethylimidazolium ethylsulfat.

6. catalyst ink according to any one of claims 1 to 5, characterized in that additionally at least one organic solvent and / or water is present.

7. Catalyst ink according to claim 6, characterized in that the at least one organic solvent is selected from the group consisting of monohydric and polyhydric alcohols, nitrogen-containing polar solvents, glycols, glycol ether glycols, glycol ethers and mixtures thereof.

8. A process for preparing a catalyst ink according to any one of claims 1 to 7 by mixing at least one catalytically active material and at least one ionic liquid.

9. A process for producing a membrane-electrode assembly (MEA) comprising at least one membrane and at least one electrode, by applying a catalyst ink according to any one of claims 1 to 7 on a membrane or by applying a catalyst ink according to any one of claims 1 to 7 on the optionally existing gas diffusion layer.

10. Use of a catalyst ink according to any one of claims 1 to 7 in the manufacture of a membrane-electrode assembly (MEA), a catalyst-coated membrane (CCM) or a gas diffusion electrode (GDE).

11. Use of an ionic liquid for the preparation of a catalyst ink.