It is preferred that in the mixture obtained in (6), the molar ratio of the one or more surfactants to the transition metal in the nanoparticles calculated as the element is comprised in the range of from 2 to 6, more preferably of from 2.5 to 5, more preferably of from 3 to 4.5, more preferably of from 3.3 to 4, and more preferably of from 3.5 to 3.7.

It is preferred that separation of the excess surfactant in (6) is achieved by centrifugation and/or filtration, more preferably by filtration, more preferably by membrane filtration, more preferably by nanofiltration, and more preferably by dialysis.

It is preferred that in (5) the mixture is heated for a duration in the range of from 0.05 to 24 h, more preferably from 0.1 to 12 h, more preferably from 0.25 to 6 h, more preferably from 0.5 to 4 h, more preferably from 1 to 3 h, and more preferably from 1.5 to 2.5 h.

It is preferred that in (5) the mixture is heated to a temperature in the range of from 70 to 95° C., more preferably of from 75 to 90° C., and more preferably of from 80 to 85° C.

It is preferred that in (4) the pH is adjusted to a pH in the range of from 2.5 to 7.5, more preferably of from 3 to 7, more preferably of from 3.5 to 6.5, more preferably of from 4 to 6, and more preferably of from 4.5 to 5.5.

It is preferred that the transition metal of the one or more transition metal salts in (2) is selected from the group consisting of Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, Au, and mixtures of two or more thereof, more preferably from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, and mixtures of two or more thereof, more preferably from the group consisting of Pd, Pt, Au, Ag, and mixtures of two or more thereof, wherein more preferably the transition metal of the one or more transition metal salts in (2) comprises Pd or Pd and Au, wherein more preferably the transition metal of the one or more transition metal salts in (2) is Pd or Pd and Au, preferably Pd.

It is preferred that the counterion of the one or more transition metal salts in (2) is selected from the group consisting of halides, hydroxide, nitrate, phosphate, sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, bromide, hydroxide, nitrate, sulfate, and combinations of two or more thereof. It is particularly preferred that the counterion is chloride and/or nitrate, more preferably chloride.

In the case where the counterion of the one or more transition metal salts in (2) is selected from the group consisting of halides, hydroxide, nitrate, phosphate, sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, bromide, hydroxide, nitrate, sulfate, and combinations of two or more thereof, wherein more preferably the counterion is chloride and/or nitrate, preferably chloride, it is preferred that the one or more transition metal salts in (2) are provided as a halide complex, more preferably as a chloride complex, and more preferably as a tetrachloro complex, wherein the counterion of the complex is preferably selected from the group consisting of H⁺, alkali metals, alkaline earth metals, ammonium, and combinations of two or more thereof, more preferably from the group consisting of Na⁺, K⁺, H⁺, and combinations of two or more thereof, wherein more preferably the counterion is Na⁺ and/or H⁺, preferably Na⁺.

It is preferred that independently from one another, the solvent system in (1) and (2) comprises one or more polar solvents, more preferably one or more polar protic solvents, more preferably one or more polar protic solvents selected from the group consisting of C1-C4 alcohols, water, and mixtures of two or more thereof, more preferably from the group consisting of n-propanol, isopropanol, methanol, ethanol, water, and mixtures of two or more thereof, more preferably from the group consisting of methanol, ethanol, water, and mixtures of two or more thereof, wherein more preferably the solvent system comprises ethanol and/or water, preferably water, wherein more preferably the solvent system is ethanol and/or water, preferably water.

It is preferred that the one or more surfactants in (1) are selected from the group consisting of ionic and nonionic surfactants, including mixtures thereof, more preferably from the group consisting of ionic surfactants.

In the case where the one or more surfactants in (1) are selected from the group consisting of ionic surfactants, it is preferred that the one or more ionic surfactants comprise one or more cationic surfactants, more preferably one or more cationic surfactants selected from the group consisting of tetraalkylammonium compounds, including mixtures of two or more thereof, wherein more preferably the cationic surfactants comprise one or more hydroxyl group containing tetraalkylammonium compounds, preferably one or more tetraalkylammonium compounds containing R¹R²R³N⁺R⁴OH, wherein R¹stands for C10-C20 alkyl, preferably for C12-C19 alkyl, more preferably for C14-C18 alkyl, more preferably for C15-C17 alkyl, and more preferably for C16 alkyl,

- wherein independently from one another, R²and R³stands for C1-C5 alkyl, preferably for C1-C4 alkyl, more preferably for C1-C3 alkyl, more preferably for C1-C2 alkyl, and more preferably for C1 alkyl, and
- R⁴stands for C1-C6 alkylene, preferably for C1-C5 alkylene, more preferably for C2-C4 alkylene, more preferably for C2-C3 alkylene, and more preferably for C2 alkylene, wherein more preferably the one or more cationic surfactants comprise a hexadecyl(2-hydroxyethyl)dimethyl ammonium containing compound,
- wherein the counterion is preferably selected from the group consisting of halides, carbonates, hydroxide, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, hydrogen sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, fluoride, bromide, hydrogen carbonate, hydroxide, nitrate, hydrogen phosphate, dihydrogen phosphate, hydrogen sulfate, and combinations of two or more thereof, more preferably from the group consisting of hydroxide, nitrate, dihydrogen phosphate, hydrogen sulfate, and combinations of two or more thereof, wherein more preferably the counterion is dihydrogen phosphate,
- wherein more preferably the one or more ionic surfactants comprise hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogen phosphate, wherein more preferably the ionic surfactant is hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogen phosphate.

Further in the case where the one or more surfactants in (1) are selected from the group consisting of ionic and nonionic surfactants, it is preferred that the one or more ionic surfactants comprise one or more cationic surfactants, more preferably one or more cationic surfactants selected from the group consisting of primary, secondary, tertiary, and quaternary ammonium compounds, including mixtures of two or more thereof, wherein more preferably the cationic surfactants comprise one or more quaternary ammonium compounds, preferably selected from the group consisting of salts of (C₈-C₁₈)trimethylammonium, (C₈-C₁₈)pyridinium, benzalkonium, benzethonium, dimethyldioctadecylammonium, cetrimonium, dioctadecyldimethylammonium, and mixtures of two or more thereof, more preferably from the group consisting of salts of cetyltrimethylammonium, dodecyltrimethylammonium, cetylpyridinium, benzalkonium, benzethonium, dimethyldioctadecylammonium, cetrimonium, dioctadecyldimethylammonium, wherein the counterion is preferably selected from the group consisting of halides, carbonates, hydroxide, nitrate, phosphate, sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, fluoride, bromide, hydrogen carbonate, hydroxide, nitrate, sulfate, and combinations of two or more thereof, wherein more preferably the counterion is chloride and/or nitrate, preferably chloride.

Further in the case where the one or more surfactants in (1) are selected from the group consisting of ionic and nonionic surfactants, it is preferred that the one or more ionic surfactants comprise one or more anionic surfactants, more preferably one or more anionic surfactants selected from the group consisting of salts of (C₆-C₁₈)sulfate, (C₆-C₁₈)ethersulfate, (C₆-C₁₈)sulfonate, (C₆-C₁₈)sulfosuccinate (C₆-C₁₈)phosphate, (C₆-C₁₈)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of (C₈-C₁₆)sulfate, (C₈-C₁₆)ethersulfate, (C₈-C₁₆)sulfonate, (C₈-C₁₆)sulfosuccinate, (C₈-C₁₆)phosphate, (C₈-C₁₆)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of (C₁₀-C₁₄)sulfate, (C₁₀-C₁₄)ethersulfate, (C₁₀-C₁₄)sulfonate, (C₈-C₁₄)sulfosuccinate, (C₁₀-C₁₄)phosphate, (C₁₀-C₁₄)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of laurylsulfate, laurylsulfonate, dioctyl sulfosuccinate, laurylphosphate, laurate, and mixtures of two or more thereof, wherein the counterion is preferably selected from the group consisting of H⁺, alkali metals, alkaline earth metals, ammonium, and combinations of two or more thereof, more preferably from the group consisting of H⁺, Li⁺, Na⁺, K⁺, ammonium, and combinations of two or more thereof, more preferably from the group consisting of Na⁺, K⁺, ammonium, and combinations of two or more thereof, wherein even more preferably the counterion is Nat and/or ammonium, preferably Na⁺.

Further in the case where the one or more surfactants in (1) are selected from the group consisting of ionic and nonionic surfactants, it is preferred that the one or more ionic surfactants comprise one or more zwitterionic surfactants, more preferably one or more betaines, wherein more preferably the one or more ionic surfactants comprise cocamidopropylbetaine or alkyldimethylaminoxide.

Further in the case where the one or more surfactants in (1) are selected from the group consisting of ionic and nonionic surfactants, it is preferred that the one or more nonionic surfactants are selected from the group consisting of (C₈-C₂₂)alcohols, (C₆-C₂₀)alcohol ethoxylates with 1 to 8 ethylene oxide units, (C₆-C₂₀)alkyl polyglycosides, polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkyl esters, sorbitan alkyl esters, polyoxyethylene glycol sorbitan alkyl esters, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and mixtures of two or more thereof,

- wherein more preferably the one or more nonionic surfactants are selected from the group consisting of (C₁₄-C₂₀)alcohols, (C₈-C₁₈)alcohol ethoxylates with 2 to 6 ethylene oxide units, (C₈-C₁₈)alkyl polyglycosides, octaethylene glycol monododecyl ether and/or pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, decyl glucoside, lauryl glucoside, myristil glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, preferably triton X100, nonoxynol-9, glyceryl laurate, polyglycerol polyricinoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and mixtures of two or more thereof,
- wherein more preferably the one or more nonionic surfactants are selected from the group consisting of (C₁₆-C₁₈)alcohols, (C₁₆-C₁₈)alcohol ethoxylates with 2 to 6 ethylene oxide units, (C₈-C₁₄)alkyl polyglycosides, preferably cetyl alcohol, stearyl alcohol, oleyl alcohol, and mixtures of two or more thereof, octaethylene glycol monododecyl ether and/or pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, decyl glucoside, lauryl glucoside, myristil glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, nonoxynol-9, glyceryl laurate, polyglycerol polyricinoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan oleate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, Stearyl-EO₂, polyglyceryl-2-dipolyhydroxystearate, polyglyceryl-distearate, C13/15-PEG₃, C13-PEG₂, glyceryl monooleate, C16/18-PEG₂, oleyl-PEG₂, PEG₂₀-sorbitan monooleate, functionalized polyisobutene, C16/18-PEG₉, and mixtures of two or more thereof,
- more preferably from the group consisting of polyglyceryl-2-dipolyhydroxystearate, diglyceryldistearate, triglyceryl-distearate, C13/15-PEG₃, C13-PEG₂, glyceryl monooleate, sorbitan monooleate, polyglycerol-3-polyricinoleate, C16/18-PEG₂, oleyl-PEG₂, PEG₂₀-sorbitan monooleate, functionalized polyisobutene, C16/18-PEG₉, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, and mixtures of two or more thereof,
- more preferably from the group consisting of polyglyceryl-2-dipolyhydroxystearate, diglyceryldistearate, triglyceryl-distearate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, and mixtures of two or more thereof,
- wherein it is even more preferred that the one or more nonionic surfactants comprise polyoxyethylene (10) oleyl ether and/or polyoxyethylene (20) oleyl ether.

It is preferred that the one or more optional coordinating agents in (1) comprise urea and/or ammonia, preferably urea, wherein more preferably the one or more optional coordinating agents consist of urea and/or ammonia, preferably of urea.

It is preferred that in the mixture obtained in (3), the molar ratio of the one or more coordinating agents to the transition metal in the nanoparticles calculated as the element is comprised in the range of from 0.01 to 2, more preferably of from 0.05 to 1, more preferably of from 0.1 to 0.7, more preferably of from 0.15 to 0.5, more preferably of from 0.2 to 0.45, more preferably of from 0.25 to 0.4, and more preferably of from 0.3 to 0.35.

It is preferred that the support material in (7) comprises carbon and/or a metal oxide and/or a metalloid oxide, more preferably activated carbon and/or an oxide selected from the group consisting of oxides of Si, Al, Ti, Zr, Hf, La, Ce, Pr, Nd, and mixtures and/or mixed oxides of two or more thereof, more preferably from the group consisting of oxides of Si, Al, Ti, Zr, and mixtures and/or mixed oxides of two or more thereof, wherein more preferably the support material is selected from the group consisting of activated carbon, silica, alumina, silica-alumina, aluminosilicates, titanosilicates, and mixtures of two or more thereof, wherein more preferably the support material comprises activated carbon and/or silicalite, preferably silicalite, wherein more preferably the support material consists of activated carbon and/or silicalite, preferably of silicalite.

It is preferred that the support material in (7) is a particulate material, wherein prior to contacting in (7), the particulate material more preferably displays an weight-based average particle size D50 in the range of from 10 to 800 μm, more preferably of from 20 to 500 μm, more preferably of from 40 to 350 μm, more preferably of from 60 to 250 μm, more preferably of from 80 to 200 μm, more preferably of from 100 to 180 μm, more preferably of from 120 to 160 μm, and more preferably of from 130 to 150 μm, wherein preferably the average particle size distribution is determined according to ISO 13320-1, and the weight-based average particle size D50 is calculated according to ISO 9276-2:2001.

It is preferred that the support material in (7) is a monolith substrate and/or is in the form of granules.

It is preferred that prior to contacting in (7), the support material has a BET surface area in the range of from 50 to 800 m²/g, more preferably of from 80 to 600 m²/g, more preferably of from 100 to 500 m²/g, more preferably of from 120 to 450 m²/g, more preferably of from 140 to 300 m²/g, more preferably of from 160 to 250 m²/g, and more preferably of from 180 to 220 m²/g, wherein preferably the surface area is determined according to ISO 9277:2010.

Further, the present invention relates to a catalyst comprising transition metal nanoparticles, stabilizing ligands, and a support material, wherein the stabilizing ligands are adsorbed on the surface of the transition metal nanoparticles such as to form stabilized transition metal nanoparticles, wherein the stabilized transition metal nanoparticles are supported on the support material, wherein the catalyst is obtainable and/or obtained by the process according to any of the embodiments disclosed herein.

Yet further, the present invention relates to a use of a catalyst according to any one of the embodiments disclosed herein as a hydrogenation catalyst, preferably as a hydrogenation catalyst in the production of hydrogen peroxide, and more preferably as a hydrogenation catalyst in the anthraquinone process for the production of hydrogen peroxide.

The unit bar (abs) refers to an absolute pressure of 105 Pa and the unit Angstrom refers to a length of 10⁻¹⁰m.

The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as “any one of embodiments (1) to (4)”, every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to “any one of embodiments (1), (2), (3), and (4)”.

Further, it is explicitly noted that the following set of embodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and preferred aspects of the present invention.

According to an embodiment (1), the present invention relates to a catalyst comprising transition metal nanoparticles, stabilizing ligands, and a support material, wherein at least a portion of the stabilizing ligands are adsorbed on the surface of the transition metal nanoparticles such as to form stabilized transition metal nanoparticles, wherein the stabilized transition metal nanoparticles are supported on the support material, wherein the catalyst displays a molar ratio of the stabilizing ligands to the transition metal in the nanoparticles calculated as the element, wherein the molar ratio is comprised in the range of from 0.1 to 25, preferably of from 0.5 to 15, more preferably of from 1 to 10, more preferably of from 2 to 5, more preferably of from 3 to 4.5, more preferably of from 3.3 to 4, and more preferably of from 3.5 to 3.7.

A preferred embodiment (2) concretizing embodiment (1) relates to said catalyst, wherein the number-based average particle size D50 of the transition metal nanoparticles is in the range of from 0.2 to 20 nm, more preferably from 0.4 to 10 nm, more preferably from 0.6 to 5 nm, more preferably from 0.8 to 4 nm, more preferably from 1 to 3.5 nm, more preferably from 1.2 to 3 nm, more preferably from 1.4 to 2.7 nm, more preferably from 1.6 to 2.5 nm, more preferably from 1.8 to 2.3 nm, and more preferably from 1.9 to 2.1 nm.

A further preferred embodiment (3) concretizing embodiment (1) or (2) relates to said catalyst, wherein the transition metal of the nanoparticles is selected from the group consisting of Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, Au, and alloys of two or more thereof, more preferably from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, and alloys of two or more thereof, and more preferably from the group consisting of Pd, Pt, Au, Ag, and alloys of two or more thereof, wherein more preferably the transition metal of the nanoparticles comprises Pd, Pt, PdAu, PdAg, PtAu, or PtAg, preferably Pd, PdAg, or PdAu, more preferably Pd or PdAu, and more preferably Pd, wherein more preferably the transition metal of the nanoparticles is Pd, Pt, PdAu, PdAg, PtAu, or PtAg, preferably Pd, PdAg, or PdAu, more preferably Pd or PdAu, and more preferably Pd.

A further preferred embodiment (4) concretizing any one of embodiments (1) to (3) relates to said catalyst, wherein the stabilizing ligands comprise one or more surfactants, wherein the one or more surfactants are preferably selected from the group consisting of ionic and nonionic surfactants, including mixtures thereof, preferably from the group consisting of ionic surfactants.

A further preferred embodiment (5) concretizing embodiment (4) relates to said catalyst, wherein the one or more ionic surfactants comprise one or more cationic surfactants, more preferably one or more cationic surfactants selected from the group consisting of tetraalkylammonium compounds, including mixtures of two or more thereof, wherein more preferably the cationic surfactants comprise one or more hydroxyl group containing tetraalkylammonium compounds, preferably one or more tetraalkylammonium compounds containing R¹R²R³N⁺R⁴OH, wherein R¹stands for C10-C20 alkyl, preferably for C12-C19 alkyl, more preferably for C14-C18 alkyl, more preferably for C15-C17 alkyl, and more preferably for C16 alkyl,

- wherein independently from one another, R²and R³stands for C1-C5 alkyl, preferably for C1-C4 alkyl, more preferably for C1-C3 alkyl, more preferably for C1-C2 alkyl, and more preferably for C1 alkyl, and

R⁴stands for C1-C6 alkylene, preferably for C1-C5 alkylene, more preferably for C2-C4 alkylene, more preferably for C2-C3 alkylene, and more preferably for C2 alkylene,

- wherein more preferably the one or more cationic surfactants comprise a hexadecyl(2-hydroxyethyl)dimethyl ammonium containing compound,
- wherein the counterion is preferably selected from the group consisting of halides, carbonates, hydroxide, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, hydrogen sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, fluoride, bromide, hydrogen carbonate, hydroxide, nitrate, hydrogen phosphate, dihydrogen phosphate, hydrogen sulfate, and combinations of two or more thereof, more preferably from the group consisting of hydroxide, nitrate, dihydrogen phosphate, hydrogen sulfate, and combinations of two or more thereof, wherein more preferably the counterion is dihydrogen phosphate,
- wherein more preferably the one or more ionic surfactants comprise hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogen phosphate, wherein more preferably the ionic surfactant is hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogen phosphate.

A further preferred embodiment (6) concretizing embodiment (4) or (5) relates to said catalyst, wherein the one or more ionic surfactants comprise one or more cationic surfactants, more preferably one or more cationic surfactants selected from the group consisting of primary, secondary, tertiary, and quaternary ammonium compounds, including mixtures of two or more thereof, wherein more preferably the cationic surfactants comprise one or more quaternary ammonium compounds, preferably selected from the group consisting of salts of (C₈-C₁₈)trimethylammonium, (C₈-C₁₈)pyridinium, benzalkonium, benzethonium, dimethyldioctadecylammonium, cetrimonium, dioctadecyldimethylammonium, and mixtures of two or more thereof, more preferably from the group consisting of salts of cetyltrimethylammonium, dodecyltrimethylammonium, cetylpyridinium, benzalkonium, benzethonium, dimethyldioctadecylammonium, cetrimonium, dioctadecyldimethylammonium, wherein the counterion is preferably selected from the group consisting of halides, carbonates, hydroxide, nitrate, phosphate, sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, fluoride, bromide, hydrogen carbonate, hydroxide, nitrate, sulfate, and combinations of two or more thereof, wherein more preferably the counterion is chloride and/or nitrate, preferably chloride.

A further preferred embodiment (7) concretizing any one of embodiments (4) to (6) relates to said catalyst, wherein the one or more ionic surfactants comprise one or more anionic surfactants, more preferably one or more anionic surfactants selected from the group consisting of salts of (C₆-C₁₈)sulfate, (C₆-C₁₈)ethersulfate, (C₆-C₁₈)sulfonate, (C₆-C₁₈)sulfosuccinate (C₆-C₁₈)phosphate, (C₆-C₁₈)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of (C₈-C₁₆)sulfate, (C₈-C₁₆)ethersulfate, (C₈-C₁₆)sulfonate, (C₈-C₁₆)sulfosuccinate, (C₈-C₁₆)phosphate, (C₈-C₁₆)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of (C₁₀-C₁₄)sulfate, (C₁₀-C₁₄)ethersulfate, (C₁₀-C₁₄)sulfonate, (C₈-C₁₄)sulfosuccinate, (C₁₀-C₁₄)phosphate, (C₁₀-C₁₄)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of laurylsulfate, laurylsulfonate, dioctyl sulfosuccinate, laurylphosphate, laurate, and mixtures of two or more thereof, wherein the counterion is preferably selected from the group consisting of H⁺, alkali metals, alkaline earth metals, ammonium, and combinations of two or more thereof, more preferably from the group consisting of H⁺, Li⁺, Na⁺, K⁺, ammonium, and combinations of two or more thereof, more preferably from the group consisting of Na⁺, K⁺, ammonium, and combinations of two or more thereof, wherein even more preferably the counterion is Na⁺ and/or ammonium, preferably Na⁺.

A further preferred embodiment (8) concretizing any one of embodiments (4) to (7) relates to said catalyst, wherein the one or more ionic surfactants comprise one or more zwitterionic surfactants, more preferably one or more betaines, wherein more preferably the one or more ionic surfactants comprise cocamidopropylbetaine or alkyldimethylaminoxide.

A further preferred embodiment (9) concretizing any one of embodiments (4) to (8) relates to said catalyst, wherein the one or more nonionic surfactants are selected from the group consisting of (C₈-C₂₂)alcohols, (C₆-C₂₀)alcohol ethoxylates with 1 to 8 ethylene oxide units, (C₆-C₂₀)alkyl polyglycosides, polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkyl esters, sorbitan alkyl esters, polyoxyethylene glycol sorbitan alkyl esters, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and mixtures of two or more thereof, wherein more preferably the one or more nonionic surfactants are selected from the group consisting of (C₁₄-C₂₀)alcohols, (C₈-C₁₈)alcohol ethoxylates with 2 to 6 ethylene oxide units, (C₈-C₁₈)alkyl polyglycosides, octaethylene glycol monododecyl ether and/or pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, decyl glucoside, lauryl glucoside, myristil glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, preferably triton X100, nonoxynol-9, glyceryl laurate, polyglycerol polyricinoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and mixtures of two or more thereof,

- wherein more preferably the one or more nonionic surfactants are selected from the group consisting of (C₁₆-C₁₈)alcohols, (C₁₆-C₁₈)alcohol ethoxylates with 2 to 6 ethylene oxide units, (C₈-C₁₄)alkyl polyglycosides, preferably cetyl alcohol, stearyl alcohol, oleyl alcohol, and mixtures of two or more thereof, octaethylene glycol monododecyl ether and/or pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, decyl glucoside, lauryl glucoside, myristil glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, nonoxynol-9, glyceryl laurate, polyglycerol polyricinoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan oleate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, Stearyl-EO₂, polyglyceryl-2-dipolyhydroxystearate, polyglyceryl-distearate, C13/15-PEG₃, C13-PEG₂, glyceryl monooleate, C16/18-PEG₂, oleyl-PEG₂, PEG₂₀-sorbitan monooleate, functionalized polyisobutene, C16/18-PEG₉, and mixtures of two or more thereof,
- more preferably from the group consisting of polyglyceryl-2-dipolyhydroxystearate, diglyceryldistearate, triglyceryl-distearate, C13/15-PEG₃, C13-PEG₂, glyceryl monooleate, sorbitan monooleate, polyglycerol-3-polyricinoleate, C16/18-PEG₂, oleyl-PEG₂, PEG₂₀-sorbitan monooleate, functionalized polyisobutene, C16/18-PEG₉, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, and mixtures of two or more thereof,
- more preferably from the group consisting of polyglyceryl-2-dipolyhydroxystearate, diglyceryldistearate, triglyceryl-distearate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, and mixtures of two or more thereof, wherein it is even more preferred that the one or more nonionic surfactants comprise polyoxyethylene (10) oleyl ether and/or polyoxyethylene (20) oleyl ether.

A further preferred embodiment (10) concretizing any one of embodiments (1) to (9) relates to said catalyst, wherein the stabilizing ligands form a micelle and or a liposome around at least a portion of the respective nanoparticles, more preferably a liposome.

A further preferred embodiment (11) concretizing any one of embodiments (1) to (10) relates to said catalyst, wherein the catalyst comprises from 0.01 to 10 wt.-% of transition metal nanoparticles calculated as the transition metal and based on 100 wt.-% of the support material, more preferably from 0.05 to 6 wt.-%, more preferably from 0.1 to 4 wt.-%, more preferably from 0.3 to 3 wt.-%, more preferably from 0.5 to 2.5 wt.-%, more preferably from 0.6 to 2 wt.-%, more preferably from 0.7 to 1.5 wt.-%, more preferably from 0.8 to 1.3 wt.-%, and more preferably from 0.9 to 1.1 wt.-%.

A further preferred embodiment (12) concretizing any one of embodiments (1) to (11) relates to said catalyst, wherein the support material comprises carbon and/or a metal oxide and/or a metalloid oxide, more preferably activated carbon and/or an oxide selected from the group consisting of oxides of Si, Al, Ti, Zr, Hf, La, Ce, Pr, Nd, and mixtures and/or mixed oxides of two or more thereof, more preferably from the group consisting of oxides of Si, Al, Ti, Zr, and mixtures and/or mixed oxides of two or more thereof, wherein more preferably the support material is selected from the group consisting of activated carbon, silica, alumina, silica-alumina, aluminosilicates, titanosilicates, and mixtures of two or more thereof, wherein more preferably the support material comprises activated carbon and/or aluminosilicate, preferably sodium aluminosilicate, wherein more preferably the support material consists of activated carbon and/or aluminosilicate, preferably of sodium aluminosilicate.

A further preferred embodiment (13) concretizing any one of embodiments (1) to (12) relates to said catalyst, wherein the support material is a particulate material, wherein more preferably the particulate material displays and weight-based average particle size D50 in the range of from 10 to 800 μm, preferably of from 20 to 500 μm, more preferably of from 40 to 350 μm, more preferably of from 60 to 250 μm, more preferably of from 80 to 200 μm, more preferably of from 100 to 180 μm, more preferably of from 120 to 160 μm, and more preferably of from 130 to 150 μm, wherein preferably the particle size distribution is determined according to ISO 13320-1, and the weight-based average particle size D50 is preferably calculated according to ISO 9276-2:2001.

A further preferred embodiment (14) concretizing any one of embodiments (1) to (12) relates to said catalyst, wherein the support material is a monolith substrate and/or is in the form of granules.

A further preferred embodiment (15) concretizing any one of embodiments (1) to (14) relates to said catalyst, wherein the support material has a BET surface area in the range of from 50 to 800 m²/g, more preferably of from 80 to 600 m²/g, more preferably of from 100 to 500 m²/g, more preferably of from 120 to 450 m²/g, more preferably of from 140 to 300 m²/g, more preferably of from 160 to 250 m²/g, and more preferably of from 180 to 220 m²/g, wherein preferably the surface area is determined according to ISO 9277:2010.

An embodiment (16) of the present invention relates to a process for the preparation of a catalyst, preferably of a catalyst according to any one of embodiments (1) to (15), said process comprising

- (1) dissolving one or more surfactants and optionally one or more coordinating agents into a solvent system;
- (2) dissolving one or more transition metal salts into a solvent system;
- (3) mixing the solution obtained in (1) with the solution obtained in (2);
- (4) optionally adjusting the pH of the mixture obtained in (3) to a pH in the range of from 2 to 8;
- (5) heating the mixture obtained in (3) or (4) to a temperature in the range of from 50 to 100° C. for forming stabilized transition metal nanoparticles;
- (6) separating excess surfactant from the mixture obtained in (5);
- (7) contacting the mixture obtained in (6) with a support material for supporting the stabilized transition metal nanoparticles on the support material; wherein in the mixture obtained in (6), the molar ratio of the one or more surfactants to the transition metal in the nanoparticles calculated as the element is preferably comprised in the range of from 1 to 7.

A preferred embodiment (17) concretizing embodiment (16) relates to said process wherein in (6) the molar amount of surfactants in the mixture obtained in (5) is reduced by 20 to 80%, more preferably by 25 to 75%, more preferably by 30 to 70%, more preferably by 35 to 65%, more preferably by 40 to 60%, and more preferably by 45 to 55%.

A further preferred embodiment (18) concretizing embodiment (16) or (17) relates to said process, wherein contacting in (7) is achieved by impregnation, more preferably by incipient wetness impregnation and/or by vacuum impregnation, preferably by vacuum impregnation.

A further preferred embodiment (19) concretizing any one of embodiments (16) to (18) relates to said process, wherein in the mixture obtained in (3), the molar ratio of the one or more surfactants to the transition metal calculated as the element is comprised in the range of from 0.1 to 50, more preferably from 0.3 to 30, more preferably from 0.5 to 20, more preferably from 1 to 15, more preferably from 3 to 12, more preferably from 5 to 10, more preferably from 7 to 8.5, and more preferably from 7.5 to 8.

A further preferred embodiment (20) concretizing any one of embodiments (16) to (19) relates to said process, wherein in the mixture obtained in (6), the molar ratio of the one or more surfactants to the transition metal in the nanoparticles calculated as the element is comprised in the range of from 2 to 6, more preferably of from 2.5 to 5, more preferably of from 3 to 4.5, more preferably of from 3.3 to 4, and more preferably of from 3.5 to 3.7.

A further preferred embodiment (21) concretizing any one of embodiments (16) to (20) relates to said process wherein separation of the excess surfactant in (6) is achieved by centrifugation and/or filtration, more preferably by filtration, more preferably by membrane filtration, more preferably by nanofiltration, and more preferably by dialysis.

A further preferred embodiment (22) concretizing any one of embodiments (16) to (21) relates to said process, wherein in (5) the mixture is heated for a duration in the range of from 0.05 to 24 h, more preferably from 0.1 to 12 h, more preferably from 0.25 to 6 h, more preferably from 0.5 to 4 h, more preferably from 1 to 3 h, and more preferably from 1.5 to 2.5 h.

A further preferred embodiment (23) concretizing any one of embodiments (16) to (22) relates to said process, wherein in (5) the mixture is heated to a temperature in the range of from 70 to 95° C., more preferably of from 75 to 90° C., and more preferably of from 80 to 85° C.

A further preferred embodiment (24) concretizing any one of embodiments (16) to (23) relates to said process, wherein in (4) the pH is adjusted to a pH in the range of from 2.5 to 7.5, more preferably of from 3 to 7, more preferably of from 3.5 to 6.5, more preferably of from 4 to 6, and more preferably of from 4.5 to 5.5.

A further preferred embodiment (25) concretizing any one of embodiments (16) to (24) relates to said process, wherein the transition metal of the one or more transition metal salts in (2) is selected from the group consisting of Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, Au, and mixtures of two or more thereof, more preferably from the group consisting of Pd, Pt, Ru, Rh, Au, Ag, and mixtures of two or more thereof, more preferably from the group consisting of Pd, Pt, Au, Ag, and mixtures of two or more thereof, wherein more preferably the transition metal of the one or more transition metal salts in (2) comprises Pd or Pd and Au, wherein more preferably the transition metal of the one or more transition metal salts in (2) is Pd or Pd and Au, preferably Pd.

A further preferred embodiment (26) concretizing any one of embodiments (16) to (25) relates to said process, wherein the counterion of the one or more transition metal salts in (2) is selected from the group consisting of halides, hydroxide, nitrate, phosphate, sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, bromide, hydroxide, nitrate, sulfate, and combinations of two or more thereof, wherein more preferably the counterion is chloride and/or nitrate, preferably chloride.

A further preferred embodiment (27) concretizing embodiment (26) relates to said process, wherein the one or more transition metal salts in (2) are provided as a halide complex, more preferably as a chloride complex, and more preferably as a tetrachloro complex, wherein the counterion of the complex is preferably selected from the group consisting of H⁺, alkali metals, alkaline earth metals, ammonium, and combinations of two or more thereof, more preferably from the group consisting of Na⁺, K⁺, H⁺, and combinations of two or more thereof, wherein more preferably the counterion is Na⁺ and/or H⁺, preferably Na⁺.

A further preferred embodiment (28) concretizing any one of embodiments (16) to (27) relates to said process, wherein independently from one another, the solvent system in (1) and (2) comprises one or more polar solvents, more preferably one or more polar protic solvents, more preferably one or more polar protic solvents selected from the group consisting of C1-C4 alcohols, water, and mixtures of two or more thereof, more preferably from the group consisting of n-propanol, isopropanol, methanol, ethanol, water, and mixtures of two or more thereof, more preferably from the group consisting of methanol, ethanol, water, and mixtures of two or more thereof, wherein more preferably the solvent system comprises ethanol and/or water, preferably water, wherein more preferably the solvent system is ethanol and/or water, preferably water.

A further preferred embodiment (29) concretizing any one of embodiments (16) to (28) relates to said process, wherein the one or more surfactants in (1) are selected from the group consisting of ionic and nonionic surfactants, including mixtures thereof, more preferably from the group consisting of ionic surfactants.

A further preferred embodiment (30) concretizing embodiment (29) relates to said process, wherein the one or more ionic surfactants comprise one or more cationic surfactants, more preferably one or more cationic surfactants selected from the group consisting of tetraalkylammonium compounds, including mixtures of two or more thereof, wherein more preferably the cationic surfactants comprise one or more hydroxyl group containing tetraalkylammonium compounds, preferably one or more tetraalkylammonium compounds containing R¹R²R³N⁺R⁴OH, wherein R¹stands for C10-C20 alkyl, preferably for C12-C19 alkyl, more preferably for C14-C18 alkyl, more preferably for C15-C17 alkyl, and more preferably for C16 alkyl,

- wherein independently from one another, R²and R³stands for C1-C5 alkyl, preferably for C1-C4 alkyl, more preferably for C1-C3 alkyl, more preferably for C1-C2 alkyl, and more preferably for C1 alkyl, and
- R⁴stands for C1-C6 alkylene, preferably for C1-C5 alkylene, more preferably for C2-C4 alkylene, more preferably for C2-C3 alkylene, and more preferably for C2 alkylene,
- wherein more preferably the one or more cationic surfactants comprise a hexadecyl(2-hydroxyethyl)dimethyl ammonium containing compound,
- wherein the counterion is preferably selected from the group consisting of halides, carbonates, hydroxide, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, hydrogen sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, fluoride, bromide, hydrogen carbonate, hydroxide, nitrate, hydrogen phosphate, dihydrogen phosphate, hydrogen sulfate, and combinations of two or more thereof, more preferably from the group consisting of hydroxide, nitrate, dihydrogen phosphate, hydrogen sulfate, and combinations of two or more thereof, wherein more preferably the counterion is dihydrogen phosphate,
- wherein more preferably the one or more ionic surfactants comprise hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogen phosphate, wherein more preferably the ionic surfactant is hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogen phosphate.

A further preferred embodiment (31) concretizing embodiment (29) or (30) relates to said process, wherein the one or more ionic surfactants comprise one or more cationic surfactants, more preferably one or more cationic surfactants selected from the group consisting of primary, secondary, tertiary, and quaternary ammonium compounds, including mixtures of two or more thereof, wherein more preferably the cationic surfactants comprise one or more quaternary ammonium compounds, preferably selected from the group consisting of salts of (C₈-C₁₈)trimethylammonium, (C₈-C₁₈)pyridinium, benzalkonium, benzethonium, dimethyldioctadecylammonium, cetrimonium, dioctadecyldimethylammonium, and mixtures of two or more thereof, more preferably from the group consisting of salts of cetyltrimethylammonium, dodecyltrimethylammonium, cetylpyridinium, benzalkonium, benzethonium, dimethyldioctadecylammonium, cetrimonium, dioctadecyldimethylammonium, wherein the counterion is preferably selected from the group consisting of halides, carbonates, hydroxide, nitrate, phosphate, sulfate, and combinations of two or more thereof, more preferably from the group consisting of chloride, fluoride, bromide, hydrogen carbonate, hydroxide, nitrate, sulfate, and combinations of two or more thereof, wherein more preferably the counterion is chloride and/or nitrate, preferably chloride.

A further preferred embodiment (32) concretizing any one of embodiments (29) to (31) relates to said process, wherein the one or more ionic surfactants comprise one or more anionic surfactants, more preferably one or more anionic surfactants selected from the group consisting of salts of (C₆-C₁₈)sulfate, (C₆-C₁₈)ethersulfate, (C₆-C₁₈)sulfonate, (C₆-C₁₈)sulfosuccinate (C₆-C₁₈)phosphate, (C₆-C₁₈)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of (C₈-C₁₆)sulfate, (C₈-C₁₆)ethersulfate, (C₈-C₁₆)sulfonate, (C₈-C₁₆)sulfosuccinate, (C₈-C₁₆)phosphate, (C₈-C₁₆)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of (C₁₀-C₁₄)sulfate, (C₁₀-C₁₄)ethersulfate, (C₁₀-C₁₄)sulfonate, (C₈-C₁₄)sulfosuccinate, (C₁₀-C₁₄)phosphate, (C₁₀-C₁₄)carboxylate, and mixtures of two or more thereof, more preferably from the group consisting of salts of laurylsulfate, laurylsulfonate, dioctyl sulfosuccinate, laurylphosphate, laurate, and mixtures of two or more thereof, wherein the counterion is preferably selected from the group consisting of H⁺, alkali metals, alkaline earth metals, ammonium, and combinations of two or more thereof, more preferably from the group consisting of H⁺, Li⁺, Na⁺, K⁺, ammonium, and combinations of two or more thereof, more preferably from the group consisting of Na⁺, K⁺, ammonium, and combinations of two or more thereof, wherein even more preferably the counterion is Nat and/or ammonium, preferably Na⁺.

A further preferred embodiment (33) concretizing any one of embodiments (29) to (32) relates to said process, wherein the one or more ionic surfactants comprise one or more zwitterionic surfactants, more preferably one or more betaines, wherein more preferably the one or more ionic surfactants comprise cocamidopropylbetaine or alkyldimethylaminoxide.

A further preferred embodiment (34) concretizing any one of embodiments (29) to (33) relates to said process, wherein the one or more nonionic surfactants are selected from the group consisting of (C₈-C₂₂)alcohols, (C₆-C₂₀)alcohol ethoxylates with 1 to 8 ethylene oxide units, (C₆-C₂₀)alkyl polyglycosides, polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkyl esters, sorbitan alkyl esters, polyoxyethylene glycol sorbitan alkyl esters, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and mixtures of two or more thereof, wherein more preferably the one or more nonionic surfactants are selected from the group consisting of (C₁₄-C₂₀)alcohols, (C₈-C₁₈)alcohol ethoxylates with 2 to 6 ethylene oxide units, (C₈-C₁₈)alkyl polyglycosides, octaethylene glycol monododecyl ether and/or pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, decyl glucoside, lauryl glucoside, myristil glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, preferably triton X100, nonoxynol-9, glyceryl laurate, polyglycerol polyricinoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and mixtures of two or more thereof,

- wherein more preferably the one or more nonionic surfactants are selected from the group consisting of (C₁₆-C₁₈)alcohols, (C₁₆-C₁₈)alcohol ethoxylates with 2 to 6 ethylene oxide units, (C₈-C₁₄)alkyl polyglycosides, preferably cetyl alcohol, stearyl alcohol, oleyl alcohol, and mixtures of two or more thereof, octaethylene glycol monododecyl ether and/or pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, decyl glucoside, lauryl glucoside, myristil glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, nonoxynol-9, glyceryl laurate, polyglycerol polyricinoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan oleate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, cocamide monoethanolamine, cocamide diethanolamine, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, Stearyl-EO₂, polyglyceryl-2-dipolyhydroxystearate, polyglyceryl-distearate, C13/15-PEG₃, C13-PEG₂, glyceryl monooleate, C16/18-PEG₂, oleyl-PEG₂, PEG₂₀-sorbitan monooleate, functionalized polyisobutene, C16/18-PEG₉, and mixtures of two or more thereof,
- more preferably from the group consisting of polyglyceryl-2-dipolyhydroxystearate, diglyceryldistearate, triglyceryl-distearate, C13/15-PEG₃, C13-PEG₂, glyceryl monooleate, sorbitan monooleate, polyglycerol-3-polyricinoleate, C16/18-PEG₂, oleyl-PEG₂, PEG₂₀-sorbitan monooleate, functionalized polyisobutene, C16/18-PEG₉, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, and mixtures of two or more thereof,
- more preferably from the group consisting of polyglyceryl-2-dipolyhydroxystearate, diglyceryldistearate, triglyceryl-distearate, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, and mixtures of two or more thereof,
- wherein it is even more preferred that the one or more nonionic surfactants comprise polyoxyethylene (10) oleyl ether and/or polyoxyethylene (20) oleyl ether.

A further preferred embodiment (35) concretizing any one of embodiments (16) to (34) relates to said process, wherein the one or more optional coordinating agents in (1) comprise urea and/or ammonia, preferably urea, wherein more preferably the one or more optional coordinating agents consist of urea and/or ammonia, preferably of urea.

A further preferred embodiment (36) concretizing any one of embodiments (16) to (35) relates to said process, wherein in the mixture obtained in (3), the molar ratio of the one or more coordinating agents to the transition metal in the nanoparticles calculated as the element is comprised in the range of from 0.01 to 2, more preferably of from 0.05 to 1, more preferably of from 0.1 to 0.7, more preferably of from 0.15 to 0.5, more preferably of from 0.2 to 0.45, more preferably of from 0.25 to 0.4, and more preferably of from 0.3 to 0.35.

A further preferred embodiment (37) concretizing any one of embodiments (16) to (36) relates to said process, wherein the support material in (7) comprises carbon and/or a metal oxide and/or a metalloid oxide, more preferably activated carbon and/or an oxide selected from the group consisting of oxides of Si, Al, Ti, Zr, Hf, La, Ce, Pr, Nd, and mixtures and/or mixed oxides of two or more thereof, more preferably from the group consisting of oxides of Si, Al, Ti, Zr, and mixtures and/or mixed oxides of two or more thereof, wherein more preferably the support material is selected from the group consisting of activated carbon, silica, alumina, silica-alumina, aluminosilicates, titanosilicates, and mixtures of two or more thereof, wherein more preferably the support material comprises activated carbon and/or silicalite, preferably silicalite, wherein more preferably the support material consists of activated carbon and/or silicalite, preferably of silicalite.