Rhodium sulfides as hydroformylation catalysts

Abstract

The present invention relates to a catalyst comprising rhodium, sulfur and a catalyst support, wherein the average particle size (D50) of the catalyst is in the range of from 100 to 1000µm, as well as to a process for its preparation and to its use.

Description

[0001] Rhodium Sulfides as Hydroformylation Catalysts

[0002] TECHNICAL FIELD

[0003] The present invention relates to process for the preparation of a supported rhodium sulfide catalyst article as well as to a supported rhodium sulfide catalyst particles as such and as obtainable from the inventive process.

[0004] INTRODUCTION

[0005] The hydroformylation of olefins yielding aldehydes is one of the most industrially important homogeneously catalyzed reactions. Aldehydes are easily further converted into many secondary products. Well-known catalysts for the hydroformylation are rhodium and cobalt based catalysts like CO(CO)4H , for a state of the art see for instance “Oxo Synthesis” in Ullmann's Encyclopedia of Industrial Chemistry June 2000 DOI: 10.1002 / 14356007. a18_321 . Recently, heterogeneous rhodium based catalysts gained attention like rhodium phosphides or phosphites (see “Current State of the Art of the Solid Rh-Based Catalyzed Hydroformylation of Short-Chain Olefins” by S. Hanf, L. Alvardo Rupflin, R. Glaser, S. A. Schunk, Catalysts 2020, 10, 1-36, https: / / doi.Org / 10.3390 / catal10050510).

[0006] CN 103691456 B relates to a Rh-Rhi7Si5catalysts and its preparation method, wherein the catalyst comprises carbon black pellets and wherein the rhodium sulfide is supported on the carbon black in the form of nanocrystals which are in the range of from 8 to 10 nm.

[0007] GB 1066579 A relates to a catalysts consisting of Rh2Ss on carbon and wherein the catalyst is used for the alkylation of p-amino diphenylamine with methyl isobutyl ketone in the presence of hydrogen.

[0008] US 4560803 A relates to an improved process for forming ketones from the corresponding olefins by vapor phase oxidation of the olefin in the presence of molecular oxygen and water vapor employing a heterogeneous catalyst comprising rhenium compounds and complexes, optionally containing at least one metal compound or complex selected from the group consisting of Group VI B metals and Group VIII noble metals, and mixtures thereof.

[0009] US 6310261 B1 relates to a method for the production of aldehydes or aldehydes and alcohols by hydroformylation of olefins in the presence of a complexing catalyst homogeneously dissolved in a reaction mixture, containing a metal of Group Villa of the periodic table of the elements and a phosphorus-free, polydentate nitrogen compound suitable for complex formation as ligand. CN 113385205 B relates to a metal phosphide catalyst for catalyzing heterogeneous hydroformylation reaction.

[0010] Although processes exist for the hydroformylation of olefins, there remains the need for optimization of the process in terms of efficiency (specific activity of the catalyst and the reaction conditions play a role in that) - heterogeneous catalysts offer an interesting means for process intensification. Beyond process efficiency items heterogeneous catalyst alternatives are advantageous compared to the homogeneous catalyst candidates that usually they do not require a catalyst separation process and dedicated equipment for that separation. In terms of process efficiency this is advantageous.

[0011] DETAILED DESCRIPTION

[0012] Therefore, it was an object of the first invention to provide a suitable heterogeneous catalyst system with sufficient activity and selectivity, and which is also stable towards deactivation. Surprisingly it was found that materials containing rhodium and sulfur as supported catalysts, in particular rhodium sulfide, preferably as nanoparticles, supported on a particulate oxidic material can be usefully employed in the hydroformylation reaction. Further, it was an object to provide a process for preparation of such a material. Furthermore, it was an object of the first invention to provide a highly active and selective catalyst regarding the hydroformylation of alphaolefins. Surprisingly, it was found that the inventive catalyst according to the first invention allows not only for high activity at lower metal loadings, but also provides high selectivity to target products, low selectivity in undesirable side reactions, and especially a low selectivity towards hydrogenation of double bonds of the olefin reactants.

[0013] Therefore, the first invention relates to a catalyst comprising rhodium, sulfur, preferably one or more rhodium sulfides, and a catalyst support, wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, wherein the particle size is preferably measured according to reference example 4.

[0014] Within the meaning of the first invention, the rhodium sulfide hi7Si5is the rhodium sulfide according to ICSD-410838. Further, the rhodium sulfide RhsS4 is the rhodium sulfide according to ICSD-410813, and the rhodium sulfide Rf^Ss is the rhodium sulfide according to ICSD-56882.

[0015] It is preferred that the one or more rhodium sulfides are selected from the group consisting of RhiySis, RhsS i, and Rf^Ss, and mixtures thereof, preferably from hi7Si5and Rf^Ss, and mixtures thereof, more preferably wherein the one or more rhodium sulfides is RhnSis.

[0016] The first invention further refers to a catalyst comprising one or more crystalline binary RhxAysystems, wherein one or more of the crystalline binary RhxAysystems are located on the surface of the catalyst, wherein said surface of the catalyst comprising one or more of the crystalline binary RhxAysystems comprises a first structure motive according to formula (I) comprising 4 adjacent rhodium atoms Rh(1 ) to Rh(4) in a planar or substantially planar ring arrangement: wherein all of the rhodium atoms Rh(1) to Rh(4) are in the outermost layer of atoms forming the outer surface of the one or more crystalline binary RhxAysystems, wherein the first structure motive comprises a first Rh(1)-Rh(2)-Rh(3) angle in the range of from 55.0 to 65.0°, and a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 105.0 to 120.0, wherein preferably the geometry of the ring arrangement according to formula (I) and the angles of the first structure motive are determined according to reference example 6.

[0017] In the case where the surface of the catalyst comprises one or more of the crystalline binary RhxAy systems comprises a first structure motive according to formula (I), it is preferred that the first structure motive comprises a first Rh(1)-Rh(2)-Rh(3) angle in the range of from 57.0 to 63.0°, preferably from 58.0 to 62.0°, more preferably from 59.0 to 61 .0 °, wherein preferably the first Rh(1 )-Rh(2)-Rh(3) angle of the first structure motive is determined according to reference example 6.

[0018] Yet further, it is preferred that the first structure motive comprises a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 110.0 to 116.0°, preferably from 111 .0 to 115.0°, more preferably from 112.0 to 114.0°, wherein preferably the second Rh(2)-Rh(3)-Rh(4) angle of the first structure motive is determined according to reference example 6.

[0019] Yet further, it is preferred that the ring arrangement of rhodium atoms Rh(1 ) to Rh(4) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(1 ), Rh(2), and Rh(4) and the plane defined by Rh(2), Rh(3), and Rh(4) or the dihedral angle between the plane defined by Rh(1 ), Rh(2), and Rh(3) and the plane defined by Rh(1 ), Rh(3), and Rh(4) deviates from 180° in the range of from -15 to 15°, preferably in the range of from -12 to 12°, wherein preferably the dihedral angles of the first structure motive are determined according to reference example 6.

[0020] Yet further, it is preferred that the first structure motive comprises a first rhodium-rhodium distance Rh(1 )-Rh(2) in the range of from 2.50 to 2.65 A and a second rhodium-rhodium distance Rh(2)-Rh(3) in the range of from 2.70 to 2.90 A, wherein preferably the rhodium-rhodium distances of the first structure motive are determined according to reference example 6.

[0021] In the case where the first structure motive comprises a first rhodium-rhodium distance Rh(1 )- Rh(2) and a second rhodium-rhodium distance, it is preferred that the first rhodium-rhodium distance Rh(1 )-Rh(2) is in the range of from 2.54 to 2.62 A, preferably from 2.55 to 2.61 A, more preferably from 2.56 to 2.60 A, wherein preferably the first rhodium-rhodium distance Rh(1 )- Rh(2) of the first structure motive is determined according to reference example 6.

[0022] Yet further, it is preferred that the second rhodium-rhodium distance Rh(2)-Rh(3) is in the range of from 2.75 to 2.85 A, preferably from 2.76 to 2.84 A, more preferably from 2.77 to 2.83 A, wherein preferably the second rhodium-rhodium distance Rh(2)-Rh(3) of the first structure motive is determined according to reference example 6.

[0023] In the case where the surface of the catalyst comprises one or more of the crystalline binary RhxAy systems comprises a first structure motive according to formula (I), it is preferred that A is selected from the group consisting of N, P, As, Sb, S, O, Se, and mixtures of two or more thereof, preferably selected from the group consisting of P, S and mixtures thereof, more preferably wherein A comprises S, more preferably wherein A is S.

[0024] Yet further, it is preferred that the one or more crystalline binary systems RhxAycomprise, preferably consists of, one or more rhodium sulfides, wherein the one or more rhodium sulfides are selected from the group consisting of Rhi7Si5, RhsS i, and Rf^Ss, and mixtures thereof, preferably from RhiySis and Rf^Ss, and mixtures thereof, more preferably wherein the one or more crystalline binary systems RhxAycomprise hi7Si5, wherein more preferably the one or more crystalline binary systems RhxAyis RhnSis.

[0025] Yet further, it is preferred that the ring arrangement of the first structure motive forms a rhomboid.

[0026] Yet further, it is preferred that the surface is the (100) surface plane of the one or more crystalline binary RhxAysystems.

[0027] Yet further, it is preferred that the first structure motive is comprised in a 3x3x1 supercell.

[0028] In the case where the first structure motive is comprised in a 3x3x1 supercell, it is preferred that the 3x3x1 supercell comprises, preferably consists of, 8 rhodium atoms.

[0029] In the case where the surface of the catalyst comprises one or more of the crystalline binary RhxAysystems comprises a first structure motive according to formula (I), it is preferred that the catalyst further comprises a second structure motive comprising 4 adjacent rhodium atoms Rh(5) to Rh(8) in a planar or substantially planar ring arrangement, according to formula (II): wherein all of the rhodium atoms Rh(1 ) to Rh(8) are in the outermost layer of atoms forming the outer surface of the one or more crystalline binary RhxAysystems comprising the first structure motive in said outermost layer, wherein preferably the geometry of the ring arrangement according to formula (II) is determined according to reference example 6.

[0030] In the case where the catalyst further comprises a second structure motive according to formula (II), it is preferred that the ring arrangement of rhodium atoms Rh(5) to Rh(8) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(5), Rh(6), and Rh(8) and the plane defined by Rh(6), Rh(7), and Rh(8) or between the plane defined by Rh(5), Rh(6), and Rh(7) and the plane defined by Rh(5), Rh(7), and Rh(8) deviates from 180° in the range of from -10 to 10°, preferably in the range of from -6 to 6°, wherein preferably the dihedral angles of the second structure motive are determined according to reference example 6. Yet further, it is preferred that the first structure motive and the second structure motive do not have any rhodium atoms in common. Yet further, it is preferred that the ring arrangement of the second structure motive forms a rhomboid. Yet further, it is preferred that the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)- Rh(8) angle in the range of from 93.0 to 104.0°, wherein preferably the angles of the second structure motive are determined according to reference example 6.

[0031] In the case where the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)-Rh(8) angle in the range of from 93.0 to 104.0°, it is preferred that the first Rh(5)-Rh(6)-Rh(7) angle is in the range of from 78.0 to 85.0°, preferably from 80.0 to 83.0 °, wherein preferably the first Rh(5)-Rh(6)-Rh(7) angle of the second structure motive is determined according to reference example 6. Yet further, it is preferred that the second Rh(6)-Rh(7)-Rh(8) angle is in the range of from 95.0 to 102.0°, preferably from 97.0 to 100.0°, wherein preferably the second Rh(6)-Rh(7)-Rh(8) angle of the second structure motive is determined according to reference example 6.

[0032] In the case where the catalyst further comprises a second structure motive according to formula (II), it is preferred that the second structure motive comprises a first rhodium-rhodium distance Rh(5)-Rh(6) in the range of from 2.48 to 2.58 A, preferably from 2.50 to 2.56 A, more preferably from 2.52 to 2.54 A, and a second rhodium-rhodium distance Rh(6)-Rh(7) in the range of from 2.70 to 3.00 A, preferably from 2.75 to 2.95 A, more preferably from 2.80 to 2.90 A, wherein preferably the rhodium-rhodium distances of the second structure motive are determined according to reference example 6.

[0033] In the case where the surface of the catalyst comprises one or more of the crystalline binary RhxAy systems comprises a first structure motive according to formula (I), it is preferred that the one or more crystalline binary RhxAysystems display a cubic crystal structure, preferably wherein the space group of the unit cell is Pm3m. Yet further, it is preferred that the catalyst further comprises one or more ligands, wherein the one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive, preferably to Rh(1 ) or Rh(3) of the first structure motive. In case where the catalyst further comprises one or more ligands, it is preferred that one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive.

[0034] Yet further, it is preferred that the one or more ligands are selected from the group consisting of anionic ligands, cationic ligands, and neutral ligands.

[0035] Yet further, it is preferred that the ligand is selected from the group consisting of carbon monoxide, nitrogen monoxide, water, and ammonia, preferably selected from the group consisting of carbon monoxide, and nitrogen monoxide, wherein more preferably the one or more ligands are carbon monoxide.

[0036] Yet further, it is preferred that the one or more ligands are selected from the group consisting of nitrogen monoxide, water, and ammonia, wherein preferably the one or more ligands are nitrogen monoxide.

[0037] Alternatively, it is preferred that no ligand is coordinated and / or bonded, preferably bonded, to the first structure motive.

[0038] As a second alternative, it is preferred that the catalyst is substantially free of carbon monoxide, preferably wherein the catalyst is free of carbon monoxide.

[0039] In the case where the surface of the catalyst comprises one or more of the crystalline binary RhxAy systems comprises a first structure motive according to formula (I), it is preferred that the catalyst further comprises a catalyst support.

[0040] It is preferred that the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, wherein the particle size is preferably measured according to reference example 4.

[0041] It is preferred that the catalyst is a heterogeneous catalyst.

[0042] In the case where the catalyst comprises a catalyst support, it is preferred that the catalyst support, preferably a particulate catalyst support, is selected from the group consisting of ZrC>2, AI2O3, SiC>2, TiC>2, La2C>3-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2C>3-doped CeO2-ZrO2 mixed oxide, Nd2C>3-doped CeO2-ZrO2 mixed oxide, Y2Os-doped CeO2-ZrO2 mixed oxide, P^Os-doped CeO2-ZrC>2 mixed oxide, ZrC>2-doped AI2O3, ZrC>2-doped SiC>2, SiC>2-doped AI2O3, and mixtures of two or more thereof, more preferably from the group consisting of ZrC>2, SiC>2, La2O3-doped ZrC>2, CeO2-ZrC>2 mixed oxide, La2C>3-doped CeO2-ZrO2 mixed oxide, Nd2Os-doped CeO2-ZrO2 mixed oxide, Y2Os-doped CeO2-ZrO2 mixed oxide, P^Os-doped CeO2-ZrO2 mixed oxide, ZrC>2- doped SiC>2, and mixtures of two or more thereof, more preferably from the group consisting of SiC>2, ZrC>2-doped SiC>2, and mixtures of two or more thereof. Alternatively, it is preferred that the catalyst support is selected from the group consisting of activated carbon, graphite, carbide, and mixtures of two or more thereof, preferably activated carbon, graphite, silicon carbide, boron carbide, tungsten carbide, and mixtures of two or more thereof.

[0043] As a second alternative, it is preferred that the catalyst support, preferably a porous catalyst support, is selected from the group of metal organic frameworks (MOF) and zeolites, preferably wherein the catalyst support is a zeolite.

[0044] As a third alternative, it is preferred that the catalyst support is a polymer, preferably wherein the polymer is selected from the group consisting of polyolefins, polyamide, polyester, polyacrylate, polyethylene, polyurethane, polyvinylpyrrolidone, polystyrene, and mixtures of two or more thereof, preferably selected from the group consisting of polystyrene, polyethylene, and mixtures of two or more thereof.

[0045] It is preferred that the rhodium content of the catalyst is in the range of from 0.1 to 15 wt.-%, calculated as the element, preferably from 0.2 to 14 wt.-%, more preferably from 0.3 to 13 wt.-%, more preferably from 0.4 to 12 wt.-%, more preferably from 0.5 to 11 wt.-%, more preferably from 0.6 to 10 wt.-%, more preferably from 0.7 to 5 wt.-%, more preferably from 0.8 to 2 wt.-%, more preferably from 0.9 to 1 .5 wt.-%, based on 100 wt.-% of the catalyst.

[0046] In the case where the catalyst comprises one or more rhodium sulfides, it is preferred that independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.1 to 5, preferably from 0.5 to 3, more preferably from 0.6 to 2, more preferably from 0.7 to 1 .8, more preferably from 0.8 to 1 .7. Yet further, it is preferred that independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.5 to 2.0, preferably from 0.7 to 1.1 , more preferably from 0.8 to 1.0, more preferably from 0.85 to 0.95. Yet further, it is preferred that independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 1 to 2.5, preferably from 1 .4 to 1 .9, more preferably from 1 .5 to 1 .8, more preferably from 1 .6 to 1 .7.

[0047] Within the meaning of the first invention, the particle size distribution refers to a volume or number based particle size distribution, preferably to a number based particle size distribution.

[0048] It is preferred that the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, preferably from 0.5 to 8 nm, more preferably from 1 to 6 nm, more preferably from 1 .5 to 5 nm, wherein the particle size is preferably measure according to reference example 4.

[0049] In the case where the catalyst comprises one or more rhodium sulfides, it is preferred that the one or more rhodium sulfides is Rhi7Si5and wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, preferably from 0.5 to 8 nm, more preferably from 1 to 6 nm, more preferably from 1 .5 to 5 nm, wherein the particle size is preferably measure according to reference example 4. In the case where the one or more rhodium sulfide is Rhi7Si5, it is preferred that the particle size distribution D90 of the catalyst is in the range of from 0.1 to 10 nm, preferably from 1 to 5 nm, more preferably from 2 to 4 nm, more preferably from 2.5 to 3.5 nm.

[0050] Alternatively, it is preferred that the particle size distribution D90 of the catalyst is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm.

[0051] As a second alternative, it is preferred that the particle size distribution D90 of the catalyst is in the range of from 1 to 25 nm, preferably from 5 to 20 nm, more preferably from 8 to 14 nm, more preferably from 10 to 12 nm.

[0052] In the case where the one or more rhodium sulfide is Rhi7Si5, it is preferred that the particle size distribution D10 of the catalyst according to (2) is in the range of from 0.5 to 3 nm, preferably from 1 to 2 nm, more preferably from 1 .1 to 1 .9 nm, more preferably from 1 .3 to 1 .7 nm.

[0053] Alternatively, it is preferred that the particle size distribution D10 of the catalyst according to (2) is in the range of from 1 to 3.5 nm, preferably from 1 .5 to 2.5 nm, more preferably from 1 .7 to 2.3 nm, more preferably from 1 .9 to 2.2 nm.

[0054] As a second alternative, it is preferred that the particle size distribution D10 of the catalyst according to (2) is in the range of from 2 to 4.5 nm, preferably from 2.5 to 3.5 nm, more preferably from 2.7 to 3.3 nm, more preferably from 2.9 to 3.1 nm.

[0055] In the case where the catalyst comprises one or more rhodium sulfides, it is preferred that the one or more rhodium sulfides is Rf^Ss and wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, preferably from 2 to 4 nm, more preferably from 2.3 to 3.7 nm, more preferably from 2.5 to 3.5 nm, wherein the particle size is preferably measure according to reference example 4.

[0056] In the case where the one or more rhodium sulfides is Rf^Ss, it is preferred that the particle size distribution D90 of the catalyst is in the range of from 0.1 to 10 nm, preferably from 1 to 8 nm, more preferably from 2 to 6 nm, more preferably from 3 to 5 nm.

[0057] Alternatively, it is preferred that the particle size distribution D90 of the catalyst is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm.

[0058] In the case where the one or more rhodium sulfides is Rf^Ss, it is preferred that the particle size distribution D10 of the catalyst according to (2) is in the range of from 1 to 4 nm, preferably from 1 .5 to 3 nm, more preferably from 2 to 2.5 nm, more preferably from 2.1 to 2.4 nm. Alternatively, it is preferred that the particle size distribution D10 of the catalyst according to (2) is in the range of from 1 to 3 nm, preferably from 1 .4 to 2.6 nm, more preferably from 1 .6 to 2.4 nm, more preferably from 1 .8 to 2.2 nm.

[0059] In the case where the catalyst comprises one or more rhodium sulfides, it is preferred that the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 31 ° 20 [Cu K alpha], a second diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0060] Yet further, it is preferred that the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 28° 20 [Cu K alpha], a second diffraction angle in the range of from 29 to 31 ° 20 [Cu K alpha], a third diffraction angle in the range of from 40 to 42° 20 [Cu K alpha], a fourth diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a fifth diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], a sixth diffraction angle in the range of from 72 to 75° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0061] Alternatively, in the case where the catalyst comprises one or more rhodium sulfides, it is preferred that the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 32° 20 [Cu K alpha], a second diffraction angle in the range of from 40 to 44° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0062] Yet further, it is preferred that the phase purity of the one or more rhodium sulfides is in the range of from 100 to 10 %, preferably in the range of from 95 to 30 %, more preferably in the range of from 90 to 50%, wherein the phase purity is preferably determined according to Rietveld refinement of the X-ray diffraction pattern or the electron diffraction pattern.

[0063] In the context of the present application, the term „lanthanide“ refers to the elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0064] It is preferred that the catalyst further comprises one or more promotors, preferably wherein the one or more promotors are sulfides selected from the group consisting of Sc, Y, lanthanide , Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Ni, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Ge, Si, Sn, Pb, Sb, As, Se, and Te. Further, it is preferred that the molar ratio of Rh, calculated as the element, to the one or more promotors is in the range of from 0.01 :1 to 100:1 , preferably in the range of from 0.1 :1 to 10:1 , more preferably in the range of from 1 :1 to 5:1.

[0065] The first invention further relates to a process for the preparation of a catalyst comprising rhodium, sulfur, preferably one or more rhodium sulfides, and preferably a catalyst support, preferably a catalyst according to any of the embodiments disclosed herein, wherein the process comprises,

[0066] (2.1) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents, obtaining a precursor solution;

[0067] (2.2) impregnating a support material with the precursor solution obtained according to (2.1 ), obtaining an impregnated material;

[0068] (2.3) optionally drying the impregnated material obtained according to (2.2);

[0069] (2.4) subjecting the impregnated material obtained according to (2.2) or (2.3) to a thermal treatment under a gas atmosphere.

[0070] It is preferred that the thermal treatment in (2.4) is conducted at a temperature in the range of from 300 to 750 °C, preferably from 400 to 745°C, more preferably from 500 to 740°C, more preferably from 600 to 730°C, more preferably from 650 to 720°C, more preferably from 670 to 715°C.

[0071] It is preferred that the thermal treatment in (2.4) is conducted for a duration in the range of from 1 to 24 h, preferably from 3 to 12 h, more preferably from 4 to 8 h.

[0072] It is preferred that the preparation of the catalyst according to (2) comprises, (2.T) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents;

[0073] (2.2’) heating the mixture obtained according to (2.T) under mixing;

[0074] (2.3’) separating the liquid phase from the mixture obtained according to (2.2’), obtaining a solid material;

[0075] (2.4’) washing the solid material obtained according to (2.3’);

[0076] (2.5’) optionally drying the solid material obtained according to (2.4’);

[0077] (2.6’) subjecting the solid material obtained according to (2.4’) or (2.5’) to a thermal treatment.

[0078] In the case where the process comprises steps (2.1 ’)-(2.6’), it is preferred that separating in (2.3’) is conducted by filtration or centrifugation, preferably centrifugation.

[0079] In the case where the process comprises steps (2.1 ’)-(2.6’), it is preferred that the thermal treatment in (2.6’) is conducted at a temperature in the range of from 200 to 550 °C, preferably from 300 to 545°C, more preferably from 350 to 540°C, more preferably from 400 to 535°C, more preferably from 450 to 530°C, more preferably from 470 to 520°C. Further, it is preferred that the thermal treatment in (2.6’) is conducted for a duration in the range of from 1 to 10 h, preferably from 2 to 8 h, more preferably from 3 to 6 h. Alternatively, it is preferred that the thermal treatment in (2.6’) is conducted at a temperature in the range of from 700 to 1000°C, preferably from 800 to 950°C, more preferably from 850 to 930°C, more preferably from 870 to 920°C. Yet further, it is preferred that the thermal treatment in (2.6’) is conducted for a duration in the range of from 10 to 300 min, preferably of from 20 to 200 min, more preferably of from 50 to 120 min, more preferably of from 70 to 100 min.

[0080] It is preferred that independently from each other the thermal treatment in (2.4) and (2.6’) is performed under an inert gas atmosphere, wherein the inert gas atmosphere in (2.4) or (2.6’) preferably comprises argon or nitrogen, more preferably argon.

[0081] In the case where the process comprises steps (2.1 ’)-(2.6’), it is preferred that mixing in (2.2’) is conducted at a temperature in the range of from 100 to 300°C, preferably from 130 to 250°C, more preferably from 150 to 230°C, more preferably from 170 to 210°C. Yet further, it is preferred that mixing in (2.2’) is conducted for a duration in the range of from 1 to 24 h, preferably from 5 to 20 h, more preferably from 10 to 15h.

[0082] It is preferred that independently from each other the one or more rhodium sources according to (2.1) or (2.1 ’) are rhodium salts, wherein preferably the one or more rhodium sources are selected from the group consisting of rhodium acetate, rhodium chloride, rhodium nitrate, rhodium acetyl acetonate, rhodium phosphate, hexa rhodium hexadecacarbonyl, rhodium carbonyl chloride, rhodium bromide, rhodium triflouride, rhodium iodide, rhodium sulfate, rhodium perchlorate, rhodium oxide, rhodium hydroxide, or mixtures of two or more thereof, more preferably selected from the group consisting of rhodium acetate, rhodium acetyl acetonate, or mixtures thereof, more preferably wherein the one or more rhodium sources are rhodium acetate.

[0083] It is preferred that independently from each other the one or more sulfur sources according to (2.1 ) or (2.1 ’) are sulfur containing compounds, wherein preferably the one or more sulfur sources are selected from the group consisting of thiourea, ammonium sulfide, ammonium bisulfate, ammonium thiosulfate, hydrogen sulfide, carbonyl sulfide, sulfuryl fluoride, sodium sulfide, sodium thiosulfate, dimethyl sulfide, sodium sulfate, ammonium sulfate, thiol, thioether, sulfonic acid, or mixtures of two or more thereof, more preferably selected from the group consisting of thiourea, ammonium thiosulfate, or mixtures thereof, more preferably wherein the one or more sulfur sources are thiourea.

[0084] It is preferred that independently from each other the one or more solvents according to (2.1) or (2.1 ’) are selected from the group consisting of water, diethylene glycol, acetaldehyde, acetone, ethanol, ethylene glycol, glycerol, methanol, 1 -propanol, 2-propanol, or mixtures of two or more thereof, preferably selected from water, diethylene glycol, acetone, ethanol, 2-propanol, or mixtures of two or more thereof, more preferably selected from water, diethylene glycol, 2-propanol, or mixtures of two or more thereof. It is preferred that independently from each other drying in (3.3) or (3.5’) is conducted at a temperature in the range of from 5 to 200°C, preferably from 10 to 150°C, more preferably from 15 to 100°C, more preferably from 20 to 80 °C.

[0085] It is preferred that independently from each other heating in (2.4), or (2.6’) is performed under a gas atmosphere, wherein the gas atmosphere in (2.4) or (2.6’) preferably comprises an inert gas, more preferably nitrogen and / or argon, more preferably comprises argon.

[0086] It is preferred that independently from each other during (2.2) or (2.1 ’) 30 to 75 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1), is added to the mixture, preferably 35 to 70 wt.-% or , more preferably 40 to 65 wt.-% or , more preferably 45 to 60 wt.-% or more, more preferably 50 to 55 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1 ), is added to the mixture.

[0087] It is preferred that the impregnated material obtained according to (2.4) comprises at least one or more crystalline or partially crystalline rhodium sulfides.

[0088] The first invention further refers to a catalyst comprising rhodium, sulfur, preferably at least one or more rhodium sulfides, and a catalyst support, as obtained or obtainable according to any of the embodiments disclosed herein.

[0089] The first invention further refers to a process for the hydroformylation of olefins comprising, preferably consisting of,

[0090] (1 ) providing a mixture comprising one or more olefins, carbon monoxide, and hydrogen;

[0091] (2) providing a catalyst comprising rhodium, sulfur, and preferably a catalyst support;

[0092] (3) subjecting the mixture provided according to (1 ) to hydroformylation conditions in a reaction space S, said conditions comprising contacting the mixture according to (1 ) with the catalyst provided according to (2), obtaining a reaction mixture comprising one or more aldehydes.

[0093] It is preferred that the one or more olefins have a C2 to C30 carbon chain forming the backbone of the one or more olefins, preferably a C2 to C20 carbon chain, more preferably wherein the one or more olefins have a C3 to C10 carbon chain forming the backbone of the one or more olefins.

[0094] It is preferred that the one or more olefins are selected from the group consisting of branched and unbranched olefins, including mixtures thereof, wherein preferably the one or more olefins are selected from the group consisting of unbranched olefins, including mixtures thereof.

[0095] It is preferred that the one or more olefins are alpha olefins. It is preferred that independently from one another, the one or more olefins contain one or more C-C double bonds, preferably one to three C-C double bonds, more preferably one or two C-C double bonds, more preferably one C-C double bond.

[0096] It is preferred that the one or more olefins comprise one or more aromatic groups, wherein the aromatic group is preferably a benzyl group.

[0097] It is preferred that the one or more olefins are selected from the group consisting of branched and / or unbranched, preferably unbranched, ethylene, propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -heptene, 1 -octene, 1 -decene, 1 -dodecene, 1 -octadecene, and styrene, preferably from the group consisting of 1 -octene and styrene.

[0098] It is preferred that contacting in (3) is conducted in a fixed bed reactor or a fluidized bed reactor, preferably in a fixed bed reactor, most preferably all reactants in the fixed bed reactor are in gaseous phase.

[0099] It is preferred that contacting in (3) is conducted in a stirred tank, a trickle bed reactor or a bubble column, preferably in a stirred tank or a trickle bed reactor.

[0100] It is preferred that the temperature in the reaction space S is in the range of from 30 to 200°C, preferably from 40 to 150°C, more preferably from 50 to 110°C, more preferably from 60 to 100°C, more preferably from 70 to 90°C.

[0101] It is preferred that the pressure in the reaction space S is in the range of from 1 to 100 bar, preferably from 10 to 80 bar, more preferably from 20 to 60 bar, more preferably from 30 to 50 bar.

[0102] It is preferred that the reaction time in the reaction space S is in the range of from 0.1 to 12 h, preferably from 0.1 to 9 h, more preferably from 0.5 to 5 h, more preferably from 0.75 to 3 h, more preferably from 1 to 2 h.

[0103] It is preferred that the conversion rate of the one or more olefins is 40% or higher, preferably 50% or higher, more preferably 60% or higher, more preferably 70% or higher, more preferably 80% or higher, more preferably 90% or higher.

[0104] It is preferred that the one or more aldehydes comprised in the reaction mixture obtained in (3) comprise one or more unbranched and / or branched aldehydes, preferably one or more unbranched aldehydes.

[0105] In case where the reaction mixture obtained in (3) comprises one or more unbranched and / or branched aldehydes, it is preferred that the molar ratio of unbranched to branched aldehydes is 0.5 or higher, preferably 0.6 or higher, more preferably 0.7 or higher, more preferably 0.8 or higher, more preferably 0.9 or higher. It is preferred that the process further comprises

[0106] (5) removing a product mixture from the reaction space S, wherein the reaction mixture comprises the one or more aldehydes.

[0107] In the case where the process comprises step (5), it is preferred that the process further comprises

[0108] (6) separating the one or more aldehydes from the reaction mixture.

[0109] In the case where the process comprises step (6), it is preferred that separating the one or more aldehydes according to (6) is conducted by distillation, preferably fractionated distillation.

[0110] It is preferred that the reaction mixture is substantially free of hydrogenation products of the one or more olefins, preferably wherein the content of hydrogenation products is 10% or less, preferably 5% or less, more preferably 4% or less, more preferably 3% or less, based on the total amount of the reaction mixture, wherein preferably the hydrogenation products comprise one or more compounds selected from the group consisting of propane, 1 -butane, 1 -pentane, 1 -hexane, 1 -heptane, 1 -octane, 1 -decane, 1-dodacene, 1-octadacene, and ethylbenzene.

[0111] It is preferred that the reaction space S is a batch reactor, preferably a stirred tank reactor.

[0112] It is preferred that the reaction space S is a continuous reactor, preferably a tubular reactor or a continuous stirred tank reactor.

[0113] It is preferred that the molar ratio of CO:H2 comprised in the mixture according to (1) is in the range of from 1 :0.75 to 1 :3, preferably from 1 :0.8 to 1 :2, more preferably from 1 :0.85 to 1 :1.5, more preferably from 1 :0.9 to 1 :1 .2.

[0114] It is preferred that the weight ratio of Rh to the one or more olefins in the reaction space according to (3) is in the range of from 1 :100 to 1 :900, preferably from 1 :200 to 1 :800, more preferably from 1 :300 to 1 :700, more preferably from 1 :400 to 1 :600.

[0115] The first invention further refers to the use of a catalyst according to any of the embodiments disclosed herewith as a catalyst in the conversion of olefins to aldehydes.

[0116] The present inventions further relates to a second invention. It was an object of the second invention to provide a suitable heterogeneous catalyst system with sufficient activity and selectivity, and which is also stable towards deactivation. Surprisingly it was found that materials containing one or more rhodium sulfides, preferably as nanoparticles, supported on a particulate oxidic material can be usefully employed in the hydroformylation reaction. Further, it was an object to provide a process for preparation of such a material. Furthermore, it was an object of the second invention to provide a highly active and selective catalyst regarding the hydroformylation of alpha-olefins. Surprisingly, it was found that the inventive catalyst according to the second invention allows not only for high activity at lower metal loadings, but also provides high selectivity to target products, low selectivity in undesirable side reactions, and especially a low selectivity towards hydrogenation of double bonds of the olefin reactants. Without wanting to be bound by any theories, the high activity even with low metal loading could be related to the large surface area and defined porosity of the oxidic support materials, whereby oxidic support materials are relatively inexpensive materials compared to other support materials with comparable properties. Further, it was found that a catalyst according to the second invention comprising an oxidic support material exhibits good chemical and thermal stability.

[0117] Therefore, the second invention relates to a catalyst comprising one or more rhodium sulfides and a catalyst support, wherein the average particle size (D50) of the catalyst is in the range of from 100 to 1000 pm, wherein the particle size is preferably measured according to reference example 4.

[0118] Within the meaning of the second invention, the rhodium sulfide Rhi7Si5is the rhodium sulfide according to ICSD-410838. Further, the rhodium sulfide RhsS4 is the rhodium sulfide according to ICSD-410813, and the rhodium sulfide Rf^Ss is the rhodium sulfide according to ICSD- 56882.

[0119] It is preferred that the one or more rhodium sulfides are selected from the group consisting of RhiySis, RhsS i, and Rf^Ss, and mixtures thereof, preferably from Rhi7Si5and Rf^Ss, and mixtures thereof, more preferably wherein the one or more rhodium sulfides is RhnSis.

[0120] It is preferred that the one or more rhodium sulfides are located on the surface of the catalyst, wherein said surface of the catalyst comprising one or more rhodium sulfides comprises a first structure motive according to formula (I) comprising 4 adjacent rhodium atoms Rh(1 ) to Rh(4) in a planar or substantially planar ring arrangement: wherein all of the rhodium atoms Rh(1) to Rh(4) are in the outermost layer of atoms forming the outer surface of the one or more rhodium sulfides, wherein the first structure motive comprises a first Rh(1 )-Rh(2)-Rh(3) angle in the range of from 55.0 to 65.0°, and a second Rh(2)-Rh(3)- Rh(4) angle in the range of from 105.0 to 120.0, wherein preferably the geometry of the ring arrangement according to formula (I) and the angles of the first structure motive are determined according to reference example 6.

[0121] In the case where the surface of the catalyst comprises a first structure motive according to formula (I), it is preferred that the first structure motive comprises a first Rh(1 )-Rh(2)-Rh(3) angle in the range of from 57.0 to 63.0°, preferably from 58.0 to 62.0°, more preferably from 59.0 to 61 .0 °, wherein preferably the first Rh(1)-Rh(2)-Rh(3) angle of the first structure motive is determined according to reference example 6.

[0122] Yet further, it is preferred that the first structure motive comprises a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 110.0 to 116.0°, preferably from 111 .0 to 115.0°, more preferably from 112.0 to 114.0°, wherein preferably the second Rh(2)-Rh(3)-Rh(4) angle of the first structure motive is determined according to reference example 6.

[0123] Yet further, it is preferred that the ring arrangement of rhodium atoms Rh(1) to Rh(4) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(1 ), Rh(2), and Rh(4) and the plane defined by Rh(2), Rh(3), and Rh(4) or the dihedral angle between the plane defined by Rh(1 ), Rh(2), and Rh(3) and the plane defined by Rh(1 ), Rh(3), and Rh(4) deviates from 180° in the range of from -15 to 15°, preferably in the range of from -12 to 12°, wherein preferably the dihedral angles of the first structure motive are determined according to reference example 6.

[0124] Yet further, it is preferred that the first structure motive comprises a first rhodium-rhodium distance Rh(1 )-Rh(2) in the range of from 2.50 to 2.65 A and a second rhodium-rhodium distance Rh(2)-Rh(3) in the range of from 2.70 to 2.90 A, wherein preferably the rhodium-rhodium distances of the first structure motive are determined according to reference example 6.

[0125] In the case where the first structure motive comprises a first rhodium-rhodium distance Rh(1 )- Rh(2) and a second rhodium-rhodium distance, it is preferred that the first rhodium-rhodium distance Rh(1 )-Rh(2) is in the range of from 2.54 to 2.62 A, preferably from 2.55 to 2.61 A, more preferably from 2.56 to 2.60 A, wherein preferably the first rhodium-rhodium distance Rh(1 )- Rh(2) of the first structure motive is determined according to reference example 6.

[0126] Yet further, it is preferred that the second rhodium-rhodium distance Rh(2)-Rh(3) is in the range of from 2.75 to 2.85 A, preferably from 2.76 to 2.84 A, more preferably from 2.77 to 2.83 A, wherein preferably the second rhodium-rhodium distance Rh(2)-Rh(3) of the first structure motive is determined according to reference example 6.

[0127] Yet further, it is preferred that the ring arrangement of the first structure motive forms a rhomboid.

[0128] Yet further, it is preferred that the surface is the (100) surface plane of the one or more rhodium sulfides.

[0129] Yet further, it is preferred that the first structure motive is comprised in a 3x3x1 supercell.

[0130] In the case where the first structure motive is comprised in a 3x3x1 supercell, it is preferred that the 3x3x1 supercell comprises, preferably consists of, 8 rhodium atoms. In the case where the surface of the catalyst a first structure motive according to formula (I), it is preferred that the catalyst further comprises a second structure motive comprising 4 adjacent rhodium atoms Rh(5) to Rh(8) in a planar or substantially planar ring arrangement, according to formula (II): wherein all of the rhodium atoms Rh(1) to Rh(8) are in the outermost layer of atoms forming the outer surface of the one or more rhodium sulfides comprising the first structure motive in said outermost layer, wherein preferably the geometry of the ring arrangement according to formula (II) is determined according to reference example 6.

[0131] In the case where the catalyst further comprises a second structure motive according to formula (II), it is preferred that the ring arrangement of rhodium atoms Rh(5) to Rh(8) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(5), Rh(6), and Rh(8) and the plane defined by Rh(6), Rh(7), and Rh(8) or between the plane defined by Rh(5), Rh(6), and Rh(7) and the plane defined by Rh(5), Rh(7), and Rh(8) deviates from 180° in the range of from -10 to 10°, preferably in the range of from -6 to 6°, wherein preferably the dihedral angles of the second structure motive are determined according to reference example 6. Yet further, it is preferred that the first structure motive and the second structure motive do not have any rhodium atoms in common. Yet further, it is preferred that the ring arrangement of the second structure motive forms a rhomboid. Yet further, it is preferred that the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)- Rh(8) angle in the range of from 93.0 to 104.0°, wherein preferably the angles of the second structure motive are determined according to reference example 6.

[0132] In the case where the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)-Rh(8) angle in the range of from 93.0 to 104.0°, it is preferred that the first Rh(5)-Rh(6)-Rh(7) angle is in the range of from 78.0 to 85.0°, preferably from 80.0 to 83.0 °, wherein preferably the first Rh(5)-Rh(6)-Rh(7) angle of the second structure motive is determined according to reference example 6. Yet further, it is preferred that the second Rh(6)-Rh(7)-Rh(8) angle is in the range of from 95.0 to 102.0°, preferably from 97.0 to 100.0°, wherein preferably the second Rh(6)-Rh(7)-Rh(8) angle of the second structure motive is determined according to reference example 6.

[0133] In the case where the catalyst further comprises a second structure motive according to formula (II), it is preferred that the second structure motive comprises a first rhodium-rhodium distance Rh(5)-Rh(6) in the range of from 2.48 to 2.58 A, preferably from 2.50 to 2.56 A, more preferably from 2.52 to 2.54 A, and a second rhodium-rhodium distance Rh(6)-Rh(7) in the range of from 2.70 to 3.00 A, preferably from 2.75 to 2.95 A, more preferably from 2.80 to 2.90 A, wherein preferably the rhodium-rhodium distances of the second structure motive are determined according to reference example 6.

[0134] In the case where the surface of the catalyst comprises a first structure motive according to formula (I), it is preferred that the one or more rhodium sulfides display a cubic crystal structure, preferably wherein the space group of the unit cell is Pm3m. Yet further, it is preferred that the catalyst further comprises one or more ligands, wherein the one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive, preferably to Rh(1) or Rh(3) of the first structure motive.

[0135] In case where the catalyst further comprises one or more ligands, it is preferred that one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive.

[0136] Yet further, it is preferred that the one or more ligands are selected from the group consisting of anionic ligands, cationic ligands, and neutral ligands.

[0137] Yet further, it is preferred that the ligand is selected from the group consisting of carbon monoxide, nitrogen monoxide, water, and ammonia, preferably selected from the group consisting of carbon monoxide, and nitrogen monoxide, wherein more preferably the one or more ligands are carbon monoxide.

[0138] Yet further, it is preferred that the one or more ligands are selected from the group consisting of nitrogen monoxide, water, and ammonia, wherein preferably the one or more ligands are nitrogen monoxide.

[0139] Alternatively, it is preferred that no ligand is coordinated and / or bonded, preferably bonded, to the first structure motive.

[0140] As a second alternative, it is preferred that the catalyst is substantially free of carbon monoxide, preferably wherein the catalyst is free of carbon monoxide.

[0141] In the case where the surface of the catalyst comprises one or more of the crystalline binary RhxAy systems comprises a first structure motive according to formula (I), it is preferred that the catalyst further comprises a catalyst support.

[0142] It is preferred that the average particle size (D50) of the catalyst is in the range of from 250 to 500 pm, wherein the particle size is preferably measured according to reference example 4.

[0143] It is preferred that the catalyst is a heterogeneous catalyst.

[0144] In the case where the catalyst comprises a catalyst support, it is preferred that the catalyst support, preferably a particulate catalyst support, is an oxidic catalyst support, more preferably wherein the oxidic catalyst support comprises, more preferably consists of, a metal oxide and / or metalloid, preferably wherein the metal of the metal oxide and / or metalloid oxide catalyst support is selected from the group consisting of Zr, Al, Si, Ti, La, Ce, Nd, Y, Pr, and mixtures of two or more thereof, more preferably selected from the group consisting of Zr, Al, Si, La, Ce, Y and mixtures of two or more thereof, more preferably selected from the group consisting of Zr, Si and mixtures of two or more thereof, more preferably wherein the metal of the metal oxide and / or metalloid oxide catalyst support comprises, preferably consists of, Si, more preferably wherein the oxidic catalyst support is selected from the group consisting of ZrC>2, AI2O3, SiC>2, TiC>2, La2C>3-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2Os-doped CeO2-ZrO2 mixed oxide, Nd20s- doped CeO2-ZrC>2 mixed oxide, Y2Os-doped CeO2-ZrO2 mixed oxide, P^Os-doped CeO2-ZrO2 mixed oxide, ZrC>2-doped AI2O3, ZrC>2-doped SiC>2, SiC>2-doped AI2O3, and mixtures of two or more thereof, more preferably from the group consisting of ZrC>2, SiC>2, La2Os-doped ZrC>2, CeO2-ZrC>2 mixed oxide, La2Os-doped CeO2-ZrO2 mixed oxide, Nd2Os-doped CeO2-ZrO2 mixed oxide, Y2C>3-doped CeO2-ZrO2 mixed oxide, P^Os-doped CeO2-ZrO2 mixed oxide, ZrC>2-doped SiC>2, and mixtures of two or more thereof, more preferably from the group consisting of SiC>2, ZrC>2-doped SiC>2, and mixtures of two or more thereof.

[0145] In the case that the catalyst is an oxidic catalyst support, it is preferred that the catalyst support exhibits an average particle size (D50) in the range of from 200 to 600 pm, more preferably in the range of from 210 to 580 pm, more preferably in the range of from 220 to 560 pm, more preferably in the range of from 230 to 540 pm, more preferably in the range of from 240 to 520 pm, more preferably in the 30 range of from 200 to 500 pm, wherein the average particle size is preferably measured according to reference example 4. Yet further, it is preferred that the catalyst support exhibits a BET surface area in the range of from 300 to 700 m2 / g, more preferably in the range of from 400 to 600 35 m2 / g, more preferably in the range of from 420 to 580 m2 / g, more preferably in the range of from 440 to 560 m2 / g, more preferably in the range of from 460 to 540 m2 / g, more preferably in the range of from 480 to 520 m2 / g, wherein the BET surface area is preferably measured according to reference example 7. Yet further, it is preferred that the catalyst support exhibits an average pore diameter in the range of from 10 to 100 A, more preferably in the range of from 30 to 90 A, more preferably in the rage of from 40 to 80 A, more preferably in the range of from 50 to 70 A,, wherein the average pore diameter is preferably measured according to reference example 7.

[0146] Alternatively, it is preferred that the catalyst support is selected from the group consisting of activated carbon, graphite, carbide, and mixtures of two or more thereof, preferably activated carbon, graphite, silicon carbide, boron carbide, tungsten carbide, and mixtures of two or more thereof.

[0147] As a second alternative, it is preferred that the catalyst support, preferably a porous catalyst support, is selected from the group of metal organic frameworks (MOF) and zeolites, preferably wherein the catalyst support is a zeolite. As a third alternative, it is preferred that the catalyst support is a polymer, preferably wherein the polymer is selected from the group consisting of polyolefins, polyamide, polyester, polyacrylate, polyethylene, polyurethane, polyvinylpyrrolidone, polystyrene, and mixtures of two or more thereof, preferably selected from the group consisting of polystyrene, polyethylene, and mixtures of two or more thereof.

[0148] It is preferred that the rhodium content of the catalyst is in the range of from 0.1 to 15 wt.-%, calculated as the element, preferably from 0.2 to 14 wt.-%, more preferably from 0.3 to 13 wt.-%, more preferably from 0.4 to 12 wt.-%, more preferably from 0.5 to 11 wt.-%, more preferably from 0.6 to 10 wt.-%, more preferably from 0.7 to 5 wt.-%, more preferably from 0.8 to 2 wt.-%, more preferably from 0.9 to 1 .5 wt.-%, based on 100 wt.-% of the catalyst.

[0149] In the case where the catalyst comprises one or more rhodium sulfides, it is preferred that independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.1 to 5, preferably from 0.5 to 3, more preferably from 0.6 to 2, more preferably from 0.7 to 1 .8, more preferably from 0.8 to 1 .7. Yet further, it is preferred that independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.5 to 2.0, preferably from 0.7 to 1 .1 , more preferably from 0.8 to 1 .0, more preferably from 0.85 to 0.95. Yet further, it is preferred that independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 1 to 2.5, preferably from 1 .4 to 1 .9, more preferably from 1 .5 to 1 .8, more preferably from 1 .6 to 1 .7.

[0150] Within the meaning of the first invention, the particle size distribution refers to a volume or number based particle size distribution, preferably to a number based particle size distribution.

[0151] It is preferred that the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 0.5 to 8 nm, more preferably from 1 to 6 nm, more preferably from 1 .5 to 5 nm, wherein the particle size is preferably measure according to reference example 4.

[0152] It is preferred that the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 0.1 to 7 nm, more preferably from 0.1 to 6 nm, more preferably from 0.5 to 5 nm, wherein the particle size is preferably measure according to reference example 4.

[0153] In the case where the one or more rhodium sulfides comprise, preferably consist of, hi7Si5, it is preferred that the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, more preferably from 0.5 to 7 nm, more preferably from 1 to 6 nm, more preferably from 1 .5 to 5 nm, wherein the particle size is preferably measure according to reference example 4.

[0154] In the case where the one or more rhodium sulfides comprise, preferably consist of, hi7Si5, it is preferred that the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, more preferably from 1 to 5 nm, more preferably from 2 to 4 nm, more preferably from 2.5 to 3.5 nm.

[0155] Alternatively, it is preferred that the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm.

[0156] As a second alternative, it is preferred that the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 1 to 25 nm, preferably from 5 to 20 nm, more preferably from 8 to 14 nm, more preferably from 10 to 12 nm.

[0157] In the case where the one or more rhodium sulfide comprise, preferably consist of, Rhi7Si5, it is preferred that the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 0.5 to 3 nm, more preferably from 1 to 2 nm, more preferably from 1.1 to 1.9 nm, more preferably from 1 .3 to 1 .7 nm.

[0158] Alternatively, it is preferred that the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 1 to 3.5 nm, more preferably from 1 .5 to 2.5 nm, more preferably from 1 .7 to 2.3 nm, more preferably from 1 .9 to 2.2 nm.

[0159] As a second alternative, it is preferred that the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 2 to 4.5 nm, more preferably from 2.5 to 3.5 nm, more preferably from 2.7 to 3.3 nm, more preferably from 2.9 to 3.1 nm.

[0160] In the case where the one or more rhodium sulfides comprise, preferably consist of, Rf^Ss, it is preferred that the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, more preferably from 2 to 4 nm, more preferably from 2.3 to 3.7 nm, more preferably from 2.5 to 3.5 nm, wherein the particle size is preferably measure according to reference example 4.

[0161] In the case where the one or more rhodium sulfides comprise, preferably consist of, Rf^Ss, it is preferred that the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, more preferably from 1 to 8 nm, more preferably from 2 to 6 nm, more preferably from 3 to 5 nm.

[0162] Alternatively, it is preferred that the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm.

[0163] In the case where the one or more rhodium sulfides comprise, preferably consist of, Rf^Ss, it is preferred that the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 1 to 4 nm, more preferably from 1 .5 to 3 nm, more preferably from 2 to 2.5 nm, more preferably from 2.1 to 2.4 nm. Alternatively, it is preferred that the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 1 to 3 nm, more preferably from 1 .4 to 2.6 nm, more preferably from 1 .6 to 2.4 nm, more preferably from 1 .8 to 2.2 nm.

[0164] It is preferred that the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 31 ° 20 [Cu K alpha], a second diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0165] Yet further, it is preferred that the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 28° 20 [Cu K alpha], a second diffraction angle in the range of from 29 to 31 ° 20 [Cu K alpha], a third diffraction angle in the range of from 40 to 42° 20 [Cu K alpha], a fourth diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a fifth diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], a sixth diffraction angle in the range of from 72 to 75° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0166] Alternatively, it is preferred that the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 32° 20 [Cu K alpha], a second diffraction angle in the range of from 40 to 44° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0167] Yet further, it is preferred that the phase purity of the one or more rhodium sulfides is in the range of from 100 to 10 %, preferably in the range of from 95 to 30 %, more preferably in the range of from 90 to 50%, wherein the phase purity is preferably determined according to Rietveld refinement of the X-ray diffraction pattern or the electron diffraction pattern.

[0168] In the context of the present application, the term „lanthanide“ refers to the elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0169] It is preferred that the catalyst further comprises one or more promotors, preferably wherein the one or more promotors are sulfides selected from the group consisting of Sc, Y, lanthanide , Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Ni, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Ge, Si, Sn, Pb, Sb, As, Se, and Te. Further, it is preferred that the molar ratio of Rh, calculated as the element, to the one or more promotors is in the range of from 0.01 :1 to 100:1 , preferably in the range of from 0.1 :1 to 10:1 , more preferably in the range of from 1 :1 to 5:1. The second invention further relates to a process for the preparation of a catalyst comprising rhodium, sulfur, preferably one or more rhodium sulfides, and preferably a catalyst support, preferably a catalyst according to any of the embodiments disclosed herein, wherein the process comprises,

[0170] (2.1 ) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents, obtaining a precursor solution;

[0171] (2.2) impregnating a support material with the precursor solution obtained according to (2.1 ), obtaining an impregnated material;

[0172] (2.3) optionally drying the impregnated material obtained according to (2.2);

[0173] (2.4) subjecting the impregnated material obtained according to (2.2) or (2.3) to a thermal treatment under a gas atmosphere.

[0174] It is preferred that the thermal treatment in (2.4) is conducted at a temperature in the range of from 300 to 750 °C, preferably from 400 to 745°C, more preferably from 500 to 740°C, more preferably from 600 to 730°C, more preferably from 650 to 720°C, more preferably from 670 to 715°C.

[0175] It is preferred that the thermal treatment in (2.4) is conducted for a duration in the range of from 1 to 24 h, preferably from 3 to 12 h, more preferably from 4 to 8 h.

[0176] It is preferred that the preparation of the catalyst according to (2) comprises, (2.T) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents;

[0177] (2.2’) heating the mixture obtained according to (2.T) under mixing;

[0178] (2.3’) separating the liquid phase from the mixture obtained according to (2.2’), obtaining a solid material;

[0179] (2.4’) washing the solid material obtained according to (2.3’);

[0180] (2.5’) optionally drying the solid material obtained according to (2.4’);

[0181] (2.6’) subjecting the solid material obtained according to (2.4’) or (2.5’) to a thermal treatment.

[0182] In the case where the process comprises steps (2.1 ’)-(2.6’), it is preferred that separating in (2.3’) is conducted by filtration or centrifugation, preferably centrifugation.

[0183] In the case where the process comprises steps (2.1 ’)-(2.6’), it is preferred that the thermal treatment in (2.6’) is conducted at a temperature in the range of from 200 to 550 °C, preferably from 300 to 545°C, more preferably from 350 to 540°C, more preferably from 400 to 535°C, more preferably from 450 to 530°C, more preferably from 470 to 520°C. Further, it is preferred that the thermal treatment in (2.6’) is conducted for a duration in the range of from 1 to 10 h, preferably from 2 to 8 h, more preferably from 3 to 6 h.

[0184] Alternatively, it is preferred that the thermal treatment in (2.6’) is conducted at a temperature in the range of from 700 to 1000°C, preferably from 800 to 950°C, more preferably from 850 to 930°C, more preferably from 870 to 920°C. Yet further, it is preferred that the thermal treatment in (2.6’) is conducted for a duration in the range of from 10 to 300 min, preferably of from 20 to 200 min, more preferably of from 50 to 120 min, more preferably of from 70 to 100 min.

[0185] It is preferred that independently from each other the thermal treatment in (2.4) and (2.6’) is performed under an inert gas atmosphere, wherein the inert gas atmosphere in (2.4) or (2.6’) preferably comprises argon or nitrogen, more preferably argon.

[0186] In the case where the process comprises steps (2.1 ’)-(2.6’), it is preferred that mixing in (2.2’) is conducted at a temperature in the range of from 100 to 300°C, preferably from 130 to 250°C, more preferably from 150 to 230°C, more preferably from 170 to 210°C. Yet further, it is preferred that mixing in (2.2’) is conducted for a duration in the range of from 1 to 24 h, preferably from 5 to 20 h, more preferably from 10 to 15h.

[0187] It is preferred that independently from each other the one or more rhodium sources according to (2.1) or (2.1 ’) are rhodium salts, wherein preferably the one or more rhodium sources are selected from the group consisting of rhodium acetate, rhodium chloride, rhodium nitrate, rhodium acetyl acetonate, rhodium phosphate, hexa rhodium hexadecacarbonyl, rhodium carbonyl chloride, rhodium bromide, rhodium triflouride, rhodium iodide, rhodium sulfate, rhodium perchlorate, rhodium oxide, rhodium hydroxide, or mixtures of two or more thereof, more preferably selected from the group consisting of rhodium acetate, rhodium acetyl acetonate, or mixtures thereof, more preferably wherein the one or more rhodium sources are rhodium acetate.

[0188] It is preferred that independently from each other the one or more sulfur sources according to (2.1 ) or (2.1 ’) are sulfur containing compounds, wherein preferably the one or more sulfur sources are selected from the group consisting of thiourea, ammonium sulfide, ammonium bisulfate, ammonium thiosulfate, hydrogen sulfide, carbonyl sulfide, sulfuryl fluoride, sodium sulfide, sodium thiosulfate, dimethyl sulfide, sodium sulfate, ammonium sulfate, thiol, thioether, sulfonic acid, or mixtures of two or more thereof, more preferably selected from the group consisting of thiourea, ammonium thiosulfate, or mixtures thereof, more preferably wherein the one or more sulfur sources are thiourea.

[0189] It is preferred that independently from each other the one or more solvents according to (2.1) or (2.1 ’) are selected from the group consisting of water, diethylene glycol, acetaldehyde, acetone, ethanol, ethylene glycol, glycerol, methanol, 1 -propanol, 2-propanol, or mixtures of two or more thereof, preferably selected from water, diethylene glycol, acetone, ethanol, 2-propanol, or mixtures of two or more thereof, more preferably selected from water, diethylene glycol, 2-propanol, or mixtures of two or more thereof.

[0190] It is preferred that independently from each other drying in (3.3) or (3.5’) is conducted at a temperature in the range of from 5 to 200°C, preferably from 10 to 150°C, more preferably from 15 to 100°C, more preferably from 20 to 80 °C. It is preferred that independently from each other heating in (2.4), or (2.6’) is performed under a gas atmosphere, wherein the gas atmosphere in (2.4) or (2.6’) preferably comprises an inert gas, more preferably nitrogen and / or argon, more preferably comprises argon.

[0191] It is preferred that independently from each other during (2.2) or (2.1 ’) 30 to 75 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1 ), is added to the mixture, preferably 35 to 70 wt.-% or , more preferably 40 to 65 wt.-% or , more preferably 45 to 60 wt.-% or more, more preferably 50 to 55 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1), is added to the mixture.

[0192] It is preferred that the impregnated material obtained according to (2.4) comprises at least one or more crystalline or partially crystalline rhodium sulfides.

[0193] The second invention further refers to a catalyst comprising rhodium, sulfur, preferably at least one or more rhodium sulfides, and a catalyst support, as obtained or obtainable according to any of the embodiments disclosed herein.

[0194] The second invention further refers to a process for the hydroformylation of olefins comprising, preferably consisting of,

[0195] (1) providing a mixture comprising one or more olefins, carbon monoxide, and hydrogen;

[0196] (2) providing a catalyst comprising rhodium, sulfur, and preferably a catalyst support;

[0197] (3) subjecting the mixture provided according to (1) to hydroformylation conditions in a reaction space S, said conditions comprising contacting the mixture according to (1) with the catalyst provided according to (2), obtaining a reaction mixture comprising one or more aldehydes.

[0198] It is preferred that the one or more olefins have a C2 to C30 carbon chain forming the backbone of the one or more olefins, preferably a C2 to C20 carbon chain, more preferably wherein the one or more olefins have a C3 to C10 carbon chain forming the backbone of the one or more olefins.

[0199] It is preferred that the one or more olefins are selected from the group consisting of branched and unbranched olefins, including mixtures thereof, wherein preferably the one or more olefins are selected from the group consisting of unbranched olefins, including mixtures thereof.

[0200] It is preferred that the one or more olefins are alpha olefins.

[0201] It is preferred that independently from one another, the one or more olefins contain one or more C-C double bonds, preferably one to three C-C double bonds, more preferably one or two C-C double bonds, more preferably one C-C double bond.

[0202] It is preferred that the one or more olefins comprise one or more aromatic groups, wherein the aromatic group is preferably a benzyl group. It is preferred that the one or more olefins are selected from the group consisting of branched and / or unbranched, preferably unbranched, ethylene, propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -heptene, 1 -octene, 1 -decene, 1 -dodecene, 1 -octadecene, and styrene, preferably from the group consisting of 1 -octene and styrene.

[0203] It is preferred that contacting in (3) is conducted in a fixed bed reactor or a fluidized bed reactor, preferably in a fixed bed reactor, most preferably all reactants in the fixed bed reactor are in gaseous phase.

[0204] It is preferred that contacting in (3) is conducted in a stirred tank, a trickle bed reactor or a bubble column, preferably in a stirred tank or a trickle bed reactor.

[0205] It is preferred that the temperature in the reaction space S is in the range of from 30 to 200°C, preferably from 40 to 150°C, more preferably from 50 to 110°C, more preferably from 60 to 100°C, more preferably from 70 to 90°C.

[0206] It is preferred that the pressure in the reaction space S is in the range of from 1 to 100 bar, preferably from 10 to 80 bar, more preferably from 20 to 60 bar, more preferably from 30 to 50 bar.

[0207] It is preferred that the reaction time in the reaction space S is in the range of from 0.1 to 12 h, preferably from 0.1 to 9 h, more preferably from 0.5 to 5 h, more preferably from 0.75 to 3 h, more preferably from 1 to 2 h.

[0208] It is preferred that the conversion rate of the one or more olefins is 40% or higher, preferably 50% or higher, more preferably 60% or higher, more preferably 70% or higher, more preferably 80% or higher, more preferably 90% or higher.

[0209] It is preferred that the one or more aldehydes comprised in the reaction mixture obtained in (3) comprise one or more unbranched and / or branched aldehydes, preferably one or more unbranched aldehydes.

[0210] In case where the reaction mixture obtained in (3) comprises one or more unbranched and / or branched aldehydes, it is preferred that the molar ratio of unbranched to branched aldehydes is 0.5 or higher, preferably 0.6 or higher, more preferably 0.7 or higher, more preferably 0.8 or higher, more preferably 0.9 or higher.

[0211] It is preferred that the process further comprises

[0212] (5) removing a product mixture from the reaction space S, wherein the reaction mixture comprises the one or more aldehydes. In the case where the process comprises step (5), it is preferred that the process further comprises

[0213] (6) separating the one or more aldehydes from the reaction mixture.

[0214] In the case where the process comprises step (6), it is preferred that separating the one or more aldehydes according to (6) is conducted by distillation, preferably fractionated distillation.

[0215] It is preferred that the reaction mixture is substantially free of hydrogenation products of the one or more olefins, preferably wherein the content of hydrogenation products is 10% or less, preferably 5% or less, more preferably 4% or less, more preferably 3% or less, based on the total amount of the reaction mixture, wherein preferably the hydrogenation products comprise one or more compounds selected from the group consisting of propane, 1 -butane, 1 -pentane, 1 -hexane, 1 -heptane, 1 -octane, 1 -decane, 1-dodacene, 1-octadacene, and ethylbenzene.

[0216] It is preferred that the reaction space S is a batch reactor, preferably a stirred tank reactor.

[0217] It is preferred that the reaction space S is a continuous reactor, preferably a tubular reactor or a continuous stirred tank reactor.

[0218] It is preferred that the molar ratio of CO:H2 comprised in the mixture according to (1) is in the range of from 1 :0.75 to 1 :3, preferably from 1 :0.8 to 1 :2, more preferably from 1 :0.85 to 1 :1.5, more preferably from 1 :0.9 to 1 :1 .2.

[0219] It is preferred that the weight ratio of Rh to the one or more olefins in the reaction space according to (3) is in the range of from 1 :100 to 1 :900, preferably from 1 :200 to 1 :800, more preferably from 1 :300 to 1 :700, more preferably from 1 :400 to 1 :600.

[0220] The second invention further refers to the use of a catalyst according to any of the embodiments disclosed herewith as a catalyst in the conversion of olefins to aldehydes.

[0221] The present inventions are 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 “The catalyst according to 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 “The catalyst according to any of embodiments 1 , 2, 3, and 4”.

[0222] Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention. A catalyst comprising rhodium, sulfur, preferably one or more rhodium sulfides, and a catalyst support, wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, wherein the particle size is preferably measured according to reference example 4. The catalyst according to embodiment 1 , wherein the one or more rhodium sulfides are selected from the group consisting of Rhi7Si5, RhsS i, and Rf^Ss, and mixtures thereof, preferably from RhiySis and Rf^Ss, and mixtures thereof, more preferably wherein the one or more rhodium sulfides is Rhi7Si5. A catalyst comprising one or more crystalline binary RhxAysystems, wherein one or more of the crystalline binary RhxAysystems are located on the surface of the catalyst, wherein said surface of the catalyst comprising one or more of the crystalline binary RhxAysystems comprises a first structure motive according to formula (I) comprising 4 adjacent rhodium atoms Rh(1) to Rh(4) in a planar or substantially planar ring arrangement: wherein all of the rhodium atoms Rh(1 ) to Rh(4) are in the outermost layer of atoms forming the outer surface of the one or more crystalline binary RhxAysystems, wherein the first structure motive comprises a first Rh(1)-Rh(2)-Rh(3) angle in the range of from 55.0 to 65.0°, and a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 105.0 to 120.0, wherein preferably the geometry of the ring arrangement according to formula (II) and the angles of the first structure motive are determined according to reference example 6. The catalyst according to embodiment 3, wherein the first structure motive comprises a first Rh(1 )-Rh(2)-Rh(3) angle in the range of from 57.0 to 63.0°, preferably from 58.0 to 62.0°, more preferably from 59.0 to 61 .0 °, wherein preferably the first Rh(1)-Rh(2)-Rh(3) angle of the first structure motive is determined according to reference example 6. The catalyst according to embodiment 3 or 4, wherein the first structure motive comprises a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 110.0 to 116.0°, preferably from 111 .0 to 115.0°, more preferably from 112.0 to 114.0°, wherein preferably the second Rh(2)- Rh(3)-Rh(4) angle of the first structure motive is determined according to reference example

[0223] 6. The catalyst according to any one of embodiments 3 to 5, wherein the ring arrangement of rhodium atoms Rh(1 ) to Rh(4) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(1), Rh(2), and Rh(4) and the plane defined by Rh(2), Rh(3), and Rh(4) or the dihedral angle between the plane defined by Rh(1), Rh(2), and Rh(3) and the plane defined by Rh(1 ), Rh(3), and Rh(4) deviates from 180° in the range of from -15 to 15°, preferably in the range of from -12 to 12°, wherein preferably the dihedral angles of the first structure motive are determined according to reference example 6.

[0224] 7. The catalyst according to any of embodiments 3 to 6, wherein the first structure motive comprises a first rhodium-rhodium distance Rh(1 )-Rh(2) in the range of from 2.50 to 2.65 Aand a second rhodium-rhodium distance Rh(2)-Rh(3) in the range of from 2.70 to 2.90 A, wherein preferably the rhodium-rhodium distances of the first structure motive are determined according to reference example 6.

[0225] 8. The catalyst according to embodiment 7, wherein the first rhodium-rhodium distance Rh(1 )- Rh(2) is in the range of from 2.54 to 2.62 A, preferably from 2.55 to 2.61 A, more preferably from 2.56 to 2.60 A, wherein preferably the first rhodium-rhodium distance Rh(1 )-Rh(2) of the first structure motive is determined according to reference example 6.

[0226] 9. The catalyst according to embodiment 7 or 8, wherein the second rhodium-rhodium distance Rh(2)-Rh(3) is in the range of from 2.75 to 2.85 A, preferably from 2.76 to 2.84 A, more preferably from 2.77 to 2.83 A, wherein preferably the second rhodium-rhodium distance Rh(2)- Rh(3) of the first structure motive is determined according to reference example 6.

[0227] 10. The catalyst according to any of embodiments 3 to 9, wherein A is selected from the group consisting of N, P, As, Sb, S, O, Se, and mixtures of two or more thereof, preferably selected from the group consisting of P, S and mixtures thereof, more preferably wherein A comprises S, more preferably wherein A is S.

[0228] 11 . The catalyst according to any of embodiments 3 to 10, wherein the one or more crystalline binary systems RhxAycomprise, preferably consists of, one or more rhodium sulfides, wherein the one or more rhodium sulfides are selected from the group consisting of Rhi7Si5, RhsS i, and Rf^Ss, and mixtures thereof, preferably from Rhi7Si5and Rf^Ss, and mixtures thereof, more preferably wherein the one or more crystalline binary systems RhxAycomprise Rhi7Si5, wherein more preferably the one or more crystalline binary systems RhxAyis Rhi7Si5.

[0229] 12. The catalyst according to any of embodiments 3 to 11 , wherein the ring arrangement of the first structure motive forms a rhomboid.

[0230] 13. The catalyst according to any of embodiments 3 to 12, wherein the surface is the (100) surface plane of the one or more crystalline binary RhxAysystems.

[0231] 14. The catalyst according to any of embodiments 3 to 13, wherein the first structure motive is comprised in a 3x3x1 supercell. 15. The catalyst according to embodiment 14, wherein the 3x3x1 supercell comprises, preferably consists of, 8 rhodium atoms.

[0232] 16. The catalyst according to any of embodiments 3 to 15, wherein the catalyst further comprises a second structure motive comprising 4 adjacent rhodium atoms Rh(5) to Rh(8) in a planar or substantially planar ring arrangement, according to formula (II): wherein all of the rhodium atoms Rh(1 ) to Rh(8) are in the outermost layer of atoms forming the outer surface of the one or more crystalline binary RhxAysystems comprising the first structure motive in said outermost layer, wherein preferably the geometry of the ring arrangement according to formula (II) is determined according to reference example 6.

[0233] 17. The catalyst according to embodiment 16, wherein the ring arrangement of rhodium atoms Rh(5) to Rh(8) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(5), Rh(6), and Rh(8) and the plane defined by Rh(6), Rh(7), and Rh(8) or between the plane defined by Rh(5), Rh(6), and Rh(7) and the plane defined by Rh(5), Rh(7), and Rh(8) deviates from 180° in the range of from -10 to 10°, preferably in the range of from -6 to 6°, wherein preferably the dihedral angles of the second structure motive are determined according to reference example 6.

[0234] 18. The catalyst according to embodiment 16 or 17, wherein the first structure motive and the second structure motive do not have any rhodium atoms in common.

[0235] 19. The catalyst according to any of embodiments 16 to 18, wherein the ring arrangement of the second structure motive forms a rhomboid.

[0236] 20. The catalyst according to any of embodiments 16 to 19, wherein the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)-Rh(8) angle in the range of from 93.0 to 104.0°, wherein preferably the angles of the second structure motive are determined according to reference example 6.

[0237] 21 . The catalyst according to embodiment 20, wherein the first Rh(5)-Rh(6)-Rh(7) angle is in the range of from 78.0 to 85.0°, preferably from 80.0 to 83.0 °, wherein preferably the first Rh(5)- Rh(6)-Rh(7) angle of the second structure motive is determined according to reference example 6.

[0238] 22. The catalyst according to embodiment 20 or 21 , wherein the second Rh(6)-Rh(7)-Rh(8) angle is in the range of from 95.0 to 102.0°, preferably from 97.0 to 100.0°, wherein preferably the second Rh(6)-Rh(7)-Rh(8) angle of the second structure motive is determined according to reference example 6.

[0239] 23. The catalyst according to any of embodiments 16 to 22, wherein the second structure motive comprises a first rhodium-rhodium distance Rh(5)-Rh(6) in the range of from 2.48 to 2.58 A, preferably from 2.50 to 2.56 A, more preferably from 2.52 to 2.54 A, and a second rhodium-rhodium distance Rh(6)-Rh(7) in the range of from 2.70 to 3.00 A, preferably from 2.75 to 2.95 A, more preferably from 2.80 to 2.90 A, wherein preferably the rhodium-rhodium distances of the second structure motive are determined according to reference example 6.

[0240] 24. The catalyst according to any of embodiments 3 to 23, wherein the one or more crystalline binary RhxAysystems display a cubic crystal structure, preferably wherein the space group of the unit cell is Pm3m.

[0241] 25. The catalyst according to any of embodiments 3 to 24, wherein the catalyst further comprises one or more ligands, wherein the one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive, preferably to Rh(1 ) or Rh(3) of the first structure motive.

[0242] 26. The catalyst according to embodiment 25, wherein one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive.

[0243] 27. The catalyst according to embodiment 25 or 26, wherein the one or more ligands are selected from the group consisting of anionic ligands, cationic ligands, and neutral ligands.

[0244] 28. The catalyst according to any of embodiments 25 to 27, wherein the ligand is selected from the group consisting of carbon monoxide, nitrogen monoxide, water, and ammonia, preferably selected from the group consisting of carbon monoxide, and nitrogen monoxide, wherein more preferably the one or more ligands are carbon monoxide.

[0245] 29. The catalyst according to any of embodiments 25 to 28, wherein the one or more ligands are selected from the group consisting of nitrogen monoxide, water, and ammonia, wherein preferably the one or more ligands are nitrogen monoxide.

[0246] 30. The catalyst according to any of embodiments 3 to 24, wherein no ligand is coordinated and / or bonded, preferably bonded, to the first structure motive.

[0247] 31 . The catalyst according to any of embodiments 3 to 24, wherein the catalyst is substantially free of carbon monoxide, preferably wherein the catalyst is free of carbon monoxide.

[0248] 32. The catalyst according to any of embodiments 3 to 31 , wherein the catalyst further comprises a catalyst support. 33. The catalyst according to any of embodiments 3 to 32, wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, wherein the particle size is preferably measured according to reference example 4.

[0249] 34. The catalyst according to any of embodiments 1 to 33, wherein the catalyst is a heterogeneous catalyst.

[0250] 35. The catalyst according to any of embodiments 1 and 32 to 34, wherein the catalyst support, preferably a particulate catalyst support, is an oxidic catalyst support, preferably wherein the oxidic catalyst support comprises, more preferably consists of, a metal oxide and / or metalloid, preferably wherein the metal of the metal oxide and / or metalloid oxide catalyst support is selected from the group consisting of Zr, Al, Si, Ti, La, Ce, Nd, Y, Pr, and mixtures of two or more thereof, more preferably selected from the group consisting of Zr, Al, Si, La, Ce, Y and mixtures of two or more thereof, more preferably selected from the group consisting of Zr, Si and mixtures of two or more thereof, more preferably wherein the metal of the metal oxide and / or metalloid oxide catalyst support comprises, preferably consists of, Si, more preferably wherein the oxidic catalyst support is selected from the group consisting of ZrC>2, AI2O3, SiC>2, TiC>2, La2C>3-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2Os-doped CeO2-ZrO2 mixed oxide, Nd2Os-doped CeO2-ZrO2 mixed oxide, Y2Os-doped CeO2-ZrO2 mixed oxide, Pr2O3-doped CeO2-ZrO2 mixed oxide, ZrC>2-doped AI2O3, ZrC>2-doped SiC>2, SiC>2-doped AI2O3, and mixtures of two or more thereof, more preferably from the group consisting of ZrC>2, SiC>2, La2C>3-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2Os-doped CeO2-ZrO2 mixed oxide, Nd2C>3-doped CeO2-ZrO2 mixed oxide, Y2Os-doped CeO2-ZrO2 mixed oxide, P^Os- doped CeO2-ZrC>2 mixed oxide, ZrC>2-doped SiC>2, and mixtures of two or more thereof, more preferably from the group consisting of SiC>2, ZrC>2-doped SiC>2, and mixtures of two or more thereof.

[0251] 36. The catalyst according to any of embodiments 1 and 32 to 34, wherein the catalyst support is selected from the group consisting of activated carbon, graphite, carbide, and mixtures of two or more thereof, preferably activated carbon, graphite, silicon carbide, boron carbide, tungsten carbide, and mixtures of two or more thereof.

[0252] 37. The catalyst according to any of embodiments 1 and 32 to 34, wherein the catalyst support, preferably a porous catalyst support, is selected from the group of metal organic frameworks (MOF) and zeolites, preferably wherein the catalyst support is a zeolite.

[0253] 38. The catalyst according to any of embodiments 1 and 32 to 34, wherein the catalyst support is a polymer, preferably wherein the polymer is selected from the group consisting of polyolefins, polyamide, polyester, polyacrylate, polyethylene, polyurethane, polyvinylpyrrolidone, polystyrene, and mixtures of two or more thereof, preferably selected from the group consisting of polystyrene, polyethylene, and mixtures of two or more thereof. The catalyst according to any of embodiments 1 to 38, wherein the rhodium content of the catalyst is in the range of from 0.1 to 15 wt.-%, calculated as the element, preferably from 0.2 to 14 wt.-%, more preferably from 0.3 to 13 wt.-%, more preferably from 0.4 to 12 wt.-%, more preferably from 0.5 to 11 wt.-%, more preferably from 0.6 to 10 wt.-%, more preferably from 0.7 to 5 wt.-%, more preferably from 0.8 to 2 wt.-%, more preferably from 0.9 to 1.5 wt.- %, based on 100 wt.-% of the catalyst. The catalyst according to any of embodiments 1 and 11 to 39, wherein independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.1 to 5, preferably from 0.5 to 3, more preferably from 0.6 to 2, more preferably from 0.7 to 1 .8, more preferably from 0.8 to 1 .7. The catalyst according to any of embodiments 1 and 11 to 40, wherein independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.5 to 2.0, preferably from 0.7 to 1.1 , more preferably from 0.8 to 1.0, more preferably from 0.85 to 0.95. The catalyst according to any of embodiments 1 and 11 to 41 , wherein independently from each other the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from

[0254] 1 to 2.5, preferably from 1 .4 to 1.9, more preferably from 1 .5 to 1.8, more preferably from 1.6 to 1.7. The catalyst according to any of embodiments 1 to 42, wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, preferably from 0.5 to 8 nm, more preferably from 1 to 6 nm, more preferably from 1 .5 to 5 nm, wherein the particle size is preferably measure according to reference example 4. The catalyst according to any of embodiments 1 and 11 to 43, wherein the one or more rhodium sulfides is Rhi7Si5and wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, preferably from 0.5 to 8 nm, more preferably from 1 to 6 nm, more preferably from 1 .5 to 5 nm, wherein the particle size is preferably measure according to reference example 4. The catalyst according to embodiment 44, wherein the particle size distribution D90 of the catalyst is in the range of from 0.1 to 10 nm, preferably from 1 to 5 nm, more preferably from

[0255] 2 to 4 nm, more preferably from 2.5 to 3.5 nm. The catalyst according to embodiment 44, wherein the particle size distribution D90 of the catalyst is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm. 47. The catalyst according to embodiment 44, wherein the particle size distribution D90 of the catalyst is in the range of from 1 to 25 nm, preferably from 5 to 20 nm, more preferably from 8 to 14 nm, more preferably from 10 to 12 nm.

[0256] 48. The catalyst according to any of embodiments 44 to 47, wherein the particle size distribution D10 of the catalyst according to (2) is in the range of from 0.5 to 3 nm, preferably from 1 to 2 nm, more preferably from 1.1 to 1.9 nm, more preferably from 1 .3 to 1.7 nm.

[0257] 49. The catalyst according to any of embodiments 44 to 47, wherein the particle size distribution D10 of the catalyst according to (2) is in the range of from 1 to 3.5 nm, preferably from 1 .5 to

[0258] 2.5 nm, more preferably from 1.7 to 2.3 nm, more preferably from 1 .9 to 2.2 nm.

[0259] 50. The catalyst according to any of embodiments 44 to 47, wherein the volume based particle size distribution D10 of the catalyst according to (2) is in the range of from 2 to 4.5 nm, preferably from 2.5 to 3.5 nm, more preferably from 2.7 to 3.3 nm, more preferably from 2.9 to 3.1 nm.

[0260] 51 . The catalyst according to any of embodiments 1 and 11 to 42, wherein the one or more rhodium sulfides is Rf^Ss and wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, preferably from 2 to 4 nm, more preferably from 2.3 to 3.7 nm, more preferably from 2.5 to 3.5 nm, wherein the particle size is preferably measure according to reference example 4.

[0261] 52. The catalyst according to embodiment 51 , wherein the particle size distribution D90 of the catalyst is in the range of from 0.1 to 10 nm, preferably from 1 to 8 nm, more preferably from 2 to 6 nm, more preferably from 3 to 5 nm.

[0262] 53. The catalyst according to embodiment 51 , wherein the particle size distribution D90 of the catalyst is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm.

[0263] 54. The catalyst according to any of embodiments 51 to 53, wherein the particle size distribution D10 of the catalyst according to (2) is in the range of from 1 to 4 nm, preferably from 1 .5 to 3 nm, more preferably from 2 to 2.5 nm, more preferably from 2.1 to 2.4 nm.

[0264] 55. The catalyst according to any of embodiments 51 to 53, wherein the particle size distribution D10 of the catalyst according to (2) is in the range of from 1 to 3 nm, preferably from 1 .4 to

[0265] 2.6 nm, more preferably from 1 .6 to 2.4 nm, more preferably from 1.8 to 2.2 nm.

[0266] 56. The catalyst according to any of embodiments 1 and 11 to 55, wherein the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 31° 20 [Cu K alpha], a second diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1.

[0267] 57. The catalyst according to any of embodiments 1 and 11 to 56, wherein the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 28° 20 [Cu K alpha], a second diffraction angle in the range of from 29 to 31 ° 20 [Cu K alpha], a third diffraction angle in the range of from 40 to 42° 20 [Cu K alpha], a fourth diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a fifth diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], a sixth diffraction angle in the range of from 72 to 75° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1.

[0268] 58. The catalyst according to any of embodiments 1 and 11 to 55, wherein the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 32° 20 [Cu K alpha], a second diffraction angle in the range of from 40 to 44° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1.

[0269] 59. The catalyst according to any of embodiments 1 and 11 to 58, wherein the phase purity of the one or more rhodium sulfides is in the range of from 100 to 10 %, preferably in the range of from 95 to 30 %, more preferably in the range of from 90 to 50%, wherein the phase purity is preferably determined according to Rietveld refinement of the X-ray diffraction pattern or the electron diffraction pattern.

[0270] 60. The catalyst according to any of embodiments 1 to 59, wherein the catalyst further comprises one or more promotors, preferably wherein the one or more promotors are sulfides selected from the group consisting of Sc, Y, lanthanide , Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Ni, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Ge, Si, Sn, Pb, Sb, As, Se, and Te.

[0271] 61 . The catalyst according to embodiment 60, wherein the molar ratio of Rh, calculated as the element, to the one or more promotors is in the range of from 0.01 :1 to 100:1 , preferably in the range of from 0.1 :1 to 10:1 , more preferably in the range of from 1 :1 to 5:1.

[0272] 62. A process for the preparation of a catalyst comprising rhodium, sulfur, preferably one or more rhodium sulfides, and preferably a catalyst support, preferably a catalyst according to any of embodiments 1 to 61 , wherein the process comprises,

[0273] (2.1) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents, obtaining a precursor solution; (2.2) impregnating a support material with the precursor solution obtained according to (2.1 ), obtaining an impregnated material;

[0274] (2.3) optionally drying the impregnated material obtained according to (2.2);

[0275] (2.4) subjecting the impregnated material obtained according to (2.2) or (2.3) to a thermal treatment under a gas atmosphere.

[0276] 63. The process according to embodiment 62, wherein the thermal treatment in (2.4) is conducted at a temperature in the range of from 300 to 750 °C, preferably from 400 to 745°C, more preferably from 500 to 740°C, more preferably from 600 to 730°C, more preferably from 650 to 720°C, more preferably from 670 to 715°C.

[0277] 64. The process according to embodiments 62 or 63 wherein the thermal treatment in (2.4) is conducted for a duration in the range of from 1 to 24 h, preferably from 3 to 12 h, more preferably from 4 to 8 h.

[0278] 65. The process according to any of embodiments 62 to 64, wherein the preparation of the catalyst according to (2) comprises,

[0279] (2.T) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents;

[0280] (2.2’) heating the mixture obtained according to (2.T) under mixing;

[0281] (2.3’) separating the liquid phase from the mixture obtained according to (2.2’), obtaining a solid material;

[0282] (2.4’) washing the solid material obtained according to (2.3’);

[0283] (2.5’) optionally drying the solid material obtained according to (2.4’);

[0284] (2.6’) subjecting the solid material obtained according to (2.4’) or (2.5’) to a thermal treatment.

[0285] 66. The process according to embodiment 65, wherein separating in (2.3’) is conducted by filtration or centrifugation, preferably centrifugation.

[0286] 67. The process according to embodiment 65 or 66, wherein the thermal treatment in (2.6’) is conducted at a temperature in the range of from 200 to 550 °C, preferably from 300 to 545°C, more preferably from 350 to 540°C, more preferably from 400 to 535°C, more preferably from 450 to 530°C, more preferably from 470 to 520°C.

[0287] 68. The process according to any of embodiments 65 to 67, wherein the thermal treatment in (2.6’) is conducted for a duration in the range of from 1 to 10 h, preferably from 2 to 8 h, more preferably from 3 to 6 h.

[0288] 69. The process according to embodiment 65 or 66, wherein the thermal treatment in (2.6’) is conducted at a temperature in the range of from 700 to 1000°C, preferably from 800 to 950°C, more preferably from 850 to 930°C, more preferably from 870 to 920°C. 70. The process according to embodiment 69, wherein the thermal treatment in (2.6’) is conducted for a duration in the range of from 10 to 300 min, preferably of from 20 to 200 min, more preferably of from 50 to 120 min, more preferably of from 70 to 100 min.

[0289] 71 . The process according to any of embodiments 62 to 70, wherein independently from each other the thermal treatment in (2.4) and (2.6’) is performed under an inert gas atmosphere, wherein the inert gas atmosphere in (2.4) or (2.6’) preferably comprises argon or nitrogen, more preferably argon.

[0290] 72. The process according to any of embodiments 65 to 71 , wherein mixing in (2.2’) is conducted at a temperature in the range of from 100 to 300°C, preferably from 130 to 250°C, more preferably from 150 to 230°C, more preferably from 170 to 210°C.

[0291] 73. The process according to any of embodiments 65 to 72, wherein mixing in (2.2’) is conducted for a duration in the range of from 1 to 24 h, preferably from 5 to 20 h, more preferably from 10 to 15h.

[0292] 74. The process according to any of embodiments 62 to 73, wherein independently from each other the one or more rhodium sources according to (2.1) or (2.T) are rhodium salts, wherein preferably the one or more rhodium sources are selected from the group consisting of rhodium acetate, rhodium chloride, rhodium nitrate, rhodium acetyl acetonate, rhodium phosphate, hexarhodiumhexadecacarbonyl, rhodium carbonyl chloride, rhodium bromide, rhodium triflouride, rhodium iodide, rhodium sulfate, rhodium perchlorate, rhodium oxide, rhodium hydroxide, or mixtures of two or more thereof, more preferably selected from the group consisting of rhodium acetate, rhodium acetyl acetonate, or mixtures thereof, more preferably wherein the one or more rhodium sources are rhodium acetate.

[0293] 75. The process according to any of embodiments 62 to 74, wherein independently from each other the one or more sulfur sources according to (2.1 ) or (2.T) are sulfur containing compounds, wherein preferably the one or more sulfur sources are selected from the group consisting of thiourea, ammonium sulfide, ammonium bisulfate, ammonium thiosulfate, hydrogen sulfide, carbonyl sulfide, sulfuryl fluoride, sodium sulfide, sodium thiosulfate, dimethyl sulfide, sodium sulfate, ammonium sulfate, thiol, thioether, sulfonic acid, or mixtures of two or more thereof, more preferably selected from the group consisting of thiourea, ammonium thiosulfate, or mixtures thereof, more preferably wherein the one or more sulfur sources are thiourea.

[0294] 76. The process according to any of embodiments 62 to 75, wherein independently from each other the one or more solvents according to (2.1 ) or (2.T) are selected from the group consisting of water, diethylene glycol, acetaldehyde, acetone, ethanol, ethylene glycol, glycerol, methanol, 1 -propanol, 2-propanol, or mixtures of two or more thereof, preferably selected from water, diethylene glycol, acetone, ethanol, 2-propanol, or mixtures of two or more thereof, more preferably selected from water, diethylene glycol, 2-propanol, or mixtures of two or more thereof.

[0295] 77. The process according to any of embodiments 62 to 76, wherein independently from each other drying in (3.3) or (3.5’) is conducted at a temperature in the range of from 5 to 200°C, preferably from 10 to 150°C, more preferably from 15 to 100°C, more preferably from 20 to 80 °C.

[0296] 78. The process according to any of embodiments 62 to 77, wherein independently from each other heating in (2.4), or (2.6’) is performed under a gas atmosphere, wherein the gas atmosphere in (2.4) or (2.6’) preferably comprises an inert gas, more preferably nitrogen and / or argon, more preferably comprises argon.

[0297] 79. The process according to any of embodiments 62 to 78, wherein independently from each other during (2.2) or (2. T) 30 to 75 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1 ), is added to the mixture, preferably 35 to 70 wt.-% or , more preferably 40 to 65 wt.-% or , more preferably 45 to 60 wt.-% or more, more preferably 50 to 55 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1 ), is added to the mixture.

[0298] 80. The process according to any of embodiments 62 to 79, wherein the impregnated material obtained according to (2.4) comprises at least one or more crystalline or partially crystalline rhodium sulfides.

[0299] 81 . A catalyst comprising rhodium, sulfur, preferably at least one or more rhodium sulfides, and a catalyst support, as obtained or obtainable according to any of embodiments 62 to 80.

[0300] 82. A process for the hydroformylation of olefins comprising, preferably consisting of,

[0301] (1 ) providing a mixture comprising one or more olefins, carbon monoxide, and hydrogen;

[0302] (2) providing a catalyst comprising rhodium, sulfur, and preferably a catalyst support, more preferably the catalyst according to any one of claims 1 to 77;

[0303] (3) subjecting the mixture provided according to (1 ) to hydroformylation conditions in a reaction space S, said conditions comprising contacting the mixture according to (1 ) with the catalyst provided according to (2), obtaining a reaction mixture comprising one or more aldehydes.

[0304] 83. The process according to embodiment 82, wherein the one or more olefins have a C2 to C30 carbon chain forming the backbone of the one or more olefins, preferably a C2 to C20 carbon chain, more preferably wherein the one or more olefins have a C3 to C10 carbon chain forming the backbone of the one or more olefins.

[0305] 84. The process according to embodiment 82 or 83, wherein the one or more olefins are selected from the group consisting of branched and unbranched olefins, including mixtures thereof, wherein preferably the one or more olefins are selected from the group consisting of unbranched olefins, including mixtures thereof.

[0306] 85. The process according to embodiments 82 to 84, wherein the one or more olefins are alpha olefins.

[0307] 86. The process according to any one of embodiments 82 to 85, wherein independently from one another, the one or more olefins contain one or more C-C double bonds, preferably one to three C-C double bonds, more preferably one or two C-C double bonds, more preferably one C-C double bond.

[0308] 87. The process according to any one of embodiments 82 to 86, wherein the one or more olefins comprise one or more aromatic groups, wherein the aromatic group is preferably a benzyl group.

[0309] 88. The process according to any one of embodiments 82 to 87, wherein the one or more olefins are selected from the group consisting of branched and / or unbranched, preferably unbranched, ethylene, propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -heptene, 1 -octene, 1-de- cene, 1 -dodecene, 1 -octadecene, and styrene, preferably from the group consisting of 1-oc- tene and styrene.

[0310] 89. The process according to any of embodiments 82 to 88, wherein contacting in (3) is conducted in a fixed bed reactor or a fluidized bed reactor, preferably in a fixed bed reactor, most preferably all reactants in the fixed bed reactor are in gaseous phase.

[0311] 90. The process according to any of embodiments 82 to 89, wherein contacting in (3) is conducted in a stirred tank, a trickle bed reactor or a bubble column, preferably in a stirred tank or a trickle bed reactor.

[0312] 91 . The process according to any of embodiments 82 to 90, wherein the temperature in the reaction space S is in the range of from 30 to 200°C, preferably from 40 to 150°C, more preferably from 50 to 110°C, more preferably from 60 to 100°C, more preferably from 70 to 90°C.

[0313] 92. The process according to any of embodiments 82 to 91 , wherein the pressure in the reaction space S is in the range of from 1 to 100 bar, preferably from 10 to 80 bar, more preferably from 20 to 60 bar, more preferably from 30 to 50 bar.

[0314] 93. The process according to any of embodiments 82 to 92, wherein the reaction time in the reaction space S is in the range of from 0.1 to 12 h, preferably from 0.1 to 9 h, more preferably from 0.5 to 5 h, more preferably from 0.75 to 3 h, more preferably from 1 to 2 h. 94. The process according to any of embodiments 82 to 93, wherein the conversion rate of the one or more olefins is 40% or higher, preferably 50% or higher, more preferably 60% or higher, more preferably 70% or higher, more preferably 80% or higher, more preferably 90% or higher.

[0315] 95. The process according to any of embodiments 82 to 94, wherein the one or more aldehydes comprised in the reaction mixture obtained in (3) comprise one or more unbranched and / or branched aldehydes, preferably one or more unbranched aldehydes.

[0316] 96. The process according to embodiment 95, wherein the molar ratio of unbranched to branched aldehydes is 0.5 or higher, preferably 0.6 or higher, more preferably 0.7 or higher, more preferably 0.8 or higher, more preferably 0.9 or higher.

[0317] 97. The process according to any of embodiments 82 to 96, further comprising

[0318] (5) removing a product mixture from the reaction space S, wherein the reaction mixture comprises the one or more aldehydes.

[0319] 98. The process according to embodiment 97, further comprising

[0320] (6) separating the one or more aldehydes from the reaction mixture.

[0321] 99. The process according to embodiment 98, wherein separating the one or more aldehydes according to (6) is conducted by distillation, preferably fractionated distillation.

[0322] 100. The process according to any of embodiments 82 to 99, wherein the reaction mixture is substantially free of hydrogenation products of the one or more olefins, preferably wherein the content of hydrogenation products is 10% or less, preferably 5% or less, more preferably 4% or less, more preferably 3% or less, based on the total amount of the reaction mixture, wherein preferably the hydrogenation products comprise one or more compounds selected from the group consisting of propane, 1 -butane, 1 -pentane, 1 -hexane, 1 -heptane, 1 -octane,

[0323] 1 -decane, 1-dodacene, 1-octadacene, and ethylbenzene.

[0324] 101 . The process according to any of embodiments 82 to 100, wherein the reaction space S is a batch reactor, preferably a stirred tank reactor.

[0325] 102. The process according to any of embodiments 82 to 101 , wherein the reaction space S is a continuous reactor, preferably a tubular reactor or a continuous stirred tank reactor.

[0326] 103. The process according to any of embodiments 82 to 102, wherein the molar ratio of CO:H2 comprised in the mixture according to (1) is in the range of from 1 :0.75 to 1 :3, preferably from 1 :0.8 to 1 :2, more preferably from 1 :0.85 to 1 :1.5, more preferably from 1 :0.9 to 1 :1.2.

[0327] 104. The process according to any of embodiments 82 to 103, wherein the weight ratio of Rh to the one or more olefins in the reaction space according to (3) is in the range of from 1 :100 to 1 :900, preferably from 1 :200 to 1 :800, more preferably from 1 :300 to 1 :700, more preferably from 1 :400 to 1 :600.

[0328] 105. Use of a catalyst according to any of embodiments 1 to 61 or 81 as a catalyst in the conversion of olefins to aldehydes.

[0329] The present invention is further illustrated by the following second set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. The second set of embodiments may be combined with the first set of embodiments above.

[0330] 1 °. A catalyst comprising one or more rhodium sulfides and a catalyst support, wherein the average particle size (D50) of the catalyst is in the range of from 100 to 1000 pm, wherein the particle size is preferably measured according to reference example 4.

[0331] 2°. The catalyst according to embodiment 1 °, wherein the one or more rhodium sulfides are selected from the group consisting of Rhi7Si5, RhsS i, and Rf^Ss, and mixtures thereof, preferably from RhiySis and Rf^Ss, and mixtures thereof, more preferably wherein the one or more rhodium sulfides is Rhi7Si5.

[0332] 3°. The catalyst according to embodiment 1 ° or 2°, wherein the one or more rhodium sulfides are located on the surface of the catalyst, wherein said surface of the catalyst comprising one or more rhodium sulfides comprises a first structure motive according to formula (I) comprising 4 adjacent rhodium atoms Rh(1 ) to Rh(4) in a planar or substantially planar ring arrangement: wherein all of the rhodium atoms Rh(1 ) to Rh(4) are in the outermost layer of atoms forming the outer surface of the one or more rhodium sulfides, wherein the first structure motive comprises a first Rh(1 )-Rh(2)-Rh(3) angle in the range of from 55.0 to 65.0°, and a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 105.0 to 120.0, wherein preferably the geometry of the ring arrangement according to formula (II) and the angles of the first structure motive are determined according to reference example 6.

[0333] 4°. The catalyst according to embodiment 3°, wherein the first structure motive comprises a first Rh(1 )-Rh(2)-Rh(3) angle in the range of from 57.0 to 63.0°, preferably from 58.0 to 62.0°, more preferably from 59.0 to 61.0 °, wherein preferably the first Rh(1)-Rh(2)-Rh(3) angle of the first structure motive is determined according to reference example 6. 5°. The catalyst according to embodiment 3° or 4°, wherein the first structure motive comprises a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 110.0 to 116.0°, preferably from 111 .0 to 115.0°, more preferably from 112.0 to 114.0°, wherein preferably the second Rh(2)-Rh(3)-Rh(4) angle of the first structure motive is determined according to reference example 6.

[0334] 6°. The catalyst according to any one of embodiments 3° to 5°, wherein the ring arrangement of rhodium atoms Rh(1) to Rh(4) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(1), Rh(2), and Rh(4) and the plane defined by Rh(2), Rh(3), and Rh(4) or the dihedral angle between the plane defined by Rh(1), Rh(2), and Rh(3) and the plane defined by Rh(1), Rh(3), and Rh(4) deviates from 180° in the range of from -15 to 15°, preferably in the range of from -12 to 12°, wherein preferably the dihedral angles of the first structure motive are determined according to reference example 6.

[0335] 7°. The catalyst according to any of embodiments 3° to 6°, wherein the first structure motive comprises a first rhodium-rhodium distance Rh(1)-Rh(2) in the range of from 2.50 to 2.65 Aand a second rhodium-rhodium distance Rh(2)-Rh(3) in the range of from 2.70 to 2.90 A, wherein preferably the rhodium-rhodium distances of the first structure motive are determined according to reference example 6.

[0336] 8°. The catalyst according to embodiment 7°, wherein the first rhodium-rhodium distance Rh(1)- Rh(2) is in the range of from 2.54 to 2.62 A, preferably from 2.55 to 2.61 A, more preferably from 2.56 to 2.60 A, wherein preferably the first rhodium-rhodium distance Rh(1)-Rh(2) of the first structure motive is determined according to reference example 6.

[0337] 9°. The catalyst according to embodiment 7° or 8°, wherein the second rhodium-rhodium distance Rh(2)-Rh(3) is in the range of from 2.75 to 2.85 A, preferably from 2.76 to 2.84 A, more preferably from 2.77 to 2.83 A, wherein preferably the second rhodium-rhodium distance Rh(2)-Rh(3) of the first structure motive is determined according to reference example 6.

[0338] 10°. The catalyst according to any of embodiments 3° to 9°, wherein the one or more rhodium sulfides are selected from the group consisting of hi7Si5, RhsSi, and Rf^Ss, and mixtures thereof, preferably from hi7Si5and Rf^Ss, and mixtures thereof, more preferably wherein the one or more rhodium sulfides comprise, preferably consist of, RhnSis.

[0339] 11 °. The catalyst according to any of embodiments 3° to 10°, wherein the ring arrangement of the first structure motive forms a rhomboid.

[0340] 12°. The catalyst according to any of embodiments 3° to 11 °, wherein the surface is the (100) surface plane of the one or more rhodium sulfides. °. The catalyst according to any of embodiments 3° to 12°, wherein the first structure motive is comprised in a 3x3x1 supercell. °. The catalyst according to embodiment 13°, wherein the 3x3x1 supercell comprises, preferably consists of, 8 rhodium atoms. °. The catalyst according to any of embodiments 3° to 14°, wherein the catalyst further comprises a second structure motive comprising 4 adjacent rhodium atoms Rh(5) to Rh(8) in a planar or substantially planar ring arrangement, according to formula (II): wherein all of the rhodium atoms Rh(1) to Rh(8) are in the outermost layer of atoms forming the outer surface of the one or more rhodium sulfides comprising the first structure motive in said outermost layer, wherein preferably the geometry of the ring arrangement according to formula (II) is determined according to reference example 6. °. The catalyst according to embodiment 15°, wherein the ring arrangement of rhodium atoms Rh(5) to Rh(8) is substantially planar, and wherein the dihedral angle between the plane defined by Rh(5), Rh(6), and Rh(8) and the plane defined by Rh(6), Rh(7), and Rh(8) or between the plane defined by Rh(5), Rh(6), and Rh(7) and the plane defined by Rh(5), Rh(7), and Rh(8) deviates from 180° in the range of from -10 to 10°, preferably in the range of from -6 to 6°, wherein preferably the dihedral angles of the second structure motive are determined according to reference example 6. °. The catalyst according to embodiment 15° or 16°, wherein the first structure motive and the second structure motive do not have any rhodium atoms in common. °. The catalyst according to any of embodiments 15° to 17°, wherein the ring arrangement of the second structure motive forms a rhomboid. °. The catalyst according to any of embodiments 15° to 18°, wherein the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)-Rh(8) angle in the range of from 93.0 to 104.0°, wherein preferably the angles of the second structure motive are determined according to reference example 6. °. The catalyst according to embodiment 19°, wherein the first Rh(5)-Rh(6)-Rh(7) angle is in the range of from 78.0 to 85.0°, preferably from 80.0 to 83.0 °, wherein preferably the first Rh(5)-Rh(6)-Rh(7) angle of the second structure motive is determined according to reference example 6. °. The catalyst according to embodiment 19° or 20°, wherein the second Rh(6)-Rh(7)-Rh(8) angle is in the range of from 95.0 to 102.0°, preferably from 97.0 to 100.0°, wherein preferably the second Rh(6)-Rh(7)-Rh(8) angle of the second structure motive is determined according to reference example 6. °. The catalyst according to any of embodiments 15° to 21 °, wherein the second structure motive comprises a first rhodium-rhodium distance Rh(5)-Rh(6) in the range of from 2.48 to 2.58 A, preferably from 2.50 to 2.56 A, more preferably from 2.52 to 2.54 A, and a second rhodium-rhodium distance Rh(6)-Rh(7) in the range of from 2.70 to 3.00 A, preferably from 2.75 to 2.95 A, more preferably from 2.80 to 2.90 A, wherein preferably the rhodium- rhodium distances of the second structure motive are determined according to reference example 6. °. The catalyst according to any of embodiments 3° to 22°, wherein the one or more rhodium sulfides display a cubic crystal structure, preferably wherein the space group of the unit cell is Pm3m. °. The catalyst according to any of embodiments 3° to 23°, wherein the catalyst further comprises one or more ligands, wherein the one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive, preferably to Rh(1) or Rh(3) of the first structure motive. °. The catalyst according to embodiment 24°, wherein one or more ligands are coordinated and / or bonded, preferably bonded, to the first structure motive. °. The catalyst according to embodiment 24° or 25°, wherein the one or more ligands are selected from the group consisting of anionic ligands, cationic ligands, and neutral ligands. °. The catalyst according to any of embodiments 24° to 26°, wherein the ligand is selected from the group consisting of carbon monoxide, nitrogen monoxide, water, and ammonia, preferably selected from the group consisting of carbon monoxide, and nitrogen monoxide, wherein more preferably the one or more ligands are carbon monoxide. °. The catalyst according to any of embodiments 24° to 27°, wherein the one or more ligands are selected from the group consisting of nitrogen monoxide, water, and ammonia, wherein preferably the one or more ligands are nitrogen monoxide. °. The catalyst according to any of embodiments 3° to 23°, wherein no ligand is coordinated and / or bonded, preferably bonded, to the first structure motive. °. The catalyst according to any of embodiments 3° to 23°, wherein the catalyst is substantially free of carbon monoxide, preferably wherein the catalyst is free of carbon monoxide. °. The catalyst according to any of embodiments 1 ° to 30°, wherein the average particle size (D50) of the catalyst is in the range of from 0.1 to 10 nm, wherein the particle size is preferably measured according to reference example 4. °. The catalyst according to any of embodiments 1 ° to 31 °, wherein the catalyst is a heterogeneous catalyst. °. The catalyst according to any of embodiments 1 ° to 34°, wherein the catalyst support, preferably a particulate catalyst support, is an oxidic catalyst support, preferably wherein the oxidic catalyst support comprises, more preferably consists of, a metal oxide and / or metalloid oxide, preferably wherein the metal of the metal oxide and / or metalloid oxide catalyst support is selected from the group consisting of Zr, Al, Si, Ti, La, Ce, Nd, Y, Pr, and mixtures of two or more thereof, more preferably selected from the group consisting of Zr, Al, Si, La, Ce, Y and mixtures of two or more thereof, more preferably selected from the group consisting of Zr, Si and mixtures of two or more thereof, more preferably wherein the metal of the metal oxide and / or metalloid oxide catalyst support comprises, preferably consists of, Si, more preferably wherein the catalyst support is selected from the group consisting of ZrC>2, AI2O3, SiC>2, TiC>2, La2Os-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2C>3-doped CeO2-ZrO2 mixed oxide, Nd2Os-doped CeO2-ZrO2 mixed oxide, Y2O3- doped CeO2-ZrC>2 mixed oxide, P^Os-doped CeO2-ZrO2 mixed oxide, ZrC>2-doped AI2O3, ZrC>2-doped SiC>2, SiC>2-doped AI2O3, and mixtures of two or more thereof, more preferably from the group consisting of ZrC>2, SiC>2, La2Os-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2C>3-doped CeO2-ZrO2 mixed oxide, Nd2Os-doped CeO2-ZrO2 mixed oxide, Y2Os-doped CeO2-ZrC>2 mixed oxide, P^Os-doped CeO2-ZrO2 mixed oxide, ZrC>2-doped SiC>2, and mixtures of two or more thereof, more preferably from the group consisting of SiC>2, ZrC>2- doped SiC>2, and mixtures of two or more thereof. °. The catalyst according to any of embodiments 10to 33°, wherein the catalyst support exhibits an average particle size (D50) in the range of from 200 to 600 pm, preferably in the range of from 210 to 580 pm, more preferably in the range of from 220 to 560 pm, more preferably in the range of from 230 to 540 pm, more preferably in the range of from 240 to 520 pm, more preferably in the range of from 200 to 500 pm, wherein the average particle size is preferably measured according to reference example 4. °. The catalyst according to any of embodiments 10to 34°, wherein the catalyst support exhibits a BET surface area in the range of from 300 to 700 m2 / g, preferably in the range of from 400 to 600 m2 / g, more preferably in the range of from 420 to 580 m2 / g, more preferably in the range of from 440 to 560 m2 / g, more preferably in the range of from 460 to 540 m2 / g, more preferably in the range of from 480 to 520 m2 / g, wherein the BET surface area is preferably measured according to reference example 7. 36°. The catalyst according to any of embodiments 1 ° to 35°, wherein the catalyst support exhibits an average pore diameter in the range of from 10 to 100 A, preferably in the range of from 30 to 90 A, more preferably in the rage of from 40 to 80 A, more preferably in the range of from 50 to 70 A,, wherein the average pore diameter is preferably measured according to reference example 7.

[0341] 37°. The catalyst according to any of embodiments 1 ° to 32°, wherein the catalyst support is selected from the group consisting of activated carbon, graphite, carbide, and mixtures of two or more thereof, preferably activated carbon, graphite, silicon carbide, boron carbide, tungsten carbide, and mixtures of two or more thereof.

[0342] 38°. The catalyst according to any of embodiments 1 ° to 32°, wherein the catalyst support, preferably a porous catalyst support, is selected from the group of metal organic frameworks (MOF) and zeolites, preferably wherein the catalyst support is a zeolite.

[0343] 39°. The catalyst according to any of embodiments 1 ° to 32°, wherein the catalyst support is a polymer, preferably wherein the polymer is selected from the group consisting of polyolefins, polyamide, polyester, polyacrylate, polyethylene, polyurethane, polyvinylpyrrolidone, polystyrene, and mixtures of two or more thereof, preferably selected from the group consisting of polystyrene, polyethylene, and mixtures of two or more thereof.

[0344] 40°. The catalyst according to any of embodiments 1 ° to 39°, wherein the rhodium content of the catalyst is in the range of from 0.1 to 15 wt.-%, calculated as the element, preferably from 0.2 to 14 wt.-%, more preferably from 0.3 to 13 wt.-%, more preferably from 0.4 to 12 wt.-%, more preferably from 0.5 to 11 wt.-%, more preferably from 0.6 to 10 wt.-%, more preferably from 0.7 to 5 wt.-%, more preferably from 0.8 to 2 wt.-%, more preferably from 0.9 to 1.5 wt.-%, based on 100 wt.-% of the catalyst.

[0345] 41 °. The catalyst according to any of embodiments 1 ° to 40°, wherein the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.1 to 5, preferably from 0.5 to 3, more preferably from 0.6 to 2, more preferably from 0.7 to 1.8, more preferably from 0.8 to 1.7.

[0346] 42°. The catalyst according to any of embodiments 1 ° to 41°, wherein the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 0.5 to 2.0, preferably from 0.7 to 1.1 , more preferably from 0.8 to 1 .0, more preferably from 0.85 to 0.95.

[0347] 43°. The catalyst according to any of embodiments 1 ° to 42°, wherein the S:Rh molar ratio of the one or more rhodium sulfides is in the range of from 1 to 2.5, preferably from 1 .4 to 1 .9, more preferably from 1.5 to 1 .8, more preferably from 1.6 to 1 .7. °. The catalyst according to any of embodiments 1 ° to 43°, wherein the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 0.1 to 7 nm, more preferably from 0.1 to 6 nm, more preferably from 0.5 to 5 nm, wherein the particle size is preferably measure according to reference example 4. °. The catalyst according to any of embodiments 1 ° to 44°, wherein the one or more rhodium sulfides comprise, preferably consist of, Rhi7Si5and wherein the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 0.5 to 7 nm, more preferably from 1 to 6 nm, more preferably from 1.5 to 5 nm, wherein the particle size is preferably measure according to reference example 4. °. The catalyst according to embodiment 45°, wherein the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 1 to 5 nm, more preferably from 2 to 4 nm, more preferably from 2.5 to 3.5 nm, wherein the particle size is preferably measured according to reference example 4. °. The catalyst according to embodiment 45°, wherein the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm, wherein the particle size is preferably measured according to reference example 4. °. The catalyst according to embodiment 45°, wherein the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 1 to 25 nm, preferably from 5 to 20 nm, more preferably from 8 to 14 nm, more preferably from 10 to 12 nm, wherein the particle size is preferably measured according to reference example 4. °. The catalyst according to any of embodiments 45° to 48°, wherein the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 0.5 to 3 nm, preferably from 1 to 2 nm, more preferably from 1 .1 to 1 .9 nm, more preferably from 1 .3 to 1 .7 nm, wherein the particle size is preferably measured according to reference example 4. °. The catalyst according to any of embodiments 45° to 48°, wherein the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 1 to 3.5 nm, preferably from 1 .5 to 2.5 nm, more preferably from 1 .7 to 2.3 nm, more preferably from 1 .9 to 2.2 nm, wherein the particle size is preferably measured according to reference example 4. °. The catalyst according to any of embodiments 45° to 48°, wherein the volume based particle size distribution D10 of the one or more rhodium sulfides is in the range of from 2 to 4.5 nm, preferably from 2.5 to 3.5 nm, more preferably from 2.7 to 3.3 nm, more preferably from 2.9 to 3.1 nm, wherein the particle size is preferably measured according to reference example 4. 52°. The catalyst according to any of embodiments 1 ° to 44° wherein the one or more rhodium sulfides is Rf^Ss and wherein the average particle size (D50) of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 2 to 4 nm, more preferably from 2.3 to 3.7 nm, more preferably from 2.5 to 3.5 nm, wherein the particle size is preferably measured according to reference example 4.

[0348] 53°. The catalyst according to embodiment 52°, wherein the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 10 nm, preferably from 1 to 8 nm, more preferably from 2 to 6 nm, more preferably from 3 to 5 nm, wherein the particle size is preferably measured according to reference example 4.

[0349] 54°. The catalyst according to embodiment 51 °, wherein the particle size distribution D90 of the one or more rhodium sulfides is in the range of from 0.1 to 15 nm, preferably from 1 to 10 nm, more preferably from 4 to 7 nm, more preferably from 5 to 6 nm, wherein the particle size is preferably measured according to reference example 4.

[0350] 55°. The catalyst according to any of embodiments 52° to 54°, wherein the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 1 to 4 nm, preferably from 1.5 to 3 nm, more preferably from 2 to 2.5 nm, more preferably from 2.1 to 2.4 nm, wherein the particle size is preferably measured according to reference example 4.

[0351] 56°. The catalyst according to any of embodiments 52° to 54°, wherein the particle size distribution D10 of the one or more rhodium sulfides is in the range of from 1 to 3 nm, preferably from 1.4 to 2.6 nm, more preferably from 1.6 to 2.4 nm, more preferably from 1.8 to 2.2 nm, wherein the particle size is preferably measured according to reference example 4.

[0352] 57°. The catalyst according to any of embodiments 1 ° to 56°, wherein the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 31 ° 20 [Cu K alpha], a second diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 .

[0353] 58°. The catalyst according to any of embodiments 1 ° to 57°, wherein the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 28° 20 [Cu K alpha], a second diffraction angle in the range of from 29 to 31° 20 [Cu K alpha], a third diffraction angle in the range of from 40 to 42° 20 [Cu K alpha], a fourth diffraction angle in the range of from 45 to 49° 20 [Cu K alpha], a fifth diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], a sixth diffraction angle in the range of from 72 to 75° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 . °. The catalyst according to any of embodiments 1 ° to 57°, wherein the one or more rhodium sulfides comprised in the catalyst display an X-ray diffraction pattern comprising a first diffraction angle in the range of from 27 to 32° 20 [Cu K alpha], a second diffraction angle in the range of from 40 to 44° 20 [Cu K alpha], a third diffraction angle in the range of from 50 to 54° 20 [Cu K alpha], wherein the X-ray diffraction pattern is preferably determined according to reference example 1 . °. The catalyst according to any of embodiments 1 ° to 59°, wherein the phase purity of the one or more rhodium sulfides is in the range of from 100 to 10 %, preferably in the range of from 95 to 30 %, more preferably in the range of from 90 to 50%, wherein the phase purity is preferably determined according to Rietveld refinement of the X-ray diffraction pattern or the electron diffraction pattern. °. The catalyst according to any of embodiments 1 ° to 60°, wherein the catalyst further comprises one or more promotors, preferably wherein the one or more promotors are sulfides selected from the group consisting of Sc, Y, lanthanide , Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Ni, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Ge, Si, Sn, Pb, Sb, As, Se, and Te. °. The catalyst according to embodiment 61 °, wherein the molar ratio of Rh, calculated as the element, to the one or more promotors is in the range of from 0.01 :1 to 100:1 , preferably in the range of from 0.1 :1 to 10: 1 , more preferably in the range of from 1 :1 to 5: 1 . °. A process for the preparation of a catalyst comprising one or more rhodium sulfides and a catalyst support, preferably a catalyst according to any of embodiments 1 ° to 62°, wherein the process comprises,

[0354] (2.1) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents, obtaining a precursor solution;

[0355] (2.2) impregnating a support material with the precursor solution obtained according to (2.1 ), obtaining an impregnated material;

[0356] (2.3) optionally drying the impregnated material obtained according to (2.2);

[0357] (2.4) subjecting the impregnated material obtained according to (2.2) or (2.3) to a thermal treatment under a gas atmosphere. °. The process according to embodiment 63°, wherein the thermal treatment in (2.4) is conducted at a temperature in the range of from 300 to 750 °C, preferably from 400 to 745°C, more preferably from 500 to 740°C, more preferably from 600 to 730°C, more preferably from 650 to 720°C, more preferably from 670 to 715°C. 65°. The process according to embodiments 63° or 64° wherein the thermal treatment in (2.4) is conducted for a duration in the range of from 1 to 24 h, preferably from 3 to 12 h, more preferably from 4 to 8 h.

[0358] 66°. The process according to any of embodiments 63° to 65°, wherein the preparation of the catalyst according to (2) comprises,

[0359] (2.T) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents;

[0360] (2.2’) heating the mixture obtained according to (2.T) under mixing;

[0361] (2.3’) separating the liquid phase from the mixture obtained according to (2.2’), obtaining a solid material;

[0362] (2.4’) washing the solid material obtained according to (2.3’);

[0363] (2.5’) optionally drying the solid material obtained according to (2.4’);

[0364] (2.6’) subjecting the solid material obtained according to (2.4’) or (2.5’) to a thermal treatment.

[0365] 67°. The process according to embodiment 66°, wherein separating in (2.3’) is conducted by filtration or centrifugation, preferably centrifugation.

[0366] 68°. The process according to embodiment 66° or 67°, wherein the thermal treatment in (2.6’) is conducted at a temperature in the range of from 200 to 550 °C, preferably from 300 to 545°C, more preferably from 350 to 540°C, more preferably from 400 to 535°C, more preferably from 450 to 530°C, more preferably from 470 to 520°C.

[0367] 69°. The process according to any of embodiments 66° to 68°, wherein the thermal treatment in (2.6’) is conducted for a duration in the range of from 1 to 10 h, preferably from 2 to 8 h, more preferably from 3 to 6 h.

[0368] 70°. The process according to embodiment 68° or 69°, wherein the thermal treatment in (2.6’) is conducted at a temperature in the range of from 700 to 1000°C, preferably from 800 to 950°C, more preferably from 850 to 930°C, more preferably from 870 to 920°C.

[0369] 71 °. The process according to embodiment 70°, wherein the thermal treatment in (2.6’) is conducted for a duration in the range of from 10 to 300 min, preferably of from 20 to 200 min, more preferably of from 50 to 120 min, more preferably of from 70 to 100 min.

[0370] 72°. The process according to any of embodiments 63° to 71 °, wherein independently from each other the thermal treatment in (2.4) and (2.6’) is performed under an inert gas atmosphere, wherein the inert gas atmosphere in (2.4) or (2.6’) preferably comprises argon or nitrogen, more preferably argon. 73°. The process according to any of embodiments 66° to 72°, wherein mixing in (2.2’) is conducted at a temperature in the range of from 100 to 300°C, preferably from 130 to 250°C, more preferably from 150 to 230°C, more preferably from 170 to 210°C.

[0371] 74°. The process according to any of embodiments 66° to 73°, wherein mixing in (2.2’) is conducted for a duration in the range of from 1 to 24 h, preferably from 5 to 20 h, more preferably from 10 to 15h.

[0372] 75°. The process according to any of embodiments 63° to 74°, wherein independently from each other the one or more rhodium sources according to (2.1) or (2.T) are rhodium salts, wherein preferably the one or more rhodium sources are selected from the group consisting of rhodium acetate, rhodium chloride, rhodium nitrate, rhodium acetyl acetonate, rhodium phosphate, hexarhodiumhexadecacarbonyl, rhodium carbonyl chloride, rhodium bromide, rhodium triflouride, rhodium iodide, rhodium sulfate, rhodium perchlorate, rhodium oxide, rhodium hydroxide, or mixtures of two or more thereof, more preferably selected from the group consisting of rhodium acetate, rhodium acetyl acetonate, or mixtures thereof, more preferably wherein the one or more rhodium sources are rhodium acetate.

[0373] 76°. The process according to any of embodiments 63° to 75°, wherein independently from each other the one or more sulfur sources according to (2.1 ) or (2.T) are sulfur containing compounds, wherein preferably the one or more sulfur sources are selected from the group consisting of thiourea, ammonium sulfide, ammonium bisulfate, ammonium thiosulfate, hydrogen sulfide, carbonyl sulfide, sulfuryl fluoride, sodium sulfide, sodium thiosulfate, dimethyl sulfide, sodium sulfate, ammonium sulfate, thiol, thioether, sulfonic acid, or mixtures of two or more thereof, more preferably selected from the group consisting of thiourea, ammonium thiosulfate, or mixtures thereof, more preferably wherein the one or more sulfur sources are thiourea.

[0374] 77°. The process according to any of embodiments 63° to 76°, wherein independently from each other the one or more solvents according to (2.1) or (2.T) are selected from the group consisting of water, diethylene glycol, acetaldehyde, acetone, ethanol, ethylene glycol, glycerol, methanol, 1 -propanol, 2-propanol, or mixtures of two or more thereof, preferably selected from water, diethylene glycol, acetone, ethanol, 2-propanol, or mixtures of two or more thereof, more preferably selected from water, diethylene glycol, 2-propanol, or mixtures of two or more thereof.

[0375] 78°. The process according to any of embodiments 63° to 77°, wherein independently from each other drying in (3.3) or (3.5’) is conducted at a temperature in the range of from 5 to 200°C, preferably from 10 to 150°C, more preferably from 15 to 100°C, more preferably from 20 to 80 °C.

[0376] 79°. The process according to any of embodiments 63° to 78°, wherein independently from each other heating in (2.4), or (2.6’) is performed under a gas atmosphere, wherein the gas atmosphere in (2.4) or (2.6’) preferably comprises an inert gas, more preferably nitrogen and / or argon, more preferably comprises argon.

[0377] 80°. The process according to any of embodiments 63° to 79°, wherein independently from each other during (2.2) or (2.T) 30 to 75 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1), is added to the mixture, preferably 35 to 70 wt.-% or , more preferably 40 to 65 wt.-% or, more preferably 45 to 60 wt.-% or more, more preferably 50 to 55 wt.-% of the one or more sulfur sources, based on 100 wt.-% of the one or more sulfur sources provided in (2.1 ), is added to the mixture.

[0378] 81 °. The process according to any of embodiments 63° to 80°, wherein the impregnated material obtained according to (2.4) comprises at least one or more crystalline or partially crystalline rhodium sulfides.

[0379] 82°. A catalyst comprising one or more rhodium sulfides and a catalyst support, as obtained or obtainable according to any of embodiments 63° to 81 °.

[0380] 83°. A process for the hydroformylation of olefins comprising, preferably consisting of,

[0381] (1 ) providing a mixture comprising one or more olefins, carbon monoxide, and hydrogen;

[0382] (2) providing a catalyst comprising one or more rhodium sulfides and a catalyst support, preferably the catalyst according to any one of claims 1 to 62°;

[0383] (3) subjecting the mixture provided according to (1 ) to hydroformylation conditions in a reaction space S, said conditions comprising contacting the mixture according to (1 ) with the catalyst provided according to (2), obtaining a reaction mixture comprising one or more aldehydes.

[0384] 84°. The process according to embodiment 83°, wherein the one or more olefins have a C2 to C30 carbon chain forming the backbone of the one or more olefins, preferably a C2 to C20 carbon chain, more preferably wherein the one or more olefins have a C3 to C10 carbon chain forming the backbone of the one or more olefins.

[0385] 85°. The process according to embodiment 83° or 84°, wherein the one or more olefins are selected from the group consisting of branched and unbranched olefins, including mixtures thereof, wherein preferably the one or more olefins are selected from the group consisting of unbranched olefins, including mixtures thereof.

[0386] 86°. The process according to embodiments 83° to 85°, wherein the one or more olefins are alpha olefins.

[0387] 87°. The process according to any one of embodiments 83° to 86°, wherein independently from one another, the one or more olefins contain one or more C-C double bonds, preferably one to three C-C double bonds, more preferably one or two C-C double bonds, more preferably one C-C double bond. 88°. The process according to any one of embodiments 83° to 87°, wherein the one or more olefins comprise one or more aromatic groups, wherein the aromatic group is preferably a benzyl group.

[0388] 89°. The process according to any one of embodiments 83° to 88°, wherein the one or more olefins are selected from the group consisting of branched and / or unbranched, preferably unbranched, ethylene, propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -heptene, 1 -octene, 1- decene, 1 -dodecene, 1 -octadecene, and styrene, preferably from the group consisting of 1 -octene and styrene.

[0389] 90°. The process according to any of embodiments 83° to 89°, wherein contacting in (3) is conducted in a fixed bed reactor or a fluidized bed reactor, preferably in a fixed bed reactor, most preferably all reactants in the fixed bed reactor are in gaseous phase.

[0390] 91 °. The process according to any of embodiments 83° to 90°, wherein contacting in (3) is conducted in a stirred tank, a trickle bed reactor or a bubble column, preferably in a stirred tank or a trickle bed reactor.

[0391] 92°. The process according to any of embodiments 83° to 91 °, wherein the temperature in the reaction space S is in the range of from 30 to 200°C, preferably from 40 to 150°C, more preferably from 50 to 110°C, more preferably from 60 to 100°C, more preferably from 70 to 90°C.

[0392] 93°. The process according to any of embodiments 83° to 92°, wherein the pressure in the reaction space S is in the range of from 1 to 100 bar, preferably from 10 to 80 bar, more preferably from 20 to 60 bar, more preferably from 30 to 50 bar.

[0393] 94°. The process according to any of embodiments 83° to 93°, wherein the reaction time in the reaction space S is in the range of from 0.1 to 12 h, preferably from 0.1 to 9 h, more preferably from 0.5 to 5 h, more preferably from 0.75 to 3 h, more preferably from 1 to 2 h.

[0394] 95°. The process according to any of embodiments 83° to 94°, wherein the conversion rate of the one or more olefins is 40% or higher, preferably 50% or higher, more preferably 60% or higher, more preferably 70% or higher, more preferably 80% or higher, more preferably 90% or higher.

[0395] 96°. The process according to any of embodiments 83° to 95°, wherein the one or more aldehydes comprised in the reaction mixture obtained in (3) comprise one or more unbranched and / or branched aldehydes, preferably one or more unbranched aldehydes. 97°. The process according to embodiment 96°, wherein the molar ratio of unbranched to branched aldehydes is 0.5 or higher, preferably 0.6 or higher, more preferably 0.7 or higher, more preferably 0.8 or higher, more preferably 0.9 or higher.

[0396] 98°. The process according to any of embodiments 83° to 97°, further comprising

[0397] (5) removing a product mixture from the reaction space S, wherein the reaction mixture comprises the one or more aldehydes.

[0398] 99°. The process according to embodiment 98°, further comprising

[0399] (6) separating the one or more aldehydes from the reaction mixture.

[0400] 100°. The process according to embodiment 99°, wherein separating the one or more aldehydes according to (6) is conducted by distillation, preferably fractionated distillation.

[0401] 101 °. The process according to any of embodiments 83° to 100°, wherein the reaction mixture is substantially free of hydrogenation products of the one or more olefins, preferably wherein the content of hydrogenation products is 10% or less, preferably 5% or less, more preferably 4% or less, more preferably 3% or less, based on the total amount of the reaction mixture, wherein preferably the hydrogenation products comprise one or more compounds selected from the group consisting of propane, 1 -butane, 1 -pentane, 1 -hexane, 1 -heptane, 1 -octane, 1 -decane, 1-dodacene, 1-octadacene, and ethylbenzene.

[0402] 102°. The process according to any of embodiments 83° to 101 °, wherein the reaction space S is a batch reactor, preferably a stirred tank reactor.

[0403] 103°. The process according to any of embodiments 83° to 102°, wherein the reaction space S is a continuous reactor, preferably a tubular reactor or a continuous stirred tank reactor.

[0404] 104°. The process according to any of embodiments 83° to 103°, wherein the molar ratio of CO:H2 comprised in the mixture according to (1 ) is in the range of from 1 :0.75 to 1 :3, preferably from 1 :0.8 to 1 :2, more preferably from 1 :0.85 to 1 :1 .5, more preferably from 1 :0.9 to 1 :1.2.

[0405] 105°. The process according to any of embodiments 83° to 104°, wherein the weight ratio of Rh to the one or more olefins in the reaction space according to (3) is in the range of from 1 :100 to 1 :900, preferably from 1 :200 to 1 :800, more preferably from 1 :300 to 1 :700, more preferably from 1 :400 to 1 :600.

[0406] 106°. Use of a catalyst according to any of embodiments 1 ° to 62° or 82° as a catalyst in the conversion of olefins to aldehydes. The present invention is further illustrated by the following reference examples, examples and comparative examples.

[0407] EXPERIMENTAL SECTION

[0408] Reference Example 1 : Powder x-ray diffraction (PXRD) analysis

[0409] A Stoe STADI-MP diffractometer operating with Ge-monochromatized Cu (A=1.54178 A) in transmission mode was used for the PXRD measurements.

[0410] Reference Example 2: SEM-EDX measurement

[0411] A Zeiss Supra 40 VP microscope (Zeiss, Germany), equipped with a Schottky field emitter (2.0 nm resolution) was used for the SEM measurements and to perform EDX measurements a Supra40VP from Zeiss using a Sapphire Si(Li) detector from the company EDAX Genesis was used.

[0412] Reference Example 3: TEM measurement

[0413] Samples for Transmission Electron Microscopy (TEM) were prepared on ultra-thin carbon TEM carriers. The powder was therefore dispersed in ethanol. One drop of the dispersion was applied between two glass objective slides and gently dispersed. The TEM carrier film was subsequently dipped on the resulting thin film. The samples were imaged by TEM using a 300kV probe-corrected Themis Z 3.1 machine (Thermo-Fisher, Waltham, USA) at atomic resolution in High-Angle Annular Dark-Field (HAADF) Scanning Transmission Electron Microscopy (STEM) as well as in high-resolution bright-field (HRTEM) mode.

[0414] The chemical composition was analyzed with the integrated SuperX G2 Energy-Dispersive X- Ray Spectroscopy (EDXS) detectors (Thermo-Fisher, Waltham, USA). Data was analyzed using the Velox 3 software (Thermo-Fisher, Waltham, USA).

[0415] The crystal structure of the sample was analyzed by parallel beam selected area electron diffraction (SAD). Size of the selected area was about 200nm in diameter.

[0416] Reference Example 4: Particle size distribution

[0417] Automated particle size detection from the micrographs was accomplished using the NanoDefine ParticleSizer plugin for Imaged (FIJI).

[0418] Reference Example 5: DFT calculation The geometric properties were established by Density Functional Theory, on the Perdew-Burke- Ernzerhof (PBE) level of theory, confirmed with two industry standard software packages (Quantum Espresso, VASP), by relaxing the structures to a maximal force threshold of 0.01 eV / A.

[0419] Reference Example 6: Analysis via X-ray diffraction

[0420] Samples may be analyzed via Rietveld refinement of the X-ray diffraction data for estimation of the distances and angles of the surface rhodium atoms according to standard practice as disclosed in Runcevski, T. et al. in Cryst. Growth Des. 2021 , 21 , 9, 4821-4822.

[0421] Reference Example 7: BET surface area and pore size

[0422] The sorption measurements were carried out using an Autosorb iQ from the company Quanto- chrome (now a part of Anton Paar), using ASiQwin software from Quantochrome Instruments (Model 7, ASiQwin Version 5.2) for data evaluation. The samples were weighed and taken in a measuring cell and dried in the device at 150°C and 10-3mbar for 3 hours. Nitrogen (77 K) is used for the measurement and pressure was gradually increased during a measurement. The specific surface area was determined using the Brunauer Emmett-Teller (BET) theory.

[0423] Example 1 : Preparation of Rhi?Si5@SiO2 via incipient wetness impregnation method

[0424] Rhodium acetate (Rh(OAc)3), in the required ratio considering 10 wt.-% rhodium loading of the impregnated sample, and thiourea were dissolved in water and impregnated on silica (fused silica, particle size 250-500 pm, BET 495 m2 / g, mean pore diameter of 60 A). The impregnated precursor was dried at 50 °C and afterwards was treated thermally in a flowing stream of Ar for 6h at 700 °C (heating rate of 10 K / min). In order to compensate the loss of sulfur during the thermal treatment, an excess of thiourea with regard to the desired Rh / S stoichiometry (17 / 15 in this case) was added during the impregnation step.

[0425] Samples were prepared with 20%, 30% and 50% thiourea excess, and the PXRD patterns obtained after the thermal treatment are provided in Figure 1.

[0426] It was observed that the addition of 30 % excess thiourea resulted in the formation of phase pure RhnSiswith major reflexes at diffraction angles 29°, 47°, and 52°, however other reflexes identifying the phase are not visible due to the poor crystallinity of the samples.

[0427] In order to enhance the crystallinity of the rhodium sulfide nanoparticles, the sample impregnated with 30% excess thiourea was thermally treated at 750 °C with an identical heating ramp and gas atmosphere. However, this resulted in the formation of pure metallic Rh, indicating the loss of sulfur due to the increased temperature. Hence, a temperature of 700 °C and 30% excess of thiourea were selected for the synthesis of Rhi7Si5@SiO2. The obtained samples were further characterized by SEM-EDX measurement. A uniform distribution of rhodium and sulfur on silica was confirmed with a S / Rh molar ratio of 0.9, which is in line with the S / Rh molar ratio of Rhi7Si5. This value also indicates the loss of sulfur during the thermal treatment and underlines the requirement of excess S precursor for the formation of the targeted phase. Further, almost spherical particles with an average particle size of 5.5 nm and a homogeneous Rh and S distribution were observed by TEM and SEM-EDX analysis.

[0428] Example 2: Preparation of bulk RhnSis via polyol method

[0429] Rhodium acetate with 20% excess thiourea were provided in an autoclave with diethylene glycol (DEG) and heated to 190°C for 12 h with continuous stirring. The obtained product was centrifuged and washed multiple times with acetone and dried overnight at 50°C. PXRD analysis of the product indicated the formation of metallic Rh only (see Figure 2).

[0430] However, after the thermal treatment in Ar at 500°C for 4 h followed by enhanced cooling of quartz tube in air, the formation of RhnSis was observed by PXRD. An enhancement in crystallinity was observed when the sample was heated up to 900°C in 90 min (see Figure 2).

[0431] The synthesized bulk RhnSis samples were further characterized by SEM-EDX measurement. A spherical morphology was overserved with a S / Rh molar ratio of 0.9 and uniform distribution of Rh and S was observed.

[0432] Example 3: Preparation of Rh2S3@SiC>2

[0433] Rhodium acetate (Rh(OAc)3), in the required ratio considering 10 wt.-% rhodium loading of the impregnated sample, and thiourea were dissolved in water and impregnated on silica (fused silica, particle size 250-500 pm, BET 495 m2 / g, mean pore diameter of 60 A). The impregnated precursor was dried at 50 °C and afterwards was treated thermally in a flowing stream of Ar for 6h at 700 °C (heating rate of 10 K / min). In order to compensate the loss of sulfur during the thermal treatment, an excess of thiourea was added during the impregnation step.

[0434] Samples were prepared with 50% thiourea excess, based on S / Rh molar ratio mixed into the impregnation solution, and the PXRD patterns obtained after the thermal treatment are provided in Figure 1.

[0435] It was observed that the addition of 50 % excess thiourea resulted in the formation of phase pure Rf^Ss with major reflexes at diffraction angles 29.5°, 42°, and 52°, however other reflexes identifying the phase are not visible due to the poor crystallinity of the samples.

[0436] Example 4: Catalyst testing

[0437] The supported catalyst compounds synthesized by impregnation method were tested for their catalytic activity towards the liquid phase hydroformylation reaction of alkenes. The reactions were performed in 5 mL batch reactors equipped with automatic pressure, temperature and stirring monitoring and control facility (1200 rpm, Rh / olefin 1 :500). The catalytic tests were conducted with styrene as proof-of-concept-substrate and toluene as solvent under varying reaction conditions. A synthesis gas with a CO to H2 ratio of 1 :1 was used in all tests and the reaction products were analyzed via GC-MS.

[0438] An initial test with Rhi?Si5@SiO2 (10 wt.-% Rh, Example 4.1) led to 18% conversion in 1 h 20 min with a n / iso (linear to branched aldehyde) ratio of 0.7 at 40 bar pressure and 80 °C. A further increase in reaction time to 3h 45 min resulted in 85% conversion with n / iso of 0.88 (Exam- pie 4.2).

[0439] Table 1 : Results of the catalytic testing using Rhi?Si5@SiO2 and Rh2S3@SiO2 as catalysts. asolvent less condition, Rh / olefin 1 :1500

[0440] A further attempt was made to increase the catalytic activity by reducing the impregnation loading of Rh within the catalyst. This leads to a reduced hi7Si5particle size on the support, which can possibly increase the number of active sites within the catalyst and thereby enhance the performance. Therefore, varying rhodium loadings of 10 wt.-%, and 1 wt.-% were tested under similar reaction conditions (see Examples 4.1 and 4.3). The synthesis gas pressure inside the reactor was recorded for the tests and a plot of the pressure drop versus the time is provided in Figure 3. These results clearly indicate the increase in catalytic activity with reduced metal loading.

[0441] However, a further reduction in Rh loading from 1 wt.-% to 0.5 wt.-% (see Examples 4.3 and 4.4) did not exhibit any considerably enhancement in catalyst activity.

[0442] Another test was performed in solvent less conditions (see Example 4.8 of Table 1 ) with Rh / olefin 1 :1500 using Rhi7Si5@SiO2catalyst (1 wt.-% Rh). After a reaction time of 2 h, the analysis indicated a conversion of 40%.

[0443] Further, a substrate variation was attempted by using 1 -octene, wherein the isomerization leading to branched aldehydes is most likely to occur as side reaction. The catalytic test was performed at 80°C, 40 bar using Rhi7Si5@SiO2(1 wt.-% Rh) and a conversion of 100% with a n / iso ratio of 1.0 was achieved after 1 h (see Example 4.9 of Table 1 ). The isomerization products of 1 -octene and corresponding aldehydes were observed with selectivity towards alpha-aldehydes around 95% and 5% towards isomerized olefins.

[0444] In order to verify the recyclability of the catalysts, recovery tests were conducted with Rhi7Si5@SiO2(1 wt.-% Rh) up to 3 cycles at 80°C, 40 bar providing a reaction time of 1 h 20 min. The catalyst was recovered after the test and dried overnight. The recovered catalyst was used for a second catalytic test, again recovered and applied for the third round of catalytic testing. No reduction in conversion of styrene and n / iso was observed in all 3 tests (see Figure 4) and revealed the possibility to reuse the catalyst without losing catalytic performance.

[0445] After conducting the tests using the metal (rhodium) rich Rhi7Si5@SiO2catalysts, the metal (rhodium) lean phase Rh2S3@SiO2catalyst was tested for the hydroformylation of styrene. The synthesized Rh2S3@SiO2(10 wt.-% and 1 wt.-% Rh) exhibited inferior performance compared to the metal rich Rhi7Si5@SiO2catalyst. Under similar reaction conditions Example 4.2 achieved a conversion of 85% in 3 h 45 min with Rhi7Si5@SiO2(10 wt.-% Rh), whereas Example 4.11 exhibited 42% conversion in 3 h 45 min with Rh2S3@SiO2(10 wt.-% Rh). Similar trend was ob- served with catalyst prepared having low Rh content. With the reaction conditions shown in Example 4.3 in Table 1 , Rhi?Si5@SiO2 (1 wt.-% Rh) showed a conversion of 87%, whereas Rh2Si3@SiC>2 (1 wt.-% Rh) led to a conversion of only 60%. A plot of synthesis gas pressure drop with respect to reaction time for the catalysts discussed above are provided as Figure 3 indicating the difference in activities. For all tests no or only trace amounts (up to a limit of 2.7% at a conversion of 100%) of hydrogenations products were observed, thus indicating a high selectivity of the catalysts towards aldehydes.

[0446] Further, a test was conducted with Rh@SiC>2 (1 wt.-% Rh) with reaction conditions same as Example 4.3 and 4.12, and a styrene conversion of 40% was observed, which is less than the conversion observed while using rhodium sulfides.

[0447] The particle size distribution of the Rhi?Si5@SiO2 samples (loaded with 1 , 5 or 10 wt.-% Rh) and Rh2S3@SiC>2 samples (loaded with 1 or 10 wt.-% Rh) is provided in Figures 5 and 6.

[0448] DESCRIPTION OF FIGURES

[0449] Figure 1 shows the PXRD pattern of the impregnated sampled obtained after the thermal treatment at 700°C for 6h with a) 20%, b) 30%, and c) 50% excess of thiourea for the synthesis of Rhi?Si5@SiO2 (10 wt.-% Rh).

[0450] Figure 2 shows the PXRD pattern of the sample obtained by polyol synthesis a) as synthesized, b) after thermal treatment at 500°C and c) after heating to 900°C.

[0451] Figure 3 shows the synthesis gas pressure drop inside the reactor during the hydroformylation using Rhi?Si5@SiO2and Rh2Ss@SiO2 catalysts with various rhodium loadings (10 wt.- %, and 1 wt.-%) at 80°C and 40 bar.

[0452] Figure 4 shows the recovery test results for Rhi?Si5@SiO2 (1 wt.-% Rh) conducted at 80°C and 40 bar with a reaction time of 1 h 20min.

[0453] Figure 5 shows the particle size distribution of Rhi7Si5particles on the SiC>2 samples loaded with 1 , 5 and 10 wt.-% Rh.

[0454] Figure 6 shows the particle size distribution of Rf^Ss particles on the SiC>2 samples loaded with 1 and 10 wt.-% Rh.

[0455] List of cited documents:

[0456] “Oxo Synthesis”, Ullmann's Encyclopedia of Industrial Chemistry June 2000 DOI: 10.1002 / 14356007. a18_321 “Current State of the Art of the Solid Rh-Based Catalyzed Hydroformylation of Short- Chain Olefins” by S. Hanf, L. Alvardo Rupflin, R. Glaser, S. A. Schunk, Catalysts 2020, 10, 1-36, https: / / doi.org / 10.3390 / catal10050510

[0457] Runcevski, T. et al. in Cryst. Growth Des. 2021 , 21 , 9, 4821-4822 - CN 103691456 B

[0458] - GB 1066579 A

[0459] - US 4560803 A

[0460] - US 6310261 B1

[0461] - CN 113385205 B

Claims

Claims1 . A catalyst comprising one or more rhodium sulfides and a catalyst support, wherein the average particle size (D50) of the catalyst is in the range of from 100 to 1000 pm.

2. The catalyst according to claim 1 , wherein the one or more rhodium sulfides are located on the surface of the catalyst, wherein said surface of the catalyst comprising one or more rhodium sulfides comprises a first structure motive according to formula (I) comprising 4 adjacent rhodium atoms Rh(1 ) to Rh(4) in a planar or substantially planar ring arrangement: :wherein all of the rhodium atoms Rh(1 ) to Rh(4) are in the outermost layer of atoms forming the outer surface of the one or more rhodium sulfides, wherein the first structure motive comprises a first Rh(1 )-Rh(2)-Rh(3) angle in the range of from 55.0 to 65.0°, and a second Rh(2)-Rh(3)-Rh(4) angle in the range of from 105.0 to 120.0, wherein the geometry of the ring arrangement according to formula (II) and the angles of the first structure motive are determined according to reference example 6.

3. The catalyst according to claim 2, wherein the first structure motive comprises a first rho- dium-rhodium distance Rh(1 )-Rh(2) in the range of from 2.50 to 2.65 A and a second rho- dium-rhodium distance Rh(2)-Rh(3) in the range of from 2.70 to 2.90 A, wherein the rho- dium-rhodium distances of the first structure motive are determined according to reference example 6.

4. The catalyst according to any of claims 1 to 3, wherein the one or more rhodium sulfides are selected from the group consisting of Rhi7Si5, RhsS i, and Rf^Ss, and mixtures thereof.

5. The catalyst according to any of claims 2 to 4, wherein the catalyst further comprises a second structure motive comprising 4 adjacent rhodium atoms Rh(5) to Rh(8) in a planar or substantially planar ring arrangement, according to formula (II):wherein all of the rhodium atoms Rh(1 ) to Rh(8) are in the outermost layer of atoms forming the outer surface of the one or more rhodium sulfides comprising the first structure motive in said outermost layer, wherein the geometry of the ring arrangement according to formula (II) is determined according to reference example 6.

6. The catalyst according to claim 5, wherein the second structure motive comprises a first Rh(5)-Rh(6)-Rh(7) angle in the range of from 76.0 to 87.0, and a second Rh(6)-Rh(7)-Rh(8) angle in the range of from 93.0 to 104.0°.

7. The catalyst according to any of claims 2 to 6, wherein the catalyst further comprises one or more ligands, wherein the one or more ligands are coordinated and / or bonded to the first structure motive.

8. The catalyst according to any one of claims 1 to 7, wherein the catalyst support is selected from the group consisting of ZrC>2, AI2O3, SiC>2, TiC>2, La2O3-doped ZrC>2, CeO2-ZrO2 mixed oxide, La2C>3-doped CeO2-ZrO2 mixed oxide, Nd2Os-doped CeO2-ZrO2 mixed oxide, Y2O3- doped CeO2-ZrC>2 mixed oxide, P^Os-doped CeO2-ZrO2 mixed oxide, ZrC>2-doped AI2O3, ZrC>2-doped SiC>2, SiC>2-doped AI2O3, and mixtures of two or more thereof.

9. The catalyst according to any one of claims 1 to 8, wherein the catalyst support exhibits an average particle size (D50) in the range of from 200 to 600 pm.

10. The catalyst according to any of claims 1 to 9, wherein the catalyst support exhibits a BET surface area in the range of from 300 to 700 m2 / g.11 . The catalyst according to any of claims 1 to 10, wherein the catalyst further comprises one or more promotors.

12. A process for the preparation of a catalyst comprising one or more rhodium sulfides and a catalyst support according to any one of claims 1 to 11 , wherein the process comprises,(2.1) mixing one or more rhodium sources and one or more sulfur sources with one or more solvents, obtaining a precursor solution;(2.2) impregnating a support material with the precursor solution obtained according to (2.1 ), obtaining an impregnated material;(2.3) optionally drying the impregnated material obtained according to (2.2);(2.4) subjecting the impregnated material obtained according to (2.2) or (2.3) to a thermal treatment under a gas atmosphere.

13. A catalyst comprising one or more rhodium sulfides and a catalyst support, as obtained or obtainable according to any of claim 12.

14. A process for the hydroformylation of olefins comprising,(1 ) providing a mixture comprising one or more olefins, carbon monoxide, and hydrogen;(2) providing a catalyst comprising one or more rhodium sulfides and a catalyst support according to any one of claims 1 to 11 ; (3) subjecting the mixture provided according to (1 ) to hydroformylation conditions in a reaction space S, said conditions comprising contacting the mixture according to (1 ) with the catalyst provided according to (2), obtaining a reaction mixture comprising one or more aldehydes.

15. Use of a catalyst according to any of claims 1 to 11 or 13 as a catalyst in the conversion of olefins to aldehydes.

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