RU2777912C2 - Heterogenous catalysts for direct carbonylation of nitroaromatic compounds into isocyanates - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to heterogeneous catalysts, a method for their production, and a method for direct carbonylation of nitroaromatic compounds into aromatic isocyanates. A method is proposed for the production of aromatic isocyanate by direct carbonylation of a nitroaromatic compound by reaction of the nitroaromatic compound with carbon monoxide in the presence of a catalyst, which contains multi-metal material containing one or more binary intermetallic phases of the general formula A_xB_y, where A is one or more elements selected from Rh and Pd, B is one or more elements selected from Sn, Sb, Pb, Ga, and In, x is in the range from 0.1 - 10, y is in the range from 0.1 - 10. The invention also relates to a catalyst containing multi-metal material, which contains the above-mentioned one or more binary intermetallic phases of the general formula A_xB_y. The method for the production of the catalyst includes stages (i) and (iv) of: (i) provision of one or more precursors for elements A and B and optionally component C in the form of a solution; (ii) application of metal precursors to carrier material; (iii) reducing treatment of composite material; (iv) heat treatment of composite material.

EFFECT: providing a method for carbonylation of nitroaromatic compounds to a corresponding isocyanate showing a significant improvement in activity and selectivity.

19 cl, 9 tbl, 3 dwg, 15 ex

Description

The present invention relates to heterogeneous catalysts for the direct carbonylation of nitroaromatic compounds to aromatic isocyanates and to a process for the direct carbonylation of nitroaromatic compounds to aromatic isocyanates.

Direct carbonylation of nitroaromatic compounds to the corresponding aromatic isocyanates with homogeneous catalysts has been described in the literature. PdCl ₂ (pyridine) ₂ and Fe(cyclopentadienyl) ₂ as cocatalyst achieved toluene diisocyanate (TDI) selectivity from 9 to 67% with dinitrotoluene (DNT) conversion from 82 to 100%, as described in (DE19635723A1. The main problems that prevent commercial uses are low RPM, difficult catalyst separation, harsh reaction conditions (T=250°C, p=200-300 barg), by-product formation and TDI polymerization.

A catalyst is known in the art for the carbonylation of 2,4-dinitrotoluene containing a mixture of a complex of palladium with isoquinoline and Fe ₂ Mo ₇ O ₂₄ as described in DE 2165355. 2,4-Toluene diisocyanate is obtained with a maximum yield of 70% at 100% conversion of the starting compound 2,4-dinitrotoluene. When pyridine is used instead of isoquinoline, the yield is 21-76% at a conversion of the starting compound of 83-100% as described in FR 2,120,110. Also known are catalysts for the carbonylation of aromatic nitro compounds containing Pd(pyridine) ₂ Cl ₂ and MoO ₃ or Cr ₂ O ₃ /Al ₂ O ₃ as disclosed in US3,823,174 and US3,828,089, respectively. Another homogeneous-heterogeneous catalyst for the synthesis of aromatic monoisocyanates, in particular phenylisocyanate, is PdCl ₂ /V ₂ O ₅ as disclosed in US 3,523,964. In contrast to the present invention, the systems described in the above documents are not truly heterogeneous and correspond to a hybrid system containing homogeneous and heterogeneous components. The disadvantage is that the palladium chloride is present in the liquid phase, which requires a complex system for its separation and recovery.

Only a few heterogeneous catalysts for the carbonylation of DNT to TDI are reported in the literature. US 4,207,212 reports that PdO/MoO ₃ /ZnO is a highly active and selective catalyst for the carbonylation of DNT. All examples of this patent were made in the presence of pyridine as an additive. This fact leads to the assumption that the formation of pyridine complexes is necessary to achieve the carbonylation of nitroarenes using these catalysts.

In addition to the direct conversion of nitroaromatic compounds to isocyanates, an indirect conversion with a nitrosoaromatic compound as a separable intermediate is also known. The conversion of nitroarenes to nitrosoarenes, as well as the conversion of nitrosoarenes to aromatic isocyanates in the presence of carbon monoxide, are described in the literature as two separate reactions. This is also the case if the parent nitroarene has more than one nitro group. Since the present invention provides for the direct synthesis of isocyanates as well as the indirect synthesis of isocyanates with nitrosoaromatic compounds as suitable intermediates. The relevant literature is cited below.

Scheme 1

The preparation of nitrosoarenes according to stage 1 (Scheme 1), which can also be considered as the selective reduction of nitrobenzene to nitrosobenzene, is possible using Mn-containing catalysts. DE 1810828 discloses catalytic systems of the general formula M _x Mn _y O _z , where M is Co, Fe, Pb or Ag, as a catalyst for the selective reduction of nitrobenzene to nitrosobenzene. An oxide compound containing Mn and Pb at a ratio of 70/30 gives a yield of 4.53% nitrosobenzene per hour of reaction.

The conversion of nitrosobenzene to isocyanate according to step 2 (Scheme 1) with the same Mn-containing system is not reported. The carbonylation of nitrosoarenes to aromatic isocyanates according to reaction 2 (Scheme 1) can be carried out with a heterogeneous catalyst containing one or more of Pd, Rh and Ir supported on Al ₂ O ₃ as reported in US 3,979,427.

GB 1 315 813 A describes the heterogeneously catalyzed carbonylation of nitroso and nitroaromatic compounds to isocyanates in the presence of physical mixtures of M _x Mn _y O _z , where M is Fe, Ag or Pb, with platinum group metals selected from Pd, Ru and Rh, applied to the media. such as carbon or pumice. Nitrobenzene is carbonylated to phenyl isocyanate in the presence of a physical mixture of Pb _x Mn _y O _z and 5% Rh on carbon. The specified yield of isocyanate is 4.5% after 2 hours at 190°C.

It is an object of the present invention to provide heterogeneous catalysts having high activity and selectivity for a heterogeneously catalyzed process allowing the synthesis of isocyanates via direct carbonylation. Direct carbonylation in the context of the present invention should be understood as carrying out reaction steps 1 and 2 in a one-pot manner without isolation of intermediates. However, intermediates such as nitroso compounds or partially carbonylated nitroaromatic compounds can be produced from an incomplete reaction.

The object of the present invention is to provide a process for the carbonylation of nitroaromatic compounds to the corresponding isocyanate, showing a significant improvement in activity and selectivity.

Multimetal material composition

The object of the present invention is achieved by a catalyst for the direct carboxylation of a nitroaromatic compound to the corresponding aromatic isocyanate and a method for producing an aromatic isocyanate by direct carboxylation of a nitroaromatic compound in the presence of a catalyst.

The process of the present invention is carried out as a heterogeneously catalyzed process

In such a heterogeneous catalyzed process, the catalyst and the reactant(s)/product(s) are in different phases that are in contact with each other. The reactant(s)/product(s) are in the liquid phase and the gas phase, while the catalyst will be in the solid phase. The reaction will take place at the interface between the liquid phase, the gas phase and the solid phase.

The process according to the present invention is carried out in the presence of a catalyst. The catalyst contains a multimetallic material containing one or more binary intermetallic phases of the general formula A _x B _y , where

A is one or more metallic elements selected from Ni, Ru, Rh, Pd, Ir, Pt and Ag,

B is one or more metallic elements selected from Sn, Sb, Pb, Zn, Ga, In, and As,

x in A _x B _y is in the range from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.5 to 2,

y in A _x B _y ranges from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.5 to 2.

More preferably, the multimetallic materials contain one or more of the binary intermetallic phases of the general formula A _x B _y , where

A is one or more metallic elements selected from Ni, Rh, Pd, Ir and Pt,

B is one or more metallic elements selected from Sn, Sb, Pb, Ga and In,

x in A _x B _y is in the range from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.5 to 2,

y in A _x B _y ranges from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.5 to 2.

Even more preferably, the multimetallic materials contain one or more binary intermetallic phases of the general formula A _x B _y , where

A is Rh,

B is one or more of Pb, Sn or Sb,

x in A _x B _y is in the range from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.5 to 2,

y in A _x B _y ranges from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.5 to 2.

The object of the present invention is also solved by providing a continuous heterogeneous process using liquid and gaseous feed material together with a multi-metal material.

In general, a multimetallic material may contain or be composed of one or more binary intermetallic phases of the general formula A _x B _y as previously specified. In addition, a multi-metal material is defined as a material containing at least two different metals in a macroscopically homogeneous phase. In general, multimetallic materials contain at least 85 wt.%, preferably at least 90 wt.% and more preferably 95 wt.% of one or more intermetallic phases of the general formula A _x B _y . The multimetallic material may contain one or more other C components, where the C component may consist of or contain A and/or B that are not part of the A _x B _y intermetallic compound. Component C may also contain or be composed of one or more metallic or non-metallic elements. Preferably component C contains O, N, C, H, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, Mn, Fe, Co, Ni, Zn, Ga. In a more preferred embodiment of the present invention, component C contains O, N, C, H, Mg, Ca, Mn, Fe, Co, Ni, Zn, Ga.

The intermetallic phase or intermetallic compound according to the present invention is a compound made from at least two different metals in an ordered or partially ordered structure with a defined stoichiometry. The structure may be similar or different from that of the pure constituent metals. Examples of intermetallic compounds are ordered, partially ordered and eutectic alloys, Laves phases, Zintl phases, Heusler phases, Hume-Rothery phases and other intermetallic phases known to those skilled in the art. Also included are compounds containing semimetal elements such as selenides, tellurides, arsenides, antimonides, silysides, germanides and borides.

Examples of intermetallic phases according to the present invention are RhPb, RhPb ₂ , Rh ₄ Pb ₅ , Rh ₂ Sn, RhSn, RhSn ₂ , RhSn ₄ , Rh ₂ Sb, RhSb, RhSb ₂ , RhSb ₃ , RhGa, Rh ₁₀ Ga ₁₇ , Rh ₃ Ga ₅ , Rh ₂ Ga ₉ , Rh ₄ Ga ₂₁ , Rh ₃ Ga ₁₆ , RhGa ₃ , RhIn, RhIn ₃ , Rh ₅ Ge ₃ , Rh ₂ Ge, RhGe, Rh ₁₇ Ge ₂₂ , RhGe ₄ , IrPb, IrSn, Ir ₅ Sn ₇ , IrSn ₂ , Ir ₃ Sn ₇ , IrSn ₄ , IrSn, Ir ₅ Sn ₇ , IrSn ₂ , Ir ₃ Sn ₇ , IrSn ₄ , Pd ₃ Pb, Pd ₁₃ Pb ₉ , Pd ₅ Pb ₃ , PdPb _, Pd ₃ Sn, Pd ₂₀ Sn ₁₃ , Pd ₂ Sn, PdSn, Pd ₅ Sn ₇ , PdSn ₂ , PdSn ₃ , PdSn ₄ , Pd ₃ Sb, Pd ₂₀ Sb ₇ , Pd ₅ Sb ₂ , Pd ₈ Sb ₃ , Pd ₂ Sb , PdSb, PdSb ₂ , Pd ₂ Ga, Pd ₅ Ga ₂ , Pd ₅ Ga ₃ , PdGa, PdGa ₅ , Pd ₇ Ga ₃ , Ru ₂ Sn ₃ , RuSn ₂ , Ru ₃ Sn ₇ , RuSb, RuSb ₂ , RuSb ₃ , NiPb, Ni ₃ Sn ₄ , Ni ₃ Sn ₂ , Ni ₃ Sn, NiSn, Ni ₅ Sb ₂ , Ni ₃ Sb, NiSb ₂ and NiSb ₃ , where RhPb, RhPb ₂ , RhSb, Rh ₂ Sb, RhSb ₂ and Rh ₂ Sn are preferred.

The presence of intermetallic phases in a multimetallic material can be detected by standard solids characterization methods such as, for example, electron microscopy, solid state NMR, or powder X-ray diffraction (PXRD), where PXRD analysis is preferred.

In general, the form in which the multi-metal material of the present invention is provided is not limited.

The multimetallic material can be used as a single compound or mixed with other compounds, where it is preferred to apply to the carrier by methods including shallow impregnation, spray impregnation, wet impregnation, melt impregnation, and other impregnation methods known to those skilled in the art. A description of how to place the multi-metal material on the media is given below.

The carrier material according to the present invention may be a crystalline or amorphous oxide material. It includes both binary and polynar oxides. Examples of suitable binary oxides are: Al ₂ O ₃ , CaO, CeO ₂ , Ce ₂ O ₃ , Fe ₂ O ₃ , La ₂ O ₃ , MgO, MnO ₂ , Mn ₂ O ₃ , SiO ₂ , TiO ₂ , Ti2O ₃ , _ZrO2 and ZnO. These specifically include non-stoichiometric or mixed valence oxides where the non-oxygen element is present in more than one oxidation state, for example: CeO _2-x , WO _x , Fe _0.95 O Mn ₃ O ₄ , Fe ₃ O ₄ , Ti ₄ O ₇ and other non-stoichiometric oxides known to those skilled in the art. Also included are polynar oxides such as, for example, MgAl ₂ O ₄ , LaAlO ₃ , CaTiO ₃ , CeZrO ₄ H ₂ Al ₁₄ Ca ₁₂ O ₃₄ . Also included are physical mixtures of binary, polynar, and non-stoichiometric oxides.

Also included in the group of oxide supports are zeolite supports, as indicated below. It includes carriers containing one or more zeolites, microporous molecular sieves, aluminosilicates and aluminophosphates, as well as mixtures of zeolites with binary, polynar and/or non-stoichiometric oxides. In general, it is possible that the type of zeolite framework structure is one of the following ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, *-EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, *-ITN, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV , LIO, -LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, *MRE, MSE, MSO, MTF , MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, POS, PSI, PUN, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SB N, SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, *SFV, SFW, SGT, SIV, SOD, SOF, SOS, SSF, *-SSO, SSY, STF, STI, * STO, STT, STW, -SVR, SVV, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI , -WEN, YUG, ZON, or a mixed type of two or more of them. More preferably, the zeolite material comprises, more preferably is, one or more of zeolite materials having a framework type of MFI, MOR, BEA, and FAU.

Additional examples of carriers are carbon or carbon-like materials such as activated carbon, graphite or graphene. Also included are modified carbon based materials such as intercalated compounds, and carbides such as W-C, B-C, Si-C. Also included are nitrides, borides, silicides, phosphides, antimonides, arsenides, sulfides, selenides and tellurides.

Also included are alloys, solid solution alloys, partial solution alloys, and intermetallic compounds, as well as compounds referred to as metal compounds in the context of this invention. Also included in the group of carriers are binary and polynar oxide carriers containing one or more elements from the main groups (excluding noble gases and halides), transition elements and/or lanthanides in combination with oxygen and their respective modifications.

The carrier material may be provided in the form of a powder, dispersion, colloid, granulate, shaped articles such as rings, spheres, extrudates, beads, and other shaped articles known to those skilled in the art.

Preferred carrier materials are carbon, binary and poly- nary oxides, and mixtures of binary and poly nary oxides.

Synthesis of multimetallic material

The catalyst according to the present invention can be obtained by a method comprising steps in the order (i) to (iv):

(i) Providing the metal precursor, preferably in the form of a solution;

(ii) Applying the metal precursor to the carrier material, optionally after drying;

(iii) Restorative processing of the composite material;

(iv) Heat treatment of the composite material.

(i) This step involves the preparation of a metal precursor by dissolving or diluting a metal-containing component such as metal salts, colloidal metals or organic metal compounds in a suitable solvent such as water, alcohols, polyols, acids, bases and other solvents known to those skilled in the art. this field of technology. This solution can be prepared either as a solution containing a single metal, A or B, or as a multi-metal solution containing any concentration of A and B. In a particular embodiment of the present invention, a further solution is prepared containing promoter component C. In a very particular In an embodiment of the present invention, the scavenger component may be part of a single metal solution containing A or B, or part of a multimetal solution containing A and B.

(ii) The metal solution(s) obtained in step (i) are applied to the carrier material using standard techniques such as shallow impregnation, spray impregnation, wetness impregnation, melt impregnation, and other impregnation methods known to those skilled in the art. this field of technology. The impregnation can be carried out in one step using solutions of one or more metals or mixtures of solutions of one or more metals. The impregnation can be carried out in several stages using solutions of one or more metals or mixtures of solutions of one or more metals in several stages. The present invention also covers precipitation methods where the support is obtained in situ from metal solutions or in a separate step. This step also includes one or more drying steps (iia).

The product of step (ii) or step (iia), respectively, is a composite material.

(iii) Restorative treatment comprises exposing the composite material obtained in step (ii) or step (iia) respectively to a reducing agent or restoring the composite material by thermal reduction. This reducing agent may be provided in solid, liquid or gaseous form. The recovery step may be performed with or without performing step (iia) before it. The reducing agents according to the present invention are gases such as, for example, H ₂ , CO and gaseous hydrocarbons such as CH ₄ , C ₂ H ₄ and other reducing gases known to the person skilled in the art, liquid reducing agents, such as alcohols, hydrocarbons and amines such as, for example, polyols and hydrazine, as well as reducing agents provided in solid form, such as, for example, metal powder.

(iv) Heat treatment of the recovered composite material is carried out by heating the recovered composite material taken from step (iii) to the desired temperature under chemically inert conditions where the gas mixture present does not contain any reactive components that can undergo chemical reaction with the composite material. In particular, the mixture should not contain oxidizing agents such as, for example, oxygen, water, NO _x , halides or the like. Heating can be performed by any method suitable for heating solids or wet solids, such as heating in muffle furnaces, microwave ovens, rotary kilns, tube furnaces, fluidized bed and other heating devices known to the person skilled in the art.

In a particular embodiment of the present invention, steps (iii) and (iv) can be combined into one step by thermally treating the composite material in the presence of a reducing agent or at a temperature at which thermal reduction occurs.

Method for the synthesis of isocyanates from nitroaromatic compounds and carbon monoxide

The object of the present invention is also solved by a process for the preparation of an aromatic isocyanate by direct carbonylation of a nitroaromatic compound by the reaction of a nitroaromatic compound with carbon monoxide in the presence of a catalyst, characterized in that the catalyst contains a multimetallic material, as previously specified, containing one or more of the binary intermetallic phases of the general formula A _x B _y, with or without the C component.

The method can be carried out intermittently or continuously.

The present invention provides new catalytic materials capable of catalyzing reaction steps 1 and 2 of the entire reaction. The catalytic material is not a physical mixture of two separate catalysts, each capable of catalyzing only one of two successive reaction steps as described in GB 1315813A, but a catalyst that catalyzes both reaction steps 1 and 2.

GB 1 315 813 describes the heterogeneously catalyzed carbonylation of nitroso and nitroaromatic compounds to isocyanates. However, in contrast to the present invention, physical mixtures of one catalyst of the general formula M _x Mn _y O _z , where M is Fe, Ag or Pb, with a second catalyst containing platinum group metals selected from Pd, Ru and Rh, on a carrier such as carbon or pumice. The indicated isocyanate yield is 4.5% after 2 hours at 190°C. According to the present invention, one multi-metal material containing one or more A _x B _y intermetallic phases provides the desired isocyanate with significantly higher selectivity at higher conversions (see Table 4). The presence of one or more intermetallic phases is believed to be responsible for the significantly higher yields.

In addition, the present invention provides a process for the synthesis of isocyanates from nitroaromatic compounds and carbon monoxide, comprising the following steps:

a) providing a mixture of reagents M1 containing nitroaromatic compounds and at least one additional component D, where D contains a suitable solvent;

b1) Providing a reactant mixture M2 containing a reactant mixture M1 and carbon monoxide or a mixture of carbon monoxide and an inert gas G, and/or

b2) providing a reaction mixture R1 containing a reactant mixture M1 a carbonylation catalyst containing a multi-metal material as described in more detail above;

c) contacting the reactant mixture M2 with a carbonylation catalyst containing, preferably consisting of, the multi-metal material n I) as described in more detail above; and/or

d) contacting the reagent mixture R1 with carbon monoxide or a mixture of carbon monoxide and inert gas G;

e) obtaining a reaction mixture containing isocyanates.

The above steps can be performed using either step b1), or step b2), or both.

Preferably, the concentration of the nitroaromatic compound in the mixture M1 is in the range from 0.01 wt.% to 60 wt.%, more preferably in the range from 0.1 wt.% to 50 wt.%, more preferably in the range from 1 wt. % to 40 wt.%.

Preferably, the concentration of component D in the mixture M1 is in the range from 40 wt.% to 99.99 wt.%, more preferably in the range from 50 wt.% to 99.9 wt.%, and more preferably in the range from 60 wt.% to 99 wt%.

Suitable nitroaromatic compounds (or nitroaromatic compound) to be reacted according to the present invention are simple or polyaromatic compounds with one or more nitro groups, such as nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, trinitrotoluene, nitronaphthalene, nitroanthracene, nitrodiphenyl, bis(nitrophenyl)methane and other simple and polyaromatic compounds having one or more nitro groups. Nitroaromatic compounds may also contain other functional groups. In the context of this invention, functional groups are substituents associated with an aromatic ring. The functional groups may contain one or more heteroatoms selected from the group consisting of H, B, C, N, P, O, S, F, Cl, Br, and I.

Examples of functional groups are hydroxyl groups, halogens, aliphatic side chains, carbonyl groups, isocyanate groups, nitroso groups, carboxyl groups and amino groups.

Also included are organonitro compounds containing one or more nitro groups linked to an aliphatic chain or side chain or ring, such as 1,6-dinitrohexene or nitrocyclohexene, nitrocyclopentene, nitromethane, nitrooctane, and bis(nitrocyclohexyl)methane.

A suitable source of nitroaromatic compounds is any source containing at least partially nitroaromatic compounds. The source may be a nitroaromatic compound freshly provided to the reagent stream M1. In addition, the nitroaromatic compounds may be unreacted nitroaromatic compounds which, after being separated from the product stream, are recycled after one or more processing steps. The nitroaromatic compound may also be a compound which contains at least one nitro and/or at least one nitroso group, which is recycled after its partial conversion with carbon monoxide. A combination of freshly provided nitroaromatic compound and recycled nitroaromatic compound may also be used. It is also possible to use nitroaromatic adducts or precursors, such as, for example, nitrosoaromatic compounds.

A suitable source of carbon monoxide is also any source containing at least partially carbon monoxide. The source can only be monoxide freshly provided to the reactant stream M1. In addition, the carbon monoxide may be unreacted carbon monoxide, which, after being separated from the product stream, is recycled after one or more processing steps. A combination of freshly provided carbon monoxide and recycled carbon monoxide can also be used. It is also possible to use carbon monoxide adducts or precursors such as, for example, formic acid.

In addition to nitroaromatic compounds and optionally carbon monoxide, the reactant stream M1 may contain one or more components D containing solvents S, additives X and inert gases G.

Suitable solvents S are aprotic organic solvents such as arenes and substituted arenes such as chlorobenzene, dichlorobenzene, benzene, toluene, 1,2-diphenylbenzene, 1,2-dimethylnaphthalene, hexadecylbenzene, Solvesso 150 ND and Solvesso 200 ND.

Other suitable aprotic solvents are (cyclo)alkanes and substituted (cyclo)alkanes such as n-alkanes, cycloalkanes, chloroform, dichloromethane, diphenylmethane, dibenzyl.

Other suitable solvents are open chain ethers and cyclic ethers such as dioctyl ether or THF.

Preferred solvents have a boiling point in the range of 50°C to 300°C, more preferably 100°C to 275°C, and more preferably 125° to 255°C.

The solvent may also be an isocyanate corresponding to the corresponding nitroaromatic compound.

Suitable inert gases G include gases such as nitrogen, helium, neon, argon or carbon dioxide, of which nitrogen, argon and carbon dioxide are preferred.

The carbonylation is generally carried out at a temperature in the range of 50 to 250°C, preferably in the range of 80 to 190°C, and more preferably in the range of 100 to 170°C.

The total pressure during the reaction is in the range of 1 to 200 bar, preferably 10 to 150 bar, and more preferably in the range of 15 to 100 bar.

The partial pressure of carbon monoxide is in the range of 1 to 150 bar, preferably in the range of 1 to 120 bar, and more preferably in the range of 1 to 100 bar.

In general, the contacting of the reaction mixture M1 with a catalyst containing preferably consisting of a multi-metal material and with carbon monoxide can be carried out in a continuous or discontinuous manner.

Preferably, the present invention is carried out in batch reactors, batch reactors, semi-batch reactors, or continuous reactors. Suitable reactors are agitated reactors, loop reactors, venturi loop reactors, reverse flow loop reactors, pulsed flow reactors, tubular reactors, slurry reactors, carrier bed reactors, trickled bed reactors, moving catalyst reactors, pressure vessel reactors. rotor, other types of reactors known to those skilled in the art, and combinations of different types of reactors.

In one unit, the reaction includes the following reaction steps:

a) providing a mixture of reagents M1 containing nitroaromatic compounds and at least one additional component D, where D contains a suitable solvent;

b) providing a reaction mixture R1 containing a mixture of reactants M1 and a carbonylation catalyst containing a multi-metal material as described in more detail above;

c) contacting the reaction mixture R1 with carbon monoxide or a mixture of carbon monoxide and inert gas G;

d) obtaining a reaction mixture containing isocyanates.

In an alternative setup, the reaction includes the following reaction steps:

a) Providing a mixture of reagents M1 containing nitroaromatic compounds and at least one additional component D, where D contains a suitable solvent;

b) Providing a reactant mixture M2 containing a reactant mixture M1 and carbon monoxide or a mixture of carbon monoxide and an inert gas G to obtain a reactant mixture M2.

c) Contacting the reactant mixture M2 with a carbonylation catalyst containing, preferably consisting of, the multimetallic material I) as described in more detail above,

d) Preparation of a reaction mixture containing isocyanates.

In general, the reaction mixture R1 contains a carbonylation catalyst containing a multi-metal material. The concentration of the carbonylation catalyst is in the range of 0.1 to 10 wt.%, preferably in the range of 0.1 to 7.5 wt.%, and more preferably in the range of 0.1 to 5 wt.%.

In general, the reaction mixture R1 is contacted with carbon monoxide for 0.5 to 24 hours, preferably 2 to 20 hours, and more preferably 4 to 12 hours.

In general, in the reaction mixture M2, the partial pressure of carbon monoxide is in the range of 1 to 150 bar, preferably in the range of 1 to 120 bar, and more preferably in the range of 1 to 100 bar.

Preferred embodiments of the present invention

The present invention is further illustrated by the following embodiments of the present invention and combinations of embodiments of the present invention as indicated below.

In general, the present invention provides a process for producing an aromatic isocyanate by direct carbonylation of a nitroaromatic compound catalyzed by a multi-metal material containing one or more binary intermetallic phases of general formula A _x B _y, where:

A is one or more elements selected from the group consisting of Ni, Ru, Rh, Pd, Ir, Pt and Ag;

B is one or more elements selected from the group consisting of Sn, Sb, Pb, Zn, Ga, In, Ge, and As;

x in A _x B _y ranges from 0.1 to 10, preferably from 0.2 to 5, and more preferably from 0.5 to 2;

y in A _x B _y ranges from 0.1 to 10, preferably from 0.2 to 5, and more preferably from 0.5 to 2.

The preferred catalyst contains one or more of the binary intermetallic phases of the general formula A _x B _y , where

A represents one or more elements selected from the group consisting of Ni, Rh, Pd, Ir and Pt;

B is one or more elements selected from the group consisting of Sn, Sb, Pb, Ga and In.

More preferred catalysts contain one or more binary intermetallic phases of the general formula A _x B _y , where

A is Rh;

B is one or more elements selected from the group consisting of Pb, Sn and Sb.

Preferably, the multimetallic material comprises up to at least 85 wt.%, more preferably up to at least 90 wt.%, and even more preferably up to at least 95 wt.% of one or more of the A _x B _y intermetallic phases.

In one embodiment of the present invention, the multimetallic material contains one or more C components, where the C component consists of or contains A and/or B that are not part of the A _x B _y intermetallic compound.

In another embodiment of the present invention, the multimetallic material contains one or more C components, where the C component contains or consists of one or more elements selected from the group consisting of O, N, C, H, Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba, Ti, Mn, Fe, Co, Ni, Zn, Ga, preferably one or more elements from the group consisting of O, N, C, H, Mg, Ca, Mn, Fe, Co, Ni, Zn and Ga.

Preferably, the multimetallic material is applied to a carrier material, generally a crystalline or amorphous carrier material. In a first preferred embodiment of the present invention, the carrier material contains carbon, graphite, graphene or an intercalated compound. In a second preferred embodiment of the present invention, the carrier material contains a carbide, nitride, boride, silicide, phosphide, antimonide, arsenide, sulfide, selenide or telluride. In a third preferred embodiment of the present invention, the carrier material contains one or more of binary and polynar oxides such as MgO, CaO, ZnO, CeO ₂ , SiO ₂ , Al ₂ O ₃ . TiO ₂ , ZrO ₂ , Mn ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgAl ₂ O ₄ , LaAlO ₃ , CaTiO ₃ , CeZrO ₄ H ₂ Al ₁₄ Ca ₁₂ O ₃₄ and other binary and poly- nary oxides known specialists in the art in their respective modifications. In a fourth preferred embodiment of the present invention, the carrier material comprises, preferably consists of, one or more zeolite materials, where the zeolite material preferably has a framework structure of the ZSM, MFI, MOR, BEA or FAU type.

The carrier material may be provided in a form containing powders, dispersions, colloids, granulates, molded bodies such as rings, spheres, extrudates or beads.

The multimetallic material preferably contains one or more intermetallic crystalline phases selected from RhPb, RhPb ₂ , Rh ₄ Pb ₅ , Rh ₂ Sn, RhSn, RhSn ₂ , RhSn ₄ , Rh ₂ Sb, RhSb, RhSb ₂ , RhSb ₃ , RhGa, Rh ₁₀ Ga ₁₇ , Rh ₃ Ga ₅ , Rh ₂ Ga ₉ , Rh ₄ Ga ₂₁ , Rh ₃ Ga ₁₆ , RhGa ₃ , RhIn, RhIn ₃ , Rh ₅ Ge ₃ , Rh ₂ Ge, RhGe, Rh ₁₇ Ge ₂₂ , RhGe ₄ , IrPb, IrSn, Ir ₅ Sn ₇ , IrSn ₂ , Ir ₃ Sn ₇ , IrSn ₄ , IrSn, Ir ₅ Sn ₇ , IrSn ₂ , Ir ₃ Sn ₇ , IrSn ₄ , Pd ₃ Pb, Pd ₁₃ Pb ₉ , Pd ₅ Pb ₃ , PdPb _, Pd ₃ Sn, Pd ₂₀ Sn ₁₃ , Pd ₂ Sn, PdSn, Pd ₅ Sn ₇ , PdSn ₂ , PdSn ₃ , PdSn ₄ , Pd ₃ Sb, Pd ₂₀ Sb ₇ , Pd ₅ Sb ₂ , Pd ₈ Sb ₃ , Pd ₂ Sb, PdSb, PdSb ₂ , Pd ₂ Ga, Pd ₅ Ga ₂ , Pd ₅ Ga ₃ , PdGa, PdGa ₅ , Pd ₇ Ga ₃ , Ru ₂ Sn ₃ , RuSn ₂ , Ru ₃ Sn ₇ , RuSb , RuSb ₂ , RuSb ₃ , NiPb, Ni ₃ Sn ₄ , Ni ₃ Sn ₂ , Ni ₃ Sn, NiSn, Ni ₅ Sb ₂ , Ni ₃ Sb, NiSb ₂ and NiSb ₃ , In particular, multimetallic materials contain one or more intermetallic crystalline phases selected from RhPb, RhPb ₂ , RhSb, Rh ₂ Sb, R hSb ₂ and Rh ₂ Sn.

The multimetallic material according to any of the preceding embodiments of the present invention is produced by a method comprising steps (i) to (iv):

(i) Providing the metal precursor, preferably in the form of a solution;

(ii) Applying the metal precursor to the carrier material;

(iia) optionally a drying step;

(iii) Restorative processing of the composite material;

(iv) Heat treatment of the composite material.

In step (i), a mixture is prepared containing a solvent and one or more sources for A, B, and C, where the solvent contains one or more of water, alcohols, polyols, acids, and bases.

In step (ii), the mixture obtained according to step (i) is brought into contact with a carrier material using a method selected from shallow impregnation, spray impregnation, wetness impregnation, and melt impregnation. A method selected from evaporation, heating or freeze drying is used to remove the solvent. Also included are precipitation methods where the carrier material is obtained in situ from metal solutions or in a separate step. This method also includes an optional drying step.

The reduction treatment step and the heat treatment steps (iii) and (iv) preferably comprise

(iii) Contacting the material obtained in step (ii) with one or more reducing agents, where the reducing agent may be provided in solid, liquid or gaseous form and contain alcohols, hydrocarbons, amines, polyols, Zn powder, H ₂ , CO, CH ₄ and C ₂ H ₄ ;

(iv) Recovery of the material obtained in step (iii) by thermal reduction under chemically inert conditions.

Heat treatment involves heating material produced under chemically inert conditions, for example in inert gases such as gases such as nitrogen, argon and helium. Heating can be carried out in muffle furnaces, microwave ovens, rotary kilns, tube furnaces and fluidized beds.

The multi-metal material and catalyst containing the multi-metal material according to any of the preceding embodiments of the present invention are used for the direct carbonylation of nitroaromatic compounds to isocyanates.

In general, the process for synthesizing isocyanates from nitroaromatic compounds and carbon monoxide comprises steps a) to d):

a) providing a mixture of reagents M1 containing nitroaromatic compounds and at least one additional component D, where D contains a suitable solvent;

b1) Providing a reactant mixture M2 containing a reactant mixture M1 and carbon monoxide or a mixture of carbon monoxide and an inert gas G, and/or

b2) providing a reaction mixture R1 containing a mixture of reactants M1 and a carbonylation catalyst containing a multi-metal material, which is described in more detail below;

c) contacting the reactant mixture M2 with a carbonylation catalyst containing, preferably consisting of, the multimetallic material I) as described in more detail above; and/or

d) contacting the reagent mixture R1 with carbon monoxide or a mixture of carbon monoxide and inert gas G;

e) obtaining a reaction mixture containing isocyanates.

The concentration of the nitroaromatic compound in mixture M1 is generally in the range of 0.01 wt.% to 60 wt.%, more preferably in the range of 0.1 wt.% to 50 wt.%, and more preferably in the range of 0.1 wt.% up to 40 wt.%. The concentration of component D in mixture M1 is generally in the range of 40 wt.% to 99 wt.%, more preferably in the range of 50 wt.% to 99 wt.%, and more preferably in the range of 60 wt.% to 99 wt. .%.

Suitable nitroaromatic compounds include simple or polyaromatic compounds with one or more nitro groups: nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, trinitrotoluene, nitronaphthalene, nitroanthracene, nitrodiphenyl, bis(nitrophenyl)methane, and in addition, simple and polyaromatic compounds having one or more nitro groups . Nitroaromatic compounds may also contain other functional groups. In the context of the present invention, functional groups are substituents attached to an aromatic ring. The functional groups may contain one or more heteroatoms selected from the group consisting of H, B, C, N, P, O, S, F, Cl, Br and I. Examples of functional groups are hydroxyl groups, halogens, aliphatic side chains, carbonyl groups, isocyanate groups, nitroso groups, carboxyl groups and amino groups.

Also included are organonitro compounds containing one or more nitro groups linked to an aliphatic chain, side chain, or ring, such as 1,6-dinitrohexene or nitrocyclohexene, nitrocyclopentene, nitromethane, nitrooctane, bis(nitrocyclohexyl)methane.

In preferred embodiments of the present invention, the nitroaromatic compound is provided in one or more aprotic organic solvents selected from chlorobenzene, dichlorobenzene, benzene, toluene, THF, dioctyl ether, chloroform, dichloromethane, n-alkanes, cycloalkanes, 1,2-diphenylbenzene, 1 -phenylnaphthalene, dibenzyl, 1,2-dimethylnaphthalene, diphenylmethane, hexadecylbenzene, tetradecylbenzene, dodecylbenzene or Solvesso 150 ND and Solvesso 200 ND.

In general, the boiling point of one or more aprotic organic solvents is in the range of 50°C to 300°C, preferably 100°C to 275°C, more preferably 125° to 255°C.

In a particular embodiment of the present invention, the solvent may be an isocyanate corresponding to the corresponding nitroaromatic compound.

In general, isocyanate preparation is carried out at a temperature in the range of 50 to 250°C, preferably 80 to 190°C, more preferably 100 to 170°C. In general, the production of isocyanates is carried out at a total pressure in the range of 1 to 200 bar, preferably 10 to 150 bar, and more preferably 15 to 100 bar. The partial pressure of carbon monoxide is generally 1 to 150 bar, preferably 1 to 120 bar and more preferably 1 to 100 bar.

In the first embodiment of the present invention, isocyanates are produced batchwise, where the following steps are carried out for the batch:

a) providing a mixture of reagents M1 containing nitroaromatic compounds and at least one additional component D, where D contains a suitable solvent;

b) providing a reaction mixture R1 containing a mixture of reactants M1 and a carbonylation catalyst containing a multi-metal material as described above;

c) contacting the reaction mixture R1 with carbon monoxide or a mixture of carbon monoxide and inert gas G;

d) obtaining a reaction mixture containing isocyanates.

In general, the concentration of the carbonylation catalyst in the reaction mixture R1 is in the range of 0.1 to 10% by weight, preferably in the range of 0.1 to 7.5% by weight, more preferably in the range of 0.2 to 5% by weight. The reaction time is generally in the range of 0.5 to 24 hours, preferably 2 to 20 hours, and more preferably 4 to 12 hours.

In the second embodiment of the present invention, isocyanates are produced continuously in a process comprising the steps of:

a) providing a mixture of reagents M1 containing nitroaromatic compounds and at least one additional component D, where D contains a suitable solvent;

b) providing a reactant mixture M2 containing a reactant mixture M1 and carbon monoxide or a mixture of carbon monoxide or a mixture of carbon monoxide and an inert gas G to obtain a reactant mixture M2.

c) contacting the reactant mixture M2 with a carbonylation catalyst containing, preferably consisting of, the multimetallic material I) as detailed above

d) obtaining a reaction mixture containing isocyanates.

In general, in the reaction mixture M2, the partial pressure of carbon monoxide is in the range of 1 to 150 bar, preferably in the range of 1 to 120 bar, and more preferably in the range of 1 to 100 bar.

Examples

Fig. 1 shows catalytic results for exemplary catalysts H, I, J according to Table 2.

Fig. 2 shows a PXRD pattern of sample J α: RhPb ₂ reflections. β: Graphite reflex.

Fig. 3 shows catalytic results for exemplary K-O catalysts according to Table 3.

For X-ray powder diffraction (XRPD) data were collected on a Bruker AXS D8 Advance. Cu Kα radiation was used to collect data. The beam was narrowed using a line focusing collimator (Soller slit, 2.5°) and a motorized divergence slit. Generator settings of 40 kV and 40 mA were used. The samples were carefully ground in a mortar and pestle and then packed in a round mount. Data collection from the round mount covered the 2θ range from 5° to 70° using a step scan with a step size of 0.02° and a measurement time of 0.2 s per step. The DIFFRAC.EVA software was used for all steps of data analysis. The phases present in each sample were determined by searching and comparing data available at the International Center for Diffraction Data (ICDD, 2015 version).

Batch Reactor Testing:

Screening in a batch reactor was carried out in a series of single experiments using batch autoclaves made from Hastelloy C276. The general experimental procedure for each screening experiment was as follows:

At the first stage, the reaction mixture was prepared by dissolving nitrobenzene in chlorobenzene. The concentration of nitrobenzene in the reaction mixture was set between 1 wt.% and 5 wt.%. An appropriate amount of catalyst was placed in an empty reactor and heated to 160°C and 10 ^-1 bar for at least 12 hours. At the second stage, the reaction mixture was loaded into the reactor without lowering the temperature and without opening the reactor, using a special loading device. After loading the reaction mixture, the autoclave was heated or cooled to the desired temperature. In the last step, the autoclave was pressurized with CO gas and nitrogen to the desired total pressure. The reaction mixture was stirred at 1000 rpm for the appropriate time.

The corresponding range of products was analyzed using a GC-MS node (GC-MS from Agilent Technologies) equipped with FID, MS and TCD detectors. The overall reaction conversion was calculated as the difference in the initial and final concentrations of the nitroaromatic compound divided by the initial concentration of the nitroaromatic compound. The concentration of the respective products in the reaction mixture was determined by GC-analytics using the appropriate response factors. The yield was determined by dividing the corresponding product concentration (in mmol/kg) by the initial concentration of the nitroaromatic compound (in mmol/kg) and multiplying this value by the mole(s) of the starting nitroaromatic compound required to obtain the mole of the corresponding product.

The difference between the combined yield of all products and the total calculated conversion is represented by the term "polymer". "Polymer" contains products formed that cannot be analyzed using the applied GC method.

Comparative examples A - C

Synthesis of oxides according to DE 1 810 828

Synthesis of Pb _0.3 Mn _0.7 O _z

To obtain samples with a Mn : Pb ratio of 0.7 : 0.3, 0.1752 mol Mn in the form of Mn(NO ₃ ) ₂ x6H ₂ O and 0.075 mol Pb in the form of Pb(NO ₃ ) _{2 were} dissolved in 1 L of deionized water with stirring. After the nitrates were dissolved, deionized water was added to 2.5 L. 1.04 mol of activated carbon was added to the solution. The pH value was adjusted to 10 by adding 8 wt.% NaOH solution. The product precipitated out and the suspension was stirred for 30 minutes to age.

The liquid medium was separated from the solids by decantation. Deionized water was added to the solids and stirred for 15 minutes. The procedure was repeated until the pH value was identical to the deionized water used. Solids were separated by filtration and dried at 100°C overnight.

Synthesis of Fe _x Mn _y O _z

To obtain MnFe samples with Mn : Fe ratio equal to 0.8 : 0.2, the method described above was applied, except that the sources of Mn and Fe were not nitrates, but chlorides (0.2 mol Mn in the form of MnCl ₂ x4H ₂ O and 0.05 mol Fe as FeCl ₃ x6H ₂ O).

1:1 physical mixtures of oxides with 5 wt% Rh or Pd impregnated on activated carbon were prepared according to GB1315813 A and catalytically tested. Table 2 shows the results of nitrobenzene reduction and CO incorporation into nitrosobenzene for mixtures of (A) 5 wt.% Pd on C and Pb _0.3 Mn _0.7 O _x , (B) 5 wt.% Rh on C and Pb _0.3 Mn _0.7 O _x and ( C) 5 wt% Rh on C and Fe _0.2 Mn _0.8 O _x . Reaction conditions were p _{= 100 barg} , T = 190 ^° C. and reaction time 6 h. nitrosobenzene, azo- and azoxybenzene. However, the other two systems _tested , (B) 5 wt.% Rh on C and Pb _{x Mn y} O _z and (C ₎ 5 wt. , as well as "polymer".

Comparative examples D - G

Comparative Examples D-G were prepared by preparing individual metal solutions as described in step (i) and impregnating the solutions onto an activated carbon carrier as described in step (ii). The impregnation method followed was moisture capacity impregnation. The drying step (iia) at 80°C was performed after the impregnation. The amount of metal deposited on the support was 5 wt.% of the weight of the support. Appropriate metal components and solvents can be taken from Table 1.

Table 1

Metal Metal containing component Solvent Rh Rh(NO ₃ ) _{3 H2O} Pb Pb(NO ₃ ) _{3 H2O} Sb Sb(CH ₃ COO) ₃ Tartaric acid (4M) sn S&C ₂ O ₄ Nitric acid (35%) Pd Pd(NO ₃ ) ₂ Nitric acid (35%) In In(NO ₃ ) _{3 H2O} Ni Ni(NO ₃ ) _{2 H2O} Ga Ga(NO ₃ ) _{3 H2O}

Catalytic results for examples A - G

Comparative examples A - G were catalytically tested. Table 2 shows the yields of nitrobenzene reduction (step 1) and incorporation of CO into nitrosobenzene to form phenylisocyanate (step 2). For mixtures (A) 5 wt.% Pd on C and Pb _0.3 Mn _0.7 O _x , (B) 5 wt.% Rh on C and Pb _0.3 Mn _0.7 O _x and (C) 5 wt.% Rh on C and Fe _0.2 Mn _0.8 O _x reaction conditions were: p = 100 barg, T = 190 °C and reaction time 6 hours. Physical mixture (A) of 5 wt.% Pd on C and Pb _x Mn _y O _z did not give phenyl isocyanate at all, but the formation of nitrosobenzene, azo- and azoxybenzene was observed. However, two other systems tested, (B) 5 wt.% Rh on C and _{Pb x Mn y} O _z and (C ₎ 5 wt. azoxybenzene, as well as a "polymer"

For single metal metal catalysts D - G, the reaction conditions were p = 100 barg, T = 160° C. and reaction time 4 hours. None of the single metal metal catalysts produced phenyl isocyanate.

Table 2: Results for Comparative Examples. PI = Phenyl isocyanate; AZO=Azobenzene; AZY = Azoxybenzene; NSB = Nitrosobenzene; DCD = Diphenylcarbodiamide; POL = Polymer

No. Composition PI
[%] AZO
[%] AZY
[%] NSB
[%] DCD
[%] POL
[%] A Pd on C + Pb _0.3 Mn _{0.7 Ox} 0 1.79 20.16 1.50 0 0 B Rh on C + Pb _0.3 Mn _{0.7 Ox} 0.34 5.92 0.42 0 0 9.88 C Rh on C + Fe _0.2 Mn _{0.8 Ox} 3.69 0.92 0.31 0 0 4.58 D 5 wt% Rh on C 0 0 0 0 0 0 E 5 wt% Pb on C 0 0 0.12 0 0 0.3 F 5 wt% Sb on C 0 0 0 0 0 0 G 5 wt% Sn on C 0 0 0 0 0 0

The results of Comparative Examples B and C show that both reaction steps were performed in a one-pot synthesis by combining the functionality of two catalysts: an oxide responsible for reaction step 1 and a parent metal responsible for reaction step 2.

H-O

The preparation of examples H-J according to the present invention was carried out by preparing two separate solutions of the individual metals as described in step (i). After that, a mixture was obtained from these solutions. The concentration of the individual metal solutions and the corresponding volume used to prepare the mixture are shown in Table 3. The mixture was impregnated onto an activated carbon carrier as described in step (ii). An impregnation method was used, which was the impregnation method by moisture capacity, and the drying step (iia) was carried out at 80°C after each impregnation step.

The amount of metal A deposited on the support was to be 5 wt.% of the weight of the support. The amount of metal B was calculated according to the general formula. After the drying step, the composite materials of examples HJ according to the present invention received a combined reduction and heat treatment for 5 hours at 500°C (stages iii and iv) using a muffle furnace and N ₂ atmosphere. Appropriate masses, concentrations and volumes of carrier can be taken from Table 3. Metal containing components and solvents can be taken from Table 1.

The preparation of examples of K-O according to the present invention was carried out by preparing solutions of individual metals, as described in step (i), and successively impregnating the solutions onto an oxide carrier, as described in step (ii). The impregnation method followed was the moisture capacity impregnation method. For examples K, L, and M, an individual metal solution containing metal A was first impregnated. For examples N and O, an individual metal solution containing metal B was impregnated first. For example N and O, multiple impregnations were required for each solution (see details in table 3). The drying step (iia) was performed at 80°C after each impregnation step. The amount of metal A deposited on the carrier was to be 5 wt.% of the weight of the substrate. The amount of metal B was calculated by the general formula. After the final drying step, the composite material was suspended in polyethylene glycol (polyol) and subjected to a reduction treatment as described in step (iii). The reduction was carried out for 20 minutes at 200°C using a 1000 W microwave oven under N ₂ atmosphere. The recovered composite material was separated from the polyol and heat treated as described in step (iv) for 5 hours at 500°C using a muffle furnace and N ₂ atmosphere.

Appropriate masses, concentrations and volumes of carrier can be taken from Table 3. Metal containing components and solvents can be taken from Table 1.

Table 3

No. Composition A _x B _y one 2 3 four 5 6 7 eight 9 H _Rh2Sn C 2.5 1.16 1.07 one one 6.32 one a I RhSb C 2.5 1.16 1.11 one one 1.29 one a J RhPb ₂ C 2.5 1.16 1.32 one one 3.04 one a K RhPb Al ₂ O ₃ ^*) 3 1.15 1.41 one one 1.62 one b L RhPb ₂ Al ₂ O ₃ ^*) 3 1.15 1.59 one one 3.65 one b M RhPb ₂ Al ₂ O ₃ ^**) 3 1.15 1.59 one one 3.65 one b N RhPb _{2 Mn2O3 _} 33.5 1.148 17.75 3 1.5 27.17 5 b O RhSb _TiO2 ^***) 2.5 1.16 1.11 2 one 1.30 2 b

1: Carrier material. *) specific surface area: 100 ^m2

**) specific surface area: 5 ^m2

***) Rutile

2: Amount of carrier material [g].

3: Concentration of the solution containing metal A [mol/l].

4: Total volume of solution containing metal A used for impregnation [ml].

5: Number of stages of impregnation of a solution containing metal A.

6: Concentration of the solution containing metal B [mol/l].

7: Total volume of solution containing metal B used for impregnation [ml].

8: Number of stages of impregnation of a solution containing metal B.

9: Heating method. a) Muffle Furnace 500°C; 5h; N ₂ atmosphere.

b) Microwave (1000W) 200°C; 20 minutes; N ₂ atmosphere

Catalytic results of examples H - O

Table 4 and FIG. 1 show the results of nitrobenzene reduction and incorporation of CO into nitrosobenzene. The reaction conditions were p = 100 barg, T = 160°C and a reaction time of 4 h.

Table 4: Results of examples H - O

No. Composition PI
[%] AZO
[%] AZY
[%] NSB [%] DCD
[%] POL
[%] H Rh ₂ Sn to C 2.45 0.40 0 0 0 0.95 I RhSb to C 14.27 0.89 1.87 0 0.30 18.43 J RhPb ₂ on C 26.57 3.21 5.08 0 2.55 20.29 K RhPb on Al ₂ O ₃ 3.60 1.98 0.34 0 0 4.68 L RhPb ₂ on Al ₂ O ₃ 4.50 2.60 1.69 0 0 6.09 M RhPb ₂ on Al ₂ O ₃ 2.46 0.14 0.35 0 0 2.24 N RhPb ₂ on Mn ₂ O ₃ 4.07 1.75 0.39 0 0 4.22 O RhSb on TiO ₂ 2.26 0 0 0 0 1.18

The results show that - in contrast to metal catalysts based on individual metals - multi-metal catalysts give phenyl isocyanate as a product.

On FIG. 2 shows a PXRD diagram of sample J proving that the multi-metal catalyst consists of an intermetallic compound RhPb ₂ (α) on an amorphous carbon support. However, some traces of graphite (β) coming from the carbon support have also been identified. In addition, graphite reflections appeared as a consequence of the heat treatment step.

Testing in a continuous reactor:

Screening in a continuous reactor was carried out in a series of experiments using a trickled-bed reactor system. The general experimental procedure for each screening experiment was as follows:

At the first stage, the reaction mixture was prepared by dissolving nitrobenzene or dinitrotoluene in chlorobenzene. The concentration of the corresponding nitroaromatic compound in the reaction mixture ranged from 1 wt.% to 3 wt.%.

The reactor used was a tubular reactor 40 cm long with an internal diameter of 0.4 cm.

Inside the reactor was loaded with 1 ml of the appropriate catalyst, sieved to a fraction size of 125-160 μm. SiO ₂ was used as an inert material before and after the layer.

The reactor was heated to 160°C in N ₂ atmosphere for at least 12 hours to remove residual water. After that, the temperature in the reactor was brought to the desired value.

In the next step, the reaction mixture was mixed with CO or a mixture of CO and N ₂ and fed into the reactor. The liquid hourly space velocity (LHSV) was set between 1 h ^-1 and 4 h ^-1 . Whereas the gas hourly space velocity (GHSV) w was set between 500 and 3500 h ^-1 .

The resulting mixture of products was collected over time and analyzed by GC.

All experimental parameters are shown in Table 6.

The corresponding range of products was analyzed using a GC-MS node (GC-MS from Agilent Technologies) equipped with FID, MS and TCD detectors. The total conversion of each reaction was calculated as the difference between the reactor inlet (initial) concentration of the reactor and the concentration of the nitroaromatic compound in the product mixture, divided by the initial concentration of the nitroaromatic compound. The concentration of the respective products in the product mixture was determined by GC analytics using the appropriate response factors. The yield was determined by dividing the corresponding product concentration (in mmol/kg) by the concentration of the nitroaromatic compound (in mmol/kg) and multiplying this value by the mole (moles) of the starting nitroaromatic compound required to form the mole of the corresponding product.

The difference between the combined yields of all products and the total calculated conversion of nitroaromatic compounds is represented by the term "polymer". "Polymer" contains products formed that cannot be analyzed using the applied GC method.

Obtaining examples of H-BI according to the present invention by obtaining separate solutions of individual metals, as described in stage (i). After that, a mixture was prepared from these solutions. The concentration of individual metal solutions and the corresponding volume used to prepare the mixture are shown in Table 5. The mixture was impregnated onto various supports as described in step (ii). An impregnation method was used which consisted of impregnation according to moisture capacity, and a drying step (iia) was carried out at 80° C. after each impregnation step.

In some examples, the support was made from a mixture of two oxides. In this case, the oxides were physically mixed using a hand mill. The resulting oxide mixture was calcined at 500°C before impregnation.

The amount of metal A deposited on the support should be from 1 to 5 wt.% of the weight of the support. The amount of metal B was calculated by the general formula. After the drying step, the composite materials of examples H-BI according to the present invention were subjected to reduction and heat treatment for 5 hours at 500 °C (stages iii and iv) using a muffle furnace and N ₂ atmosphere. The masses, concentrations and volumes of the respective carriers can be taken from Table 5. Metal containing components and solvents can be taken from Table 1.

Table 5:

No. Composition
_{AxBy _} one 2 3 four 5 6 7 eight 9 H _Rh2Sn C 2.5 0 1.16 1.07 one one 6.32 one I RhSb C 2.5 0 1.16 1.11 one one 1.29 one J RhPb ₂ C 2.5 0 1.16 1.32 one one 3.04 one O RhSb _TiO2 **) 2.5 0 1.16 1.11 2 one 1.30 2 P _{Rh2Sn TiO2} **) 2.5 0 1.16 1.07 2 one 6.32 2 Q RhGa _TiO2 **) eight 0 1.15 3.38 2 2 1.94 2 R Rh In _TiO2 **) eight 0 1.15 3.38 3 one 3.89 3 S Pd ₅ Sb _{2 TiO2} **) 5 0 3.63 0.65 one one 0.94 one T Pd ₈ Sb _{3 TiO2} **) 5 0 3.63 0.65 one one 0.88 one U PdPb _{2 TiO2} **) 5 0 3.41 0.69 one 1.5 3.13 2 V RhSb _TiO2 **) 21.2 0 1.16 1.78 one one 2.05 one W RhSb TiO ₂ **) + 5% ZnO 3.8 0.2 one 0.39 one one 0.33 one X RhSb TiO ₂ **) + 10% ZnO 10.5 1.17 one 1.14 one one 1.14 one Y RhSb TiO ₂ **) + 20% ZnO 3.2 0.8 one 0.39 one one 0.33 one Z RhSb TiO ₂ **) + 30% ZnO 2.8 1.2 one 0.39 one one 0.33 one AA RhSb TiO ₂ **) + 40% ZnO 2.4 1.6 one 0.39 one one 0.33 one AB RhSb TiO ₂ **) + 50% ZnO 1.75 1.75 one 0.34 one one 0.29 one AD RhSb TiO ₂ **) + 67% ZnO 0.85 1.65 one 0.24 one one 0.21 one AE RhSb ZnO 0 ten one 0.97 one one 0.97 one AF RhSb TiO ₂ *) + 10% CaO 3.51 0.39 1.13 0.33 one one 0.38 one AG RhSb TiO ₂ **) + 10% CaO 6.08 0.68 1.13 0.58 one one 0.65 one AH RhSb TiO ₂ *) + 10% MgO 3.89 0.43 1.13 0.37 one one 0.42 one AI RhSb TiO ₂ **) + 10% MgO 5.04 0.56 1.13 0.48 one one 0.54 one AJ RhSb TiO ₂ *) +10% V ₂ O ₅ 5.54 0.62 1.13 0.53 one one 0.6 one AK RhSb _{Mn2O3 _} 0 12.2 1.13 1.05 one one 1.19 one AL RhSb Mn ₂ O ₃ + 10% CaO 5.49 0.61 1.13 0.52 one one 0.59 one AM RhSb Mn ₂ O ₃ + 45% Fe ₂ O ₃ 7.55 6.17 1.13 1.19 one one 1.35 one AN RhSb Mn ₂ O ₃ + 35% Fe ₂ O ₃ 8.99 4.84 1.13 1.19 one one 1.34 one AO RhSb Mn ₂ O ₃ + 25% Fe ₂ O ₃ 10.4 3.48 1.13 1.19 one one 1.35 one AP RhSb Mn ₂ O ₃ + 10% MgO 5.03 0.56 1.13 0.48 one one 0.54 one AQ RhSb Mn ₂ O ₃ + 30% PbO 12.3 5.28 1.13 1.51 one one 1.71 one AR RhSb Mn ₂ O ₃ + 10% ZnO 6.44 0.72 1.13 0.61 one one 0.69 one AS RhSb MoO ₃ 7.54 0 1.13 0.65 2 one 0.73 2 AT RhSb MoO ₃ +10% CaO 5.49 0.61 1.13 0.52 one one 0.59 one AU RhSb MoO ₃ +10% MgO 6.80 0.76 1.13 0.65 one one 0.73 one AV RhSb MoO ₃ +10% ZnO 7.25 0.81 1.13 0.69 one one 0.78 one A.W. RhSb C 3.52 0 1.16 0.29 one one 0.34 one AX RhSb Elorit 2 0 1.15 0.89 one one 1.03 one AY RhSb Bi ₂ O ₃ 18.2 0 1.13 1.56 2 one 1.77 2 AZ RhSb CaO 10.0 0 one 0.97 one one 0.97 one BA RhSb _{Co2O3 _} 14.6 0 1.13 1.26 2 one 1.42 2 BB RhSb _{Cr2O3 _} 8.58 0 1.13 0.74 one one 0.83 one BC RhSb _{Fe2O3 _} 7.17 0 1.13 0.62 one one 0.69 one BD RhSb Fe ₃ O ₄ 7.39 0 1.13 0.63 one one 0.71 one BE RhSb V ₂ O ₅ 5.7 0 1.13 0.49 2 one 0.55 2 bf RhSb _WO3 12.6 0 1.13 1.09 one one 1.23 one BG RhSb _ZrO2 one 0 1.13 0.09 one one 0.1 one BH RhSb _ZrO2 one 0 1.13 0.09 one one 0.1 one BI RhSb ZrWO _x 5.79 0 1.13 0.5 one one 0.56 one

1: Carrier material. *) specific surface area: > ^5m2

**) Rutile

2: Amount of carrier material I [g].

3: Amount of carrier material II [g].

4: Concentration of the solution containing metal A [mol/l].

5: Total volume of solution containing metal A used for impregnation [ml].

6: Number of stages of impregnation of a solution containing metal A.

7: Concentration of the solution containing metal B [mol/l].

8: Total volume of solution containing metal B used for impregnation [ml].

9: Number of stages of impregnation of a solution containing metal B.

Table 6: Overview of experimental parameters.

No. 1a 2a 3a 4a 5a 6a 7a 8a a NB one 160 100 100 0 four 2000 b NB one 120 100 100 0 four 2000 c NB one 80 100 100 0 four 2000 d 2,4-DNT one 60 100 100 0 four 2000 e 2,4-DNT one 80 100 100 0 four 2000 f 2,4-DNT one 100 100 100 0 four 2000 g 2,4-DNT one 120 100 100 0 four 2000 h 2,4-DNT one 80 100 100 0 one 2000 i 2,4-DNT one 80 100 100 0 four 500 j 2,4-DNT one 80 100 100 0 one 500 k 2,4-DNT one 120 100 100 0 one 2000 l 2,4-DNT one 120 100 100 0 four 500 m 2,4-DNT one 120 100 100 0 one 500 n 2,4-DNT one 130 100 100 0 four 2000 o 2,4-DNT one 140 100 100 0 four 2000 p 2,4-DNT one 120 100 100 0 one 2750 q 2,4-DNT one 120 100 100 0 one 3500 r 2,4-DNT one 140 100 100 0 3 2000 s 2,4-DNT one 140 100 100 0 2 2000 t 2,4-DNT one 140 100 100 0 one 2000 v 2.4 DNT and 2.6 DNT 3 140 fifty 100 0 one 2000

1a: Boot mix

NB) Nitrobenzene

2,4-DNT) 2,4-Dinitrotoluene

2,4-DNT and 2,6-DNT) Mixture of 20 wt% 2,6-DNT and 80 wt% 2,4-DNT

2a: Incoming concentration [wt.%]

3a: Temperature [°C]

4a: Total pressure [bar]

5a: CO concentration [vol%]

6a: N2 concentration [vol%]

7a: LHSV (Liquid Hourly Space Velocity) [h ^-1 ]

8a: GHSV (Gas Hourly Space Velocity) [h ^-1 ]

Table 7: Results of catalytic tests in a nitrobenzene trickle-bed plant: PI = Phenyl isocyanate; AZO=Azobenzene; AZY = Azoxybenzene; NSB = Nitrosobenzene; DCD = Diphenylcarbodiamide; POL = Polymer. X = General transformation.

No. # PI [%] AZO [%] AZY [%] NSB [%] DCD [%] POL [%] I a 32.01 1.71 0.00 0 1.09 65.20 J a 1.67 1.69 18.78 0 0.03 58.53 O a 49.07 2.31 0.00 0 4.10 44.53 H b 7.54 0.30 0.48 0 0.01 10.43 O b 72.20 2.32 1.73 0 1.02 18.96 H c 0.79 0.03 0.09 0 0 2.77 O c 9.93 0.73 0.51 0 0 5.31

The results show that isocyanates can be obtained from nitroaromatic compounds in a continuous process.

Table 8: Results of catalytic tests in a trickle bed plant with DNT feed mixture: TDI = 2,4-Toluene diisocyanate; TNI = Toluene nitroisocyanates, AZOC = Azo compounds; AZYC = Azoxy compounds; NSC = Nitroso compounds; AC = Amine compounds; POL = Polymer.

No. # TDI [%] TNI [%] AZOC [%] AZYC [%] NSC [%] AC [%] POL [%] O d 0.05 11.43 2.01 2.75 0.06 1.01 1.43 O e 0.15 16.65 1.57 2.74 0.15 0.97 1.25 O f 0.89 33.85 1.54 3.60 0.39 1.08 3.10 O g 3.31 55.68 0.99 2.59 0.69 1.05 1.15 O h 0.48 25.22 1.03 1.55 0.19 1.01 1.62 O i 0.00 4.88 0.83 0.32 0.20 0.81 2.79 O j 0.04 6.17 0.81 0.43 0.18 0.84 6.82 O k 35.57 48.82 0.27 0.98 0.41 0.16 10.67 O l 2.73 48.11 0.80 2.03 0.76 1.02 1.23 O m 4.28 48.85 0.76 1.95 0.68 0.93 1.23 O n 5.02 56.79 0.70 2.12 0.78 0.89 8.99 O o 12.90 71.06 0.48 2.09 0.98 0.74 1.20 O p 14.16 70.82 0.40 1.58 0.54 0.68 3.60 O q 14.55 72.89 0.42 1.66 0.55 0.76 1.45 O r 0.00 2.29 0.65 0.36 0.32 0.74 3.51 O s 19.26 69.01 0.28 1.35 0.72 0.69 3.99 O t 47.52 36.47 0.19 0.71 0.36 0.20 14.68 P d 0.04 5.87 0.95 1.28 0.00 1.73 1.26 P e 0.04 5.03 1.40 1.14 0.31 1.44 2.17 P f 0.11 8.75 1.81 1.53 0.89 1.53 5.71 P g 0.12 7.44 1.50 0.66 1.34 1.48 5.15 P h 0.00 1.09 1.40 0.31 0.48 1.43 4.02 P i 0.00 0.14 0.77 0.00 0.14 0.80 1.59 P j 0.00 0.31 0.94 0.09 0.21 1.01 5.70 P k 0.40 9.74 1.48 1.55 1.75 2.54 17.54 P l 0.00 2.35 1.06 0.21 1.00 1.12 4.34 P m 0.08 4.41 1.21 0.44 1.27 1.34 5.76 P n 0.08 4.54 1.21 0.49 1.53 1.31 18.32 P o 0.15 7.65 1.54 0.75 2.13 1.60 7.80 P p 0.15 4.70 2.81 0.77 1.24 3.69 11.38 P q 0.14 4.29 3.02 0.83 1.08 4.01 12.78 P r 0.00 0.04 0.60 0.00 0.00 0.76 2.17 P s 0.16 5.42 1.87 0.66 1.69 2.32 8.43 P t 0.27 7.66 2.41 1.14 1.29 3.24 18.15

The results show that nitroaromatic compounds containing multiple nitro groups can be directly converted to isocyanates. Since the number of structural isomers increases with the number of nitro groups, the yields are presented as group yields.

As stated above, intermediates such as nitroso compounds or partially carbonylated nitroaromatic compounds such as toluene nitroisocyanates (TNI) can be obtained from an incomplete reaction, but are still considered to be a successful result in terms of this invention.

Table 9: Results of catalytic tests in a trickle-bed plant with DNT feed mixture: TDI = 2,4+2,6-Toluene diisocyanate; TNI = (toluene nitroisocyanate isomers, By-products = Azo compounds, Azoxy compounds, Nitroso compounds, Amine compounds, Polymer.

No. # TDI TNI by-products Q v 0.00 0.08 7.02 R v 0.06 2.04 17.47 S v 0.00 1.57 11.66 T v 0.00 2.24 5.15 U v 0.00 0.12 5.17 V v 7.00 41.03 20.4 W v 8.48 42.88 44.37 X v 33.81 59.80 5.81 Y v 16.91 39.11 40.35 Z v 19.11 42.01 35.71 AA v 23.51 40.92 32.51 AB v 11.34 58.96 23.51 AD v 19.80 47.35 29.94 AE v 1.68 29.90 43.88 AF v 12.38 61.52 16.15 AG v 18.12 71.15 5.18 AH v 10.09 60.85 13.53 AI v 23.67 64.83 10.08 AJ v 5.73 44.05 28.61 AK t 4.11 45.56 23.93 AL v 18.21 73.10 3.70 AM v 2.34 46.49 9.53 AN v 2.05 43.53 8.41 AO v 2.05 44.31 8.37 AP v 1.77 37.36 17.05 AQ v 0.00 0.21 15.97 AR v 13.60 57.68 17.72 AS v 0.02 2.03 3.84 AT v 0.00 3.36 9.63 AU v 1.65 38.77 8.90 AV v 0.33 16.63 11.89 A.W. v 5.56 32.18 51.16 AX v 0.19 12.07 12.19 AY v 0.00 0.17 13.84 AZ v 0.00 15.81 25.41 BA v 1.98 34.08 17.09 BB v 0.00 0.24 12.38 BC v 1.72 35.88 15.64 BD v 1.27 31.77 13.40 BE v 0.00 1.91 6.57 bf v 3.30 46.46 14.42 BG v 0.50 16.21 30.92 BH v 0.01 3.07 22.84 BI v 0.00 0.00 8.61

Claims (37)

1. A method for producing an aromatic isocyanate by direct carbonylation of a nitroaromatic compound by reaction of a nitroaromatic compound with carbon monoxide in the presence of a catalyst, characterized in that the catalyst contains a multimetallic material containing one or more binary intermetallic phases of the general formula A _x B _y , where A is one or more elements selected from Rh and Pd, B is one or more elements selected from Sn, Sb, Pb, Ga and In, x is in the range from 0.1 - 10, y is in the range from 0.1 - 10. 2. The method according to p. 1, characterized in that A is Rh, B is one or more elements selected from Pb, Sn and Sb. 3. The method according to p. 1, characterized in that the multimetallic material contains one or more components C, where the component C contains or consists of A or B, which are not part of the intermetallic phase A _x B _y . 4. The method according to p. 1, characterized in that the multimetallic material contains one or more C components, where the C component contains or consists of one or more elements selected from O, N, C, H, Mg, Ca, Mn, Fe , Co, Ni, Zn, Ga. 5. The method according to p. 1, characterized in that the multimetallic material is located on the carrier material. 6. The method according to claim 1, characterized in that the nitroaromatic compound is selected from nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, trinitrotoluene, nitronaphthalene, nitroanthracene, nitrodiphenyl, bis(nitrophenyl)methane and other mono- and polyaromatic compounds having one or more nitro groups . 7. The method according to any one of paragraphs. 1-6, characterized in that it is carried out periodically. 8. The method according to any one of paragraphs. 1-6, characterized in that it is carried out continuously. 9. Catalyst for direct carbonylation of a nitroaromatic compound to the corresponding aromatic isocyanate, containing a multimetallic material containing one or more binary intermetallic phases of the general formula A _x B _y , where A is one or more elements selected from Rh and Pd, B is one or more elements selected from Sn, Sb, Pb, Ga and In, x is in the range from 0.1 - 10, y is in the range from 0.1 - 10. 10. The catalyst according to claim 9, characterized in that A is Rh, B is one or more elements selected from Pb, Sn and Sb. 11. The catalyst according to claim 9, characterized in that the multimetallic material contains one or more C components, where the C component contains or consists of A or B that are not part of the A _x B _y intermetallic compound. 12. The catalyst according to claim 9, characterized in that the multimetallic material contains one or more C components, where the C component contains or consists of one or more elements selected from O, N, C, H, Mg, Ca, Mn, Fe , Co, Ni, Zn and Ga. 13. The catalyst according to claim 9, characterized in that the multimetallic material contains one or more binary intermetallic crystalline phases selected from RhPb, RhPb ₂ , Rh ₄ Pb ₅ , Rh ₂ Sn, RhSn, RhSn ₂ , RhSn ₄ , Rh ₂ Sb , RhSb, RhSb ₂ , RhSb ₃ , RhGa, Rh ₁₀ Ga ₁₇ , Rh ₃ Ga ₅ , Rh ₂ Ga ₉ , Rh ₄ Ga ₂₁ , Rh ₃ Ga ₁₆ , RhGa ₃ , RhIn, RhIn ₃ , Pd ₃ Pb, Pd ₁₃ Pb ₉ , Pd ₅ Pb ₃ , PdPb, Pd ₃ Sn, Pd ₂₀ Sn ₁₃ , Pd ₂ Sn, PdSn, Pd ₅ Sn ₇ , PdSn ₂ , PdSn ₃ , PdSn ₄ , Pd ₃ Sb, Pd ₂₀ Sb ₇ , Pd ₅ Sb ₂ , Pd ₈ Sb ₃ , Pd ₂ Sb, PdSb, PdSb ₂ , Pd ₂ Ga, Pd ₅ Ga ₂ , Pd ₅ Ga ₃ , PdGa, PdGa ₅ and Pd ₇ Ga ₃ . 14. Catalyst according to claim 13, characterized in that the multimetallic material contains one or more binary intermetallic crystalline phases selected from RhPb, RhPb ₂ , RhSb, Rh ₂ Sb, RhSb ₂ and Rh ₂ Sn. 15. The catalyst according to any one of paragraphs. 9-14, characterized in that the multimetallic material is located on the carrier material. 16. The method of obtaining a catalyst as defined in paragraph 15, including stages (i) and (iv): (i) providing one or more precursors for elements A and B and optionally component C in the form of a solution; (ii) applying the metal precursors to the carrier material; (iii) restorative processing of the composite material; (iv) heat treatment of the composite material. 17. The method of claim 16 wherein the solution contains one or more solvents selected from water, alcohols, polyols, acids and bases. 18. The method according to p. 16, including the steps: (iii) contacting a carrier material containing metal precursors with one or more reducing agents in solid, liquid or gaseous form, selected from alcohols, hydrocarbons, amines, polyols, Zn powder, H ₂ , CO, CH ₄ and C _{2 H4} , and (iv) reducing the carrier material containing metal precursors by thermal reduction under chemically inert conditions. 19. The method according to any one of paragraphs. 16-18, where step (iii) and (iv) are carried out in one step.

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