EP4713309A1 - Process for the isomerization of aromatic amines - Google Patents

Process for the isomerization of aromatic amines

Info

Publication number
EP4713309A1
EP4713309A1 EP24727711.4A EP24727711A EP4713309A1 EP 4713309 A1 EP4713309 A1 EP 4713309A1 EP 24727711 A EP24727711 A EP 24727711A EP 4713309 A1 EP4713309 A1 EP 4713309A1
Authority
EP
European Patent Office
Prior art keywords
methylenedianiline
feed
catalyst
mixture
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP24727711.4A
Other languages
German (de)
French (fr)
Inventor
Trees Maria DE BAERDEMAEKER
Matthias Maximilian NIEDERMAIER
Torsten Mattke
Jens Ferbitz
Andrei-Nicolae PARVULESCU
Dirk De Vos
Ka Yan CHEUNG
Sam VAN MINNEBRUGGEN
Toshiyuki Yokoi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Publication of EP4713309A1 publication Critical patent/EP4713309A1/en
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/54—Preparation of compounds containing amino groups bound to a carbon skeleton by rearrangement reactions
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/68—Preparation of compounds containing amino groups bound to a carbon skeleton from amines, by reactions not involving amino groups, e.g. reduction of unsaturated amines, aromatisation, or substitution of the carbon skeleton
    • C07C209/78—Preparation of compounds containing amino groups bound to a carbon skeleton from amines, by reactions not involving amino groups, e.g. reduction of unsaturated amines, aromatisation, or substitution of the carbon skeleton from carbonyl compounds, e.g. from formaldehyde, and amines having amino groups bound to carbon atoms of six-membered aromatic rings, with formation of methylene-diarylamines
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C211/00—Compounds containing amino groups bound to a carbon skeleton
    • C07C211/43—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
    • C07C211/44—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring
    • C07C211/49—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring having at least two amino groups bound to the carbon skeleton
    • C07C211/50—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring having at least two amino groups bound to the carbon skeleton with at least two amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The present invention relates to a process for the isomerization of 2,4'- methylenedianiline and/or, preferably and, 2,2'- methylenedianiline to 4,4'-methylenedianiline, respectively, the process comprising (1) preparing a feed F2 comprising 2,4'-methylenedianiline and/or, preferably and, 2,2'- methylenedianiline and optionally further comprising aniline; (2) providing a catalyst C2 comprising a Bronsted acid; (3) contacting the feed F2 prepared in (1) with the catalyst C2 provided in (2), obtaining a mixture M2 comprising 4,4'-methylenedianiline as a reaction product; (4) optionally separating the 4,4'-methylenedianiline from the reaction product obtained in (3); wherein the feed F2 in (1) comprises 5 wt.-% or less of formaldehyde.

Description

Process for the isomerization of aromatic amines TECHNICAL FIELD The present invention relates to a process for the isomerization of 2,4’- methylenedianiline and/or, preferably and, 2,2’- methylenedianiline to 4,4’-methylenedianiline, as well as to a pro- cess for the isomerization of 2,2’- methylenedianiline to 2,4’- methylenedianiline. INTRODUCTION Methylene diphenylene diamine and polymethylene polyphenylene polyamines are widely used as intermediates in the production of methylene diphenylene diisocyanates and polymethylene polyphenylene polyisocyanates. The isocyanates then are applied in polymerization reactions with themselves and CH-acidic compounds to yield polyisocyanurates, polyurethanes and poly- ureas. A mixture of methylenedianiline (MDA) isomers (p,p or 4,4’, o,p or 2,4’, and o,o or 2,2’) and oligomers is produced during this synthesis, wherein 4,4’-MDA is preferred in many applications. This preference is due to the higher reactivity of isocyanate groups in para- position as well as the physical properties resulting from this isomer. While the 2,4’-MDA has values in flexible or soft applications like soft foams or adhesives, the 2,2’-MDA is an undesired side-product. Further processing of these product streams results in side streams with an increased 2,4’- and/or 2,2’-MDA isomer content. A method for the conversion of these streams into a 4,4’- MDA richer product would be desirable, wherein the conversion of the amino-group in ortho- position of the 2,2’- and/or 2,4’-MDA isomers to the respective isomer with the amino-group in para-position (4,4’-MDA) would be desirable. P. J. Whitman et al., ‘Protodealkylation of bis(aminophenyl)methanes’, Tetrahedron Letters, Vol. 27, pages 1887-1890, relates to the isomerization of 2,4’-methylenedianiline with Wyoming ben- tonite in the presence of aniline. EP 0329367 A2 relates to a method of preparing 4,4’-MDA from aniline and a methylenating agent by using a dealuminated Y type zeolite, a fluorine treated dealuminized Y type zeolite or a metal ion-treated product of dealuminized Y type zeolite. WO 2021/116419 A relates to a catalytic material and to its use for producing one or more of 4,4’-MDA, 2,2’-MDA, 2,4’-MDA or oligomers thereof, wherein the catalytic material comprises an oxidic support, wherein the oxidic support comprises an element Eos1 selected from the group consisting of Ti, Zr, Al , Si, and mixtures of two or more thereof, and further comprising a sup- ported material supported on the oxidic support, wherein the supported material comprises an element EsM1 selected from the group consisting of Ti, Zr, V, Nb, Ta, Mo, W, Ge, Sn, Sc, Y, La, Ce, Nd, Pr, Hf, Cr, Fe, Co, Ni, Cu, Zn, Pb, and mixtures of two or more thereof. Despite the advances made with regard to the production of 4,4’-MDA, there remains the need for a highly selective process to increase the concentration of 4,4’-MDA, including oligomers and polymers thereof at all stages of the production process by treating side and/or product streams containing or enriched in 2,2’- and/or 2,4’-MDA. In particular, there remains the need for catalysts displaying improved selectivities towards 4,4’-MDA, while suppressing unwanted 2,2’-MDA, including oligomers and polymers thereof, as well as catalysts displaying improved selectivities towards 2,4’-MDA for making use of any unwanted 2,2’-MDA in the feeds to be treated. DETAILED DESCRIPTION Thus, it was the object of the present invention to provide an improved process for the pro- duction of 4,4’-methylenedianiline by the isomerization of a feed, preferably of a product feed, comprising one or more of 2,2’-methylenedianiline and 2,4’-methylenedianiline. Said object is achieved by the process of the present invention, consisting of a highly selec- tive isomerization of 2,4’-methylenedianiline towards 4,4’-methylenedianiline. Surprisingly, it was found that the process of the present invention permits an efficient conversion of a 2,4’- methylenedianiline and/or 2,2’- methylenedianiline comprising product feed to an 4,4’-meth- ylenedianiline enriched product using Bronsted acid and in particular zeolite catalysts with high selectivity towards said isomer. Further, it has unexpectedly been found that the in- ventive process not only restricts conversion to unwanted side products, in particular 2,2’- methylenedianiline and acridine, but also displays a high selectivity for the isomerization of 2,2’- methylenedianiline to 2,4’- methylenedianiline, the latter being not only valuable as such as a precursor for the production of soft polymers, but also as a precursor for 4,4’- methylenedianiline via the inventive process. Therefore, the present invention relates to a process for the isomerization of 2,4’- methylene- dianiline and/or, preferably and, 2,2’- methylenedianiline to 4,4’-methylenedianiline, respec- tively, the process comprising (1) preparing a feed F2 comprising 2,4’-methylenedianiline and/or, preferably and, 2,2’- meth- ylenedianiline and optionally further comprising aniline; (2) providing a catalyst C2 comprising a Bronsted acid; (3) contacting the feed F2 prepared in (1) with the catalyst C2 provided in (2), obtaining a mix- ture M2 comprising 4,4’-methylenedianiline as a reaction product; (4) optionally separating the 4,4’-methylenedianiline from the reaction product obtained in (3); wherein the feed F2 in (1) comprises 5 wt.-% or less of formaldehyde. It is preferred that the amount of 2,4’-methylenedianiline in the feed F2 in (1) ranges from 1 to 60 wt.-%, preferably 5 to 50 wt.-%, more preferably from 10 to 45 wt.-%, more preferably from 15 to 40 wt.-%, more preferably from 20 to 35 wt.-%. It is preferred that the feed F2 prepared in (1) and contacted with the catalyst C2 in (3) is in the liquid phase and/or in the gas phase, preferably in the liquid phase. In case that the feed F2 prepared in (1) is in the liquid phase, it is preferred that the liquid hourly space velocity at which the feed F2 obtained in (1) is contacted with the catalyst C2 in (3) is in the range of from 150 to 500 h-1. It is preferred that the concentration of 4,4’-methylenedianiline in the mixture M2 obtained by (3) is greater than the concentration of 4,4’-methylenedianiline which may optionally be comprised in the feed F2 prepared in (1). It is preferred that the molar ratio of 2,4’-methylenedianiline to 2,2’-methylenedianiline in the feed F2 in (1) is in the range of from 1:1 to 100:1, preferably from 15:1 to 50:1, more preferably from 18:1 to 30:1; more preferably from 20:1 to 28:1. It is preferred that the feed F2 in (1) comprises aniline, wherein the amount of aniline in the feed F2 in (1) ranges of from 45 to 90 wt.-%, preferably from 50 to 85 wt.-%, more preferably from 55 to 80 wt.-%, more preferably from 60 to 75 wt.-%. It is preferred that the feed F2 in (1) comprises 5 wt.-% or less formaldehyde, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more pref- erably 0.005 wt.-% or less, more preferably 0.001 wt.-% or less of formaldehyde, wherein more preferably the feed F2 in (1) is free of formaldehyde. Further, it is preferred the feed F2 in (1) comprises 5 wt.-% or less of formaldehyde and (C1-C10)alkyl aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.- % or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more prefera- bly 0.005 wt.-% or less, more preferably 0.001 wt-% or less of formaldehyde and (C1-C10)alkyl aldehydes, wherein more preferably the feed F2 in (1) is free of formaldehyde. Yet further, it is preferred that the feed F2 in (1) comprises 5 wt.-% or less of aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt-% or less of aldehydes, wherein more preferably the feed F2 in (1) is free of aldehydes. It is preferred that prior to contacting in (3), the feed F2 in (1) is heated to a temperature T1, wherein T1>TM, TM being the melting point of the feed F2, wherein T1 is preferably in the range of 50 to 220 °C, preferably of from 80 to 210°C, preferably of from 100 to 200°C, more prefera- bly from 150 to 190°C, more preferably from 160 to 180°C. It is preferred that the feed F2 in (1) is a feed stream and the reaction in (3) is conducted in a continuous mode. It is preferred that the feed F2 in (1) further comprises one or more of 4,4’-methylenedianiline, oligomers of 2,2’-methylenedianiline, oligomers of 2,4’-methylenedianiline, and oligomers of 4,4’-methylenedianiline, wherein more preferably the feed F2 in (1) further comprises one or more of oligomers of 2,2’-methylenedianiline, oligomers of 2,4’-methylenedianiline and/or oligo- mers of 4,4’-methylendianiline. It is preferred that the feed F2 in (1) is a product feed obtained from a process for the prepara- tion of one or more of 4,4’-methylenedianiline, 2,2’-methylenedianiline, 2,4’-methylenedianiline, and oligomers thereof. It is preferred that preparing the feed F2 in (1) comprises (1.1) providing a feed F1a comprising aniline and a feed F1b comprising formaldehyde; (1.2) contacting the feeds F1a and F1b provided in (1.1), obtaining a mixture M1b; (1.3) optionally separating water from the mixture M1b obtained in (1.2), obtaining a Mixture M1c; (1.4) providing a catalyst C1 comprising a Bronsted acid; and (1.5) contacting the mixture M1b obtained in (1.2) or the mixture M1c obtained in (1.3), prefera- bly the mixture M1c obtained in (1.3), with the catalyst C1 provided in (1.4), obtaining a mixture M1a comprising 2,4’-methylenedianiline. In case the feed F2 in (1) is prepared from a process comprising steps (1.1) to (1.5), it is pre- ferred that the mixture M1a further comprises one or more of 2,2’-methylenedianiline, 4,4’-meth- ylenedianiline, acridine, and oligomers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenedianiline, preferably one or more of 2,2’-methylenedianiline, 4,4’-meth- ylenedianiline, and oligomers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’- methylenedianiline, more preferably one or more of 2,2’-methylenedianiline and 4,4’-methylene- dianiline, wherein more preferably the mixture M1a further comprises 2,2’-methylenedianiline. Yet further, it is preferred that the process further comprises (1.6) separating 4,4’-methylenedianiline from mixture M1a, obtaining a mixture M1d. Yet further, it is preferred that the process further comprises (1.7) separating the catalyst C1 from the mixture M1a obtained in (1.5) or from the mixture M1d obtained in (1.6), preferably by filtration. Yet further, it is preferred that the process further comprises (1.8) recycling the catalyst C1 to (1.4). Yet further, it is preferred that after (1.5), or after (1.5) and prior to (1.6), or after (1.6), or after (1.6) and prior to (1.7), aniline is added to the mixture M1a obtained in (1.5) or to the mixture M1b obtained in (1.6). Independently thereof, the present invention relates to a process for the isomerization of 2,2’- methylenedianiline to 2,4’-methylenedianiline, the process comprising (1’) preparing a feed F3 comprising 2,2’- methylenedianiline and optionally further comprising aniline; (2’) providing a catalyst C3 comprising a Bronsted acid; (3’) contacting the feed F3 prepared in (1’) with the catalyst C3 provided in (2’), obtaining a mix- ture M3 comprising 2,4’-methylenedianiline as a reaction product; wherein the feed F3 in (1’) comprises 5 wt.-% or less of formaldehyde. In case the process comprises steps (1’) to (3’), it is preferred that the process further comprises (4’) providing a catalyst C2 comprising a Bronsted acid; (5’) contacting the mixture M3 prepared in (3’) with the catalyst C2 provided in (4’), obtaining a mixture M4 comprising 4,4’-methylenedianiline as a reaction product; (6’) optionally separating the 4,4’-methylenedianiline from the reaction product obtained in (5’). It is preferred that independently from each other the Bronsted acid in (2) or (2’) and/or (4’) is a zeolite. In case the Bronsted acid in (2) or (2’) and/or (4’) is a zeolite, it is preferred that the zeo- lite comprises YO2 and X2O3 in its framework structure, wherein Y stands for a tetravalent ele- ment and X stands for a trivalent element. In case the zeolite comprises YO2 and X2O3 in its framework structure, it is preferred that X is selected from the group consisting of Al, B, Ga, and combinations of two or more thereof, wherein X is preferably Al. Further, it is preferred that Y is selected from the group consisting of Si, Ti, Sn, Ge, and combinations of two or more thereof, wherein Y is preferably Si. Further, it is preferred that the zeolite comprises Si and Al in its framework structure, wherein the SiO2:Al2O3 molar ratio of the zeolite ranges from 1 to 45, pref- erably from 2 to 30, more preferably from 5 to 25, more preferably from 10 to 20, more prefera- bly from 12 to 18. Further, it is preferred that from 95 to 100 weight-% of the zeolite consists of the tetravalent element Y, the trivalent element X, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.-%, based on the total weight of the zeolite. Further, it is preferred that from 95 to 100 wt.-% of the zeolite consists of Si, Al, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.- %, based on the total weight of the zeolite. In case the process comprises steps (1) to (4) or (4’) to (6’), it is preferred that independently from each other the catalyst C2 in (2) or (4’) further comprises a binder. In case the process comprises steps (1’) to (3’), it is preferred that the catalyst C3 in (2’) further comprises a binder. In case the catalyst C2 in (2) or (4’) and/or the catalyst C3 in (2’) comprises a binder, it is pre- ferred that the binder comprises, preferably consists of, one or more selected from the group consisting of titania, zirconia, alumina, silica, silica-alumina, titania-silica, titania-alumina, zirco- nia-silica, zirconia-alumina, titania-zirconia, and mixtures of two or more thereof, preferably from the group consisting of silica-alumina, titania-silica, titania-alumina, zirconia-silica, zirconia-alu- mina, titania-zirconia, and mixtures of two or more thereof, wherein more preferably the binder comprises, more preferably consists of, silica-alumina. In case the process comprises steps (1) to (4) or (4’) to (6’), it is preferred that independently from each other the catalyst C2 in (2) or (4’) is provided as a shaped body, preferably as an ex- trudate. In case the process comprises steps (1’) to (3’), it is preferred that the catalyst C3 in (2’) is pro- vided as a shaped body, preferably as an extrudate. In case the process comprises steps (1) to (4) or (4’) to (6’),it is preferred that independently from each other from 95 to 100 wt.-% of the catalyst C2 provided in (2) or (4’) consists of the ze- olite and the optional binder, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, based on the total weight of the catalyst. In case the process comprises steps (1’) to (3’), it is preferred that from 95 to 100 wt.-% of the catalyst C3 provided in (2’) consists of the zeolite and the optional binder, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, based on the total weight of the catalyst. In case the process comprises steps (1) to (4) or (4’) to (6’),it is preferred that independently from each other from 95 to 100 wt.-% of the catalyst C2 in (2) or (4’) consists of Si, Al, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.-%, based on the total weight of the catalyst. In case the process comprises step (2’), it is preferred that from 95 to 100 wt.-% of the catalyst C3 in (2’) consists of Si, Al, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.-%, based on the total weight of the catalyst. Further, it is preferred that independently from each other the catalyst C2 in (2) or (4’) is a zeolite comprising 12-membered rings, wherein the number of members in a ring preferably refers to the number of T-atoms in the ring. Further, it is preferred that independently from each other the catalyst C2 in (2) or (4’) is a zeolite having an AFY, BEA, BEC, BOG, CON, FAU, GME, ISV, ITG, IWR, IWS, IWW, LTF, MEI, MOR, MSE, OFF, POS, SAO, SOR, SOV, UOV, UWY, or YFI type frame- work structure, preferably a BEA, MSE, or YFI structure type or mixtures thereof, more prefera- bly a YFI or MSE structure type, more preferably a MSE structure type. Further, it is preferred that independently from each other the catalyst C2 in (2) or (4’) is a zeolite having an MSE type framework structure, wherein the zeolite is MCM-68 or YNU-2, preferably MCM-68. Further, it is preferred that independently from each other the catalyst C2 in (2) or (4’) is a zeolite having a YFI type framework structure, wherein the zeolite is YNU-5. Further, it is preferred that inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite having a BEA type framework structure, wherein the zeolite is selected from the group consisting of zeolite beta, [B-Si-O]- BEA, [Ga-Si-O]-BEA, and [Ti-Si-O]-BEA, wherein preferably the preferably the zeolite is zeolite beta. Further, it is preferred that independently from each other the catalyst C2 in (2) or (4’) is a zeolite of which the maximum pore of the zeolite is in the range of from 5 to 12 Å, preferably from 5.5 to 10.5 Å, more preferably from 6 to 10 Å, more preferably from 6.5 to 8.5 Å. Within the meaning of the present application, the maximum diameter of a sphere which can be included in the framework structure of a zeolite refers to the value obtained by computational geometry by Delaunay triangulation with the following assumptions: - both the framework T- and O-atoms are hard spheres of diameter 2.7 angstrom - all extra-framework atoms (i.e. water, organics and cations) are ignored - the interrupted frameworks are not terminated by hydrogen atoms, i.e. only T and O atoms are considered as hard spheres - the calculations are based on the coordinates of ideal SiO2 frameworks in the highest possible symmetry. Preferably, the values are calculated as described in: "A geometric solution to the largest-free-sphere problem in zeolite frameworks", M.D. Foster, I. Rivin, M.M.J. Treacy and O. Delgado Friedrichs, Micropor. Mesopor. Mat., 90,32-38, 2006. In case the process comprises steps (1) to (4) or (4’) to (6’),it is preferred that independently from each other the catalyst C2 in (2) or (4’) is a zeolite of which the maximum diameter of a sphere which can be included in the framework structure of the zeolite is in the range of from 5 to 12 Å, preferably from 5.5 to 10.5 Å, more preferably from 6 to 10 Å, more preferably from 6.5 to 8.5 Å, more preferably from 7 to 8 Å. In case the process comprises steps (1’) to (3’), it is preferred that the catalyst C3 in (2’) is a ze- olite having a BEA, FAU, MSE or MWW type framework structure or mixtures thereof, preferably a BEA, MSE, or MWW structure type, more preferably a MWW structure type. Further, it is pre- ferred that the catalyst C3 in (2’) is a zeolite and the zeolite has an MWW type framework struc- ture, wherein the zeolite is PSH-3, SSZ-25, ERB-1, MCM-22, ITQ-1, [Ga-Si-O]-MWW or [Ti-Si- O]-MWW, preferably MCM-22. It is preferred that independently from each other the Bronsted acid in (2) or (2’) and/or (4’) is an inorganic acid, preferably selected from the group consisting of HCl, HNO3, H2SO4, CF3SO3H, and H3PO4, including mixtures of two or more thereof, wherein more preferably the Bronsted acid is HCl. In case the process comprises steps (1) to (4) or (4’) to (6’), it is preferred that independently from each other the catalyst C2 in (2) or (4’) is present in a slurry bed. In case the process comprises steps (1’) to (3’), it is preferred that the catalyst C3 in (2’) is pre- sent in a slurry bed. It is preferred that independently from each other in (3) or (3’) and/or (5’) the reaction occurs in a fixed bed reactor or in a fluidized bed reactor, preferably in a fixed bed reactor. It is preferred that independently from each other contacting in (3) or (3’) and/or (5’) is con- ducted at a temperature in the range of from 130 to 210°C, preferably of from 140 to 200°C, more preferably from 150 to 190°C, more preferably from 160 to 180°C. It is preferred that independently from each other contacting in (3) or (3’) and/or (5’) is con- ducted at a pressure in the range of from 0.9 to 1.3 bara. It is preferred that independently from each other contacting in (3) or (3’) and/or (5’) is con- ducted for a duration in the range of from 0.1 to 24 h, preferably from 1 to 22 h, preferably from 2 to 20 h, more preferably from 3 to 18 h, more preferably from 5 to 15 h. In case the process comprises steps (4’) to (6’), it is preferred that the mixture M3 obtained in (3’) and contacted with the catalyst C2 in (5’) is in the liquid phase and/or in the gas phase, pref- erably in the liquid phase. In case the mixture M3 obtained in (3’) and contacted with the cata- lyst C2 in (5’) is in the liquid phase, it is preferred that the liquid hourly space velocity at which the mixture M3 obtained in (3’) is contacted with the catalyst C2 in (5’) is in the range of from 150 to 500 h-1. It is preferred that independently from each other contacting in (3) or (3’) and/or (5’) is per- formed under a gas atmosphere, wherein the gas atmosphere in (3) or (3’) and/or (5’) preferably comprises one or more inert gases, preferably nitrogen and/or argon, more preferably nitrogen. In case the process comprises steps (1) to (4) or (4’) to (6’),it is preferred that independently from each other the process includes a step of regenerating the catalyst C2 after contacting with the feed in (3) or (5’), wherein the catalyst C2 is preferably regenerated by calcination at a tem- perature in the range of from 300 to 800 °C, preferably from 350 to 700 °C, more preferably from 400 to 600 °C, more preferably from 450 to 500 °C. In case the process comprises steps (1’) to (3’), it is preferred that the process includes a step of regenerating the catalyst C3 after contacting with the feed in (3’), wherein the catalyst C3 is preferably regenerated by calcination at a temperature in the range of from 300 to 800 °C, pref- erably from 350 to 700 °C, more preferably from 400 to 600 °C, more preferably from 450 to 500 °C. In case the process includes a step of regenerating the catalyst C2 or C3 after contacting with the feed in (3), (5’) or (3), it is preferred that the calcination is conducted for a period ranging from 1 to 24 h, preferably from 2 to 12 h, more preferably from 3 to 8 h. In case the process comprises steps (4’) to (6’), it is preferred that the concentration of 4,4’- methylenedianiline in the mixture M4 obtained by (5’) is greater than the concentration of 4,4’- methylenedianiline which may optionally be comprised in the feed F3 prepared in (1’). In case the process comprises steps (1’) to (3’), it is preferred that the feed F3 in (1’) comprises 2,2’-methylenedianiline and wherein the amount of 2,2’-methylenedianiline in the feed F3 ranges from 1 to 40 wt.-%, preferably 3 to 30 wt.-%, more preferably from 5 to 26 wt.-%, more preferably from 8 to 23 wt.-%, more preferably from 10 to 20 wt.-%. Further, it is preferred that the feed F3 in (1’) comprises aniline, wherein the amount of aniline in the feed F3 in (1’) ranges of from 45 to 90 wt.-%, preferably from 50 to 85 wt.-%, more preferably from 55 to 80 wt.-%, more preferably from 60 to 75 wt.-%. Further, it is preferred that the feed F3 in (1’) comprises 5 wt.-% or less formaldehyde, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt.-% or less of formaldehyde, wherein more preferably the feed F3 in (1’) is free of for- maldehyde. Yet further, it is preferred that the feed F3 in (1’) comprises 5 wt.-% or less of for- maldehyde and (C1-C10)alkyl aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt-% or less of formaldehyde and (C1-C10)alkyl aldehydes, wherein more preferably the feed F3 in (1’) is free of formaldehyde. Yet further, it is preferred that the feed F3 in (1’) comprises 5 wt.-% or less of aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.- % or less, more preferably 1 wt.-% or less, more preferably 0.1 wt-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt-% or less of aldehydes, wherein more preferably the feed F3 in (1’) is free of aldehydes. Further, it is preferred that prior to contacting in (3’), the feed F3 in (1’) is heated to a temperature T2, wherein T2>TM’, TM’ being the melting point of the feed F3, wherein T2 is preferably in the range of 50 to 220 °C, preferably of from 80 to 210°C, preferably of from 100 to 200°C, more preferably from 150 to 190°C, more preferably from 160 to 180°C. Further, it is preferred that the feed F3 in (1’) is a feed stream and the reaction in (3’) or in (3’) and/or (5’) is conducted in a continuous mode. It is preferred that the process is conducted as a continuous or as a batch process, preferably as a continuous process. In case the process comprises steps (1’) to (3’), it is preferred that preparing the feed F3 in (1’) comprises (1.1’) providing a feed F1a comprising aniline and a feed F1b comprising formaldehyde; (1.2’) contacting the feeds F1a and F1b provided in (1.1’), obtaining a mixture M1b’; (1.3’) optionally separating water from the mixture M1b’ obtained in (1.2’), obtaining a mixture M1c’; (1.4’) providing a catalyst C1 comprising a Bronsted acid; and (1.5’) contacting the mixture M1b’ obtained in (1.2’) or the mixture M1c’ obtained in (1.3’), pref- erably the mixture M1c’ obtained in (1.3’), with the catalyst C1 provided in (1.4’), obtaining a mixture M1a’ comprising 2,2’-methylenedianiline. In case the process comprises steps (1.1’) to (1.5’), it is preferred that the mixture M1a’ further comprises one or more of 2,4’-methylenedianiline, 4,4’-methylenedianiline, acridine, and oligo- mers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenedianiline, prefer- ably one or more of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and oligomers of 2,2’- methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenedianiline, more preferably one or more of 2,4’-methylenedianiline and 4,4’-methylenedianiline, wherein more preferably the mixture M1a’ further comprises 2,4’-methylenedianiline. Further, it is preferred that the process further comprises (1.6’) separating 4,4’-methylenedianiline from mixture M1a’, obtaining a mixture M1d’. Further, it is preferred that the Bronsted acid in (1.4) or (1.4’) is a solid acid, preferably a zeolite. In case the Bronsted acid in (1.4) or (1.4’) is a solid acid, it is preferred that the catalyst C1 is present in a fixed bed or in a slurry bed. Further, it is preferred that the catalyst C1 is provided as a shaped body, preferably as an extrudate. In case the process comprises steps (1.1) to (1.5) or (1.1’) to (1.5’), it is preferred that the cata- lyst C1 is dried prior to (1.1) or (1.1’) in a gas atmosphere, wherein the gas atmosphere has a temperature in the range of from 100 to 300 °C, preferably in the range of from 150 to 250 °C, more preferably in the range of from 190 to 210 °C. Further, it is preferred that the gas atmos- phere comprises one or more of nitrogen, oxygen and a mixture thereof, wherein the gas at- mosphere is preferably oxygen, air or lean air. Further, it is preferred that the drying is per- formed for a duration in the range of from 10 to 40 h, preferably in the range of from 20 to 30 h, more preferably in the range of from 23 to 25 h. In case the process comprises steps (1.1) to (1.5) or (1.1’) to (1.5’), it is preferred that the Bronsted acid in (1.4) or (1.4’) is an inorganic acid, preferably HCl. Further, it is preferred that the catalyst C1 is a heterogeneous or a homogeneous catalyst. Further, it is preferred that the feeds F1a and F1b in (1.1) or (1.1’) are a feed stream and the reaction in (1.5) or (1.5’) is con- ducted in a continuous mode. Further, it is preferred that the reaction conditions in (1.5) or (1.5’) comprise heating at a temperature in the range of from 100 to 200 °C, preferably in the range of from 130 to 170 °C, more preferably in the range of from 145 to 155 °C. Further, it is preferred that the reaction conditions in (1.5) or (1.5’) comprise a pressure of equal to or smaller than 100 bar, preferably of equal to or smaller than 90, more preferably of equal to or smaller than 70, more preferably of equal to or smaller than 50, more preferably of equal to or smaller than 30, and more preferably of equal to or smaller than 10 bars. Further, it is preferred that (1.5) or (1.5’) is performed under a gas atmosphere, wherein the gas atmosphere in (1.5) or (1.5’) pref- erably comprises one or more inert gases, preferably nitrogen and/or argon, more preferably ni- trogen. In case the process comprises steps (1.1’) to (1.5’), it is preferred that the process further com- prises (1.7’) separating the catalyst C1 from the mixture M1a’ obtained in (1.5’) or from the mixture M1d’ obtained in (1.6’), preferably by filtration. Further, it is preferred that the process further comprises (1.8’) recycling the catalyst C1 to (1.4’). In case the process comprises steps (1.1) to (1.5) or (1.1’) to (1.5’), it is preferred that after (1.7) and prior to (1.8), or after (1.7’) and prior to (1.8’), the catalyst C1 is not subject to a step of washing or drying, wherein preferably the catalyst C1 is not subject to any treatment after (1.7) and prior to (1.8), or after (1.7’) and prior to (1.8’). Further, it is preferred that separating in (1.6) or (1.6’) is conducted by distillation, preferably by fractional distillation. Further, it is preferred that after (1.5’), or after (1.5’) and prior to (1.6’), or after (1.6’), or after (1.6’) and prior to (1.7’), aniline is added to the mixture M1a’ obtained in (1.5’) or to the mixture M1b’ obtained in (1.6’). In case the process comprises steps (1) to (4) or (4’) to (6’), it is preferred that separating in (4) or (6’) is conducted by distillation, preferably by fractional distillation. The present invention is further illustrated by the following set of embodiments and combi- nations 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 process accordingly to any one of embod- iments 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 process according to any one of embodiments 1, 2, 3 and 4”. Further, it is explicitly noted that the following set of embodiments is not the set of claims determin- ing the extent of protection, but represent a suitably structured part of the description di- rected to general and preferred aspects of the present invention. 1. A process for the isomerization of 2,4’- methylenedianiline and/or, preferably and, 2,2’- methylenedianiline to 4,4’-methylenedianiline, respectively, the process comprising (1) preparing a feed F2 comprising 2,4’-methylenedianiline and/or, preferably and, 2,2’- methylenedianiline and optionally further comprising aniline; (2) providing a catalyst C2 comprising a Bronsted acid; (3) contacting the feed F2 prepared in (1) with the catalyst C2 provided in (2), obtain- ing a mixture M2 comprising 4,4’-methylenedianiline as a reaction product; (4) optionally separating the 4,4’-methylenedianiline from the reaction product ob- tained in (3); wherein the feed F2 in (1) comprises 5 wt.-% or less of formaldehyde. 2. The process according to embodiment 1, wherein the amount of 2,4’-methylenedianiline in the feed F2 in (1) ranges from 1 to 60 wt.-%, preferably 5 to 50 wt.-%, more prefera- bly from 10 to 45 wt.-%, more preferably from 15 to 40 wt.-%, more preferably from 20 to 35 wt.-%. 3. The process according to embodiment 1 or 2, wherein the feed F2 prepared in (1) and contacted with the catalyst C2 in (3) is in the liquid phase and/or in the gas phase, pref- erably in the liquid phase. 4. The process according to embodiment 3, wherein the liquid hourly space velocity at which the feed F2 obtained in (1) is contacted with the catalyst C2 in (3) is in the range of from 150 to 500 h-1. 5. The process according to any one of embodiments 1 to 4, wherein the concentration of 4,4’-methylenedianiline in the mixture M2 obtained by (3) is greater than the concentra- tion of 4,4’-methylenedianiline which may optionally be comprised in the feed F2 pre- pared in (1). 6. The process according to any one of embodiments 1 to 5, wherein the molar ratio of 2,4’-methylenedianiline to 2,2’-methylenedianiline in the feed F2 in (1) is in the range of from 1:1 to 100:1, preferably from 15:1 to 50:1, more preferably from 18:1 to 30:1; more preferably from 20:1 to 28:1. 7. The process according to any one of embodiments 1 to 6, wherein the feed F2 in (1) comprises aniline, wherein the amount of aniline in the feed F2 in (1) ranges of from 45 to 90 wt.-%, preferably from 50 to 85 wt.-%, more preferably from 55 to 80 wt.-%, more preferably from 60 to 75 wt.-%. 8. The process according to any one of embodiments 1 to 7, wherein the feed F2 in (1) comprises 5 wt.-% or less formaldehyde, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt.-% or less of formaldehyde, wherein more preferably the feed F2 in (1) is free of formaldehyde. 9. The process of embodiment 8, wherein the feed F2 in (1) comprises 5 wt.-% or less of formaldehyde and (C1-C10)alkyl aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt-% or less of formaldehyde and (C1- C10)alkyl aldehydes, wherein more preferably the feed F2 in (1) is free of formalde- hyde. 10. The process of embodiment 9, wherein the feed F2 in (1) comprises 5 wt.-% or less of aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more prefera- bly 0.001 wt-% or less of aldehydes, wherein more preferably the feed F2 in (1) is free of aldehydes. 11. The process according to any one of embodiments 1 to 10, wherein prior to contacting in (3), the feed F2 in (1) is heated to a temperature T1, wherein T1>TM, TM being the melting point of the feed F2, wherein T1 is preferably in the range of 50 to 220 °C, pref- erably of from 80 to 210°C, preferably of from 100 to 200°C, more preferably from 150 to 190°C, more preferably from 160 to 180°C. 12. The process according to any one of embodiments 1 to 11, wherein the feed F2 in (1) is a feed stream and the reaction in (3) is conducted in a continuous mode. 13. The process according to any one of embodiments 1 to 12, wherein the feed F2 in (1) further comprises one or more of 4,4’-methylenedianiline, oligomers of 2,2’-methylene- dianiline, oligomers of 2,4’-methylenedianiline, and oligomers of 4,4’-methylenediani- line, wherein more preferably the feed F2 in (1) further comprises one or more of oligo- mers of 2,2’-methylenedianiline, oligomers of 2,4’-methylenedianiline and/or oligomers of 4,4’-methylendianiline. 14. The process according to any one of embodiments 1 to 13, wherein the feed F2 in (1) is a product feed obtained from a process for the preparation of one or more of 4,4’- methylenedianiline, 2,2’-methylenedianiline, 2,4’-methylenedianiline, and oligomers thereof. 15. The process according to any one of embodiments 1 to 14, wherein preparing the feed F2 in (1) comprises (1.1) providing a feed F1a comprising aniline and a feed F1b comprising formalde- hyde; (1.2) contacting the feeds F1a and F1b provided in (1.1), obtaining a mixture M1b; (1.3) optionally separating water from the mixture M1b obtained in (1.2), obtaining a Mixture M1c; (1.4) providing a catalyst C1 comprising a Bronsted acid; and (1.5) contacting the mixture M1b obtained in (1.2) or the mixture M1c obtained in (1.3), preferably the mixture M1c obtained in (1.3), with the catalyst C1 provided in (1.4), obtaining a mixture M1a comprising 2,4’-methylenedianiline. 16. The process according to embodiment 15, wherein the mixture M1a further comprises one or more of 2,2’-methylenedianiline, 4,4’-methylenedianiline, acridine, and oligo- mers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenediani- line, preferably one or more of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and oli- gomers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenediani- line, more preferably one or more of 2,2’-methylenedianiline and 4,4’-methylenediani- line, wherein more preferably the mixture M1a further comprises 2,2’-methylenediani- line. 17. The process according to any one of embodiments 15 or 16, further comprising (1.6) separating 4,4’-methylenedianiline from mixture M1a, obtaining a mixture M1d. 18. The process according to any one of embodiments 15 to 17, further comprising (1.7) separating the catalyst C1 from the mixture M1a obtained in (1.5) or from the mixture M1d obtained in (1.6), preferably by filtration. 19. The process according to any one of embodiments 15 to 18, further comprising (1.8) recycling the catalyst C1 to (1.4). 20. The process according to any one of embodiments 15 to 19, wherein after (1.5), or af- ter (1.5) and prior to (1.6), or after (1.6), or after (1.6) and prior to (1.7), aniline is added to the mixture M1a obtained in (1.5) or to the mixture M1b obtained in (1.6). 21. A process for the isomerization of 2,2’- methylenedianiline to 2,4’-methylenedianiline, the process comprising (1’) preparing a feed F3 comprising 2,2’- methylenedianiline and optionally further comprising aniline; (2’) providing a catalyst C3 comprising a Bronsted acid; (3’) contacting the feed F3 prepared in (1’) with the catalyst C3 provided in (2’), obtain- ing a mixture M3 comprising 2,4’-methylenedianiline as a reaction product; wherein the feed F3 in (1’) comprises 5 wt.-% or less of formaldehyde. 22. The process of embodiment 21, the process further comprising (4’) providing a catalyst C2 comprising a Bronsted acid; (5’) contacting the mixture M3 prepared in (3’) with the catalyst C2 provided in (4’), ob- taining a mixture M4 comprising 4,4’-methylenedianiline as a reaction product; (6’) optionally separating the 4,4’-methylenedianiline from the reaction product ob- tained in (5’). 23. The process according to any one of embodiments 1 to 22, wherein independently from each other the Bronsted acid in (2) or (2’) and/or (4’) is a zeolite. 24. The process according to embodiment 23, wherein the zeolite comprises YO2 and X2O3 in its framework structure, wherein Y stands for a tetravalent element and X stands for a trivalent element. 25. The process according to embodiment 24, wherein X is selected from the group consist- ing of Al, B, Ga, and combinations of two or more thereof, wherein X is preferably Al. 26. The process according to embodiment 24 or 25, wherein Y is selected from the group consisting of Si, Ti, Sn, Ge, and combinations of two or more thereof, wherein Y is pref- erably Si. 27. The process according to any one of embodiments 23 to 26, wherein the zeolite com- prises Si and Al in its framework structure, wherein the SiO2:Al2O3 molar ratio of the ze- olite ranges from 1 to 45, preferably from 2 to 30, more preferably from 5 to 25, more preferably from 10 to 20, more preferably from 12 to 18. 28. The process according to any one of embodiments 26 or 27, wherein from 95 to 100 weight-% of the zeolite consists of the tetravalent element Y, the trivalent element X, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more prefera- bly from 99.9 to 100 wt.-%, based on the total weight of the zeolite. 29. The process according to any one of embodiments 23 to 28, wherein from 95 to 100 wt.-% of the zeolite consists of Si, Al, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.-%, based on the total weight of the zeolite. 30. The process according to any one of embodiments 1 to 20 and 22 to 29, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) further comprises a binder. 31. The process according to any one of embodiments 21 to 30, wherein the catalyst C3 in (2’) further comprises a binder. 32. The process according to embodiment 30 or 31, wherein the binder comprises, prefera- bly consists of, one or more selected from the group consisting of titania, zirconia, alu- mina, silica, silica-alumina, titania-silica, titania-alumina, zirconia-silica, zirconia-alu- mina, titania-zirconia, and mixtures of two or more thereof, preferably from the group consisting of silica-alumina, titania-silica, titania-alumina, zirconia-silica, zirconia-alu- mina, titania-zirconia, and mixtures of two or more thereof, wherein more preferably the binder comprises, more preferably consists of, silica-alumina. 33. The process according to any one of embodiments 1 to 20 and 22 to 32, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is provided as a shaped body, preferably as an extrudate. 34. The process according to any one of embodiments 21 to 33, wherein the catalyst C3 in (2’) is provided as a shaped body, preferably as an extrudate. 35. The process according to any one of embodiments 1 to 20 and 23 to 34, wherein inde- pendently from each other from 95 to 100 wt.-% of the catalyst C2 provided in (2) or (4’) consists of the zeolite and the optional binder, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, based on the total weight of the catalyst. 36. The process according to any one of embodiments 23 to 35, wherein from 95 to 100 wt.-% of the catalyst C3 provided in (2’) consists of the zeolite and the optional binder, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, based on the total weight of the catalyst. 37. The process according to any one of embodiments 1 to 20 and 22 to 36, wherein inde- pendently from each other from 95 to 100 wt.-% of the catalyst C2 in (2) or (4’) consists of Si, Al, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.- %, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.-%, based on the total weight of the catalyst. 38. The process according to any one of embodiments 21 to 37, wherein from 95 to 100 wt.-% of the catalyst C3 in (2’) consists of Si, Al, O, and H, preferably from 97 to 100 wt.-%, more preferably from 98 to 100 wt.-%, more preferably from 99 to 100 wt.-%, more preferably from 99.5 to 100 wt.-%, more preferably from 99.9 to 100 wt.-%, based on the total weight of the catalyst. 39. The process according to any one of embodiments 1 to 20 and 23 to 38, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite comprising 12-mem- bered rings, wherein the number of members in a ring preferably refers to the number of T-atoms in the ring. 40. The process according to any one of embodiments 1 to 20 and 23 to 39, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite having an AFY, BEA, BEC, BOG, CON, FAU, GME, ISV, ITG, IWR, IWS, IWW, LTF, MEI, MOR, MSE, OFF, POS, SAO, SOR, SOV, UOV, UWY, or YFI type framework structure, preferably a BEA, MSE, or YFI structure type or mixtures thereof, more preferably a YFI or MSE structure type, more preferably a MSE structure type. The process according to any one of embodiments 1 to 20 and 23 to 40, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite having an MSE type framework structure, wherein the zeolite is MCM-68 or YNU-2, preferably MCM-68. The process according to any one of embodiments 1 to 20 and 23 to 41, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite having a YFI type framework structure, wherein the zeolite is YNU-5. The process according to any one of embodiments 23 to 20 and 23 to 42, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite having a BEA type framework structure, wherein the zeolite is selected from the group consisting of zeolite beta, [B-Si-O]-BEA, [Ga-Si-O]-BEA, and [Ti-Si-O]-BEA, wherein preferably the prefera- bly the zeolite is zeolite beta. The process according to any one of embodiments 23 to 20 and 23 to 43, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite of which the maxi- mum pore of the zeolite is in the range of from 5 to 12 Å, preferably from 5.5 to 10.5 Å, more preferably from 6 to 10 Å, more preferably from 6.5 to 8.5 Å. The process according to any one of embodiments 1 to 20 and 23 to 44, wherein inde- pendently from each other the catalyst C2 in (2) or (4’) is a zeolite of which the maxi- mum diameter of a sphere which can be included in the framework structure of the zeo- lite is in the range of from 5 to 12 Å, preferably from 5.5 to 10.5 Å, more preferably from 6 to 10 Å, more preferably from 6.5 to 8.5 Å, more preferably from 7 to 8 Å. The process according to any one of embodiments 23 to 45, wherein the catalyst C3 in (2’) is a zeolite having a BEA, FAU, MSE or MWW type framework structure or mixtures thereof, preferably a BEA, MSE, or MWW structure type, more preferably a MWW struc- ture type. The process according to any one of embodiments 23 to 46, wherein the catalyst C3 in (2’) is a zeolite and the zeolite has an MWW type framework structure, wherein the zeo- lite is PSH-3, SSZ-25, ERB-1, MCM-22, ITQ-1, [Ga-Si-O]-MWW or [Ti-Si-O]-MWW, preferably MCM-22. The process according to any one of embodiments 1 to 47, wherein independently from each other the Bronsted acid in (2) or (2’) and/or (4’) is an inorganic acid, preferably se- lected from the group consisting of HCl, HNO3, H2SO4, CF3SO3H, and H3PO4, including mixtures of two or more thereof, wherein more preferably the Bronsted acid is HCl. The process according to embodiment 48, wherein independently from each other the catalyst C2 in (2) or (4’) is present in a slurry bed. 50. The process according to embodiment 48 or 49, wherein the catalyst C3 in (2’) is pre- sent in a slurry bed. 51. The process according to any one of embodiments 1 to 50, wherein independently from each other in (3) or (3’) and/or (5’) the reaction occurs in a fixed bed reactor or in a fluid- ized bed reactor, preferably in a fixed bed reactor. 52. The process according to any one of embodiments 1 to 51, wherein independently from each other contacting in (3) or (3’) and/or (5’) is conducted at a temperature in the range of from 130 to 210°C, preferably of from 140 to 200°C, more preferably from 150 to 190°C, more preferably from 160 to 180°C. 53. The process according to any one of embodiments 1 to 52, wherein independently from each other contacting in (3) or (3’) and/or (5’) is conducted at a pressure in the range of from 0.9 to 1.3 bara. 54. The process according to any one of embodiments 1 to 53, wherein independently from each other contacting in (3) or (3’) and/or (5’) is conducted for a duration in the range of from 0.1 to 24 h, preferably from 1 to 22 h, preferably from 2 to 20 h, more preferably from 3 to 18 h, more preferably from 5 to 15 h. 55. The process according to any one of embodiments 22 to 54, wherein the mixture M3 obtained in (3’) and contacted with the catalyst C2 in (5’) is in the liquid phase and/or in the gas phase, preferably in the liquid phase. 56. The process according to embodiment 55, wherein the liquid hourly space velocity at which the mixture M3 obtained in (3’) is contacted with the catalyst C2 in (5’) is in the range of from 150 to 500 h-1. 57. The process according to any one of embodiments 1 to 56, wherein independently from each other contacting in (3) or (3’) and/or (5’) is performed under a gas atmosphere, wherein the gas atmosphere in (3) or (3’) and/or (5’) preferably comprises one or more inert gases, preferably nitrogen and/or argon, more preferably nitrogen. 58. The process according to any one of embodiments 1 to 20 and 22 to 57, wherein inde- pendently from each other the process includes a step of regenerating the catalyst C2 after contacting with the feed in (3) or (5’), wherein the catalyst C2 is preferably regen- erated by calcination at a temperature in the range of from 300 to 800 °C, preferably from 350 to 700 °C, more preferably from 400 to 600 °C, more preferably from 450 to 500 °C. 59. The process according to any one of embodiments 21 to 58, wherein the process in- cludes a step of regenerating the catalyst C3 after contacting with the feed in (3’), wherein the catalyst C3 is preferably regenerated by calcination at a temperature in the range of from 300 to 800 °C, preferably from 350 to 700 °C, more preferably from 400 to 600 °C, more preferably from 450 to 500 °C. 60. The process according to embodiment 58 or 59, wherein the calcination is conducted for a period ranging from 1 to 24 h, preferably from 2 to 12 h, more preferably from 3 to 8 h. 61. The process according to any one of embodiments 22 to 60, wherein the concentration of 4,4’-methylenedianiline in the mixture M4 obtained by (5’) is greater than the concen- tration of 4,4’-methylenedianiline which may optionally be comprised in the feed F3 pre- pared in (1’). 62. The process according to any one of embodiments 21 to 61, wherein the feed F3 in (1’) comprises 2,2’-methylenedianiline and wherein the amount of 2,2’-methylenedianiline in the feed F3 ranges from 1 to 40 wt.-%, preferably 3 to 30 wt.-%, more preferably from 5 to 26 wt.-%, more preferably from 8 to 23 wt.-%, more preferably from 10 to 20 wt.-%. 63. The process according to any one of embodiments 21 to 62, wherein the feed F3 in (1’) comprises aniline, wherein the amount of aniline in the feed F3 in (1’) ranges of from 45 to 90 wt.-%, preferably from 50 to 85 wt.-%, more preferably from 55 to 80 wt.-%, more preferably from 60 to 75 wt.-%. 64. The process according to any one of embodiments 21 to 63, wherein the feed F3 in (1’) comprises 5 wt.-% or less formaldehyde, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt.-% or less of formaldehyde, wherein more pref- erably the feed F3 in (1’) is free of formaldehyde. 65. The process of embodiment 64, wherein the feed F3 in (1’) comprises 5 wt.-% or less of formaldehyde and (C1-C10)alkyl aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt.-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more preferably 0.001 wt-% or less of formaldehyde and (C1- C10)alkyl aldehydes, wherein more preferably the feed F3 in (1’) is free of formalde- hyde. 66. The process of embodiment 65, wherein the feed F3 in (1’) comprises 5 wt.-% or less of aldehydes, preferably 3 wt.-% or less, more preferably 2 wt.-% or less, more preferably 1 wt.-% or less, more preferably 0.1 wt-% or less, more preferably 0.05 wt.-% or less, more preferably 0.01 wt.-% or less, more preferably 0.005 wt.-% or less, more prefera- bly 0.001 wt-% or less of aldehydes, wherein more preferably the feed F3 in (1’) is free of aldehydes. 67. The process according to any one of embodiments 21 to 66, wherein prior to contacting in (3’), the feed F3 in (1’) is heated to a temperature T2, wherein T2>TM’, TM’ being the melting point of the feed F3, wherein T2 is preferably in the range of 50 to 220 °C, pref- erably of from 80 to 210°C, preferably of from 100 to 200°C, more preferably from 150 to 190°C, more preferably from 160 to 180°C. 68. The process according to any one of embodiments 21 to 67, wherein the feed F3 in (1’) is a feed stream and the reaction in (3’) or in (3’) and/or (5’) is conducted in a continu- ous mode. 69. The process according to any one of embodiments 1 to 68, wherein the process is con- ducted as a continuous or as a batch process, preferably as a continuous process. 70. The process according to any one of embodiments 21 to 69, wherein preparing the feed F3 in (1’) comprises (1.1’) providing a feed F1a comprising aniline and a feed F1b comprising formalde- hyde; (1.2’) contacting the feeds F1a and F1b provided in (1.1’), obtaining a mixture M1b’; (1.3’) optionally separating water from the mixture M1b’ obtained in (1.2’), obtaining a mixture M1c’; (1.4’) providing a catalyst C1 comprising a Bronsted acid; and (1.5’) contacting the mixture M1b’ obtained in (1.2’) or the mixture M1c’ obtained in (1.3’), preferably the mixture M1c’ obtained in (1.3’), with the catalyst C1 provided in (1.4’), obtaining a mixture M1a’ comprising 2,2’-methylenedianiline. 71. The process according to embodiment 70, wherein the mixture M1a’ further comprises one or more of 2,4’-methylenedianiline, 4,4’-methylenedianiline, acridine, and oligomers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenedianiline, pref- erably one or more of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and oligomers of 2,2’-methylenedianiline, 4,4’-methylenedianiline, and/or 2,4’-methylenedianiline, more preferably one or more of 2,4’-methylenedianiline and 4,4’-methylenedianiline, wherein more preferably the mixture M1a’ further comprises 2,4’-methylenedianiline. 72. The process according to any one of embodiments 70 or 71, further comprising (1.6’) separating 4,4’-methylenedianiline from mixture M1a’, obtaining a mixture M1d’. 73. The process according to any one of embodiments 70 to 72, wherein the Bronsted acid in (1.4) or (1.4’) is a solid acid, preferably a zeolite. 74. The process according to any one of embodiments 15 to 20 and 70 to 73, wherein the catalyst C1 is present in a fixed bed or in a slurry bed. 75. The process according to any one of embodiments 15 to 20 and 70 to 74, wherein the catalyst C1 is provided as a shaped body, preferably as an extrudate. 76. The process according to any one of embodiments 15 to 20 and 70 to 75, wherein the catalyst C1 is dried prior to (1.1) or (1.1’) in a gas atmosphere, wherein the gas atmos- phere has a temperature in the range of from 100 to 300 °C, preferably in the range of from 150 to 250 °C, more preferably in the range of from 190 to 210 °C. 77. The process according to embodiment 76, wherein the gas atmosphere comprises one or more of nitrogen, oxygen and a mixture thereof, wherein the gas atmosphere is pref- erably oxygen, air or lean air. 78. The process according to any one of embodiments 76 or 77, wherein the drying is per- formed for a duration in the range of from 10 to 40 h, preferably in the range of from 20 to 30 h, more preferably in the range of from 23 to 25 h. 79. The process according to any one of embodiments 15 to 20 and 70 to 78, wherein the Bronsted acid in (1.4) or (1.4’) is an inorganic acid, preferably HCl. 80. The process according to any one of embodiments 15 to 20 and 70 to 79, wherein the catalyst C1 is a heterogeneous or a homogeneous catalyst. 81. The process according to any one of embodiments 15 to 20 and 70 to 80, wherein the feeds F1a and F1b in (1.1) or (1.1’) are a feed stream and the reaction in (1.5) or (1.5’) is conducted in a continuous mode. 82. The process according to any one of embodiments 15 to 20 and 70 to 81, wherein the reaction conditions in (1.5) or (1.5’) comprise heating at a temperature in the range of from 100 to 200 °C, preferably in the range of from 130 to 170 °C, more preferably in the range of from 145 to 155 °C. 83. The process according to any one of embodiments 15 to 20 and 70 to 82, wherein the reaction conditions in (1.5) or (1.5’) comprise a pressure of equal to or smaller than 100 bar, preferably of equal to or smaller than 90, more preferably of equal to or smaller than 70, more preferably of equal to or smaller than 50, more preferably of equal to or smaller than 30, and more preferably of equal to or smaller than 10 bars. 84. The process according to any one of embodiments 15 to 20 and 70 to 83, wherein (1.5) or (1.5’) is performed under a gas atmosphere, wherein the gas atmosphere in (1.5) or (1.5’) preferably comprises one or more inert gases, preferably nitrogen and/or argon, more preferably nitrogen. The process according to any one of embodiments 70 to 84, further comprising (1.7’) separating the catalyst C1 from the mixture M1a’ obtained in (1.5’) or from the mixture M1d’ obtained in (1.6’), preferably by filtration. The process according to any one of embodiments 70 to 85, further comprising (1.8’) recycling the catalyst C1 to (1.4’). The process according to embodiment 15 to 20 and 70 to 86, wherein after (1.7) and prior to (1.8), or after (1.7’) and prior to (1.8’), the catalyst C1 is not subject to a step of washing or drying, wherein preferably the catalyst C1 is not subject to any treatment af- ter (1.7) and prior to (1.8), or after (1.7’) and prior to (1.8’). The process according to any of embodiments 15 to 20 and 70 to 87, wherein separat- ing in (1.6) or (1.6’) is conducted by distillation, preferably by fractional distillation. The process according to any one of embodiments 15 to 20 and 70 to 88, wherein after (1.5’), or after (1.5’) and prior to (1.6’), or after (1.6’), or after (1.6’) and prior to (1.7’), aniline is added to the mixture M1a’ obtained in (1.5’) or to the mixture M1b’ obtained in (1.6’). The process according to any one of embodiments 1 to 20 and 22 to 89, wherein sepa- rating in (4) or (6’) is conducted by distillation, preferably by fractional distillation.
EXAMPLES Reference Example 1: Determination of Si/Al content The determination of the Si/Al ratio of the synthesized materials was done using inductively cou- pled plasma-optical emission spectroscopy (ICP-OES). This was done using a Varian 720-ES with a double-pass glass cyclonic spray chamber with a SeaSpray concentric glass nebulizer and a high solids torch. For sample digestion, 100 mg of sample and 500 mg LiBO2 were homogenized and added to a graphite crucible.This crucible was then heated in an oven to 1000°C for 15 min. Afterwards, the crucible was emptied in a Teflon beaker containing 50 mL HNO3 (0.42 N). Finally, the graphite precipitant was removed and the sample was diluted accordingly. Quantification of the Si and Al content was done by using a calibration curve for both elements. Reference Example 2: Kinetic model for MDA isomerization To determine apparent rate constants associated with the isomerization of methylenedianilines, a kinetic model was constructed. Herein following assumptions were made. First of all, the isom- erization reaction was considered to be a first order reaction in the corresponding MDA concen- tration. The oligomerization reaction was described as a second order reaction in the total con- centration of MDA ([2,2’]+[2,4’]+[4,4’]). Furthermore, the oligomerization reaction was assumed to be irreversible. As was shown in mechanistic studies, the isomerization can follow either a mono- or bimolecular pathway. Since aniline affected these rate constants significantly, an extra term was added to the rate constants to take into account the role of aniline. Example 1: Effect of aniline addition on the catalytic process First, dry beta zeolite (100 mg), 2,4’-methylenedianiline (500 mg) and x mL aniline, wherein x ranges of from 0 to 1.2 mL, were added to a GC vial. The GC vial was flushed with Ar and the vial was heated to 170°C. After reaction, THF was added to dilute/dissolve the reaction mixture. The obtained products were identified by GC-MS. For quantification, tetradecane was added as an external standard and analysis was done using GC. Rate constants were calculated accord- ing to Reference Example 2. Table 1: Effect of aniline addition on MDA isomerization kinetics. Aniline Aniline kiso,1 (4,4’) kiso,-1 kiso,2 (2,2’) koligo (mL) (M) (10-6 s-1)c (10-6 s-1)c (10-6 s-1)c (10-6 s-1)c Example 2 1.2 7.7 5.3 0.5 0.3 0.2 Example 3 0.8 6.7 6 20 0.7 0.1 Example 4 0.6 5.9 8.4 19 0.5 0.3 Example 5 0.4 4.8 9.6 40 0.9 0.3 Example 6 0.2 3.1 28 100 1.2 1.6 Example 7 0 0 3.8 8.0 1.5 2.4 c The kinetic values represent respectively the following: kiso,1 (2,4’→ 4,4’), kiso,-1 (4,4’→ 2,4’), kiso,2 (2,4’→ 2,2’) and koligo (MDA→ oligomer) The effect of aniline addition on the kinetic parameters was evaluated first (see figure 2). Aniline affects both kiso,2 and koligo especially the formation of 2,2’-MDA and oligomers in a negative fashion over the entire concentration range. In contrast, the formation of 4,4’-MDA (kiso,1) is ini- tially strongly enhanced upon addition of aniline; only from high aniline concentrations onwards, the rate constant diminishes. Example 8: Catalytic testing First, a catalyst (100 mg, see table 2), 2,4’-MDA (500 mg) and 1.2 mL aniline were added to a GC vial. The GC vial was flushed with Ar and the vial was heated to 170°C. After the reaction, THF was added to dilute the reaction mixture. The obtained products were identified by GC-MS. For quantification, tetradecane was added as an external standard and analysis was done using GC. Rate constants were calculated according to Reference Example 2. Table 2: Results from catalytic testing with 2,4’-MDA as starting material. Catalyst Topology Si/Al kiso,1 (4,4’) kiso,2 (2,2’) koligo (10-6 s-1)c (10-6 s-1)c (10-7 s-1)c Example 9 HCla - 1.9 0.2 11.4 Example 10 CF3SO3Hb - 2.7 1.0 4.2 Example 11 ZSM-5 MFI 15 0.4 0.2 0.4 Example 12 mordenite MOR 10 0.6 0.3 0.4 Example 13 zeolite beta BEA 12.5 5.3 0.25 2.3 Example 14 nanobeta BEA 23 3.3 2.5 0.02 Example 15 faujasite FAU 40 1.9 0.3 0.1 Example 16 MCM-68 MSE 10.8 4.7 0.2 0.2 Example 17 UZM-35 MSE 7.8 1.0 0.3 0.5 Example 18 YNU-5 YFI 9.8 4.8 0.6 0.2 Example 19 MCM-22 MWW 14 0.5 19.9 2.0 a In case of HCl as catalyst: 50µL of a 37 wt.-% solution of HCl was used. b In case of CF3SO3H as catalyst: 50 µL CF3SO3H was used. c The kinetic values represent respectively the following: kiso,1 (2,4’→ 4,4’), kiso,2 (2,4’→ 2,2’), and koligo (MDA→ oligomer). Isomerization of 2,4’-MDA to 4,4’-MDA Compared to the reference case (i.e. with CF3SO3H as catalyst, see fig.4), all zeolites sup- pressed oligomerization, indicating that the confined environment surrounding the acid site in- hibits formation of bulky products (see fig.3). Zeolites with MFI (ZSM-5, see fig.5) or MOR (Mordenite) topologies were found to be inactive, likely due to pore blocking. Also FAU yielded moderate isomerization rates, although possessing the most spacious pores. Beta gave the highest isomerization rates towards the preferred 4,4’-MDA (see fig.7). On the other hand, MCM-68 and YNU-5 (see fig.8 and 9 respectively) also yielded promising results, especially in the suppression of 2,2’-MDA (kiso,2) and oligomers (koligo). For the MSE to- pology, the synthesis route affected its activity as MCM-68 was found to be more active than UZM-35. Finally, MCM-22 yielded peculiar results, giving a strong, though undesired selectivity towards 2,2’-MDA. The zeolite catalysts were also found to be easily recyclable via calcination. Isomerization of 2,2’-MDA to 2,4’-MDA First, a catalyst (50 mg, see table 2), 2,2’-MDA (250 mg) and 0.3 mL aniline were added to a GC vial. The GC vial was flushed with Ar and the vial was heated to temperature T, wherein T is 170, 200 or 220 °C (see table 3). After the reaction, THF was added to dilute the reaction mix- ture. The obtained products were identified by GC-MS. For quantification, tetradecane was added as an external standard and analysis was done using GC. Rate constants were calcu- lated according to Reference Example 2. Table 3: Results from catalytic testing with 2,2’-MDA as starting material Experiment Catalyst T kiso,-2 (°C) (10-5 s-1) (10-5 s-1) Example 20 zeolite beta 200 1.1 0.8 1.375 Example 21 zeolite beta 220 2.5 2.4 1.04 Example 22 MCM-68 220 5.0 1.9 2.63 Example 23 MCM-22 200 1.6 0.23 6.15 Example 24 faujasite 200 0.8 1.3 0.62 Example 25 HCl 170* 0.6 3.0 0.2 * At 200°C only acridine formation, reaction too fast to determine kinetics Compared to the HCl catalyst, all zeolites suppressed the formation of acridine, indicating that the confined environment surrounding the acid site inhibits formation of bulky products. Isomerization of mixtures of 2,2’-/2,4’-MDA to 4,4’-MDA First, a catalyst (100 mg, see table 2), an industrial product feed comprising 2,2’- and 2,4’-MDA (500 mg) and 1.2 mL aniline were added to a GC vial. The GC vial was flushed with Ar and the vial was heated to 170°C. After the reaction, THF was added to dilute the reaction mixture. The obtained products were identified by GC-MS. For quantification, tetradecane was added as an external standard and analysis was done using GC. Rate constants were calculated according to Reference Example 2. Further, the isomerization of an industrial product stream was tested with HCl (see fig.10) as catalyst and zeolite beta (see fig.11) as zeolite catalysts. Beta zeolite supressed oligomeriza- tion and acridine formation and yielded an increased 4,4’-MDA. DESCRIPTION OF THE FIGURES Figure 1 shows a reaction scheme for the isomerization of 2,4’-MDA, wherein the kinetic val- ues are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligomer). Figure 2 shows the effect of aniline concentration on 2,4’-MDA isomerization, wherein the ki- netic values are represented respectively by: ◇ kiso,1 (2,4’→ 4,4’); ◆ kiso,2 (2,4’ → 2,2’) and ○ koligo(MDA → oligomer). Figure 3 shows the product distribution after the 2,4’-MDA isomerization using different cata- lysts. Figure 4 shows the change in concentrations during 2,4’-MDA isomerization using CF3SO3H as catalyst, wherein the kinetic values are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligo- mer). Figure 5 shows the change in concentrations during 2,4’-MDA isomerization using a MFI ze- olite catalyst, wherein the kinetic values are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligo- mer). Figure 6 shows the change in concentrations during 2,4’-MDA isomerization using HCl as catalyst, wherein the kinetic values are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligo- mer). Figure 7 shows the change in concentrations during 2,4’-MDA isomerization using a beta ze- olite catalyst, wherein the kinetic values are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligo- mer). Figure 8 shows the change in concentrations during 2,4’-MDA isomerization using a MCM-68 zeolite catalyst, wherein the kinetic values are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligomer). Figure 9 shows the change in concentrations during 2,4’-MDA isomerization using a Y-UZM- 35 zeolite catalyst, wherein the kinetic values are represented respectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligomer) and wherein an industrial waste stream is used. Figure 10 shows the change in concentrations during the isomerization of an industrial product stream using HCl as catalyst, wherein the kinetic values are represented respec- tively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligomer). Figure 11 shows the change in concentrations during the isomerization of an industrial product stream using a beta zeolite catalyst, wherein the kinetic values are represented re- spectively by: kiso,1 (2,4’→ 4,4’); kiso,-1(4,4’ → 2,4’), kiso,2 (2,4’ → 2,2’), kiso,-2 (2,2’ → 2,4’) and koligo(MDA → oligomer) and wherein an industrial waste stream is used. Cited prior art documents: ^ EP 0329367 A2 ^ WO 2021/116419 A ^ P. J. Whitman et al., ‘Protodealkylation of bis(aminophenyl)methanes’, Tetrahedron Let- ters, Vol.27, pages 1887-1890

Claims

Claims 1. A process for the isomerization of 2,4’- methylenedianiline and/or 2,2’- methylenediani- line to 4,4’-methylenedianiline, respectively, the process comprising (1) preparing a feed F2 comprising 2,4’-methylenedianiline and/or 2,2’- methylenedian- iline and optionally further comprising aniline; (2) providing a catalyst C2 comprising a Bronsted acid; (3) contacting the feed F2 prepared in (1) with the catalyst C2 provided in (2), obtain- ing a mixture M2 comprising 4,4’-methylenedianiline as a reaction product; (4) optionally separating the 4,4’-methylenedianiline from the reaction product ob- tained in (3); wherein the feed F2 in (1) comprises 5 wt.-% or less of formaldehyde. 2. The process according to claim 1, wherein the amount of 2,4’-methylenedianiline in the feed F2 in (1) ranges from 1 to 60 wt.-%. 3. The process according to any one of claim 1 or 2, wherein the concentration of 4,4’- methylenedianiline in the mixture M2 obtained by (3) is greater than the concentration of 4,4’-methylenedianiline which may optionally be comprised in the feed F2 prepared in (1). 4. The process according to any one of claims 1 to 3, wherein the molar ratio of 2,4’- methylenedianiline to 2,2’-methylenedianiline in the feed F2 in (1) is in the range of from 1:1 to 100:1. 5. The process according to any one of claims 1 to 4, wherein the feed F2 in (1) com- prises aniline, wherein the amount of aniline in the feed F2 in (1) ranges of from 45 to 90 wt.-%. 6. The process according to any one of claims 1 to 5, wherein the feed F2 in (1) further comprises one or more of 4,4’-methylenedianiline, oligomers of 2,2’-methylenedianiline, oligomers of 2,4’-methylenedianiline, and oligomers of 4,4’-methylenedianiline. 7. The process according to any one of claims 1 to 6, wherein the feed F2 in (1) is a prod- uct feed obtained from a process for the preparation of one or more of 4,4’-methylene- dianiline, 2,2’-methylenedianiline, 2,4’-methylenedianiline, and oligomers thereof. 8. The process according to any one of claims 1 to 7, wherein preparing the feed F2 in (1) comprises (1.1) providing a feed F1a comprising aniline and a feed F1b comprising formalde- hyde; (1.2) contacting the feeds F1a and F1b provided in (1.1), obtaining a mixture M1b; (1.3) optionally separating water from the mixture M1b obtained in (1.2), obtaining a Mixture M1c; (1.4) providing a catalyst C1 comprising a Bronsted acid; and (1.5) contacting the mixture M1b obtained in (1.2) or the mixture M1c obtained in (1.3) with the catalyst C1 provided in (1.4), obtaining a mixture M1a comprising 2,4’- methylenedianiline. 9. A process for the isomerization of 2,2’- methylenedianiline to 2,4’-methylenedianiline, the process comprising (1’) preparing a feed F3 comprising 2,2’- methylenedianiline and optionally further comprising aniline; (2’) providing a catalyst C3 comprising a Bronsted acid; (3’) contacting the feed F3 prepared in (1’) with the catalyst C3 provided in (2’), obtain- ing a mixture M3 comprising 2,4’-methylenedianiline as a reaction product; wherein the feed F3 in (1’) comprises 5 wt.-% or less of formaldehyde. 10. The process of claim 9, the process further comprising (4’) providing a catalyst C2 comprising a Bronsted acid; (5’) contacting the mixture M3 prepared in (3’) with the catalyst C2 provided in (4’), ob- taining a mixture M4 comprising 4,4’-methylenedianiline as a reaction product; (6’) optionally separating the 4,4’-methylenedianiline from the reaction product obtained in (5’). 11. The process according to any one of claims 1 to 10, wherein independently from each other the Bronsted acid in (2) or (2’) and/or (4’) is a zeolite. 12. The process according to any one of claims 1 to 11, wherein independently from each other the Bronsted acid in (2) or (2’) and/or (4’) is an inorganic acid. 13. The process according to any one of claims 10 to 12, wherein the concentration of 4,4’- methylenedianiline in the mixture M4 obtained by (5’) is greater than the concentration of 4,4’-methylenedianiline which may optionally be comprised in the feed F3 prepared in (1’). 14. The process according to any one of claims 9 to 13, wherein the feed F3 in (1’) com- prises 2,2’-methylenedianiline and wherein the amount of 2,2’-methylenedianiline in the feed F3 ranges from 1 to 40 wt.-%. 15. The process according to any one of claims 9 to 14, wherein the feed F3 in (1’) com- prises aniline, wherein the amount of aniline in the feed F3 in (1’) ranges of from 45 to 90 wt.-%. 16. The process according to any one of claims 9 to 15, wherein preparing the feed F3 in (1’) comprises (1.1’) providing a feed F1a comprising aniline and a feed F1b comprising formalde- hyde; (1.2’) contacting the feeds F1a and F1b provided in (1.1’), obtaining a mixture M1b’; (1.3’) optionally separating water from the mixture M1b’ obtained in (1.2’), obtaining a mixture M1c’; (1.4’) providing a catalyst C1 comprising a Bronsted acid; and (1.5’) contacting the mixture M1b’ obtained in (1.2’) or the mixture M1c’ obtained in (1.3’) with the catalyst C1 provided in (1.4’), obtaining a mixture M1a’ comprising 2,2’- methylenedianiline.
EP24727711.4A 2023-05-19 2024-05-17 Process for the isomerization of aromatic amines Pending EP4713309A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP23174260 2023-05-19
PCT/EP2024/063668 WO2024240631A1 (en) 2023-05-19 2024-05-17 Process for the isomerization of aromatic amines

Publications (1)

Publication Number Publication Date
EP4713309A1 true EP4713309A1 (en) 2026-03-25

Family

ID=86469235

Family Applications (1)

Application Number Title Priority Date Filing Date
EP24727711.4A Pending EP4713309A1 (en) 2023-05-19 2024-05-17 Process for the isomerization of aromatic amines

Country Status (4)

Country Link
EP (1) EP4713309A1 (en)
KR (1) KR20260014603A (en)
CN (1) CN121152780A (en)
WO (1) WO2024240631A1 (en)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0329367A3 (en) 1988-02-15 1990-10-31 Mitsui Petrochemical Industries, Ltd. Method of preparing 4,4'-methylenedianiline
EP4072726A1 (en) 2019-12-13 2022-10-19 Basf Se Heterogeneous synthesis of methylene dianiline

Also Published As

Publication number Publication date
KR20260014603A (en) 2026-01-30
CN121152780A (en) 2025-12-16
WO2024240631A1 (en) 2024-11-28

Similar Documents

Publication Publication Date Title
JP4681194B2 (en) Method for producing diaminodiphenylmethane
US20230028994A1 (en) Heterogeneous synthesis of methylene dianiline
CN106660938B (en) Process for producing diamines and polyamines of diphenylmethane series
US20100174117A1 (en) Method for pre-treating hydroamination catalysts
US20030228970A1 (en) Process for regenerating titanium-containing catalysts
EP2099734B1 (en) Method of preparing mono-iodo benzene through transiodination
EP4713309A1 (en) Process for the isomerization of aromatic amines
US6958397B2 (en) Method of selectively synthesizing triethylenediamine
NL2007478C2 (en) Method for manufacturing cyclohexanone oxime.
KR100716096B1 (en) Process for the production of triethylenediamine using ethylenediamine
CS277105B6 (en) Process for preparing nitrobenzenes
CN107445788B (en) Method for liquid-phase transalkylation of polyethylbenzene and benzene
CN100450619C (en) Method for producing ε-caprolactam and method for activating a catalyst for producing ε-caprolactam
EP1814836B1 (en) Continuous process for the preparation of phenol from benzene in a fixed bed reactor
JP4297702B2 (en) Dinitronaphthalene isomer mixture and process for producing 1,5-diaminonaphthalene
JP4505911B2 (en) Method for producing diarylamine
US6825388B2 (en) Process for the preparation of 4-nitro-o-xylene
KR20060044642A (en) Method for producing ε-caprolactam
EP0648724B1 (en) Process for the preparation of 1-Bromo-3,5-difluorobenzene
JPH02180843A (en) Production of dichlorobenzene
EP4602024A1 (en) Process for producing hexamethylenediamine from caprolactam
JP3879290B2 (en) Process for producing aromatic compounds
JPH02184658A (en) Production of 4,4'-methylenedianiline
JP2595637B2 (en) Highly selective production of p-dichlorobenzene
JPH0796533B2 (en) Method for producing aromatic nitro compound

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20251219

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC ME MK MT NL NO PL PT RO RS SE SI SK SM TR