METHOD FOR THE PRODUCTION OF CRESOL FROM DITOLYLE ETHER

Description

[0001] The present invention relates to new processes for the production of cresol from dititolyl ether. State of the art

[0002] It is known that the CO bonds of aromatic ethers can be cleaved by means of hydrolysis or hydrogenolysis, for example in the presence of radioactive thorium oxide (DE-A 2604474), which does not open up any industrial application possibilities.

[0003] Furthermore, the use of nickel / nickel compounds on various supports, such as carbon or aluminum oxide / silicon oxide, is known for the hydrogenolysis of CO bonds in diaryl ethers in the presence of larger amounts of sterically demanding strong bases, such as NaOtBu or potassium hexamethyldisilazide (see Gao et al. Angew. Chem. Int. Ed. 2016, 55, 1474-1478). The disadvantages here are, in particular, the long reaction time, the high proportion of transition metal nickel, and also the necessary use of sterically demanding strong bases, which must be separated in a complex process. Object of the present invention

[0004] The object of the present invention is therefore to provide an improved process for the production of cresol from dititol ether that enables the simple production of cresol in high yield and with high selectivity. Solution to the task

[0005] It has now been surprisingly found that the problem can be solved if dititolyl ether and water are reacted in the presence of a catalyst consisting of at least 2 of the following oxides: titanium oxide, zirconium oxide and tungsten oxide, and / or if a catalyst from the group of zeolites is used, containing at least 85 wt% of at least 2 of the following oxides, selected from aluminum oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide. Subject matter of the invention

[0006] The present invention relates to a method for producing Cresol out of Ditoyl ether and Water in the presence of Catalysts,which consist of at least 2 of the following oxides: titanium oxide, zirconium oxide and tungsten oxide, and / or that a catalyst from the group of zeolites is used which contains at least 85 wt% of at least 2 of the following oxides, selected from aluminum oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide.

[0007] It is preferred that a catalyst consisting of at least 2 of the following oxides titanium oxide, zirconium oxide and tungsten oxide and / or a catalyst from the group of zeolites is used, which contains at least 85 wt.% of at least 2 of the following oxides, selected from aluminium oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide.

[0008] Cresol within the meaning of the invention o-cresol, m-cresol and p-cresol as a single compound as well as in a mixture. Mixtures can exist in any ratio of o-, m-, and p-cresol to each other.

[0009] Ditoyl etherFor the purposes of the invention, 2,2'-, 2,3'-, 2,4'-, 3,3'-, 3,4'- and / or 4,4'-ditolyl ethers as a single compound as well as as a mixture of 2 or more of these single aforementioned compounds are included.

[0010] The use of a mixture of is preferred. 2,2'-, 2,3'-, 2,4'-, 3,3'-, 3,4'- and 4,4'-ditolyl ethers, as is produced, for example, during the alkaline hydrolysis of chlorotoluenes (see H. Fiege, Cresols and Xylenols, Ullmann's Encyclopedia of Industrial Chemistry, page 427, Vol. 10, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2012.)

[0011] Water For the purposes of the invention, this preferably includes fully demineralized water.

[0012] catalyst In the context of the invention, this means that a catalyst is used which contains at least 85 wt.%, preferably 90-100 wt.%, at least 2 of the following oxides, selected from aluminium oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide.

[0013] In a preferred embodiment, the catalyst from at least 2 of the following oxides: titanium oxide, zirconium oxide and tungsten oxide and / or from the group of zeolites, which contain at least 85 wt% of at least 2 of the following oxides, selected from aluminium oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide.

[0014] In a preferred embodiment, the catalyst from the group of zeolites silicon dioxide, aluminum oxide, titanium oxide and / or zirconium oxide.

[0015] It is preferred that the catalyst preferably contains silicon oxide and aluminum oxide and that the molar ratio of silicon to aluminum is preferably 3:1 to 300:1, particularly preferably 5:1 to 250:1, and most preferably 30:1 to 90:1.

[0016] In a particularly preferred embodiment, the catalyst the structure of a Zeolites. Under ZeoliteFor the purposes of the invention, a microporous material is preferably understood to be one whose structure is characterized by a framework of corner-sharing tetrahedra. Each tetrahedron typically consists of four oxygen atoms surrounding a cation. Preferred cations for these tetrahedra are preferably aluminum and silicon.

[0017] The zeolite structure preferably consists of oxygen-aluminum tetrahedra and oxygen-silicon tetrahedra.

[0018] Each zeolitic cell structure is known to be characterized by a 3-letter code via the Structure Commission of the International Zeolite Association (IZA).

[0019] Particularly preferred are zeolites consisting of mixtures of aluminum oxide and silicon oxide of the following framework types: LTA = Linde Type A (e.g.: Zeolite A), MFI = Mobil Five (e.g.: ZSM-5, Zeolite Socony Mobil-5), MOR = Mordenite, BEA = Beta Zeolite and / or FAU = Faujasite (e.g.: Zeolite X,Y).

[0020] MFI and MOR are particularly preferred as scaffolding types.

[0021] The zeolite can be used as a powder or as a shaped body. For shaping into a formed body, the zeolite is preferably combined with 5-70 wt% aluminum- or silicon-based binder material and various inorganic and organic additives, such as nitric acid, citric acid, acetic acid, methylcellulose, glycerol, polyethylene glycol, sugar, and / or starch, and then processed. In this case, processing includes the steps of shaping, e.g., by pressing, and tempering at temperatures in the range of 350 to 900 °C.

[0022] For the process according to the invention, commercially available ZSM-5 zeolites (Zeolite Socony Mobil-5) and MFI zeolites, for example from Clariant Produkte (Deutschland) GmbH, are preferably used from the group of MFI zeolites.

[0023] The ZSM-5 and MFI host structure is predominantly characterized by ten-membered rings that form a pore system oriented in three spatial directions and intersecting each other. Furthermore, as is typical for "high-silica" zeolites and pentasil zeolites, there is a large number of five-membered rings (in addition to a few four-, six-, seven-, and eight-membered rings).

[0024] The general chemical composition of the zeolite group is exemplified for Al and Si oxide as follows: M n+< x / n [(AlO 2 ) -< x (SiO 2 ) y ] · z H 2 O

[0025] Mn+ is a cation, preferably Hn+, Nan+, and / or NH4+, where n denotes the charge of the cation and is preferably 1 or 2. The Mn+ cations are generally not part of the structure-forming aluminum-oxygen tetrahedra and silicon-oxygen tetrahedra, but are located in the zeolite channels or cavities for charge balance. In the preferred embodiment, Hn+ is used as the cation, which can be denoted as H-ZSM-5 and H-MFI. The type of cation can be reversibly changed by chemical derivatization, e.g., via ion exchange reactions.

[0026] The molar ratio of oxygen-silicon tetrahedra to oxygen-aluminum tetrahedra (Si / Al ratio for short) is called the modulus and is expressed by the quotient y / x. In the preferred form, y / x is between 3 and 300, and particularly preferably between 30 and 90. The quotient can be denoted as H-MFI-y / x, e.g., H-MFI-90.

[0027] For the process according to the invention, commercially available mixed oxide catalysts can be used as shaped bodies, preferably as spheres or extrudates. Such catalysts include, for example, mixtures of ZrO₂ / WO₃ and ZrO₂ / SiO₂ from Saint-Gobain Ceramic Materials GmbH, and Al₂O₃ / SiO₂ from Shell Catalysts & Technologies Leuna GmbH. Commercially available zeolites can also be used as mixtures of Al₂O₃ / SiO₂, preferably as spheres or extrudates. Examples of commercially available zeolites are extrudates of MFI zeolites, MOR zeolites, BEA zeolites, such as those from Clariant Produkte (Deutschland) GmbH, and FAU zeolites, such as those from Zeolyst International.

[0028] The process according to the invention is preferably carried out at temperatures of 250 to 450°C, preferably 270 to 400°C, particularly preferably 300 to 370°C.

[0029] The method according to the invention is preferably carried out at a pressure of 0.5 bar to 300 bar, particularly preferably 0.9 bar to 50 bar and most preferably 1 bar to 10 bar.

[0030] The process according to the invention is preferably carried out in reactors.

[0031] Any vessel capable of metering gases and where the catalyst is a rigid bed, e.g., fixed-bed reactors, or where the catalyst is moved by the feedstock or a stirring unit, e.g., entrained-flow reactors, fluidized-bed reactors, or batch reactors, can be used as reactors. The feedstocks can be metered in gaseous or liquid form. In the preferred embodiment, the feedstocks are metered as gases into a fixed-bed reactor with a rigid catalyst bed. The process according to the invention can be carried out continuously or batchwise.

[0032] The total amount of catalyst, based on dititolyl ether (DTE), can be chosen arbitrarily for continuously or batch-operated reactors. For continuously operated reactors, this is preferably 0.01–1000 g DTE / (g catalyst × h), particularly preferably 0.1–100 g DTE / (g catalyst × h). For batch-operated reactors, this is preferably 0.1–10000 g DTE / g catalyst.

[0033] The molar ratio of Ditoyl ether to water The ratio is preferably 10:1 to 1:40, particularly preferably 1:1 to 1:20, and most particularly preferably 1:5 to 1:15.

[0034] In addition to dititol ether and water, another gas, preferably an inert gas such as nitrogen or argon, can be added. Preferably, enough standard liters Ln of nitrogen or argon are added such that the proportion of the total volume is 0–95 vol%, particularly preferably 0–40 vol%.

[0035] NitrogenIn accordance with the invention, it preferably has a purity greater than 99 vol.%.

[0036] In this embodiment of the method for producing Cresol out of Ditoyl ether and Water In the presence of a catalyst, this is also referred to as hydrolytic cleavage of the dititol ether.

[0037] In this preferred embodiment of the invention, the following implementation of the method in continuous operation is preferred: The catalyst The mixture is placed in a fixed-bed reactor and heated to 300 °C to 370 °C. A mixture of dititolyl ether and water, preheated to at least 250 °C in a molar ratio of 1:5 to 1:15 and containing a maximum of 40 vol% nitrogen, is fed at a rate of 0.1 g to 5 g of dititolyl ether per g of catalyst per hour. The resulting reaction product is collected, as it contains cresol in high yield.

[0038] In a further preferred embodiment of the invention, the production of Cresol out of Ditoyl ether hydrogenolytic by implementing it in the presence of water, hydrogen and a catalyst which additionally contains at least one metal from the group of Platinum group metals (Ru, Rh, Pd, Os, Ir, Pt) contains.

[0039] Advantage of hydrogenolytic Production of Cresol out of Ditoyl ether is the simultaneous occurrence of toluene.

[0040] In this preferred embodiment of the invention, with regard to Cresol, diitolyl ether, water Reference is made to the aforementioned definitions and embodiments.

[0041] hydrogen In accordance with the invention, it preferably has a purity greater than 99 vol.%.

[0042] catalystIn the context of the invention with regard to hydrogenolysis, this means that a catalyst is used which contains at least 85 wt.%, preferably 90 - 99.9 wt.%, at least 2 of the following oxides, selected from aluminum oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide, and additionally at least one element from the platinum group metals.

[0043] In a preferred embodiment, the catalyst Silicon oxide and aluminum oxide or zirconium oxide and tungsten oxide and additionally at least one element from the platinum group metals.

[0044] It is preferred that the molar ratio of silicon oxide to aluminum oxide is 3:1 to 300:1, particularly preferably 5:1 to 250:1, and most preferably 30:1 to 90:1.

[0045] In a particularly preferred embodiment, the catalyst the structure of a Zeolites. Regarding the definition of ZeoliteFor the purposes of the invention, reference is made to the above statements.

[0046] Particularly preferred are zeolites consisting of mixtures of aluminum oxide and silicon oxide of the following framework types: LTA = Linde Type A (e.g.: Zeolite A), MFI = Mobil Five (e.g.: ZSM-5, Zeolite Socony Mobil-5), MOR = Mordenite, BEA = Beta Zeolite and / or FAU = Faujasite (e.g.: Zeolite X,Y).

[0047] MFI and MOR are particularly preferred as scaffolding types.

[0048] A proportion of 0.1–10 wt.% of the platinum group metals, based on the total amount of the catalyst, is preferred. A proportion of 0.5–5 wt.% of the platinum group metals is particularly preferred.

[0049] Furthermore, it is preferred that the Metal from the platinum group metals which involves platinum and / or rhodium.

[0050] Platinum metal-containing catalystsPrecious metal catalysts can be produced using standard manufacturing processes. For example, a metal salt solution of the precious metal is brought into contact with the catalyst substrate by impregnation or spraying. Impregnation can be carried out as immersion impregnation, where the volume of aqueous solution is greater than the liquid absorption volume of the catalyst substrate, or as dry impregnation, where the volume of aqueous solution is less than or equal to the liquid absorption volume of the catalyst substrate. The same applies to spraying precious metal solutions onto the catalyst substrate. Furthermore, an ion exchange process can be used to add precious metals to the catalysts, for example, by repeatedly dosing a dilute metal salt solution of the precious metal over a catalyst substrate.Following impregnation, spraying, or ion exchange, the precious metal-containing catalyst is dried, preferably in an air stream at elevated temperature, preferably at 60 °C to 200 °C for 0.5 to 10 hours. Optionally, calcination at elevated temperature can also be carried out, preferably at 200 °C to 1000 °C for 10 minutes to 24 hours.

[0051] The inventive method is preferably used in Temperatures is carried out at temperatures of 250 to 450°C, particularly preferably 270 to 400°C, and most preferably 300 to 370°C.

[0052] The inventive method is preferably used in a Pressure from 0.5 bar to 300 bar, particularly preferably from 0.9 bar to 50 bar and most preferably from 1 bar to 10 bar.

[0053] The inventive method is preferably used in Reactors carried out.

[0054] As Reactors are all containerThe process can be used in reactors that allow the dosing of gases and where the catalyst is present as a rigid bed, e.g., fixed-bed reactors, and in reactors where the catalyst is moved by the feedstock or a stirring unit, e.g., entrained-flow reactors, fluidized-bed reactors, or batch reactors. The feedstocks can be dosed in gaseous or liquid form. In the preferred embodiment, the feedstocks are dosed as gases into a fixed-bed reactor with a rigid catalyst bed. The process according to the invention can be carried out continuously or batchwise.

[0055] The total amount of catalyst, based on dititolyl ether (DTE), can be chosen arbitrarily for continuously or batch-operated reactors. For continuously operated reactors, this is preferably 0.01–1000 g DTE / (g catalyst × h), particularly preferably 0.1–100 g DTE / (g catalyst × h). For batch-operated reactors, this is preferably 0.1–10000 g DTE / g catalyst.

[0056] The molar ratio of Ditoyl ether to water The ratio is preferably 10:1 to 1:40, particularly preferably 1:1 to 1:20, and most particularly preferably 1:5 to 1:15.

[0057] The molar ratio of Ditoyl ether to hydrogen preferably 10:1 to 1:100, particularly preferably 1:1 to 1:50, most particularly preferably 1:5 to 1:40.

[0058] In addition to Ditoyl ether and Water and hydrogenAnother gas, e.g., an inert gas such as nitrogen or argon, can be metered in. Preferably, enough standard liters Ln of nitrogen or argon are metered in such a way that the proportion of the total volume is 0–95 vol%, particularly preferably 0–40 vol%.

[0059] As Reactors are all container These reactors can be used in both fixed-bed reactors, which allow the dosing of gases and where the catalyst is a rigid bed, e.g., fixed-bed reactors, and those where the catalyst is moved by the reactant feed or a stirring unit, e.g., entrained-flow reactors, fluidized-bed reactors, or batch reactors. The reactants can be dosed in gaseous or liquid form. In the preferred embodiment, the reactants are dosed as gases into a fixed-bed reactor with a rigid catalyst bed.

[0060] In this preferred embodiment of the invention as hydrogenolysis, the following implementation of the process in continuous operation is preferred: The catalystThe mixture is placed in a fixed-bed reactor and heated to 300 °C to 370 °C. A mixture of dititolyl ether, water, and hydrogen, preheated to at least 250 °C, with a molar ratio of dititolyl ether to water ranging from 1:5 to 1:15 and a molar ratio of dititolyl ether to hydrogen ranging from 1:5 to 1:40, and containing a maximum of 40 vol% nitrogen, is added at a rate of 0.1 g to 5 g of dititolyl ether per g of catalyst per hour. The resulting reaction product is collected, as it contains cresol in high yield.

[0061] The method according to the invention is explained with reference to the following examples, without being limited to them. Examples

[0062] The experiments listed below were carried out in a steel tube with a perforated bottom plate as a reactor. Information on the type and manufacturer of the catalyst for each experiment can be found in Tables 1 and 2. A gaseous mixture of dititolyl ether, water, and nitrogen and / or hydrogen was introduced into the reactor in the ratios specified in Tables 3 and 4. After the reaction, the product mixture was cooled to room temperature, and acetone was added to obtain a single-phase mixture, which was analyzed by gas chromatography-flame ionization. The results are listed in Tables 3 and 4. Table 1: Catalysts (CAT) used Nr. CAT composition Si / Al ratio Trade name of the respective CAT, before the precious metal is applied 1 (V) Al2O3 Al2O3 - Alumina Spheres 1.8 / 210, Sasol Germany GmbH 2 (E) ZrO₂, 18 wt% WO₃ ZrO 2 / WO 3 - SZ 61143, Saint-Gobain Ceramic Materials GmbH 3 (E) H-MFI-30 SiO2 / Al2O3 30:1 Clariant Products (Germany) GmbH 4 (E) H-MFI-55 SiO2 / Al2O3 55:1 Süd-Chemie AG 5 (E) H-MFI-60 SiO2 / Al2O3 60:1 Süd-Chemie AG 6 (E) H-MFI-90 SiO2 / Al2O3 90:1 HCZP 90E, Clariant Products (Germany) GmbH 7 (E) H-MOR-40 SiO2 / Al2O3 40:1 HCZM 40E, Clariant Products Germany GmbH 8 (E) H-MFI-30, 0.5 wt% platinum SiO2 / Al2O3 30:1 Clariant Products (Germany) GmbH 9 (E) H-MFI-55, 0.5 wt% platinum SiO2 / Al2O3 55:1 Süd-Chemie AG 10 (E) H-MFI-90, 0.5 wt% platinum SiO2 / Al2O3 90:1 HCZP 90E, Clariant Products (Germany) GmbH 11 (E) H-MFI-240, 0.5 wt% platinum SiO2 / Al2O3 240:1 Clariant Products (Germany) GmbH 12 (E) H-MFI-55, 1 wt% platinum SiO2 / Al2O3 55:1 Süd-Chemie AG 13 (E) H-MOR-40, 1 wt% platinum SiO2 / Al2O3 40:1 HCZM 40E, Clariant Products (Germany) GmbH 14 (E) H-MFI-90, 1 wt% Rhodium SiO2 / Al2O3 90:1 HCZP 90E, Clariant Products (Germany) GmbH 15 (E) H-MFI-60, 1 wt% platinum, 0.2 wt% nickel SiO2 / Al2O3 60:1 Süd-Chemie AG 16 (V) Al2O3 / SiO2 with 20 wt% nickel SiO2 / Al2O3 1:5 Based on Example 6 for diphenyl ethers in Gao et al. Angew. Chem. Int. Ed. 2016, 55, 1474-1478, without the addition of bases 17 (V) Norit RX 1.5 Extra activated carbon, 0.1 wt% platinum C - Norit RX 1.5 Extra, Cabot Norit Nederland BV MFI = SiO₂ / Al₂O₃ zeolite; MOR = SiO₂ / Al₂O₃ zeolite with mordenite structure; E = according to the invention, V = comparative example

[0063] The precious metal in the precious metal-containing catalysts (see Examples 8 (E) to 15 (E)) was applied – as explained below – by dry impregnation or ion exchange. Quantities and properties can be found in Table 2.

[0064] For dry impregnation, the precious metal source specified in Table 2 was dissolved in demineralized water and added to a substrate. The amount of demineralized water corresponds to 98% of the absorbency applicable to the respective substrate (see Table 2). After the solution was completely absorbed, the impregnated substrate was dried for 1 h at 120 °C in a warm air stream and—with the exception of Example 16 (V)—calcined in a static furnace for 12–16 hours at temperatures of 300–500 °C. In the case of Example 16 (V), dry impregnation and drying were repeated three times to apply the entire quantity of precious metal solution.

[0065] For the ion exchange, the precious metal doping solution was added to a support in a glass tube with a glass frit bottom, and the solution was pumped in a closed loop over the support for 24 hours. The support remained covered with liquid throughout this time. Table 2: Quantities and properties of precious metal-containing catalysts Nr. Carrier before precious metal doping Doping with precious metal Mass / g Water content / wt.% Absorbency / wt.% type Volume of solution / mL precious metal source 8 (E) 51,5 3,4 43,2 Dry soaking 22,2 1 g H₂PtCl₆ solution, 25 wt% Pt 9 (E) 51,7 3,8 40,5 Dry soaking 20,9 1 g H₂PtCl₆ solution, 25 wt% Pt 10 (E) 101,7 2,2 42,5 ion exchange 150,0 0.9 g [Pt(NH 3 ) 4 ]Cl 2 ×H 2 O 11 (E) 51,4 3,3 51,5 Dry soaking 25,6 1 g H₂PtCl₆ solution, 25 wt% Pt 12 (E) 102,9 3,8 40,5 ion exchange 150,0 1.8 g [Pt(NH 3 ) 4 Cl 2 ×H 2 O 13 (E) 106,4 7,0 38,2 Dry soaking 40,7 1 g H₂PtCl₆ solution, 25 wt% Pt 14 (E) 50,6 2,2 42,5 Dry soaking 21,1 5 g Rh(NO3)3 solution, 10 wt% Rh 15 (E) 51,9 4,7 46,0 Dry soaking 22,7 2 g H₂PtCl₆ solution, 25 wt% Pt + 0.5 g Ni(NO₃)₂ × 6H₂O 16 (V) 240,0 0,8 44,0 Dry soaking 320,0 291 g Ni(NO 3 ) 2 ×6H 2 O 17 (V) 72,2 3,2 92,8 Dry soaking 67,0 0.3 g H₂PtCl₆ solution, 25 wt% Pt Table 3: Measurement results for the hydrolytic cleavage of dititolyl ether at a temperature of 315 °C, a pressure of 1 bar and a catalyst volume of 68 mL. The flow rates were: 15.2 g / h dititolyl ether and 13.8 g / h water with a nitrogen content of 20 vol%. Nr. catalyst Revenue DTE / % Selectivity cresol / % Cresol yield / % 1 (V) Al2O3 1,3 51,9 0,7 2 (E) ZrO₂, 18 wt% WO₃ 23,1 54,0 12,5 3 (E) H-MFI-30 13,4 74,2 9,9 4 (E) H-MFI-55 12,8 68,2 8,7 5 (E) H-MFI-60 14,3 70,5 10,1 6 (E) H-MFI-90 7,4 84,6 6,2 7 (E) H-MOR-40 15,5 46,4 7,2 V = comparison, E = according to the invention

[0066] In the experiments 2-7 carried out with water according to the inventive method, a high conversion, a high selectivity and a high yield were observed in comparison to the comparative example, Example 1 (V). Table 4: Measurement results for the hydrogenolytic cleavage of dititolyl ether at a temperature of 315 °C, a pressure of 1 bar, and a catalyst volume of 68 mL. The flow rates were: 15.2 g / h dititolyl ether and 13.8 g / h water with a hydrogen content of 20 vol%. Nr. catalyst Revenue DTE / % Selectivity of cresol / % Selectivity of toluene / % yield cresol + toluene / % 8 (E) H-MFI-30, 0.5 wt% platinum 93,3 21,9 41,7 59,4 9 (E) H-MFI-55, 0.5 wt% platinum 95,3 22,3 32,2 51,9 10 (E) H-MFI-90, 0.5 wt% platinum 86,9 22,1 40,1 54,1 11 (E) H-MFI-240, 0.5 wt% platinum 98,1 20,7 37,3 56,9 12 (E) H-MFI-55, 1 wt% platinum 85,4 32,4 43,4 64,8 13 (E) H-MOR-40, 1 wt% platinum 94,2 17,7 35,1 49,7 14 (E) H-MFI-90, 1 wt% Rhodium 36,3 35,1 39,4 27,1 15 (E) H-MFI-60, 1 wt% platinum, 0.2 wt% nickel 96,5 16,7 32,2 47,3 16 (V) 1)< Al2O3 / SiO2 with 20 wt% nickel 1,8 16,3 5,1 0,4 17 (V) Norit RX 1.5 Extra activated carbon, 0.1 wt% platinum 4,4 32,1 42,0 3,2 V = comparative experiments, E = according to the invention 1)< analogous to Gao et al. Angew. Chem. Int. Ed. 2016, 55, 1474-1478.

[0067] It was shown that in the experiments 8 (E) - 13 (E) and 15 (E) carried out according to the inventive method for platinum-containing or, in the case of example 14 (E), for rhodium-containing catalysts, a high conversion with respect to dititolyl ether and a high selectivity and yield with respect to cresol and toluene are obtained, in comparison to the comparative examples 16 (V) and 17 (V).

[0068] Comparative example 16 (V) also shows that the prior art use of nickel without the addition of a strong base results in extremely low conversion, significantly lower selectivity and yield than the inventive catalysts 8 (E) - 15 (E) containing at least one element of the platinum group.

Claims

1. Process for producing cresol from ditolyl ether and water in the presence of a catalyst, characterized in that a catalyst consisting of at least 2 of the following oxides titanium oxide, zirconium oxide and tungsten oxide and / or a catalyst from the group of zeolites which contains at least 85% by weight of at least 2 of the following oxides selected from aluminium oxide, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide is employed.

2. Process according to Claim 1, characterized in that the catalyst from the group of zeolites contains silicon oxide, aluminium oxide, titanium oxide and / or zirconium oxide.

3. Process according to Claim 1 or 2, characterized in that the catalyst from the group of zeolites contains silicon oxide and aluminium oxide and the molar ratio of silicon to aluminium is 3:1 to 300:1, preferably 5:1 to 250:1, particularly preferably 30:1 to 90:1.

4. Process according to any of Claims 1 to 3, characterized in that the catalysts employed are zeolites of the types LTA, MFI, MOR, BEA, FAU, particularly preferably MFI, MOR.

5. Process according to any of Claims 1 to 4, characterized in that the catalyst additionally contains at least one element from the group of platinum metals and the reaction is performed in the presence of hydrogen.

6. Process according to any of Claims 1 to 5, characterized in that the proportion of the elements from the group of platinum metals is 0.1-10% by weight, based on the total amount of the catalyst, particularly preferably 0.5-5% by weight.

7. Process according to either of Claims 5 to 6, characterized in that the metal from the group of platinum metals is platinum and / or rhodium.

8. Process according to any of Claims 1 to 7, characterized in that it is performed at temperatures of 250°C to 450°C, preferably 270°C to 400°C, particularly preferably 300°C to 370°C.

9. Process according to any of Claims 1 to 7, characterized in that it is performed at a pressure of 0.5 bar to 300 bar, particularly preferably 0.9 bar to 50 bar and very particularly preferably 1 bar to 10 bar.