Method for preparing cresol from xylene ether

Abstract

This invention relates to a novel method for preparing cresol from xylyl ether.

Description

Technical Field

[0001] This invention relates to a novel method for producing cresol from xylyl ether. Background Technology

[0002] It is known that the CO bond of aromatic ethers can be broken, for example, by hydrolysis or hydrogenolysis in the presence of radioactive thorium oxide (DE-A 2604474), but this does not enable industrial applications.

[0003] In the hydrogenolysis of CO bonds in diaryl ethers, nickel / nickel compounds are known to be used for various substrates such as carbon or alumina / silica, in the presence of relatively large amounts of space-constrained strong bases such as NaOtBu or hexamethyldisilazine potassium azide (see Gao et al. Angew. Chem. Int. Ed. 2016, 55, 1474-1478). The disadvantages include long reaction times, a high proportion of transition metal nickel, and the necessity of using space-constrained strong bases that require expensive and complex separation.

[0004] Purpose of the invention

[0005] Therefore, the object of the present invention is to provide an improved method for producing cresol from xylyl ether, which allows for the simple production of cresol with high yield and high selectivity.

[0006] Objective

[0007] It has now been unexpectedly discovered that this can be achieved when xylyl ether and water react in the presence of a catalyst containing at least two oxides selected from the following: alumina, silicon oxide, titanium oxide, zirconium oxide and / or tungsten oxide. Summary of the Invention

[0008] The present invention provides a method for producing cresol from xylyl ether and water in the presence of a catalyst containing at least 85% by weight of at least two oxides selected from the group consisting of: alumina, silicon oxide, titanium oxide, zirconium oxide and / or tungsten oxide.

[0009] Preferably, a catalyst composed of at least two of the following oxides is used: titanium oxide, zirconium oxide and tungsten oxide, and / or a catalyst from the zeolite group containing at least 85% by weight of at least two of the following oxides selected from: alumina, silicon oxide, titanium oxide, zirconium oxide and tungsten oxide.

[0010] In the context of this invention, cresol includes o-cresol, m-cresol, and p-cresol in the form of individual compounds and mixtures. Mixtures may contain o-cresol, m-cresol, and p-cresol in any desired ratio.

[0011] In the context of this invention, xylyl ethers include 2,2'-xylyl ether, 2,3'-xylyl ether, 2,4'-xylyl ether, 3,3'-xylyl ether, 3,4'-xylyl ether and / or 4,4'-xylyl ether, in the form of individual compounds and mixtures of two or more of these individual compounds.

[0012] Preferred materials include mixtures of 2,2'-xylyl ether, 2,3'-xylyl ether, 2,4'-xylyl ether, 3,3'-xylyl ether, 3,4'-xylyl ether and 4,4'-xylyl ether (see: H. Fiege, Cresols and Xylenols, Ullmann's Encyclopedia of Industrial Chemistry, page 427, vol. 10, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2012 [H. Fiege, Cresols and Xylenols, Ullmann's Encyclopedia of Industrial Chemistry, page 427, vol. 10, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2012]).

[0013] In the context of this invention, water preferably comprises softened water.

[0014] In the context of this invention, catalyst is to be understood to mean a catalyst containing at least 85% by weight, preferably 90%-100% by weight, of at least two of the following oxides: alumina, silicon oxide, titanium oxide, zirconium oxide, and tungsten oxide.

[0015] In a preferred embodiment, the catalyst consists of at least two of the following oxides: titanium oxide, zirconium oxide, and tungsten oxide, and / or consists of a zeolite group containing at least 85% by weight of at least two of the following oxides: alumina, silicon oxide, titanium oxide, zirconium oxide, and tungsten oxide.

[0016] In a preferred embodiment, the catalyst from the zeolite group contains silicon oxide, aluminum oxide, titanium oxide, and / or zirconium oxide.

[0017] Preferably, the catalyst contains silicon oxide and aluminum oxide, and the molar ratio of silicon to aluminum is preferably from 3:1 to 300:1, particularly preferably from 5:1 to 250:1, and very particularly preferably from 30:1 to 90:1.

[0018] In a particularly preferred embodiment, the catalyst has a zeolite structure. In the context of this invention, zeolite is preferably understood to mean a microporous material whose structure is characterized by a tetrahedral framework with connected vertices. Each tetrahedron typically consists of four oxygen atoms surrounding a cation. The preferred cations for these tetrahedra are preferably selected from aluminum and silicon. The zeolite structure preferably consists of oxygen-aluminum tetrahedra and oxygen-silicon tetrahedra.

[0019] As is well known, the cell structure of each zeolite is characterized by a three-letter code by the International Zeolite Association (IZA) Structure Committee.

[0020] Zeolite is particularly preferred as a mixture of alumina and silica having the following framework types:

[0021] LTA = Linde type A (e.g., type A zeolite),

[0022] MFI = Mobil Type 5 (e.g., ZSM-5, Socone Mobil Zeolite-5).

[0023] MOR = Silky Zeolite

[0024] BEA = β-zeolite, and / or

[0025] FAU = octahedral zeolite (e.g., X-type and Y-type zeolite).

[0026] The most preferred frame types are MFI and MOR.

[0027] Zeolite can be used in powder or molded form. For molding, it is preferable to mix and process the zeolite with 5%-70% by weight of an aluminum-based or silicone-based binder and various inorganic and organic additives (e.g., nitric acid, citric acid, acetic acid, methylcellulose, glycerol, polyethylene glycol, sugar, and / or starch). Processing in this case includes molding steps, such as by pressing, and heating at a temperature ranging from 350°C to 900°C.

[0028] The method according to the invention preferably uses commercially available ZSM-5 zeolite (Soconi Mobil 5) and MFI zeolite from the MFI zeolite group, for example from Clariant Produkte (Deutschland) GmbH.

[0029] The main structure of ZSM-5 and MFI is preferably characterized by ten-membered rings forming a three-dimensional interlocking hole system. In addition, for "high-silica" zeolites and pentasil zeolites, there are typically a large number of five-membered rings (in addition to a small number of four-membered, six-membered, seven-membered, and eight-membered rings).

[0030] For example, Al oxides and Si oxides, the general chemical composition of the zeolite group is as follows:

[0031] M n+ x / n [(AlO2) - x (SiO2) y ]·z H2O

[0032] M n+ It is a cation, preferably H. + Na + and / or NH4 + Where n represents the charge of the cation and is preferably 1 or 2. Cation Mn + Typically, they are not part of the aluminum-oxygen tetrahedra or silicon-oxygen tetrahedra that define the structure, but are arranged in zeolite channels or cavities for charge balancing. In a preferred embodiment, H is used. + As cations, they can be characterized by symbols such as H-ZSM-5 and H-MFI. The type of cation can be reversibly changed by chemical derivatization, such as through ion exchange reactions.

[0033] The molar ratio of oxygen-silicon tetrahedra to oxygen-aluminum tetrahedra (abbreviated as Si / Al ratio) is called the modulus and is represented by the quotient y / x. In a preferred form, y / x is 3-300, and particularly preferred is 30-90. The quotient can be characterized by the symbol H-MFI-y / x, i.e., for example, H-MFI-90.

[0034] Catalysts usable in the method according to the invention include commercially available mixed oxide catalysts, preferably in the form of spheres or extrusions. Such catalysts are, for example, mixtures of ZrO2 / WO3 and ZrO2 / SiO2 from Saint-Gobain Ceramic Materials GmbH, and Al2O3 / SiO2 mixtures from Shell Catalysts & Technologies Leuna GmbH. The usable Al2O3 / SiO2 mixtures further include commercially available zeolites, preferably in the form of spheres or extrusions. Examples of commercially available zeolites are MFI zeolite, MOR zeolite, BEA zeolite (e.g., from Clariant Products (Germany) GmbH), and FAU zeolite (e.g., extrusions from Zeolyst International).

[0035] The method according to the invention is preferably carried out at a temperature of 250°C to 450°C, more preferably 270°C to 400°C, and particularly preferably 300°C to 370°C.

[0036] 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 very particularly preferably 1 bar to 10 bar.

[0037] The method according to the invention is preferably carried out in a reactor.

[0038] The reactors that can be used include all vessels that allow the addition of gas and in which the catalyst is in the form of a fixed bed, such as fixed-bed reactors, as well as those vessels in which the catalyst moves via reactant feed or agitation, such as entrained flow reactors, fluidized bed reactors, or batch reactors. The reactants can be added in gaseous or liquid form. In a preferred embodiment, the reactants are added in gaseous form to a fixed-bed reactor having a fixed catalyst bed. The method according to the invention can be carried out continuously or discontinuously.

[0039] The total amount of xylene ether (DTE)-based catalyst can be selected according to the needs of either continuous or discontinuous reactor operation. For continuous reactor operation, the amount is preferably 0.01-1000 g DTE / (g catalyst × h), particularly preferably 0.1-100 g DTE / (g catalyst × h). In the case of discontinuous reactor operation, the amount is preferably 0.1-10,000 g DTE / g catalyst.

[0040] The molar ratio of xylyl ether to water is preferably from 10:1 to 1:40, particularly preferably from 1:1 to 1:20, and very particularly preferably from 1:5 to 1:15.

[0041] In addition to xylene ether and water, other gases may be added, preferably inert gases such as nitrogen or argon. It is preferable to add the same amount of standard liters (STL) as required. n Nitrogen or argon gas is used to achieve a ratio of 0-95% by volume, particularly preferably 0-40% by volume, based on the total volume.

[0042] In the context of this invention, nitrogen gas preferably has a purity of greater than 99% by volume.

[0043] In this embodiment, the method for producing cresol from xylene ether and water in the presence of a catalyst can also be referred to as the hydrolytic cracking of xylene ether.

[0044] In this preferred embodiment of the invention, the method is preferably performed in the following continuous mode:

[0045] First, the catalyst is loaded into a fixed-bed reactor and heated to 300°C to 370°C. A mixture of xylene ether preheated to at least 250°C and water (molar ratio in the range of 1:5 to 1:15) with no more than 40% by volume nitrogen is added at a rate of 0.1 g to 5 g xylene ether per g catalyst per hour. The resulting reaction product is collected because it contains cresol formed in high yield.

[0046] In another preferred embodiment of the invention, the production of cresol from xylyl ether is carried out by hydrogenolysis in the presence of water, hydrogen and a catalyst, wherein the catalyst additionally contains at least one metal from the platinum group metals (Ru, Rh, Pd, Os, Ir, Pt).

[0047] The advantage of producing cresol by hydrogenolysis of xylyl ether is that toluene is also produced.

[0048] In this preferred embodiment of the invention, reference is made to the above definitions and examples regarding cresol, xylyl ether, and water.

[0049] In the context of this invention, hydrogen gas preferably has a purity of greater than 99% by volume.

[0050] In the context of this invention, the term "catalyst for hydrogenolysis" should be understood to mean the use of a catalyst containing at least 85% by weight, preferably 90% to 99.9% by weight, of at least two oxides selected from the group consisting of aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, and tungsten oxide, and at least one other element from the platinum group metals.

[0051] In a preferred embodiment, the catalyst contains silicon oxide and aluminum oxide or zirconium oxide and tungsten oxide, as well as at least one other element from the platinum group metals.

[0052] Preferably, the molar ratio of silicon oxide to aluminum oxide is 3:1 to 300:1, particularly preferably 5:1 to 250:1, and very particularly preferably 30:1 to 90:1.

[0053] In a particularly preferred embodiment, the catalyst has a zeolite structure. For the definition of zeolite in the context of this invention, refer to the foregoing.

[0054] Zeolite is particularly preferred as a mixture of alumina and silica having the following framework types:

[0055] LTA = Linde type A (e.g., type A zeolite),

[0056] MFI = Mobil Type 5 (e.g., ZSM-5, Soconi Mobil Zeolite-5),

[0057] MOR = Silky Zeolite

[0058] BEA = β-zeolite, and / or

[0059] FAU = octahedral zeolite (e.g., X-type and Y-type zeolite).

[0060] The most preferred frame types are MFI and MOR.

[0061] Based on the total amount of catalyst, the proportion of elements derived from platinum group metals is preferably 0.1 wt% to 10 wt%. The proportion of elements derived from platinum group metals is particularly preferably 0.5 wt% to 5 wt%.

[0062] More preferably, the metal from the platinum group metals is platinum and / or rhodium.

[0063] Catalysts containing platinum can be produced using methods commonly used for producing catalysts containing precious metals. This can be carried out, for example, by contacting a solution of a precious metal salt with a catalyst support through impregnation or spraying. Impregnation can be performed by a soak-impregnation method, in which the volume of the aqueous solution is greater than the liquid absorption volume of the catalyst support to be coated, or by a dry impregnation method, in which the volume of the aqueous solution is not greater than the liquid absorption volume of the catalyst support to be coated. The same applies to spraying a solution of precious metal onto a catalyst support. Ion exchange methods can also be used to add precious metals to the catalyst, for example, by repeatedly adding a diluted solution of a precious metal salt onto the catalyst support. After impregnation, spraying, or ion exchange, the catalyst containing the precious metal is dried, preferably in an air stream at an elevated temperature, preferably between 60°C and 200°C, for 0.5 h to 10 h. Optionally, calcination can also be performed at an elevated temperature, preferably between 200°C and 1000°C, for 10 min to 24 h.

[0064] The method according to the invention is particularly preferably carried out at a temperature of 250°C to 450°C, preferably 270°C to 400°C, and especially preferably 300°C to 370°C.

[0065] 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 very particularly preferably 1 bar to 10 bar.

[0066] The method according to the invention is preferably carried out in a reactor.

[0067] The reactors that can be used include all vessels that allow the addition of gas and in which the catalyst is in the form of a fixed bed, such as fixed-bed reactors, as well as those vessels in which the catalyst moves via reactant feed or agitation, such as entrained flow reactors, fluidized bed reactors, or batch reactors. The reactants can be added in gaseous or liquid form. In a preferred embodiment, the reactants are added in gaseous form to a fixed-bed reactor having a fixed catalyst bed. The method according to the invention can be carried out continuously or discontinuously.

[0068] The total amount of xylene ether (DTE)-based catalyst can be selected according to the needs of either continuous or discontinuous reactor operation. For continuous reactor operation, the amount is preferably 0.01-1000 g DTE / (g catalyst × h), particularly preferably 0.1-100 g DTE / (g catalyst × h). In the case of discontinuous reactor operation, the amount is preferably 0.1-10,000 g DTE / g catalyst.

[0069] The molar ratio of xylyl ether to water is preferably from 10:1 to 1:40, particularly preferably from 1:1 to 1:20, and very particularly preferably from 1:5 to 1:15.

[0070] The molar ratio of xylyl ether to hydrogen is preferably from 10:1 to 1:100, particularly preferably from 1:1 to 1:50, and very particularly preferably from 1:5 to 1:40.

[0071] In addition to xylene ether, water, and hydrogen, other gases may be added, preferably inert gases such as nitrogen or argon. It is preferable to add the same amount of standard liters (STL) as required. n Nitrogen or argon gas is used to achieve a ratio of 0-95% by volume, particularly preferably 0-40% by volume, based on the total volume.

[0072] The reactors that can be used include all containers that allow the addition of gas and in which the catalyst is in the form of a fixed bed, such as fixed-bed reactors, as well as those in which the catalyst moves via a reactant feed or agitation device, such as entrained flow reactors, fluidized bed reactors, or batch reactors. The reactants can be added in gaseous or liquid form. In a preferred embodiment, the reactants are added in gaseous form to a fixed-bed reactor having a fixed catalyst bed.

[0073] In this preferred embodiment of the invention in the form of hydrogenolysis, the following operations of the method performed in a continuous mode are preferred:

[0074] First, the catalyst is loaded into a fixed-bed reactor and heated to 300°C to 370°C. A mixture of xylene ether, water, and hydrogen, preheated to at least 250°C and containing no more than 40% by volume nitrogen, is added at a rate of 0.1g to 5g xylene ether per gram of catalyst per hour. (The molar ratio of xylene ether to water is in the range of 1:5 to 1:15, and the molar ratio of xylene ether to hydrogen is in the range of 1:5 to 1:40.) The resulting reaction product is collected because it contains cresol, which is formed in high yield.

[0075] The method according to the invention is illustrated based on the following examples, but is not limited thereto. Detailed Implementation

[0076] Example

[0077] The experiments described below were conducted in a steel tube with an open bottom plate serving as the reactor. Tables 1 and 2 report the type and manufacturer of the catalyst used in each experiment. A gaseous mixture of xylene ether, water, and nitrogen and / or hydrogen was introduced into the reactor at the ratios reported 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 using flame ionization. The results are listed in Tables 3 and 4.

[0078] Table 1: Catalysts Used (CAT)

[0079]

[0080]

[0081] MFI = SiO2 / Al2O3 zeolite; MOR = SiO2 / Al2O3 zeolite with a mordenite structure; I = of the present invention; C = comparative example.

[0082] In the catalysts containing noble metals (see Examples 8(I) to 15(I)), the noble metals are applied via dry impregnation / ion exchange, as explained below. The amounts and characteristics are clearly shown in Table 2.

[0083] For dry impregnation, the precious metal source dissolved in softened water as specified in Table 2 is added to the carrier. The amount of softened water corresponds to 98% of the absorption capacity of the corresponding carrier (see Table 2). Once the solution is completely absorbed, the impregnated carrier is dried in a stream of hot air at 120°C for 1 hour and (except in Example 16(C)) calcined in a static oven at 300°C–500°C for 12–16 hours. In the case of Example 16(C), dry impregnation and drying are repeated three times to ensure that the full amount of precious metal solution is applied.

[0084] For ion exchange, a noble metal-doped solution is added to a support in a glass tube with a glass frit bottom, and the solution is recirculated on the support for 24 hours. During this period, the support is always covered by the liquid.

[0085] Table 2: Amount and characteristics of catalysts containing precious metals

[0086]

[0087]

[0088] Table 3: Measurement results of hydrolysis and cracking of xylene ether at a temperature of 315℃, a pressure of 1 bar, and a catalyst volume of 68 mL. Flow rates were as follows: 15.2 g / h xylene ether and 13.8 g / h water, with a nitrogen content of 20% by volume.

[0089] C = comparative, I = invention

[0090] Compared with the comparative example (Example 1(C)), experiments 2-7 conducted with water according to the method of the present invention showed high conversion, high selectivity and high yield.

[0091] Table 4: Measurement results of xylene ether hydrogenation cracking at 315℃, 1 bar pressure, and 68 mL catalyst volume. Flow rates were as follows: 15.2 g / h xylene ether and 13.8 g / h water, with a hydrogen ratio of 20% by volume.

[0092]

[0093]

[0094] C = comparative experiment, I = invention

[0095] 1) Similar to Gao et al. Angew. Chem. Int. Ed. 2016, 55, 1474-1478 [Gao et al., Applied Chemistry, 2016, 55, pp. 1474-1478].

[0096] It was found that, compared with comparative examples 16(C) and 17(C), experiments 8(I)-13(I) and 15(I) on platinum-containing catalysts according to the method of the present invention, as well as experiments on rhodium-containing catalysts in the case of example 14(I), achieved high conversion based on xylyl ethers and high selectivity and high yield based on cresol and toluene.

[0097] Comparative Example 16(C) also shows that, compared with the catalysts of the present invention 8(I)-15(I) containing at least one platinum group element, the prior art uses nickel without the addition of a strong base, resulting in extremely low conversion and significantly lower selectivity and yield.

Claims

1. A method for producing cresol from xylyl ether and water in the presence of a catalyst, characterized in that, The catalyst used is from the MFI and MOR type zeolite group, and the catalyst contains at least 85% by weight of alumina and silica.

2. The method according to claim 1, characterized in that, The molar ratio of silicon to aluminum in the catalyst from the zeolite group is from 3:1 to 300:

1.

3. The method according to claim 1 or 2, characterized in that, The catalyst additionally contains at least one element from the platinum group metals Ru, Rh, Pd, Os, Ir, and Pt, and the reaction is carried out in the presence of hydrogen.

4. The method according to claim 3, characterized in that, Based on the total amount of the catalyst, the proportion of these elements from the platinum group metals is 0.1% to 10% by weight.

5. The method according to claim 3, characterized in that, The metals derived from the platinum group metals are platinum and / or rhodium.

6. The method according to claim 1 or 2, characterized in that, The method is carried out at temperatures ranging from 250°C to 450°C.

7. The method according to claim 1 or 2, characterized in that, The method is carried out at pressures ranging from 0.5 bar to 300 bar.

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