HK1030895B - Platinum metal-containing catalysts prepared in a sol-gel process and a process for producing diaryl carbonates - Google Patents

Description

Sol-gel process for preparing platinum group metal-containing catalyst and process for preparing diaryl carbonate

The invention relates to a mixed oxide catalyst containing platinum group metals prepared by a sol-gel process and its use in the preparation of diaryl carbonates by reacting aromatic hydroxy compounds with carbon monoxide and oxygen.

It is known that organic carbonates can be prepared by oxidation of aromatic hydroxy compounds with carbon monoxide in the presence of noble metal catalysts (DE-OS 2815512). The preferred noble metal is palladium. It is also possible to use a cocatalyst (e.g.manganese or cobalt salts), a base, a quaternary salt, different quinones or hydroquinones and a drying agent. The process may be carried out in a solvent, preferably dichloromethane.

In order to make the process economically viable, efficient recovery of the noble metal catalyst is a critical factor, in addition to the activity and selectivity of the catalyst. On the one hand, noble metal catalysts represent a large cost factor. The cost of replenishing lost precious metal catalyst is high. On the other hand, the product does not contain a trace amount of noble metal catalyst. The economical and efficient recovery of homogeneous catalysts during the oxidative carbonylation of aromatic hydroxy compounds to produce diaryl carbonates has not been reported. If a heterogeneous supported catalyst is used, the cost of separating the noble metal catalyst from the liquid reaction mixture, such as by filtration or centrifugation, is greatly reduced.

Noble metal catalysts containing 5% palladium on a carbon support are used in European patents A572980, -A503581 and-A614876. However, supported catalysts of this type have very low or even no conversion and are therefore not economically viable processes.

Japanese patent A01/165551 (cited in chemical literature 112: 76618j (1990)) describes the preparation of aryl carbonates using palladium or a palladium compound such as palladium acetylacetonate, and an iodide or an onium iodide of an alkali metal or alkaline earth metal such as tetrabutylammonium iodide and at least one zeolite.

Japanese patents-A04/257 and-A04/261142 both describe supported catalysts for the preparation of aryl carbonates, in which particles of silicon carbide are used as an example of a support for the supported catalyst in a distillation column. Although the severe reaction conditions (high pressure, high temperature) were employed in the examples, these catalysts produced only very low space-time yields. This low space-time yield makes it impossible to economically produce aryl carbonates using such supported catalysts.

European patent application A736324 describes the preparation of diaryl carbonates using heterogeneous catalysts containing a metal of the platinum group, preferably palladium, and a compound of a promoter metal, preferably selected from Mn, Cu, Co, Ce and Mo. When preparing the catalyst, the promoter metal acts as a support.

European patent A736325 describes the preparation of diaryl carbonates using heterogeneous catalysts comprising a platinum group metal, preferably palladium, supported on a metal oxide support containing various valences.

Although these supported catalysts achieve the production of aryl carbonates for the first time, the activity of such catalysts must be further increased from an economic standpoint.

It has now been found that higher catalyst activity is obtained if the catalyst is prepared by a sol-gel process, for example, using oxides of V, Mn, Ti, Cu, La, rare earth metals and mixtures thereof, and containing a metal of the platinum group.

The catalyst provided by the invention comprises

(i) Oxides of elements such as silicon, aluminum, titanium, zirconium, etc., or mixtures of oxides of these elements,

(ii) according to the new International Union of pure and applied chemistry nomenclature

Group 4, 5, 6, 7, 11, 12, 13, 14 in the system, iron group (atomic number)

Number 26 to 28) metal or rare earth metal (atomic number 58 to 71) oxide

And one or more promoter metal oxides and

(iii) one or more platinum group metals or one or more compounds of platinum group metals

Sub-numbers 44 to 46 and 77 and 78) relative to the total weight of the catalyst and

0.01 to 15 wt.% based on the platinum group metal.

(iii) forming a gel of one or more of the precursors of the components described in (i) and (ii) and the platinum group metal component (iii), ageing, drying and optionally calcining the gel to form the catalyst.

The gels of the present invention can be made by almost any known method. The known methods for preparing mixed oxide gels are preferably used. These processes comprise, for example, hydrolysis of one or more metal alkoxides and/or hydrolysable metal compounds under acidic, neutral or basic conditions in a suitable solvent at a temperature of from 0 ℃ to 200 ℃. Mixtures of different precursors of one or more elements may also be employed in this case.

Suitable precursors for silicon dioxide are silicon alkoxides, such as tetraethoxysilane, tetramethoxysilane.

Suitable precursors of aluminum oxide are lower alkoxides such as trimethoxyaluminum, triethoxyaluminum, tri-n-propoxyaluminum, tri-i-propoxyaluminum, tri-s-butoxyaluminum or tri-t-butoxyaluminum or aluminum alkoxides of chelating ligands such as ethyl dibutoxyaluminum-acetoacetate.

Suitable precursors for titanium oxide are tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium; suitable precursors of zirconium oxide are tetraethoxyzirconium, tetra-tert-butoxyzirconium, tetra-n-butoxyzirconium, tetra-isopropoxyzirconium. Suitable hydrolysable salts are titanium tetrachloride and organic salts are aluminium acetylacetonate, zirconium acetylacetonate or related mixed metal compounds and salts.

Suitable solvents are, for example, monohydric alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, polyhydric alcohols, such as ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, monofunctional or polyfunctional ketones, such as acetone, 1, 3-pentanedione (acetylacetone), cyclic or linear ethers with one to three oxygen atoms, such as tetrahydrofuran, dioxane, diethyl ether, ethylene glycol diethyl ether or diethylene glycol diethyl ether, ether alcohols, such as ethylene glycol monomethyl ether, nitriles, such as acetonitrile and benzonitrile, and amides, such as dimethylformamide. Alcohols, diketones and ether alcohols are preferred. It is obvious that mixed solvents can also be used.

The solvent is used in such an amount that the molar ratio of alkoxide to solvent is from 1: 0.2 to 1: 100.

Partially alkylated precursor R¹ _XM(OR²)_YAlso useful in the process of the invention, wherein M represents the element recited in (i), (x + y) is the valence of the element, R¹And R²Independently of one another, represents an alkyl, aralkyl or aryl radical having 1 to 20 carbon atoms. The following will be illustrated by way of example: methyltriethoxysilane, ethyltriethoxysilane.

Promoter compounds which may be mentioned are compounds of one or more elements of groups 4, 5, 6, 7, 11, 12, 13, 14, the iron group (atomic numbers 26 to 28) or the rare-earth metal (atomic numbers 58 to 71) in the periodic system of the elements (new international union of pure and applied chemistry), the components mentioned in (ii) being incorporated into the catalyst, preferably Mn, Cu, Co, V, Nb, W, Zn, Ce, Mo, in particular Mn, Co, Cu, Mo, Ce, in particular Mn and/or Ce, in amounts of from 0.1% to 99.9%, preferably from 0.1% to 40%, in particular from 0.5% to 20%, relative to the total number of moles of the components mentioned (i) and (ii).

Suitable precursors of the promoter metals are essentially known, and the following are examples which may be employed: inorganic salts such as halides, oxides, nitrates, sulfates, carboxylates, monofunctional or polyfunctional organic C₂To C₁₅Salts of carboxylic acids, such as acetates, cyclohexanebutyrates, diketonates, such as acetylacetonates, ethylhexanoates, alkoxides, such as methoxides, ethoxides and isopropoxides, and coordination compounds containing, for example, carbon monoxide, alkenes, amines, nitriles, phosphines and halides, and mixed salts thereof.

Formula [ L ]_mM-(OR)₂-M′L_n′]Also known and described are multimetal alkoxides such as Mehrotra et al at mat.res.soc.symp.proc, 121(1988) 81; bradley et al in "metal alkoxides", Academic Press, NY (1978); k.g. caulton et al in chem.rev.90(1990) 969.

Examples of compounds containing organic ligands are: cerium (IV) isopropoxide, cerium (IV) methoxyethoxide, cerium (III) acetylacetonate, methoxycobalt carbonyl, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, manganese (II) ethoxide, manganese (II) acetylacetonate, manganese (III) acetylacetonate, copper (II) 2-ethylhexanoate, copper (II) ethoxide, copper (II) ethylacetoacetate, copper (II) acetylacetonate, niobium (V) ethoxide, molybdenum (V) ethoxide (decaethoxydimolybdenum), molybdenum (VI) oxide-diacetoneate, vanadium (IV) oxide-diacetoneate (vanadium acetylacetonate), vanadium (III) acetylacetonate, vanadium triisopropoxide, vanadium tri-n-propoxide, tungsten (VI) ethoxide, tungsten (V) ethoxide, tungsten (VI) phenoxide, zinc (II) acetylacetonate.

European patent A736324 describes that suitable platinum group metal compounds are platinum group metal compounds and coordination compounds containing platinum group metals. In the example presented, palladium is presented as the platinum group metal, but other platinum group metals such as Pt, Ir, Ru or Rh are also suitable. Pd and Rh are preferred, especially Pd. Examples of suitable platinum group metal compounds are: li₂(PdCl₄)，Na₂(PdCl₄)，K₂(PdCl₄)，(NBu₄)₂(PdCl₄)，Na₂(PdBr₄)，K₂(PdBr₄)，(NBu₄)₂(PdBr₄) (wherein Bu ═ n-butyl), platinum group metal nitrates, acetates, propionates, butyrates, oxalates, carbonates, oxides, hydroxides, acetylacetonates and other compounds known to those skilled in the art. The olefin-containing platinum group metal complex being a [ allylpalladium chloride ] dimer [ C₃H₅PdCl〕₂1, 5-cyclooctadienepalladium dichloride C₈H₅PdCl₂(ii) a The phosphine-containing platinum group metal complex is 1, 2-bis [ (diphenylphosphino) ethane ] palladium dichloride Pd [ P (C)₆H₅)₂PCH₂CH₂P(C₆H₅)₂]Cl₂Bis (triphenylphosphine) palladium dichloride Pd [ P (C)₆H₅)₃]₂Cl₂(ii) a An example of an amine-containing platinum group metal complex is Pd (NH) palladium dibromide₃)₂Br₂Diamino coordinated palladium dichloride Pd (NH)₃)₂Cl₂Tetraammine palladium [ Pd (NH) ] tetrachloropalladate₃)₄][PdCl₄](ii) a Nitrile-containing platinum groupThe metal complex is bis (acetonitrile) palladium dichloride Pd (CH)₃CN)₂Cl₂Bis (benzonitrile) palladium dichloride Pd (C)₆H₅CN)₂Cl₂(ii) a The platinum group metal complex containing carbon monoxide is tetrabutylammonium tribromocarbonyl palladium (NBu)₄)Pd(CO)Br₃(wherein Bu ═ n-butyl) and tetrabutylammonium trichlorocarbonylpalladate (NBu)₄)Pd(CO)Cl₃(wherein Bu ═ n-butyl).

The catalyst of the present invention may be prepared in one or more steps. In this case, the platinum group metal may be added to the mixture immediately or over a period of time when the mixed oxide is prepared. It is also possible to use the procedure in which part of the platinum group metal is added during the sol-gel process and the remainder is subsequently added to the mixed oxide.

In preparing the catalyst of the present invention, the precursor solutions of (i) and (ii) can be prepared by hydrolysis in a conventional manner using 1 to 20, preferably 1.5 to 10, molar equivalents of water based on the total molar amount of the compounds of (i) and (ii) in a suitable solvent. The water may be added in one or several portions, either neat or mixed with other solvents, or may contain the precursor of (ii) or a platinum group metal compound dissolved therein.

According to the invention, one or more compounds of the platinum group metals (atomic numbers 44 to 46 and 77 and 78) can be added to the catalyst at various times, in an amount of from 0.01 to 20% by weight, preferably from 0.05 to 10% by weight, based on the total weight of the platinum group metal, based on the total weight of the final catalyst.

In another preferred method of catalyst preparation, one or more platinum group metal compounds are added to a mixture of a solution of the precursor of (i) (ii), solvent, water and the optional acid or base described above in a suitable solvent, either before or during gelling.

The platinum group metal compound precursor which is insoluble in the solvent can be made into a soluble compound in situ by using a complexing agent or further using a ligand. In another preferred embodiment, the platinum group metal compound is dissolved in the solvent used and added in this form. In another preferred embodiment, the platinum group metal compound is added to the prehydrolyzed mixture as a solid or in solution.

During the hydrolysis, the acid or base is added in an amount of 0.1 to 200 mol% based on the total moles of the compounds (i) and (ii).

Suitable acids are, for example, hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid or higher carboxylic acids having 3 to 8 carbon atoms. Di-and tri-carboxylic acids containing up to 8 carbon atoms are also suitable. Suitable bases are ammonia, quaternary ammonium bases, NR₄OH, where R, independently of one another, can be alkyl, aryl or alkylaryl having from 1 to 15 carbon atoms, such as tetramethyl-, tetraethyl-, tetrapropyl-, tetrabutyl-, tetrapentyl-or tetraphenylammonium bases, or organic nitrogen bases, such as amines, pyridines, guanidines. Preferred bases are ammonia and quaternary ammonium bases. The acids and bases used may be pure substances, anhydrous solutions or aqueous solutions.

When the individual components are added, the mixture can be homogenized thoroughly using mixing equipment such as stirrers or nozzles.

If several compounds (i) (ii) are hydrolysed, their reactivity can be mutually adjusted using known techniques. Some examples may be mentioned: pre-hydrolysis of a compound, chemical modification of a compound with a chelating agent, hydrolysis with different alkoxide groups in the compound and at different temperatures, as described by d.a. ward and e.i. ko (ind.eng.chem.res.34(1995) 421).

Another suitable method of the invention for preparing mixtures from the precursors of (i) and (ii) is the gelation of inorganic precursors in aqueous systems, for example the preparation of silica gels by neutralizing alkali metal silicates with strong acids. Additional steps may be required such as washing the gel to remove salts generated from the mixture. In the step described herein, the precursor of (ii) or the platinum-group metal-containing compound (iii) may be added to one of the components, for example, before the alkali metal silicate and the acid are mixed.

After gelation, it is advantageous to age the gel at 20 to 100 ℃, preferably 20 to 80 ℃ for at least 10 minutes. The upper limit of the aging time is limited only by economic factors and can be several weeks. The preferred time is 1 hour to two weeks. Aging can also be carried out in stages at different temperatures or with a slow change in temperature over time.

The gel was aged and dried. The gel may be dried in different ways, depending on the method of preparation, in which connection drying affects the internal surface and pore volume of the material.

Drying can be carried out in air, under vacuum or in a stream of air. Suitable gases for drying the gel in the gas stream are nitrogen, oxygen, carbon dioxide or noble gases or mixtures of any of said gases, preferably air. Gaseous hydrocarbons, such as alkanes, e.g., methane, ethane, propane, butane, alkenes, e.g., ethylene, propylene, butenes, butadiene, and alkynes, e.g., acetylene, propyne, and the like, may take any composition. The drying is carried out at from 0 to 300 ℃, preferably from 20 to 250 ℃, in particular from 20 to 150 ℃. The drying time depends on the porosity of the gel and the solvent used. Usually several hours, such as 0.5 to 50 hours, preferably 1 to 40 hours, especially 1 to 30 hours.

Another preferred drying method is under supercritical conditions, as described in g.m. pajonk (Applied Catalysis 72(1992)217) and Dutoit et al (j.cat.161 (1996)651), and this results in the formation of a gel with very high porosity. Such as carbon dioxide (T)_{Critical point of}＝31℃，P_{Critical point of}73bar) or alcohols above the critical point (e.g. ethanol T)_{Critical point of}＝243℃，P_{Critical point of}63bar) may be used. The drying may be carried out batchwise, continuously or partly continuously, and optionally with another inert gas.

Sometimes, the reduction of the platinum group metal occurs during supercritical drying with an alcohol, which generally has an adverse effect on the activity of the catalyst of the present invention. In this case, it is advisable to dry the catalyst before oxidation, for example by calcination at from 200 to 800 ℃ under a gas stream containing oxygen, air, halogen or hydrogen halide.

Further drying processes, in particular for drying gels prepared in aqueous systems, are extraction and azeotropic drying as described in U.S. Pat. No. 3, 3887494, U.S. Pat. No. 3, 3900457, U.S. Pat. No. 3, 4169926, U.S. Pat. No. 3, 4152503, U.S. Pat. No. 3, 4436883 and U.S. Pat. No. 4081407.

After drying, the dried mixed oxide can be calcined. Calcination may be carried out in air, under vacuum, or in a gas stream. Suitable gases for calcining the mixed oxides in a gas stream are nitrogen, oxygen, carbon dioxide or noble gases and any mixture of the mentioned gases, preferably air. The calcination is carried out at from 100 to 800 ℃, preferably from 100 to 700 ℃, in particular from 100 to 600 ℃. It may be beneficial to change the composition of the gas from time to time or abruptly or continuously. The calcination time is usually several hours, for example from 0.5 to 50 hours, preferably from 1 to 40 hours, in particular from 1 to 30 hours.

The mixed oxides of the invention can also be applied as a layer on other catalyst supports. Suitable support materials for applying a layer of the metal mixed oxide can be any catalyst support material customary in industry, such as carbon in various forms, oxides, carbides or salts of the elements. Examples of carbon-containing supports are coke, graphite, carbon black or activated carbon. An example of an elemental oxide catalyst support is SiO₂(natural or synthetic silica, quartz), various modifications of Al₂O₃(α, γ, δ, η, θ), alumina, natural and synthetic aluminosilicates (zeolites), TiO₂(rutile, anatase), ZrO₂Or ZnO. The carbide and salt of the element being SiC, AlPO₄，BaSO₄，CaCO₃And the like. They can be used in a chemically homogeneous pure substance or as a mixture. According to the invention, powdery or granular material, even monolithic masses, are suitable.

The present invention also provides a process for preparing organic carbonates by reacting an aromatic hydroxy compound with carbon monoxide and oxygen in the presence of the catalyst of the present invention, a quaternary ammonium salt or phosphonium salt and a base.

The organic carbonates prepared by the process of the present invention can be represented by the following formula

R-O-CO-O-R (I) wherein R represents substituted or unsubstituted C₆-C₁₂Aryl, preferably a substituted or unsubstituted phenyl, especially an unsubstituted phenyl.

The aromatic hydroxy compound useful in the present invention can be represented by the following formula

R-O-H (II) wherein R has the same meaning as above. Examples of aromatic hydroxy compounds which can be reacted with the supported catalysts of the invention are phenol, o-, m-or p-cresol, o-, m-or p-chlorophenol, o-, m-, or p-ethylphenol, o-, m-, or p-propylphenol, o-, m-, p-methoxyphenol, 2, 6-dimethylphenol, 2, 4-dimethylphenol, 3, 4-dimethylphenol, 1-naphthol, 2-naphthol or bisphenol-A, preferably phenol. The aromatic hydroxy compound may be substituted by one or two substituents, such as C₁-C₄Alkyl radical, a C₁-C₄Alkoxy, fluoro, chloro or bromo.

The catalyst used in the present invention may be in the form of a powder, a molded product or a monolith, preferably a powder or a molded product, and the catalyst may be separated from the reaction mixture by filtration, sedimentation or centrifugation.

Different methods can be selected for preparing aryl carbonates using the supported catalysts of the present invention. One solution is to use a batch process. On a continuously operated fixed-bed catalyst, either in a countercurrent or cocurrent system or in the trickle phase, loadings of from 0.01 to 20 g of aromatic hydroxy compound per gram of supported catalyst per hour, preferably from 0.05 to 10 g of aromatic hydroxy compound per gram of supported catalyst per hour, in particular from 0.1 to 5 g of aromatic hydroxy compound per gram of supported catalyst per hour, can be employed. In batch experiments, when the charge was constant, the supported catalyst could be reused without purification. In continuous operation, the supported catalyst can remain in the reactor for a long time. The supported catalysts according to the invention are preferably used in a single reactor or in a series of reactors operating continuously.

If the supported catalyst used is a powder, the stirred vessel used for mixing the reaction components is equipped with a stirrer for this purpose. When the supported catalyst powder suspension is used in a stirred vessel or bubble column, the amount of supported catalyst powder used is from 0.001 to 50% by weight, preferably from 0.01 to 20% by weight, in particular from 0.1 to 10% by weight, based on the amount of aromatic hydroxy compound used. In a particularly preferred embodiment, the supported heterogeneous catalyst used is a molded product and is fixed in a stirred vessel, a bubble column, a trickle phase reactor or a cascade reactor, wherein the cascade reactor can also be a different type of reactor.

When the catalyst constitutes a fixed bed in the reactor, the catalyst is preferably used in the form of a molded product such as a sphere, a column, a small rod, a hollow cylinder, a ring or the like. If desired, the catalyst may be modified by extrusion, to form tablets, and optionally by addition of catalyst supports or binders such as SiO₂Or Al₂O₃And then baked. The preparation and further processing of the catalysts of the invention are generally known to the person skilled in the art and are part of the prior art.

Any organic or inorganic base or mixtures thereof may be employed in the process of the present invention. Inorganic bases which may be mentioned, without restricting the process according to the invention, are alkali metal hydroxides and carbonates, carboxylates or other salts of weak acids, alkali metal salts of aromatic hydroxy compounds of the formula (II), such as alkali metal phenolates. Obviously, it is also possible to use hydrates of alkali phenolates in the process of the invention. An example of such a hydrate, which may be mentioned, but does not limit the process of the invention, is sodium phenolate trihydrate. The amount of water added is preferably up to 5 moles of water per mole of base. The addition of an excess of water results in a low conversion and decomposition of the carbonate formed. Organic bases which may be mentioned, but which do not limit the process according to the invention, have the formula C₆-C₁₀Aryl radical, C₇-C₁₂Aralkyl and/or C₁-C₂₀Tertiary amines with alkyl as organic radical or pyridine bases or hydrogenated pyridine bases, such as triethylamine, tripropylamine, tributylamine, trioctylamine, benzyldimethylamine, dioctylbenzylamine, dimethylphenylamine, 1-dimethylamino-2-phenylpropane, pyridine, N-methyl-piperidine, 1, 2, 2, 6, 6-pentamethylpiperidine. Preferably, an alkali metal salt of an aromatic hydroxy compound is used as the base, and in particular the aromatic hydroxy compound is also reacted to form an alkali metal salt of an organic carbonate. The alkali metal salt can be lithium, sodium, potassium, rubidium, cesium salt. Preference is given to using lithium, sodium and potassium phenolates, in particular sodium phenolate.

The solid base of the pure compound or a melt thereof may be added to the reaction mixture. In a further embodiment of the invention, the base is added to the reaction mixture as a solution which contains from 0.1 to 80% by weight, preferably from 0.5 to 65% by weight, in particular from 1 to 50% by weight, of base. Optionally, a solvent such as an alcohol or phenol, which may be reacted or simply an inert solvent. The following are examples that may be used as reaction media. These solvents may be used alone or in admixture with each other. In one embodiment of the process of the present invention, the base is dissolved in phenol which is melted and diluted with a solvent. The base is preferably dissolved in the molten aromatic hydroxy compound, particularly the molten aromatic hydroxy compound intended to react to form the organic carbonate. In particular, the base is dissolved in phenol. The amount of base added does not depend on the stoichiometry. The ratio of platinum group metal, e.g. palladium, to base is from 0.1 to 500, preferably from 0.3 to 200, in particular from 0.9 to 130, equivalents of base per mole of platinum group metal, e.g. palladium.

The process of the invention preferably does not employ a solvent. It is clear that inert solvents can also be used. Solvents which may be mentioned are dimethylacetamide, N-methylpyrrolidone, dioxane, tert-butanol, cumyl alcohol, isoamyl alcohol, methylurea, diethylene glycol, halogenated hydrocarbons (e.g.chlorobenzene or dichlorobenzene) and ethers.

Quaternary salts used in the context of the present invention can be ammonium and phosphonium salts with organic groups. Is suitable forThe compounds of the process of the invention are compounds containing an organic group C₆-C₁₀Aryl radical, C₇-C₁₂Aralkyl and/or C₁-C₂₀The anion is a halide, tetrafluoroborate or hexafluorophosphate. Preferred organic radicals of the ammonium salts for use in the present invention are C₆-C₁₀Aryl radical, C₇-C₁₂Aralkyl and/or C₁-C₂₀Alkyl, halo is anionic, especially tetrabutylammonium bromide. The quaternary salts are used in amounts of 0.1 to 50% by weight, based on the weight of the reaction mixture. Preferred amounts are from 0.5 to 15% by weight, in particular from 1 to 5% by weight.

The process of the invention, preferably without solvent, is carried out at a temperature of from 30 to 200 ℃, preferably from 30 to 150 ℃, in particular from 40 to 120 ℃, and at a pressure of from 1 to 100 bar, preferably from 2 to 50 bar, in particular from 5 to 25 bar.

Examples of the invention

Comparative example 1(according to European patent-A736324)

Preparing a powdery manganese oxide carrier:

85 g of sodium hydrochloride (2.125 mol) are dissolved in 200ml of water and added dropwise to a solution of 126 g of manganese (II) chloride (1 mol) in 500ml of water. The resulting precipitate was filtered under reduced pressure, washed with water and dried. Then, the mixture was calcined at 300 ℃ for 3 hours and 500 ℃ for 2 hours.

Covering the powdery manganese oxide with palladium:

300ml of an aqueous solution of 50 g of sodium tetrachloropalladium (II) hydrate containing 15% palladium was added to a slurry of 292.5 g of manganese dioxide powder in 1500ml of water at room temperature. The mixture is made alkaline with dilute caustic soda. The suspension was filtered under vacuum and dried at 100 ℃. Heterogeneous catalyst in MnO₂The support contained 2.5% palladium, calculated as metal.

Preparing diphenyl carbonate by using a supported catalyst:

8.31 g of tetrabutylammonium bromide and 0.77 g of manganese (II) acetylacetonate are dissolved in 450 g of phenol and introduced into an autoclave equipped with a gas dispersion stirrer, condenser and cold trap. Then 4 g of supported catalyst and 2.21 g of sodium phenate solution in 50 g of phenol were added. A gas mixture of carbon monoxide and oxygen (95 ═ 5% by volume) was introduced and the pressure was adjusted to 14 bar. The amount of gas mixture was adjusted to 350 normal liters/hour. Samples were taken from the reaction well by gas chromatography every hour. The analysis showed 9.9% diphenyl carbonate after 1 hour, 15.2% diphenyl carbonate after 2 hours and 18.2% diphenyl carbonate after 3 hours in the reaction mixture. In the cold trap 11.8 g of a phenol/water mixture were condensed.

Comparative example 2(according to European patent-A736325)

Covering the powdered titanium dioxide with palladium and manganese:

300ml of an aqueous solution of 40.5 g (0.16 mol) of manganese (II) nitrate tetrahydrate in 1500ml of water was added to a slurry of 283.5 g of titanium oxide powder (Norton) in 1500ml of water at room temperature. The mixture was made alkaline with dilute caustic soda. The suspension was filtered under vacuum, washed with water, dried at 100 ℃ and calcined at 300 ℃ for 3 hours. The manganese-doped support was slurried in 1500ml of water, and then 300ml of a solution containing 50 g of sodium tetrachloropalladium (II) hydrate containing 15% palladium was added. The mixture is made alkaline with dilute caustic soda. The suspension was filtered under vacuum, washed and dried at 100 ℃.

The catalyst contained 2.5% palladium and 3% manganese, each calculated as metal.

Preparing diphenyl carbonate by using a supported catalyst:

the supported catalyst was used for the production of diphenyl carbonate in the same manner as in comparative example 1. The analysis showed 9.6% diphenyl carbonate after 1 hour, 16.1% diphenyl carbonate after 2 hours and 21.0% diphenyl carbonate after 3 hours in the reaction mixture. In the cold trap a 12.3 phenol/water mixture was condensed.

Example 1

Preparation of a Si/Mn/Pd cogel

100ml of tetraethoxysilane and 200ml of a solution containing 6.9 g of manganese (III) acetylacetonate and 1.24 g of palladium (II) acetylacetonate are mixed and then a 25.7% strength aqueous hydrochloric acid solution is added with stirring and over 18 minutes. The mixture was allowed to stand at room temperature for 6 days, and then dried in a vacuum oven at 40 ℃ for 2 days. The solid obtained was ground and calcined in an air stream at 300 ℃ for 3 hours.

The catalyst contained 1.5% palladium and 3.0% manganese, each calculated as metal.

Preparing diphenyl carbonate by using a supported catalyst:

the supported catalyst was used for the preparation of diphenyl carbonate in the same manner as in comparative example 1 except that 6.7 g of the catalyst was used. The analysis showed that 9.2% diphenyl carbonate was present in the reaction mixture after 1 hour, 17.8% diphenyl carbonate was present after 2 hours, and 24.4% diphenyl carbonate was present after 3 hours. In the cold trap 15.0 g of phenol/water mixture was condensed.

Example 2

Preparation of a Si/Mn/Pd cogel

The catalyst was prepared in the same manner as in example 1, except that 13.8 g of manganese (III) acetylacetonate, 2.48 g of palladium (II) acetylacetonate and 300ml of ethanol were used.

The catalyst contained 3.0% palladium and 6.0% manganese, each calculated as metal.

Preparing diphenyl carbonate by using a supported catalyst:

the supported catalyst was used to prepare diphenyl carbonate in the same manner as in example 1, except that 3.3 g of the catalyst was used. The analysis showed 11.6% diphenyl carbonate after 1 hour, 21.4% diphenyl carbonate after 2 hours and 27.0% diphenyl carbonate after 3 hours in the reaction mixture. 16.5 g of a phenol/water mixture was condensed in the cold trap.

Example 3

Preparation of a Si/Mn/Pd cogel

100ml of tetraethoxysilane and 200ml of an ethanolic solution containing 6.9 g of manganese (III) acetylacetonate are mixed and, over 18 minutes and with stirring, 1.24 g of potassium tetrachloropalladate in 36ml of 25.7% strength aqueous hydrogen chloride are added. The mixture was left at 40 ℃ for 3 days and then dried in a vacuum oven at 40 ℃ for two days. The solid obtained was ground and calcined in an air stream at 300 ℃ for 3 hours.

The catalyst contained 1.5% palladium and 6% manganese, each calculated as metal.

Preparing diphenyl carbonate by using a supported catalyst:

the supported catalyst was used for the preparation of diphenyl carbonate in the same manner as in example 1. The analysis showed that 11.4% diphenyl carbonate was present in the reaction mixture after 1 hour, 19.2% diphenyl carbonate after 2 hours and 24.2% diphenyl carbonate after 3 hours. In the cold trap 13.9 g of a phenol/water mixture was condensed.

Example 4

Preparation of a Si/Mn/Pd cogel

The preparation of the catalyst was carried out as described in example 1, but 17ml of glacial acetic acid and 30ml of water were used for the hydrolysis instead of hydrochloric acid.

The catalyst contained 1.5% palladium and 6% manganese, each calculated as metal.

Preparing diphenyl carbonate by using a supported catalyst:

the supported catalyst was used for the preparation of diphenyl carbonate in the same manner as in example 1. The analysis showed that 13.4% diphenyl carbonate was present in the reaction mixture after 1 hour, 19.6% diphenyl carbonate was present after 2 hours, and 24.6% diphenyl carbonate was present after 3 hours. In the cold trap 15.1 g of a phenol/water mixture was condensed.

Claims (3)

1. A catalyst comprising the following components:

(i) oxides of the elements silicon, aluminum, titanium, zirconium or mixtures of these elements,

(ii) groups 4, 5, 6, 7, 11, 12, 13, 14, iron (atomic number 26)

To 28) or of rare earth metals (atomic number 58 to 71)

A compound of, and

(iii) of platinum group metals or platinum group metals (atomic numbers 44 to 46 and 77 and 78)

Compound in a quantity of 0.01% by weight relative to the total weight of the catalyst and calculated as platinum group metal

To a content of 15% by weight,

the preparation method comprises preparing a gel from the suitable precursors of the components (i) and (ii) and the platinum group metal component (iii), aging, and drying the gel to obtain the catalyst.

2. The catalyst of claim 1, characterized in that the method of preparing the catalyst further comprises calcining the gel after drying.

3. A process for the preparation of an organic carbonate comprising reacting an aromatic hydroxy compound with carbon monoxide and oxygen in the presence of a catalyst according to claim 1, a quaternary ammonium or quaternary phosphonium salt having an organic group C and a base₆-C₁₀Aryl radical, C₇-C₁₂Aralkyl and/or C₁-C₂₀The anion is a halide, tetrafluoroborate or hexafluorophosphate.