DE4414330A1 - Cyclic olefin prodn. by hydrogenating aromatic hydrocarbons - Google Patents

Abstract

Prodn. of cyclic olefins is effected by partial hydrogenation of aromatic hydrocarbons in the presence of water, a Ru catalyst at least one promoter and at least one additive. The catalyst is prepd. by reacting a Ru cpd. with a metal less noble than Ru in the presence of a solvent.

Description

The present invention relates to a simple and effective method for Production of cyclic olefins by partial hydrogenation of aromatic Hydrocarbons using special ruthenium catalysts.

Cyclic olefins are important starting materials for the production of a Series of organic chemicals, e.g. B. for the production of cyclohexanol, Cyclohexene oxide, phenol and adipic acid.

It is known that cyclic olefins by partial hydrogenation of aro can produce hydrocarbons with hydrogen, in the presence of Zinc compounds, metal oxides, hydroxides or oxide hydrates, water and a hydrogenation catalyst, the metallic ruthenium with a medium Contains crystallite size of 200 Å or less (see EP-A 220 525). The production The metallic ruthenium is made by reducing ruthenium compound with hydrogen, formaldehyde, borohydride or hydrazine. Good hydrogenation results are only obtained with catalysts that are initially soluble Ruthenium compounds, e.g. B. RuCl₃ × 3H₂O, in a strongly akali medium poorly soluble ruthenium hydroxide transferred and this z. B. at 150 ° C and 50 bar reduced to metal with hydrogen for 12 hours.

This catalyst production is cumbersome and complex. So are for that Working in a strongly alkaline environment, special materials, large amounts of alkali and special measures for disposal are required, and the reduction requires lots of energy, time and pressure equipment.

It was therefore the task of catalysts for the production of cyclic To provide olefins that are more easily accessible.

There has now been a process for the preparation of cyclic olefins by partial Hydrogenation of aromatic hydrocarbons in the presence of water optionally doped ruthenium as a catalyst, at least one promoter and optionally found one or more additives, characterized thereby is that the ruthenium catalyst has been obtained in the presence of a Solvent by reacting ruthenium compounds with a metal, which is less noble than ruthenium.

In the inventive method, for. B. mono- or polycyclic, unsub substituted or substituted aromatic hydrocarbons can be used. These can e.g. B. contain 6 to 18 carbon atoms. Come as substituents e.g. B. up to 5 alkyl groups with z. B. 1 to 8 carbon atoms in question. Preferred aro Matic hydrocarbons are benzene, naphthalene and their derivatives with 1 to 3 methyl or ethyl substituents such as toluene, xylene and ethylbenzene. Especially benzene is preferably used in the process according to the invention.

In general, one obtains from the aromatic hydrocarbons used the corresponding cyclic monoolefins, e.g. B. from benzene and benzene Derivatives cyclohexenes and from naphthalene and naphthalene derivatives, di-, tetra- and Octahydronaphthalenes. Unsubstituted is particularly preferred according to the invention Cyclohexene manufactured.

In the process according to the invention, water can, for. B. in an amount of 0.01 to 100 times, preferably from 0.5 to 20 times, based on the weight of the aromatic hydrocarbon used.

The ruthenium catalyst to be used according to the invention can be any Ruthenium compounds are prepared, for example from salts, oxides, Hydroxides and complex compounds of ruthenium. Preferred ruthenium  Compounds for this purpose are halides, sulfates, nitrates, hydroxides, Oxides and salts of carboxylic acids, particularly preferred are ruthenium chloride, bromide, nitrate, sulfate and acetate.

As a solvent in the implementation of the ruthenium compounds such. B. Water, alcohols, amines, polar organic solvents (e.g. ethers, ketones, Carbonic acid and carboxylic acid esters, sulfoxides, amides and lactones), hydrocarbons substances and mixtures of such solvents in question. Water is preferred, Alcohols, ketones, ethers and their mixtures, especially water, C₁-C₄- Alcohols and their mixtures.

The solvent can optionally contain additions of acids, preferably inorganic acids, especially hydrohalic acids. Per part by weight Solvents can e.g. B. 0.001 to 4 parts by weight of acid (calculated as anhydrous Acid) can be added. Sufficient acid is preferably added that the Ge mix a pH value of ruthenium compound, solvent and acid Range 0 to 4.

It is not absolutely necessary that before adding the metal that is less noble than Ruthenium is, the ruthenium compound used completely in dissolved form is present, but this is preferred. The concentration of the ruthenium used Compound is preferably between 0.001% by weight and the saturation con concentration in the respective solvent. This con is particularly preferably concentration in the range 0.01 wt .-% to 20 wt .-%, in particular in the range 0.1 to 5% by weight. The specialist has no difficulty routinely combi nations of ruthenium compounds, solvents and optionally acid add together with which the desired concentration let conditions be realized.

As metals that are less noble than ruthenium, z. B. the metals of I. to V. Main group of the periodic table of the elements in question as well as zinc, iron, cobalt and nickel. Alkali and alkaline earth metals as well as zinc, iron and  Aluminum, calcium, magnesium and zinc are particularly preferred. Should with Alkali metals are worked in the presence of water, so are special To take precautions.

The molar ratio of ruthenium compound to base metal can for example range from 1: 0.1 to 100. This ratio is preferably 1: 1 until 10.

The less noble metals can e.g. B. in the form of granules, powders, chips, Pieces or wires can be used.

The pressures and temperatures in the manufacture of the ruthenium catalyst are without special concern and can be varied within wide limits, for example between -50 and + 300 ° C and between 0.1 and 100 bar. From practical Er Weighing is often carried out at 20 to 100 ° C and 0.8 to 1.2 bar, preferably at normal pressure.

A preferred embodiment of the preparation of the ruthenium catalyst consists in that the ruthenium compounds are dissolved in an acid submitted mixed solvent and then the base metal in portions inflicts. If necessary, you can also use the base metal together with the Submit solvent and the ruthenium compound dissolved in portions or add undissolved form. There are a number of other versions Forms for the production of the ruthenium catalyst possible.

During the reaction, the more noble metal is added with increasing progress the pH value, for example from 0 to 14, preferably from 2 to 10. Stark alkaline pH values as required by the state of the art can be avoided, nevertheless effective catalysts are obtained. If necessary, one can work in the additional presence of buffer salts, e.g. B. in the presence of oxalates, tartrates, phthalates, phosphates, citrates, borates or calcium hydroxide. You can also check the pH values before, during and after the reaction, also by varying the ruthenium used  Compound and / or the solvent and / or the optionally used influencing modifiers.

As a doping for the ruthenium catalyst, which may be before, during or after the reaction of the ruthenium compound with a less noble metal than Ruthenium, but before the hydrogenation of the aromatic hydrocarbon is added that the ruthenium catalyst and the doping with each other are connected (chemically or physically) or at least stick together, come z. B. salts, oxides, hydroxides and / or complex compounds of Metals of III. to V. main and / or I. to VIII. subgroups of Periodic table of the elements in question, preferably of aluminum, gallium, Indium, tin, lead, titanium, zircon, vanadium, niobium, chromium, molybdenum, tungsten, Manganese, iron, cobalt, nickel, copper, silver, gold, zinc, cadmium, mercury and / or the lanthanides. Sulfates and basic sulfates are particularly preferred of the metals mentioned, especially zinc sulfate and / or basic zinc sulfate. Such Doping can e.g. B. be used in such quantities that the finished Ruthenium catalyst contains up to 50 wt .-% doping, each based on the metals. The finished ruthenium catalyst preferably contains 0.001 to 30% by weight of such doping, based on the metals. The endowments can with an uned during the implementation of the ruthenium compound ler metal and / or before or during the partial hydrogenation of aromatic Change hydrocarbons, e.g. B. by formation of poorly soluble compounds or (if necessary partial) conversion to the metallic state.

The term promoters is understood to mean materials that are in the reaction mixture for the partial hydrogenation of aromatic hydrocarbons are, but are neither connected to the catalyst nor adhere to it. she increase the yield of cyclic olefins. As promoters come for example wise in question: compounds of zinc, of metals from I. to VI. Subgroups of the periodic table of the elements as well as of manganese, iron, cobalt, nickel, aluminum minium, gallium, indium, germanium, tin, lead and the rare earth metals such as Cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium and dyspro sium. Compounds of zinc, chromium, manganese, molybdenum, iron,  Cobalt, nickel, copper, silver, cadmium, gallium and indium, particularly preferred are compounds of zinc, iron, cobalt, nickel, silver, cadmium, gallium and Compounds of zinc are indium and very particularly preferred. As a verb For example, salts or hydroxides are suitable. Those are preferred Sulfates of the metals mentioned and very particularly preferred is zinc sulfate and / or basic zinc sulfate. Several promoters can also be present.

The promoters need not be completely dissolved during the reaction. Your concentration in the aqueous phase of the reaction mixture for production Cyclic olefins are preferably between 0.001% by weight and the concentration tration of the saturated solution. This con is particularly preferably concentration of the promoters between 0.01 and 40 wt .-%, in particular between 0.1 and 30% by weight.

The term additives is understood to mean materials that are used during manufacture Position of cyclic olefins in the reaction mixture in particulate form. Examples of possible additives are: oxides, hydroxides and oxide hydrates of zircon, hafnium, titanium, niobium, tantalum, chromium, iron, cobalt, aluminum, Gallium, silicon, vanadium, molybdenum, tungsten, manganese, nickel, copper, Scandium, yttrium, lanthanum and actinium, borides for example of aluminum, Silicon, lanthanum, titanium, zircon, hafnium, vanadium, niobium, tantalum, chrome, Tungsten, molybdenum, cobalt and nickel, carbides for example from boron, aluminum minium, silicon, titanium, zircon, hafnium, vanadium, niobium, tantalum, chrome, Molybdenum, tungsten (also in the form of mixed carbides, e.g. tantalum / titanium / niobium / - Tungsten carbide), nitrides, for example of boron, aluminum, silicon, Germanium, titanium, zircon, hafnium, vanadium, niobium, tantalum, chromium, thorium and Uranium, phosphides for example from scandium, yttrium, lanthanum, actinium, niobium, Tantalum and tungsten, silicides for example from titanium, zircon, hafnium, vanadium, Niobium, tantalum, chrome, molybdenum, tungsten and iron, silicon / aluminum / acid Substance / nitrogen compounds, for example the general formula

Si _6-0.75x Al _0.67x O _x N _8-x ,

where x is an integer or fractional number between 0 and 8, boron silicon Carbonitrides, for example of the formula SiBN₃C, elements of III. and IV. main and V. and VI. subgroups of the Periodic Table of the Elements, for example Boron, aluminum, carbon, silicon, germanium, vanadium, niobium, tantalum, Chromium, molybdenum and tungsten, and / or other ceramic and / or among the Reaction conditions chemically and mechanically stable non-agglomerating Poorly soluble powder, but the additives do not support the catalyst represent.

Preferred additives are oxides, hydroxides and oxide hydrates of zirconium, hafnium, Titanium, niobium, tantalum, chrome, iron, cobalt, aluminum, gallium, silicon, vanadium, Molybdenum, tungsten, manganese, nickel, copper and lanthanum, borides of silicon, Lanthanum, titanium, zircon, hafnium, chromium and molybdenum, carbides of boron, silicon, Titanium, zirconium, hafnium, molybdenum and tantalum / titanium / niobium / tungsten mixed carbides, Nitrides of boron, silicon, titanium, zircon, hafnium and chromium, silicides of titanium, Zircon and hafnium, silicon / aluminum / oxygen / nitrogen compounds of the general formula given above, the boron silicon carbonitride of the formula SiBN₃C, and boron, carbon and silicon in elemental form. Especially before the oxides, hydroxides and oxide hydrates of zirconium, hafnium, titanium, Chromium, iron, cobalt, aluminum, silicon and the carbide SiC, the nitride Si₃N₄, La₂O₃ and activated carbon.

Additives can, for example, in amounts of 0.001 to 0.3 times the Weight of the water in the reaction system can be used. This amount is preferably from 0.01 to 0.1 times.

The additives are preferably used in the form of fine powders, for example with a particle size of 0.005 to 100 microns, particularly preferably from 0.005 to 10 µm.

A material can possibly also have several functions from the group of Meet modifiers, promoters and additives at the same time.  

It is advantageous during the reaction of the ruthenium compounds Ruthenium catalyst to stir the reaction mixture vigorously.

The response time for this implementation is determined by a number of parameters influenced, e.g. B. from the surface quality of the base used Metal, the temperature, the solvent, the stirring speed, etc. Man the implementation generally continues until the maximum possible amount the ruthenium compound has been reacted.

After the reaction has ended, the catalyst is dispersed in the reaction mix before. If necessary after adding acid, he can e.g. B. by filtration, Decanting or centrifuging can be separated. It is beneficial to use it after Wash off with one of the solvents mentioned and then to dry.

It may be advantageous to carry out the entire catalyst preparation and separation an inert gas atmosphere. Examples of inert gases are noble gases, Nitrogen and carbon dioxide. In dried form, in an inert gas atmosphere and at The finished catalyst can be used at room temperature or at a reduced temperature if necessary, be kept for a long time without significant activity loses.

The other conditions in the production of cyclic according to the invention Olefins from aromatic hydrocarbons can, for example, ent be selected according to the prior art, preferably as follows

• - Average crystallite size of the ruthenium-containing catalyst particles below 200 Å.
• - Use of 0.001 to 50 wt .-% ruthenium catalyst, based on a set aromatic hydrocarbon.
• - pH 0.5 to 7.  
• - Reaction temperature 20 to 250 ° C.
• - Hydrogen pressure 1 to 200 bar.

The inventive production of cyclic olefins by the partial Hydrogenation of aromatic hydrocarbons with hydrogen is becoming more typical continuously or discontinuously, e.g. B. in suspension or with a solid arranged catalyst performed.

The process according to the invention allows the production of cyclic mono olefins, especially cyclohexene, with conversions, yields and selectives vities that are the same or better than the state of the art. The The inventive method has the advantage that the required catalysts are accessible in a simple and inexpensive manner.

Examples example 1

10.0 g of ruthenium in the form of a 20% by weight solution of ruthenium (III) chloride in 20% by weight aqueous hydrochloric acid were diluted with 1000 ml of water, where a pH of 1.5 was established. With stirring for an hour A total of 8.5 g of calcium granules were added in portions, the temperature the reaction mixture was kept at 80 ° C. After the addition was complete Stirred for a further 3 hours, then the precipitated ruthenium catalyst filtered off. The filtrate had a pH of about 6. After washing with The catalyst thus obtained was dried with water over phosphorus pentoxide. Under It was argon and at 0 ° C without loss of activity and selectivity keep for a long time.

In an autoclave made of a nickel alloy (Hastelloy®) with a content of 0.7 l was 0.4 g of the catalyst thus obtained together with 320 ml of water, 14.4 g of ZnSO₄ × 7 H₂O, 2.0 g of zirconium dioxide and 80 ml of benzene. Then the autoclave was closed, heated to 150 ° C and hydrogen up to a Internal pressure of 50 bar pressed on. At the same time, stirring was vigorous. To At times, part of the reaction mixture was removed and its part Composition examined by gas chromatography. The results are out Table 1 can be seen.

Example 2

10.0 g of ruthenium in the form of a 20% by weight solution of ruthenium (III) chloride in 20% by weight aqueous hydrochloric acid were diluted with 1000 ml of water, where a pH of 1.5 was established. Then the mixture was heated to 50 ° C and a total of 10.0 g of magnesium powder in portions over a period of 5 minutes added, the temperature of the reaction mixture by means of external cooling was kept at 50 ° C. After the addition had ended, the mixture was stirred at 50 ° C. for 4 hours stirred, the pH of the reaction mixture by successive addition  of 25% by weight aqueous hydrochloric acid was kept at about 6. After this After cooling, the precipitated ruthenium catalyst was filtered off with water washed and dried over phosphorus pentoxide. Under argon at about 0 ° C the catalyst for a long time without loss of activity and selectivity store. The catalyst prepared in this way became the same as in Example 1 partial hydrogenation of benzene used. The result is from Table 1 evident.

Example 3

0.4 g of ruthenium in the form of a 20% by weight solution of ruthenium (III) chloride in 20 wt .-% aqueous hydrochloric acid were diluted with 60 ml of water and with 9.85 g of 10% aqueous hydrochloric acid are added, with a pH of 1.0 set. In the course of an hour, 1.56 g were added in portions and with stirring Zinc powder added, the temperature of the reaction mixture by means of external Cooling was kept at 20 ° C. After the addition was complete, 4 hours long stirred, then the precipitated ruthenium catalyst is filtered off. The Filtrate had a pH of 5. After washing with water, the kata Analyzer dried over phosphorus pentoxide. Under argon at approx. 0 ° C, he was without Keep reduction in activity and selectivity for a long time.

The catalyst thus prepared became partial as described in Example 1 Hydrogenation of benzene used. The results are shown in Table 1.

Table 1

Examples 1 to 3 were each carried out until the benzene conversion Had been 50%.

Example 4

To a mixture of 280 ml of water, 12.6 g of ZnSO₄ × 7 H₂O and 1.75 g of zircon dioxide in an autoclave made of a nickel alloy (Hastelloy®) with a content of 0.7 l 0.4 g of the catalyst prepared according to Example 1 was added. Then was the autoclave closed, heated to 150 ° C and hydrogen to the inside pressure of 40 bar, while with vigorous stirring within about 1 min 80 ml of benzene were added. Immediately afterwards the internal pressure of the Autoclave brought up to 50 bar by pressing hydrogen and Ver Run the hydrogenation kept at this value. At certain intervals part of the reaction mixture is removed and the composition gaschro analyzed matographically. The results are shown in Table 2.

Table 2

Example 5

To a mixture of 280 ml of water, 50.4 g of ZnSO₄ × 7 H₂O and 1.75 g Zirconium dioxide in a titanium autoclave of 0.7 l content was 1.0 g of the according Example 1 prepared catalyst given. Then the autoclave was ver closed and heated to 198 ° C, hydrogen up to an internal pressure of 145 bar  pressed on and with vigorous stirring within 2 min a total of 70 ml Benzene added, the internal pressure of the reaction vessel to 159 bar rise. In the course of the instant hydrogenation, the internal pressure of the Reaction vessel kept constant at 159 bar by replenishing hydrogen. Part of the reaction mixture was removed at certain intervals and analyzed the composition by gas chromatography. The results are shown in Table 3.

Table 3

Claims (10)

1. A process for the preparation of cyclic olefins by partial hydrogenation of aromatic hydrocarbons in the presence of water, optionally doped ruthenium as a catalyst, at least one promoter and optionally one or more additives, characterized in that the ruthenium catalyst has been obtained in the presence of a Solvent by reacting ruthenium compounds with a metal that is less noble than ruthenium. 2. The method according to claim 1, characterized in that the aroma hydrocarbons mono- or polycyclic, unsubstituted or with up to 5 C₁ to C₈ alkyl groups substituted compounds with 6 to 18 Carbon atoms used in the aromatic system. 3. Process according to claims 1 and 2, characterized in that one for Production of cyclic olefins by partial hydrogenation in water an amount of 0.01 to 20 times, based on the aroma used table hydrocarbon used. 4. Process according to Claims 1 to 3, characterized in that as Solvents in the reaction of the ruthenium compounds water, Alcohols, amines, polar organic solvents, hydrocarbons and / or mixtures of such solvents and if appropriate 0.001 to 4 parts by weight of an inorganic acid per part by weight contain. 5. Process according to Claims 1 to 4, characterized in that as base metal as ruthenium a metal of the 1st to 5th main group of the Periodic table of the elements, zinc, iron, cobalt or nickel. 6. The method according to claims 1 to 5, characterized in that the Catalyst a doping associated with it or adhering to it  Salts, oxides, hydroxides and / or complex compounds of metals the III. to V. main and / or I. to VIII. subgroup of Periodic table of the elements in amounts of up to 50 wt .-%, based to the pure metals. 7. The method according to claims 1 to 6, characterized in that the Reaction mixture promoters from compounds of zinc, of metals the 1st to VI. Subgroup of the Periodic Table of the Elements and / or of Manganese, iron, cobalt, nickel, aluminum, gallium, indium, germanium, Tin, lead and / or the rare earth metals in amounts between 0.001% by weight and the concentration of the respectively saturated solution, based on the aqueous phase of the reaction mixture. 8. The method according to claims 1 to 7, characterized in that the Reaction mixture particulate additives from oxides, hydroxides and Oxide hydrates of zirconium, hafnium, titanium, niobium, tantalum, chromium, iron, Cobalt, aluminum, gallium, silicon, vanadium, molybdenum, tungsten, Manganese, nickel, copper, scandium, yttrium, lanthanum and actinium, Borides, carbides, nitrides, phosphides, silicides, silicon / aluminum / - Oxygen / nitrogen compounds, boron-silicon carbonitrides, elements the III.- and IV. main group and V.- and VI. Subgroup of the periods systems of elements and / or other ceramic and / or among the Reaction conditions chemically and mechanically stable not agglomerate sparingly soluble powders in amounts of 0.001 to 0.3 times the Contains weight of water in the reaction system. 9. The method according to claims 1 to 8, characterized in that

• the ruthenium-containing catalyst particles have an average crystallite size of less than 200 Å,
• 0.001 to 50% by weight of ruthenium catalyst, based on the aromatic hydrocarbon used, are used,
• - a pH of 0.5 to 7 is maintained and
• - at 20 to 250 ° C and
• - A hydrogen pressure of 1 to 200 bar is used.

10. The method according to claims 1 to 9, characterized in that the Ruthenium catalyst to be used from any ruthenium compound is produced, for example from salts, oxides, hydroxides and Complex compounds of ruthenium.