EP1330422A2

EP1330422A2 - Method for the hydrogenation of unsubstituted or alkyl substituted aromatics using a catalyst with a structured or monolithic support

Info

Publication number: EP1330422A2
Application number: EP01986667A
Authority: EP
Inventors: Arnd BÖTTCHER; Jochem Henkelmann; Mathias Haake; Gerd Kaibel
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-10-13
Filing date: 2001-10-09
Publication date: 2003-07-30
Also published as: AU2002218222A1; MXPA03002847A; AU2002218222A8; CN1469851A; PL366054A1; JP2004529068A; US20040024274A1; WO2002030851A3; WO2002030851A2; IN2003CH00534A; DE10050709A1; RU2003113962A; KR20030040533A

Abstract

The invention relates to a method for the hydrogenation of unsubstituted or at least monoalkyl substituted uni- or poly-nuclear aromatics by means of bringing the above at least one aromatic into contact with a gas containing hydrogen, in the presence of a catalyst comprising at least one metal of sub-group VIII of the periodic system as active metal, supported on a structured or monolithic support.

Description

Process for the hydrogenation of unsubstituted or alkyl-substituted aromatics using a catalyst with a structured or monolithic support

The present invention relates to a process for the hydrogenation of mono- or polynuclear aromatics optionally substituted with at least one alkyl group to give the corresponding cycloaliphatics, in particular benzene to cyclohexane, by contacting the aromatics with a hydrogen-containing gas in the presence of a catalyst which is at least one active metal Metal of the NHL subgroup of the periodic table, applied to a structured or monolithic carrier.

There are numerous processes for the hydrogenation of, for example, benzene to cyclohexane. These hydrogenations are predominantly carried out on particulate nickel and platinum catalysts in the gas or liquid phase (see, for example, US Pat. No. 3,597,489 or GB 1,444,499 or GB 992 104). Typically, most of the benzene is first hydrogenated to cyclohexane in a main reactor and then the reaction to cyclohexane is completed in one or more post-reactors.

The highly exothermic hydrogenation reaction requires careful pressure, temperature and residence time control in order to achieve complete conversion with high selectivity. In particular, significant formation of methylcyclopentane, which preferably occurs at higher temperatures, must be suppressed. Typical cyclohexane specifications require a residual benzene content <100 ppm and a methylcyclopentane content <200 ppm. The content of n-paraffins (n-hexane, n-pentane, etc.) are critical. These undesirable compounds also preferably form at higher hydrogenation temperatures and, like methylcyclopentane, can only be separated from the cyclohexane produced by complex separation operations. The separation can take place, for example, by extraction, rectification or by using molecular sieves, as described in GB 1 341 057. The catalyst used for the hydrogenation also has a strong influence on the extent of the desired formation of methylcyclopentane.

Against this background, it is desirable to carry out the hydrogenation at low temperatures if possible. However, this is limited in that, depending on the type of hydrogenation catalyst used, a sufficiently high hydrogenation activity of the catalyst, which is sufficient to obtain economical space-time yields, is only achieved from higher temperatures.

The nickel and platinum catalysts used for the hydrogenation of benzene have a number of disadvantages. Nickel catalysts are very sensitive to sulfur-containing impurities in benzene, so that either very pure benzene must be used for the hydrogenation or, as described in GB 1 104 275, a platinum catalyst is used in the main reactor that tolerates a higher sulfur content and so the post-reactor that is used is filled with a nickel catalyst. Another possibility is to dope the catalyst with rhenium (GB 1 155 539) or to produce the catalyst using ion exchangers (GB 1 144 499). However, the production of such catalysts is complex and expensive. The hydrogenation can also be carried out on Raney nickel (US Pat. No. 3,202,723); however, the flammability of this catalyst is a disadvantage. Homogeneous nickel catalysts can also be used for the hydrogenation (EP 0 668 257). However, these catalysts are very sensitive to water, so that the benzene used is first in a drying column before the hydrogenation Residual water content <1 ppm must be dried. Another disadvantage of the homogeneous catalyst is that it cannot be regenerated.

Platinum catalysts have fewer disadvantages than nickel catalysts, but are much more expensive to manufacture. Very high hydrogenation temperatures are necessary both when using platinum ice and nickel catalysts, which can lead to a significant formation of undesired by-products.

The hydrogenation of benzene to cyclohexane is not carried out industrially on ruthenium catalysts, but there are references in the patent literature to the use of ruthenium-containing catalysts for this application.

According to SU 319 582, Ru suspension catalysts which are doped with Pd, Pt or Rh are used for the production of cyclohexane from benzene. However, the catalysts are very expensive due to the use of Pd, Pt or Rh. Furthermore, the work-up and recovery of the catalyst is complicated and expensive in the case of suspension catalysts.

According to SU 403 658, a Cr-doped Ru catalyst is used to produce cyclohexane. The active metals are supported on an Ai ₂ θ ₃ grate. The hydrogenation takes place at temperatures of 160 to 180 ° C. This generates a significant amount of undesirable by-products

US Pat. No. 3,917,540 discloses A ₂ θ ₃ supported catalysts for the preparation of cyclohexane. As active metal, these contain a noble metal from subgroup VIII of the periodic table, furthermore an alkali metal and technetium or rhenium. The A_ ₂ θ ₃ carriers are in the form of spheres, granules or the like. The disadvantage of such catalysts is that only a selectivity of 99.5% is achieved. Finally, US Pat. No. 3,244,644 describes η-AkO supported ruthenium hydrogenation catalysts which are also said to be suitable for the hydrogenation of benzene. The catalysts are shaped into particles of a maximum of ¹ A inch and have at least 5% active metal; the production of η-Al ₂ O ₃ is complex and expensive.

In addition to the particulate catalysts or suspension catalysts described above, the prior art discloses monolithic supported catalysts in the form of ordered packings with catalytically active layers which can be used for hydrogenation reactions.

EP 0 564 830 B1, for example, describes a monolithic supported catalyst which can have elements of group VIII of the periodic table as active components.

EP 0 803 488 A2 discloses a process for the reaction, for example hydrogenation, of an aromatic compound which carries at least one hydroxyl group or amino group on an aromatic ring in the presence of a catalyst which comprises a homogeneous ruthenium compound which is in situ on a support, for example, a monolith. The hydrogenation is carried out at pressures of more than 50 bar and temperatures of preferably 150 ° C. to 220 ° C.

The object of the present invention was to provide an economical process for the hydrogenation of unsubstituted or mononuclear or polynuclear aromatics substituted with at least one alkyl group to give the corresponding cycloaliphatics, in particular from benzene to cyclohexane.

This object is achieved by the process according to the invention for hydrogenating at least one unsubstituted or with at least one

Alkyl group substituted mono- or polynuclear aromatics by Bringing the at least one aromatic into contact with a hydrogen-containing gas in the presence of a catalyst which has as active metal at least one metal from subgroup VIII of the Periodic Table, applied to a structured or monolithic support.

It was surprisingly found that aromatics of this type selectively and with a high space-time yield on catalysts which have a structured or monolithic support, compared to the processes of the prior art, significantly lower pressures and temperatures to give the corresponding cycloaliphatics let it hydrate. This was also very surprising, since even for the hydrogenation of aromatics with polar substituents, as described in EP 0 803 488 A2, which have a significantly higher reactivity than unsubstituted or mononuclear or polynuclear aromatics substituted with at least one alkyl group, very high Pressures and temperatures for hydrogenation are necessary. It was therefore not to be expected that the process according to the invention could be used to hydrogenate such aromatics in an economical manner at all. At the low pressures and temperatures which can be used according to the invention, the formation of undesired by-products, e.g. Methylcyclopentane or other n-paraffins almost completely, so that an expensive purification of the cycloaliphate produced is unnecessary, which makes the process very economical.

In the context of the present invention, structured supports are understood to mean those supports which have a regular planar or spatial structure and thereby differ from supports in particle form which are used as loose piles. Examples of structured carriers are carriers constructed from threads or wires, usually in the form of carrier webs, such as woven, knitted, crocheted or felted. Structured supports can also be foils or sheets, which can also have cutouts, such as perforated sheets or expanded metals. Such essentially flat structured For the intended use, supports can be shaped into appropriately shaped spatial structures, so-called monoliths or monolithic supports, which in turn can be used, for example, as catalyst packs or column packs. Packs can consist of several monoliths. It is also possible not to build monoliths from flat carrier webs, but to produce them directly without intermediate stages, for example the ceramic monoliths with flow channels known to the person skilled in the art.

Flat structured supports can be used as structured supports, for example woven fabrics, knitted fabrics, knitted fabrics, felts, foils, sheets, such as perforated sheets, or expanded metals. However, essentially spatial structures, such as monoliths, can also be used.

The structured supports or monoliths can consist of metallic, inorganic, organic or synthetic materials or combinations of such materials.

Examples of metallic materials are pure metals such as iron, copper, nickel, silver, aluminum and titanium or alloys such as steels such as nickel, chromium and molybdenum steel, brass, phosphor bronze, monell and nickel silver. Examples of ceramic materials are aluminum oxide, silicon dioxide, zirconium dioxide, cordierite and steatite. Carbon can also be used.

Examples of synthetic carrier materials are, for example, plastics, such as polyamides, polyethers, polyvinyls, polyethylene, polypropylene, polytetrafluoroethylene, polyketones, polyether ketones, polyether sulfones, epoxy resins, alkyd resins, urea and melamine-aldehyde resins.

Glass fibers can also be used. Structured supports in the form of metal fabrics, knits, knits or felts, carbon fiber fabrics or felts or plastic fabrics or knits are preferably used.

Monoliths from tissue packs are particularly preferred because they can withstand high cross-sectional loads of gas and liquid and show only minor wear.

Metallic, structurized supports or monoliths are particularly preferably used, which consist of stainless steel, which preferably shows a roughening of the surface when tempering in air and then cooling. These properties are particularly evident in stainless steel, in which an alloy component accumulates on the surface above a specific segregation temperature and forms a firmly adhering, rough, oxidic surface layer in the presence of oxygen. Such an alloy component can be, for example, aluminum or chromium, from which a surface layer of AL-O ₃ or Cr ₂ θ ₃ is formed accordingly. Examples of stainless steel are those with the material numbers (according to the German standard DIN 17007) 1.4767, 1.4401, 1.4301, 2.4610, 1.4765, 1.4847 and 1.4571. These steels can preferably be thermally roughened by air tempering at 400 to 1100 ° C for a period of 1 hour to 20 hours and then allowed to cool to room temperature. It can also be roughened mechanically and / or thermally.

Before application of the active metals and optionally promoters, the stagnated or monolithic supports can optionally be coated with one, two or more oxides. This can be done physically, for example by sputtering. Here, oxides such as Al ₂ O _{3 are} applied to the carrier in an oxidizing atmosphere in a thin layer. The structured supports can be deformed or rolled up either before or after the application of the active metals or promoters, for example by means of a gear shaft, in order to obtain a monolithic catalyst element.

In principle, all metals of subgroup VIII of the periodic table can be used as active metals. Platinum, rhodium, palladium, cobalt, nickel or ruthenium or a mixture of two or more thereof are preferably used as active metals, ruthenium in particular being used as the active metal. Ruthenium alone is particularly preferably used as the active metal. An advantage of using the hydrogenation metal ruthenium is that, compared to the much more expensive hydrogenation metals platinum, palladium or rhodium, this can save considerable costs in the production of the catalyst.

The catalysts which are used in the context of the present invention can also contain promoters for doping the catalyst, for example alkali and / or alkaline earth metals, such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium and barium; Silicon, carbon, titanium, zirconium, tungsten, and the lanthanoids and actinides; Coin metals such as copper, silver and / or gold, zinc, tin, bismuth, antimony, molybdenum, tungsten and / or other promoters such as sulfur and / or selenium.

The catalysts used according to the invention can be prepared industrially by applying at least one metal from subgroup VIII of the periodic table and, if appropriate, at least one promoter to one of the supports described above.

The application of the active metals and optionally promoters to the carriers described above can be done by the active metals in

Vacuum evaporates and condenses continuously on the carrier. Another It is possible to apply the active metals to the supports by impregnating them with solutions which contain the active metals and optionally promoters. Another possibility is to apply the active metals and, if appropriate, promoters to the supports by chemical methods such as chemical vapor deposition (CVD).

The catalysts prepared in this way can be used directly or can be tempered and / or calcined before they are used, and can be used both in a pre-reduced and in a non-reduced state.

Optionally, the carrier is pretreated before the application of the active metals and optionally promoters. Pretreatment is advantageous, for example, if the adhesion of the active components to the support is to be improved. Examples of a pretreatment are coating the support with adhesion promoters or roughening with mechanical (for example grinding, sandblasting) or thermal processes such as heating, usually in air, plasma etching or glowing.

The present invention thus also relates to structured catalyst supports charged with a promoter, the promoter being selected from metals from the group consisting of metals from the L, II. And IV. Main group of the Periodic Table of the Elements, metals from I. to IV. And VI. Sub-group of the periodic table of the elements as well as sulfur, selenium and carbon, preferably stagnated carriers. Particularly preferred promoters are: Si, Ti, Zr, Mg, Ca, C, Yt, La, Ac, Pr, W, and combinations of two or more thereof.

Furthermore, the present invention relates to catalysts comprising a support as defined above and — applied thereon — an active metal of subgroup VIII of the periodic table. The catalysts 1 and 2 which are preferably used will be described below; with regard to general features of the catalysts 1 and 2, reference is made to the above statements.

Catalyst 1

The structured support or monolith which is used for catalyst 1 is preferably pretreated, for example by the above-described tempering in air (thermal roughening) and subsequent cooling. The carrier is then preferably impregnated with a solution (impregnating medium) containing the active metal. Subsequently, if it is an essentially flat structured support, it can be processed into a monolithic catalyst element.

If the carrier is metallic, for example made of stainless steel, it is preferably roughened thermally by air tempering at 400 to 1100 ° C. for a period of 1 hour to 20 hours and then cooling to room temperature.

The support can be impregnated with the solution by immersion, rinsing or spraying.

The impregnation medium preferably has a surface tension of at most 50 mN / m. In a further preferred form, the impregnation medium has a surface tension of at most 40 mN / m. The minimum value of the surface tension is generally freely selectable. In a preferred form, however, the impregnation medium has a surface tension of at least 10 mN / m and in a particularly preferred form of at least 25 mN / m. The surface tension is measured according to the OECD ring method known to the person skilled in the art (ISO 304, cf. Official Journal of the EC No. L 383 of December 29, 1992, pages A 47 - A / 53). The impregnating medium preferably contains a solvent and / or suspending agent, for example water, in which the active metals are preferably dissolved in the form of their metal salts.

The impregnation medium can optionally also contain promoters for doping the catalyst. In this context, reference is made to the general statements above.

A solvent and / or suspending agent contained in the ink medium is selected so that the active components, active metals, promoters or their precursors to be applied therein and / or thus do not show any undesirable reactions.

The known and commercially available solvents can be used as solvents and / or suspending agents, for example aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cumene, pentane,

Hexane, heptane, hydrocarbon cuts such as gasoline, ligroin, white oil,

Alcohols, diols, polyols such as methanol, ethanol, the two propanol isomers, the four butanol isomers, glycol, glycerin, ethers such as diethyl ether, di-n-butyl ether, methyl tert. -butyl ether, ethyl tert. butyl ether, methyl tert-amyl ether,

Ethyl tert-amyl ether, diphenyl ether, ethylene glycol dimethyl ether,

Diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, or water. The organic solvents or suspending agents used can also be substituted, for example with halogens, such as chlorobenzene, or with nitro groups, such as nitrobenzene. The solvents or suspending agents are used individually or in a mixture.

The tear medium can also contain auxiliary substances if necessary.

For example, the impregnation medium contains acidic or basic compounds or buffers, if this is for stabilization or solubility at least one of its active components or their precursors is necessary or advantageous.

Soluble salts of the active components are preferably completely dissolved in a solvent. An aqueous solution of active components is advantageously used.

If the active composition consists of metals, either an aqueous, nitric acid solution of the nitrates of the metals or an aqueous, ammoniacal solution of amine complexes of the metals is used in a particularly preferred manner. If the active components consist of amorphous metal oxides, an aqueous sol of the oxide, which is optionally stabilized, is preferably used.

The surface tension of the impregnation medium can be adjusted using suitable surface-active substances such as anionic or non-anionic surfactants. The impregnated carrier is generally dried after the impregnation at temperatures from 100 to about 120 ° C. and optionally calcined at temperatures from 120 to 650 ° C., preferably from 120 to 400 ° C.

An essentially flat-structured support can be deformed after the thermal treatment into a spatial structure shaped according to the intended use. The deformation can take place, for example, by working steps such as cutting, corrugating the webs, arranging or fixing the corrugated webs in the form of a monolith with parallel or crosswise channels. The deformation to the monolith is optionally carried out before impregnation, drying, thermal treatment or chemical treatment. Further details regarding catalyst 1 and its production can be found in DE-A 198 27 385J, the content of which in this regard is fully incorporated into the present application by reference.

Catalyst 2

The structured support or monolith that is used for catalyst 2 is preferably pretreated, for example by air tempering and subsequent cooling. The carrier is then preferably coated with at least one active metal in vacuo. Subsequently, if it is an essentially flat shaped support, it can be processed into a monolithic catalyst element.

In addition to the active metal or metals, promoters for doping the catalyst are preferably also applied to the support material in vacuo. With regard to possible promoters, reference is made to the general statements above.

The carrier material preferably consists of metal, particularly preferably stainless steel, more preferably stainless steel of the numbers mentioned above. The support is pretreated preferably by tempering the metal support at temperatures of 600 to 1100 ° C, preferably at 800 to 1000 ° C, 1 to 20, preferably 1 to 10 hours in air. The carrier is then cooled.

The active components (active metals and promoters) can be applied to the support by vapor deposition and sputtering. For this purpose, the carrier is vacuumed at a pressure of 10 ^"3 to 10 ^{" 8} mbar, preferably by means of an evaporation device, for example electron beam vaporization or sputtering device, with the active components simultaneously or in succession discontinuous or continuous driving style coated. Tempering under inert gas or air can be followed to form the catalyst.

The active components can be applied in several layers. The catalyst obtained in this way can be processed further to form a monolith. In this regard, i.a. refer to the comments on catalyst 1. The catalyst is preferably processed by deforming (corrugated, corrugated) the catalyst fabric or the catalyst film using a gear roller and rolling smooth and corrugated fabric into a cylindrical monolith with similar vertical channels.

Further details regarding catalyst 2 and its production can be found in EP 0 564 830, the content of which in this regard is fully incorporated into the present application by reference.

Verfal-jens leadership

In principle, all mono- or polynuclear aromatics which are either unsubstituted or one or more can be used in the process according to the invention

Have alkyl groups, used individually or as mixtures of two or more thereof, preferably individually. The length of the alkyl group is also not subject to any particular restrictions, but in general it is Ci to C ₃₀ , preferably C to C ₁₈ , in particular C to C, alkyl groups. In particular, the following aromatics are to be mentioned as educts for the present process: benzene, toluene, xylenes, cumene,

Diphenylmethane, tri-, tetra-, penta- and hexabenzenes, triphenylmethane, alkyl-substituted naphthalenes, naphthalene, alkyl-substituted anthracenes,

Anthracene, alkyl substituted tetralins and tetralin. Benzene is preferably converted to cyclohexane in the context of the present processes. In the process according to the invention, the hydrogenation is preferably carried out at a temperature of approximately 50 to 200 ° C., particularly preferably approximately 70 to 160 ° C., in particular between 80 to 100 ° C. The lowest temperatures can be reached, especially when using ruthenium as the active metal. The hydrogenation process according to the invention is preferably carried out at pressures of less than 50 bar, for example 1 to 49 bar, particularly preferably at pressures of 2 to 10 bar and in particular at pressures between 5 and 10 bar. Due to the low pressures and temperatures that can be used in the process according to the invention, the formation of undesired by-products, such as, for example, methylcyclopentane or other n-paraffins, is almost completely eliminated, so that complex purification of the cycloaliphatene produced is unnecessary, which makes the process very economical. Despite low temperatures and pressures, the aromatic compounds can be hydrogenated economically selectively and with a high space-time yield to the corresponding cycloaliphatics.

The process according to the invention can be carried out both in the gas phase and in the liquid phase, the latter being preferred.

The process according to the invention can be carried out continuously or batchwise, with the continuous process being preferred.

The process is preferably carried out in a tubular reactor, for example a column, with product return and cycle gas. A continuous swamp procedure is further preferred.

The hydrogenation of the aromatics according to the invention is preferably carried out in such a way that the hydrogen-containing gas is conducted in countercurrent to the liquid aromatics or in a column which is equipped with one of the catalysts described above. The liquid phase can be passed through the column from top to bottom and the gaseous phase from the bottom up. In the context of the present invention, the hydrogenation is preferably carried out continuously, in particular in countercurrent. The hydrogenation is preferably carried out in two or more stages. The catalyst described in this application is used in at least one stage. In a particularly preferred embodiment of the process according to the invention, the hydrogenation is carried out continuously in one or more reactors connected in series.

In the case of continuous process control, the amount of the compound provided for the hydrogenation is preferably about 0.05 to about 3 kg / 1 catalyst per hour, more preferably about 0.2 to about 2 kg / 1 catalyst per hour.

The hydrogenation can be carried out with a low cross-sectional load in trickle mode, preferably in a bottoms mode with a high cross-sectional load. The cross-sectional loads for the liquid and gaseous phases are preferably 150 to 600 m ³ / (m ² 'h), based on the free area of the rector, particularly preferably 200 to 300 m ³ / (m ² h). The holdup of the gas is preferably 0.5, the holdup of the gas being defined here as the quotient of the volume of gas in the numerator and the sum of the volume of gas and the volume of liquid in the denominator. The pressure loss is preferably 0.1 to 1.0, particularly preferably 0.15 to 0.3 bar, in each case per m of column height.

Any gases which contain free hydrogen and have no harmful amounts of catalyst poisons, such as CO, can be used as hydrogenation gases. For example, reformer exhaust gases can be used. Pure hydrogen is preferably used as the hydrogenation gas. The hydrogenation according to the invention can be carried out in the absence or presence of a solvent or diluent, ie it is not necessary to carry out the hydrogenation in solution.

Any suitable solvent or diluent can be used as the solvent or diluent. The selection is not critical as long as the solvent or diluent used is able to form a homogeneous solution with the aromatics to be hydrogenated.

The amount of solvent or diluent used is not particularly limited and can be freely selected as required, but such amounts are preferred which lead to a 10 to 70% strength by weight solution of the aromatic intended for hydrogenation.

If a solvent is used, the product formed in the hydrogenation, that is to say the cycloaliphate (s) in question, is used as the preferred solvent in the process according to the invention, optionally in addition to other solvents or diluents. In this case, part of the product formed in the process can be mixed with the aromatics still to be hydrogenated. Based on the weight of the aromatic intended for hydrogenation, preferably 1 to 30 times, particularly preferably 5 to 20 times, in particular 5 to 10 times, the amount of product as a solvent or diluent is added.

In the context of the present invention, benzene is preferably reacted at a temperature of 80 to 100 ° C., ruthenium alone being used as the active metal. A particularly preferred embodiment of the present invention, which has been found to be particularly advantageous, provides for the hydrogenation of benzene to cyclohexane in the liquid phase in the bottoms mode with Produl-friicl ulirung and cycle gas with a cross-sectional load of 200 to 300 m ³ / (m ² h) at temperatures from 50 ° C to 160 ° C and pressures from 1 to 100 bar to perform on a pure ruthenium monolith catalyst. For the preferred pressure and temperature ranges, reference is made to the above explanations.

The present method according to the invention has numerous advantages over the methods of the prior art. The aromatics can be hydrogenated at significantly lower pressures and temperatures than described in the prior art, selectively and with a high space-time yield to the corresponding cycloaliphatics. The catalysts are very active even at low pressures and temperatures. The cycloaliphatics are obtained in highly pure form, which makes complex stripping processes unnecessary. The formation of, for example, undesired methylcyclopentane in the hydrogenation of benzene to cyclohexane or other n-paraffins is almost completely avoided, so that purification of the cycloaliphatics produced is unnecessary. Cycloaliphatics can be obtained with a high space-time yield even at low pressures. Furthermore, the hydrogenation can be carried out with excellent selectivity without the addition of auxiliary chemicals.

The invention will now be explained in more detail using the following examples with reference to the accompanying drawings. The drawing shows in

Fig. 1 is a schematic drawing of a preferred method according to the present invention.

1, the process according to the invention can be carried out in a tubular reactor 1, for example a column, with product stirring and cycle gas. Fig. 1 shows a continuous swamp mode of operation using a packed bubble column. In the reactor 1 there is a monolithic catalyst 2 as a fixed bed. Feed is put together via feed 3 with circulating liquid via line 4 as a propellant jet into a mixing nozzle 5 in which fresh hydrogen via line 6 and circulating gas via line 7 are mixed. The two-phase gas / liquid mixture 8 emerges at the upper end of the reactor 1 and is separated in a gas liquid separator 9. A partial gas stream 11 is discharged from the gas stream 10. The circulating gas stream 7 is fed back into the mixing nozzle 5 via a compressor 12. This compressor 12 can optionally be omitted if the circulating liquid 4, which is fed via the pump 13, can be provided at a sufficiently high pressure and the mixing nozzle 5 is designed as a propellant jet. A partial stream 14 is taken from the circulating liquid 4 as a product stream. The volume ratio of circulating liquid 5 to product stream 14 is 90: 1 to 500: 1, preferably 150.J to 250.J. The heat exchange is regulated via the heat exchanger 15. The dimensioning of the tube reactor 1 is based on the diameter so that there is an empty tube speed of 100 to 1000 m / h for the liquid.

Production examples for catalysts

Production Example 1

This monolith catalyst was made from a V2A fabric tape coated with 0.455 g Ru / m ² , material no. 1.4301, which had previously been annealed in air at 800 ° C for 3 hours. This cloth tape was coated with a ruthenium metal salt solution by soaking. The coated fabric was then heated at 200 ° C. for 1 hour. 51 cm of the 20 cm wide catalyst fabric belt were corrugated with a gear roller, module 1.0 mm, and rolled up with a 47 cm long smooth catalyst fabric tape, so that a monolith with vertical channels and a diameter of 2.7 cm was formed (catalyst A ). Production Example 2

This monolith catalyst was made from a V2A fabric tape coated with 0.432 g Ru / m, material no. 1.4301 manufactured. The fabric band was air-annealed for 3 hours at 800 ° C. and then steamed with 2000 Å silicon. The siliconized vapor-coated tape was then tempered at 650 ° C. This fabric tape was subsequently coated with a total of 0.432 g Ru / m ² by impregnation with a ruthenium metal salt solution. The coated fabric tape was then heated at 200 ° C. for 1 hour. 51 cm of the 20 cm wide catalyst fabric tape were corrugated with a gear roller, module 1.0 mm, and rolled up with a 47 cm long smooth catalyst fabric tape, so that a monolith with vertical channels and a diameter of 2.7 cm was formed (catalyst B ).

process examples

Process example 1

Three ruthenium monolith catalysts A with a total volume of 343 cm ^{3 were} installed in a heatable double-jacket tubular reactor. The apparatus was then flushed with N ₂ and then N _{2 was} replaced by H2 and the catalyst was reduced at 80 ° C. for 1 hour. It was then cooled and the system circuit was charged with benzene. Hydrogenation was carried out at 100 ° C., 8 bar and a cross-sectional load for liquid and gas of 200 m ³ / (m ² 'h) in accordance with the procedure shown in FIG. 1. The GC analyzes of the reaction product showed a yield of 99.99% with a quantitative conversion of benzene. The space-time yield was 0.928 kg / (l'h). Methylcyclopentane could not be detected.

Process example 2

Three ruthenium monolith catalysts B with a total volume of 343 cm ^{3 were} installed in a heatable double-jacket tubular reactor. The apparatus was then rinsed with N_ and the catalyst was not reduced beforehand. The system was then charged with benzene and hydrogen was injected. Hydrogenation was carried out at 100 ° C., 8 bar and a cross-sectional load for liquid and gas of 200 m ³ / (m ² 'h) in accordance with the procedure shown in FIG. 1.

The GC analyzes of the reaction product showed a yield of 99.99% with a quantitative conversion of benzene. The space-time yield was 0.802 kg / (l ^'h). Methylcyclopentane could not be detected.

Claims

claims

1. Process for the hydrogenation of at least one unsubstituted or mononuclear or polynuclear aromatic substituted with at least one alkyl group by contacting the at least one aromatic with a hydrogen-containing gas in the presence of a catalyst which, as the active metal, applied at least one metal from subgroup VIII of the periodic table has a structured or monolithic support.

2. The method according to claim 1, wherein the hydrogenation is carried out at pressures of less than 50 bar, preferably at pressures between 5 and 10 bar.

3. The method according to claim 1 or 2, in which the structured carrier is selected from woven, knitted, knitted, felted, foils,

Sheets or expanded metals.

4. The method according to any one of the preceding claims, wherein the carrier consists of metallic, inorganic, organic or synthetic materials or combinations of such materials.

5. The method according to any one of the preceding claims, in which ruthenium is used alone as the active metal.

6. The method according to any one of the preceding claims, in which a supported catalyst is used, which by annealing the structured Carrier or monolith in air and cooling, subsequent impregnation with a solution containing the at least one active metal and optionally processing to a monolithic catalyst element, is available.

7. The method according to any one of claims 1 to 5, in which a supported catalyst is used which by tempering the structured support or monolith in air and cooling, then coating the same with the at least one active metal in vacuo and optionally processing to a monolithic

Catalyst element is available.

8. The method according to any one of the preceding claims, in which benzene is hydrogenated to cyclohexane or aniline to cyclohexylamine.

9. The method according to any one of the preceding claims, wherein the hydrogenation is carried out at a temperature of 70 to 160 C.

10. The method according to any one of the preceding claims, in which benzene is hydrogenated at a temperature of 80 to 100 C and as

Active metal ruthenium is used alone.

11. The method according to any one of the preceding claims, wherein the hydrogenation is carried out continuously and in countercurrent.

12. Structured catalyst carrier loaded with a promoter, the promoter being selected from metals of the L, II., IV. Main group of the Periodic Table of the Elements, metals of the I. to IV. And VI. Sub-group of the periodic table of elements and sulfur, selenium and carbon.

13. Structured support according to claim 12, wherein the promoter is selected from the group consisting of: Si, Ti, Zr, Mg, Ca, C, Yt, La, Ac, Pr, W, and combinations of two or more thereof.

14. Stnikturierter carrier according to claim 12 or 13, wherein the carrier material has a roughened by thermal, chemical or thermal and chemical treatment surface.

15. A catalyst comprising a support according to any one of claims 12 to 14 and applied thereto an active metal of subgroup VIII

Periodic Table.