WO2004007414A1 - Method for the continuous hydrogenation of citral to give citronellal - Google Patents

Method for the continuous hydrogenation of citral to give citronellal Download PDF

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Publication number
WO2004007414A1
WO2004007414A1 PCT/EP2003/007601 EP0307601W WO2004007414A1 WO 2004007414 A1 WO2004007414 A1 WO 2004007414A1 EP 0307601 W EP0307601 W EP 0307601W WO 2004007414 A1 WO2004007414 A1 WO 2004007414A1
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Prior art keywords
liquid phase
catalyst particles
catalyst
citral
transport
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PCT/EP2003/007601
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German (de)
French (fr)
Inventor
Hans-Georg Göbbel
Günter WEGNER
Hartwig Fuchs
Signe Unverricht
Axel Salden
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Basf Aktiengesellschaft
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Priority to AU2003254348A priority Critical patent/AU2003254348A1/en
Publication of WO2004007414A1 publication Critical patent/WO2004007414A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
    • C07C45/62—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by hydrogenation of carbon-to-carbon double or triple bonds

Definitions

  • the present invention relates to a process for the continuous, selective hydrogenation of citral to citronellal (Scheme 1).
  • Citral and its hydrogenation products are used as fragrance and aroma substances.
  • GB 1 389 177, GB 1 476 818, GB 1 340 409 and US 3,971,830 describe processes for the preparation of citronellal by hydrogenating citral over a palladium-containing catalyst in the presence of borax or bases.
  • Catalytic hydrogenations on heterogeneous catalysts are often carried out using fixed bed reactors in order to obtain the advantages of a continuous process.
  • specially prepared catalysts have to be manufactured and used for this purpose, which have to be replaced or regenerated in a complex manner if activity is lost - often after a short period of idle time - which is usually not only the case when the hydrogenation system is switched off, but also afterwards Processing stages is connected.
  • a heterogeneously catalyzed hydrogenation can be carried out in the form of a suspension reaction, the hydrogenation catalyst being suspended in a liquid phase by supplying mechanical energy, for example in a stirred tank, cf. eg Ull ann's Encyclopedia of Technical Chemistry, 4th ed. Volume 13, 1997, p. 138, Verlag Chemie Weinheim.
  • mechanical energy for example in a stirred tank, cf. eg Ull ann's Encyclopedia of Technical Chemistry, 4th ed. Volume 13, 1997, p. 138, Verlag Chemie Weinheim.
  • Fluidized or fluidized bed reactors allow higher relative speeds, but require the use of significantly larger catalyst particles so that a more or less strongly expanded catalyst bed is present during operation.
  • the smaller volume-related surface area of larger catalyst particles limits the material conversion and thus compensates for the effect of the higher relative speed.
  • EP-A 798 039 discloses a process for carrying out catalytic reactions in a reactor which contains a liquid phase in which at least one catalyst is suspended. The hydrogenation of hydrodehydrolinalool to hydrolinalool and further to tetrahydrolinalool is described. Hydrodehydrolinalool contains only a triple bond as the functional group to be hydrogenated, so that the person skilled in the art would not have taken any suggestion regarding selective hydrogenation.
  • the present invention has for its object to provide a process for the selective hydrogenation of citral to citronellal, which combines the advantages of a high space-time yield and a simple catalyst exchange.
  • the object is achieved according to the invention by a process in which a liquid phase in which the citral is dissolved and suspended in the particles of a catalyst which is capable of preferential hydrogenation of carbon-carbon double bonds before carbon-oxygen double bonds , in the presence of a hydrogen-containing gas through a device which inhibits the transport of the catalyst particles.
  • a higher relative speed of the liquid phase compared to the catalyst particles is generated because the transport of the catalyst particles is inhibited by suitable means, such as internals in a reactor, i.e. the particles are held back more strongly by the surrounding liquid.
  • suitable means such as internals in a reactor, i.e. the particles are held back more strongly by the surrounding liquid.
  • high space-time yields are achieved as a result.
  • the device which inhibits the transport of the catalyst particles preferably has openings or channels whose hydraulic diameter is 2 to 2000 times, in particular 5 to 500 times, particularly preferably 5 to 100 times the average diameter of the catalyst particles.
  • the hydraulic diameter is a parameter familiar to the person skilled in the art for describing the equivalent diameter of non-circular channel structures.
  • the hydraulic diameter of an opening is defined as the quotient of 4 times the cross-section of the opening and its circumference.
  • the hydraulic diameter can be as
  • the openings or channels of suitable devices generally have a hydraulic diameter of 0.5 to 20 mm, preferably 1 to 10 mm, particularly preferably 1 to 3 mm.
  • catalyst particles with an average diameter of 0.0001 to 2 mm, preferably 0.001 to 1 mm, particularly preferably 0.005 to 0.1 mm are used.
  • the device which inhibits the transport of the catalyst particles can consist of a bed, a knitted fabric, or an open-celled one
  • Foam structure preferably made of plastic e.g. Polyurethane or melamine resin, or ceramic, or a packing element as is basically, i.e. its geometrical shape, already known from the distillation and extraction technology, exist.
  • the packs generally have a hydraulic diameter which is smaller by a factor of 2 to 10 than that of comparable internals in the area of distillation and extraction technology.
  • Metal mesh packs or wire mesh packs are particularly suitable as packing elements.
  • packs made of other woven, knitted or felted materials can also be used.
  • Packs of flat or corrugated metal sheets are also suitable, preferably without perforation or other larger openings, for example in accordance with the Montz Bl or Sulzer Mellapak types.
  • Packings made of are also advantageous Expanded metal, such as packs of the type Montz BSH. What is decisive for the suitability of a package in the context of the present invention is not its geometry, but rather the opening sizes or channel widths in the package which arise for the current conduction.
  • the surfaces of the device facing the liquid phase have a roughness in the range from 0.1 to 10 times, preferably from 0.5 to 5 times, the average diameter of the catalyst particles.
  • Materials are preferred whose surfaces have a mean roughness value R a (determined according to DIN 4768/1) of 0.001 to 0.01 mm.
  • R a determined according to DIN 4768/1
  • a corresponding surface roughness can be achieved when using wire mesh packings made of stainless steel by thermal treatment in the presence of oxygen, for example by tempering the tissue in air at a temperature of about 800 ° C.
  • the process according to the invention is generally carried out at a pressure between 1 and 100 bar, preferably 1 and 60 bar, particularly preferably 1 and 50 bar.
  • the reaction temperatures are usually between 40 and 120 ° C, preferably between 60 and 100 ° C, particularly preferably between 70 and 90 ° C.
  • the liquid phase preferably comprises an inert diluent, in particular a C 1 -C 6 -alkanol, particularly preferably a C 1 -C 4 -alkanol, such as, in particular, methanol.
  • the liquid phase further preferably comprises ammonia, a primary, secondary and / or tertiary amine, of which tertiary amines, for example tri (C (-C -alkyl) amines, in particular trimethylamine, are particularly preferred.
  • the concentration of citral in the liquid phase is preferably 50 to 90% by weight, particularly preferably 60 to 80% by weight, that of the diluent 40 to 5% by weight, preferably 20 to 35%, that of the ammonia / amine 1 up to 15% by weight, preferably 1 to 8% by weight.
  • Hydrogen gas with a purity of at least 99.5% by volume is generally used as the hydrogen-containing gas. It is used in an at least stoichiometric amount, based on the carbonyl compound contained in the liquid phase, usually in an excess of 1 to 20%.
  • a commercially available suspension catalyst which is capable of preferentially hydrogenating carbon-carbon double bonds over carbon-oxygen double bonds can be used as the catalyst.
  • Catalysts which contain at least palladium as the active component are particularly suitable.
  • the catalyst can also contain other active components, such as zinc, cadium, platinum, silver or a rare earth metal.
  • the catalyst can be used in metallic and / or oxidic form.
  • the active components are preferably applied to a carrier material. Suitable carrier materials are, for example, Si0 2 , Ti0 2 , Zr0 2 , Al 2 0 3 or carbon such as graphite, carbon black or activated carbon. Activated carbon is preferred because of its easy suspendability.
  • the palladium content is preferably 0.1 to 10% by weight, in particular 0.5 to 7% by weight and particularly preferably 2 to 6% by weight, based on the total weight of the catalyst.
  • the suspended catalyst material can be introduced into the liquid phase and distributed therein using conventional techniques.
  • the device which inhibits the transport of the catalyst particles is usually built into a reactor which is arranged in such a way that the reaction mixture is forced through the device as it passes through the reactor, i.e. the internals usually fill the entire free cross-section of the reactor.
  • the internals preferably, but not necessarily, extend over the entire extent of the reactor in the direction of flow of the liquid phase.
  • reactors such as jet nozzle reactors, bubble columns or tube bundle reactors.
  • a vertically arranged bubble column or a tube bundle reactor in which the internals are accommodated in the individual tubes are particularly suitable.
  • the hydrogen-containing gas and the liquid phase are preferably passed through the reactor in cocurrent, preferably counter to the direction of gravity.
  • the gas phase is intimately mixed with the liquid phase, for example by means of an injector nozzle.
  • the empty tube velocity of the liquid phase is preferably more than 100 m 3 / m 2 h, in particular 100 to 250 m 3 / m 2 h, that of the gas phase more than 100 Nm 3 / m 2 h, in particular 100 to 250 Nm 3 / m 2 h , In order to achieve sufficiently high empty tube velocities, it is preferred to return partial streams of the gas and liquid phase that leave the reactor.
  • the catalyst particles suspended in the hydrogenation discharge are separated off by customary methods, for example by sedimentation, centrifugation, cake filtration or crossflow filtration.
  • the hydrogenation according to the invention can be carried out either continuously or batchwise, but it is preferably continuous.
  • FIG. 1 shows schematically a plant suitable for carrying out the process according to the invention with a reactor (bubble column) 1 with a packing 2, which inhibited the transport of the catalyst particles.
  • Liquid is introduced into the reactor via lines 3 and hydrogen gas via line 4.
  • the circulating gas 5 is mixed in with the mixing nozzle 6 with fresh gas and the suspension 11 circulated by the pump 14.
  • the reactor discharge is fed via line 7 into the separating vessel 8, in which the gas phase is separated off and discharged via line 9.
  • a partial stream of this gas quantity is withdrawn via line 10 and the remaining amount is fed via line 5 into the reactor.
  • the suspended catalyst remains in the reactor system in that it is retained by a crossflow filter 12 and only catalyst-free liquid phase emerges via line 13 and is removed.
  • the temperature in the reactor system can be set in a targeted manner via the heat exchanger 15.
  • FIG. 2 shows schematically a layer of a folded fabric. Packs which can be used according to the invention are obtained if several of these layers are arranged one above the other. Each layer comprises channels with a cross section in the form of an isosceles triangle with the leg length s, the base b and the height h.
  • FIG. 1 A system was used as shown in FIG. 1, which comprised a bubble column (1000 mm long, 27.3 mm in diameter) equipped with a Montz AI 1200 type tissue pack.
  • the package consisted of layers of a fabric of stainless steel wires, which were folded so that channels with a cross section in the shape of an isosceles triangle were formed, the leg length 3.1 mm, the base 5.1 mm and the height 1.8 mm was, corresponding to a hydraulic diameter of 1.62 mm.
  • a mixture of 70% by weight of citral, 27% by weight of methanol and 3% by weight of trimethylamine was used as the feed.
  • a palladium-carbon suspension catalyst which contained 5% palladium on activated carbon and an average particle size of about 50 was suspended in the feed ⁇ m.
  • the reaction was carried out continuously under a hydrogen pressure of 10 bar and a temperature of 80 ° C.
  • the liquid with the suspended catalyst and the gas were introduced into the packed reactor from below at an empty tube speed of 200 m3 / m2h.
  • the conversion was 97% with a selectivity of more than 90% for Citronellal and about 5% for Citronellol.
  • the catalyst load was 140 kg C itrai / (kg ⁇ at (Pd) * n ) ' ⁇ - e space-time yield 930 kg cit rai / (m 3 h).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

A method for the continuous hydrogenation of citral to give citronellal is disclosed, whereby a liquid phase, in which citral is dissolved and the particles of a catalyst, for the preferential hydrogenation of carbon-carbon double bonds before carbon-oxygen double bonds, are suspended, is fed through a device in the presence of a gas comprising hydrogen, said device preventing the transport of the catalyst particles.

Description

Verfahren zur kontinuierlichen Hydrierung von Citral zu CitronellalProcess for the continuous hydrogenation of citral to citronellal
Beschreibungdescription
Die vorliegende Erfindung betrifft ein Verfahren zur kontinuierlichen, selektiven Hydrierung von Citral zu Citronellal (Schema 1).The present invention relates to a process for the continuous, selective hydrogenation of citral to citronellal (Scheme 1).
Schema 1Scheme 1
Figure imgf000003_0001
Figure imgf000003_0001
Citral CitronellalCitral Citronellal
Citral und seine Hydrierungsprodukte finden als Riech- und Aromastoffe Anwendung.Citral and its hydrogenation products are used as fragrance and aroma substances.
Die GB 1 389 177, GB 1 476 818, GB 1 340 409 und die US 3,971,830 beschreiben Verfahren zur Herstellung von Citronellal durch Hydrierung von Citral an einem palladiumhaltigen Katalysator in Gegenwart von Borax bzw. Basen.GB 1 389 177, GB 1 476 818, GB 1 340 409 and US 3,971,830 describe processes for the preparation of citronellal by hydrogenating citral over a palladium-containing catalyst in the presence of borax or bases.
Katalytische Hydrierungen an heterogenen Katalysatoren werden vielfach unter Einsatz von Festbettreaktoren durchgeführt, um die Vorzüge einer kontinuierlichen Verfahrensführung zu erhalten. Allerdings müssen dafür speziell präparierte Katalysatoren herge- stellt und eingesetzt werden, die bei Verlust der Aktivität - oft bereits nach kürzeren Standzeiten - in aufwändiger Weise ausgetauscht oder regeneriert werden müssen, was in der Regel nicht nur mit der Abstellung der Hydrieranlage, sondern auch der nachfolgenden Aufarbeitungsstufen verbunden ist.Catalytic hydrogenations on heterogeneous catalysts are often carried out using fixed bed reactors in order to obtain the advantages of a continuous process. However, specially prepared catalysts have to be manufactured and used for this purpose, which have to be replaced or regenerated in a complex manner if activity is lost - often after a short period of idle time - which is usually not only the case when the hydrogenation system is switched off, but also afterwards Processing stages is connected.
Alternativ kann eine heterogen katalysierte Hydrierung in Form einer Suspensionsreaktion durchgeführt werden, wobei der Hydrierkatalysator durch Zufuhr mechanischer Energie z.B. in einem Rührkessel in einer Flüssigphase suspendiert wird, vgl. z.B. Ull anns Encyklopädie der technischen Chemie, 4. Aufl. Band 13, 1997, S. 138, Verlag Chemie Weinheim. Eine Erhöhung der Energiezufuhr über den zur Suspendierung erforderlichen Betrag führt zu keiner nennenswerten Verbesserung des Stofftransports der zu hydrierenden Moleküle an die Oberfläche der Katalysatorteilchen, da die erzielbare Relativgeschwindigkeit zwischen Katalysatorteilchen und Flüssigphase die Sedimentationsgeschwindigkeit nur unwesentlich übersteigt. Fließ- oder Wirbelbettreaktoren gestatten zwar höhere Relativgeschwindigkeiten, erfordern aber die Verwendung deutlich größerer Katalysatorteilchen, damit im Betrieb ein mehr oder weniger stark expandiertes Katalysatorbett vorliegt. Die geringere volumenbezogene Oberfläche größerer Katalysatorteilchen limitiert aber den Stoffumsatz und kompensiert so den Effekt der höheren Relativgeschwindigkeit.Alternatively, a heterogeneously catalyzed hydrogenation can be carried out in the form of a suspension reaction, the hydrogenation catalyst being suspended in a liquid phase by supplying mechanical energy, for example in a stirred tank, cf. eg Ull ann's Encyclopedia of Technical Chemistry, 4th ed. Volume 13, 1997, p. 138, Verlag Chemie Weinheim. An increase in the energy supply above the amount required for the suspension does not lead to any noteworthy improvement in the mass transport of the substances to be hydrogenated Molecules on the surface of the catalyst particles, since the achievable relative speed between the catalyst particles and the liquid phase only insignificantly exceeds the sedimentation speed. Fluidized or fluidized bed reactors allow higher relative speeds, but require the use of significantly larger catalyst particles so that a more or less strongly expanded catalyst bed is present during operation. However, the smaller volume-related surface area of larger catalyst particles limits the material conversion and thus compensates for the effect of the higher relative speed.
Die EP-A 798 039 offenbart ein Verfahren zur Durchführung von katalytischen Reaktionen in einem Reaktor, der eine Flüssigphase enthält, in der mindestens ein Katalysator suspendiert ist. Beschrieben wird die Hydrierung von Hydrodehydrolinalool zu Hy- drolinalool und weiter zu Tetrahydrolinalool . Hydrodehydrolinalool enthält lediglich eine Dreifachbindung als zu hydrierende funktioneile Gruppe, so dass der Fachmann dieser Schrift keine Anregung bezüglich einer selektiven Hydrierung entnommen hätte.EP-A 798 039 discloses a process for carrying out catalytic reactions in a reactor which contains a liquid phase in which at least one catalyst is suspended. The hydrogenation of hydrodehydrolinalool to hydrolinalool and further to tetrahydrolinalool is described. Hydrodehydrolinalool contains only a triple bond as the functional group to be hydrogenated, so that the person skilled in the art would not have taken any suggestion regarding selective hydrogenation.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Verfahren zur selektiven Hydrierung von Citral zu Citronellal anzugeben, das die Vorteile einer hohen Raum-Zeit-Ausbeute und eines einfachen Katalysatoraustausches vereint.The present invention has for its object to provide a process for the selective hydrogenation of citral to citronellal, which combines the advantages of a high space-time yield and a simple catalyst exchange.
Die Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren, bei dem man eine Flüssigphase, in der das Citral gelöst ist und in der Teilchen eines Katalysators suspendiert sind, der zur präfe- rentiellen Hydrierung von Kohlenstoff-Kohlenstoff-Doppelbindungen vor Kohlenstoff-Sauerstoff-Doppelbindungen fähig ist, in Gegenwart eines wasserstoffhaltigen Gases durch eine Vorrichtung führt, welche den Transport der Katalysatorteilchen hemmt.The object is achieved according to the invention by a process in which a liquid phase in which the citral is dissolved and suspended in the particles of a catalyst which is capable of preferential hydrogenation of carbon-carbon double bonds before carbon-oxygen double bonds , in the presence of a hydrogen-containing gas through a device which inhibits the transport of the catalyst particles.
Beim erfindungsgemäßen Verfahren wird eine höhere Relativge- schwindigkeit der Flüssigphase gegenüber den Katalysatorteilchen erzeugt, weil der Transport der Katalysatorteilchen durch geeignete Mittel, wie Einbauten in einem Reaktor, gehemmt wird, d.h. die Partikel werden gegenüber der umgebenden Flüssigkeit stärker zurückgehalten. In Verbindung mit der hohen volumenbezogenen Oberfläche der suspendierten Partikel werden im Ergebnis hohe Raum-Zeit-Ausbeuten erzielt.In the process according to the invention, a higher relative speed of the liquid phase compared to the catalyst particles is generated because the transport of the catalyst particles is inhibited by suitable means, such as internals in a reactor, i.e. the particles are held back more strongly by the surrounding liquid. In conjunction with the high volume-related surface area of the suspended particles, high space-time yields are achieved as a result.
Eine geeignete Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens ist in der EP-A 798 039 beschrieben. Die den Transport der Katalysatorteilchen hemmende Vorrichtung weist vorzugsweise Öffnungen oder Kanälen auf, deren hydraulischer Durchmesser das 2- bis 2000-fache, insbesondere das 5- bis 500-fache, besonders bevorzugt das 5- bis 100-fache des mittleren Durchmessers der Katalysatorteilchen beträgt.A suitable device for carrying out the method according to the invention is described in EP-A 798 039. The device which inhibits the transport of the catalyst particles preferably has openings or channels whose hydraulic diameter is 2 to 2000 times, in particular 5 to 500 times, particularly preferably 5 to 100 times the average diameter of the catalyst particles.
Der hydraulische Durchmesser ist eine dem Fachmann geläufige Kenngröße zur Beschreibung des Äquivalentdurchmessers nichtkreisrunder Kanalstrukturen. Der hydraulische Durchmesser einer Öffnung ist als Quotient des 4-fachen Querschnitts der Öffnung und deren Umfang definiert. Bei Kanälen mit einem Querschnitt in Gestalt eines gleichschenkeligen Dreiecks lässt sich der hydraulische Durchmesser alsThe hydraulic diameter is a parameter familiar to the person skilled in the art for describing the equivalent diameter of non-circular channel structures. The hydraulic diameter of an opening is defined as the quotient of 4 times the cross-section of the opening and its circumference. For channels with a cross section in the form of an isosceles triangle, the hydraulic diameter can be as
2bh b + 2s beschreiben, worin b für die Basis, h für die Höhe und s für die Schenkellänge des Dreiecks steht.2bh b + 2s describe, where b stands for the base, h for the height and s for the leg length of the triangle.
Die Öffnungen oder Kanäle geeigneter Vorrichtungen weisen im Allgemeinen einen hydraulischen Durchmesser von 0,5 bis 20 mm, vorzugsweise 1 bis 10 mm, besonders bevorzugt 1 bis 3 mm, auf.The openings or channels of suitable devices generally have a hydraulic diameter of 0.5 to 20 mm, preferably 1 to 10 mm, particularly preferably 1 to 3 mm.
Üblicherweise verwendet man Katalysatorteilchen eines mittleren Durchmessers von 0,0001 bis 2 mm, bevorzugt von 0,001 bis 1 mm, besonders bevorzugt von 0,005 bis 0,1 mm.Typically, catalyst particles with an average diameter of 0.0001 to 2 mm, preferably 0.001 to 1 mm, particularly preferably 0.005 to 0.1 mm are used.
Die den Transport der Katalysatorteilchen hemmende Vorrichtung kann aus einer Schüttung, einem Gestrick, einer offenzelligenThe device which inhibits the transport of the catalyst particles can consist of a bed, a knitted fabric, or an open-celled one
Schaumstruktur, vorzugsweise aus Kunststoff z.B. Polyurethan oder Melaminharz, oder Keramik, oder einem Packungselement, wie es grundsätzlich, d.h. seiner geometrischen Form nach, bereits aus der Destillations- und Extraktionstechnik bekannt ist, bestehen. Für Zwecke der vorliegenden Erfindung haben die Packungen jedoch grundsätzlich einen wesentlich, regelmäßig um den Faktor 2 bis 10 kleineren hydraulischen Durchmesser als vergleichbare Einbauten im Bereich der Destillations- und Extraktionstechnik.Foam structure, preferably made of plastic e.g. Polyurethane or melamine resin, or ceramic, or a packing element as is basically, i.e. its geometrical shape, already known from the distillation and extraction technology, exist. For the purposes of the present invention, however, the packs generally have a hydraulic diameter which is smaller by a factor of 2 to 10 than that of comparable internals in the area of distillation and extraction technology.
Als Packungselemente eignen sich insbesondere Metallgewebepackungen bzw. Drahtgewebepackungen, z.B. der Bauart Montz A3, Sulzer BX, DX und EX. Anstelle von Metallgewebepackungen können auch Packungen aus anderen gewebten, gewirkten oder gefilzten Materialien verwendet werden. Weiterhin eignen sich Packungen ebener oder gewellter Bleche, bevorzugt ohne Perforation oder andere größere Öffnungen, beispielsweise entsprechend den Bauarten Montz Bl oder Sulzer Mellapak. Vorteilhaft sind auch Packungen aus Streckmetall, wie z.B. Packungen des Typs Montz BSH. Entscheidend für die Eignung einer Packung im Rahmen der vorliegenden Erfindung ist nicht deren Geometrie, sondern die für die Stromführung entstehenden Öffnungsgrößen bzw. Kanalbreiten in der Packung.Metal mesh packs or wire mesh packs, for example of the type Montz A3, Sulzer BX, DX and EX, are particularly suitable as packing elements. Instead of metal mesh packs, packs made of other woven, knitted or felted materials can also be used. Packs of flat or corrugated metal sheets are also suitable, preferably without perforation or other larger openings, for example in accordance with the Montz Bl or Sulzer Mellapak types. Packings made of are also advantageous Expanded metal, such as packs of the type Montz BSH. What is decisive for the suitability of a package in the context of the present invention is not its geometry, but rather the opening sizes or channel widths in the package which arise for the current conduction.
In einer bevorzugten Ausführungsform weisen die der Flüssigphase zugewandten Oberflächen der Vorrichtung eine Rauhigkeit im Bereich des 0,1 bis 10-fachen, vorzugsweise des 0,5- bis 5-fachen, des mittleren Durchmessers der Katalysatorteilchen auf. Bevorzugt sind Materialien, deren Oberflächen einen Mittelrauwert Ra (bestimmt nach DIN 4768/1) von 0,001 bis 0,01 mm aufweisen. Eine entsprechende Oberflächenrauhigkeit kann bei Verwendung von Drahtgewebepackungen aus Edelstahl durch thermische Behandlung in Gegenwart von Sauerstoff erreicht werden, z.B. indem man das Ge- webe an der Luft bei einer Temperatur von etwa 800 °C tempert.In a preferred embodiment, the surfaces of the device facing the liquid phase have a roughness in the range from 0.1 to 10 times, preferably from 0.5 to 5 times, the average diameter of the catalyst particles. Materials are preferred whose surfaces have a mean roughness value R a (determined according to DIN 4768/1) of 0.001 to 0.01 mm. A corresponding surface roughness can be achieved when using wire mesh packings made of stainless steel by thermal treatment in the presence of oxygen, for example by tempering the tissue in air at a temperature of about 800 ° C.
Das erfindungsgemäße Verfahren erfolgt im Allgemeinen bei einem Druck zwischen 1 und 100 bar, bevorzugt 1 und 60 bar, besonders bevorzugt 1 und 50 bar. Die Reaktionstemperaturen liegen übli- cherweise zwischen 40 und 120°C, bevorzugt zwischen 60 und 100°C, besonders bevorzugt zwischen 70 und 90°C.The process according to the invention is generally carried out at a pressure between 1 and 100 bar, preferably 1 and 60 bar, particularly preferably 1 and 50 bar. The reaction temperatures are usually between 40 and 120 ° C, preferably between 60 and 100 ° C, particularly preferably between 70 and 90 ° C.
Vorzugsweise umfasst die Flüssigphase neben Citral ein inertes Verdünnungsmittel, insbesondere ein Ci-Cβ-Alkanol, besonders be- vorzugt ein Cι-C4-Alkanol, wie insbesondere Methanol. Weiter umfasst die Flüssigphase vorzugsweise außerdem Ammoniak, ein primäres, sekundäres und/oder tertiäres Amin, wovon tertiäre Amine, z.B. Tri(Cχ-C -alkyl) amine, insbesondere Trimethylamin, besonders bevorzugt sind. Die Konzentration an Citral in der Flüssigphase beträgt bevorzugt 50 bis 90 Gew.-%, besonders bevorzugt 60 bis 80 Gew.-%, die des Verdünnungsmittels 40 bis 5 Gew.-%, bevorzugt 20 bis 35 %, die des Ammoniaks/Amins 1 bis 15 Gew.-%, bevorzugt 1 bis 8 Gew.-%.In addition to citral, the liquid phase preferably comprises an inert diluent, in particular a C 1 -C 6 -alkanol, particularly preferably a C 1 -C 4 -alkanol, such as, in particular, methanol. The liquid phase further preferably comprises ammonia, a primary, secondary and / or tertiary amine, of which tertiary amines, for example tri (C (-C -alkyl) amines, in particular trimethylamine, are particularly preferred. The concentration of citral in the liquid phase is preferably 50 to 90% by weight, particularly preferably 60 to 80% by weight, that of the diluent 40 to 5% by weight, preferably 20 to 35%, that of the ammonia / amine 1 up to 15% by weight, preferably 1 to 8% by weight.
Als wasserstoffhaltiges Gas verwendet man in der Regel Wasserstoffgas mit einer Reinheit von wenigstens 99,5 Vol.-%. Es wird in wenigstens stöchiometrischer Menge, bezogen auf die in der Flüssigphase enthaltene Carbonylverbindung eingesetzt, meist in einem Überschuß von 1 bis 20 %.Hydrogen gas with a purity of at least 99.5% by volume is generally used as the hydrogen-containing gas. It is used in an at least stoichiometric amount, based on the carbonyl compound contained in the liquid phase, usually in an excess of 1 to 20%.
Als Katalysator kann ein handelsüblicher Suspensionskatalysator verwendet werden, der zur präferentiellen Hydrierung von Kohlenstoff-Kohlenstoff-Doppelbindungen vor Kohlenstoff-SauerStoff-Doppelbindungen fähig ist. Es eignen sich besonders solche Katalysa- toren, die als Aktivkomponente mindestens Palladium enthalten. Neben Palladium kann der Katalysator auch weitere Aktivkomponenten, wie beispielsweise Zink, Cadium, Platin, Silber oder ein Seltenerdmetall, enthalten. Der Katalysator kann in metallischer und/oder oxidischer Form eingesetzt werden. Vorzugsweise sind die Aktivkomponenten auf einem Trägermaterial aufgebracht. Als Trägermaterialien eignen sich beispielsweise Si02, Ti02, Zr02, Al203 oder Kohlenstoff wie Graphite, Ruße oder Aktivkohle. Aktivkohle ist aufgrund ihrer leichten Suspendierbarkeit bevorzugt. Der Gehalt an Palladium beträgt vorzugsweise 0,1 bis 10 Gew.-%, insbesondere 0,5 bis 7 Gew.-% und besonders bevorzugt 2 bis 6 Gew.-%, bezogen auf das Gesamtgewicht des Katalysators.A commercially available suspension catalyst which is capable of preferentially hydrogenating carbon-carbon double bonds over carbon-oxygen double bonds can be used as the catalyst. Catalysts which contain at least palladium as the active component are particularly suitable. In addition to palladium, the catalyst can also contain other active components, such as zinc, cadium, platinum, silver or a rare earth metal. The catalyst can be used in metallic and / or oxidic form. The active components are preferably applied to a carrier material. Suitable carrier materials are, for example, Si0 2 , Ti0 2 , Zr0 2 , Al 2 0 3 or carbon such as graphite, carbon black or activated carbon. Activated carbon is preferred because of its easy suspendability. The palladium content is preferably 0.1 to 10% by weight, in particular 0.5 to 7% by weight and particularly preferably 2 to 6% by weight, based on the total weight of the catalyst.
Das suspendierte Katalysatormaterial kann mit Hilfe gebräuchlicher Techniken in die Flüssigphase eingebracht und darin verteilt werden.The suspended catalyst material can be introduced into the liquid phase and distributed therein using conventional techniques.
Bei der den Transport der Katalysatorteilchen hemmenden Vorrichtung handelt es sich üblicherweise um Einbauten in einem Reaktor, die so angeordnet sind, dass das Reaktionsgemisch beim Passieren des Reaktors durch die Vorrichtung gezwängt wird, d.h. die Einbauten füllen in der Regel den gesamten freien Querschnitt des Reaktors. Die Einbauten erstrecken sich vorzugsweise, aber nicht notwendigerweise über die gesamte Ausdehnung des Reaktors in Strömungsrichtung der Flüssigphase.The device which inhibits the transport of the catalyst particles is usually built into a reactor which is arranged in such a way that the reaction mixture is forced through the device as it passes through the reactor, i.e. the internals usually fill the entire free cross-section of the reactor. The internals preferably, but not necessarily, extend over the entire extent of the reactor in the direction of flow of the liquid phase.
Es eignen sich verschiedene Reaktorformen, wie Strahldüsenreakto- ren, Blasensäulen oder Rohrbündelreaktoren. Davon sind eine vertikal angeordnete Blasensäule oder ein Rohrbündelreaktor, bei dem die Einbauten in den einzelnen Rohren untergebracht sind, besonders geeignet.Various types of reactor are suitable, such as jet nozzle reactors, bubble columns or tube bundle reactors. Of these, a vertically arranged bubble column or a tube bundle reactor in which the internals are accommodated in the individual tubes are particularly suitable.
Das wasserstoffhaltige Gas und die Flüssigphase werden bevorzugt im Gleichstrom, vorzugsweise entgegen der Richtung der Schwerkraft, durch den Reaktor geführt. Die Gasphase wird beispielsweise mittels einer Injektordüse innig mit der Flüssigphase durchmischt. Die Leerrohrgeschwindigkeit der Flüssigphase beträgt vorzugsweise mehr als 100 m3/m2h, insbesondere 100 bis 250 m3/m2h, die der Gasphase mehr als 100 Nm3/m2h, insbesondere 100 bis 250 Nm3/m2h. Um ausreichend hohe Leerrohrgeschwindigkeiten zu erzielen, ist es bevorzugt, Teilströme der Gas- und Flüssigphase, die den Reaktor verlassen, zurückzuführen.The hydrogen-containing gas and the liquid phase are preferably passed through the reactor in cocurrent, preferably counter to the direction of gravity. The gas phase is intimately mixed with the liquid phase, for example by means of an injector nozzle. The empty tube velocity of the liquid phase is preferably more than 100 m 3 / m 2 h, in particular 100 to 250 m 3 / m 2 h, that of the gas phase more than 100 Nm 3 / m 2 h, in particular 100 to 250 Nm 3 / m 2 h , In order to achieve sufficiently high empty tube velocities, it is preferred to return partial streams of the gas and liquid phase that leave the reactor.
Die im Hydrieraustrag suspendierten Katalysatorteilchen werden durch übliche Verfahren abgetrennt, z.B. durch Sedimentation, Zentrifugation, Kuchenfiltration oder Querstromfiltration. Die erfindungsgemäße Hydrierung kann sowohl kontinuierlich als auch diskontinuierlich erfolgen, bevorzugt verläuft sie jedoch kontinuierlich .The catalyst particles suspended in the hydrogenation discharge are separated off by customary methods, for example by sedimentation, centrifugation, cake filtration or crossflow filtration. The hydrogenation according to the invention can be carried out either continuously or batchwise, but it is preferably continuous.
Das erfindungsgemäße Verfahren wird durch die beigefügte Figur und das nachstehende Beispiel näher veranschaulicht.The method according to the invention is illustrated in more detail by the attached figure and the example below.
Figur 1 zeigt schematisch eine zur Durchführung des erfindungsgemäßen Verfahrens geeignete Anlage mit einem Reaktor (Blasensäule) 1 mit einer Packung 2, die den Transport der Katalysatorteilchen hemmte. In den Reaktor werden über die Leitungen 3 Flüssigkeit und über die Leitung 4 Wasserstoffgas eingeführt. Das Kreisgas 5 wird mittels der Mischdüse 6 mit Frischgas und der durch die Pumpe 14 im Kreis geführten Suspension 11 eingemischt. Der Reaktoraustrag wird über die Leitung 7 in das Abscheidegefäß 8 gefahren, in dem die Gasphase abgeschieden und über Leitung 9 abgeführt wird. Von dieser Gasmenge wird zur Begrenzung der Auf- pegelung von gasförmigen Verunreinigungen ein Teilstrom über die Leitung 10 entnommen und die verbleibende Restmenge über die Lei- tung 5 in den Reaktor geführt. Der suspendierte Katalysator verbleibt im Reaktorsystem, indem er über einen Querstromfilter 12 zurückgehalten und nur katalysatorfreie Flüssigphase über die Leitung 13 austritt und entnommen wird. Über den Wärmetauscher 15 kann die Temperatur im Reaktorsystem gezielt eingestellt werden.Figure 1 shows schematically a plant suitable for carrying out the process according to the invention with a reactor (bubble column) 1 with a packing 2, which inhibited the transport of the catalyst particles. Liquid is introduced into the reactor via lines 3 and hydrogen gas via line 4. The circulating gas 5 is mixed in with the mixing nozzle 6 with fresh gas and the suspension 11 circulated by the pump 14. The reactor discharge is fed via line 7 into the separating vessel 8, in which the gas phase is separated off and discharged via line 9. To limit the leveling of gaseous impurities, a partial stream of this gas quantity is withdrawn via line 10 and the remaining amount is fed via line 5 into the reactor. The suspended catalyst remains in the reactor system in that it is retained by a crossflow filter 12 and only catalyst-free liquid phase emerges via line 13 and is removed. The temperature in the reactor system can be set in a targeted manner via the heat exchanger 15.
Figur 2 zeigt schematisch eine Lage eines gefalzten Gewebes. Erfindungsgemäß verwendbare Packungen werden erhalten, wenn mehrere dieser Lagen übereinander angeordnet werden. Jede Lage umfasst Kanäle mit einem Querschnitt in Gestalt eines gleichschenkeligen Dreiecks mit der Schenkellänge s, der Basis b und der Höhe h.Figure 2 shows schematically a layer of a folded fabric. Packs which can be used according to the invention are obtained if several of these layers are arranged one above the other. Each layer comprises channels with a cross section in the form of an isosceles triangle with the leg length s, the base b and the height h.
Beispiel 1example 1
Man verwendete eine Anlage wie in Fig. 1 dargestellt, die eine mit einer Gewebepackung vom Typ Montz AI 1200 bestückte Blasensäule (1000 mm Länge, 27,3 mm Durchmesser) umfasste. Die Packung bestand aus übereinander angeordneten Lagen eines Gewebe von Edelstahldrähten, das so gefalzt war, dass Kanäle mit einem Querschnitt in Gestalt eines gleichschenkeligen Dreiecks gebildet werden, wobei die Schenkellänge 3,1 mm, die Basis 5,1 mm und die Höhe 1,8 mm betrug, entsprechend einem hydraulischen Durchmesser von 1,62 mm.A system was used as shown in FIG. 1, which comprised a bubble column (1000 mm long, 27.3 mm in diameter) equipped with a Montz AI 1200 type tissue pack. The package consisted of layers of a fabric of stainless steel wires, which were folded so that channels with a cross section in the shape of an isosceles triangle were formed, the leg length 3.1 mm, the base 5.1 mm and the height 1.8 mm was, corresponding to a hydraulic diameter of 1.62 mm.
Als Zulauf diente ein Gemisch von 70 Gew.-% Citral, 27 Gew.-% Me- thanol und 3 Gew.-% Trimethylamin. In dem Zulauf wurde ein Palladium-Kohle-Suspensionskatalysator suspendiert, der 5 % Palladium auf Aktivkohle enthielt und eine mittlere Korngröße von etwa 50 μm aufwies. Die Reaktion erfolgte kontinuierlich unter einem Wasserstoffdruck von 10 bar und einer Temperatur von 80°C. Die Flüssigkeit mit dem suspendierten Katalysator und das Gas wurden mit einer Leerrohrgeschwindigkeit von 200 m3/m2h von unten in den gepackten Reaktor eingebracht.A mixture of 70% by weight of citral, 27% by weight of methanol and 3% by weight of trimethylamine was used as the feed. A palladium-carbon suspension catalyst which contained 5% palladium on activated carbon and an average particle size of about 50 was suspended in the feed μm. The reaction was carried out continuously under a hydrogen pressure of 10 bar and a temperature of 80 ° C. The liquid with the suspended catalyst and the gas were introduced into the packed reactor from below at an empty tube speed of 200 m3 / m2h.
Der Umsatz betrug 97 % bei einer Selektivität von mehr als 90 % für Citronellal und etwa 5% für Citronellol. Die Katalysatorbelastung betrug 140 kgCitrai/(kgκat(Pd)*n) ' ά -e Raumzeitausbeute 930 kgcitrai/(m3h). The conversion was 97% with a selectivity of more than 90% for Citronellal and about 5% for Citronellol. The catalyst load was 140 kg C itrai / (kgκat (Pd) * n ) ' ά - e space-time yield 930 kg cit rai / (m 3 h).

Claims

Patentansprüche claims
1. Verfahren zur kontinuierlichen Hydrierung von Citral zu Ci- tronellal, bei dem man eine Flüssigphase, in der das Citral gelöst ist und in der Teilchen eines Katalysators suspendiert sind, der zur präferentiellen Hydrierung von Kohlenstoff-Kohlenstoff-Doppelbindungen vor Kohlenstoff-Sauerstoff-Doppelbindungen fähig ist, in Gegenwart eines Wasserstoffhaltigen Gases durch eine Vorrichtung führt, welche den Transport der Katalysatorteilchen hemmt.1. Process for the continuous hydrogenation of citral to citronellal, in which a liquid phase in which the citral is dissolved and suspended in the particles of a catalyst is used for the preferential hydrogenation of carbon-carbon double bonds over carbon-oxygen double bonds capable, in the presence of a hydrogen-containing gas, through a device which inhibits the transport of the catalyst particles.
2. Verfahren nach Anspruch 1 , wobei die Aktivkomponente des Katalysators Palladium enthält.2. The method according to claim 1, wherein the active component of the catalyst contains palladium.
3. Verfahren nach Anspruch 1 oder 2 , wobei die den Transport der Katalysatorteilchen hemmende Vorrichtung Öffnungen oder Kanälen aufweist, deren hydraulischer Durchmesser das 2- bis 2000-fache des mittleren Durchmessers der Katalysatorteilchen beträgt.3. The method according to claim 1 or 2, wherein the device inhibiting the transport of the catalyst particles has openings or channels whose hydraulic diameter is 2 to 2000 times the average diameter of the catalyst particles.
4. Verfahren nach einem der vorhergehenden Ansprüche, wobei man Katalysatorteilchen eines mittleren Durchmessers von 0,0001 bis 2 mm verwendet.4. The method according to any one of the preceding claims, wherein catalyst particles having an average diameter of 0.0001 to 2 mm are used.
5. Verfahren nach einem der vorhergehenden Ansprüche, wobei man als die den Transport der Katalysatorteilchen hemmende Vorrichtung eine Schüttung, ein Gestrick, eine offenzellige Schaumstruktur oder ein Packungselement verwendet.5. The method according to any one of the preceding claims, wherein a bed, a knitted fabric, an open-cell foam structure or a packing element is used as the device which inhibits the transport of the catalyst particles.
6. Verfahren nach einem der vorhergehenden Ansprüche, wobei man die Flüssigphase und das wasserstoffhaltige Gas mit einer Leerrohrgeschwindigkeit von mehr als 100 m3/m2h durch die den Transport der Katalysatorteilchen hemmende Vorrichtung führt.6. The method according to any one of the preceding claims, wherein the liquid phase and the hydrogen-containing gas at an empty tube speed of more than 100 m 3 / m 2 h through the device inhibiting the transport of the catalyst particles.
7. Verfahren nach einem der vorhergehenden Ansprüche, wobei die der Flüssigphase zugewandten Oberflächen der Vorrichtung eine Rauhigkeit im Bereich des 0,1 bis 10-fachen des mittleren Durchmessers der Katalysatorteilchen aufweisen.7. The method according to any one of the preceding claims, wherein the surfaces of the device facing the liquid phase have a roughness in the range of 0.1 to 10 times the average diameter of the catalyst particles.
8. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Flüssigphase außerdem ein inertes Verdünnungsmittel umfasst. 8. The method according to any one of the preceding claims, wherein the liquid phase further comprises an inert diluent.
9. Verfahren nach Anspruch 8, wobei es sich bei dem Verdünnungsmittel um ein Ci-Cβ-Alkanol handelt.9. The method according to claim 8, wherein the diluent is a Ci-Cβ-alkanol.
10. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Flüssigphase außerdem Ammoniak, ein primäres, sekundäres und/ oder tertiäres Amin umfasst.10. The method according to any one of the preceding claims, wherein the liquid phase further comprises ammonia, a primary, secondary and / or tertiary amine.
11. Verfahren einem der Ansprüche 8 bis 10, wobei die Konzentration von Citral in der Flüssigphase 50 bis 90 Gew.-% be- trägt.11. The method according to any one of claims 8 to 10, wherein the concentration of citral in the liquid phase is 50 to 90% by weight.
12. Verfahren nach einem der vorhergehenden Ansprüche, wobei man die Hydrierung bei einer Temperatur von40 bis 120 °C und einem Druck von 1 bis 50 bar durchführt. 12. The method according to any one of the preceding claims, wherein the hydrogenation is carried out at a temperature of 40 to 120 ° C and a pressure of 1 to 50 bar.
PCT/EP2003/007601 2002-07-15 2003-07-14 Method for the continuous hydrogenation of citral to give citronellal WO2004007414A1 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006021822A1 (en) 2004-08-23 2006-03-02 Thalesnano Zrt. A cartridge reactor for a flow-type laboratory hydrogenation apparatus
DE102004047794A1 (en) * 2004-09-29 2006-04-06 Studiengesellschaft Kohle Mbh Process for the hydrogenation of α, β-unsaturated carbonyl compounds
WO2011067386A2 (en) 2009-12-04 2011-06-09 Basf Se Method for producing aliphatic aldehydes
US8318985B2 (en) 2007-11-30 2012-11-27 Basf Se Method for producing optically active, racemic menthol

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1476818A (en) * 1975-06-18 1977-06-16 Rhone Poulenc Ind Process for the semihydrogenation of citral and its homo logues to citronellal and its homologues
EP0798039A2 (en) * 1996-03-26 1997-10-01 Basf Aktiengesellschaft Method and reactor for carrying out the conversion of substances using catalysts suspended in liquids
EP0947493A1 (en) * 1998-04-02 1999-10-06 Basf Aktiengesellschaft Process for the selective liquid phase hydrogenation of alpha,beta-unsaturated carbonyl compounds

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1476818A (en) * 1975-06-18 1977-06-16 Rhone Poulenc Ind Process for the semihydrogenation of citral and its homo logues to citronellal and its homologues
EP0798039A2 (en) * 1996-03-26 1997-10-01 Basf Aktiengesellschaft Method and reactor for carrying out the conversion of substances using catalysts suspended in liquids
EP0947493A1 (en) * 1998-04-02 1999-10-06 Basf Aktiengesellschaft Process for the selective liquid phase hydrogenation of alpha,beta-unsaturated carbonyl compounds

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006021822A1 (en) 2004-08-23 2006-03-02 Thalesnano Zrt. A cartridge reactor for a flow-type laboratory hydrogenation apparatus
DE102004047794A1 (en) * 2004-09-29 2006-04-06 Studiengesellschaft Kohle Mbh Process for the hydrogenation of α, β-unsaturated carbonyl compounds
US8318985B2 (en) 2007-11-30 2012-11-27 Basf Se Method for producing optically active, racemic menthol
US9988331B2 (en) 2007-11-30 2018-06-05 Basf Se Method for producing optically active, racemic menthol
WO2011067386A2 (en) 2009-12-04 2011-06-09 Basf Se Method for producing aliphatic aldehydes

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